Effect on Poly(C6H5NH2) Emeraldine Salt by FeCl3 and KMnO4 as Secondary Dopants

Abstract

Polyaniline in its emeraldine salt form was synthesized by chemical method from aniline monomer in the presence of HCl mixed with LiCl and Ammonium-persulphate (APS) as oxidant. Then a portion of samples was de-doped with NH3 solution and another equal portion was separately post doped with secondary dopants such as FeCl3 and KMnO4 respectively. Finally the dried samples of polyaniline prepared in all its three different forms were characterized by ultraviolet – visible (UV-Vis) spectroscopy, Fourier- Transform Infrared (FTIR) spectroscopy and electrical conductivity measurement. FT-IR and UV-Vis spectra confirmed the expected structural modification upon doping, undoping and post doping processes of the polymer. The influences of secondary doping on the electrical conductivity were also investigated from their spectroscopic data and the dramatic rise in conductivity was said to be induced from the secondary doping is attributed by structural rearrangement from a compact-coil form of PANI to a more expanded conformation. The result also shows that secondary doping increased the conjugation. Their measured electrical conductivities were from 0.02 for undoped, 156 for primary doped form and increasing from 158 to 210 S/cm for those secondary doped polyaniline.