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

Foldamères d’oligoamides aromatiques : des doubles hélices artificielles aux ligands de G-quadruplex

Baptiste, Benoît 17 December 2009 (has links)
Les oligopyridine-dicarboxamides et les oligoquinoline-carboxamides sont des oligomères synthétiques capables d’adopter des conformations hélicoïdales stables et bien définies. Les premiers sont comparables à des ressorts moléculaires qui peuvent s’étirer puis s’autoassembler pour former des doubles hélices artificielles. L’étude structurale d’oligopyridines de différentes tailles par diffraction des rayons X et RMN a permis d’éclaircir les principes de l’hybridation en double hélice. Par exemple, nous constatons que la stabilité du duplex est d’autant plus grande que l’oligomère est long mais la cinétique de l’hybridation décroit avec la taille des hélices. Ces propriétés sont modulables en fonction de divers paramètres tels que le solvant ou les substituants des pyridines. Les seconds forment de simples hélices moléculaires stables dans les solvants organiques mais aussi dans l’eau. Nous avons développé leur synthèse sur support solide afin de disposer de séquences variées, à l’image des alpha-peptides. Des études par RMN suggèrent que l’introduction d’unités aminométhylpyridines au sein d’un oligoquinoline hydrosoluble apporte de la flexibilité sans perturber sa structure hélicoïdale. Cela témoigne de la stabilité de ces structures secondaires dans les solvants protiques. Par ailleurs, certains de ces peptidomimes s’avèrent capables de reconnaitre et stabiliser des motifs structuraux particuliers de l’ADN : les G-quadruplex. Etant donné que ces architectures se forment à des endroits clés du génome impliqués dans des cancers, ces hélices moléculaires font figure de potentiels agents antitumoraux d’un nouveau genre. / Oligopyridine-dicarboxamides and oligoquinoline-carboxamides are synthetic oligomers able to fold into stable and well defined helical conformations. The first ones are comparable to molecular springs which can extend then associate to form artificial double helices. A structural study of oligopyridines of various sizes by X-ray diffraction and NMR provided a better understanding of the hybridization process. For example, we noticed that the stability of the duplex is all the higher as the oligomer is long but the kinetics of hybridization decrease with length. These properties depend on diverse parameters such as the solvent or the substituants of pyridine rings. The second family forms stable single helices in organic solvents and also in water. We adapted their synthesis on solid support to promote accessibility to a variety of sequences, just like for alphas-peptides. NMR studies suggested that the introduction of aminomethylpyridine units within a hydrophilic oligoquinoline strand brings some flexibility without disrupting its helical structure, showing the high stability of these secondary structures in protic solvents. Besides, some of these peptidomimetics turn out to be capable of recognizing and stabilizing a particular DNA motif: G-quadruplex structure. Given that these architectures form in critical places of the genome involved in cancers, these molecular helices may represent a new class of potential antitumoral agents.
12

La réaction de transfert O-N acylique : nouvelles applications pour la synthèse de peptides et de polypeptides / New methodologies for peptides and polypeptides synthesis using the O-N acyl shift

