A novel strategy for fabrication of responsive functional polymer films is based on grafting of several different functional polymers onto a solid substrate at high grafting density, resulting in varied types of polymer brushes. Such an arrangement suggests many interesting applications of the multicomponent polymer brushes, regarding their versatile adaptive surfaces, capable for responding to changes of solvent polarity, pH, temperature, electromagnetic field and other stimuli, generally by reversible swelling. Mixed amphiphilic polystyrene-poly(2-vynil pyridine) (PS-P2VP) brushes are an example for responsive class of smart materials, which can switch between hydrophilic and hydrophobic energetic state upon changes in the quality of surrounding media. The switching of wettability was found to operate in a broad range and was selectively controlled in organic solvents and in aqueous solutions. Another example for an adaptive/switching behavior is addressed to a polymer brush with a remarkable response to the pH and the ionic strength variations of the aqueous solutions. Combination of weak polyacrylic acid, PAA, and weak polybase, P2VP, in the anchored layer allowed one with a small shift of the pH, to obtain a significant effect on the surface and the interfacial properties of the material. Both type of polymer brushes were examined as adsorbing materials for nanoparticles and charged synthetic- and bio-macromolecules. Their adaptive properties were successively linked to the results of the adsorption experiments. The simplest case was adsorption of nano-particles, functionalised with strong ionic groups, onto binary, PAA-P2VP, polyelectrolyte brushes. Maintaining a constant charge density of the adsorbing component (strong polyelectrolyte effect), allowed one to cause and manipulate a privileged swelling of one of the weak polyelectrolyte brush layers, without affecting the adsorbate properties, and to regulate the thickness of adsorbed layer only by the pH signal. In the case of adsorption of macromolecules with tuneable electrical charge (polyampholytes and proteins), the system became more complicated, regarding their environmentally responsive properties, similar to that exhibited by the polymer brushes. The driving forces were regulated by the switching performance of the brush, simply by adjusting the pH and/or ionic strength conditions. The adsorbed amount and morphological changes of polyampholyte layers were investigated as function of pH and was performed on mixed amphiphilic and binary polyelectrolyte brushes. A special emphasis was set on the binary brush capability to take the control over the interfacial performance of attaching proteins. It was found, that the sharp environmental response of the adsorbent (the polymer brush) strongly influences the morphology of adsorbed protein layers, their thickness and properties. Changing the polarity of the substrate allowed one to regulate the adsorption processes qualitatively and quantitatively. The significant aggregation of protein molecules on PS-P2VP brush and their disassembly on PAA-P2VP brush at the same solvent conditions, we devote to the hydrophobic-hydrophilic transition, occurred at the surface by replacing PS with PAA. The protein aggregates, monitored on the surface of PS-P2VP, sufficiently decrease their size, when switching the brush energetic state from hydrophobic to hydrophilic by adjusting the pH of the media. This effect was found to be well controlled by the brush switching phenomenon in hydrophilic-hydrophobic direction and vice versa. In conclusion, we showed how the structural reorganization in thin polymer brush layers of different type may dramatically affect their surface properties. The adaptive behavior in response of external stimuli was found to be a basis for highly specific interactions, depending on geometric factors, conformational state and environment.

The thesis aims to explain the design a prototype of an innovated small engine. It is divided into three main parts. The first part is focused on the analysis of low power DC small engines available on the market. The second part consists of measuring, construction and loss analysis of a DC small engine with permanent magnets. The last part deals with the possible innovations of a small engine with permanent magnets and subsequent implementation of some of them. The innovations are supported by calculations and simulations.

