Nanoparticle-based technologies are an emerging field with the promise to impact a wide range of application areas. However, that potential is somewhat married to a host of research questions that remain to be answered. This work explores the surface modification of magnetic nanoparticles in a controlled fashion to produce hybrid nanoparticle (metal/polymer) systems with different morphologies, understand in-situ behavior of stimuli-responsive polymers grafted to a substrate, and obtain better computational methods for particle-tracking and -deposition. Nanoparticle surface modification was performed using ATRP, obtaining homo-, block-co-, and ‘twoaced/biphasic’ polymer structures on the nanoparticle surfaces. Biphasic Janus nanoparticles (JPs) were formed using a magnetic nanoparticle core and an innovative technique combining non-covalent solid protection with sequential controlled radical polymerization to form the two surface-grafted polymer phases. Surface-confined polymerizations were conducted using pH- and thermo-responsive materials. Poly(methacrylic acid) (PMAA) and a series of (aminoalkyl) methacrylate polymers were used as pH responsive polymers. Additionally, poly(N-isopropylacrylamide) (PNIPAM) was selected as the thermo-responsive material for this study. In-situ characterization techniques, including atomic force microscopy (AFM), dynamic light scattering (DLS), and ellipsometry, were used to evaluate the thermo- and pH-responsiveness of these stimuli responsive materials. A new general-oscillator (GENOSC) model was used to determine swelling ratio, thickness, and optical constant changes in the polymer brush as pH was changed in-situ. AFM was used to study morphological changes due to changes in pH and temperature. Nanoparticle temperature responsiveness was investigated using DLS. A related effort involved the use of computational fluid dynamic (CFD) methods to track (micron-sized) particles in certain geometries, including a human lung morphology. Predicted particle transport and deposition was compared to Lagrangian computational approaches and available experimental data. The Eulerian particle phase modeling method developed resulted in the accurate prediction of both near-wall particle tracking and wall deposition. This Eulerian-Eulerian model is a new tool that has potential for particle tracking in physiological morphologies. This combination of experimental and computational research has led to new nano- and micro-particle surface modification methods and particle transport modeling.

Several analytical mean field models are presented for the class of stimuli responsive polymers that are driven by the lower critical solution temperature (LCST) transition. For solutions above the polymer crossover concentration, a hybrid model combines lattice-fluid excluded volume and van-der-Waals interactions with a combinatorial approach for the statistics of hydrogen bonding, hydration, and ionic bonding. This approach yields models for the LCST of both neutral polymers and lightly charged polyelectrolytes in aqueous salt solution. The results are shown to be in semi-quantitative agreement with experimental data for the cloud point of polyethylene oxide (PEO) in aqueous solution with various salts, and some aspects of the lyotropic series are reproduced. Results for lightly charged polyelectrolytes are compared to and shown to be in qualitative agreement with aspects of experimentally observed behavior. Finally, a framework is established for extension of these models to further aspects of the lyotropic series and polyelectrolyte behavior. At the nanoscale, lattice fluid (LF) and scaled particle theory (SPT) approaches are employed to model the LCST-related coil-globule-transition (CGT) of isolated polymer chains in highly dilute solution. The predicted CGT behavior semi-quantitatively correlates with experimental results for several polymer-solvent systems and over a range of pressures. Both the LF and SPT models exhibit a heating induced coil-to-globule transition (HCGT) temperature that increases with pressure until it merges with a cooling induced coil-to-globule transition (CCGT). The point at which the CCGT and HCGT meet is a hypercritical point that also corresponds to a merging of the lower critical and upper critical solution temperatures. Theoretical results are discussed in terms of a generalized polymer/solvent phase diagram that possesses three hypercritical points. Within the lattice model, a dimensionless transition temperature [author gives mathematical symbol] is given for a long chain simply by the equation [author gives mathematical equation], where [part of the equation] is the bulk solvent occupied volume fraction at the transition temperature. Furthermore, there is a critical value of the ratio of polymer to solvent S-L characteristic temperature below which no HCGT transition is predicted for an infinite chain. / text

