High thermal storage capacity phase change microcapsules for heat transfer enhancement through hydroxylated-silanized nano-silicon carbide

In this study, nano-silicon carbide (SiC) doped tetradecyl octadecanoate (TO) phase change microcapsules with enhanced thermal energy transfer and storage capacity were prepared through interfacial polymerization. Besides, a series of experiments were performed to comparatively investigate the effects of SiC, hydroxylated SiC (H–SiC), and hydroxylated-silanized SiC (Si–H–SiC) on the morphology, chemical structure, thermal storage performance, thermal stability, cyclic thermal stability, thermal conductivity, and exudation stability of prepared phase change microcapsules. The findings show that phase change microcapsules containing 1 wt% Si–H–SiC exhibit the best performance, as evidenced by their large thermal storage capacity (161.54 J/g) and high encapsulation efficiency (69.03 %). The thermal conductivity of Si–H–SiC-doped phase change microcapsules is up to 0.1167 W/m·k, being 17.6 % higher than that of SiC-doped ones. In addition, they show favorable thermal stability and reliability as no leakage is found after 300 thermal cycles, and they barely leak the core material TO after being kept at 120 °C for 2 h. The reason behind this phenomenon is that Si–H–SiC is doped into the shell of phase change microcapsules through chemical bonds and gets evenly distributed, which greatly improves the interfacial thermal resistance and capsule wall strength of phase change microcapsules.