Die Synthese von oberflächengepfropften Polypeptoidbürsten durch die Oberflächeninitiierte Ringoffnungspolmerisation von N-substituierten N-carboxyanhydriden wird beschrieben. Die entstehenden Schichten werden durch Zelladhäsionsexperimente und Oberflächenplasmonenresonanzspektroskopie auf ihre Antibiofouling-Eigenschaften untersucht. UV-Lithographie und Mikrokontaktdrucken wird zur Herstellung von strukturierten Oberflächen verwendet. Eine Funktionalisierung der Strukturen wird mit Fluoreszenzmikroskopie und Fluoreszenzmapping nachgewiesen. Ein zweiter Schwerpunkt befasst sich mit der Synthese von Kompositschichten. Oberflächengepropfte polykationische Polymerbürsten dienen als Einlagerungsmedium für negativ geladene Nanopartikel. Durch calcinieren werden poröse Schichten erhalten. Die Anwendung des Verfahrens auf ein Partikelsystem generiert poröse Core-Shell-Partikel.

Cononsolvency occurs if a mixture of two good solvents causes the collapse or demixing of polymers into a polymer-rich phase in a certain range of compositions of these two solvents. The better solvent is usually called cosolvent and another common solvent is called solvent. So far, the phase-transition mechanism behind cononsolvency is still rather controversially debated in literature. In this thesis, I experimentally investigated the cononsolvency effect of poly(N-isopropylacrylamide) (PNiPAAm) brushes with different grafting density in aqueous alcohol mixtures. I have used Vis-spectroscopic ellipsometry measurements and proved the hypothesis that the cononsolvency transition of PNiPAAm brushes consists of a volume phase-like equilibrium transition. I found a strong collapse transition in PNiPAAm brushes followed by a reentry behavior as observed by ellipsometry measurements. Using a series of alcohols with increasing alkyl-chain length I have demonstrated that the cononsolvency effect is enhanced and shifted to smaller volume fractions of the alcohol. Particularly for the alcohol with increasing hydrophobic property this is correlated with an increasing tendency of demixing between the cosolvent and water. This is apparently in contrast to the hypothesis of strongly associative solvents being the origin of the cononsolvency effect. The hypothesis of preferential adsorption, on the other hand, can account for this case by assuming an increasing hydrophobically driven adsorption of the cosolvent on the polymer chains. The recently proposed adsorption-attraction model based on the concept of preferential adsorption, can be used to predict the corresponding phase-transition behavior. In particularly the model predictions for variation of the grafting density is in agreement with the experimental findings. However, to reflect the imperfect mixing of the longer alcohols in water as well as finite miscibility of the polymers in the common solvent, extensions of the model have to be considered. I have shown that the simplest extension of the model taking into account the Flory-Huggins parameter for polymer and water can account for the qualitative changes observed for temperature changes in my experiments. Both a theoretical analysis and experimental observations show that the phase-transition mechanism of cononsolvency depends on the relative strengths of various interactions in the polymer solutions. A cononsolvency transition can be driven by a strong cosolvent-solvent attraction or by the preferential adsorption of cosolvent onto the polymer. By an extension of the adsorption-attraction model, I report on a comprehensive and quantitative theoretical study of the cononsolvency effect of neutral polymers such as PNiPAAm brushes, macro-gels and single long chains. The extended adsorption-attraction model is able to describe and predict the phase-transition behaviors of these systems in various aqueous alcohol solutions quantitatively. My analysis showed that besides the dominant role of polymer-cosolvent preferential adsorption and the monomer-cosolvent-monomer triple contacts (cosolvent-assisted temporary cross-linking effect) that define the strength of the collapse-transition in the cosolvent-poor region, other effects are shown to be of relevance: The non-ideal mixing between polymer and solvent plays a role in shifting the collapse transition to the lower-concentration