Study on a novel solid–solid phase change materials: solvent-free preparation, thermal properties and phase separation behaviors

Thermal energy storage is one of the most important strategies for sustainable development. Phase change materials (PCMs) can store thermal energy through an economically feasible and eco-friendly way. Herein, we develop a novel solid–solid phase change materials (SSPCMs) based on solvent-free radical polymerization of methyl methacrylate with methacrylate-functionalized polyethylene glycol (PEG). PEG featuring as phase change ingredient is tightly bonded with reliable crosslinking network, which offers the prepared solid–solid phase change materials (SSPCMs) with robust physical properties and good shape-stable properties. The chemical structures, microstructures, crystalline properties and thermal properties of the synthesized SSPCMs are, respectively, characterized by Fourier transform infrared spectroscopy, scanning electron microscope (SEM), X-ray diffraction, polarizing optical microscopy, differential scanning calorimetry (DSC) and thermogravimetric analysis (TG). Accelerated thermal cycling test and leakage test are also conducted to illustrate the thermal reliabilities and shape-stable properties. Microphase separation is observed and discussed in SEM analysis. DSC results show that SSPCMs have reversible thermal storage capacities and their phase change enthalpies are related to the concentration of PEG content. TG and accelerated thermal cycling test explain the excellent thermal stability and reliability of SSPCMs. Therefore, the prepared SSPCMs with satisfied properties have potential in room-temperature-use thermal energy storage applications such as buildings, textile industry and so on.