TY  - JOUR
A1  - Kreuzer, Lucas
A1  - Widmann, Tobias
A1  - Geiger, Christina
A1  - Wang, Peixi
A1  - Vagias, Apostolos N.
A1  - Heger, Julian Eliah
A1  - Haese, Martin
A1  - Hildebrand, Viet
A1  - Laschewsky, André
A1  - Papadakis, Christine M.
A1  - Müller-Buschbaum, Peter
T1  - Salt-dependent phase transition behavior of doubly thermoresponsive poly(sulfobetaine)-based diblock copolymer thin films
JF  - Langmuir : the ACS journal of surfaces and colloids / American Chemical Society
N2  - The water vapor-induced swelling, as well as subsequent phase-transition kinetics, of thin films of a diblock copolymer (DBC) loaded with different amounts of the salt NaBr, is investigated in situ. In dilute aqueous solution, the DBC features an orthogonally thermoresponsive behavior. It consists of a zwitterionic poly(sulfobetaine) block, namely, poly(4-(N-(3'-methacrylamidopropyl)-N, N-dimethylammonio) butane-1-sulfonate) (PSBP), showing an upper critical solution temperature, and a nonionic block, namely, poly(N-isopropylmethacrylamide) (PNIPMAM), exhibiting a lower critical solution temperature. The swelling kinetics in D2O vapor at 15 degrees C and the phase transition kinetics upon heating the swollen film to 60 degrees C and cooling back to 15 degrees C are followed with simultaneous time-of-flight neutron reflectometry and spectral reflectance measurements. These are complemented by Fourier transform infrared spectroscopy. The collapse temperature of PNIPMAM and the swelling temperature of PSBP are found at lower temperatures than in aqueous solution, which is attributed to the high polymer concentration in the thin-film geometry. Upon inclusion of sub-stoichiometric amounts (relative to the monomer units) of NaBr in the films, the water incorporation is significantly increased. This increase is mainly attributed to a salting-in effect on the zwitterionic PSBP block. Whereas the addition of NaBr notably shifts the swelling temperature of PSBP to lower temperatures, the collapse temperature of PNIPMAM remains unaffected by the presence of salt in the films.
Y1  - 2021
U6  - https://doi.org/10.1021/acs.langmuir.1c01342
SN  - 0743-7463
SN  - 1520-5827
VL  - 37
IS  - 30
SP  - 9179
EP  - 9191
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Pessanha, Tatiana
A1  - Paschoalino, Waldemir J.
A1  - Deroco, Patricia B.
A1  - Kogikoski Junior, Sergio
A1  - Moraes, Ana C. M. de
A1  - Carvalho Castro de Silva, Cecilia de
A1  - Kubota, Lauro T.
T1  - Interfacial capacitance of graphene oxide films electrodes
BT  - Fundamental studies on electrolytes interface aiming (bio)sensing applications
JF  - Electroanalysis : an internatinal journal devoted to electroanalysis, sensors and bioelectronic devices
N2  - The understanding of bidimensional materials dynamics and its electrolyte interface equilibrium, such as graphene oxide (GO), is critical for the development of a capacitive biosensing platform. The interfacial capacitance (C-i) of graphene-based materials may be tuned by experimental conditions such as pH optimization and cation size playing key roles at the enhancement of their capacitive properties allowing their application as novel capacitive biosensors. Here we reported a systematic study of C-i of multilayer GO films in different aqueous electrolytes employing electrochemical impedance spectroscopy for the application in a capacitive detection system. We demonstrated that the presence of ionizable oxygen-containing functional groups within multilayer GO film favors the interactions and the accumulation of cations in the structure of the electrodes enhancing the GO C-i in aqueous solutions, where at pH 7.0 (the best condition) the C-i was 340 mu F mg(-1) at -0.01 V vs Ag/AgCl. We also established that the hydrated cation radius affects the mobility and interaction with GO functional groups and it plays a critical role in the Ci, as demonstrated in the presence of different cations Na+=640 mu F mg(-1), Li+=575 mu F mg(-1) and TMA(+)=477 mu F mg(-1). As a proof-of-concept, the capacitive behaviour of GO was explored as biosensing platform for standard streptavidin-biotin systems. For this system, the C-i varied linearly with the log of the concentration of the targeting analyte in the range from 10 pg mL(-1) to 100 ng mL(-1), showing the promising applicability of capacitive GO based sensors for label-free biosensing.
KW  - Interfacial capacitance
KW  - Graphene oxide
KW  - Functional groups
KW  - Electrochemical impedance
KW  - Graphene derivates
Y1  - 2021
U6  - https://doi.org/10.1002/elan.202100220
SN  - 1521-4109
VL  - 34
IS  - 4
SP  - 692
EP  - 700
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - THES
A1  - Savatieiev, Oleksandr
T1  - Carbon nitride semiconductors: properties and application as photocatalysts in organic synthesis
N2  - Graphitic carbon nitrides (g-CNs) are represented by melon-type g-CN, poly(heptazine imides) (PHIs), triazine-based g-CN and poly(triazine imide) with intercalated LiCl (PTI/Li+Cl‒). These materials are composed of sp2-hybridized carbon and nitrogen atoms; C:N ratio is close to 3:4; the building unit is 1,3,5-triazine or tri-s-triazine; the building units are interconnected covalently via sp2-hybridized nitrogen atoms or NH-moieties; the layers are assembled into a stack via weak van der Waals forces as in graphite. Due to medium band gap (~2.7 eV) g-CNs, such as melon-type g-CN and PHIs, are excited by photons with wavelength ≤ 460 nm. Since 2009 g-CNs have been actively studied as photocatalysts in evolution of hydrogen and oxygen – two half-reactions of full water splitting, by employing corresponding sacrificial agents. At the same time application of g-CNs as photocatalysts in organic synthesis has been remaining limited to few reactions only. Cumulative Habilitation summarizes research work conducted by the group ‘Innovative Heterogeneous Photocatalysis’ between 2017-2023 in the field of carbon nitride organic photocatalysis, which is led by Dr. Oleksandr Savatieiev.
g-CN photocatalysts activate molecules, i.e. generate their more reactive open-shell intermediates, via three modes: i) Photoinduced electron transfer (PET); ii) Excited state proton-coupled electron transfer (ES-PCET) or direct hydrogen atom transfer (dHAT); iii) Energy transfer (EnT). The scope of reactions that proceed via oxidative PET, i.e. one-electron oxidation of a substrate to the corresponding radical cation, are represented by synthesis of sulfonylchlorides from S-acetylthiophenols. The scope of reactions that proceed via reductive PET, i.e. one-electron reduction of a substrate to the corresponding radical anion, are represented by synthesis of γ,γ-dichloroketones from the enones and chloroform.
Due to abundance of sp2-hybridized nitrogen atoms in the structure of g-CN materials, they are able to cleave X-H bonds in organic molecules and store temporary hydrogen atom. ES-PCET or dHAT mode of organic molecules activation to the corresponding radicals is implemented for substrates featuring relatively acidic X-H bonds and those that are characterized by low bond dissociation energy, such as C-H bond next to the heteroelements. On the other hand, reductively quenched g-CN carrying hydrogen atom reduces a carbonyl compound to the ketyl radical via PCET that is thermodynamically more favorable pathway compared to the electron transfer. The scope of these reactions is represented by cyclodimerization of α,β-unsaturated ketones to cyclopentanoles.
g-CN excited state demonstrates complex dynamics with the initial formation of singlet excited state, which upon intersystem crossing produces triplet excited state that is characterized by the lifetime > 2 μs. Due to long lifetime, g-CN activate organic molecules via EnT. For example, g-CN sensitizes singlet oxygen, which is the key intermediate in the dehydrogenation of aldoximes to nitrileoxides. The transient nitrileoxide undergoes [3+2]-cycloaddition to nitriles and gives oxadiazoles-1,2,4.
PET, ES-PCET and EnT are fundamental phenomena that are applied beyond organic photocatalysis. Hybrid composite is formed by combining conductive polymers, such as poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) with potassium poly(heptazine imide) (K-PHI). Upon PET, K-PHI modulated population of polarons and therefore conductivity of PEDOT:PSS. The initial state of PEDOT:PSS is recovered upon material exposure to O2. K-PHI:PEDOT:PSS may be applied in O2 sensing.
In the presence of electron donors, such as tertiary amines and alcohols, and irradiation with light, K-PHI undergoes photocharging – the g-CN material accumulates electrons and charge-compensating cations. Such photocharged state is stable under anaerobic conditions for weeks, but at the same time it is a strong reductant. This feature allows decoupling in time light harvesting and energy storage in the form of electron-proton couples from utilization in organic synthesis. The photocharged state of K-PHI reduces nitrobenzene to aniline, and enables dimerization of α,β-unsaturated ketones to hexadienones in dark.
N2  - Graphitische Kohlenstoffnitride (g-CNs) werden durch g-CN vom Melonen-Typ, Poly(heptazinimide) (PHIs), g-CN auf Triazinbasis und Poly(triazinimid) mit interkaliertem LiCl (PTI/Li+Cl-) repräsentiert. Diese Materialien bestehen aus sp2-hybridisierten Kohlenstoff- und Stickstoffatomen; das C:N-Verhältnis liegt nahe bei 3:4; das Grundgerüst ist 1,3,5-Triazin oder Tri-s-Triazin; die Grundgerüste sind kovalent über sp2-hybridisierte Stickstoffatome oder NH-Moleküle miteinander verbunden; die Schichten werden über schwache van-der-Waals-Kräfte wie in Graphit zu einem Stapel zusammengefügt. Aufgrund der mittleren Bandlücke (~2,7 eV) werden g-CNs, wie z. B. g-CN vom Melonen-Typ und PHIs, durch Photonen mit einer Wellenlänge ≤ 460 nm angeregt. Seit 2009 werden g-CNs aktiv als Photokatalysatoren für die Entwicklung von Wasserstoff und Sauerstoff - zwei Halbreaktionen der vollständigen Wasserspaltung - untersucht, indem entsprechende Opferstoffe eingesetzt werden. Gleichzeitig ist die Anwendung von g-CNs als Photokatalysatoren in der organischen Synthese auf wenige Reaktionen beschränkt geblieben. Die kumulative Habilitation fasst die Forschungsarbeiten zusammen, die von der Gruppe "Innovative heterogene Photokatalyse" zwischen 2017 und 2023 auf dem Gebiet der organischen Photokatalyse mit Kohlenstoffnitrid durchgeführt wurden, die von Dr. Oleksandr Savatieiev geleitet wird.
g-CN-Photokatalysatoren aktivieren Moleküle, d. h. sie erzeugen ihre reaktiveren Zwischenprodukte mit offener Schale über drei Modi: i) photoinduzierter Elektronentransfer (PET); ii) protonengekoppelter Elektronentransfer im angeregten Zustand (ES-PCET) oder direkter Wasserstoffatomtransfer (dHAT); iii) Energietransfer (EnT). Der Bereich der Reaktionen, die über oxidativen PET ablaufen, d. h. die Ein-Elektronen-Oxidation eines Substrats zum entsprechenden Radikalkation, wird durch die Synthese von Sulfonylchloriden aus S-Acetylthiophenolen dargestellt. Der Bereich der Reaktionen, die über reduktive PET ablaufen, d. h. Reduktion eines Substrats mit einem Elektron zum entsprechenden radikalischen Anion, wird durch die Synthese von γ,γ-Dichloroketonen aus Enonen und Chloroform repräsentiert.
Aufgrund der zahlreichen sp2-hybridisierten Stickstoffatome in der Struktur der g-CN-Materialien können sie X-H-Bindungen in organischen Molekülen spalten und temporäre Wasserstoffatome speichern. Der ES-PCET- oder dHAT-Modus der Aktivierung organischer Moleküle zu den entsprechenden Radikalen wird bei Substraten mit relativ sauren X-H-Bindungen und solchen, die sich durch eine niedrige Bindungsdissoziationsenergie auszeichnen, wie z. B. die C-H-Bindung neben den Heteroelementen, durchgeführt. Andererseits reduziert reduktiv gequenchtes g-CN, das ein Wasserstoffatom trägt, eine Carbonylverbindung über PCET zum Ketylradikal, was im Vergleich zum Elektronentransfer der thermodynamisch günstigere Weg ist. Der Umfang dieser Reaktionen wird durch die Cyclodimerisierung von α,β-ungesättigten Ketonen zu Cyclopentanolen dargestellt.
Der angeregte Zustand von g-CN zeigt eine komplexe Dynamik mit der anfänglichen Bildung eines angeregten Singulett-Zustands, der beim Übergang zwischen den Systemen einen angeregten Triplett-Zustand erzeugt, der durch eine Lebensdauer von > 2 μs gekennzeichnet ist. Aufgrund der langen Lebensdauer aktivieren g-CN organische Moleküle über EnT. So sensibilisiert g-CN beispielsweise Singulett-Sauerstoff, der das wichtigste Zwischenprodukt bei der Dehydrierung von Aldoximen zu Nitriloxiden ist. Das transiente Nitriloxid unterliegt einer [3+2]-Cycloaddition zu Nitrilen und ergibt Oxadiazole-1,2,4.
PET, ES-PCET und EnT sind grundlegende Phänomene, die über die organische Photokatalyse hinaus Anwendung finden. Hybridkomposit wird durch die Kombination von leitfähigen Polymeren wie Poly(3,4-ethylendioxythiophen)polystyrolsulfonat (PEDOT:PSS) mit Kaliumpoly(heptazinimid) (K-PHI) gebildet. Nach PET modulierte K-PHI die Population der Polaronen und damit die Leitfähigkeit von PEDOT:PSS. Der Ausgangszustand von PEDOT:PSS wird wiederhergestellt, wenn das Material O2 ausgesetzt wird. K-PHI:PEDOT:PSS kann für die O2-Sensorik verwendet werden.
In Gegenwart von Elektronendonatoren, wie tertiären Aminen und Alkoholen, und bei Lichteinstrahlung wird K-PHI photogeladen - das g-CN-Material sammelt Elektronen und ladungsausgleichende Kationen an. Dieser photogeladene Zustand ist unter anaeroben Bedingungen wochenlang stabil, gleichzeitig ist er aber ein starkes Reduktionsmittel. Diese Eigenschaft ermöglicht die zeitliche Entkopplung von Lichtsammlung und Energiespeicherung in Form von Elektron-Protonen-Paaren von der Nutzung in der organischen Synthese. Der photogeladene Zustand von K-PHI reduziert Nitrobenzol zu Anilin und ermöglicht die Dimerisierung von α,β-ungesättigten Ketonen zu Hexadienonen im Dunkeln.
KW  - carbon nitride
KW  - photocatalysis
KW  - photochemistry
KW  - photocharging
KW  - organic synthesis
Y1  - 2023
ER  - 
TY  - GEN
A1  - Hechenbichler, Michelle
A1  - Laschewsky, Andre
A1  - Gradzielski, Michael
T1  - Poly(N,N-bis(2-methoxyethyl)acrylamide), a thermoresponsive non-ionic polymer combining the amide and the ethyleneglycolether motifs
T2  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Poly(N,N-bis(2-methoxyethyl)acrylamide) (PbMOEAm) featuring two classical chemical motifs from non-ionic water-soluble polymers, namely, the amide and ethyleneglycolether moieties, was synthesized by reversible addition fragmentation transfer (RAFT) polymerization. This tertiary polyacrylamide is thermoresponsive exhibiting a lower critical solution temperature (LCST)-type phase transition. A series of homo- and block copolymers with varying molar masses but low dispersities and different end groups were prepared. Their thermoresponsive behavior in aqueous solution was analyzed via turbidimetry and dynamic light scattering (DLS). The cloud points (CP) increased with increasing molar masses, converging to 46 degrees C for 1 wt% solutions. This rise is attributed to the polymers' hydrophobic end groups incorporated via the RAFT agents. When a surfactant-like strongly hydrophobic end group was attached using a functional RAFT agent, CP was lowered to 42 degrees C, i.e., closer to human body temperature. Also, the effect of added salts, in particular, the role of the Hofmeister series, on the phase transition of PbMOEAm was investigated, exemplified for the kosmotropic fluoride, intermediate chloride, and chaotropic thiocyanate anions. A pronounced shift of the cloud point of about 10 degrees C to lower or higher temperatures was observed for 0.2 M fluoride and thiocyanate, respectively. When PbMOEAm was attached to a long hydrophilic block of poly(N,N-dimethylacrylamide) (PDMAm), the cloud points of these block copolymers were strongly shifted towards higher temperatures. While no phase transition was observed for PDMAm-b-pbMOEAm with short thermoresponsive blocks, block copolymers with about equally sized PbMOEAm and PDMAm blocks underwent the coil-to-globule transition around 60 degrees C.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1345 
KW  - polyacrylamide
KW  - water-soluble polymers
KW  - responsive systems
KW  - lower
KW  - critical solution temperature
KW  - polymer amphiphile
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-598378
SN  - 0303-402X
SN  - 1435-1536
SN  - 1866-8372
VL  - 299
IS  - 2
PB  - Springer
CY  - Berlin; Heidelberg
ER  - 
TY  - THES
A1  - Hussein, Mahmoud
T1  - Solvent engineering for highly-efficiency lead-free perovskite solar cells
T1  - Lösungsmitteltechnik für hocheffiziente Zinn-Perowskit-Solarzellen
N2  - Global warming, driven primarily by the excessive emission of greenhouse gases such as carbon dioxide into the atmosphere, has led to severe and detrimental environmental impacts. Rising global temperatures have triggered a cascade of adverse effects, including melting glaciers and polar ice caps, more frequent and intense heat waves disrupted weather patterns, and the acidification of oceans. These changes adversely affect ecosystems, biodiversity, and human societies, threatening food security, water availability, and livelihoods. One promising solution to mitigate the harmful effects of global warming is the widespread adoption of solar cells, also known as photovoltaic cells. Solar cells harness sunlight to generate electricity without emitting greenhouse gases or other pollutants. By replacing fossil fuel-based energy sources, solar cells can significantly reduce CO2 emissions, a significant contributor to global warming. This transition to clean, renewable energy can help curb the increasing concentration of greenhouse gases in the atmosphere, thereby slowing down the rate of global temperature rise.
Solar energy’s positive impact extends beyond emission reduction. As solar panels become more efficient and affordable, they empower individuals, communities, and even entire nations to generate electricity and become less dependent on fossil fuels. This decentralized energy generation can enhance resilience in the face of climate-related challenges. Moreover, implementing solar cells creates green jobs and stimulates technological innovation, further promoting sustainable economic growth. As solar technology advances, its integration with energy storage systems and smart grids can ensure a stable and reliable energy supply, reducing the need for backup fossil fuel power plants that exacerbate environmental degradation.
The market-dominant solar cell technology is silicon-based, highly matured technology with a highly systematic production procedure. However, it suffers from several drawbacks, such as: 1) Cost: still relatively high due to high energy consumption due to the need to melt and purify silicon, and the use of silver as an electrode, which hinders their widespread availability, especially in low-income countries. 2) Efficiency: theoretically, it should deliver around 29%; however, the efficiency of most of the commercially available silicon-based solar cells ranges from 18 – 22%. 3) Temperature sensitivity: The efficiency decreases with the increase in the temperature, affecting their output. 4) Resource constraints: silicon as a raw material is unavailable in all countries, creating supply chain challenges. 
Perovskite solar cells arose in 2011 and matured very rapidly in the last decade as a highly efficient and versatile solar cell technology. With an efficiency of 26%, high absorption coefficients, solution processability, and tunable band gap, it attracted the attention of the solar cells community. It represented a hope for cheap, efficient, and easily processable next-generation solar cells. However, lead toxicity might be the block stone hindering perovskite solar cells’ market reach. Lead is a heavy and bioavailable element that makes perovskite solar cells environmentally unfriendly technology. As a result, scientists try to replace lead with a more environmentally friendly element. Among several possible alternatives, tin was the most suitable element due to its electronic and atomic structure similarity to lead.
Tin perovskites were developed to alleviate the challenge of lead toxicity. Theoretically, it shows very high absorption coefficients, an optimum band gap of 1.35 eV for FASnI3, and a very high short circuit current, which nominates it to deliver the highest possible efficiency of a single junction solar cell, which is around 30.1% according to Schockly-Quisser limit. However, tin perovskites’ efficiency still lags below 15% and is irreproducible, especially from lab to lab. This humble performance could be attributed to three reasons: 1) Tin (II) oxidation to tin (IV), which would happen due to oxygen, water, or even by the effect of the solvent, as was discovered recently. 2) fast crystallization dynamics, which occurs due to the lateral exposure of the P-orbitals of the tin atom, which enhances its reactivity and increases the crystallization pace. 3) Energy band misalignment: The energy bands at the interfaces between the perovskite absorber material and the charge selective layers are not aligned, leading to high interfacial charge recombination, which devastates the photovoltaic performance. To solve these issues, we implemented several techniques and approaches that enhanced the efficiency of tin halide perovskites, providing new chemically safe solvents and antisolvents. In addition, we studied the energy band alignment between the charge transport layers and the tin perovskite absorber.  
Recent research has shown that the principal source of tin oxidation is the solvent known as dimethylsulfoxide, which also happens to be one of the most effective solvents for processing perovskite. The search for a stable solvent might prove to be the factor that makes all the difference in the stability of tin-based perovskites. We started with a database of over 2,000 solvents and narrowed it down to a series of 12 new solvents that are suitable for processing FASnI3 experimentally. This was accomplished by looking into 1) the solubility of the precursor chemicals FAI and SnI2, 2) the thermal stability of the precursor solution, and 3) the potential to form perovskite. Finally, we show that it is possible to manufacture solar cells using a novel solvent system that outperforms those produced using DMSO. The results of our research give some suggestions that may be used in the search for novel solvents or mixes of solvents that can be used to manufacture stable tin-based perovskites.
Due to the quick crystallization of tin, it is more difficult to deposit tin-based perovskite films from a solution than manufacturing lead-based perovskite films since lead perovskite is more often utilized. The most efficient way to get high efficiencies is to deposit perovskite from dimethyl sulfoxide (DMSO), which slows down the quick construction of the tin-iodine network that is responsible for perovskite synthesis. This is the most successful approach for achieving high efficiencies. Dimethyl sulfoxide, which is used in the processing, is responsible for the oxidation of tin, which is a disadvantage of this method. This research presents a potentially fruitful alternative in which 4-(tert-butyl) pyridine can substitute dimethyl sulfoxide in the process of regulating crystallization without causing tin oxidation to take place. Perovskite films that have been formed from pyridine have been shown to have a much-reduced defect density. This has resulted in increased charge mobility and better photovoltaic performance, making pyridine a desirable alternative for use in the deposition of tin perovskite films.
The precise control of perovskite precursor crystallization inside a thin film is of utmost importance for optimizing the efficiency and manufacturing of solar cells. The deposition process of tin-based perovskite films from a solution presents difficulties due to the quick crystallization of tin compared to the more often employed lead perovskite. The optimal approach for attaining elevated efficiencies entails using dimethyl sulfoxide (DMSO) as a medium for depositing perovskite. This choice of solvent impedes the tin-iodine network’s fast aggregation, which plays a crucial role in the production of perovskite. Nevertheless, this methodology is limited since the utilization of dimethyl sulfoxide leads to the oxidation of tin throughout the processing stage. In this thesis, we present a potentially advantageous alternative approach wherein 4-(tert-butyl) pyridine is proposed as a substitute for dimethyl sulfoxide in regulating crystallization processes while avoiding the undesired consequence of tin oxidation. Films of perovskite formed using pyridine as a solvent have a notably reduced density of defects, resulting in higher mobility of charges and improved performance in solar applications. Consequently, the utilization of pyridine for the deposition of tin perovskite films is considered advantageous.
Tin perovskites are suffering from an apparent energy band misalignment. However, the band diagrams published in the current body of research display contradictions, resulting in a dearth of unanimity. Moreover, comprehensive information about the dynamics connected with charge extraction is lacking. This thesis aims to ascertain the energy band locations of tin perovskites by employing the kelvin probe and Photoelectron yield spectroscopy methods. This thesis aims to construct a precise band diagram for the often-utilized device stack. Moreover, a comprehensive analysis is performed to assess the energy deficits inherent in the current energetic structure of tin halide perovskites. In addition, we investigate the influence of BCP on the improvement of electron extraction in C60/BCP systems, with a specific emphasis on the energy factors involved. Furthermore, transient surface photovoltage was utilized to investigate the charge extraction kinetics of frequently studied charge transport layers, such as NiOx and PEDOT as hole transport layers and C60, ICBA, and PCBM as electron transport layers. The Hall effect, KP, and TRPL approaches accurately ascertain the p-doping concentration in FASnI3. The results consistently demonstrated a value of 1.5 * 1017 cm-3. Our research findings highlight the imperative nature of autonomously constructing the charge extraction layers for tin halide perovskites, apart from those used for lead perovskites.
The crystallization of perovskite precursors relies mainly on the utilization of two solvents. The first one dissolves the perovskite powder to form the precursor solution, usually called the solvent. The second one precipitates the perovskite precursor, forming the wet film, which is a supersaturated solution of perovskite precursor and in the remains of the solvent and the antisolvent. Later, this wet film crystallizes upon annealing into a full perovskite crystallized film. In our research context, we proposed new solvents to dissolve FASnI3, but when we tried to form a film, most of them did not crystallize. This is attributed to the high coordination strength between the metal halide and the solvent molecules, which is unbreakable by the traditionally used antisolvents such as Toluene and Chlorobenzene. To solve this issue, we introduce a high-throughput antisolvent screening in which we screened around 73 selected antisolvents against 15 solvents that can form a 1M FASnI3 solution. We used for the first time in tin perovskites machine learning algorithm to understand and predict the effect of an antisolvent on the crystallization of a precursor solution in a particular solvent. We relied on film darkness as a primary criterion to judge the efficacy of a solvent-antisolvent pair. We found that the relative polarity between solvent and antisolvent is the primary factor that affects the solvent-antisolvent interaction. Based on our findings, we prepared several high-quality tin perovskite films free from DMSO and achieved an efficiency of 9%, which is the highest DMSO tin perovskite device so far.
N2  - Zinn ist eine der vielversprechendsten Alternativen zu Blei, um bleifreie Halogenidperowskite für die Optoelektronik herzustellen. Die Stabilität von Perowskiten auf Zinnbasis wird jedoch durch die Oxidation von Sn(II) zu Sn(IV) beeinträchtigt. Jüngste Arbeiten haben ergeben, dass Dimethylsulfoxid, eines der besten Lösungsmittel für die Verarbeitung von Perowskiten, die Hauptquelle für die Oxidation von Zinn ist. Die Suche nach einem stabilen Lösungsmittel könnte den Ausschlag für die Stabilität von Perowskiten auf Zinnbasis geben. Ausgehend von einer Datenbank mit über 2000 Lösungsmitteln haben wir eine Reihe von 12 neuen Lösungsmitteln identifiziert, die für die Verarbeitung von Formamidinium-Zinniodid-Perowskit (FASnI3) geeignet sind, indem wir 1) die Löslichkeit der Vorläuferchemikalien FAI und SnI2, 2) die thermische Stabilität der Vorläuferlösung und 3) die Möglichkeit zur Bildung von Perowskit experimentell untersucht haben. Schließlich demonstrieren wir ein neues Lösungsmittelsystem zur Herstellung von Solarzellen, das die auf DMSO basierenden Zellen übertrifft. Unsere Arbeit liefert Leitlinien für die weitere Identifizierung neuer Lösungsmittel oder Lösungsmittelmischungen zur Herstellung stabiler Perowskite auf Zinnbasis.
