Promising candidate for thermal management: Thermophysical and mechanical properties of h-BN/polyurea@n-eicosane phase change microcapsules

Encapsulated phase change materials (MPCMs) can be used to address thermal runaway issues in electronic devices and battery systems in small spaces or flexible requirements. In this work, polyurea microcapsules incorporating h-BN and encapsulating n-eicosane were successfully synthesized. The h-BN was embedded to enhance the microcapsules' thermal conductivity. Comprehensive characterizations revealed that the microcapsules' area change rates before and after phase transition were approximately 3 %. Among the various microcapsules, h/MC-2 exhibited the best performance, with an enthalpy value of 184.37 J/g, an encapsulation efficiency of 79.72 %, and a high thermal storage efficiency of up to 99 %. Moreover, the thermal conductivity coefficient increased by 51.24 % to 0.3297 W/(m·K) due to the addition of h-BN. Mechanical properties testing was conducted on individual h/MC-2 microcapsules, revealing an average nominal rupture tension of 46.31 ± 2.09 N/m and an average Young's modulus of 0.17 ± 0.01 GPa. Furthermore, the h/MC-2 microcapsules were combined with silicone gel to prepare composites, incorporating h-BN to enhance thermal conductivity. The composites were found to reduce the simulative chip temperature by 15.90 %, demonstrating their potential application in thermal management.