Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Inorganic nanomaterials are a class of advanced materials, which have been widespread in both science and nanotechnology. The use of nanomaterials in several areas makes nanoscience an interdisciplinary field. Some challenges, such as the type of synthesis and toxicity control should be explored, mainly because those materials can be controlled at the nanometer level by means of the synthesis variables. In this work, we performed the synthesis of cadmium telluride (CdTe) nanoparticles with the surface capped by a mixture of organic thiol stabilizers such as mercaptopropionic acid (MPA), cysteine (CYS), glutathione (GLU), and biopolymer sodium alginate (ALG). Synthesis were performed by two distinct aqueous methods hydrothermal and reflux and the synthesis parameters such as pH and ratio Cd/Te/stabilizer were fixed based on the literature. The colloidal dispersions obtain present remain stable for at least 3 months (time observed so far). Optical absorption spectra of all mixtures of CdTe - stabilizers presented a red shift with increasing synthesis time, and furthermore, the position of this band was at a wavelength below the bulk CdTe (790 nm). The emission spectra in all cases were intense, with little difference between them. The diameter of the particles, calculated from an empirical equation from the of maximum absorption wavelength, were comparable compared to those obtained by X-ray diffraction (XRD) (Scherrer equation) as well as transmission electron microscopy (TEM). The results from the three techniques agreed very well for CdTe via reflux. However for hydrothermal synthesis it was not possible to determine the diameter of the particles by TEM due to morphology of nanostructured aggregates. The crystal structures as obtained by XRD indicating the incorporation of sulfur atoms in the CdTe structure, in agreement to the literature for this type of synthesis. Infrared spectroscopy confirmed the presence of organic stabilizers on the surface of CdTe. The morfology of samples identified by TEM/HRTEM was different depending on the method of syntesis aggregates for the hydrothermal samples and isolated particles for reflux samples so the mechanisms of nucleation and growth were proposed oriented attachment (OA) and Ostwald ripening (OR) for synthesis CdTe-hydrothermal and reflux, respectively. / Os nanomateriais inorgânicos são uma classe de materiais avançados, que vêm sendo difundidos tanto em ciência como em nanotecnologia. O uso destes materiais está localizado em diversas áreas de atuação, fazendo com que tal classe seja interdisciplinar. Alguns desafios como o tipo de síntese e a toxidade devem ser explorados, principalmente porque estes materiais podem ser controlados a nível nanométrico por meio das variáveis de síntese. Neste trabalho, foi realizada a síntese de nanopartículas de Telureto de Cádmio (CdTe) com a superfície coberta pela mistura de estabilizantes orgânicos tióis tais como, ácido mercaptopropiônico (MPA), cisteína (CYS) e glutationa (GLU) e o biopolímero alginato de sódio (ALG). Esta síntese foi realizada por dois métodos aquosos, via hidrotermal e refluxo, e os parâmetros de síntese como pH e relação Cd/Te/estabilizante foram fixos com base na literatura. As dispersões coloidais obtidas apresentaram-se com estabilidade coloidal por pelo menos 3 meses (tempo observado até o momento). Os espectros eletrônicos de absorção óptica de todas as misturas de CdTe-estabilizantes se apresentaram largos, com deslocamento para o vermelho com o aumento do tempo de síntese, e além disso, a posição desta banda estava em comprimento de onda abaixo do CdTe bulk (790 nm), indicando confinamento quântico. Os espectros de emissão em todos os casos foram intensos e com pouca diferença entre os mesmos. Os diâmetros das partículas foram calculados usando-se uma fórmula empírica, a partir do comprimento de onda máximo de absorção e comparado aos resultados obtidos por difratometria de raios X (XRD) (equação de Scherrer) e por microscopia eletrônica de transmissão (TEM). Os resultados das três técnicas corroboram entre si para as amostras de CdTe via refluxo. Contudo, no caso do hidrotermal, não foi possível determinar os diâmetros por TEM porque a morfologia foi de agregados nanoestruturados. As estruturas cristalinas forma obtidas por XRD, indicando a incorporação de átomos de enxofre na estrutura do CdTe, estando de acordo com a literatura para o tipo de síntese. A espectroscopia de infravermelho confirmou a presença dos estabilizantes orgânicos na superfície do CdTe. A morfologia identificada por TEM/HRTEM das amostras sintetizadas pelas duas sínteses foi diferente agregados para a síntese hidrotermal e partículas isoladas para refluxo sendo que os mecanismos proposto para nucleação e crescimento foram o oriented attachment (OA) e o Ostwald ripening (OR) para CdTe-hidrotermal e o CdTe-refluxo, respectivamente.

