Superhygroscopic Multilayer Microfibrous Membrane for Cold Stress Management

In subzero environments, moisture from exhaled breath and perspiration readily condenses and freezes inside protective gear, accelerating heat loss and triggering severe cold stress. To address this issue, this study developed a sandwich-structured microfibrous membrane that enabled rapid moisture capture, condensation/freezing inhibition, real-time thermal compensation, and solar-driven regeneration. Even at -21 °C, the membrane can still achieve a high water uptake of 1.41 g g^-1 at 90% RH, while storing the absorbed water in a nonfrozen state and releasing appreciable absorption heat to create localized warming zones. The integrated photothermal layer enabled the membrane to regenerate rapidly with low energy consumption, releasing approximately 99% of the absorbed water within 7 min under 1 sun illumination and about 50% within 12 min under 0.4 sun. When integrated into a face mask, the membrane effectively suppressed moisture condensation in a real outdoor environment at -2 °C and elevated the inner-surface temperature from 3.5 to 13.6 °C. This study demonstrates a self-adaptive passive thermal-moisture management material, offering a promising strategy for the smart textiles for extreme-cold protection.