The course of aniline oxidation with ammonium peroxydisulfate in aqueous solutions has been investigated. The reaction was terminated at various times and the intermediates collected. Besides the precipitates, the films deposited in situ on silicon windows have also been studied. The kinetic course of polymerization is controlled by the acidity level, which changes during the polymerization from pH 8 to a final value close to pH 1. It has two distinct exothermic phases. Gel-permeation chromatography indicates that aniline oligomers are produced at first at high pH, while polyaniline follows after the pH becomes sufficiently low. The growth of polyaniline nanotubes was observed by optical microscopy and confirmed by electron microscopy. The molecular structure of the reaction intermediates was studied in detail by FTIR spectroscopy. Oxidation products are markedly sulfonated, and they contain phenazine units. Aniline oligomers are more soluble in chloroform than the polymer fraction, which contains nanotubes.

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Polyaniline (PANI) was prepared by the oxidation of aniline in the presence of various inorganic and organic acids at 20 • C and −50 • C. When strong acids were used, the conductivity of the protonated PANI was typically 1-10 S cm −1 . The results indicate that the protonation of PANI in media containing carboxylic acids was achieved with the help of sulfuric acid produced during the reaction with ammonium peroxydisulfate. The conductivity of PANI prepared under such conditions was reduced. Partial benzene-ring sulfonation has been proposed to explain the wide range in conductivity of PANI bases, 10 −11 -10 −7 S cm −1 . The densities of the samples reflect the nature of the acid used. The densities of the corresponding PANI bases exhibit much less variation. Molecular weight and degree of crystallinity of PANI are higher when the polymerization is carried out at −50 • C. The conductivity of the PANI is determined mainly by way of protonation. The effects of molecular weight and of crystallinity on PANI conductivity are marginal.