Particle-Reinforced High-Performance Low-Cost Adhesive for Underwater Applications

Underwater adhesives serve as essential functional materials with extensive applications in underwater robotic operations, submarine pipeline installation and maintenance, maritime defense projects, and marine engineering infrastructure. However, the construction of robust and reliable underwater bonding interfaces is severely constrained by substrate surface hydration layers and limited interfacial interaction strength, which has become a core bottleneck restricting the development of high-performance underwater adhesives. Herein, we use in situ polymerization and particle reinforcement to enhance adhesion strength: An underwater adhesive is prepared by reacting bis(3-aminopropyl)-terminated polydimethylsiloxane with hexamethylene diisocyanate in the presence of Ca(OH)2, which acts as a precursor of reinforcing CaCO3 particles. Such particle reinforcement effectively hinders crack propagation and enhances structural integrity, which can significantly enhance the bonding strength. The adhesive is fully underwater-curable, demonstrates strong reliable adhesion to diverse substrates including iron, glass, polyethylene terephthalate (PET), and polytetrafluoroethylene (PTFE), and complies with general application requirements. Among the tested substrates, polyethylene terephthalate is bonded most strongly, with its maximum underwater adhesion strength reaching 817 kPa. Furthermore, Rheological characterizations validate its favorable processing stability and tunable viscoelastic properties. Thus, this work provides important theoretical and practical insights for the development of high-performance underwater adhesives, and exhibits promising application prospects in marine engineering and underwater equipment fields.