A High-Strength Phase-Separated Underwater Adhesive with Self-Reinforcement in Dynamic Water

Adhesives with excellent adhesion properties are crucial for aquatic activities. However, natural dynamic water can lead to the loss of adhesive molecules and a reduction in adhesion strength. In this work, we propose a unique phase-separated underwater adhesive through the copolymerization of hydrophilic and hydrophobic monomers. The hydrophobic groups repel interfacial water, while the hydrophilic groups form strong bonds with substrates, endowing the adhesive with outstanding adhesion. Moreover, the adhesive exhibits unique self-reinforcing properties in dynamic water. The self-reinforcement is realized through dynamic water-accelerated phase separation kinetics of the adhesive. The dynamic water forms a dense surface of adhesive, reducing adhesive loss and increasing the bonding area. The adhesion strength in dynamic water significantly increases, reaching 1.97-fold of that in static water. In addition, the adhesive demonstrates excellent adaptability and maintains strong adhesion in various water environments. Benefiting from its linear structure and good solubility, the adhesive exhibits recyclability and erasability, which promotes sustainable chemistry and utility. The recycled adhesive retains 95% of its original adhesive strength without obvious damage. The adhesive demonstrates practicality and accessibility in applications such as tube repair and leakage sealing. Overall, this work provides insights into the design and preparation of novel self-reinforcing underwater adhesives.