One-stage synthesis of narrowly dispersed polymeric core-shell microspheres

Abstract

A method of one-stage soap-free emulsion polymerization to synthesize narrowly dispersed core-shell microspheres is proposed. Following this method, core-shell microspheres of poly(styrene-co-4-vinylpyridine), poly(styrene-co-methyl acrylic acid), and poly[styrene-co-2-(acetoacetoxy)ethyl methacrylate-co-methyl acrylic acid] are synthesized by one-stage soap-free emulsion polymerization of a mixture of one or two hydrophobic monomers and a suitable hydrophilic monomer in water. The effect of the molar ratio of the hydrophobic monomer to the hydrophilic one on the size, the core thickness, and the shell thickness of the core-shell microspheres is discussed. The molar ratio of the hydrophobic and hydrophilic monomers and the hydrophilicity of the resultant oligomers of the hydrophilic monomer are optimized to synthesize narrowly dispersed core-shell microspheres. A possible mechanism of one-stage soap-free emulsion polymerization to synthesize core-shell microspheres is suggested and coagglutination of the oligomers of the hydrophilic monomers on the hydrophobic core is considered to be the key to form core-shell microspheres. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1192–1202, 2008