Flexible Phase-Change Films with Exceptional Water and Temperature Resistance for Smart Personal Thermal Protection

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