Equivalent circuit analysis of the electrical properties of conducting polymers: Electrical relaxation mechanisms in polyaniline under dry and wet conditions

Abstract

Alternating current impedance measurements were used to characterize the electrical properties of the emeraldine base form of polyaniline. This conjugated polymer presently attracts much attention due to the possibilities of practical applications in sensors. The impedance data were acquired in the range of frequencies from 0.1 to 105 Hz at constant temperature of 30°C. The single surface electrodes covered by the polymer suspension in different solvents (water, N-methyl-pyrrolidinone and m-cresol) were used in the work. The substance was gradually dried during the analysis, being subjected to the continuous flow of dry nitrogen. The results of measurements were interpreted using an electrical equivalent circuit approach. Theoretical curves to fit the experimental data were obtained using ZVIEW program. Corresponding equivalent circuits were found to include a number of capacitors, resistors and constant phase elements with their parameters sensitive to the experimental conditions. Electrical behavior of the samples at different stages of their drying from different types of suspensions was monitored employing this method. The results were interpreted in terms of the involvement of solvent molecules into the mechanism of the electrical conduction of the polymer. © 1998 Elsevier Science B.V. All rights reserved.