Preparation and Characterization of Poly(methyl methacrylate) Particles by Combined Dispersion and Emulsion Polymerization

Monodispersed poly(methyl methacrylate) (PMMA) nanoparticles were synthesized by combined dispersion and emulsion polymerization, using aqueous alcohol (methanol/water) as the dispersion medium. The influence of the dispersion medium ratio, stabilizer concentration, and initiator type and concentration on the colloidal stability, particle size, size distribution, and %conversion, was investigated. Submicron PMMA particles with a size of approximately 760 nm with a narrow size distribution, high conversion (91%) and good stability throughout the polymerization were obtained using a 50/50 methanol/water ratio, 1 wt% 2,2'-azobisisobutyronitrile (based on monomer), and 1 wt% polyvinylpyrrolidone (based on medium). With increasing the polarity of the dispersion medium (30/70 methanol/water ratio), the size and conversion of PMMA particles decreased to 345 nm and 72%, respectively.