Title from second page of PDF document. Includes bibliographical references (p. Xx-Xx).

Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Nesta dissertação, foram estudadas a preparação e a caracterização debionanocompósitos à base de gelatina e magnetita. Sacarose foi empregada comoagente de reticulação e gelatina tipo A e gelatina tipo B foram comparadas nautilização para a preparação das microesferas por meio de emulsão água-em-óleo.As microesferas foram caracterizadas por VSM, DSC, TGA, FTIR, testes deinchamento, espectroscopia de absorção atômica, microscopia ótica e microscopiaeletrônica de varredura. Um planejamento de experimentos variando-se aconcentração de gelatina e de sacarose, a temperatura e a velocidade de agitaçãofoi realizado a fim de encontrar quais parâmetros influenciam o diâmetro dasmicroesferas. A concentração de gelatina e velocidade de agitação foram osparâmetros diretamente associados com os tamanhos de partículas. A distribuiçãode tamanho das partículas revelou que o diâmetro das microesferas variou de 5 a 60micrômetros, com predominância na faixa de 11 a 30 micrômetros. A extensão dareticulação foi aumentada com o aumento do tempo de aquecimento na etapa depreparação das microesferas. Todos os bionanocompósitos apresentaramsuperparamagnetismo. Os resultados mostraram que não há diferença significativa entre a utilização de gelatina do tipo A e gelatina do tipo B. Além disso, o estudo de reticulação degelatina revelou que, ao contrário do que diz a literatura, a sacarose não é umagente de reticulação para as cadeias proteicas, pois não foram encontradasevidências de uma reação química entre a sacarose e gelatina / The preparation and characterization of microbeads based on gelatin and magnetite are reported. Sucrose was employed as crosslinking agent and type A gelatin and type B gelatin were compared for preparation of microspheres by water-in-oil emulsion. The microbeads were characterized by VSM, DSC, FTIR, swelling ratio, atomic absorption spectroscopy and optical and scanning electronic microscopy. The influence of gelatin and sucrose concentration, temperature and stirring speed on the microbeads characteristics was studied. The gelatin concentration and stirring speed were the parameters directly associated with the particle sizes. The particle size distribution revealed that the diameter of the microspheres ranged from 5 to 60 micrometers, with predominance in the range from 11 to 30 micrometers. The extent of cross linking increased as a function of preparation heating time periods. The microbeads presented superparamagnetism. The results show that have no significant difference between the utilization of type A gelatin and type B gelatin. In addition, the gelatin crosslinking study revealed that sucrose is not a crosslinking agent because there was no evidence of chemical reaction between sucrose and gelatin

Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Nesta dissertação, foram estudadas a preparação e a caracterização debionanocompósitos à base de gelatina e magnetita. Sacarose foi empregada comoagente de reticulação e gelatina tipo A e gelatina tipo B foram comparadas nautilização para a preparação das microesferas por meio de emulsão água-em-óleo.As microesferas foram caracterizadas por VSM, DSC, TGA, FTIR, testes deinchamento, espectroscopia de absorção atômica, microscopia ótica e microscopiaeletrônica de varredura. Um planejamento de experimentos variando-se aconcentração de gelatina e de sacarose, a temperatura e a velocidade de agitaçãofoi realizado a fim de encontrar quais parâmetros influenciam o diâmetro dasmicroesferas. A concentração de gelatina e velocidade de agitação foram osparâmetros diretamente associados com os tamanhos de partículas. A distribuiçãode tamanho das partículas revelou que o diâmetro das microesferas variou de 5 a 60micrômetros, com predominância na faixa de 11 a 30 micrômetros. A extensão dareticulação foi aumentada com o aumento do tempo de aquecimento na etapa depreparação das microesferas. Todos os bionanocompósitos apresentaramsuperparamagnetismo. Os resultados mostraram que não há diferença significativa entre a utilização de gelatina do tipo A e gelatina do tipo B. Além disso, o estudo de reticulação degelatina revelou que, ao