Polymerization Conditions and the Development of a Core-Shell Morphology in PMMA/PS Latex Particles. 1. Influence of Initiator Properties and Mode of Monomer Addition

Latex particles containing equal amounts of poly(methylmethacrylate) (PMMA) and polystyrene (PS) were prepared by polymerizing styrene in the presence of PMMA seed particles using two different initiators, potassium persulfate (KPS) and tert-butyl hydroperoxide (t-BHP). Styrene was added either before polymerization (batch) or continuously during the polymerization. Particles prepared using batch addition of styrene showed no signs of a core-shell morphology, and the surface concentration of PS was lower than 50%. Particles with well-defined core-shell structures were obtained when styrene was added at a low feed rate