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Organic-inorganic metal halides represent a versatile platform for optoelectronic applications such as solar cells, LEDs, and photodetectors due to their tunable structures and properties. The ability to achieve broadband white-light emission through exciton self-trapping, tunable by controlling dimensionality with organic-metal halide combinations, makes them particularly exciting for light emission applications. This study explores a 1D cadmium halide hybrid system with the luminescent A-site ion, 1,2-bis(pyridine)butane, to achieve broadband white light emission. Further, this study investigates halide replacement effects, structural distortions, and dopant influences on the emission characteristics to achieve enhanced performance. Additionally, the synthesis and characterization of Mn and Sb-based metal halides using the same luminescent A-site ion are discussed to highlight their potential for advancing optoelectronic applications. Finally, this study demonstrates the importance of the space charge limited current (SCLC) method in studying the charge carrier density and mobilities using 1D copper halides.

L’accroissement de l’espérance de vie s’accompagne d’une détérioration de l’état de santé général des seniors et d’une recrudescence des maladies chroniques. Parmi les manifestations de la sénescence, l’atteinte de l’appareil locomoteur est particulièrement invalidante et accélère considérablement l’entrée en dépendance. C’est également le cas chez les plus jeunes lors d’atteintes traumatiques ou pathologiques. Ainsi, au niveau mondial 2,2 millions de greffes osseuses sont pratiquées chaque année, mais le taux de complications post-opératoires demeure élevé et est estimé à 15 % des interventions. Ces faits dessinent les contours d’un enjeu sociétal majeur ; les matériaux d’origine animale posent des problèmes d’histocompatibilité, de pathogénicité et donc de rejet. C’est pourquoi les efforts de recherche ciblent prioritairement le développement de biomatériaux synthétiques aptes à promouvoir la régénération osseuse. Actuellement les principaux substituts osseux sur le marché sont les « céramiques » bioactives (phosphates de calcium, verres bioactifs) qui présentent comme caractéristiques d’être biocompatibles, de se lier spontanément aux tissus osseux, de promouvoir l’adhésion des cellules osseuses et enfin d’être biorésorbables. Cependant, malgré cet ensemble de caractéristiques très satisfaisantes, la fragilité de ces matériaux en limite les applications. Pour pallier ce défaut, une solution ingénieuse est de s’inspirer de la structure particulière du tissu osseux. Celle-ci mêle intimement une phase inorganique, le minéral osseux constitué de cristaux d’apatite (phosphate de calcium résorbable), à une phase organique qui est majoritairement du collagène. De manière remarquable, une telle structure associe la rigidité de la partie inorganique à la ténacité des fibres de collagène. Pour obtenir des implants aux propriétés mécaniques proches du tissu osseux, la stratégie consiste donc à combiner céramiques bioactives et matière organique. À cette fin, l’équipe Biomatériaux du Laboratoire de Physique de Clermont (LPC) a récemment mis au point un procédé innovant qui permet la synthèse de matrices tridimensionnelles d’hybrides organique-inorganique à base de verre bioactif et de polymère biocompatible aux caractéristiques variées. Dans la continuité des travaux, il était alors question d’exploiter ce procédé afin de développer un substitut osseux hybride aux propriétés optimisées. Il s’agissait tout d’abord de sélectionner le polymère le plus adéquat pour la régénération osseuse, qui s’est avéré être le polycaprolactone, puis d’optimiser la synthèse (notamment la source de calcium), la structure macroporeuse et la proportion organique-inorganique. Le matériau hybride résultant a ensuite été dopé en éléments thérapeutiques à faible dose (< 5 % de la masse totale) avec des ions strontium ou des nutriments tels que la fisétine et l’hydroxytyrosol qui possèdent un effet ostéogénique. Les mousses hybrides ainsi développées ont finalement été caractérisées in vitro afin de déterminer leurs propriétés physico-chimiques