Scalable Underwater Adhesives with High-Strength, Long-Term, and Harsh-Environment Adhesion Enabled by Heterocyclic Chemistry

Developing scalable and high-performance underwater adhesivesisimportant in various biomedical and industrial applications. However,despite massive efforts, the realization of such adhesives remainsa challenging task, as mainly imposed by the difficulty in balancingthe interfacial and bulk properties via an efficient way. Here, wereport a facile yet effective strategy to construct a novel underwateradhesive with multiple advantaged performances by virtue of heterocyclicchemistry. This adhesive is designed with the cooperation of a heterocycle-basedversatile adhesive functionality and an eco-friendly hydrophilic matrixwith cross-linkable sites, which allows water absorption to destroyhydration layer, diverse molecular interactions to enhance interfacialadhesion, and abundant covalent crosslinks to strengthen bulk cohesion.Such a rational design endows the adhesive with strong underwateradhesion (up to 1.16 MPa for wood and 0.36 MPa for poly(tetrafluoroethylene)(PTFE)), long-term durability (maintaining pristine strength evenafter 4 months), and harsh-environment stability (salt, acidic/alkaline,low/high-temperature solutions). This strategy is also generic toderive more adhesive formulas, which offers a new direction for designingthe next-generation underwater adhesives with high performance andscalability for practical applications.