Dynamics of spin charge carriers in polyaniline

The review summarizes the results of the study of emeraldine forms of polyaniline by multifrequency (9.7-140 GHz, 3-cm and 2-mm) wavebands Electron Paramagnetic Resonance (EPR) spectroscopy combined with the spin label and probe, steady-state saturation of spin-packets, and saturation transfer methods. Spin excitations formed in emeraldine form of polyaniline govern structure, magnetic resonance, and electronic properties of the polymer. Conductivity in neutral or weakly doped samples is defined mainly by interchain charge tunneling in the frames of the Kivelson theory. As the doping level increases, this process is replaced by a charge thermal activation transport by molecular-lattice polarons. In heavily doped polyaniline, the dominating is the Mott charge hopping between well-conducting crystalline ravels embedded into amorphous polymer matrix. The main properties of polyaniline are described in the first part. The theoretical background of the magnetic, relaxation, and dynamics study of nonlinear spin carriers transferring a charge in polyaniline is briefly explicated in the second part. An original data obtained in the EPR study of the nature, relaxation, and dynamics of polarons as well as the mechanism of their transfer in polyaniline chemically modified by sulfuric, hydrochloric, camphorsulfonic, 2-acrylamido-2-methyl-1-propanesulfonic, and para-toluenesulfonic acids up to different doping levels are analyzed in the third part. Some examples of utilization of polyaniline in molecular electronics and spintronics are described. (C) 2014 AIP Publishing LLC.