et biologiques, et in vivo afin d’évaluer leur performance. Après 3 mois d’implantation dans un défaut critique de la calvaria de souris, les résultats démontrent le potentiel de ce substitut osseux: comparé au matériau commercial de référence (os bovin traité) qui conduit à une reconstruction osseuse de 16% (± 5%), l’hybride permet une reconstruction allant de 32% (± 3%) lorsqu’il n’est pas dopé, jusqu’à 55% (± 7%) voire 58% (± 7%) lorsqu’il est dopé respectivement en fisétine ou en strontium. Ces travaux de thèse laissent entrevoir des perspectives prometteuses telles que l’association des dopants et l’impression 3D des mousses hybrides polycaprolactone-verre bioactif. / The increase in life expectancy results in the decline of seniors’ health conditions and the resurgence of chronic diseases. Among the expressions of senescence, disorders of the musculoskeletal system are particularly disabling and considerably accelerate the state of dependency. This is also the case for young people who suffer from traumatic injuries or pathologic conditions. Thus, about 2.2 million bone grafts are performed worldwide every year. Yet, the level of postoperative complications remains high and is estimated at 15% of surgical operations. These facts outline a major societal concern: animal-based materials present a risk of histocompatibility issues and pathogenicity that may lead to implant failure. This is the reason why research efforts focus on the development of synthetic biomaterials capable of promoting bone regeneration. Currently, commercialised bone substitutes are mainly made of bioactive “ceramics” (calcium phosphates, bioactive glass) that are known to be biocompatible, to spontaneously bond to bone tissues, to promote bone cell adhesion and finally to be bioresorbable. However, despite these remarkable properties, the brittleness of these materials limits their applications. An ingenious solution to this brittleness can be learned from the particular structure of bone tissue. Bone tissue intimately blends an inorganic phase, the bone mineral, which is made of apatite crystals (resorbable calcium phosphates), with an organic phase that is mainly collagen. Such a structure associates the stiffness of the inorganic part with the toughness of collagen fibres. Therefore, in order to obtain implants with mechanical properties similar to that of bone, the strategy consists in combining bioactive ceramics with organic matter. To this end, the Biomatériaux team from the Laboratoire de Physique de Clermont (LPC) recently developed an innovative process that allows the synthesis of tridimensional organic-inorganic hybrids comprised of bioactive glass and biocompatible polymer. The objective of the thesis was to exploit this process in order to develop a hybrid bone substitute with optimal properties. First of all, polycaprolactone was selected as the polymer, especially because of its adequate degradation rate for long-term applications such as bone regeneration. Then, the synthesis process was improved (in particular, the calcium source was changed), the macroporous structure was optimised and the organic-inorganic ratio was chosen. Afterwards, elements that are known to induce an osteogenic effect were incorporated in the hybrid at low doses (< 5% of total weight): an inorganic doping was performed using strontium ions and an organic doping was performed using nutrients such as fisetin or hydroxytyrosol. The resultant hybrid scaffolds were eventually characterised in vitro in order to determine their physicochemical and biological properties and in vivo in order to evaluate their performance. After 3 months of implantation in a mouse calvarial critical defect, results demonstrate the potential of this bone substitute: compared to the reference commercial material (treated bovine bone) that leads to a bone reconstruction of 16% (± 5%), the hybrid allows a reconstruction going from 32% (± 3%) when it is not doped, to 55% (± 7%) and even 58% (± 7%) when it is doped respectively with fisetin or strontium. This thesis paves the way to promising perspectives like the association of doping agents and the 3D printing of polycaprolactone-bioactive glass hybrid scaffolds.

