Conventional fibers are comprised of a solid glass core and solid glass cladding often protected by a thin polymer sheath. The finely tuned difference in refractive indices, for step index-fibers, is achieved by doping the core with germanium or elements with similar effects. Holey fibers (including photonic crystal fibers) comprise of a pure silica core, and a pure but porous silica cladding of air holes [1]. This provides a huge difference in the refractive indices on the cladding and core without doping. This translates into radiation resistant fibers with very low losses and very robust to high temperatures to mention a few [2]. Several successful attempts have been made for ordered holey optical fibers since the initial publication by Knight et al; random holey optical fibers, which can be just as effective, have yet to be fabricated [3]. Sol-gel processing of silicon alkoxides can be used to fabricate silica monoliths of tailored pore densities and sizes [4]; this makes the process attractive for random holey fiber preform manufacturing. Similar attempts have been made by Okazaki et al [5] to make conventional optical fibers. This paper chronicles efforts to make random holey fiber optical preforms from silica sol-gel monoliths, characterized for some structural properties. Silica monoliths can be made by hydrolysis and condensation of TEOS (tetraethylorthosilicate) or TMOS (tetramethylorthosilicate). These can be catalyzed in a single step or two-step process, aged and dried at ambient pressures and temperatures, as well as by supercritical fluid extraction of CO2. Mechanical strengthening techniques as described by Okazaki [5] have also been employed. The silica gel monoliths are characterized by helium pycnometry and scanning electron microscopy. Various shapes and densities of silica monoliths have been prepared and characterized. Some of these have also drawn into fibers to demonstrate their viability. / Master of Science

The sol–gel method is a straightforward technique that allows electrode modification with silica thin films. The silica pores could be functionalized to enhance the electrochemical and optical characteristics. Silica was functionalized with ferrocene using electroassisted accumulation, creating composite electrodes (Fc@Silica electrode). These electrodes were tested by electrochemical and spectroelectrochemical methods, showing that ferrocene was stably confined in silica. The Fc@Silica film enhances the electrochemical response of cytochrome c in solution, which gives rise to further applications and electrochemical studies of other redox-active proteins. Class I hybrid silica matrices were studied by adding negatively charged poly(4-styrene sulfonic acid) (PSS) and positively charged poly(diallyl dimethylammonium chloride) (PDADMAC) to the silica precursor solution. These hybrid films were functionalized with ferrocene species. Silica-PSS films showed higher ferrocenium cation accumulation capacity. UV-vis spectroscopy indicates the electroactivity of ferrocene confined within the silica and hybrid silica films. An enhancement in the cyt c signal was observed with the Fc@silica-PSS films. Silica was used as a host material for fluorescent conjugated polymers, specifically Poly(9,9-dioctyl-fluorene) (PFO). Polyfluorene nanoparticles were synthetized using the mini-emulsion method and were incorporated into a silica matrix. These matrices were used for the spectroelectrochemical detection of ferrocene. The reduced form of ferrocene quenches the fluorescence of PFO. The extent fluorescence quenching depends on the concentration of ferrocenium. Incorporating polyelectrolytes within silica enhanced the performance of the spectroelectrochemical sensor. PFO@silica-PSS shows an improved response to ferrocene, offering new opportunity for the spectroelectrochemical detection of other redox species.

Thèse ou mémoire avec insertion d'articles / La fabrication additive (FA) est une technologie à fort potentiel d'utilisation dans les applications photoniques car elle surmonte les limites des méthodes de fabrication traditionnelles. Parmi les différentes techniques de FA disponibles, la photopolymérisation en cuve (VPP) est l'une des rares à répondre aux exigences de la fabrication photonique. Cependant, l'un des principaux défis qui entravent l'adoption généralisée du VPP dans la fabrication de dispositifs optiques est la disponibilité limitée de matériaux compatibles avec les techniques VPP. L'objectif de cette thèse était de développer, d'élucider la structure, de fabriquer via la fabrication additive et d'étudier les propriétés optiques de pièces imprimées en 3D de matériaux hybrides aluminium-phosphate. Ces matériaux ont été développés par voie sol-gel comme candidats pour la fabrication de dispositifs photoniques actifs et passifs. Ces matériaux ont été fabriqués via VPP en utilisant un système AM sur mesure fonctionnant dans des conditions d'exposition intermittentes. Nous avons développé un modèle mathématique décrivant le profil d'exposition produit par cette système VPP, car son principe de fonctionnement diffère grandement des plateformes commerciales. Ensuite, les paramètres VPP et la cinétique de photopolymérisation de ces nouveaux matériaux ont été caractérise, de façon a démontré leur impression 3D. Enfin, nous avons examiné l'homogénéité optique et l'anisotropie des éléments fabrique 3D à partir de ces matériaux. Ces objectifs ont été explorés à travers cinq publications scientifiques, composant les cinq chapitres de cette thèse. Dans notre première contribution, nous avons synthétisé des sols de phosphate d'aluminium photopolymérisables, qui ont été polymérisés pour aboutir à des matériaux hybrides organiques-inorganiques (OIH) composés de chaînes de poly (méthacrylate de 2-hydroxyéthyle) avec des groupes de phosphate d'aluminium liés de manière covalente au squelette polymère. Ces unités inorganiques fournissent de nombreux agents de réticulation, résultant en une structure inorganique/organique hautement interconnectée et imbriquée. Les matériaux OIH étaient optiquement transparents entre 420 nm et 1100 nm, cependant, ces matériaux présentaient une faible transmission dans la région du proche infrarouge (NIR) en raison de la forte teneur