Tailhades, Julien 23 April 2010 (has links)
Nous nous sommes attachés à trouver de nouvelles applications de la réaction de transfert O-N acylique pour la synthèse de peptides et de polypeptides. Nous avons mis au point une nouvelle voie pour la synthèse de peptide alcool sur support solide. Cette méthodologie a permis de préparer 3 peptides alcool modèles comme l'Octréotide avec de bons rendements et d'excellentes puretés. Nous avons développé une nouvelle stratégie pour la synthèse de polyamide à partir de polyester via une réaction de multi-transfert O-N acylique. Pour cela, nous avons isolé trois générations de polymères : les polyesters Z-protégés après polymérisation, les polyesters hydrosolubles après le clivage des groupements Z et les polyamides après multi-transfert O-N acylique dans des conditions basiques organiques et à pH physiologique. Cette stratégie a été appliquée à la synthèse de polyamide de sérine et de sérine gamma-homologuée. Maintenant, nous développons une nouvelle stratégie de polymérisation de séquence peptidique contenant une sérine N-protégée en position N-terminale. Comme décrit précédemment pour les polysérines, les objectifs de cette étude sont de synthétiser in fine des polypeptides à partir des polypeptides/esters correspondants. / We founded some news applications of the O-N acyl transfer, notably for the synthesis of peptides and polypeptides. We optimized a new general voice for the preparation of peptides alcohol on solid support. This methodology permits to synthesize 3 peptides alcohol with yield and purity, notably Octreotide. We developed a new strategy for the synthesis of polyamide from polyester using an O-N acyl multi-transfer reaction. We have isolated 3 generations of polymers: the Z-protected polyesters after polymerization (polycondensation and ROP), the unprotected water-soluble polyesters after the cleavage of the protection Z and the polyamides after the O-N acyl multi-transfer in basic organic condition or in phosphate buffer. This methodology was applied to the synthesis of the polyamide serine and gamma-homologated serine. Currently, we are developing a new methodology for the polymerization peptide sequence containing an N-protected serine in N-terminal position. As previously described on polyserine, the objectives of this polymerization are to generate polypeptides from the corresponding polypeptides/esters.
13

Influences de l'oxydation et de la biodégradation anaérobie sur la matière organique de l'argile oligocène de Boom (Mol, Belgique) : Conséquences sur la formation d'espèces organiques hydrosolubles / Influence of air oxidation and anaerobic biodegradation on the organic matter of oligocene Boom clay formation (Mol, Belgium) : Consequences on the formation of the soluble organic species

Blanchart, Pascale 13 December 2011 (has links)
Les Argiles de Boom ont été identifiées par le SCK-CEN comme un éventuel site de stockage de déchets nucléaires en couche géologique profonde : elles font l’objet d’études dans le laboratoire souterrain de Mol (Belgique). Dans ce contexte, il est important d’évaluer les conséquences du creusement de galeries sur les propriétés de ces Argiles. Ce travail de thèse cible plus particulièrement les effets d’oxydation à l’air et de biodégradation anaérobie sur la MO fossile. Les expériences d’oxydation ont combiné des suivis expérimentaux (série artificielle) et des études sur des échantillons altérés in situ (série naturelle) dans les galeries du laboratoire. Elles ont ciblé le kérogène, la MOE et MOD. La confrontation des données des deux séries révèle que nos simulations expérimentales sont représentatives des processus ayant lieu dans les galeries. Ces travaux démontrent aussi que l’oxydation induit (i) une augmentation importante de la quantité de MOD et (ii) une modification majeure de la chimie de la MOE et de la MOD caractérisée par la formation de molécules oxygénées de faible poids moléculaire. Par ailleurs, l’étude comparative des eaux issues des échantillons altérés avec celles prélevées dans les piézomètres du site démontre que ces dernières ne sont pas affectées par des processus d’oxydation et sont comparables aux eaux issues des échantillons sains. Des expériences de biodégradation menées sur des argiles saines et préalablement oxydées artificiellement n’ont montré aucune évolution significative de la MO fossile (MOE et MOD); la biodégradation anaérobie n’est donc pas un processus dominant dans le contexte des perturbations induites par les excavations / The Boom Clay was focused because it is identified by SCK-CEN as a possible radioactive waste storage in the geological disposal site and in situ experiments are performed in the underground laboratory of Mol (Belgium). In this context, it is important to assess the consequences of galleries excavation on the properties of the Boom Clay. The particular focus of this study is the effects of air oxidation and anaerobic biodegradation on the OM. The experiments dealing with the effects of air oxidation have combined studies of artificial oxidized samples (artificial series) and samples altered in the gallery of the underground laboratory (natural series). These experiments focus on the Kerogen, the EOM and the DOM. The comparison of data from artificial and natural series shows firstly that our experimental simulations are the representative of processes taking place in the galleries. These studies show that air oxidation induced (i) a significant increase in the amount of DOM and (ii) a major change in the chemistry of the EOM and DOM characterized by the formation of low molecular weight oxygenated molecules. Moreover, comparison between water extracted from altered samples and piezometers shows that the water of the site is not affected by oxidation processes. The piezometer water samples are similar to that extracted from non-altered samples. Biodegradation experiments conducted on non altered and artificially oxidized clay did not show significant changes of fossil and dissolved organic matter. It seems that anaerobic biodegradation is not a major process in the context of disturbances induced by the excavation
14

