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.
The partial support by the Russian Foundation of Basic Researches, Grant No. 12-03-00148, was gratefully acknowledged. The author expresses his gratitude to Professor Dr. G. Hinrichsen, Professor A. P. Monkman, and Dr. B. Wessling for collaboration, to Dr. S. D. Chemerisov and Dr. N. N. Denisov for the assistance in EPR experiments, to Professor Dr. H.-K. Roth, Professor Dr. K. Lüders, and Professor Y. S. Lebedev for fruitful discussion.
A. Electronic properties of polyaniline (PANI)
B. Magnetic properties of polyaniline
II. THEORETICAL BACKGROUNDS OF SPIN RESONANCE AND SPIN TRANSFER IN CONDUCTING POLYANILINE
A. Magnetic parameters of polarons stabilized in PANI directly obtained by EPR spectroscopy
1. Lande factor
2. Spin susceptibility
3. Line shape and width
4. Electron spin-spin and spin-lattice relaxation of spin-packets
5. Saturation transfer EPR (ST-EPR) of paramagnetic centers in polymer semiconductors
B. Spin diffusion in conducting polymers
C. Mechanisms of charge carrier transfer in conjugated polymers
III. MAGNETIC, RELAXATION, AND DYNAMICS PARAMETERS OF CHARGE CARRIERS IN POLYANILINE AS FUNCTION OF STRUCTURE AND CONCENTRATION OF DOPAND
A. Polyaniline chemically modified by sulfuric and hydrochloric acids
B. Polyaniline chemically modified by camphorsulfonic and 2-acrylamido-2-methyl-1-propanesulfonic acids
C. Polyaniline chemically modified by para-toluenesulfonic acid
IV. UTILIZATION OF POLYANILINE IN MOLECULAR ELECTRONICS
A. Polyaniline-based sensors for solution components
1. Ethanol in hexane
2. Citric acid in ethanol
3. Nitroxide radical ATPO in ethanol
B. Spin-assisted charge transfer in polyaniline composites
1. EPR and light-induced EPR (LEPR) spectra of PANI-ES/P3DDT/PCBM composite
2. EPR linewidth of charge carriers in PANI-ES/P3DDT/PCBM composites
3. Spin susceptibility of charge carriers in PANI-ES/P3DDT/PCBM composites
4. Electron relaxation of polarons in PANI-ES/P3DDT/PCBM composites
V. CONCLUDING REMARKS
Data & Media loading...
Article metrics loading...
Full text loading...