Preparation of capsule particles by self-assembling phase separated polymer method and its application

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We have proposed the preparation method for micron-sized, cross-linked polystyrene/polydivinylbenzene (PS/PDVB) particles having a single hollow. The mechanism for the hollow polymer particles was based on the Self-assembling of Phase Separated Polymer at an interface with aqueous media, which was named the SaPSeP method. Recently, when the SaPSeP method was applied in the presence of sodium dodecyl sulfate (SDS), it was found that a single hole was formed in the shell of the hollow PS/PDVB composite particles.In this research, in order to clarify such a strange phenomenon, preparations of capsule particles were examined in detail. It was clarified that the phase separation in the droplets in the early stage of the polymerization was one of key factors for the formation of the single hole. Hole was most likely formed as a result of reduced microgel adsorption at oil-water interface domains of high SDS content. Moreover, we succeeded in preparing submicrometer-sized hollow PS particles, microcapsules containing curing agent for epoxy resin, and PDVB particles with encapsulated titanium oxide or n-hexadecane (HD)by micro-suspension polymerization utilizing the SaPSeP method. HD is useful for heat storage materials. The encapsulation of HD has many advantages that provide large heat transfer area and control the volume change of the heat storage materials. However, there were some problems in encapsulated HD such as decrease of the heat of solidification and supercooling. In this research, the problem in the application of the polymer particles with encapsulated HD as heat storage material was improved by the copolymerization of hydrophilic acrylic monomer. This seems to be based on that the copolymerizations of hydrophilic monomer enhance the phase separation of copolymer chains and HD, eventually resulting in the complete isolation of the HD core from the polymer shell.