FULLY PROTONATED POLYANILINE - HOPPING TRANSPORT ON A MESOSCOPIC SCALE

In order to clarify the transport mechanism in fully protonated highly conductive polyaniline, the origin and size of the electronic localiz ation centers and barriers have to be determined. Dispersions of polya niline in an insulating polymer have been studied by temperature-depen dent broadband dielectric spectroscopy (5 Hz to 2 GHz, 100-320 K). The electronic transport in the blends and in pure polyaniline is shown t o be governed by three-dimensional (3D) hopping between mesoscopic cry stalline regions surrounded by amorphous polyaniline and not by interm olecular hopping or molecular scale disorder. Two independent approach es yield an average size of 8 nm for the metallic regions in polyanili ne with 3D extended electron wave functions. The barrier width is esti mated to be 1.6 nm. The crystalline metallic regions with an amorphous shell correspond to the primary particles which were found in morphol ogical studies.