Energy harvesting using ferrofluid in OHP. Characterization of as-synthesized (bare) and surface-modified ferrofluid samples was performed using Fourier transform infrared spectroscopy, dynamic light scattering, X-ray powder diffraction, transmission electron microscopy, and atomic force microscopy. These ferrofluids were tested in a novel oscillating heat pipe set-up was utilized to harvest electricity, demonstrating the concept of ferrofluidic induction. Cobalterrite nanoparticles surface-modified with citric acid demonstrated good magnetic strengths and generated voltages close to those of the as-synthesized ferrofluids while maintaining dispersion. Surface modification of ferrous nanoparticles with SRP. Thermo responsive polymer poly(N-isopropylacrylamide) was successfully grown from the surface of cobalt-zinc ferrite nanoparticles. A dual responsive block copolymer, pH and thermo responsive comprised of poly(itaconic) acid and poly(N-isopropylacrylamide) was successfully polymerized from the surface of ferrous oxide nanoparticles. These composite having magnetic properties along with stimulus can be used in applications such as controlled drug delivery and similar biomedical applications.

A scalable method for the synthesis of polyethylene terephthalamide microcapsules grafted with polyacrylic acid to enable pH responsiveness has been developed. Microcapsules were produced by interfacial polymerisation of an oil-in-water emulsion in a 2 L batch reactor and subsequently circulated through an external loop reactor for UV irradiative surface grafting. Ungrafted microcapsule samples yielded 1.0 - 1.2 g desiccated capsules per experiment. Initial production trials were subject to severe agglomeration, observed during dialysis of the microcapsules with 30 % (v/v) ethanol solution. Lowering of the terephthaloyl dichloride monomer concentration, to 0.2 mol L⁻¹ in the chloroform / cyclohexane (3 : 1) organic solution, alleviated this unwanted agglomeration. Laser diffraction particle size analysis revealed microcapsules were produced with a 51 µm average diameter. A purpose built external loop irradiation reactor was used to facilitate graft polymerisation of acrylic acid on the microcapsules, using 254 nm UV light at 19 mW cm⁻². Characterisation of the external loop flow regime showed a mild deviation from ideal plug flow, with a vessel dispersion number of 0.014 and a Reynolds number of 1310. Confirmation of monomer polymerisation was ascertained by back titration and Fourier transform infrared spectroscopy. No distinction between homopolymer and grafted polyacrylic acid could be made by these characterisation methods. A Taguchi analysis on variables influencing grafting revealed high temperature to contribute most significantly to graft yield, followed by a long irradiation period. The development of a packed column pulse response method for testing pH response showed a high repeatability. However, release profile testing of a microcapsule slurry with an observed graft yield of 1.13 mmol g⁻¹ did not provide a definitive pH-based release of mPEG 5000 or PEGylated TAMRA dye. Determination of acrylic acid polymerisation kinetics following UV irradiation of the microcapsules is required for future optimisation of a functional graft yield.