Das corneale Endothel bildet die innere, einschichtige Zelllage der Cornea und ist für die Aufrechterhaltung der cornealen Transparenz zuständig. Krankheiten oder Verletzungen des cornealen Endothels können zu schweren Beeinträchtigungen des Sehvermögens führen und eine corneale Transplantation erforderlich machen. Der während und nach der Operation auftretende endotheliale Zellverlust erschwert das Überleben des Transplantates. Darum besteht ein Hauptziel des cornealen Tissue Engineerings in der Bereitstellung von transplantierbaren humanen cornealen Endothelzellsheets (HCEC-Sheets) mit einer adäquaten Zelldichte. Thermo-responsive Zellkulturträger fanden für die schonende, enzymfreie Gewinnung von Zellsheets für verschiedene Gewebetypen bereits Verwendung. HCEC stellen in diesem Kontext einen besonderen Fall dar, da sie eine starke Adhäsion zu ihrem Kultursubstrat ausbilden, was deren schonende, thermisch induzierte Ablösung als funktionelles Zellsheet erschwert. Im Rahmen dieser Arbeit wurde ein neuartiger thermo-responsiver Zellkulturträger entwickelt. Dieser basiert auf dem durch Elektronenbestrahlung immobilisierten und vernetzten thermo-responsiven Polymer Poly(vinylmethylether) (PVME) sowie dem alternierenden Co-Polymer Poly(vinylmethylehter-alt-maleinsäureanhydrid) (PVMEMA) als biofunktionalisierbare Komponente. Die Kombination dieser Polymere führte zur Etablierung eines thermo-responsiven Zellkulturträgers, dessen physikochemische und biomolekulare Eigenschaften in weiten Grenzen einstellbar und dadurch an die spezifischen Anforderungen von HCEC anpassbar waren. Das PVME-PVMEMA-Blend ermöglichte die Bildung konfluenter HCEC-Monolayer mit den morphologischen Grundlagen für ein funktionelles corneales Endothelgewebe. Durch Inkorporation von Poly(N-isopropylacrylamid) (PNiPAAm) als weitere thermo-responsive Polymerkomponente konnte das Ablösungsverhalten funktioneller HCEC-Sheets weiter verbessert werden. In einem weiteren Schritt erfolgte der Transfer abgelöster HCEC-Sheets auf ein planares, biofunktionalisiertes Kultursubstrat sowie auf endothelfreie porcine Corneae. Die HCEC-Sheets wurden auch nach dem Transfer umfassend biologisch analysiert. Diese Arbeit legt einen Grundstein für die Bereitstellung klinisch anwendbarer Alternativen für das Tissue Engineering von cornealem Gewebe.

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Comme je suis particulièrement intéressé par les nanosciences et les nombreuses applications des nanotechnologies, je me suis penché sur le développement de méthodes de fabrication de nanoparticules ultra-petites dont les fonctions peuvent être ajustées avec précision. Récemment, une nouvelle technologie appelée « technologie d’une seule chaîne », c’est-à-dire qui utilise une seule chaîne polymère, est devenue un sujet de recherche de plus en plus motivant pour la communauté scientifique. Cette technologie a l’avantage de dépendre d’une méthode facile de préparation de nanoparticules polymères d’une seule chaîne (SCNPs) et ayant des dimensions typiques de 1,5 à 20 nm. Leurs tailles ultra petites leur confèrent des propriétés spécifiques, ce qui permet de les utiliser comme capteurs, systèmes catalytiques, revêtements à faible viscosité, nanoréacteurs ou pour des applications biomédicales. Grâce aux contributions de nombreux scientifiques durant la dernière décennie, les méthodes de synthèse des SCNPs sont devenues très variées et représentent une technologie désormais mature. Néanmoins, de nombreux problèmes sont à résoudre dans ce domaine, ce qui permettra d’ajouter de nouvelles fonctions ou de les valoriser pour de nouvelles applications. Les polymères sensibles à plusieurs stimuli sont une classe de matériaux intelligents dont les propriétés peuvent être modifiées par l’application d’un stimulus extérieur. Ils sont utilisés extensivement dans les domaines énergétique et biomédical. Comme leurs propriétés physiques et chimiques peuvent être modifiées aisément et efficacement par un contrôle de leur environnement externe, ces polymères sont des candidats pour fabriquer de nouvelles SCNPs. Dans cette thèse, nous nous sommes intéressés au développement de SCNPs ayant de multiples fonctionnalités car cela permet d’ouvrir la voie pour de nouvelles applications. Pour cela, de nombreux polymères sensibles à plusieurs stimuli ont été préparés comme précurseurs à des SCNPs. En concevant spécifiquement