Design and synthesis of novel microencapsulated phase change materials with enhancement of thermal conductivity and thermal stability: Self-assembled boron nitride into shell materials

A novel type of microencapsulated phase change material (micro-PCM) with boron nitride (BN) reinforced melamine-formaldehyde shell for improvement of thermal conductivity was successfully synthesized through in-situ polymerization method. The resulting micro-PCMs were found to exhibit a well-defined core-shell microstructure as well as a regular spherical morphology. The chemical composition and structural characterizations determined the successful syntheses of this microcapsule with BN reinforced melamine-formaldehyde shells in accordance with our design idea. This structure supplies the prepared micro-PCMs with excellent phase change behavior, good thermal cycling stability, and high thermal conductivity. The phase-change behavior of the micro-PCMs was verified by differential scanning calorimetry (DSC). The results revealed that the obtained microcapsules possess good phase change behavior and excellent thermal cycling stability. The crystallization enthalpy and melting enthalpy of the micro-PCMs can reach 145.5 J/g and 127.9 J/g, respectively, and have almost no change under multicycle DSC thermal cycles. Thermal conductivity analysis indicated that the thermal conductivities of micro-PCMs increased by the addition of BN incorporated into the shell of microcapsules. Furthermore, temperature-time curves demonstrated that the micro-PCMs have excellent thermal regulation properties. Herein, the novel micro-PCM developed by this study is expected to have a promising potential for applications in thermal energy storage, thermal regulation, and solar energy harvesting systems.