Luminóforos inorgânicos contendo Terras Raras (TR) apresentam um papel importante como detectores de radiação ionizante, aplicados em diagnósticos médicos por imagem, como radiologia e tomografia. A função dos luminóforos é transformar os fótons da radiação de alta energia absorvidos (raios X ou ?) em fótons de luz visível, promovendo melhor qualidade de imagem e, conseqüentemente menor tempo de exposição do paciente à radiação. Os luminóforos de TR consistem de uma matriz hospedeira onde estão presentes íons de TR como Lu, La, Y ou Gd e de um íon ativador (que emite luz na região visível do espectro) como Eu3+, Tb3+, Tm3+ ou Ce3+, por exemplo. Luminóforos contendo íons Ce3+ como ativador são alvo de várias pesquisas relacionadas com detecção de radiação ionizante, devido às rápidas transições 5 d ? 4 f (tempo de resposta de ~ 10 a 100 ns) e emissão de luz na região do azul ou verde, requisitos esperados para um eficiente luminóforo para tal aplicação. Este trabalho apresenta a preparação de luminóforos de TR, dopados com Ce3+ ou Tm3+, na forma de pó, por diferentes métodos de síntese, como os métodos de combustão e Pechini e também por processo sol-gel. Aluminatos de TR (Lu3Al5O12 e Y3Al5O12) dopados com cério ou túlio foram obtidos pela reação de combustão entre precursores nitrato com uréia ou glicina sob aquecimento, ou pela síntese de polímeros de ácido cítrico com etilenoglicol contendo íons TR e alumínio (método Pechini). Em ambos os métodos os compostos foram obtidos por calcinação a temperaturas baixas quando comparadas às dos métodos convencionais. Silicatos de TR (Gd2SiO5, Lu2SiO5 e Y2SiO5) dopados com cério ou túlio foram preparados pelo método sol-gel convencional, por reação entre tetraetóxisilano (TEOS), etanol, água e nitratos metálicos, sob catálise básica, e por um método sol-gel modificado utilizando um polímero precursor. Neste último procedimento, TEOS, etanol e água reagiram juntamente com um sal orgânico de TR, álcool polivinílico (PVA) e uréia como combustível, produzindo um gel. Posterior calcinação levou à formação do silicato. A caracterização dos compostos foi realizada por análises de difratometria de raios X pelo método do pó (DRX), microscopia de eletrônica de varredura (MEV) ou de transmissão (MET), EDX, excitação e emissão no UV-Vis e tempo de vida de luminescência. Para os aluminatos dopados com cério foram ainda realizados espectros de emissão sob excitação por raios X. Os métodos de síntese utilizados se mostraram eficientes para obtenção de luminóforos na forma de pó nanométrico, com exceção do método sol-gel modificado, pois para algumas amostras observou-se a formação de mistura de fases. Os compostos dopados com cério apresentaram excitação e emissão características desse íon na região do verde ou azul do espectro visível, dependendo da matriz, com tempos de vida menores que 100 ns. Já aqueles dopados com túlio apresentaram emissão característica do íon, na região do azul, porém com tempos de vida da ordem de microssegundos. / Rare Earth (RE) inorganic phosphors play an important role as ionizing radiation detectors when applied to medical imaging techniques like radiology and tomography. These phosphors is to convert the high energy radiation absorbed photons (X or ?-rays) into visible photons, leading to better quality images and reducing the time the patient is exposed to radiation. RE phosphors consist of a host lattice where RE ions such as Lu, La, Y, or Gd are present, as well as activator ions (which emit light in the visible range of the spectrum) such as Eu3+, Tb3+, Tm3+, or Ce3+. Cerium-doped phosphors have been the target of several researches related with ionizing radiation detection due to their 5d - 4 f fast transitions (decay time in the ~ 10 to 100 ns range) and due to the fact that they emit light in the blue or green region of the spectrum, which is required for to the efficient phosphors to be applied in the detection of X or ?-rays. This work presents the synthesis of RE phosphor powders doped with Ce3+ or Tm3+, through different synthetic methods: combustion, Pechini, and sol-gel. RE aluminates (Lu3Al5O12 and Y3Al5O12) doped with Ce or Tm were prepared by combustion reaction between nitrate precursors and urea or glycine under heating. They were also obtained via the synthesis of polymers using citric acid, ethileneglycol, RE3+ and Al3+ ions (Pechini method). In both cases, the compounds were obtained by calcination at lower temperatures than those used inconventional methods. RE silicates (Gd2SiO5, Lu2SiO5 e Y2SiO5) doped with Ce or Tm were synthesized by the conventional sol-gel method using tetraethoxisylane (TEOS), ethanol and water, under basic catalysis, and also by a modified sol-gel route that uses a polymeric precursor. In the latter one, TEOS, ethanol and water were reacted with an organic RE salt, polyvinyl alcohol (PVA), and urea was used as fuel, thus yielding a gel. After calcination, we observed silicate formation. Characterization of the compounds was performed by X-ray diffractometry (XRD ? powder method), scanning or transmission electron microscopy (SEM or TEM), energy dispersive X-ray (EDX), luminescence spectroscopy in the UV-Vis range and lifetime analyses. For the cerium doped aluminates, emission spectra under X-ray excitation were also obtained. The synthetic methods used here showed to be efficient for the preparation of nanometric phosphor powders except for the modified sol-gel route, because in this case formation of a mixture of phases was observed for some samples. The Ce-doped compounds exhibited excitation and emission features of this ion in either the green or blue region of the visible spectrum, depending on the matrix, with lifetime values lower than 100 ns. However, the Tm-doped compounds displayed the blue emission typical of Tm ions, but the lifetime values were in the range of microseconds.

