Polyaniline nanotubes with rectangular-hollow-core and its self-assembled surface decoration: high conductivity and dielectric properties

Abstract

Polyaniline (PANI) nanotubes with a rectangular hollow core and decorated outer surface-wall with self-assembled nanobeads and triangular flakes of PANI have been synthesized in the presence of ZnO NPs by a sonochemical approach. This is the first example of the formation of well-defined hollow PANI nanotubes with a rectangular hollow interior. The hollow PANI nanotubes have an average length of ca. 10 μm and a hollow core with rectangular geometry. Nanobeads of PANI with diameter ca. 50 nm have been decorated/self-assembled on the surface of the outer wall of rectangular hollow PANI nanotubes to obtain a “Date-tree-like” 3D structure. The crystal structure has been characterized through XRD. The conduction bands and electronic environment have been confirmed through Raman, FT-IR, UV-Vis-NIR, XPS and EPR. Impedance measurements of rectangular hollow PANI nanotubes demonstrate their higher electrical conductivity (σ = 1.1 ± 0.1 × 10⁻⁴ S m⁻¹ to 3.0 ± 0.23 × 10⁻³ S m⁻¹) and dielectric properties, depending on the frequency range compared to the PANI particles synthesized in the presence of H⁺ and solid PANI fibres. PANI nanotubes with this novel rectangular hollow core structure and surface decorated texture are a unique type of nanostructure, which can be used in various conductive polymer based device applications.