A versatilidade das espumas poliuretanas permite sua aplicação em inúmeros setores industriais, devido à possibilidade de se obter diferentes conjuntos de propriedades apenas alterando sua formulação básica. Um tipo recorrente de alteração é a incorporação de diferentes tipos de fibras em matrizes de poliuretano, vastamente estudada com o objetivo de gerar materiais compósitos com melhores propriedades mecânicas do que a matriz original. Inúmeros autores reportaram a utilização de celulose cristalina como uma alternativa renovável aos agentes de reforço e revelaram que a celulose utilizada como aditivo em matrizes poliméricas afetou as propriedades mecânicas da matriz original e, em menor escala, exerceu influência sobre a estabilidade térmica do compósito. O presente trabalho dedicou-se a isolar a celulose cristalina contida nas fibras de bananeira mediante tratamento com ácido acético concentrado. Os tratamentos químicos são necessários para modificar a superfície do material e melhorar a adesão do agente de reforço à matriz. Tendo em vista os resultados associados à estabilidade térmica dos compósitos de poliuretano reforçados com celulose, buscou-se sintetizar materiais híbridos de celulose e MgO.nH2O. Foi observado que, mesmo em pequenas quantidades, a presença do óxido hidratado de magnésio afetou significativamente a estabilidade térmica do HB 98:2. Estudos térmicos indicam que os materiais compósitos estudados apresentaram comportamento semelhante ao da matriz PU. Estudos das propriedades compressivas dos materiais poliméricos gerados mostraram que a incorporação do HB 98:2 ao PU afetou positivamente as propriedades mecânicas do material, sendo que o compósito PU + 1 HB 98:2 apresentou desempenho mecânico superior ao da matriz pura. / The versatility of polyurethanes foams allows its application in numerous industries because of the possibility of obtaining different sets of properties just by changing its basic formulation. A recurrent type of modification is the incorporation of different types of fibers in polyurethane matrices widely studied with the objective of generating composite materials with better mechanical properties than the original matrix. Numerous authors have reported the use of crystalline cellulose as a renewable alternative to fillers and showed that the cellulose used as additive in polymer matrices affect the mechanical properties of the original matrix and, to a lesser extent, influence upon thermal stability of the composite. This work was dedicated to isolate the crystalline cellulose contained in banana fibers by treatment with concentrated acetic acid. The chemical treatments are needed to modify the surface of the material and improve adhesion of the filler to the matrix. In view of the results associated with the thermal stability of the composite polyurethane reinforced with cellulose, sought to synthesize hybrid materials cellulose and MgO.nH2O. It has been observed that even in small quantities, the presence of hydrated magnesium oxide significantly affect the thermal stability of HB 98: 2. thermal studies indicate that the studied composites showed similar behavior to the PU matrix. Studies of the compressive properties of polymeric materials generated showed that the incorporation of HB 98: 2 to PU positively affect the mechanical properties of the material, and the composite PU + HB 98 1: 2 had mechanical performance superior to that of pure matrix.

A intercalação de espécies de interesse biológico e terapêutico em Hidróxidos Duplos Lamelares (HDLs) vem se mostrando uma estratégia interessante para a obtenção de sistemas de armazenamento ou carregadores de drogas. No presente trabalho foram investigadas rotas sintéticas e parâmetros experimentais para a intercalação dos ânions derivados dos fármacos ácido mefenâmico e piroxicam em HDL de Mg2+ e Al3+. Os sólidos foram caracterizados por difratometria de raios X, análises elementar e térmica, microscopia eletrônica de varredura e espectroscopia no infravermelho e Raman. Os difratogramas de raios X dos materiais híbridos HDL-mefenamato isolados por co-precipitação (pH=9-9,5) mostram, além de fase do tipo HDL, alguns picos finos e de baixa intensidade que podem estar relacionados com a presença de um sal de mefenamato. Os melhores resultados foram obtidos empregando uma relação molar ânion/Al3+ =1. Nos processos de reconstituição e troca iônica, os picos finos não são observados. Os espectros vibracionais mostram que o ácido mefenâmico está na forma desprotonada e intacto. Os ânions mefenamato se arranjam em uma bicamada no espaço interlamelar (d003 ~21-22 Å). Os híbridos HDL-piroxicamato obtidos por co-precipitação são constituídos de pelo menos duas fases. À medida que a razão ânion/Al3+ diminui, observa-se o aumento na formação de fase HDL. / Intercalation of biological and therapeutical species into Layered Double Hydroxides (LDHs) has been shown an interesting strategy to get drug storage or drug carrier systems. In this work it were investigated synthetic routes and experimental parameters for intercalation of anions derived from mefenamic acid and piroxicam drugs into LDH of Mg2+ and Al3+ composition. The isolated solids were characterized by X-ray diffractometry, elemental and thermal analysis, scanning electron microscopy and infrared and Raman spectroscopies. Besides LDH phase, XRD patterns of LDH-mefenamate hybrid materials isolated by coprecipitation (pH=9-9.5) show some narrow and low intensity peaks that can be related to a mefenamate salt phase. Improved data were obtained using an anion/Al3+ molar ratio equal 1. When employing reconstruction and ion exchange methods, narrow peaks are no observed. Vibrational spectra indicate that mefenamic acid is deprotonated and integral between the layers. Guest anions are arranged in a bylayer in the interlayer space (d003 ~21-22 Å). LDH-piroxicamate hybrid materials obtained by coprecipitation are constituted by at least two phases. An increase in LDH phase formation it is observed when the molar ratio anion/Al3+ decreases.

