Electrical conductivity and dielectric properties of polypyrrole/Na⁺–montmorillonite (PPy/Na⁺–MMT) clay nanocomposites

Abstract

Frequency dependent ac conductivity (σac), dielectric constant (e') and loss factor (e'') have been measured in the frequency range 100–106 Hz in polypyrrole/Na+–montmorillonite (PPy/Na+–MMT) clay nanocomposites. The nanocomposites were synthesized by in situ polymerization of pyrrole with varying amounts of Na+–MMT from 0.2 to 1.0 wt% in the presence of FeCl3 6H2O in an aqueous medium. All three measured quantities; σac, e' and e'' increased with the increase in MMT content in the composites at all frequencies. The frequency dependence of σac displayed a low frequency region of almost constant conductivity below 104 Hz, while above this frequency a rapid rise in σac was observed with the increase in frequency obeying a power law of frequency dependence with an exponent equal to 1. Both real and imaginary parts of the permittivity exhibited a low frequency dispersion which has been attributed to hopping of polarons and bipolarons in PPy and its composites.