High thermal buffer and radiative cooling sodium alginate-based Janus aerogel enables multi-scenario thermal...

Firefighting clothing is an indispensable protective equipment for firefighters performing rescue activities under extreme heat and fire conditions. However, few bio-based thermal management materials that provide thermal comfort to firefighters in different operational scenarios have been reported. Herein, we present a novel strategy to prepare Janus-type aerogels based on sodium alginate biological macromolecules, consisting of a SiO₂ nanoparticle layer and a microencapsulated paraffin@SiO₂ phase-change composite layer. A passive radiative cooling and thermal energy storage was integrated into a functional dual-mode material system. Results show that Janus-type aerogel to cool down by 11.5 °C on a hot summer day. Meanwhile, paraffin@SiO₂ has a high melting enthalpy of 127.5 J g^-1 that effectively buffers temperature rise during the phase-change process. This Janus-type aerogel has ultra-low heat insulation (0.042 W/(m·K)), it can delay approximately 76.6 s to reach second-degree burn time for skin at a radiant heat exposure of 18.4 kW m^-2. The work provides an innovative way to develop bio-based thermal management materials, which could enable multi-scenario thermal management for firefighting clothing.