Pn@MF@SiO₂ Double-Shelled Phase Change Microcapsules with High Latent Heat and Low Leakage Rate

Microencapsulation of paraffin with melamine formaldehyde shell (Pn@MF) shows the drawbacks of low thermal conductivity. Hence, we constructed SiO₂ shells on Pn@MF phase change microcapsules by interfacial polycondensation to obtain Pn@MF@SiO₂ double-shelled microcapsules. The effect of tetraethoxysilane (TEOS) contents on the performance of Pn@MF@SiO₂ was discussed in detail. As the TEOS contents increased, the thermal conductivity of Pn@MF@SiO₂ gradually increased, reaching up to 0.376 W m⁻¹ K⁻¹. The Pn@MF@SiO₂ have exhibited superior leakage-proof properties and thermal reliability through double-shelled protection, and the highest reduction in leakage rate reached 45.06 % compared to Pn@MF microcapsules. The Pn@MF@SiO₂-3 with the lowest enthalpy still exhibit a latent heat storage capacity of more than 176 J/g, which displayed outstanding latent heat storage/release capability and good anti-permeable property.