Electrochemical Growth and Charge-Transport Properties of Polyaniline/Poly(styrenesulfonate) Composite Films

The kinetic parameters of charge transport in composite-modified electrodes were measured as a function of the electrode potential, film thickness, solution pH, and counter ion composition by electrochemical impedance spectroscopy. The impedance characteristics of composite films were analyzed on the basis of the diffusion-migration transport of both holes and protons in the film. Incorporation of the polyanion with the host matrix produced a more compact deposite. A slow growth of the composite film during electropolymerization was ascribed mainly to its low electronic conductivity caused by poor contacts among polyaniline chains. Poly(styrenesulfonic acid) lowered the coupled diffusion coefficient of the charge carriers by a factor of ten. The relationships between the kinetic parameters and the oxidation and protonation levels of polyaniline suggested that the rate of charge transport through the composite film was controlled by electron transport, which occurred probably via interchain electron hopping