Orientador: Ulf Friedrich Schuchardt / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-04T03:11:25Z (GMT). No. of bitstreams: 1 Cesquini_RenatoGiovani_M.pdf: 3468081 bytes, checksum: e107be89a6831d6fb6508cfa3942126d (MD5) Previous issue date: 2004 / Mestrado / Quimica Inorganica / Mestre em Química

Jusqu'à récemment dans de nombreuses régions tropicales et subtropicales, on utilisait surtout les graveleux latéritiques en géotechnique routière, comme matériaux d’assise de chaussée. Avec l'évolution des besoins, la récente prise en compte des contraintes environnementales et la rareté des graveleux latéritiques de bonne qualité, la promotion de matériaux dont l'usage est peu répandu pour diverses raisons techniques ou historiques est encouragée. En Afrique subsaharienne, la valorisation des matériaux marginaux naturels locaux, singulièrement les sols latéritiques fins, en technique routière est vivement encouragée pour une meilleure utilisation des ressources dans le cadre du développement durable et dans un contexte socio-économique particulier.Ce mémoire de thèse expose une étude du comportement mécanique d’un sol latéritique fin traité au ciment à différents dosages pour une valorisation en technique routière. Il comporte cinq parties:La première partie concerne une étude bibliographique des travaux réalisés sur les sols latéritiques. On présente également les travaux réalisés sur les sols traités au ciment.La deuxième partie est consacrée à la description des matériaux étudiés. Après la présentation des caractérisations physiques, chimiques et minéralogiques de ces matériaux, on présente les paramètres de l’étude. Cette partie s’achève par la caractérisation minéralogique et microstructurale du sol latéritique traité au ciment à différents dosages.La troisième partie présente les résultats expérimentaux d’une étude de la consolidation unidimensionnelle du sol latéritique avant et après traitement au ciment à différents dosages. La vérification de l’aptitude au traitement du sol, la détermination des caractéristiques intrinsèques et de compactage du sol traité au ciment sont également présentées dans cette partie.La quatrième partie présente les résultats expérimentaux de la résistance mécanique du sol avant et après traitement au ciment. La portance, les résistances en compression et en traction, les résistances à la rupture et au cisaillement forment l’ossature de cette partie.Enfin la cinquième partie présente une analyse numérique et économique de la conception d’une assise de chaussée en sol latéritique traité au ciment à différents dosages L’influence du traitement du sol sur l’épaisseur de l’assise de chaussée est examinée, ainsi que le coût économique de l’assise de chaussée. / Until recently, in many tropical and subtropical regions, lateritic gravels have been used in geotechnical highway, like for example in the road foundations. With the increase of needs, the recent consideration of environmental constraints and the unavailability of lateritic gravels with good mechanical properties, the promotion of materials whose use is not widespread for various technical or historical reasons is encouraged. In Sub-saharan Africa, the valorization of local natural marginal materials particularly the fine grained lateritic soils, in road construction purposes is strongly encouraged where a better utilization of resources might help insure sustainable development in a particular socio-economic context.This thesis presents a study of the mechanical behavior of a cement treated fine grained lateritic soil for a valorization in road construction. It constains five parts:The first part concerns a literature review of work on lateritic soils. It also presents the work completed on soils treated with cement.The second part is devoted to the description of the materials studied. After the presentation of physical, chemical and mineralogical characterizations of these materials, we present the parameters of the study. At the end, mineralogical and microstructural characterization of cement treated lateritic at different dosages is presented.The third part presents the experimental results of a study of one-dimensional consolidation of lateritic soil before and after treatment with cement at different dosages. The verification of the processability of the soil, as well as the determination of intrinsic characteristics and compaction of the cement treated lateritic are also illustrated in this section.The fourth part shows the experimental results of the mechanical strength of the lateritic soil before and after treatment with cement. The discussion about bearing capacity, the compressive and tensile strength and the rupture and shear strengths constitutes the major concern of this part.Finally, the fifth part presents a numerical and economic analysis of the design of a road foundation of lateritic soil treated with cement at different dosages. The influence of soil treatment on the thickness of the road foundation is examined, as well as the economic cost of the road foundation.

