Diese Arbeit beschäftigt sich mit der Synthese neuer photoreaktiver Polymere, die bei Bestrahlung mit Licht (Hg-Dampflampe, fs-gepulster Ti:Sa-Laser) definierte Reaktionen durchlaufen. Mittels kontrolliert-radikalischer Polymerisation und anschließender polymeranaloger Reaktion wurden verschiedene Azobenzen-Derivate, Arylazosulfonat-Derivate und photolabil geschützte Aminogruppen (Nitroveratryloxycarbonyl, Nvoc) in Methacrylat-Polymere eingeführt. Diese Strukturen wurden ausführlich hinsichtlich ihrer Struktur und vor allem ihrer photochemischen Eigenschaften (Extinktionskoeffizienten, Zerfallskinetik) untersucht. Dünne Schichten (d<30nm) der so hergestellten Materialien wurden bei der Entwicklung einer neuen photolithographischen Methode, der plasmonischen Nanolithographie, eingesetzt.

No description available.

Pour ce travail de thèse, nous nous sommes intéressés dans une première partie à la conception et à la synthèse de nouveaux matériaux multifonctionnels (LC, photosensible, systèmes moléculaires dendritiques) capables d'être élaborés en films minces anisotropes et doués de propriétés photo-induites. Nous avons réalisé l'étude complète des propriétés mésomorphes de ces nouveaux matériaux et de dérivés structuraux (en fonction de la connectivité dendritique intrinsèque) par la diffraction des rayons X aux petits angles; l’étude de leurs propriétés optiques a également été effectuée. Dans une seconde partie, nous avons fonctionnalisé des nanoparticules d'or avec des ligands dendritiques mésogènes afin d'organiser ces particules dans des structures mésomorphes. Les objectifs principaux de cette partie sont tout d’abord la synthèse d'une "bibliothèque" de nanoparticules mésomorphes dendronisées, et ensuite la caractérisation de réseaux simples formée par l’auto-assemblage des particules précédentes. / The need to expand further the range of mesomorphic organization, develop original materials where different functionalities can be added (i.e. multifunctional), and to design “multitask materials” with tunable properties are particularly interesting and crucial challenges for potential uses in future technologies. On the one hand, we focused on the design and synthesis of multifunctional materials (liquid crystalline, dendritic, photoresponisve) which are suitable for making thin films where photoinduced optical anisotropy and surface relief gratings can be generated. The mesomorphic behaviour of these dendrimers was investigated and also their optical properties. On the other hand, we grafted structurally related protodendritic mesogenic ligands to monodisperse gold nanoparticles to elaborate liquid crystalline hybrids in order to self-organize NPs in periodic arrays. A set of dendronized gold nanohybrids was synthesized to carry out this study.

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No description available.

Light is one of the most advantageous stimuli to manipulate functional materials because it can be applied contactless and with high precision. A common strategy to prepare light-responsive physical systems is the embedding of photoswitchable groups such as the dye molecule azobenzene (azo). Upon irradiation with UV light, azobenzene undergoes photoisomerization from the trans to the cis isomer, whereas blue light triggers the inverse conversion. The two isomers differ with respect to their shape, solubility, and light absorption. Up to now, comparatively little research has been focusing on compounds that unite several photoswitchable groups. Such so-called multiphotochromes are promising multi-state molecular systems that can be controlled by light. In this thesis, the object of study is a star-shaped multiphotochromic molecule denoted TrisAzo. It is composed of three azo groups, which are centrally linked by a light-inert BTA group. The molecule has four photoisomers, ranging from the all-trans to the all-cis isomer. Furthermore, TrisAzo is the elementary building block of light-responsive supramolecular aggregates in solution. Previous experimental works report severe morphological changes of the aggregates under UV–Vis light but the underlying molecular mechanisms are still debated. The objective of this thesis is to elucidate the effects of light on TrisAzo – first, concerning its molecular properties and second, regarding the structure and stability of its supramolecular aggregates. In the presented work, the photoisomers of an azobenzene star with a BTA core are studied for the first time via computational methods, particularly using density functional theory and fully atomistic molecular dynamics (MD) simulations. The solvational and optical properties of TrisAzo are quantified as a function of its isomerization state. The solubility of TrisAzo in polar solvents improves with an increasing fraction of the cis-azo arms due to a redistribution of electron density. The absorption spectra of the TrisAzo isomers are nearly linear superpositions of the individual azo arm spectra but with slight deviations. These deviations indicate weak electronic coupling effects between the connected azo groups. Supramolecular aggregates of TrisAzo molecules in water are modeled using fully atomistic MD simulations for extensive investigations on the molecular scale. In equilibrium conditions, it is verified that randomly distributed TrisAzo molecules self-assemble into column-shaped stacks. Simulations of pre-assembled TrisAzo stacks provide detailed insights into their intermolecular interactions. The binding energies are dominated by π-π interactions between conjugated parts of the stacked molecules, especially the azo groups, while hydrogen bonds between the BTA cores play a subordinate but stabilizing role. To implement the effects of light into the