Electrochemistry of Conductive Polymers VIII: In Situ Spectroelectrochemical Studies of Polyaniline Growth Mechanisms

The earlier stage of the polymerization reaction of polyaniline has been studied employing in situ spectroelectrochemical techniques. The results indicate that the nitrene cation appears to be a key intermediate species, which leads to all three possible dimers including a head‐to‐tail dimer (N‐phenyl‐p‐phenylenediamine), a tail‐to‐tail dimer (benzidine), and a head‐to‐head dimer (hydrazobenzene). The oxidized forms of these dimers were all shown to be capable of growing polyaniline in the presence of aniline, even though aniline was not oxidized. The cyclic voltammetric peaks observed during the PA synthesis in the middle potential regions were shown to arise from the redox reactions of these dimers, oligomers, and degradation products of polyaniline including quinoneimines and p‐benzoquinone.