@article{ZimmermannStompsSchulteOsseilietal.2020, author = {Zimmermann, Marc and Stomps, Benjamin Ren{\´e} Harald and Schulte-Osseili, Christine and Grigoriev, Dmitry and Ewen, Dirk and Morgan, Andrew and B{\"o}ker, Alexander}, title = {Organic dye anchor peptide conjugates as an advanced coloring agent for polypropylene yarn}, series = {Textile Research Journal}, volume = {91}, journal = {Textile Research Journal}, number = {1-2}, publisher = {Sage Publ.}, address = {London}, issn = {0040-5175}, doi = {10.1177/0040517520932231}, pages = {28 -- 39}, year = {2020}, abstract = {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.}, language = {en} } @article{DengWangXuaetal.2020, author = {Deng, Zijun and Wang, Weiwei and Xua, Xun and Gould, Oliver E. C. and Kratz, Karl and Ma, Nan and Lendlein, Andreas}, title = {Polymeric sheet actuators with programmable bioinstructivity}, series = {PNAS}, volume = {117}, journal = {PNAS}, number = {4}, publisher = {National Academy of Sciences}, address = {Washington, DC}, issn = {1091-6490}, doi = {10.1073/pnas.1910668117}, pages = {1895 -- 1901}, year = {2020}, abstract = {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.}, language = {en} } @article{HartliebMansfieldPerrier2020, author = {Hartlieb, Matthias and Mansfield, Edward D. H. and Perrier, Sebastien}, title = {A guide to supramolecular polymerizations}, series = {Polymer Chemistry}, volume = {11}, journal = {Polymer Chemistry}, number = {6}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1759-9954}, doi = {10.1039/c9py01342c}, pages = {1083 -- 1110}, year = {2020}, abstract = {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.}, language = {en} } @article{FranzToebbensLehmannetal.2020, author = {Franz, Alexandra and T{\"o}bbens, Daniel M. and Lehmann, Frederike and K{\"a}rgell, Martin and Schorr, Susan}, title = {The influence of deuteration on the crystal structure of hybrid halide perovskites: a temperature-dependent neutron diffraction study of FAPbBr(3)}, series = {Acta crystallographica; Section B, Structural science, crystal engineering and materials}, volume = {76}, journal = {Acta crystallographica; Section B, Structural science, crystal engineering and materials}, number = {2}, publisher = {Wiley-Blackwell}, address = {Oxford [u.a.]}, issn = {2052-5206}, doi = {10.1107/S2052520620002620}, pages = {267 -- 274}, year = {2020}, abstract = {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.}, language = {en} } @article{WojcikBrinkmannZduneketal.2020, author = {Wojcik, Michal and Brinkmann, Pia and Zdunek, Rafał and Riebe, Daniel and Beitz, Toralf and Merk, Sven and Cieslik, Katarzyna and Mory, David and Antonczak, Arkadiusz}, title = {Classification of copper minerals by handheld laser-induced breakdown spectroscopy and nonnegative tensor factorisation}, series = {Sensors}, volume = {20}, journal = {Sensors}, number = {18}, publisher = {MDPI}, address = {Basel}, issn = {1424-8220}, doi = {10.3390/s20185152}, pages = {17}, year = {2020}, abstract = {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.}, language = {en} } @article{KayaDebsharmaSchlaadetal.2020, author = {Kaya, Kerem and Debsharma, Tapas and Schlaad, Helmut and Yagci, Yusuf}, title = {Cellulose-based polyacetals by direct and sensitized photocationic ring-opening polymerization of levoglucosenyl methyl ether}, series = {Polymer Chemistry}, volume = {11}, journal = {Polymer Chemistry}, number = {43}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1759-9954}, doi = {10.1039/d0py01307b}, pages = {6884 -- 6889}, year = {2020}, abstract = {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.}, language = {en} } @article{YanOschatzWu2020, author = {Yan, Runyu and Oschatz, Martin and Wu, Feixiang}, title = {Towards stable lithium-sulfur battery cathodes by combining physical and chemical confinement of polysulfides in core-shell structured nitrogen-doped carbons}, series = {Carbon}, volume = {161}, journal = {Carbon}, publisher = {Elsevier Science}, address = {Amsterdam [u.a.]}, issn = {0008-6223}, doi = {10.1016/j.carbon.2020.01.046}, pages = {162 -- 168}, year = {2020}, abstract = {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.