Synthesis and Nanoencapsulation of Poly(ethylene glycol)-Distearates Phase Change Materials for Latent Heat Storage and Release

Phase change materials (PCMs) are essential candidates for thermal energy storage and management. In this work, a library of PCMs with a wide range of phase transition temperatures and latent heat storage capacities was synthesized using green and catalyst-free esterification reactions of stearic acid with different molecular weight of poly(ethylene glycol) (PEG). In this process, the phase transition temperature and phase change enthalpies of synthesized PCMs were easily tuned by changing the molecular weight of PEG. The resultant PEG-distearates showed melting temperature in the range of 34.8–52.9 °C, with the latent heat storage capacities ranging from 121.5 to 145.1 J/g, depending on the molecular weight of PEG. These PCMs have a pleasant odor, do not undergo sublimation during their heating process, and are noncorrosive. Furthermore, to enhance its practical applicability, the PEG-distearate synthesized with PEG having 6000 MW (E6000) was nanoencapsulated into a thin silica shell using a miniemulsion-assisted sol–gel method. The nanoencapsulated E6000@SiO2 showed excellent phase change performance with more than 48% encapsulation efficiency, 100% of heat storage capacity, and more than 98% retention of heat storage capacity after continuous 50 cycles of heating and cooling.