Field-cycling NMR relaxometry study of dynamic processes in conducting polyaniline

Fast-field cycling NMR relaxometry been applied to investigate dynamic processes in the conducting polymer, polyaniline. For a group of samples with different concentrations of the dopant trifluoromethanesulfonic acid, the 1H spin−lattice relaxation rates exhibit power law dependence on the Larmor frequency. The powers obtained are found to increase above a percolation threshold in dopant concentration and to show similar concentration and temperature dependence as is observed for the macroscopic polymer conductivity. These observations are discussed in terms of the accepted models for both the fast polaron dynamics and the slower, low-frequency, polymer dynamics.