Synergistic borate crosslinking and chain entanglement for mechanically robust and water-rich hydrogels

Hydrogels that simultaneously achieve high water content and mechanical robustness remain a challenge in biomaterials science, as conventional reinforcement strategies tend to conflict with hydration requirements. Herein, we present a chain entanglement-mediated dynamic crosslinking strategy that transcends this limitation in poly(vinyl alcohol) hydrogels through molecular-to-macroscopic hierarchical engineering. By pre-constructing an entangled network in a glycerol organogel and inducing the formation of borate ester bonds via solvent exchange, we establish hydrogels with a dual-reinforcement architecture: borate esterification disrupts crystalline domains and expands the polymeric network to enable good hydration (85.5-93.4 % water content) while synergizing dynamic bond reversibility with macromolecular entanglements for multiscale energy dissipation. The resultant hydrogels achieve skin-matched modulus (370 kPa), high tensile strength (4.3 MPa), toughness (27.2 MJ/m³) and extensibility (1447.9 % fracture strain), surpassing most of the reported water-rich hydrogels. Crucially, the hydrogel maintains stable ionic conductivity and biocompatibility, functioning as a conformal electrode that captures precisely electrocardiogram signals during vigorous physical activities. Therefore, this work provides a facile method for designing hydrogels that reconcile tissue-like functionality with engineered performance, holding implications for their practical applications in biomaterial fields.