STUDIES ON SUSPENSION AND EMULSION .122. PREPARATION OF MICRON-SIZE MONODISPERSE POLYMER PARTICLES BY SEEDED POLYMERIZATION UTILIZING THE DYNAMIC MONOMER SWELLING METHOD

Utilizing a new type of monomer swelling method, 6.1-mu-m-size monodisperse polymer particles were prepared by seeded polymerization. 1.8-mu-m-size mono-disperse polystyrene (PS) seed particles (1.8-mu-m in size) were prepared by dispersion polymerization in ethanol-water (80/20, v/v) medium in the presence of poly(acrylic acid) as stabilizer with 2,2'-azobisisobutyronitrile as initiator. The PS seed dispersion was mixed with ethanol-water (60/40, v/v) solution dissolving styrene (S) monomer, benzoyl peroxide as initiator, and poly(vinyl alcohol) as stabilizer. By slow, continuous, dropwise addition of water with a micro feeder into the mixture, the PS particles absorbed the many S monomers, which were separated from the medium and swelled from 1.8-mu-m to 8.4-mu-m while keeping the monodispersity high. We named this procedure the "dynamic swelling method". Then, the seeded polymerization of the absorbed S monomer was carried out in the presence of NaNO2 as water-solube inhibitor.