Chemical and electronic properties of vapor-deposited polyaniline films on metal substrates

Polyaniline thin films produced by the evaporative deposition of emeraldine on Cu(110) and on evaporated Au surfaces have been characterized using high-resolution electron energy loss spectroscopy (HREELS). Ultrathin films (less than 100 إ) doped with HCl exhibited plasma frequencies in the far-IR, suggesting a high degree of ordering and electrical conductivities greater than those of HCl-doped solution-cast films. In contrast, thicker vapor-deposited films (more than 1000 إ) were found to be highly branched and have lower conductivities upon doping. These results indicate that the substrate plays a major role in determining the chemical and electronic structure of vapor-deposited polyaniline near a polymer/metal intetface. Furthermore, variations in the properties of ultrathin films grown on Au and Cu substrates suggest that interface formation is sensitive to specific interactions between the vapor-deposited polymer film and the metal substrate.