region of cosolvent, and an increase of the demixing tendency between cosolvent and solvent on the polymer chains reduces the window width of the cononsolvency transition. Using data from my own experiments and literature I can show that the cononsolvency response of brushes, gels and single long polymer chain can be consistently described with the same model. The model parameters are consistent with their microscopic interpretation. In addition, weakening of the cononsolvency transition in cosolvent-poor aqueous solutions at high hydrostatic pressure can be explained by the suppression of demixing tendency between cosolvent and water, and between polymer and water in the case of PNiPAAm. An investigation of the grafting-density effect in the cononsolvency transition of grafted PNiPAAm polymer, showed that a decrease of grafting density at the collapse state as well as the temperature is fixed, the swollen polymer chains can show various morphologies not limited to collapse brush. In addition, my experimental results clearly showed that the strongest collapse state can be only realized by polymer brushes with moderate grafting densities. My results display the universal character of the cononsolvency effect with respect to series of cosolvents and show that PNiPAAm brushes display a well-defined and sharp collapse transition. This is most pronounced for 1-propanol as cosolvent which is still fully miscible in water. Potential applications are switches built from implementation of brushes in pores and similar concave geometries can be realized by harnessing the cononsolvency effect of stimuli-responsive polymers such as PNiPAAm. As an example of application of cononsolvency effect of grafted polymers, different molecular-weight PNiPAAm polymers are grafted around the rim of solid-state nanopores by using grafting-to method. I demonstrate that small amounts of ethanol admixed to an aqueous solution can trigger the translocation of fluorescence DNA through polymer-decorated nanopores. I can identify the cononsolvency effect as being responsible for this observation which causes an abrupt collapse of the brush by increasing the alcohol content of the aqueous solution followed by a reswelling at higher alcohol concentration. For the first time, I provide a quantitative method to estimate hydrodynamic thickness of a polymer layer which is grafted around the rim of nanopores. Regardless of the grafting density of a grafted PNiPAAm polymer layer around the rim of nanopores, in the alcohol-tris buffer mixtures, the polymer layer displays solvent-composition responsive behaviors in the range of metabolic pH values and room temperatures. Although in this study PNiPAAm was chosen as a model synthetic polymer, I believe in that the conclusions made for PNiPAAm can be also in general extended to other synthetic polymers as well as to biopolymers such as proteins. As a proof of concept of using synthetic polymers to mimic biological functions of cell-membrane channels, my study clearly transpired that cononsolvency effect of polymers can be used as a trigger to change the size of nanopores in analogy to the opening and closure of the gates of cell-membrane channels.:Chapter 1 Background and motivation 4 1.1 Liquid-liquid phase separation 4 1.2 Polymer phase separation in a pure solvent 5 1.3 Polymer phase separation in mixtures of two good solvents 10 1.4 Characterizing cononsolvency transition in experimental study 14 1.5 Research motivation 16 Chapter 2 Phase behaviors of PNiPAAm brushes in alcohol/water mixtures: A combined experimental and theoretical study 17 2.1 Introduction 17 2.2 Materials and Methods 17 2.2.1 Materials 17 2.2.2 Preparation of Polymer Brushes 18 2.2.3 VIS-Spectroscopic Ellipsometry Measurement 18 2.2.4 Determining a polymer brush’s overlap grafting density 19 2.2.5 Test of PNiPAAm solubility in short-chain polyols 20 2.3 The adsorption-attraction model 20 2.4 Equilibrium behavior of cononsolvency transition of PNiPAAm brushes 22 2.5 Role of volume of solvent molecules in the swelling of PNiPAAm brushes 24 2.6 Cononsolvency transition of PNiPAAm brushes in aqueous solutions of a series of alcohol 24 2.7 Isomer effect of alcohol in the cononsolvency transition of PNiPAAm brushes 27 2.8 Role of alcohol-water interaction in