Electrically conducting polymer nanostructures confined in anodized aluminum oxide templates (AAO)

Abstract

Intrinsically or extrinsically conducting polymers are considered good candidates for replacement of metals in specific applications. In order to further expand their applications, it seems necessary to examine the influence of confinement effects on the electric properties of nanostructured conducting polymers in comparison to the bulk. The present study reports a novel way to fabricate and characterize high quality and controllable one-dimensional (1D) polymer nanostructures with promising electrical properties, with the aid of two examples polyaniline (PANI) and poly(vinylidene fluoride) with multiwall carbon nanotubes (PVDF-MWCNT) as representative of intrinsically and extrinsically conducting polymers, respectively. In this work, porous anodic aluminum oxide (AAO) templates have been used both as a nanoreactor to synthesize 1D PANI nanostructures by polymerization of the ANI monomer and as a nanomold to prepare 1D PVDFMWCNT nanorods by melt infiltration of the precursor PVDF-MWCNT film. The obtained polymer nanostructures were morphologically and chemically characterized by SEM and Confocal Raman Spectroscopy, respectively, and the electrical properties determined by Broadband Dielectric Spectroscopy (BDS) in a non-destructive way. SEM study allowed to establish the final nanostructure of PANI and PVDF-MWCNT and confirmed, in both cases, the well-aligned and uniform rodlike polymer nanostructures. Confocal Raman Microscopy has been performed to study the formation of the conducting emeraldine salt of PANI through all the length of AAO nanocavities. Finally, the electrical conductivity of both types of polymer nanostructures was easily evaluated by means of Dielectric Spectroscopy.