Photoelectrochemical and spectroscopic studies of sulfonated polyanilines .2. Copolymers of orthanilic acid and substituted anilines

Copolymerization of orthanilic acid (o-aminobenzenesulfonic acid) with m-methylaniline (m-toluidine) on a platinum electrode led to the formation of conducting films of a sulfonated poly(methylaniline). Anodic photocurrents for the conducting copolymer were seen in response to a light-flash perturbation on a millisecond time scale, allowing a partial conductivity phase diagram to be constructed. The profile was similar to that obtained for sulfonated polyaniline, but with a smaller conductive range (0.25 V) at any particular pH value. Only a thin insulating layer was produced by copolymerization of orthanilic acid with either o-methoxyaniline or o-ethoxyaniline. The structure of the copolymers was further investigated using X-ray photoelectron spectroscopy and in situ Raman spectroscopy (514 nm excitation).