simulations, a stochastic model of the repeated photoisomerization of azobenzene is developed. This model reproduces the photoisomerization kinetics of TrisAzo in good agreement with theory and previous experimental results. Based on this approach, light of various intensities and wavelengths is applied on an equilibrated TrisAzo stack. In contrast to prior assumptions, the simulations indicate that a stacked TrisAzo aggregate irradiated by light does not break or disassemble into separate fragments. The stack instead develops defects in the form of molecular shifts and reorientations. As a result, the aggregate eventually loses its columnar shape. The mechanism and driving forces behind these structural changes are clarified based on the simulation results. Thus, this work provides a new interpretation of the experimentally observed morphological changes. The obtained insights on the molecular scale may facilitate the design of light-responsive gels and supramolecular polymers.:Abstract v Kurzfassung vii 1 Introduction 1 2 Properties of Azobenzene and Azobenzene-Containing Materials 5 2.1 Azobenzene 5 2.1.1 Isomers and Photoisomerization 6 2.1.2 The Photostationary State 10 2.2 Multiphotochromic Molecules Based on Azobenzene 10 2.2.1 Azobenzene Stars 11 2.2.2 The Benzene-1,3,5-Tricarboxamide Linker Unit 11 3 Computational Methods and Models 15 3.1 Density Functional Theory 15 3.1.1 Functional and Basis Set 16 3.1.2 Implicit Solvation Models 17 3.1.3 Time-Dependent Density Functional Theory 17 3.2 Molecular Dynamics Simulations 18 3.2.1 All-Atom MD Simulations 18 3.2.2 Force Fields 19 4 Simulation Techniques 23 4.1 Thermodynamic Integration 23 4.1.1 Implementation in Atomistic Simulations 24 4.2 Modeling Photoisomerization in MD Simulations 27 4.2.1 Implementation of the Rotation Pathway 28 4.3 Modeling Light-Irradiated Azo-Materials in MD Simulations 30 4.3.1 The Cyclic Photoisomerization Model 31 5 Photoisomers of an Azobenzene Star 35 5.1 Object of Study: The Molecule TrisAzo 35 5.1.1 Isomers and Conformers 35 5.2 Ground State Properties in the Gas Phase and in Solvents 36 5.2.1 Energies and Standard Enthalpies of Formation 37 5.2.2 Geometry and Shape Properties 38 5.2.3 Dipole Moments 42 5.2.4 Molecular Properties Upon Hydration in Explicit Water 44 5.3 Solubility 47 5.3.1 Influence of Solvent Polarity 48 5.3.2 Influence of Isomerization State 48 5.3.3 Hydration Free Energy 49 5.4 Absorption Spectra and Intramolecular Coupling 51 5.4.1 Influence of the Number of Azo Groups and Their Isomerization State 52 5.4.2 Effect of the Solvent Polarity 54 5.5 Summary 56 6 Equilibrium Properties of TrisAzo Clusters 59 6.1 Supramolecules of Azobenzene Stars in the Experiment 60 6.1.1 Light-Induced Morphological Transition 60 6.2 Self-Assembly Starting from a Random Distribution 62 6.2.1 Radial Distribution Function 63 6.2.2 Cluster Analysis 65 6.3 Intermolecular Energy of a TrisAzo Dimer 69 6.3.1 Total Intermolecular Energy 70 6.3.2 Energy Decomposition 71 6.4 Structural Properties of Columnar TrisAzo Clusters 75 6.4.1 Considered Cluster Arrangements (Cluster Types) 75 6.4.2 Inner Structure of the Clusters 79 6.4.3 Effect of Cluster Size 79 6.5 Intermolecular Energy of Columnar TrisAzo Clusters 82 6.5.1 Total Intermolecular Energy 82 6.5.2 Energy Decomposition 83 6.5.3 The Role of Hydrogen Bonding 88 6.5.4 Rationalizing the Structural Differences of the Considered Cluster Types 91 6.6 Summary 93 7 Columnar TrisAzo Clusters Under UV–Vis Light 97 7.1 TrisAzo Stacks in the Full Photoisomerization Model 97 7.1.1 Cluster Structure Before and After Irradiation 98 7.1.2 Intermolecular Energy 101 7.2 TrisAzo Stacks in the Cyclic Photosomerization Model 104 7.2.1 Photoisomerization Kinetics 104 7.2.2 Cluster Structure Under Irradiation 108 7.2.3 Intermolecular Energy of TrisAzo Stacks Under Irradiation 112 7.2.4 Mechanism of Defect Formation 116 7.2.5 Comparison with Simulations of Comparable Systems 118 7.3 Summary 118 8 Summary and Outlook 121 8.1 Summary 121 8.2 Outlook 123 A Functional Form of the Force Fields 125 A.1 DREIDING Force Field 125 A.2 Polymer Consistent Force Field (PCFF) 129 B Additional Details about Thermodynamic Integration 133 B.1 Derivation of the Formalism 133 B.2 Avoiding Singularities and Instabilities 134 C Details of the Computational Models 137 C.1 DFT and TD-DFT Calculations 137 C.1.1 DFT Calculations 137 C.1.2 TD-DFT Calculations 138 C.2 MD Simulations of TrisAzo Molecules in PCFF 138 C.2.1 Parametrization 139 C.2.2 Preparation of Initial Configurations 139 C.2.3 Simulation Settings 140 C.3 MD Simulations of TrisAzo Molecules in DREIDING 140 C.3.1 Parametrization 141 C.3.2 Preparation of Initial Configurations 141 C.3.3 Simulation Settings 141 C.4 Intermolecular Energy Calculations of TrisAzo Dimers in PCFF and DREIDING 142 C.5 Visualization of Molecular Structures 142 D Equilibrium Properties of TrisAzo Clusters: Additional Material 143 D.1 From Experiments to Simulations 143 D.2 Cluster Analysis for TrisAzo Self-Assembly: Additional Material 144 D.3 Intermolecular Energy of a TrisAzo Dimer: PCFF Results 145 D.3.1 Total Intermolecular Energy 145 D.3.2 Energy Decomposition 145 D.3.3 Estimated Total Intermolecular Energy of TrisAzo-H 148 D.4 Structural Properties of Columnar TrisAzo Clusters: Additional Material 149 D.5 Intermolecular Energy of Columnar TrisAzo Clusters: Additional Material 150 D.5.1 Defect Detection Algorithm 151 D.6 The Role of Hydrogen Bonds: Additional Material 152 E Columnar TrisAzo Clusters Under UV–Vis Light: Additional Material 155 E.1 TrisAzo Stacks in the Full Photoisomerization Model: Additional Material 155 E.2 TrisAzo Stacks in the Cyclic Photosomerization Model: Additional Material 156 F Code Availability 161 Bibliography 163 List