Compósitos de Carbono Polimérico Vítreo/sílica foram preparados por carbonização de resinas fenólicas e sílica xerogel. A idéia por trás deste estudo é a obtenção de um eletrodo composto através da polimerização simultânea de oligômeros de fenol-formaldeído e monômeros de tetraetoxisilano ou viniltrietoxisilano formando uma rede de polímero híbrido utilizando a abordagem do método sol-gel, seguido de aquecimento controlado por pirólise até 1100 °C. A metodologia proposta permite obter vidro monolítico isotrópico e eletrodos compósitos de carbono/sílica com elevada quantidade de carbono (esses eletrodos são conhecidos também como compósitos vítreos cerâmicos e contém até 85% em massa de carbono e 15% em massa de sílica) com base em resinas termofixas fenol-formaldeído e sua aplicação como eletrodo de trabalho. A caracterização dos monólitos sintetizados foi efetuada por meio de análise térmica, microscopia electrônica de varredura, espectroscopia por energia dispersiva de raios-X, difração de raios-X do pó, espectroscopia Raman e infravermelho. As propriedades eletroquímicas foram avaliadas por voltametria cíclica. O mapeamento da energia dispersiva de raios-X indica que a sílica (presença confirmada pelos padrões de difração de raios-X) esta dispersa na matriz de carbono vítreo. Além disso, observou-se a presença de sílica (cristalitos de cristobalita) no compósito. Os eletrodos foram avaliados quanto à sua reatividade de transferência de elétrons em sistemas eletrólito aquoso com o ferroceno e [Fe(CN)6]3-/4-, assim como o seu comportamento em diferente eletrólito de suporte. / Polymeric glassy carbon/silica composites were prepared by carbonizing phenolic resins and silica xerogel. The idea behind this study is to obtain a composite electrode through simultaneous polymerization of phenol-formaldehyde oligomers and tetraethoxysilane or vinylltriethoxysilane monomers forming an interpenetrating hybrid polymer network using soft chemistry approach, followed by controlled heating up to 1100oC in an oxygen-free environment. The proposed methodology enables to obtain isotropic and monolithic glass-like carbon/silica composite electrodes with high carbon amount (the resultant glassy-ceramic composites consist of up to 85 mass% of glassy carbon and 15 mass% of silica) based on phenol-formaldehyde thermosetting resin, and their application as working electrode. The characterization of the as-synthesized monoliths was carried out by thermal analysis, scanning electron microscopy, X-ray dispersive energy spectroscopy, X-ray powder diffraction, infrared and Raman spectroscopies, and the electrochemical properties were evaluated by cyclic voltammetry. X-ray dispersive energy mapping indicates that the silica (presence confirmed by X-ray diffraction patterns) is dispersed in the glassy carbon matrix. In addition, it was shown the presence of silica phase (cristobalite) in the composite. The electrode were evaluated for their electron transfer reactivity with ferrocene and Fe(CN6)3-/4- systems in aqueous electrolyte, as well as their behavior in different support electrolyte.

