Photoelectrochemistry and spectroscopy of substituted polyanilines

The properties of four substituted polyanilines, poly(N-methylaniline), pol y(m-methylaniline), poly(o-methoxyaniline), and poly(o-ethoxyaniline) have been examined by photoelectrochemical and spectroscopic techniques (Raman a nd XPS). The middle peak in cyclic voltammograms for poly(N-methylaniline) was ascribed to hydrolysis products such as benzoquinone, and in the case o f poly(o-methoxyaniline) to branched forms. The photocurrent profiles of th e substituted polyanilines resembled those of polyaniline to a large extent , with prolonged cathodic and anodic photocurrents given for the polymer in a state of high conductivity. With poly(o-ethoxyaniline) only short-lived photocurrents were obtained pointing to a more highly insulating material, also shown by the limited growth of this polymer. Raman spectra of the subs tituted polyanilines taken in situ revealed typical polyaniline Raman bands , while the largest shift in the nu(CN) band (35 cm(-1)) occurred with poly (N-methylaniline). A deconvolution of the N Is signal in XPS scans showed n itrogens consistent with oxidised forms of the polymers: a high proportion of positively charged nitrogens for poly(N-methylaniline) and of imine nitr ogens for poly(m-methylaniline). (C) 1999 Elsevier Science S.A. All rights reserved.