of Publications 183 Copyright of Published Articles 187 Acknowledgements / Danksagung 189 List of Abbreviations 191 List of Symbols 193 List of Physical Constants and Unit Conversions 195 Eidesstattliche Erklärung 197 / Licht ist einer der vorteilhaftesten Stimuli für die Manipulation responsiver Funktionsmaterialien, da es berührungslos und mit hoher Präzision angewendet werden kann. Ein weit verbreiteter Ansatz zur Herstellung lichtresponsiver physikalische Systeme ist der Einbau lichtschaltbarer Gruppen wie das Farbstoffmolekül Azobenzol (Azo). Unter UV-Licht vollzieht Azobenzol eine Photoisomerisation vom trans- zum cis-Isomer, während blaues Licht die umgekehrte Umwandlung auslöst. Die beiden Isomere unterscheiden sich vor allem durch ihre räumliche Gestalt, Löslichkeit und Lichtabsorption. Noch unzureichend erforscht sind Moleküle, die mehrere lichtschaltbare Gruppen in sich vereinen. Solche sogenannten Multiphotochrome sind vielversprechende molekulare Mehrzustandssysteme, die durch Licht geschaltet werden können. Untersuchungsobjekt dieser Arbeit ist ein sternförmiges multiphotochromes Molekül namens TrisAzo. Es besteht aus drei Azogruppen, die zentral über eine gegenüber Licht inerte BTA-Gruppe verknüpft sind. Dementsprechend existieren vier Photoisomere dieses Moleküls, vom all-trans- bis zum all-cis-Isomer. Des Weiteren ist TrisAzo der elementare Baustein lichtempfindlicher supramolekularer Aggregate in Lösung. Frühere experimentelle Arbeiten berichten starke morphologische Strukturänderungen der Aggregate unter Lichteinfluss, jedoch sind die zugrundeliegenden molekularen Mechanismen bisher ungeklärt. Ziel dieser Arbeit ist es, die Auswirkungen von Licht auf TrisAzo aufzuklären, erstens in Bezug auf dessen molekulare Eigenschaften und zweitens hinsichtlich der Struktur und Stabilität der supramolekularen Aggregate. In der vorgestellten Arbeit werden erstmals die Photoisomere eines Azosterns mit BTA-Kern auf Basis computerbasierter Methoden untersucht. Eingesetzt werden dabei Dichtefunktionaltheorie und atomistische Molekulardynamiksimulationen (MD). Insbesondere wird die Löslichkeit und das Lichtabsorptionsverhalten von TrisAzo in Abhängigkeit seines Isomerisationszustands analysiert. Die Löslichkeit von TrisAzo verbessert sich mit steigendem Anteil der cis-Azogruppen aufgrund einer damit einhergehenden Umverteilung der Elektronendichte. Die Absorptionsspektren der TrisAzo-Isomere sind in erster Näherung lineare Superpositionen der Einzelspektren jedes Molekülarms, jedoch mit geringen Abweichungen. Diese Abweichungen deuten auf schwache elektronische Kopplungseffekte zwischen den Azogruppen hin. Supramolekularen Aggregate von TrisAzo-Molekülen in Wasser werden für umfangreiche Untersuchungen auf molekularer Ebene in atomistischen MD-Simulationen modelliert. Im thermodynamischen Gleichgewicht bestätigt sich, dass sich zufällig verteilte TrisAzo-Moleküle in säulenförmig gestapelten Aggregaten zusammenfinden. Weitere Simulationen vorgestapelter TrisAzo-Aggregate liefern detaillierte Rückschlüsse auf deren intermolekulare Wechselwirkungen. Die Bindungsenergien werden von π-π-Wechselwirkungen zwischen den konjugierten Bereichen der aufeinanderliegenden Moleküle dominiert. Wasserstoffbrücken zwischen den BTA-Gruppen haben eine untergeordnete, aber stabilisierende Rolle. Um den Effekt von Licht in die Simulationen einzubauen, ist ein stochastisches Modell für die wiederholte Photoisomerisation der Azogruppen entwickelt worden. Dieses Modell reproduziert die Photoisomerisationskinetik von TrisAzo in guter Übereinstimmung mit Theorie und vorigen Experimenten. Basierend auf diesem Ansatz wird Licht verschiedener Intensitäten und Wellenlängen auf die gestapelten TrisAzo-Aggregate angewandt. Entgegen früherer Annahmen zerfallen die Aggregate daraufhin nicht in Einzelfragmente. Stattdessen entwickeln sie Defekte in Form von Molekülumordnungen sowie -reorientierungen und verlieren dadurch ihre säulenartige Form. Der Mechanismus und die Ursachen dieser Strukturänderungen werden anhand der Simulationen aufgeklärt. Damit liefert diese Arbeit eine neue Interpretation der experimentell beobachteten morphologischen Veränderungen. Die gewonnenen Erkenntnisse können die Entwicklung lichtresponsiver Gele und supramolekularer Polymere unterstützen.:Abstract v Kurzfassung vii 1 Introduction 1 2 Properties of Azobenzene and Azobenzene-Containing Materials 5 2.1 Azobenzene 5 2.1.1 Isomers and Photoisomerization 6 2.1.2 The Photostationary State 10 2.2 Multiphotochromic Molecules Based on Azobenzene 10 2.2.1 Azobenzene Stars 11 2.2.2 The Benzene-1,3,5-Tricarboxamide Linker Unit 11 3 Computational Methods and Models 15 3.1 Density Functional Theory 15 3.1.1 Functional and Basis Set 16 3.1.2 Implicit Solvation Models 17 3.1.3 Time-Dependent Density Functional Theory 17 3.2 Molecular Dynamics Simulations 18 3.2.1 All-Atom MD Simulations 18 3.2.2 Force Fields 19 4 Simulation Techniques 23 4.1 Thermodynamic Integration 23 4.1.1 Implementation in Atomistic Simulations 24 4.2 Modeling Photoisomerization in MD Simulations 27 4.2.1 Implementation of the Rotation Pathway 28 4.3 Modeling Light-Irradiated Azo-Materials in MD Simulations 30 4.3.1 The Cyclic Photoisomerization Model 31 5 Photoisomers of an Azobenzene Star 35 5.1 Object of Study: The Molecule TrisAzo 35 5.1.1 Isomers and Conformers 35 5.2 Ground State Properties in the Gas Phase and in Solvents 36 5.2.1 Energies and Standard Enthalpies of Formation 37 5.2.2 Geometry and Shape Properties 38 5.2.3 Dipole Moments 42 5.2.4 Molecular Properties Upon Hydration in Explicit Water 44 5.3 Solubility 47 5.3.1 Influence of Solvent Polarity 48 5.3.2 Influence of Isomerization State 48 5.3.3 Hydration Free Energy 49 5.4 Absorption Spectra and