MICROWAVE DIELECTRIC RESPONSE OF MESOSCOPIC METALLIC REGIONS AND THE INTRINSIC METALLIC STATE OF POLYANILINE

We report the dependence of the microwave-frequency dielectric constan t and de conductivity on the crystallinity and local order of doped po lyaniline. The dramatic increase of the dielectric response in the thr ee highest crystalline physically crosslinked polyaniline samples prov ides evidence for the formation of three-dimensional coupled mesoscopi c metallic regions. We report the measurement of a negative dielectric constant in polyaniline (doped with camphor sulfonic acid) demonstrat ing the intrinsic metallic nature of polyaniline.