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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.
221

Ordered Structures from Nanoparticles/Block Copolymer Hybrids: Ex-situ Approaches toward Binary and Ternary Nanocomposites

Horechyy, Andriy 28 July 2011 (has links) (PDF)
Within the field of modern technology, nanomatrials, such as nanoparticles (NP), nanorods (NR), quantum dots (QD) etc. are, probably, the most prominent and promising candidates for current and future technological applications. The interest in nanomaterials arise not only form the continuous tendency towards dimensions minimisation of electronic devices, but also due to the fact, that new and, often, unique properties are acquired by the matter at the length scale between 1 and 100 nm. The ability to organize nanoparticles into ordered arrays extends the range of useful NP-based systems that can be fabricated and the diversity of functionalities they can serve. However, in order to successfully exploit nanoparticle assemblies in technological applications and to ensure efficient scale-up, a high level of direction and control is required. Recently, block copolymers (BCP) have attracted much attention as a powerful and very promising tool for creation of nanoscale ordered structures owing to their self-assembling properties. In addition, these systems offer the possibility to fabricate nanostructured composite materials via incorporation of certain nanoadditives (i.e. NPs). The concept is that by selective inclusion of the nanoparticles into one of the blocks of a self-assembling copolymer, the nanoparticles are forced into a defined spatial arrangement determined by the phase morphology of the block copolymer. In present work self-assembling phenomena of block copolymers was exploited to fabricate binary (NP/BCP) and ternary (NP1/NP2/BCP) composites, filled with pre-synthesized nanoparticles of various nature. Polystyrene-block-polyvinylpyridine block copolymers (PS-b-PVP) of various composition and molecular weight were used for fabrication of nanocomposites. The first part of the thesis focuses on fabrication of functional BCP-based composites containing magnetic nanoparticles (MNP), selectively assembled within one of the blocks of BCP matrix. Magnetic nanoparticles (MNPs) were selected among others since, as for today, there is the least number of successful results reported in literature on their selective incorporation into one of the phases of a BCP matrix. From the application point of view fabrication of periodic arrays of “magnetic domains” with periodicity on nanometer scale is also of interest for potential use in high-density magnetic data storage devices. For this purpose, ferrite-type MNP (Fe3O4, CoFe2O4) having apparent affinity toward polyvinylpyridine (PVP) phase were prepared using simple one-pot synthesis. Highly selective nanoparticles segregation into PVP domains of BCP was achieved owing to the presence of sparse stabilizing organic shell on the nanoparticles surface. Importantly, as-prepared MNPs did not require any additional surface modification step to acquire affinity towards PVP phase. Appropriate selection of annealing conditions allowed to produce patterns of nearly perfect degree of lateral order over relatively large surface large area (more than 4 sq µm). The second task of present work was fabrication of ternary NP1/NP2/BCP hybrid composites with two different types of nanoparticles being selectively localized in different microdomains of phase segregated block copolymer matrix. So far as only few studies have been reported on developing of approaches toward ternary composites, creation of alternative and straight forward routes toward such systems is still a challenge. In the frame of this part of present work, silver nanoparticles (AgNPs) covered with polystyrene shell were prepared, with the purpose to be incorporated into polystarene phase of phase separated PS-b-PVP block copolymer matrix. Two different approaches were tested to achieve desired three-component system. First, supposed simple blending of block copolymer and two kinds of nanoparticles having specific affinity toward different blocks of BCP in common solvent. After preparation of MNP/AgNP/BCP composite thin film and subsequent solvent vapour annealing, different domains of microphase segregated PS-b-PVP BCP were filled with different type of nanoparticles. Alternatively, step-wise approach for nanoparticles incorporation was developed and implemented for successful selective nanoparticles incorporation. For this purpose polystyrene stabilized AgNPs (i.e. NP1) were initially mixed with PS-b-PVP BCP to produce composite thin films having nanoparticles selectively located within PS microdomains, while citrate-stabilized second type nanoparticles (i.e NP2) were deposited from their aqueous solutions into PVP domains of AgNP/PS-b-PVP composites. By partition of nanoparticles incorporation procedure into two distinct steps it was also possible to increase effective loading of each type of NPs into BCP matrix.
222

