A triple-shield strategy integrating conductive polymer, biocide, and binder against microbiologically influenced corrosion

Microbiologically influenced corrosion (MIC), predominantly caused by sulfate-reducing bacteria (SRB), is a significant cause of metal degradation. Although conductive polymers and bactericidal metal oxide composites have been studied for their applications in mitigating metal corrosion and providing antibacterial effects, composite anti-corrosion strategies that integrate corrosion resistance with the mechanical durability essential for practical use, especially for protection against SRB, still hold significant potential for development. In this study, a poly(o-toluidine)/nano-CuO/epoxy resin (POT/CuO/EP) composite coating was developed for carbon steel to address these challenges. The coating synergistically combines POT and CuO to provide both corrosion resistance and antibacterial action, while the epoxy matrix enhances adhesion and mechanical strength. Electrochemical and antibacterial tests conducted in a 3.5 % NaCl solution containing SRB demonstrated that the POT/CuO/EP composite coating exhibited the highest charge transfer resistance and the most effective suppression of SRB biofilm formation, achieving superior protection significantly outperforming single-component coatings. This performance is attributed to the combined action of POT-induced passivation and the synergistic antibacterial effect of POT’s N+ and Cu2+. By uniting multifunctional anticorrosion mechanisms with enhanced mechanical properties, this study proposes a promising strategy for protecting metals in marine environments.