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La vaste gamme de combinaisons possibles de cations et anions, ainsi que les excellentes propriétés intrinsèques des liquides ioniques (LIs) peuvent être considérées comme les principaux facteurs qui ont conduit au développement d’une recherche utilisant des LIs comme additifs des matériaux polymère. Ainsi, l'objectif principal de ce travail est d'explorer le rôle de la nature du cation et/ou du anion du LI sur les propriétés des matériaux basées de poly (méthacrylate de méthyle) (PMMA). Dans une première partie, des LIs de type imidazolium et ammonium ont été incorporés au PMMA et des caractérisations morphologiques et structurales ont été effectuées afin de comprendre leur impact sur les propriétés thermiques, viscoélastiques et mécaniques des matériaux résultants. Dans la section suivante, la capacité de ces LIs à base d'imidazolium et d'ammonium en tant qu’agents interfaciaux à la surface de la silice a été évaluée. Sub-micro et nanoparticules de silice, ainsi que les LIs, ont été incorporées dans une matrice de PMMA afin de préparer des composites. L'amélioration des propriétés des matériaux ont été discutées en fonction du degré auquel chaque LI influence la compatibilité entre les particules et la matrice polymère. De plus, ces composites ont été exposés au dioxyde de carbone en état supercritique (scCO2) pour utiliser celui-ci comme agent moussant et ainsi produire des matériaux expansés. Le rôle du LI et des particules de silice pour structurer les matériaux expansés a été analysé. Dans la dernière partie de cette étude, le scCO2 est utilisé comme milieu de réaction pour la modification chimique par greffage de la surface des nanoparticules de silice par des LIs de type imidazolium, contenant également des groupes hydrolysables et différentes chaînes alkyles. Le rôle de la pression et la quantité de LI ajoutées au milieu de réaction, ainsi que la longueur de la chaîne alkyle des LIs se sont avérées essentielles pour contrôler le degré de fonctionnalisation des nanoparticules. Enfin, ces nanoparticules modifiées ont été incorporées dans une matrice PMMA. Des analyses de morphologie ont été utilisées pour évaluer la dispersion des particules dans la matrice et les propriétés physico-chimiques de ces matériaux ont été également étudiées. / The large array of cation/anion combinations, and the excellent intrinsic properties of ionic liquids (ILs) open a large range of possibilities in their use as additives to polymer materials. Thus, the main objective of this work is to explore the role of both the cation and anion of a series of ILs on the properties of poly(methyl methacrylate) (PMMA)-based materials. In a first approach, low amounts of imidazolium and ammonium-based ILs were incorporated as additives to PMMA in the molten state. Morphological and structural characterizations were developed in order to understand the impact of the presence of such ILs on the thermal and mechanical properties of the resulting materials. Then, in the following section, the ability of the same imidazolium and ammonium-based ILs as physical modifiers of silica surface was evaluated. In such an approach, ILs were supposed to act as interfacial agents. Sub-micron and nanosize silica particles were used to prepare PMMA composites. Thus, the extents of each IL improve the interfacial interaction between PMMA and silica particles were discussed. In addition, supercritical carbon dioxide (scCO2) was used as foaming agent to produce foamed PMMA-based composites. In such a case, the combined effect of the presence of ILs and silica particles was analyzed regarding the morphology of the foamed structures. In the last section, scCO2 was used as reaction medium, in an environmental friendly approach, to chemically modify silica nanoparticles using a series of imidazolium IL-functionalized silanes (with different alkyl chain lengths). Thermogravimetric analysis (TGA) was used to highlight the effect of the working pressure and the content of such ILs in the reaction medium. The effect of the alkyl chain length on the grafting density of the resulting nanoparticles was also discussed. Finally, novel PMMA-based nanocomposites were prepared by the incorporation of such grafted nanoparticles. Transmission electron microscopy (TEM) and small-angle neutron scattering (SANS) analyses were used to evaluate the state of dispersion of the particles into the polymer matrix. Moreover, the thermal, rheological and mechanical properties of the materials were studied.