L’étude menée concerne divers aspects d’une nouvelle voie de synthèse sol-gel : la génération électro-assistée de films à base de silice fonctionnalisée et/ou mésostructurée, ainsi que leurs applications en électrochimie analytique. Des films à base de silice fonctionnalisée par des groupements amine ou thiol ont été déposés sur électrode d’or par catalyse électrochimiquement assistée de la polycondensation. La formation d’une monocouche auto-assemblée partielle de mercaptopropyltriméthoxysilane permet une très bonne adhésion du film silicaté sur la surface d’or. Le processus d’électro-dépôt est caractérisé par deux étapes successives de vitesse différente. A une étape de dépôt lent et régulier succède une croissance bien plus rapide du film. L’utilisation des électrodes modifiées a été envisagée en tant que capteur de Cu2+. En introduisant un tensioactif dans le sol de synthèse, il est possible d’électrogénérer des films à base de silice mésoporeuse de structure hexagonale avec les pores orientés perpendiculairement par rapport au substrat (difficile à obtenir par d’autres méthodes). Il semblerait que l’électrochimie permette à la fois un contrôle de la structure du tensioactif à la surface de l’électrode et la croissance simultanée du film sol-gel. Cette méthode d’électrogénération permet aussi d’obtenir des films fins homogènes sur des surfaces non planes ou présentant des hétérogénéités de conductivité. Enfin, une approche préliminaire a été proposée visant à appliquer le processus d’électrogénération, couplé à la technique de microscopie électrochimique à balayage, pour déposer localement des films à base de silice sous forme de plots de taille micrométrique sur or. / The study deals with various aspects of a novel method of sol-gel synthesis : the electro-assisted generation of functionalized and/or mesostructured silica thin films, and their applications in analytical electrochemistry. Sol-gel-derived silica films functionnalized with amine or thiol groups have been electrogenerated on gold electrodes. The formation of a partial self-assembled monolayer of mercaptopropyltrimethoxysilane (MPTMS) on gold led to a silica film adhering well to the electrode surface owing to the MPTMS acting as a « molecular glue ». The whole process was characterized by two successive distinct rates, starting by a slow deposition stage leading to thin deposits, which was followed by a much faster film growing in the form of macroporous coatings. The use of these modified electrodes was considered as a voltammetric sensor for copper(II). By adding a surfactant in the synthesis medium, it’s possible to electrogenerate mesostructured silica films with hexagonal structure with pore channels oriented perpendiculary to the substrate (which is difficult to get by other methods). The electrochemically-induced-self-assembly of surfactant-templated silica thin films can be applied to various conducting supports. The broad interest of the novel method was demonstrated by its ability to produce homogeneous deposits of silica on non-planar surfaces or heterogeneous substrates, what is difficult by the traditional techniques of film deposition. Finally, a preliminary approach has been proposed in order to apply the electrodeposition process coupled with a scanning electrochemical microscope in order to get localized sol-gel deposits at the micrometric size level on gold.

Dióxido de estanho (SnO2) é um óxido com características semicondutoras, cujo comportamento de transporte elétrico tem interesse crescente de aplicação tecnológica, principalmente na utilização como filmes condutores transparentes. Neste trabalho, são produzidos xerogéis (pós) e filmes finos de SnO2 dopados com antimônio (Sb) pelo processo sol-gel, usando a técnica de molhamento (\"dip-coating\") na deposição dos filmes, com o intuito de se investigar os fenômenos envolvidos na condutividade elétrica do material. Os filmes finos são compostos por uma grande quantidade de pequenos grãos (3-6nm), tornando o espalhamento eletrônico na região do contorno de grão um fator determinante para a condução. Experimentos de fotocondutividade são feitos com luz monocromáticas advinda de uma fonte de deutério acoplada a um monocromador apropriado à baixas temperaturas, em filmes finos de Sn02, e mostram um aumento na fotocorrente que se inicia na transição de banda (\"bandgap\" ≅ 3,6eV) e continua aumentando mesmo para energias superiores ao bandgap. Este resultado está relacionado com a recombinação de pares elétron-buraco fotogerados com espécies de oxigênio adsorvidas no contorno de grão. Esta relação de recombinação também é observada em medidas de decaimento da condutividade fotoexcitada com o quarto harmônico de um laser de Nd:YAG (266nm), pelas quais se verifica o fenômeno de fotocondutividade persistente nos filmes. Resultados de resistência elétrica em função da temperatura (25-300K) indicam o caráter doador do dopante. Análises por Espectroscopia de Absorção de Raios X (XAS), feitas com radiação sincrotron, mostram que o antimônio em seu estado de oxidação Sb+5, entra na rede de SnO2 em sítios na superfície do cristalito, em substituição à átomos de estanho (Sn+4), levando a um aumento na concentração de elétrons livres. Medidas de Espectroscopia de Fotoemissão de Raios X (XPS) confirmam este comportamento substitucional de Sb e sugerem sua localização na superfície dos grãos. Em adição a isso, análises de Difração de Raios X (XRD) mostram as dimensões manométricas dos grãos e indicam que o dopante inibe o crescimento desses grãos. Caracterizações óticas mostram uma diminuição