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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Development and Characterization of Ethanol-Compatibilized PPO-Based EPMM Membranes

Wang, Qiang January 2011 (has links)
Emulsion polymerized mixed matrix (EPMM) membranes is a new category of membranes, which incorporate silica-based inorganic nanoparticles dispersed in continuous phase of an organic polymer. The uniqueness of the EPMM membranes comes from the fact that they may combine otherwise incompatible inorganic and organic phases. This is achieved by the synthesis of the inorganic nanoparticles from a silica precursor in a stable emulsion, in which an aqueous phase is dispersed in a continuous phase of the polymer solution. More specifically, the silica precursor soluble in the polymer solution polymerizes in contact with the aqueous phase, and consequently the latter acts as finely dispersed micro reactors. The objective of this work was to optimize the previously developed protocol for the synthesis of poly (2,6-dimethyl-1,4pheneylene oxide) (PPO) based EPMM membranes, and to characterize their physical and gas transport properties. In particular, the effects of inorganic loading and the membrane post-treatment protocol on the permeability and selectivity of the membranes were of interest. However, the results showed that the obtained permeation and separation were virtually not affected by the theoretical Si loading and the post-treatment protocol. Moreover, in comparison to the base PPO membranes, the observed O2 permeability and the O2/N2 permselectivity have generally decreased. The differential scanning calorimetry (DSC) analysis of the synthesized membranes showed an important scatter of the glass transition temperatures (Tg) of the EPMM membranes with the values generally lower than the Tg of the base PPO. Moreover, the inductively coupled plasma mass spectrometry (ICP-MS) showed the silica content in selected EPMM membranes to be far below the expected theoretical level. This, in combination with the 29Si nuclear magnetic resonance (29Si NMR) results, showed that most of the already low silica content comes from the unreacted silica source (tetraethylorthosilicate) and have led to the second phase of the project in which a modified synthesis protocol has been developed. The major differences of the modified protocol compared to the original one include the replacement of a surfactant, 1-octanol, by ethanol and using greater concentrations of the reactants. To study the effect of different parameters involved in the synthesis protocol, a Gravimetric Powder experiment, in which the inorganic polymerization is carried out in an emulsion with a pure solvent rather than a polymer solution, has been designed. The Gravimetric Powder experiments have confirmed polymerization of tetraethylorthosilicate (TEOS) in the emulsion system. Using the conditions, which resulted in the maximum production of the polymerized TEOS in the Gravimetric Powder experiments, one set of new EPMM membranes has been synthesized and characterized. The new EPMM membranes have the Tg of 228.2oC, which is distinctly greater compared to the base PPO, and contain one order of magnitude more of silica compared to the old EPMM membranes. More importantly, the 29Si NMR analysis has proven that the silica content in the new EPMM membranes originates from the reacted rather than unreacted TEOS. Interestingly, the observed conversion of TEOS in the new EPMM membranes, exceeding 20%, is greater than the largest conversion in the Gravimetric Powder experiments. The oxygen permeability in the new EPMM membrane of 33.8 Barrer is more than twice that of the base PPO membrane. Moreover, this increase in O2 permeability is associated with a modest increase in the O2/N2 permselectivity (4.75 versus 4.67).
12

Démonstrateurs des potentialités applicatives des clustomésogènes / Clustomesogen containing demonstrative devices

