En milieu aqueux, les verres nucléaires AVM présentent de grandes différences de comportement à l'altération, malgré de faibles variations de composition. La vitesse résiduelle d'altération de ces verres est contrôlée par deux phénomènes, qui sont la précipitation de phases secondaires de type hectorites alumineuses, qui en altérant le gel protecteur, augmentent la vitesse résiduelle d'altération du verre, et, la diffusion de l'eau à travers un gel plus ou moins protecteur. Le magnésium, contenu dans ces verres, facilite la précipitation de ces phases secondaires, mais s'incorpore également dans le gel, augmentant son pouvoir de passivation. La prédominance de l'un ou l'autre de ces phénomènes dépend de la composition initiale du verre, du pH de la solution, des conditions d'altération. Altérés en eau souterraine de stockage (riche en Mg et Ca), les verres AVM s'altèrent moins qu'en eau pure, et ce malgré la précipitation de phases secondaires. Le calcium s'incorpore dans le gel, à la place du sodium et du magnésium, augmentant son pouvoir de passivation. Nous avons adapté le modèle géochimique d'altération des verres GRAAL, aux verres AVM. Malgré ses limites, ce modèle nous permet de rendre compte des différences de comportement entre les verres AVM, selon leur composition, ainsi que de proposer un modèle opérationnel de l'altération des verres AVM. / During their aqueous alteration, AVM French nuclear glasses exhibit a large range of behaviour, in spite of a small range of composition. AVM glasses alteration rates are controlled by two phenomena: (i) precipitation of secondary phases, mostly aluminous hectorites, and (ii) diffusion of water across a more or less protective gel. The magnesium contained in these glasses increases the precipitation of these secondary phases, leading to a partial or total dissolution of the gel layer. This dissolution increases the glass alteration rates. On the other hand, Mg also incorporates in the gel, increasing his passivation properties. The predominance of one of these two phenomena depends on the initial composition of the glass, the pH of the solution, and the alteration conditions. In presence of Bure geological disposal site water (Mg and Ca rich), AVM glasses undergo less alteration than in initially pure water, in spite of larger amounts of secondary phase precipitates. This results from incorporation of calcium in the gel instead of sodium and magnesium, improving its passivating properties. We have adapted the geochemical GRAAL model for AVM glasses. In spite of its limitations, this model allows us to describe the differences of behaviour between these glasses, in function of their composition. Moreover, GRAAL can be proposed as a basis of a future operational model for predicting the alteration of AVM glasses.

Os argilominerais são empregados na área farmacêutica e cosmética tanto como excipientes quanto ingredientes ativos. Esses compostos inorgânicos são inertes quimicamente, apresentam estruturas definidas e alta estabilidade térmica, o que contribui para o uso nessas áreas. Atualmente a indústria farmacêutica busca modificações no sistema de entrega de drogas (melhorias no tempo, local e taxa de liberação), objetivando um aumento na estabilidade das drogas e a prevenção e diminuição de efeitos colaterais. Nesse sentido, surge a necessidade de desenvolver novas formulações farmacêuticas, novos métodos de preparação e novos materiais. Considerando o fato dos argilominerais incorporarem espécies diversas entre suas lamelas, é interessante explorar a possibilidade de uso dessas matrizes inorgânicas como carregadores de espécies bioativas. O principal objetivo do presente trabalho foi preparar e caracterizar argilas de uso farmacêutico e/ou cosmético intercaladas com espécies que apresentam potencial terapêutico. Para tanto, usou-se duas argilas esmectitas naturais do tipo montmorilonita (Cloisita Sódica e Veegum HS) e uma esmectita sintética do tipo hectorita (Laponita RD). Os aminoácidos L-lisina, L-arginina e L-ornitina, e o dipeptídeo L-carnosina foram imobilizados em argilas catiônicas, por meio de reação de troca iônica. Na preparação dos materiais híbridos, alguns parâmetros experimentais foram avaliados: concentração hidrogeniônica (pH) da suspensão de reação, proporção argila/aminoácido e tempo de reação. As argilas precursoras e os materiais híbridos obtidos foram caracterizados por difratometria de raios X, espectroscopia vibracional na região do infravermelho e Raman, análise termogravimétrica acoplada à espectrometria de massas e análise química de carbono. Os valores de distância interlamelar (d(001)) dos materiais sugerem que a cadeia carbônica das