Comparative study of electrical properties of polyaniline films and polyaniline-polystyrene blends

In this paper, a simple model classically used to describe electrical behav ior in conducting polymers can take into account transport properties in po lyaniline doped with two different counter-ions and in polyaniline-polystyr ene blends. Conduction is mainly limited by hopping or tunneling between po laronic conducting clusters. When the structural disorder is less pronounce d, a metallic contribution can occur near room temperature in series with t he hopping/tunneling one. This heterogeneous picture used for unblended pol yaniline can be applied to explain electrical blend properties above the pe rcolation threshold when conduction occurs among completely connected polya niline paths. Below the percolation threshold, the model has to take into a ccount an additional contribution due to a hopping mechanism between large disconnected segments of polyaniline. It is shown that thermoelectric power reflects essentially the metallic behavior of the conducting clusters.