A Highly Water-Resistant and Antibacterial Adhesive Coating for Marine Concrete Protection

The relentless degradation of marine concrete by chloride ingress and microbiologically influenced corrosion poses a critical challenge to the offshore infrastructure. Herein, we present an innovative solvent-free, in situ polymerized ternary copolymer adhesive coating, poly(hydroxyethyl methacrylate-<i>co</i>-butyl methacrylate-<i>co</i>-1-allyl-3-vinylimidazole chloride) (PHEMA-PBMA-P[AVIM]Cl), which consists of hydroxyethyl methacrylate (HEMA), butyl methacrylate (BMA), and a polymerizable ionic liquid monomer, 1-allyl-3-vinylimidazolium chloride ([AVIM]Cl). This coating is designed to provide multilevel protection for concrete in marine environments. The optimized terpolymer coating exhibits exceptional adhesion strength (1.82 MPa), surpassing conventional epoxy, maintained after prolonged immersion. It also demonstrates antibacterial efficacy, achieving a 75% bactericidal rate and a 15 mm inhibition zone against sulfur-oxidizing bacteria. Crucially, this coating significantly impedes chloride penetration (<200 C) and suppresses acid-induced corrosion, markedly reducing electrical flux and preserving mechanical integrity during long-term exposure. This molecular design offers a scalable, high-performance material strategy for durable marine concrete systems.