contrário do que diz a literatura, a sacarose não é umagente de reticulação para as cadeias proteicas, pois não foram encontradasevidências de uma reação química entre a sacarose e gelatina / The preparation and characterization of microbeads based on gelatin and magnetite are reported. Sucrose was employed as crosslinking agent and type A gelatin and type B gelatin were compared for preparation of microspheres by water-in-oil emulsion. The microbeads were characterized by VSM, DSC, FTIR, swelling ratio, atomic absorption spectroscopy and optical and scanning electronic microscopy. The influence of gelatin and sucrose concentration, temperature and stirring speed on the microbeads characteristics was studied. The gelatin concentration and stirring speed were the parameters directly associated with the particle sizes. The particle size distribution revealed that the diameter of the microspheres ranged from 5 to 60 micrometers, with predominance in the range from 11 to 30 micrometers. The extent of cross linking increased as a function of preparation heating time periods. The microbeads presented superparamagnetism. The results show that have no significant difference between the utilization of type A gelatin and type B gelatin. In addition, the gelatin crosslinking study revealed that sucrose is not a crosslinking agent because there was no evidence of chemical reaction between sucrose and gelatin

Orientador: Josimeri Hebling / Resumo: Objetivo: Avaliar o desempenho clínico de restaurações de resina composta em lesões cervicais não cariosas (LCNC) realizadas com ou sem a aplicação de um agente de ligação cruzada (carbodiimida, EDC) durante o período de 12 meses. Métodos: 21 pacientes com no mínimo duas LCNC participaram deste estudo. Um total de 142 LCNC foram distribuídas randomicamente em dois grupos (n=71 cada): controle e experimental. Todas as LCNC foram restauradas pelo mesmo operador e com os mesmos materiais (sistema adesivo Adper Single Bond 2 e resina composta Z350), sendo que, no grupo experimental a dentina recebeu a aplicação de EDC 0,5 mol/L por 60 segundos após o condicionamento ácido e no grupo controle apenas PBS. As restaurações foram avaliadas imediatamente após sua confecção (baseline) e após uma semana, 6 e 12 meses pelo critério USPHS/Ryge por apenas um avaliador calibrado. Os escores obtidos a partir da avaliação clínica, considerando-se os fatores de confundimento, foram analisados pelos testes de Woolf e Cochran-Mantel-Haenzel (p<0,05). Resultados: As taxas de falhas acumuladas na retenção das restaurações nos períodos 7 dias, 6 e 12 meses, foram de 0%; 3,0% e 4,5%, respectivamente, para o grupo controle e de 0%; 3,0% e 7,4% para o grupo experimental (EDC). Não houve diferença estatisticamente significante entre os dois grupos para todos os critérios e períodos avaliados. A taxa de retorno dos pacientes nos períodos de 7 dias, 6 e 12 meses foi de 100%, 90,5% e 85,7%, respectivamente... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: o evaluate the clinical performance of composite restorations placed in noncarious cervical lesions (NCCL) performed with or without the application of a cross-linking agent, over a period of 12 months. Methods: 21 patients with at least two NCCL, participated in this study. A total of 142 NCCL were randomly allocated into two groups (n=71): control and experimental. All NCCL were restored by the same operator and with the same materials (Single Bond 2 and Z350). In the experimental group the etched dentin was exposed to 0.5 mol/L EDC for 60 seconds while in the control group the etched dentin was exposed to Phosphate buffer solution (PBS). The restorations were evaluated at baseline, 7 days, 6 and 12 months using the USPHS/Ryge criteria, by one blinded calibrated examiner. The scores from the clinical evaluation were submitted to Woolf and CochranMantel-Haenzel tests, considering the confounding factors (p<0.05). Results: The rates of accumulated failures in the retention of restorations in the periods 7 days, 6 and 12 months were 0%; 3,0% and 4.5%, respectively, for the control group, and 0%; 3,0% and 7.4% for the experimental group. There was no statistically significant difference between the two groups for all criteria and periods. The return rate of patients in the 7-day, 6- and 12-month periods was 100%, 90.5% and 85.7%, respectively. Conclusion: The treatment of the etched dentin with with EDC prior to the application of the dentin bonding agent did not affect the performance of composite resin restorations in NCCL...(Complete abstract electronic access below) / Doutor

CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Devido a busca e necessidade da aplicação de produtos sustentáveis, as blendas e os nanocompósitos a partir de biopolímeros surgem como uma proposta de uso em diversos campos tais como: embalagens, biomedicina e agricultura. Nesse sentido foram desenvolvidos blendas de goma de linhaça/ágar reticulados com glutaraldeído utilizando nanocristais de celulose como reforço, obtidos através do método “casting”. Testes preliminares foram realizados inicialmente variando a proporção de agente reticulante e plastificante além da variação de pH do meio, com o objetivo de promover ligações cruzadas na estrutura e consequente diminuição da hidrofilicidade do material. Seguiu-se o desenvolvimento das blendas em meio ácido fixando as proporções mássicas de aditivos (30% m/m de glicerol e 15% m/m de glutaraldeído em relação a massa final para cada filme), além de variar as proporções dos polímeros (75/25, 50/50 e 25/75 GL/AG). Os nanocompósitos foram obtidos a partir de cada formulação (blendas e amostras controles) com a adição de 2, 4 e 8% m/m de nanocristal de celulose (NC). Os filmes e blendas foram caracterizados pelas técnicas: Calorimetria Exploratória Diferencial, Análise Termogravimétrica, Difração de Raios-X e Infravermelho com Transformada de Fourier a fim de avaliar possíveis interações e organização do sistema. O estudo da reticulação das matrizes poliméricas, de suas blendas e dos nanocompósitos foram avaliados através da interação com a água pelo teste de solubilidade, absorção de vapor de água, ângulo de contato e permeabilidade ao vapor de água. A morfologia das amostras foi estudada por Microscopia Eletrônica de Varredura e por fim, o ensaio sob tração foi realizado para avaliação do desempenho mecânico das amostras. Os eventos endotérmicos observados nas curvas de DSC podem estar associados a novas interações estabelecidas no sistema. As curvas termogravimétricas apresentaram aumento da estabilidade térmica para os filmes controles e as blendas reticuladas em meio ácido. Os difratogramas de DRX apresentaram um padrão difuso de material tipicamente amorfo. Os espectros de FTIR não apresentaram bandas específicas de reticulação, apenas as existentes na estrutura original dos polissacarídeos. As imagens de MEV mostraram boa agregação e dispersão para as blendas e nanocompósitos. Os testes realizados de interação dos filmes com água mostraram que a reticulação em meio ácido levou a menor solubilidade para a formulação de goma de linhaça. A inserção de ágar bem como de NC contribuiu para uma menor absorção de água e melhora nas propriedades mecânicas. As formulações 50/502% NC e 50/504% NC apresentaram aumento da tensão na ruptura, elongamento e módulo de Young demonstrando assim resultados que justificam tanto a obtenção destas blendas quanto dos nanocompósitos. Além disso, com as diferentes morfologias obtidas nesse estudo é possível estender a faixa de aplicação para as formulações propostas. / Nowadays, due to the incentive and the requirement for the use of sustainable products, the blends and nanocomposites from biopolymers appear as a proposal for application in several fields, such as: packaging, biomedicine and agriculture. In this sense, flaxseed gum/agar blends were developed using glutaraldehyde as a crosslinker and cellulose nanocrystals as reinforcement, produced by casting method. Preliminary tests were fulfilled varying the amount of crosslinker agent and plasticizer, changing the pH of the medium in order to insert crosslinks in the polymer structure and consequently decrease the hydrophilicity of the samples. The development of the blends in acid medium by setting the mass proportions of additives (30 wt.% glycerol and 15 wt.