Utilisation de copolymères à blocs dans les cellules solaires organiques : morphologie, transport de charges et conversion photovoltaïque / Use of block copolymers in organic solar cells : morphology, charge transport and photovoltaic performances

Gernigon, Véronique 04 January 2012 (has links)
Les matériaux les plus répandus dans le domaine du photovoltaïque (PV) organique à base de polymères sont le poly(3-hexylthiophène) régiorégulier (rr-P3HT) et le [6,6]-phenyl-C61-butyric acide methyl ester (PCBM). La couche active est une hétérojonction en volume (BHJ) de nanodomaines interpénétrés accepteur d’électron (le PCBM) et donneur d’électron (le P3HT). Le contrôle de la morphologie de la couche active et de sa stabilité est un défi majeur pour le développement des cellules organiques et est au centre de ce travail de thèse.Dans un premier temps, nous avons cherché à contrôler la morphologie du mélange P3HT:PCBM via l’utilisation de compatibilisants. Deux familles de copolymères à blocs rigide et souple ont été étudiées. Elles ont en commun leur bloc rigide à base de P3HT et diffèrent par leur bloc souple. Pourla première famille, le bloc souple poly-butylacrylate est greffé de C60, ce qui lui confère une affinité chimique avec les domaines de PCBM, et la seconde famille a un bloc souple poly(4-vinylpiridine) (P4VP) non greffé en C60. De par son affinité chimique avec le C60, le PCBM se localisera préférentiellement au voisinage des domaines P4VP.Dans un deuxième temps, nous avons exploité les propriétés d’auto-assemblages des copolymères à blocs afin de les étudier en tant que matériaux photo-actifs. Nous avons cherché à appréhender l’influence de la nature du bloc flexible let de a taille des blocs souple et rigide sur l’organisation des copolymères ainsi que sur les propriétés de transport de charge et sur les performances PV. / Polymer/fullerene bulk heterojunction (BHJ) solar cells use an interpenetrating network of TT-conjugated electron-donor polymers and electron-acceptor C60 as photo-active layer. Currently, the most investigated blends are constituted of regioregular poly(3-hexylthiophene) (rr-P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). The nanostructured active layer determines to great extend the overall performance of the devices.First of all, we introduced rod-coil block copolymers as compatibilizer into P3HT:PCBM blends and investigate their influence on the blend morphology and the related photovoltaic performance. Two P3HT-based block copolymer families have been studied. The first one has a C60-grafted polybutylacrylate coil block and the second one is based on poly(4-vinylpyridine) (P4VP) coil block. The film morphology and device efficiencies are investigated as a function of copolymer content, P3HT/PCBM mass ratio and coil nature.A second possible route to obtain a stable donor/acceptor nanostructure consists of using semiconductor block copolymers as photoactive layer, since these materials are able to self-assemble into donor/acceptor BHJ by microphase separation. We explored P3HT-P4VP rod-coil block copolymers blended with PCBM in view of their utilization in photovoltaic devices. The copolymer selfassembles into nano-domains rich in either P3HT or P4VP, while the strong chemical affinity of P4VP with PCBM leads to an accumulation of the latter in the P4VP domains, providing them an acceptorcharacter. It is found that organized and thermally stable thin films, that exhibit ambipolar field effect mobilities, can be achieved for a specific rod/coil ratio.
223

Filmes de Langmuir e Langmuir-Blodgett (LB) de azopolímeros com controle do tamanho da cadeia e posição dos cromóforos / Langmuir and Langmuir-Blodgett (LB) films of azopolymers with controlled chain-length and chromophores position