Prévôt, Marianne 18 December 2014 (has links)
Les clustomésogènes sont une nouvelle classe de cristaux liquides hybrides multifonctionnels découverts dans l'équipe CSM de l'Institut des Sciences Chimiques de Rennes en 2008. Ils sont constitués d'un cœur inorganique - des clusters de métaux de transition - auquel sont associés, de manière covalente ou électrostatique, des ligands organiques pro-mésogéniques. Ces matériaux hybrides associent les propriétés d'auto-assemblage des cristaux liquides aux propriétés intrinsèques des clusters métalliques. Le présent travail s'articule autour de clustomésogènes contenant des clusters octaédriques de molybdène, phosphorescents dans le rouge-proche infra-rouge, et aux rendements quantiques compris entre 10% et 50%. Ils sont synthétisés par approche ionique en vue de leur intégration dans des dispositifs optiques. La démarche consiste à rationaliser les relations structures-propriétés afin de contrôler l'arrangement des clustomésogènes à l'échelle nanométrique. Nous créons ainsi des états nématiques sur de larges gammes de température. Le transfert de ces systèmes dans des cellules électro-optiques est renforcé par leur miscibilité dans un certain nombre de cristaux liquides commerciaux. La nature et la concentration de ces derniers permet l'ajustement des températures de fonctionnement et le contrôle de la viscosité de l'état cristal-liquide. Nous montrons qu'il est possible de faire commuter l'intensité de photoluminescence des clustomésogènes de 50% par l'application d'un champ alternatif à la manière des systèmes d'affichage. L'intégration au sein de diodes électroluminescentes constitue le dernier volet de ce travail. La maîtrise de leur structure permet d'envisager leur potentiel dans des dispositifs d'éclairage. L'ensemble de ces études ouvre la voie aux clustomésogènes de molybdène comme alternative réaliste aux émetteurs inorganiques rouges actuels. / Clustomesogens are a new class of hybrid liquid crystals developed since 2008 in our laboratory. They are a combination of an inorganic core, namely transition metal clusters, linked with promesogenic organic ligands through covalent or electrostatic interactions. These hybrid materials associate liquid crystals self-assembling abilities to the metallic clusters intrinsic properties. This work present octahedral molybdenum cluster based clustomesogens, emitting, through phosphorence mechanisms, in the deep red area and exhibiting 10% to 50% quantum efficiency. These materials are produced via an ionic approach by replacing the alkali cations of the ternary solid state compounds with tailored promesogenic organic ones. The ambition of this work is to rationalize the structures-properties relationship to control, at the nanometric scale, the clustomesogens organization. This approach allows us to observe nematic liquid crystalline phases over a wide range of temperatures. As these compounds are miscible with commercial nematic liquid crystals, we could envision their use as emissive species in the design of electroswitchable luminescent liquid crystal cells. By changing the type and concentration of commercial liquid crystals, we could adjust the operating temperature range as well as the viscosity of the mixture. We also establish that it is possible to modulate the clustomesogens' photoluminescence by 50% by applying an alternative electric field, as in display devices. In the last part of this work, we study the integration of clustomesogens as the emissive species into electroluminescent diodes. Being able to control their structure should allow their use in lighting devices. These works pave the way for using Molybdenum clustomesogens as an alternative to inorganic compounds presently used as red light emitters.
13

Development of Functional Materials Based on Polyhedral Oligomeric Silsesquioxane with Flexible Side-Chains / 柔軟性側鎖を有するかご型シルセスキオキサンを基盤とした機能性材料の創出

Narikiyo, Hayato 23 March 2021 (has links)
付記する学位プログラム名: 充実した健康長寿社会を築く総合医療開発リーダー育成プログラム / 京都大学 / 新制・課程博士 / 博士(工学) / 甲第23227号 / 工博第4871号 / 新制||工||1760(附属図書館) / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 田中 一生, 教授 秋吉 一成, 教授 古賀 毅 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM
14

Métallophosphates bidimensionnels luminescents et magnétiques : relation structure-propriétés / Luminescent and magnetic two-dimensional metal phosphonates : structure-properties relationships

Bloyet, Clarisse 16 November 2018 (has links)
Ce travail de thèse concerne l’étude de nouveaux matériaux hybrides organiques-inorganiques lamellaires magnétiques et luminescents synthétisés par voie hydrothermale. Ces matériaux ont été obtenus à partir de sels de métaux de transition de configuration électronique 3d (Cu2+, Co2+, Mn2+, Zn2+) et de molécules organiques de basse symétrie constituées d’au moins un acide phosphonique greffé sur une plateforme rigide aromatique (phényle ou naphtalène). Le choix du cation métallique ainsi que l’ajout d’autres fonctions (halogène : F, Cl, Br, I, acide carboxylique ou méthyle) sur ces systèmes cycliques ont conduit à des matériaux hybrides bidimensionnels aux architectures et propriétés physiques (luminescence, magnétisme et/ou couplage magnétoélectrique) diverses. La compréhension du lien entre les propriétés structurales et physiques de ces métallophosphonates ouvre la voie vers la conception de nouveaux matériaux multifonctionnels originaux. / This PhD work deals with the study of new lamellar magnetic and luminescent organic-inorganic hybrid materials synthesized by hydrothermal process. These materials were obtained from 3d transition metal salts (Cu2+, Co2+, Mn2+, Zn2+) and low symmetric organic molecules bearing at least one phosphonic acid function grafted onto a rigid aromatic platform (phenyl or naphthalene). The choice of the metal cation as well as additional functions (halogen: F, Cl, Br, I, carboxylic acid or methyl) on these cyclic systems led to two-dimensional hybrid materials with various architectures and physical properties (luminescence, magnetism and/or magnetoelectric coupling). Understanding the interconnections between the structural and physical properties of these metal phosphonates paves the way for the design of novel multifunctional materials.
15

Vrstevnaté hydroxidy přechodných kovů, jejich delaminace a vlastnosti / Layered Transition Metal Hydroxides: Delamination and Properties

