Determination of pyrrole–aniline copolymer compositions by X-ray photoelectron spectroscopy

Oxidative chemical copolymerization of pyrrole(Py) and aniline (An) by copper perchlorate in acetonitrile was carried out. By varying the monomer feed ratios, the copolymer compositions could be effectively modified. The high-resolution X-ray photoelectron spectroscopy (XPS) analysis using monochromatized Al Kα X-ray source enabled the quantification of the proportions of pyrrole and aniline units in the copolymers. The copolymer composition and microstructure obtained were also characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and electrical conductivity measurements. The results of XPS, FTIR, SEM and conductivity measurements supported the presence of copolymers consisting of random segments of aniline and pyrrole units. The copolymers generally exhibited reduced electrical conductivity, compared to those of the respective homopolymers, probably as a result of the interruption of the polaron lattice by the presence of the second monomer.