ces polymères, il fut possible d’ajouter leurs propriétés de réponse à des stimuli dans les systèmes SCNPs. Le cœur même de cette thèse consiste en trois projets qui utilisèrent trois classes de SCNPs provenant de polymères sensibles aux stimuli. Grâce à leur réponse à plusieurs stimuli, ces SCNPs remplirent de nombreuses fonctions et subirent des modifications soit de leur structure, soit de leur morphologie, soit de leurs propriétés. Et en plus de la variété de fonctions, chaque classe de SCNPs a le potentiel pour de nombreuses applications. Dans la première étude présentée dans cette thèse (chapitre 1), nous avons préparé une classe de SCNPs photodégradables ayant une taille ajustable et inférieure à 10 nm. Il s’agit de polyesters rendus photosensibles par la présence de coumarines à l’intérieur de la chaîne principale (nommés CAPPG) grâce à la copolymérisation de coumarine diol, d’acide adipique et de propylène glycol (PPG). Cette incorporation de coumarines dans la chaîne principale permet au polymère d’être photosensible par deux façons. En effet, les coumarines peuvent se photo-dimériser, lorsqu’elles sont irradiées par des rayonnements UV (> 320 nm) en des cyclobutanes qui peuvent être ouverts à nouveau par d’autres rayonnements UV (254 nm) permettant la restauration des coumarines initiales. Cela a permis la création de SCNPs de tailles inférieures à 10 nm et incluant des propriétés de photodégradation. Cette propriété a été démontrée par une irradiation de 3 h avec des chaînes polymères de 13220 g/mol à 1385 g/mol dans les SCNPs. La taille de ces SNCPs (caractérisée par leur rayon hydrodynamique) peut être modifiée entre 3 nm et 5,3 nm en modifiant le taux de dimérisation des coumarines, ce qui est aisément obtenu en ajustant le temps d’irradiation UV. Les résultats ont démontré que cette méthode permet un contrôle aisé de la taille des SCNPs sans avoir recours à la synthèse de nombreux polymères précurseurs. Finalement, comme le polyester était biodégradable et biocompatible, ces SCNPs peuvent être exploitées pour des applications biomédicales. Dans la deuxième étude effectuée au cours de cette thèse (chapitre 2), nous avons préparé un nouveau type de SCNPs multifonctionnel à partir d’un polymère cristallin liquide. Il s’agit du polyméthacrylate de [2- (7-méthylcoumaryl) oxyéthyle - co - 6-[4-(4’-méthoxyphenylazo) phénoxy] hexyle] (PAzoMACMA). Les groupements latéraux du polymère contiennent, en majorité, des azobenzènes photoisomérisables et, en minorité, des coumarines photodimérisables. Les azobenzènes servent de mésogènes pour la formation de cristaux liquides alors que les coumarines ont été utilisées pour une réticulation photoinduite et intrachaîne. Malgré les dimensions inférieures à 15 nm, le confinement et la réticulation, les phases cristallines liquides (LC) persistèrent même dans les SCNPs. Ces SCNPs cristaux liquides (LC-SCNPs) présentèrent un certain nombre de propriétés intéressantes et particulières. Alors que leurs dispersions dans le THF n’étaient pas fluorescentes, celles dans le chloroforme l’étaient. En plus, ces nanoparticules s’aggloméraient quelque peu dans le chloroforme ce qui induisait des fluorescences différentes entre des SCNPs riches en isomères cis ou riches en isomères trans des azobenzènes. A cause de la photoisomérisation des azobenzènes, ces LC-SCNPs se déformaient sous irradiation comme le font les microparticules ou les colloïdes contenant des azobenzènes. Cependant, la déformation de ces nanoparticules dépend de la longueur d’onde de lumière polarisée. Alors que sous irradiation UV polarisée à 365 nm, l’élongation des SCNPs était perpendiculaire à la polarisation de la lumière incidente, sous irradiation visible polarisée entre 400 et 500 nm, l’étirement se faisait parallèlement à la polarisation. Finalement, un nanocomposite fut préparé par dispersion de LC-SCNPs dans une matrice de polyméthacrylate de méthyle (PMMA). Si celui-ci était étiré mécaniquement, les azobenzènes s’orientaient dans la direction de la déformation induite. Ces propriétés intéressantes des LC-SCNPs que cette étude a permis de dévoiler, suggèrent de nouvelles applications potentielles. Dans la troisième étude de cette thèse (chapitre 3), nous avons préparé une classe de SCNPs sensibles à la présence de CO2 et leurs agrégats micellaires auto-assemblés. D’un côté, des SCNPs ont été préparées à partir d’un polyméthacrylate de {(N, N-diméthylaminoéthyle)-co-4-méthyl-[7-(méthacryloyl)-oxyéthyl-oxy] coumaryle} (PDMAEMA-co-CMA). Lorsqu’elles sont dispersées en solution aqueuse, les nanoparticules individuelles peuvent subir des cycles réversibles d’expansion et de rétrécissement