Polyaniline toluenesulfonates: X-ray diffraction and electrical conductivity

Two polyaniline toluenesulfonates with different crystallinities were synthesized by using iron(III) and copper(II) toluenesulfonates, respectively, as oxidative coupling agents. The toluenesulfonate obtained with the iron(III) salt showed well-defined X-ray powder diffraction peaks; the other toluenesulfonate showed a diffuse pattern. When the toluenesulfonate with the higher crystallinity was neutralized and then doped again with HCl, the resulting polyaniline chloride showed an X-ray pattern closely resembling that of the original toluenesulfonate. The diffraction patterns of the toluenesulfonate and the chloride can be interpreted by assuming an essentially identical crystal packing in the unit cell. Since the cell volumes of the two salts are almost identical, the counteranion with a larger molecular size has a closer contact with a polyaniline chain; the close intermolecular contact may enhance interchain diffusion of charge carriers.