en matières organiques de ces matrices. Dans une deuxième contribution, nous avons modifié la voie de synthèse pour obtenir des matériaux OIH aluminium-phosphate-silicate avec une concentration en masse inorganique plus élevée et une transmittance améliorée dans le NIR. Nous avons étudié en profondeur la structure de matériaux avec la RMN à l'état solide et observé que le réseau inorganique est formé d'unités d'aluminium-phosphate interconnectées par des chaînes de silicate. L'environnement chimique des sites de phosphate et d'aluminate pourrait être réglé en fonction du rapport aluminium sur phosphore, permettant à la structure d'être adaptée afin d'améliorer la capacité d'accueil des ions lanthanides de ces matériaux. Ces caractéristiques structurelles présentent ces matériaux comme des candidats potentiels pour immobiliser les ions lanthanides pour développer des composants optiques actifs. Dans une troisième contribution, nous avons développé et testé un modèle mathématique décrivant le profil d'exposition produit par l'imprimante utilisée dans ce travail, nous permettant de modéliser l'interaction laser-résine dans cet équipement, et de corréler les paramètres d'impression mesurés pour notre matériau avec ceux des système FA commerciales. De plus, nous avons identifié que ce système d'impression peut, théoriquement, imprimer plus rapidement par rapport aux plateformes commerciales dans des conditions spécifiques de diamètre de faisceau et de chevauchement entre les impulsions. Dans une quatrième contribution, nous avons exploré la fabrication additive des résines aluminium-phosphate-silicate. L'évolution des paramètres d'impression 3D de ces matériaux (énergie critique et profondeur de pénétration), et de la cinétique de photopolymérisation avec l'intensité lumineuse et la concentration en silicate a été étudiée. Ces résultats indiquent le déplacement de la conversion critique vers un degré de polymérisation plus élevé à mesure que la concentration de silicate augmente, ce qui était associé à une tendance plus élevée à la cyclisation. Ces résultats ont été utilisés pour valider un modèle photochimique publié dans la littérature décrivant l'interaction laser-résine dans les systèmes VPP, élucidant le lien entre l'énergie critique et la cinétique de photopolymérisation. Dans notre dernière contribution, nous avons étudié la distribution de l'indice de réfraction et la présence d'anisotropies optiques dans les lignes imprimées en 3D. Nous avons identifié que les pièces imprimées en 3D sont optiquement homogènes, malgré la présence d'un gradient de degré de polymérisation associé à la pénétration du laser dans la résine et au profil du faisceau. Des anisotropies optiques ont été identifiées et des mesures micro-Raman polarisées indiquent que la biréfringence provient de la contrainte de cisaillement perpendiculaire à la direction de balayage due à l'afflux de monomère vers le point de polymérisation. / Additive manufacturing (AM) is a technology with great potential for use in photonic applications because it overcomes the limitations of traditional manufacturing methods. Among the various AM techniques available, the vat-photopolymerization (VPP) is one of the few that meets the requirements for photonics manufacturing. However, one of the main challenges hindering the widespread adoption of VPP in optical device manufacturing is the limited availability of materials compatible with VPP techniques. The aim of this thesis was to develop, elucidate the structure of, fabricate via additive manufacturing, and study the optical properties of 3D printed parts of aluminum-phosphate hybrid materials. These materials were developed using the sol-gel route as candidates for the fabrication of active and passive photonic devices. These materials were additive manufactured via VPP using a custom-made AM system operating under intermittent exposure conditions. We developed a mathematical model describing the exposure profile output by this custom-made VPP setup, since its operating principle greatly differs from commercial platforms. Then, these new materials were 3D printed after characterizing their VPP parameters and photopolymerization kinetics. Lastly, we examined the optical homogeneity and anisotropy of additive manufactured elements from these materials. These goals were explored throughout five scientific publications, composing the five chapters of this thesis. In our first contribution, we synthesized photopolymerizable aluminum-phosphate sols, that were polymerized to result in organic-inorganic hybrid (OIH) materials composed by poly (2-hydroxyethyl methacrylate) chains with aluminum-phosphate groups covalently bonded to the polymeric backbone. These inorganic units provide numerous crosslinkers, resulting in a highly interconnected and interlocked inorganic/organic structure. The OIH materials were optically transparent between the 420 nm - 1100 nm, however, these materials showed low transmittance in the near-infrared region (NIR) due to the high organic content of these matrices. In a second contribution, we modified the synthesis route to achieve aluminum-phosphate-silicate OIH materials with higher inorganic mass concentration and improved transmittance in the NIR. We investigated in-depth the structure of these materials by means of solid-state NMR and observed that the inorganic network is formed by aluminum-phosphate units interconnected by silicate chains. The chemical environment of the phosphate and aluminate sites could be tuned based on the aluminum to phosphorus ratio, allowing the structure to be tailored in order to enhance the lanthanide ions hosting ability of these materials. These structural features present these materials as potential candidates to immobilize lanthanide ions for developing active optical components. In a third contribution, we developed and tested a mathematical model describing the exposure profile outputted by the custom-built printer employed in this work, allowing us to model the laser-resin interaction in this equipment, and to correlate the printing parameters measured for our materials with those of commercial AM setups. Furthermore, we identified that this printing system can, theoretically, print faster compared to commercial