Made available in DSpace on 2014-10-09T12:42:31Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:02:09Z (GMT). No. of bitstreams: 0 / A ampla utilização de medicamentos, a falta de gerenciamento na produção e no descarte desses produtos, bem como a dificuldade na remoção de resíduos de fármacos das águas residuais durante as fases do tratamento de efluentes tem causado a liberação destes micropoluentes nos recursos hídricos. O cloridrato de fluoxetina, conhecido comercialmente como Prozac®, tem sido muito utilizado em diversos países. Estudos demonstram sua presença no meio ambiente e o potencial de danos que este fármaco pode causar à biota. Desta forma, este trabalho estudou uma tecnologia de tratamento (POA - Processo Oxidativo Avançado) utilizando-se radiação ionizante, proveniente de um acelerador de elétrons, para a degradação do fármaco cloridrato de fluoxetina em solução aquosa e na mistura com esgoto doméstico. Após a irradiação foram feitas análises químicas na solução aquosa do fármaco com Espectrofotometria UV/VIS, Cromatografia Líquida Ultra Rápida (detectores UV/VIS e fluorescência) e quantificação do Carbono Orgânico Total (COT). Também foram empregados ensaios de toxicidade aguda (Daphnia similis e Vibrio fischeri) e crônica (Ceriodaphnia dubia). A eficiência na degradação do fármaco foi superior a 98,00% na menor dose de radiação (0,5 kGy), porém houve baixa taxa de mineralização para as doses aplicadas neste estudo. Para a Daphnia similis na dose de 0,5 kGy houve eficiência de 83,75% na redução da toxicidade do cloridrato de fluoxetina e 87,24% para 5,0 kGy, houve eficiência de 100,00% na redução da toxicidade para o esgoto doméstico e para a mistura (CF + esgoto) 79,32% na dose de 5,0 kGy. A eficiência para a Vibrio fischeri foi de 17,26% (melhor eficiência na dose de 5,0 kGy) e após a correção do pH das amostras a melhor eficiência foi para 20,0 kGy (26,78%), para o esgoto e para a mistura as eficiências ficaram em torno dos 20,00% para todas as doses de radiação aplicadas. Em relação a toxicidade crônica para Ceriodaphnia dubia a eficiência foi de 97,50% para 5,0 kGy. Verificou-se que a Ceriodaphnia dubia possui maior sensibilidade ao fármaco, seguido da bactéria Vibrio fischeri e por fim a Daphnia similis. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:27:47Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:04:53Z (GMT). No. of bitstreams: 0 / Cinza leve de carvão, resíduo gerado em usina termelétrica, foi usada para sintetizar zeólita por meio de tratamento hidrotérmico com solução de NaOH. A cinza leve (CL-2) e a zeólita sintética (ZM-2) que foi predominantemente identificada como hidroxi-sodalita foram utilizadas como adsorventes dos corantes aniônicos índigo carmina (IC) e reativo laranja 16 (RL16) de soluções aquosas. Nos processos de adsorção, os efeitos de tempo de contato, concentração inicial de corantes, pH, massa de adsorventes e temperatura foram avaliados. O estudo cinético de adsorção demonstrou que os resultados apresentaram melhor ajuste ao modelo de pseudo-segunda ordem e que adsorção de superfície e difusão intrapartícula participaram no mecanismo de adsorção. Os parâmetros termodinâmicos demonstraram que a adsorção foi espontânea em todos os processos de adsorção. Os processos de adsorção foram de natureza endotérmica para todos os sistemas, com exceção do sistema IC/ZM-2, em que foi exotérmico. Os dados de entropia mostraram a ocorrência do aumento da desordem na interface sólido/solução durante a adsorção em todos os sistemas, exceto novamente no IC/ZM-2, no qual se verificou a diminuição da desordem na interface. As isotermas de adsorção ajustaram-se à equação linear de Langmuir. As capacidades máximas de adsorção foram 1,48 mg/g para o sistema IC/CL-2; 