Intramolecular Coupling 51 5.4.1 Influence of the Number of Azo Groups and Their Isomerization State 52 5.4.2 Effect of the Solvent Polarity 54 5.5 Summary 56 6 Equilibrium Properties of TrisAzo Clusters 59 6.1 Supramolecules of Azobenzene Stars in the Experiment 60 6.1.1 Light-Induced Morphological Transition 60 6.2 Self-Assembly Starting from a Random Distribution 62 6.2.1 Radial Distribution Function 63 6.2.2 Cluster Analysis 65 6.3 Intermolecular Energy of a TrisAzo Dimer 69 6.3.1 Total Intermolecular Energy 70 6.3.2 Energy Decomposition 71 6.4 Structural Properties of Columnar TrisAzo Clusters 75 6.4.1 Considered Cluster Arrangements (Cluster Types) 75 6.4.2 Inner Structure of the Clusters 79 6.4.3 Effect of Cluster Size 79 6.5 Intermolecular Energy of Columnar TrisAzo Clusters 82 6.5.1 Total Intermolecular Energy 82 6.5.2 Energy Decomposition 83 6.5.3 The Role of Hydrogen Bonding 88 6.5.4 Rationalizing the Structural Differences of the Considered Cluster Types 91 6.6 Summary 93 7 Columnar TrisAzo Clusters Under UV–Vis Light 97 7.1 TrisAzo Stacks in the Full Photoisomerization Model 97 7.1.1 Cluster Structure Before and After Irradiation 98 7.1.2 Intermolecular Energy 101 7.2 TrisAzo Stacks in the Cyclic Photosomerization Model 104 7.2.1 Photoisomerization Kinetics 104 7.2.2 Cluster Structure Under Irradiation 108 7.2.3 Intermolecular Energy of TrisAzo Stacks Under Irradiation 112 7.2.4 Mechanism of Defect Formation 116 7.2.5 Comparison with Simulations of Comparable Systems 118 7.3 Summary 118 8 Summary and Outlook 121 8.1 Summary 121 8.2 Outlook 123 A Functional Form of the Force Fields 125 A.1 DREIDING Force Field 125 A.2 Polymer Consistent Force Field (PCFF) 129 B Additional Details about Thermodynamic Integration 133 B.1 Derivation of the Formalism 133 B.2 Avoiding Singularities and Instabilities 134 C Details of the Computational Models 137 C.1 DFT and TD-DFT Calculations 137 C.1.1 DFT Calculations 137 C.1.2 TD-DFT Calculations 138 C.2 MD Simulations of TrisAzo Molecules in PCFF 138 C.2.1 Parametrization 139 C.2.2 Preparation of Initial Configurations 139 C.2.3 Simulation Settings 140 C.3 MD Simulations of TrisAzo Molecules in DREIDING 140 C.3.1 Parametrization 141 C.3.2 Preparation of Initial Configurations 141 C.3.3 Simulation Settings 141 C.4 Intermolecular Energy Calculations of TrisAzo Dimers in PCFF and DREIDING 142 C.5 Visualization of Molecular Structures 142 D Equilibrium Properties of TrisAzo Clusters: Additional Material 143 D.1 From Experiments to Simulations 143 D.2 Cluster Analysis for TrisAzo Self-Assembly: Additional Material 144 D.3 Intermolecular Energy of a TrisAzo Dimer: PCFF Results 145 D.3.1 Total Intermolecular Energy 145 D.3.2 Energy Decomposition 145 D.3.3 Estimated Total Intermolecular Energy of TrisAzo-H 148 D.4 Structural Properties of Columnar TrisAzo Clusters: Additional Material 149 D.5 Intermolecular Energy of Columnar TrisAzo Clusters: Additional Material 150 D.5.1 Defect Detection Algorithm 151 D.6 The Role of Hydrogen Bonds: Additional Material 152 E Columnar TrisAzo Clusters Under UV–Vis Light: Additional Material 155 E.1 TrisAzo Stacks in the Full Photoisomerization Model: Additional Material 155 E.2 TrisAzo Stacks in the Cyclic Photosomerization Model: Additional Material 156 F Code Availability 161 Bibliography 163 List of Publications 183 Copyright of Published Articles 187 Acknowledgements / Danksagung 189 List of Abbreviations 191 List of Symbols 193 List of Physical Constants and Unit Conversions 195 Eidesstattliche Erklärung 197

Organelles are crucial compartments in living cells for carrying out biological events, and cells normally employ compartmentalization to spatially manage their cellular material transport, signaling, and metabolic processes. Engineering biomimetic nanoreactors to replicate biological processes has attracted a lot of interest in recent years. pH-responsive and photo-crosslinked polymersomes, for example, as synthetic vesicles, have tuable membrane permeability and mechanical stability, and may be utilized to build artificial organelles by encapsulating bioactive molecules in their cavity. Most existing reports of stimuli-responsive polymersomes for enzymatic cascade reactions are based on a simple mix of two types of polymersomes loaded with different enzymes, whereas cells process multi-enzyme catalytic systems in which intracellular biological reactions are carried out by combining two or more enzymes in the same organelle. In fact, the most of sophisticated biological functions and features of cells are based on self-organization, the coordination and connection between their cell organelles determines their key functions. Therefore, spatially ordered and controllable self-assembly of polymersomes to construct clusters to simulate complex intracellular biological functions has attracted widespread attention. Here, a simple one-step copper-free click strategy is present to crosslink nanoscale pH-responsive and photo-crosslinked polymersomes (less than 100 nm) to micron-level clusters (more than 90% in 0.5-2 µm range). Various influencing factors in the clustering process and subsequent purification methods were studied to obtain optimal clustered polymeric vesicles. Even if co-clustering the separately loaded polymeric vesicles with different enzymes (glucose oxidase and myoglobin), the overall permeability of the clusters can still be regulated through tuning the pH values on demand. Compared with the conventional enzyme cascade reaction through simple blending polymersomes, the rate of enzymatic cascade reaction increased significantly due to the interconnected complex microstructure established. The connection of catalytic nano-compartments into clusters confining different enzymes of a