X-RAY PHOTOELECTRON-SPECTROSCOPY STUDY OF BULK AND COLLOIDAL POLYANILINE

X-ray photoelectron spectroscopy (XPS) has been used to determine doping levels and the nature of doping species in bulk and colloidal polyaniline prepared in the presence of KIO3 in acidic media. The results show that protonation/doping of polyaniline is due to both chlorine (as CI-) and iodine (as I3- and I5-), whose relative contents depend on the initial oxidant to monomer ratio. Although most of the chlorine and iodine are in the ionic form, the results indicate that covalent (C-Cl and C-I) bonding occurs and has been quantified. The core level spectrum of N 1s is deconvoluted, and the doping level is determined from the integrated intensity of the peak which corresponds to the protonated imine nitrogen. Due to high-vacuum conditions, deprotonation occurs, resulting in lower doping levels than those obtained by elemental analysis.