Preparation of PU/SiO2 2 composite shell microencapsulated phase change materials with high thermal stability and thermal conductivity

To address the issues of poor thermal stability and thermal conductivity in polyurethane (PU) shell micro- encapsulated phase change materials (MEPCMs), this study prepared PU/SiO2-MEPCMs 2-MEPCMs using an interfacial polymerization method combined with electrostatic self-assembly technology. First, the PU shell was synthesized via an interfacial polymerization reaction between isophorone diisocyanate (IPDI) and triethanolamine (TEA). Subsequently, the hydrolyzed product of tetraethyl orthosilicate (TEOS), monosilicic acid (Si (OH)4), 4 ), was adsorbed onto the PU shell surface using electrostatic self-assembly technology and reacted with the -NCO groups to form an SiO2 2 shell. The effects of the PU/SiO2 2 composite shell on the surface morphology, chemical structure, compactness, thermal stability, phase transition performance, thermal conductivity, and thermal cycling stability of MEPCMs were investigated. The results showed that the formation of the PU/SiO2 2 composite shell significantly improved the thermal stability, compactness, thermal conductivity, and cyclic stability of MEPCMs. After continuous treatment at 150 degrees C degrees C for 120 min, the leakage rate of the core material decreased from 12.13 % to 3.74 % , and the heat-resistant temperature (T95 95 % ) increased by 30 degrees C. degrees C . Even after 1000 thermal cycles, MEPCMs still exhibited excellent heat storage performance. Additionally, even under high temperature conditions of 257 degrees C degrees C (where pure butyl stearate completely decomposes), the PU/SiO2-MEPCMs 2-MEPCMs still maintained a stable core-shell structure. The introduction of the SiO2 2 shell greatly enhanced the thermal conductivity of MEPCMs, aligning the phase change temperature more closely with that of the core material and effectively reducing the supercooling phenomenon. Furthermore, the stable energy storage system formed by MEPCMs on the finished fabric surface can endow it with excellent temperature regulation functionality.