Atualmente com o advento da nanociência e nanotecnologia, as nanopartículas magnéticas têm encontrado inúmeras aplicações nos campos da biomedicina, diagnóstico, biologia molecular, bioquímica, catálise, etc. As nanopartículas magnéticas funcionalizadas são constituídas de um núcleo magnético, envolvido por uma camada polimérica com sítios ativos, que podem ancorar metais ou compostos orgânicos seletivos. Estas nanopartículas são consideradas materiais híbridos orgânico-inorgânicos de grande interesse em aplicações comerciais devido à particularidade das propriedades obtidas. Entre as aplicações importantes podemos citar: tratamento por magnetohipertermia, carregadores de fármacos para áreas específicas do corpo, seleção de moléculas específicas, biossensores, melhoria da qualidade de imagens por RMN, etc. O trabalho foi desenvolvido em duas partes: 1) a síntese do núcleo constituído de nanopartículas superparamagnéticas de ferrita de cobalto e, 2) o recobrimento do núcleo por um polímero bifuncional o 3-aminopropiltrietoxissilano. Os parâmetros estudados na primeira parte da pesquisa foram: pH, concentração molar da base, tipo de base, ordem de adição dos reagentes, modo de adição dos reagentes, velocidade de agitação, concentração inicial dos metais, fração molar de cobalto e tratamento térmico. Na segunda parte estudou-se: o pH, a temperatura, o catalisador, a concentração do catalisador, o tempo de reação, a relação H2O/silano, o tipo de meio, o agente umectante e a eficiência do recobrimento em relação ao pH. Os produtos obtidos foram caracterizados pelas técnicas de difratometria de raios-X (DRX), microscopia eletrônica de transmissão (MET), microscopia eletrônica de varredura (MEV), espectroscopia de energia dispersiva (EDS), espectroscopia de emissão atômica (ICP-AES), espectroscopia por infravermelho (FTIR), análises termogravimétricas (TGA/DTGA), calorimetria exploratória diferencial (DSC) e curvas de magnetização (MAV) / Nowadays with the appear of nanoscience and nanotechnology, magnetic nanoparticles have been finding a variety of applications in the fields of biomedicine, diagnosis, molecular biology, biochemistry, catalysis, etc. The magnetic functionalized nanoparticles are constituted of a magnetic nucleus, involved by a polymeric layer with active sites, which ones could anchor metals or selective organic compounds. These nanoparticles are considered organic-inorganic hybrid materials and have great interest as materials for commercial applications due to the specific properties. Among the important applications it can be mentioned: magnetohyperthermia treatment, drugs delivery in specific local of the body, molecular recognition, biossensors, enhancement of nuclear magnetic ressonance images quality, etc. This work was developed in two parts: 1) the synthesis of the nucleus composed by superparamagnetic nanoparticles of cobalt ferrite and, 2) the recovering of nucleus by a polymeric bifunctional 3-aminepropyltriethoxysilane. The parameters studied in the first part of the research were: pH, hydroxide molar concentration, hydroxide type, reagent order of addition, reagent way of addition, speed of shake, metals initial concentrations, molar fraction of cobalt and thermal treatment. In the second part it was studied: pH, temperature, catalyst type, catalyst concentration, time of reaction, relation ratios of H2O/silane, type of medium and the efficiency of the recovering regarding to pH. The products obtained were characterized using the following techniques X-ray powder diffraction (DRX), transmission electronic microscopy (MET), scanning electronic microscopy (MEV), spectroscopy of scatterbrained energy spectroscopy (DES), atomic emission spectroscopy (ICP-AES), themogravimetric analysis (TGA/DTGA), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and magnetization curves (VSM)