Poly(N-isopropylacrylamide) (PNIPAM), a temperature responsive polymer, undergoes a phase change at a lower critical solution temperature (LCST) in aqueous solutions. For PNIPAM this temperature is 32 °C in water. Below the LCST, the polymer is readily solvated by water. As the temperature of the solution increases, the polymer undergoes a phase transition so that above the LCST it is no longer water soluble. The LCST of PNIPAM may be changed by the addition of salt solutions from the Hofmeister series which will follow the Hofmeister effect for salting-in and salting-out the polymer. Temperature responsive polymers may be grafted to a surface in a variety of methods to create responsive thin films that exhibit a change in wettability. The surface wettability is directly related to the polymers ability to be solvated in its coil conformation. When PNIPAM is grafted to a surface, the surface becomes alternatively hydrophobic and hydrophilic in response to both temperature and the anions in the Hofmeister series which take the surface either above or below the LCST of PNIPAM. The synthesis of responsive nanocomposite grafts was successfully applied to glass slides and three-dimensional surfaces, porous glass frits which were capable of controlling the passive flow rate. The nanocomposite graft was assembled in a covalent layer-by-layer approach to create more chemically robust surfaces, and also to incorporate nanoparticles into the graft for increased surface roughness and therefore improve wettability response. Because of a much greater inherent roughness to a glass frit, characterization of the polymers and nanoparticles was performed before they were covalently bound to the surface. The final product, a functionalized frit with a PNIPAM/SiO2 nanocomposite graft, was analyzed by observing changes in the passive permeation rate of the frit between water and salt solutions. These changes in flow were indicative of the surface bound PNIPAM changing between its hydrophilic and hydrophobic conformation in response to water and concentrations of kosmotropic salts such as sodium sulfate and sodium citrate. In addition to the solute response, the frit was also determined to be responsive to temperature and concentration. Water exhibited a passive flow rate 1000 times faster than a kosmotropic salt but had a similar flow rate to that a chaotropic salt. By measuring the flow rate of 0.5 M Na2SO4 at ~7 °C in a cold room and at room temperature it was observed that sodium sulfate in the cold room passed through the frit at a rate 100 times faster than at room temperature. Because of the hysteresis of PNIPAM documented in literature, washing procedures were kept consistent between experiments to achieve more reproducible results. It was concluded that the frits were temperature responsive and had relative standard deviations below 25 percent for flow rates on a single frit. However, standard deviations of flow rates between frits were higher. This was likely due to a combination of factors, such as the frits’ pore size range of 10 μm resulting in the possibility of varied degrees of functionalization of each frit.

Nanofabrication techniques produce materials with enhanced physicochemical properties through a combination of nanoscale roughness and the use of chemically diverse polymers which enable advanced applications in separation science (air/water purification), tissue engineering, and biosensing. Since the late 1990’s, electrospinning has been extensively studied and utilized to produce nano- to microfiber meshes with 3D porosity on the gram scale. By combining a high surface area to volume ratio and tunable surface chemistry, electrospinning is a facile platform for generating non-woven polymeric fibers for many biomedical and industrial applications. This thesis describes three applications of electrospun nano- and microfiber meshes spun from both commercially available and novel polymer systems for: 1) oil and water separation after an accidental oil spill; 2) ultraviolet light controlled protein and cell patterning throughout 3-dimensional nanofiber meshes; and 3) novel diagnostic platform by combining electrospun nanofiber meshes with solid state nanopores for enhanced single molecule nucleic acid and protein detection. Each application embodies the philosophy that electrospun materials have the potential to solve a wide variety of problems by simply tuning the physicochemical properties and mesh morphologies towards the design requirements for a specific problem. For example, to solve the problem of recovering crude oil after an oil spill while generating a minimal waste burden, a hydrophobic and biodegradable microfiber mesh was designed to repeatedly separate oil and water and naturally biodegrade after use. In order to solve the problem of spatiotemporal placement of cells within a 3-dimensional tissue engineering construct, an ultraviolet light activated mesh was designed to transition from hydrophobic (water impermeable) to hydrophilic (water permeable) upon exposure to ultraviolet light facilitating protein and cell patterning. Finally to address two problems with single molecule solid state nanopore biosensors, namely rapid nucleic acid translocation rates and limited protein identification capabilities, a new biosensor platform was developed based on two novel polymeric systems which were synthesized and electrospun into high surface area nanofiber mesh coatings. / 2018-02-17T00:00:00Z

