Robust, Reusable, and Antioxidative Supramolecular Adhesive to Inorganic Surfaces Based on Water-Stimulated Hydrogen Bonding

Reusable adhesives able to bond and debond to a surface as needed in response to stimuli are eagerly sought. Despite recent advances in catechol-derived adhesives, achieving strong and switchable adhesion persists as a challenge because easy catechol-to-quinone oxidation invariably reduces the adhesive catechol units which induce the formation of irreversible cross-linked networks. For this study, a supramolecular adhesive carrying a hydrophobic tetramethylcyclotetrasiloxane (TMCS) core surrounded by hydrophilic groups including four peripheral catechol groups (Cat) and four carboxyl groups (CGs) was demonstrated to have good oxidation resistance and strong and reusable adhesion to inorganic surfaces upon contacting water. The hydrophobic TMCS core supplied a hydrophobic environment for oxidation resistance. Once water was added to the materials, TMCS expelled water to expose more catechol units outward for sufficient contact with the substrate surface. The supramolecule was found to have a remarkably high complex viscosity of up to 2.6 × 108 mPa·s at 1 Hz, which is 105 times that of the TMCS core. These unique properties make the supramolecular material a promising candidate for extensive applications such as marine adhesives.