Paraffin@Silica Microencapsulated Phase Change Materials with Improved Anti‐Leakage Properties

Abstract A series of paraffin (Pn)@silica (SiO 2 ) microencapsulated phase change materials (MEPCM) were synthesized by sol‐gel process using tetraethyl orthosilicate (TEOS) and silane coupling agent as precursors. The morphology and chemical compositions of Pn@SiO 2 microcapsules were characterized by SEM and FT‐IR, and thermal energy storage capacity was tested by DSC. The results showed that the Pn@SiO 2 microcapsules modified with 3‐methacryloxypropyltrimethoxysilane (MPS) had a desirable phase transition enthalpy (184.12 J/g). Meanwhile, the contact angle and leakage rate of Pn@SiO 2 microcapsules were analyzed, and the data indicated the contact angle of Pn@SiO 2 microcapsules was significantly improved and the leakage rate of Pn@SiO 2 microcapsules was reduced to different degrees by modification with silane coupling agents. The main reason is that the modification of silane coupling agents improves the wettability of silica on the surface of paraffin wax, which makes the aggregation of silica on the surface of paraffin more efficient. Among them, the Pn@SiO 2 microcapsules modified by MPS showed the most significant reduction in leakage rate, which was reduced from 8.38 % to 1.24 %. Pn@SiO 2 microcapsules modified by MPS not only showed outstanding latent heat‐storage/release capability with a high capacity but also exhibited good shape stability, high thermal stability and excellent phase‐change reliability and durability.