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 degrees 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 degrees C, which rose to more than 45 degrees 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.