1,13 mg/g para IC/ZM-2; 0,96 mg/g para RL16/CL-2 e 1,14 mg/g para RL16/ZM-2 à temperatura ambiente. O estudo de dessorção realizado com água, com soluções aquosas ácidas e com solução aquosa básica demonstrou ser ineficiente tanto para a recuperação dos corantes quanto para a regeneração dos adsorventes. / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Neste trabalho estudou-se a modelagem termodinâmica do equilíbrio de fases de sistemas aquosos bifásicos formados por um polímero neutro, especificamente o poli(etileno glicol), e um sal. O modelo implementado é baseado na equação de Pitzer para soluções de eletrólitos, dele diferindo ao considerar a influência das propriedades do polímero no cálculo da constante dielétrica e da densidade do meio, presentes no cálculo do termo relativo às interações de longo alcance da energia de Gibbs excedente. Além disso, procurou-se também considerar a dependência dos parâmetros relativos ao polímero com respeito ao tamanho de sua cadeia. Dados experimentais obtidos da literatura foram utilizados para a obtenção dos parâmetros ajustáveis do modelo, em cuja implementação foi utilizada a linguagem FORTRAN. A alteração nas propriedades do meio modificou o estado de equilíbrio calculado, fato que pôde ser observado por meio da análise de fatores como o desvio entre a composição calculada pelos modelos e os valores experimentais em cada fase e a inclinação da linha de amarração. Em alguns sistemas o desempenho do modelo modificado foi superior nesses parâmetros, mas em termos gerais a modificação no cálculo da constante dielétrica e da densidade não resultou em melhora no cálculo do equilíbrio de fases, por vezes piorando-o, de modo que investigações específicas sobre o termo de longo alcance foram conduzidas para verificar a razão deste comportamento. A inclusão de parâmetros ternários aumentou a capacidade de correlação de ambos os modelos. No que diz respeito à possibilidade de correlação dos parâmetros de interação como função do tamanho da cadeia polimérica, que poderia levar a um modelo preditivo, observou-se que somente para tamanhos grandes de cadeia foi possível estabelecer uma dependência direta e inequívoca. / The thermodynamic modeling of phase equilibrium in aqueous two phase systems containing the neutral polymer poly(ethylene glycol) and a salt was studied in this work. The implemented model is based on the Pitzer equation for electrolytes solutions, modified in order to account for the influence of polymer properties in both the medium dielectric constant and the medium density, values which are present in long range term of the excess Gibbs energy. The dependence of the adjustable parameters on the polymer molecule size was also investigated. Experimental data from literature were used to obtain the adjustable parameters of the model, in whose implementation the FORTRAN computer language was used. The changes introduced into the long range term resulted in a shift of the calculated equilibrium compositions, which could be observed by analyzing the deviation between calculated and experimental compositions and tie-line slopes. For some systems the performance of the modified model was superior, but in most cases the changes introduced did not result in a significant improvement in phase equilibrium calculations, and even worsened them. Specific investigations on the long range term were carried out to verify the reason for such behavior. The insertion of ternary parameters increased the correlation capacity of both models. Concerning the hypothesis that the interaction parameters can be directly related to the polymer chain size, which might eventually lead to a predictive model, it was noticed that a direct dependency holds only for larger chain sizes.

