Self-Assembled, Nanostructured Aniline Oxidation Products: A Structural Investigation

Abstract

The structure and oxidation state of self-assembled nanostructures formed by oxidation of aniline with ammonium persulfate in the presence of alanine have been investigated by solid-state 13C and 15N NMR, FTIR, GPC, elemental, UV−vis, and SEM methods. These techniques have been applied to samples obtained 1 and 20 h after the beginning of the reaction in their doped as-synthesized form or after reduction with hydrazine or dedoping with NH4OH or LiOH. Peaks at 66 and 72 ppm and a peak at 241 ppm in the 15N NMR spectra are shifted downfield by about 1−6 ppm and upfield by about 80 ppm, respectively, relative to the positions expected for the amine and imine N atoms in polyaniline. This indicates a difference in molecular structure between the nanotube material and standard polyaniline. This may be attributed to the presence of either strong H-bonding or a fundamentally different bonding connectivity in the nanotube material. Despite the significant difference in morphology of the samples after 1 and 20 h as...