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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.
571

Estudo da miscibilidade e das propriedades mecânicas de blendas SAN/NBR

Ziquinatti, Francine 21 February 2005 (has links)
Made available in DSpace on 2016-12-08T17:19:14Z (GMT). No. of bitstreams: 1 iniciais.pdf: 130139 bytes, checksum: cfb58dd0103455dbb6c7b372a4cf5ad3 (MD5) Previous issue date: 2005-02-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Aiming the study of miscibility and mechanical properties, blends of poli(styrene-coacrylonitrile) (SAN) with poli(butadiene-co-acrylonitrile) (NBR) rubbers were prepared by casting, co-precipitation and extrusion followed by injection, varying acrylonitrile (AN) contents from 32,7 to 45% (w/w) in NBR. The blends were prepared in the compositions: SAN/NBR 90/10, 80/20, 70/30, 60/40 and 50/50 (w/w) and valued by Infrared spectroscopy (FTIR), Differential scanning calorimetry (DSC), Scanning electron micrographs (SEM), Tensile and Izod impact tests. FTIR analyses of casting blends displayed that not happened reactions or specific interactions between polymers during blending because did not happened a shift in the spectrum blends bands. The DSC analyses of casting blends showed total imiscibility to SAN/NBR 50/50 blend (AN contents in NBR 32,7%), partial miscibility to the 60/40, 70/30 and 80/20 compositions and total miscibility to the 90/10 composition. The SAN/NBR blends (AN contents in NBR 39%), prepared by casting and coprecipitation revealed partial miscibility for all compositions. Coprecipitated blends prepared with AN rubber content of 45% showed partial miscibility to 50/50, 60/40, 70/30 and 90/10 compositions and total miscibility to 80/20 composition. The phase morphology was influenciated by blending methods, casting blends revealed dispersed spherical elastomeric domains in matrix while coprecipitated blends form co continuous phase. The NBR addition result in significant impact resistant increase but decrease in tensile strenght / Com o objetivo de estudar a miscibilidade e propriedades mecânicas, foram preparadas blendas do copolímero poli(estireno-co-acrilonitrila) (SAN) com o copolímero poli(butadienoco-acrilonitrila) (NBR). As blendas foram preparadas por três métodos diferentes: evaporação de solvente, co-precipitação e extrusão seguida de injeção, variando o teor de acrilonitrila no NBR de 33 a 45 % (m/m). As blendas foram preparadas nas composições SAN/NBR 90/10, 80/20, 70/30, 60/40 e 50/50 (m/m) e avaliadas por Espectroscopia na região do infravermelho com Transformada de Fourrier (FTIR), Calorimetria diferencial exploratória (DSC), Microscopia eletrônica de varredura (MEV), Ensaios de Tração e Impacto Izod. As análises de FTIR das blendas preparadas por evaporação de solvente mostraram não ter ocorrido nenhuma reação nem interação específica entre os polímeros durante o processo de mistura porque não houve deslocamentos, aparecimento ou desaparecimentos de picos no espectro das blendas em relação ao espectro dos polímeros puros. O DSC avaliou a miscibilidade das blendas preparadas por evaporação de solvente e co-precipitação. A blenda SAN/NBR 50/50, preparada por evaporação de solvente, (NBR contendo 32,7% de acrilonitrila), é totalmente imiscivel, as composições 60/40, 70/30 e 80/20 são parcialmente miscíveis e a composição 90/10 formou um sistema miscível. As blendas SAN/NBR (NBR contendo 39% de acrilonitrila), preparadas por evaporação de solvente e co-precipitação, mostraram-se parcialmente miscíveis em todas as composições. As blendas preparadas por co-precipitação usando a borracha com 45% de acrilonitrila são parcialmente miscíveis com exceção da composição 80/20 que é totalmente miscível. A morfologia de fase foi influenciada pelo método de preparação das blendas, aquelas preparadas por evaporação de solvente mostraram domínios elastoméricos ovais dispersos na matriz SAN, enquanto que as preparadas por coprecipitação apresentaram fases semi-contínuas. A resistência ao impacto foi significativamente aumentada pela incorporação do NBR no SAN porém com decréscimo do Módulo de Young.
572