Ce travail de thèse présente une méthode de synthèse par le procédé sol-gel pour la préparation de matériaux hybrides organiques-inorganiques (OIH) basés sur le mélange de deux polyéthers différents, le poly (oxyde d´éthylène) (PEO) et le poly (oxyde de propylène) (PPO) liées de façon covalente avec l´agent de réticulation ureasil (U). Dû aux différents sites actifs présents dans la structure du matériau OIH, plusieurs cations métalliques peuvent être introduits dans la matrice hybride par complexation soit avec l´oxygène de type éther, soit avec l´oxygène du type carbonyle. Suite à ce constat, différentes matrices hybrides ont été synthétisées en introduisant des ions Eu3+ ou Li+ afin de conférer aux matériaux des propriétés optiques ou électriques. La compréhension des propriétés structurales et thermiques des différents polymères, l´ajout de différents cations Eu3+/Li+, et l'effet du plastifiant (PPO2000) dans la mélange hybride U-xPEO1900:/U-1-xPPO2000 (ratio de PPO2000 dans la mélange, x = 0.2, 0.5 et 0.8), ont été étudiés par DSC et SAXS. Les résultats de DSC ont révélé une unique température de transition vitreuse (Tg) pour tous les matériaux étudiés. L´ajout des ions Eu3+ dans le matrice n´a pas causé de variations dans les valeurs de Tg tandis que l´insertion de cations Li+ a provoqué une augmentation dans les valeurs de Tg, indiquant l´existence d’interactions entre les cations Li+ et la phase polymérique du matériau OIH. Les courbes de calorimètrie de l´U-PEO1900 ont aussi révélé la présence d´une pic endothermique à 25 °C, associé à la fusion des domaines cristallins du PEO1900. La présence d´un deuxième maximum dans les courbes de diffusion des rayons X à petits angles (SAXS) a confirmé l’existence de la structure semi-cristalline du PEO1900 dans une région de température entre -100 °C < T < Tf. Tous les échantillons, non-dopés et dopés avec les ions Li+ et Eu3+, ont montré un pic de corrélation indiquant que la nano-structure de la matrice hybride n´est pas affecté par le dopage avec les cations métalliques. Les études par Spectroscopie Infrarouge à Transformée de Fourier (FTIR) et par spectroscopie Raman ont confirmé l´interaction des ions Eu3+ avec l´oxygène du type carbonyle présent dans les groupes urées de la matrice hybride, et des ions Li+ avec l´oxygène du type éther. La photodégradation accélérée a révélé une perte des performances de la photo-luminescence (PL) associée à des changements dans la coordination des ions Eu3+ avec la matrice hybride. La photodégradation induit la formation de photo-produits venant de la β-scission du macroradical formé dans la portion organique de la matrice hybride. La β-scission peut-être responsable pour la diminution de la PL du matériau dû la perte de l´efficacité de l´effet antenne du ligand organique pour le centre luminescent. La transition dans la région visible du rouge vers le bleu avec la photodégradation qualifie ces matériaux de bons candidats pour l'application comme capteurs et marqueurs optiques. La conduction ionique des matrices hybrides dopés avec Li+ a été évaluée par Spectroscopie d´Impédance en fonction de la température et les résultats ont révélé des corrélations entre la superstructure lamellaire du PEO1900 et le mécanisme de conduction. L´addition d´un plastifiant, le PPO2000, a permis l´augmentation de la conductivité ionique dans une région de température entre -100 °C < T < 10 °C dû à l´augmentation de la portion amorphe utilisée comme chemin de transport ionique efficace dans le mélange polymère hybride U-xPEO1900/U-1-xPPO2000. / In this PhD thesis a greener synthesis route via sol-gel reactions aiming to prepare multifunctional organic-inorganic hybrid (OIH) materials based on blending of two polyether amine end chains (i.e., Jeffamine® compounds) Poly(ethylene oxide) (PEO) and Poly(propylene oxide) (PPO) covalently bonded with an ureasil cross-linking agent (U) is reported. Due to the different polar oxygen sites present in this OIH material, several metallic cations can to be introduced into the OIH matrix via ether- or carbonyl-type oxygen. So, different OIH matrices containing Eu3+ or Li+ cations were synthetized to evaluate their potential as photoluminescent or ionic conductor material, respectively. The thermal and structural characteristics of the Eu3+ or Li+ – loaded OIH materials, as well as the plasticizer effect of PPO2000 at the U-xPPO2000:/U-1-xPEO1900, (PPO2000 fraction x = 0.2, 0.5 and 0.8) blends, were carried out by DSC and SAXS. DSC results revealed a unique glass transition temperature (Tg) for all the studied OIH materials. The addition of Eu3+ cations do not change the Tg values while the Li+ cations caused an increase in the values of Tg, due to the Li+ interaction with the polymeric phase of the material. The U-PEO1900 calorimetric curves also showed the presence of an endothermic peak at 25 °C associated to the fusion of the