Synthesis and Properties of Dynamic Crosslinking Polyurethane/PEG Shape-Stable Phase Change Materials Based on the Diels–Alder Reaction

Phase change materials (PCMs) can absorb and release energy while keeping the temperature constant; hence, they play a crucial role in the thermal management field. Shape-stable phase change materials (SSPCMs) were synthesized by chemical crosslinking to address the liquid leakage problem of solid–liquid phase change materials (SLPCMs) during the phase change process. However, the abandoned SSPCMs cannot be reused and recycled, which seriously restricts their practical application. Herein, a polyurethane network containing Diels–Alder bonds was used as the enclosure compound to obtain the encapsulation of polyethylene glycol (PEG), and then, the chemical structure, crystallization behavior, and phase transition ability of SSPCMs were systematically investigated. The results showed that the SSPCMs-3 sample (300 wt % PEG) had the best comprehensive performance, an enthalpy value of 171.7 J/g, and no leakage at 80 °C for 1 h. Moreover, the structure, crystallization behavior, and phase transition ability of SSPCMs could also basically remain unchanged after multiple thermal cycling and reprocessing.