Electrochemomechanical deformation of polyaniline films doped with self-existent and giant anions

Electrochemomechanical deformation of polyaniline films, which are substituted with sulfonic acid as a self-dopant and doped with camphor sulfonic acid as a giant dopant, have been studied. Upon oxidation, the self-doped polyaniline film basically contracts by proton doping, in contrast to the expansion by anion doping in usual polyaniline films. The film polymerized in camphor sulfonic acid by a constant-current method also shows proton dedoping and slight expansion upon oxidation. These results indicate that the chemomechanical deformation of these polyanilines by oxidation is primarily determined by the dedoping of protons or oxonium ion, and cancelled by the expansion due to electrostatic repulsion and/or conformational change resulting from the delocalization of pi electrons. (C) 1998 Elsevier Science B.V. All rights reserved.