% glutaraldehyde relative to the final mass for each film) and varying the polymers proportions (75/25, 50/50 and 25/75 GL/AG). The nanocomposites were obtained from each formulation (blends and control samples) with the addition of 2, 4 and 8% w/w of cellulose nanocrystals (NC). Films and blends were characterized by Differential Scanning Calorimeter, Thermal Gravimetric Analysis, X-ray Diffraction and Attenuated Total Reflectance with Fourier Transforms Infrared Spectroscopy techniques in order to assess possible interactions and organization of the system. The effect of the crosslinking in the polymer matrices, their blends and the nanocomposites were evaluated through the interaction with water by the solubility test, water vapor absorption, contact angle and water vapor permeability. The morphology of the samples was studied by the Scanning electron microscopy and, finally, the tensile test was performed to evaluate the mechanical performance of the samples. The endothermic events observed in the DSC curves may be associated with new interactions established in the polymeric systems. The thermogravimetric curves showed increased thermal stability for the control films and crosslinked blends in acid media. The X-ray diffractograms presented a diffuse pattern of the amorphous material. The infrared spectra did not present specific bands of crosslinking, only those being in the original structure of the polysaccharides. MEV images showed good aggregation and dispersion for blends and nanocomposites. Tests performed on the interaction of the films with water show that crosslinking in acid media led to a lower solubility for the flax gum formulation. The insertion of agar, as well as, the insertion of NC contributed to a lower water absorption and improvement in the mechanical tensile properties. The 50/502%NC and 50/504%NC formulations showed increased tensile rupture, Young's Modulus and elongation thus demonstrating results that justify both blends and nanocomposites originated from these. Moreover, with the different morphologies obtained in this study it is possible to extend the application range for the proposed formulations. / Dissertação (Mestrado)

Orientador: Marcelo Ganzarolli de Oliveira / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-19T16:07:51Z (GMT). No. of bitstreams: 1 Simoes_MairaMartinsdeSouzaGodoy_D.pdf: 6359705 bytes, checksum: 9fb71ed44e3423b6b245f6b70134e270 (MD5) Previous issue date: 2011 / Resumo: O Poli(álcool vinílico) (PVA) é polímero biocompatível que pode ser usado como matriz para a incorporação de S-nitrosoglutationa (GSNO), que é uma molécula endógena que exerce todas as funções bioquímicas do óxido nítrico (NO). Os principais objetivos deste trabalho foram a obtenção de filmes sólidos de PVA capazes de eluir GSNO localmente, que pudessem ser utilizados para aplicações tópicas e para o recobrimento de stents. Os filmes de PVA foram reticulados fisicamente através de ciclos de congelamento/descongelamento (C/D). Verificou-se que a aplicação de 1 a 5 ciclos C/D leva a um aumento da cristalinidade dos filmes comparada aos filmes não submetidos a C/D. Este efeito está associado ao aumento do raio de giro de estruturas espalhadoras de raios X e com a redução do coeficiente de difusão da GSNO. A liberação tópica de GSNO a partir de filmes de PVA na pele de voluntários levou a um aumento significativo do fluxo sanguíneo dérmico, medido por fluxometria com laser Doppler. Demonstrou-se que a aplicação de ciclos C/D pode ser usada para controlar a velocidade e a intensidade de aumento de fluxo sanguíneo. Filmes de PVA/GSNO aplicados como revestimentos de poços de placas de cultura de células mostraram atividade bactericida dose e tempo-dependentes contra cepas de S. aureus e P. aeruginosa, sendo capazes de esterilizar completamente estas duas bactérias multi-resistentes após 6 h de incubação. Filmes de PVA/GSNO permitiram a obtenção de revestimentos aderentes sobre a superfície de stents intracoronários de aço inox levando a uma redução significativa da adesão plaquetária após incubação com sangue total. Estes resultados permitem propor o uso de filmes de PVA/GSNO fisicamente reticulados para aplicações tópicas no tratamento de lesões infectadas, para promover a vasodilatação de tecidos isquêmicos e para a melhoria das propriedades hemocompatíveis de dispositivos de contato sanguíneo / Abstract: Poly(vinyl alcohol) (PVA) is a biocompatible polymer that can be used as a matrix for incorporation of