Flexible Phase-Change\nFilms with Exceptional Water\nand Temperature Resistance for Smart Personal Thermal Protection

Personal thermal protection is crucial in extreme temperature\nenvironments,\nand the rising global temperatures present significant challenges\nin managing heat stress for individuals. Phase-change materials (PCMs)\ncan absorb or release heat during phase transition to maintain a constant\ntemperature, thus making them ideal innovative thermal protection\nmaterials. However, it is currently a bottleneck issue for using PCMs\nin wearable thermal protection systems due to a balance between the\nmechanical properties, latent heat, temperature resistance, and rapid\nresponse on demand. Herein, a flexible composite PCM film is developed\nand demonstrated by incorporating superhydrophobic silica aerogel\nparticles (SSAPs) in a cross-linked poly(ethylene glycol) (PEG) network.\nThe cross-linked network effectively addresses the inherent solid–liquid\nphase-change issue of PCMs, providing self-support, high flexibility,\nand heat resistance. Meanwhile, the SSAP endows water resistance and\nsynergistic thermal insulation properties to the PCM film. When the\nSSAP content is adjusted, a latent heat range of 113.1–146.9\nJ g<sup>–1</sup> is achieved. Despite a lower latent heat of\nthe PCM film than pure PEG films, a temperature drop of 13.8 °C\nis achieved at 80 °C, marking a 2.65-fold enhancement. Interestingly,\nthe heating rate of the PCM film is decelerated by 275% compared to\nthat of pure PEG cross-linked networks. This study not only proposes\na strategy for preparing phase-change films with flexibility and temperature\nresistance but also demonstrates their feasibility of achieving lower\nlatent heat while paradoxically enhancing thermal regulation capability.