Chemical Polymerization of Aniline Using Para-toluene Sulphonic Acid

Abstract

Polyaniline doped with hydrochloric acid (HCl) was prepared by chemical oxidative polymerization of aniline (ANI) in aqueous medium with ammonium peroxy disulphate as an oxidant. The deprotonation of the PANI: HCl samples were performed by stirring the PANI: HCl powder (emeraldine salt) in 0.1 M aqueous solution of ammonium hydroxide for 24 hours at room temperature, thus obtaining the polymer in the emeraldine base form. The redoping of the PANI (emeraldine base) with para- toluene sulphonic acid was performed by mixing emeraldine base (EB) with para- toluene sulphonic acid (PTSA) to obtain the required doping levels (Y = 0.5, Y =0.3, Y =0.1), known as the molar ratio of TSA to phenyl-nitrogen repeat units (S/N).The prepared samples were characterized by Fourier transform- infrared (FT-IR) spectroscopy, Ultraviolet- Visible (UV-VIS) spectroscopy and X-ray diffraction technique.The prepared samples were pressed into pellets, and DC electrical conductivity was measured, using four-probe method. The FT-IR peaks obtained in the samples are in good agreement with the reported peaks in literature. UV-VIS spectroscopy shows the various electron transitions present in the polyaniline samples. The crystallinity of the samples was studied in detail by X-ray diffraction technique.The conductivity shows an increase with increase in temperature, for all the three samples.