SYNTHESIS AND PROPERTIES OF NOVEL WATER-SOLUBLE CONDUCTING POLYANILINE COPOLYMERS

The chemical polymerization of aniline and sodium diphenylamine-4-sulf onate produces poly(aniline-co-N-(4-sulfophenyl)aniline) (PAPSA), copo lymers which have high molecular weights and are recovered as a dark g reen powder. The PAPSA copolymers have a monomer composition like the composition in the reaction mixture. They have conductivities which ra nge between the conductivities of the poly(N-(4-sulfophenyl)aniline) h omopolymer (0.0035 S/cm) and polyaniline (5.2 S/cm). While the homopol ymer poly(N-(4-sulfophenyl)aniline) is 103 times less conductive than polyaniline, it is still 10(6) times more conductive than other polyan iline polymers with sulfonate groups. The conductivity and the ESR sig nal both decrease with the phenylsulfonic acid content in the copolyme r. The PAPSA copolymers are soluble in aqueous NH4OH but not in aqueou s HCl solutions. The color of the resulting solutions varies with the copolymer monomer composition. Films of the PAPSA copolymers on an ele ctrode show two reversible redox reactions for the aniline units and o ne for the pendant phenylsulfonic acid groups between 0.2 and 0.8 V vs Ag/AgCl reference electrode, when immersed in aqueous acid solutions. During the redox process, the PAPSA films exhibit reversible color ch anges from pale yellow to green to dark blue.