sous une stimulation alternative de CO2 et de N2 qui vont protoner et déprotoner les amines tertiaires. D’un autre côté, des SCNPs de type ‘Janus’ (SCJNPs) ont été préparées à partir d’un copolymère dibloc amphiphile : PS-b-P(DMAEMA-co-CMA) (PS correspond au polystyrène qui est hydrophobe). Ce type de SCJNPs peut s’autoassembler sous forme de micelles en solution aqueuse. Sous stimulation CO2 ou N2, l’expansion ou le rétrécissement à l’intérieur des particules permet de grands changements de volume. En plus, ces particules ont été étudiées comme potentiels nanoréacteurs pour des nanoparticules d’or (AuNPs) que ce soit sous formes SCNPs ou micelles SCJNPs. La vitesse de formation des AuNPs augmente sous bullage de CO2 et décroît sous N2. Cela permet de rendre possible cette réaction contrôlable par ces deux gaz. Qui plus est, utiliser des micelles de SCJNPs dont le volume peut être modifié sur un large intervalle en changeant l’intensité de la stimulation de CO2, permit d’obtenir des AuNPs de taille variable. / Abstract : With interests on nanoscience and nanotechnology for many applications, there is a demand for development of fabrication technology of ultra-small nano-size objects that allow for precise size control and tailored functionality. Recently, a new technology called ‘single-chain technology’, which manipulates a single polymer chain, becomes a rapidly-growing research topic. This technology provides a facile method to prepare polymer single-chain nanoparticles (SCNPs) with a typical size of 1.5-20 nm. Due to the ultra-small size-enabled unique properties, SCNPs have wide range of applications, including sensor, catalytic system, low viscosity coating, nanoreactor and biomedical applications. Through the contributions by many scientists in the past decade, the synthetic methodologies to fabricate SCNPs have been reported using various chemistries and been getting mature. However, there are still several unsolved problems in the field of SCNPs including functions and application. Stimuli-responsive polymers, as a class of smart materials whose properties can be changed by responding to external stimuli, have been widely used in energy and biomedical applications. Since their chemical and physical properties can be changed easily and efficiently via environmental control, stimuli-responsive polymers provide a potential pathway to preparing functional SCNPs. In this thesis, we are focusing on developing functional SCNPs, especially systems with multi-functions, and expanding their applications. To achieve this target, various stimuli-responsive polymers were prepared as polymer precursors and their stimuli-responsive properties were introduced into the SCNP systems by rational design of their chemical structures. The core of this thesis is comprised of three projects which deal with three classes of SCNPs from stimuli-responsive polymers. These stimuli-responsive SCNPs perform multi-functions and undergo certain change either in structure or morphology and properties. In addition, according to their variety of functions, each class of multi-functional SCNPs has diverse potential applications. In the first study presented in the thesis (Chapter 1), we prepared a class of sub-10 nm photodegradable and size-tunable SCNPs based on photo-responsive main-chain coumarin-based polyesters Poly{[7-(hydroxypropoxy)-4-(hydroxymethyl)coumarin adipate]-co- (polypropylene glycol adipate)} (CAPPG) through copolymerization of coumarin diol, adipic acid and polypropylene glycol (PPG). By incorporating coumarin moieties into the chain backbone of a polyester, dual photo-responsive reaction, i.e. photo-dimerization (>320 nm) and photo-induced chain scission (254 nm), occur under two different wavelengths of UV irradiation, enabling the preparation of sub-10 nm SCNPs and their photo-degradation property. The photo-degradability of SCNPs is evidenced under 254 nm UV irradiation for 3 h, which molecular weight of SCNPs decreasing from 13220 g/mol to 1385 g/mol. Moreover, the size of SCNPs can be tunable from 5.3 nm to 3 nm (hydrodynamic diameter) by varying the dimerization degree of coumarin moieties, that is simply controlled by the UV irradiation time. These results demonstrate a facile method to control the size of SCNPs without the need for synthesizing different polymer precursors. Finally, due to the biocompatible and biodegradable nature of polyester as polymer precursor, the SCNPs with photo-degradability and size-tunability have the potential to be exploited for biomedical applications. In the second study realized in this thesis (Chapter 2), we prepared a new type of multi-functional SCNPs from