Thermally 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.

中文翻译：

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聚（MMA-St）热膨胀核壳微球的制备与工艺研究

在石蜡发泡剂的存在下，通过甲基丙烯酸甲酯（MMA）和苯乙烯（St）的悬浮聚合合成可热膨胀的微球。研究了单体组成，引发剂，发泡剂，聚合温度对微球形态和结构的影响。结果表明，AIBN引发了MMA的水相聚合反应，形成了吸附在微球表面的次级聚合物颗粒。MMA从油相扩散到水相，这加速了相分离并促进了核壳微球的形成。然而，LPO不能引发水相聚合，相分离缓慢并且存在具有多孔表面的中间状态。