Modification of Surface-Oxidized Copper Alloy by Coupling of Viologens for Inhibiting Microbiologically Influenced Corrosion

Microbiologically influenced corrosion (MIC) is extremely harmful to maritime industries and to the environment. A surface modification technique was developed in this work to impart antibacterial and corrosion-inhibition properties onto the surface-oxidized alloy to inhibit MIC. Thus, 4-(chloromethyl)phenyl tricholorosilane was first immobilized on the oxidized metal surface to allow the coupling of -bipyridine to the methyl-chloride groups. Subsequently quaternization by benzyl chloride converted the terminal pyridine groups into pyridinium groups. The success of each functionalization step was ascertained by X-ray photoelectron spectroscopy, atomic force microscopy, and static water contact angle measurement. The quaternized viologen moieties exhibited good bacterial inhibition efficiency at the initial stages of exposure to a seawater-based medium containing aerobic bacteria belonging to the genera Pseudomonas , as revealed by scanning electron microscopy images. The corrosion-inhibition properties of the organic layer were verified by Tafel polarization curves, cyclic polarization curves, and electrochemical impedance spectroscopy. In comparison, the pristine alloy was readily susceptible to MIC in the same medium and under the same conditions.