Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第17525号 / 工博第3684号 / 新制||工||1560(附属図書館) / 30291 / 京都大学大学院工学研究科分子工学専攻 / (主査)教授 佐藤 啓文, 教授 今堀 博, 教授 山本 量一 / 学位規則第4条第1項該当

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第17587号 / 工博第3746号 / 新制||工||1571(附属図書館) / 30353 / 京都大学大学院工学研究科物質エネルギー化学専攻 / (主査)教授 安部 武志, 教授 陰山 洋, 教授 阿部 竜 / 学位規則第4条第1項該当

L'obtention de manière contrôlée de matériaux chalcogénures nanostructurés et possédant une surface spécifique importante ou fonctionnalisée est un défi très intéressant. En alliant une surface spécifique élevée à la polarisabilité des surfaces chalcogénures ou en élaborant des matériaux fonctionnalisés, on peut espérer une percée dans de nombreux domaines comme la catalyse, la séparation gazeuse, l'électrochimie, le photovoltaïque ou l'optique... L'objectif de cette thèse était de développer des voies de synthèse du disulfure de germanium (GeS2) par chimie douce à température et pression ambiantes. Pour cela, nous avons utilisé deux agents sulfurants, le sulfure de dihydrogène (H2S) et le thioacétamide que nous avons fait réagir avec du tétraéthoxyde de germanium en présence d'un solvant. Les synthèses ont été réalisées en l'absence ou en présence d'un structurant, le plus souvent un liquide ionique (LI). Les synthèses sans structurant ont permis l'obtention de nanoparticules de GeS2 amorphes ou nano-organisées de 20 à 35 nm de diamètre et de surface spécifique intéressante (320 m2.g-1 avec H2S, 270 m2.g-1 avec le thioacétamide). Les synthèses réalisées en présence de LI conduisent à des matériaux hybrides contenant GeS2 et le cation du LI utilisé, de formule générale 0.2GeS2-0.8 cation organique. Les particules obtenues de taille micrométrique et présentant de très faibles surfaces spécifiques ont une morphologie qui dépend de la nature du cation organique impliqué dans la synthèse (sphères ou roses des sables). Des mesures XPS montrent la présence de liaisons Ge-S- au sein de l'hybride. L'utilisation de lithium de bis(trifluorométhanesulfonyl)imide nous a conduit à synthétiser un matériau GeS2-Li dont la conductivité de ~10-10 S.cm-1 est celle d'un sel ionique. En l'absence de solvant et en faisant jouer au LI le rôle de solvant et de structurant, nous avons pu préparer le premier iono-chalcogel qui, après optimisation, pourrait conduire à un matériau poreux. Par ailleurs, l'utilisation d'un structurant non ionique, l'hexadecylamine (HDA), au-delà de sa concentration micellaire critique, a conduit à l'obtention d'un matériau hybride nanométrique (environ 15 nm) qui possède non seulement une surface spécifique intéressante (130 m2.g-1) mais surtout une porosité intra-granulaire. En résumé, ce premier travail exploratoire nous a permis d'obtenir, selon le procédé de chimie douce choisi, du disulfure de germanium sous forme soit de nanoparticules aux surfaces spécifiques intéressantes, soit de particules présentant une certaine porosité intragranulaire, soit de matériaux hybrides où un cation organique interagit avec GeS2. / The controlled elaboration of nanostructured chalcogenides with high specific area or functionalized surface is an interesting challenge. Breakthrough in various domains such as catalysis, gas separation, electrochemistry, photovoltaics or optics can be achieved by the production of chalcogenide materials with functionalized surface or high specific area coupled with high polarisability.The aim of the thesis was to develop new soft chemistry routes for the synthesis of germanium disulfide at room temperature and pressure. Two sulfur precursors, i.e. hydrogen sulfide (H2S) and thioacetamide, and a germanium precursor, the tetraethoxigermanium were used for the syntheses. The syntheses were carried out either in the presence or in the absence of a template, in most case an ionic liquid (IL).Syntheses without templating agent led to amorphous or nano-organized GeS2 nanoparticles of 20 to 35 nm in diameter and interesting specific areas (320 m2.g-1 with H2S, 270 m2.g-1 with thioacetamide). Hybrid materials comprising GeS2 and LI cation with a general formula 0.2GeS2-0.8 organic cation were obtained in the presence of IL. The obtained particles of nanometric sizes and with hardly any specific area have a morphology that depends on the nature of the organic cation present during the synthesis, i .e. spheres or gypsum rosette-like particles. XPS measurements indicate the presence of Ge-S- bonds in the hybrid material. The use of lithium de bis(trifluorométhanesulfonyl)imide led to the elaboration of a GeS2-Li material which conductivity of ~10-10 S.cm-1 is that of an ionic salt.A first iono-chalcogel which could lead after optimization to a porous chalcogenide has been elaborated when using the IL as both the solvent and the templating agent and in the absence of any other solvent. The use of hexadecilamine (HDA) above its critical micellar concentration, led to hybrid nanoparticles of 15 nm in size with interesting specific area (130 m2.g-1) but also intra-granular porosity.In conclusion, this exploratory work led to the elaboration of GeS2 either as naoparticles with high specific area or particles with intragranular porosity or finally hybrid materials with GeS2 interacting with an organic cation, the final product depending upon the chosen soft chemistry route.Keywords: chalcogenide, ionic liquid, organic-inorganic hybrid, morphology, soft chemistry

