Cooperative doping in polyaniline-poly(ethylene-3,4-dioxythiophene): poly(styrenesulfonic acid) composite system

Interaction of emeraldine base of polyaniline (PANI) and poly(ethylene-3,4-dioxythiophene): poly(styrenesulfonic acid) (PEDOT:PSS) in a complex solution is shown to lead to a new polymer complex whose components act to each other to favor an increase in intramolecular conductivity in both PANI and PEDOT backbones. Asymmetric changes in intramolecular conductivity of the polymer mixture have been demonstrated upon addition of PANI to PEDOT:PSS dispersion and vise versa. Complex films cast from the solution revealed a specific spherulite-like morphology and increased conductivity up to one order of magnitude as compared to films of the net PEDOT:PSS, which allowed us to conclude on formation of a qualitatively new system rather than a simple blend of the polymers and the effect of cooperative doping of the components by each other, respectively. The doping efficiency was shown to be strongly dependent on the solvent environment and concentration of the polymers in solutions. It is discussed that the increase in conductivity of the composite system is controlled not only by the direct doping of PANI with PSS, but also by weakening of interaction of PSS with the PEDOT backbone itself as a result of the above doping process.