Thermal cycling and rheological properties of sponge-like graphene oxide/polyethylene glycol composite phase change materials

This study proposes a shape-stabilized composite phase-change material prepared by impregnating polyethylene glycol (PEG) into a three-dimensional porous sponge-like graphene oxide (SLGO) matrix. SLGO was synthesized via an improved Hummers method followed by freeze-drying. Comprehensive characterization confirmed the effective adsorption of PEG into the SLGO pores, which increased the interlayer spacing and formed hydrogen bonds. The resulting composite phase-change material exhibited a latent heat exceeding 170 J·g−1 (maintaining 162 J·g−1 after 50 cycles) and a thermal conductivity of 0.95 W·m−1·K−1. Its mechanical performance was notably superior to that of pure PEG, with 1.5-fold higher bending stress and 3-fold higher tensile stress. Rheological analysis revealed that SLGO increased the storage modulus and promoted an earlier viscous–elastic transition. Furthermore, the composite showed excellent photothermal conversion efficiency (up to 92 %), highlighting its strong potential for the efficient storage of thermal energy and solar energy utilization.