a side-chain liquid crystalline polymer (SCLCP), namely poly{6-[4-(4-methoxyphenylazo) phenoxy]hexylmethacrylate-co-4-methyl-[7-(methacr-yloyl) oxy-ethyl-oxy]coumarin} (PAzoMACMA). The polymer’s side groups comprise photo-isomerizable azobenzene in majority and photo-dimerizable coumarin in minority, with the former as mesogens and the latter for intra-chain photo-crosslinking. Despite the sub-15 nm size, confinement and crosslinking, the liquid crystalline (LC) phases of bulk PAzoMACMA persist in SCLCPs. Such LC-SCNPs exhibit a number of interesting and peculiar properties. While their dispersion in THF is non-fluorescent, when dispersed in chloroform, the nanoparticles appear to agglomerate to certain degree and display significant fluorescence that is different for SCNPs rich in the trans or cis isomer of azobenzene. The azobenzene LC-SCNPs also undergo photo-induced deformation, similar to azobenzene micro- or colloidal particles. However, the elongational deformation of the nanoparticles is dependent upon the linearly polarized excitation wavelength. While under polarized 365 nm UV irradiation the SCNP stretching direction is perpendicular to the light polarization, under polarized 400-500 nm visible light irradiation, the stretching takes place along the light polarization direction. Finally, an all-polymer nanocomposite was prepared by dispersing the LC-SCNPs in poly(methyl methacrylate) (PMMA), and mechanically stretching-induced orientation of azobenzene mesogens developed along the strain direction. The interesting properties of LC-SCNPs unveiled in this study suggest new possibilities for applications including bio-imaging and LC materials. As the third study in this thesis (Chapter 3), we studied a class of CO2-responsive SCNPs and their self-assembled micellar aggregates. On one hand, SCNPs are prepared from a random copolymer of poly{(N,N-dimethylaminoethyl methacrylate)-co-4-methyl-[7-(methacryloyl)oxyethyl-oxy]coumarin} (P(DMAEMA-co-CMA)). When dispersed in aqueous solution, individual nanoparticles can undergo reversible swelling/shrinking under alternating CO2/N2 stimulation as a result of the reversible protonation/deprotonation of tertiary amine groups. On the other hand, tadpole-like single-chain ‘Janus’ nanoparticles (SCJNPs) are prepared using an amphiphilic diblock copolymer of PS-b-P(DMAEMA-co-CMA) (PS is hydrophobic polystyrene). This type of SCJNPs can self-assemble into core-shell micellar aggregates in aqueous solution. Under CO2/N2 stimulation, the collective swelling/shrinking of SCJNPs within the micelle results in large, reversible volume change. In addition, both P(DMAEMA-co-CMA) SCNPs and PS-b-P(DMAEMA-co-CMA) SCJNP micelles are explored as gas-tunable nanoreactors for gold nanoparticles (AuNPs). The rate of AuNP formation increases under CO2 stimulation and decreases upon N2 bubbling, which makes it possible to tune the reaction rate up and down (on/off switching) by using the two gases. Moreover, using the micelles of SCJNPs, whose volume can be controlled over a wide range by adjusting the CO2 stimulation strength, variable-size AuNPs and their aggregates are obtained with continuous redshift of the surface plasmon resonance (SPR) into the long wavelength visible light region.

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Step-growth polymerization provided an effective method for the preparation of several high performance polymers. Step-growth polymerization was used for syntheses of poly(siloxane imides), polyesters, poly(triazole esters), poly(triazole ether esters), and epoxy networks. Each of these polymeric systems exhibited novel structures, and either photoreactive capabilities, or high performance properties. There is an increasing trend towards the development of photoactive adhesives. In particular these polymers are often used in flip bonding, lithography, stimuli responsive polymers, drug delivery, and reversible adhesives. The ability to tailor polymer properties carefully with exposure to light allows for very unique stimuli responsive properties for many applications. This dissertation primarily investigates photoreactive polymers for reversible adhesion for use in the fabrication of microelectronic devices. In particular cyclobutane diimide functionality within polyimides and poly(siloxane imides) and o-nitro benzyl ester functionality within polyesters acted effectively as chromophores to this end. Thermal solution imidization allowed for the effective synthesis of polyimides and poly(siloxane imides). 