Anodic Coating of 1.4622 Stainless Steel with Polydopamine by Repetitive Cyclic Voltammetry and Galvanostatic Deposition

Polydopamine exhibits high potential as coating of materials used for medical devices, antifouling, and corrosion prevention. Repetitive cyclic voltammetry on gold electrodes was used to deposit polydopamine by anodic oxidation. Investigation of polydopamine formation in the pH range 5–8 showed that coating at pH 6.5 permits selective polydopamine formation on the electrode, while auto-oxidation of dopamine in the electrolyte could be suppressed. The optimized conditions then were transferred to stainless steel electrodes. At pH 6.5–6.6, an anodic peak current density of 12.9 μA/mm2 was measured using a plane stainless steel anode in 5 mM dopamine solution. During experimental scale-up, anodic coating of 1.4622 steel plates in galvanostatic experiments led to formation of a colored polydopamine surface, which exhibited reduction of the water contact angle by 13.5°. The controlled anodic polydopamine formation is of a particular value for an economic polydopamine coating of the conductive material in larger-scale applications.