da transmitância dos filmes na região do infravermelho próximo (0,8-4,5&#181m), proporcionalmente à adição de Sb. Este fato pode ser explicado pela teoria de Drude e tem relação com a alta concentração de portadores (cerca de 1020cm-3) e alta reflexão ótica nesta região, promovida pela dopagem. As várias caracterizações feitas, indicam que filmes finos de SnO2:Sb depositados por este processo, apresentam baixa mobilidade eletrônica influenciando a condutividade elétrica do material / Tin dioxide (SnO2) is an oxide with semiconducting characteristics and electrical transport behavior of growing interest for technological applications, mainly as transparent conducting films. In this work, thin films and xerogels (powder) of Sb-doped SnO2 have been produced by the sol-gel process. Films are deposited by dip-coating technique. These samples aim at the investigation of electrical conductivity phenomena of this material. Thin films grown by this technique are composed of a huge amount of tiny grains (3-6nm), leading to high electron scattering at grain boundary region, which becomes the most relevant factor to the conduction. Photoconductivity experiments on SnO2 thin films are carried out with monochromatic light from a deuterium source coupled to an appropriate monochromator, at low temperature, and shows increase in the photocurrent, beginning about bandgap transition ≈ 3.6eV) and keep increasing even for higher energy than the bandgap. This result is related to electron and hole recombination with oxygen species adsorbed at grain boundary. This recombination is also observed in measurements of decay of photo-excited conductivity, where the sample is excited with the fourth harmonic of a ND:YAG laser (266nm). These results allow the verification of persistent photoconductivity phenomena in SnO2 thin films. Electrical resistance as function of temperature (25-300K) indicates the donor nature of antimony. X-ray absorption spectroscopy (XAS), done with sincrotron radiation, shows that antimony enters into the Iattice at surface crystallite sites, substitutional to tin atoms (Sn 4+) in the Sb5+ oxidation state, leading to an increase of the free electron concentration. X-ray photoemission spectroscopy (XPS) data confirm this behavior and suggest the Sb location at grain boundary surface. In addition, X-ray diffraction analysis (XRD) shows the nanoscopic dimensions of grains and indicates that doping inhibits grain growth. Optical characterization shows transmittance decrease in the near infrared (0.8-4.5µm), proportional to Sb concentration. It can be explained by Drude\'s theory and is related with a high electron concentration (about 1020 cm-3), which originates optical reflection, promoted by doping. AII the characterization done in this work, indicates that SnO2:Sb thin films, deposited by this process, present low electronic mobility, influencing the electrical conductivity of this material

M.A., Faculty of Arts, University of the Witwatersrand, 1996

Les forêts sont caractérisées par les nombreuses fonctions et les biens et services qu'elles offrent à la société. Toutefois, les diverses utilisations du territoire forestier posent un défi fondamental : la cohabitation des acteurs. Généralement associée à des conflits d'usages, mais aussi à des utilisations complémentaires, la diversité des biens et services de la forêt met en exergue la complexité associée à la gestion forestière. La gestion intégrée des ressources et du territoire (GIRT) est un concept théorique qui tente de faciliter l'utilisation multiple du territoire forestier. Cependant, la GIRT intègre à son tour plusieurs concepts qui, pris individuellement, sont tous aussi complexes les uns que les autres. Pensons notamment au processus de gestion coopératif, à la concertation, au développement du territoire, à la conservation, à la mise en valeur des ressources et des fonctions du milieu, aux bénéfices et retombées économiques, aux collectivités forestières et à l'optimisation de l'utilisation des ressources qui sont inclus dans la définition de la GIRT. Cette thèse permet ainsi de démystifier la GIRT en explorant les différentes facettes, théoriques et appliquées, tout en se basant sur les perceptions des acteurs qui sont au cœur même de cette approche. Avant tout, la GIRT est un concept englobant qui prend forme grâce à la dynamique des acteurs sur le territoire forestier. Cette thèse, divisée en quatre chapitres, considère la perception de ces acteurs, passés et actuels, qui ont été impliqués dans la mise en œuvre de la GIRT. Premièrement, dans le but de comprendre le concept et ses origines, un bilan des trente dernières années, soit depuis le changement de régime forestier en 1986, a été dressé pour le Québec. Ce sont ici les experts d'hier et d'aujourd'hui, issus de différents secteurs du milieu forestier, qui ont été mobilisés. Ainsi, les conclusions s'appuient sur leurs témoignages, sur l'analyse de documents gouvernementaux, d'actes de colloques et de la littérature scientifique. Deuxièmement, pour comprendre les subtilités, les enjeux et les opportunités associés à la mise en œuvre de la GIRT telle que définie dans la législation forestière québécoise, une étude de la perception des professionnel(le)s responsables de son implantation a été menée. Au moyen d'entrevues semi-dirigées, il a été possible d'identifier les principaux défis et de proposer une nouvelle définition du concept pour mieux correspondre aux enjeux contemporains. Troisièmement, au-delà du concept théorique, la GIRT est avant tout un concept pratique qui s'intéresse aux