Supramolecular Engineering of Dynamically Interlocked Dual‐Stiffness Interphase for Biomimetic Strong and Tough Double Network Aerogel

Resolving the fundamental modulus‐toughness trade‐off in organic‐inorganic hybrids remains a formidable challenge in supramolecular chemistry and materials science. Herein, we present a molecular‐level design of a dynamically interlocked dual‐stiffness interphase to break this limit, utilizing an aramid nanofiber/silica double‐network architecture. Unlike traditional physical blending, this interphase is governed by a bidirectional hydrogen‐bonding network. Through deep spectroscopic investigations, we reveal that this strong interfacial interaction triggers an intramolecular proton transfer and electronic redistribution within the ANFs. More intriguingly, this supramolecular interaction drives a rare and critical structural phase transition within the inorganic network, transforming flexible six‐membered siloxane rings (SiO) 6 into rigid four‐membered rings (SiO) 4 . Macroscopically, this chemical interphase is integrated into a biomimetic skin‐core aerogel fiber. The bimodal chemical interactions—static anchoring and dynamic silanol‐mediated slippage—synergistically endow the hybrid with an ultrahigh modulus (1.15 GPa) and exceptional toughness (8.1 MJ m −3 ), while preserving intrinsic extreme‐temperature stability. This chemically driven dynamic phase‐reconfiguration mechanism establishes a universal theoretical framework for interphase engineering, offering profound insights for the precise construction of high‐performance multifunctional nanocomposites.