Spatially confined hydration for robust underwater adhesion
Gang Lü, Rui Ma, Jian Lü, Yuanhao Chang, Ming Li, Eduardo Saiz
Abstract
Underwater adhesion has long been limited by interfacial water's paradoxical role as both bonding mediator and failure initiator. We present a confined hydration adhesive tape (CHAT) that harnesses water as a molecular architect through spatial hydration management. By confining water penetration to sub-8-micrometer depths, we create a dynamic interface where hydration-activated hydrogen bonds enable adaptive, high-density interfacial connections, and hydrophobic nanodomains maintain bulk integrity via entropic water exclusion. This orchestrated hydration yields an interfacial toughness of 6 kilojoules per square meter (>1.8× literature benchmarks; 1.4 to 3.8× commercial tapes), while preserving stability across harsh conditions (pH 1 and 13, 3.5% saline). Multiscale experiments and simulations reveal water's triple role as a hydrogen bond catalyst at the interface, a dynamical reorganizer of supramolecular networks, and a mechanical decoupler of interfacial adhesion/bulk cohesion. By establishing interfacial water as a design variable rather than a compromise, CHAT opens avenues for marine, biomedical, and industrial applications where water-resistant adhesion is critical.