Electrochemical synthesis of perfluorinated ion doped conducting polyaniline films consisting of helical fibers and their reversible switching between superhydrophobicity and superhydrophilicity

Superhydrophobic conducting polyaniline (PAni) films were electrochemically deposited in acetonitrile-H2O electrolyte containing aniline monomer and perfluorooctanesulfonic (PFOS) acid. The films exhibited an extended network structure composed of helical PAni sub-micron fibers. The helical fibrous structure is thought to form through a supermolecular templating process. The surface of the PFOS-doped PAni films showed a water contact angle of 153 degrees. Reducing the PFOS-doped PAni (in emeraldine salt form) by negative potential led to de-doped PAni films (in leucoemeraldine base form) which were superhydrophilic (water contact angle close to 0 degrees). By controlling the electrical potential, PAni films were changed between the doped state and de-doped state, resulting in reversibly switchable superhydrophobic and superhydrophilic surfaces.