Bebida prebiótica à base de amêndoa da castanha de caju: estudos com consumidores em diferentes abordagens para avaliação de fatores sensoriais e externos ao produto / Cashew nut kernel-based prebiotic beverage: A study with consumers in different approaches for the evaluation of sensory and external factors to the product

Rebouças, Marina Cabral January 2016 (has links)
RERBOUÇAS, Marina Cabral. Bebida prebiótica à base de amêndoa da castanha de caju: estudos com consumidores em diferentes abordagens para avaliação de fatores sensoriais e externos ao produto. 2016. 117 f. : Tese (doutorado) - Universidade Federal do Ceará, Centro de Ciências Agrárias, Departamento de Tecnologia de Alimentos, Fortaleza-CE, 2016 / Submitted by Nádja Goes (nmoraissoares@gmail.com) on 2016-07-08T13:07:50Z No. of bitstreams: 1 2016_tese_mcreboucas.pdf: 2626341 bytes, checksum: e0b191879ed659a68c541e05ea4d4613 (MD5) / Approved for entry into archive by Nádja Goes (nmoraissoares@gmail.com) on 2016-07-08T13:08:22Z (GMT) No. of bitstreams: 1 2016_tese_mcreboucas.pdf: 2626341 bytes, checksum: e0b191879ed659a68c541e05ea4d4613 (MD5) / Made available in DSpace on 2016-07-08T13:08:22Z (GMT). No. of bitstreams: 1 2016_tese_mcreboucas.pdf: 2626341 bytes, checksum: e0b191879ed659a68c541e05ea4d4613 (MD5) Previous issue date: 2016 / Prebiotic beverages made from cashew nut kernels and fruit juice are a viable alternative in the area of new functional products’ development. Thus, this research aimed to develop three prebiotic beverages made from cashew nut kernels added with fruit juice (grape, mango and pineapple), evaluating how non-sensory attributes (external to the product) and consumers’ characteristics as to behavior and personality affect their acceptance. A factorial 2² central composite rotatable design was used for the development of the formulations. Focus groups were applied to define the most important label attributes on consumer’s purchasing decision. The illustration, nutritional information and the term prebiotic associated with its functional claim, within their respective levels, were selected for the labels’ development via the 3x2x3 full factorial design and the employment of conjoint analysis and cluster analysis multi-varying techniques for results evaluation. The mango beverage was evaluated displaying three different label versions in order to check if the expectation generated by different nutritional information affected consumers’ perception as to characteristics of quality, overall impression and purchasing attitude. The beverage added with pineapple juice was compared to its soy-based commercially similar in order to evaluate if information on composition, nutritional characteristics and functional claims associated with these products affect the acceptance and perception of consumers with different behavioral characteristics and personality. The formulations optimized as to acceptance should be added with the following concentrations of sugar and juice, respectively; grape beverage (37% and 7%), pineapple (35% and 7%) and mango (40% and 8%). Among the most important label attributes in the purchasing process, the illustration was the one that mostly influenced, followed by nutritional information and the term prebiotic and its functional claim. The nutritional claims displayed on the label revealed to have a positive impact over the perception of the beverage as to the characteristics of quality, overall impression and purchasing attitude, with information such as “0% lactose, 0% cholesterol and fiber-rich” and “0% lactose, 0% cholesterol and antioxidants” found