Comparison of the π-conjugated ring orientations in polyaniline and polypyrrole

While both polyaniline and polypyrrole are similar conducting polymers, from angle-resolved photoemission, they exhibit key structural differences. A temperature dependent change in the orientation of the aromatic ring orientation is observed in polypyrrole doped with the perchlorate (ClO4−) counter ion. This structural change occurs at about 220–240 K and is associated with a change in carrier mobility and ring orientation, but is not associated with a significant change in metallicity. Polyaniline exhibits a change in aromatic ring orientation with films thickness, but not with temperature.