Broadband dielectric and conducting properties of poly(N-alkylanilines)

Dielectric and conducting properties from 5 Hz to 8 GHz of poly(N-alkylanilines), with alkyl=methyl, ethyl, propyl and butyl, were investigated. It is shown that the d.c. electrical conductivity of these materials can be extrapolated from the a.c. conductivity at low frequency. The d.c. conductivity of poly(N-alkylanilines) in the salt form systematically increases as the number of carbon atoms in the alkyl chain decreases, from 1.9 × 10−4 S m−1 for poly(N-butylaniline) to 5.7 × 10−2 S m−1 for poly(N-methylaniline) at 21°C, while the d.c. conductivity of the materials in the base form is all in the order of 10−7 S m−1 at 21 °C. The dielectric constant and loss of both the salt and base forms exhibit a strong dispersion at low frequency; this has been attributed to the hopping of the charge carriers in the localized states. The dielectric constant and loss of the salt form are always larger than those of the base form. Conduction and dielectric relaxation mechanisms, phase and attenuation constants related with the microwave absorption have been discussed. A conduction mechanism of the variable-range hopping of the charge carriers is confirmed in these materials from 0 to 100 °C.