Die genaue Steuerung der Kristallisation des Perowskit-Vorläufers in einer Dünnschicht ist entscheidend für die Effizienz und Produktion von Solarzellen. Die Abscheidung von Perowskit-Filmen auf Zinnbasis aus einer Lösung stellt aufgrund der schnellen Kristallisation von Zinn im Vergleich zu dem üblicherweise verwendeten Bleiperowskit eine Herausforderung dar. Die effektivste Methode zur Erzielung hoher Wirkungsgrade ist die Abscheidung von Perowskit aus Dimethylsulfoxid (DMSO), das den schnellen Aufbau des für die Perowskitbildung verantwortlichen Zinn-Jod-Netzwerks behindert. Dieser Ansatz hat jedoch einen Nachteil, da Dimethylsulfoxid während der Verarbeitung eine Zinnoxidation verursacht. In dieser Studie wird eine vielversprechende Alternative vorgestellt, bei der 4-(tert-Butyl)-pyridin Dimethylsulfoxid bei der Steuerung der Kristallisation ersetzen kann, ohne eine Zinnoxidation zu verursachen. Aus Pyridin abgeschiedene Perowskit-Filme weisen eine deutlich geringere Defektdichte auf, was zu einer erhöhten Ladungsbeweglichkeit und einer verbesserten photovoltaischen Leistung führt und es zu einer günstigen Wahl für die Abscheidung von Zinn-Perowskit-Filmen macht.
Zinnperowskite haben sich als vielversprechender, umweltverträglicher Ersatz für Bleiperowskite erwiesen, vor allem wegen ihrer besseren optoelektronischen Eigenschaften und ihrer geringeren Bioverfügbarkeit. Dennoch gibt es mehrere Gründe, warum die Leistung von Zinnperowskiten nicht mit der von Bleiperowskiten verglichen werden kann. Einer dieser Gründe ist die Nichtübereinstimmung der Energiebänder zwischen dem Perowskit-Absorberfilm und den ladungstransportierenden Schichten (CTLs). Die in der vorhandenen Literatur dargestellten Banddiagramme sind jedoch uneinheitlich, was zu einem Mangel an Konsens führt. Außerdem ist das Verständnis der mit der Ladungsextraktion verbundenen Dynamik noch unzureichend. In dieser Studie sollen die Energiebandpositionen von Zinnperowskiten mit Hilfe der Kelvinsonde (KP) und der Photoelektronenausbeutespektroskopie (PYS) bestimmt werden. Ziel ist es, ein genaues Banddiagramm für den üblicherweise verwendeten Bauelementestapel zu erstellen. Darüber hinaus führen wir eine Diagnose der energetischen Unzulänglichkeiten durch, die im bestehenden energetischen Rahmen von Zinnhalogenid-Perowskiten vorhanden sind. Unser Ziel ist es, Folgendes zu klären den Einfluss von BCP auf die Verbesserung der Elektronenextraktion in C60/BCP-Systemen, wobei der Schwerpunkt auf den energetischen Aspekten liegt. Darüber hinaus haben wir die transiente Oberflächenphotospannung (tr-SPV) eingesetzt, um Einblicke in die Ladungsextraktionskinetik von allgemein bekannten CTLs zu gewinnen, einschließlich NiOx und PEDOT als Lochtransportschichten (HTLs) und C60, ICBA und PCBM als Elektronentransportschichten (ETLs). In diesem Kapitel verwenden wir den Halleffekt, KP- und TRPL-Techniken, um die genaue p-Dotierungskonzentration in FASnI3 zu bestimmen. Unsere Ergebnisse ergaben durchweg einen Wert von 1.5 * 1017 cm-3. Die Ergebnisse unserer Studie zeigen, dass es notwendig ist, die Ladungsextraktionsschichten von Zinnhalogenidperowskiten unabhängig von den Bleiperowskiten zu entwickeln.
Die Kristallisation von Perowskit-Vorstufen beruht hauptsächlich auf der Verwendung von zwei Lösungsmitteln. Das erste löst das Perowskit-Pulver auf und bildet die Vorläuferlösung, die üblicherweise als Lösungsmittel bezeichnet wird. Mit dem zweiten wird der Perowskit-Precursor ausgefällt, wobei sich der Nassfilm bildet, der eine übersättigte Lösung des Perowskit-Precursors und der Reste des Lösungsmittels und des Antisolierungsmittels ist. Später kristallisiert dieser nasse Film beim Ausglühen zu einem vollständig kristallisierten Perowskit-Film. In unserem Forschungskontext haben wir neue Lösungsmittel vorgeschlagen, um FASnI3 aufzulösen, aber als wir versuchten, einen Film zu bilden, kristallisierten die meisten von ihnen nicht. Dies ist auf die hohe Koordinationsstärke zwischen dem Metallhalogenid und den Lösungsmittelmolekülen zurückzuführen, die von den traditionell verwendeten Antisolierungsmitteln wie Toluol und Chlorbenzol nicht aufgebrochen werden kann. Um dieses Problem zu lösen, haben wir ein Hochdurchsatz-Screening von Antisolventien durchgeführt, bei dem wir 73 ausgewählte Antisolventien mit 15 Lösungsmitteln verglichen haben, die eine 1M FASnI3-Lösung bilden können. Wir haben zum ersten Mal bei Zinnperowskiten einen Algorithmus für maschinelles Lernen verwendet, um die Wirkung eines Antisolvens auf die Kristallisation einer Vorläuferlösung in einem bestimmten Lösungsmittel zu verstehen und vorherzusagen. Wir stützten uns auf die Schwärzung des Films als primäres Kriterium zur Beurteilung der Wirksamkeit eines Lösungsmittel-Antisolierungsmittel-Paares. Wir fanden heraus, dass die relative Polarität zwischen Lösungsmittel und Antisolvent der wichtigste Faktor ist, der die Wechselwirkung zwischen Lösungsmittel und Antisolvent beeinflusst. Auf der Grundlage unserer Erkenntnisse haben wir mehrere hochwertige Zinn-Perowskit-Filme ohne DMSO hergestellt und einen Wirkungsgrad von 9 % erzielt, was die bisher höchste DMSO-Zinn-Perowskit-Vorrichtung darstellt.
KW  - perovskite solar cells
KW  - lead-free perovskites
KW  - tin perovskites
KW  - solar cells
KW  - perovskite
KW  - Perowskit-Solarzellen
KW  - photovoltaische Materialien
KW  - Solarzellen
KW  - Lösungsmittel
KW  - bleifreie Perowskit-Solarzellen
Y1  - 2024
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-630375
ER  - 
TY  - JOUR
A1  - Wang, Peixi
A1  - Geiger, Christina
A1  - Kreuzer, Lucas
A1  - Widmann, Tobias
A1  - Reitenbach, Julija
A1  - Liang, Suzhe
A1  - Cubitt, Robert
A1  - Henschel, Cristiane
A1  - Laschewsky, André
A1  - Papadakis, Christine M.
A1  - Müller-Buschbaum, Peter
T1  - Poly(sulfobetaine)-based diblock copolymer thin films in water/acetone atmosphere: modulation of water hydration and co-nonsolvency-triggered film contraction
JF  - Langmuir : the ACS journal of surfaces and colloids
N2  - The water swelling and subsequent solvent exchange including co-nonsolvency behavior of thin films of a doubly thermo-responsive diblock copolymer (DBC) are studied viaspectral reflectance, time-of-flight neutron reflectometry, and Fourier transform infrared spectroscopy. 
The DBC consists of a thermo-responsive zwitterionic (poly(4-((3-methacrylamidopropyl) dimethylammonio) butane-1-sulfonate)) (PSBP) block, featuring an upper critical solution temperature transition in aqueous media but being insoluble in acetone, and a nonionic poly(N-isopropylmethacrylamide) (PNIPMAM) block, featuring a lower critical solution temperature transition in water, while being soluble in acetone. 
Homogeneous DBC films of 50-100 nm thickness are first swollen in saturated water vapor (H2OorD2O), before they are subjected to a contraction process by exposure to mixed saturated water/acetone vapor (H2OorD2O/acetone-d6 = 9:1 v/v).
The affinity of the DBC film toward H2O is stronger than for D2O, as inferred from the higher film thickness in the swollen state and the higher absorbed water content, thus revealing a pronounced isotope sensitivity. 
During the co-solvent-induced switching by mixed water/acetone vapor, a two-step film contraction is observed, which is attributed to the delayed expulsion of water molecules and uptake of acetone molecules. 
The swelling kinetics are compared for both mixed vapors (H2O/acetone-d6 and D2O/acetone-d6) and with those of the related homopolymer films. 
Moreover, the concomitant variations of the local environment around the hydrophilic groups located in the PSBP and PNIPMAM blocks are followed. 
The first contraction step turns out to be dominated by the behavior of the PSBP block, where as the second one is dominated by the PNIPMAM block. 
The unusual swelling and contraction behavior of the latter block is attributed to its co-nonsolvency behavior. 
Furthermore, we observe cooperative hydration effects in the DBC films, that is, both polymer blocks influence each other's solvation behavior.
Y1  - 2022
U6  - https://doi.org/10.1021/acs.langmuir.2c00451
SN  - 0743-7463
SN  - 1520-5827
VL  - 38
IS  - 22
SP  - 6934
EP  - 6948
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Kuntze, Kim
A1  - Viljakka, Jani
A1  - Titov, Evgenii
A1  - Ahmed, Zafar
A1  - Kalenius, Elina
A1  - Saalfrank, Peter
A1  - Priimagi, Arri
T1  - Towards low-energy-light-driven bistable photoswitches
BT  - ortho-fluoroaminoazobenzenes
JF  - Photochemical & photobiological sciences / European Society for Photobiology
N2  - Thermally stable photoswitches that are driven with low-energy light are rare, yet crucial for extending the applicability of photoresponsive molecules and materials towards, e.g., living systems. Combined ortho-fluorination and -amination couples high visible light absorptivity of o-aminoazobenzenes with the extraordinary bistability of o-fluoroazobenzenes. Herein, we report a library of easily accessible o-aminofluoroazobenzenes and establish structure-property relationships regarding spectral qualities, visible light isomerization efficiency and thermal stability of the cis-isomer with respect to the degree of o-substitution and choice of amino substituent. We rationalize the experimental results with quantum chemical calculations, revealing the nature of low-lying excited states and providing insight into thermal isomerization. The synthesized azobenzenes absorb at up to 600 nm and their thermal cis-lifetimes range from milliseconds to months. The most unique example can be driven from trans to cis with any wavelength from UV up to 595 nm, while still exhibiting a thermal cis-lifetime of 81 days. <br /> [GRAPHICS] <br /> .
Y1  - 2022
U6  - https://doi.org/10.1007/s43630-021-00145-4
SN  - 1474-905X
SN  - 1474-9092
VL  - 21
IS  - 2
SP  - 159
EP  - 173
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - JOUR
A1  - Xie, Dongjiu
A1  - Xu, Yaolin
A1  - Wang, Yonglei
A1  - Pan, Xuefeng
A1  - Härk, Eneli
A1  - Kochovski, Zdravko
A1  - Eljarrat, Alberto
A1  - Müller, Johannes
A1  - Koch, Christoph T.
A1  - Yuan, Jiayin
A1  - Lu, Yan
T1  - Poly(ionic liquid) nanovesicle-templated carbon nanocapsules functionalized with uniform iron nitride nanoparticles as catalytic sulfur host for Li-S batteries
JF  - ACS nano
N2  - Poly(ionic liquid)s (PIL) are common precursors for heteroatom-doped carbon materials. Despite a relatively higher carbonization yield, the PIL-to-carbon conversion process faces challenges in preserving morphological and structural motifs on the nanoscale. Assisted by a thin polydopamine coating route and ion exchange, imidazoliumbased PIL nanovesicles were successfully applied in morphology-maintaining carbonization to prepare carbon composite nanocapsules. Extending this strategy further to their composites, we demonstrate the synthesis of carbon composite nanocapsules functionalized with iron nitride nanoparticles of an ultrafine, uniform size of 3-5 nm (termed "FexN@C "). Due to its unique nanostructure, the sulfur-loaded FexN@C electrode was tested to efficiently mitigate the notorious shuttle effect of lithium polysulfides (LiPSs) in Li-S batteries. The cavity of the carbon nanocapsules was spotted to better the loading content of sulfur. The well-dispersed iron nitride nanoparticles effectively catalyze the conversion of LiPSs to Li2S, owing to their high electronic conductivity and strong binding power to LiPSs. Benefiting from this well-crafted composite nanostructure, the constructed FexN@C/S cathode demonstrated a fairly high discharge capacity of 1085 mAh g(-1) at 0.5 C initially, and a remaining value of 930 mAh g(-1 )after 200 cycles. In addition, it exhibits an excellent rate capability with a high initial discharge capacity of 889.8 mAh g(-1) at 2 C. This facile PIL-to-nanocarbon synthetic approach is applicable for the exquisite design of complex hybrid carbon nanostructures with potential use in electrochemical energy storage and conversion.
KW  - poly(ionic liquid)s
KW  - nanovesicles
KW  - sulfur host
KW  - iron nitride
KW  - Li-S
KW  - batteries
Y1  - 2022
U6  - https://doi.org/10.1021/acsnano.2c01992
SN  - 1936-0851
SN  - 1936-086X
VL  - 16
IS  - 7
SP  - 10554
EP  - 10565
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Neffe, Axel T.
A1  - Löwenberg, Candy
A1  - Julich-Gruner, Konstanze K.
A1  - Behl, Marc
A1  - Lendlein, Andreas
T1  - Thermally-induced shape-memory behavior of degradable gelatin-based networks
JF  - International journal of molecular sciences
N2  - Shape-memory hydrogels (SMH) are multifunctional, actively-moving polymers of interest in biomedicine. In loosely crosslinked polymer networks, gelatin chains may form triple helices, which can act as temporary net points in SMH, depending on the presence of salts. Here, we show programming and initiation of the shape-memory effect of such networks based on a thermomechanical process compatible with the physiological environment. The SMH were synthesized by reaction of glycidylmethacrylated gelatin with oligo(ethylene glycol) (OEG) alpha,omega-dithiols of varying crosslinker length and amount. Triple helicalization of gelatin chains is shown directly by wide-angle X-ray scattering and indirectly via the mechanical behavior at different temperatures. The ability to form triple helices increased with the molar mass of the crosslinker. Hydrogels had storage moduli of 0.27-23 kPa and Young's moduli of 215-360 kPa at 4 degrees C. The hydrogels were hydrolytically degradable, with full degradation to water-soluble products within one week at 37 degrees C and pH = 7.4. A thermally-induced shape-memory effect is demonstrated in bending as well as in compression tests, in which shape recovery with excellent shape-recovery rates R-r close to 100% were observed. In the future, the material presented here could be applied, e.g., as self-anchoring devices mechanically resembling the extracellular matrix.
KW  - shape-memory hydrogel
KW  - active polymer
KW  - biopolymer
KW  - mechanical
KW  - properties
KW  - degradation
Y1  - 2021
U6  - https://doi.org/10.3390/ijms22115892
SN  - 1422-0067
SN  - 1661-6596
VL  - 22
IS  - 11
PB  - Molecular Diversity Preservation International
CY  - Basel
ER  - 
TY  - JOUR
A1  - Bochove, Bas van
A1  - Grijpma, Dirk W.
A1  - Lendlein, Andreas
A1  - Seppälä, Jukka
T1  - Designing advanced functional polymers for medicine
JF  - European polymer journal : EPJ
Y1  - 2021
U6  - https://doi.org/10.1016/j.eurpolymj.2021.110573
SN  - 0014-3057
VL  - 155
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Hwang, Jinyeon
A1  - Zhang, Wuyong
A1  - Youk, Sol
A1  - Schutjajew, Konstantin
A1  - Oschatz, Martin
T1  - Understanding structure-property relationships under experimental conditions for the optimization of lithium-ion capacitor anodes based on all-carbon-composite materials
JF  - Energy technology : generation, conversion, storage, distribution
N2  - The nanoscale combination of a conductive carbon and a carbon-based material with abundant heteroatoms for battery electrodes is a method to overcome the limitation that the latter has high affinity to alkali metal ions but low electronic conductivity. The synthetic protocol and the individual ratios and structures are important aspects influencing the properties of such multifunctional compounds. Their interplay is, herein, investigated by infiltration of a porous ZnO-templated carbon (ZTC) with nitrogen-rich carbon obtained by condensation of hexaazatriphenylene-hexacarbonitrile (HAT-CN) at 550-1000 degrees C. The density of lithiophilic sites can be controlled by HAT-CN content and condensation temperature. Lithium storage properties are significantly improved in comparison with those of the individual compounds and their physical mixtures. Depending on the uniformity of the formed composite, loading ratio and condensation temperature have different influence. Most stable operation at high capacity per used monomer is achieved with a slowly dried composite with an HAT-CN:ZTC mass ratio of 4:1, condensed at 550 degrees C, providing more than 400 mAh g(-1) discharge capacity at 0.1 A g(-1) and a capacity retention of 72% after 100 cycles of operation at 0.5 A g(-1) due to the homogeneity of the composite and high content of lithiophilic sites.
KW  - anodes
KW  - hybrid materials
KW  - nitrogen-doped carbon
KW  - porous carbon
KW  - lithium-ion capacitors
Y1  - 2021
U6  - https://doi.org/10.1002/ente.202001054
SN  - 2194-4296
VL  - 9
IS  - 3
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Pan, Xuefeng
A1  - Sarhan, Radwan Mohamed
A1  - Kochovski, Zdravko
A1  - Chen, Guosong
A1  - Taubert, Andreas
A1  - Mei, Shilin
A1  - Lu, Yan
T1  - Template synthesis of dual-functional porous MoS2 nanoparticles with photothermal conversion and catalytic properties
JF  - Nanoscale
N2  - Advanced catalysis triggered by photothermal conversion effects has aroused increasing interest due to its huge potential in environmental purification. 
In this work, we developed a novel approach to the fast degradation of 4-nitrophenol (4-Nip) using porous MoS2 nanoparticles as catalysts, which integrate the intrinsic catalytic property of MoS2 with its photothermal conversion capability. 
Using assembled polystyrene-b-poly(2-vinylpyridine) block copolymers as soft templates, various MoS 2 particles were prepared, which exhibited tailored morphologies (e.g., pomegranate-like, hollow, and open porous structures). 
The photothermal conversion performance of these featured particles was compared under near-infrared (NIR) light irradiation. 
Intriguingly, when these porous MoS2 particles were further employed as catalysts for the reduction of 4-Nip, the reaction rate constant was increased by a factor of 1.5 under NIR illumination. 
We attribute this catalytic enhancement to the open porous architecture and light-to-heat conversion performance of the MoS2 particles. This contribution offers new opportunities for efficient photothermal-assisted catalysis.
Y1  - 2022
U6  - https://doi.org/10.1039/d2nr01040b
SN  - 2040-3372
VL  - 14
IS  - 18
SP  - 6888
EP  - 6901
PB  - RSC Publ. (Royal Society of Chemistry)
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Zhao, Yuhang
A1  - Sarhan, Radwan Mohamed
A1  - Eljarrat, Alberto
A1  - Kochovski, Zdravko
A1  - Koch, Christoph
A1  - Schmidt, Bernd
A1  - Koopman, Wouter-Willem Adriaan
A1  - Lu, Yan
T1  - Surface-functionalized Au-Pd nanorods with enhanced photothermal conversion and catalytic performance
JF  - ACS applied materials & interfaces
N2  - Bimetallic nanostructures comprising plasmonic and catalytic components have recently emerged as a promising approach to generate a new type of photo-enhanced nanoreactors. Most designs however concentrate on plasmon-induced charge separation, leaving photo-generated heat as a side product. 
This work presents a photoreactor based on Au-Pd nanorods with an optimized photothermal conversion, which aims to effectively utilize the photo-generated heat to increase the rate of Pd-catalyzed reactions. Dumbbell-shaped Au nanorods were fabricated via a seed-mediated growth method using binary surfactants. Pd clusters were selectively grown at the tips of the Au nanorods, using the zeta potential as a new synthetic parameter to indicate the surfactant remaining on the nanorod surface. 
The photothermal conversion of the Au-Pd nanorods was improved with a thin layer of polydopamine (PDA) or TiO2. 
As a result, a 60% higher temperature increment of the dispersion compared to that for bare Au rods at the same light intensity and particle density could be achieved. 
The catalytic performance of the coated particles was then tested using the reduction of 4-nitrophenol as the model reaction. Under light, the PDA-coated Au-Pd nanorods exhibited an improved catalytic activity, increasing the reaction rate by a factor 3. 
An analysis of the activation energy confirmed the photoheating effect to be the dominant mechanism accelerating the reaction. Thus, the increased photothermal heating is responsible for the reaction acceleration. 
Interestingly, the same analysis shows a roughly 10% higher reaction rate for particles under illumination compared to under dark heating, possibly implying a crucial role of localized heat gradients at the particle surface. 
Finally, the coating thickness was identified as an essential parameter determining the photothermal conversion efficiency and the reaction acceleration.
KW  - Au-Pd nanorods
KW  - PDA
KW  - photothermal conversion
KW  - surface plasmon
KW  - 4-nitrophenol
Y1  - 2022
U6  - https://doi.org/10.1021/acsami.2c00221
SN  - 1944-8244
SN  - 1944-8252
VL  - 14
IS  - 15
SP  - 17259
EP  - 17272
PB  - American Chemical Society
CY  - Washington, DC
ER  - 
TY  - JOUR
A1  - Floyd, Thomas G.
A1  - Song, Ji-Inn
A1  - Hapeshi, Alexia
A1  - Laroque, Sophie
A1  - Hartlieb, Matthias
A1  - Perrier, Sebastien
T1  - Bottlebrush copolymers for gene delivery: influence of architecture, charge density, and backbone length on transfection efficiency
JF  - Journal of materials chemistry : B, materials for biology and medicine
N2  - The influence of polymer architecture of polycations on their ability to transfect mammalian cells is probed. Polymer bottle brushes with grafts made from partially hydrolysed poly(2-ethyl-2-oxazoline) are used while varying the length of the polymer backbone as well as the degree of hydrolysis (cationic charge content). Polyplex formation is investigated via gel electrophoresis, dye-displacement and dynamic light scattering. Bottle brushes show a superior ability to complex pDNA when compared to linear copolymers. Also, nucleic acid release was found to be improved by a graft architecture. Polyplexes based on bottle brush copolymers showed an elongated shape in transmission electron microscopy images. The cytotoxicity against mammalian cells is drastically reduced when a graft architecture is used instead of linear copolymers. Moreover, the best-performing bottle brush copolymer showed a transfection ability comparable with that of linear poly(ethylenimine), the gold standard of polymeric transfection agents, which is used as positive control. In combination with their markedly lowered cytotoxicity, cationic bottle brush copolymers are therefore shown to be a highly promising class of gene delivery vectors.
Y1  - 2022
U6  - https://doi.org/10.1039/d2tb00490a
SN  - 2050-750X
SN  - 2050-7518
VL  - 10
IS  - 19
SP  - 3696
EP  - 3704
PB  - Royal Society of Chemistry
CY  - London [u.a.]
ER  - 
TY  - GEN
A1  - Perovic, Milena
A1  - Zeininger, Lukas
A1  - Oschatz, Martin
T1  - Immobilization of gold-on-carbon catalysts onto perfluorocarbon emulsion droplets to promote oxygen delivery in aqueous phase (D)-glucose oxidation
T2  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - The catalytic activity of metal nanoparticles (NPs) supported on porous supports can be controlled by various factors, such as NPs size, shape, or dispersivity, as well as their interaction with the support or the properties of the support material itself. However, these intrinsic properties are not solely responsible for the catalytic behavior of the overall reaction system, as the local environment and surface coverage of the catalyst with reactants, products, intermediates and other invloved species often play a crucial role in catalytic processes as well. Their contribution can be particularly critical in liquid-phase reactions with gaseous reactants that often suffer from low solubiltiy. One example is (D)-glucose oxidation with molecular oxygen over gold nanoparticles supported on porous carbons. The possibility to promote oxygen delivery in such aqueous phase oxidation reactions via the immobilization of heterogenous catalysts onto the interface of perfluorocarbon emulsion droplets is reported here. Gold-on-carbon catalyst particles can stabilize perfluorocarbon droplets in the aqueous phase and the local concentration of the oxidant in the surroundings of the gold nanoparticles accelerates the rate-limiting step of the reaction. Consequently, the reaction rate of a system with the optimal volume fraction of fluorocarbon is higher than a reference emulsion system without fluorocarbon, and the effect is observed even without additional oxygen supply.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1362 
KW  - perfluorocarbon emulsion
KW  - glucose oxidation
KW  - porous carbon
KW  - gas
KW  - solubility
KW  - pickering emulsion
KW  - liquid-phase catalysis
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-569471
SN  - 1867-3880
SN  - 1867-3899
SN  - 1866-8372
IS  - 1
ER  - 
TY  - JOUR
A1  - Abbasi, Ali
A1  - Xu, Yaolin
A1  - Khezri, Ramin
A1  - Etesami, Mohammad
A1  - Lin, C.
A1  - Kheawhom, Soorathep
A1  - Lu, Yan
T1  - Advances in characteristics improvement of polymeric membranes/separators for zinc-air batteries
JF  - Materials Today Sustainability
N2  - Zinc-air batteries (ZABs) are gaining popularity for a wide range of applications due to their high energy density, excellent safety, and environmental friendliness. A membrane/separator is a critical component of ZABs, with substantial implications for battery performance and stability, particularly in the case of a battery in solid state format, which has captured increased attention in recent years. In this review, recent advances as well as insight into the architecture of polymeric membrane/separators for ZABs including porous polymer separators (PPSs), gel polymer electrolytes (GPEs), solid polymer electrolytes (SPEs) and anion exchange membranes (AEMs) are discussed. The paper puts forward strategies to enhance stability, ionic conductivity, ionic selectivity, electrolyte storage capacity and mechanical properties for each type of polymeric membrane. In addition, the remaining major obstacles as well as the most potential avenues for future research are examined in detail.