espécies orgânicas se orienta paralelamente em relação às lamelas de baixa densidade de carga dos argilominerais. Nos espectros vibracionais na região do infravermelho há predominância das bandas características da estrutura inorgânica, mas as bandas entre 1800 e 1400 cm-1 relativas aos grupos funcionais do aminoácido permitem inferir sobre o seu grau de protonação no material híbrido. A acidez de Brönsted gerada pela polarização das moléculas de água associadas à argila foi observada para as montmorilonitas empregadas neste estudo. Amostras preparadas em suspensões nas quais o valor do pH era maior que o valor da primeira constante ácida (pKa1) dos aminoácidos apresentam bandas atribuídas ao estiramento C=O de grupo carboxilato protonado. Os espectros Raman foram obtidos apenas para a argila sintética, uma vez que as naturais apresentam luminescência. O espectro Raman da L-carnosina imobilizada em Laponita indica a presença preponderante da espécie zwitteriônica; o deslocamento das bandas atribuídas aos grupos amida e carboxílico do dipeptídeo para região de menor energia sugere a formação de ligações de hidrogênio com os grupos silanol da Laponita. Os resultados de análise termogravimétrica acoplada à espectrometria de massas dos materiais híbridos são distintos daqueles observados para os aminoácidos livres. A temperatura de início de decomposição das espécies orgânicas não é praticamente modificada após imobilização nas argilas, mas os processos térmicos se estendem até regiões de maior temperatura, evidenciando a influência da estrutura inorgânica sobre a decomposição térmica dos aminoácidos. Através dos dados de quantidade de carbono e de água nas amostras, calculou-se a concentração de aminoácidos nos materiais híbridos (massa de aminoácido / 100 gramas de material). As maiores concentrações de aminoácido (entre seis e oito por cento) foram observadas para as amostras de Cloisita e Veegum HS, isoladas em condições nas quais predomina a interação eletrostática entre as lamelas e os aminoácidos com carga positiva. Nas condições experimentais empregadas neste trabalho não foi observada a saturação das argilas com os aminoácidos, ou seja, as cargas das lamelas não foram totalmente neutralizadas pelos íons orgânicos. / Clay minerals are used as excipients or active ingredients in the pharmaceutical and cosmetic fields. These inorganic compounds are chemically inert, have defined structures and high thermal stability, which make them useful for these areas. Currently the pharmaceutical industry seeks modifications in the drug delivery systems (improvements in the time, place and rate of release), aiming an increase in the stability of the drugs and also the prevention and reduction of side effects. In this way, it is a need to develop new pharmaceutical formulations, new preparation methods and new materials. Considering the fact that clay minerals incorporate various species between their layers, it is interesting to explore the possibility of using these inorganic matrices as carriers of bioactive species. The main aim of this work was to prepare and characterize clays of pharmaceutical and/or cosmetic usage intercalated with species of therapeutic potential. Two natural smectite clays of montmorillonite type (Sodium Cloisite and Veegum HS) and one synthetic smectite of hectorite type (Laponita RD) were employed. The amino acids L-lysine, L-arginine and L-ornithine, and the L-carnosine dipeptide were immobilized on cationic clays by ion exchange reaction. Some experimental parameters were evaluated in the preparation of hybrid materials: hydrogen ion concentration (pH) of reaction suspension, clay/amino acid proportion and reaction time. Pristine clays and hybrid materials were characterized by X-ray diffraction, infrared and Raman vibrational spectroscopies, thermogravimetric analyses coupled to mass spectrometry and chemical analysis of carbon. The materials values of interlayer distance (d(001)) suggest that the carbon chain of the organic species is oriented parallel to the layers of clay minerals. The infrared vibrational spectra are dominated by the inorganic structure bands; however the bands between 1800 and 1400 cm-1 related to the functional groups of the amino acid allow to infer about the protonation degree in the hybrid material. The Brönsted acidity generated by the polarization of water molecules associated with the clay was observed for montmorillonite samples used in this study. Materials prepared in suspensions in which the pH value was greater than the value of the first acid constant (pKa1) show bands assigned to the C=O stretching of protonated carboxylate group. Raman spectra were obtained