Ionic weaving network enables mechanically robust smart hydrogels with anti-swelling and anti-freezing capabilities

Stretchable hydrogels hold great promise in cutting-edge fields such as flexible sensing and soft robotics. However, the poor mechanical properties and environmental intolerance restrict their practical applications in intelligent integrated systems. Herein, we construct ionic weaving hydrogels (IWHs) by pre-arranging polymer chains through force-induced restrictive drying, followed by the introduction of metal ions to form a 3D topological network with uniformly distributed dynamic coordination. This design dissipates energy through the synchronous dissociation of massive coordination bonds, yielding the hydrogel with high strength, high modulus, and excellent toughness. Additionally, the strong topological constraints impart excellent anti-swelling and anti-freezing capabilities, as well as dehydration-rehydration activation characteristics. Consequently, the IWH enables not only stable underwater sensing but also integrated actuation-sensing functions through solvent stimulation. Moreover, when processed by 3D printing, it achieves spatiotemporally programmable actuation while simultaneously monitoring the response process in real time. This work demonstrates an intelligent 4D printing platform that seamlessly integrates complex structures, actuation, and self-sensing, thereby opening an avenue for designing next-generation multifunctional smart hydrogels and soft material systems.