Stable and reliable PEG/TiO2 phase change composite with enhanced thermal conductivity based on a facile sol-gel method without deionized water

Abstract

Some shortcomings exist in organic phase change materials, including leakage susceptibility, low thermal conductivity, and preparation complexity. Herein, polyethylene glycol/titanium dioxide shape-stabilized composite phase change material (PEG/TiO2 ss-CPCM) was fabricated by facile sol-gel method without deionized water using tetrabutyl titanate (TBOT) as precursor. In this composite, not adding deionized water prolonged the gelation time, allowing PEG to bind as much TiO2 as possible and enhancing energy storage capability; TiO2 acted as the supporting framework to maintain the material's shape stability and enhance thermal conductivity. The melting and crystallization phase change enthalpies of prepared PEG/TiO2 ss-CPCM were 128.3 J/g and 113.1 J/g with an encapsulation efficiency of 74.14 % when PEG: TBOT = 1.5: 1. After repeating 300 thermal cycles, the phase change enthalpy remained almost constant. Besides, the thermal conductivity of PEG/TiO2 ss-CPCM was 1.22 times that of PEG, and the potential for thermal management applications. The advantages (energy storage capability, shape stability in thermal environments, thermal reliability, and thermal management) of the PEG/TiO2 ss-CPCM prepared by facile synthesis, not only propose a phase change material with excellent thermal properties and shape stabilization but provide a green and feasible strategy for the fabrication of PEG/TiO2 composite phase change materials utilizing the sol-gel method.