A new numerical analysis method, dispersion vs. absorption plots (DISPA), has been developed for ESR. This method may be used for semi-quantitative line-shape studies and is useful both as a diagnostic and analytical tool. In addition it provides a method of automatic phasing for magnetic resonance spectra. Numerous examples of its applications, both simulated and experimental are presented, with emphasis on spin-probe studies. The digital acquisition and processing methods used for these studies are also briefly discussed. ESR and NMR relaxation time studies of the bis(dialkyl-N-carbodithioate) metal(II) class of spin-probes have been performed. The T₁,'s of ¹³C and ²H enriched nickel complex were measured by NMR. The line-widths of ⁶³Cu complex were measured by ESR and analysed by Redfield theory. The two sets of results were combined to give the principal elements of the rotational diffusion tensor for the pyrollidine derivative in toluene. This is the first time that ESR and NMR studies have been combined to measure a diffusion tensor. A general strategy for this approach is presented. ESR data from previous work has been re-analysed in the light of the new results. The analysis shows that the commonly used assumption of isotropic diffusion is extremely misleading. / Science, Faculty of / Chemistry, Department of / Graduate

Orientador: Maria Regina Wolf Maciel / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-18T13:50:07Z (GMT). No. of bitstreams: 1 JaimesFigueroa_JaiverEfren_M.pdf: 4284661 bytes, checksum: 5b7383def90a5143160bc892b406c75c (MD5) Previous issue date: 2011 / Resumo: A produção de etanol a partir da cana de açúcar é uma tecnologia dominada completamente pelo Brasil porém, encontra-se na etapa de intensificação, otimização e inovação. O etanol pode ser produzido como hidratado ou anidro, sendo necessário, para produção deste último, um processo posterior de desidratação. Existem inúmeros processos de desidratação, dentre dos quais a destilação extrativa é um dos mais simples de realizar. A destilação extrativa usa um solvente para modificar o equilíbrio líquido-vapor, permitindo quebrar o azeótropo etanol/água que impede que a desidratação seja feita por destilação convencional. O solvente de extração é de grande importância, dele depende a facilidade com que vai ser feita a separação, a quantidade a ser utilizada e o requerimento energético do processo. Nesse contexto, aparecem os líquidos iônicos, que são apresentados como ótimos solventes potenciais de extração; um líquido iônico (LI) é um sal composto por um cátion orgânico com pelo menos uma carga deslocada e um ânion inorgânico; sua estrutura evita que se forme uma rede cristalina estável, resultando em solventes líquidos altamente iônicos com temperaturas de fusão inferiores a 100 °C e com insignificante pressão de vapor. Os LI são principalmente usados em substituição aos solventes convencionais, podendo ser uma alternativa para diminuir a poluição ambiental, evitando a emissão de componentes orgânicos voláteis ao meio ambiente. Com a justificativa anterior, o objetivo desta dissertação foi analisar e otimizar o processo de obtenção de etanol anidro a partir da mistura etanol + água de composição pré-azeotrópica, empregando líquidos iônicos (LI), visando avaliar seu potencial; os LI estudados foram: 1-butil-3-metilimidazólio cloreto, 1-butil-3-metilimidazólio metilsulfato, 1-butil-3-metilimidazólio acetato, 1-butil-3-metilimidazólio tetrafluoroborato, 1-butil-3-metilimidazólio dicianamida, 1-etil-3-metilimidazólio cloreto, 1-etil-3-metilimidazólio tetrafluoroborato, 1-hexil-3-metilimidazólio cloreto. Neste trabalho foi encontrado o requerimento energético e a quantidade de LI a ser empregado para obter os valores máximos de pureza e porcentagens de recuperação de etanol e água. A influência das condições de operação e desenho utilizadas, tais como fração de etanol na alimentação, relação LI:alimentação, temperatura da alimentação e do LI de reposição, quantidade de estágios, relação molar de refluxo, estágio de