Polyester‐based phase change materials with flexible poly(ethylene glycol) chains for thermal energy storage

ABSTRACT Phase change materials are capable of storing renewable energy in an economical, feasible, and green way. Here, novel polyester‐based solid–solid phase change materials (PPCMs) are synthesized through solvent‐free crosslinking polymerization. Poly(ethylene glycol) (PEG) is used as the phase change ingredient, while crosslinked polyester acts as the supporting material. One chain end of PEG reliably bonds with the rigid skeleton, while another chain end is movable. The combination of reliable crosslinked structures with flexible PEG chains endows the PPCMs with good thermal storage capacity and outstanding thermal reliability simultaneously. Fourier transform infrared spectroscopy is adopted to confirm the chemical structures of PPCMs. Their excellent crystalline properties are confirmed by wide‐angle X‐ray diffraction and polarizing optical microscopy (POM). Phase change properties are investigated using differential scanning calorimetry (DSC) and POM images. It is obvious in the DSC results that PPCMs have good thermal storage capacity in the range 18–63 °C with phase change enthalpy reaching 139.0 J/g. POM images vividly reveal the crystallization process of PPCMs. Additionally, thermal stability is studied using thermogravimetric analysis, and the results show that PPCMs are thermally stable up to 300 °C. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47108.