Montmorillonite-Reinforced Acrylic Copolymer Adhesive for Robust Underwater Bonding via Bulk-Interfacial Adhesion Synergy.

Underwater adhesion is often compromised by interfacial hydration and insufficient bulk properties. Herein, a montmorillonite-reinforced poly (acrylic acid-co-butyl acrylate-co-2-phenoxyethyl acrylate) [P(AA-co-BA-co-PEA)/MMT] liquid adhesive was fabricated by one-pot free-radical polymerization. Solvent exchange and the balanced hydrophilic-hydrophobic composition facilitated hydration-layer displacement and intimate substrate contact, whereas MMT introduced additional physical interactions that restricted chain mobility and reinforced the adhesive bulk. The adhesive achieved underwater lap-shear strengths of 66.01-238.00 kPa on polypropylene, poly (vinyl chloride), polytetrafluoroethylene, wood, 304 stainless steel, and glass, representing improvements of 10.35-157.62% over the MMT-free adhesive. The highest strength, 238.00 ± 5.52 kPa, was obtained on 304 stainless steel. Moreover, the 180° peel strength increased by 23.90% to 107.76 ± 5.12 N m-1, while the swelling ratio decreased by 33.59% to 10.20 ± 1.09%. Rheological and thermal analyses further supported the MMT-induced enhancement of the adhesive bulk. This synergistic regulation of interfacial adhesion and composite reinforcement provides a simple route toward versatile liquid adhesives for robust underwater bonding.