to influence more positively consumers. Information related to the beverages made from soy and cashew nut did not influence the acceptance of flavor nor on the overall impression, nonetheless, it had a positive impact over consumers’ perception as to healthiness and the nutritious value of both, being the cashew nut kernel-based beverage perceived as more nutritious and healthier than the soy-based one. Consumers’ different characteristics as to the interest in healthy eating and food neophobia did not influence the acceptance of the beverages, their perception as healthy food and nutritious value. / Bebida prebióticas à base de amêndoas de castanha de caju e suco de frutas é uma alternativa viável na área de desenvolvimento de novos produtos funcionais. Assim, este trabalho objetivou desenvolver três bebidas prebióticas à base de amêndoa da castanha de caju adicionadas de suco de frutas (uva, manga e abacaxi), avaliando de que forma atributos não sensoriais (externos ao produto) e características comportamentais e de personalidade dos consumidores afetam a sua aceitação. Utilizou-se um delineamento fatorial 22 do tipo composto central rotacionado para desenvolvimento das formulações. Grupos de foco foram empregados para definição dos atributos do rótulo mais importantes na decisão de compra do consumidor. A ilustração, as informações nutricionais e o termo prebiótico associado a sua alegação funcional, com seus respectivos níveis, foram selecionados para o desenvolvimento dos rótulos por meio de delineamento fatorial completo do tipo 3 x 2 x 3, aplicando-se as técnicas multivariadas conjoint analysis e cluster analysis para avaliação dos resultados. A bebida de manga foi avaliada associada a três versões do rótulo para verificar se a expectativa gerada por diferentes informações nutricionais afetavam a percepção dos consumidores quanto às características de qualidade, impressão global e atitude de compra. A bebida adicionada de suco de abacaxi foi comparada frente ao seu similar comercial à base de soja para avaliar se informações sobre composição, características nutricionais e alegações funcionais associadas a estes produtos afetam a aceitação e percepção dos consumidores com diferentes características comportamentais e de personalidade. As formulações otimizadas quanto à aceitação devem ser adicionadas das seguintes concentrações de suco e açúcar, respectivamente, para a bebida de uva (37% e 7%), abacaxi (35% e 7%) e manga (40% e 8%). Dentre os atributos do rótulo mais importantes no processo de compra, a ilustração foi o que mais influenciou, seguido pelas informações nutricionais e pelo termo prebiótico e sua alegação funcional. As alegações nutricionais no rótulo mostraram ter um impacto positivo na percepção da bebida quanto às características de qualidade, impressão global e atitude de compra, com os as informações “0% lactose, 0% colesterol e fonte de fibras” e “0% lactose, 0% colesterol e antioxidantes” influenciando mais positivamente os consumidores As informações relacionadas às bebidas de soja e castanha de caju não influenciaram a aceitação do sabor e impressão global, no entanto tiveram um impacto positivo na percepção dos consumidores quanto à saudabilidade e o valor nutritivo de ambas, sendo a bebida à base de amêndoa da castanha de caju percebida como mais nutritiva e mais saudável do que a bebida de soja. As diferentes características dos consumidores quanto ao interesse em alimentação saudável e a neofobia alimentar não tiveram influência sobre a aceitação das bebidas, a percepção de alimento saudável e valor nutritivo.
15