cascade reaction provide an excellent platform for the development of artificial systems mimicking natural organelles or cells. Although pH-responsive polymersomes present a good membrane permeability in response to alternate pH values and good stability in swelling/shrinking behavior owing to the photo-crosslinked membrane, they are still insufficient to simulate more complex biological activity. The intrinsic pH values for molecules transport are always acidic, whereas the majority of cellular action occurs at physiological pH levels. Due to the closed membrane, the enzyme reaction cannot be carried out efficiently under simulated physiological conditions (pH 7.4). To generate a permeable membrane at a physiological pH value, a new stimulus element must be introduced into existing polymersomes. To self-assemble pH- and light-responsive as well as photo-crosslinked polymersomes, a single azobenzene unit is used as a junction molecule between the hydrophilic and hydrophobic segments of block copolymer. To compare light utilization, block copolymers based on donor-acceptor-substituted azobenzene junction and ether-substituted azobenzene junction were prepared. Besides, the photo-isomerization of novel macroinitiators, block copolymers and polymersomes was also studied to get responsive wavelength ranges of light. The dye release experiments proven the hydrophobic dye on the membrane of polymersomes can release from the membrane under light irradiation. Despite the fact that blue light (400-500 nm) has a higher release efficiency than UV light (365 nm) and ether-substituted azobenzene polymersomes have a slightly higher release efficiency than donor-acceptor-substituted azobenzene polymersomes, the mechanism is still unknown due to the different power of light sources. Furthermore, based on the results of light-driven enzyme reaction, more experiments are required to confirm the light-induced membrane permeability, such as photo-oxidation of substrates and photo-induced deactivation of enzyme. But in general, photo-induced membrane disorder does squeeze the tiny cargo out of the membrane. The single azobenzene unit as the linkage between hydrophilic and hydrophobic block induced membrane pertubation proposes a novel concept in which a trace of azobenzene unit can affect cargo mobility on the membrane of polymersomes and even propagate the fluidity of water molecules to the entire membrane, thereby resulting in membrane permeability. This approach offers a unique framework for the development of biomimetic behaviors under physiological simulated conditions.:Part I Fundamentals 1 Theoretical Background 1.1 Polymersomes 1.1.1 Polymersomes Formation 1.1.2 Self-Assembly Principles of Amphiphilic Block Copolymers (BCPs) 1.1.3 Preparation Methods of Polymersomes 1.1.4 Cargo Loading in Polymersomes 1.2 Clustering Methods of Synthetic Vesicle 1.2.1 Host-Guest Interaction 1.2.2 DNA Hybridization 1.2.3 Copper-Free Click Chemistry 1.3 Stimuli-Responsive Polymersomes with Controllable Membrane Permeability 1.3.1 pH-Responsive Polymersomes 1.3.2 Light-Responsive Polymersomes 2 Motivation and Aim Part II Experiments 3 Materials and Methods 3.1 Materials 3.2 Analytical Methods 4 Clustered pH-Responsive Polymersomes for Enzymatic Cascade Reaction 4.1 Synthetic Methods and Characterization of Block Copolymer (BCP) for Self- Assembly of Polymersomes 4.1.1 Synthesis of Poly(Ethylene Glycol) (PEG) Macroinitiator 4.1.2 Synthesis of Photo-Crosslinker 4.1.3 Synthesis of BCP with Different Terminal Groups 4.1.4 Synthesis of Bis-BCN Poly(ethylene glycol) Crosslinker (BisBCN-PEG) 4.2 Formation of Empty and Loaded Psomes-N3 4.2.1 Formation and Photo-Crosslinking of Empty-Psomes-N3 4.2.2 Preparation of Cy5 Labeled BSA (BSA-Cy5) 4.2.3 Preparation of RhB Labeled Myo (Myo-RhB) 4.2.4 Preparation of Cy5 Labeled GOx (GOx-Cy5) 4.2.5 Formation and Photo-Crosslinking of Loaded Psomes-N3 4.3 Preparation and Purification of Clustered Empty-Psomes-N3 II 4.3.1 Preparation of Clustered Empty-Psomes-N3 at Different Conditions 4.3.2 Optimized Preparation of Clustered Empty-Psomes-N3 4.3.3 Purification Method of Clustered Empty-Psomes-N3 4.3.4 DLS Measurement of the Empty-Psomes-N3 in the Supernatant 4.3.5 Quantification of Removed Psomes-N3 after Centrifugal Purification 4.4 Preparation and Purification of Clustered Enzyme-Psomes-N3: Enzymatic Cascade Reaction 4.4.1 Preparation of Clustered GOx or Myo Loaded Psomes-N3 (GOx-Psomes-N3 or Myo-Psomes-N3) 4.4.2 Enzyme Activity of Myo Samples 4.4.3 Enzyme Activity of GOx Samples 4.5 Preparation and Purification of Co-Clustered Enzyme-Psomes-N3: Enzymatic Cascade Reaction 4.5.1 Preparation of Co-Clustered Myo/GOx-Psomes-N3 4.5.2 Enzyme Activity of Co-Clustered Myo/GOx-Psomes-N3 Samples 5 Light-Driven Enzyme Reaction Based on pH-Responsive Polymersomes 5.1 Synthetic Methods and Characterization of Block Copolymers with Single Azobenzene Unit 5.1.1 Synthesis of Block Copolymer with Donor-Acceptor-Substituted Azobenzene Linkage between Hydrophilic and Hydrophobic Segments (BCP-DA-Azo) 5.1.2 Synthesis of Block Copolymer with Ether Substituted Azobenzene Linkage between Hydrophilic and Hydrophobic Segments (BCP-Azo) 5.2 Photo-Isomerization of Macroinitiator and Block Copolymer with Azobenzene Linkage 5.2.1 Photo-Isomerization of PEG-DA-Azo Macroinitiator Based on Blue Light Irradiation or UV Irradiation 5.2.2 Photo-Isomerization of PEG-Azo Macroinitiator Based on Blue Light Irradiation or UV Irradiation 5.2.3 Photo-Isomerization of BCP-DA-Azo (-) Based on Blue Light Irradiation or UV Irradiation 5.2.4 Photo-Isomerization of BCP-Azo (-) Based on Blue Light Irradiation or UV Irradiation 5.3 Formation and Characterization of Polymersomes with Azobenzene 5.3.1 Self-Assembly of