the cononsolvency transition of PNiPAAm polymers 28 2.9 Temperature effect in the cononsolvency transition of PNiPAAm brushes 30 2.10 Grafting-density effect in the cononsolvency transition of PNiPAAm brushes 33 2.11 Octopus-shape-micelle morphology of grafted PNiPAAm polymers 34 2.12 Chapter summary 35 2.13 Chapter appendix 37 2.13.1 Data extraction and reprocessing for the molar Gibbs free energy of mixing 37 2.13.2 Temperature effect in the cononsolvency transition of PNiPAAm gels 37 Chapter 3 The extended adsorption-attraction model 41 3.1 Introduction 41 3.2 An extension of the adsorption-attraction model 43 3.3 Numerical solution of the extended adsorption-attraction model 47 3.4 Validation of the extended adsorption-attraction model 50 3.4.1 Cononsolvency transition of polymer brushes and macro-gels in different alcohol-water mixtures 51 3.4.2 An analysis of the enthalpic interaction between cosolvent and solvent 57 3.4.3 The window width of the cononsolvency transition 60 3.4.4 Pressure effect in the cononsolvency transition of PNiPAAm polymers 61 3.4.5 Cononsolvency transition of a single long polymer 65 3.5 Chapter summary 66 3.6 Chapter appendix 67 3.6.1 Chemical potential change of mixing two components 67 3.6.2 The Enthalpic Wilson model 68 3.6.3 Estimation of effective Flory-interaction parameter 73 3.6.4 Crosslink-density effect in the cononsolvency transition of poly(N-isopropylacrylamide) micro-gel and macro-gel 74 3.6.5 Pressure effect on the dimensionless chemical potential change (μ) 75 3.6.6 Pressure effect on the cosolvent-solvent interaction (χcs) 76 3.6.7 Pressure effect on the polymer-solvent interaction (χps) 77 3.6.8 Chemical potential change of DMSO/water mixtures 78 Chapter 4 Gating the translocation of DNA through poly(N-isopropylacrylamide) decorated nanopores using the cononsolvency effect in aqueous environments 80 4.1 Introduction 80 4.2 Methods 80 4.2.1 Preparation of polymer-grafted gold membrane 80 4.2.2 Translocation experiments of fluorescence λ-DNA through nanopores 82 4.2.3 Method of identification and counting of DNA translocation events 84 4.3 Results and discussion 86 4.3.1 Grafting density effect on the swollen behaviors of PNiPAAm polymers around the rim of nanopores 86 4.3.2 Switching effect of polymer chains around the rim of nanopores in the tri-buffer/ethanol mixtures 88 4.3.3 Switching effect of polymer brushes on the flat surface in the tri-buffer/ethanol mixtures 92 4.3.4 An attempt of numerical fit of experimental data using the extended adsorption-attraction model 94 4.4 Chapter summary 95 4.5 Chapter appendix 96 4.5.1 An estimation of grafting density 96 4.5.2 The method of processing data 97 Chapter 5 Concluding remarks and outlooks 100 5.1 Concluding remarks 100 5.2 Outlooks: A preliminary discussion of the cononsolvency transition of polymer solutions 102 References and notes 108 List of figures 119 List of tables 128 Acknowledgements 130 List of publications 131 Erklärung 132

Title: The study on interactions of functional surfaces with biological systems Author: Ivana Víšová Department: Institute of Physics of the Czech Academy of Sciences, Department of optical and biophysical systems. Supervisor: RNDr. Hana Vaisocherová-Lísalová, Ph.D., Institute of Physics of the Czech Academy of Sciences, Department of optical and biophysical systems. Abstract: This work is devoted to the study of processes influencing the performance of functional antifouling polymer brush coatings and their interactions with complex biological media. Specifically, both results of the fundamental and applied research on the i) functionalization processes influencing coating resistance, ii) tailoring of the physico-chemical properties of the antifouling coatings to minimize the nonspecific interactions with complex biological samples, and iii) behavior and performance of the polymer brush coatings in varying environments are presented. Acrylamide and methacrylamide-based polymer brushes with side hydroxyl, carboxybetaine, and sulfobetaine groups were studied, showing the great potential of their optimized copolymer structures as tunable antifouling functionalizable platforms for cell research or biosensor applications. Moreover, newly developed procedures for antifouling properties recovery after EDC/NHC...

