Universal tough hydrogel glue based on dual post-crosslinking strategy of the double network structure

Inspired by the robust interfacial adhesion in nature, researchers have hoped to develop hydrogel glues or adhesives with application potentials in medicine and engineering. However, the diverse mechanical (soft, hard, and stretchable) and compositional properties (micro/macro-porous, or non-porous) of the general solids make it complicated for developing universal hydrogel glues, particularly concerning the issues in adhesion and interfacial compatibility. Here, we propose a hydrogel glue with a novel curing strategy of dual post-crosslinking for the double-network, which means both chemical and physical networks are formed after applying glue to target surfaces. The cured hydrogel exhibits excellent transparency (> 94%) and stretchability (areal ratio > 1000%). It demonstrates outstanding repair capabilities for both soft and hard substrates, bonding fractured pork bones with a maximum adhesive strength of ~ 1 MPa. The hydrogel glue shows strong adhesion on both porous and non-porous substrates, with maximum adhesion energy exceeding 1800 J·m⁻². As a multifunctional coating, hydrogel glue features excellent lubricity and stability, making it suitable for large-scale production. The glue provides excellent conformability when applied to elastic substrates, and the coating is ideal for mass production of protective and elastic coatings for medical devices and other targets in fields of engineering and medicine.