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

Frequency dependent ac conductivity (sigma(ac)), dielectric constant (epsilon') and loss factor (epsilon '') have been measured in the frequency range 100-10(6) 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 center dot 6H(2)O in an aqueous medium. All three measured quantities; sigma(ac), epsilon' and epsilon '' increased with the increase in MMT content in the composites at all frequencies. The frequency dependence of sigma(ac) displayed a low frequency region of almost constant conductivity below 10(4) Hz, while above this frequency a rapid rise in sigma(ac) 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.