KW  - Ionic selectivity
KW  - Ionic conductivity
KW  - Gel polymer
KW  - Ion exchange
KW  - Porous
KW  - polymer
Y1  - 2022
U6  - https://doi.org/10.1016/j.mtsust.2022.100126
SN  - 2589-2347
VL  - 18
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - GEN
A1  - Rausch, Ann-Kristin
A1  - Brockmeyer, Robert
A1  - Schwerdtle, Tanja
T1  - Development, validation, and application of a multi-method for the determination of mycotoxins, plant growth regulators, tropane alkaloids, and pesticides in cereals by two-dimensional liquid chromatography tandem mass spectrometry
T2  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Mycotoxins and pesticides regularly co-occur in agricultural products worldwide. Thus, humans can be exposed to both toxic contaminants and pesticides simultaneously, and multi-methods assessing the occurrence of various food contaminants and residues in a single method are necessary. A two-dimensional high performance liquid chromatography tandem mass spectrometry method for the analysis of 40 (modified) mycotoxins, two plant growth regulators, two tropane alkaloids, and 334 pesticides in cereals was developed. After an acetonitrile/water/formic acid (79:20:1, v/v/v) multi-analyte extraction procedure, extracts were injected into the two-dimensional setup, and an online clean-up was performed. The method was validated according to Commission Decision (EC) no. 657/2002 and document N° SANTE/12682/2019. Good linearity (R2 > 0.96), recovery data between 70-120%, repeatability and reproducibility values < 20%, and expanded measurement uncertainties < 50% were obtained for a wide range of analytes, including very polar substances like deoxynivalenol-3-glucoside and methamidophos. However, results for fumonisins, zearalenone-14,16-disulfate, acid-labile pesticides, and carbamates were unsatisfying. Limits of quantification meeting maximum (residue) limits were achieved for most analytes. Matrix effects varied highly (−85 to +1574%) and were mainly observed for analytes eluting in the first dimension and early-eluting analytes in the second dimension. The application of the method demonstrated the co-occurrence of different types of cereals with 28 toxins and pesticides. Overall, 86% of the samples showed positive findings with at least one mycotoxin, plant growth regulator, or pesticide.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1365 
KW  - 2D-LC-MS/MS
KW  - Multi-method
KW  - Mycotoxins
KW  - Modified mycotoxins
KW  - Pesticides
KW  - Cereals
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-514795
SN  - 1866-8372
IS  - 143
ER  - 
TY  - GEN
A1  - Ilic, Ivan K.
A1  - Tsouka, Alexandra
A1  - Perovic, Milena
A1  - Hwang, Jinyeon
A1  - Heil, Tobias
A1  - Löffler, Felix
A1  - Oschatz, Martin
A1  - Antonietti, Markus
A1  - Liedel, Clemens
T1  - Sustainable cathodes for Lithium-ion energy storage devices based on tannic acid-toward ecofriendly energy storage
T2  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - The use of organic materials with reversible redox activity holds enormous potential for next-generation Li-ion energy storage devices. Yet, most candidates are not truly sustainable, i.e., not derived from renewable feedstock or made in benign reactions. Here an attempt is reported to resolve this issue by synthesizing an organic cathode material from tannic acid and microporous carbon derived from biomass. All constituents, including the redox-active material and conductive carbon additive, are made from renewable resources. Using a simple, sustainable fabrication method, a hybrid material is formed. The low cost and ecofriendly material shows outstanding performance with a capacity of 108 mAh g(-1) at 0.1 A g(-1) and low capacity fading, retaining approximately 80% of the maximum capacity after 90 cycles. With approximately 3.4 V versus Li+/Li, the cells also feature one of the highest reversible redox potentials reported for biomolecular cathodes. Finally, the quinone-catecholate redox mechanism responsible for the high capacity of tannic acid is confirmed by electrochemical characterization of a model compound similar to tannic acid but without catecholic groups.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1366 
KW  - biomass
KW  - electrochemistry
KW  - energy storage
KW  - redox chemistry
KW  - sustainability
KW  - tannic acid
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-570560
SN  - 1866-8372
IS  - 1
ER  - 
TY  - GEN
A1  - Farhan, Muhammad
A1  - Chaudhary, Deeptangshu
A1  - Nöchel, Ulrich
A1  - Behl, Marc
A1  - Kratz, Karl
A1  - Lendlein, Andreas
T1  - Electrical actuation of coated and composite fibers based on poly[ethylene-co-(vinyl acetate)]
T2  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Robots are typically controlled by electrical signals. Resistive heating is an option to electrically trigger actuation in thermosensitive polymer systems. In this study electrically triggerable poly[ethylene-co-(vinyl acetate)] (PEVA)-based fiber actuators are realized as composite fibers as well as polymer fibers with conductive coatings. In the coated fibers, the core consists of crosslinked PEVA (cPEVA), while the conductive coating shell is achieved via a dip coating procedure with a coating thickness between 10 and 140 mu m. The conductivity of coated fibers sigma = 300-550 S m(-1) is much higher than that of the composite fibers sigma = 5.5 S m(-1). A voltage (U) of 110 V is required to heat 30 cm of coated fiber to a targeted temperature of approximate to 65 degrees C for switching in less than a minute. Cyclic electrical actuation investigations reveal epsilon '(rev) = 5 +/- 1% reversible change in length for coated fibers. The fabrication of such electro-conductive polymeric actuators is suitable for upscaling so that their application potential as artificial muscles can be explored in future studies.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1375 
KW  - artificial muscles
KW  - fiber actuators
KW  - resistive heating
KW  - shape‐memory polymer actuators
KW  - soft robotics
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-571679
SN  - 1866-8372
IS  - 2
ER  - 
TY  - JOUR
A1  - Mayer, Dennis
A1  - Picconi, David
A1  - Robinson, Matthew S.
A1  - Gühr, Markus
T1  - Experimental and theoretical gas-phase absorption spectra of thionated uracils
JF  - Chemical physics : a journal devoted to experimental and theoretical research involving problems of both a chemical and physical nature
N2  - We present a comparative study of the gas-phase UV spectra of uracil and its thionated counterparts (2-thiouracil, 4-thiouracil and 2,4-dithiouracil), closely supported by time-dependent density functional theory calculations to assign the transitions observed. We systematically discuss pure gas-phase spectra for the (thio)uracils in the range of 200-400 nm (similar to 3.2-6.4 eV), and examine the spectra of all four species with a single theoretical approach. We note that specific vibrational modelling is needed to accurately determine the spectra across the examined wavelength range, and systematically model the transitions that appear at wavelengths shorter than 250 nm. Additionally, we find in the cases of 2-thiouracil and 2,4-dithiouracil, that the gas-phase spectra deviate significantly from some previously published solution-phase spectra, especially those collected in basic environments.
KW  - Thiouracil
KW  - Uracil
KW  - UV-VIS Spectroscopy
KW  - Excited-state calculations;
KW  - TD-DFT
KW  - Gas phase
Y1  - 2022
U6  - https://doi.org/10.1016/j.chemphys.2022.111500
SN  - 0301-0104
VL  - 558
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Zimmermann, Marc
A1  - Stomps, Benjamin René Harald
A1  - Schulte-Osseili, Christine
A1  - Grigoriev, Dmitry
A1  - Ewen, Dirk
A1  - Morgan, Andrew
A1  - Böker, Alexander
T1  - Organic dye anchor peptide conjugates as an advanced coloring agent for polypropylene yarn
JF  - Textile Research Journal
N2  - Polypropylene as one of the world's top commodity polymers is also widely used in the textile industry. However, its non-polar nature and partially crystalline structure significantly complicate the process of industrial coloring of polypropylene. Currently, textiles made of polypropylene or with a significant proportion of polypropylene are dyed under quite harsh conditions, including the use of high pressures and temperatures, which makes this process energy intensive. This research presents a three-step synthesis of coloring agents, capable of adhering onto synthetic polypropylene yarns without harsh energy-consuming conditions. This is possible by encapsulation of organic pigments using trimethoxyphenylsilane, introduction of surface double bonds via modification of the silica shell with trimethoxysilylpropylmethacrylate and final attachment of highly adhesive anchor peptides using thiol-ene chemistry. We demonstrate the applicability of this approach by dyeing polypropylene yarns in a simple process under ambient conditions after giving a step-by-step guide for the synthesis of these new dyeing agents. Finally, the successful dyeing of the yarns is visualized, and its practicability is discussed.
KW  - anchor peptides
KW  - organic dye pigments
KW  - coloring agents
KW  - polypropylene
KW  - yarns
Y1  - 2020
U6  - https://doi.org/10.1177/0040517520932231
SN  - 0040-5175
SN  - 1746-7748
VL  - 91
IS  - 1-2
SP  - 28
EP  - 39
PB  - Sage Publ.
CY  - London
ER  - 
TY  - GEN
A1  - Zimmermann, Marc
A1  - Stomps, Benjamin René Harald
A1  - Schulte-Osseili, Christine
A1  - Grigoriev, Dmitry
A1  - Ewen, Dirk
A1  - Morgan, Andrew
A1  - Böker, Alexander
T1  - Organic dye anchor peptide conjugates as an advanced coloring agent for polypropylene yarn
T2  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Polypropylene as one of the world's top commodity polymers is also widely used in the textile industry. However, its non-polar nature and partially crystalline structure significantly complicate the process of industrial coloring of polypropylene. Currently, textiles made of polypropylene or with a significant proportion of polypropylene are dyed under quite harsh conditions, including the use of high pressures and temperatures, which makes this process energy intensive. This research presents a three-step synthesis of coloring agents, capable of adhering onto synthetic polypropylene yarns without harsh energy-consuming conditions. This is possible by encapsulation of organic pigments using trimethoxyphenylsilane, introduction of surface double bonds via modification of the silica shell with trimethoxysilylpropylmethacrylate and final attachment of highly adhesive anchor peptides using thiol-ene chemistry. We demonstrate the applicability of this approach by dyeing polypropylene yarns in a simple process under ambient conditions after giving a step-by-step guide for the synthesis of these new dyeing agents. Finally, the successful dyeing of the yarns is visualized, and its practicability is discussed.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1380 
KW  - anchor peptides
KW  - organic dye pigments
KW  - coloring agents
KW  - polypropylene yarns
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-548913
SN  - 1866-8372
IS  - 1-2
ER  - 
TY  - GEN
A1  - Wessig, Pablo
A1  - John, Leonard
A1  - Sperlich, Eric
A1  - Kelling, Alexandra
T1  - Sulfur tuning of [1,3]-dioxolo[4.5-f]benzodioxole (DBD) fluorescent dyes
T2  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - The replacement of oxygen by sulfur atoms of [1,3]-dioxolo[4.5-f]benzodioxole (DBD) fluorescent dyes is an efficient way to adjust the photophysical properties (sulfur tuning). While previously developed S-4-DBD dyes exhibit considerably red-shifted absorption and emission wavelength, the heavy atom effect of four sulfur atoms cause low fluorescence quantum yields and short fluorescence lifetimes. Herein, we demonstrate that the replacement of less than four sulfur atoms (S-1-DBD, 1,2-S-2-DBD, and 1,4-S-2-DBD dyes) permits a fine-tuning of the photophysical properties. In some cases, a similar influence on the wavelength without the detrimental effect on the quantum yields and lifetimes is observed. Furthermore, the synthetic accessibility of S-1- and S-2-DBD dyes is improved, compared with S-4-DBD dyes. For coupling with biomolecules a series of reactive derivatives of the new dyes were developed (azides, OSu esters, alkynes, maleimides).
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1381 
KW  - fluorescent dyes
KW  - heterocycles
KW  - photophysics
KW  - stokes shift
KW  - sulfur
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-566241
SN  - 1866-8372
IS  - 3
ER  - 
TY  - GEN
A1  - Bourgat, Yannick
A1  - Tiersch, Brigitte
A1  - Koetz, Joachim
A1  - Menzel, Henning
T1  - Enzyme degradable polymersomes from chitosan-g-[poly-l-lysine-block-epsilon-caprolactone] copolymer
T2  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - The scope of this study includes the synthesis of chitosan-g-[peptide-poly-epsilon-caprolactone] and its self-assembly into polymeric vesicles employing the solvent shift method. In this way, well-defined core-shell structures suitable for encapsulation of drugs are generated. The hydrophobic polycaprolactone side-chain and the hydrophilic chitosan backbone are linked via an enzyme-cleavable peptide. The synthetic route involves the functionalization of chitosan with maleimide groups and the preparation of polycaprolactone with alkyne end-groups. A peptide functionalized with a thiol group on one side and an azide group on the other side is prepared. Thiol-ene click-chemistry and azide-alkyne Huisgen cycloaddition are then used to link the chitosan and poly-epsilon-caprolactone chains, respectively, with this peptide. For a preliminary study, poly-l-lysin is a readily available and cleavable peptide that is introduced to investigate the feasibility of the system. The size and shape of the polymersomes are studied by dynamic light scattering and cryo-scanning electron microscopy. Furthermore, degradability is studied by incubating the polymersomes with two enzymes, trypsin and chitosanase. A dispersion of polymersomes is used to coat titanium plates and to further test the stability against enzymatic degradation.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1382 
KW  - chitosan
KW  - click chemistry
KW  - drug delivery system
KW  - enzyme
KW  - polymersomes
KW  - poly‐ ε ‐ caprolactone
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-566584
SN  - 1866-8372
IS  - 1
ER  - 
TY  - GEN
A1  - Al-Naji, Majd
A1  - Schlaad, Helmut
A1  - Antonietti, Markus
T1  - New (and old) monomers from biorefineries to make polymer chemistry more sustainable
T2  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - This opinion article describes recent approaches to use the "biorefinery" concept to lower the carbon footprint of typical mass polymers, by replacing parts of the fossil monomers with similar or even the same monomer made from regrowing dendritic biomass. Herein, the new and green catalytic synthetic routes are for lactic acid (LA), isosorbide (IS), 2,5-furandicarboxylic acid (FDCA), and p-xylene (pXL). Furthermore, the synthesis of two unconventional lignocellulosic biomass derivable monomers, i.e., alpha-methylene-gamma-valerolactone (MeGVL) and levoglucosenol (LG), are presented. All those have the potential to enter in a cost-effective way, also the mass market and thereby recover lost areas for polymer materials. The differences of catalytic unit operations of the biorefinery are also discussed and the challenges that must be addressed along the synthesis path of each monomers.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1385 
KW  - biodegradable polymers
KW  - biorefineries
KW  - carbohydrate‐ based
KW  - monomers
KW  - green polymers
KW  - lignocellulosic biomass
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-570614
SN  - 1866-8372
IS  - 3
ER  - 
TY  - GEN
A1  - Wang, Xuepu
A1  - Sperling, Marcel
A1  - Reifarth, Martin
A1  - Böker, Alexander
T1  - Shaping metallic nanolattices
BT  - Design by microcontact printing from wrinkled stamps
T2  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - A method for the fabrication of well-defined metallic nanostructures is presented here in a simple and straightforward fashion. As an alternative to lithographic techniques, this routine employs microcontact printing utilizing wrinkled stamps, which are prepared from polydimethylsiloxane (PDMS), and includes the formation of hydrophobic stripe patterns on a substrate via the transfer of oligomeric PDMS. Subsequent backfilling of the interspaces between these stripes with a hydroxyl-functional poly(2-vinyl pyridine) then provides the basic pattern for the deposition of citrate-stabilized gold nanoparticles promoted by electrostatic interaction. The resulting metallic nanostripes can be further customized by peeling off particles in a second microcontact printing step, which employs poly(ethylene imine) surface-decorated wrinkled stamps, to form nanolattices. Due to the independent adjustability of the period dimensions of the wrinkled stamps and stamp orientation with respect to the substrate, particle arrays on the (sub)micro-scale with various kinds of geometries are accessible in a straightforward fashion. This work provides an alternative, cost-effective, and scalable surface-patterning technique to fabricate nanolattice structures applicable to multiple types of functional nanoparticles. Being a top-down method, this process could be readily implemented into, e.g., the fabrication of optical and sensing devices on a large scale.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1391 
KW  - gold nanoparticle assembly
KW  - hydroxyl-functional poly(2-vinyl pyridine)
KW  - metallic nanolattices
KW  - microcontact printing
KW  - oligomeric polydimethylsiloxane
KW  - polydimethylsiloxane wrinkles
KW  - wrinkled stamps
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-514341
SN  - 1866-8372
IS  - 11
ER  - 
TY  - JOUR
A1  - Ilic, Ivan
A1  - Schutjajew, Konstantin
A1  - Zhang, Wuyong
A1  - Oschatz, Martin
T1  - Changes of porosity of hard carbons during mechanical treatment and the relevance for sodium-ion anodes
JF  - Carbon : an international journal sponsored by the American Carbon Society
N2  - Lithium-ion batteries have revolutionized battery technology. However, the scarcity of lithium in nature is driving the search for alternatives. For that reason, sodium-ion batteries have attracted increasing attention in recent years. The main obstacle to their development is the anode as, unlike for lithium-ion batteries, graphite cannot be used due to the inability to form stoichiometrically useful intercalation compounds with sodium. A promising candidate for sodium storage is hard carbon a form of nongraphitisable carbon, that can be synthesized from various precursor materials. Processing of hard carbons is often done by using mechanochemical treatments. Although it is generally accepted and often observed that they can influence the porosity of hard carbons, their effect on battery performance not well understood. Here, the changes in porosity occurring during ball milling are elucidated and related to the properties of hard carbons in sodium storage. Analysis by combined gas physisorption and small angle X-ray scattering shows that porosity changes during ball milling with a significant increase of the open porosity, unsuitable for reversible sodium storage, and decrease of the closed porosity, suitable for reversible sodium storage. While pristine hard carbon can store 58.5 mAh g(-1) in the closed pores, upon 5 h of mechanical treatment in a ball mill it can only store 35.5 mAh g(-1). The obtained results are furthermore pointing towards the disputed "intercalation-adsorption" mechanism.
KW  - Hard carbons
KW  - Sodium-ion batteries
KW  - Anodes
KW  - Microporosity
KW  - Ball milling
Y1  - 2022
U6  - https://doi.org/10.1016/j.carbon.2021.09.063
SN  - 0008-6223
SN  - 1873-3891
VL  - 186
SP  - 55
EP  - 63
PB  - Elsevier Science
CY  - Amsterdam [u.a.]
ER  - 
TY  - JOUR
A1  - Gupta, Banshi D.
A1  - Pathak, Anisha
A1  - Shrivastav, Anand
T1  - Optical Biomedical Diagnostics Using Lab-on-Fiber Technology
BT  - a review
JF  - Photonics : open access journal
N2  - Point-of-care and in-vivo bio-diagnostic tools are the current need for the present critical scenarios in the healthcare industry. The past few decades have seen a surge in research activities related to solving the challenges associated with precise on-site bio-sensing. Cutting-edge fiber optic technology enables the interaction of light with functionalized fiber surfaces at remote locations to develop a novel, miniaturized and cost-effective lab on fiber technology for bio-sensing applications. The recent remarkable developments in the field of nanotechnology provide innumerable functionalization methodologies to develop selective bio-recognition elements for label free biosensors. These exceptional methods may be easily integrated with fiber surfaces to provide highly selective light-matter interaction depending on various transduction mechanisms. In the present review, an overview of optical fiber-based biosensors has been provided with focus on physical principles used, along with the functionalization protocols for the detection of various biological analytes to diagnose the disease. The design and performance of these biosensors in terms of operating range, selectivity, response time and limit of detection have been discussed. In the concluding remarks, the challenges associated with these biosensors and the improvement required to develop handheld devices to enable direct target detection have been highlighted.
KW  - fiber optic sensors
KW  - synthesis
KW  - interferometry
KW  - fluorescence
KW  - SERS
KW  - SPR
KW  - immunosensors
KW  - enzymatic sensors
KW  - molecular imprinted polymers
Y1  - 2022
U6  - https://doi.org/10.3390/photonics9020086
SN  - 2304-6732
VL  - 9
IS  - 2
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Akampurira, Denis
A1  - Akala, Hoseah M.
A1  - Derese, Solomon
A1  - Heydenreich, Matthias
A1  - Yenesew, Abiy
T1  - A new C-C linked benzophenathridine-2-quinoline dimer, and the antiplasmodial activity of alkaloids from Zanthoxylum holstzianum
JF  - Natural product research
N2  - The CH2Cl2/MeOH (1:1) extract of Zanthoxylum holstzianum stem bark showed good antiplasmodial activity (IC50 2.5 +/- 0.3 and 2.6 +/- 0.3 mu g/mL against the W2 and D6 strains of Plasmodium falciparum, respectively). From the extract five benzophenanthridine alkaloids [8-acetonyldihydrochelerythrine (1), nitidine (2), dihydrochelerythine (3), norchelerythrine (5), arnottianamide (8)]; a 2-quinolone alkaloid [N-methylflindersine (4)]; a lignan [4,4 '-dihydroxy-3,3 '-dimethoxylignan-9,9 '-diyl diacetate (7)] and a dimer of a benzophenanthridine and 2-quinoline [holstzianoquinoline (6)] were isolated. The CH2Cl2/MeOH (1:1) extract of the root bark afforded 1, 3-6, 8, chelerythridimerine (9) and 9-demethyloxychelerythrine (10). Holstzianoquinoline (6) is new, and is the second dimer linked by a C-C bond of a benzophenanthridine and a 2-quinoline reported thus far. The compounds were identified based on spectroscopic evidence. Amongst five compounds (1-5) tested against two strains of P. falciparum, nitidine (IC50 0.11 +/- 0.01 mu g/mL against W2 and D6 strains) and norchelerythrine (IC50 value of 0.15 +/- 0.01 mu g/mL against D6 strain) were the most active.
KW  - Antiplasmodial
KW  - benzophenanthridine alkaloid
KW  - holstzianoquinoline;
KW  - rutaceae
KW  - Zanthoxylum holstzianum
Y1  - 2022
U6  - https://doi.org/10.1080/14786419.2022.2034810
SN  - 1478-6419
SN  - 1478-6427
VL  - 37
IS  - 13
SP  - 2161
EP  - 2171
PB  - Taylor & Francis
CY  - London [u.a.]
ER  - 
TY  - JOUR
A1  - Kreuzer, Lucas
A1  - Lindenmeir, Christoph
A1  - Geiger, Christina
A1  - Widmann, Tobias
A1  - Hildebrand, Viet
A1  - Laschewsky, André
A1  - Papadakis, Christine M.
A1  - Müller-Buschbaum, Peter
T1  - Poly(sulfobetaine) versus poly(N-isopropylmethacrylamide)
BT  - co-nonsolvency-type behavior of thin films in a water/methanol atmosphere
JF  - Macromolecules : a publication of the American Chemical Society
N2  - The swelling and co-nonsolvency behaviors in pure H2O and in a mixed H2O/CH3OH vapor atmosphere of two different polar, water-soluble polymers in thin film geometry are studied in situ. Films of a zwitterionic poly(sulfobetaine), namely, poly[3-((2-(methacryloyloxy)ethyl)dimethylammonio) propane-1-sulfonate] (PSPE), and a polar nonionic polymer, namely, poly(N-isopropylmethacrylamide) (PNIPMAM), are investigated in real time by spectral reflectance (SR) measurements and Fourier transform infrared (FTIR) spectroscopy. Whereas PSPE is insoluble in methanol, PNIPMAM is soluble but exhibits cononsolvency behavior in water/methanol mixtures. First, the swelling of PSPE and PNIPMAM thin films in H2O vapor is followed. Subsequently, CH3OH is added to the vapor atmosphere, and its contracting effect on the water-swollen films is monitored, revealing a co-nonsolvency-type behavior for PNIPMAM and PSPE. SR measurements indicate that PSPE and PNIPMAM behave significantly different during the H2O swelling and subsequent exposure to CH3OH, not only with respect to the amounts of absorbed water and CH3OH, but also to the cosolvent-induced contraction mechanisms. While PSPE thin films exhibit an abrupt one-step contraction, the contraction of PNIPMAM thin films occurs in two steps. FTIR studies corroborate these findings on a molecular scale and reveal the role of the specific functional groups, both during the swelling and the cosolvent-induced switching of the solvation state.
Y1  - 2021
U6  - https://doi.org/10.1021/acs.macromol.0c02281
SN  - 0024-9297
SN  - 1520-5835
VL  - 54
IS  - 3
SP  - 1548
EP  - 1556
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - GEN
A1  - Kar, Manaswita
A1  - Körzdörfer, Thomas
T1  - Computational high throughput screening of inorganic cation based halide perovskites for perovskite only tandem solar cells
T2  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - We search for homovalent alternatives for A, B, and X-ions in ABX(3) type inorganic halide perovskites suitable for tandem solar cell applications. We replace the conventional A-site organic cation CH3NH3, by 3 inorganic cations, Cs, K, and Rb, and the B site consists of metals; Cd, Hg, Ge, Pb, and Sn This work is built on our previous high throughput screening of hybrid perovskite materials (Kar et al 2018 J. Chem. Phys. 149, 214701). By performing a systematic screening study using Density Functional Theory (DFT) methods, we found 11 suitable candidates; 2 Cs-based, 3 K-based and 6 Rb-based that are suitable for tandem solar cell applications.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1438 
KW  - inorganic perovskites
KW  - tandem solar cells
KW  - density functional theory
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-516831
SN  - 1866-8372
IS  - 5
ER  - 
TY  - GEN
A1  - Deng, Zijun
A1  - Wang, Weiwei
A1  - Xua, Xun
A1  - Gould, Oliver E. C.
A1  - Kratz, Karl
A1  - Ma, Nan
A1  - Lendlein, Andreas
T1  - Polymeric sheet actuators with programmable bioinstructivity
T2  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe
N2  - Stem cells are capable of sensing and processing environmental inputs, converting this information to output a specific cell lineage through signaling cascades. Despite the combinatorial nature of mechanical, thermal, and biochemical signals, these stimuli have typically been decoupled and applied independently, requiring continuous regulation by controlling units. We employ a programmable polymer actuator sheet to autonomously synchronize thermal and mechanical signals applied to mesenchymal stem cells (MSC5). Using a grid on its underside, the shape change of polymer sheet, as well as cell morphology, calcium (Ca2+) influx, and focal adhesion assembly, could be visualized and quantified. This paper gives compelling evidence that the temperature sensing and mechanosensing of MSC5 are interconnected via intracellular Ca2+. Up-regulated Ca2+ levels lead to a remarkable alteration of histone H3K9 acetylation and activation of osteogenic related genes. The interplay of physical, thermal, and biochemical signaling was utilized to accelerate the cell differentiation toward osteogenic lineage. The approach of programmable bioinstructivity provides a fundamental principle for functional biomaterials exhibiting multifaceted stimuli on differentiation programs. Technological impact is expected in the tissue engineering of periosteum for treating bone defects.
T3  - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1441 
KW  - reversible shape-memory actuator
KW  - mesenchymal stem cells
KW  - calcium influx
KW  - HDAC1
KW  - RUNX2
Y1  - 2020
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-515490
SN  - 1866-8372
IS  - 4
ER  - 
TY  - JOUR
A1  - Deng, Zijun
A1  - Wang, Weiwei
A1  - Xua, Xun
A1  - Gould, Oliver E. C.