The work presented here has a multidisciplinary character, having as a common factor the characterization of self-assembled nanostructures through force spectroscopy. Exploring AFM as a tool for characterizing self-assembly and interaction forces in soft matter nanostructures, three different Bio and nonbiological systems where investigated, all of them share the common characteristic of being soft matter molecular structures at the nanoscale. The studied systems in question are: a) Polyelectrolyte – lipid nanocomposites. Single polyelectrolyte adsorption-desorption from supported lipid bilayers, b) Polyelectrolyte brushes and c) Virus-Like particles (VLPs). The scientific interest and industrial applications for each of these different nanostructures is broad, and their potential uses in the near future ranges from smart nanocontainers for drug and gene delivery, surface platforms for molecular recognition to the development of new nanodevices with ultrasensitive external stimuli responsiveness. These nano-structures are constructed following assembly of smaller subunits and belong to representative examples of soft matter in modern nanotechnology. The stability, behavior, properties and long term durability of these self-organized structures depends strongly on the environmental conditions to which they are exposed since their building mechanism is a balance between attractive noncovalent interactions and momentum transmitted collisions due Brownian motion of the solvent molecules. For example a set of long chain molecules firmly attached to one end to a surface will alter their conformation as the space between them is reduced or the environmental conditions are modified (i.e. ionic strength, pH or temperature). For a highly packed condition, this fuzzy surface known as a polyelectrolyte brush will then behave as a responsive material with tunable responsiveness. Thus the objective in the present case was to investigate the change in morphology and the mechanical response of a polyelectrolyte brush to external forces by application of AFM nanoindentations under different ionic strength conditions. The degree of penetration of the AFM tip through the brush will provide insights into the forces exerted by the brush against the tip. Compressions on the brush should aid to characterize its changes in compressibility for different salt concentrations. For the second chosen system, the interaction between two assembled interfaces was investigated at the single molecular level. A multilayered film formed by the consecutive assembly of oppositely charged polyelectrolytes and subsequently coated with a lipid membrane represents a fascinating soft composite material resembling more than a few structural components emerging in living organisms. The fluid bilayer, thus provide a biocompatible interface where additional functionalities can further be integrated (fusion peptides for instance). The smooth polymer cushion confers not only structural flexibility but also adaptability of the chosen substrate properties to be coated. This type of interface could be useful in the development of novel molecular biosensors with single molecule recognition capacities or in the fabrication of assays against pathogenic agents. The aim of this project was to study the molecular binding mechanism between the last polyelectrolyte layer and the lipid head group of the lower lipid leaflet. Understanding this adsorption mechanism between both interfaces, should likewise contribute to improve the fabrication of lipid coated polymeric nano/micro capsules with targeting properties. For example this could be critical in the field of nonviral gene therapy, where the improvement in the design of condensates of nucleic acids and other polymers with lipids (lipoplexes) are of main interest for its posterior use as delivery vectors. Finally, viral capsids were investigated. These naturally occurring assembled nanocontainers within living organisms stand for a remarkable example of nature’s morphological designs. These structures self-assemble from a small number of different proteins occurring in identical copies. The capsid as a self-assembled structure carries multiple functions: compaction of the genome, protection against external chemical threats, target recognition, structural support and finally facilitating the release of the genome into the host cell. It is highly interesting how these different functions are organized within the capsid which consists, for example, in the case of the norovirus of 180 identical copies of one single protein. Therefore, the mechanical stability and elastic properties of virus-like particles of Rubella and Norovirus were investigated by external application of loading forces with an AFM tip. The measurements were performed under conditions relevant for the virus infection mechanism. The applied compressions on these protein shells at pH values mimicking the virus life cycle will aid to learn about possible internal transitions among proteins which may be important for switching between the various functions of the capsid. The choice of two unrelated viral systems with different entry pathways into the cell and with different morphological architectures is expected to reveal crucial information about the stability and mechanical resistance to deformation of these empty membrane-coated and bare viral capsids. This last might provide clues on the stage of particle disassembly and cargo release during the final step of the infection process.

