EPR study of charge transfer in polyaniline highly doped by p-toluenesulfonic acid

Magnetic, relaxation and electronic dynamic parameters of paramagnetic centers in crystalline domains of polyaniline highly doped by p-toluenesulfonic acid (PANI-PTSA) as well as PANI-PTSA dispersed in poly(methyl methacrylate) were studied by the 3 cm (9.7 GHz) and 2 mm (140 GHz) wavebands EPR. These centers demonstrate the Lorentzian single line with the Dysonian contribution at both wavebands indicating intrinsic conductivity of metal-like domains near 1500–4000 S/cm at room temperature. Effective conductivity of the polymer is defined by Q3D delocalization of charge carriers within such domains and their Mott variable range hopping between the domains dominating its micro- and macroscopic conductivity. It was shown that the interaction of the charge carriers with the lattice phonons governs intradomain charge transfer at high temperatures. Reversible dipolare interaction of paramagnetic centers with oxygen was revealed. This interaction depends on electron precession frequency and/or on the PANI-PTSA dispersion in an insulating matrix. Charge transfer in PANI-PTSA was analyzed to be non-correlated with spin relaxation and dynamics that evidences the formation of Q3D metal-like domains contrary to the “single conducting chain” model.