Electrochemical copolymerization of aniline and azure B

The electrochemical copolymerization of aniline and N,N,N'-trimethylthionin (azure B) in aqueous solutions has been carried out using the potential sw eep method. The optimum conditions for the coelectrodeposition are that the pH value and the temperature of the electrolytic solution are controlled a t 5.57 and 30 degreesC, respectively, and the scan potential range is set b etween -0.25 and 1.10 V (versus SCE). The copolymerization rate of aniline and azure B is about 3 times larger than that of aniline in the absence of azure B. The copolymerization of aniline and azure B was verified from the results of visible spectra during electrolysis, FTIR spectra and the atomic force microscopy (AFM) images of the polymers. The in situ visible spectru m for the electrolysis of the solution containing aniline and azure B is di fferent from that of the respective aniline and azure B. The FTIR spectrum of the copolymer is not a superposition of that of polyaniline and poly(azu re B). The AFM image of the copolymer is different from those of polyanilin e and poly(azure B) and is not a mixture of individual polymers. The conduc tivity of the copolymer synthesized at pH 5.57 is four orders of magnitude higher than that of polyaniline synthesized under the same conditions, but in the absence of azure B. The electrochemical properties of the copolymer are mainly attributed to polyaniline, but the copolymer has a better electr ochemical reversibility and a much faster charge transfer than those of pol yaniline.