LCST-type synthetic thermoresponsive polymers can reversibly respond to certain stimuli in aqueous media with a massive change of their physical state. When fluorophores, that are sensitive to such changes, are incorporated into the polymeric structure, the response can be translated into a fluorescence signal. Based on this idea, this thesis presents sensing schemes which transduce the stimuli-induced variations in the solubility of polymer chains with covalently-bound fluorophores into a well-detectable fluorescence output. Benefiting from the principles of different photophysical phenomena, i.e. of fluorescence resonance energy transfer and solvatochromism, such fluorescent copolymers enabled monitoring of stimuli such as the solution temperature and ionic strength, but also of association/disassociation mechanisms with other macromolecules or of biochemical binding events through remarkable changes in their fluorescence properties. For instance, an aqueous ratiometric dual sensor for temperature and salts was developed, relying on the delicate supramolecular assembly of a thermoresponsive copolymer with a thiophene-based conjugated polyelectrolyte. Alternatively, by taking advantage of the sensitivity of solvatochromic fluorophores, an increase in solution temperature or the presence of analytes was signaled as an enhancement of the fluorescence intensity. A simultaneous use of the sensitivity of chains towards the temperature and a specific antibody allowed monitoring of more complex phenomena such as competitive binding of analytes. The use of different thermoresponsive polymers, namely poly(N-isopropylacrylamide) and poly(meth)acrylates bearing oligo(ethylene glycol) side chains, revealed that the responsive polymers differed widely in their ability to perform a particular sensing function. In order to address questions regarding the impact of the chemical structure of the host polymer on the sensing performance, the macromolecular assembly behavior below and above the phase transition temperature was evaluated by a combination of fluorescence and light scattering methods. It was found that although the temperature-triggered changes in the macroscopic absorption characteristics were similar for these polymers, properties such as the degree of hydration or the extent of interchain aggregations differed substantially. Therefore, in addition to the demonstration of strategies for fluorescence-based sensing with thermoresponsive polymers, this work highlights the role of the chemical structure of the two popular thermoresponsive polymers on the fluorescence response. The results are fundamentally important for the rational choice of polymeric materials for a specific sensing strategy. / Als Reaktion auf bestimmte äußere Stimuli ändern bestimmte wasserlösliche Polymere reversibel ihren physikalischen Zustand. Dieser Vorgang kann mithilfe von Fluorophoren, die in die Polymerstrukturen eingebaut werden und deren Fluoreszenzeigenschaften vom Polymer¬zustand abhängen, detektiert werden. Diese Idee ist der Ausgangspunkt der vorliegenden Arbeit, die sich damit beschäftigt, wie äußerlich induzierte Änderungen der Löslichkeit solcher Polymere mit kovalent gebundenen Fluorophoren in Wasser in ein deutlich messbares Fluoreszenzsignal übersetzt werden können. Dazu werden photophysikalische Phänomene wie Fluoreszenz-Resonanz¬energie¬transfer und Solvatochromie ausgenutzt. In Kombination mit einem responsiven Polymergerüst wird es möglich, verschiedene Stimuli wie Lösungs¬temperatur oder Ionenstärke, oder auch Assoziation-Dissoziation Reaktionen mit anderen Makromolekülen oder biochemische Bindungs¬reaktionen über die Änderung von Fluorezenz¬farbe bzw. –Intensität autonom mit bloßem Auge zu detektieren. Unter anderem wurde ein wässriger ratiometrischer Temperatur- und Salzsensor entwickelt, der auf der komplexen supramolekularen Struktur eines thermoresponsiven Copolymers und eines thiophenbasierten konjugierten Polyelektrolyts beruht. Die Anbindung solvato¬chromer Fluorophore erlaubte den empfindlichen Nachweis einer Temperatur¬änderung oder des Vorhandenseins von Analyten. Komplexere Phänomene wie das kompetitive Anbinden von Analyten ließen sich hochempfindlich steuern und auslesen, indem gleichzeitig die Sensitivität dieser Polymeren gegenüber der Temperatur und spezifischen Antikörpern ausgenutzt wurde. Überraschenderweise wiesen die hier untersuchten thermoresponsiven Polymere wie poly-N-isopropylacrylamid (pNIPAm) oder poly-Oligoethylenglykolmethacrylate (pOEGMA) große Unterschiede bzgl. ihrer responsiven optischen Eigenschaften auf. Dies erforderte eine ausführliche Charakterisierung des Fluoreszenz- und Aggregationsverhaltens, unter- und oberhalb des Phasenübergangs, im Bezug auf die chemische Struktur. Ein Ergebnis war, dass alle drei Polymertypen sehr ähnliche temperaturabhängige makroskopische Absorptionseigenschaften aufweisen, während sich die Eigenschaften auf molekularer Ebene, wie der Hydratisierungsgrad oder die intermolekulare Polymerkettenaggregation, bei diesen Polymeren sehr unterschiedlich. Diese Arbeit zeigt damit anhand zweier sehr etablierter thermoresponsiver Polymere, nämlich pNIPAm und pOEGMA, das die chemische Struktur entscheidend für den Einsatz dieser Polymere in fluoreszenzbasierten Sensoren ist. Diese Ergebnisse haben große Bedeutung für die gezielte Entwicklung von Polymermaterialien für fluoreszenzbasierte Assays.

