Insulating organic coatings by electropolymerization of heterocyclic corrosion inhibitors

The feasibility of anodic electropolymerization of 2-mercaptobenzimidazole (2-MBI) and 2-hydroxybenzothiazole (2-OHBT) was demonstrated on Pt, Cu and Fe electrodes in methanol or water-methanol alkaline solutions. With 2-MBI, thick powdery and poorly adherent coatings were obtained limiting its interest as a protective coating. With 2-OHBT, thin (<0.1 μm) adherent coatings were obtained motivating an electrochemical estimate of their corrosion resistance in NaCl (3%) solution. These results were explained considering the greater tendency to formation of insoluble dimeric products with 2-MBI compared with 2-OHBT.