Cashew nut kernel-based prebiotic beverage: A study with consumers in different approaches for the evaluation of sensory and external factors to the product / Bebida prebiÃtica à base de amÃndoa da castanha de caju: estudos com consumidores em diferentes abordagens para avaliaÃÃo de fatores sensoriais e externos ao produto

Marina Cabral RebouÃas 19 February 2016 (has links)
CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Prebiotic beverages made from cashew nut kernels and fruit juice are a viable alternative in the area of new functional productsâ development. Thus, this research aimed to develop three prebiotic beverages made from cashew nut kernels added with fruit juice (grape, mango and pineapple), evaluating how non-sensory attributes (external to the product) and consumersâ characteristics as to behavior and personality affect their acceptance. A factorial 2 central composite rotatable design was used for the development of the formulations. Focus groups were applied to define the most important label attributes on consumerâs purchasing decision. The illustration, nutritional information and the term prebiotic associated with its functional claim, within their respective levels, were selected for the labelsâ development via the 3x2x3 full factorial design and the employment of conjoint analysis and cluster analysis multi-varying techniques for results evaluation. The mango beverage was evaluated displaying three different label versions in order to check if the expectation generated by different nutritional information affected consumersâ perception as to characteristics of quality, overall impression and purchasing attitude. The beverage added with pineapple juice was compared to its soy-based commercially similar in order to evaluate if information on composition, nutritional characteristics and functional claims associated with these products affect the acceptance and perception of consumers with different behavioral characteristics and personality. The formulations optimized as to acceptance should be added with the following concentrations of sugar and juice, respectively; grape beverage (37% and 7%), pineapple (35% and 7%) and mango (40% and 8%). Among the most important label attributes in the purchasing process, the illustration was the one that mostly influenced, followed by nutritional information and the term prebiotic and its functional claim. The nutritional claims displayed on the label revealed to have a positive impact over the perception of the beverage as to the characteristics of quality, overall impression and purchasing attitude, with information such as â0% lactose, 0% cholesterol and fiber-richâ and â0% lactose, 0% cholesterol and antioxidantsâ found to influence more positively consumers. Information related to the beverages made from soy and cashew nut did not influence the acceptance of flavor nor on the overall impression, nonetheless, it had a positive impact over consumersâ perception as to healthiness and the nutritious value of both, being the cashew nut kernel-based beverage perceived as more nutritious and healthier than the soy-based one. Consumersâ different characteristics as to the interest in healthy eating and food neophobia did not influence the acceptance of the beverages, their perception as healthy food and nutritious value. / Bebida prebiÃticas à base de amÃndoas de castanha de caju e suco de frutas à uma alternativa viÃvel na Ãrea de desenvolvimento de novos produtos funcionais. Assim, este trabalho objetivou desenvolver trÃs bebidas prebiÃticas à base de amÃndoa da castanha de caju adicionadas de suco de frutas (uva, manga e abacaxi), avaliando de que forma atributos nÃo sensoriais (externos ao produto) e caracterÃsticas comportamentais e de personalidade dos consumidores afetam a sua aceitaÃÃo. Utilizou-se um delineamento fatorial 22 do tipo composto central rotacionado para desenvolvimento das formulaÃÃes. Grupos de foco foram empregados para definiÃÃo dos atributos do rÃtulo mais importantes na decisÃo de compra do consumidor. A ilustraÃÃo, as informaÃÃes nutricionais e o termo prebiÃtico associado a sua alegaÃÃo funcional, com seus respectivos nÃveis, foram selecionados para o desenvolvimento dos rÃtulos por meio de delineamento fatorial completo do tipo 3 x 2 x 3, aplicando-se as tÃcnicas multivariadas conjoint analysis e cluster analysis para avaliaÃÃo dos resultados. A bebida de manga foi avaliada associada a trÃs versÃes do rÃtulo para verificar se a expectativa gerada por diferentes informaÃÃes nutricionais afetavam a percepÃÃo dos consumidores quanto Ãs caracterÃsticas de qualidade, impressÃo global e atitude de compra. A bebida adicionada de suco de abacaxi foi comparada frente ao seu similar comercial à base de soja para avaliar se informaÃÃes sobre composiÃÃo, caracterÃsticas nutricionais e alegaÃÃes funcionais associadas a estes produtos afetam a aceitaÃÃo e percepÃÃo dos consumidores com diferentes caracterÃsticas comportamentais e de personalidade. As formulaÃÃes otimizadas quanto à aceitaÃÃo devem ser adicionadas das seguintes concentraÃÃes de suco e aÃÃcar, respectivamente, para a bebida de uva (37% e 7%), abacaxi (35% e 7%) e manga (40% e 8%). Dentre os atributos do rÃtulo mais importantes no processo de compra, a ilustraÃÃo foi o que mais influenciou, seguido pelas informaÃÃes nutricionais e pelo termo prebiÃtico e sua alegaÃÃo funcional. As alegaÃÃes nutricionais no rÃtulo mostraram ter um impacto positivo na percepÃÃo da bebida quanto Ãs caracterÃsticas de qualidade, impressÃo global e atitude de compra, com os as informaÃÃes â0% lactose, 0% colesterol e fonte de fibrasâ e â0% lactose, 0% colesterol e antioxidantesâ influenciando mais positivamente os consumidores As informaÃÃes relacionadas Ãs bebidas de soja e castanha de caju nÃo influenciaram a aceitaÃÃo do sabor e impressÃo global, no entanto tiveram um impacto positivo na percepÃÃo dos consumidores quanto à saudabilidade e o valor nutritivo de ambas, sendo a bebida à base de amÃndoa da castanha de caju percebida como mais nutritiva e mais saudÃvel do que a bebida de soja. As diferentes caracterÃsticas dos consumidores quanto ao interesse em alimentaÃÃo saudÃvel e a neofobia alimentar nÃo tiveram influÃncia sobre a aceitaÃÃo das bebidas, a percepÃÃo de alimento saudÃvel e valor nutritivo.
16

