Enhanced electrochromic stability of polyaniline in polyaniline‐matrix polymer composite films in aprotic medium

Abstract

Abstract Electrochromic behavior and stability in aprotic medium of polyaniline composite films prepared by chemical oxidative polymerization at gas/liquid interface were investigated. The results are compared with chemically and electrochemically snythesized polyaniline homogeneous films. The polyaniline composite films show almost the same electrochromic behavior as the homogeneous films. The behavior is due to a two‐step oxidation mechanism, which is different from that in aqueous medium, especially in the second oxidation process. Degradation of polyaniline in aprotic medium is due to the partial formation of the electrochemically inactive quinonediimine structure in the higher oxidized state. The degradation is restrained by hybridization with an appropriate matrix polymer. The stabilization of the electrochromic behavior of polyaniline depends on molecular weight and pK a of the matrix polymer.