Investigation of structural and electrical properties of nickel chloride doped pyrrole aniline copolymer

Abstract

Chemical oxidative copolymerization has been employed for the synthesis of pyrrole and aniline copolymer at room temperature, in equal proportion. The prepared copolymer was undoped and then further doped with 10% NiCl2 using immersion method. Structural characterization of self-doped, undoped and doped copolymer was performed using FTIR, WAXD and SEM techniques. Results reveal the modifications in the original copolymer structure accompanied by various shifts in the band positions and appearance of the new bands in IR spectrum due to doping. The X-ray diffractograms reveals presence of modified and shifted peaks indicating the changes due to doping. The scanning electron micrographs of undoped and doped copolymers show globular structure due to doping when compared with that of the parent copolymer. In addition, using two probe methods the dc electrical conductivity of these samples was recorded in the temperature range of 313 K to 673 K, at a field of 27 V/cm. The log σ Versus 1/T plots of the self-doped and doped samples display the transformation of the sample at a given temperature from metallic to semi conducting and vice versa. The I-V plots for the self-doped and doped copolymer has also been plotted at a fixed temperature of 323 K which shows linear behavior of the samples. The conductivity measurements show reduction in conductivity of prepared samples thereby suggesting the presence of bipolarons as charge carrier. The results confirm the effect of doping on the copolymer properties.