Intrinsically Reversible Superglues via Shape Adaptation Inspired by Snail Epiphragm

We often meet with this dilemma: material’s adhesion could be strong but not reversible, or it is reversible but not strong. The Yang lab discovered that hydrogel made from polyhydroxyethylmethacrylate (PHEMA) had unusual adhesive properties akin to that of the snail’s epiphragm: PHEMA was rubbery when wet but rigid when dry.  When wet, PHEMA conforms to the small grooves on a surface, which allows the material to stick to a surface. When it dries: It becomes as rigid as a plastic bottle cap, but, uniquely, doesn’t shrink. Instead, PHEMA fastens itself securely to the surface like super glue. When it is rewetted, it slips off effortlessly.