From polymeric surfactants to colloidal systems: 4. Neutral and anionic amphiphilic polysaccharides for miniemulsion stabilization and polymerization

Neutral and anionic amphiphilic polysaccharides have been prepared by chemical modification of a bacterial polysaccharide, dextran. ability of oil-in-water emulsions prepared in the presence of polymeric surfactants is described and related to the number of charged groups within polysaccharide backbone. Ostwald ripening is the main process of irreversible increase of the average droplet size. Macroscopic creaming observations are shown to be consistent with data about droplet size increase. The effect of ionic strength on emulsion aging is also investigated. scosity of oil-in-water emulsions is examined for oil volume fractions below 13% varying the structure of polymeric surfactants. Ionic groups within the polymer backbone induce an increase of the viscosity of the suspensions. ccharide-covered poly(styrene) nanoparticles are prepared by miniemulsion polymerization of styrene-in-water emulsions stabilized with dextran derivatives. The size of final nanoparticles is controlled by that of the initial styrene emulsion, provided that emulsion aging is set low enough. lloidal stability of the obtained suspensions is analysed as a function of ionic strength.