In this work we investigate the reaction propagation velocity of aluminum and copper oxide Metastable Intermolecular Composites (MIC's). All samples were deposited in a magnetron sputtering system using 2 aluminum targets and 2 copper targets. The copper is sputtered in an oxygen rich environment in order to obtain copper oxide rich films. Three different layer structures are used for various measurements that are composed of alternating 20 layer pairs, 30 layer pairs, and 40 layer pairs. All layer pairs maintain a constant total thickness of 3.2 microns. Each layer structure can be prepared independent of a substrate and is measured with the use of photodiodes or with direct device contact. Aluminum and copper oxide structures have potential use as propellants and additives to explosives, thus, accurate propagation velocity or burn rate measurements are important. The developed measurement system for burn rate measurements of Al/CuO MIC's can achieve and accuracy of 0.1 m/s. In order to determine the velocity limiting characteristics, MIC's on glass and silicon substrates were measured as well as free standing Al/CuO MIC's. Separate burn rate measurement devices were created in order to handle the variety of substrates. In addition, the ignition energy of the Al/CuO MIC was studied to further characterize the samples. This was done using both voltage and current probes of a reacting sample. Rutherford backscattering spectroscopy (RBS) was used for sample composition calibration. The pre- and post-reaction Al/CuO MIC's were also characterized by transmission electron microscopy (TEM).

No description available.

An alternative indirect integration regime of porous low-k materials was investigated. Based on a single Damascene structure the intra level dielectric SiO2 or damaged ULK was removed by using HF:H2O solutions to create free standing metal lines. The free spaces between the metal lines were refilled with a spin-on process of a low-k material. The persistence of barrier materials and copper against HF solutions, the gap fill behavior of the used spin on glass on different structure sizes and the main challenges which have to solve in the future are shown in this study.

L'oxydation spontanée de la dopamine en solution légèrement basique a été étudiée sur la base de la publication de Lee [Science, 318:426-430, 2007], et le produit de la réaction a été identifié comme de la mélanine. La capacité de la mélanine de lier des groupements amines de façon covalente a été confirmée par la quantification des sites de liaison correspondants. En outre il est possible de rédisperser des agrégats de mélanine dans des solutions fortement basiques. Les grains de mélanine ainsi obtenus ont été utilisés pour construire des films multicouches avec le poly(diallyldimethyl ammonium) (PDADMA). Différentes méthodes d'oxydation de la dopamine pour former des films de mélanine à l'interface solide-liquide ont été développées. Toutes les méthodes mènent à la formation de films continus de mélanine ayant des morphologies de surface similaires. Elles deviennent imperméables à des sondes électrochimiques à partir d'une épaisseur de l'ordre de 10 nm. Une plus grande perméabilité à des sondes chargées positivement ou neutres qu'à des sondes négatives a été confirmée. L'adsorption de protéines à des revêtements de mélanine a été expliquée par une combinaison d'interactions électrostatiques et covalentes. Pour arriver à cette explication le potentiel zêta de dépôts de mélanine a été mesuré en fonction du pH. La formation de la mélanine dans des films multicouches de poly(L-lysine) (PLL) et de hyaluronate (HA) a été étudiée: la mélanine est capable de remplir des films (PLL-HA)n de manière homogène, et les composés ainsi obtenus peuvent être détachés de leurs substrats comme membranes autosupportées préparées par une méthode biomimétique sous conditions douces.

