ESR study of mechanism of polyaniline conductivity

Powders, solutions, and films of polyanilines synthesized by three methods of aniline oxidative polymerization were studied by ESR, optical spectroscopy, and X-ray diffractometry. Polyanilines under study were shown to differ in the degree of polaron delocalization along solitary polymer chains in a solution, the packing density in powders and films, the mobility of polarons, and the degree of crystallinity. The conductivity of films correlates only with the characteristic time () of O₂ diffusion into amorphous regions of the films. These times were determined from the kinetics of changes in the ESR line intensities after admission of O₂. The higher the film conductivity, the greater the value and the sizes of the amorphous regions. The electroconductivity of the films is likely determined by the mobility of polarons in boundary regions between the amorphous regions rather than within the amorphous regions: the larger the sizes of the amorphous regions, the less the number of low-conducting contacts between the amorphous regions and the higher the conductivity.