Synthèse et caractérisations de nouveaux polyesters biodégradables dérivés du poly (acide 3,3-diméthylmalique) comme revêtement prometteur de stents cardiovasculaires. / Synthesis and characterizations of new biodegradable polysters derivided of poly (3,3-Dimethylmalic acid) as a promising cardiovascular stents coating

Belibel, Rima 07 December 2015 (has links)
A l’exception du chapitre bibliographique, cette thèse a été rédigée sous forme d’articles avec des résumés et des discussions tout en comparant les résultats obtenus à d’autres résultats de la littérature dans la même thématique de recherche. Ce travail s’organise en trois axes de recherche : la synthèse organique et la chimie des polymères, la physicochimie de la surface et l’étude de la réponse biologique et de la dégradation des polymères. La problématique de ce sujet de thèse s’articule autour de la resténose intra-stent qui représente la complication majeure de l’angioplastie par pose de stent dans les artères sténosées. Les stents actifs restent la solution actuellement utilisée pour le traitement de la resténose. Ce sont des stents métalliques recouverts d’un polymère qui comporte une substance bioactive généralement un antiprolifératif. Le rôle du polymère est de créer une barrière protectrice entre le métal et la paroi artérielle. Cette barrière doit améliorer la rugosité et la composition chimique du stent métallique, réparer l’endothélium par la prolifération des cellules endothéliales et inhiber la prolifération et la migration des cellules musculaires lisses qui sont responsables d’une façon directe de la reformation de la plaque d’athérome. Les propriétés de surface du polymère lui confèrent un fort pouvoir d’adhérence au métal et de biocompatibilité vis-à-vis de la paroi artérielle. Les interactions créées entre le revêtement polymère et les cellules vasculaires sont modulées par les propriétés physicochimiques de la surface. C’est dans cette optique que mon sujet de thèse est organisé en deux thématiques. / With the exception of bibliographic chapter, this thesis was written in the format of collection of articles with abstracts and discussions while comparing the results with other’s in the literature in the same research theme. This work is organized in three tasks: organic synthesis and stereochemistry of polymers, surface physicochemical properties and biological response and degradation study of polymers. The issue of this thesis is based on in-stent restenosis which represents the major complications of angioplasty with stent placement. Drug-eluting stents are currently the solution used for the restenosis treatment. These are metal stents coated with a polymer having a bioactive substance which is generally an antiproliferative agent. The polymer role is to create a protective barrier between the metal and the arterial wall. This barrier must improve the roughness and the chemical composition of the metallic stent, repair the endothelium by the proliferation of endothelial cells and inhibit the proliferation and the migration of smooth muscle cells which are responsible to the reformation of atheroma plaque. The surface properties confer to polymer a strong adhesiveness to the metal and biocompatibility vis-a-vis of the arterial wall. Interaction created between the polymer coating and vascular cells are modulated by the physicochemical properties of the surface. It is in this context that my thesis is organized into two themes.The first aim of my thesis is to develop a series of amorphous polymers and study their physicochemical (wettability, roughness ...) and biological properties (adhesion, cell behavior and proliferation) and then correlate these properties to choose the promising coating coronary stent. A degradation study was also conducted on elaborate systems. The second is dedicated to chemical synthesis and stereochemistry of polymers. Indeed, new optically active monomers and the corresponding stereopolyesters were synthesized and characterized in order to compare their physicochemical properties with those of amorphous polyesters studied as a coating of the stent and enhance the biomaterials field.
573

Caracterização de filmes formados por dispersões aquosas de poli(uretano-uréia)s para aplicação em membranas para permeação de gases / Characterizations of films formed from aqueous dispersions of poly(urethane-urea)s for use as membranes for gas permeation

