Strong Underwater Supramolecular Adhesives via Fluorinated Ionic Liquids

Abstract Underwater adhesion plays a vital role in various fields, e.g., underwater labeling or coating, underwater actuators and surgery. However, it is a big challenge to design underwater adhesives with high adhesion and durability, especially for burgeoning supramolecular adhesives due to their dynamic nature. Herein, ionic liquids (ILs) are explored as underwater adhesives directly via a fluorinated and branched modification strategy. The subsequent self‐assembly of these ILs promotes the formation of robust hydrophobic supramolecular polymeric networks, thus effectively driving both high cohesion and outstanding underwater interfacial adhesion. Owing to this strategy, the IL‐based supramolecular aggregates can obtain high‐performance underwater adhesion strength (up to 4.11 MPa) as well as great cyclability. The IL‐based adhesives further showcase that they can benefit the assembly of hydrogel units for achieving diverse shapes. More importantly, the molecular mechanism is elucidated underlying the underwater adhesion of the fluorinated analogs. These fundamental understandings open the door to the design of functional IL‐based adhesives while facilitating high‐performance underwater supramolecular adhesive materials.