1,2,3,4-Cyclobutane tetracarboxylic dianhydride acted as the chromophore within the polymer backbone. The polyimides obtained exhibited dispersibility only in dipolar, aprotic, high boiling solvents such as DMAc or NMP. The obtained poly(siloxane imides) demonstrated enhanced dispersibility in lower boiling organic solvents such as THF and CHCl₃. Dynamic mechanical analysis and tensile testing effectively measure the mechanical properties of the photoactive poly(siloxane imides) and confirmed elastomeric properties. Atomic force microscopy confirmed microphase separation of the photoactive poly(siloxane imides). ¹H NMR spectroscopy confirmed formation of maleimide peaks upon exposure to narrow band UV light with a wavelength of 254 nm. This suggested photo-cleavage of the cyclobutane diimide units within the polymer backbone. Melt transesterification offered a facile method for the synthesis of o-nitro benzyl ester-containing polyesters. ¹H NMR spectroscopy confirmed the structures of the photoactive polyesters and size exclusion chromatography confirmed reasonable molecular weights and polydispersities of the obtained samples. ¹H NMR spectroscopy also demonstrated a decrease in the integration of the resonance corresponding to the o-nitro benzyl ester functionality relative to the photo-stable m-nitro benzyl ester functionality upon exposure to high-intensity UV light, suggesting photo-degradation of the adhesive. ASTM wedge testing verified a decrease in fracture energy of the adhesive upon UV exposure, comparable to the decrease in fracture energy of a commercial hot-melt adhesive upon an increase in temperature. Click chemistry was used to synthesize polyesters and segmented block copolyesters. Triazole-containing homopolyesters exhibited a marked increase (~40 °C) in Tg, relative to structurally analogous classical polyesters synthesized in the melt. However, the triazole-containing homopolyesters exhibited insignificant dispersibility in many organic solvents and melt-pressed films exhibited poor flexibility. Incorporation of azide-functionalized poly(propylene glycol) difunctional oligomers in the synthesis of triazole-containing polyesters resulted in segmented block copolyesters which exhibited enhanced dispersibility and film robustness relative to the triazole-containing homopolyesters. The segmented triazole-containing polyesters all demonstrated a soft segment Tg near -62 °C, indicating microphase separation. Dynamic mechanical analysis confirmed the presence of a rubbery plateau, with increasing plateau moduli as a function of hard segment content, as well as increasing flow temperatures as a function of hard segment content. Tensile testing revealed increasing tensile strength as a function of hard segment, approaching 10 MPa for the 50 wt % HS sample. Atomic force microscopy confirmed the presence of microphase separated domains, as well as semicrystalline domains. These results indicated the effectiveness of click chemistry towards the synthesis of polyesters and segmented block copolyesters. Click chemistry was also used for the synthesis of photoactive polyesters and segmented block polyesters. The preparation of 2-nitro-p-xylylene glycol bispropiolate allowed for the synthesis of triazole-containing polyesters, which exhibited poor dispersibility and flexibility of melt-pressed films. The synthesis of segmented photoactive polyesters afforded photoactive polyesters with improved dispersibility and film robustness. ¹H NMR spectroscopy confirmed the photodegradation of the o-nitro benzyl functional groups within the triazole-containing polyesters, which indicated the potential utility of these polyesters for reversible adhesion. Synthesis of the glycidyl ether of 2,2,4,4-tetramethyl-1,3-cyclobutane diol (CBDOGE) allowed for the subsequent preparation of epoxy networks which did not contain bisphenol-A or bisphenol-A derivatives. Preparation of analogous epoxy networks from the glycidyl ether of bisphenol-A (BPA-GE) provided a method for control experiments. Tensile testing demonstrated that, dependent on network Tg, the epoxy networks prepared from CBDOGE exhibited similar Young's moduli and tensile strain at break as epoxy networks prepared from BPAGE. Dynamic mechanical analysis demonstrated similar glassy moduli for the epoxy networks, regardless of the glycidyl ether utilized. Tg and rubbery plateau moduli varied as a function of diamine molecular weight. Melt rheology demonstrated a gel time of 150 minutes for the preparation of epoxy networks from CBDO-GE and 78 minutes for the preparation of epoxy networks from BPA-GE, with the difference attributed to increased sterics surrounding CBDO-GE. These results indicated the suitability of CBDO-GE as a replacement for BPA-GE in many applications. / Ph. D.

