Evaluation of the electrical conductivity of polypyrrole polymer composites

A study of the electrical conductivity of polypyrrole-polyoxyphenylene composites (PPy-POP and PPy-POP-MPcTS) prepared by in situ electropolymerization is presented, where MPcTS stands for tetrasulfonated tetrasodium metallophthalocyanine salts and is used as a second dopand for polypyrrole. The conductivity is studied as a function of temperature in the range 77 less than or equal to T less than or equal to 300 K. The temperature dependence of the total ac conductivity, in the frequency range 10(2)-10(5) Hz, changes by approximately five orders of magnitude, showing a sub-linear dispersive behaviour. The temperature dependence of the de conductivity gives evidence for a transport mechanism based on the Mott's variable-range hopping model in one dimension for the PPy-POP composite, which shows a crossover to three dimensions for the PPy-POP-MPcTS composites. Using this model we were able to calculate meaningful values for the density of states, hopping energy and hopping distance.