Développement de nouvelles formulations à base de polymères fonctionnels pour la mise au point de papiers techniques à propriétés spécifiques

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 viscosityCette 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 (