Comparisons of charge compensation process in aqueous media of polyanilineand self-doped polyanilines

This work describes comparisons between the redox behavior of electrochemic ally formed polyaniline (PANI) and two chemically obtained self-doped polya nilines: sulfonated polyaniline (SPAN) and poly-(aniline-co-N-propanesulfon ic acid-aniline) (PAPSAH). The charge compensation processes in HCl and cam phorsulfonic acid (HCSA) aqueous solutions were studied using simultaneous cyclic voltammetry and electrochemical quartz crystal microbalance techniqu es. Film electroactivity decreases in the PANI much greater than SPAN > PAP SAH sequence in HCl solution. Charge compensation is carried out mainly wit h proton participation in SPAN modified electrode in both HCl and HCSA solu tions. In contrast, for PANI and PAPSAH, the participation of anions also o ccurs, with a contribution strongly dependent on anion size. These results were analyzed in terms of the acid/base equilibrium of the polymer chains. (C) 2001 Elsevier Science B.V. All rights reserved.