only for the synthetic clay, since the natural ones luminesce. Raman spectrum of L-carnosine immobilized on Laponita indicates the presence of mostly zwitterionic species; the displacement of bands assigned to amide and carboxylic groups of the dipeptide to the lower energy region suggests the formation of hydrogen bonds with the Laponita silanol groups. The results of thermogravimetric analyses coupled to mass spectrometry of hybrid materials are different from those observed for the free amino acids. The onset temperature of the organic species decomposition is practically unmodified after the immobilization on clays, but thermal processes are postponed up to higher temperature, revealing the inorganic structure influence on the amino acids thermal decomposition. Data on the carbon and water amounts in the samples were used to calculate the concentration of amino acids in the hybrid materials (mass of amino acid / 100 grams of material). The highest concentrations of amino acid (between six and eight percent) was observed for Cloisite and Veegum HS samples, isolated under conditions in which the electrostatic interaction between the layers and the positively charged amino acids are predominant. Under the experimental conditions employed in this study no saturation of clay with amino acids was observed, i.e. the layer charges were not completely neutralized by the organic ions.

Os argilominerais são empregados na área farmacêutica e cosmética tanto como excipientes quanto ingredientes ativos. Esses compostos inorgânicos são inertes quimicamente, apresentam estruturas definidas e alta estabilidade térmica, o que contribui para o uso nessas áreas. Atualmente a indústria farmacêutica busca modificações no sistema de entrega de drogas (melhorias no tempo, local e taxa de liberação), objetivando um aumento na estabilidade das drogas e a prevenção e diminuição de efeitos colaterais. Nesse sentido, surge a necessidade de desenvolver novas formulações farmacêuticas, novos métodos de preparação e novos materiais. Considerando o fato dos argilominerais incorporarem espécies diversas entre suas lamelas, é interessante explorar a possibilidade de uso dessas matrizes inorgânicas como carregadores de espécies bioativas. O principal objetivo do presente trabalho foi preparar e caracterizar argilas de uso farmacêutico e/ou cosmético intercaladas com espécies que apresentam potencial terapêutico. Para tanto, usou-se duas argilas esmectitas naturais do tipo montmorilonita (Cloisita Sódica e Veegum HS) e uma esmectita sintética do tipo hectorita (Laponita RD). Os aminoácidos L-lisina, L-arginina e L-ornitina, e o dipeptídeo L-carnosina foram imobilizados em argilas catiônicas, por meio de reação de troca iônica. Na preparação dos materiais híbridos, alguns parâmetros experimentais foram avaliados: concentração hidrogeniônica (pH) da suspensão de reação, proporção argila/aminoácido e tempo de reação. As argilas precursoras e os materiais híbridos obtidos foram caracterizados por difratometria de raios X, espectroscopia vibracional na região do infravermelho e Raman, análise termogravimétrica acoplada à espectrometria de massas e análise química de carbono. Os valores de distância interlamelar (d(001)) dos materiais sugerem que a cadeia carbônica das espécies orgânicas se orienta paralelamente em relação às lamelas de baixa densidade de carga dos argilominerais. Nos espectros vibracionais na região do infravermelho há predominância das bandas características da estrutura inorgânica, mas as bandas entre 1800 e 1400 cm-1 relativas aos grupos funcionais do aminoácido permitem inferir sobre o seu grau de protonação no material híbrido. A acidez de Brönsted gerada pela polarização das moléculas de água associadas à argila foi observada para as montmorilonitas empregadas neste estudo. Amostras preparadas em suspensões nas quais o valor do pH era maior que o valor da primeira constante ácida (pKa1) dos aminoácidos apresentam bandas atribuídas ao estiramento C=O de grupo carboxilato protonado. Os espectros Raman foram obtidos apenas para a argila sintética, uma vez que as naturais apresentam luminescência. O espectro Raman da L-carnosina imobilizada em Laponita indica a presença preponderante da espécie zwitteriônica; o deslocamento das bandas atribuídas aos grupos amida e carboxílico do dipeptídeo para região de menor energia sugere a formação de ligações de hidrogênio com os grupos silanol da Laponita. Os resultados de análise termogravimétrica acoplada à espectrometria de massas dos materiais híbridos são distintos daqueles observados para os aminoácidos livres. A temperatura de início de decomposição das espécies orgânicas não é