platforms under specific conditions of beam diameter and overlap between pulses. In a fourth contribution, we explored the additive manufacturing of the aluminum-phosphate-silicate resins. The evolution of the 3D printing parameters of these materials (critical energy and penetration depth), and of the photopolymerization kinetics with light intensity and silicate concentration was studied. These results indicate the shift of critical conversion towards higher polymerization degree as the concentration of silicate increases, which was associated to a higher tendency towards cyclization. These results were employed to validate a photochemical model published in the literature describing the laser-resin interaction in VPP systems, elucidating the link between critical energy and photopolymerization kinetics. In our last contribution, we studied the refractive index distribution and the presence of optical anisotropies in 3D printed lines. We identified that the 3D printed parts are optically homogenous, despite the presence of a gradient of polymerization degree associated to the penetration of the laser into the resin and the beam profile. Optical anisotropies were identified, and polarized micro-Raman measurements indicate that the birefringence arises from the shear stress perpendicular to the scan direction due to the inflow of monomer towards the polymerization spot. / A manufatura aditiva (MA) é uma tecnologia com grande potencial para aplicações em fotônica, pois contorna as limitações impostas por métodos tradicionais de manufatura. Entre as várias técnicas de MA disponíveis, a fotopolimerização em cuba (VPP) é uma das poucas que atende os requisitos de tolerância presente na fabricação de dispositivos fotônicos. No entanto, um dos principais desafios que impedem ampla adoção da VPP na fabricação de dispositivos ópticos é a baixa disponibilidade de materiais processáveis com as técnicas de VPP. O objetivo desta tese foi desenvolver, elucidar a estrutura, fabricar via manufatura aditiva e estudar as propriedades ópticas de peças impressas 3D de materiais híbridos de alumínio-fosfato. Esses materiais foram desenvolvidos utilizando a rota sol-gel como candidatos para a fabricação de dispositivos fotônicos ativos e passivos via impressão 3D. Esses materiais foram processados via VPP usando um sistema MA customizado, operando sob condições de exposição intermitente. Foi desenvolvido e testado um modelo matemático descrevendo o perfil de exposição produzido por esse sistema VPP customizado, uma vez que seu princípio operacional difere daquele de plataformas comerciais. Em seguida, os parâmetros de impressão 3D e a cinética de fotopolimerização desses novos materiais foram estudados, permitindo sua impressão 3D. Por fim, foi estudado a homogeneidade óptica e a presença de anisotropias ópticas em partes produzidas por MA desses materiais. Esses objetivos foram explorados ao longo de cinco publicações científicas, compondo os cinco capítulos desta tese. Em nossa primeira contribuição, sintetizamos soluções fotopolimerizáveis de alumínio-fosfato, resultando em materiais híbridos orgânico-inorgânicos (HOI) compostos por cadeias de poli (2-hidroxietil metacrilato) com grupos alumínio-fosfato covalentemente ligados ao esqueleto polimérico. Essas unidades inorgânicas atuam como ligações cruzadas, resultando em uma estrutura inorgânica-orgânica altamente interconectada e interligada. Os materiais obtidos são totalmente transparentes entre 420 nm - 1100 nm, porém possuem baixa transmitância na região do infravermelho próximo (NIR) devido ao alto teor orgânico dessas matrizes. Em uma segunda contribuição, modificamos a rota de síntese para obter materiais HOI de alumínio-fosfato-silicato com maior teor de massa inorgânica e melhor transmitância no NIR. Investigamos em detalhe a estrutura desses materiais por meio de RMN de estado sólido e observamos que a rede inorgânica é formada por unidades de alumínio-fosfato interligadas por cadeias de silicato. O ambiente químico dos sítios de fosfatos e alumínio podem ser modificados por meio da razão alumínio para fosforo, permitindo que a estrutura seja otimizada para a introdução de íons lantanídeos. Essas características estruturais apresentam esses materiais como potenciais candidatos à imobilização de íons lantanídeos para o desenvolvimento de componentes ópticos ativos. Em uma terceira contribuição, desenvolvemos e testamos um modelo matemático descrevendo o perfil de exposição produzido pela impressora personalizada empregada neste trabalho, permitindo-nos modelar a interação laser-resina e correlacionar os parâmetros de impressão medidos para nossos materiais com aqueles de plataformas comerciais de MA. Além disso, identificamos que este sistema de impressão pode, teoricamente, imprimir mais rápido comparado a plataformas comerciais, desde que condições específicas de diâmetro do feixe e sobreposição entre pulsos sejam atendidas. Em uma quarta contribuição, exploramos a manufatura aditiva das resinas de alumínio-fosfato-silicato. Foi estudada a evolução dos parâmetros de impressão 3D desses materiais (energia crítica e profundidade de penetração) e da cinética de fotopolimerização com a intensidade de luz e a concentração de silicato. Os resultados obtidos indicaram um aumento da conversão critica das resinas com o aumento da concentração de silicato, o que estaria associado a uma maior contribuição da reação de ciclização. Esses resultados foram empregados para validar um modelo fotoquímico descrevendo a interação laser-resina em sistemas VPP publicados na literatura, elucidando a relação entre energia crítica e cinética de fotopolimerização. Em nossa última contribuição, estudamos a distribuição do índice de refração e a presença de anisotropias ópticas em linhas impressas 3D. Foi verificado que as peças impressas em 3D são opticamente homogêneas, apesar da presença de um gradiente de grau de polimerização associado à penetração do laser na resina e do perfil do feixe. Anisotropias ópticas foram identificadas, e medidas de espalhamento micro-Raman polarizado indicaram que a birrefringência e oriunda da tensão de cisalhamento perpendicular à direção da varredura causada pelo influxo de monômero em direção ao centro da polimerização.

