Fatigue-resistant and thermal insulating polyimide nanofibrous aerogels with temperature-invariant flexibility and nanofiber-lamella crosslinking architecture

Nanofibrous aerogels with excellent flexibility and compressibility, assembled from one-dimensional nanofibers, are attractive candidates for flexible thermal protection. However, achieving high mechanical stability of the three-dimensional network of nanofibers remains challenging owing to the weak interactions between the nanofibers. Herein, we report a new strategy of crosslinking nanofibers with two-dimensional lamellae for the construction of fatigue-resistant polyimide nanofibrous aerogels (PINAs) with temperature-invariant flexibility. The interaction between the nanofibers and the lamellae results in a self-assembled network with high nodal articulation and strong crosslinking between the nanofibers. The stable crosslinking structure between the nanofibers and lamellae also provides the PINAs with temperature-invariant flexibility (−196 °C to 300 °C), good mechanical properties and a high strain recovery rate of 97% (10 000 compression-release cycles at 75% strain). More significantly, when suffering from a large strain (≥95%), the PINAs can be repeatedly compressed for 100 cycles with little structural degradation, highlighting their good resilience. In addition, the resulting PINAs exhibit a low thermal conductivity of 26.4 mW m⁻¹ K⁻¹ at room temperature, which can be applied as flexible thermal insulators. These nanofibrous aerogels with a nanofiber-lamella crosslinking architecture may provide new insights into the development of ultralight aerogel materials with excellent resilience and stability.