Stimuli-responsive polymers have aroused enormous interest in fundamental and applied polymer research in the last decades as they exhibit a spontaneous, defined, and reversible adaptation of their physicochemical properties towards environmental conditions. Their switching behavior can be triggered by external physical, chemical or biological stimuli, such as a change in temperature, pH value or the presence of certain enzymes. These materials, often referred to as 'smart' polymers, offer a huge potential for novel (bio-medical) sensors, actuators like artificial muscles and flexible robotics, drug-delivery systems, tissue engineering, and switchable catalysts. For almost all of these applications, responsive polymer chains need to be attached to interfaces such as particles or flat substrates or assembled into constrained architectures, like branched structures, micelles, or cross-linked networks. Although there are strong indications that the assembly of responsive polymers largely impacts their adaptiveness, the underlying structure–property relationships are still poorly understood. Besides the challenge of synthesizing constrained polymeric architectures precisely, the analytical characterization of their responsiveness is challenging too. Despite these obstacles, fundamental scientific characterization is an important tool for making smart polymers accessible for real-life applications. To contribute to this, the overarching objective of this work is to synthesize, characterize, adapt, and control the switching characteristics of a multi-responsive polymeric coating. The responsive polyelectrolyte, poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA), is covalently anchored to flat silicon substrates or gold nanoparticles via three newly developed, distinct grafting-to approaches in a controlled manner. In particular, the thermo-responsive behavior of the nanometer-thick polymer layer in aqueous solutions is being investigated using complementary in-situ techniques such as spectroscopic ellipsometry, attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR spectroscopy) and atomic force microscopy (AFM). Herein, the polymer coating reveals an extraordinary responsiveness, exhibiting two distinct modes of thermo-responses, namely a lower critical solution temperature (LCST) and a multivalent ion induced upper critical solution temperature (UCST). The temperature-dependent switching characteristics of the coating, in terms of switching amplitude, temperature, and sharpness, can be tailored by secondary triggers, such as a change in the pH value, ionic strength, or type of counterions present. In addition to characterizing the interactions between the polymer layer and the aqueous environment on a molecular level, the remarkable impact of thermo-responsiveness on the surface patterning of the coating is exposed. A nanostructured surface of pinned PDMAEMA micelles of tunable size during the UCST transition is opposing a homogenous surface detected both below and above the LCST. Furthermore, the synthetic control over the grafting density of the polymer chains reveals the ambiguous influence of steric constraint on both the LCST and induced UCST transition of the coating for the first time. In summary, the in-depth physicochemical characterization of a multi-responsive polymer coating in this work marks a comprehensive contribution to fundamental advances in constrained responsive polymers and their future applications in tailoring surface properties. / Stimuli-responsive Polymere haben in den letzten Jahrzehnten ein enormes Interesse in der Grundlagen- und angewandten Polymerforschung geweckt, da sie eine spontane, definierte und reversible Anpassung ihrer physikalisch-chemischen Eigenschaften