}, language = {en} } @article{ZhangBehlBalketal.2020, author = {Zhang, Pengfei and Behl, Marc and Balk, Maria and Peng, Xingzhou and Lendlein, Andreas}, title = {Shape-programmable architectured hydrogels sensitive to ultrasound}, series = {Macromolecular rapid communications}, volume = {41}, journal = {Macromolecular rapid communications}, number = {7}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1022-1336}, doi = {10.1002/marc.201900658}, pages = {7}, year = {2020}, abstract = {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.}, language = {en} } @article{KocSchardtNolteetal.2020, author = {Koc, Julian and Schardt, Lisa and Nolte, Kim and Beyer, Cindy and Eckhard, Till and Schwiderowski, Philipp and Clarke, Jessica L. and Finlay, John A. and Clare, Anthony S. and Muhler, Martin and Laschewsky, Andr{\´e} and Rosenhahn, Axel}, title = {Effect of dipole orientation in mixed, charge-equilibrated self-assembled monolayers on protein adsorption and marine biofouling}, series = {ACS applied materials \& interfaces}, volume = {12}, journal = {ACS applied materials \& interfaces}, number = {45}, publisher = {American Chemical Society}, address = {Washington}, issn = {1944-8244}, doi = {10.1021/acsami.0c11580}, pages = {50953 -- 50961}, year = {2020}, abstract = {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.}, language = {en} } @article{LoewenbergTripodoJulichGruneretal.2020, author = {L{\"o}wenberg, Candy and Tripodo, Giuseppe and Julich-Gruner, Konstanze K. and Neffe, Axel T. and Lendlein, Andreas}, title = {Supramolecular gelatin networks based on inclusion complexes}, series = {Macromolecular bioscience}, volume = {20}, journal = {Macromolecular bioscience}, number = {10}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {1616-5187}, doi = {10.1002/mabi.202000221}, pages = {8}, year = {2020}, abstract = {Hydrogel forming physical networks based on gelatin are an attractive approach toward multifunctional biomaterials with the option of reshaping, self-healing, and stimuli-sensitivity. However, it is challenging to design such gelatin-based hydrogels to be stable at body temperature. Here, gelatin functionalized with desaminotyrosine (DAT) or desaminotyrosyl tyrosine (DATT) side chains is crosslinked with cyclodextrin (CD) dimers under formation of inclusions complexes. The supramolecular networks displayed at room temperature decreased water uptake (200-600 wt\% for DAT-based systems, 200 wt\% for DATT based systems), and increased storage moduli up to 25.6 kPa determined by rheology compared to DAT(T) gelatin. The gel-sol transition temperature increased from 33 up to 42 degrees C. The presented system that is completely based on natural building blocks may form the basis for materials that may potentially respond by dissolution or changes of properties to changes in environmental conditions or to the presence of CD guest molecules.}, language = {en} } @article{PiekarczykHeitmannWeissetal.2020, author = {Piekarczyk, Andreas and Heitmann, Ulrike and Weiß, Karl-Anders and K{\"o}hl, Michael and Bald, Ilko}, title = {Development of a simple setup for temperature dependent mass spectrometric measurements for the investigation of outgassing effects in polymeric materials for solar application}, series = {Polymer testing}, volume = {81}, journal = {Polymer testing}, publisher = {Elsevier}, address = {Oxford}, issn = {0142-9418}, doi = {10.1016/j.polymertesting.2019.106164}, pages = {8}, year = {2020}, abstract = {A simple experimental setup for temperature dependent mass spectrometric measurements has been constructed. It consists of a heated sample chamber and a mass spectrometer and allows for measurements under inert gas and ambient air. Based on initial measurements on two extruded polystyrene (XPS) samples a methodology for the data analysis has been developed. With this methodology the outgassing temperature of volatile compounds, which were used as blowing agents, has been identified. Furthermore, the composition of the blowing agents has been analyzed by temperature dependent mass spectra. The results indicate the use of ambient air in one material and a mixture of the banned blowing agents R142b and R22, both hydrochlorofluorocarbons (HCFC), in the other material. The here described methodology provides an easy to use approach to identify such compounds, for example as part of environmental or quality control.