A1  - Kratz, Karl
A1  - Ma, Nan
A1  - Lendlein, Andreas
T1  - Polymeric sheet actuators with programmable bioinstructivity
JF  - PNAS
N2  - Stem cells are capable of sensing and processing environmental inputs, converting this information to output a specific cell lineage through signaling cascades. Despite the combinatorial nature of mechanical, thermal, and biochemical signals, these stimuli have typically been decoupled and applied independently, requiring continuous regulation by controlling units. We employ a programmable polymer actuator sheet to autonomously synchronize thermal and mechanical signals applied to mesenchymal stem cells (MSC5). Using a grid on its underside, the shape change of polymer sheet, as well as cell morphology, calcium (Ca2+) influx, and focal adhesion assembly, could be visualized and quantified. This paper gives compelling evidence that the temperature sensing and mechanosensing of MSC5 are interconnected via intracellular Ca2+. Up-regulated Ca2+ levels lead to a remarkable alteration of histone H3K9 acetylation and activation of osteogenic related genes. The interplay of physical, thermal, and biochemical signaling was utilized to accelerate the cell differentiation toward osteogenic lineage. The approach of programmable bioinstructivity provides a fundamental principle for functional biomaterials exhibiting multifaceted stimuli on differentiation programs. Technological impact is expected in the tissue engineering of periosteum for treating bone defects.
KW  - reversible shape-memory actuator
KW  - mesenchymal stem cells
KW  - calcium influx
KW  - HDAC1
KW  - RUNX2
Y1  - 2020
U6  - https://doi.org/10.1073/pnas.1910668117
SN  - 1091-6490
VL  - 117
IS  - 4
SP  - 1895
EP  - 1901
PB  - National Academy of Sciences
CY  - Washington, DC
ER  - 
TY  - JOUR
A1  - Saretia, Shivam
A1  - Machatschek, Rainhard Gabriel
A1  - Lendlein, Andreas
T1  - Degradation kinetics of oligo(ε-caprolactone) ultrathin films
BT  - Influence of crystallinity
JF  - MRS advances : a journal of the Materials Research Society (MRS)
N2  - The potential of using crystallinity as morphological parameter to control polyester degradation in acidic environments is explored in ultrathin films by Langmuir technique. Films of hydroxy or methacrylate end-capped oligo(epsilon-caprolactone) (OCL) are prepared at the air-water interface as a function of mean molecular area (MMA). The obtained amorphous, partially crystalline or highly crystalline ultrathin films of OCL are hydrolytically degraded at pH similar to 1.2 on water surface or on silicon surface as-transferred films. A high crystallinity reduces the hydrolytic degradation rate of the films on both water and solid surfaces. Different acceleration rates of hydrolytic degradation of semi-crystalline films are achieved either by crystals complete melting, partially melting, or by heating them below their melting temperatures. Semi-crystalline OCL films transferred via water onto a solid surface retain their crystalline morphology, degrade in a controlled manner, and are of interest as thermoswitchable coatings for cell substrates and medical devices.
Y1  - 2021
U6  - https://doi.org/10.1557/s43580-021-00067-4
SN  - 2059-8521
VL  - 6
IS  - 33
SP  - 790
EP  - 795
PB  - Springer Nature Switzerland AG
CY  - Cham
ER  - 
TY  - JOUR
A1  - Yue, Yanhua
A1  - Melani, Giacomo
A1  - Kirsch, Harald
A1  - Paarmann, Alexander
A1  - Saalfrank, Peter
A1  - Campen, Richard Kramer
A1  - Tong, Yujin
T1  - Structure and Reactivity of a-Al2O3(0001) Surfaces: How Do Al-I and Gibbsite-like Terminations Interconvert?
JF  - The journal of physical chemistry / publ. weekly by the American Chemical Society. C, Energy, materials, and catalysis
N2  - The alpha-Al2O3(0001) surface has been extensively studied because of its significance in both fundamental research and application. Prior work suggests that in ultra-high-vacuum (UHV), in the absence of water, the so-called Al-I termination is thermodynamically favored, while in ambient, in contact with liquid water, a Gibbsite-like layer is created. While the view of the alpha- Al2O3(0001)/H2O(l) interface appears relatively clear in theory, experimental characterization of this system has resulted in estimates of surface acidity, i.e., isoelectric points, that differ by 4 pH units and surface structure that in some reports has non-hydrogen-bonded surface aluminol (Al-OH) groups and in others does not. In this study, we employed vibrational sum frequency spectroscopy (VSFS) and density functional theory (DFT) simulation to study the surface phonon modes of the differently terminated alpha-Al2O3(0001) surfaces in both UHV and ambient. We find that, on either water dosing of the Al-I in UHV or heat-induced dehydroxylation of the Gibbsite-like in ambient, the surfaces do not interconvert. This observation offers a new explanation for disagreements in prior work on the alpha-Al2O3(0001)/liquid water interface -different preparation methods may create surfaces that do not interconvert-and shows that the surface phonon spectral response offers a novel probe of interfacial hydrogen bonding structure.
Y1  - 2022
U6  - https://doi.org/10.1021/acs.jpcc.2c03743
SN  - 1932-7447
SN  - 1932-7455
VL  - 126
IS  - 31
SP  - 13467
EP  - 13476
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Tarazona Lizcano, Natalia Andrea
A1  - Machatschek, Rainhard Gabriel
A1  - Balcucho, Jennifer
A1  - Castro-Mayorga, Jinneth Lorena
A1  - Saldarriaga, Juan Francisco
A1  - Lendlein, Andreas
T1  - Opportunities and challenges for integrating the development of sustainable polymer materials within an international circular (bio)economy concept
JF  - MRS energy & sustainability : science & technology & socio-economics & policy
N2  - The production and consumption of commodity polymers have been an indispensable part of the development of our modern society. Owing to their adjustable properties and variety of functions, polymer-based materials will continue playing important roles in achieving the Sustainable Development Goals (SDG)s, defined by the United Nations, in key areas such as healthcare, transport, food preservation, construction, electronics, and water management. Considering the serious environmental crisis, generated by increasing consumption of plastics, leading-edge polymers need to incorporate two types of functions: Those that directly arise from the demands of the application (e.g. selective gas and liquid permeation, actuation or charge transport) and those that enable minimization of environmental harm, e.g., through prolongation of the functional lifetime, minimization of material usage, or through predictable disintegration into non-toxic fragments. Here, we give examples of how the incorporation of a thoughtful combination of properties/functions can enhance the sustainability of plastics ranging from material design to waste management. We focus on tools to measure and reduce the negative impacts of plastics on the environment throughout their life cycle, the use of renewable sources for their synthesis, the design of biodegradable and/or recyclable materials, and the use of biotechnological strategies for enzymatic recycling of plastics that fits into a circular bioeconomy. Finally, we discuss future applications for sustainable plastics with the aim to achieve the SDGs through international cooperation. <br /> Leading-edge polymer-based materials for consumer and advanced applications are necessary to achieve sustainable development at a global scale. It is essential to understand how sustainability can be incorporated in these materials via green chemistry, the integration of bio-based building blocks from biorefineries, circular bioeconomy strategies, and combined smart and functional capabilities.
KW  - biomaterial
KW  - degradable
KW  - functional
KW  - life cycle assessment
KW  - renewable
KW  - sustainability
Y1  - 2022
U6  - https://doi.org/10.1557/s43581-021-00015-7
SN  - 2329-2229
SN  - 2329-2237
VL  - 9
IS  - 1
SP  - 28
EP  - 34
PB  - Springer Nature
CY  - London
ER  - 
TY  - JOUR
A1  - Folikumah, Makafui Y.
A1  - Behl, Marc
A1  - Lendlein, Andreas
T1  - Reaction behaviour of peptide-based single thiol-thioesters exchange reaction substrate in the presence of externally added thiols
JF  - MRS communications / a publication of the Materials Research Society
N2  - Identification of patterns in chemical reaction pathways aids in the effective design of molecules for specific applications. Here, we report on model reactions with a water-soluble single thiol-thioester exchange (TTE) reaction substrate, which was designed taking in view biological and medical applications. This substrate consists of the thio-depsipeptide, Ac-Pro-Leu-Gly-SLeu-Leu-Gly-NEtSH (TDP) and does not yield foul-smelling thiol exchange products when compared with aromatic thiol containing single TTE substrates. TDP generates an alpha,omega-dithiol crosslinker in situ in a 'pseudo intramolecular' TTE. Competitive intermolecular TTE of TDP with externally added "basic" thiols increased the crosslinker concentration whilst "acidic" thiols decreased its concentration. TDP could potentially enable in situ bioconjugation and crosslinking applications.
KW  - Biomaterials
KW  - Biomimetic
KW  - Mass spectrometry
KW  - Nuclear magnetic resonance
KW  - (NMR)
Y1  - 2021
U6  - https://doi.org/10.1557/s43579-021-00041-z
SN  - 2159-6859
SN  - 2159-6867
VL  - 11
IS  - 4
SP  - 402
EP  - 410
PB  - Springer
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Kleinpeter, Erich
A1  - Heydenreich, Matthias
A1  - Shainyan, Bagrat A.
T1  - At the experimental limit of the NMR conformational analysis
BT  - Si-29 and C-13 NMR study of the conformational equilibrium of 1-phenyl-1-tert-butylsilacyclohexane
JF  - Organic letters
N2  - The low temperature (95 K) NMR study of 1-Ph-1-t-Bu-silacyclohexane (1) showed the conformational equilibrium to be extremely one-sided toward thePh(ax),t-Bueq conformer. The barrier to interconversion has been measured (4.2-4.6 kcal/mol) and the conformational equilibrium [Delta nu = 1990.64 ppm (Si-29), 618.9 ppm (C-13), 1-Ph-ax:1-Pheq = (95.6-96.6%):(3.4-4.4%), K = 25 +/- 3, Delta G degrees = -RT ln K = 0.58-0.63 kcal/mol] analyzed. The assignment and quantification of the NMR signals is supported by MP2 and DFT calculations.
Y1  - 2021
U6  - https://doi.org/10.1021/acs.orglett.0c03878
SN  - 1523-7060
SN  - 1523-7052
VL  - 23
IS  - 2
SP  - 405
EP  - 409
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Mullan, Thomas
A1  - Maschio, Lorenzo
A1  - Saalfrank, Peter
A1  - Usvyat, Denis
T1  - Reaction barriers on non-conducting surfaces beyond periodic local MP2
BT  - Diffusion of hydrogen on alpha-Al2O3 (0001) as a test case
JF  - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr
N2  - The quest for "chemical accuracy" is becoming more and more demanded in the field of structure and kinetics of molecules at solid surfaces. In this paper, as an example, we focus on the barrier for hydrogen diffusion on a alpha-Al2O3 (0001) surface, aiming for a couple cluster singles, doubles, and perturbative triples [CCSD(T)]-level benchmark. We employ the density functional theory (DFT) optimized minimum and transition state structures reported by Heiden, Usvyat, and Saalfrank [J. Phys. Chem. C 123, 6675 (2019)]. The barrier is first evaluated at the periodic Hartree-Fock and local Moller-Plesset second-order perturbation (MP2) level of theory. The possible sources of errors are then analyzed, which includes basis set incompleteness error, frozen core, density fitting, local approximation errors, as well as the MP2 method error. Using periodic and embedded fragment models, corrections to these errors are evaluated. In particular, two corrections are found to be non-negligible (both from the chemical accuracy perspective and at the scale of the barrier value of 0.72 eV): the correction to the frozen core-approximation of 0.06 eV and the CCSD(T) correction of 0.07 eV. Our correlated wave function results are compared to barriers obtained from DFT. Among the tested DFT functionals, the best performing for this barrier is B3LYP-D3.
Y1  - 2022
U6  - https://doi.org/10.1063/5.0082805
SN  - 0021-9606
SN  - 1089-7690
VL  - 156
IS  - 7
PB  - AIP Publishing
CY  - Melville
ER  - 
TY  - THES
A1  - Martínez Guajardo, Alejandro
T1  - New zwitterionic polymers for antifouling applications
T1  - Neue zwitterionische Polymere für Antifouling-Anwendungen
N2  - The remarkable antifouling properties of zwitterionic polymers in controlled environments are often counteracted by their delicate mechanical stability. In order to improve the mechanical stabilities of zwitterionic hydrogels, the effect of increased crosslinker densities was thus explored. In a first approach, terpolymers of zwitterionic monomer 3-[N -2(methacryloyloxy)ethyl-N,N-dimethyl]ammonio propane-1-sulfonate (SPE), hydrophobic monomer butyl methacrylate (BMA), and photo-crosslinker 2-(4-benzoylphenoxy)ethyl methacrylate (BPEMA) were synthesized. Thin hydrogel coatings of the copolymers were then produced and photo-crosslinked. Studies of the swollen hydrogel films showed that not only the mechanical stability but also, unexpectedly, the antifouling properties were improved by the presence of hydrophobic BMA units in the terpolymers.

Based on the positive results shown by the amphiphilic terpolymers and in order to further test the impact that hydrophobicity has on both the antifouling properties of zwitterionic hydrogels and on their mechanical stability, a new amphiphilic zwitterionic methacrylic monomer, 3-((2-(methacryloyloxy)hexyl)dimethylammonio)propane-1-sulfonate (M1), was synthesized in good yields in a multistep synthesis. Homopolymers of M1 were obtained by free-radical polymerization. Similarly, terpolymers of M1, zwitterionic monomer SPE, and photo-crosslinker BPEMA were synthesized by free-radical copolymerization and thoroughly characterized, including its solubilities in selected solvents.

Also, a new family of vinyl amide zwitterionic monomomers, namely 3-(dimethyl(2-(N -vinylacetamido)ethyl)ammonio)propane-1-sulfonate (M2), 4-(dimethyl(2-(N-vinylacetamido)ethyl)ammonio)butane-1-sulfonate (M3), and 3-(dimethyl(2-(N-vinylacetamido)ethyl)ammonio)propyl sulfate (M4), together with the new photo-crosslinker 4-benzoyl-N-vinylbenzamide (M5) that is well-suited for copolymerization with vinylamides, are introduced within the scope of the present work. The monomers are synthesized with good yields developing a multistep synthesis. Homopolymers of the new vinyl amide zwitterionic monomers are obtained by free-radical polymerization and thoroughly characterized. From the solubility tests, it is remarkable that the homopolymers produced are fully soluble in water, evidence of their high hydrophilicity. Copolymerization of the vinyl amide zwitterionic monomers, M2, M3, and M4 with the vinyl amide photo-crosslinker M5 proved to require very specific polymerization conditions. Nevertheless, copolymers were successfully obtained by free-radical copolymerization under appropriate conditions.

Moreover, in an attempt to mitigate the intrinsic hydrophobicity introduced in the copolymers by the photo-crosslinkers, and based on the proven affinity of quaternized diallylamines to copolymerize with vinyl amides, a new quaternized diallylamine sulfobetaine photo-crosslinker 3-(diallyl(2-(4-benzoylphenoxy)ethyl)ammonio)propane-1-sulfonate (M6) is synthesized. However, despite a priori promising copolymerization suitability, copolymerization with the vinyl amide zwitterionic monomers could not be achieved.
N2  - Die hervorragenden Antifouling-Eigenschaften zwitterionischer Polymere in kontrollierten Bedingungen werden häufig durch ihre geringe mechanische Stabilität beeinträchtigt. Um die mechanische Eigenschaften zwitterionischer Hydrogele zu verbessern, wurde daher der Effekt einer erhöhten Vernetzungsdichte untersucht. In einem ersten Ansatz wurden Terpolymere aus dem zwitterionischen Monomer 3-[N -2(Methacryloyloxy)ethyl-N,N-dimethyl]ammonio propan-1-sulfonat (SPE), dem hydrophoben Monomer Butylmethacrylat (BMA) und dem Photovernetzer 2-(4-Benzoylphenoxy)ethylmethacrylat (BPEMA) synthetisiert. Daraufhin wurden dünne Beschichtungen der Copolymere hergestellt und photovernetzt. Die Untersuchung der gequollenen Hydrogelfilme zeigte, dass nicht nur die mechanischen Eigenschaften, sondern überraschenderweise auch die Antifouling-Eigenschaften der Hydrogele durch den Einbau von hydrophoben BMA-Einheiten in die Terpolymere verbessert wurden. 

Aufgrund der positiven Ergebnisse der amphiphilen Terpolymere und um die Auswirkungen der Hydrophobie sowohl auf die Antifouling- als auch auf die mechanische Eigenschaften der zwitterionischen Hydrogele zu testen, wurde ein neues amphiphiles zwitterionisches Methacrylat, nämlich 3-((2-(Methacryloyloxy)hexyl)dimethylammonio)propan-1-sulfonat (M1), in guter Ausbeute synthetisiert. Homopolymere von M1 wurden durch radikalische Polymerisation erhalten. In ähnlicher Weise wurden Terpolymere aus M1, dem zwitterionischen Monomer SPE und dem Photovernetzer BPEMA durch radikalische Copolymerisation synthetisiert und gründlich charakterisiert, einschließlich ihrer Löslichkeiten in ausgewählten Lösungsmitteln. 

Außerdem wurde im Rahmen der vorliegenden Arbeit eine neue Familie von zwitterionischen Vinylamidmonomeren, nämlich 3-(Dimethyl(2-(N-vinylacetamido)ethyl)ammonio)propan-1-sulfonat (M2), 4-(Dimethyl(2-(N -vinylacetamido)ethyl)ammonio)butan-1-sulfonat (M3) und 3-(Dimethyl(2-(N -vinylacetamido)ethyl)ammonio)propylsulfat (M4), zusammen mit einem geeigneten Vinylamid-Photovernetzer, nämlich 4-Benzoyl-N -vinylbenzamide (M5) entwickelt. Die Monomere wurden in einer Mehrstufen-Synthese mit guten Ausbeuten synthetisiert. Homopolymere der neuen zwitterionischen Vinylamidmonomere wurden durch radikalische Polymerisation erhalten und eingehend charakterisiert. Die Löslichkeitstests zeigen, dass die hergestellten Homopolymere bemerkenswerterweise vollständig in reinem Wasser löslich sind, was ihre hohe Hydrophilie beweist. Die Copolymerisation der zwitterionischen Vinylamidmonomere M2, M3 und M4 mit dem Vinylamid-Photovernetzer M5 erwies sich als schwierig. Die Copolymere lassen sich dennoch unter sehr spezifische Bedingungen durch radikalische Copolymerisation herstellen. 

Des Weiteren, um die durch die Photovernetzer in die Copolymere eingebrachte inhärente Hydrophobie zu mindern und aufgrund ihrer nachgewiesenen Affinität zur Copolymerisation mit Vinylamiden, wurde ein neuer quaternisierter Diallylaminsulfobetain-Photovernetzer 3-(Diallyl(2-(4-benzoylphenoxy)ethyl)ammonio)propan-1-sulfonat (M6) synthetisiert. Trotz a priori vielversprechender Copolymerisationseignung konnte jedoch keine Copolymerisation mit den zwitterionischen Vinylamidmonomeren erreicht werden.
KW  - antifouling
KW  - Antifouling
KW  - copolymers
KW  - Copolymere
KW  - hydrogels
KW  - Hydrogele
KW  - zwitterions
KW  - Zwitterionen
KW  - synthesis
KW  - Synthese
Y1  - 2024
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-626820
ER  - 
TY  - JOUR
A1  - Mawire, Phillip
A1  - Mozirandi, Winnie
A1  - Heydenreich, Matthias
A1  - Chi, Godloves Fru
A1  - Mukanganyama, Stanley
T1  - Isolation and antimicrobial activities of phytochemicals from Parinari curatellifolia (Chrysobalanaceae)
JF  - Advances in pharmacological and pharmaceutical sciences
N2  - The widespread use of antimicrobial agents to treat infectious diseases has led to the emergence of antibiotic resistant pathogens. Plants have played a central role in combating many ailments in humans, and Parinari curatellifolia has been used for medicinal purposes. Seven extracts from P. curatellifolia leaves were prepared using serial exhaustive extraction of nonpolar to polar solvents. The microbroth dilution method was used to evaluate antimicrobial bioactivities of extracts. Five of the extracts were significantly active against at least one test microbe. Mycobacterium smegmatis was the most susceptible to most extracts. The methanol and ethanol extracts were the most active against M. smegmatis with an MIC of 25 mu g/mL. The hexane extract was the most active against Candida krusei with an MIC of 25 mu g/mL. None of the extracts significantly inhibited growth of Klebsiella pneumoniae and Staphylococcus aureus. Active extracts were selected for fractionation and isolation of pure compounds using gradient elution column chromatography. TLC analyses was carried out for pooling fractions of similar profiles. A total of 43 pools were obtained from 428 fractions. Pools 7 and 10 were selected for further isolation of single compounds. Four compounds, Pc4963r, Pc4962w, Pc6978p, and Pc6978o, were isolated. Evaluation of antimicrobial activities of Pc4963r, Pc4962w, and Pc6978p showed that the compounds were most active against C. krusei with MFC values ranging from 50 to 100 mu g/mL. Only Pc6978p was shown to be pure. Using spectroscopic analyses, the structure of Pc6978p was determined to be beta-sitosterol. The antifungal effects of beta-sitosterol were evaluated against C. krusei in vitro and on fabrics. Results showed that beta-sitosterol reduced the growth of C. krusei attached to Mendy fabric by 83%. Therefore, P. curatellifolia can be a source of lead compounds for prospective development of novel antimicrobial agents. Further work needs to be done to improve the antifungal activity of the isolated compound using quantitative structure-activity relationships.
Y1  - 2021
U6  - https://doi.org/10.1155/2021/8842629
SN  - 2633-4682
SN  - 2633-4690
PB  - Hindawi
CY  - London
ER  - 
TY  - JOUR
A1  - Bekir, Marek
A1  - Jelken, Joachim
A1  - Jung, Se-Hyeong
A1  - Pich, Andrij
A1  - Pacholski, Claudia
A1  - Kopyshev, Alexey
A1  - Santer, Svetlana
T1  - Dual responsiveness of microgels induced by single light stimulus
JF  - Applied physics letters
N2  - We report on the multiple response of microgels triggered by a single optical stimulus. Under irradiation, the volume of the microgels is reversibly switched by more than 20 times. The irradiation initiates two different processes: photo-isomerization of the photo-sensitive surfactant, which forms a complex with the anionic microgel, rendering it photo-responsive; and local heating due to a thermo-plasmonic effect within the structured gold layer on which the microgel is deposited. The photo-responsivity is related to the reversible accommodation/release of the photo-sensitive surfactant depending on its photo-isomerization state, while the thermo-sensitivity is intrinsically built in. We show that under exposure to green light, the thermo-plasmonic effect generates a local hot spot in the gold layer, resulting in the shrinkage of the microgel. This process competes with the simultaneous photo-induced swelling. Depending on the position of the laser spot, the spatiotemporal control of reversible particle shrinking/swelling with a predefined extent on a per-second base can be implemented.
Y1  - 2021
U6  - https://doi.org/10.1063/5.0036376
SN  - 0003-6951
SN  - 1077-3118
VL  - 118
IS  - 9
PB  - American Institute of Physics
CY  - Melville
ER  - 
TY  - JOUR
A1  - Hoffmann, Falk
A1  - Machatschek, Rainhard Gabriel
A1  - Lendlein, Andreas
T1  - Analytical model and Monte Carlo simulations of polymer degradation with improved chain cut statistics
JF  - Journal of materials research : JMR
N2  - The degradation of polymers is described by mathematical models based on bond cleavage statistics including the decreasing probability of chain cuts with decreasing average chain length. We derive equations for the degradation of chains under a random chain cut and a chain end cut mechanism, which are compared to existing models. The results are used to predict the influence of internal molecular parameters. It is shown that both chain cut mechanisms lead to a similar shape of the mass or molecular mass loss curve. A characteristic time is derived, which can be used to extract the maximum length of soluble fragments l of the polymer. We show that the complete description is needed to extract the degradation rate constant k from the molecular mass loss curve and that l can be used to design polymers that lose less mechanical stability before entering the mass loss phase.
KW  - Modeling
KW  - Degradable
KW  - Polymer
KW  - Molecular weight
KW  - Simulation
Y1  - 2022
U6  - https://doi.org/10.1557/s43578-022-00495-4
SN  - 0884-2914
SN  - 2044-5326
VL  - 37
IS  - 5
SP  - 1093
EP  - 1101
PB  - Springer
CY  - Heidelberg
ER  - 
TY  - JOUR
A1  - Neffe, Axel T.
A1  - Löwenberg, Candy
A1  - Lendlein, Andreas
T1  - Hydrogel networks by aliphatic dithiol Michael addition to glycidylmethacrylated gelatin
JF  - MRS advances : a journal of the Materials Research Society (MRS)
N2  - Functionalization of gelatin with glycidylmethacrylate (GMA-gelatin) enables network formation employing the double bond, so that the reaction is orthogonal to the inherent functional groups in the biomacromolecule. Here, network formation by crosslinking of GMA-gelatin with hexane 1,6-dithiol or nonane 1,9-dithiol to tailor properties and enable a shape-memory effect is shown by H-1 NMR and FT-IR spectroscopy. Hydrogel swelling (460-1900 vol%) and mechanical properties (Young's modulus E = 59-512 kPa, elongation at break epsilon(b) = 44-127%) depended on the molecular composition of the networks and temperature. Increased crosslinker length, thiol:methacrylate molar ratio, and precursor concentrations led to denser networks. Change of properties with temperature suggested adoption of triple helices by gelatin chains, forming physical netpoints at lower temperatures (< 20 degrees C). However, the limited freedom of the gelatin chains to move allowed only a minimal extent of triple helices formation, as it became apparent from the related signal in wide-angle X-ray scattering and the thermal transition associated to triple helices in some networks by DSC. The presented strategy is likely transferable to other biomacromolecules, and the results suggest that too short crosslinkers may result in a significant amount of grafting rather than network formation.
