Studies of block copolymer stabilizers for dispersion polymerization

Anionic polymerization techniques have been used to prepare AB block copolymers of polystyrene and poly[dimethyl siloxane] having well-defined molecular weight and composition, and narrow molecular weight distribution. Block copolymers prepared over a range of molecular weights and compositions were characterized by gel permeation chromatography, osmometry and silicon analysis. Such block copolymers have been used as stabilizers for non-aqueous dispersion polymerizations of styrene and methyl methacrylate in aliphatic hydrocarbon. The polymer particles thus produced were stabilized by well-defined surface layers of poly[dimethyl siloxane]. The effects of varying the polymerization conditions, and the type and concentration of stabilizer present, were studied. Both radical and anionic polymerization mechanisms have been considered, and methods of preparing polymer particles of a narrow size distribution were developed. [Continues.]