L’extraction de matières premières du sol à des fins énergétiques (récupération assistée d’huile) et environnementales (dépollution des sols) fait l’objet de recherches intensives en lien avec des thématiques telles que la séquestration du carbone ou la fracturation hydraulique. L’objectif est de trouver des méthodes moins destructives, moins gourmandes en matériel et en énergie, mais aussi plus efficaces et moins coûteuses. Nous proposons d’étudier une méthode alternative aux moyens conventionnels avec l’utilisation de mousses aqueuses comme agent extracteur d’huile. Les mousses aqueuses sont souvent utilisées en présence d'huile : dans des applications quotidiennes comme la cosmétique et la détergence, mais aussi dans des domaines moins connus comme la décontamination des centrales nucléaires ou l’industrie pétrolière. Ainsi, des tensioactifs et du gaz sont couramment injectés dans le sol afin d'améliorer les procédés de récupération de pétrole. Nous explicitons deux mécanismes d'extraction que nous quantifions en termes d'efficacité et de stabilité. Tout d'abord, la mousse peut aspirer de l'huile en son sein, comme le ferait une éponge. Ensuite, lorsque celle-ci est mise en écoulement, elle peut entraîner de l'huile confinée dans la rugosité d'une surface par cisaillement. Notre étude s’appuie en particulier sur une analyse théorique et expérimentale, à la fois multi-échelle, statique et dynamique pour laquelle nous avons systématiquement fait varier les paramètres géométriques (configuration de l'huile, taille des bulles et fraction volumique de liquide dans la mousse) et physico-chimiques (tensions interfaciales, rigidité des interfaces entre bulles et viscosité) / The extraction of raw materials from the soil for energetical (enhanced oil recovery) and environmental purposes (soil remediation) is the subject of intense fundamental and applied research. This field is related to other important topics, such as carbon sequestration and hydraulic fracturing. The goal is to find fewer destructive, as well as energy and material-saving methods. These techniques should also be cost-effective and more efficient. To find a substitution to conventional means, we study an alternative method that puts aqueous foams on the map as the extraction material. Aqueous foams are often used in numerous daily applications, such as cosmetics and detergency, but also in less known fields, such as the decommissioning of nuclear power plants and the oil industry. Thus, surfactants and gas are commonly injected into the soil to improve the recovery processes of oil. We explain two extraction mechanisms that we quantify in terms of efficiency and stability. On one hand, the foam is able to absorb oil, similarly to a solid sponge. On the other hand, when a flow of foam is induced, the foam can entrain oil confined in the roughness of a surface by shearing the oil-water interface. Our work especially lies on a theoretical and experimental analysis, which is multiscale, static and dynamic. We systematically vary the geometrical parameters (oil configuration, bubble size and liquid fraction in the foam) and the physical and chemical parameters (interfacial tensions, interfacial rigidity and viscosity)

Basé sur les concepts de développement durable et de chimie verte, l’une des alternatives envisagées par les chimistes, pour une chimie plus propre, est de substituer les solvants organiques, pouvant être dangereux et toxiques, par des solvants plus verts. L’eau est un bon candidat pour cette substitution car c’est le solvant le moins cher dans nos contrées, et le plus sûr : il est non-toxique, ininflammable et non explosif. Afin de palier la faible solubilité de la majeure partie des composés organiques dans l’eau, les tensioactifs peuven têtre utilisés afin d’améliorer les rendements réactionnels. Les milieux ainsi obtenus sont difficilement recyclables car ils nécessitent une forte dilution afin de casser les agrégats et de récupérer les produits. C’est