A preparação de vitrocerâmicas transparentes a base de SiO2-ZrO2 dopado com íons Eu3+ e Er3+ através da metodologia sol-gel foi o objetivo desta dissertação. São apresentados resultados estruturais e óticos deste sistema, em função de temperatura, tempo e composição (variando-se a concentração de zircônia). Os sóis foram preparados em meio ácido e deixados em repouso até evaporação total do solvente, obtendo-se assim monolitos amorfos, os quais foram submetidos a tratamentos a 900, 1000 e 1100ºC durante 2, 4 e 8 horas visando eliminação de resíduos orgânicos, moléculas de água, grupos hidroxilas e densificação do material. O processo de densificação com os tratamentos leva a formação inicial da fase tetragonal de ZrO2. Foi observado o crescimento de nanopartículas de ZrO2 com dimensão dependente do tempo e temperatura de tratamento térmico, além da composição do nanocompósito. As nanopartículas obtidas apresentam tamanho que variam entre 3,1 a 5,5 nm, observadas por microscopia eletrônica de transmissão. A partir da adição de 20% de óxido de zircônio é possível observar uma mistura de fases entre tetragonal e monoclínica, resultado este evidenciado principalmente por espectroscopia Raman. Neste trabalho, o íon Eu3+ foi usado como sonda estrutural e um possível luminóforo na região do vermelho. Íons lantanídeos encontram-se parcialmente distribuídos na rede amorfa à base de sílica, apresentando um tempo de vida do 5D0 de 1,5 ms e em óxido de zircônio, com um tempo de vida de 2,7 ms. À medida que ocorre cristalização, aumenta-se a proporção de íons no óxido de zircônio, sugerindo que os íons lantanídeos preferencialmente encontram-se distribuídos em regiões ricas de ZrO2. Todas as amostras dopadas com íons Er3+ apresentam emissão no infravermelho próximo, na região da banda C utilizada em telecomunicações. A emissão do íon Er3+ em 1532 nm, atribuída à transição 4I13/2 4I15/2, apresentou uma largura a meia altura que variou entre 29 a 56 nm, dependendo da composição e do tratamento térmico realizado. O tempo de vida (1/e) do estado excitado 4I13/2 é de 5,3 ms a 6,5 ms dependendo do tratamento térmico. / The preparation of transparent glass-ceramic based on the SiO2-ZrO2 doped with Eu3+ and Er3+ ions by the sol-gel methodology was the aim of this work. The structural and optical properties of the systems as a function of the time and temperature of annealing and also zirconium concentration are presented. The sol was prepared in acid solution and left in rest until total evaporation solvent, to obtaining the amorphous monoliths. The follow, the growthing of ZrO2 nanoparticles were induced and by the Transmission Electron Microscopy sizes between 3.1 and 5.5 nm were observed to be dependent to the time and temperature of annealing. The densification from the annealing at 900, 1000 and 1100ºC initially takes the formation of the tetragonal phase of ZrO2, and after 20 mol% of zirconium oxide is observed a mixture of phases between the tetragonal and monoclinic phase, result this evidenced by Raman spectroscopy. In this work the Eu3+ ion was used as a structural and possible luminescent material in the red region, displaying a life time value between 1.4 - 2.3 ms, for samples contend 0.3 mol% of Eu3+. The life time values increases as a function of time and temperature of annealing due the increase of the crystallinity of material that decreases the sites number of Eu3+ ions on the system. The Er3+ ions emission assigned to 4I13/2 4I15/2 localized around 1532 nm, showed a full width half maximum between 29 and 56 nm. The lifetime measurements were realized for Er3+ ions. The larger values of lifetime obtained are correspondent to samples with less crystalinity. Samples annealed in less temperatures show 5.3 ms of lifetime while samples annealed in higher temperatures show 6.5 ms of lifetime.

Este trabalho mostra estudos das propriedades eletroquímicas do eletrodo de diamante dopado com boro (DDB) e descreve a utilização de eletrodos de DDB, modificados direta ou indiretamente pelo método Sol-gel, para a oxidação de metanol e de etanol em meio ácido. Do estudo das propriedades superficiais do diamante concluiu-se que a polarização catódica é bastante apropriada para um bom desempenho do material é que não introduz diferenças estruturais detectáveis no filme de DDB, indicando que a melhora na resposta eletroquímica é devida somente a mudanças superficiais. Entretanto, polarizações catódicas consecutivas e extensivas por longos períodos de tempo produzem uma erosão da superfície do eletrodo. Adicionalmente, estudos realizados usando voltametria cíclica e espectroscopia fotoeletrônica de raios X, mostraram que a superfície de eletrodos de DDB pré-tratados catodicamente tem um comportamento eletroquímico dinâmico, apresentando uma perda da reversibilidade para o sistema Fe(CN)63-/4- em função do tempo de exposição ao ar. Isto é devido, possivelmente, à perda de hidrogênio superficial decorrente da oxidação da superfície do eletrodo pelo oxigênio do ar. Este comportamento dinâmico da superfície do DDB é inversamente dependente ao teor de boro do eletrodo. Foi observado também que a quantidade de sítios ativos disponíveis na superfície do eletrodo é diretamente proporcional à dopagem do mesmo e deve ser conseqüência da quantidade de boro superficial. Desses estudos concluiu-se que todos os eletrodos de DDB com distintas dopagens usados nesta tese (300, 800, 2000 e 8000 ppm de B) apresentam uma superfície eletroquímica heterogênea (sítios ricos em boro que apresentariam uma alta condutividade e sítios de diamante com terminação hidrogênio com menor condutividade), quando polarizados catodicamente e parcialmente bloqueada (diamante com terminações oxigênio) quando polarizados anodicamente, formando arranjos de microeletrodos (provavelmente sítios ricos em boro). As superfícies do diamante foram modificadas diretamente com Pt, Pt-RuO2 e Pt-RuO2-RhO2 pelo método Sol-gel. Estes depósitos de catalisadores apresentavam tamanhos nanométricos e mostraram um bom contato elétrico com a superfície do diamante e elevada pureza, assim como, uma composição atômica