Preparation of hollow polymer particles encapsulating functional substance and its application

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Polymer particles with hollow structures have gotten a lot of attention in many industrial fields. Such particles are used as microcapsules, weight-saving or thermal insulation agents, and are applied to hiding or opacifying agents in coating and molding compositions because of their high light-scattering ability. We had succeeded in preparing micron-sized, monodisperse, crosslinking polymer particles having a single hollow at the center by seeded polymerization. Similar hollow polymer particles were produced by suspension polymerization for divinylbenzene (DVB)/toluene droplets dissolving polystyrene though they were polydisperse. The formation of the hollow structure is based on the self- assembling of phase separated polymer at the interface of the droplet. The method is named the Self-assembling of Phase Separated Polymer (SaPSeP) method.In this research, in order to clarify the formation mechanism of hollow particles by the SaPSeP method in more detail, the effects of phase separation of PDVB in the droplets, viscosity within the droplet and its size on the formation of the hollow structure were discussed. The phase separation in the early stage was required point for the formation of the hollow structure. Since the viscosity in the droplet is low at the low conversion, the PDVB can move and adsorb at the interface of the droplet. The mobility of PDVB microgels after the phase separation in polymerizing droplet was important factor for the formation of the hollow structure. The SaPSeP method was developed to produce composite particles encapsulating hinokitiol or magnetite. Moreover, the method was applied to the polyaddition reaction in a suspension system. The polyaddition reaction system satisfied the required conditions for the preparation of hollow particle by the SaPSeP method. In actual, cured epoxy resin particles having one hollow at the center were successfully prepared after evaporation of toluene.