Synthèse, analyses structurales et assemblage de foldamères oligoamide hydrosolubles à base de quinolines / Synthesis, structural analysis, and assembly of water soluble quinoline-based oligoamide foldamers

Hu, Xiaobo 15 June 2017 (has links)
La chimie des foldamères est un domaine de recherche en pleine expansion où les chimistes explorent la construction d’architectures artificielles variées mimant les structures repliées des biopolymères naturels. Les foldamères d’oligoamides quinoline, constituent une branche importante des foldamères montrant de nombreuses caractéristiques attractives, incluant la stabilité et la prédictibilité de leurs conformations repliées, qui en font de bons candidats pour des applications biologiques. Jusqu’à présent, la plupart des études sur les foldamères d’oligoamides quinolines ont été menées dans des solvants organiques. Cette thèse a pour objectif d’étendre leur portée au milieu aqueux et présente plusieurs méthodologies pour parvenir à leur solubilité, leur repliement, la variation de leurs chaines latérales, leur agrégation et leur capacité à former des cristaux dans l’eau.Tout d’abord, une méthode de synthèse en phase solide a été développée permettant l’accès rapide aux foldamères hybrides α-amino acide/quinoline (X/Q). Leur étude dans l’eau montre que contrairement aux foldamères hybrides de type (XQ)n, ceux de type (XQ2)n sont capables d’adopter une conformation hélicoïdale présentant un alignement des chaines α-amino acides dans l’espace. Ensuite, plusieurs chaines latérales courtes ont été identifiées pour doter les foldamères aromatiques d’une solubilité et d’une capacité à cristalliser dans l’eau. Six oligoamides quinoline ont ainsi été synthétisés pour une étude modèle. Des cristaux ont été obtenus pour toutes les séquences sauf une, présentant une excessive solubilité dans l’eau. Enfin, des efforts ont été faits pour construire des faisceaux d’hélices auto-assemblés dans l’eau à base d’effets hydrophobes et d’interactions électrostatiques. Les études RMN et cristallographiques ont indiqué que les effets hydrophobes étaient plus faibles qu’attendu et ne provoquaient pas d’agrégation forte. / Foldamer chemistry is a rapidly expanding research field where chemists explore the construction of various artificial architectures that mimic the folded structures of biopolymers found in nature. Quinoline oligoamide foldamers, as an important branch of foldamers, have been shown to possess many desirable features, including stability and predictability of their folded conformations, and are promising candidates to achieve biological applications. Up to now, most investigations of quinoline oligoamide foldamers have been carried out in organic solvents. This thesis is aimed to expand their scope in aqueous medium and presents several methodologies to achieve solubility, folding, side-chain variation, aggregation and crystal growth ability in water.First, a solid phase synthesis method was developed to enable the fast access to α-amino acid/quinoline (X/Q) hybrid oligoamide foldamers. The study of these hybrid foldamers in water showed that contrary to (XQ)n-type foldamers the (XQ2)n-type foldamers could adopt aromatic helical conformations with α-amino acid side chains aligned in space. Then, several short side chains were identified to endow aromatic foldamers with both solubility in, and crystal growth ability from water. Six quinoline oligoamides displaying these side chains were synthesized as a case study. Crystals were obtained from aqueous medium in all cases but one, exceedingly soluble in water. At last, efforts were made to construct self-assembled aromatic helix bundles in water based on hydrophobic effects and electrostatic interactions. NMR and crystallographic studies indicated that hydrophobic effects are weaker than expected and not strongly conducive of aggregation.
17