crystalline domains of PEO1900. The second maxima observed in the curves of small angle X-ray scattering (SAXS) confirmed the presence of the crystalline structure of PEO1900 in a temperature range of -100 < T < Tf. All the samples, undoped and Li+ or Eu3+ doped ones, showed a correlation peak indicating that the OIH nano-structure is not affected by the metallic cations doping. Analysis carried out by Fourier Transform InfraRed (FTIR) and Raman Spectroscopy confirmed the Eu3+ cations interaction via the oxygen carbonyl-type present in the urea groups of the hybrid matrix, and that of Li+ cations with the oxygen ether-type. The accelerate photo-degradation revealed a loss of the photo-luminescence (PL) efficiency due to the changes in the Eu3+ cations coordination with the hybrid matrix. The photo-degradation induces the formation of photo-products from the macro-radical β-scission formed in the organic fraction of the hybrid matrix. The β-scission can be responsible for the material PL decrease due to the drop in the antenna effect from organic ligand to luminescent center. The visible emission transition from red → blue with the photo-degradation qualify these materials as good candidates to be applied as sensors and optical markers. The ionic conduction of the Li+-loaded hybrid matrices was investigated by Impedance Spectroscopy as a function of the temperature. Results showed a correlation between the lamellar superstructure of the PEO1900 and the conducting process. The plasticizers addition (PPO2000) alloyed to improve the value of the ionic conductivity in the low temperature range, -100 °C < T < 10 °C due to the increase of the amorphous fraction used as effective ionic transport pathway in the U-xPEO1900/U-1-xPPO2000 polymeric hybrid blend.

No estudo de sistemas híbridos orgânico-inorgânico, o uso de materiais como polímeros conjugados e óxidos de metal de transição tem despertado grande interes- se. Em particular, destacam-se sistemas compostos de tiofenos e óxido de titânio, que encontram uma importante aplicação em células solares. Para um melhor entendimento da interação entre os dois sistemas, torna-se necessário conhecer a organização do polímero sobre o substrato inorgânico. Desse modo, investigamos neste trabalho a formação da interface entre oligômeros de tiofeno e a superfície (101) de TiO2-anatase utilizando um enfoque de multiformalismo, que inclui simulações de dinâmica molecular clássica, e uma combinação de cálculos de primeiros princípios segundo Hartree-Fock e Teoria do Funcional da Densidade (DFT) para a determinação de propriedades estruturais e eletrônicas. A deposição de oligômeros de tiofeno sobre TiO2, constituindo sistemas de milhares de átomos, foi simulada por meio de dinâmica molecular clássica. Como requisito do cálculo clássico para estes sistemas, realizamos a reparametrização do campo de forças Universal tanto para os oligômeros, cujas estruturas não são bem descritas pelos campos de força padrões, como para o cristal e a superfície de TiO2. Foi observada a formação de filmes desordenados e densos de quatertiofeno, com a presença de uma maioria de moléculas de orientação quase perpendicular em relação ao plano superficial. Na camada de interface também se encontram moléculas dispostas paralelamente ao substrato, aumentando o contato entre os sistemas orgânico e inorgânico. A deposição de oligômeros isolados de quatertiofeno e de hexatiofeno mostra ainda que as moléculas se dispõem paralelas na superfície, alinhadas segundo direções de periodicidade dos átomos da superfície. Estudamos desta forma as propriedades eletrônicas de um sistema composto de politiofeno sobre TiO2, com o polímero paralelo na superfície e disposto na direção preferencial, através de um formalismo ab initio DFT. Apesar do tratamento DFT apresentar problemas conhecidos quanto na definição do gap, o que é mais relevante ainda no nosso caso de sistemas híbridos, os resultados revelam um deslocamento do topo da banda de valência do material orgânico em relação ao inorgânico. Isto possibilita o aprisionamento de um buraco no polímero, condição necessária para o uso deste tipo de sistema em células fotovoltaicas. Verifica-se ainda o acoplamento entre átomos de enxofre do politiofeno e de oxigênio do TiO2 através da presença de um estado associado a uma densidade eletrônica que se estende do polímero na superfície. Nossos