Abstract
An inductively coupled pulsedβplasma reactor was used to synthesize polyaniline thin films on several substrates positioned at various distances from the center of the radio frequency (RF) coil. The samples were characterized with Fourier transform infrared (FTIR), cyclic voltammetry, and microscopic techniques. Impedance spectroscopy was used to determine the electrical characteristics of threeβlayer structures with polyaniline as the middle layer between top and bottom metal electrodes. FTIR results indicated that the chemical composition and structure of the films were very dependent on the substrate's position with respect to the RF coil, there being considerably less aromatic character closer to the coil. The electrochemical behavior of the films in acidic electrolytes was similar to that of smallβmolecule aniline oxidation products; the number of peaks in the cyclic voltammograms varied with the substrate. Scanning electron microscopy indicated that as the films became thicker, they developed nodules atop a somewhat smoother underlayer. Results from transmission electron microscopy and optical birefringence suggested that the films were not completely homogeneous. The impedance measurements were consistent with relatively rough films possibly containing pinholes. Β© 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93:1317β1325, 2004