pourquoi, l’utilisation de tensioactifs photo-régulables est une bonne alternative car il est possible d’organiser/désorganiser les agrégats par irradiation lumineuse et ainsi récupérer les composés organiques en fin de réaction tout en recyclant le milieu réactionnel. Pour cela, nous avons synthétisé trois tensioactifs possédant une fonction azobenzène(anionique, cationique, non ionique), afin de les tester en catalyse micellaire. Certains de ces tensioactifs, après en avoir déterminé leurs propriétés physico-chimiques (cmc et spectre UV-Visible) ont été testés dans une réaction pallado-catalysée : la substitution allylique de Tsuji-Trost. Nous avons réussi à démontrer l’intérêt d’utiliser un tensioactif photo-régulable par rapport aux tensioactifs commerciaux en terme de rendement et de recyclabilité. D’autre part, la décarboxylation de Barton, décrite pour la première fois en 1983, permet la formation d’alcanes à partir d’acides carboxyliques en utilisant un dérivé d’étain comme donneur d’hydrogène. Depuis lors, cette réaction a toujours été utilisée comme étape clé en synthèse totale de composés naturels et en solvants organiques. De plus, cette réaction est historiquement réalisée par activation conventionnelle, thermique ou par irradiation ultra-violette. C’est pourquoi, nous avons décidé d’étudier cette décarboxylation radicalaire dans l’eau, en présence de tensioactifs et en utilisant des modes d’activation non conventionnels : les micro-ondes et les ultrasons. De plus, en lieu et place d’étain, nous avons préféré l’utilisation de N-phénylmaléimide, déjà connu et étudié comme piège à radicaux, afin d’obtenir des maléimides substitués par des chaînes carbonées. Les rendements obtenus en milieux micellaires se sont avérés être aussi bons, voire meilleurs qu’en solvants organiques. / Based on concepts of sustainable development and green chemistry, one of the alternatives envisioned by chemists is to substitute organic solvents, which can be dangerous and toxic, for greener solvents. Water is the best candidate for this substitution because it is thesafest and cheapest solvent in our countries : this solvent is non-toxic, non-flammable and inexplosive. In order to overcome the low solubility of most of organic compounds in water, surfactants can be used to improve the reaction yields. Media thus obtained are difficult to recycle because they require high dilution in order to break aggregates and recover products. Therefore, using photo-switchable surfactants is a good alternative because they can organize/disorganize by light irradiation. Organic compounds could be recovered after reactions and the recyclability of the medium can be improved. For this purpose, we synthesized three surfactants having an azobenzene moiety (anionic,cationic, nonionic), to test them in micellar catalysis. Some of these surfactants, after determining their physicochemical properties (CMCs and UV-visible spectra) were studied in a pallado-catalyzed reaction, the allylic substitution of Tsuji-Trost. We have successfully demonstrated the value of using a photo-switchable surfactant compared to commercialones in terms of yields and recyclability. In other hand, Barton decarboxylation, described for the first time in 1983, permits the formation of alkanes from carboxylic acids, using tin derivatives as hydrogen donors. Since then, this reaction has always been used as a key step in total synthesis of natural compounds in organic solvents. In addition, historically, this reaction was carried out by conventional activation (heat or ultraviolet light). Therefore, we decided to study this radical decarboxylation in water, in the presence of surfactants and using unconventional activation modes : microwave and ultrasound. Moreover, instead of tin, we preferred the use of N-phenylmaleimide, already known and studied as a radical trap, to obtain maleimides substituted by carbon chains. Yields obtained in micellar media were found tobe at least as good as in organic solvents.