Felippe José Pavinatto 08 March 2006 (has links)
Azopolímeros apresentam propriedades de fotoisomerização, úteis para confecção de memórias ópticas, que dependem da arquitetura molecular do azopolímero e do filme formado a partir dele. Neste trabalho foram sintetizados polímeros com arquitetura molecular controlada, usando os azomonômeros [4-(N-etil-N-2-(metacriloxietil)) amino-2\'-cloro-4\'-nitroazobenzeno] (DR13MA) e [4-(N-etil-N-2-(metacriloxietil)) aminoazobenzeno] (MAEAMA). Para a síntese de homopolímeros e copolímeros em bloco foram utilizados dois métodos: NMRP - polimerização radicalar mediada por nitróxidos e ATRP - polimerização radicalar por transferência de átomo. Foram produzidos copolímeros dibloco, com um dos blocos contendo azocorantes, pela reação do monômero DR13MA com macroiniciadores poliestireno (PS) no método NMRP, e poli(metacrilato de metila) (PMMA) via ATRP. Homopolímeros de ambos os azomonômeros foram sintetizados por ATRP, e assim como os copolímeros em bloco mostraram cadeias com baixa polidispersividade. Complementando o trabalho de síntese, foram estudadas as propriedades dos materiais na interface ar-água, utilizando filmes de Langmuir, e procedeu-se a transferência dos mesmos para substratos sólidos formando filmes Langmuir-Blodgett (LB). Nos filmes de Langmuir foi observada a conformação e as interações (agregação) das moléculas dos materiais, destacadamente, no caso do homopolímero HPMAEA, foi observado um patamar próximo a 8 mN/m na isoterma de pressão de superfície, indicando haver reorganização do material no filme. Os filmes LB serviram como objeto de estudo das propriedades ópticas dos compostos, e no caso do homopolímero HPDR13 sintetizado via ATRP, pela primeira vez foi possível a realização de medidas em filmes puros do material. Medidas de armazenamento óptico foram realizadas para comprovar a aplicabilidade dos materiais em memórias ópticas. No caso do terpolímero PS-b-[MMA-co-DR13] sintetizado por NMRP, os resultados de armazenamento foram semelhantes aos obtidos com blendas. Para o homopolímero HPMAEA, uma grande influência do tipo de filme empregado (cast ou LB) foi observada no tempo de escrita das memórias, com o tempo para o filme LB sendo 26 vezes menor. Copolímeros em bloco PMMA-b-DR13 podem ser vantajosos por aliarem as propriedades ópticas do homopolímero HPDR13 à maior estabilidade térmica e mecânica do PMMA. / Azopolymers display photoisomerization properties, which can be exploited in optical memories, and depend strongly on the molecular architecture of the polymer chain and kind of film employed. In this work, azopolymers with controlled molecular architecture were synthesized using the azomonomers [4-(N-ethyl-N-2(methacryloxyethyl))amino-2\'-chloro-4\'-nitroazobenzene](DR13MA)and[4-(N-ethyl-N-2-(methacryloxyethyl))aminoazobenzene] (MAEAMA). Two methods were used to synthesize homopolymers and block-copolymers: NMRP - Nitroxide-mediated radical polymerization and ATRP - Atom transfer radical polymerization. Diblock-copolymers were produced, with one block composed by azodyes units, by reacting the monomer DR13MA with a polystyrene (PS) macroinitiator via NMRP, or with poly(methyl methacrylate) (PMMA) macroinitiator via ATRP. Homopolymers of both azomonomers were synthesized by ATRP, and - analogously to the blockcopolymers - exhibited controlled structure with a small polydispersity. The synthesized polymers were then used in the formation of Langmuir films at the air-water interface, which could be transferred onto solid substrates forming Langmuir-Blodgett (LB) films. In Langmuir films, an investigation was made of the conformation and interactions (aggregation) of the film-forming molecules. Interestingly, a plateau was observed at 8 mN/m in the surface pressure isotherm for the HPMAEA homopolymer, pointing to a reorganization of the polymer during compression. For HPDR13 produced by ATRP, it was possible to deposit LB films with no need to use surfactants, unlike the case of HPDR13 synthesized by conventional methods. Optical storage measurements were performed to demonstrate the applicability of the azo-containing materials in optical memories. For the terpolymer PS-b-[MMA-co-DR13] made by NMRP, the storage results were similar to those obtained with blends. In the case of the homopolymer HPMAEA, a large influence of the kind of film used (cast or LB) was observed in the writing time of the memories, with the writing time for the LB film being 26 times faster. PMMA-b-DR13 block-copolymers may be advantageous in combining the optical properties of the homopolymer HPDR13 with the thermal and mechanical stability of PMMA.
224