multiples utilisations du territoire forestier. Ce sont donc les acteurs qui utilisent le territoire forestier qui sont au cœur de la GIRT. Cette thèse vise à connaître leurs perceptions de la mise en œuvre de la GIRT. Au moyen d'un sondage réalisé en ligne et destiné aux membres des Tables locales de gestion intégrée des ressources et du territoire (TLGIRT) et qui sont les représentants officiels des acteurs présents sur le territoire forestier, il a été possible d'identifier les forces et les faiblesses associées à la GIRT. Bien que tout soit en place pour faciliter une prise en compte équitable des acteurs, des écarts sont toujours observés. Quatrièmement, la GIRT se déploie localement sur l'ensemble des forêts publiques et elle prend en compte les retombées générées par l'utilisation des ressources. Le dernier chapitre permet de cartographier la valeur économique des usages directs dans des territoires ciblés où cohabitent plusieurs usagers, soit les réserves fauniques. Les résultats permettent ainsi de visualiser la GIRT en fonction des caractéristiques biophysiques et anthropiques du territoire, dans le but de développer des scénarios d'aménagement qui facilitent la cohabitation des utilisations dans le temps et dans l'espace. En conclusion, les résultats de cette thèse proposent un nouveau modèle théorique de la GIRT qui met en lumière l'importance des relations qui se sont bâties entre les acteurs au fil du temps. Afin de faire face aux défis que pose la présence d'intérêts multiples, il faut s'appuyer sur des approches qui prennent en compte les enjeux sociaux en amont de la planification forestière. Pour y arriver, il faut octroyer aux parties prenantes impliquées sur le territoire forestier un pouvoir décisionnel en matière de gestion intégrée et ultimement d'aménagement forestier intégré. / Forests are characterized by the many goods and services they provide to the society. However, the various uses of the forest territory pose a fundamental challenge: the cohabitation of actors. Usually related to usage conflicts, but also with complementary uses, the diversity of goods and services highlights the complexity associated with forest management. Integrated land and resource management (ILRM) is a theoretical concept that aims to achieve multiple uses of forest lands. The ILRM definition also includes various concepts that, analyzed individually, are as complex as ILRM itself. This includes the cooperative management process, concertation, land development, conservation, enhancement of forest resources and functions, economic benefits, forest communities, and optimization of resource use. This thesis demystifies ILRM by exploring its different facets, theoretical and applied, while focusing on the perceptions of stakeholders that represent the very heart of this approach. Above all, ILRM is an all-encompassing concept that takes shape through the dynamics of the actors in the forest territory. This thesis, divided into four chapters, considers the perceptions of these actors, past and present, who have been involved in the implementation of ILRM. First, in order to understand the concept and its origins, a review of the last thirty years was made for Quebec. Experts from the past and present, from different sectors of the forestry industry, were mobilized. Thus, the conclusions are based on their testimonies, on the analysis of government documents, symposium proceeding sand scientific literature. Secondly, in order to understand the subtleties, issues and opportunities associated with the implementation of IWRM as defined in Quebec's forestry legislation, a study of the perceptions of the professionals responsible for its implementation was conducted. Through semi-directed interviews, it was possible to identify the main challenges to propose a new definition of the concept to better correspond to contemporary issues. Thirdly, beyond the theoretical concept, ILRM is above all a practical concept that focuses on the multiple uses of the forest territory. It is therefore the actors who use the forest territory who are at the heart of ILRM. This thesis aims to fin out their perceptions of the implementation of IRTWM. By means of a survey carried out online and intended for the members of the Integrated land and resource management panels (ILRMP), who are the official representatives of the actors present on the forest territory, it was possible to identify the strengths and weaknesses associated with ILRM. Although everything is in place to facilitate equitable consideration of stakeholders, gaps are still observed. Fourth, ILRM is being implemented locally across the public forest and is considering the benefits generated by resource use. The last chapter maps the economic value of direct uses in targeted areas where several users coexist, i.e. wildlife reserves. The results allow us to visualize the ILRM according to the biophysical and anthropic characteristics of the territory, with the aim of developing management scenarios that facilitate the cohabitation of uses in time and space. In conclusion, the results of this thesis propose a new theoretical model of IWRM that highlights the importance of the relationships that have been built between actors overtime. To address the challenges posed by the presence of multiple interests, it is necessary to rely on approaches that take social issues into account at the beginning of forest planning. To achieve this, stakeholders involved in the forest area must be given decision making power in integrated management and ultimately in integrated forest management.