Y1  - 2021
U6  - https://doi.org/10.1557/s43580-021-00136-8
SN  - 2059-8521
VL  - 6
IS  - 33
SP  - 796
EP  - 800
PB  - Springer Nature Switzerland AG
CY  - Cham
ER  - 
TY  - JOUR
A1  - Lau, Skadi
A1  - Maier, Anna
A1  - Braune, Steffen
A1  - Gossen, Manfred
A1  - Lendlein, Andreas
T1  - Effect of endothelial culture medium composition on platelet responses to polymeric biomaterials
JF  - International journal of molecular sciences
N2  - Near-physiological in vitro thrombogenicity test systems for the evaluation of blood-contacting endothelialized biomaterials requires co-cultivation with platelets (PLT). However, the addition of PLT has led to unphysiological endothelial cell (EC) detachment in such in vitro systems. A possible cause for this phenomenon may be PLT activation triggered by the applied endothelial cell medium, which typically consists of basal medium (BM) and nine different supplements. To verify this hypothesis, the influence of BM and its supplements was systematically analyzed regarding PLT responses. For this, human platelet rich plasma (PRP) was mixed with BM, BM containing one of nine supplements, or with BM containing all supplements together. PLT adherence analysis was carried out in six-channel slides with plasma-treated cyclic olefin copolymer (COC) and poly(tetrafluoro ethylene) (PTFE, as a positive control) substrates as part of the six-channel slides in the absence of EC and under static conditions. PLT activation and aggregation were analyzed using light transmission aggregometry and flow cytometry (CD62P). Medium supplements had no effect on PLT activation and aggregation. In contrast, supplements differentially affected PLT adherence, however, in a polymer- and donor-dependent manner. Thus, the use of standard endothelial growth medium (BM + all supplements) maintains functionality of PLT under EC compatible conditions without masking the differences of PLT adherence on different polymeric substrates. These findings are important prerequisites for the establishment of a near-physiological in vitro thrombogenicity test system assessing polymer-based cardiovascular implant materials in contact with EC and PLT.
KW  - cyclic olefin copolymer
KW  - poly(tetrafluoroethylene)
KW  - endothelial cells
KW  - platelets
KW  - in vitro thrombogenicity testing
Y1  - 2021
U6  - https://doi.org/10.3390/ijms22137006
SN  - 1422-0067
SN  - 1661-6596
VL  - 22
IS  - 13
PB  - Molecular Diversity Preservation International
CY  - Basel
ER  - 
TY  - JOUR
A1  - Schönemann, Eric
A1  - Koc, Julian
A1  - Karthäuser, Jana
A1  - Özcan, Onur
A1  - Schanzenbach, Dirk
A1  - Schardt, Lisa
A1  - Rosenhahn, Axel
A1  - Laschewsky, André
T1  - Sulfobetaine methacrylate polymers of unconventional polyzwitterion architecture and their antifouling properties
JF  - Biomacromolecules : an interdisciplinary journal focused at the interface of polymer science and the biological sciences
N2  - Combining high hydrophilicity with charge neutrality, polyzwitterions are intensely explored for their high biocompatibility and low-fouling properties. Recent reports indicated that in addition to charge neutrality, the zwitterion's segmental dipole orientation is an important factor for interacting with the environment. Accordingly, a series of polysulfobetaines with a novel architecture was designed, in which the cationic and anionic groups of the zwitterionic moiety are placed at equal distances from the backbone. They were investigated by in vitro biofouling assays, covering proteins of different charges and model marine organisms. All polyzwitterion coatings reduced the fouling effectively compared to model polymer surfaces of poly(butyl methacrylate), with a nearly equally good performance as the reference polybetaine poly(3-(N-(2-(methacryloyloxy)ethyl)-N,N-dimethylammonio)propanesulfonate). The specific fouling resistance depended on the detailed chemical structure of the polyzwitterions. Still, while clearly affecting the performance, the precise dipole orientation of the sulfobetaine group in the polyzwitterions seems overall to be only of secondary importance for their antifouling behavior.
Y1  - 2021
U6  - https://doi.org/10.1021/acs.biomac.0c01705
SN  - 1525-7797
SN  - 1526-4602
VL  - 22
IS  - 4
SP  - 1494
EP  - 1508
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Ihlenburg, Ramona
A1  - Mai, Tobias
A1  - Thünemann, Andreas F.
A1  - Baerenwald, Ruth
A1  - Saalwächter, Kay
A1  - Koetz, Joachim
A1  - Taubert, Andreas
T1  - Sulfobetaine hydrogels with a complex multilength-scale hierarchical structure
JF  - The journal of physical chemistry : B, Condensed matter, materials, surfaces, interfaces & biophysical chemistry
N2  - Hydrogels with a hierarchical structure were prepared from a new highly water-soluble crosslinker N,N,N',N'-tetramethyl-N,N'-bis(2-ethylmethacrylate)-propyl-1,3-diammonium dibromide and from the sulfobetaine monomer 2-(N-3-sulfopropyl-N,N-dimethyl ammonium)ethyl methacrylate. The free radical polymerization of the two compounds is rapid and yields near-transparent hydrogels with sizes up to 5 cm in diameter. Rheology shows a clear correlation between the monomer-to-crosslinker ratio and the storage and loss moduli of the hydrogels. Cryo-scanning electron microscopy, low-field nuclear magnetic resonance (NMR) spectroscopy, and small-angle X-ray scattering show that the gels have a hierarchical structure with features spanning the nanometer to the sub-millimeter scale. The NMR study is challenged by the marked inhomogeneity of the gels and the complex chemical structure of the sulfobetaine monomer. NMR spectroscopy shows how these complications can be addressed via a novel fitting approach that considers the mobility gradient along the side chain of methacrylate-based monomers.
KW  - Defects
KW  - Hydrogels
KW  - Nuclear magnetic resonance spectroscopy
KW  - Scattering
KW  - X-ray scattering
Y1  - 2021
U6  - https://doi.org/10.1021/acs.jpcb.0c10601
SN  - 1520-6106
SN  - 1520-5207
VL  - 125
IS  - 13
SP  - 3398
EP  - 3408
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Lau, Skadi
A1  - Gossen, Manfred
A1  - Lendlein, Andreas
A1  - Jung, Friedrich
T1  - Differential sensitivity of assays for determining vein endothelial cell senescence
JF  - Clinical hemorheology and microcirculation : blood flow and vessels
N2  - In vivo endothelialization of polymer-based cardiovascular implant materials is a promising strategy to reduce the risk of platelet adherence and the subsequent thrombus formation and implant failure. However, endothelial cells from elderly patients are likely to exhibit a senescent phenotype that may counteract endothelialization. The senescence status of cells should therefore be investigated prior to implantation of devices designed to be integrated in the blood vessel wall. Here, human umbilical vein endothelial cells (HUVEC) were cultivated up to passage (P) 4, 10 and 26/27 to determine the population doubling time and the senescence status by four different methods. Determination of the senescence-associated beta-galactosidase activity (SA-beta-Gal) was carried out by colorimetric staining and microscopy (i), as well as by photometric quantification (ii), and the expression of senescence-associated nuclear proteins p16 and p21 as well as the proliferation marker Ki67 was assessed by immunostaining (iii), and by flow cytometry (iv). The population doubling time of P27-cells was remarkably greater (103 +/- 65 h) compared to P4-cells (24 +/- 3 h) and P10-cell (37 +/- 15 h). Among the four different methods tested, the photometric SA-beta-Gal activity assay and the flow cytometric determination of p16 and Ki67 were most effective in discriminating P27-cells from P4- and P10-cells. These methods combined with functional endothelial cell analyses might aid predictions on the performance of implant endothelialization in vivo.
KW  - Ageing
KW  - population doubling time
KW  - senescence-associated
KW  - beta-galactosidase
KW  - cell cycle inhibitors
KW  - p16
KW  - p21
KW  - Ki67
Y1  - 2022
U6  - https://doi.org/10.3233/CH-211294
SN  - 1386-0291
SN  - 1875-8622
VL  - 81
IS  - 3
SP  - 191
EP  - 203
PB  - IOS Press
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Zhang, Pengfei
A1  - Rešetič, Andraž
A1  - Behl, Marc
A1  - Lendlein, Andreas
T1  - Multifunctionality in polymer networks by dynamic of coordination bonds
JF  - Macromolecular chemistry and physics
N2  - The need for multifunctional materials is driven by emerging technologies and innovations, such as in the field of soft robotics and tactile or haptic systems, where minimizing the number of operational components is not only desirable, but can also be essential for realizing such devices. This study report on designing a multifunctional soft polymer material that can address a number of operating requirements such as solvent resistance, reshaping ability, self-healing capability, fluorescence stimuli-responsivity, and anisotropic structural functions. The numerous functional abilities are associated to rhodium(I)-phosphine coordination bonds, which in a polymer network act with their dynamic and non-covalently bonded nature as multifunctional crosslinks. Reversible aggregation of coordination bonds leads to changes in fluorescence emission intensity that responds to chemical or mechanical stimuli. The fast dynamics and diffusion of rhodium-phosphine ions across and through contacting areas of the material provide for reshaping and self-healing abilities that can be further exploited for assembly of multiple pieces into complex forms, all without any loss to material-sensing capabilities.
KW  - assembly capabilities
KW  - fluorescence stimuli‐ responsivity
KW  - multiple functions
KW  - reshaping abilities
KW  - rhodium(I)– phosphine
KW  - coordination bonds
KW  - solvent resistance
Y1  - 2021
U6  - https://doi.org/10.1002/macp.202000394
SN  - 1521-3935
VL  - 222
IS  - 3
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Göttlich, Richard
A1  - Graulich, Nicole
A1  - Huwer, Johannes
A1  - Banerji, Amitabh
T1  - Analog und digital
BT  - Chemieunterricht mit Potenzial
JF  - Chemie konkret : CHEMKON ; Forum für Unterricht und Didaktik
Y1  - 2022
U6  - https://doi.org/10.1002/ckon.202200046
SN  - 0944-5846
SN  - 1521-3730
VL  - 29
SP  - 182
EP  - 182
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Tartivel, Lucile
A1  - Blocki, Anna M.
A1  - Braune, Steffen
A1  - Jung, Friedrich
A1  - Behl, Marc
A1  - Lendlein, Andreas
T1  - An Inverse shape-memory hydrogel scaffold switching upon cooling in a tissue-tolerated temperature range
JF  - Advanced materials interfaces
N2  - Tissue reconstruction has an unmet need for soft active scaffolds that enable gentle loading with regeneration-directing bioactive components by soaking up but also provide macroscopic dimensional stability. Here microporous hydrogels capable of an inverse shape-memory effect (iSME) are described, which in contrast to classical shape-memory polymers (SMPs) recover their permanent shape upon cooling. These hydrogels are designed as covalently photo cross-linked polymer networks with oligo(ethylene glycol)-oligo(propylene glycol)-oligo(ethylene glycol) (OEG-OPG-OEG) segments. When heated after deformation, the OEG-OPG-OEG segments form micelles fixing the temporary shape. Upon cooling, the micelles dissociate again, the deformation is reversed and the permanent shape is obtained. Applicability of this iSME is demonstrated by the gentle loading of platelet-rich plasma (PRP) without causing any platelet activation during this process. PRP is highly bioactive and is widely acknowledged for its regenerative effects. Hence, the microporous inverse shape-memory hydrogel (iSMH) with a cooling induced pore-size effect represents a promising candidate scaffold for tissue regeneration for potential usage in minimally invasive surgery applications.
KW  - active scaffold
KW  - critical micellation temperature
KW  - hydrogel
KW  - inverse
KW  - shape-memory effect
KW  - platelet-rich plasma
Y1  - 2022
U6  - https://doi.org/10.1002/admi.202101588
SN  - 2196-7350
VL  - 9
IS  - 6
PB  - Wiley
CY  - Hoboken
ER  - 
TY  - JOUR
A1  - Machatschek, Rainhard Gabriel
A1  - Heuchel, Matthias
A1  - Lendlein, Andreas
T1  - Hydrolytic stability of polyetherimide investigated in ultrathin films
JF  - Journal of materials research : JMR / Materials Research Society
N2  - Increasing the surface hydrophilicity of polyetherimide (PEI) through partial hydrolysis of the imide groups while maintaining the length of the main-chain was explored for adjusting its function in biomedical and membrane applications. The outcome of the polymer analogous reaction, i.e., the degree of ring opening and chain cleavage, is difficult to address in bulk and microstructured systems, as these changes only occur at the interface. Here, the reaction was studied at the air-water interface using the Langmuir technique, assisted by atomic force microscopy and vibrational spectroscopy. Slow PEI hydrolysis sets in at pH > 12. At pH = 14, the ring opening is nearly instantaneous. Reduction of the layer viscosity with time at pH = 14 suggested moderate chain cleavage. No hydrolysis was observed at pH = 1. Hydrolyzed PEI films had a much more cohesive structure, suggesting that the nanoporous morphology of PEI can be tuned via hydrolysis.
KW  - 2D materials
KW  - Membrane
KW  - Polymer
KW  - Water
KW  - Nanostructure
Y1  - 2021
U6  - https://doi.org/10.1557/s43578-021-00267-6
SN  - 0884-2914
SN  - 2044-5326
VL  - 36
IS  - 14
SP  - 2987
EP  - 2994
PB  - Springer
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Tang, Jo Sing Julia
A1  - Smaczniak, Aline Debrassi
A1  - Tepper, Lucas
A1  - Rosencrantz, Sophia
A1  - Aleksanyan, Mina
A1  - Dähne, Lars
A1  - Rosencrantz, Ruben R.
T1  - Glycopolymer based LbL multilayer thin films with embedded liposomes
JF  - Macromolecular bioscience
N2  - Layer-by-layer (LbL) self-assembly emerged as an efficient technique for fabricating coating systems for, e.g., drug delivery systems with great versatility and control. In this work, protecting group free and aqueous-based syntheses of bioinspired glycopolymer electrolytes aredescribed. Thin films of the glycopolymers are fabricated by LbL self-assembly and function as scaffolds for liposomes, which potentially can encapsulate active substances. The adsorbed mass, pH stability, and integrity of glycopolymer coatings as well as the embedded liposomes are investigated via whispering gallery mode (WGM) technology and quartz crystal microbalance with dissipation (QCM-D) monitoring , which enable label-free characterization. Glycopolymer thin films, with and without liposomes, are stable in the physiological pH range. QCM-D measurements verify the integrity of lipid vesicles. Thus, the fabrication of glycopolymer-based surface coatings with embedded and intact liposomes is presented.
KW  - glycopolymers
KW  - layer-by-layer self-assembly
KW  - liposomes
KW  - polyelectrolyte
KW  - multilayer film
Y1  - 2022
U6  - https://doi.org/10.1002/mabi.202100461
SN  - 1616-5187
SN  - 1616-5195
VL  - 22
IS  - 4
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - THES
A1  - Breternitz, Joachim
T1  - Structural systematic investigations of photovoltaic absorber materials
N2  - The direct conversion of light from the sun into usable forms of energy marks one of the central cornerstones of the change of our living from the use of fossil, non-renewable energy resources towards a more sustainable economy. Besides the necessary societal changes necessary, it is  the understanding of the solids employed that is of particular importance for the success of this target. In this work, the principles and approaches of systematic-crystallographic characterisation and systematisation of solids is used and employed to allow a directed tuning of the materials properties. The thorough understanding of the solid-state forms hereby the basis, on which more applied approaches are founded.
Two material systems, which are considered as promising solar absorber materials, are at the core of this work: halide perovskites and II-IV-N2 nitride materials. While the first is renowned for its high efficiencies and rapid development in the last years, the latter is putting an emphasis on true sustainability in that toxic and scarce elements are avoided.
N2  - Die direkte Umwandlung der Energie der Sonne bildet einen zentralen Baustein im Umbau unserer Gesellschaft von der Nutzung fossiler, nicht nachhaltiger Energieträger zum Erreichen einer nachhaltigen Wirtschaft. Neben den gesellschaftlichen Veränderungen ist es insbesondere das Verständnis der genutzten Festkörper, das den Motor dieser Entwicklung bildet. In dieser Arbeit werden Prinzipien der systematisch-kristallographischen Untersuchung und Kategorisierung von Festkörpern genutzt, um die Eigenschaften der Materialien gezielt steuern zu können. Dabei bildet das Verständnis des kristallinen Zustands und seine Untersuchung die Basis, auf der angewandtere Forschungsansätze aufbauen.
In dieser Arbeit werden vor allem zwei Materialsysteme betrachtet, die als Absorbermaterialien in Solarzellen in Betracht gezogen werden: Halid-Perowskite und II-IV-N2-Nitrid Materialien. Die ersteren zeichnen sich insbesondere durch ihre erstaunlich hohen Effizienzen und rapide Entwicklung in den letzten Jahren aus, während das letztere System in besonderer Weise auf Nachhaltigkeit optimiert ist, und giftige oder seltene Elemente zu vermeiden sucht.
KW  - Materials Chemistry
KW  - Crystallography
KW  - Photovoltaics
Y1  - 2023
ER  - 
TY  - THES
A1  - Iqbal, Zafar
T1  - Interface design and characterization for stable inorganic perovskite solar cells
T1  - Grenzflächendesign und- charakterisierung für stabile anorganische Perowskit-Solarzellen
BT  - inorganic perovskite solar cells
N2  - We live in an era driven by fossil fuels. The prevailing climate change suggests that we have to significantly reduce greenhouse gas emissions. The only way forward is to use renewable energy sources. Among those, solar energy is a clean, affordable, and sustainable source of energy. It has the potential to satisfy the world’s energy demand in the future. However, there is a need to develop new materials that can make solar energy usable. Photovoltaics (PV) are devices that convert photon energy into electrical energy. The most commonly used solar cells are based on crystalline silicon. However, the fabrication process for silicon solar cells is technologically difficult and costly. Solar cells based on lead halide perovskites (PSCs) have emerged as a new candidate for PV applications since 2009. To date, PSCs have achieved 26% power-conversion-efficiency (PCE) for its single junction, and 33.7% PCE for tandem junction devices. However, there is still room for improvement in overall performance. The main challenge for the commercialization of this technology is the stability of the solar cells under operational conditions. Inorganic perovskite CsPbI3 has attracted researchers’ interest due to its stability at elevated temperatures, however, inorganic perovskites also have associated challenges, e.g. phase stability, larger voltage loss compared to their organic-inorganic hybrid counterparts, and interface energy misalignment. The most efficient inorganic perovskite solar cell is stable for up to a few hundred hours while the most stable device in the field of inorganic PSCs reported so far is at 17% PCE. This suggests the need for improvement of the interfaces for enhanced open circuit voltage (VOC), and optimization of the energy alignment at the interfaces. This dissertation presents the study on interfaces between the perovskite layer and hole transport layer (HTL) for stable CsPbI3 solar cells.
The first part of the thesis presents an investigation of the CsPbI3 film annealing environment and its subsequent effects on the perovskite/HTL interface dynamics. Thin films annealed in dry air were compared with thin films annealed in ambient air. Synchrotron-based hard X-ray spectroscopy (HAXPES) measurements reveal that annealing in ambient air does not have an adverse effect; instead, those samples undergo surface band bending. This surface band modification induces changes in interface charge dynamics and, consequently, an improvement in charge extraction at the interfaces. Further, transient surface photovoltage (tr-SPV) simulations show that air-annealed samples exhibit fewer trap states compared to samples annealed in dry air. Finally, by annealing the CsPbI3 films in ambient air, a PCE of 19.8% and Voc of 1.23 V were achieved for an n-i-p structured device.
Interface engineering has emerged as a strategy to extract the charge and optimize the energy alignment in perovskite solar cells (PSCs). An interface with fewer trap states and energy band levels closer to the selective contact helps to attain improved efficiencies in PSCs. The second part of the thesis presents a design for the CsPbI3/HTM interface. In this work, an interface between CsPbI3 perovskite and its hole selective contact N2,N2,N2′,N2′,N7,N7,N7′,N7′-octakis(4-methoxyphenyl)-9,9′-spirobi[9H-fluorene]-2,2′,7,7′-tetramine(Spiro-OMeTAD), realized by trioctylphosphine oxide (TOPO), a dipole molecule is introduced. On top of a perovskite film well-passivated by n-octyl ammonium Iodide (OAI), it created an upward surface band-bending at the interface byTOPO that optimizes energy level alignment and enhances the extraction of holes from the perovskite layer to the hole transport material. Consequently, a Voc of 1.2 V and high-power conversion efficiency (PCE) of over 19% were achieved for inorganic CsPbI3 perovskite solar cells. In addition, the work also sheds light on the interfacial charge-selectivity and the long-term stability of CsPbI3 perovskite solar cells.
The third part of the thesis extends the previous studies to polymeric poly(3-hexylthiophene-2,5-diyl) (P3HT) as HTL. The CsPbI3/P3HT interface is critical due to high non-radiative recombination. This work presents a CsPbI3/P3HT interface modified with a long-chain alkyl halide molecule, n-hexyl trimethyl ammonium bromide (HTAB). This molecule largely passivates the CsPbI3 perovskite surface and improves the charge extraction across the interface. Consequently, a Voc of over 1.00 V and 14.2% PCE were achieved for CsPbI3 with P3HT as HTM.
Overall the results presented in this dissertation introduce and discuss methods to design and study the interfaces in CsPbI3-based solar cells. This study can pave the way for novel interface designs between CsPbI3 and HTM for charge extraction, efficiency and stability.
N2  - Wir leben in einem Zeitalter, das von fossilen Brennstoffen geprägt ist. Der fortschreitende Klimawandel erfordert eine merkliche Reduktion der Treibhausgasemissionen. Der einzige Weg hin zu einer nachhaltigen Energiewirtschaft ist die Implementierung erneuerbarer Energiequellen. Solarenergie hat das Potential, den Energiebedarf der Welt langfristig auf saubere und kostengünstige Weise zu decken. Es müssen jedoch neue Materialien zur Marktreife entwickelt werden, die die Solarenergie nutzbar machen können. In der Photovoltaik (PV) wird Lichtenergie in elektrische Energie umwandelt, wobei die gängisten Solarzellen aus kristallinem Silizium bestehen. Die Herstellung von Silizium-Solarzellen ist jedoch technisch aufwending und kostspielig. Deshalb haben sich Solarzellen auf Basis von Bleihalogenid-Perowskiten (engl. perovskite solar cells, PSCs) seit 2009 als mögliche Alternative zur Siliziumtechnologie entwickelt. Bisweilen konnten Wirkungsgrade (engl. power conversion efficiency, PCE) von 26% in einem einzelnen Halbleiterübergang und von 33.7% in einem Tandemübergang erzielt werden. Diese Werte sind jedoch steigerbar und werden regelmäßig übertroffen. Die größte Herausfoderung für die Entwicklung dieser Technologie ist die Stabilität der Solarzellen unter Betriebsbedingungen. Der anorganische Perowskit CsPbI3 ist aufgrund seiner Stabilität bei hohen Temperaturen deshalb besonders interessant für die Forschung, obwohl das Material seine eigenen Herausforderungen birgt, wie zum Beispiel seine Phaseninstabilität, größere Leerlaufspannungsverluste im Vergleich zu seinen organisch-anorganisch-hybriden Analoga und Fehlaurichtung der Energiebänder an der Grenzfläche. Die Stabilität der effizientesten Solarzelle auf CsPbI3-Basis liegt bei einigen hundert Stunden, während die stabilste Solarzelle einen Wirkungsgrad von nunmehr 17% erzielt. Dies deutet auf die Notwendigkeit hin, die Grenzflächen zu den angrenzenden ladungsselektiven Kontakten zu verbessern – mit dem Ziel, die Leerlaufspannung (engl. open-circuit voltage, VOC) zu erhöhen und die Ausrichtung der Energiebänder an den Grenzflächen zu optimieren. Diese Dissertation befasst sich mit der Untersuchung der Grenzflächen zwischen der Perowskitschicht und der Lochtransportschicht (engl. hole transport layer, HTL) für stabile CsPbI3-Solarzellen.
Im ersten Teil der Arbeit werden die Temperbedingungen für CsPbI3-Dünnfilme und ihre Auswirkungen auf die Ladungsträgerdynamik an der Perowskit/HTL-Grenzfläche untersucht. Dünnfilme, die in trockener Atmosphäre getempert wurden, wurden mit Dünnfilmen verglichen, die in Standardatmosphäre getempert wurden. Synchrotrongestützte Messungen der Photoelektronenspektroskopie mit harter Röntgenstrahlung (engl. hard X-ray photoelectron spectrpscopy, HAXPES) zeigen, dass das Tempern in Umgebungsluft keine nachteiligen Auswirkungen hat; stattdessen erfahren jene Proben eine Verbiegung der Energiebänder an der Oberfläche. Diese Modifikation der Oberflächenbänder führt zu Veränderungen in der Grenzflächenladungsdynamik und in der Folge zu einer Verbesserung der Ladungsträgerextraktion über die Grenzfläche. Darüber hinaus zeigen Simulationen der transienten Oberflächenphotospannung (engl. transient surface photovoltage, trSPV), dass luftgetemperte Proben im Vergleich zu trockengetemperten Proben weniger Fallenzustände aufweisen. Letztlich wurde durch das Tempern der CsPbI3-Filme in Umgebungsluft eine PCE von 19,8% und ein VOC von 1,23 V für eine Solarzelle in n-i-p-Architektur erreicht.
Die Manipulation der Grenzflächen ist eine Strategie, um die Extraktion von Ladungsträgern und die Ausrichtung der Energiebänder in PSCs zu kontrollieren. Eine Grenzfläche mit geringerer Dichte an Fallenzuständen sowie der Fähigkeit, das Energiebandniveau näher an das des selektiven Kontakts zu verschieben, trägt zur Verbesserung des Wirkungsgrads von PSCs bei. Im zweiten Teil der Arbeit wird ein Design für die CsPbI3/HTM-Grenzfläche vorgeschlagen. Dabei wird das Dipolmolekül Trioctylphosphinoxid (TOPO) an der Grenzfläche zwischen CsPbI3-Perowskit und dem lochselektiven Kontakt N2, N2, N2′, N2′, N7, N7, N7′, N7′-octakis(4-Methoxyphenyl) -9,9′-Spirobi[9H-Fluoren] -2,2′,7,7′-Tetramin (spiro-OMeTAD) eingeführt. Auf einem mit n-Octylammoniumiodid (OAI) passivierten Perowskitfilm erzeugt TOPO eine nach oben gerichtete Oberflächenbandverkrümmung, die die Ausrichtung der Energieniveaus optimiert und die Extraktion von Löchern aus CsPbI3 in den HTL verbessert. Infolgedessen wurden in den hergestellten Solarzellen ein VOC von 1,2 V und eine PCE von über 19% erzielt. Darüber hinaus nimmt die Arbeit auch die Ladungsträgerselektivität an der Grenzfläche und die Langzeitstabilität von CsPbI3-Perowskit-Solarzellen in den Fokus.
Der dritte Teil der Arbeit erweitert die bisherigen Untersuchungen auf das Polymer Poly-(3-hexylthiophen-2,5-diyl) (P3HT) als HTL. Die CsPbI3/P3HT-Grenzfläche ist aufgrund der hohen nicht-radiativen Rekombination kritisch. In dieser Arbeit wird eine CsPbI3/P3HT-Grenzfläche vorgestellt, die mit einem langkettigen Alkylhalogenidmolekül, n-Hexyltrimethylammoniumbromid (HTAB), modifiziert wurde. Dieses Molekül passiviert die CsPbI3-Perowskit-Oberfläche weitgehend und verbessert die Ladungsträgerextraktion an der Grenzfläche. Für CsPbI3 mit P3HT als HTM konnte ein VOC von über 1,00 V und 14,2% PCE erreicht werden.