Kinetically frozen copolymer nanocarriers : from non-equilibrium self-assembly to in vitro and in vivo evaluation / Micelles figées de copolymères séquencés : de l'auto-assemblage hors équilibre aux comportements in vitro et in vivo

Jennings, Laurence 23 November 2015 (has links)
L'objectif de cette thèse, la production et la caractérisation de nanovéhicules de morphologies différentes propres au traitement et au diagnostic par radio-isotopes, a conduit à une meilleure compréhension de la façon dont ces véhicules se forment. Les résultats ont permis de concevoir des méthodes de préparation novatrices qui permettent d'obtenir des échantillons de qualité supérieure à ce qui est actuellement l'état de l'art. Un nouveau procédé pour la préparation d'échantillons pour les essais de flexion de microscopie à force atomique a été développé. Cela a permis de mesurer le module d'élasticité de nanofils préparés avec des mélanges copolymère séquencé/homopolymère de composition variable. Enfin, les nanoparticules de morphologies sphérique et allongée ont été comparées dans des études in vivo réalisées avec des souris saines. Les résultats montrent que leur temps de circulation et leur biodistribution peuvent être modulés par leur taille et leur morphologie. / This thesis provides an overview of the formation, characterization and testing of micelles of different morphology for biological applications. One major aspect of this thesis is the understanding of the processes which lead to the formation of block copolymer micelles through the emulsion evaporation method. The results obtained made it possible to develop an innovative micelle formation technique which provides samples which are of superior quality to what the current state of the art. A new method has been developed for the preparation of samples for three point bending tests experiments performed by atomic force microscopy. This has made it possible to determine the elastic modulus of elongated micelles formed with various blends of homopolymers and copolymers. Finally, the behavior of spherical and elongated micelles was compared in vivo in healthy mice. The results have shown that the micelle size and morphology influences their biodistribution and circulation time.
225

Émulsions stabilisées par des particules polymériques biodégradables : études physico-chimiques et évaluation pour l'application cutanée / Pickering emulsions stabilization using biodegradable particles : physical chemistry studies and application to skin drug delivery