resultados indicam assim um bom acoplamento eletrônico da superfície (101) de TiO2-anatase com politiofenos. / In the study of organic-inorganic hybrid systems, the use of materials such as conjugated polymers and transition metal oxides has attracted great interest. In particular, it is worth mentioning systems composed by thiophenes and titanium oxide, which have an important application in solar cells. For a better understand- ing of the interaction between these systems, it is necessary to know the polymer organization over the inorganic substrate. Therefore, we investigated in this work the formation of the interface between thiophene oligomers and the (101) surface of TiO2-anatase by means of a multi-formalism approach, which includes classical molecular dynamics simulations, and a combination of ¯rst principles calculations based on Hartree-Fock and Density Functional Theory (DFT) for structural and electronic properties. The simulation of deposition of thiophene oligomers on TiO2, which demands systems with thousands of atoms, was performed by classical molecular dynamics. As a prerequisite for the classical calculation for these systems, we performed a re-parameterization of the Universal force ¯eld for the oligomers, whose structures are not well described by standard force ¯elds, and for the TiO2 bulk and surface. We observed the formation of disordered and dense quaterthiophene ¯lms, with presence of a majority of molecules oriented almost perpendicularly to the surface plane. In the ¯rst interfacial layer we ¯nd also molecules oriented parallel to the sub- strate, which increases the contact between the organic and the inorganic systems. The deposition of isolated quaterthiophene and sexithiophene oligomers resulted in molecules disposed parallel to the surface and aligned along directions of periodicity of the surface atoms. We therefore studied the electronic properties of a system composed of poly- thiophene on TiO2, with the polymer parallel to the surface and oriented along a preferential direction, by means of DFT formalism. Although DFT treatments present known problems in the de¯nition of the energy gap, even of more relevance in our case of hybrid systems, the results for the occupied states revealed a sizeable displacement of the top of the valence band of one system with respect to the other. The misalignment will prevent the passage of a hole from the polymer to the oxide, providing in this way the necessary condition for the use of this type of system in solar cells. It was also seen electronic coupling between sulfur atoms from polythio- phene, and oxygen atoms from TiO2 through the presence of a state associated with an electronic density extended from the polymer to the surface. Our results thus indicate there is good electronic coupling between the (101) surface of TiO2-anatase and polythiophenes.

A intercalação de espécies de interesse biológico e terapêutico em Hidróxidos Duplos Lamelares (HDLs) vem se mostrando uma estratégia interessante para a obtenção de sistemas de armazenamento ou carregadores de drogas. No presente trabalho foram investigadas rotas sintéticas e parâmetros experimentais para a intercalação dos ânions derivados dos fármacos ácido mefenâmico e piroxicam em HDL de Mg2+ e Al3+. Os sólidos foram caracterizados por difratometria de raios X, análises elementar e térmica, microscopia eletrônica de varredura e espectroscopia no infravermelho e Raman. Os difratogramas de raios X dos materiais híbridos HDL-mefenamato isolados por co-precipitação (pH=9-9,5) mostram, além de fase do tipo HDL, alguns picos finos e de baixa intensidade que podem estar relacionados com a presença de um sal de mefenamato. Os melhores resultados foram obtidos empregando uma relação molar ânion/Al3+ =1. Nos processos de reconstituição e troca iônica, os picos finos não são observados. Os espectros vibracionais mostram que o ácido mefenâmico está na forma desprotonada e intacto. Os ânions mefenamato se arranjam em uma bicamada no espaço interlamelar (d003 ~21-22 Å). Os híbridos HDL-piroxicamato obtidos por co-precipitação são constituídos de pelo menos duas fases. À medida que a razão ânion/Al3+ diminui, observa-se o aumento na formação de fase HDL. / Intercalation of biological and therapeutical species into Layered Double Hydroxides (LDHs) has been shown an interesting strategy to get drug