Insgesamt werden in dieser Dissertation Methoden zur Entwicklung und Untersuchung von Grenzflächen für Solarzellen auf CsPbI3-Basis vorgestellt und diskutiert. Diese Studie kann Wege für neuartiges Grenzflächendesign zwischen CsPbI3 und HTM im Hinblick auf Ladungsträgerextraktion, Effizienz und Stabilität eröffnen.
KW  - CsPbI3
KW  - interfaces
KW  - perovskite solar cells
KW  - CsPbI3
KW  - Grenzflächen
KW  - Perowskit-Solarzellen
Y1  - 2023
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-618315
ER  - 
TY  - JOUR
A1  - Abdou, Nicole
A1  - Alonso, Bruno
A1  - Brun, Nicolas
A1  - Landois, Perine
A1  - Taubert, Andreas
A1  - Hesemann, Peter
A1  - Mehdi, Ahmad
T1  - Ionic guest in ionic host
BT  - ionosilica ionogel composites via ionic liquid confinement in ionosilica supports
JF  - Materials chemistry frontiers
N2  - Ionosilica ionogels, i.e. composites consisting of an ionic liquid (IL) guest confined in an ionosilica host matrix, were synthesized via a non-hydrolytic sol-gel procedure from a tris-trialcoxysilylated amine precursor using the IL [BMIM]NTf2 as solvent. Various ionosilica ionogels were prepared starting from variable volumes of IL in the presence of formic acid. The resulting brittle and nearly colourless monoliths are composed of different amounts of IL guests confined in an ionosilica host as evidenced via thermogravimetric analysis, FT-IR, and C-13 CP-MAS solid-state NMR spectroscopy. In the following, we focused on confinement effects between the ionic host and guest. Special host-guest interactions between the IL guest and the ionosilica host were evidenced by H-1 solid-state NMR, Raman spectroscopy, and broadband dielectric spectroscopy (BDS) measurements. The three techniques indicate a strongly reduced ion mobility in the ionosilica ionogel composites containing small volume fractions of confined IL, compared to conventional silica-based ionogels. We conclude that the ionic ionosilica host stabilizes an IL layer on the host surface; this then results in a strongly reduced ion mobility compared to conventional silica hosts. The ion mobility progressively increases for systems containing higher volume fractions of IL and finally reaches the values observed in conventional silica based ionogels. These results therefore point towards strong interactions and confinement effects between the ionic host and the ionic guest on the ionosilica surface. Furthermore, this approach allows confining high volume fractions of IL into self-standing monoliths while preserving high ionic conductivity. These effects may be of interest in domains where IL phases must be anchored on solid supports to avoid leaching or IL spilling, e.g., in catalysis, in gas separation/sequestration devices or for the elaboration of solid electrolytes for (lithium-ion) batteries and supercapacitors.
Y1  - 2022
U6  - https://doi.org/10.1039/d2qm00021k
SN  - 2052-1537
VL  - 6
IS  - 7
SP  - 939
EP  - 947
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Bapolisi, Alain Murhimalika
A1  - Kielb, Patrycja
A1  - Bekir, Marek
A1  - Lehnen, Anne-Catherine
A1  - Radon, Christin
A1  - Laroque, Sophie
A1  - Wendler, Petra
A1  - Müller-Werkmeister, Henrike
A1  - Hartlieb, Matthias
T1  - Antimicrobial polymers of linear and bottlebrush architecture
BT  - Probing the membrane interaction and physicochemical properties
JF  - Macromolecular rapid communications : publishing the newsletters of the European Polymer Federation
N2  - Polymeric antimicrobial peptide mimics are a promising alternative for the future management of the daunting problems associated with antimicrobial resistance. However, the development of successful antimicrobial polymers (APs) requires careful control of factors such as amphiphilic balance, molecular weight, dispersity, sequence, and architecture. While most of the earlier developed APs focus on random linear copolymers, the development of APs with advanced architectures proves to be more potent. It is recently developed multivalent bottlebrush APs with improved antibacterial and hemocompatibility profiles, outperforming their linear counterparts. Understanding the rationale behind the outstanding biological activity of these newly developed antimicrobials is vital to further improving their performance. This work investigates the physicochemical properties governing the differences in activity between linear and bottlebrush architectures using various spectroscopic and microscopic techniques. Linear copolymers are more solvated, thermo-responsive, and possess facial amphiphilicity resulting in random aggregations when interacting with liposomes mimicking Escheria coli membranes. The bottlebrush copolymers adopt a more stable secondary conformation in aqueous solution in comparison to linear copolymers, conferring rapid and more specific binding mechanism to membranes. The advantageous physicochemical properties of the bottlebrush topology seem to be a determinant factor in the activity of these promising APs.
KW  - antimicrobial polymers
KW  - bottlebrush copolymers
KW  - liposomes
KW  - membrane
KW  - interactions
KW  - quartz crystal microbalance
Y1  - 2022
U6  - https://doi.org/10.1002/marc.202200288
SN  - 1521-3927
SN  - 1022-1336
VL  - 43
IS  - 19
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Kim, Jiyong
A1  - Kim, Yohan
A1  - Park, Kyoungwon
A1  - Boeffel, Christine
A1  - Choi, Hyung-Seok
A1  - Taubert, Andreas
A1  - Wedel, Armin
T1  - Ligand Effect in 1-Octanethiol Passivation of InP/ZnSe/ZnS Quantum Dots-Evidence of Incomplete Surface Passivation during Synthesis
JF  - Small : nano micro
N2  - The lack of anionic carboxylate ligands on the surface of InP/ZnSe/ZnS quantum dots (QDs), where zinc carboxylate ligands can be converted to carboxylic acid or carboxylate ligands via proton transfer by 1-octanethiol, is demonstrated. The as-synthesized QDs initially have an under-coordinated vacancy surface, which is passivated by solvent ligands such as ethanol and acetone. Upon exposure of 1-octanethiol to the QD surface, 1-octanethiol effectively induces the surface binding of anionic carboxylate ligands (derived from zinc carboxylate ligands) by proton transfer, which consequently exchanges ethanol and acetone ligands that bind on the incomplete QD surface. These systematic chemical analyses, such as thermogravimetric analysis-mass spectrometry and proton nuclear magnetic resonance spectroscopy, directly show the interplay of surface ligands, and it associates with QD light-emitting diodes (QD-LEDs). It is believed that this better understanding can lead to industrially feasible QD-LEDs.
KW  - colloidal quantum dots
KW  - incomplete surface passivation
KW  - indium
KW  - phosphide
KW  - surface chemistry
KW  - thiol passivation
Y1  - 2022
U6  - https://doi.org/10.1002/smll.202203093
SN  - 1613-6810
SN  - 1613-6829
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - THES
A1  - Eren, Enis Oğuzhan
T1  - Covalent anode materials for high-energy sodium-ion batteries
T1  - Kovalente Anodenmaterialien für hoch-energetische Natrium-Ionen-Batterien
N2  - The reliance on fossil fuels has resulted in an abnormal increase in the concentration of greenhouse gases, contributing to the global climate crisis. In response, a rapid transition to renewable energy sources has begun, particularly lithium-ion batteries, playing a crucial role in the green energy transformation. However, concerns regarding the availability and geopolitical implications of lithium have prompted the exploration of alternative rechargeable battery systems, such as sodium-ion batteries. Sodium is significantly abundant and more homogeneously distributed in the crust and seawater, making it easier and less expensive to extract than lithium. However, because of the mysterious nature of its components, sodium-ion batteries are not yet sufficiently advanced to take the place of lithium-ion batteries. Specifically, sodium exhibits a more metallic character and a larger ionic radius, resulting in a different ion storage mechanism utilized in lithium-ion batteries. Innovations in synthetic methods, post-treatments, and interface engineering clearly demonstrate the significance of developing high-performance carbonaceous anode materials for sodium-ion batteries. The objective of this dissertation is to present a systematic approach for fabricating efficient, high-performance, and sustainable carbonaceous anode materials for sodium-ion batteries. This will involve a comprehensive investigation of different chemical environments and post-modification techniques as well.
This dissertation focuses on three main objectives. Firstly, it explores the significance of post-synthetic methods in designing interfaces. A conformal carbon nitride coating is deposited through chemical vapor deposition on a carbon electrode as an artificial solid-electrolyte interface layer, resulting in improved electrochemical performance. The interaction between the carbon nitride artificial interface and the carbon electrode enhances initial Coulombic efficiency, rate performance, and total capacity. Secondly, a novel process for preparing sulfur-rich carbon as a high-performing anode material for sodium-ion batteries is presented. The method involves using an oligo-3,4-ethylenedioxythiophene precursor for high sulfur content hard carbon anode to investigate the sulfur heteroatom effect on the electrochemical sodium storage mechanism. By optimizing the condensation temperature, a significant transformation in the materials’ nanostructure is achieved, leading to improved electrochemical performance. The use of in-operando small-angle X-ray scattering provides valuable insights into the interaction between micropores and sodium ions during the electrochemical processes. Lastly, the development of high-capacity hard carbon, derived from 5-hydroxymethyl furfural, is examined. This carbon material exhibits exceptional performance at both low and high current densities. Extensive electrochemical and physicochemical characterizations shed light on the sodium storage mechanism concerning the chemical environment, establishing the material’s stability and potential applications in sodium-ion batteries.
N2  - Die Abhängigkeit von fossilen Brennstoffen hat zu einem abnormalen Anstieg von Treibhausgasen in der Atmosphäre geführt, was zur globalen Klimakrise beiträgt. Als Reaktion darauf hat eine rasche Umstellung auf erneuerbare Energiequellen begonnen, insbesondere Lithium-Ionen-Batterien, die eine entscheidende Rolle in der grünen Energiewende spielen. Bedenken hinsichtlich der Verfügbarkeit und geopolitischen Implikationen von Lithium haben jedoch die Erforschung alternativer wiederaufladbarer Batteriesysteme wie Natrium-Ionen-Batterien angeregt. Natrium ist in der Erdkruste und im Meerwasser deutlich häufiger und gleichmäßiger verteilt, was seine Extraktion im Vergleich zu Lithium einfacher und kostengünstiger macht. Aufgrund der geheimnisvollen Natur ihrer Komponenten sind Natrium-Ionen-Batterien derzeit noch nicht ausreichend fortgeschritten, um Lithium-Ionen-Batterien zu ersetzen. Insbesondere weist Natrium einen stärker metallischen Charakter und einen größeren Ionenradius auf, was zu einem anderen Ionen-Speichermechanismus führt, der in Lithium-Ionen-Batterien verwendet wird. Innovationen in synthetischen, post-synthetischen Methoden und Schnittstellentechnik zeigen deutlich die Bedeutung der Entwicklung hochleistungsfähiger kohlenstoffhaltiger Anodenmaterialien für Natrium-Ionen-Batterien auf. Das Ziel dieser Dissertation ist es, einen systematischen Ansatz zur Herstellung effizienter, leistungsstarker und nachhaltiger kohlenstoffhaltiger Anodenmaterialien für Natrium-Ionen-Batterien zu untersuchen. 
Diese Dissertation konzentriert sich auf drei Hauptziele. Erstens untersucht sie die Bedeutung von post-synthetischen Methoden bei der Gestaltung von Schnittstellen. Eine konforme Kohlenstoffnitrid-Beschichtung wird durch chemische Gasphasenabscheidung auf einer Kohlenstoffelektrode als künstliche Festelektrolytschnittstelle abgeschieden, was zu einer verbesserten elektrochemischen Leistung führt. Die Wechselwirkung zwischen der künstlichen Kohlenstoffnitrid-Schnittstelle und der Kohlenstoffelektrode trägt zu einer verbesserten anfänglichen kolumbischen Effizienz, Leistung bei hohen Raten und Gesamtkapazität bei. Zweitens wird ein neuartiger Prozess zur Herstellung von schwefelreichem Kohlenstoff als hochleistungsfähiges Anodenmaterial für Natrium-Ionen-Batterien vorgestellt. Die Methode verwendet einen Oligo-3,4-ethylendioxythiophen-Vorläufer für eine harte Kohlenstoffanode mit hohem Schwefelgehalt, um den Effekt des Schwefelheteroatoms auf den elektrochemischen Natriumspeichermechanismus zu untersuchen. Durch Optimierung der Kondensationstemperatur wird eine bedeutende Transformation in der Nanostruktur des Materials erreicht, was zu einer verbesserten elektrochemischen Leistung führt. Der Einsatz von in-operando-Röntgenkleinwinkelstreuung liefert wertvolle Erkenntnisse über die Wechselwirkung zwischen Mikroporen und Natriumionen während der elektrochemischen Prozesse. Letzendlich wird die Entwicklung einer hochkapazitiven harten Kohlenstoffanode, die aus 5-Hydroxymethylfurfural gewonnen wird, untersucht. Dieses Kohlenstoffmaterial zeigt eine außergewöhnliche Leistung sowohl bei niedrigen als auch bei hohen Stromdichten.
KW  - sodium-ion battery
KW  - sulfur
KW  - carbon
KW  - CN
KW  - anode
KW  - in-operando SAXS
KW  - Kohlenstoffnitrid (CN)
KW  - Anode
KW  - Kohlenstoff
KW  - in-operando SAXS
KW  - Natrium-Ionen-Batterie
KW  - Schwefel
Y1  - 2024
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-622585
ER  - 
TY  - JOUR
A1  - Hartlieb, Matthias
A1  - Mansfield, Edward D. H.
A1  - Perrier, Sebastien
T1  - A guide to supramolecular polymerizations
JF  - Polymer Chemistry
N2  - Supramolecular polymers or fibers are non-covalent assemblies of unimeric building blocks connected by secondary interactions such as hydrogen bonds or pi-pi interactions. Such structures hold enormous potential in the development of future materials, as their non-covalent nature makes them highly modular and adaptive. Within this review we aim to provide a broad overview over the area of linear supramolecular polymers including the different mechanisms of their polymerization as well as methods essential for their characterization. The different non-covalent interactions able to form supramolecular polymers are discussed, and key examples for each species are shown. Particular emphasis is laid on the development of living supramolecular polymerization able to produce fibers with a controlled length and low length dispersity, and even enable the production of supramolecular block copolymers. Another important and very recent field is the development of out-of-equilibrium supramolecular polymers, where the polymerization process can be temporally controlled enabling access to highly adaptive materials.
Y1  - 2020
U6  - https://doi.org/10.1039/c9py01342c
SN  - 1759-9954
SN  - 1759-9962
VL  - 11
IS  - 6
SP  - 1083
EP  - 1110
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Doering, Ulrike
A1  - Grigoriev, Dmitry
A1  - Tapio, Kosti
A1  - Bald, Ilko
A1  - Böker, Alexander
T1  - Synthesis of nanostructured protein-mineral-microcapsules by sonication
JF  - Soft matter
N2  - We propose a simple and eco-friendly method for the formation of composite protein-mineral-microcapsules induced by ultrasound treatment. Protein- and nanoparticle-stabilized oil-in-water (O/W) emulsions loaded with different oils are prepared using high-intensity ultrasound. The formation of thin composite mineral proteinaceous shells is realized with various types of nanoparticles, which are pre-modified with Bovine Serum Albumin (BSA) and subsequently characterized by EDX, TGA, zeta potential measurements and Raman spectroscopy. Cryo-SEM and EDX mapping visualizations show the homogeneous distribution of the densely packed nanoparticles in the capsule shell. In contrast to the results reported in our previous paper,(1) the shell of those nanostructured composite microcapsules is not cross-linked by the intermolecular disulfide bonds between BSA molecules. Instead, a Pickering-Emulsion formation takes place because of the amphiphilicity-driven spontaneous attachment of the BSA-modified nanoparticles at the oil/water interface. Using colloidal particles for the formation of the shell of the microcapsules, in our case silica, hydroxyapatite and calcium carbonate nanoparticles, is promising for the creation of new functional materials. The nanoparticulate building blocks of the composite shell with different chemical, physical or morphological properties can contribute to additional, sometimes even multiple, features of the resulting capsules. Microcapsules with shells of densely packed nanoparticles could find interesting applications in pharmaceutical science, cosmetics or in food technology.
Y1  - 2022
U6  - https://doi.org/10.1039/d1sm01638e
SN  - 1744-6848
VL  - 18
IS  - 13
SP  - 2558
EP  - 2568
PB  - Royal Society of Chemistry
CY  - London
ER  - 
TY  - JOUR
A1  - Machatschek, Rainhard Gabriel
A1  - Heuchel, Matthias
A1  - Lendlein, Andreas
T1  - Thin-layer studies on surface functionalization of polyetherimide
BT  - hydrolysis versus amidation
JF  - Journal of materials research : JMR / Materials Research Society
N2  - Among the high-performance and engineering polymers, polyimides and the closely related polyetherimide (PEI) stand out by their capability to react with nucleophiles under relatively mild conditions. By targeting the phthalimide groups in the chain backbone, post-functionalization offers a pathway to adjust surface properties such as hydrophilicity, solvent resistance, and porosity. Here, we use ultrathin PEI films on a Langmuir trough as a model system to investigate the surface functionalization with ethylene diamine and tetrakis(4-aminophenyl)porphyrin as multivalent nucleophiles. By means of AFM, Raman spectroscopy, and interfacial rheology, we show that hydrolysis enhances the chemical and mechanical stability of ultrathin films and allows for the formation of EDC/NHS-activated esters. Direct amidation of PEI was achieved in the presence of a Lewis acid catalyst, resulting in free amine groups rather than cross-linking. When comparing amidation with hydrolysis, we find a greater influence of the latter on material properties.
KW  - Membrane
KW  - Nanostructure
KW  - Polymer
KW  - Raman spectroscopy
KW  - Scanning probe microscopy (SPM)
KW  - Surface reaction
KW  - Thin film
Y1  - 2021
U6  - https://doi.org/10.1557/s43578-021-00339-7
SN  - 0884-2914
SN  - 2044-5326
VL  - 37
IS  - 1
SP  - 67
EP  - 76
PB  - Springer
CY  - Berlin
ER  - 
TY  - JOUR
A1  - Buyinza, Daniel
A1  - Derese, Solomon
A1  - Ndakala, Albert
A1  - Heydenreich, Matthias
A1  - Yenesew, Abiy
A1  - Koch, Andreas
A1  - Oriko, Richard
T1  - A coumestan and a coumaronochromone from Millettia lasiantha
JF  - Biochemical systematics and ecology
N2  - The manuscript describes the phytochemical investigation of the roots, leaves and stem bark of Millettia lasiantha resulting in the isolation of twelve compounds including two new isomeric isoflavones lascoumestan and las-coumaronochromone. The structures of the new compounds were determined using different spectroscopic techniques.
KW  - Millettia lasiantha
KW  - Leguminosae
KW  - Coumestan
KW  - Coumaronochromone
Y1  - 2021
U6  - https://doi.org/10.1016/j.bse.2021.104277
SN  - 0305-1978
SN  - 1873-2925
VL  - 97
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Yang, Jin
A1  - Ghosh, Samrat
A1  - Roeser, Jérôme
A1  - Acharjya, Amitava
A1  - Penschke, Christopher
A1  - Tsutsui, Yusuke
A1  - Rabeah, Jabor
A1  - Wang, Tianyi
A1  - Tameu, Simon Yves Djoko
A1  - Ye, Meng-Yang
A1  - Grüneberg, Julia
A1  - Li, Shuang
A1  - Li, Changxia
A1  - Schomaecker, Reinhard
A1  - Van de Krol, Roel
A1  - Seki, Shu
A1  - Saalfrank, Peter
A1  - Thomas, Arne
T1  - Constitutional isomerism of the linkages in donor–acceptor covalent organic frameworks and its impact on photocatalysis
JF  - Nature Communications
N2  - When new covalent organic frameworks (COFs) are designed, the main efforts are typically focused on selecting specific building blocks with certain geometries and properties to control the structure and function of the final COFs. The nature of the linkage (imine, boroxine, vinyl, etc.) between these building blocks naturally also defines their properties. However, besides the linkage type, the orientation, i.e., the constitutional isomerism of these linkages, has rarely been considered so far as an essential aspect. In this work, three pairs of constitutionally isomeric imine-linked donor-acceptor (D-A) COFs are synthesized, which are different in the orientation of the imine bonds (D-C=N-A (DCNA) and D-N=C-A (DNCA)). The constitutional isomers show substantial differences in their photophysical properties and consequently in their photocatalytic performance. Indeed, all DCNA COFs show enhanced photocatalytic H2 evolution performance than the corresponding DNCA COFs. Besides the imine COFs shown here, it can be concluded that the proposed concept of constitutional isomerism of linkages in COFs is quite universal and should be considered when designing and tuning the properties of COFs.
Y1  - 2022
U6  - https://doi.org/10.1038/s41467-022-33875-9
SN  - 2041-1723
VL  - 13
IS  - 1
PB  - Nature Publishing Group UK
CY  - [London]
ER  - 
TY  - GEN
A1  - Moerschbacher, Bruno
A1  - Jaworska, Małgorzata
A1  - Peter, Martin G.
T1  - Obituary of George A.F. Roberts (1939-2018)
T2  - Reactive & functional polymers
Y1  - 2020
U6  - https://doi.org/10.1016/j.reactfunctpolym.2020.104711
SN  - 1381-5148
SN  - 1873-166X
VL  - 156
PB  - Elsevier
CY  - Amsterdam [u.a.]
ER  - 
TY  - JOUR
A1  - Franz, Alexandra
A1  - Többens, Daniel M.
A1  - Lehmann, Frederike
A1  - Kärgell, Martin
A1  - Schorr, Susan
T1  - The influence of deuteration on the crystal structure of hybrid halide perovskites: a temperature-dependent neutron diffraction study of FAPbBr(3)
JF  - Acta crystallographica; Section B, Structural science, crystal engineering and materials
N2  - This paper discusses the full structural solution of the hybrid perovskite formamidinium lead tribromide (FAPbBr(3)) and its temperature-dependent phase transitions in the range from 3 K to 300 K using neutron powder diffraction and synchrotron X-ray diffraction. Special emphasis is put on the influence of deuteration on formamidinium, its position in the unit cell and disordering in comparison to fully hydrogenated FAPbBr(3). The temperature-dependent measurements show that deuteration critically influences the crystal structures, i.e. results in partially-ordered temperature-dependent structural modifications in which two symmetry-independent molecule positions with additional dislocation of the molecular centre atom and molecular angle inclinations are present.
KW  - hybrid perovskite
KW  - FAPbBr(3)
KW  - deuteration
KW  - neutron powder diffraction
KW  - crystal structure
Y1  - 2020
U6  - https://doi.org/10.1107/S2052520620002620
SN  - 2052-5206
VL  - 76
IS  - 2
SP  - 267
EP  - 274
PB  - Wiley-Blackwell
CY  - Oxford [u.a.]
ER  - 
TY  - JOUR
A1  - Gu, Sasa
A1  - Risse, Sebastian
A1  - Lu, Yan
A1  - Ballauff, Matthias
T1  - Mechanism of the oxidation of 3,3′,5,5′-tetramethylbenzidine catalyzed by peroxidase-like Pt nanoparticles immobilized in spherical polyelectrolyte brushes
BT  - a kinetic study
JF  - ChemPhysChem
N2  - Experimental and kinetic modelling studies are presented to investigate the mechanism of 3,3 ',5,5 '-tetramethylbenzidine (TMB) oxidation by hydrogen peroxide (H2O2) catalyzed by peroxidase-like Pt nanoparticles immobilized in spherical polyelectrolyte brushes (SPB-Pt). Due to the high stability of SPB-Pt colloidal, this reaction can be monitored precisely in situ by UV/VIS spectroscopy. The time-dependent concentration of the blue-colored oxidation product of TMB expressed by different kinetic models was used to simulate the experimental data by a genetic fitting algorithm. After falsifying the models with abundant experimental data, it is found that both H2O2 and TMB adsorb on the surface of Pt nanoparticles to react, indicating that the reaction follows the Langmuir-Hinshelwood mechanism. A true rate constant k, characterizing the rate-determining step of the reaction and which is independent on the amount of catalysts used, is obtained for the first time. Furthermore, it is found that the product adsorbes strongly on the surface of nanoparticles, thus inhibiting the reaction. The entire analysis provides a new perspective to study the catalytic mechanism and evaluate the catalytic activity of the peroxidase-like nanoparticles.
KW  - kinetics
KW  - nanoparticles
KW  - reaction mechanisms
KW  - spherical polyelectrolyte
KW  - brushes
KW  - UV
KW  - vis spectroscopy
Y1  - 2019
U6  - https://doi.org/10.1002/cphc.201901087
SN  - 1439-4235
SN  - 1439-7641
VL  - 21
IS  - 5
SP  - 450
EP  - 458
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Gharabekyan, Hrant H.
A1  - Koetz, Joachim
A1  - Poghosyan, Armen H.
T1  - A protonated L-cysteine adsorption on gold surface
BT  - a molecular dynamics study
JF  - Colloids and surfaces : an international journal devoted to the principles and applications of colloid and interface science ; A, Physicochemical and engineering aspects
N2  - The adsorption of protonated L-cysteine onto Au(111) surface was studied via molecular dynamics method. The detailed examination of trajectories reveals that a couple of picoseconds need to be strongly adsorbed at the gold surface via L-cysteine's sulfur and oxygen atoms. The average distances of L-cysteine's adsorbed sulfur and oxygen from gold plane are-2.7 angstrom and-3.2 angstrom, correspondingly. We found that the adsorption of L-cysteine takes place preferentially at bridge site with possibility of-82%. Discussing the conformation features of protonated L-cysteine, we consider that the most stable conformation of protonated L-cysteine is "reverse boat" position, where sulfur and oxygen pointed down to the gold surface, while the amino group is far from the gold surface.
KW  - MD simulations
KW  - gold surface
KW  - GOIP
KW  - l-cysteine
KW  - adsorption
KW  - protonation
Y1  - 2021
U6  - https://doi.org/10.1016/j.colsurfa.2021.127452
SN  - 0927-7757
SN  - 1873-4359
VL  - 629
PB  - Elsevier
CY  - Amsterdam
ER  - 
TY  - JOUR
A1  - Bouakline, Foudhil
A1  - Saalfrank, Peter
T1  - Seemingly asymmetric atom-localized electronic densities following laser-dissociation of homonuclear diatomics
JF  - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistry
N2  - Recent experiments on laser-dissociation of aligned homonuclear diatomic molecules show an asymmetric forward-backward (spatial) electron-localization along the laser polarization axis. Most theoretical models attribute this asymmetry to interference effects between gerade and ungerade vibronic states. Presumably due to alignment, these models neglect molecular rotations and hence infer an asymmetric (post-dissociation) charge distribution over the two identical nuclei. In this paper, we question the equivalence that is made between spatial electron-localization, observed in experiments, and atomic electron-localization, alluded by these theoretical models. We show that (seeming) agreement between these models and experiments is due to an unfortunate omission of nuclear permutation symmetry, i.e., quantum statistics. Enforcement of the latter requires mandatory inclusion of the molecular rotational degree of freedom, even for perfectly aligned molecules. Unlike previous interpretations, we ascribe spatial electron-localization to the laser creation of a rovibronic wavepacket that involves field-free molecular eigenstates with opposite space-inversion symmetry i.e., even and odd parity. Space-inversion symmetry breaking would then lead to an asymmetric distribution of the (space-fixed) electronic density over the forward and backward hemisphere. However, owing to the simultaneous coexistence of two indistinguishable molecular orientational isomers, our analytical and computational results show that the post-dissociation electronic density along a specified space-fixed axis is equally shared between the two identical nuclei-a result that is in perfect accordance with the principle of the indistinguishability of identical particles. Published under an exclusive license by AIP Publishing.