alimentação e vazão molar de destilado da coluna de recuperação de etanol e de purificação de LI, foram analisadas empregando o simulador comercial Aspen Plus e, otimizadas empregando a técnica de delineamento de experimentos. Todos os LI estudados apresentaram capacidade de desidratar o etanol, elevando sua concentração de pré até pós-azeotropia, obtendo-se pureza de etanol maiores que 0,995 em massa. Além disso, dependendo do LI utilizado, o processo atinge porcentagens de recuperação de etanol e água, em média, de 98% e 74%, respectivamente. Na definição do modelo para o coeficiente de atividade do equilíbrio ternário líquido vapor da mistura etanol + água + LI foram testados o NRTL e UNIQUAC, chegando-se à conclusão de que o equilíbrio representado pelo modelo de NRTL é o mais adequado / Abstract: The production of ethanol from sugar cane is a technology led and dominated by Brazil. However, it is still in a stage of optimization and innovation. Ethanol can be produced in a hydrated or dehydrated state, but the latter requires an additional process to the conventional distillation. There are numerous dehydration processes that can be implemented, but the extractive distillation is one of the most simple. Extractive distillation uses a solvent that modifies the liquid-vapor equilibrium and eliminates the presence of the ethanol-water azeotrope that prevents the use of conventional distillation for the dehydration process. The solvent for the extraction is of great importance since it dictates the degree of separation and the energy requirements for the process. In this context, ionic liquids are considered since they have been presented as excellent solvents for extraction. An ionic liquid (IL) is a salt formed by an organic cation with at least one delocalized charge, and an inorganic anion. The structure of the ionic liquids prevents the formation of a stable crystalline net, resulting in highly ionic liquid solvents that have melting points below 100 ºC and negligible vapor pressures. With those characteristics, ionic liquids can be a replacement for conventional solvents offering alternatives for the decrease of the environmental impact by preventing the emissions of volatile compounds to the environment. With the previous justification, the objective of this master dissertation was to analyze and optimize the process of obtaining anhydrous ethanol from a mixture ethanol + water with pre-azeotropic composition by using ionic liquids; and also to evaluate their performance in this application to evaluate its potential. Ionic liquids were studied: 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium methylsulfate, 1-butyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium dicyanamide, 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-hexil-3-methylimidazolium chloride. In this work, the minimum energy requirement and the amount of ionic liquid needed to obtain maximum ethanol purity and maximum recovery of ethanol and water exiting the process were found. The influence of the design and operation conditions used, such as the ethanol composition in the feed, the IL/feed ratio, the temperature of the feed and the IL, the number of plates, the reflux molar ratio and the distilled flux in the columns of purification of ethanol and recovery of ionic liquids were studied using the commercial simulator ASPEN PLUS, and optimized by utilization of the design of experiments (DOE) technique. All the ionic liquids used were able to dehydrate the ethanol, increasing its concentration from pre to post azeotrope, generating ethanol with purity above 0.995 in mass. In addition to that, depending on the ionic liquid used, the process reached average water and ethanol recoveries of 98% and 74% respectively. In the definition of the model for the activity coefficient in the ternary vapor-liquid equilibrium of the ethanol-water-IL mixtures, the models NRTL and UNIQUAC were studied concluding that the NRTL model was the most adequate / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química

