Emulsion polymerization of styrene in the presence of a mixture of oil- and water-soluble initiators

The rate of emulsion polymerization of styrene initiated with a combination of benzoyl peroxide and potassium persulfate and the molecular weight of the polymer are proportional to C0.4×CO and C-0.6×CO, respectively. The polymerization rate does not depend on benzoyl peroxide concentration because the poorly soluble initiator has no effect on the particle nucleation process and on the average number of radicals per particle (n0.5)×Mn does not depend on potassium persulfate concentration, which is attributable to the constant rate of radical entry from the water phase to the individual particle regardless potassium persulfate level fluctuations, because aqueous environment favors the bimolecular termination of oligomeric radicals.