Investigation on size and conductivity of polyaniline nanofiber synthesised by surfactant-free polymerization

Abstract

An attempt has been made to combine interfacial polymerization with a fast mixing technique without the use of surfactant. Effects of mixing speed, reaction time, temperature, oxidant-to-monomer molar ratio and nitric-to-monomer molar ratio were tested for electrical conductivity and polyaniline nanofiber size. The findings demonstrate that the diameter of polyaniline nanofiber can be reduced by optimising the synthesising parameter, thereby increasing the electrical conductivity of polyaniline nanofiber. Infrared spectroscopy has shown increased amplitude of the main absorption peak of polyaniline nanofiber during the conversion of aniline to conductive polyaniline nanofiber. The crystalline nature of polyaniline nanofiber has been discovered by the X-ray diffraction spectra. Hall effects experiments have shown that the electrical conductivity of polyaniline nanofiber has improved from 5.2 to 17.5 Scm −1 with an increase in homogenizer speed. The morphological properties of polyaniline nanofiber through electron microscopy scanning have confirmed the decreasing size of polyaniline nanofiber from 50-60 nm to 20–30 nm by increasing the homogenizer speed to 30,000 rpm. These findings demonstrate that higher homogenization speed can split the solution to smaller molecules during polymerization contributing to the creation of smaller nanofiber sizes.