Juliana Henriques Costa Pereira 28 February 2012 (has links)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Entre os polímeros considerados promissores para a remoção seletiva de CO2, destacam-se aqueles que contêm os grupos glicol etilênico (EG). Nesta dissertação, foram obtidos filmes a partir de dispersões aquosas de poliuretano (PU), sintetizadas em trabalho anterior, à base de poli(glicol propilênico) (PPG), copolímero em bloco à base de poli(glicol etilênico) (PEG) e PPG (EG-b-PG), ácido dimetilolpropiônico (DMPA), diisocianato de isoforona (IPDI) e etilenodiamina (EDA). PPG, EG-b-PG e DMPA formaram as regiões flexíveis nas proporções de: PPG 100% e 0% EG-b-PG, PPG 75% e 25% EG-b-PG, PPG 50% e 50% EG-b-PG e PPG 25% e 75% EG-b-PG em termos de equivalentes-gramas. A influência da quantidade dos segmentos de PEG foi avaliada por ensaios de permeação com os gases CO2, CH4 e N2. Os filmes obtidos das dispersões foram caracterizados por espectrometria de infravermelho com transformadas de Fourier (FTIR), análise termogravimétrica (TGA), difração de raios x (DRX) e espalhamento de raios X a baixo ângulo (SAXS). Espectros de FTIR mostraram que os segmentos de EG influenciaram a frequência da banda de carbonila. Curvas de perda de massa (TG) mostraram perfis semelhantes de degradação, enquanto que as curvas derivadas apresentaram diferenças. DRX e SAXS mostraram que os segmentos de PEG promoveram uma maior ordenação na estrutura da membrana. Testes de permeação de gases mostraram que o aumento do teor de PEG aumentou o valor da permeabilidade para o CO2, indicando que os segmentos de PEG interagiram favoravelmente com este gás. Em relação ao CH4 e N2, houve uma diminuição na permeabilidade quando comparados com os valores encontrados para o CO2, sendo atribuído a perda de mobilidade segmental. Em termos de seletividade, para o par CO2/CH4 foi obtido um valor médio de 61,7 para a membrana contendo o maior teor de PEG, e o par CO2/N2 um valor médio de 121,5, sendo superior aos valores encontrados na literatura, tornando o material promissor / Among the polymers considered promising for the selective removal of CO2 from natural gas, those containing ethylene glycol groups (EG) are the most distinguished. In this study cast films were obtained from aqueous dispersions of polyurethane (PU), synthesized in a previous work with poly (propylene glycol) (PPG), block copolymer based on poly(ethylene glycol) (PEG) and PPG, dimethylolpropionic acid (DMPA), isophorone diisocyanate (IPDI) and ethylenediamine (EDA). Segments of PPG, EG-b-PG and DMPA formed the flexible domains in the proportions of: PPG 100% and 0% EG-b-PG, PPG 75% and 25% EG-b-PG, PPG 50% and 50% EG-b-PG and PPG 25% and 75% EG-b-PG, in terms of equivalent-grams. The influence of the amount of PEG segments in permeation properties of CO2, CH4 and N2 was verified by permeability essays. The membranes were obtained as cast films from the dispersions and was characterized by infrared spectrometry (FTIR), termogravimetric analysis (TGA), X ray diffractometry (XRD) and small angle X ray scattering (SAXS). FTIR spectra showed that PEG segments influenced carbonyl band frequency. Loss of mass curves with temperature (TG) showed similar profiles of degradation, whereas DTG curves presented more stages. PEG segments conferred higher thermal stability for the materials. XRD and SAXS analysis showed that PEG promoted ordination to the membranes. In gas permeation tests, it was verified that the increase in copolymer amount increased permeability value for CO2, being attributed to the fact that the segments of poly(ethylene glycol) interacted favorably with this gas. In relation to CH4 and N2, there was a significant decrease in permeability when compared to the values found for CO2, being assigned to a loss of segmental mobility with increasing content of EG. In terms of selectivity, the pair CO2/CH4 had a mean value of 61,7 for the membrane containing the highest amount of EG groups, and the pair CO2/N2 produced a mean value of 121,5 for the same one, being superior than those found in the literature, making a promising material
574

Síntese e caracterização do copolímero tribloco anfifílico biodegradável poli(L, L-lactídeo-stat-e-caprolactona)-bloco-poli(óxido de etileno)-bloco-poli(L, L-lactídeo-stat-e-caprolactona). / Synthesis and characterization of triblock anfiphilic biodegradable copolymer poly(l,l-lactide-stat-e-caprolactone)-b-poly(ethylene oxide)-b-poly(l,l-lactide-stat-e-caprolactone).

