Hollow particles are produced by the burying of sulfate end-groups inside particles prepared by emulsion polymerization of styrene with potassium persulfate as initiator in the absence/presence of a nonionic emulsifier

We resolved the longtime enigma in emulsion polymerization of styrene with K ₂ S ₂ O ₈ by showing the fact that hollow polystyrene particles were successfully prepared by heat treatment in the emulsion state.