Low frequency alternating current conduction and dielectric relaxation in polypyrrole, poly(N-methyl pyrrole), and their copolymers

The alternating current (ac) conductivity [sigma(m)(omega)], dielectric constant (epsilon') and loss (epsilon '') of polypyrrole (PPY), poly(N-methyl pyrrole) [P(NMPY)] and their copolymers; poly(N-methyl pyrrole-pyrrole [P(NMPY-PY)I have been measured in the frequency range 10(2)-10(6) Hz and in the temperature range 77-350 K. At 77 K, the ac conductivity can be expressed by the relation; sigma(ac)=A omega(s) where the slope s lies in the range 0.72-0.81 for these three polymers and decreases with increase in temperature. The well-defined loss peaks, whose magnitude decreases with the increase in frequency, have been observed in the temperature region where the measured ac conductivity approaches the direct current (dc) conductivity. These loss peaks have been associated with the movement of charge carriers in these polymeric films. The dc conductivity has also been measured in the temperature range 77-350 K and an attempt has been made to correlate it with dielectric data. (C) 1996 American Institute of Physics.