Gelation‐Constrained Freeze‐Casting Fabrication of Ultra‐Homogeneous Nanocomposite Aerogels with Superelasticity and Harsh Environment Tolerance

Abstract Freeze casting is a versatile technique for organizing low‐dimensional building blocks into ordered porous structural materials. However, the freeze‐casting fabrication of porous materials with a robust and topologically elastic skeleton to withstand harsh conditions is challenging. Herein, a silanized ultra‐homogeneous nanocomposite aerogel is fabricated using a gelation‐constrained freeze‐casting strategy. Diverging from traditional freeze‐casting methods employing a solution precursor, the approach involves a gelation‐constrained freeze‐casting process utilizing a rational‐designed supramolecular hydrogel as the quasi‐solid precursor. The low‐dimensional building blocks within the hydrogel, enclosed in a dense hydrogen‐bonded network, effectively mitigate secondary agglomeration caused by ice crystallization and concentration enrichment during freeze‐casting. By forming a topologically elastic cellular skeleton with an interconnected nanoparticle network, the resulting aerogels exhibit exceptional mechanical elasticity retaining over 98% height after 10 000 compression cycles, along with superior electrical properties showing a 78.9% increase in conductivity compared to conventional freeze‐casting aerogels. Wearable piezoresistive sensors with these aerogels demonstrate outstanding force sensing capabilities, showing a broad linear range (0–17.6 kPa) and high sensitivity (1.32 kPa⁻¹). When integrated as an intermediate layer in protective garments, these sensors offer exceptional insulation and fire resistance, enabling them to endure harsh conditions like repetitive extreme deformations, exposure to high‐temperature flames, and water‐erosion damages.