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 form ation 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 parti al conductivity phase diagram to be constructed. The profile was simil ar to that obtained for sulfonated polyaniline, but with a smaller con ductive range (0.25 V) at any particular pH value. Only a thin insulat ing layer was produced by copolymerization of orthanilic acid with eit her o-methoxyaniline or o-ethoxyaniline. The structure of the copolyme rs was further investigated using X-ray photoelectron spectroscopy and in situ Raman spectroscopy (514 nm excitation).