Dielectric spectroscopy of conductive polyaniline salt films

Dielectric responses of polyaniline (PANI) salt films, made from two different methods, were compared to investigate the effect of a dopant and film-formation methods on the dielectric properties. One of the film-formation methods for emeraldine salt was the film-doping method, and the other, the solution-doping method. The conductivity relaxation and dielectric properties were measured by a microdielectrometer at 293 K in the frequency range of 1-100,000 Hz. Dielectric spectra were a function of the dopant in the case of the film-doping method, whereas it was a function of solvent-dopant combinations as well as the dopants in the solution-doping method. The dielectric responses of film-doped samples had similar patterns irrespective of the dopants, while those of solution-doped samples were varied, probably due to different conjugation conditions or/and the conduction mechanism. In the case of film-doped samples, dielectric loss and permittivity values were increased with decreasing dopant sizes. The dielectric relaxation times were also varied depending on the kind of dopants. The different solvent-dopant combinations led to variation of the dielectric responses in the solution-doped PANI due to an altered chain structure. (C) 2001 John Wiley & Sons, Inc.