Electrochemical characteristics of copolymers electrochemically synthesized from N-methylpyrrole and 3,4-ethylenedioxythiophene on steel electrodes: Comparison with homopolymers

Copolymers of N-methylpyrrole and 3,4-ethylenedioxythiophene have been prepared electrochemically using monomer mixtures with various concentration ratios. Copolymers were generated on stainless electrodes by chronoamperometry in acetonitrile with LiClO4. Elemental analyses indicated that the amount of N-methylpyrrole in the copolymers was higher than in the generation media, this feature being explained by the diffusion coefficients determined for the two monomers. On the other hand, the electrochemical properties and the doping level of the copolymers have examined and compared with those of the two corresponding homopolymers, which were prepared using the same electrochemical procedure. It has been found that the electroactivity of the copolymers decreases when the concentration of N-methylpyrrole increases, even although the two homopolymers present both electrochemical stability and a quasi-reversible redox pair. On the other hand, the doping level of the homopolymers was higher than that of the copolymers suggesting that the interaction between the monomers during the copolymerization procedure hinders the incorporation of counterions to the molecular chains.