Kinetic Study of Polymerization of Indole Using UV-Vis Spectroscopy

Abstract

The chemical oxidative polymerization of indole (IND) was carried out in 0.5 M H₂SO₄ solution using potassium peroxodisulphate. The rate of polymerization was followed by UV-vis spectroscopy. The absorbance corresponding to the amount of polymer at visible region (lmax = 535 nm) was followed for different concentrations of indole and oxidant at various time intervals of polymerization. Rate of polymerization (R_p) was determined under various conditions. The empirical kinetic was obtained from ex situ UV-vis spectroscopy (R_p = k[IND] [PDS]) PDS is peroxodisulfate and the rate constant of poly indole formation was estimated to be 15.26 M^-1 s^-1. The activation energy for polymerization of indole was also estimated. All the results were interpreted based on the mechanism that the polymer chain growth is accomplished by radical cation-monomer reaction pathway.