A Curable Underwater Adhesive Based on Poly(propylene oxide) and Tannic Acid Coacervate

Coacervation of poly(propylene oxide) and tannic acid, driven by hydrogen bonding, renders a tacky viscous material that provides an underwater adhesion strength of ∼350–550 kPa on aluminum substrates and also can bond other wet surfaces such as glass, metal, plastic, and porcelain. A curing functionality is achieved by designing a two-component system, using epoxidized poly(propylene oxide)/tannic acid coacervate as part A and amine-terminated poly(propylene oxide) as part B. Aside from underwater bonding, this adhesive can cure underwater through amine-epoxide reactions providing a commercially competitive and waterproof bonding.