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

Abstract 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.