Des matériaux hybrides organiques-inorganiques mésostructurés ont été élaborés par deux voies différentes: le procédé sol-gel et l'assemblage de « briques » hybrides moléculaires. Dans une première partie, nous nous sommes intéressés à la synthèse directe de mésoporeux cubiques monofonctionnalisés (SBA-16) par voie sol-gel. Différents groupements organiques ont été insérés dans les pores du matériau (SH, CN, Cl, PO(OEt)2 et acac). Leur accessibilité a été mise en évidence par la complexation d'un lanthanide (europium) grâce aux fonctions acac, mais aussi par la croissance de nanoparticules d'or régulièrement distribuées dans les pores grâce aux groupements SH. Grâce à leur petite taille (2nm) et leur accessibilité, ces nanoparticules ont pu être utilisées en catalyse. Notre étude a ensuite été étendue aux matériaux mésoporeux bifonctionnels. La fonctionnalisation des pores et de la charpente de silices hexagonales (SBA-15) a été réalisée en une seule étape. Plusieurs fonctionnalités chimiques ont été insérées avec succès et ont permis le confinement intime de deux types de nanoparticules pouvant interagir entre-elles. Le matériau est alors qualifié d' « interactif ». Dans une dernière partie, nous avons développé une nouvelle approche de la synthèse de matériaux 3D organisés par assemblage de « cages » moléculaires hybrides (octasilsesquioxanes fonctionnalisés). Nous avons choisi des fonctions Cl, facilement convertibles en acides ou en ions et capables de s'auto-assembler par liaisons faibles (liaisons H) ou par forces coulombiennes. Nous avons également envisagé d'utiliser des « connecteurs » organiques comme le cyclame, capables de lier les différentes cages par liaison covalente et de fixer des ions métalliques. / Mesostructured hybrid materials (organic-inorganic) were prepared according two different ways: the sol-gel process on the one hand, the assembly of molecular hybrid 'bricks' on the other. In the first part, we focused on the one-pot synthesis of monofunctionalised cubic silicas (SBA-16) through the sol-gel process. Different organic functions were successfully introduced within the pores of the material (SH, CN, Cl, PO(OEt)2 and acac). Their accessibility was brought to light by complexation of lanthanide salts (europium) by acac moieties, but also by growing of gold nanoparticles within the pores, regularly distributed thanks to the SH groups. Thanks to their small size (2 nm) and their high accessibility, these supported nanoparticles could be used as catalysts. Secondly, our study was extended to bifunctional materials. 2-D hexagonal silicas (SBA-15) were functionalised by one-step synthesis within both pores and walls. Several organic groups were covalently included within the structure, which then allowed us to confine very closely two kinds of nanoparticles, able to interact between themselves at nanometric scale. The bimetallic material is consequently qualified as 'interactive'. The last part was dedicated to a new approach for the synthesis of 3-D structured materials, consisting in the assembly of hybrid molecular 'cages' (functionalised octasilsesquioxanes). Chloro terminations were chosen because of their easy conversion into acid or ionic moieties, able to self-assemble, driven by weak interactions such as H-bonds or electrostatic forces. The use of organic “linkers” such as cyclam groups was also considered to connect cages and anchor metallic ions.

L'objet de cette thèse a été l'étude de la structuration et de la fonctionnalisation de matériaux hybrides organiques-inorganiques par le procédé sol-gel.La synthèse et la caractérisation de nouvelles membranes à conduction protonique, pour pile à combustible à membrane échangeuse de protons, ont été réalisées dans la première partie. Des membranes hybrides à base de polyéthylène glycol hautement fonctionnalisées par de l'acide sulfonique ont été synthétisées et caractérisées d'un point de vue physicochimique et conductivité protonique. Elles présentent des bonnes propriétés mécaniques, une stabilité chimique suffisante et une conductivité protonique pertinente pour être utilisées comme électrolyte dans les piles à combustible à membrane échangeuse de proton.Dans une seconde partie, nous avons développé des matériaux hybrides mésoporeux et multifonctionnalisés dans les pores en présence de tensioactif de type copolymère block non-ionique (P123). Deux sondes ont été utilisées pour cette étude: la capacité d'échange protonique et le contrôle de la croissance des nanoparticules d'or dans les pores. / The aim of this work was focused on the structuration and the functionalization of organic-inorganic hybrid materials by the sol-gel process.The synthesis and characterization of new proton conductive membranes for fuel cell proton exchange membrane (PMFC), was prepared in the first part. Hybrid membranes based on polyethylene glycol highly functionalized with sulfonic acid have been synthesized and characterized through a physicochemical and proton conductivity. They have good mechanical properties, a sufficient chemical stability and a performant proton conductivity to be used as an electrolyte in fuel cell proton exchange membrane.In the second part, we have developed hybrid mesoporous materials with porous multifunctionalized in the presence of surfactant nonionic block copolymer (P123). Two probes were used for this study: the proton exchange capacity and the control of the growth of gold nanoparticles in the pores.