an Umweltbedingungen aufweisen. Ihr Schaltverhalten kann dabei sowohl durch externe physikalische, chemische oder biologische Reize wie zum Beispiel eine Änderung der Temperatur, des pH-Wertes bzw. der Präsenz bestimmter Enzyme, ausgelöst werden. Diese oft als 'intelligente' Polymere bezeichneten Materialien bieten ein großes Potenzial für neuartige (biomedizinische) Sensoren, Aktoren wie künstliche Muskeln und flexible Roboter, Systeme zur Abgabe von Medikamenten, Gewebezüchtung sowie schaltbare Katalysatoren. Für fast alle diese Anwendungen müssen responsive Polymerketten an Grenzflächen wie (Nano-)Partikel oder flache Substrate gebunden bzw. zu sterisch anspruchsvollen Architekturen wie verzweigten Strukturen, polymeren Mizellen oder Netzwerken zusammengefügt werden. Obwohl es deutliche Hinweise darauf gibt, dass die Assemblierung von responsiven Polymeren deren Adaptivität signifikant beeinflusst, sind die zugrunde liegenden Struktur-Eigenschafts-Beziehungen noch wenig bekannt. Neben den hohen Anforderungen der Synthese sterisch eingeschränkter Polymerarchitekturen, ist auch die analytische Charakterisierung ihrer Responsivität anspruchsvoll. Trotz dieser Herausforderungen ist gerade diese grundlegende wissenschaftliche Charakterisierung ein wichtiges Instrument, um intelligente Polymere für reale Anwendungen zugänglich zu machen. Um einen Beitrag dafür zu leisten, ist das übergeordnete Ziel dieser Arbeit die Synthese, Charakterisierung, Anpassung und Regulierung der Schalteigenschaften einer multi-responsiven Polymerbeschichtung. Der responsive Polyelektrolyt, Poly(N,N-dimethylaminoethylmethacrylat) (PDMAEMA), wird über drei neu entwickelte, unterschiedliche Pfropfansätze kontrolliert auf flachen Siliziumsubstraten oder Goldnanopartikeln kovalent verankert. Insbesondere das thermo-responsive Verhalten dieser nur wenigen nanometerdicken Beschichtung wird in wässrigen Lösungen mit komplementären in-situ Techniken wie der spektroskopischen Ellipsometrie, ATR-FTIR (attenuated total reflection Fourier-transform infrared) Spektroskopie sowie AFM (atomic force microscopy) analytisch untersucht. Hierbei zeigt die entwickelte Polymerbeschichtung eine außergewöhnliche Adaptivität bestehend aus zwei unterschiedlichen Arten der Thermoresponsivität, namentlich einer unteren kritischen Entmischungstemperatur (lower critical solution temperature, LCST) und einer durch multivalente Ionen induzierten oberen kritischen Entmischungstemperatur (upper critical solution temperture, UCST). Die Schalteigenschaften der Beschichtung in Bezug auf Schaltamplitude, -temperatur, und Schärfe des Übergangs können durch sekundäre Stimuli, wie eine Änderung des pH-Werts, der Ionenstärke oder der Art der vorhandenen Gegenionen, maßgeschneidert werden. Neben der Charakterisierung der molekularen Wechselwirkungen zwischen Polymerschicht und wässriger Umgebung, wird auch der bemerkenswerte Einfluss der Thermoresponsivität auf die Oberflächenstrukturierung der Beschichtung gezeigt. Eine Nanostrukturierung aus gepinnten PDMAEMA-Mizellen mit einstellbarer Größe während des UCST-Übergangs steht einer homogenen Oberfläche gegenüber, die sowohl unterhalb als auch oberhalb der LCST festgestellt wird. Darüber hinaus zeigt die synthetische Kontrolle der Pfropfdichte der Polymerketten erstmals den ambivalenten Einfluss sterischer Restriktionen sowohl auf den LCST als auch auf den induzierten UCST-Übergang der Beschichtung. Zusammenfassend leistet die tiefgründige physiko-chemische Charakterisierung einer multi-responsiven Polymerbeschichtung in dieser Arbeit einen umfangreichen Beitrag zum grundlegenden Verständnis gepfropfter, responsiver Polymere und ihren künftigen Anwendungen bei der gezielten Anpassung von Oberflächeneigenschaften.