praticamente modificada após imobilização nas argilas, mas os processos térmicos se estendem até regiões de maior temperatura, evidenciando a influência da estrutura inorgânica sobre a decomposição térmica dos aminoácidos. Através dos dados de quantidade de carbono e de água nas amostras, calculou-se a concentração de aminoácidos nos materiais híbridos (massa de aminoácido / 100 gramas de material). As maiores concentrações de aminoácido (entre seis e oito por cento) foram observadas para as amostras de Cloisita e Veegum HS, isoladas em condições nas quais predomina a interação eletrostática entre as lamelas e os aminoácidos com carga positiva. Nas condições experimentais empregadas neste trabalho não foi observada a saturação das argilas com os aminoácidos, ou seja, as cargas das lamelas não foram totalmente neutralizadas pelos íons orgânicos. / Clay minerals are used as excipients or active ingredients in the pharmaceutical and cosmetic fields. These inorganic compounds are chemically inert, have defined structures and high thermal stability, which make them useful for these areas. Currently the pharmaceutical industry seeks modifications in the drug delivery systems (improvements in the time, place and rate of release), aiming an increase in the stability of the drugs and also the prevention and reduction of side effects. In this way, it is a need to develop new pharmaceutical formulations, new preparation methods and new materials. Considering the fact that clay minerals incorporate various species between their layers, it is interesting to explore the possibility of using these inorganic matrices as carriers of bioactive species. The main aim of this work was to prepare and characterize clays of pharmaceutical and/or cosmetic usage intercalated with species of therapeutic potential. Two natural smectite clays of montmorillonite type (Sodium Cloisite and Veegum HS) and one synthetic smectite of hectorite type (Laponita RD) were employed. The amino acids L-lysine, L-arginine and L-ornithine, and the L-carnosine dipeptide were immobilized on cationic clays by ion exchange reaction. Some experimental parameters were evaluated in the preparation of hybrid materials: hydrogen ion concentration (pH) of reaction suspension, clay/amino acid proportion and reaction time. Pristine clays and hybrid materials were characterized by X-ray diffraction, infrared and Raman vibrational spectroscopies, thermogravimetric analyses coupled to mass spectrometry and chemical analysis of carbon. The materials values of interlayer distance (d(001)) suggest that the carbon chain of the organic species is oriented parallel to the layers of clay minerals. The infrared vibrational spectra are dominated by the inorganic structure bands; however the bands between 1800 and 1400 cm-1 related to the functional groups of the amino acid allow to infer about the protonation degree in the hybrid material. The Brönsted acidity generated by the polarization of water molecules associated with the clay was observed for montmorillonite samples used in this study. Materials prepared in suspensions in which the pH value was greater than the value of the first acid constant (pKa1) show bands assigned to the C=O stretching of protonated carboxylate group. Raman spectra were obtained only for the synthetic clay, since the natural ones luminesce. Raman spectrum of L-carnosine immobilized on Laponita indicates the presence of mostly zwitterionic species; the displacement of bands assigned to amide and carboxylic groups of the dipeptide to the lower energy region suggests the formation of hydrogen bonds with the Laponita silanol groups. The results of thermogravimetric analyses coupled to mass spectrometry of hybrid materials are different from those observed for the free amino acids. The onset temperature of the organic species decomposition is practically unmodified after the immobilization on clays, but thermal processes are postponed up to higher temperature, revealing the inorganic structure influence on the amino acids thermal decomposition. Data on the carbon and water amounts in the samples were used to calculate the concentration of amino acids in the hybrid materials (mass of amino acid / 100 grams of material). The highest concentrations of amino acid (between six and eight percent) was observed for Cloisite and Veegum HS samples, isolated under conditions in which the electrostatic interaction between the layers and the positively charged amino acids are predominant. Under the experimental conditions employed in this study no saturation of clay with amino acids was observed, i.e. the layer charges were not completely neutralized by the organic ions.

