This diploma thesis deals with the synthesis of an organosilica polymer which could be used as a binder for titanium dioxide photocatalytic layers. The main reason for incorporating the binder into the photocatalytic layers is not only the improving of the mechanical properties, but above all, the binder could help with production of low-temperature photocatalytic layers, that could be applied to heat-sensitive materials such as plastic materials. This could create layers on flexible materials that could be easily made into any shape. The work focuses on the synthesis of organosilica polymer from the organosilica precursor and subsequent characterization of the binder. Surface tension, viscosity, density, XRD, thermal analysis of silica binder solutions was performed. Titanium dioxide compositions with this binder were prepared, then they were printed and the layers were treated with UV and plasma. Treated layers were examined by FT-IR and a voltamperometric characterization was performed.

Au cours de ces dernières années, les nanostructures à base de silicium et de germanium, enfouies dans une matrice diélectrique, ont été largement étudiées en raison de leurs applications potentielles dans la nanoélectronique et l’optoélectronique. Afin de fabriquer des dispositifs de haute performance avec des nanocristaux Si1-xGex, il est nécessaire de connaître et de contrôler leurs propriétés structurelles et électriques, ce qui est le but de ce travail. Pour cela, nous avons utilisé la co-implantation ionique de Si et de Ge avec différentes doses dans des matrices de SiO2 pour synthétiser les NCx de Si1-xGex. Concernant l’influence de la matrice sur les propriétés des NCx, nous avons également utilisé l’implantation ionique de Ge dans des films minces de SiOxNy riches en Si élaborés par PECVD. Enfin, l’effet de la présence des dopants sur les propriétés structurales et électriques des NCx de Si1-xGex a été étudié par la co-implantation des dopants avec le Si et le Ge dans le SiO2. Suite à l'implantation des éléments désirés (Si, Ge et éventuellement le dopant), la formation des NCx est induite par un recuit thermique à 1000 ou 1100°C. / Semiconductor nanostructures based on silicon and germanium have attracted enormous interest in the last years because of their potential applications in nanoelectronics and optoelectronics. In order to fabricate high performance devices with Si1-xGex nanocrystals, it is required to know and control their structural and electrical properties which is the aim of our study. For that, we used the ionic co-implantation of Si and Ge of different fluences in SiO2 matrices to synthesize the Si1-xGex NCx. Matrix effect on the properties of Si1-xGex NCx, have been also studied by the implantation of Ge in Si-rich SiOxNy thin films prepared by PECVD. Finally, the effect of the presence of dopants on the structural and electrical properties of Si1-xGex NCx has been studied by the co-implantation of dopants with Si and Ge in SiO2. The formation of NCx is induced by thermal annealing at 1000 or 1100 °C after the implantation of the desired elements (Si, Ge and possibly the dopant).

