Supramolecular Semi-Interpenetrating Polymer Network for Robust Underwater Adhesion

Achieving efficient underwater adhesion has been a long-standing challenge, as the surface hydration layer impedes the adhesive contact with substrates. To address this issue, we have developed a supramolecular semi-interpenetrating polymer network (SsIPN) for pressure-sensitive adhesive (PSA) applications. The SsIPN combines poly­(butyl acrylate)-based copolymers as both linear polymer chains and a cross-linked network. The linear polymer, acting as a fluid, effectively diffuses to repel the hydration layer, while the cross-linked network provides cohesion through chain entanglement and structural integrity. Both components feature hydrogen bonding, which not only enhances intermolecular interactions with substrates but also acts as sacrificial bonds within the gels. As a result, SsIPN tapes demonstrate outstanding water-repellent properties and underwater adhesion, achieving an adhesion strength of over 2000 N/m on glass substrates. Moreover, even after 72 h of underwater storage, the adhesive retains a peel strength of 1243 N/m due to its hydrophobic nature. This simple, robust method for producing SsIPN offers a promising approach to developing high-performance underwater adhesives.