Polymer coatings on periodic nanostructures have facilitated advanced applications in various fields. The performance of these structures is intimately linked to their nanoscale characteristics. Smart polymer coatings responsive to environmental stimuli such as temperature, pH level, and ionic strength have found important uses in these applications. Therefore, to optimize their performance and improve their design, precise characterization techniques are essential for understanding the nanoscale properties of polymer coating, especially in response to stimuli and interactions with the surrounding medium. Due to their layered compositions, applying non-destructive measurement methods by X-ray/neutron scattering is optimal. These approaches offer unique insights into the structure, dynamics, and kinetics of polymeric coatings and interfaces. The caveat is that scattering methods require non-trivial data modeling, particularly in the case of periodic structures, which result in strong correlations between scattered beams. The dynamical theory (DT) model offers an exact model for interpreting off-specular signals from periodically structured surfaces and has been validated on substrates measured by neutron scattering. In this dissertation, we improved the model using a computational optimization approach that simultaneously fits specular and off-specular scattering signals and efficiently retrieves the three-dimensional sample profile with high precision. In addition, we extended this to the case of X-ray scattering. We applied this approach to characterize polymer brushes for nanofluidic applications and protein binding to modulated lipid membranes. This approach opens new possibilities in developing soft matter nanostructured substrates with desired properties for various applications. / Doctor of Philosophy / Polymer coatings on nanopatterned surfaces have recently facilitated advanced applications in various fields, particularly biotechnology. For example, multichannel surfaces coated with polymer can serve as nanofluidic devices for precise control of fluid flow in drug screening and detection of specific biomolecules. Moreover, polymer-coated nanopatterned surfaces, which possess similar properties to the extracellular matrix, provide excellent substrates for biological studies. The performance of these systems is closely tied to their nanoscale features, such as the thickness and conformation of the polymer layers. Therefore, high-resolution non-invasive nanoscale characterization techniques are essential for investigating these coatings to optimize their performance and enhance their design. X-ray/neutron scattering offers a non-destructive measurement method with unique capabilities in the nanoscale characterization of polymer coatings. However, scattering methods require non-trivial data modeling, particularly in the case of layered coatings on patterned surfaces. To tackle this challenge, we improved a dynamical theory (DT) model that allows for precise modeling of neutron and X-ray scattering signals from such systems. Using a computational optimization approach, the model enables efficient retrieval of the three-dimensional sample profile with high accuracy. We applied this approach to characterize polymer brushes for nanofluidic applications and protein binding to modulated lipid membranes. This methodology opens up new avenues for developing customizable, nanostructured substrates made from soft materials that possess tailored properties for a wide range of uses.

The scope of this work is to fathom different possibilities to create functional coatings with polymer brushes. The immobilization of nanoparticles and enzymes is investigated, as well as the affection of their properties by the stimuli-responsiveness of the brushes. Another aspect is the coating of 3D-nanostructures by polymer brushes and the investigation of the resulting functional properties of the hybrid material. The polymer brush coatings are characterized by a variety of microscopic and spectroscopic techniques, with a special emphasis on the establishment of the combinatorial quartz crystal microbalance/spectroscopic ellipsometry technique as a tool to characterize the functional properties of the polymer brush systems insitu. The pH-responsive swelling of the polyelectrolyte brushes poly(acrylic acid) and poly(2-vinylpyridine), as well as the thermoresponsive swelling of poly(N-isopropylacryl amide) is studied in detail by this technique. Poly(2-vinylpyridine) and binary poly(N-isopropylacryl amide)-poly (2-vinylpyridine) brushes are used as templates for the insitu-synthesis of palladium and platinum nanoparticles with catalytic activity. As an example for the use of polymer brushes to immobilize enzymes, the model enzyme glucose oxidase is physically adsorbed to poly (2-vinylpyridine) and poly (acrylic acid) brushes and also covalently bound to poly (acrylic acid) brushes. In the last part of this thesis, sculptured thin films are coated with poly (acrylic acid) and poly (N-isopropylacryl amide) brushes and the swelling characteristics as well as the adsorption behavior of the model protein bovine serum albumin are investigated.

We present a mean field model for a mixture of AB diblock-copolymers and A-block selective nanoparticles confined between two identical non-selective walls. A horizontally symmetric lamellar structure of the nanocomposite is considered where nanoparticles are allowed to segregate between the polymer–wall interfaces. For a fixed value of wall separation, we study changes in the free energy as a function of the number of lamellar layers and the amount of nanoparticle uptake in the A-phase denoted by y = ϕx with 0 ≤ x ≤ 1 for a given value of ϕ, where ϕ is the overall nanoparticle volume fraction. The absorption isotherm for nanoparticle uptake in the A-phase as a function of ϕ shows saturation beyond a threshold value ϕs, and the optimal value of uptake y increases with increasing strength of monomer–nanoparticle attractive interaction. Increasing ϕ above ϕs produces a decrease in the optimal number of lamellar layers which is related to a jump-like transition of the chain extension. The effect of varying film thickness is also studied. By considering A-block selective walls we also investigated a wetting transition of the copolymer film and found the transition to be discontinuous. A corresponding phase diagram is constructed. / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.