Complex Permittivity Studies of Polyaniline

Abstract

ABSTRACTA study of the complex dielectric properties at microwave and millimeterwave frequencies on several polyanilines was performed. The polymers investigated were based on emeraldine salts. The chemically synthesized emeraldine base was protonated with acids of various pH levels. Aqueous HCI (pH range 0.12 to 1.07) and Tosylic (pH range 0.22 to 1.13) were used. Complex permittivities of the emeraldine base and salts were determined at X-band and R-band using waveguide measurements. Characterization techniques were developed to reduce the measurement error. This included the electrical determination of the sample holder length and sample position. The real component of the dielectric constant was found to vary from 4 to 107 at Xband and from 3.8 to 926 at R-band. The dielectric loss spanned 3 orders of magnitude at X-band and 4 orders of magnitude at Rband. The frequency dependence was relatively level within each band with a slight decrease in each permittivity component with increasing frequency. The DC conductivity ranged from 10−4 S/cm to 10−1 S/cm for the emeraldine salts. The time dependence of the complex permittivity and DC conductivity was examined.