This dissertation presents the novel creation of a hybrid D-fiber electro-optic polymer electric field sensor. The sensor is made by removing a portion of the cladding from a D-shaped optical fiber, thus exposing the core to interaction with external stimulus. Then, an electro-optic polymer is deposited, partially replacing the core of the fiber. Next, the polymer is poled to endow it with electro-optic properties. This sensor is packaged in order to restore its mechanical strength. Because D-fiber is not intrinsically compatible with standard optical equipment it is fusion spliced to standard polarization maintaining fiber. Finally the sensor is tested for electro-optic sensitivity. The hybrid D-fiber electric field sensors designed and fabricated in this work meet the requirements of mechanical strength, temporal stability, minimal perturbation of the electric field by the sensor, and a small and flexible cross-sectional area so that it can be embedded into the device under test. A fully packaged hybrid electro-optic polymer D-fiber electric field sensor which is capable of detecting electric fields of 50 V/m at a frequency of 6 GHz is produced. The sensor's electro-optic response is shown to be temporally stable. Additionally, the sensor is physically robust, and physically and electrically non-intrusive. This work also adds a thorough understanding of the design and fabrication of D-fiber waveguides with a polymer material deposited in the core. Several new fabrication techniques are developed and presented. A path to greater electric field sensitivity is outlined for future research.

<p> Over the past decade, the development of surface-initiated living polymerization methods has brought a breakthrough to surface modification owing to their control ability. Surface-initiated atom transfer radical polymerization (si-ATRP), as the most popular one, has been widely employed to give novel polymer structures and functionalities to various surfaces for the purposes of tailoring surface properties, introducing new functions, or preparing so-called "smart surfaces", which can respond to external stimuli such as solvent type, pH, temperature, electric and magnetic fields etc. In this thesis, the mechanistic study of the si-ATRP was first carried out through modeling to gain good understanding of si-ATRP. Si-ATRP was then employed to prepare different types of polymer brushes to produce "smart surfaces". </p> <p> The kinetic model was developed using the method of moment. Combined with experimental data, a quantitative analysis was carried out for the si-ATRP mechanism. All information of grafted polymer chains, including active chain concentration, radical concentration, chain length, polydispersity, was illustrated. A new radical termination mechanism, termed as migration-termination, was proposed for si-ATRP. </p> <p> Si-ATRP was then employed to graft poly(oligo(ethylene glycol) methacrylate) (POEGMA) block poly(methyl methacrylate) (PMMA) brushes on silicon wafer surfaces. Simple solvent treatment gave nanoscale patterns via the phase segregation of POEGMA and PMMA segments. Various patterns including spherical aggregates, wormlike aggregates, stripe patterns, perforated layers and complete overlayers, were obtained by adjusting the upper block layer thickness. Furthermore, these nanopatterns had a unique stimuli-responsive property, i.e., switching between different morphologies reversibly after being treated with selective solvents. </p> <p> POEGMA-block-poly(2-(methacryloyloxy)ethyl trimethylammonium chloride) (PMETAC) brushes, having two hydrophilic segments, were synthesized by si-ATRP method. A variety of nanopatterns and their stimuli-responsive ability were observed. The adsorption behaviors of fibrinogen on these patterns were thoroughly studied by ellipsometry, water contact angel measurement, AFM and radio labelling method. </p> <p> A novel thermo-responsive copolymer, poly(2-(2-methoxyethoxy)ethyl methacrylate -co-oligo(ethylene glycol) methacrylate) (P(ME02MA-co-OEGMA)), was also grafted onto silicon wafers. Its thermo-responsive behavior and chain conformation in aqueous solution were studied by neutron reflectometry (NR). Both extended and collapsed brushes exhibited good protein adsorption resistance. </p> / Thesis / Doctor of Philosophy (PhD)

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Cette thèse présente les travaux de développement de formulations injectables capables de se solidifier in situ, formant ainsi un implant piégeant des microparticules magnétiques en vue du traitement de tumeurs par induction magnétique d'une hyperthermie locale modérée. Nous exposons tout d'abord le contexte physique, biologique et clinique de l'hyperthermie comme traitement anticancéreux, particulièrement des modalités électromagnétiques. Les performances in vitro et in vivo des matériaux et formulations sont alors présentées. L'objet du chapitre suivant est la caractérisation des propriétés physicochimiques, magnétiques, et chauffantes, dans un champ magnétique alternatif (115 kHz, 9 - 12 mT), des microparticules de silice renfermant des nanoparticules d'oxyde de fer superparamagnétiques (SPIONs) et de deux de leurs formulations: un hydrogel d'alginate de sodium et un organogel de poly(éthylène-co-alcool vinylique) dans le diméthylsulfoxide. Finalement, nous présentons le potentiel thérapeutique de 20 minutes d'hyperthermie locale induite après injection de l'organogel superparamagnétique dans un modèle murin sous-cutané de tumeurs nécrosantes de colocarcinome humain.