Yield optimization of chemically synthesized p-TSA-doped polyaniline using a Box-Behnken design of experiment

Abstract

This research was aimed at optimizing the polyaniline (PAni) yield using a Box-Behnken design of experiment (DOE). The PAni sample was synthesized by the oxidative chemical polymerization of aniline using p-toluene sulfonic acid (p-TSA) as the dopant acid and ammonium peroxydisulfate (APS) as the initiator. The factors (concentration of dopant acid, initiator-to-monomer ratio, and the addition rate of initiator to monomer) that affect the yield were varied using a Box-Behnken DOE method. The polymer was characterized using various analytical techniques, including Ultraviolet-visible spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), and scanning electron microscopy (SEM). The yield was calculated and examined using the regression equation, main effects plots, contour plots, and optimisation plots. The results show that under the optimized conditions of dopant acid concentration of 0.1 mol/dm3, an initiator addition rate of 45 cm³/h, and an initiator to monomer (I/M) ratio of 1.5, PAni with a yield of 82.81% was obtainable. The characteristics identified in the UV-Vis analysis confirm that the synthesized PAni exhibits a semi-conductive property and as a result, could be applied as an additive in anticorrosive paint.