Polyaniline nanotubes and their dendrites doped with different naphthalene sulfonic acids

Polyaniline (PANI) nanotubes (130-250 nm in average diameter) doped with (alpha)-naphthalene sulfonic acid ((alpha)-NSA), (beta)-naphthalene sulfonic acid ((beta)-NSA) and 1,5-naphthalene disulfonic acid were synthesized via a self-assembly process. It was found that the formation yield, morphology (hollow or solid), size, crystalline and electrical properties of the nanostructures are affected by the position and number of -SO3H groups attached to the naphthalene ring of NSA as well as the synthesis conditions. Moreover, these nanotubes aggregate to form a dendritic morphology when the polymerization is performed at a static state. The micelles composed of dopant or dopant/anilinium cations might act in a template-like fashion in forming self-assembled PANI nanotubes, which was further confirmed by X-ray diffraction measurements, while the aggregated morphology of the nanotubes might result from polymer chain interactions including (pi)-(pi) interactions, hydrogen and ionic bonds.