Conduction mechanism of polyaniline: Effect of moisture

It has recently been shown that the emeraldine base polymer form of polyaniline undergoes a transition from an insulating to a metallic state upon protonation with HCl. The conductivity of the protonated polymer is sensitive to the moisture content of the polymer, varying by as much as a factor of five upon pumping the samples. We report here the temperature-dependent microwave-frequency (1010 Hz) conductivity and dielectric constant as a function of environmental history. The results are consistent with the effect of moisture on the barriers between small metallic polymer grains. Texture of granular metal particles and localization within metallic islands are decisive in the frequency- and temperature-dependence of the conductivity and dielectric constant.