Zhao Lili 09 April 2007 (has links)
Este trabalho apresenta um estudo sobre a síntese e propriedades do copolímero poli(l,l-lactídeo-stat-e-caprolactona)-bloco-poli(óxido de etileno)-bloco-poli(l,l-lactideostat-e-caprolactona). Poli(óxido de etileno) de massa molar 20.000 u.m.a. e poli(óxido de etileno) modificado, preparado a partir de poli(glicol etilênico) de massa molar 4.000 u.m.a., foram selecionados para o processo da síntese. A reação foi feita pela polimerização por abertura de anel em massa a 120ºC usando octoanato de estanho como iniciador. A composição química de cada amostra foi determinada com auxílio de RMN-1H e RMN-13C e suas propriedades mecânicas foram verificadas e comparadas utilizando análises térmicas como DMTA, DSC, TG e a aplicação da MEV como análise complementar. A observação pelas fotos de MOLP permitiu a visualização do comportamento de nucleação dos copolímeros e as características de sua cristalinidade. Seu grau de cristalinidade e as fases cristalinas foram identificados por difração de raios X (WAXS). A biocompatibilidade do material também foi examinada pela cultura de células. Os resultados de caracterização indicam o sucesso da copolimerização, as propriedades elastoméricas e, sua não citotoxidade comprovaram a possibilidade do uso destes copolímeros como biomateriais. Contudo, o tempo prolongado de reação e baixa incorporação do monômero lactídeo ainda são questões a serem melhoradas para a viabilização do copolímero como material de implante na área biomédica. / This work includes the study of the synthesis and characterization of the copolymer poly(l,l-lactide-stat-e-caprolactone)-b-PEG-b-poly(l,l-lactide-stat-e-caprolactone). Poly (ethylene oxide) with molar weight 20.000 and poly(ethylene oxide) modified, prepared from poly(ethylene oxide) with molar weight 4000 have been selected for this synthesis process. The reaction was done by ring-opening bulk polymerization, using stannous octoate as initiator at 120ºC. The chemical composition of samples were determined by 1H-NMR and 13C-NMR and their mechanical properties were verified using thermal analyses like DMTA, DSC and TG. Scanning electron microscopy (SEM) was applied as a complementary analysis. The pictures of polarizing optical microscopy showed us the copolymer\'s nucleation behaviors and their respective crystallization. The degrees of crystallinity and phase of copolymers were determined by WAXS. The biocompatibility of the copolymer was examined by cell cultivation test. The result of these analyses above indicated the success of synthesis. Their rubbery properties and non-toxicity allowed their application as biomaterial. However, the long reaction time and low incorporation of monomer of lactide might to be improved to increase its potential use in biomedical area in the future.
575

Synthèse de nouveaux polyesters “verts” issus de ressources oléagineuses : application au renfort au choc du poly(L-lactide) / Synthesis of novel “green” polyesters from plant oils : application to the rubber-toughening of poly(L-lactide)

Lebarbe, Thomas 06 December 2013 (has links)
Dans cette étude, plusieurs voies ont été explorées dans l’objectif d’utiliser des polyesters aliphatiques issus de ressources oléagineuses comme additifs pour le renfort au choc du poly(L-lactide) (PLLA). Dans un premier temps, des poly(ester-amide)s (PEAs) ont été synthétisés à partir de dérivés de l’huile de ricin. La relation structure-propriétés des PEAs obtenus a été clairement établie. La dispersion des PEAs (à différents taux) par extrusion à l’état fondu dans une matrice de PLLA a ensuite été effectuée, démontrant un accroissement de la résilience de ces mélanges en comparaison au PLLA seul. Une étude systématique reliant la structure d’une large gamme de polyesters aux propriétés des mélanges polyesters/PLLA, a ensuite été réalisée. Une forte dépendance de la résilience des mélanges polyesters/PLLA avec la cristallinité de l’additif polyester a été observée et quantifiée.Une amélioration des propriétés mécaniques du PLLA a également été obtenue par polymérisation par ouverture de cycle du lactide amorcée par un poly(acide ricinoléique) di-hydroxy téléchélique. Les copolymères triblocs ainsi formés ont été caractérisés d’un point de vue morphologique et mécanique.Enfin, un travail exploratoire utilisant l’ADMET comme méthode de polymérisation a été conduit, permettant la synthèse de nouveaux polymères prometteurs pour le renfort au choc du PLLA. Notamment, la copolymérisation de α,ω-diènes bio-sourcés a permis de mimer le polyéthylène basse densité linéaire, couramment employé pour le renfort au choc du PLLA. / The objective of this thesis work, is to promote the use of fatty acid-based aliphatic polyesters as impact modifiers for poly(L-lactide) (PLLA).Firstly, poly(ester-amide)s (PEAs) have been synthesized from castor oil derivatives. The structure-properties relationship of the PEAs so-formed was clearly established. The PEAs were then melt-blended with PLLA by extrusion, yielding blends with improved impact strength compared to neat PLLA.A series of polyesters covering a wide range of thermo-mechanical properties was then employed to evaluate the influence of the polyester morphology on the properties of the blends with PLLA. A strong dependence of the impact strength of the blends was noticed with the crystallinity degree of the polyester additive.An improvement of the mechanical properties of PLLA was also obtained by ring-opening polymerization of lactide initiated by a di-hydroxy telechelic poly(ricinoleic acid). The so-formed triblock copolymers were fully characterized in terms of morphology and mechanical properties.Finally, an exploratory investigation related to the synthesis of PLLA impact modifiers by ADMET was carried out. Particularly, the copolymerization of two bio-based α,ω-dienes yielded a series of “LLDPE like” polyesters, LLDPE being a commonly used impact modifier for PLLA.
576

