Fabrication of silica hard-shell microcapsule containing inorganic phase-change materials.

The fabrication of silica hard shell microcapsules containing disodium hydrogen phosphate dodecahydrate has been developed. The effects of the mixing rate and time to emulsification of solutions added by a homogenizer, volume ratio of solutions and of surfactant concentration on the size of porous hollow microcapsule have been studied. From the results, it was found that the effect of mixing conditions and of the volume ratio is rather small compared with that of surfactant concentration in the present range. Thus, it was concluded that the control of the surfactant concentration is effective for controlling the size of microcapsule. It was also found that the containing ratio of disodium hydrogen phosphate dodecahydrate is smaller than the void fraction of microcapsules. This was considered partially due to the microcapsule agglomeration and partially to hydrogen desorption through the shell during of the reaction. The supercooling depression in the microcapsules was also found in this study. Thus, the present microcapsule was concluded to be a promising item not only as latent heat transportation media but also as static thermal storage materials.