In the present work, we study the effects of external fields and surfaces on liquid-crystalline systems. Initially, we investigate the effects caused by the addition of ferroelectric nanoparticles in a nematic liquid crystal. Using the technique of molecular dynamics simulation, we estimate the density of liquid crystal molecules, the orientational order parameter, and the polar and azimuthal angle profiles as a function of the distance to the center of the immersed nanoparticle for different temperatures of the system. We observe that the presence of ferroelectric nanoparticles enhance the nematic order of the liquid-crystalline medium changing many properties above the transition temperature Tn — Iso. In the second moment, we determine the interaction mediated by elastic deformations between colloidal nanoparticles adsorbed on the surface of free-standing smectic films. In these films, the elastic-mediated force between the adsorbed particles have a long-range character, which contrasts with the character of short-range in films on a solid substrate. The study of phase transitions and critical phenomena in free-standing smectic films has been a subject of many theoretical and experimental works. The McMillan-Miranstsev mean-field approach was used to show that the additional orientational order imposed by the surface anchoring stabilizes the surface-induced smectic siSmA and nematic N phases, leading to he collapse of the tricritical point and to the emergence of a critical end point. Usually strongly anchored free-standing smectic exhibit a stepwise reduction in the thickness when the temperature is raised above the smectic-isotropic bulk transition temperature. In this study, we demonstrate that a layer trinning transition, induced by and external field, can occur in smectic films with negative dielectric anisotropy even below the bulk transition temperature. Using an extended McMillian's model, we show that when the field increases above the bulk transition field, the film thickness reduction is well described by a power law. / Conselho Nacional de Desenvolvimento Científico e Tecnológico / No presente trabalho, estudamos os efeitos de superfícies e campos externos em sistemas líquido-cristalinos. Inicialmente, investigamos os feitos causados pela adição de nanopartículas ferroeléticas em um cristal líquido nemático. Utilizando a técnica de simulação por dinâmica molecular, estimamos a densidade de moléculas do cristal líquido, o parâmetro de ordem orientacional e os perfis dos ângulos polar e azimutal em função da distância ao centro da nanopartícula imersa. Foram consideradas diferentes temperaturas do sistema. Pudemos observar que a presença das nanopartículas ferroelétricas favorece a ordem nemática do meio líquido-cristalino, alterando muitas propriedades do meio acima da temperatura de transição Tn-Iso. Num segundo momento, determinamos a interação, mediada por deformações elásticas, entre nanopartículas coloidais adsorvidas em filmes esméticos livremente suspensos. Nesses filmes, a força de interação entre as partículas adsorvidas tem um caráter de longo alcance, o que contrasta com o comportamento de curto alcance em filmes sobre um substrato sólido. O estudo das transições de fase e fenômenos críticos em filmes esméticos livremente suspensos têm sido objeto de estudo de vários trabalhos teóricos e experimentais. Dentro desse contexto, nós estudamos a transição de fases esmética-nemática (SmA — N) que ocorre no centro de um filme livremente suspenso sujeito a um forte ancoramento superficial, promovido pelo gás ao seu redor. A aproximação de campo médio de McMillan-Mirantsev foi utilizada para mostrar que a ordem orientacional, imposta pelo ancoramento superficial, estabiliza as fases esmética induzida pela superfície (siSmA) e nemática (N), levando ao colapso do ponto tricrítico e ao aparecimento de um ponto crítico terminal. Usualmente, filmes esméticos livremente suspensos e fortemente ancorados apresentam uma redução camada por camada na espessura quando a temperatura aumenta acima da temperatura da transição esmético-isotrópico. Nesse trabalho, nós demostramos que uma transição por redução de camadas, induzida por um campo externo, pode ocorrer em filmes esméticos com anisotropia negativa, mesmo em temperaturas abaixo da temperatura de transição do bulk. Utilizando o mesmo modelo extendido de McMillan, nós mostramos que quando o campo cresce acima do valor do campo crítico, a redução da espessura do filme é bem descrita por uma lei de potência.

