Synthèse et caractérisation de dérivés amphiphiles du xanthane : application à la stabilisation d'émulsions

Abstract : Amphiphilic polysaccharides are composed of a hydrophilic backbone grafted with hydrophobic moieties. They show specific rheological properties due to their capacity to self-associate in solution, but also interfacial properties due to their ability to adsorb at the water/oil interface. However, only few studies describe the chemical modification of complex heteropolysaccharides regarding their structure or their conformation, such as xanthan. Indeed, this polysaccharide can adopt in solution two distinct conformations depending on experimental conditions: an ordered rigid helix or a disordered flexible coil.The objective of this work is to determine the impact of the chain stiffness of hydrophobically modified xanthan on associative properties in solution, but also on stabilizing properties in emulsion.The conformation adopted by the polymer during the grafting procedure has a major impact on the rheological properties: xanthan modified under disordered conformation is an associative polysaccharide, contrary to xanthan modified under its ordered conformation.In addition, hydrophobically modified xanthan is able, under certain conditions, to form and stabilize O/W emulsion, without further addition of molecular surfactant, by partitioning between stabilization of the water/oil interface and viscosifying the continuous aqueous phase.
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Céline Fantou. Synthèse et caractérisation de dérivés amphiphiles du xanthane : application à la stabilisation d'émulsions. Polymères. Normandie Université, 2018. Français. ⟨NNT : 2018NORMLH38⟩. ⟨tel-02157077⟩



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