bem controlada e uma distribuição homogênea na superfície do DDB. Os estudos da oxidação eletroquímica de metanol e de etanol sugerem fortemente que o envenenamento da superfície do eletrodo é grandemente inibido sobre o catalisador ternário Pt-RuO2-RhO2/DDB quando comparado com os eletrodos Pt-RuO2/DDB e Pt/DDB. Adicionalmente, esse eletrodo mostra uma excelente atividade catalítica para a oxidação de etanol, provavelmente devido à habilidade que o ródio tem para quebrar a ligação C-C somada ao mecanismo bifuncional que acontece no catalisador contendo Pt e Ru. Em seguida, realizaram-se modificações indiretas do DDB pela síntese de compósitos de pó de carbono modificados com metais e óxidos metálicos e posterior fixação usando uma solução de Nafion. A oxidação dos álcoois foi estudada por voltametria cíclica e curvas de polarização em estado estacionário (diagramas de Tafel). Os sistemas investigados incluíram misturas metálicas binárias, ternárias e quaternárias contendo Pt, Ru, Ir, Rh, PbOx, TaOx e MoOx num total de 16 sistemas diferentes. Assim, os melhores catalisadores para a oxidação de metanol foram: Pt-Ru-TaOx-PbOx > Pt-Ru-TaOx-MoOx ≈ Pt-Ru-MoOx-Ir enquanto que, para a oxidação de etanol foram Pt-Ru-TaOx-PbOx e Pt-Ru-PbOx-Rh. Consequentemente, catalisadores do tipo Pt-Ru-TaOx-M são promissores para futuras aplicações práticas. Finalmente, estudos preliminares realizados usando pó de DDB modificado diretamente com Pt-RuOx pelo método Sol-gel mostraram que este compósito apresenta uma excelente atividade catalítica para oxidação de metanol, que foi maior do que a observada sobre um catalisador comercial considerado como o estado da arte (Pt-Ru/C da E-TEK) nas mesmas condições experimentais. Desta forma, foi mostrada a possibilidade do uso de pó de DDB como suporte para eletrocatalisadores para aplicações em células a combustível que funcionem diretamente com álcoois. / The electrochemical properties of boron-doped diamond (BDD) surfaces as well as studies of the oxidation of methanol and ethanol in acid media on BDD surfaces modified with catalysts by the Sol-gel method are presented here. Studies of the surface properties of BDD electrodes revealed that a cathodic polarization (-3,0 V vs. HESS, 30 min) is necessary for a good performance of the system while no important bulk structural differences are introduced in the film indicating that the enhanced electrochemical responses brought on by the cathodic pre-treatment is only due to superficial changes. Meanwhile, repeated and extensive cathodic polarizations led to severe erosion of the electrode surface. On the other hand, studies performed using cyclic voltammetry and X-ray photoelectron spectroscopy have shown that, after a cathodic pre-treatment, the BDD electrode surface presents a dynamic behaviour that results in a loss of the reversibility towards the Fe(CN)6 4−/3− redox couple as a function of the time exposed to atmospheric conditions. This dynamic behaviour must be associated to a loss of superficial hydrogen due to oxidation by the air and is inversely proportional to the BDD doping level suggesting that the boron content has a stabilizing effect on the H-terminated surface. It was also observed that the amount of electrochemical active sites of the BDD electrode has a direct dependence with the doping level (maybe due to the amount of superficial boron). From those studies, it was concluded that all BDD electrodes used in this work having different doping levels (300, 800, 2000 and 8000 ppm of boron) posses, after cathodic polarization, electrochemical heterogeneous surfaces (i.e. boron-rich sites with high conductivity and H-terminated diamond sites with lower conductivity) while after anodic polarization the surface is partially blocked by O-terminated diamond sites, resulting in a behaviour that resembles microelectrode arrays (probably formed by the few boron-rich sites). The BDD surface was also modified directly with Pt, Pt-RuO2 and Pt-RuO2-RhO2 using the Sol-gel method. These catalysts deposits have nanometric sizes, good electrical contact with the diamond surface and high purity. They also show a well controlled atomic composition and a homogeneous distribution on the BDD surface. Methanol and ethanol electrochemical oxidation studies on those modified electrodes suggested that poisoning of the surface by undesired intermediates (most xvi probably CO) is highly inhibited on the ternary catalyst Pt-RuO2-RhO2/BDD when compared with the Pt-RuO2/BDD and Pt/BDD responses. Additionally, the observed catalytic activity for ethanol oxidation was excellent, probably due to the rhodium ability to break the C-C bond which was added to the bifunctional mechanism operating in Pt-Ru catalysts. In the sequence, indirect modifications of the BDD surface were carried out by the production of carbon powder composites modified with metals and metallic oxides by the Sol-gel method and their subsequent anchoring to the BDD using a Nafionsolution. The alcohols oxidation on these electrodes was studied by cyclic voltammetry and steady-state polarization curves (Tafel plots). The investigated systems included binary, ternary and quaternary catalysts containing Pt, Ru, Ir, Rh, PbOx, TaOx and MoOx in a total of 16 different systems The higher catalytic activity towards methanol oxidation was observed in the sequence: Pt-Ru-TaOx-PbOx > Pt-Ru-TaOx-MoOx _ Pt-Ru-MoOx-Ir while for ethanol oxidation, the catalysts activity sequence was: Pt-Ru-TaOx-PbOx _ Pt-Ru-PbOx-Rh > Pt- Ru-Rh. Consequently, it was concluded that catalysts of the type Pt-Ru-TaOx-M are very promising systems to be used in future practical applications. Finally, preliminary studies carried out using BDD powder directly modified with Pt-RuOx by the Sol-gel method showed that this material has an excellent catalytic activity towards methanol oxidation reaction, being higher than that observed on a state of the art commercial catalyst (Pt-Ru/C from E-TEK) under the same experimental conditions. Thus, the feasibility of the use of BDD powder as catalysts support in direct-alcohol fuel cell systems was clearly established.

