Template-Free Synthesis of Aligned Polyaniline Nanorods/Tubes and Copper/Copper Hydroxide Nanowires for Application as Fillers in Polymer Nanocomposites

Abstract

Aligned polyaniline nanorods were synthesized in the presence of salicylic acid. Nanorods and nanotubes were also formed in the presence of camphorsulfonic acid (CSA) and para-toluenesulfonic acid (pTSA). Electrical conductivity measurements showed that the aligned nanorods had better electrical conductivity than the non-aligned nanostructures. Nanospheres were also observed in some cases. The formation of elongated nanostructures or spheres depended on the aniline monomer to surfactant molar ratio. This method in which nanostructures are formed using soft templates is often referred to as the template-free approach. Our success motivated us to explore the feasibility of obtaining similar metallic nanostructures without the use of a template. We successfully synthesized copper and copper hydroxide nanowires. While the copper nanowires formed as a mesh, the copper hydroxide nanowires formed as winding bundles. Upon switching the order in which the reactants were added, copper hydroxide nanoribbons were formed instead of bundles. Characterization of these nanostructures was done using Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FTIR) and the Four-point probe to measure electrical conductivity. Both metallic and organic nanowires that are fabricated by template-free methods are potential candidates for use as fillers in polymer nanocomposites. Polymer nanocomposites are found to be used in many advanced modern applications such as thermal interface materials in electronic devices which continue to be miniaturized, aerospace engineering where lightweight and robustness are important, sensors, medicine and catalytic activity.