Les synthèses par sol-gel non-hydrolytique (SGNH) d'oxydes mixtes Re-Si-Al et Mo-Si-Al sont présentées comme une voie innovante pour la préparation en une étape de catalyseurs hétérogènes de métathèse. Les catalyseurs supportés à base d'oxyde de molybdène sont intéressants du fait de leur faible coût d'achat, de leur résistance mécanique et de leur bonne activité à température modérée. Les catalyseurs supportés à base d'oxyde de rhénium sont connus pour être très actifs et sélectifs même à température ambiante. Cependant ils sont chers et la sublimation de l'oxyde de rhénium pose problème lors de leur synthèse. La synthèse utilisée est basée sur la réaction en une étape des précurseurs chlorés (ReCl5 ou MoCl3, SiCl4, AlCl3) avec du diisopropyléther (iPr2O) à 110 °C dans le dichloromethane. Le faible coût des précurseurs, l'absence de modificateurs de réactivité et de templates ainsi que la simplicité de synthèse rendent le procédé SGNH particulièrement attractif. Les catalyseurs oxydes mixtes obtenus présentent des compositions bien contrôlées, des textures mésoporeuses et avec des densités en sites acides élevées. La caractérisation par DRX, XPS et ToF-SIMS montre que les catalyseurs peuvent être décrits comme une matrice silice-alumine amorphe avec des espèces de surface Mo et Re bien dispersées. Pour les catalyseurs à base de Re, dans les compositions riches en silice, des pertes de rhénium ont été observées durant la calcination. Cette perte de rhenium peut être évitée en augmentant le taux d'alumine dans la composition. De plus, nous avons montré que la sublimation de Re, au cours de la calcination dans les compositions riches en silice, n'a pas lieu quand toutes les étapes du procédé (synthèse, lavage, séchage et calcination) sont réalisées en l'absence d'humidité. Nous avons étudié l'influence de la composition sur la texture, la structure, l'acidité et les propriétés de surface, qui sont corrélées aux performances catalytiques. Les performances des catalyseurs Re-Si-Al et Mo-Si-Al ont été évaluées en métathèse du propène et en métathèse croisée de l'éthène et du trans-2-butène. Les catalyseurs SGNH sont comparés à des catalyseurs avec des compositions similaires préparés par d'autres méthodes (imprégnation, thermal spreading, flame spray pyrolysis). Les catalyseurs préparés par SGNH présentent une très bonne activité spécifique en métathèse. / The non-hydrolytic sol-gel synthesis (NHSG) of Re-Si-Al and Mo-Si-Al mixed oxides was proposed as an innovative one step route to heterogeneous olefin metathesis catalysts. Supported molybdenum oxide catalysts are receiving much attention as a result of their relatively low price, robustness and good activity at low temperature. Supported rhenium oxide catalysts are known to be highly active and selective even at room temperature. However, they are expensive and moderately stable because of the sublimation of the rhenium oxide. The NHSG synthesis used in this work is based on the one pot reaction of chloride precursors (ReCl5 or MoCl3, SiCl4, AlCl3) with diisopropylether (iPr2O) at 110 °C in dichloromethane. The simplicity of NHSG makes it attractive: multi-step procedures, expensive precursors, or reactivity modifiers are not needed. The mixed oxide catalysts exhibited well-controlled compositions and mesoporous textures, with high acid site densities. XRD, XPS and ToF-SIMS showed that the catalysts could be described as an amorphous silica-alumina matrix with well-dispersed Re or Mo surface species. In the case of Re-based catalysts, rhenium losses by sublimation during calcination were observed for the silica-rich formulations. The loss of rhenium could however be avoided by increasing the Al content. More importantly we demonstrate that Re sublimation during calcination of silica-rich formulations is suppressed when the whole preparation procedure (synthesis, washing, drying and calcination) is carried out in the absence of water. Particular attention was devoted to the study of the influence of the composition on texture, structure, acidity and surface properties, which were correlated with the catalytic performances. The performance of selected Re-Si-Al and Mo-Si-Al catalysts was evaluated in the metathesis of propene and in the cross-metathesis of ethene and trans-2-butene. The NHSG catalysts were compared to catalysts of similar compositions prepared by other more methods (impregnation, thermal spreading, flame spray pyrolysis). The catalysts prepared by NHSG have a high specific activity in the metathesis reaction.

