Charge Transport of the Mesoscopic Metallic State in Partially CrystallinePolyanilines

摘要

The charge transport properties including temperature dependent dc conductivity,thermoelectric power, electron paramagnetic resonance, microwave frequency dielectric constant and conductivity, and electric field dependent conductivity of partially crystalline ('physically' crosslinked) polyaniline correlated with x-ray structure studies demonstrate that charge delocalization in physically crosslinked polyaniline systems is structurally controlled. Further, we observe a positive dielectric constant at room temperature which increases to values greater than or equal 10(exp 4) with increasing percent crystallinity, size of crystalline regions and polymer chain alignment in the disordered regions supporting the establishment of mesoscopic metallic regions. We propose an inhomogeneous disorder model for this system in which ordered (crystalline) regions, described by three-dimensional metallic states are connected through amorphous regions of polymer chains where one-dimensional disorder-induced localization is dominant. We utilize the metallic box, interrupted metal strands, and Nakhmedov's phonon induced delocalization models to account for the temperature dependence of charge transport properties of the various partially crystalline polyanilines. Novel analyses for the sample and temperature dependent electron paramagnetic resonance linewidth and thermoelectric power are presented.