Polymérisation radicalaire contrôlée par les nitroxydes en émulsion sans tensioactif pour le développement industriel de latex à morphologies variées / Nitroxide-mediated polymerization induced self-assembly in emulsion for the industrial development of latexes with well-defined nanoobjects

Groison, Émilie 04 November 2013 (has links)
La synthèse de macroalcoxyamines hydrosolubles à partir d’acide méthacrylique et d’un faible pourcentage de styrène sulfonate de sodium a été étudiée en solution aqueuse. Ces macroalcoxyamines ont été utilisées comme macroamorceurs pour la polymérisation en émulsion sanstensioactif du méthacrylate de méthyle et du méthacrylate de n-butyle avec un faible pourcentage destyrène. Les copolymères diblocs amphiphiles produits s’auto-assemblent in situ et conduisent, en fonction de leur taux d’hydrophilie, à l’obtention de nano-objets présentant des morphologies variées(sphères, fibres, vésicules). La plus intéressante est la morphologie fibrillaire car les suspensions correspondantes présentent des propriétés rhéofluidifiantes à basse concentration et possèdent un comportement viscoélastique à haute concentration. La synthèse de ces latex a été étudiée et développée dans des conditions monotopes les plus proches possibles d’une production industrielle. / Water-soluble, SG1-based macroalkoxyamines composed of methacrylic acid with a low percentage of sodium 4-styrene sulfonate were synthesized in aqueous solution. These macroalkoxyamines were used as macroinitiators in the surfactant-free emulsion polymerization ofmethyl methacrylate or n-butyl methacrylate with a low percentage of styrene. The polymerization induced self-assembly of the so-formed amphiphilic block copolymers leads to nanoobjects with various morphologies (spheres, fibers, vesicles), depending on their hydrophilic/hydrophobic balance. The most interesting morphology is the nanofiber type of organization as the suspensions presentshear-thinning properties at low concentration and viscoelastic behavior at high concentration. The synthesis of these latexes was investigated and developed in one-pot conditions in order to allow further production at the industrial scale.
18

Étude de catalyseurs hydrosolubles pour la génération d’hydrogène vert par méthodes photocatalytiques