Stimuli-responsive polymers and self-assembling peptides represent two classes of materials with interesting properties and great potential to be used as biomaterials. The conjugation of polymer with peptide offers a way to combine the controlled chemical, mechanical, and thermal properties of polymer with the functionality of designed bioactive group. Pure hybrid materials with the characteristics of individual components or systems containing hybrid materials became attractive for applications in drug delivery and tissue engineering. This work focused on systems where the thermo-responsive properties of a polymer were combined with the gelling properties of two different ionic-complementary peptides via conjugation. The prototypical thermo-responsive polymer poly(N-isopropylacrylamide) (PNIPAAm) was chosen due to its lower critical solution temperature (LCST) ~32°C being close to body temperature. Ionic-complementary oligo-peptides, containing the alternating hydrophobic/hydrophilic and charged/uncharged amino acids, phenylalanine (F), glutamic acid (E) and lysine (K), were selected as they are known to form β-sheet rich fibrillar networks at low concentrations. Two peptide sequences with different charge distribution were chosen: FEFEFKFK and FEFKFEFK which form self-supporting gels at ~17 and 10 mg ml-1 respectively. Polymer-peptide conjugates were used to confer self-assembling and thermo-responsive behaviour to the system.Thermo-responsive PNIPAAm-rich hydrogels were obtained by targeting different degrees of functionalisation of PNIPAAm with the self-assembling peptides. Two series of such systems were prepared by using either a thiol-modified FEFEFKFK or a thiol-modified FEFKFEFK peptide as the chain-transfer agent in the free radical polymerisation of NIPAAm. The resulting polymer/conjugate mixtures were studied by proton nuclear magnetic resonance (1H NMR). The polymer/conjugate ratios were calculated and showed that the conjugate fraction in the mixtures increased with increasing concentration of peptide used for the polymerisation. Static light scattering (SLS) and viscometry showed the aggregation of the polymer/conjugate mixtures presumably due to the presence of peptide. The values from gel permeation chromatography (GPC), which were mostly attributed to the unconjugated polymers, were higher than those obtained from 1H NMR and centrifugation for the conjugates. The polymer/conjugate mixtures formed self-supporting gels where the critical gelation concentration decreased with increasing conjugate content. Oscillatory rheology experiments confirmed gels had formed and revealed that their elastic modulus, G' varied from ~ 10 to 400 Pa depending on the sample. TEM and AFM studies proved the formation of β-sheet fibres of ~ 4.5 ± 1.5 nm in diameter. The PNIPAAm-rich hydrogels were also characterised by micro DSC to reveal their thermo-responsiveness and phase separation and showed the LCST at ~ 30°C. The results of the study showed that varying the peptide sequence did not have an effect on thermal, mechanical or morphological properties of the hydrogels. By exploiting the self-assembly of the ionic-complementary peptides, it was possible to create PNIPAAm-rich, thermo-responsive hydrogels with controllable properties.Further in the study pure PNIPAAm-FEFEFKFK conjugate was incorporated into the FEFEFKFK peptide matrix to create peptide-rich thermo-responsive composite gels. Two series of the composite gels were prepared by varying separately the peptide matrix and polymer-peptide conjugate concentration. Micro DSC measurements revealed an endothermic peak at ~ 30ºC characteristic of the LCST of PNIPAAm. Oscillatory rheology studies showed that the composite gels became stronger with increasing conjugate concentration (G' ~ 20 - 200 Pa). Network morphology was studied by SANS. Using contrast variation and contrast matching techniques it was possible to distinguish between the peptide fibres and the PNIPAAm chains. Below and above the LCST the scattering curves showed a q-1 behaviour which is typical of rod-like objects. TEM and AFM also proved the formation of fibres of ~4.0 ± 0.8 nm and ~4.5 ± 1 nm respectively. AFM studies showed that the fibres of the composite gels were decorated with polymer chains. The thermo-responsiveness and the gelation properties of these conjugate-based scaffolds have potential for use as drug delivery vehicles or tissue engineering scaffolds.

