A charge in conducting polymers (CP) is transferred by polarons with weakly anisotropic magnetic parameters. Charge transport depends sufficiently on the structure and macromolecular dynamics of PC and can be studied by the saturation transfer EPR (ST-EPR) method. In the present report the results of the study of superslow dynamics in polytetrathiafulvalene with phenyl (PTTF-Ph) and tetrahydroanthracene (PTTF-THA) bridges, poly(3-alkylthiophene) (P3AT), poly(bis-alkylthioacetylene) (PATAC) presented below, emeraldine base form of polyaniline (PANI-EB) and other conducting polymers with heteroatoms are summarized.
The data presented evidence that the activation energy depends not only on the structure of a polymer but also on the level of its doping by a counter ion. For instance, this value obtained for PANI-EB, laser-modified PATAC, iodine doped PTTF-Me-Ph, PTTF-Et-Ph, and PTTF-THA are 15, 43, 36, 21, and 41 meV, respectively. Slight doping of an initial PTTF sample doubles the activation energy of macromolecular librations. This value was evaluated by the ST-EPR method for P3OT to be 4x10-4 s at 66 K and for PTTF-Me-Ph and PANI-EB to be 1x10-4 s at 75 and 125 K, respectively. The value deduced for P3OT (n = 8) decreases with temperature increase up to Tc = 150 K and then increases above this critical temperature.
This fact is evidence of the superslow 1D libration of the polarons stabilized on polymer chains near main X-axis at low temperatures for T < Tc, whereas their high-temperature part can be explained by the collective 2D motion at T > Tc with Ea = 69 meV.
Therefore, macromolecular dynamics is governed by the polymer structure, crystallinity as well as its doping level by counterion. A higher spectral resolution and saturation at D-band EPR provides qualitatively new information on magnetic, relaxation and dynamics parameters of paramagnetic centers and their microenvironment in CP. This allows the establishment of the correlation between these parameters and the polymer structure for a synthesis of different organic elements with optimal and controllable properties suitable for molecular electronics.