}, language = {en} } @article{SeuffertWintzheimerOppmannetal.2020, author = {Seuffert, Marcel T. and Wintzheimer, Susanne and Oppmann, Maximilian and Granath, Tim and Prieschl, Johannes and Alrefai, Anas and Holdt, Hans-J{\"u}rgen and M{\"u}ller-Buschbaum, Klaus and Mandel, Karl}, title = {An all white magnet by combination of electronic properties of a white light emitting MOF with strong magnetic particle systems}, series = {Journal of materials chemistry : C, Materials for optical and electronic devices}, volume = {8}, journal = {Journal of materials chemistry : C, Materials for optical and electronic devices}, number = {45}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {2050-7526}, doi = {10.1039/d0tc03473h}, pages = {16010 -- 16017}, year = {2020}, abstract = {A multi-component particle system was developed that combines the properties of white color, white light emission and strong magnetism on the macroscopic and microscopic scale. The system is constituted by combination of an inorganic white core with either hard or soft magnetic properties and a white light emitting MOF. The key towards this achievement is the supraparticulate character constituted by a magnetic core, of either magnetite or alpha-Fe, surrounded by titania and silica nanoparticles of a certain size in a loose structural shell-arrangement as white components and finally the white light emitting metal-organic framework (MOF) EuTb@IFP-1 as building blocks of a core-shell structure. The supraparticles are created by forced assembly of the inorganic compounds and by combining spray-drying and postsynthetic modification by solvothermal chemistry. Thereby, the gap is bridged that homogenous compounds are either strongly magnetic, white in appearance or white light emitting. The composites presented herein inherit these properties intrinsically as electronic properties. The white characteristics are based on all optical properties that enable white: light reflection, refraction, and light emission. This work shifts the paradigm that strong magnetic materials are always expected to be intrinsically dark.}, language = {en} } @article{LiebigSarhanSchmittetal.2020, author = {Liebig, Ferenc and Sarhan, Radwan Mohamed and Schmitt, Clemens Nikolaus Zeno and Th{\"u}nemann, Andreas F. and Prietzel, Claudia Christina and Bargheer, Matias and Koetz, Joachim}, title = {Gold nanotriangles with crumble topping and their influence on catalysis and surface-enhanced raman spectroscopy}, series = {ChemPlusChem}, volume = {85}, journal = {ChemPlusChem}, number = {3}, publisher = {Wiley-VCH}, address = {Weinheim}, issn = {2192-6506}, doi = {10.1002/cplu.201900745}, pages = {519 -- 526}, year = {2020}, abstract = {By adding hyaluronic acid (HA) to dioctyl sodium sulfosuccinate (AOT)-stabilized gold nanotriangles (AuNTs) with an average thickness of 7.5 +/- 1 nm and an edge length of about 175 +/- 17 nm, the AOT bilayer is replaced by a polymeric HA-layer leading to biocompatible nanoplatelets. The subsequent reduction process of tetrachloroauric acid in the HA-shell surrounding the AuNTs leads to the formation of spherical gold nanoparticles on the platelet surface. With increasing tetrachloroauric acid concentration, the decoration with gold nanoparticles can be tuned. SAXS measurements reveal an increase of the platelet thickness up to around 14.5 nm, twice the initial value of bare AuNTs. HRTEM micrographs show welding phenomena between densely packed particles on the platelet surface, leading to a crumble formation while preserving the original crystal structure. Crumbles crystallized on top of the platelets enhance the Raman signal by a factor of around 20, and intensify the plasmon-driven dimerization of 4-nitrothiophenol (4-NTP) to 4,4 '-dimercaptoazobenzene in a yield of up to 50 \%. The resulting crumbled nanotriangles, with a biopolymer shell and the absorption maximum in the second window for in vivo imaging, are promising candidates for biomedical sensing.}, language = {en} } @article{BaldSolov'yovMasonetal.2020, author = {Bald, Ilko and Solov'yov, Ilia A. and Mason, Nigel J. and Solov'yov, Andrey V.