Y1  - 2021
U6  - https://doi.org/10.1063/5.0049710
SN  - 0021-9606
SN  - 1089-7690
VL  - 154
IS  - 23
PB  - American Institute of Physics
CY  - Melville
ER  - 
TY  - JOUR
A1  - Qiu, Liang
A1  - Zhang, Haoran
A1  - Bick, Thomas
A1  - Martin, Johannes
A1  - Wendler, Petra
A1  - Böker, Alexander
A1  - Glebe, Ulrich
A1  - Xing, Chengfen
T1  - Construction of highly ordered glyco-inside nano-assemblies through RAFT dispersion polymerization of galactose-decorated monomer
JF  - Angewandte Chemie : a journal of the Gesellschaft Deutscher Chemiker ; International edition
N2  - Glyco-assemblies derived from amphiphilic sugar-decorated block copolymers (ASBCs) have emerged prominently due to their wide application, for example, in biomedicine and as drug carriers. However, to efficiently construct these glyco-assemblies is still a challenge. Herein, we report an efficient technology for the synthesis of glyco-inside nano-assemblies by utilizing RAFT polymerization of a galactose-decorated methacrylate for polymerization-induced self-assembly (PISA). Using this approach, a series of highly ordered glyco-inside nano-assemblies containing intermediate morphologies were fabricated by adjusting the length of the hydrophobic glycoblock and the polymerization solids content. A specific morphology of complex vesicles was captured during the PISA process and the formation mechanism is explained by the morphology of its precursor and intermediate. Thus, this method establishes a powerful route to fabricate glyco-assemblies with tunable morphologies and variable sizes, which is significant to enable the large-scale fabrication and wide application of glyco-assemblies.
KW  - galactose-decorated monomer
KW  - glyco-inside nano-assemblies
KW  - morphology
KW  - evolution
KW  - PISA
KW  - RAFT dispersion polymerization
Y1  - 2021
U6  - https://doi.org/10.1002/anie.202015692
SN  - 1433-7851
SN  - 1521-3773
VL  - 60
IS  - 20
SP  - 11098
EP  - 11103
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Zhang, Shanshan
A1  - Liu, Yue
A1  - Machatschek, Rainhard Gabriel
A1  - Lendlein, Andreas
T1  - Ultrathin collagen type I films formed at the air-water interface
JF  - MRS advances : a journal of the Materials Research Society (MRS)
N2  - Collagen-based biomaterials with oriented fibrils have shown great application potential in medicine. However, it is still challenging to control the type I collagen fibrillogenesis in ultrathin films. Here, we report an approach to produce cohesive and well-organized type I collagen ultrathin films of about 10 nm thickness using the Langmuir-Blodgett technique. Ellipsometry, rheology, and Brewster angle microscopy are applied to investigate in situ how the molecules behave at the air-water interface, both at room temperature and 37 degrees C. The interfacial storage modulus observed at room temperature vanishes upon heating, indicating the existence and disappearance of the network structure in the protein nanosheet. The films were spanning over holes as large as 1 mm diameter when transferred at room temperature, proving the strong cohesive interactions. A highly aligned and fibrillar structure was observed by atomic force microscopy (AFM) and optical microscopy.
Y1  - 2022
U6  - https://doi.org/10.1557/s43580-021-00160-8
SN  - 2059-8521
VL  - 7
IS  - 4
SP  - 56
EP  - 62
PB  - Springer Nature Switzerland AG
CY  - Cham
ER  - 
TY  - JOUR
A1  - Sperlich, Eric
A1  - Köckerling, Martin
T1  - Cluster salts [Nb6Cl12(HIm)(6)]A(n) (with HIm=1H-imidazole and A=Mineral Acid Anion, n=1 or 2) made in and with Bronsted-basic ionic liquids and liquid mixtures
JF  - ChemistryOpen
N2  - Four new hexanuclear niobium cluster compounds of the general formula [Nb6Cl12(HIm)(6)](A)(n) . x(solvent molecule) (HIm=1H-imidazole, A=mineral acid anion, Cl- (n=2) (1), (SO4)(2-) (n=1) (2), (CrO4)(2-) (n=1) (3), and (HAsO4)(2-) (n=1) (4)) were prepared. Their synthesis can be done in basic ionic liquids, which form on the addition of a mineral acid, which also delivers the counter anion for the final cluster compound, to an excess of the 1H-imidazole. Some addition of an auxiliary solvent, like methanol, improves the speed of crystallisation. The cluster unit comprises a hexanuclear Nb-6 unit of octahedral shape with the edges bridged by Cl atoms and the exo sites being occupied by N-bonded 1H-imidazole ligands. The cluster cation carries sixteen cluster-based electrons. Between the NH groups of the ligands of the cluster unit, the anions and the co-crystallised water (1), or 1H-imidazole and methanol molecules (2, 3, and 4) a network of hydrogen bonds exists.
KW  - cluster
KW  - ionic liquid
KW  - structure elucidation
KW  - heterocyclic ligand
KW  - Niobium
Y1  - 2021
U6  - https://doi.org/10.1002/open.202000266
SN  - 2191-1363
VL  - 10
IS  - 2
SP  - 248
EP  - 254
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Roy, Parna
A1  - Mukherjee, Arpita
A1  - Mondal, Pritha
A1  - Bhattacharyya, Biswajit
A1  - Narayan, Awadhesh
A1  - Pandey, Anshu
T1  - Electronic structure and spectroscopy of I-III-VI2 nanocrystals
BT  - a perspective
JF  - The journal of physical chemistry : C, Nanomaterials and interfaces
N2  - I-III-VI2 semiconductor nanocrystals have been applied to a host of energy conversion devices with great success. Large scale implementation of device concepts based on these materials has, however, been somewhat stymied by the strong role of defects in determining the optoelectronic characteristics of these materials. Here we present a perspective view of the role of electronic structure and defects on the physical properties, particularly the spectroscopy, of this family of materials. Applications of these materials are further discussed in this context.
Y1  - 2022
U6  - https://doi.org/10.1021/acs.jpcc.1c10922
SN  - 1932-7447
SN  - 1932-7455
VL  - 126
IS  - 17
SP  - 7364
EP  - 7373
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Madani, Amiera
A1  - Anghileri, Lucia
A1  - Heydenreich, Matthias
A1  - Möller, Heiko Michael
A1  - Pieber, Bartholomäus
T1  - Benzylic fluorination induced by a charge-transfer complex with a solvent-dependent selectivity switch
JF  - Organic letters / publ. by the American Chemical Society
N2  - We present a divergent strategy for the fluorination of phenylacetic acid derivatives that is induced by a charge-transfer complex between Selectfluor and 4-(dimethylamino)pyridine. A comprehensive investigation of the conditions revealed a critical role of the solvent on the reaction outcome. In the presence of water, decarboxylative fluorination through a single-electron oxidation is dominant. Non-aqueous conditions result in the clean formation of alpha-fluoro-alpha-arylcarboxylic acids.
KW  - Charge transfer
KW  - Halogenation
KW  - Oxidation
KW  - Reaction products
KW  - Reagents
Y1  - 2022
U6  - https://doi.org/10.1021/acs.orglett.2c02050
SN  - 1523-7060
SN  - 1523-7052
VL  - 24
IS  - 29
SP  - 5376
EP  - 5380
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - THES
A1  - Halbrügge, Lena
T1  - Von der Curricularen Innovation zur Wissenschaftskommunikation
T1  - From curriculum innovation to science communication
BT  - Explorative Entwicklung und Evaluation einer Wissenschaftskommunikationsstrategie für naturwissenschaftliche Forschungsverbünde
BT  - exploratory development and evaluation of a strategy for science communication in scientific research associations
N2  - Im Rahmen einer explorativen Entwicklung wurde in der vorliegenden Studie ein Konzept zur Wissenschaftskommunikation für ein Graduiertenkolleg, in dem an photochemischen Prozessen geforscht wird, erstellt und anschließend evaluiert. Der Grund dafür ist die immer stärker wachsende Forderung nach Wissenschaftskommunikation seitens der Politik. Es wird darüber hinaus gefordert, dass die Kommunikation der eigenen Forschung in Zukunft integrativer Bestandteil des wissenschaftlichen Arbeitens wird. Um junge Wissenschaftler bereits frühzeitig auf diese Aufgabe vorzubereiten, wird Wissenschaftskommunikation auch in Forschungsverbünden realisiert.
Aus diesem Grund wurde in einer Vorstudie untersucht, welche Anforderungen an ein Konzept zur Wissenschaftskommunikation im Rahmen eines Forschungsverbundes gestellt werden, indem die Einstellung der Doktoranden zur Wissenschaftskommunikation sowie ihre Kommunikationsfähigkeiten anhand eines geschlossenen Fragebogens evaluiert wurden. Darüber hinaus wurden aus den Daten Wissenschaftskommunikationstypen abgeleitet. Auf Grundlage der Ergebnisse wurden unterschiedliche Wissenschaftskommunikationsmaßnahmen entwickelt, die sich in der Konzeption, den Rezipienten, sowie der Form der Kommunikation und den Inhalten unterscheiden.
Im Rahmen dieser Entwicklung wurde eine Lerneinheit mit Bezug auf die Inhalte des Graduiertenkollegs, bestehend aus einem Lehr-Lern-Experiment und den dazugehörigen Begleitmaterialien, konzipiert. Anschließend wurde die Lerneinheit in eine der Wissenschaftskommunikationsmaßnahmen integriert. Je nach Anforderung an die Doktoranden, wurden die Maßnahmen durch vorbereitende Workshops ergänzt.
Durch einen halboffenen Pre-Post-Fragebogen wurde der Einfluss der Wissenschaftskommunikationsmaßnahmen und der dazugehörigen Workshops auf die Selbstwirksamkeit der Doktoranden evaluiert, um Rückschlüsse darauf zu ziehen, wie sich die Wahrnehmung der eigenen Kommunikationsfähigkeiten durch die Interventionen verändert. Die Ergebnisse deuten darauf hin, dass die einzelnen Wissenschaftskommunikationsmaßnahmen die verschiedenen Typen in unterschiedlicher Weise beeinflussen. Es ist anzunehmen, dass es abhängig von der eigenen Einschätzung der Kommunikationsfähigkeit unterschiedliche Bedürfnisse der Förderung gibt, die durch dedizierte Wissenschaftskommunikationsmaßnahmen berücksichtigt werden können.
Auf dieser Grundlage werden erste Ansätze für eine allgemeingültige Strategie vorgeschlagen, die die individuellen Fähigkeiten zur Wissenschaftskommunikation in einem naturwissenschaftlichen Forschungsverbund fördert.
N2  - As part of an exploratory research approach a concept for science communication was developed and evaluated for a research training group that focuses on photochemical processes. The increasing demand for science communication by politics justifies this approach. Furthermore, for future scientists the communication of their own research is demanded to be an integrative part of good scientific practice. To prepare young researchers for the upcoming task at an early stage, science communication is also required in research associations.
Hence, a preliminary study was conducted to first investigate the requirements of a science communication concept by evaluating doctoral students’ attitudes towards science communication and their communication skills using a questionnaire comprising closed questions. Moreover, science communication types where derived from the data. Based on these results multiple science communication measures that differ in the conception, the recipients, the form of the communication and their content were developed.
With reference to the content of the graduate program an experiment and the accompanying material for teaching was designed. It can be used in schools and extracurricular learning settings. Subsequently, the teaching unit was implemented into one measure. Depending on the requirements of each science communication measure for the doctoral students the measures were complemented by preparatory workshops.
Through a semi-open pre-post questionnaire, the impact of the science communication measures and the associated workshops on the doctoral students’ self-efficacy was evaluated. Also, conclusions about how the perception of their own communication skills changed as a result of the intervention could be drawn. The results suggest that the individual science communication measures affect the different types in various ways. It is likely that depending on one’s assessment of communication skills, there are different funding needs that can be addressed through dedicated measures.
In this way, a generally applicable strategy which promotes individual science communication skills in a scientific research association will be proposed.
KW  - Wissenschaftskommunikation
KW  - Curriculare Innovation
KW  - Chemie
KW  - Elektrolumineszenz
KW  - Lerneinheit
KW  - Elektrolumineszenz-Folie
KW  - Wissenschaftskommunikationstypen
KW  - chemistry
KW  - curriculum innovation
KW  - electroluminescence
KW  - electroluminescent foil
KW  - learning unit
KW  - science communication
KW  - science communication types
Y1  - 2024
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-620357
ER  - 
TY  - JOUR
A1  - Wojcik, Michal
A1  - Brinkmann, Pia
A1  - Zdunek, Rafał
A1  - Riebe, Daniel
A1  - Beitz, Toralf
A1  - Merk, Sven
A1  - Cieslik, Katarzyna
A1  - Mory, David
A1  - Antonczak, Arkadiusz
T1  - Classification of copper minerals by handheld laser-induced breakdown spectroscopy and nonnegative tensor factorisation
JF  - Sensors
N2  - Laser-induced breakdown spectroscopy (LIBS) analysers are becoming increasingly common for material classification purposes. However, to achieve good classification accuracy, mostly noncompact units are used based on their stability and reproducibility. In addition, computational algorithms that require significant hardware resources are commonly applied. For performing measurement campaigns in hard-to-access environments, such as mining sites, there is a need for compact, portable, or even handheld devices capable of reaching high measurement accuracy. The optics and hardware of small (i.e., handheld) devices are limited by space and power consumption and require a compromise of the achievable spectral quality. As long as the size of such a device is a major constraint, the software is the primary field for improvement. In this study, we propose a novel combination of handheld LIBS with non-negative tensor factorisation to investigate its classification capabilities of copper minerals. The proposed approach is based on the extraction of source spectra for each mineral (with the use of tensor methods) and their labelling based on the percentage contribution within the dataset. These latent spectra are then used in a regression model for validation purposes. The application of such an approach leads to an increase in the classification score by approximately 5% compared to that obtained using commonly used classifiers such as support vector machines, linear discriminant analysis, and the k-nearest neighbours algorithm.
KW  - LIBS
KW  - NTF
KW  - HALS
KW  - classification
KW  - copper minerals
Y1  - 2020
U6  - https://doi.org/10.3390/s20185152
SN  - 1424-8220
VL  - 20
IS  - 18
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Kaya, Kerem
A1  - Debsharma, Tapas
A1  - Schlaad, Helmut
A1  - Yagci, Yusuf
T1  - Cellulose-based polyacetals by direct and sensitized photocationic ring-opening polymerization of levoglucosenyl methyl ether
JF  - Polymer Chemistry
N2  - This study aims to explore the photoinitiated cationic ring-opening polymerization of levoglucosenyl methyl ether (LGME), a chemical obtained from the most abundant biomass - cellulose. Direct and sensitized photopolymerizations of LGME using photoinitiators acting at the near UV or visible range in conjunction with diphenyliodonium hexafluoroantimonate (DPI) yielded unsaturated polyacetals with varying molar masses and distributions.
Y1  - 2020
U6  - https://doi.org/10.1039/d0py01307b
SN  - 1759-9954
SN  - 1759-9962
VL  - 11
IS  - 43
SP  - 6884
EP  - 6889
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Yan, Runyu
A1  - Oschatz, Martin
A1  - Wu, Feixiang
T1  - Towards stable lithium-sulfur battery cathodes by combining physical and chemical confinement of polysulfides in core-shell structured nitrogen-doped carbons
JF  - Carbon
N2  - Despite intensive research on porous carbon materials as hosts for sulfur in lithium-sulfur battery cathodes, it remains a problem to restrain the soluble lithium polysulfide intermediates for a long-term cycling stability without the use of metallic or metal-containing species. Here, we report the synthesis of nitrogen-doped carbon materials with hierarchical pore architecture and a core-shell-type particle design including an ordered mesoporous carbon core and a polar microporous carbon shell. The initial discharge capacity with a sulfur loading up to 72 wt% reaches over 900 mA h g(sulf)(ur)(-1) at a rate of C/2. Cycling performance measured at C/2 indicates similar to 90% capacity retention over 250 cycles. In comparison to other carbon hosts, this architecture not only provides sufficient space for a high sulfur loading induced by the high-pore-volume particle core, but also enables a dual effect of physical and chemical confinement of the polysulfides to stabilize the cycle life by adsorbing the soluble intermediates in the polar microporous shell. This work elucidates a design principle for carbonaceous hosts that is capable to provide simultaneous physical-chemical confinement. This is necessary to overcome the shuttle effect towards stable lithium-sulfur battery cathodes, in the absence of additional membranes or inactive metal-based anchoring materials.
KW  - lithium-sulfur battery
KW  - sulfur
KW  - porous carbon
KW  - cathode
KW  - polysulfides
Y1  - 2020
U6  - https://doi.org/10.1016/j.carbon.2020.01.046
SN  - 0008-6223
SN  - 1873-3891
VL  - 161
SP  - 162
EP  - 168
PB  - Elsevier Science
CY  - Amsterdam [u.a.]
ER  - 
TY  - JOUR
A1  - Zhang, Pengfei
A1  - Behl, Marc
A1  - Balk, Maria
A1  - Peng, Xingzhou
A1  - Lendlein, Andreas
T1  - Shape-programmable architectured hydrogels sensitive to ultrasound
JF  - Macromolecular rapid communications
N2  - On-demand motion of highly swollen polymer systems can be triggered by changes in pH, ion concentrations, or by heat. Here, shape-programmable, architectured hydrogels are introduced, which respond to ultrasonic-cavitation-based mechanical forces (CMF) by directed macroscopic movements. The concept is the implementation and sequential coupling of multiple functions (swellability in water, sensitivity to ultrasound, shape programmability, and shape-memory) in a semi-interpenetrating polymer network (s-IPN). The semi-IPN-based hydrogels are designed to function through rhodium coordination (Rh-s-IPNH). These coordination bonds act as temporary crosslinks. The porous hydrogels with coordination bonds (degree of swelling from 300 +/- 10 to 680 +/- 60) exhibit tensile strength sigma(max) up to 250 +/- 60 kPa. Shape fixity ratios up to 90% and shape recovery ratios up to 94% are reached. Potential applications are switches or mechanosensors.
KW  - cavitation-based mechanical force
KW  - rhodium-phosphine coordination bonds
KW  - semi-IPN hydrogels
KW  - shape-memory effect
Y1  - 2020
U6  - https://doi.org/10.1002/marc.201900658
SN  - 1022-1336
SN  - 1521-3927
VL  - 41
IS  - 7
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Akarsu, Pinar
A1  - Grobe, Richard
A1  - Nowaczyk, Julius
A1  - Hartlieb, Matthias
A1  - Reinicke, Stefan
A1  - Böker, Alexander
A1  - Sperling, Marcel
A1  - Reifarth, Martin
T1  - Solid-phase microcontact printing for precise patterning of rough surfaces
BT  - using polymer-tethered elastomeric stamps for the transfer of reactive silanes
JF  - ACS applied polymer materials
N2  - We present a microcontact printing (mu CP) routine suitable to introduce defined (sub-) microscale patterns on surface substrates exhibiting a high capillary activity and receptive to a silane-based chemistry. This is achieved by transferring functional trivalent alkoxysilanes, such as (3-aminopropyl)-triethoxysilane (APTES) as a low-molecular weight ink via reversible covalent attachment to polymer brushes grafted from elastomeric polydimethylsiloxane (PDMS) stamps. The brushes consist of poly{N-[tris(hydroxymethyl)-methyl]acrylamide} (PTrisAAm) synthesized by reversible addition-fragmentation chain-transfer (RAFT)-polymerization and used for immobilization of the alkoxysilane-based ink by substituting the alkoxy moieties with polymer-bound hydroxyl groups. Upon physical contact of the silane-carrying polymers with surfaces, the conjugated silane transfers to the substrate, thus completely suppressing ink-flow and, in turn, maximizing printing accuracy even for otherwise not addressable substrate topographies. We provide a concisely conducted investigation on polymer brush formation using atomic force microscopy (AFM) and ellipsometry as well as ink immobilization utilizing two-dimensional proton nuclear Overhauser enhancement spectroscopy (H-1-H-1-NOESY-NMR). We analyze the mu CP process by printing onto Si-wafers and show how even distinctively rough surfaces can be addressed, which otherwise represent particularly challenging substrates.
KW  - microcontact printing
KW  - capillary-active substrates
KW  - silane chemistry
KW  - PDMS surface grafting
KW  - surface patterning
KW  - shuttled RAFT-polymerization
Y1  - 2021
U6  - https://doi.org/10.1021/acsapm.1c00024
SN  - 2637-6105
VL  - 3
IS  - 5
SP  - 2420
EP  - 2431
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Mazarei, Elham
A1  - Barker, John R.
T1  - CH2 + O-2
BT  - reaction mechanism, biradical and zwitterionic character, and formation of CH2OO, the simplest Criegee intermediate
JF  - Physical chemistry, chemical physics : PCCP ; a journal of European Chemical Societies
N2  - The singlet and triplet potential surfaces for the title reaction were investigated using the CBS-QB3 level of theory. The wave functions for some species exhibited multireference character and required the CASPT2/6-31+G(d,p) and CASPT2/aug-cc-pVTZ levels of theory to obtain accurate relative energies. A Natural Bond Orbital Analysis showed that triplet (CH2OO)-C-3 (the simplest Criegee intermediate) and (CH2O2)-C-3 (dioxirane) have mostly polar biradical character, while singlet (CH2OO)-C-1 has some zwitterionic character and a planar structure. Canonical variational transition state theory (CVTST) and master equation simulations were used to analyze the reaction system. CVTST predicts that the rate constant for reaction of (CH2)-C-1 + O-3(2) is more than ten times as fast as the reaction of (CH2)-C-3 ((XB1)-B-3) + O-3(2) and the ratio remains almost independent of temperature from 900 K to 3000 K. The master equation simulations predict that at low pressures the (CH2O)-C-1 + O-3 product set is dominant at all temperatures and the primary yield of OH radicals is negligible below 600 K, due to competition with other primary reactions in this complex system.
Y1  - 2021
U6  - https://doi.org/10.1039/d1cp04372b
SN  - 1463-9076
SN  - 1463-9084
VL  - 24
IS  - 2
SP  - 914
EP  - 927
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Riemer, Nastja
A1  - Riemer, Martin
A1  - Krüger, Mandy
A1  - Clarkson, Guy J.
A1  - Shipman, Michael
A1  - Schmidt, Bernd
T1  - Synthesis of arylidene-beta-lactams via exo-selective Matsuda-Heck arylation of methylene-beta-lactams
JF  - The journal of organic chemistry : JOC
N2  - exo-Methylene-beta-lactams were synthesized in two steps from commercially available 3-bromo-2-(bromomethyl)-propionic acid and reacted with arene diazonium salts in a Heck-type arylation in the presence of catalytic amounts of Pd(OAc)(2) under ligand-free conditions. The products, arylidene-beta-lactams, were obtained in high yields as single isomers. The beta-hydride elimination step of the Pd-catalyzed coupling reaction proceeds with high exo-regioselectivity and E-stereoselectivity. With aryl iodides, triflates, or bromides, the coupling products were isolated only in low yields, due to extensive decomposition of the starting material at elevated temperatures. This underlines that arene diazonium salts can be superior arylating reagents in Heck-type reactions and yield coupling products in synthetically useful yields and selectivities when conventional conditions fail.
Y1  - 2021
U6  - https://doi.org/10.1021/acs.joc.1c00638
SN  - 0022-3263
SN  - 1520-6904
VL  - 86
IS  - 13
SP  - 8786
EP  - 8796
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Balischewski, Christian
A1  - Choi, Hyung-Seok
A1  - Behrens, Karsten
A1  - Beqiraj, Alkit
A1  - Körzdörfer, Thomas
A1  - Gessner, Andre
A1  - Wedel, Armin
A1  - Taubert, Andreas
T1  - Metal sulfide nanoparticle synthesis with ionic liquids state of the art and future perspectives
JF  - ChemistryOpen
N2  - Metal sulfides are among the most promising materials for a wide variety of technologically relevant applications ranging from energy to environment and beyond. Incidentally, ionic liquids (ILs) have been among the top research subjects for the same applications and also for inorganic materials synthesis. As a result, the exploitation of the peculiar properties of ILs for metal sulfide synthesis could provide attractive new avenues for the generation of new, highly specific metal sulfides for numerous applications. This article therefore describes current developments in metal sulfide nano-particle synthesis as exemplified by a number of highlight examples. Moreover, the article demonstrates how ILs have been used in metal sulfide synthesis and discusses the benefits of using ILs over more traditional approaches. Finally, the article demonstrates some technological challenges and how ILs could be used to further advance the production and specific property engineering of metal sulfide nanomaterials, again based on a number of selected examples.
KW  - Ionic liquids
KW  - ionic liquid crystals
KW  - ionic liquid precursors
KW  - metal
KW  - sulfides
KW  - catalysis
KW  - electrochemistry
KW  - energy materials
KW  - LED
KW  - solar
KW  - cells
Y1  - 2021
U6  - https://doi.org/10.1002/open.202000357
SN  - 2191-1363
VL  - 10
IS  - 2
SP  - 272
EP  - 295
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Quan, Ting
A1  - Haerk, Eneli
A1  - Xu, Yaolin
A1  - Ahmet, Ibbi
A1  - Höhn, Christian
A1  - Mei, Shilin
A1  - Lu, Yan
T1  - Unveiling the formation of solid electrolyte interphase and its temperature dependence in "Water-in-Salt" supercapacitors
JF  - ACS applied materials & interfaces
N2  - "Water-in-salt" (WIS) electrolytes have emerged as an excellent superconcentrated ionic medium for high-power energy storage systems such as supercapacitors due to their extended working potential compared to the conventional dilute aqueous electrolyte. In this work, we have investigated the performance of WIS supercapacitors using hollow carbon nanoplates as electrodes and compared it to that based on the conventional "salt-in-water" electrolytes. Moreover, the potentiostatic electrochemical impedance spectroscopy has been employed to provide an insightful look into the charge transport properties, which also, for the first time, reveals the formation of a solid-electrolyte interphase (SEI and their temperature-dependent impedance for charge transfer and adsorption. Furthermore, the effect of temperature on the electrochemical performance of the WIS supercapacitors in the temperature range from 15 to 60 degrees C has been studied, which presents a gravimetric capacitance of 128 F g(-1) and a volumetric capacitance of 197.12 F cm(-3) at 55 degrees C compared to 87.5 F g(-1) and 134.75 F cm(-3) at 15 degrees C. The in-depth understanding about the formation of SEI layer and the electrochemical performance at different temperatures for WIS supercapacitors will assist the efforts toward designing better aqueous electrolytes for supercapacitors.
