Nanoscale Covalent Organic Framework Confinement Enables Ultratough and Hyperelastic Hydrogels Applied as...

Hydrogels are widely applied in various fields, including energy storage and flexible electronics. However, their mechanical properties often fail to meet the requirements for long-term and repeated deformation and full recovery. Achieving simultaneous improvement in the strength, toughness, and elasticity of hydrogels remains a significant challenge. Here, we report a nanoconfined polymerization strategy within the well-designed, fully delaminated nanoscale covalent organic frameworks (nCOFs) that overcomes these trade-offs. This approach yields hydrogels with an order increase in strength (from 0.3 to 3.2 MPa), a two orders enhancement in toughness (from 7.5 to 186 MJ/m³) and fracture energy (from 0.8 to 14.7 kJ m^-2), and a very low-hysteresis (∼93% energy recovery) recoverable deformation even after 2000% strain in the 100 cycles. The dense entanglements provide high strength and toughness, and nanochannel-threaded crosslinking enables large elastic deformation. Furthermore, their robust architecture affords a fivefold improvement in puncture resistance, enabling application as dendrite-inhibiting and durable quasi-solid-state Zn-ion electrolytes. This bottom-up toughening strategy based on the nano-reactor nCOF structural design could guide the development of next-generation tough hydrogels for applications such as flexible energy devices and related fields.