Orientador: Yoshitaka Gushikem / Texto em inglês / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-21T20:29:33Z (GMT). No. of bitstreams: 1 Rahim_Abdur_D.pdf: 2383649 bytes, checksum: 98658562d78717c6e16d2a66e1d8cfa6 (MD5) Previous issue date: 2013 / Resumo: Este trabalho descreve as sínteses, caracterizações e as aplicações dos materiais carbono cerâmicos mesoporosos identificados como: SiO2/20wt%C (SBET= 160 mg) e SiO2/50wt%C (SBET= 170 mg), em que C corresponde ao carbono grafite. Tais materiais foram preparados através do método sol-gel e empregados como matrizes para o desenvolvimento de sensores e biosensores eletroquímicos. Imagens obtidas através da microscopia eletrônica de varredura (MEV) acoplada com a espectrosocopia de energia dispersiva (EDS) mostraram que, com relação as resoluções utilizadas, não foram detectadas segregação de fases. Os materiais que contem 20 e 50 wt% de C apresentaram condutividades elétricas de 9,2 x 10 S cm e 0,49 S cm, respectivamente. Esses materiais foram utilizados como matrizes para suportar ftalocianinas de: cobalto (CoPc), cobre (CuPc) e manganês (MnPc), as quais foram preparadas in situ ao longo de suas superfícies de forma que fosse assegurada dispersão homogênea dos complexos eletroativos nos poros das matrizes. As densidades superficiais da ftalocianina de cobalto em ambas as superfícies da matriz foram: 0,014 mol cm e 0,015 mol cm, para os materiais contendo 20 e 50 % m/m de C, respectivamente. Foram empregados como eletrodos de trabalho pastilhas preparadas a partir dos eletrodos carbono cerâmicos, considerando-se os seguintes materiais: SiO2/C/CoPc, SiO2/C/CuPc e SiO2/C/MnPc. A técnica de XPS foi usada para determinar as proporções de Mn/Si atómicos dos materiais MnPc modificados. O material SiO2/C/CoPc foi testado como um sensor de ácido oxálico e de oxigenio, e os materiais e SiO2/C/CuPc e SiO2/C/MnPc foram testados como sensores para a dopamina e nitrito, respectivamente. Esses materiais tem se mostrado como alternativas promissoras para o desenvolvimento de sensores eletroquímicos e de biosensores, atuando como substratos robustos e versáteis para a construção de novos eletrodos carbono cerâmicos. / Abstract: This work describes the synthesis, characterization and applications of mesoporous carbon ceramic materials identified as: SiO2/20wt%C (SBET = 160 mg) and SiO2/50wt%C (SBET= 170 mg), where C represents the carbon graphite. These materials were prepared by the sol-gel method and used as support for the development of electrochemical sensors and biosensors. Images obtained by scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) showed that, within the magnification used, no phase segregation was detectable. The materials containing 20 and 50 wt% of C presented electric conductivities of 9.2×10and 0.49 S cm, respectively. These materials were used as matrices to support manganese phthalocyanines (MnPc), cobalt phthalocyanines (CoPc), and copper phthalocyanines (CuPc), prepared in situ on their surfaces, to assure homogeneous dispersion of the electroactive complex in the pores of matrices. The surface densities of cobalt phthalocyanine on both matrix surfaces were: 0.014 mol cm and 0.015 mol cm, for materials containing 20 and 50% wt% of C, respectively. The pressed disk carbon ceramic electrode: SiO2/C/MnPc, SiO2/C/CoPc, and SiO2/C/CuPc were used as working electrode. XPS was used to determine the Mn/Si atomic ratios of the MnPc-modified materials. The material SiO2/C/CoPc was tested as a sensor for oxalic acid and oxygen and the materials SiO2/C/CuPc and SiO2/C/MnPc were tested as sensors for dopamine and nitrite, respectively. These materials have shown to be promising alternative in the development of electrochemical sensors and biosensor, acting as a robust and versatile conducting substrate for the construction of new carbon ceramic electrodes. / Doutorado / Quimica Inorganica / Doutor em Ciências

Ce travail de thèse est consacré à l'élaboration de membrane photocatalytique à partir de nanoparticules de TiO2 obtenues par voie sol-gel (système TTIP-eau). Les sols sont préparés dans un réacteur à micro-mélange rapide (turbulent). L'effet de l'hydrodynamique au sein de différents mélangeurs (T simple, T chicanes, T rétrécissement) sur la morphologie et l'activité photocatalytique de nanoparticules déposées sur des plaques d'α-alumine a été étudié. Les dépôts de TiO2 ont été réalisés durant la période d'induction de la réaction sol-gel. Le mélange des réactifs a été simulé en utilisant un logiciel de modélisation numérique (modèle k-ε), Les différences hydrodynamiques au sein du micro-mélange a seulement un impact significatif sur le temps de stabilité des nanoparticules (période d'induction). Des couches minces et des membranes photo-actives ont été réalisées en vue du couplage membrane et réaction photocatalytique. Ces membranes ont été caractérisées et testées en photocatalyse. Elles ont montrées de bonnes photo-activités. Des tests de couplage direct séparation/photodégradation ont été réalisés sur des solutions aqueuses d'acide orange 7. Ce dispositif expérimental a permis de mettre en évidence une augmentation de flux de perméation significative avec de l'eau et en présence de colorant en solution. L'effet de la concentration et du pH de la solution a été