Laredj Bourezg, Faïza 08 July 2013 (has links)
La stabilisation dite de Pickering repose sur l'utilisation de particules solides au lieu des émulsifiants. Leur forte adsorption aux interfaces confère à celles-ci une rigidité les protégeant de la coalescence. Ce travail se partage en quatre grandes parties. Un premier volet traite de la fabrication de ces particules et de leur caractérisation physico-chimique. Une deuxième partie traite de la formulation d'émulsions H/E selon deux procédés différents et leur caractérisation. La troisième partie avait pour but l'investigation du comportement de ces particules à l'interface H/E par diffusion de neutrons. La dernière partie traite de l'évaluation de ces émulsions pour l'application cutanée. Ce travail a pour objectif de formuler des émulsions de Pickering en utilisant des particules polymériques biodégradables. Des particules individualisées formées à partir de copolymères di-blocs du type : PCL-b-PEG et PLA-b-PEG, ont été fabriquées selon un procédé de nanoprécipitation innovant. Elles ont été caractérisées en termes de taille et de stabilité. Leur structure interne a également été investiguée par RMN et cryo-MET. Leur aptitude à stabiliser des émulsions H/E très concentrées a été démontrée. L'impact du procédé d'emulsification sur les propriétés finales a été souligné et l'adsorption de particules en forme de chapelets serrés à l'interface a été visualisée par diffusion de neutrons et microscopie électronique après cryofracture. L'absorption du rétinol dans la peau à partir de ces émulsions innovantes, a montré une accumulation accrue de cet actif dans le stratum corneum comparée à celle d'une émulsion stabilisée par des tensioactifs classiques. Cette absorption cutanée a été montrée dépendre du procédé de fabrication des émulsions. Les particules en suspension aqueuse ont aussi été testées pour l'encapsulation et la libération cutanée du rétinol. Les résultats ont montré l'influence de la constitution interne des particules (PCL ou PLA) sur l'absorption du rétinol dans la peau. L'utilisation de polymères biodégradables apporte de nouvelles perspectives dans la formulation des émulsions de Pickering à usage cosmétique ou pharmaceutique, en s'affranchissant des effets jugées hasardeux pour la santé humaine des particules inorganiques / The so-called Pickering stabilization is based on the use of solid particles instead of emulsifiers. Their strong adsorption at interfaces confers rigidity preventing them from coalescence. This work is divided into four main parts. The first part deals with the manufacture of these particles and their physicochemical characterization. A second part deals with the O/W emulsions formulation according to two different methods and their characterization. The third part is an investigation into the behavior of these particles at the O/W interface by small angle neutron scattering. The last part deals with the evaluation of these emulsions for their application to skin delivery. This work aims at the preparation of Pickering emulsions using biodegradable polymeric particles. Individual particles formed from diblock copolymers such as: PCL-b-PEG and PLA-b-PEG, were made by an innovative nanoprecipitation process. They were characterized in terms of their size and stability. Their internal structure was also investigated by NMR and cryo-TEM. Their ability to stabilize highly concentrated O/W emulsions has been demonstrated. The impact of the emulsification process on the final properties was emphasized and the adsorption of particles as tight necklaces at the interface was visualized by neutron scattering and freeze-fracture electron microscopy. The skin absorption of retinol from these innovative emulsions showed enhanced accumulation of the asset in the stratum corneum compared to conventional surfactant-stabilized emulsions. Such skin absorption of retinol was shown to depend on the manufacturing method of the emulsions. Particles in aqueous suspension were also tested for encapsulation and delivery of retinol in skin. The results showed the influence of the internal structure of the particles (PCL or PLA) on the absorption of retinol in the skin. The use of biodegradable polymers brings new perspectives in the formulation of Pickering emulsions for cosmetic or pharmaceutical use, while avoiding the effects of inorganic particles considered hazardous to human health
226

Ordered Structures from Nanoparticles/Block Copolymer Hybrids: Ex-situ Approaches toward Binary and Ternary Nanocomposites