storage or drug carrier systems. In this work it were investigated synthetic routes and experimental parameters for intercalation of anions derived from mefenamic acid and piroxicam drugs into LDH of Mg2+ and Al3+ composition. The isolated solids were characterized by X-ray diffractometry, elemental and thermal analysis, scanning electron microscopy and infrared and Raman spectroscopies. Besides LDH phase, XRD patterns of LDH-mefenamate hybrid materials isolated by coprecipitation (pH=9-9.5) show some narrow and low intensity peaks that can be related to a mefenamate salt phase. Improved data were obtained using an anion/Al3+ molar ratio equal 1. When employing reconstruction and ion exchange methods, narrow peaks are no observed. Vibrational spectra indicate that mefenamic acid is deprotonated and integral between the layers. Guest anions are arranged in a bylayer in the interlayer space (d003 ~21-22 Å). LDH-piroxicamate hybrid materials obtained by coprecipitation are constituted by at least two phases. An increase in LDH phase formation it is observed when the molar ratio anion/Al3+ decreases.

Dans le contexte énergétique actuel, la conception de panneaux photovoltaïques efficaces représente une des solutions pour pallier à la pénurie prochaine des énergies fossiles. Cependant, les phénomènes de dégradation de l’encapsulant, un des matériaux passifs du panneau, sont une des origines de la baisse de rendement des modules. L’objectif de ce travail de thèse a été de concevoir, caractériser et évaluer les différentes propriétés de nouveaux encapsulants hybrides organique-inorganique contenant des ressources renouvelables. Ainsi, trois matériaux ont été élaborés à partir d’alcool polyvinylique (PVA), de résines terpéniques et de charges minérales (silice ou argile (Bentonite)). Un premier matériau comprenant PVA, résine et silicates, dans lequel composantes organique et inorganique sont liées par des liaisons covalentes fortes (hybride de classe II), a conduit à des stabilités thermiques et photochimiques, et des propriétés optiques et barrières à la vapeur d’eau et à l’oxygène, similaires à celles des encapsulants actuels.L’introduction de nanoparticules de silice dans un mélange PVA/résine via des liaisons faibles a ensuite fourni un matériau hybride de classe I aux propriétés barrières à la vapeur d’eau satisfaisantes mais avec des transparences optiques insuffisantes pour une utilisation comme encapsulant, du fait de l’agrégation des nanoparticules. Enfin, malgré une transparence optique devant être encore optimisée, un matériau hybride de classe I constitué de PVA, de résine et de Bentonite a conduit à de bonnes propriétés thermiques, photochimiques, barrières à la vapeur d’eau et surtout d’excellentes propriétés barrières à l’oxygène, ce qui ouvre de nouvelles perspectives (emballage alimentaire…). / In the current energetic context, the design of efficient solar photovoltaic panels represents one of the solutions to overcome the coming fossil fuels shortage. However, degradation phenomena of the encapsulant, one of the passive materials of the panel, have been evidenced as one of the reasons of the performance decrease. The aim of this PhD research work was to design, characterize and assess the different properties of more environment-friendly new hybrid organic-inorganic encapsulants. In this way, three materials have been developed using polyvinyl alcohol (PVA), terpenic resins and mineral fillers (silica or clay(Bentonite)). A first material including PVA, resin and silicates, in which both organic and inorganic networksare linked through strong covalent bonds (class II hybrid material), led to thermal and photochemical stabilities, and water vapor and oxygen barriers properties similar to those of commercial encapsulants.Dispersion of silica nanoparticles into PVA/terpenic resin mixture through weak bond then provided a class Ihybrid material showing rather good water vapor barrier properties but optical transmittance too low to beused as an encapsulant, due to the aggregation of the nanoparticles. Finally, despite an optical transparency that should be optimized, a class I hybrid material made of PVA, resin and Bentonite showed promisingbehavior with good thermal, photochemical and water barrier properties and remarkable oxygen barrier properties, which opens up new prospects in the field of food packaging.