Pod-inspired emulsion-crosslinking strategy for intrinsically flexible, flame-retardant, and photothermal phase change composites

Developing flexible, form-stable phase change materials (PCMs) that simultaneously possess high photothermal conversion efficiency and robust flame retardancy is crucial for optimizing solar energy utilization. However, conventional composites typically struggle with an inherent trade-off between preventing liquid leakage and maintaining mechanical flexibility, primarily due to their rigid, continuous network structures. Inspired by natural pod structures, we report an innovative emulsion-crosslinking approach to fabricate intrinsically flexible phase change composites (MSPCFs). By establishing a stable water-in-oil emulsion, polyethylene glycol (PEG) serves as the dispersed phase encapsulated within a flexible, crosslinked organosilicon continuous matrix. This unique discrete, non-continuous morphology effectively eradicates leakage risks while imparting superior intrinsic flexibility compared to traditional porous scaffolds. To further elevate performance, a novel phosphorus-based flame retardant (DOPO-HEA) and single-layer Ti 3 C 2 T x MXene were synthesized and synergistically incorporated. The optimized MSPCFs demonstrate exceptional multifunctionality, exhibiting a 64.6% enhancement in thermal conductivity and a remarkable solar-thermal storage efficiency of 88.41%. Moreover, fire safety is significantly improved, evidenced by a 58.3% reduction in peak heat release rate. This study provides a pioneering strategy for designing safe, shape-stable, and intrinsically flexible PCMs, offering significant potential for efficient solar-thermal energy storage and advanced thermal management applications.