L'augmentation des réglementations environnementales, l'optimisation de la productivité industrielle, associées aux tendances du marché, pousse le secteur des couvre-planchers en bois prévernis à évoluer continuellement. Pour répondre à ces demandes, le développement de revêtements photopolymérisables à haute teneur en solides (ou 100 % solides) de faible brillance est très populaire. Les revêtements photopolymérisables sont très utilisés dans le secteur des couvre-planchers en bois prévernis du fait de leur polymérisation rapide, de leur très faible besoin en énergie et de leur faible impact environnemental. Bien que l'esthétique de la finition soit importante, le revêtement doit également garantir de bonnes propriétés mécaniques et physiques. Parmi les nombreuses stratégies disponibles pour diminuer la brillance, l'ajout de silice est la méthode la plus utilisée dans tous les revêtements mats confondus, mais reste une source de défis majeurs dans le cas des revêtements photopolymérisables 100 % solides. Ceci est dû au faible retrait pendant le processus de formation du film. Dans le cadre de ce projet, différentes stratégies ont été mises en place et étudiées pour diminuer la brillance des revêtements photopolymérisables 100 % solides tout en conservant de bonnes propriétés mécaniques. Dans un premier temps, pour augmenter la compatibilité entre le revêtement à base d'acrylate et la silice, la surface d'une silice micrométrique a été modifiée en deux étapes. La première étape a consisté à greffer du (3-aminopropyl) triéthoxysilane (APTES) pour introduire des groupes amino-réactifs à la surface. La seconde étape a consisté à greffer un monomère acrylate, le diacrylate de dipropylène glycol (DPGDA), via la réaction aza-Michael. L'efficacité de la silice-acrylate modifiée comme agent de matage a été démontrée dans cette étude. Par la suite, les revêtements photopolymérisables automatifiants se sont révélés des candidats prometteurs pour obtenir des surfaces de faible brillance sans agents de matage. L'étude d'un système hybride radicalaire/cationique à séparation de phases a démontré qu'il était possible de modifier la rugosité de surface en contrôlant la cinétique de réaction du système. Pour cela, l'impact de la concentration en photoamorceurs a été étudié afin de déterminer comment la cinétique de réaction influence les morphologies finales des systèmes hybrides. Finalement, ce système hybride initial a été modifié par l'ajout d'un monomère méthacrylate et l'étude de la miscibilité a été réalisé afin de sélectionner un système ternaire compatible avant l'irradiation ultraviolette (UV). Un copolymère réactif (poly(butyl acrylate-co-glycidyl méthacrylate)) a été ajouté pour manipuler le réseau de réticulation, les morphologies et propriétés du polymère. Dépendamment de la concentration en copolymère, les morphologies de surface obtenues pouvaient être lisse à très ondulée avec diverses variations d'amplitudes, menant à de faibles valeurs de brillance. L'impact du copolymère sur la formation des ondulations a été donc été étudié avec attention. La compréhension et le contrôle des systèmes hybrides constituent la nouveauté majeure de ce projet et peuvent aider à améliorer les formulations actuelles afin de préparer la prochaine génération de revêtements automatifiants. / The increase in environmental regulations and industrial productivity, combined with market trends, are driving the prefinished wood flooring industry to evolve continually. To meet this demand, the development of photopolymerizable low-gloss coatings is increasingly popular. Photopolymerizable coatings are very attractive in prefinished wood flooring industry due to its fast cure, very low energy requirements and low environmental impact. While the aesthetics of the finish are important, the coating must also ensure good mechanical and physical properties. Of the many strategies available to reduce gloss, the addition of silica is the most widely used matting technique in all types of coatings and remains a source of ongoing challenges in UV-curable coatings. This is due to the lack of significant shrinkage during the film formation process. In this project, various strategies were studied to decrease the gloss of photopolymerizable coatings. First, to improve the compatibility between the acrylate-based coating and the silica, the microsized silica surface was modified in two steps. The first step involved grafting of (3-aminopropyl) triethoxysilane (APTES) to introduce amino-reactive groups onto the surface. The second step consisted of grafting an acrylate monomer, dipropylene glycol diacrylate (DPGDA), via the aza-Michael reaction. The effectiveness of the modified silica-acrylate as a matting agent was demonstrated in this study. Subsequently, self-matting photopolymerizable coatings were found to be promising for low gloss surfaces applications without the use of matting agents. The study of a hybrid radical/cationic phase separated system showed that it was possible to obtain surface roughness by controlling the reaction kinetics of the system. To this end, the impact of photoinitiator concentration was studied to determine how reaction kinetics influence the final morphologies of the hybrid systems. Finally, this initial hybrid system was modified by the addition of a third methacrylate monomer and the miscibility study was performed to select a compatible ternary system before ultraviolet (UV) irradiation. Then a reactive copolymer, poly(butyl acrylate-co-glycidyl methacrylate), was added to manipulate the cross-linking network, polymer morphologies and properties. Depending on the copolymer concentration, the obtained surface morphologies could be smooth to very wrinkled with various amplitude variations, leading to low gloss values. The impact of the copolymer on the formation of the wrinkles was therefore studied by attention. The understanding and control of the hybrid systems are the major innovation of this project and can help to improve the current formulations for the next generation of self-matting coatings.