Made available in DSpace on 2016-06-02T19:19:56Z (GMT). No. of bitstreams: 1 MENA_Rodrigo_2013.pdf: 2867164 bytes, checksum: bfe45eefdca81e4813750dfe0d6cfc15 (MD5) Previous issue date: 2013-07-31 / Financiadora de Estudos e Projetos / It is known that polypropylene is degraded in the presence of UV radiation, making difficult its use in applications where occurs this kind of radiation. This situation arises a need to improve the properties of polypropylene under photodegradation. Some work was done in order to improve the surface properties of the polypropylene film with deposition of organosilicon, but the photoprotection caused by these films is still poorly studied. The purpose of this study was to deposit a film prepared from organosilicon plasmas of HMDSO (Hexamethyldisiloxane) on the surface of polypropylene films and verify the protection provided against photodegradation. Depending on the plasma deposition conditions, we detected a variation in the protection exerted by the deposited film. Among the tests, the chemical vapor deposition on low pressure plasma by radio frequency of 13.56 MHz using a mixture of gases with pressure O2/HMDSO added 6 Pa and a power of 80 W for a period of 1 h showed the best protection results, measured by comparing the evolution of the area in the region with the carbonyl peak at 1722 cm-1. FEG-SEM analysis showed that the film generated have adhesion to the substrate. Profilometry analyzes demonstrated that increasing the deposition time increases the film thickness and decreases its surface roughness. / É sabido que o polipropileno sofre degradação na presença de radiação UV, dificultando a sua utilização em aplicações onde ocorre incidência deste tipo de radiação. Surge assim a necessidade de se melhorar as propriedades do polipropileno em relação à fotodegradação. Alguns trabalhos foram desenvolvidos no sentido de melhorar as propriedades superficiais do polipropileno com a deposição de filmes de organosilicone, mas a fotoproteção originada por estes filmes ainda é pouco estudada. O propósito do presente trabalho foi o de depositar um filme organosilicone preparado a partir de plasmas de HMDSO (Hexametildisiloxano) sobre a superfície de filmes de polipropileno e verificar a proteção fornecida contra a fotodegradação. Dependendo das condições de deposição a plasma empregadas, detectou-se uma variação na proteção exercida pelo filme depositado. Dentre os testes realizados, a deposição de vapor químico por plasma de baixa pressão de radiofrequência de 13,56 MHz usando uma mistura de gases de O2/HMDSO com pressão de somada de 6 Pa e com uma potência de 80 W pelo período de 1 h foi a que apresentou melhores resultados de proteção, medida pela comparação da evolução da área da carbonila na região com pico em 1722 cm-1 As análises SEMFEG demonstraram que o filme formado tem adesão ao substrato. As análises de perfilometria demonstraram que o aumento do tempo de deposição aumenta a espessura do filme e diminui sua rugosidade.

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

L'interaction métal-support (MSI) joue un rôle important dans la catalyse hétérogène. La compréhension et la modification du MSI sont des étapes essentielles pour développer catalyseurs de haute performance. Dans cette thèse, un nouveau concept, qu’il s’agit de recouvrir le support l'oxyde avec un revêtement mono-couche de graphène, a été proposé pour modifier le MSI. L'influence de la couche de graphène sur les interactions de métal (Co et Co-Pt) - oxyde (ZnO et SiO2) et sur les propriétés d'oxydo-réduction des particules métalliques ont été évaluées via des systèmes catalytiques de modèle. Les résultats ont montré que la mono-couche de graphène peut influencer considérablement les états d'oxydation et les morphologies des Co monométallique et Co-Pt bimétallique par rapport aux ceux résultent d’un dépôt direct sur les oxydes nus. En particulier, par calcination sous vide, le graphène protége Co d'être oxydé par ZnO, ce qui conduit à la formation d’un mélange métallique Co-Pt. Co interagit avec les substrats d'oxydes pour former des particules plates qui sont facilement oxydés par O2 en pression faible, tandis que l'insertion d'une couche intermédiaire de graphène entre la couche supérieure métallique et le supporte d’oxyde entraîne la formation des nanoparticules de Co en état très dispersés, qui sont résistants à l'oxydation. Sous la condition de réduction par H2, le graphène favorise clairement la réduction de Co. La quantité de dépôt de Co, le substrat d'oxyde, la température de calcination et l'environnement ont été prouvés pour pouvoir influencer la stabilité de graphène. Ces résultats ouvrent des nouvelles voies possibles d'utiliser le graphène comme promoteur dans des réactions catalytiques à l'avenir. / The metal-support interaction (MSI) plays an important role in heterogeneous catalysis. Understanding and tuning the MSI are essential steps for developing catalysts with high performance. In this thesis, a new concept, which is coating the oxide supports with a single layer graphene, was introduced to modify the MSI. The influence of graphene layer on the metal (Co and Co-Pt) – oxide (ZnO and SiO2) interactions and on the redox properties of metal particles were evaluated through model catalyst systems. The results showed that single layer graphene can significantly influence the oxidation states and morphologies of both mono Co and bimetallic Co-Pt as compared to the one after direct deposition on bare oxides. In particular, under vacuum annealing, graphene protects Co from being oxidized by ZnO and results in Co-Pt metallic mixture. Co interacts with oxide substrates forming flat particles which are easily oxidized by low pressure O2, while insertion of a graphene interlayer between the metal overlayer and the oxide supports leads to the formation of highly dispersed Co nanoparticles, which are resistant to oxidation. Under H2 reduction condition, graphene evidently facilitates the reduction of Co. The deposition amount of Co, the oxide substrate, the annealing temperature and the environment were proved to influence the stability of graphene. These results explore new directions for the possible future of using graphene as a promoter in catalytic reactions.