In this dissertation, three aspects about surface and interface engineering of conjugated polymers and nanomaterials will be discussed. (i) There is a significant promise for electroactive conjugated polymers (ECPs) in applications of electrochemical devices including energy harvesting, electrochromic displays, etc. Among these, ECPs has also been developed as electroactive materials in electrochemical supercapacitors (ESCs). Compared with metal oxides, ECPs are attractive because they have good intrinsic conductivity, low band-gaps, relatively fast doping-and-undoping process, the ease of synthesis, and tunable electronic and structural properties through structural modifications. Here, Multiple-branch-chain 3,4-ethylenedioxythiophene (EDOT) derivatives was designed as crosslinkers in the co-electropolymerization of EDOT to optimize its morphology and improve the cycling stability of PEDOT in the supercapacitor applications. High-surface-area π-conjugated polymeric networks can be synthesized via the electrochemical copolymerization of the 2D (trivalent) motifs benzo[1,2-b:3,4-b’:5,6-b’’]trithiophene (BTT) and tris-EDOT-benzo[1,2-b:3,4-b’:5,6-b’’]trithiophene (TEBTT) with EDOT. Of all the material systems studied, P(TEBTT/EDOT)-based frameworks achieved the highest areal capacitance with values as high as 443.8 mF cm-2 (at 1 mA cm-2), higher than those achieved by the respective homopolymers (PTEBTT and PEDOT) in the same experimental conditions of electrodeposition (PTEBTT: 271.1 mF cm-2 (at 1 mA cm-2); PEDOT: 12.1 mF cm-2 (at 1 mA cm-2). (ii) In electrochemical process, the suitable choice of appropriate electrolytes to enlarge the safe working potential window with electrolyte stability is well known to improve ECPs’ performance in ESCs applications. Ionic liquids (ILs) are ion-composed salts and usually fluid within a wide temperature range with low melting points. There are many unique characteristics for these intrinsic ion conductors, including high ionic conductivity, wide electrochemical voltage windows in neutral conditions, fast ion mobility in redox reaction process (>10-14 m2 V-1 s-1), low vapor pressure, and environmental stability. These properties qualified ambient-temperature ILs to be applied as supporting medium for various devices and materials processing applications in both industry and academia, overcoming the limitation of volatile organic compounds (VOCs). Especially, ILs have been utilized as superior medium to electrodeposit metals, alloys, semiconductors and ECPs in the application of supercapacitors. Electropolymerization of EDOT and its derivative 4,4'-dimethoxy-3,3'-bithiophene (BEDOT) have been studied in three kinds of imidazolium-based ionic liquids and conducting salt in VOCs with different anions both as the growth medium and the supporting electrolyte, to assess the influence of these anions on their morphology and electrochemical activity. It is found these thiophene polymers grown in ILs with higher viscosity and lower diffusion shows much slower growth rate and orderly morphologies than in Tetrabutylammonium hexafluorophosphate (TBAPF6) dissolved in acetonitrile (ACN), and gives better electrochemical performance via cyclic voltammetry (CV) and galvanostatic charge-and-discharge (CD) studies. Polymers displayed multiple redox peaks in several cases, the possible reasons and origins are discussed. The synthesized polymer can be affected greatly by both the ILs with different anion/cation, and its mutal interation with targeted monomer.. As far as known, there is no systematic study on how the anions of ILs and common organic solution could play a role as a medium both for polymerization and post-polymerization electrolyte for PEDOT and its derivatives. This study can be used as an easy reference and provide experimental diagnositc data when selecting ionic liquids to investigate and optimize thiophene-based electrochemical systems, such as batteries and supercapactiors. (iii) Another aspect about interface chemistry of direct functionalization of nanodiamond with maleimide has also been addressed. Functional nanodiamonds are promising candidates for extensive practical applications in surface science, photonics and nanomedicine. Here, a protocol of direct functionalization is described by which maleimide-derivatized substituents can be appended to the outer shell of thermally annealed nanodiamonds through Diels-Alder reaction. This protocol can be carried out in room temperature, ambient atmosphere, without catalyst, and provide functionalized nanodiamonds with good solubility in organic solution. Also, this method can be applied for other maleimide derivatives,e.g.m aleimide-fluorescene, which can be applied in fluorescence labeling, sensing, and drug delivery. A series of techniques, especially Fourier transform infrared spectroscopy (FTIR), and Solid State Nuclear Magnetic Resonance (SS-NMR) was conducted for the analysis of surface chemistry and the investigation of the two-point binding strategy in details.

Electrical insulating liquids, organic esters, conductivity, dielectric, permittivity

This work uses high-speed video imaging to study the formation of filaments, during impact and rebounding of drops with polymer additives. We use PEO of different concentrations from 10 to 1000 ppm and study how drops rebound from various different surfaces: superhydrophilic, hydrophilic, hydrophobic, and superhydrophobic. Bouncing occurs for all surfaces at low impact velocities. We specifically focus on the phenomenon of the generation of polymer filaments, which are pulled out of the free surface of the drop during its rebounding from micro-pillared or rough substrates. We map the parameter regime, in terms of polymer concentration and impact Weber number, where the filaments are generated in the most repeatable manner. This occurs for regularly pillared surfaces and drops of 100 ppm PEO concentrations, where numerous separated filaments are observed. In contrast, for superhydrophobic coatings with random roughness the filaments tend to merge forming a branching structure. Impacts on inclined surfaces are used to deposit the filaments on top of the pillars for detailed study.

No description available.

No description available.