S-nitrosoglutathione (GSNO), an endogenous molecule that exerts all the biochemical functions of nitric oxide (NO). The main objectives of this work were to obtain solid PVA films capable of releasing GSNO locally, which could be used in topical applications and for the coating for stents. PVA films were physically crosslinked through freezing-thawing cycles (F/T).It was observed that films subjected to 1 to 5 cycles shows higher crystallinity than films not subjected to F/T. This effect is associated with an increase in the gyration radius of the X-ray scattering structures an with a decrease in the GSNO diffusion coefficient. Topical GSNO release from PVA films on the skin of volunteers led to a significant increase of dermal blood flow, measured by laser Doppler flowmetry. It was shown that F/T cycles can be used to control the rate and intensity of blood flow increase. PVA/GSNO films applied as coatings of cell-culture plate wells showed dose and time-dependent bactericidal activities against S. aureus and P. aeruginosa, being able of completely sterilizing these mult-resistant bacteria after 6 h of incubation. PVA/GSNO films allowed the formation of adherent coatings on the surface of intracoronary stainless steel stents, and lead to a significant reduction of platelet adhesion after incubation with whole blood. These results allow suggesting the use of physically crosslinked PVA/GSNO films in topical applications for the treatment of infected lesions, for promoting the vasodilation of ischemic tissues and for improving the hemocompatible properties of blood contact devices / Doutorado / Físico-Química / Doutor em Ciências

Les mastics polysulfures sont très utilisés dans l'aéronautique, ceci grâce à leur bonne tenue au froid et leur résistance au carburant. La plupart d'entre eux sont des bicomposants (un polymère polysulfure et un durcisseur avec éventuellement un catalyseur dans l'un des composants). Les formulations de mastic, réticulé au MnO2, permettent d'avoir des temps de gel de 2 jours, avec une réticulation complète au bout de 70 jours. Cependant, ce temps de gel long induit un temps de réticulation trop long. Ainsi, l'objectif de cette thèse était de créer un nouveau type de mastic, qui serait idéalement monocomposant avec un temps de gel toujours long, voir infini et qui réagirait sur demande après stimulus avec un temps de réticulation court. C'est ce qui est appelé le concept SCOD (sealant cure on demand). Pour cela, il faut bloquer un des trois réactifs, et que celui-ci soit déblocable sur demande à l'aide d'un stimulus simple industriellement tel que la température (cible entre 60-80°C). Le concept de blocage choisi est la réaction de Diels-Alder sur des composés accepteurs de Michaël. En effet, cette réaction est réversible et la cycloréversion permet la déprotection de la double liaison réactive. Après déblocage, l'accepteur de Michaël peut réagir avec le polysulfure. Une première étude, sur les accepteurs de Michaël, a permis de déterminer que les fonctions maléimides, en présence de DABCO, donnent les meilleures cinétiques pour la réaction avec les thiols du polysulfure. Une deuxième étude, sur la réaction de Diels-Alder et rétroDiels-Alder, a prouvé la faisabilité du projet et a permis de sélectionner les dérivés du furane comme agents bloquants pour répondre à la fourchette de température imposée. Ensuite, des durcisseurs polymaléimides aliphatiques ont été synthétisés à l'aide des Jeffamines® d'Huntsman et bloqués avec le furfuryl acétate, afin d'être utilisés pour la création de matériaux suivant le concept SCOD. Le temps de gel obtenu avec les durcisseurs bloqués, était de 7 jours et un matériau était obtenu après 17 heures de chauffe. Le concept SCOD a donc été démontré. Cette étude a, ensuite, été extrapolée au Centre de Recherche d'Hutchinson en formulation modèle sur de plus grandes quantités. Aussi, les propriétés des mastics obtenus ont été déterminées et répondaient à une majorité des critères du cahier des charges.. Le déblocage a été amélioré après ajout d'un thiol tétrafonctionnel (PETMA, co-agent) et l'utilisation d'un autre catalyseur (DBU), Le temps de déblocage étant encore trop long et le bloquant, relargué dans la formulation, forme des porosités dans le mastic et dégrade, de