Highly‐Buckled Nanofibrous Ceramic Aerogels with Ultra‐Large Stretchability and Tensile‐Insensitive Thermal Insulation

Ceramic aerogels have exhibited many superior characteristics with promising applications. As an attractive material system for thermal insulation under extreme conditions, ceramic aerogels are required to withstand complex thermomechanical stress to retain their super-insulating properties but, they often suffer from severe fracture damage that can lead to catastrophic failure. Herein, inspired by the tendrils of Parthenocissus, we report a design and synthesis of ultra-stretchable ceramic aerogels constructed by highly buckled nanofibers. The buckling of nanofibers is formed by asymmetric deformation through two-component off-axial electrospinning method. The resulting aerogels feature an ultra-large stretchability with a tensile strain of up to 150% and high restorability with a tensile strain of up to 80%. They also display a near-zero Poisson's ratio (4.3 × 10^-2) and a near-zero thermal expansion coefficient (2.6 × 10^-7 per °C), resulting in excellent thermomechanical stability. Benefiting from this ultra-stretchability, the aerogels exhibit a unique tensile-insensitive thermal insulation performance with thermal conductivities remaining only ≈106.7 mW m^-1 K^-1 at 1000 °C. This work promotes the development of ceramic aerogels for robust thermal insulation under extreme conditions and establishes a set of fundamental considerations in structural design of stretchable aerogels for a wide spectrum of applications.