Study on preparation and process of poly(MMA‐St) thermally expandablecore‐shellmicrospheres

Abstract

AbstractThermally expandable microspheres were synthesized by the suspension polymerization of methyl methacrylate (MMA) and styrene (St) in the presence of paraffin blowing agents. The effect of the monomer composition, the initiator, the blowing agent, the polymerization temperature on the morphology and structure of microspheres were studied. The results showed that AIBN initiated the water phase polymerization of MMA to form secondary polymer particles adsorbed on the surface of the microspheres. MMA diffused from the oil phase to the water phase, which accelerated the phase separation and facilitated the formation of core‐shell microspheres. However, LPO could not initiate the water phase polymerization, the phase separation was slow and there was an intermediate state with a porous surface. When the boiling point of the blowing agent was lower than the polymerization temperature, the microspheres were porous and there were a large number of holes on the surface.