fait, les propriétés de celui-ci. Ainsi une dernière partie d'amélioration a été effectuée. En effet, dans celle-ci, une nouvelle génération de durcisseur, cette fois-ci aromatique, et d'agent bloquant, jouant le rôle de plastifiant non volatil, a été créée et testée en laboratoire. Ceux-ci ont présenté de très bons résultats préliminaires avec des temps de déprotection plus courts et des bloquants moins volatils à la température de déblocage comparé au furfuryl acétate. L'extrapolation doit se poursuivre fin 2014-début 2015 sur ces nouveaux durcisseurs en formulation mastic modèle. / Polysulfide sealants are widely used in aviation because of their good resistance to low temperature and to fuels. Most of them are bycomponent (a polysulfide polymer and a crosslinking agent and, eventually a curing catalyst in one of them). These sealant formulations, crosslinked with MnO2, have a gel time of two days, with a full curing after 70 days. However, because of this short gel time, the curing time is too long. Thus, the objective of this thesis was to create a new type of sealant, monocomponent, with still a long gel time, ideally infinite, that could react on demand after stimulus, in order to have a short curing time. This concept is called SCOD concept (sealant cure on demand). These criteria require to block one of the three products, and this one should be unblocked on demand using an ease stimulus such as temperature. The system chosen as blocking principle is the Diels-Alder reaction of a Michaël acceptor. Indeed, this reaction is reversible and the cycloreversion allows to unprotect the reactive double bond. After the unblocking reaction, the Michaël acceptor may react with the polysulfide. A primary study, on Michael acceptors, allowed to determine that maleimide function, in the presence of triethylamine, gives the best kinetics for reaction with polysulfide's thiol. A second study, this time on the Diels-Alder and retroDiels-Alder reaction, proved the feasibility of the project and allowed to select furan derivatives as blocking agents. Then, aliphatic polymaleimides hardeners were synthesized using Huntsman's Jeffamine and were blocked with the acetate furfuryl, so as to be used for creating SCOD materials. The gel time obtained with blocked hardener was 7 days at room temperature and after heating for 17 hours, a material was obtained; the SCOD concept has been demonstrated. The study was, then, extrapolated to Hutchinson's research and development department on bigger quantities to do some basic formulation. In addition, the sealant's characteristics have been determined and have shown very interesting results. Unblocking time was improved after adding tetrafunctional thiols (co-agent) and one another catalyst (DBU). The unblocking time was too long and the blocking agent, once released into the formulation, formed porosities into the sealant and, because of it, damaged the properties of the sealant. A latter part was done to improve the SCOD concept. Two new generations of hardener, aromatic this time, and blocking agent, acting as a non-volatile plasticizer, were created and tested in laboratory. These have presented very good preliminary results. Indeed, the unblocking time is much shorter and the unblocking agent is less volatile at high temperature compare to acetate furfuryl. The scaling up to pilot level is under way (end of 2014).

Die Funktionalisierung von tetra-PEG Makromolekülen mit fotoreaktiven Gruppen und die anschließende Umsetzung zu Hydrogelen durch fotochemische Vernetzung werden beschrieben. Die Funktionalisierung der Makromoleküle wird mittels UV-Vis- und NMR-Spektroskopie nachgewiesen, während der Verlauf der Vernetzung über die dynamische Lichtstreuung und IR-Spektroskopie betrachtet wird. Die hergestellten Hydrogele werden hinsichtlich des Sol-Anteils und der Quelleigenschaften untersucht. Über den Umsatz wird die Konzentration der Netzketten theoretisch berechnet. Einen weiteren Schwerpunkt bildet die Charakterisierung der Hydrogele hinsichtlich der mechanischen Eigenschaften. Über den Speichermodul wird die Konzentration der Netzketten experimentell bestimmt. Mittels dynamischer Lichtstreuung werden die kooperativen Diffusionskoeffizienten und Maschenweiten der Hydrogele bestimmt.