Horechyy, Andriy 01 July 2011 (has links)
Within the field of modern technology, nanomatrials, such as nanoparticles (NP), nanorods (NR), quantum dots (QD) etc. are, probably, the most prominent and promising candidates for current and future technological applications. The interest in nanomaterials arise not only form the continuous tendency towards dimensions minimisation of electronic devices, but also due to the fact, that new and, often, unique properties are acquired by the matter at the length scale between 1 and 100 nm. The ability to organize nanoparticles into ordered arrays extends the range of useful NP-based systems that can be fabricated and the diversity of functionalities they can serve. However, in order to successfully exploit nanoparticle assemblies in technological applications and to ensure efficient scale-up, a high level of direction and control is required. Recently, block copolymers (BCP) have attracted much attention as a powerful and very promising tool for creation of nanoscale ordered structures owing to their self-assembling properties. In addition, these systems offer the possibility to fabricate nanostructured composite materials via incorporation of certain nanoadditives (i.e. NPs). The concept is that by selective inclusion of the nanoparticles into one of the blocks of a self-assembling copolymer, the nanoparticles are forced into a defined spatial arrangement determined by the phase morphology of the block copolymer. In present work self-assembling phenomena of block copolymers was exploited to fabricate binary (NP/BCP) and ternary (NP1/NP2/BCP) composites, filled with pre-synthesized nanoparticles of various nature. Polystyrene-block-polyvinylpyridine block copolymers (PS-b-PVP) of various composition and molecular weight were used for fabrication of nanocomposites. The first part of the thesis focuses on fabrication of functional BCP-based composites containing magnetic nanoparticles (MNP), selectively assembled within one of the blocks of BCP matrix. Magnetic nanoparticles (MNPs) were selected among others since, as for today, there is the least number of successful results reported in literature on their selective incorporation into one of the phases of a BCP matrix. From the application point of view fabrication of periodic arrays of “magnetic domains” with periodicity on nanometer scale is also of interest for potential use in high-density magnetic data storage devices. For this purpose, ferrite-type MNP (Fe3O4, CoFe2O4) having apparent affinity toward polyvinylpyridine (PVP) phase were prepared using simple one-pot synthesis. Highly selective nanoparticles segregation into PVP domains of BCP was achieved owing to the presence of sparse stabilizing organic shell on the nanoparticles surface. Importantly, as-prepared MNPs did not require any additional surface modification step to acquire affinity towards PVP phase. Appropriate selection of annealing conditions allowed to produce patterns of nearly perfect degree of lateral order over relatively large surface large area (more than 4 sq µm). The second task of present work was fabrication of ternary NP1/NP2/BCP hybrid composites with two different types of nanoparticles being selectively localized in different microdomains of phase segregated block copolymer matrix. So far as only few studies have been reported on developing of approaches toward ternary composites, creation of alternative and straight forward routes toward such systems is still a challenge. In the frame of this part of present work, silver nanoparticles (AgNPs) covered with polystyrene shell were prepared, with the purpose to be incorporated into polystarene phase of phase separated PS-b-PVP block copolymer matrix. Two different approaches were tested to achieve desired three-component system. First, supposed simple blending of block copolymer and two kinds of nanoparticles having specific affinity toward different blocks of BCP in common solvent. After preparation of MNP/AgNP/BCP composite thin film and subsequent solvent vapour annealing, different domains of microphase segregated PS-b-PVP BCP were filled with different type of nanoparticles. Alternatively, step-wise approach for nanoparticles incorporation was developed and implemented for successful selective nanoparticles incorporation. For this purpose polystyrene stabilized AgNPs (i.e. NP1) were initially mixed with PS-b-PVP BCP to produce composite thin films having nanoparticles selectively located within PS microdomains, while citrate-stabilized second type nanoparticles (i.e NP2) were deposited from their aqueous solutions into PVP domains of AgNP/PS-b-PVP composites. By partition of nanoparticles incorporation procedure into two distinct steps it was also possible to increase effective loading of each type of NPs into BCP matrix.
227

Alkinhaltige Blockcopolymere und ihre Modifizierung mittels 1,3-dipolarer Cycloaddition

Fleischmann, Sven 22 July 2008 (has links)
In der vorliegenden Dissertation wurden mittels kontrolliert radikalischer Polymerisationstechniken alkinhaltige Blockcopolymere synthetisiert. In effizienten Cu(I)-katalyisierten 1,3-dipolaren Cycloadditionen (Click-Chemie) wurde diese modifiziert. Insbesondere durch die Addition dendritischer Verbindungen gelang die Darstellung nanosopischer Objekte. Darüber hinaus konnten dünne Filme phasenseparierten Blockcopolymere selektiv und ortsaufgelöst funktionalisiert werden. Die Arbeit liefert somit Beiträge zur Entwicklung neuartiger Nanomaterialien sowie ihrer Modifizierung.
228