O ambiente Antártico é caracterizado por condições ambientais restritivas de clima, hábitat e biogeografia. Neste sentido, o objetivo deste estudo foi avaliar a diversidade de leveduras em amostras marinhas e terrestres do ambiente Antártico, além da prospecção de lipases que atuem em processos que requerem baixas e moderadas temperaturas. De acordo com os resultados obtidos, 97 leveduras foram recuperadas por semeadura em meio de cultura PDA e YMA a partir de diferentes amostras coletadas na OPERANTAR XXVIII (verão 2010), das quais foram identificados 12 gêneros e 21 espécies. Destas, 45 apresentaram atividade de lipase e duas foram selecionadas para o ensaio de otimização da produção enzimática: C. laurentii L59 e L. scotti L117. A extração de lipase de L. scottii L117 foi avaliada por Sistema de Duas fases Aquosas e o sistema micelar utilizando TX-114 foi o mais eficiente para purificação parcial desta enzima. Por fim, a avaliação da diversidade das 405 leveduras isoladas de macroalgas e liquens (coletadas na OPERANTAR XXXII no verão de 2013) revelou a ocorrência de 24 taxons de leveduras a partir das amostras de macroalgas e 18 taxons a partir das amostras de liquens, sendo apenas cinco espécies comuns a estes dois substratos. / The Antarctic continent is characterized by restrictive environmental conditions of climate, habitats and biogeography. In this sense, the objective of this study was to evaluate the diversity of yeasts in marine and terrestrial samples of the Antarctic environments, as well as the propspecting of lipases that can act in proceses that require low and moderate temperatures. According to the results, 97 yeasts were recovered from different samples collected in OPERANTAR XXVIII (summer 2010), representing 21 different species. Among them, 45 showed lipase activity and two were selected for the optimization of enzyme production: C. laurentii L59 and L. scotti L117. Extraction of L. scottii L117 lipase was assessed by Aqueous Two-Phase System and the micellar system TX-114 was the most efficient for partial enzyme purification. Finally, the diversity evaluation of 405 isolates from seaweeds and lichens (collected in XXXII OPERANTAR, summer of 2013) revealed the occurrence of 24 taxa from macroalgae samples and 18 taxa from lichens samples, being only five substrates common to these two substrata.

No description available.

Infectious diseases are the world’s leading cause of premature deaths in humans and animals. The resistance to antibiotics and the emergence of new infectious diseases has increased the need for additional effective antimicrobial products. Despite numerous publications investigating antimicrobial activity of plant extracts it appears that no effective single product antimicrobial has yet been developed from plants. In many cases, however crude plant extracts have excellent activity and may provide useful products. Plants are frequently selected based on traditional use. Traditional healers usually use aqueous extracts of plants which in our experience generally have very low activities and it may be one of the reasons why no new products were developed from plants. Another approach to select plants for research is to use the taxonomic approach based on the premises that: (1) there is a correlation between active chemical compounds and antimicrobial activity; and (2) species in a family or order may have similar activities if the chemical precursors are inherited from a common ancestor. Future screening programmes could then concentrate on close relatives of species within these promising families and orders. The main aim of this study was to randomly screen leaf extracts of several hundred southern African tree species against important microbial pathogens to determine which taxa have the highest activity and may yield useful products to treat infections in human and animal health markets. A wide selection of plant species improved the possibility of finding promising extracts and has the advantage that active compounds may be discovered from plants that are not used traditionally. To ensure sustainable use only leaves of trees were examined. A spin off of this study would also indicate the susceptibility of different organisms, correlate the antimicrobial activities of the different organisms and determine what minimum inhibitory concentration (MIC) represents a good activity based on investigating many extracts against many microbes. The antimicrobial activity was determined by using a sensitive serial dilution microplate method. Acetone extracts were tested against two Gram-positive bacteria, two Gram-negative bacteria and two fungi, i.e. Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, Candida albicans and Cryptococcus neoformans. Small and mostly insignificant differences were found between the susceptibility of the microbial pathogens to the extracts. E. faecalis was the most sensitive bacterium and C. neoformans the most sensitive fungal organism. The strongest correlations in activities among the pathogens were between C. albicans and C. neoformans, and among the pathogen classes between Gram-positive and Gram-negative bacteria. The tree extracts analysed in the present study had a wide range of activities against the different pathogens. Twenty six per cent of the extracts inhibited the pathogens at MIC levels of 0.16 mg/ml. This clearly shows that 0.16 mg/ml is not low enough to discriminate between promising species. Some of the extracts inhibited the growth of more than one pathogen while other extracts had selective activities and could be the most promising to follow up. The study identified families and orders with either statistically significantly higher or lower antimicrobial activities. Among the large families, Combretaceae and Fabaceae had high mean activities against all test pathogens. The families Anacardiaceae and Moraceae had high activities against both Gram-positive and Gram-negative bacteria whereas the families Proteaceae and Meliaceae had higher antifungal activities. Among the large orders, Fabales had relatively high activities against all the pathogen classes. Considering that plants in related taxa often contain similar compounds and therefore similar activities, future studies could analyse more representative species in the promising taxa. Many tree species, genera, families and orders, including well-known and lesser known medicinal taxa in southern Africa, were identified with promising activities. To evaluate the potential use of these results, additional cytotoxicity, phytochemical and pharmacological studies should be carried out. The study, although still exploratory, underlined the potential of southern African tree extracts as sources of antimicrobial products. Application of these results within the Phytomedicine Programme has led to patents and products that were as good as commercial products in animal and field trials. We hope that our results will provided a starting point for discovering new products with useful activities. / Thesis (PhD)--University of Pretoria, 2014. / gm2014 / Paraclinical Sciences / Unrestricted

Cette thèse a consisté à étudier la réaction d'acétalisation en milieu aqueux de l'alcool polyvinylique (PVA) par un aldéhyde non hydrosoluble à longue chaîne alkyle (10-14 carbones) porteur d'une fonctionnalité vinyle en bout de chaîne, pour des conditions spécifiques : concentration en polymère de 8 % massique et degrés d'acétalisation (DA) faibles (<5,6 mol%). L'objectif de cette réaction de greffage est l'obtention de films obtenus par évaporation de solvant ayant une fonctionnalité de surface. L'influence des paramètres de réaction (concentration en réactifs, pH) sur la cinétique a été étudiée sur un composé modèle, le pentane-2,4-diol, puis sur le PVA. Une méthode de dosage par RMN 1H a permis d'identifier et de quantifier les composés en présence dans le milieu de réaction.Un objectif de la thèse a été de maximiser le DA en conservant une viscosité adéquate pour un procédé d'enduction. Pour cela, l'impact du greffage par le 10-undécénal sur l'organisation et les propriétés rhéologiques des solutions d'un PVA référence à 8 % massique a été étudié en premier lieu jusqu'à un DA de 1,85 mol%. Une méthode de quantification de faibles quantités de groupements vinyle en surface des films de PVA acétalisé a permis d'étudier leur orientation en surface pour une gamme de DA de 0 à 1,48 mol%.L'influence de la masse molaire du PVA et de la longueur de chaîne alkyle de l'aldéhyde sur la cinétique d'acétalisation et son impact sur la viscosité des solutions ont également été étudiés. L'utilisation d'un PVA de masse molaire plus faible apparait être un moyen efficace de maximiser le DA tout en conservant une viscosité acceptable pour un procédé d'enduction / This PhD work dealt with the study of the acetalization reaction of polyvinyl alcohol (PVA) in aqueous medium by non-water soluble aldehydes bearing long alkyl chains and a vinyl end group such as 10-undecenal in specific conditions: in 8 wt% concentrated PVA solutions and with low acetalization degree (AD) from 0.33 mol% to 5.6 mol%. The main purpose of this grafting reaction is to obtain an activated surface on water casted polymer films. First, the impact of reactants concentrations, pH and reaction atmosphere on the acetalization kinetics was studied with a model compound first, pentane-2,4-diol, then with PVA. A new 1H NMR titration method allowed to carry out in situ quantification of the amount of reactant and of grafted aldehyde.On main objectives of this work was to obtain the highest DA while keeping PVA solutions viscosity as low as possible to keep a sufficiently low solution viscosity for a solvent cast process. The impact of AD by 10-undecenal on PVA solution organization and on the rheological properties of 8 wt% PVA aqueous solutions were investigated first until 1.85 mol% AD. A surface vinyl groups quantification method was developed through chemical labeling of the vinyl groups at the surface of solvent casted PVA films and 1H NMR titration of the labels. This method allowed the study of vinyl groups orientation toward the surface of acetalized PVA films until 1.48 mol% AD.The influence of PVA molar mass and of aldehyde alkyl chain length on acetalization kinetics and solutions viscosity was also studied. The use of a low molar mass polymer appeared to be an efficient way to obtain highly modified films while keeping a low 8 wt% acetalized PVA solution viscosity