Preparation of monodisperse PMMA microspheres in nonpolar solvents by dispersion polymerization with a macromonomeric stabilizer

Abstract

We discuss a dispersion polymerization procedure for pre- paring monodisperse and micron- sized poly(methyl methacrylate) (PMMA) particles in hexanes with methacryloxypropyl-terminated polydimethylsiloxane stabilizers. We investigate the effects of the stabi- lizer molecular weight, stabilizer concentration, and monomer con- centration on the particle size and polydispersity. We find that a mini- mum molecular weight of 10 000 g/mol is necessary to synthesize col- loidally stable PMMA dispersions. The particle polydispersity is mini- mal ( £ 5%) for stabilizer to mono- mer weight ratios of 0.02 to 0.1, while PMMA particles prepared under conditions outside this range are polydisperse. The particle diameter can be varied from 0.4 to 1.5 lm by appropriate choices of stabilizer and monomer concentra- tions. Stable PMMA suspensions can be prepared at up to 26.3% solids. The dispersions are stable in most liquid aliphatics, and are monodisperse enough to form or- dered domains at high concentra- tion. This single-stage synthesis, requiring only commercially avail- able materials, may be of interest to those seeking a simple way to pre- pare highly monodisperse non- aqueous dispersions in the micron size range.