High strength, self-activating ability and fast adhesion of polyurethane adhesives based on rosin structure in different environments.

Underwater adhesives hold significant relevance in daily life and applications. Despite great efforts, the development of high-performance underwater adhesives through a simple and effective method remains a difficult challenge. Herein, a high adhesion and environmentally stable polyurethane underwater adhesive (DAP-PU) was developed based on rosin with a hydrogenated phenanthrene ring skeleton to design hydrophobic domains, and combined with multi-strength hydrogen bonding interactions to construct "polar hydrophobic domains". DAP-PU exhibits a strong underwater bonding and adhesion performance on various substrates (steel, aluminum, PMMA and glass) in harsh aqueous conditions (1 M NaCl, pH 5 and seawater), with the highest peel and shear strengths on stainless steel substrates reaching 12.88 N cm^-1 and 1.7 MPa, respectively. In addition, DAP-PU can be used in various fields such as underwater sand consolidation, underwater sealing and repair.