Sticky when wet: Understanding the chemistry of strong adhesion

From duct tape to Post-it notes, we all use adhesives on a daily basis. And we all know how frustrating it can be when our adhesives don’t work—dirty or wet surfaces are often serious annoyances. While we’ve mastered the art of formulating an adhesive that remains sticky in air, most synthetic polymers cannot maintain their adhesive properties when wet. Water disrupts adhesion by forming layers on polar surfaces that inhibit contact between the surface and the adhesive.

But just because we haven’t made adhesives that consistently work well in water doesn’t mean they don’t exist. Recently, scientists have discovered the chemical mechanism that allows some marine organisms to adhere to wet surfaces, and this could prove useful for designing the next generation of synthetic adhesives.

Marine organisms are able to maintain their adhesion under extreme conditions where synthetic analogs generally fail. And recent investigations into mussel adhesion have provided us with a better understanding of why they stick so well under water. Scientists found a mussel that produces 15 adhesive mussel foot proteins (called mfps). During the adhesive process, two proteins in particular (mfp-3 and mfp-5) act as a primer on a target surface, preparing it so that other mfps can adhere.