Supramolecular Velcro for Reversible Underwater Adhesion

Abstract

Underwater adhesion is a challenging task for most synthetic adhesives. Efforts to overcome this challenge have largely focused on modifying natural molecules produced by marine organisms such as mussels, sandcastle worms, barnacles, and sea urchins.[1–4] In particular, the adhesive 3,4-dihydroxy-l- phenylalanine (DOPA) residue found in proteins secreted by mussels has been a popular inspiration for several synthetic underwater adhesives.[5–7] Although such biomimetic approaches can be powerful, synthetic materials that are able to achieve a similar function using orthogonal methods could be valuable alternatives. For example, most DOPA- based adhesives require curing agents that irreversibly cross- link the residues to the surfaces.[8, 9] Efforts to achieve reversibility have largely been limited to the microscopic level.[10] We thus decided to investigate whether a synthetic system entirely unrelated to DOPA could achieve underwater adhesion and potentially overcome limitations, such as the lack of reversibility at the macroscopic level.