Refinement of Crystalline Domains: A Strategy To Toughen Conductive Hydrogels

The characteristic of possessing both high strength and flexibility is a requisite for the extensive application of conductive hydrogels in the domains of flexible wearable electronic devices and implantable biomedical fields. Nevertheless, the existing strategies for optimizing mechanical properties invariably enhance the strength at the expense of stretchability, thereby causing the hydrogels to still possess relatively low toughness. Herein, we propose a crystalline refinement-driven toughening strategy that overcomes this paradigm, achieving strength of 13.4 ± 1.1 MPa, fracture strain of 2337 ± 246.2%, and toughness of 164.6 ± 25.6 MJ·m^-3. The crux of maintaining flexibility while elevating strength lies in perfecting the energy dissipation mechanism with the concurrent preservation of molecular chain extensibility. To achieve strength-toughness synergy in hydrogel systems, a crystalline domain-featured layered architecture is assembled via a controlled drying process, followed by precise modulation of domain dimensions through high-density hydrogen-bond networks during rehydration, ultimately engineering a hierarchical structure dominated by refined crystalline domains. The hydrogel's good mechanical properties impart exceptional lubricity and robust sensing capabilities, underscoring its promising applicability in biomedical and wearable device technologies.