Elaboration et caractérisation de films d’hydrogel et de composites hydrogel-céramique pour les applications biomédicales / Design and characterization of hydrogel films and hydrogel-ceramic composites for biomedical applications

Moreau, David 21 January 2016 (has links)
Le remplacement des tissus mous du système ostéo-articulaire par des implants synthétiques en hydrogels est souvent limité par un faible ancrage avec le tissu osseux. Une approche pour renforcer l’interface os/implant consiste à fonctionnaliser la surface de l’implant par un revêtement biocéramiques. Dans cette thèse, nous étudions deux approches pour revêtir des hydrogels d’alcool polyvinylique (APV) avec des particules biocéramiques d’hydroxyapatite (HA). Dans une première approche, basée sur le procédé d’enduction, des substrats d’hydrogel ont été revêtus par des particules d’HA enchâssées dans une matrice d’hydrogel d’APV non-dégradable. Dans ce procédé, le contrôle de la composition de la solution de trempage permet d’ajuster finement l’épaisseur, la cohésion et l’adhérence du revêtement, ainsi que le taux d’exposition d’HA à la surface du revêtement. La biocompatibilité avec la pratique chirurgicale et l’ostéointégration de ces revêtements ont été évaluées par une étude in vivo sur un modèle de cicatrisation de tunnel osseux chez le lapin. Ces premiers travaux nous ont menés à la découverte d’une nouvelle approche pour gélifier des films d’hydrogel par un procédé auto-entretenu, qui consiste à utiliser la déplétion de solvant créée à la surface d’un substrat gonflant dans une solution de polymère pour induire la gélification sans action extérieure. Dans ce procédé, la croissance de ces films dépend de la concentration de la solution, du temps de trempage et de la cinétique de gonflement du substrat. Le caractère doux de ce procédé de gélification a été vérifié en encapsulant des fibroblastes, qui restent viables durant 48h. Avec un second procédé plus énergétique, des substrats d’hydrogels d’APV ont été revêtus de couches denses de particules d’HA submicroniques par cold spray. Les paramètres de projection (température, pression, distance de projection) ont été variés systématiquement pour déterminer des conditions de projection appropriées. Un schéma de formation du revêtement est proposé, basé sur les observations microscopiques. Chacun de ces procédés et leur combinaison ouvrent de nouvelles voies dans la conception de système hydrogel-céramique ayant des propriétés microstructurales, mécaniques et biologique contrôlées. / The replacement of soft osteoarticular tissues by synthetic hydrogel implants is often limited by a weak anchorage to bone tissues. One approach to strengthen the bone-implant interface consists in functionalizing the surface of the implant by a coating of bioceramics. In this thesis, we investigate two approaches to coat hydrogels of poly(vinyl alcohol) (PVA) with ceramic particles of hydroxyapatite (HA). In a first “soft” process, based on dip-coating, hydrogel substrates were coated with hydroxyapatite particles embedded in a non-degradable PVA hydrogel matrix. In this process, the control of the soaking solution composition allows to finely tune the thickness, the cohesion and the adhesion of the coating, as well as the HA exposure at the coating surface. The biocompatibility with surgical handling and the osteointegration of these systems were assessed by an in vivo study in a rabbit model of bone tunnel healing. This first approach led to the discovery of a new approach to grow physical hydrogel films by a self-sustained process, consisting in using the solvent depletion created at the surface of a swelling polymer substrate immersed in a PVA solution to induce the gelation of hydrogel films without external action. In this process, the growth of these hydrogel films depends on the solution concentration, the soaking time and the swelling kinetics of the substrate. We verified the gentle character of this process by encapsulating fibroblasts, which remain viable for 48h. In a second more “energetic” process, dense coatings of submicronic HA particles were produced on PVA hydrogel by cold spray. Spraying parameters (temperature, pressure and stand-off distance) were varied systematically to determine efficient spraying condition. Based on microscopic observations, a picture explaining the formation of the coating is proposed. Both processes and their combination open new routes for the design of ceramic-hydrogel systems having controlled microstructural, mechanical and biological properties.
577

