Hyperelastic Kevlar Nanofiber Aerogels as Robust Thermal Switches for Smart Thermal Management.

Abstract

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.