Double-Crosslinked Organic–Inorganic Hybrid Polyimide Aerogel Composites with Ultra-Robust Toughness for Foldable Mechanical-Thermal-Coupled Protection

Aerogels excel in thermal insulation due to their porous structure, but their limited mechanical strength restricts broader applications. Thus, the development of aerogel composites for equipment/personnel against mechanical and thermal hazards in extreme environments necessitates more design paradigm. Herein, a novel double-crosslinked polyimide aerogel composite (PIAC) with an organic–inorganic hybridization approach is prepared. This composite, incorporating amino-modified SiO 2 nanoparticles to reduce shrinkage/density, offers exceptional thermal insulation from -110 °C to 300 °C, flame resistance, a low dielectric constant (1.4), a low thermal conductivity 0.0357 W (m K) −1 and self-cleaning properties. Meanwhile, the PIAC allows to be manipulated into various shapes and to withstand repeated folding and unfolding without damage. It boasts a tensile strength of 8.5 MPa (2.6-fold enhancement) and a nominal elongation at break of 54% (17.5-fold enhancement), representing the highest fracture toughness 32.99 × 10 6 kJ m −3 (47.8-fold enhancement) observed in aerogel materials to date. With the maximum energy absorption reaching 7.46 MJ m −3 when dissipating high-impact forces, its substantial enhancement in energy absorption capacity is 60% over its predecessor, for the SiO 2 nanoparticles not only bolster the matrix strength but also amplify strain rate strengthening effect. The fabricated PIAC is poised for foldable mechanical-thermal-coupled protection where such attributes are highly coveted.