Dielectric spectroscopy of conductive polyaniline salt films

Dielectric responses of polyaniline (PANI) salt films, made from two differ ent methods, were compared to investigate the effect of a dopant and film-f ormation methods on the dielectric properties. One of the film-formation me thods for emeraldine salt was the film-doping method, and the other, the so lution-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 comb inations as well as the dopants in the solution-doping method. The dielectr ic responses of film-doped samples had similar patterns irrespective of the dopants, while those of solution-doped samples were varied, probably due t o different conjugation conditions or/and the conduction mechanism. In the case of film-doped samples, dielectric loss and permittivity values were in creased 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-d oped PANI due to an altered chain structure. (C) 2001 John Wiley & Sons, In c.