Dispersion polymerization of styrene in supercritical CO 2 stabilized by random copolymers of 1 H,1 H-perfluorooctyl methacrylate and 2-dimethylaminoethyl methacrylate

Abstract

The dispersion polymerizations of styrene in supercritical CO 2 employing random copolymers composed of 1,1-dihydroperfluorooctyl methacrylate (FOMA) and 2-dimethylaminoethyl methacrylate (DMAEMA) (poly(FOMA- co-DMAEMA)) as stabilizers were investigated with two different compositions. It was demonstrated that micron-sized, free-flowing, spherical polystyrene (PS) particles could be obtained in high yields by poly(FOMA- co-DMAEMA) containing as low as 50% (w/w) FOMA. Results indicate that DMAEMA units in the stabilizer, as an anchor group with its special characteristics, can be adsorbed on PS particles to provide an enough colloidal stability. The initial concentration of styrene and the stabilizer affected the molecular mass, polymerization yield, and the morphology of PS particles. The PS particles could be redispersed in buffered water (pH 2.1) by an ionic stabilization mechanism provided by DMAEMA units on the surface. Dynamic light scattering (DLS) measurements of aqueous latexes gave similar particle sizes as those from SEM analysis.