évalué sur les flux de perméat et sur la photodégradation. / This PhD work is devoted to the elaboration of photocatalytic membranes using TiO2 nanoparticles synthetized by sol-gel process (titanium tetra-isopropoxyde precursor – water). Sols are prepared in sol-gel reactor with rapid turbulent micro-mixing. The effect of hydrodynamic using 3 T mixers (T simple, T with 3 baffles and T with narrow) during the mixing was studied with k-ε modeling Computational fluid Dynamics (CFD), as well as the morphology and the photo-activity of thin layers deposited on alumina support during induction period. Differences on hydrodynamic during micro-mixing have only impact on the time of nanoparticles stability (induction period). Photo-active thin layers and membranes are synthesized for coupling membrane separation and photocatalytic reaction. Photocatalytic activities of thin layers and membranes are performed with an aqueous solution of acid orange 7. Significant increases of permeate flux are observed during the filtration of water and solution containing dye. Effects of concentration and pH are evaluated on permeation flux and photodegradation.

Les travaux précédents du laboratoire Hubert Curien ont permis d’élaborer des films photosensibles Ag : TiO2 sur verre, support de marquage de motifs actualisables ou permanents. Une adaptation de ces travaux aux supports plastiques et papiers est ici proposée afin d’élargir les domaines d’application potentiels au marquage sécurité des produits par exemple. Des techniques d’élaboration de films Ag : TiO2 compatibles avec les substrats considérés ont donc été développées. Deux voies ont été envisagées. La première utilise la chimie du Sol-Gel combinée à la méthode EISA et des procédés de dépôt tel le spin-coating, le jet d’encre ou la flexographie pour former un film mésoporeux de TiO2 sur les supports. Des traitements basés sur une extraction par solvant ou un recuit infrarouge ont été imaginés afin de libérer la porosité du film sans dégradation du support. Pour réaliser les films sur papier, un sel d’argent est ajouté au Sol avant son dépôt. Dans les cas des films élaborés sur plastique, l’argent est incorporé par imprégnation du matériau dans une solution de sel d’argent. La deuxième voie d’élaboration propose de formuler une encre aqueuse jet d’encre de nanoparticules de TiO2 et d’ions argent, en adaptant la composition d’une suspension commerciale de TiO2 aux exigences du jet d’encre. Après dépôt, l’encre est séchée par recuit infrarouge. Le comportement photochromique sous expositions lumineuses UV et visible des différents films permet leur coloration et décoloration de façon réversible. Les films Sol-Gel déposés sur plastique peuvent également être support de photo-inscriptions permanentes générées par irradiation par une lumière visible d’une certaine intensité / Previous research conducted at laboratory Hubert Curien led to the development of photosensitive Ag: TiO2 films on glass as support for updatable or permanent patterns. An adaptation of this work to plastic and paper substrates is proposed here to broaden the possible application areas such as goods secure labeling, for example. Fabrication techniques of Ag: TiO2 films compatible with flexible substrates have been developed, using two different paths. The first uses the combination of Sol-Gel chemistry with the EISA method. Deposition processes such as spin coating, inkjet or flexographic printing are used to form a mesoporous film of TiO2 on substrates. Treatments based on solvent extraction or infrared annealing have been devised to release the porosity of the film without damaging the supports. Silver salt is either introduced into the titania pores by soaking the films into a silver salt solution or added to the sol before its coating. The second developed option proposes formulating an aqueous ink jet ink made of TiO2 nanoparticles and silver ions by adapting the composition of a commercial suspension of TiO2 with the requirements of the ink jet process. After printing, the ink is dried by infrared annealing. The photochromic behavior under UV and visible light exposures of fabricated films allows to get coloring and bleaching reversibly. Sol-Gel films coated on plastic can also be a support for permanent colored patterns realized by irradiation with a visible light of certain intensity

Dans le but d'améliorer la fiabilité des technologies utilisant l'électromouillage, l'objectif de cette thèse est d'étudier les mécanismes de vieillissement de matériaux diélectriques et hydrophobes utilisés en électromouillage et d'appliquer ensuite le protocole de caractérisation établi, à de nouveaux matériaux. Cette thèse s'articule en trois parties. Dans une première partie, afin de caractériser finement les propriétés d'hydrophobie de surfaces et de déterminer plus particulièrement leur polarité, nous avons mis au point une méthode de mesure de la polarité de surface basée sur le mouillage de deux liquides sur une surface, ce qui apporte une précision accrue avec un minimum de mesures. Dans une deuxième partie, nous avons étudié différents revêtements utilisés en électromouillage avant et après vieillissement. Nous nous sommes plus particulièrement intéressés aux films hydrophobes largement utilisés dans les systèmes optiques et de