Este trabalho apresenta os resultados do preparo e caracterização de janelas eletrocrômicas (ECD) contendo filmes finos de WO3 como camada eletrocrômica, CeO2-TiO2 como contra-eletrodo e eletrólitos a base de polímeros naturais plastificados. Os filmes finos de CeO2-TiO2 e WO3 foram preparados pelo processo sol-gel e usados para montagem de dispositivos (janelas) eletrocrômicas com variados eletrólitos poliméricos. Os filmes finos e as janelas foram caracterizados através de medidas de densidade de carga, voltametria cíclica e transmitância. Os filmes de CeO2-TiO2 e WO3 apresentaram respectivamente, valores de densidade de carga de 11,8 e 27,8 mC/cm2, e razão de carga anódica/catódica de 0,98 e 0,85. As análises voltamétricas dos filmes finos revelaram picos característicos dos processos de oxidação e redução e as análises espectroscópicas a transmitância de 80 e 78 %, respectivamente. Foram preparadas e caracterizadas janelas com eletrólitos a base de gelatina com ácido acético; gelatina com LiI/I2; gelatina com agar; gelatina com líquidos iônicos; gelatina com líquidos iônicos e triflato de európio; poli(vinil butirato) (PVB) com LiI/I2; PVB com LiClO4; agar com LiClO4; agar com líquidos iônicos; DNA; DNA com LiClO4; DNA-cloreto de hexadeciltrimetilamônio (DNA-CTMA) com azul da Prússia; DNA com PEDOT:PSS (poli(3,4-etilenodioxitiofeno):poli(sulfonato de estireno)); DNA-CTMA com PEDOT:PSS. Os melhores resultados de densidade de carga de 5,4 e 6,0 mC/cm2 foram obtidas para os dispositivos com eletrólitos de gelatina com agar e agar com LiClO4. A razão de carga anódica/catódica desses dispositivos foi de 0,98 e 0,99. Os voltamogramas cíclicos das amostras estudadas revelaram picos anódicos e catódicos referentes à extração e inserção de íons lítio e elétrons no filme de WO3. As análises de transmitância em 550 nm entre o estado colorido e descolorido das janelas mostrou os valores de 28% para a janela contendo eletrólito a base de PVB com LiI/I2. Além disso, também foi verificada a estabilidade dos dispositivos revelando a duração entre 100 a 400 ciclos cronoamperometricos, dependendo do eletrólito usado. Os resultados obtidos mostram que as janelas estudadas são potenciais candidatas às aplicações práticas. / This work presents the results of the preparation and characterization of electrochromic windows (ECD) containing thin films of WO3 as electrochromic layer, CeO2-TiO2 as the counter electrode and natural polymer-based electrolytes. Thin films of CeO2-TiO2 and WO3 were prepared by the sol-gel process and used to assembly the electrochromic devices (windows) with different polymer electrolytes. The thin films and windows samples were characterized by charge density, cyclic voltammetry and transmittance measurements. CeO2-TiO2 and WO3 thin films revealed charge density values of 11.8 and 27.8 mC/cm2, and anodic/cathodic charge relation of 0.98 and 0.85, respectively. The cyclic voltammograms revealed the peaks characteristic of the processes of oxidation and reduction and the spectroscopic analysis the transmittance of 80 and 78%, respectively. Electrochromic windows were assembled with electrolytes based on gelatin with acetic acid; gelatina with LiI/I2, gelatin with agar, gelatin with ionic liquids, gelatin with ionic liquids and europium triflate, PVB (poly (vinyl butyrate)) with LiI/I2; PVB with LiClO4; agar with LiClO4, agar with ionic liquids; DNA, DNA with LiClO4; DNA-CTMA (hexadecyltrimethylammonium chloride) with Prussian Blue; DNA with PEDOT:PSS (poly (3,4-ethylenedioxythiophene) poly(styrene sulfonate) ) and DNA-CTMA with PEDOT: PSS. The best results of charge density of 5.4 and 6.0 mC/cm2 and anodic/cathodic charge relations of 0.98 and 0.99 were obtained for the samples containing electrolytes based on gelatin with agar and agar with LiClO4, respectively. The cyclic voltammograms of the electrochromic windows showed cathodic and anodic peaks related to the insertion and extraction of lithium ions and electrons in the film of WO3. The transmittance measurements at 550 nm revealed 28% between the colored and discolored state of the windows with PVB-LiI/I2 electrolyte. Moreover, the stability measurements showed that the ECD remain their transmittance difference during of 100 to 400 of chronoaperometric cycling, depending on the electrolyte used. The obtained results indicate the possibility of use the naturalmacromolecules-based electrolytes in practical electrochromic windows.