Functionalization of PS-b-P4VP Nanotemplates: towards optoelectronic applications

Krenek, Radim 18 December 2007 (has links)
Self-organization of block copolymers becomes attractive for several branches of the current science and technology, which requires a cheap way of fabrication of well-ordered arrays of various nanoobjects. High ratio between the surface (or the interface) and the volume of the nanoobjects enables development of very efficient devices. The work within this thesis profits from the chemical dissimilarity between blocks of polystyrene-block-poly(4‑vinylpyridine) copolymers, where polystyrene forms “a body” of nanostructures and poly(4‑vinylpyridine) is “a link” for assemblies with low-molar-mass additives. Procedures and phenomena are demonstrated (observed) on few sorts of PS‑b‑P4VP copolymers with respect to their molecular weight and ratio of blocks. Although there are many kinds of nanostructures based on block copolymers, only nanotemplates are involved in the study. Their properties, like an influence of substrate roughness on microphase separation, stability of porous nanotemplates in ionized solutions, or a role of additives in their supramolecular assembly, respectively, are investigated. All of them appears to be important in development of various devices based on the nanotemplates. With respect to optoelectronic applications, electrical current transport and fluorescence are two basic phenomena studied on functionalized nanotemplates, developed in the thesis. DC transport is studied on nanostructures developed via sputtering of chromium into porous nanotemplates. Sputtering process is optimized in dependence of chromium deposition rate, composition and pressure of ambient gas. It is shown that a reactive nature of PS-b-P4VP nanotemplates enables development of resistant organometallic nanotemplates. On the other hand, suppression of the polymer reactivity is achieved by oxidation of a metal during sputtering in a reactive gas, which enables e. g. development of highly ordered TiO2 nanodots. Current-voltage characteristics are measured on “sandwich” devices (like LEDs) with various electrodes and composition. Several recent theoretical models fitting the characteristics are applied together with structural characterization techniques (like AFM or x-ray reflectivity) in order to elucidate relations among surface roughness, distribution of sputtered clusters, and carrier injection and transport. Fluorescence is studied on nanotemplates with organic low-molar-mass dyes, developed either via direct blending with the copolymer or via soaking of porous nanotemplates in dye solutions. Several relations between structure and fluorescence are observed. For instance, excimer emission in pyrene assemblies is supressed after ordering of the nanotemplate. Solvent induced orientation of fluorescein molecules in the nanotemplate results in fluorescence enhancement. Dimerization of Rhodamine 6G is dependent on the way of its impregnation in the nanotemplates (solvent, concentration, speed).
229

Synthesis of Bio-Based Polymers Containing D-Isosorbide by Ring-Opening Metathesis Polymerization

Yalamanchili, Chinni 17 May 2014 (has links)
The utilization of renewable sources as alternatives for petroleum and natural gas products has immense commercial, health and global warming significance. D-Isosorbide (2) is a bifunctional, polar, chiral and rigid molecule, which is produced from renewable sources. Synthesis of new polymers containing 2 is of interest for polymers and in drug delivery. The aim of the present work is to synthesize various polymers (homo- and copolymers) containing 2 via the olefin metathesis routes, ring-opening metathesis polymerization (ROMP) and acyclic-diene metathesis polymerization (ADMET). N-Phenyl-7-oxanorbornene-dicarboximide, and norbornene functionalized onto 2 were used as the monomers for ROMP. These monomers were polymerized using Grubbs’ catalysts to generate a series of homo-, co-, block and cross-linked-polymers. These polymers were characterized using GPC, NMR, and IR. In addition, ADMET polymerization of a terminal diolefinunctionalized D-isosorbide (2) was also conducted to produce ADMET polymers.
230

Synthesis of Arborescent Model Polymer Structures by Living Carbocationic Polymerization for Structure-Property Studies

Dos Santos Freire, Lucas M. 09 June 2009 (has links)
No description available.

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