Cette thèse décrit le développement de nouvelles méthodes pour obtenir des nanoparticules fonctionnelles polyvalentes qui peuvent potentiellement être utilisées pour des applications biomédicales telles que la vectorisation de médicaments, des essais biologiques et la bio-imagerie. Les nanomatériaux sont des outils polyvalents qui ont trouvé des applications comme vecteurs de médicaments, la bio-imagerie ou les biocapteurs. En particulier, les nanoparticules de type core-shell ont attiré beaucoup d'attention en raison de leur petite taille, une relation surface/volume élevée, et une biocompatibilité. Dans ce contexte, nous proposons dans la première partie de la thèse (Chapitre 2), une nouvelle méthode pour obtenir des nanoparticules core-shell via la polymérisation radicalaire en émulsion et vivante combinées. Des particules cœurs de polystyrène de 30 à 40 nm, avec une distribution de taille étroite et portant à la surface des groupements iniferter ont été utilisés pour amorcer la polymérisation supplémentaire d'une couche de polymère. Des nanoparticules core-shell ont été préparées de cette façon. Différents types d’enveloppes : anionique, zwitterioniques, à empreintes moléculaires, thermosensibles, ont ainsi été greffées. Notre méthode est une plate-forme polyvalente permettant d'ajouter des fonctionnalités multiples soit dans le noyau et/ou l'enveloppe pour les études d'interaction cellulaire et de toxicité, ainsi que des matériaux récepteurs pour l'imagerie cellulaire. Dans la deuxième partie de la thèse (Chapitre 3), nous décrivons un procédé nouveau et polyvalent pour la modification de surface des nanoparticules de conversion ascendante (UCP). Ce sont des nanocristaux fluorescents dopés de lanthanides qui ont récemment attiré beaucoup d'attention. Leur fluorescence est excitée dans le proche infrarouge, ce qui les rend idéales comme marqueurs dans des applications biomédicales telles que les tests biologiques et la bio-imagerie, l'auto-fluorescence étant réduite par rapport à des colorants organiques et les quantum dots. Cependant, les UCP sont hydrophobes et non-compatible avec les milieux aqueux, donc une modification de leur surface est essentielle. La stratégie que nous proposons utilise l'émission UV ou visible après excitation en proche infrarouge des UCP, comme source de lumière secondaire pour la photopolymérisation localisée de couches minces hydrophiles autour les UCP. Notre méthode offre de grands avantages comme la facilité d'application et la fonctionnalisation de surface rapide pour fixer divers ligands, et fournit une plateforme pour préparer des UCP encapsulée de polymères pour des différentes applications. Des hydrogels stimuli-sensibles sont des matériaux qui changent leurs propriétés physicochimiques en réponse à des stimuli externes tels que la température, le pH ou la lumière. Ces matériaux intelligents jouent un rôle critique dans des applications biomédicales telles que la vectorisation de médicaments ou l'ingénierie tissulaire. La troisième partie de cette thèse (Chapitre 4) propose un nouveau procédé de préparation d'hydrogels photo et pH sensible. Deux composantes, l'un photosensible à base dl'acide 4-[(4-méthacryloyloxy) phénylazo] benzoïque et l'autre cationic contenant des unités 2-(diéthylamino)éthyl méthacrylate, ont été synthétisés. Leur association donne des particules monodispersées de 100 nm photo et pH sensibles. Ces nanoparticules peuvent être potentiellement utilisées pour la vectorisation de médicaments, en particulier de biomolécules telles que protéines ou siARN. En conclusion, nous avons conçu plusieurs nouvelles méthodes efficaces, polyvalentes, génériques et facilement applicables pour obtenir des nanoparticules et nanocomposites de polymères fonctionnels qui peuvent être appliqués dans de différents domaines biomédicaux comme la vectorisation de médicaments, les biocapteurs, les tests biologiques et la bio-imagerie. / This thesis describes the development of novel methods to obtain versatile, functional nanoparticles that can potentially be used for biomedical applications such as drug delivery, bioassays and bioimaging. Nanomaterials are versatile tools that have found applications as drug carriers, bioimaging or biosensing. In particular, core-shell type nanoparticles have attracted much attention due to their small size, high surface to volume ratio and biocompatibility. In this regard, we propose in the first part of the thesis (Chapter 2), a novel method to obtain core-shell nanoparticles via combined radical emulsion and living polymerizations. Polystyrene core seeds of 30-40 nm, with a narrow size distribution and surface-bound iniferter moieties were used to further initiate polymerization of a polymer shell. Core-shell nanoparticles were prepared in this way. Different types of shells : anionic, zwitterionic, thermoresponsive or molecularly imprinted shells, were thus grafted. Our method is a versatile platform with the ability to add multi-functionalities in either the core for optical sensing or/and the shell for cell interaction and toxicity studies, as well as receptor materials for cell imaging. In the second part of the thesis (Chapter 3), we describe a novel and versatile method for surface modification of upconverting nanoparticles (UCPs). UCPs are lanthanide-doped fluorescent nanocrystals that have recently attracted much attention. Their fluorescence is excitated in the near infrared, which makes them ideal as labels in biomedical applications such as bioimaging and bioassays, since the autofluorescence background is minimized compared to organic dyes and quantum dots. However, UCPs are hydrophobic and non-compatible with aqueous media, therefore prior surface modification is essential. The strategy that we propose makes use oft he UV or Vis emission light of near-infrared photoexcited upconverting nanoparticles, as secondary light source for the localized photopolymerization of thin hydrophilic shells around the UCPs. Our method offers great advantages like ease of application and rapid surface functionalization for attaching various ligands and therefore can provide a platform to prepare polymeric-encapsulated UCPs for applications in bioassays, optical imaging and drug delivery. Stimuli responsive hydrogels are materials that can change their physico-chemical properties in response to external stimuli such as temperature, pH or light. These smart materials play critical roles in biomedical applications such as drug delivery or tissue engineering. The third part of the thesis (Chapter 4) proposes a novel method for obtaining photo and pH-responsive supramolecularly crosslinked hydrogels. Two building blocks, one containing photoresponsive 4-[(4-methacryloyloxy)phenylazo] benzoic acid and the other, consisting of cationic 2-(diethylamino)ethyl methacrylate units, were first synthesized. Combining the two building blocks yielded photo and pH responsive monodisperse 100-nm particles. These nanoparticles can be eventually utilized for drug delivery, especially delivery of biomolecules such as siRNAs or proteins. In conclusion, we have designed several new efficient, versatile, generic and easily applicable methods to obtain functionalized polymer nanoparticles and nanocomposites that can be applied in various biomedical domains like drug delivery, biosensing, bioassays and bioimaging.

