A conjugated polymer network approach to anticorrosion coatings: Poly(vinylcarbazole) electrodeposition

The fabrication and characterization of poly(vinylcarbazole) (PVK)-conjugated polymer network (CPN) anticorrosion coatings on flat surfaces, steel coupons or indium tin oxide (ITO) glass substrates, is reported. Electrochemical deposition methods (potentiostatic and potentiodynamic) were employed by anodic oxidation of the carbazole side units in the PVK chains, resulting in electrodeposition of a cross-linked or network macromolecular structure. This is different from traditional conjugated polymer (CP) coatings made up of mostly linear species derived from direct electropolymerization of small molecule monomers. The coating composition was characterized by attenuated total reflection infrared spectroscopy (ATR-IR) and photoelectron spectroscopy (XPS). Atomic force microscopy (AFM) allowed morphological comparison between the coatings in terms of deposition technique and surface roughness. Electrochemical impedance spectroscopy (EIS) was subsequently carried out on PVK-coated steel coupons to evaluate the performance of such coatings in an accelerated corrosion environment. The deviation from the ideal (i.e., perfectly dielectric) capacitor-like behavior and Bode plot data suggested that the CPN approach of electrodeposited PVK coatings resulted in very good protection against weathering of engineering metals.