In der vorliegenden Arbeit wird erstmals systematisch der Einfluss von gasförmigen und festen Verunreinigungen auf das O2, Pt│YSZ- Elektrodensystem am praxisnahen Beispiel der Lambdasonde untersucht. Dazu wurden Festelektrolyt- und Elektrodenmaterialien unterschiedlicher Zusammensetzung und Morphologie den realen Abgasbedingungen nachempfundenen, chemischen und physikalischen Einflüssen ausgesetzt und in Bezug auf Langzeitstabilität, Sensitivität und Wirkmechanismen untersucht. Im Einzelnen lag der Fokus der Untersuchungen auf zwei Ausführungsformen von Elektroden, die sich vor allem durch mikro- bzw. nanoskalige Partikelgrößenverteilungen sowie der Platin/YSZ-Zusammensetzung unterschieden und als Mikro- bzw. Nano-Elektrode bezeichnet wurden. Der Einfluss von Siliciumdioxid als gezielt dem Festelektrolyten beigemischte intrinsische Vergiftung sollte in Wechselwirkung zu den extrinsischen Verunreinigungen wie Natriumionen, Wasserdampf und Phosphorpentoxid untersucht werden. Im Unterschied zu den in der Literatur betrachteten, vereinfachten Modellsystemen konnten damit erstmals Wechselwirkungen beschrieben werden, die zu einem tieferen Verständnis des realen Sensorverhaltens, vor allem der Degradation beitragen. Insbesondere ist es gelungen, ein Modell für die Sauerstoffreaktion an geschädigten Elektroden aufzustellen. Neben der bekannten elektrochemischen Reduktion von Sauerstoff spielen die Transportvorgänge an der Elektrodenoberfläche eine entscheidende Rolle, über die in der Literatur bisher nur wenig bekannt war.

Les agents chimiques de guerre et leurs dérivés pesticides sont des molécules toxiques qui provoquent une incapacité temporaire ou des dommages permanents allant jusqu’à la mort de l’individu. Une des voies majeures de la contamination est la pénétration cutanée. La protection de la peau semble donc importante pour prévenir de ces dangers. Cette thèse concerne l’élaboration de nouveaux topiques protecteurs cutanés contenant des polymères HASE fluorés greffés avec des nanoparticules de silice, cérine ou titane. Dans un premier temps les actifs ont été synthétisés en grosse quantité et leurs propriétés de mouillabilité améliorées. Les tests toxicologiques ont montré que les actifs n’étaient pas irritants pour la peau et non toxiques pour l’environnement. La formulation de ces polymères a permis le développement de deux nouvelles crèmes barrières contre la pénétration du paraoxon dont l’efficacité est dépendante de la présence des nanoparticules. Le greffage des nanoparticules à un polymère HASE fluoré et leur formulation a donc permis le développement de nouveaux topiques efficaces. L’évaluation de l’efficacité a été réalisée sur membranes artificielles et confirmée sur explants de peaux humaines. Enfin, le peu de disponibilité des explants de peaux humaines a motivé le développement d’un modèle d’efficacité utilisant des épidermes humains reconstruits. / Chemical warfare agents and pesticides are toxic molecules causing temporary incapacitation or permanent harms leading to the death of people. One of the major routes of contamination is the percutaneous penetration. Skin protection is important to prevent these dangers. The aim of this thesis is to develop new active topical skin protectants based on nanoparticular networks containing fluorinated HASE polymers grafting with silica, cerium or titanium nanoparticles. First, polymers were synthesized in larger quantity and their wettability properties improved. Toxicological studies have showed that these compounds are non-irritant and non-toxic for the environment. The formulation of these polymers has led to the elaboration of two new barrier creams against paraoxon penetration whose efficiency is dependent on the presence of nanoparticles. Therefore, the grafting of nanoparticles to fluorinated HASE polymer and their formulation have enabled the development of new active topical skin protectant. Efficiency evaluation was done using artificial membranes and was confirmed on ex vivo human skin. The limited availability of human skin explants has motivated the development of a new efficiency model using reconstructed human epidermis.