micro-laboratoires comme le Fluoropel©, le Cytop© et le parylène C. Cette étude montre une altération non négligeable des performances des matériaux de manière reproductible. L'hystérésis de mouillage, l'angle de contact au repos ainsi que les propriétés de cohésion des couches ont été étudiés afin de mettre en évidence les paramètres critiques à la durée de vie.Dans la dernière partie, nous avons cherché à mettre au point une méthode de dépôt d'un nouveau matériau hydrophobe par deux techniques de synthèse ; la voie sol-gel et la pulvérisation cathodique (PVD). Ainsi, un sol de précurseur à base du métal applicable pour la préparation de couches minces de son oxyde a été élaboré. La solution est obtenue à partir d'un précurseur synthétisé au laboratoire et stabilisée par des chélatants (acétylacétone). La stabilité de la solution ainsi que la procédure de dépôt sont présentées et les revêtements recuits déposés par sol-gel et PVD sont caractérisés par DRX et d'un point de vue morphologique (MEB, microscope optique…). Si, il fut possible de préparer par la méthode sol-gel des films de 300nm couvrants, leur forte rugosité n'a pas permis de les tester en électromouillage. Par la méthode PVD, nous avons pu réaliser des couches de 400 nm d'épaisseur, très lisses et utilisables en électromouillage. Ces films donnent de très bons résultats en électromouillage sur substrats plans et en lentilles liquides / In order to increase the technologies reliability using electrowetting, this work aims to study the mechanisms of ageing on dielectric and hydrophobic materials used in electrowetting as well and to apply this study to new materials. This thesis is composed of three parts.First, to be able to characterize precisely the hydrophobic properties of these surfaces and especially their surface polarity, we established a method to measure the surface polarity based on wettability of two liquids on a surface permitting a better precision with less measurements. In a second part, we studied different films used in electrowetting before and after ageing around 90°C for one week in order to simulate a long term ageing at an ambient temperature. Widely used hydrophobic coating used in optical systems and lab-on-chip will be mainly characterized such as Fluoropel©, Cytop© and parylène C. This work shows the visible alteration of material performances in a reproducible way. Wetting hysteresis and natural contact angle with the cohesive properties of the coatings are studied in order to establish critical parameters for the life time.Finally, we tried to establish a method to deposit a hydrophobic metal oxide coating by two ways, sol-gel technic with dip-coating deposition and by PVD. A precursor sol made of the metal usable to deposit its oxide thin films has been elaborated. The solution is prepared from the synthesized precursor and stabilized by chelatant (acetylacetone). The solution stability as well as the deposition method used are presented and the annealed coatings deposited by sol-gel and PVD are characterized by XRD and morphologically (SEM, optic microscope …). By the sol-gel method, covering coatings of about 300nm have been made. However, because of the roughness, no electrowetting experiments could have been achieved. By PVD, we have deposited coatings of 400nm thickness, very smooth and usable in electrowetting. These coatings give very good results in electrowetting on plane substrates and liquid lenses

L'objectif de ce travail est de synthétiser des nanomatériaux de TiO2 pour la dégradation des COV et pour l'élimination des bactéries en surface. Tout d'abord, basé sur une synthèse des matériaux de TiO2 avec la présence d’un liquide ionique BmimPF6 par une voie sol-gel modifiée, les rôles de deux éléments constitutifs de BmimPF6 (P et F) ont été étudiés en faisant remplacer BmimPF6 par des additives contenant P et F. Par rapport à la référence P25 et aux matériaux de TiO2 synthétisés sans additif, le TiO2 synthétisé en présence de P a déjà montré une meilleure cristallinité en phase anatase avant la calcination, et une surface spécifique élevée et une petite taille moyenne des cristaux étaient maintenus même après calcination. Ces propriétés étaient similaires aux échantillons TiO2 synthétisés en présence de BmimPF6; Tandis que les cristaux de TiO2 en présence de F ont montré une forme anisotrope pendant le murissement de la synthèse. Les évaluations de l'activité photocatalytique des photocatalyseurs ont ensuite été réalisées. Par rapport au TiO2 synthétisé sans additif et au TiO2 P25, les matériaux de TiO2 à faible teneur en P et F ("PANaF") ont présenté une activité plus élevée sous irradiation UVA à la dégradation d'un COV modèle, Méthyléthylcétone (MEK) en phase gazeuse. Le même matériau a également montré une activité anti-bactérienne en surface plus élevée sous UVA contre plusieurs souches de différentes espèces bactériennes dans liquide par rapport à celles de P25. Une corrélation entre la performance photocatalytique élevée et les propriétés des matériaux pour TiO2 "PANaF" a été finalement proposée. Les influences de la présence de PO43- en bulk ou en surface de TiO2, de la concentration d’O2 dissous dans le milieu et de la topologie de surface des photocatalyseurs sur l'activité photocatalytique éteint également sujets