Este trabalho descreve o desenvolvimento e a caracterização de novos materiais catalíticos para a oxidação de etanol em células a combustível. Os materiais foram preparados pela incorporação de diferentes metais nobres, tais como Pt, Ru, Rh e/ou Ir, no carbono Vulcan® XC-72 de alta área superficial, como misturas binárias e ternárias, usando o método Sol-gel. Os sistemas usados na investigação incluíram as misturas binárias (Pt0,75-Ru0,25/C, Pt0,75-Rh0,25/C e Pt0,75-Ir0,25/C) e as misturas ternárias (Pt0,75(Ru0,5-Rh0,5)0,25/C, Pt0,5(Ru0,5-Rh0,5)0,5/C, Pt0,25(Ru0,5-Rh0,5)0,75/C, Pt0,75(Ru0,5-Ir0,5)0,25/C, Pt0,5(Ru0,5-Ir0,5)0,5/C e Pt0,25(Ru0,5-Ir0,5)0,75/C). Todos esses compósitos foram preparados usando uma quantidade fixa de 10% de Pt (m/m) em relação ao pó de carbono. Os compósitos foram inicialmente caracterizados por medidas de Difratometria de raios-X e Energia Dispersiva de raios-X, com o objetivo de determinar as estruturas cristalográficas e as dimensões dos cristalitos, bem como a composição aproximada dos catalisadores depositados. As medidas eletroquímicas foram realizadas em solução de HClO4 0,1 mol L-1 em uma célula de dois compartimentos, usando uma configuração de camada fina porosa como eletrodo de trabalho, um contra eletrodo de Pt e um eletrodo de Hidrogênio na mesma solução como referência. Métodos como Voltametria cíclica, Curvas de polarização e eletrólises a potencial constante, junto com medidas do Carbono Orgânico Total durante as eletrólises, foram empregados para determinar a eficiência dos metais frente à oxidação de etanol. Para comparação, foram realizados experimentos análogos utilizando Pt/C 10% comercial da E-TEK. Resultados iniciais sobre as curvas de polarização mostraram que as misturas binárias foram consideravelmente mais catalíticas para a oxidação de etanol do que a amostra comercial, enquanto que as misturas ternárias, praticamente em todos os casos, foram as mais ativas para essa reação. Os dois materiais que apresentaram as maiores atividades nesses experimentos foram Pt0,75(Ru0,5-Ir0,5)0,25/C e Pt0,25(Ru0,5-Rh0,5)0,75/C, apresentando também uma conversão de ~60% para CO2 + H2O da concentração inicial de etanol durante as eletrólises a potencial constante. / This work describes the development and characterization of new catalytic materials for the oxidation of ethanol in fuel cells. The materials were prepared by incorporating different noble metals such as Pt, Ru, Rh and/or Ir as binary and ternary mixtures on the large surface area carbon Vulcan® XC-72 using the sol-gel method. The systems used in this investigation included the binary mixtures (Pt0,75-Ru0,25/C, Pt0,75-Rh0,25/C and Pt0,75-Ir0,25/C) and the ternary mixtures (Pt0,75(Ru0,5-Rh0,5)0,25/C, Pt0,5(Ru0,5-Rh0,5)0,5/C, Pt0,25(Ru0,5- Rh0,5)0,75/C, Pt0,75(Ru0,5- Ir0,5)0,25/C, Pt0,5(Ru0,5-Ir0,5)0,5/C and Pt0,25(Ru0,5-Ir0,5)0,75/C). All those composites were prepared using a fixed amount of 10% Pt (w/w) in relation to the carbon powder. The composites were initially characterized by X-Ray Diffraction and Dispersive XRay Energy measurements aiming to determine the crystallographic structures and the crystallites dimensions as well as the approximate composition of the deposited catalysts. The electrochemical measurements were carried out in HC1O4 0,1 mol L-1 solutions in a two-compartment cell using a porous thin layer configuration for the working electrode, a Pt counter electrode and a Hydrogen electrode in the same solution as the reference. Cyclic voltammetry, polarization curves and constant potential electrolyses methods together with measurements of the Total Organic Carbon during the electrolyses were employed to determine the efficiency of the materials towards ethanol oxidation. For comparison, analogous experiments were carried out using a commercial 10% Pt/C catalyst from E-TEK. Initial results from the polarization curves showed that the binary mixtures were considerably more catalytic for ethanol oxidation that the commercial sample whiles the ternary mixtures were, in practicality all cases, the most active ones for the reaction. ix The two materials that presented the higher activities in those experiments were Pt0,75(Ru0,5-Ir0,5)0,25/C and Pt0,25(Ru0,5-Rh0,5)0,75/C, showing also a ~60% conversion to CO2 + H2O of the initial ethanol concentration during the electrolyses at constant potential.

