Abstract
Three polyaniline (PANI)/poly(o-phenylenediamine) (PoPD) mixtures have been electrochemically deposited on a stainless steel surface from an acidic solution. Electrocopolymerization was favorable at high molar ratios of aniline to o-phenylenediamine, and the resulting copolymer is a random type. Two bilayers, PoPD/PANI and PANI/PoPD, were prepared by successive electrodeposition, during which different multiphase structures were obtained. The presence of PoPD with PANI in the copolymer or multilayer structures enhances the passivation of the SS. The bi-layer coating in which a PANI layer lies under the PoPD produced the best passive oxide on the SS. The resistance to pitting increases with the coating order as follows: PANI < copolymer a parts per thousand(a) PANI/PoPD < PoPD < PoPD/PANI.