Polyethylene glycol/silica (PEG@SiO2) composite inspired by the synthesis of mesoporous materials as shape-stabilized phase change material for energy storage

Inspired by the common preparation method of mesoporous silica where polyethylene glycol (PEG) was used as template to obtain porous silica, PEG/silica (PEG@SiO2) composite as shape-stabilized phase change material for energy storage was well prepared. In this paper, PEG was used as phase change material (PCM) to store and release thermal energy and SiO2 acted as the supporting matrix. Various techniques were employed to characterize the structural and thermal properties of PEG@SiO2. The results indicate that PEG was encapsulated in SiO2 shell with physical interactions. The phase change enthalpy of PEG@SiO2 is 164.9 J/g in the melting process and 160.1 J/g in the solidifying process with the mass fraction of 97 wt%. It is a considerably exciting result as the value is so close to pristine PEG's (178.6 J/g). PEG@SiO2 exhibited excellent thermal reliability based on the results of undergoing the heating-cooling cycle 100 times. Also, PEG@SiO2 had a good thermal stability within its working temperature range. This study provides a general approach for increasing the loading of PCMs in porous materials and thus the energy storage capability. (C) 2019 Elsevier Ltd. All rights reserved.