Electrochemical Synthesis And Yield Optimisation Of Polyaniline Doped HCI

Abstract

In this study, potentiostatic electrochemical synthesis of polyaniline doped with hydrochloric acid (PANI- HCl) was performed and optimised using Box Behnken design of experiment. The factors chosen for the optimisation were monomer concentration, dopant concentration, current potential and polymerisation time at room temperature. The yield and conductivity of the synthesised PANI-HCl were measured and analysed. An optimum yield of 79.14% was obtained with conductivity of 181.21x10-2 S/cm. The PANI-HCl was characterized by Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible spectroscopy (UV-Vis), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The FTIR confirmed successful synthesis and doping, identifying key functional groups with a balanced ratio of quinoid to benzenoid rings, indicating an even oxidation state. UV-Vis spectroscopy revealed two peaks at around 430 nm and a broad shoulder between 500 – 600 nm, indicating good conjugation and contributing to electrical conductivity. XRD analysis showed a crystalline structure with peaks at 15.65° and 25.6°, aligning with the emeraldine salt form, suggesting the polymer's conductive nature. The calculated d- spacing of 5.5 Å supports this conductivity. SEM images displayed a nanofibrous morphology with interconnected fibers of 50-100 nm, creating a large surface area that facilitates efficient charge transport. The present study, demonstrated PANI-HCl as a potential candidate for application in corrosion protection due to its semi-conductive properties.