Synthesis and Performances of Phase Change Materials Microcapsules with a Polymer/BN/TiO2 Hybrid Shell for Thermal Energy Storage

Paraffin was encapsulated in a poly(methyl methacrylate) (PMMA)/BN/TiO2 hybrid shell to obtain a novel phase change material (PCM) microcapsule for latent-heat storage. Scanning electron microscope micrographs showed that the resultant composite PCMs exhibited a nearly spherical morphology with a size of 10–20 μm and BN/TiO2 nanoparticles were tightly embedded on the microcapsule surface. The results of thermogravimetric analysis and thermal conductivity test demonstrated that the PMMA/BN/TiO2 composite shell gave the microencapsulated paraffin an excellent thermal performance. Compared to pure paraffin, the thermal conductivity of microcapsules could significantly be enhanced by 117.0%, and the maximum decomposing temperature has an increase of 25.4 °C. The analysis of differential scanning calorimetry and thermal reliability test indicated that the composite PCMs also presented good heat storage capacity and high thermal reliability for latent-heat storage and release. After a heating–cooling cycle test was repeated 100 times, the composite microcapsule still showed a similar phase change performance as before, which can be attributed to the protective effect of PMMA/BN/TiO2 hybrid shell. With increased demands for economical and high-performance renewed energy storage materials, the prepared composite PCMs show great potential applications in thermal energy storage.