Polymersomes with Azobenzene III 5.3.2 Photo-Isomerization of Psomes-DA-Azo (-) Based on Blue Light Irradiation or UV Irradiation 5.3.3 Photo-Isomerization of Psomes-Azo (-) Based on Blue Light Irradiation or UV Irradiation 5.3.4 Photo-Crosslinking of Polymersomes with Azobenzene 5.3.5 DLS Measurement of Photo-Crosslinked Polymersomes with Azobenzene through pH Titration 5.3.6 Photo-Stability of Polymersomes with Azobenzene 5.3.7 In-Situ Loaded Nile Red in Non-Photo-Crosslinked Polymersomes with Azobenzene (NR-Psomes-DA-Azo (+) or NR-Psomes-Azo (+)) 5.3.8 In-Situ Loaded Myo in Photo-Crosslinked Polymersomes with Azobenzene (Myo-Psomes-DA-Azo (+) or Myo-Psomes-Azo (+)) 5.4 Light-Induced Dye Release from Polymersomes with Azobenzene 5.4.1 Fluorescence Photobleaching of Nile Red under Blue Light or UV Irradiation 5.4.2 Nile Red Release under Blue Light or UV Irradiation 5.5 Light-Driven Enzyme Reaction Based on Polymersomes with Azobenzene Part III Results and Discussions 6 Clustered pH-Responsive Polymersomes for Enzymatic Cascade Reaction 6.1 Aim and Strategy 6.2 Photo-Crosslinked and pH-Responsive Polymersomes 6.2.1 Synthesis and Characterization of Block Copolymers (BCPs) 6.2.2 Formation and Characterization of Polymersomes 6.3 Preparation and Purification of Clustered Empty-Psomes-N3 6.3.1 Key Parameters of Clustering Process 6.3.2 Purification Methods of Clustered Empty-Psomes-N3 6.4 Preparation and Purification of Clustered Empty-Psomes-N3 and Enzyme-Psomes- N3 90 6.4.1 Formation and Characterization of Enzyme in-Situ Loaded Psomes-N3 (Enzyme- Psomes-N3) 6.4.2 Enzyme Location in Polymersomes 6.4.3 Deeper Characterization of Clustered Empty-Psomes-N3 and Clustered Enzyme- Psomes-N3 6.5 Clustered Enzyme-Psomes-N3 for Enzymatic Cascade Reaction 6.5.1 Influence of Enzyme Activity on Clustering Condition IV 6.5.2 Mixed Enzyme-Psomes-N3 for Enzymatic Cascade Reaction 6.5.3 Co-Clustered Enzyme-Psomes-N3 for Enzymatic Cascade Reaction 6.6 Summary 7 Light-Driven Enzyme Reaction Based on pH-Responsive Polymersomes 7.1 Aim and Strategy 7.2 Preparation and Characterization of Light-Responsive Polymersomes 7.2.1 Synthesis and Characterization of BCP with Different Types of Azobenzene Unit 7.2.2 Self-Assembly and Photo-Crosslinking of Light-Responsive Polymersomes 7.2.3 Characterization of Photo-Crosslinked Light-Responsive Polymersomes 7.3 Photo-Isomerization of Azobenzene Containing Polymeric Macromolecules and Vesicles 7.3.1 Photo-Isomerization of Azobenzene Containing PEG Macroinitiators 7.3.2 Photo-Isomerization of Azobenzene Containing BCPs and Polymersomes 7.4 Light-Driven Dye Release from Polymersomes with Azobenzene at Simulated Physiological Conditions 7.4.1 Characterization of In-Situ Nile Red Loaded Polymersomes 7.4.2 Light-Driven Dye Release from Polymersomes at Simulated Physiological Conditions 7.5 Light-Induced Enzyme Reaction in Polymersomes with Azobenzene at Simulated Physiological Conditions 7.5.1 Characterization of Polymersomes in-Situ Loaded Myoglobin 7.5.2 Light-Induced Enzyme Reaction in Polymersomes at Simulated Physiological Conditions 7.6 Summary 8 Conclusion and Outlook Reference List of Figures List of Tables List of Abbreviations and Symbols Appendix Acknowledgements Versicherung

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La chimie supramoléculaire est basée sur l'assemblage non covalent de blocs simples, des petites molécules aux polymères, pour synthétiser des matériaux fonctionnels ou complexes. La poly(4-vinylpyridine) (P4VP) est l'une des composantes supramoléculaires les plus utilisées en raison de sa chaîne latérale composée d’une pyridine pouvant interagir avec de nombreuses espèces, telles que les petites molécules monofonctionnelles et bifonctionnelles, grâce à divers types d'interactions. Dans cette thèse, des assemblages supramoléculaires de P4VP interagissant par liaisons hydrogène avec de petites molécules sont étudiés, en ayant comme objectifs de faciliter l'électrofilage de polymères et de mieux comprendre et d'optimiser la photoréponse des matériaux contenant des dérivés d'azobenzène. Une nouvelle approche est proposée afin d'élargir l'applicabilité de l'électrofilage, une technique courante pour produire des nanofibres. À cet effet, un complexe entre la P4VP et un agent de réticulation bifonctionnel capable de former deux liaisons hydrogène, le 4,4'-biphénol (BiOH), a été préparé pour faciliter le processus d’électrofilage des solutions de P4VP. Pour mieux comprendre ce complexe, une nouvelle méthode de spectroscopie infrarouge (IR) a d'abord été développée pour quantifier l'étendue de la complexation. Elle permet de déterminer un paramètre clé, le rapport du coefficient d'absorption d'une paire de bandes attribuées aux groupements pyridines libres et liées par liaisons hydrogène, en utilisant la 4-éthylpyridine comme composé modèle à l’état liquide. Cette méthode a été appliquée à de nombreux complexes de P4VP impliquant des liaisons hydrogène et devrait être généralement applicable à d'autres complexes polymères. La microscopie électronique à balayage (SEM) a révélé l'effet significatif du BiOH sur la facilité du processus d’électrofilage de P4VP de masses molaires élevées et faibles. La concentration minimale pour former des fibres présentant des perles diminue dans le N, N'-diméthylformamide (DMF) et diminue encore plus lorsque le nitrométhane, un mauvais solvant pour la P4VP et un non-solvant pour le BiOH, est ajouté pour diminuer l'effet de rupture des liaisons hydrogène causé par le DMF. Les liaisons hydrogène dans les solutions et les fibres de P4VP-BiOH ont été quantifiées par spectroscopie IR et les résultats de rhéologie ont démontré la capacité de points de réticulation effectifs, analogues aux enchevêtrements