Room-Temperature Self-Healing Soft Composite Network with Unprecedented Crack Propagation Resistance Enabled by Supramolecular Assembled Lamellar Structure.

Soft self-healing materials are compelling candidates for stretchable devices because of their excellent compliance, extensibility, and self-restorability. However, most existing soft self-healing polymers suffer from crack propagation and irreversible fatigue failure due to easy breakage of their dynamic amorphous low-energy polymer networks. Herein, inspired by distinct structure-property relationship of biological tissues, we propose a supramolecular interfacial assembly strategy of preparing soft self-healing composites with unprecedented crack propagation resistance by structurally engineering preferentially-aligned lamellar structures within dynamic and super-stretchable poly(urea-ureathane) matrixes (which can be elongated to 24750× its original length). Such a design affords world-record fracture energy (501.6 kJ m -2 ), ultra-high fatigue threshold (4064.1 J m -2 ), and outstanding elastic restorability (dimensional recovery from 13 times elongation), and preserving low modulus (1.2 MPa), high stretchability (3200%), high room-temperature self-healing efficiency (97%). Thereby, the resultant composite represents the best of its kind and even surpasses most natural biological tissues. The lamellar MXene (2D transition metal carbide/carbonitride) structure also leads to a relatively high in-plane thermal conductivity, enabling composite as stretchable thermo-conductive skins applied in joints of robotics to enable thermal dissipation. The present work illustrates a viable approach how autonomous self-healing, crack tolerance and fatigue resistance can be merged in future material design. This article is protected by copyright. All rights reserved.