Morphologies of micron‐sized monodispersed composite polymer particles having crosslinked structures produced by seeded polymerizations

Three kinds of micron‐sized monodispersed polystyrene (PS)/ poly(styrene ‐ divinylbenzene) composite particles were produced by two kinds of seeded copolymerizations of styrene (S) and divinylbenzene (DVB) (PS seed/ (S+DVB)=2/1, wt. ratio; S/DVB=1/1, molar ratio) in the presence of about 2 μm‐sized monodispersed PS particles, and their morphologies were examined. One was produced by a seeded dispersion copolymerization where almost monomers and initiators exist in an ethanol/water (12.6/4.0, w/w) medium. The others two were produced by seeded copolymerizations with the dynamic swelling method where almost monomers exist in the monomer‐swollen particles using 2, 2'‐azobisisobutyronitrile in monomer‐swollen PS seed particles or using 4, 4'‐azobis (4‐cyanopentanoic acid) in an ethanol/water (7/43, w/w) medium. In the former polymerization, the produced composite particles had a high dense crosslinked shell, whereas in the latter two polymerizations, they did the comparatively homogeneous crosslinked structures.