Effective Modifications of Monodispersed Colloidal Silica Particles with Polymers.

Abstract

Surface modifications of monodispersed colloidal silica particles with polymers were investigated. In the modification of the particles with hydrophobic and hydrophilic polymer-silane coupling agents, more than 15 times of the amount of the coupling agents for that of silica was at least required to avoid the aggregation of the particles, but addition of a small amount of aqueous ammonia to the reaction system resulted in effective attachment of polymer to silica surface and afforded dispersible polymer/SiO2 composites into organic solvents without aggregation. Radical polymerization of vinyl monomers (styrene, methyl methacrylate and 2-hydroxyethyl methacrylate) using 2, 2'-azobis (2-amidinopropane) dihydrochloride as an initiator on the colloidal silica surface led to the formation of spherical polymer/SiO2 composites, and retained particle size. Surface grafting of polystyrene to poly (N-vinyl-2-pyrrolidone) having vinylphenylene end group by radical polymerization on the particle surface also successfully brought about the formation of monodispersed polymer/SiO2 composites.