Detailed studies are presented of thin films containing a polycation, a nonlinear optically (NLO) active chromophore, and a synthetic hectorite that self-assemble into the noncentrosymmetric structure required for second order nonlinear optical responses. UV/Vis spectroscopy and ellipsometry were used as probes to monitor film growth for upto 25 deposition cycles. Exceptionally homogeneous films were obtained with regular film growth for up to the 25 cycles deposited. ISAM films self-assemble from polyelectrolyte solutions due to coulombic interactions between a charged substrate and the charged polymer in solution. Charges accumulating at the surface restrict further growth due to charge overcompensation at the surface. The entire process occurs relatively quickly as compared to other competing assembly techniques such as Langmuir-Blodgett assembly and covalent self-assembly. Previous studies indicated that second harmonic signal diminishes after the deposition of the first few bilayers. This is potentially due to adjacent layer interpenetration, which becomes prominent moving further away from the hard substrate interface. Laponite RD, a synthetic hectorite was introduced in the films in an effort to minimize interpenetration of adjacent bilayers and hence maintain chromophore orientation in every bilayer of the ISAM film. The film was deposited in quadlayers that have the following sequence: Polycation–Laponite–Polycation–Chromophore. This study is unique in its approach as it investigates the possible implications of film interpenetration on the NLO-activity of ISAM films that can be easily fabricated. It also shows the effects of different interfaces on the NLO-activities of the films. We have investigated the effect of changing the polycation from poly(allylamine hydrochloride) (PAH) and poly(diallyldimethylammonium chloride) (PDDA) and the solution pH to see how these variables affect the growth and NLO properties of ISAM films. At lower pH values (specify relevant range of values), for both polycations, intrachain and interchain repulsion is strong due to little electrostatic screening. This results in polycation deposition in relatively thin, train-like layers. At higher pH levels (specify relevant range of values here) the electrostatic screening is greater due to a higher effective ionic strength. At these conditions, intrachain and interchain repulsion is reduced and so the polymers adsorb to form thicker layers with more loops and tails than for the case at lower pH. This also results in a higher density of the chromophore in the film. Extremely smooth surfaces of Laponite RD in film were obtained as confirmed by AFM imaging on glass. Regular quadlayer growth monitored by UV/Vis spectroscopy and ellipsometry was observed for up to 25 quadlayers. Second harmonic generation (SHG) signal was not conclusively affected by the presence of laponite as the decrease of signal was seen after the first few layers in the laponite containing films. This decrease was however was not as sharp in the films containing laponite as in the films that did not contain laponite. It was also noted that the SHG was not so much affected by the number of layers deposited but more so by the distance of the chromophore layer from the hard glass interface. This study thus brings to light the very important effect of the glass interface on the NLO-activity of these films. / Master of Science

