Robust, Switchable and Printable Underwater Adhesives Based on a Temperature‐Deactivated Design

Abstract Conventional adhesives generally suffer from diminished adhesion in aqueous environments, posing significant challenges for their application in wet and submerged conditions. While extensive research efforts are directed toward enhancing the interfacial bonding, cohesive strength, and durability of adhesives in such environments, most existing underwater adhesives remain static and irreversible. This limitation hinders their reusability and often results in undesirable residues. Addressing the challenge of achieving strong underwater adhesion with on‐demand detachment remains crucial. This study introduces the development of temperature‐responsive underwater adhesives that demonstrate outstanding bonding strength, reversibility, and durability. Through the strategic integration of interfacial bonding, reinforced cross‐linking networks, dynamic hydrogen bonds, and upper critical solution temperature (UCST)‐driven phase transitions, one of the few temperature‐deactivated adhesives is created. The optimized adhesive is distinguished by its performance to achieve underwater adhesion strengths exceeding 1.4 MPa, nearly 100% switching efficiency and residue‐free adherend under mild thermal cycling. Beyond the template‐assisted fabrication of adhesive patches, 3D printable adhesives are achieved with programmable architectures via direct ink‐writing. This work highlights the development of temperature‐deactivated underwater adhesives activated by UCST‐type phase transitions, not only boosting adhesion strengths and switching efficiencies across various water conditions but also broadening their applicability with user‐defined and application‐specific functions.