Improving the shape stability and photothermal conversion performance of phase change materials through three-dimensional metal-organic network

Abstract

In order to improve the shape stability of phase change materials (PCMs) while ensuring excellent thermal energy storage / release and photo-thermal conversion performance, three-dimensional metal-organic network (MON) containing polyethylene glycol (PEG) and graphene oxide (GO) composite phase change gels (PEG/MON-G) were prepared. The morphology, structure and thermal-physical properties of the gels were investigated by various instruments. The results indicated that PEG was embedded in the three-dimensional MON constructed by coordination and hydrogen bonding of zinc ions, phytic acid and Kevlar nanofibers, ensuring the shape stability of PEG/MON-G up to 120 °C within the experimental range. Due to the dynamic fracture and recombination of coordination and hydrogen bonding interactions, the composite PCMs exhibited excellent deformability. The melting and crystallization enthalpy of PEG/MON-G containing 89.5 wt% of PEG were 143.9 J·g−1 and 141.0 J·g−1, respectively. PEG/MON-G also had good thermal reliability, in which the phase transition temperature of the melting process reduced by only 0.1 °C and the enthalpy changed only 1.4% after 200 cycles. In addition, the photo-thermal conversion efficiency of the composite phase change gels reached 74.6%. In conclusion, this study provides a new strategy for preparing the shape-stabilized PCMs.