Oxidative Copolymerization of Aniline with o- and p-Nitroaniline by Ammonium Per Sulfate: Kinetic and Pathway

Abstract

The kinetic study on the oxidation of aniline with o- and p-nitroaniline by ammonium persulfate (APS) has been carried out. The course of copolymerization was investigated by UV-vis spectroscopy and structural characterization was studied by FTIR spectral analysis. The electronic spectra of the copolymers poly(aniline-co-p-nitroaniline) and poly(aniline-co-o-nitroaniline) show hypsochromic shift. The shift has been observed in the bands corresponding to π → π∗ transition as well as in the exciton transition. The presence of nitro-group not only affects the oxidative polymerization window but also brings about the remarkable changes in the optical and electronic properties of parent polymer polyaniline. The poly(aniline-co-nitroaniline) has been shown multiple color transition (yellow → lightgreen → darkgreen) as the pH of the system changes with progress of polymerization reaction. The increase in absorbance recorded at various time intervals with increasing concentration of aniline, o- and p-nitroaniline, which indicates the growth of polymer formation. The first order kinetics is suggested as the degradation curve is consistent well byan exponential decay of APS. The resulting first-order rate constant was used to calculate the rate of poly(aniline-co-nitroaniline) formation using the rate equation –d[A]/dt = kcn. The reaction shows first-order dependence for each reactant.