Design of a suitable material at the nano to micrometer scale as support for electrolysis. : Study of the electropolymerization of concentrated L-amino acids in aqueous solutions / Etude de l'électropolymérisation des acides aminés très concentrés en solution aqueuses

Alhedabi, Taleb Flieh Hassen 24 November 2015 (has links)
L'oxyde d'aluminium anodique poreux (AAO) est formé par anodisationde l'aluminium dans une solution électrolytique acide, sous une tensionconstante et de la température de l'électrolyte. Des techniques spectroscopiquespareilles que la spectroscopie infrarouge FT (ATR-FTIR), diffraction des rayonsX (XRD), spectroscopie Raman, la microscopie à force atomique (AFM) etmicroscopie électronique à balayage (MEB) utilisés pour caractériser la matrice.L'oxydation anodique d'acides L-aminés et des mélanges de monomèrescomprenant 0,1 M aniline et des acides L-aminés dans le milieu aqueux acide deplatine et électrode lisses électrodes Pt modifié (Pt / AAO) est étudié.L'oxydation des acides L-aminés et les électropolymérisation de l'aniline 0,1 Mavec des acides L-aminés tels que la L-alanine, la L-sérine, la L-méthionine,acide L-aspartique, la L-lysine, et phénylalanine en acide le milieu a étéeffectuée par voltammetric cyclique électrochimique couplée à microbalance àcristal de quartz (EQCM). La concentration des acides aminés, le pH del'électrolyte et les effets de balayage de numéros de voltamétrie cyclique ont étéexaminées. L'analyse spectroscopique comme réflectance totale atténuée FTspectroscopie infrarouge (ATR-FTIR), UV-visible, la spectroscopiephotoélectronique à rayons X (XPS), la spectroscopie Raman, et la diffractiondes rayons X (XRD) sont utilisés pour caractériser les couches minces obtenues.Microscopie électronique à balayage (MEB) utilisé pour étudier la morphologiede surface mince de films. La solubilité pour les polymères sont étudiées. Laprésence de liaisons peptidiques est clairement mise en évidence. DFTmodélisation de poly-L-acides aminés volet sur Pt (001) couplée à des mesuresspectroscopiques sont en faveur de L-amino-acides électropolymérisation enacides poly-L-aminés d'une manière irréversible.Les électrosynthèses de poly-L-amino acides, la polyaniline et depolymères ont été utilisées en tant que récepteur de protons à l'état solide pHcapteur solide. / Anodic aluminum oxide porous (AAO) is formed by the anodization ofaluminum in acidic electrolytic solution under at constant voltage and electrolytetemperature. Spectroscopic techniques such as FT infrared spectroscopy (ATRFTIR),X-ray diffraction (XRD), Raman spectroscopy, atomic force microscopy(AFM) and scanning electron microscopy (SEM) used to characterize thetemplate.The anodic oxidation of L-amino acids and monomer mixtures comprising0.1 M aniline and some L-amino acids in acidic aqueous medium on platinumsmooth electrodes and modified Pt electrode (Pt/AAO) is studied. The oxidationof L-amino acids and in presence of aniline 0.1 M with L-amino acids such as Lalanine,L-serine, L-methionine, L-aspartic acid, L-lysine, and L- phenylalaninein acidic media was carried out by cyclic voltammetry coupled withelectrochemical quartz crystal microbalance (EQCM). The Amino acidconcentration, pH of the electrolyte and the scan number effects on cyclicvoltammetry were examined. Spectroscopic analysis such as attenuated totalreflectance FT infrared spectroscopy (ATR-FTIR), UV-Visible, X-rayphotoelectron spectroscopy (XPS), Raman spectroscopy, and X-ray diffraction(XRD) are used to characterize the resulting thin film coatings. Scanningelectron microscopy (SEM) used to study the morphology of thin films surfaceas well as the solubility are studied. The presence of peptide bonds is clearlyhighlighted. DFT modelization of poly-L-amino acids strand on Pt(001) coupledto spectroscopic measurements are in favor of L-amino acidselectropolymerization into poly-L-amino acids in an irreversible way.The electrosynthesis of poly-L-amino acids, polyaniline and polymerswere used as proton receptor for solid state pH solid sensor.
578