Picard, Vincent 08 1900 (has links)
La synthèse de l'hydrogène est une alternative viable à l'utilisation du pétrole. Les méthodes telles que l’électrocatalyse font appel à une source d’énergie primaire, ce qui favorise les déchets générés par ces méthodes, de même que le gaspillage d’énergie. Bien qu’ayant de très faibles rendements, les systèmes photocatalytiques permettent la synthèse d’un hydrogène propre et quasi sans déchets. Une perspective permettant d’améliorer encore leur potentiel serait d’éliminer les solvants organiques tels que le DMF, qui sont nocif pour l’environnement et la santé des êtres vivants. Étant donné que le solvant doit être changé, il faut prendre garde à modifier le donneur d’électron sacrificiel et le photosensibilisateur en conséquence. La production de tels solvants est également source de pollution, ce qui atténue le potentiel environnemental de ces méthodes. L’objectif de ce travail est de développer et de tester de nouveaux catalyseurs hydro-solubles variés permettant une amélioration des performances photo-catalytiques actuelles ainsi qu’une performance acceptable dans l’eau. L’étude des propriétés catalytiques est réalisée par l’étude de systèmes homogènes conjugués principalement avec le [Ru(bpy)3]2+ en tant que photosensibilisateur et avec le triethanolamine (dans le DMF) et l’acide ascorbique (dans l’eau) en tant que donneur d’électron sacrificiel. Les catalyseurs présentés lors de ce travail sont des catalyseurs à base de polypyridyl, de cobaloximes et de N-imidoylamidine. Les catalyseurs à base de poly-pyridyl ont d’abord été étudiés puisqu’ils sont réputés pour leur performance en milieux aqueux. La seconde approche consistait à produire des catalyseurs à base de cobaloxime qui aient une performance relativement constante tout d’abord dans les solvants organiques, puis d’adapter ces performances en milieu aqueux. La troisième approche a été de tester des catalyseurs à base de N-imidoylamidine, ce type de catalyseurs n’ayant jamais été testé pour la production d’hydrogène, puis d’en étudier les performances dans l’objectif de paver la voie pour de futures recherches sur le sujet. / The synthesis of hydrogen is a viable alternative to the use of petroleum. Methods such as electrocatalysis use a primary energy source, which reduces the waste generated by these methods, as well as the waste of energy. Although having very low yields, photocatalytic systems allow the synthesis of clean hydrogen with virtually no waste. One prospect to further improve their potential would be to eliminate organic solvents such as DMF, which are harmful to the environment and the health of living beings. Giving the fact that we change the solvent, we need to change the electron sacrificial donor and the photosensitizer as well. The production of such solvents is also a source of pollution, which reduces the environmental potential of these methods. The objective of this work is to develop and test various new water-soluble catalysts allowing an improvement of the current photo-catalytic performances as well as an acceptable performance in water. The study of the catalytic properties is carried out by the study of homogeneous conjugated systems mainly with [Ru(bpy)3]2+ as photosensitizer and with triethanolamine (in DMF) and ascorbic acid (in water) as a sacrificial electron donor. The catalysts presented during this work are catalysts based on polypyridyl, cobaloximes, and N-imidoylamidine. Poly-pyridyl-based catalysts were first studied because they are known for their performance in aqueous media. The second approach was to produce cobaloxime-based catalysts that had relatively constant performance first in organic solvents and then to match this performance in aqueous media. The third approach was to test catalysts based on N-imidoylamidine, as this type of catalyst have never been tested to produce hydrogen, then to study their performance to pave the way for future research on the subject.
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Ligands dérivés de saccharides et, ou supportés par un bras poly(éthylène) glycol : synthèse et applications en catalyse organométallique / Ligands derived from saccharides and, or supported on poly(ethylene) glycol arm : synthesis and applications in organometallic catalysis

Adidou, Ouissam 16 October 2009 (has links)
La synthèse de deux familles de ligands a été envisagée. La première famille de ligands concerne la préparation de nouveaux ligands dérivés de la D-glucosamine ou du D-glucose qui seront engagés dans la réaction de substitution allylique de type Tsuji-Trost en phase homogène. La deuxième famillede ligands concerne la préparation de ligand supportés par un bras poly(éthylène) glycol et dérivés dela D-glucosamine ou de la di-(2-pyridyl)méthylamine. Ces ligands hydrosolubles ont été engagés dans deux réactions pallado-catalysées en phase aqueuse à savoir la substitution allylique de type Tsuji-Trost et la réaction de couplage croisé de type Suzuki-Miyaura, respectivement. / Ligands derived from saccharides and, or supported on poly(ethylene) glycol arm: synthesis and applications in organometallic catalysis. The synthesis of two types of ligands has been investigated. The first family of ligands has been the preparation of new ligands derived from D-glucosamine or D-glucose, which have been tested in the allylic substitution of Tsuji-Trost in homogeneous phase. The second one has een the preparation of ligand supported on poly(ethylene) glycol arm and derived from D-glucosamine or di-(2- pyridyl)methylamine. These last hydrosoluble ligands have been tested in two Pd-catalyzed reactions in aqueous phase: the allylic substitution of Tsuji-Trost and the cross-coupling Suzuki-Miyaura reaction, respectively.

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