WATER-SOLUBLE POLY(ANILINE-CO-O-ANTHRANILIC ACID) COPOLYMERS

Poly(aniline-co-o-anthranilic acid (PAA) copolymers which are soluble in aqueous alkaline solutions and in some organic solvents were obtained from the chemical polymerization of aniline and o-anthranilic acid. The copolymers have MWs ranging from 84K to 126K depending on the composition. The copolymers are recovered in the oxidized state and have a strong EPR signal. The FTIR and UV-visible spectra indicated that the anthranilic acid groups restrict the pi-conjugation along the polymer chain. The electrical conductivity of the PAA copolymers decreases dramatically along the series from the polyaniline value of 5.2 S/cm to the poly(o-anthranilic acid) value of 10(-8) S/cm. Films of the PAA copolymers on a platinum foil can be oxidized and reduced at potentials between 0.0 and 1.0 V vs the Ag/AgCl reference electrode when immersed in 1.2 M HCl. The waves in the voltammogram for the stepwise oxidation of the polymer which are normally observed with polyaniline become merged into a single broad wave with the incorporation of the anthranilic acid. The films exhibited multiple color changes from clear yellow to green to dark brown during the redox process. Poly(o-anthranilic acid) itself is fairly inactive, revealing little or no electrical conductivity and electroactivity.