In situ synthesized Cu2O intercalated bentonite nanocomposite with controlled release for enhanced marine antifouling performance

Abstract

Conventional copper based antifouling coatings suffer from a “burst release” of biocides, which significantly reduces their service life and increases environmental toxicity. Herein, we designed and synthesized an innovative composite antifoulant, Cu₂O@bentonite, through the in situ intercalation of Cu₂O nanoparticles within the lamellar structure of organo-modified bentonite. When integrated into an acrylic self-polishing copolymer, this composite exhibited a novel “ion buffering” mechanism, attributed to the inherent cation exchange capacity of the bentonite matrix, which effectively reduced the initial 24 h burst release by over 76% and promoted a sustained, long-term release profile. This controlled release mechanism enhanced the coating's biocidal efficacy, achieving over 99% effectiveness against marine bacteria and over 90% against algae in laboratory tests. Notably, after 120 days of exposure to real-sea fouling conditions, the coating maintained a clean surface, largely free of macrofouling, thereby demonstrating significantly superior performance compared to traditional Cu₂O-based coatings. Moreover, the integration of the nanocomposite significantly improved the coating's adhesion, hardness, and impact resistance, thereby enhancing its overall durability. This study presents an efficient and reliable methodology for developing advanced biocidal reservoirs, offering a novel and viable strategy for designing high-performance marine antifouling coatings with prolonged service life and a more environmentally benign release profile.