@phdthesis{Savatieiev2023,
  author    = {Savatieiev, Oleksandr},
  title     = {Carbon nitride semiconductors: properties and application as photocatalysts in organic synthesis},
  school      = {Universit{\"a}t Potsdam},
  pages     = {272},
  year      = {2023},
  abstract  = {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.},
  language  = {en}
}
@phdthesis{Schlaad2005,
  author    = {Schlaad, Helmut},
  title     = {Polymer self-assembly : adding complexity to mesostructures of diblock copolymers by specific interactions},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-0001824},
  school      = {Universit{\"a}t Potsdam},
  year      = {2005},
  abstract  = {In dieser Arbeit wurde die Rolle selektiver, nicht-kovalenter Wechselwirkungen bei der Selbstorganisation von Diblockcopolymeren untersucht. Durch Einf{\"u}hrung elektrostatischer, dipolarer Wechselwirkungen oder Wasserstoffbr{\"u}ckenbindungen sollte es gelingen, komplexe Mesostrukturen zu erzeugen und die Ordnung vom Nanometerbereich auf gr{\"o}ßere L{\"a}ngenskalen auszuweiten. Diese Arbeit ist im Rahmen von Biomimetik zu sehen, da sie Konzepte der synthetischen Polymer- und Kolloidchemie und Grundprinzipien der Strukturbildung in supramolekularen und biologischen Systemen verbindet. Folgende Copolymersysteme wurden untersucht: (i) Blockionomere, (ii) Blockcopolymere mit chelatisierenden Acetoacetoxyeinheiten und (iii) Polypeptid-Blockcopolymere.},
  language  = {en}
}
@phdthesis{Schmidt2020,
  author    = {Schmidt, Bernhard V. K. J.},
  title     = {Polymers, self-assembly and materials},
  doi       = {10.25932/publishup-48481},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-484819},
  school      = {Universit{\"a}t Potsdam},
  pages     = {VI, 350},
  year      = {2020},
  abstract  = {In der vorliegenden Arbeit wurden die Selbstorganisation von hydrophilen Polymeren, verst{\"a}rkte Hydrogele, sowie anorganische/Polymer Hybridmaterialien untersucht. Dabei beschreibt die Arbeit den Weg von Polymersynthese mittels verschiedener Methoden {\"u}ber Polymerselbstanordnung bis zur Herstellung von Polymermaterialien mit vielversprechenden Eigenschaften f{\"u}r zuk{\"u}nftige Anwendungen. Hydrophile Polymere wurden verwendet, um Mehrphasensysteme herzustellen, Wasser-in-Wasser Emulsionen zu bilden und selbstangeordneten Strukturen zu erzeugen, z. B. Partikel/Aggregate oder hohle Strukturen aus komplett wasserl{\"o}slichen Bausteinen. Die Strukturbildung in w{\"a}ssriger Umgebung wurde ferner f{\"u}r supramolekulare Hydrogele mit definierter Unterstruktur und reversiblem Gelierungsverhalten eingesetzt. Auf dem Gebiet der Hydrogele wurde das anorganische Material graphitisches Kohlenstoffnitrid (g-CN) als Photoinitiator f{\"u}r die Hydrogelsynthese und als Verst{\"a}rker der Gelstruktur beschrieben. Hierbei konnten Hydrogele mit herausragenden Eigenschaften generiert werden, z. B. hohe Kompressibilit{\"a}t, hohe Speichermodule oder Gleitf{\"a}higkeit. Die Kombinationen von g-CN mit verschiedenen Polymeren erlaubte es zudem neue Materialien f{\"u}r die Photokatalyse bereitzustellen. Als weiteres anorganisches Material wurden Metall-organische Ger{\"u}ste (MOFs) mit Polymeren kombiniert. Es konnte gezeigt werden, dass die Verwendung von MOFs in der Polymersynthese einen starken Einfluss auf die erzeugte Polymerstruktur hat und MOFs als Katalysator f{\"u}r Polymerisationen verwendet werden k{\"o}nnen. Zuletzt wurde die MOF Synthese an sich untersucht, wobei Polymeradditive oder L{\"o}sungsmittel eingesetzt wurden um die kristalline Struktur der MOFs zu modulieren. Insgesamt wurden hier verschiedene Errungenschaften f{\"u}r die Polymerchemie beschrieben, z.B. neuartige hydrophile Polymere und Hydrogele, die zur Zeit wichtige Materialien im Polymerbereich durch ihre vielversprechenden Anwendungen im biomedizinischen Sektor darstellen. Außerdem ergab die Kombination von Polymeren mit Materialien aus anderen Bereichen der Chemie, z. B. g-CN und MOFs, neue Materialien mit bemerkenswerten Eigenschaften, die ebenfalls von Interesse f{\"u}r zuk{\"u}nftige Anwendungen sind, z. B. Beschichtungen, Partikeltechnologie und Katalyse.},
  language  = {en}
}
@phdthesis{Strauss2023,
  author    = {Strauß, Volker},
  title     = {Laser-induced carbonization - from fundamentals to applications},
  doi       = {10.25932/publishup-59199},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-591995},
  school      = {Universit{\"a}t Potsdam},
  pages     = {VIII, 78, A245},
  year      = {2023},
