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.