Preparation and Properties of High Thermostability Phase-change Material Microcapsules

Microcapsules containing phase change materials (PCM) are commonly used in many energy storage fields. However, most PCM microcapsules have lower themostability with an onset decomposition temperature of about 150 degrees C, which to some extent restricts their application. In this study, high thermostability PCM microcapsules were synthesized with long chain ester as PCM and PMMA as shell. During the preparation, high chain ester of dodecanol laurate was first synthesized by an esterification reaction under catalysis, then the ester as core material was encapsulated using PMMA by emulsion polymerization. The resultant products were characterized by infrared spectroscopy (IR), differential scanning calorimeter (DSC), thermogravimetry (TG), laser particle size analyzer and scanning electron microscope (SEM). The synthesized dodecanol laurate have a high purity according to the IR spectrum analysis with a suitable phase temperature range of 22-30 degrees C. In addition, the ester also shows good thermal properties with latent heat of 206 J/g, small super-cooling degree of 0.5 degrees C and high thermal evaporation temperature of 220 degrees C, which is very suitable for applying in PCM energy storage materials. Using the above ester as core material, the PCM microcapsules were successfully fabricated by emulsification and polymerization. The prepared microcapsules had a perfect spherical shape with about a diameter of about 865 nm as well as a high heat storage performance with a latent energy of 118 J/g. Due to the high evaporation temperature of the ester core material itself, and with further encapsulation, the prepared PCM microcapsules demonstrated higher thermostability. TG results suggest that the microcapsules have a high onset weight loss temperature of over 252 degrees C due to the encapsulation of PMMA, it is a significant increment when compared to PCM microcapsules reported by most literatures.