de discussion. Le produit "PANaF" présente un intérêt pour l'élaboration industrielle à cause des réactifs pas cher et son performance élevée. / The objective of this work consists in synthesizing TiO2 nanomaterials designed for the degradation of VOCs and for the elimination of bacteria on surface. Firstly, based on a synthesis of a BmimPF6-ionic liquid-derived TiO2 material through a modified sol-gel route, the roles of two constituent elements of BmimPF6 (P and F) have been investigated by replacing BmimPF6 with P- and F- contained additives. Comparing to the reference P25 and additive-free-derived TiO2 materials, P-derived TiO2 showed already well crystallized anatase phase before calcination and a high surface area along with a small mean crystal size even after calcinations. Those properties were similar to that synthesized with the presence of BmimPF6; while F-derived TiO2 crystals showed anisotropic shape during the aging step of the synthesis. Evaluation of the photocatalytic activity of the photocatalysts has been performed then. Compared to additive-free derived TiO2 and the TiO2 P25, P- and F- derived TiO2 materials with low P and F content (“PANaF”) showed higher activity under UVA in terms of gas-phase degradation of a model VOC, Methl Ethyl Ketone (MEK). The same material also showed higher surface anti-bacterial activity under UVA in liquid against several strains of different bacterial species over that of P25. A correlation between the high photocatalytic performances with the material properties for “PANaF” TiO2 materials was finally proposed. The influences of the presence of bulk or surface PO43-, dissolved O2 concentration and surface topology on photocatalytic activity were also discussed. The cheap replacement additives used and the resulted high activity of “PANaF” TiO2 nanomaterials presents interest for industrial elaboration.

Les biomatériaux en titane sont de plus en plus utilisés dans les implants dentaires et les prothèses de hanche. Toutefois, la surface des implants de titane doit être modifiée pour devenir davantage bioactive. Dans cette étude, les substrats de Ti-6Al-4V ont été d'abord modifiés par un traitement mécanique, puis par un traitement acide. Dans un deuxième temps, les échantillons ont subi un traitement alcalin dans une solution de NaOH puis un traitement thermique, ce qui a provoqué la formation d'une couche de titanate de sodium sur leur surface. Enfin, du phosphate de calcium a été déposé soit par voie sol-gel, soit par voie autocatalytique, sur la couche de titanate de sodium pour obtenir un revêtement bioactif de titanate de sodium/ phosphate de calcium.Après le dépôt, la morphologie et la structure de la couche de phosphate de calcium ont été analysées par diverses méthodes comme FTIR, Raman, ORX, MES, MET, EDS-X et SAED. De plus, la coupe transversale du revêtement de titanate de sodium/ phosphate de calcium a été analysée par MEB/ EDS-X. Et l'adhésion du dépôt de phosphate de calcium au substrat a été qualitativement estimée par nano-indenteur. La bioactivité in vitro du dépôt a été vérifiée par la méthode de Kokubo utilisant la solution simulant le plasma sanguin (SBF). Et la cytotoxicité in vitro du dépôt a été vérifiée par le test de viabilité cellulaire utilisant les ostéoblastes MG63. Les résultats ont indiqué que le dépôt de phosphate de calcium est cytocompatible et bien lié au substrat. De plus, le dépôt de phosphate de calcium est stable en milieu physiologique (SBF) pour des durées d'immersion de 2 à 28 jours. La croissance d'apatite sur la surface des dépôts a été observée après 2 jours d'immersion dans SBF. / Titanium and its alloys based biomaterials are more and more used for medical implants in reconstructing of failed tissue. However to respond to the demand of orthopaedic and dental application, their surfaces have to be modified to increase the osteointegration rate. ln this study, the Ti-6Al-4V alloy surface was firstly mirror polished and treated by an acid solution. Then, a thin film of sodium titanate was formed on its surface via an alkaline-heat treatment. Finally, a calcium phosphate was coated on the sodium titanate layer by using the sol-gel technique or the autocatalytic route. By this process, a bi-phase bioactive sodium titanate/calcium phosphate layer was created on the titanium substrate.After coating, the morphology and the structure of calcium phosphate layer were analyzed by various methods such as FTIR, Raman, XRD, SEM, TEM, EDS-X and SAED. Additionally, a cross-section view of sodium titanate/ calcium phosphate layer was also realized by SEM/ EDS-X.And the adhesion of calcium phosphate layer onto the substrate was verified qualitatively by nano-indenter. The in vitro bioactivity of calcium phosphate coated samples was tested by Kokubo's method using the simulated body fluid (SBF). The in vitro cytotoxicity of calciumphosphate coated samples was estimated by cell viability assay using the osteoblasts MG63.The results showed that the calcium phosphate coating is cytocompatible and strongly bonds to the substrate. ln addition, the calcium phosphate coating was stable in SBF for different soaking periods from 2 to 28 days. And the growth of apatite on the calcium phosphate coated sample surface was identified after 2 days of immersion in SBF.