COMPARISON OF ELECTRONIC TRANSPORT IN POLYANILINE BLENDS, POLYANILINEAND POLYPYRROLE

The conductivity of PAni/PETG copolyester blends shows the expected re duction compared to unblended PAni, but PAni/PMMA (and PAni/PVC blends at lower temperatures) show a larger conductivity. SEM images indicat e that the different behaviour of the blends appears to be associated with greater granularity retained by the PAni particles dispersed in P ETG. The conductivities of the more highly conducting PAni blends, lik e PAni-CSA and its blends with PMMA measured by other authors, show a change to metallic sign for the temperature dependence near room tempe rature - simple models combining hopping/tunnelling with metallic cond uction are consistent with the conductivity except at very low tempera tures. The thermopower of PAni blends shows a remarkable similarity fo r blends with different insulating polymers and widely varying conduct ivity. For polypyrrole samples of very different conductivity, the cha nge to metallic sign for conductivity near room temperature does not o ccur, indicating a much smaller 'metallic' resistance contribution. Ne vertheless, the thermopower of polypyrrole, like that of PAni and PAni blends, is of metallic size and generally increases with temperature, as expected for metallic diffusion thermopower.