Interfacial‐Water‐Activated Hyperbranched Polyhedral Oligomeric Silsesquioxane (POSS) Adhesives via Entropy‐Driven Molecular Rearrangement

ABSTRACT

Transforming interfacial water from a detrimental factor into an active contributor to adhesion remains largely unexplored. Herein, we report an entropy‐driven, interfacial‐water‐activated hyperbranched polyhedral oligomeric silsesquioxane (POSS) adhesive that simultaneously enhances interfacial adhesion and bulk cohesion through cooperative molecular rearrangement. The adhesive integrates rigid hydrophobic POSS cages, flexible hydrophilic segments, and catechol adhesive groups within one molecular architecture. Upon exposure to a small amount of interfacial water, the hydrated interface promotes the outward migration and enrichment of hydrophilic segments and catechol moieties, thereby increasing the density of exposed adhesive groups at the bonding interface. Meanwhile, the hydrophobic POSS cages undergo inward contraction and self‐aggregation to form compact internal domains, reinforcing the cohesive phase of the adhesive. This coupled “interfacial activation‐cohesion reinforcement” mechanism converts interfacial water from an adhesion barrier into a functional trigger, enabling stronger bonding on water‐bearing interfaces than under dry conditions. The resulting POSS‐based hyperbranched adhesive exhibits broad substrate adaptability, reliable bonding on wet, rough, and dusty surfaces, and long‐term durability over 30 days. This work presents a distinct molecular design principle for wet‐surface adhesives by exploiting environmental water as an active driving force, offering opportunities for heavy‐duty structural bonding and repair of damaged materials under complex conditions.