Les matériaux dopés avec des ions de terres rares continuent de faire l’objet de nombreuses recherches grâce à leur efficacité dans les domaines de la photonique et leurs applications dans les amplificateurs ou laser à fibre optique. Dans ce contexte, dans un premier temps, des massifs de silice (SiO2) dopée par des ions europium (Eu3+) ont été préparés par le processus Sol-Gel. Les propriétés de luminescence des ions de terres rares ont été étudiées dans ces massifs, ainsi que dans des massifs co-dopés avec du magnésium et traités thermiquement à 900°C. Les propriétés optiques des ions Eu3+ ont été étudiées aussi dans un environnement totalement différent : des nanoparticules de silice (NPSi). Ces différents matériaux ont été caractérisés par ICP-OES, MET, DRX, analyse de sorption et FT-IR. La première partie de ce manuscrit décrit comment la taille des NPSi, la quantité d’europium, le traitement thermique et la présence de magnésium modifient les propriétés de photoluminescence des ions Eu3+.Le second axe de ce travail de thèse concerne l'étude de la réactivité des ions fluorures dans le système ternaire SiO2-GeO2-LaF3. Plusieurs mélanges binaires et ternaires ont été élaborés et calciné à 1500°C puis étudiés par ATG, EDS-MEB, DRX et spectroscopie Raman. L'évaporation des ions F- a été mise en évidence via une réaction préférentielle avec le silicium (pour former SiF4) plutôt qu'avec le germanium. Dans le système ternaire, nous avons observé la formation de la phase La2Si2O7. / Rare earth ions doped materials continue to be the subject of several researches thanks to their efficiency in the fields of photonics and their applications in amplifiers or optical fiber lasers. In this context, firstly, silica bulks (SiO2) doped with europium ions (Eu3+) were prepared by Sol-Gel process. The luminescence properties of rare earth ions were studied in these bulks, as well as in bulks co-doped with magnesium and heat-treated at 900°C. The optical properties of Eu3+ ions have also been studied in a very different environment: silica nanoparticles (NPSi). These different materials were characterized by ICP-OES, TEM, XRD, sorption analysis and FT-IR. The first part of this manuscript describes how the size of the NPSi, the amount of europium, the heat treatment and the presence of magnesium modify the photoluminescence properties of Eu3+ ions.The second axis of this work concerns the study of the reactivity of fluoride ions in the ternary system SiO2-GeO2-LaF3. Several binary and ternary mixtures were prepared and heat-treated at 1500°C and then studied by TGA, EDS-SEM, XRD and Raman spectroscopy. The evaporation of F- ions has been evidenced by a preferential reaction with silicon (to form SiF4) rather than with germanium. In the ternary system, we observed the formation of La2Si2O7 phase.

Ces travaux de thèse portent sur l’élaboration et la caractérisation de revêtements sol-gel composites ≪ CSG ≫ sur acier inoxydable austénitique AISI 304. L’objectif de la thèse était de mettre au point le procédé d'élaboration et d'étudier les propriétés mécaniques et le comportement tribologique des revêtements. La première partie expérimentale présente l’optimisation des conditions de synthèse d’un sol d’alumine stable et l’influence du traitement thermique du gel sur les propriétés physico-chimiques et thermostructurales. Les paramètres étudiés sont : La stabilité chimique du sol et les conditions de traitement thermique (température et temps). Différentes techniques de caractérisations ont été utilisées pour l'optimisation des paramètres d'élaboration (rhéométrie, ATD/ATG, dilatométrie, DRX, MET, pynométrie hélium). Un dopage au nitrate de fer a permis d'améliorer les conditions de frittage de l'alumine sol-gel grâce à la formation d'une solution solide (Al,Fe)2O3. Cela reste cependant insuffisant pour une application du revêtement sur le substrat acier. La seconde partie concerne l’élaboration et la caractérisation mécanique de revêtements sol-gel composites ≪ CSG ≫ charges de particules d’α-Al2O3 et de h-BN. Ce procédé a permis d'obtenir par dip-coating des dépôts monocouches de 8,5 micromètres environ avec des taux de charge de 90% volumique. Cependant, un tel taux de charge provoque la création d’une porosité importante. Les couches CSG traitées thermiquement à 750°C ont par la suite été caractérisées mécaniquement par indentation instrumentée. Les résultats obtenus ont montré une trop faible dureté des couches pour pouvoir améliorer la résistance à l'usure. La dernière partie de la thèse concerne le renforcement des revêtements CSG après traitement à l'acide phosphorique et traitement thermique à 400°C. La formation de liaisons phosphates entre les grains d'alumine renforce l'architecture du composite qui est note CB-CSG ≪ Chemically Bonded Composite Sol-Gel ≫. Des essais d'indentation instrumentée montrent, pour des revêtements CB-CSG charges d’alumine, une amélioration de la dureté par rapport au substrat en acier. Des essais de frottements secs en configuration bille sur plan montrent une augmentation de la résistance aux frottements secs d’un facteur 5 et une diminution du coefficient de frottement par rapport au substrat. L’influence du nitrure de bore hexagonal dans les couches CB-CSG en plus de l'alumine a été étudiée en particulier en ce qui concerne les propriétés mécaniques et tribologiques. / This thesis focuses on the elaboration and the characterization of composite sol-gel coatings “CSG” on austenitic stainless steelAISI 304. The aim of the thesis is to develop the process and to study the mechanical properties and tribological behavior of thecoatings. The first experimental part presents the optimization of the synthesis conditions of a stable alumina sol and the influence of the thermal treatment of the gel on the physic-chemical and thermostructural properties. The studied parameters are: The chemical stability of the sol and the thermal treatment conditions (temperature and time). Various characterization techniques are used in order to optimize the elaboration parameters (rheometry, DTA / TGA, dilatometry, XRD, TEM, helium pycnometry). A Doping with iron nitrate has improved the sintering conditions of the sol-gel alumina through the formation of a solid solution (Al,Fe)2O3. However, this remains insufficient for an application of the coating on the steel substrate. The second part concerns the elaboration and the mechanical characterization of composite sol-gel coatings "CSG" filled with particles of α-Al2O3 and h-BN. This process enables the deposition by dip coating of monolayer coatings of 8.5 micrometers thickness with fill rate of 90% by volume. However, such filler content produces a high porosity. The CSG layers thermally treated at 750°C have been mechanically characterized by instrumented indentation. The results shown to low hardnesses in order to improve the wear resistance. The last part of the work presents the strengthening of CSG coatings with a treatment with phosphoric acid followed by a thermal treatment at 400°C. The formation of phosphate bonds between the alumina grains enhances the architecture of the composite which is denoted CB-CSG "Chemically Bonded Composite Sol-Gel". Instrumented indentation tests show, for CBCSG coatings filled with alumina, an improvement of hardness compared to the steel substrate. Dry friction tests, with ball on disc configuration, show an increase of resistance to dry friction by a factor of 5 and a decrease of the coefficient of friction relatively to the substrate. The influence of the hexagonal boron nitride and of the alumina in the CB-CSG layers on the mechanical and the tribological properties are particularly studied.

