Wet adhesion enhancement through citric-acid-regulated supramolecular network

Adhesion on wet surface is of significance but remains challenging. Despite large steps forward in wet adhesives, they suffer from complicated preparation procedures and unbalanced properties. Herein, we develop a simple one-pot approach to fabricate a supramolecular adhesive with simultaneous enhancement in wet adhesion and mechanical toughness, which is achieved via citric acid (CA)-regulated supramolecular network of N-hydroxy succinimide (NHS) grafted polyacrylic acid chain and gelatin. CA not only reinforces supramolecular network by forming abundant hydrogen bonds, but also repels the NHS groups exposed outward to increase the opportunity for bonding with the target surface. The resultant adhesive shows fast and robust wet adhesion, high mechanical strength and elongation, as well as good biocompatibility. Such features enable the resultant adhesive with high potential in a variety of biomedical settings, such as tissue adhesion, sealant, and skin-adhesive strain sensor. This study opens a new avenue for the development of advanced bioadhesives, holding broad clinical application prospects.