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Aerogels, the lightest artificial solid materials characterized by low density and thermal conductivity, high porosity, and large specific surface area, have attracted increasing interest. Aerogels exhibit single-mode thermal insulation properties regardless of the surrounding temperature. In this study, hyperelastic Kevlar nanofiber aerogels (HEKAs) are designed and fabricated by a slow-proton-release-modulating gelation and thermoinduced crosslinking strategy. The method does not use crosslinking agents and endows the ultralow-density (4.7 mg cm-3 ) HEKAs with low thermal conductivity (0.029 W m-1 K-1 ), high porosity (99.75%), high thermal stability (550 °C), and increased compression resilience (80%) and fatigue resistance. Proofs of the concept of the HEKAs acting as on-off thermal switches are demonstrated through experiments and simulations. The thermal switches exhibit a rapid thermal response speed of 0.73 °C s-1 , high heat flux of 2044 J m-2 s-1 , and switching ratio of 7.5. Heat dissipation can be reversibly switched on/off more than fifty times owing to the hyperelasticity and fatigue resistance of the HEKAs. This study suggests a route to fulfill the hyperelasticity of highly porous aerogels and to tailor heat flux on-demand.
Hu et al. (Sat,) studied this question.