Flame-retardant shape-stabilized phase change composites with superior solar-to-thermal conversion

Building thermal management is responsible for over 40 % of total energy use, of which about 20 % is directly related to the operation of heating. Materials saving energy to heat buildings would contribute substantially to sustainability. In this study, we have developed a series of flame-retardant shape-stabilized phase change composites (PCCs) by incorporating MXene@PTA and flame-retardant phytic acid dicyandiamide (PD) into a waterborne polyurethane framework using a simple vacuum impregnation technique, and their thermophysical properties , photothermal conversion, and flammable retardant performance were systematically studied. It was found that the resulting composite, termed PMWP PCCs, achieved an enthalpy efficiency and relative enthalpy efficiency of 68.66 % and 99.7 %, respectively. And it maintained excellent shape stability even after 180min at 70 °C, which demonstrates effective inhibition of leakage of phase change material . Furthermore, the maximum temperature of PCCs without modified MXene was observed to be around 37 °C, which rose to more than 45 °C after adding modified MXene, indicating higher photothermal conversion performance. Most importantly, compared to pure PEG , the peak heat release rate and total heat release value of the modified phase change composites were found to be reduced by 6.7–35.8 % and 13.2–19 %, respectively. The results suggest that the combination of MXene and PD exhibits a synergistic flame retardant effect, enhancing the flame retardancy. These outcomes underscore the promising application potential of PMWP PCCs in the fields of thermal management and energy storage. • MXene@PTA reinforced WPU framework can result in effective inhibition of leakage of phase change composties (PCCs). • The obtained PCCs hold improved flame retardancy, good shape stability, and solar-thermal conversion ability. • The obtained PCCs demonstrate great potential for passive building energy saving.