Proteins are essential parts of living organisms that initiate and control almost all cellular processes. Despite the widely accepted belief that all functional proteins fold into stable and well-defined three-dimensional (3D) structures mandatory for protein activity, the existence of biologically functional disordered proteins has been increasingly recognized during past two decades. Proteins with inherent structural disorder, commonly known as intrinsically disordered proteins (IDPs), play many roles in a biological context. However, in contrast to their folded counterparts, they are dynamically unstructured and typically fluctuate among many conformations even while performing biological functions. In fact, it is this dynamical structural heterogeneity that that allows for IDPs to interact with other biological macromolecules in unique ways. Moreover, while a majority of proteins in eukaryotic proteomes have been found to have intrinsically disordered regions (IDR), the mechanisms by which protein disorder fives rise to biological functionality is still not well understood. Through a series of simulation studies on specific systems, this thesis probes several aspects of the emerging structure-function paradygm of IDPs, namely the mechanics, intermolecular assembly, and structural transitions occurring in these proteins. The lack of well-defined 3D structure in IDPs gives rise to distinct mechanical properties, the subject of the first study in the thesis on the elasticity of a elastomeric gluten-mimetic polypeptide with an intrinsically disordered character. This disordered polypeptide was shown to exhibit distinctively variable elastic response to a wide range of tensions, which a classical worm-like chain model failed to accurately describe, thus requiring a molecular-level analysis. IDPs frequently are frequently involved in protein-protein interactions, the focus of the second study on the propensity of an IDR, the B domain in dynamin-related protein 1 (Dpr1), to self-assemble into dimer structures while remaining disordered in all solution conditions. Despite a hypothesized auto-inhibitory role for this domain in Dpr1 that was assumed to be triggered by an disordered-to-order transition, the B domains in solution showed no tendency to form ordered structures even in the presence of order promoting osmolytes. Instead, self-association in the presence of osmolyte was found to occur by favorable intermolecular intereactions between specific region on the surface of the B-domains. Other IDPs do undergo a disorder-to-order transition in response to environmental cues, in ways that are unique disordered proteins, the focus of the last study on intermolecular ordering transitions in silk-like proteins. Factors such as protein sequence and physical tension were investigated, and results suggested that tyrosine residues in the key silk sequence motifs promote templating of beta structure from disordered precursors and that elongational stresses preferentialy stabilize antiparallel beta-sheet order. Together, these three computational studies provide insight into the nature of the structure-function mechanisms of IDPs.

L'utilisation de la réaction de cycloaddition 1,3 de Huisgen afin d'optimiser les propriétés de polymères fluorés constitue l'objectif de ce travail. Cette cycloaddition a été étudiée selon deux stratégies spécifiques. La première consiste en une cycloaddition, réalisée entre un groupe azidé et une fonction nitrile, non catalysée, tandis que la seconde concerne la cycloadditon, catalysée par le cuivre, entre un groupe azido et une fonction alcyne dont la réaction est classiquement appelée « click chemistry ». Le premier chapitre est consacré à une étude bibliographique sur la réticulation et la post-réticulation chimiques des polymères à température ambiante et à des températures inférieures à 150 °C. Cette étude décrit de façon quasi-exhaustive les différentes réactions chimiques permettant de réaliser une réticulation, et ce en les classant par fonctions clés. Le second chapitre décrit la réticulation d'un élastomère fluoré commercial, porteur de fonction nitrile par cycloaddition 1,3 de Huisgen non catalysée à l'aide d'un agent réticulé fluoré téléchélique bisazidé. Une étude modèle de la réaction de cycloaddition mettant en jeu une réaction nitrile-azide à l'aide de composés moléculaires afin de déterminer les meilleures conditions de réaction. Le troisième chapitre concerne le greffage d'un composé phthalocyanine sur un copolymère fluoré (de type poly(chlorotrifluoéthylène-co-2-iodoethyl vinyl éther) par cycloaddition de Huisgen catalysée au cuivre, ou « click chemistry », dans le but d'obtenir un composé possédant des propriétés photovoltaïques intéressantes. / The objective of this work deals with the Huisgen 1.3 cycloaddition reaction to optimize the properties of fluoropolymers. This cycloaddition is investigated using two main strategies. The first one concerns a cycloaddition performed between an azide group and a nitrile function, and non-catalyzed, while the second one is a copper-catalyzed cycloadditon, involving a group azide and an alkyne function and this reaction is conventionally called "click chemistry". The first chapter is devoted to a non-exhaustive literature review on the chemical crosslinking and post-crosslinking polymers carried out at room temperature and at temperatures below 150 ° C. This study describes a list of different chemical reactions to achieve a crosslinking, and that classifying them by key functions. The second chapter describes the crosslinking of commercially available, fluoroelastomer, bearing nitrile groups by 1,3 Huisgen uncatalyzed cycloaddition using a telechelic fluorintaed bisazido crosslinking agent. This chapter exhibits first a model study of the cycloaddition involving a nitrile-azide reaction to determine the best reaction conditions. The third chapter concerns the grafting of an alkyne phthalocyanine compound onto a fluorinated copolymer (poly(chlorotrifluoethylene-co-2-iodoethyl vinyl ether) by 1,3 Huisgen cycloaddition catalyzed by copper, or "click chemistry", to obtain a compound having good photovoltaic properties.