physiques, à augmenter la viscoélasticité de solutions de P4VP pour mieux résister à la formation de gouttelettes. Cette réticulation effective fonctionne en raison d'interactions entre le BiOH bifonctionnel et deux chaînes de P4VP, et entre les groupements hydroxyles du BiOH complexé de manière monofonctionnelle. Des études sur d’autres agents de réticulation de faible masse molaire ont montré que la plus forte réticulation effective est introduite par des groupes d’acide carboxylique et des ions de zinc (II) qui facilitent le processus d’électrofilage par rapport aux groupements hydroxyles du BiOH. De plus, la sublimation est efficace pour éliminer le BiOH contenu dans les fibres sans affecter leur morphologie, fournissant ainsi une méthode élégante pour préparer des fibres de polymères purs dont le processus d’électrofilage est habituellement difficile. Deux complexes entre la P4VP et des azobenzènes photoactifs portant le même groupement tête hydroxyle et différents groupes queue, soit cyano (ACN) ou hydrogène (AH), ont été étudiés par spectroscopie infrarouge d’absorbance structurale par modulation de la polarisation (PM-IRSAS) pour évaluer l'impact des groupements queue sur leur performance lors de l'irradiation avec de la lumière polarisée linéairement. Nous avons constaté que ACN mène à la photo-orientation des chaînes latérales de la P4VP et des azobenzènes, tandis que AH mène seulement à une orientation plus faible des chromophores. La photo-orientation des azobenzènes diminue pour les complexes avec une teneur croissante en chromophore, mais l'orientation de la P4VP augmente. D'autre part, l'orientation résiduelle après la relaxation thermique augmente avec la teneur en ACN, à la fois pour le ACN et la P4VP, mais la tendance opposée est constatée pour AH. Ces différences suggèrent que le moment dipolaire a un impact sur la diffusion rotationnelle des chromophores. Ces résultats contribueront à orienter la conception de matériaux polymères contenant des azobenzène efficaces. / Supramolecular chemistry is based on the non-covalent assembly of simple building blocks, from small molecules to polymers, to synthesize functional or complex materials. Poly(4-vinyl pyridine) (P4VP) is one of the most used supramolecular components because its side-chain pyridine rings can interact with many species, such as monofunctional and bifunctional small molecules, through various types of interactions. In this thesis, supramolecular assemblies of P4VP hydrogen-bonded with various small molecules are studied with the objectives of facilitating the electrospinning of polymers and to better understand and optimize the photoresponse of azobenzene-containing materials. A new approach is proposed to widen the applicability of electrospinning, a common technique to produce thin nanofibers. To this end, a complex between P4VP and a bifunctional hydrogen bond crosslinker, 4,4’-biphenol (BiOH), is prepared to increase the electrospinnability of P4VP solutions. To better understand this complex, a new infrared (IR) spectroscopy method is first developed to quantify the extent of complexation. The method allows determining a key parameter, the absorption coefficient ratio of a pair of bands due to free and hydrogen-bonded pyridine rings, by using 4-ethylpyridine as a liquid model compound. This method is applied to many hydrogen-bonded P4VP complexes and should be generally applicable to other polymer complexes. Scanning electron microscopy (SEM) reveals the significant effect of BiOH on the electrospinnability of P4VP with high and low molecular weights. The minimum concentration for the formation of beaded fibers decreases in N,N’-dimethylformamide (DMF) and to a greater extent when nitromethane, a poor solvent for P4VP and a non-solvent for BiOH, is added to decrease the hydrogen bond breaking effect of DMF. Hydrogen bonding in P4VP-BiOH solutions and fibers is quantified by IR spectroscopy and rheology results demonstrate the capability of the effective crosslinks, as analogs to physical entanglements, of increasing the viscoelasticity of P4VP solutions to better resist the formation of droplets. This effective crosslinking works due to bifunctional interactions of BiOH with two P4VP chains and between the hydroxyl groups of monofunctionally complexed BiOH. Studies of other small crosslinkers show that the stronger effective crosslinking introduced by carboxylic acid groups and zinc (II) ions leads to better electrospinnability than the hydroxyl groups of BiOH. Additionally, sublimation is found to be effective to remove BiOH from fibers without affecting their morphology, providing a smart method for preparing fibers of pure polymers with limited electrospinnability. Two complexes between P4VP and photoactive azobenzenes bearing the same hydroxyl head group and different tail groups, either cyano (ACN) or hydrogen (AH), are studied by polarization modulation infrared structural absorbance spectroscopy (PM-IRSAS) to investigate the impact of the tail groups on their performance upon irradiation with linearly polarized light. We find that ACN leads to photo-orientation of both P4VP side-chains and azobenzenes, while AH only leads to a weaker orientation of the chromophores. Photo-orientation of the azobenzenes decreases for both complexes with increasing chromophore content, but the orientation of P4VP increases. On the other hand, the residual orientation after thermal relaxation increases with increasing ACN content, for both ACN and P4VP, but the opposite trend is found for AH. Such differences suggest the impact of the dipole moment on the rotational diffusion of chromophores. These findings will contribute to directing the design of efficient azobenzene-containing polymer materials.

