Electrochemical behavior of mild steel coated by polyaniline doped with organic sulfonic acids

A comparison of electrochemical behavior was made of coatings of pure undop ed PANI cast from solution and this coating after doping as a film on the s ubstrate. These were also compared to coatings of pure PANI/sulfonic acids adducts formed from the outset in the doped state through casting from xyle ne or chloroform solutions. The results obtained allowed to assume that the formation of protective iron oxide layers occurs mainly during the coating of pure undoped PANI (emeraldine base). During the doping stage a modifica tion of these layers obviously proceeds leading to a change of the corrosio n currents of the whole coating system. As a consequence, the formation of pure doped PANI coatings by casting doped PANI from solutions cannot give a s good of results as does the two stage process. (C) 1999 Elsevier Science S.A. All rights reserved.