This thesis focuses on electron irradiated gelatin hydrogel composites for the development of a magnetically-controllable material. Smart materials comprised of magnetic nanoparticles embedded in hydrogels are known as ferrogels. Deformation, swelling and viscoelasticity of ferrogels can be controlled by external magnetic fields, with potential applications in drug delivery, tissue engineering, actuation and sensing. High energy electron irradiation was used to create stable gelatin hydrogels. Geometry, swelling, solubility and viscoelasticity were experimentally quantified for the irradiated gelatin. The degree of crosslinking and mesh size were calculated by theories of rubber elasticity and Flory-Rehner. Fourier transform infrared spectroscopy was used to confirm minimal chemical changes occurred as a result of crosslinking. The micro- and nanostructure of the hydrogels were investigated using small-angle X-ray scattering to supplement macroscopic investigations, allowing for comparison of experimental data with additional semiflexible polymer models. The cytotoxicity of the irradiated hydrogels and liquid byproduct were analyzed using NIH 3T3 mouse embryonic fibroblasts and human umbilical vein endothelial cells. The influence of the degree of crosslinking on cellular morphologies was also explored. Additionally, surface wettability and hydrogel degradation times were quantified with respect to the irradiation dose. Preliminary experiments examined the potential of irradiated gelatin hydrogels as components of vascular scaffolds. Potential surface modification strategies to enhance and direct cellular interactions were briefly explored, such as surface coating and patterning. After integration of magnetic nanoparticles into the gelatin, the magnetic response of the ferrogels was investigated using magnetic particle spectroscopy and magnetorelaxometry. These techniques were highly sensitive to the changing matrix viscoelasticity around the sol-gel transition. Irradiated ferrogels exhibited thermal stability across the sol-gel transition, although some local softening was observed. This research highlights the potential of electron irradiated gelatin hydrogels and ferrogels, while providing fundamental insights into the physical processes influencing the network structure, mechanics and resulting cellular interactions.

Yes / Amphiphilic diblock copolymers, poly(2-(diethylamino)ethyl methacrylate-co-2-(dimethylamino)ethyl methacrylate)-b-poly(2-(dimethylamino)ethyl methacrylate), P(DEAEMA-co-DMAEMA)-b-PDMAEMA with various amounts of DEAEMA have been synthesized by RAFT polymerization. Their micellization in water has been investigated by scattering measurements over a wide pH range. It appeared that the polymers self-assembled into pH sensitive star like micelles. For a given composition, when the pH is varied the extent of aggregation can be tuned reversibly by orders of magnitude. By varying the copolymer composition in the hydrophobic block, the onset and extent of aggregation were shifted with respect to pH. This class of diblock copolymer offers the possibility to select the range of stimuli-responsiveness that is useful for a given application, which can rarely be achieved with conventional diblock copolymers consisting of homopolymeric blocks. / European Science Foundation (ESF), Engineering and Physical Sciences Research Council (EPSRC), BP (Firm), Birmingham Science City, Advantage West Midlands (AWM), European Regional Development Fund (ERDF)

Yes / AB and ABA di- and triblock copolymers where A is the hydrophilic poly(oligoethylene glycol methacrylate) (POEGMA) block and B is a thermo-responsive sulfobetaine block [2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide (PDMAPS) were synthesised by aqueous RAFT polymerisation with narrow dispersity (ĐM ≤ 1.22), as judged by aqueous SEC analysis. The di- and triblock copolymers self-assembled in salt-free water to form micelles with a PDMAPS core and the self-assembly of these polymers was explored by SLS and TEM analysis. The micelles were shown, by DLS analysis, to undergo a micelle-to-unimer transition at a critical temperature, which was dependent upon the length of the POEGMA block. Increasing the length of the third, POEGMA, block decreased the temperature at which the micelle-to-unimer transition occurred as a result of the increased hydrophilicity of the polymer. The dissociation of the micelles was further studied by SLS and synchrotron SAXS. SAXS analysis revealed that the micelle dissociation began at temperatures below that indicated by DLS analysis and that both micelles and unimers coexist. This highlights the importance of using multiple complementary techniques in the analysis of self-assembled structures. In addition the micelle-to-unimer morphology transition was employed to encapsulate and release a hydrophobic dye, Nile Red, as shown by fluorescence spectroscopy. / Engineering and Physical Sciences Research Council (EPSRC), University of Warwick

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.