Electrochemical Preparation of Chiral Polyaniline Nanofibers

Chiral polyaniline(PANI) nanofibers were synthesized via facilely potentiostatic electropolymerization method without template in the presence of (1S)-(+)-camphor-10-sulfonic acid(D-CSA) or (1R)-(-)-camphor-10-sulfonic acid(L-CSA) as the dopant. The morphology and optical property of chiral PANI nanofibers were characterized with scanning electron microscopy(SEM), transmission electron microscopy(TEM), UV-Vis spectrum(UV-Vis) and circular dichroism(CD). Combined with the average diameter of micelles and zeta-potential of different deposition solutions, the formation mechanism and the enhanced optical activity of the optical PANI nanofibers were studied. The morphology of PANI nanofibers without the helical structure was consistent with the change of the concentration of aniline in the deposition solution when the concerntion of CSA was 1 mol/L. Furthermore, the chiral PANI nanofibers induced by different chiral CSA exhibited mirror-imaged circular dichroism spectra with high ellipticity, indicating the stereochemical selectivity of the molecular structure of PANI chain in the electrodeposited process. The colors and optical activities of the chiral PANI nanofibers not only can be kept with the chemical dedoping/redoping treatment, but also can reversibly varied with the different oxidized forms which were controlled via electrochemical route.