Rudy Covis

Implication of Amphiphilic Dextran on the Stability of Emulsions: Synthesis of Amphiphilic Polysaccharides Based on Dextran and Applications to the Stabilization of Emulsions Rudy Covis

A new family of amphiphilic dextran derivatives was obtained by reaction of 1,2-epoxydodecane on dextran in basic medium. Two reaction procedures were examined. Oil-in-water emulsions were prepared by sonication in the presence of different hydrosoluble derivatives. The size of the emulsion droplets increased with the oil volume fraction but did not depend on the substitution degree of modified dextran. These emulsions behave like a gel which strengthened with the oil volume fraction. Water-in- oil emulsions (water in chloroform) were obtained by sonication in the presence of organosoluble derivatives. Furthermore, dynamic emulsification process under shear flow was investigated for oil-in- water emulsions (hexadecane in water). Simultaneous in situ measurements of viscosity of emulsions and droplet size were performed. The characteristic time of emulsification depended on shear rate and viscosity ratio but was independent of the oil volume. For the newtonian system, final shear stress and final droplet size depended on the applied shear rate while they were invariant in the non newtonian system.