Abstract
The in situ ultraviolet-visible (UV-Vis) spectroelectrochemical study on the copolymerization of diphenylamine (DPA) and o-phenylenediamine (OPD) has been performed at a constant potential of 0.8 V using indium tin oxide (ITO)-coated glass electrodes as working electrode. And also, as a comparison, the electrochemical homopolymerizations of DPA and OPD have been investigated by using the in situ spectroelectrochemical technique. The intermediate species generated during the electrochemical homopoly-merization of DPA and OPD, and the copolymerization of DPA with OPD have been identified by using the in situ spectroelectrochemical procedure. The results reveal the formation of an intermediate in the initial stage of copolymerization through the cross-reaction of the cation radicals of DPA and OPD, and the absorption peak located at 538 nm in the UV–Vis spectra is assigned to this intermediate. To further investigate the copolymerization of DPA with OPD, cyclic voltammetry (CV) has been used to study the electrochemical homopolymerization of DPA and OPD and also the copolymerization of DPA and OPD with different concentration ratios in solution. The different voltammetric characteristics between the homopolymerization and copolymerization processes exhibit the occurrence of the copolymerization, and the difference between the copolymerization of DPA and OPD with different concentration ratios shows the dependence of the copoly-merization on the concentrations of DPA and OPD. The copolymer has also been characterized by Fourier transform infrared spectroscopy (FT-IR).
Highlights
Conducting polyaniline (PANI) has attracted significant attention owing to its environmental stability and its electrical, optical and electrochemical properties [1,2,3]
Gopalan et al [17,31,32,33,34] have used cyclic voltammetry (CV) and in situ UV-Vis spectroscopy to study the copolymerization of DPA with some aniline derivatives and explained the copolymer formation through a plausible mechanism
In the first cycle, an irreversible oxidation peak is observed at 0.49 V, which could be assigned to the electrooxidation of DPA to generate the diphenylamine cation radicals (DPACRs), and after the first potential scanning, another anodic peak was observed at 0.27 V
Summary
Conducting polyaniline (PANI) has attracted significant attention owing to its environmental stability and its electrical, optical and electrochemical properties [1,2,3]. The improved processability, electrochromism and other properties over PANI have been noticed for the polymers derived from the various benzene ring substituted and N-substituted aniline derivatives. This means that copolymerization can provide an alternative and easy approach to modify the structure of PANI, it becomes possible to tune the electrochemical and electronic properties by altering the conditions of copolymerization. Gopalan et al [17,31,32,33,34] have used CV and in situ UV-Vis spectroscopy to study the copolymerization of DPA with some aniline derivatives and explained the copolymer formation through a plausible mechanism. The obtained copolymer has been characterized by FT-IR spectroscopy
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