O xerogel de pentóxido de vanádio possui estrutura bi-dimensional que viabiliza a intercalação de diferentes espécies como íons, compostos orgânicos e espécies poliméricas. E, quando associeado a outros óxidos de metais transição, tais como, WO3 e MoO3 apresenta uma importância em reações de catálise, pois estes óxidos atuam como promotores em reações como, por exemplo, a redução catalítica seletiva do NOx a NH3 e a oxidação de hidrocarbonetos. Além disso, estes óxidos melhoram as propriedades eletroquímicas e eletrocrômicas, favorecendo assim sua utilização em células fotoquímicas, células para conversão de energia solar e cátodos de baterias e lítio. Dentre estes óxidos, o óxido de tungstênio hidratado foi escolhido não somente por favorecer a dissociação ácida das moléculas, mas também por apresentar uma estrutura lamelar que favorece reações de intercalação sem afetar significativamente sua estrutura original. Neste contexto, o xerogel de óxido misto V2O5/WO3 foi sintetizado e suas propriedades eletroquímicas bem como sua capacidade de intercalação foi investigada. em relação ao comportamento eletroquímico, a melhor resposta foi obtida para o óxido misto com menor concentração de WO3, ao passo que para os óxidos com alta quantidade de óxido de tungstênio, a intercalação dos íons Li+ não foi eficiente. Estudos de voltametria cíclica revelaram que a resposta eletroquímica do óxido misto é similar à encontrada para o xerogel de pentóxido de vanádio. Em adição, outros resultados revelaram a dependência da resposta eletroquímica com a natureza do eletrólito suporte. Também foi verificado que é possível intercalar anilina e agentes tensoativos (Brometo de Cetiltrimetilamônio - CTAB), mantendo o caráter bi-dimensional. Neste trabalho, o compósito V2O5/WO3/SiO2 foi preparado pelo método sol-gel. A metodologia usada possibilitou a preparação de microesferas de sílica cobertas por xerogel de V2O5/WO3, conservando não somente a estrutura, mas também as propriedades eletroquímicas. A atividade catalítica avaliou a oxidação do estireno em fase líquida. / Vanadium pentoxide xerogel has a bi-dimensional structure which is suitable for intercalation of a variety of ions, organic compounds, and even polymeric species. In addition, when associated with other metal oxides such as WO3 and MoO3, it presents an important role in catalysis, since the resulting oxides act as promoters in catalytic reduction of the NOx to NH3 and hydrocarbons oxidation. Besides, these oxides improve electrochemical and electrochromic properties, leading to their use in photochemical cells, cathodes and in solar energy cells. Among several metal oxides, hydrated tungsten oxide was chosen not only because of favor the acid dissociation of molecles but also because of its lamellar structure that allows intercalation reactions without affect significantly the original structure. In this context, V2O5/WO3 xerogel mixed oxides were synthesized and electrochemical properties as well as intercalation capacity were investigated. Concerning the electrochemical behavior, the best response was obtained for the mixed oxides with low concentration of WO3, whereas for the oxides with high amount of tungsten oxide, the lithium ions intercalation was not efficient. Cyclic voltammetric studies revealed that the electrochemical response of mixed oxide is similar to that found for the vanadium pentoxide xerogel. In addition, our results reveal the dependence of the electrochemical response on the nature of the supporting electrolyte. It was also verified that it is possible to intercalate aniline and surfactant molecules (N-cetyl-N,N,N,-trimethyl-ammonium bromide - CTAB), maintaining the bi-dimensional character. In this work, V2O5/WO3/SiO2 composite was prepared by sol-gel method. The methodology used enables the preparation of silica microspheres covered by V2O5/WO3 xerogel mixed oxides, retaining not only its structure but also the electrochemical properties. the catalytic activity evaluated in the oxidation of the styrene in liquidphase.