Tratamentos de metais contra a corrosão usando formulações contendo derivados de cromo hexavalente (Cr6+) tem sido padrão na indústria de tratamento de superfície durante muitas décadas. Esses tratamentos oferecem excelente proteção contra a corrosão, fornecem boa base para pinturas, são baratos e relativamente fáceis de aplicar. Além do mais oferecem proteção ativa ao substrato devido à capacidade de autorregeneração. Porém, restrições ambientais e de saúde, tornadas mais severas a partir das últimas décadas, requerem a substituição destes tratamentos por processos que sejam ambientalmente corretos e não agressivos à saúde humana. Neste contexto, a indústria aeroespacial, amplamente dependente de ligas de alumínio com elevada resistência mecânica para a construção das aeronaves, é uma das mais atingidas, visto que várias das etapas do tratamento superficial e dos processos de proteção contra a corrosão destas ligas utilizam compostos de Cr6+. Dentro dessa nova realidade, a utilização de revestimentos híbridos derivados de silanos, obtidos pelo processo sol-gel, tem se apresentado como uma das alternativas mais investigadas para a substituição dos pré-tratamentos à base de cromato. Estes revestimentos formam uma cadeia polimérica compacta sobre a superfície do metal constituindo uma barreira efetiva contra espécies agressivas, podendo também ser funcionalizados para apresentarem compatibilidade com revestimentos orgânicos. Entretanto os mesmos não exibem proteção ativa contra a corrosão. Nesse trabalho o comportamento anticorrosivo, em solução de NaCl 0,1 M, de um revestimento híbrido produzido pela hidrólise e condensação do 3-glicidóxipropiltrimetóxisilano (GPTMS) e do tetraetil ortosilicato (TEOS) aplicado sobre a liga AA2024-T3 foi investigado por espectroscopia de impedância eletroquímica (EIS) e analisado por SEM/EDX. Com a finalidade de melhorar o desempenho dos revestimentos, as soluções de hidrólise foram modificadas pela introdução de 0,005 M de inibidores de corrosão derivados de triazol (benzotriazol (BTAH) e toliltriazol (TTA)) ou de organofosfonatos (ácido trimetileno fosfônico (ATMP) e ácido 1-hidróxietileno 1,1-difosfônico (HEDP)). Os resultados dos ensaios eletroquímicos mostraram que, apesar de eficientes para a proteção contra a corrosão da liga, o BTAH e o TTA interferem negativamente nas propriedades anticorrosivas do revestimento híbrido. Por sua vez, a modificação do híbrido com o ATMP ou HEDP melhorou a resposta de impedância do revestimento e aumentou sua estabilidade, se mostrando como um enfoque promissor para aumentar o desempenho do revestimento. A espectroscopia por emissão de fotoelétrons (XPS) e a espectroscopia Raman foram utilizadas para caracterizar o híbrido modificado com os organofosfonatos. Através da primeira técnica foi possível evidenciar a interação das moléculas de inibidor com a superfície metálica. Já os resultados de espectroscopia Raman indicaram a incorporação dos inibidores no revestimento, tendo sido mais eficaz para esta finalidade que as análises por XPS. Entretanto, para evidenciar esse processo, foi necessário aumentar a concentração dos inibidores em 10 vezes com relação à quantidade empregada nos ensaios eletroquímicos. / Anticorrosion metals treatments using formulations containing derivatives of hexavalent chromium (Cr6+) have been standard in the surface treatment industry for many decades. These treatments afford excellent corrosion protection, offer good base for paintings, are inexpensive and relatively easy to apply. Besides, they provide active protection to the substrate due to their selfhealing abilities. However, environmental and health restrictions, made more severe from the end of the eighties, require replacement of these treatments by processes that are environmentally friendly and not aggressive to human health. In this context, the aerospace industry, which is strongly dependent on high strength aluminium alloys, is one of the most heavily affected, as (Cr6+) compounds are used in several steps of the surface treatment and corrosion protection processes. Within this new reality, the use of hybrid coatings derived from silanes and obtained by the sol-gel process, has emerged as one of the most investigated alternatives to replace the chromate based pre-treatments. These coatings form a compact polymer network on the metal surface providing an effective barrier against aggressive species, they may also be tailored to present compatibility with organic coatings. However they do not exhibit active corrosion protection. In this study the corrosion behavior, in 0.1 M NaCl, of a hybrid coating produced by hydrolysis and condensation of 3glycidoxypropyltrimethoxysilane (GPTMS) and tetraethyl orthosilicate (TEOS) applied on AA2024-T3 alloy was investigated by means of electrochemical impedance spectroscopy (EIS) and analysed by SEM/EDX. Aiming to improve the coatings performances, the hydrolysis solutions were modified by the addition of 0.005 M of triazoles (benzotriazole (BTAH) and tolyltriazole (TTA)) or organophosphates (trimethylene phosphonic acid (ATMP) and 1hydroxyethylidene-1 1-diphosphonic acid (HEDP)) based corrosion inhibitors. The results of the electrochemical tests showed that, although effective for corrosion protection of the alloy, BTAH and TTA adversely impacted the anticorrosive properties of the hybrid coating. In turn, the modification of the hybrid with ATMP or HEDP improved the impedance response of the coating and increased its stability, proving to be a promising approach to enhance the coating performance. