MINIEMULSION POLYMERIZATION - A COMPARATIVE-STUDY OF PREPARATIVE VARIABLES

Variations in the conditions used to prepare miniemulsions of monomers in water have resulted in substantial differences in polymerization kinetics and final particle sizes and distributions. These variations have included (1) surfactant amount and type; (2) cosurfactant amount and type; (3) monomer(s) type; (4) temperature of preparation and polymerization; (5) means and conditions of homogenization; and (6) degree of aging of the emulsion. In an effort to unify some of the disparate information of previous work, a systematic study of some of the above variables was undertaken using styrene as the oil phase with sodium lauryl sulfate as surfactant. Based on the polymerization kinetics and particle sizes obtained, the following conclusions are drawn: The finest droplet size miniemulsions are obtained by (1) using a cosurfactant; (2) homogenizing at elevated temperature; (3) homogenizing using a uniform high shear device (Microfluidizer); and (4) limiting the aging time prior to polymerization.