Recyclable High-Performance Underwater Adhesives Inspired by “Spider Web” Geometric Structure

Underwater adhesion achieved through biomimetic strategies is one of the mainstream directions in scientific research. Furthermore, maintaining effective adhesion over extended periods and in various aqueous environments remains a significant scientific problem. Here, inspired by the bonding mechanism of mussels, a biomass adhesive was developed using biomass caffeic acid with a catechol structure and branched polyamines. Based on this, the structure of the adhesive was tuned by using benzene-1,4-diboronic acid to further bridge the polymers and form a spider web-like polymer network. A biobased underwater adhesive with alkali resistance and high performance was conveniently prepared. It can achieve adequate adhesion to various hydrophilic and hydrophobic substrates in different water environments, such as strong alkali and seawater. The strength of the bonded steel substrates can reach 608.2 kPa after immersion in water for 2 weeks. Furthermore, the biobased underwater adhesive exhibits specific recyclable adhesive properties via the reversible borate ester bonds, which reduces resource consumption and promotes sustainable development. This work prepared an alkali-resistant and high-performance biobased underwater adhesive based on the adhesion mechanism of mussels and the geometrical structure of spider webs. The underwater adhesion was achieved by simulating mussels, and the performance enhancement was achieved by simulating the spider web geometric structure, which provides a new idea for underwater adhesion.