}, title = {Special issue}, series = {The European physical journal. D, Atomic, molecular, optical and plasma physics}, volume = {74}, journal = {The European physical journal. D, Atomic, molecular, optical and plasma physics}, number = {4}, publisher = {Springer}, address = {Berlin}, issn = {1434-6060}, doi = {10.1140/epjd/e2020-10134-4}, pages = {75 -- 82}, year = {2020}, abstract = {The structure, formation and dynamics of both animate and inanimate matter on the nanoscale are a highly interdisciplinary field of rapidly emerging research engaging a broad community encompassing experimentalists, theorists, and technologists. It is relevant for a large variety of molecular and nanosystems of different origin and composition and concerns numerous phenomena originating from physics, chemistry, biology, or materials science. This Topical Issue presents a collection of original research papers devoted to different aspects of structure and dynamics on the nanoscale. Some of the contributions discuss specific applications of the research results in several modern technologies and in next generation medicine. Most of the works of this topical issue were reported at the Fifth International Conference on Dynamics of Systems on the Nanoscale (DySoN) - the premier forum for the presentation of cutting-edge research in this field that was held in Potsdam, Germany in October of 2018.}, language = {en} } @article{StraussWangDelacroixetal.2020, author = {Strauss, Volker and Wang, Huize and Delacroix, Simon and Ledendecker, Marc and Wessig, Pablo}, title = {Carbon nanodots revised}, series = {Chemical science}, volume = {11}, journal = {Chemical science}, number = {31}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {2041-6520}, doi = {10.1039/d0sc01605e}, pages = {8256 -- 8266}, year = {2020}, abstract = {Luminescent compounds obtained from the thermal reaction of citric acid and urea have been studied and utilized in different applications in the past few years. The identified reaction products range from carbon nitrides over graphitic carbon to distinct molecular fluorophores. On the other hand, the solid, non-fluorescent reaction product produced at higher temperatures has been found to be a valuable precursor for the CO2-laser-assisted carbonization reaction in carbon laser-patterning. This work addresses the question of structural identification of both, the fluorescent and non-fluorescent reaction products obtained in the thermal reaction of citric acid and urea. The reaction products produced during autoclave-microwave reactions in the melt were thoroughly investigated as a function of the reaction temperature and the reaction products were subsequently separated by a series of solvent extractions and column chromatography. The evolution of a green molecular fluorophore, namely HPPT, was confirmed and a full characterization study on its structure and photophysical properties was conducted. The additional blue fluorescence is attributed to oligomeric ureas, which was confirmed by complementary optical and structural characterization. These two components form strong hydrogen-bond networks which eventually react to form solid, semi-crystalline particles with a size of similar to 7 nm and an elemental composition of 46\% C, 22\% N, and 29\% O. The structural features and properties of all three main components were investigated in a comprehensive characterization study.}, language = {en} } @article{PerovicAloniMastaietal.2020, author = {Perovic, Milena and Aloni, Sapir Shekef and Mastai, Yitzhak and Oschatz, Martin}, title = {Mesoporous carbon materials with enantioselective surface obtained by nanocasting for selective adsorption of chiral molecules from solution and the gas phase}, series = {Carbon}, volume = {170}, journal = {Carbon}, publisher = {Elsevier}, address = {Oxford}, issn = {0008-6223}, doi = {10.1016/j.carbon.2020.08.010}, pages = {550 -- 557}, year = {2020}, abstract = {Separation of enantiomers is an everlasting challenge in chemistry, catalysis, and synthesis of pharmaceuticals. The design and fabrication of chiral adsorbent materials is a promising way to increase the