From the viewpoint of heat storage application, encapsulation of n-hexadecane (HD) was carried out by micro-suspension copolymerizations of divinylbenzene (DVB) and acrylic monomers (butyl acrylate, BA; ethyl acrylate, EA) utilizing the selfassembling of phase separated polymer (SaPSeP) method proposed by the authors. The heat of solidification (H s) of encapsulated HD in the micron-sized, cross-linked particles was determined by differential scanning calorimeter (DSC). H s of the encapsulated HD in poly(DVB) particles was much lower than that of pure HD, but it was increased with BA or EA content copolymerized up to that of pure HD. Such an influence of encapsulation on the H s was discussed.

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The encapsulation of Rubitherm®27 (RT27), which is one of the most common commercially supplied heat storage materials, by polystyrene (PS), polydivinyl benzene (PDVB) and polymethyl methacrylate (PMMA) was carried out using conventional radical microsuspension polymerization. The products were purified to remove free RT27 and free polymer particles without RT27. In the cases of PS and PDVB microcapsules, the latent heats of melting and crystallization for RT27 ( and , J/g-RT27) were clearly decreased by the encapsulation. On the other hand, those of the PMMA microcapsules were the same as pure RT27. A supercooling phenomenon was observed not only for PS and PDVB but also for the PMMA microcapsules. These results indicate that the thermal properties of the heat storage materials encapsulated depend on the type of polymer shells, i.e., encapsulation by polymer shell changes the thermal properties of RT27. This is quite different from the idea of other groups in the world, in which they discussed the thermal properties based on the ΔHm and ΔHc values expressed in J/g-capsule, assuming that the thermal properties of the heat storage materials are not changed by the encapsulation. Hereafter, this report should raise an alarm concerning the "wrong" common knowledge behind developing the encapsulation technology of heat storage materials.

Poly(divinylbenzene) (PDVB) microencapsulated octadecane (OD) (PDVB/OD) for use as a heat storage material was prepared by the microsuspension polymerization of DVB/OD droplets, first generated by phase inversion emulsification (PIE). The influence of the surfactant on the colloidal stability, particle size and particle size distribution (PSD) was investigated. Capsules with a size of approximately 1.5 mm, a narrow PSD, and good colloidal stability throughout the polymerization were obtained using polyvinyl alcohol and sodium dodecyl sulfate as the surfactant and cosurfactant, respectively, in the process of PIE.The optical and scanning electron micrographs showed that the microcapsules have a spherical shape and display a dented surface. The thermal properties and thermal stability of the PDVB/OD microcapsules were determined using a differential scanning calorimeter (DSC) and thermogravimetric analyzer, respectively.From the DSC analysis, the onset melting temperature (T m ) of the encapsulated OD (22.6 uC) was slightly lower than that of the bulk OD (28.7 uC), while it was significantly different in the case of the crystallization temperature (T c , 12.4 uC and 26.3 uC for encapsulated and bulk OD, respectively). The latent heats of melting (H m , 192 J g 21 -OD) and crystallization (H c , 195 J g 21 -OD) of the encapsulated OD were close to those of the bulk OD (215 and 220 J g 21 , respectively).

Micrometer-sized poly(methyl methacrylate) (PMMA) particles were successfully prepared without submicrometer-sized by-products for the first time by applying microsuspension iodine transfer polymerization with iodoform as a chain transfer agent.

The thermal properties of n-hexadecane (HD) encapsulated in crosslinked capsule particles containing a water and/or air domain were studied from the viewpoint of heat-storage applications. The capsule particles were prepared by the microsuspension polymerization of divinylbenzene at 70 C with the self-assembling of phaseseparated polymer method that we developed. In the differential scanning calorimetric thermograms, pure HD had a single solidification temperature (T s ) peak at 15 C, whereas the encapsulated HD containing a water domain had two peaks at 6 and 1 C. That is, the encapsulated HD containing the water domain required a longer time and lower temperature to complete the solidification than pure HD, which was negative for heat-storage applications. However, once the particles were dried and the water domain was replaced with air, the problem with the partially lowered T s improved. The air domain was also found in the encapsulated HD core after solidification because of the shrinkage of HD. The presence of the air domain did not affect the thermal stability of the encapsulated HD.

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Poly(divinylbenzene) (PDVB) microcapsules containing octadecane (OD) (PDVB/OD) used as heat storage material were synthesized by suspension polymerization at 70 Microencapsulation, Microcapsule, Heat Storage Material, Octadecane, Suspension Polymerization, Poly(Divinylbenzene)C using benzoyl peroxide and polyvinyl alcohol as initiator and stabilizer, respectively. Thermal properties and stability of PDVB/OD microcapsules were determined using differential scanning calorimeter (DSC) and thermogravimetric analyzer. The morphology and structure of microcapsules were characterized by optical microscope, scanning electron microscope and fourier transform infrared spectrophotometer. From DSC analysis, the melting temperature of encapsulated OD (28^oC) was almost the same as that of bulk OD (30^oC) while it was quite different in the case of the solidification temperature (19^oC and 25^oC for encapsulated and bulk OD, respectively). The latent heats of melting (184.0 J/g-OD) and solidification (183.2 J/g-OD) of encapsulated OD were reduced from those of bulk OD (241.7 and 247.0 J/g, respectively). However, the prepared PDVB/OD microcapsules are able to be used for heat storage applications