Synthèse de macromonomères photopolymérisables de L-lysine biosourcée et leur polymérisation par irradiation UV pour des applications dans le domaine des revêtements / Synthesis of photocurable macromonomers based on biobased L-lysine and their polymerization under UV irradiation for coating applications

Koleilat, Houria 13 December 2013 (has links)
Les matières premières biosourcées s'avèrent être une possibilité de substitution du pétrole de plus en plus prisée dans le domaine des matériaux. De plus, l'utilisation de procédé propre limitant l'impact environnemental du développement de matériau est aujourd'hui incontournable. Dans ce contexte, l'acide aminé L-lysine, un nouveau synthon issu des biotechnologies blanches peu étudié dans le domaine de la chimie des matériaux, a été retenu. Ce synthon sera modifié pour la conception de macromonomères polymérisables sous irradiation UV. En effet, la technique de photopolymérisation est un procédé propre en plein essor, et qui permet le développement de revêtement.La L-lysine étant peu soluble dans les milieux organiques classiques, une étape de transformation est nécessaire pour améliorer sa processabilité. Ainsi, la polycondensation en masse de la L-lysine a conduit à des oligomères de poly-L-lysine de faibles masses molaires. La détermination de la structure obtenue a été réalisée par différentes techniques d'analyses. Ces oligomères sont alors greffés par des fonctions photopolymérisables dans des conditions douces. Le choix s'est porté sur des fonctions accepteur et donneur d'électron. Enfin, l'étude de la photopolymérisation des oligomères de L-lysine greffés accepteurs donneurs a été effectuée par la technique UV aqueuse, une technique innovante et respectueuse de l'environnement, dans différentes conditions pour en optimiser le système. / Biobased raw materials are an interesting and promising option for the substitution of fossil resources in material design. Moreover, using green processes which limit environmental impact of the material conception can't be avoided nowadays. In this context, the L-lysine amino acid, a building block made by white biotechnologies and poorly described in material field has been evaluated. As photopolymerization is a green process in great expansion and allowing coating design, this building block has been modified into a photocurable macromonomer.L-lysine is hardly soluble in usual organic solvents, a transformation step is necessary in order to improve its processability. Thus, L-lysine polycondensation has been tackled and led to oligomers of poly-L-lysine with low molar mass and improved solubility. In addition, the structure determination has been undertaken by different analytic technics. These oligomers can thus be grafted with photocurable functional groups in mild conditions. The chosen photocurable functional groups are donor acceptor of electron. At last, the photopolymerization of L-lysine based oligomers grafted with donor acceptor functional groups has been done by UV waterborne technic which is innovative and environmentally friendly. The photopolymerization has been carried out in different conditions in order to optimize the process.
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Compréhension des propriétés électro-réflectrices dans l'infrarouge de poly(3,4-éthylènedioxythiophène) électropolymérisé : Des couches modèles aux premiers dispositifs / Study of the electro-reflective properties in the infrared of electropolymerized poly(3,4-ethylenedioxythiophene) : From a model layer to the first device.