  abstract  = {Fabricating electronic devices from natural, renewable resources has been a common goal in engineering and materials science for many years. In this regard, carbon is of special significance due to its biological compatibility. In the laboratory, carbonized materials and their composites have been proven as promising solutions for a range of future applications in electronics, optoelectronics, or catalytic systems. On the industrial scale, however, their application is inhibited by tedious and expensive preparation processes and a lack of control over the processing and material parameters. Therefore, we are exploring new concepts for the direct utilization of functional carbonized materials in electronic applications. In particular, laser-induced carbonization (carbon laser-patterning (CLaP)) is emerging as a new tool for the precise and selective synthesis of functional carbon-based materials for flexible on-chip applications. We developed an integrated approach for on-the-spot laser-induced synthesis of flexible, carbonized films with specific functionalities. To this end, we design versatile precursor inks made from naturally abundant starting compounds and reactants to cast films which are carbonized with an infrared laser to obtain functional patterns of conductive porous carbon networks. In our studies we obtained deep mechanistic insights into the formation process and the microstructure of laser-patterned carbons (LP-C). We shed light on the kinetic reaction mechanism based on the interplay between the precursor properties and the reaction conditions. Furthermore, we investigated the use of porogens, additives, and reactants to provide a toolbox for the chemical and physical fine-tuning of the electronic and surface properties and the targeted integration of functional sites into the carbon network. Based on this knowledge, we developed prototype resistive chemical and mechanical sensors. In further studies, we show the applicability of LP-C as electrode materials in electrocatalytic and charge-storage applications. To put our findings into a common perspective, our results are embedded into the context of general carbonization strategies, fundamentals of laser-induced materials processing, and a broad literature review on state-of-the-art laser-carbonization, in the general part.},
  language  = {en}
}
@phdthesis{Titirici2013,
  author    = {Titirici, Maria-Magdalena},
  title     = {Hydrothermal carbonisation},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-66885},
  school      = {Universit{\"a}t Potsdam},
  year      = {2013},
  abstract  = {The world's appetite for energy is producing growing quantities of CO2, a pollutant that contributes to the warming of the planet and which currently cannot be removed or stored in any significant way. Other natural reserves are also being devoured at alarming rates and current assessments suggest that we will need to identify alternative sources in the near future. With the aid of materials chemistry it should be possible to create a world in which energy use needs not be limited and where usable energy can be produced and stored wherever it is needed, where we can minimize and remediate emissions as new consumer products are created, whilst healing the planet and preventing further disruptive and harmful depletion of valuable mineral assets. In achieving these aims, the creation of new and very importantly greener industries and new sustainable pathways are crucial. In all of the aforementioned applications, new materials based on carbon, ideally produced via inexpensive, low energy consumption methods, using renewable resources as precursors, with flexible morphologies, pore structures and functionalities, are increasingly viewed as ideal candidates to fulfill these goals. The resulting materials should be a feasible solution for the efficient storage of energy and gases. At the end of life, such materials ideally must act to improve soil quality and to act as potential CO2 storage sinks. This is exactly the subject of this habilitation thesis: an alternative technology to produce carbon materials from biomass in water using low carbonisation temperatures and self-generated pressures. This technology is called hydrothermal carbonisation. It has been developed during the past five years by a group of young and talented researchers working under the supervision of Dr. Titirici at the Max-Planck Institute of Colloids and Interfaces and it is now a well-recognised methodology to produce carbon materials with important application in our daily lives. These applications include electrodes for portable electronic devices, filters for water purification, catalysts for the production of important chemicals as well as drug delivery systems and sensors.},
  language  = {en}
}
@phdthesis{Yuan2015,
  author    = {Yuan, Jiayin},
  title     = {Poly(Ionic Liquid)s},
  school      = {Universit{\"a}t Potsdam},
  pages     = {300},
  year      = {2015},
  language  = {en}
}