A versatile dopamine-induced intermediate layer for polyether imides (PEI) deposition on magnesium to render robust and high inhibition performance

Dopamine (DA), with strong adhesion to metal substrate via self-polymerization reaction, was introduced as a versatile template layer for subsequent polyether imide (PEI) deposition to confer a highly robust coating on AZ31 magnesium alloy. The complicated corrosion behaviour of the coating was disclosed and investigated by employing electrochemical impedance spectroscopy (EIS) coupled with equivalent electrical circuits (EECs) analysis. The results showed that the hybrid PEI/PDA coating exhibited evidently higher retardation performance (up to 35 days) after immersing in 3.5 wt.% NaCl solution compared to PDA or PEI coated Mg.