surface area of chiral information, as well as to maximize the available surface for the adsorption of one enantiomer. Porous materials such as silica or metal-organic-frameworks are established compounds in this field, due to their well-defined surface structure and ease of functionalization with chiral groups. As another class of porous materials, carbons provide the advantages of high thermal and chemical stability, resistance against moisture, electrical conductivity, and widely tunable pore size. Although they are well established in many adsorption-related applications, carbons received far less attention in enantioselective adsorption processes because the controlled functionalization of their surface is rather difficult due to the chemically heterogeneous atoms in the network. A suitable approach to overcome this limitation is the synthesis of chiral carbons directly from chiral precursors. So far, chiral carbons synthesized from chiral precursors used salt-templating as a way of introducing porosity, which resulted in mainly microporous materials or materials with broad pore size distribution. In the present study, the possibility of combining nanocasting as an alternative templating approach with chiral ionic liquids as a carbon precursor is demonstrated. Chiral recognition is measured in the gas phase, by adsorption of chiral gas, as well as in the solution, by using isothermal titration calorimetry. (C) 2020 Elsevier Ltd. All rights reserved.}, language = {en} } @article{LuetzowWeigelLendlein2020, author = {L{\"u}tzow, Karola and Weigel, Thomas and Lendlein, Andreas}, title = {Solvent-based fabrication method for magnetic, shape-memory nanocomposite foams}, series = {MRS advances}, volume = {5}, journal = {MRS advances}, number = {14-15}, publisher = {Cambridge Univ. Press}, address = {Cambridge}, issn = {2059-8521}, doi = {10.1557/adv.2019.422}, pages = {785 -- 795}, year = {2020}, abstract = {This paper presents shape-memory foams that can be temporarily fixed in their compressed state and be expanded on demand. Highly porous, nanocomposite foams were prepared from a solution of polyetherurethane with suspended nanoparticles (mean aggregate size 90 nm) which have an iron(III) oxide core with a silica shell. The polymer solution with suspended nanoparticles was cooled down to -20 degrees C in a two-stage process, which was followed by freeze-drying. The average pore size increases with decreasing concentration of nanoparticles from 158 mu m to 230 mu m while the foam porosity remained constant. After fixation of a temporary form of the nanocomposite foams, shape recovery can be triggered either by heat or by exposure to an alternating magnetic field. Compressed foams showed a recovery rate of up to 76 +/- 4\% in a thermochamber at 80 degrees C, and a slightly lower recovery rate of up to 65 +/- 4\% in a magnetic field.}, language = {en} } @article{HoffmannMachatschekLendlein2020, author = {Hoffmann, Falk and Machatschek, Rainhard Gabriel and Lendlein, Andreas}, title = {Understanding the impact of crystal lamellae organization on small molecule diffusion using a Monte Carlo approach}, series = {MRS advances : a journal of the Materials Research Society (MRS)}, volume = {5}, journal = {MRS advances : a journal of the Materials Research Society (MRS)}, number = {52-53}, publisher = {Cambridge University Press}, address = {Cambridge}, issn = {2059-8521}, doi = {10.1557/adv.2020.386}, pages = {2737 -- 2749}, year = {2020}, abstract = {Many physicochemical processes depend on the diffusion of small molecules through solid materials. While crystallinity in polymers is advantageous with respect to structure performance, diffusion in such materials is difficult to predict. Here, we investigate the impact of crystal morphology and organization on the diffusion of small molecules using a lattice Monte Carlo approach. Interestingly, diffusion determined with this model does not depend on the internal morphology of the semi-crystalline regions. The obtained insight is highly valuable for developing predictive models for all processes in semi-crystalline polymers involving mass transport, like polymer degradation or drug release, and provide design criteria for the time-dependent functional behavior of multifunctional polymer systems.