Production of micron-sized monodispersed core/shell composite polymer particles by seeded dispersion polymerization

The effect of the weight ratio of seed polymer/monomer on the morphology of the poly(methyl methacrylate) (PMMA)/polystyrene (PS) monodispersed compos ite particles produced by batch seeded dispersion polymerization of styrene with 1.64-mu m-sized monodispersed PMMA seed particles in a methanol/ wate r medium (4/1 w/w) was examined. In the PMMA/PS: weight ratios of 3/1 and 2 /1, the composite particles had a clear morphology consisting of a PMMA cor e and a PS shell. In the ratio of 1/1, a lot of small PS domains were obser ved in the PMMA core though the PS shell was still formed. By stepwise addi tion of styrene monomer, the formation of the small PS domain was depressed and complete core/shell morphology was formed. Absorption/release treatmen ts of toluene into/from the PMMA/PS (1/1 w/w) composite particles resulted in a drastic morphological change from the core/shell structure to a multil ayered one.