Microemulsions: A Medium for Polymerization Reactions

Abstract

Abstract Aqueous and nonaqueous microemulsions containing either of the monomers styrene or hexyl methacrylate polymerize when initiated with potassium persulfate. Reactions in both types of microemulsions lead to stable, bluish dispersions of latex particles with diameters ranging from 40 to 90 nm. By substituting formamide for water, one can investigate the effect of the monomer solubility in the continuous domain on the microemulsion polymerization mechanism in a way independent of the monomer type. When the monomer solubility in the polar domain is high, the latex particles are larger and have a larger number of polymer chains than when the monomer solubility is low. If the monomer solubility in the continuous domain is greater than the overall monomer concentration in the microemulsion, the reaction mechanism shifts from that of a microemulsion polymerization to one of a solution polymerization in the presence of empty micelles.