Robust Underwater Adhesion of Catechol‐Functionalized Polymer Triggered by Water Exchange

Adhesives with strong and stable underwater adhesion performance play a critical role in industrial and biomedical fields. However, achieving strong underwater adhesion, especially in flowing aqueous and blood environments, remains challenging. In this work, a novel solvent-exchange-triggered adhesive of catechol-functionalized polyethylenimine ethoxylated is presented. The authors show that the dimethyl sulfoxide (DMSO) solution of the catechol-functionalized polymer can be directly applied to various substrates and exhibits robust dry/underwater adhesion performance induced through in situ liquid-to-solid phase transition triggered by water-DMSO solvent exchange. The adhesive can even strongly bond low-surface-energy substrates (e.g., > 86 kPa for polytetrafluoroethylene) in diverse environments, including deionized water, air, phosphate-buffered saline solution, seawater, and aqueous conditions with different pH values. Moreover, the adhesive exhibits strong adhesion to biological tissues and can be used as a hemostatic sealant to prevent bleeding from arteries and severe trauma to the viscera. The adhesives developed in this study with strong dry/underwater adhesion performance and excellent hemostatic capabilities display enormous application prospects in the biomedical fields.