Synthesis and optical characterization of benzene sulfonic acid doped polyaniline

Abstract

In this study, Polyaniline emeraldine base (PANI-EB) and benzene sulphonic acid (BSA) doped polyaniline (PANI-BSA), HCl doped Polyaniline (PANI-HCl), and BSA and HCl doped Polyaniline (PANI-HCl-BSA) polymers were synthesized. Synthesizing was accomplished by chemical oxidative polymerization of aniline in acidic environment at room temperature (20 °C). Aniline to ammonium peroxydisulfate (APS) ratio is 1:1.25, and aniline to acid ratio is 1:1 for PANI-HCl and 1:0.5:0.5 for PANI-HCl-BSA. PANI-EB was obtained by de-doping PANI-HCl with NH3. In order to determine the type and degree of doping, electrical conductivity, band gap values, physical and structural properties were investigated. Structural properties of the doped and undoped PANI samples were determined using Fourier transform infrared spectroscopy (FT-IR), Ultraviolet visible spectroscopy (UV–vis) and (SEM), and electrical was is determined using four-point probe method. PANI-BSA, PANI-HCl-BSA and PANI-HCl doped polymers conductivity were measured as 1.39, 0.77 and 0.54 S.cm−1 respectively. Band gap values calculated by Kubelka-Munk equation are 2.35, 2.38, 2.40 eV respectively. The conductivity of the insulating PANI-EB polymer was measured as 2.9.10−4 S.cm−1 and its energy band gap was found as 3.06 eV. PANI-BSA, showed higher solubility in dimethylsulphoxide (DMSO) compared to PANI-HCl which is more commonly known. With its high conductivity, high resolution and low band gap, PANI-BSA has proven to be a suitable interface for electronic devices.