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy were used to characterize the hybrid modified with organophosphates. With the first technique it was possible to demonstrate the interaction of the inhibitor molecules with the metal surface. Raman spectroscopy results indicated the incorporation of the inhibitors in the coating, being more effective for this purpose than the XPS analysis. However, to demonstrate this process, it was necessary use the concentration of the inhibitors 10 times more than the amount employed in the electrochemical tests.

Filmes híbridos fotoativos de Ormosil (silicatos organicamente modificados) contendo o polioxometalato de Keggin ácido fosfotungstico (H3PW12O40) e cátions Ag+ foram preparados por meio da rota sol-gel e deposição de filme por dip-coating. A caracterização por FTIR, Raman, XRF e DRX evidenciou a formação da matriz de organossilicato e o aprisionamento dos poliânions PW12O403- e cátions Ag+. O comportamento fotocrômico dos filmes de Ormosil-fosfotungstato baseiam-se na redução fotoinduzida do fosfotungstato por exposição à radiação UV, o que leva à formação de compostos coloridos de valência mista conhecidos como heteropolyblues. No entanto, a presença de cátions Ag+ altera completamente o comportamento fotocrômico destes filmes híbridos. Os poliânions de fosfotungstato fotorreduzidos são agentes redutores eficientes na redução dos cátions Ag+, resultando na formação in situ de nanopartículas de prata metálica na matriz híbrida como evidenciado pela intensa banda plasmônica centrada em 390 nm no espectro eletrônico da amostra. A caracterização por Uv-vis e Espectroscopia de Absorção de Raios X próxima a Borda de Absorção (XANES) mostrou que a foto-redução pode ser revertida por tratamento térmico o que caracteriza um comportamento fotocrômico reversível. O comportamento cinético da amostra foi analisado propondo mecanismos para as reações de redução e oxidação da prata, responsáveis pela alteração de coloração do material. O aprisionamento de compostos fotoativos em matrizes híbridas orgânico-inorgânico via sol-gel é uma estratégia interessante para a preparação de materiais fotocrômicos com potenciais aplicações tecnológicas. A reversibilidade fotocrômica destes materiais os torna bons candidatos para aplicação em sistemas de memória óptica, filtros óticos de passa-banda estreita, dispositivos de ótica não linear, sensores de radiação UV e revestimentos bactericidas. / Sol gel entrapment of photoactive compounds in organic-inorganic hybrid matrices is an interesting strategy for the preparation of photochromic materials with potential technological applications. In this study, we report the preparation of photoactive Ormosil (organically modified silicates) hybrid films containing the Keggin polyoxometalate phosphotungstate (H3PW12O40) and Ag+ cations by sol-gel synthesis and dip coating deposition. The materials have been characterized by infrared absorption spectroscopy (FTIR), Raman spectroscopy and X-ray Fluorescence (XRF), thus evidencing the formation of hybrid organosilicate matrix and the entrapment of the PW12O40-3 polyanions and Ag+ cations. The photochromic behavior of the Ormosil-phosphotungstate films is based on photoinduced reduction of phosphotungstate upon exposure to UV radiation, which leads to the formation of colored mixed valence compounds known as heteropolyblues. However, the presence of Ag+ cations completely changes the photochromic behavior of these hybrid films. The photoreduced phosphotungstate polyanions rapidly promote the reduction of Ag+ cations, resulting in the in situ formation of silver metal nanoparticles (Ag0) inside the hybrid matrix as evidenced by the intense plasmonic band centered at 390nm as shown by electronic, UV-vis, spectroscopy and its yellowish color. The Uv-vis and X-ray Near Edge Absorption Spectroscopy (XANES) characterization shown that this process is reversible and the yellowish color characteristic of the metallic silver nanoparticles disappears once the hybrid films are heated at 353 K. Thus, the coloration is achieved upon UV exposure and discoloration occurs upon simple heating. Therefore, the described photoactive properties, the prepared hybrid films have potential application in optical memory systems, single bandpass optical filters, non-linear optical devices, UV radiation sensors and bactericidal coatings.