Bioinspired melamine foam-based phase change composite with high energy storage for waste-heat recovery utilization and thermal management

Phase change materials (PCMs) demonstrate significant advantages in thermal energy storage and management systems due to their high enthalpy and almost constant phase transition temperatures. However, challenges such as inherent low thermal conductivity, flammability and leakage have limited their broad application. To address these issues, a biomimetic structural phase change composite (PEG/MF/PR) inspired by tomato was developed. This composite employed a melamine foam (MF) skeleton impregnated with phenolic resin (PR) followed by curing, which vacuum-adsorbed polyethylene glycol (PEG). In this biomimetic design, the MF functioned as columellar and vascular bundles, providing skeletal support; and the cured PR corresponded to flesh, enhancing mechanical strength of skeletal scaffold while providing abundant binding sites, thereby enabling the efficient encapsulation of PEG analogous to gelatinous substance. The obtained skeletal scaffold demonstrated a high PEG adsorption rate consistently above 84.5 wt%, along with superior leakage-proof feature. The PEG/MF/PR achieved an exceptional heat enthalpy of 159.2 J/g with a relative enthalpy efficiency of 97.1%, and exhibited outstanding thermal storage stability after undergoing 100 heating-cooling cycles. Thermal conductivity of PEG/MF/PR was approximately 0.1789 W·m −1 ·K −1 , representing a 41.4% enhancement compared to that of PEG/MF. More importantly, photothermal conversion capability of PEG/MF/PR was significantly enhanced due to the conjugated structures formed during PR curing and color darkening. The inherent flammability and dripping tendency of PEG upon exposure to flame were successfully mitigated by flame-retardant skeletal scaffold. Thus, the developed phase change composite provides great potential in waste-heat recovery and thermal management.