This thesis addresses the development of materials, technologies and circuits applied for the fabrication of a new class of microelectronic devices that are relying on a three-dimensional shape variation namely shapeable microelectronics. Shapeable microelectronics has a far-reachable future in foreseeable applications that are dealing with arbitrarily shaped geometries, revolutionizing the field of neuronal implants and interfaces, mechanical prosthetics and regenerative medicine in general. Shapeable microelectronics can deterministically interface and stimulate delicate biological tissue mechanically or electrically. Applied in flexible and printable devices shapeable microelectronics can provide novel functionalities with unmatched mechanical and electrical performance. For the purpose of shapeable microelectronics, novel materials based on metallic multilayers, photopatternable organic and metal-organic polymers were synthesized. Achieved polymeric platform, being mechanically adaptable, provides possibility of a gentle automatic attachment and subsequent release of active micro-scale devices. Equipped with integrated electronic the platform provides an interface to the neural tissue, confining neural fibers and, if necessary, guiding the regeneration of the tissue with a minimal impact. The self-assembly capability of the platform enables the high yield manufacture of three-dimensionally shaped devices that are relying on geometry/stress dependent physical effects that are evolving in magnetic materials including magentostriction and shape anisotropy. Developed arrays of giant magnetoimpedance sensors and cuff implants provide a possibility to address physiological processes locally or distantly via magnetic and electric fields that are generated deep inside the organism, providing unique real time health monitoring capabilities. Fabricated on a large scale shapeable magnetosensory systems and nanostructured materials demonstrate outstanding mechanical and electrical performance. The novel, shapeable form of electronics can revolutionize the field of mechanical prosthetics, wearable devices, medical aids and commercial devices by adding novel sensory functionalities, increasing their capabilities, reducing size and power consumption.

This thesis addresses the development of materials, technologies and circuits applied for the fabrication of a new class of microelectronic devices that are relying on a three-dimensional shape variation namely shapeable microelectronics. Shapeable microelectronics has a far-reachable future in foreseeable applications that are dealing with arbitrarily shaped geometries, revolutionizing the field of neuronal implants and interfaces, mechanical prosthetics and regenerative medicine in general. Shapeable microelectronics can deterministically interface and stimulate delicate biological tissue mechanically or electrically. Applied in flexible and printable devices shapeable microelectronics can provide novel functionalities with unmatched mechanical and electrical performance. For the purpose of shapeable microelectronics, novel materials based on metallic multilayers, photopatternable organic and metal-organic polymers were synthesized. Achieved polymeric platform, being mechanically adaptable, provides possibility of a gentle automatic attachment and subsequent release of active micro-scale devices. Equipped with integrated electronic the platform provides an interface to the neural tissue, confining neural fibers and, if necessary, guiding the regeneration of the tissue with a minimal impact. The self-assembly capability of the platform enables the high yield manufacture of three-dimensionally shaped devices that are relying on geometry/stress dependent physical effects that are evolving in magnetic materials including magentostriction and shape anisotropy. Developed arrays of giant magnetoimpedance sensors and cuff implants provide a possibility to address physiological processes locally or distantly via magnetic and electric fields that are generated deep inside the organism, providing unique real time health monitoring capabilities. Fabricated on a large scale shapeable magnetosensory systems and nanostructured materials demonstrate outstanding mechanical and electrical performance. The novel, shapeable form of electronics can revolutionize the field of mechanical prosthetics, wearable devices, medical aids and commercial devices by adding novel sensory functionalities, increasing their capabilities, reducing size and power consumption.