Superior Impact‐Resistant Composite Hydrogels Through an Ionic Coupling Strategy

ABSTRACT Impact resistance emerges from the coupling of strong load‐bearing networks and dynamic interfacial interactions that enable effective stress transfer and energy dissipation. Although hydrogels are promising candidates for impact‐resistant soft materials, it remains challenging to reinforce both networks and interfaces simultaneously in hydrogels, which limits their performance under high strain‐rate loading. To overcome this limitation, we develop a composite hydrogel comprised of a poly(vinyl alcohol) (PVA) matrix reinforced with chitosan–sodium alginate nanofibers (CSNFs), using sodium citrate as a multifunctional ionic coupler that (i) strengthens the PVA matrix via the Hofmeister effect, (ii) reinforces the CSNF network through desolvation and electrostatic crosslinking, and (iii) improves their fiber–matrix interfaces, enabling efficient stress transfer and energy dissipation through the integrated composite network and layered microstructure. The composite hydrogel achieves superior impact resistance relative to high‐performance solid polymers, with an impact strength of 426.7 MPa and toughness of 106.4 MJ m ^{− 3} at 7000 s ^{− 1} , while retaining excellent tensile properties (tensile strength: 54.2 MPa; fracture strain: 590%). By molecular‐level experimental and simulation analyses, this work establishes ionic coupling as a facile yet effective strategy for achieving composite hydrogels with extreme impact resistance, broadening the potential of soft materials in impact protection, damping, and energy absorption.