KW  - "water-in-salt"
KW  - supercapacitor
KW  - solid electrolyte interphase
KW  - electrochemical impedance spectroscopy
KW  - temperature effect
Y1  - 2021
U6  - https://doi.org/10.1021/acsami.0c19506
SN  - 1944-8244
SN  - 1944-8252
VL  - 13
IS  - 3
SP  - 3979
EP  - 3990
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - CHAP
A1  - Ramadan, Shahenda
A1  - Guerrero, Paula
A1  - Nedielkov, Ruslan
A1  - Klishin, Nikolai
A1  - Dimova, Rumiana
A1  - Silva, Daniel V.
A1  - Möller, Heiko
T1  - Building a mimetic system for unraveling protein-protein interactions on membranes
T2  - European biophysics journal : with biophysics letters ; an international journal of biophysics
Y1  - 2021
U6  - https://doi.org/10.1007/s00249-021-01558-w
SN  - 0175-7571
SN  - 1432-1017
VL  - 50
IS  - SUPPL 1
SP  - S153
EP  - S153
PB  - Springer
CY  - Berlin ; Heidelberg ; New York
ER  - 
TY  - JOUR
A1  - Behl, Marc
A1  - Balk, Maria
A1  - Lützow, Karola
A1  - Lendlein, Andreas
T1  - Impact of block sequence on the phase morphology of multiblock copolymers obtained by high-throughput robotic synthesis
JF  - European polymer journal : EPJ
N2  - The chemical nature, the number length of integrated building blocks, as well as their sequence structure impact the phase morphology of multiblock copolymers (MBC) consisting of two non-miscible block types. We hypothesized that a strictly alternating sequence should favour phase segregation and in this way the elastic properties. A library of well-defined MBCs composed of two different hydrophobic, semi-crystalline blocks providing domains with well-separated melting temperatures (T(m)s) were synthesized from the same type of precursor building blocks as strictly alternating (MBCsalt) or random (MBCsran) MBCs and compared. Three different series of MBCsalt or MBCsran were synthesized by high-throughput synthesis by coupling oligo(e-caprolactone) (OCL) of different molecular weights (2, 4, and 8 kDa) with oligotetrahydrofuran (OTHF, 2.9 kDa) via Steglich esterification in which the molar ratio of the reaction partners was slightly adjusted. Maximum of weight average molecular weight (M-w) were 65,000 g center dot mol(-1), 165,000 g center dot mol(-1), and 168,000 g center dot mol(-1) for MBCsalt and 80,500 g center dot mol(-1), 100,000 g center dot mol(-1), and 147,600 g center dot mol(-1) for MBCsran. When Mw increased, a decrease of both Tms associated to the melting of the OCL and OTHF domains was observed for all MBCs. T-m (OTHF) of MBCsran was always higher than Tm (OTHF) of MBCsalt, which was attributed to a better phase segregation. In addition, the elongation at break of MBCsalt was almost half as high when compared to MBCsran. In this way this study elucidates role of the block length and sequence structure in MBCs and enables a quantitative discussion of the structure-function relationship when two semi-crystalline block segments are utilized for the design of block copolymers.
KW  - Multiblock copolymers
KW  - Sequence structure
KW  - Phase morphology
KW  - Polymer
KW  - library
KW  - Robotic synthesis
KW  - High-throughput
Y1  - 2021
U6  - https://doi.org/10.1016/j.eurpolymj.2020.110207
SN  - 0014-3057
SN  - 1873-1945
VL  - 143
PB  - Elsevier
CY  - Oxford
ER  - 
TY  - JOUR
A1  - Schlappa, Stephanie
A1  - Brenker, Lee Josephine
A1  - Bressel, Lena
A1  - Hass, Roland
A1  - Münzberg, Marvin
T1  - Process characterization of polyvinyl acetate emulsions applying inline photon density wave spectroscopy at high solid contents
JF  - Polymers / Molecular Diversity Preservation International
N2  - The high solids semicontinuous emulsion polymerization of polyvinyl acetate using poly (vinyl alcohol-co-vinyl acetate) as protective colloid is investigated by optical spectroscopy. The suitability of Photon Density Wave (PDW) spectroscopy as inline Process Analytical Technology (PAT) for emulsion polymerization processes at high solid contents (>40% (w/w)) is studied and evaluated. Inline data on absorption and scattering in the dispersion is obtained in real-time. The radical polymerization of vinyl acetate to polyvinyl acetate using ascorbic acid and sodium persulfate as redox initiator system and poly (vinyl alcohol-co-vinyl acetate) as protective colloid is investigated. Starved-feed radical emulsion polymerization yielded particle sizes in the nanometer size regime. PDW spectroscopy is used to monitor the progress of polymerization by studying the absorption and scattering properties during the synthesis of dispersions with increasing monomer amount and correspondingly decreasing feed rate of protective colloid. Results are compared to particle sizes determined with offline dynamic light scattering (DLS) and static light scattering (SLS) during the synthesis.
KW  - photon density wave spectroscopy
KW  - multiple light scattering
KW  - emulsion
KW  - polymerization
KW  - process analytical technology
KW  - polyvinyl acetate
Y1  - 2021
U6  - https://doi.org/10.3390/polym13040669
SN  - 2073-4360
VL  - 13
IS  - 4
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Koc, Julian
A1  - Schardt, Lisa
A1  - Nolte, Kim
A1  - Beyer, Cindy
A1  - Eckhard, Till
A1  - Schwiderowski, Philipp
A1  - Clarke, Jessica L.
A1  - Finlay, John A.
A1  - Clare, Anthony S.
A1  - Muhler, Martin
A1  - Laschewsky, André
A1  - Rosenhahn, Axel
T1  - Effect of dipole orientation in mixed, charge-equilibrated self-assembled monolayers on protein adsorption and marine biofouling
JF  - ACS applied materials & interfaces
N2  - While zwitterionic interfaces are known for their excellent low-fouling properties, the underlying molecular principles are still under debate. In particular, the role of the zwitterion orientation at the interface has been discussed recently. For elucidation of the effect of this parameter, self-assembled monolayers (SAMs) on gold were prepared from stoichiometric mixtures of oppositely charged alkyl thiols bearing either a quaternary ammonium or a carboxylate moiety. The alkyl chain length of the cationic component (11-mercaptoundecyl)-N,N,N-trimethylammonium, which controls the distance of the positively charged end group from the substrate's surface, was kept constant. In contrast, the anionic component and, correspondingly, the distance of the negatively charged carboxylate groups from the surface was varied by changing the alkyl chain length in the thiol molecules from 7 (8-mercaptooctanoic acid) to 11 (12-mercaptododecanoic acid) to 15 (16-mercaptohexadecanoic acid). In this way, the charge neutrality of the coating was maintained, but the charged groups exposed at the interface to water were varied, and thus, the orientation of the dipoles in the SAMs was altered. In model biofouling studies, protein adsorption, diatom accumulation, and the settlement of zoospores were all affected by the altered charge distribution. This demonstrates the importance of the dipole orientation in mixed-charged SAMs for their inertness to nonspecific protein adsorption and the accumulation of marine organisms. Overall, biofouling was lowest when both the anionic and the cationic groups were placed at the same distance from the substrate's surface.
KW  - SAM
KW  - antifouling coatings
KW  - zwitterionic
KW  - XPS
KW  - Navicula perminuta
KW  - Ulva linza
KW  - SPR
Y1  - 2020
U6  - https://doi.org/10.1021/acsami.0c11580
SN  - 1944-8244
SN  - 1944-8252
VL  - 12
IS  - 45
SP  - 50953
EP  - 50961
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Machatschek, Rainhard Gabriel
A1  - Lendlein, Andreas
T1  - Fundamental insights in PLGA degradation from thin film studies
JF  - Journal of controlled release : official journal of the Controlled Release Society and of the Japanese Society of Drug Delivery Systems
N2  - Poly(lactide-co-glycolide)s are commercially available degradable implant materials, which are typically selected based on specifications given by the manufacturer, one of which is their molecular weight. Here, we address the question whether variations in the chain length and their distribution affect the degradation behavior of Poly[(rac-lactide)-co-glycolide]s (PDLLGA). The hydrolysis was studied in ultrathin films at the air-water interface in order to rule out any morphological effects. We found that both for purely hydrolytic degradation as well as under enzymatic catalysis, the molecular weight has very little effect on the overall degradation kinetics of PDLLGAs. The quantitative analysis suggested a random scission mechanism. The monolayer experiments showed that an acidic micro-pH does not accelerate the degradation of PDLLGAs, in contrast to alkaline conditions. The degradation experiments were combined with interfacial rheology measurements, which showed a drastic decrease of the viscosity at little mass loss. The extrapolated molecular weight behaved similar to the viscosity, dropping to a value near to the solubility limit of PDLLGA oligomers before mass loss set in. This observation suggests a solubility controlled degradation of PDLLGA. Conclusively, the molecular weight affects the degradation of PDLLGA devices mostly in indirect ways, e.g. by determining their morphology and porosity during fabrication. Our study demonstrates the relevance of the presented Langmuir degradation method for the design of controlled release systems.
KW  - PDLLGA
KW  - Degradation
KW  - Langmuir monolayer
Y1  - 2019
U6  - https://doi.org/10.1016/j.jconrel.2019.12.044
SN  - 0168-3659
SN  - 1873-4995
VL  - 319
SP  - 276
EP  - 284
PB  - Elsevier
CY  - New York
ER  - 
TY  - JOUR
A1  - Schürmann, Robin
A1  - Titov, Evgenii
A1  - Ebel, Kenny
A1  - Kogikoski Junior, Sergio
A1  - Mostafa, Amr
A1  - Saalfrank, Peter
A1  - Milosavljević, Aleksandar R.
A1  - Bald, Ilko
T1  - The electronic structure of the metal-organic interface of isolated ligand coated gold nanoparticles
JF  - Nanoscale Advances
N2  - Light induced electron transfer reactions of molecules on the surface of noble metal nanoparticles (NPs) depend significantly on the electronic properties of the metal-organic interface. Hybridized metal-molecule states and dipoles at the interface alter the work function and facilitate or hinder electron transfer between the NPs and ligand. X-ray photoelectron spectroscopy (XPS) measurements of isolated AuNPs coated with thiolated ligands in a vacuum have been performed as a function of photon energy, and the depth dependent information of the metal-organic interface has been obtained. The role of surface dipoles in the XPS measurements of isolated ligand coated NPs is discussed and the binding energy of the Au 4f states is shifted by around 0.8 eV in the outer atomic layers of 4-nitrothiophenol coated AuNPs, facilitating electron transport towards the molecules. Moreover, the influence of the interface dipole depends significantly on the adsorbed ligand molecules. The present study paves the way towards the engineering of the electronic properties of the nanoparticle surface, which is of utmost importance for the application of plasmonic nanoparticles in the fields of heterogeneous catalysis and solar energy conversion.
Y1  - 2022
U6  - https://doi.org/10.1039/d1na00737h
SN  - 2516-0230
VL  - 4
IS  - 6
SP  - 1599
EP  - 1607
PB  - Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Harmanli, İpek
A1  - Tarakina, Nadezda
A1  - Antonietti, Markus
A1  - Oschatz, Martin
T1  - "Giant" nitrogen uptake in ionic liquids confined in carbon pores
JF  - Journal of the American Chemical Society
N2  - Ionic liquids are well known for their high gas absorption capacity. It is shown that this is not a solvent constant, but can be enhanced by another factor of 10 by pore confinement, here of the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate (EmimOAc) in the pores of carbon materials. A matrix of four different carbon compounds with micro- and mesopores as well as with and without nitrogen doping is utilized to investigate the influence of the carbons structure on the nitrogen uptake in the pore-confined EmimOAc. In general, the absorption is most improved for IL in micropores and in nitrogen-doped carbon. This effect is so large that it is already seen in TGA and DSC experiments. Due to the low vapor pressure of the IL, standard volumetric sorption experiments can be used to quantify details of this effect. It is reasoned that it is the change of the molecular arrangement of the ions in the restricted space of the pores that creates additional free volume to host molecular nitrogen.
Y1  - 2021
U6  - https://doi.org/10.1021/jacs.1c00783
SN  - 0002-7863
SN  - 1520-5126
VL  - 143
IS  - 25
SP  - 9377
EP  - 9384
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Frieß, Fabian
A1  - Lendlein, Andreas
A1  - Wischke, Christian
T1  - Switching microobjects from low to high aspect ratios using a shape-memory effect
JF  - Soft matter
N2  - Spherical particles from shape-memory polymers (SMP) can be stretched to ellipsoids with high aspect ratio (AR) and temporarily stabilized. They can switch back to low AR upon thermal stimulation. Here, the creation of an alternative shape-switching capability of particles from low to high AR is introduced, where a SMP matrix from polyvinyl alcohol (PVA) is used to create crosslinked high AR particles and to program the embedded micrometer-sized particles from a second SMP (oligo(epsilon-caprolactone) micronetworks, MN) with a low switching temperature T-sw. This programming proceeds through shape-recovery of the PVA matrix, from which the MN are harvested by PVA matrix dissolution. The use of a dissolvable SMP matrix may be a general strategy to efficiently create systems with complex moving capabilities.
Y1  - 2021
U6  - https://doi.org/10.1039/d1sm00947h
SN  - 1744-6848
VL  - 17
IS  - 41
SP  - 9326
EP  - 9331
PB  - Royal Society of Chemistry
CY  - London
ER  - 
TY  - JOUR
A1  - Lau, Skadi
A1  - Gossen, Manfred
A1  - Lendlein, Andreas
T1  - Designing cardiovascular implants taking in view the endothelial basement membrane
JF  - International journal of molecular sciences
N2  - Insufficient endothelialization of cardiovascular grafts is a major hurdle in vascular surgery and regenerative medicine, bearing a risk for early graft thrombosis. Neither of the numerous strategies pursued to solve these problems were conclusive. Endothelialization is regulated by the endothelial basement membrane (EBM), a highly specialized part of the vascular extracellular matrix. Thus, a detailed understanding of the structure-function interrelations of the EBM components is fundamental for designing biomimetic materials aiming to mimic EBM functions. In this review, a detailed description of the structure and functions of the EBM are provided, including the luminal and abluminal interactions with adjacent cell types, such as vascular smooth muscle cells. Moreover, in vivo as well as in vitro strategies to build or renew EBM are summarized and critically discussed. The spectrum of methods includes vessel decellularization and implant biofunctionalization strategies as well as tissue engineering-based approaches and bioprinting. Finally, the limitations of these methods are highlighted, and future directions are suggested to help improve future design strategies for EBM-inspired materials in the cardiovascular field.
KW  - endothelial cells
KW  - bioinstructive implants
KW  - vascular grafts
KW  - tissue
KW  - engineering
KW  - bioprinting
KW  - bioinspired materials
KW  - biological membrane
KW  - endothelial basement membrane
KW  - biomaterial
Y1  - 2021
U6  - https://doi.org/10.3390/ijms222313120
SN  - 1422-0067
VL  - 22
IS  - 23
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Li, Zhen
A1  - Spangenberg, Erik
A1  - Schicks, Judith Maria
A1  - Kempka, Thomas
T1  - Numerical simulation of hydrate formation in the LArge-Scale Reservoir Simulator (LARS)
JF  - Energies : open-access journal of related scientific research, technology development and studies in policy and management
N2  - The LArge-scale Reservoir Simulator (LARS) has been previously developed to study hydrate dissociation in hydrate-bearing systems under in-situ conditions. In the present study, a numerical framework of equations of state describing hydrate formation at equilibrium conditions has been elaborated and integrated with a numerical flow and transport simulator to investigate a multi-stage hydrate formation experiment undertaken in LARS. A verification of the implemented modeling framework has been carried out by benchmarking it against another established numerical code. Three-dimensional (3D) model calibration has been performed based on laboratory data available from temperature sensors, fluid sampling, and electrical resistivity tomography. The simulation results demonstrate that temperature profiles, spatial hydrate distribution, and bulk hydrate saturation are consistent with the observations. Furthermore, our numerical framework can be applied to calibrate geophysical measurements, optimize post-processing workflows for monitoring data, improve the design of hydrate formation experiments, and investigate the temporal evolution of sub-permafrost methane hydrate reservoirs.
KW  - methane hydrate
KW  - temperature sensor
KW  - electrical resistivity tomography
KW  - hydrate formation
KW  - numerical simulation
Y1  - 2022
U6  - https://doi.org/10.3390/en15061974
SN  - 1996-1073
VL  - 15
IS  - 6
PB  - MDPI
CY  - Basel
ER  - 
TY  - JOUR
A1  - Kogikoski Junior, Sergio
A1  - Dutta, Anushree
A1  - Bald, Ilko
T1  - Spatial separation of plasmonic hot-electron generation and a hydrodehalogenation reaction center using a DNA wire
JF  - ACS nano
N2  - Using hot charge carriers far from a plasmonic nanoparticle surface is very attractive for many applications in catalysis and nanomedicine and will lead to a better understanding of plasmon-induced processes, such as hot-charge-carrier- or heat-driven chemical reactions. Herein we show that DNA is able to transfer hot electrons generated by a silver nanoparticle over several nanometers to drive a chemical reaction in a molecule nonadsorbed on the surface. For this we use 8-bromo-adenosine introduced in different positions within a double-stranded DNA oligonucleotide. The DNA is also used to assemble the nanoparticles into nanoparticles ensembles enabling the use of surface-enhanced Raman scattering to track the decomposition reaction. To prove the DNA-mediated transfer, the probe molecule was insulated from the source of charge carriers, which hindered the reaction. The results indicate that DNA can be used to study the transfer of hot electrons and the mechanisms of advanced plasmonic catalysts.
KW  - plasmonics
KW  - DNA nanotechnology
KW  - hot electrons
KW  - charge transfer
KW  - SERS
KW  - superlattices
Y1  - 2021
U6  - https://doi.org/10.1021/acsnano.1c09176
SN  - 1936-0851
SN  - 1936-086X
VL  - 15
IS  - 12
SP  - 20562
EP  - 20573
PB  - American Chemical Society
CY  - Washington
ER  - 
TY  - JOUR
A1  - Fudickar, Werner
A1  - Bauch, Marcel
A1  - Ihmels, Heiko
A1  - Linker, Torsten
T1  - DNA-triggered enhancement of singlet oxygen production by pyridinium alkynylanthracenes
JF  - Chemistry - a European journal
N2  - There is an ongoing interest in O-1(2) sensitizers, whose activity is selectively controlled by their interaction with DNA. To this end, we synthesized three isomeric pyridinium alkynylanthracenes 2 o-p and a water-soluble trapping reagent for O-1(2). In water and in the absence of DNA, these dyes show a poor efficiency to sensitize the photooxygenation of the trapping reagent as they decompose due to electron transfer processes. In contrast, in the presence of DNA O-1(2) is generated from the excited DNA-bound ligand. The interactions of 2 o-p with DNA were investigated by thermal DNA melting studies, UV/vis and fluorescence spectroscopy, and linear and circular dichroism spectroscopy. Our studies revealed an intercalative binding with an orientation of the long pyridyl-alkynyl axis parallel to the main axis of the DNA base pairs. In the presence of poly(dA : dT), all three isomers show an enhanced formation of singlet oxygen, as indicated by the reaction of the latter with the trapping reagent. With green light irradiation of isomer 2 o in poly(dA : dT), the conversion rate of the trapping reagent is enhanced by a factor >10. The formation of O-1(2) was confirmed by control experiments under anaerobic conditions, in deuterated solvents, or by addition of O-1(2) quenchers. When bound to poly(dG : dC), the opposite effect was observed only for isomers 2 o and 2 m, namely the trapping reagent reacted significantly slower. Overall, we showed that pyridinium alkynylanthracenes are very useful intercalators, that exhibit an enhanced photochemical O-1(2) generation in the DNA-bound state.
KW  - Anthracene
KW  - DNA
KW  - intercalations
KW  - photochemistry
KW  - singlet oxygen
Y1  - 2021
U6  - https://doi.org/10.1002/chem.202101918
SN  - 1521-3765
VL  - 27
IS  - 54
SP  - 13591
EP  - 13604
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Goswami, Koushik
T1  - Inertial particle under active fluctuations
BT  - diffusion and work distributions
JF  - Physical review E, Statistical, nonlinear, and soft matter physics
N2  - We study the underdamped motion of a passive particle in an active environment. Using the phase space path integral method we find the probability distribution function of position and velocity for a free and a harmonically bound particle. The environment is characterized by an active noise which is described as the Ornstein-Uhlenbeck process (OUP). Taking two similar, yet slightly different OUP models, it is shown how inertia along with other relevant parameters affect the dynamics of the particle. Further we investigate the work fluctuations of a harmonically trapped particle by considering the trap center being pulled at a constant speed. Finally, the fluctuation theorem of work is validated with an effective temperature in the steady-state limit.
Y1  - 2022
U6  - https://doi.org/10.1103/PhysRevE.105.044123
SN  - 2470-0045
SN  - 2470-0053
VL  - 105
IS  - 4
PB  - American Physical Society
CY  - College Park
ER  - 
TY  - JOUR
A1  - Xie, Dongjiu
A1  - Jouini, Oumeima
A1  - Mei, Shilin
A1  - Quan, Ting
A1  - Xu, Yaolin
A1  - Kochovski, Zdravko
A1  - Lu, Yan
T1  - Spherical polyelectrolyte brushes templated hollow C@MnO nanospheres as sulfur host materials for Li-S batteries
JF  - ChemNanoMat : Chemistry of Nanomaterials for Energy, Biology and More
N2  - Li-S battery has been considered as the next-generation energy storage device, which still suffers from the shuttle effect of lithium polysulfides (LiPSs). In this work, mesoporous hollow carbon-coated MnO nanospheres (C@MnO) have been designed and synthesized using spherical polyelectrolyte brushes (SPB) as template, KMnO4 as MnO precursor, and polydopamine as carbon source to improve the electrochemical performance of Li-S battery. The hollow C@MnO nanospheres enable the combination of physical confinement and chemical adsorption of the LiPSs. The thin carbon coating layer can provide good electrical conductivity and additional physical confinement to polysulfides. Moreover, the encapsulated MnO inside the carbon shell exhibits strong chemical adsorption to polysulfides. The constructed C@MnO/S cathode shows the discharge capacity of 1026 mAh g(-1) at 0.1 C with 79% capacity retention after 80 cycles. The synthesized hollow C@MnO nanoparticles can work as highly efficient sulfur host materials, providing an effective solution to suppress the shuttle effect in Li-S battery.
KW  - hollow nanospheres
KW  - lithium-sulfur battery
KW  - manganese monoxide
KW  - sperical
KW  - polyelectrolyte brushes
Y1  - 2022
U6  - https://doi.org/10.1002/cnma.202100455
SN  - 2199-692X
VL  - 8
IS  - 4
PB  - Wiley-VCH
CY  - Weinheim
ER  - 
TY  - JOUR
A1  - Fischer, Eric Wolfgang
A1  - Werther, Michael
A1  - Bouakline, Foudhil
A1  - Grossmann, Frank
A1  - Saalfrank, Peter
T1  - Non-Markovian vibrational relaxation dynamics at surfaces
JF  - The journal of chemical physics : bridges a gap between journals of physics and journals of chemistr
N2  - Vibrational dynamics of adsorbates near surfaces plays both an important role for applied surface science and as a model lab for studying fundamental problems of open quantum systems. We employ a previously developed model for the relaxation of a D-Si-Si bending mode at a D:Si(100)-(2 x 1) surface, induced by a "bath " of more than 2000 phonon modes [Lorenz and P. Saalfrank, Chem. Phys. 482, 69 (2017)], to extend previous work along various directions. First, we use a Hierarchical Effective Mode (HEM) model [Fischer et al., J. Chem. Phys. 153, 064704 (2020)] to study relaxation of higher excited vibrational states than hitherto done by solving a high-dimensional system-bath time-dependent Schrodinger equation (TDSE). In the HEM approach, (many) real bath modes are replaced by (much less) effective bath modes. Accordingly, we are able to examine scaling laws for vibrational relaxation lifetimes for a realistic surface science problem. Second, we compare the performance of the multilayer multiconfigurational time-dependent Hartree (ML-MCTDH) approach with that of the recently developed coherent-state-based multi-Davydov-D2 Ansatz [Zhou et al., J. Chem. Phys. 143, 014113 (2015)]. Both approaches work well, with some computational advantages for the latter in the presented context. Third, we apply open-system density matrix theory in comparison with basically "exact " solutions of the multi-mode TDSEs. Specifically, we use an open-system Liouville-von Neumann (LvN) equation treating vibration-phonon coupling as Markovian dissipation in Lindblad form to quantify effects beyond the Born-Markov approximation. Published under an exclusive license by AIP Publishing.
KW  - phonons
KW  - Vibrational states
KW  - Chemical dynamics
KW  - Adsorption
KW  - Surface science
KW  - Open quantum systems
KW  - Density-matrix
KW  - Coherent states
KW  - Markov processes
Y1  - 2022
U6  - https://doi.org/10.1063/5.0092836
SN  - 0021-9606
SN  - 1089-7690
SN  - 1520-9032
VL  - 156
IS  - 21
PB  - AIP Publishing
CY  - Melville
ER  - 
TY  - JOUR
A1  - Chea, Sany
A1  - Nguyen, Khac Toan
A1  - Rosencrantz, Ruben R.
T1  - Microwave-Assisted Synthesis of 5 '-O-methacryloylcytidine Using the Immobilized Lipase Novozym 435
JF  - Molecules
N2  - Nucleobase building blocks have been demonstrated to be strong candidates when it comes to DNA/RNA-like materials by benefiting from hydrogen bond interactions as physical properties. Modifying at the 5 ' position is the simplest way to develop nucleobase-based structures by transesterification using the lipase Novozym 435. Herein, we describe the optimization of the lipase-catalyzed synthesis of the monomer 5 '-O-methacryloylcytidine with the assistance of microwave irradiation. Variable reaction parameters, such as enzyme concentration, molar ratio of the substrate, reaction temperature and reaction time, were investigated to find the optimum reaction condition in terms of obtaining the highest yield.
KW  - microwave irradiation
KW  - Novozym 435
KW  - cytidine
KW  - monomer
KW  - smart materials
Y1  - 2022
U6  - https://doi.org/10.3390/molecules27134112
SN  - 1420-3049
VL  - 27
IS  - 13
PB  - MDPI
CY  - Basel
ER  -