AC-IMPEDANCE STUDY OF TRANSPORT PROCESSES IN POLYANILINE MEMBRANES

Polyaniline (PANI) membranes symmetrically bathed by electrolyte solut ions on both faces have been studied by ac impedance. The membrane imp edance is very sensitive to both solution pH and membrane potential, b eing lower under the conditions for which PANI is an electronic conduc tor: it increases by several orders of magnitude when pH is increased from 0 to 7 and less markedly upon membrane reduction. In the doped st ate, the impedance diagrams of PANI membranes have the shape of a diff usion impedance. The experimental data are analyzed with reference to a published transmission-line model. The ionic diffusion coefficient v alues derived from this analysis are compared with those obtained by p ermeation experiments.