Gegenstand der Arbeit ist die lichtinduzierte Orientierung von multifunktionalen Polymeren, die u.a. für die Herstellung von optischen Schichten in Flüssigkristalldisplays verwendet werden können. Dafür wurden Polymere entwickelt, die wenigstens eine mesogene und eine lichtsensitive Gruppe enthalten. Diese Gruppen zeigen Eigenschaften, die für die Orientierung der kompletten Polymerfilme verantwortlich sind. Das Material wird dafür zunächst in einem ersten Schritt kurz mit linear polarisiertem Licht bestrahlt, wobei richtungsabhängig eine photochemische Reaktion an der lichtsensitiven Gruppe erfolgt und dadurch ein "Orientierungskeim" gelegt wird. Durch die thermische Ausrichtung der mesogenen Gruppen an den photochemisch generierten "Orientierungskeimen" erfolgt die komplette Orientierung des Filmes in einem zweiten Schritt. Dadurch wird eine hohe optische Anisotropie erhalten. Dieses Verfahren wurde als Zwei-Stufen-Bulk-Orientierungsprozess bezeichnet. <br><br> In der vorliegenden Arbeit wurden die Photoreaktionen verschiedener lichtsensitiver Gruppen, wie z. B. Azobenzen, Stilben und Zimtsäureester und deren Orientierungsfähigkeit in flüssigkristallinen Polymeren untersucht. Der Orientierungsprozess wurde durch die Wahl geeigneter Bestrahlungsbedingungen optimiert. Die Effizienz der Orientierung wurde anhand der sich verändernden winkelabhängigen Absorptionseigenschaften und der Doppelbrechung des Materials analysiert. Es wurde gezeigt, dass eine effiziente lichtinduzierte Orientierung bei einer Vielzahl von flüssigkristallinen Polymeren realisierbar ist. So wurde z. B. erstmalig gefunden, dass durch eine Photo-Fries-Orientierung eine hohe optische Anisotropie erhalten werden kann. Außerdem wurde eine neue lichtsensitive Gruppe auf der Basis von Donor-Akzeptor-substituiertem Ethen entwickelt, die farbneutral ist und durch polarisiertes UV-Licht sowohl orientiert als auch re-orientiert werden kann. <br><br> Es wurden weiterhin Polymere entwickelt, die zusätzlich zu den photosensitiven und flüssigkristallinen Einheiten, fluoreszierende Gruppen enthalten. Die Auswahl geeigneter Fluoreszenzverbindungen erfolgte aufgrund ihrer anisometrischen Form, ihrer Ordnungsparameter in einer niedermolekularen Flüssigkristallmischung und ihrer Photostabilität. Das Orientierungsverhalten von ausgewählten Fluorophoren wurde in sechs Ter- und zwei Copolymeren untersucht. Das Prinzip der Orientierung beruht auf einer kooperativen Ausrichtung der Seitengruppen. Aus diesem Grund kommt dem Nachweis der Kooperativität in der vorliegenden Arbeit eine besondere Stellung zu. <br><br> Durch lichtinduzierte Bulk-Orientierung wurden Filme erhalten, welche durch eine richtungsabhängige Fluoreszenz und Absorption im sichtbaren- oder UV-Bereich charakterisiert sind. Die Fluoreszenz wird durch einige lichtsensitive Verbindungen komplett gelöscht. Die wahlweise erhaltenen anisotropen Filme von farbigen, fluoreszierenden oder farbneutralen Verbindungen, die zudem in kleinen Pixeln von wenigen Mikrometern orientiert werden können, eröffnen vielfältige Möglichkeiten für den Einsatz von multi-funktionalen Polymeren als optische Schichten in Flüssigkristalldisplays. / The work presents the light-induced orientation of multifunctional polymers, which can be used for the preparation of optical films in liquid crystal displays (LCDs). Polymers which contain at least one mesogenic and one photosensitive side group were developed for this approach. The side groups of the specially designed polymers show properties which allow for the orientation of the whole polymer film. Isotropic films of the polymeric material were shortly irradiated with linearly polarised light in a first step. So, a photochemical reaction on the light-sensitive group takes place and results in the generation of "orientational seeds". The complete orientation of the polymer film takes place applying a secondary thermal step which aligns the mesogenic groups near to these "orientational seeds". In this way highly anisotropic films are generated. This method was called two-step-bulk-orientation process. <br><br> The photoreaction of different light-sensitive groups, such as azobenzene, stilbene, cinnamic ester and their ability to orient liquid crystalline polymers were investigated in this thesis. The orientation process was optimised using suitable irradiation conditions. The efficiency of the orientation was analysed measuring the angular dependent absorbance and the birefringence of the material due to the ordering procedure. It was shown, that a light-induced orientation is practicable in a high amount of different liquid crystalline polymers. So, for the first time it was found, that the generation of a high optical anisotropy is achieved as result of the rearrangement of the Photo-Fries-Reaction. Moreover, a new light-sensitive group based on donor-acceptor substituted ethylene was developed, which is colourless and allow the orientation and reorientation using polarised UV light. <br><br> Moreover, polymers were developed, which contain fluorescent groups in addition to the photo-sensitive and mesogenic units. The selection of suitable fluorophores was carried out with respect to their anisometric shape, their order parameter in a low molecular liquid crystalline mixture and their photostability. The orientational behaviour of selected fluorophores in six terpolymers and in two copolymers were investigated. The principle of the ordering is based on the cooperative orientation of the side groups. In this way the verification of the cooperativity of the process plays an important role in this work. <br><br> It was shown, that films can be fabricated by means of the light-induced bulk-orientation, which is characterised by an angular selective fluorescence and absorption in the UV or visible region. The fluorescence was completely quenched by some light-sensitive groups. In this way the anisotropic films became optional coloured, fluorescent or colourless and can be patterned in small anisotropic pixels of some micrometers. So, the developed multifunctional materials and the ordering method open new possibilities for the generation of different types of optical films in LCDs.