Preparation of Ultra Fine Poly(methyl methacrylate) Microspheres in Methanol-enriched Aqueous Medium

Monodisperse PMMA microspheres are prepared by means of a simple soap-free emulsion polymerization in methanol-enriched aqueous medium in a single step process. The size and uniformity of the microspheres are dependent on the polymerization temperature. In a stable system, the uniformity is improved with the polymerization time. The most uniform and stable microspheres are obtained under mild agitation speed of 100 rpm at 70 C. The monodisperse PMMA microspheres in the size range of 1.4-2.0 μm having less than 5% size variation are successfully achieved with varying concentrations of monomer and initiator. As the monomer and initiator concentrations increase, the larger microspheres with enhanced uniformity are obtained. However, the decreased amount of water induces the polydisperse PMMA particles due to the generation of secondary particles.