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, so lution pH, and counter ion composition by electrochemical impedance spectro scopy. The impedance characteristics of composite films were analyzed on th e basis of the diffusion-migration transport of both holes and protons in t he film. Incorporation of the polyanion with the host matrix produced a mor e compact deposite. A slow growth of the composite him during electropolyme rization was ascribed mainly to its low electronic conductivity caused by p oor contacts among polyaniline chains. Poly(styrenesulfonic acid) lowered t he coupled diffusion coefficient of the charge carriers by a factor of ten. The relationships between the kinetic parameters and the oxidation anti pr otonation levels of polyaniline suggested that the rate of charge transport through the composite film was controlled by electron transport, which occ urred probably via interchain electron hopping.