Hyklová, Barbora January 2018 (has links)
Charles University Faculty of Science Study programme: Inorganic Chemistry Mgr. Barbora Hyklová Layered Transition Metal Hydroxides: Delamination and Properties Extended abstract Supervisor: Ing. Kamil Lang CSc., DSc. Supervisor-Consultant: RNDr. Jan Demel PhD. Prague, 2017 Layered transition-metal hydroxides have attracted increasing attention as promising active electrode materials for electrochemical energy storage and conversion device due to facile preparation and modification, good tunability, high capacitance capability, fast reversible redox reactions, and cost effectiveness. Many reported hierarchical architectures based on nickel and cobalt hydroxides are composed of bulky nanoplatelet-like aggregates; however, the nanomorphology and behavior of the separated hydroxide nanosheets is much less known. Figure 1. Scheme of layered nickel or cobalt hydroxide delamination and subsequent restacking on conductive HOPG support. In this respect, the dissertation thesis reports characterization and electrochemical performance of nickel, nickel-cobalt, and cobalt hydroxide nanosheets, synthesized by an economical and environmentally friendly method based on delamination of corresponding layered hydroxides in water (Figure 1). For this purpose, lactate and nitrate layered hydroxides were prepared by two...
16

Hybridní materiály se zlepšenými termomechanickými vlastnostmi / Hybrid materials with improved thermomechanical properties

Perchacz, Magdalena January 2017 (has links)
Epoxy resins have been broadly used in the industry for adhesives, laminates, coatings, composites, encapsulation of electronic devices, printed circuit boards, etc. Despite their excellent adhesion to different materials, heat and chemical resistance and good mechanical properties, they also exhibit few drawbacks like brittleness, high thermal expansion coefficient (CTE), poor resistance to crack initiation and growth. Therefore, the thesis is focused on the preparation of epoxy-silica hybrid materials exhibiting improved thermomechanical properties compared to the neat epoxides, without impairing their beneficial features. The main synthetic route of epoxy-silica hybrids' preparation has been the sol-gel process of alkoxysilanes, allowing either in-situ formation of high purity and homogeneity silica particles or creation of various siloxane structures in a form of liquid (sol) silica-based precursors. The sol-gel method, on one hand, helps to omit too high viscosity of nanofiller suspension and energy-intensive nanofiller dispergation problems, but on the other hand, is often associated with necessity to use solvents and to remove formed volatiles. Therefore, in the first part of the thesis, a simple solvent-free sol-gel procedure, enabling to minimize the side-effect of solvent evaporation and...
17

Domov bezdomovců: sociální konstrukce nekonvenčního domova / .Home of Homeless: Social Construction of Non-conventional Home

Kotyk, Lukáš January 2016 (has links)
This diploma thesis focuses on the phenomena of homelessness as a situation in which individuals do not have enough money to secure the conventional accommodation. This leads to them constructing their home in the public space or squatting abandoned buildings. This thesis refuses to interpret homelessness as a pathological phenomenon or as a violation of order (in order to demonstrate this, individual approaches are usually being used). The author of the thesis presents homelessness as a consequence of the economic system which orders out a certain part of population. This part cannot attain the minimum measure of the chance to consume which would sustain a secure life. The concept of hybrid, which is the integral part of the actor-network-theory and it originates in the works of Bruno Latour, allows us to interpret home through the interconnection of material objects and social relationship. This approach leads to disengagement from the atypical form of unconventional homes and to thinking about them as about a normal way of housing. The basis of the ethnographic research is the perspective of the material culture studies. In the framework of this perspective, individual dwellings (inhabited by the class of the poorest) are examined. The research contains an analysis of nine such dwellings in...
18

Manufacturing and Applications of Carbon Nanotube Sheet and Thread

Chauhan, Devika 30 October 2018 (has links)
No description available.
19

Development of artificial biomembrane vesicles for nano-DDS based on organic-inorganic hybrid materials / 有機-無機ハイブリッド材料に基づくナノDDSのための人工生体膜小胞の開発

Mizuta, Ryosuke 23 March 2023 (has links)
京都大学 / 新制・課程博士 / 博士(工学) / 甲第24586号 / 工博第5092号 / 新制||工||1975(附属図書館) / 京都大学大学院工学研究科高分子化学専攻 / (主査)教授 秋吉 一成, 教授 大塚 浩二, 教授 田中 一生 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM
20

Design, Synthesis and Self-assembly of Polyhedral Oligomeric Silsesquioxane (POSS) Based Hybrid Materials

Bo, Ni 24 May 2018 (has links)
No description available.

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