Les approches macroscopiques (cinétique chimique) et microscopiques (spectroscopie EXAFS polarisée) ont été couplées dans le but de caractériser les mécanismes moléculaires de fixation de cations divalents (Co, Zn) sur l' hectorite, une smectite magnésienne, et sur le quartz. À pH = 6,5, haute force ionique, et pour un rapport Zn/hectoritc de - 50 umol/g, une adsorption spécifique de Co et Zn a lieu. Cette adsorption n' atteint pas l'équilibre avant plusieurs heures, et coïncide avec une libération initiale accrue de protons et de Mg en solution, puis une inhibition à long terme (t >= 48 h) de la cinétique de dissolution de l' hectorite. Co et Zn adsorbés forment des complexes de surface mononucléaires en continuité structurale de la couche octaédrique des feuillets d' hectorite. À basse force ionique, Co et Zn sont initialement adsorbés par échange cationique. Cette réaction atteint l'équilibre en moins de 5 min. Ces cations forment initialement des complexes de sphère externe sur les sites d'échange, puis ils migrent progressivement vers les sites de bordure des feuillets, où ils forment des complexes de surface similaires à ceux formés à haute force ionique. Le mécanisme et l'amplitude de l'adsorption de Zn sur l'hectorite à pH 7,3, à haute force ionique et pour un rapport Zn/hectorite de 1480 umol/g, dépend de la concentration en silice dissoute [Si) . La quantité de Zn adsorbé est limitée pour [Si) ~ 30-60 umoI/L, et Zn forme des polymères de petite taille (2-3 octaèdres) en continuité structurale de la couche octaédrique de l'hectorite. La quantité de Zn adsorbé est beaucoup plus importante pour [Si) ~ 540 umoI/L; cette adsorption est corrélée à une adsorption de Si, et correspond à la nucléation de phyllosilicates TOT zincifères en épitaxie dans le plan ab des feuillets. Une analyse approfondie de spectres EXAFS de Co adsorbé sur le quartz révèle que cet élément polymérise sous forme de couches d'octaèdres liées à des couches de tétraèdres de Si, pour former des phyllosilicates cobaltifères. Le mécanisme de cette néoformation est discuté.

Las esmectitas como hectorita o saponita, son silicatos laminares. Tienen múltiples aplicaciones (catálisis, nanocomposites, adsorbentes) e interesa tener un material reproducible y sin impurezas. Los métodos convencionales de síntesis comportan tratamientos largos o a altas temperaturas. La introducción del microondas puede disminuir ambos. El objetivo de esta tesis es estudiar la síntesis de hectorita y saponita con microondas y su aplicación como soportes catalíticos de Ni en la hidrogenación de óxido de estireno para la obtención de 2-feniletanol (componente principal de la esencia de rosas) y en la preparación de composites con poliuretano. Se obtienen hectoritas y saponitas reproducibles. Cuando se emplean como soportes de catalizadores de Ni se obtienen conversión y selectividad total hacia el 2-feniletanol. Cuando se utilizan las arcillas obtenidas en preparación de composites sus propiedades son comparables a los de la bibliografía. / Smectites like hectorite or saponite, are phyllosilicates. They can be applied for many purposes (catalysis, nanocomposites, adsorbents) but a reproducible, pure material is necessary. Classical methods of synthesis involve long synthesis times at high temperatures. The use of microwaves can be an interesting alternative. The scope of this thesis is to study the synthesis of hectorites and saponites with microwaves and their application as supports of Ni catalysts in the hydrogenation of styrene oxide to obtain 2-phenylethanol (main component of rose oil) and in the preparation of composites with polyurethane. We obtained reproducible hectorites and saponites. When used as supports of Ni catalysts we obtained total conversion and selectivity to 2-phenyethanol. When obtained clays were used in the preparation of polyurethane composites, their properties were comparables to those of the bibliography