La technique d'auto-assemblage couche par couche de polyélectrolytes, permettant de construire des films appelés « multicouches », s'est grandement développée au cours des deux dernières décennies. Cette technique permet non seulement de modifier des surfaces de matériaux mais également d'élaborer des membranes auto-supportées. Dans cette thèse, j'ai étudié la croissance de deux systèmes multicouches assemblés dans des conditions extrêmes de pH pour accélérer leur croissance. Les films à base de poly(ethylene imine) et d'acide poly(acrylique) ont été utilisés pour réaliser, d'une part, des membranes possédant une capacité à répondre à l'humidité, et d'autre part, des membranes asymétriques présentant des propriétés anti-bactériennes. Les films à base de poly(L-lysine) et de hyaluronane ont été réalisé par croissance amplifiée par le pH, et l'effet du poids moléculaire du HA sur la croissance et les propriétés interne des films a été étudié. Ces films ont servi de réservoir pour le piégeage de précurseurs métalliques, qui ont ensuite été réduit in situ par irradiation UV, afin de former des nanoparticules. Ainsi, des films nanocomposites contenant des particules d'argent et des particules d'or ont été synthétisés. / Layer-by-layer assembly has witnessed great development during the two last decades and has expanded its application from surface modification to membrane construction. In this thesis, I studied the buildup of layer-by-layer films assembled at extreme pH (i.e. pH-amplified). I first focused on the fabrication of free-standing film made of poly(ethylene imine) and poly(acrylic acid). An application was to use these films as humidity sensors and a second one was to load silver ions in the films to create anti-bacterial membranes. Then, I worked on poly(L-lysine)/hyaluronan films and I investigated the effect of HA molecular weight on film growth and internal properties. Finally, nanocomposites were made via in situ synthesis of metal NPs in (PLL/HA) films: silver NP loaded (PLL/HA) free-standing films were constructed and their mechanical properties were tested; well dispersed gold NPs with sizes ranging from ~2 nm to ~9 nm were synthesized in (PLL/HA) films.

No description available.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第24873号 / 理博第4983号 / 新制||理||1711(附属図書館) / 京都大学大学院理学研究科化学専攻 / (主査)教授 北川 宏, 教授 有賀 哲也, 教授 堀毛 悟史 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

No description available.

Nanostructured porous materials generally, and nanoporous noble metals specifically, have received considerable attention due to their superior chemical and physical properties over nanoparticles and bulk counterparts. This dissertation work aims to develop well-established strategies for the preparation of multifunctional nanostructured porous materials based on the combination of inorganic-chemistry, organic-chemistry and electrochemistry. The preparation strategies involved one or more of the following processes: sol-gel synthesis, co-electrodeposition, metal ions reduction, electropolymerization and dealloying or chemical etching. The study did not stop at the preparation limits but extended to investigate the reaction mechanism behind the formation of these multifunctional nanoporous structures in order to determine the different factors controlling the nanoporous structures formation. First, gold-silica nanocomposites were prepared and used as a building blocks for the fabrication of high surface area gold coral electrodes. Well-controlled surface area enhancement, film thickness and morphology were achieved. An enhancement in the electrode’s surface area up to 57 times relative to the geometric area was achieved. A critical sol-gel monomer concentration was also noted at which the deposited silica around the gold coral was able to stabilize the gold corals and below which the deposited coral structures are not stable. Second, free-standing and transferable strata-like 3D porous polypyrrole nanostructures were obtained from chemical etching of the electrodeposited polypyrrole-silica nanocomposite films. A new reaction mechanism was developed and a new structural directing factor has been discovered for the first time. Finally, silver-rich platinum alloys were prepared and dealloyed in acidic medium to produce 3D bicontinuous nanoporous platinum nanorods and films with a nanoporous gold-like structure. The 3D-BC-NP-Pt displayed high surface area, typical electrochemical sensing properties in an aqueous medium, and exceptional electrochemical sensing capability in a complex biofouling environment containing fibrinogen. The 3D-BC-NP-Pt displayed high catalytic activity toward the methanol electro-oxidation that is 30 times higher that of planar platinum and high volumetric capacitance of 400 F/cm3. These findings will pave the way toward the development of high performance and reliable electrodes for catalysis, sensing, high power outputs fuel cells, battery-like supercapacitors and miniaturized device applications.