Enhancement of electrical properties of metal doped polyaniline synthesized by different doping techniques

Abstract

Metal doped polyaniline (PANI) was synthesized following chemical oxidative polymerization method in acidic medium followed by two different doping techniques i.e. doping during polymerization and doping after polymerization of aniline. Three dopant materials ZnCl2, MgCl2, and CuCl2 were used in this synthesis. In first case, metal salts with various compositions were added with aniline and the polymerization results synthesized metal doped PANI. In second case, PANI was synthesized first and then dopant materials were added to prepare metal doped PANI. The synthesized PANI was characterized on the basis of electrical properties (conductivity and capacitance), and the effects of dopants and doping techniques were studied. It was found that the electrical conductivity was increased with increasing the dopants concentration in both of the doping techniques. The test results also showed that the samples prepared with doping after polymerization exhibited higher electrical conductivity compared to that of the samples doped during polymerization.CuCl2 was found to be the best dopant materials for the PANI on the basis of electrical conductivity. The sample coming from Cu doped with PANI during polymerization showed electrical conductivity of only 7.3 S/cm at the concentration of 0.5 M CuCl2. On contrary, in case of doping after polymerization, Cu doped PANI sample showed highest electrical conductivity of 35.7 S/cm at the same dopant concentration. Furthermore, the viscosity average molecular weight of the synthesized polyaniline was also evaluated. The prepared samples were further characterized by different techniques such as Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray (EDX) spectroscopy, and X-ray diffraction (XRD).