Louet, Charlotte 23 July 2015 (has links)
L'objectif de cette thèse est l'élaboration d'un dispositif électro-émissif (DEE) à base de poly(3,4-éthylènedioxythiophène) (PEDOT), obtenu par électropolymérisation, pouvant être envisagé pour une application de régulation thermique des satellites. Pour une meilleure compréhension du comportement optique du PEDOT dans l'IR, des couches modèles ont été élaborées avant la réalisation d'un dispositif complet.La première partie de ce travail a permis de caractériser des couches modèles de PEDOT obtenues par synthèse électrochimique sur ITO dans deux sels différents : le perchlorate de lithium (LiClO4) et le bis-trifluorométhylsulfonylimide de lithium (LiTFSI) dans l'acétonitrile (ACN) comme solvant. La morphologie, la conductivité électronique et les propriétés de réflectivité dans l'IR (gamme de longueur d'onde 8-20µm) du PEDOT ont été étudiées en fonction de l'état d'oxydation du PEDOT. La réflectivité dans l'IR du PEDOT à l'état dopé diminue fortement lorsque la rugosité augmente. Ceci a été attribué à l'augmentation du coefficient d'absorption pour une surface rugueuse comme cela a déjà été reporté pour les métaux. De plus, pour une morphologie identique, il a été montré que la réflectivité des couches modèles de PEDOT évolue avec la conductivité électronique de la même manière, quel que soit le sel utilisé ou la méthode d'élaboration des films. A l'état dopé, les films ont pu être décrits par le modèle de Drude, confirmant le caractère pseudo-métallique du PEDOT. Enfin, un pourcentage de réflectivité maximal de 67% a été obtenu à l'état oxydé et de 21% à l'état réduit, ces résultats donnent une idée des performances pouvant être atteintes dans les DEE à base de PEDOT.La seconde partie de ce travail a permis l'incorporation du PEDOT par électropolymérisation au sein d'une matrice hôte à base de réseau interpénétré de polymère (RIP) combinant le caoutchouc nitrile(NBR) et le poly(oxyde d'éthylène) (POE). Le DEE obtenu est basé sur une architecture tricouches "monobloc". Ainsi, la réalisation d'un DEE à base de RIP conducteur où le PEDOT est incorporé par électropolymérisation simultanément dans les deux faces du dispositif a été validée avec succès. Une fois gonflé d'électrolyte (LiClO4 dans le carbonate de propylène), les propriétés de réflectivité dans l'IR des dispositifs ont été comparées à celles des DEE dans lesquels le PEDOT est synthétisé chimiquement. Les propriétés de réflectivité dans l'IR et de conductivité électronique ont été corrélées de la même manière que pour les couches modèles, prouvant que le comportement du PEDOT varie peu quel que soit la méthode ou le support de synthèse utilisés. / The aim of this work is the elaboration of an electro-emissive (EED) device based on electropolymerized poly(3,4-ethylenedioxythiophene) (PEDOT) for thermal control of satellites. PEDOT layers were prepared before the realization of the device in order to have a better understanding of the PEDOT optical behavior in the IR range.In the first section of this work, PEDOT model layers obtained on ITO electrodes using lithium perchlorate (LiClO4) or lithium bis-trifluoromethylsulfonylimide (LiTFSI) as supporting electrolytes and acetonitrile (ACN) as solvent were characterized. Morphology, electronic conductivity and IR reflectance properties (in the wavelength range 8-20 µm)were studied as a function of the PEDOT doping state. The IR reflectivity of doped PEDOT decreases drastically upon increasing surface roughness. This was attributed to enhanced absorption in the same way as reported for metallic surfaces. In addition, for the same morphology, the IR reflectivity is shown to follow the same trend as a function of the electronic conductivity for both salts. In the oxidized state, the layers can be described by the Drude model, confirming quasi-metallic behavior of PEDOT. Finally, the highest and lowest reflectance obtained for these PEDOT layers is 67% in the doped state ant 21% for the dedoped state respectively, which opens up interesting perspectives in terms of performances for the PEDOT-based EED.In the second part of this work, PEDOT was incorporated by electropolymerization in a host matrix based on interpenetrated polymer network (IPN) combining nitrile butadiene rubber (NBR) and poly(ethylene oxide) (PEO). The obtained EED is based on a monoblock architecture similar to a three-layer device. Thus, the elaboration of conducting IPN based EED by electropolymerization of EDOT has been made simultaneously on both faces of the device. Once the system is swollen by an electrolyte (LiClO4 in propylene carbonate), reflectivity properties of the devices were compared to those obtained by chemical oxidative polymerization of EDOT within the matrix. IR reflectivity and electronic conductivity properties were correlated following the same trend as in PEDOT layers, this means that PEDOT behavior remains the same whatever the synthesis conditions or the electrodes used for electropolymerization.
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La cristallisation de quatre poly(1,3-dioxolannes) de masses molaires différentes

Jiménez, Liliana 12 1900 (has links)
No description available.

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