L’étude de la précipitation de la silice amorphe à partir de TétraEthylOrtoSilicate (TEOS) et d’eau, selon le procédé Stöber, a permis de quantifier la cinétique de réaction par spectroscopie Infra Rouge à Transformée de Fourrier. Nous avons montré que la croissance des particules se fait par agrégation des nuclei, qui sont formés tout au long de la réaction. La transposition de ce procédé en microémulsion eau-dans-huile a permis de synthétiser des nanoparticules de silice de tailles contrôlées. L’hydrolyse du TEOS est ici dix fois plus faible qu’en phase homogène. Lors de l’ajout du TEOS à la microémulsion, on observe une coalescence des gouttelettes accompagnée d’échanges inter-micellaires. Ce phénomène a pu être décrit par un noyau d’agrégation qui dépend des concentrations en tensioactif et en TEOS non hydrolysé. L’étude de ce procédé en macroémulsion a montré l’effet déstabilisateur de l’éthanol et la nécessité de stabiliser l’émulsion pour synthétiser des particules sphériques / The study of the precipitation of amorphous silica starting from Tetraethoxysilane (TEOS) and water according to the Stöber process, made it possible to quantify the kinetics of the reaction by Fourier-Transform Infrared spectroscopy. We demonstrated that the particles grow by aggregation of the nuclei, which are formed throughout the reaction.The transposition of this process in water-in-oil microemulsion made it possible to synthesize silica nanoparticules with controlled sizes. The hydrolysis of the TEOS is here ten times weaker than in homogeneous phase. When we add the TEOS to the microemulsion, we observe a coalescence of the droplets accompanied by inter-micellar exchanges. This coalescence is well described by a core of aggregation which depends on the concentrations of the surfactant and the non-hydrolysed TEOS. The study of this process in macroemulsions showed the destabilizing effect of ethanol and the need for stabilizing the emulsion to synthesize spherical particles

The aim of this master thesis is synthesis of SiO2/Au core/shell nanoparticles. These nanoparticles should improve the signal of optical coherence tomography (OCT). The procedure of nanoparticle synthesis is described in the work. Synthetized nanoparticles were analyzed by scanning electron microscopy (SEM), Ultraviolet-Visible spectroscopy (UV-Vis), Near-infrared spectroscopy (NIRS), Fourier transform-infrared spectroscopy (FT-IR) and Dynamic light scattering (DLS). Then, the synthetized nanoparticles were tested for enhancement of OCT signal. For this testing were also used commercial nanoparticles with the same structure and similar size.

The subject of this thesis are the rheological properties of cement paste with the addition of amorphous silicon dioxide. The basic rheological parameters are that describe the behavior of cement pastes in the fresh state. The work also included rheological tests including measurement principle and method of evaluation. Effect of mineral admixtures with high content of amorphous SiO2 is summarized the available scientific articles. In the experimental part, the effects of impurities with a high content of amorphous SiO2 on the rheological properties of fresh cement paste. It was tested by substitution of up to 10 % by weight of cement in the cement pastes mineral admixtures of different chemical composition, particle size and pozzolanic activity. Flow measurement was measured yield value, viscosity, and flow index. The stability of cement pastes was investigated oscillatory measurements. To complement the behavior pastes in the fresh state was determined by calorimetry. Test results were compared with those determined by reference samples and compared the effect of various ingredients.