}, language = {en} } @article{GaebertRosenstinglLinsleretal.2020, author = {G{\"a}bert, Chris and Rosenstingl, Tobias and Linsler, Dominic and Dienwiebel, Martin and Reinicke, Stefan}, title = {Programming viscosity in silicone oils}, series = {ACS applied polymer materials}, volume = {2}, journal = {ACS applied polymer materials}, number = {12}, publisher = {ACS Publications}, address = {Washington, DC}, issn = {2637-6105}, doi = {10.1021/acsapm.0c00794}, pages = {5460 -- 5468}, year = {2020}, abstract = {Programmable oils feature tunable viscosity and therefore possess potential for technical improvements and innovative solutions in many lubricated applications. Herein, we describe the first assessment of the variability of rheological properties of light-programmable 9-anthracene ester-terminated polydimethylsiloxanes (PDMS-As), including implications that arise with UV-light as an external trigger. We applied a modified rheometer setup that enables the monitoring of dynamic moduli during exposure to UV-light. The reversible dimerization of anthracene esters is used to either link PDMS chains by UV-A radiation (365 nm) or cleave chains by UV-C radiation (254 nm) or at elevated temperatures (>130 degrees C). Thermal cleavage fully restores the initial material properties, while the photochemical cleavage of dimers occurs only to a limited extent. Prolonged UV radiation causes material damage and in turn reduces the range of programmable rheological properties. The incomplete cleavage contributes to a gradual buildup of viscosity over a course of several switching cycles, which we suggest to result from chain length-dependent reaction kinetics. Material property gradients induced during radiation due to attenuation of the light beam upon its passing through the oil layer have to be considered, emphasizing the need for proper mixing protocols during the programming step. The material in focus shows integrated photorheology and is suggested to improve the performance of silicone oils in friction systems.}, language = {en} } @article{IzraylitGouldKratzetal.2020, author = {Izraylit, Victor and Gould, Oliver E. C. and Kratz, Karl and Lendlein, Andreas}, title = {Investigating the phase-morphology of PLLA-PCL multiblock copolymer/PDLA blends cross-linked using stereocomplexation}, series = {MRS advances}, volume = {5}, journal = {MRS advances}, number = {14-15}, publisher = {Cambridge Univ. Press}, address = {New York}, issn = {2059-8521}, doi = {10.1557/adv.2019.465}, pages = {699 -- 707}, year = {2020}, abstract = {The macroscale function of multicomponent polymeric materials is dependent on their phase-morphology. Here, we investigate the morphological structure of a multiblock copolymer consisting of poly(L-lactide) and poly(epsilon-caprolactone) segments (PLLA-PCL), physically cross-linked by stereocomplexation with a low molecular weight poly(D-lactide) oligomer (PDLA). The effects of blend composition and PLLA-PCL molecular structure on the morphology are elucidated by AFM, TEM and SAXS. We identify the formation of a lattice pattern, composed of PLA domains within a PCL matrix, with an average domain spacing d0 = 12 - 19 nm. The size of the PLA domains were found to be proportional to the block length of the PCL segment of the copolymer and inversely proportional to the PDLA content of the blend. Changing the PLLA-PCL / PDLA ratio caused a shift in the melt transition Tm attributed to the PLA stereocomplex crystallites, indicating partial amorphous phase dilution of the PLA and PCL components within the semicrystalline material. By elucidating the phase structure and thermal character of multifunctional PLLA-PCL / PDLA blends, we illustrate how composition affects the internal structure and thermal properties of multicomponent polymeric materials. This study should facilitate the more effective incorporation of a variety of polymeric structural units capable of stimuli responsive phase transitions, where an understanding the phase-morphology of each component will enable the production of multifunctional soft-actuators with enhanced performance.}, language = {en} }