Kinetic Study of Polymerization of Indole Using UV-Vis Spectroscopy

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 (lambda(max) = 535 nm) was followed for different concentrations of indole and oxidant at various time intervals of polymerization. Rate of polymerization (R,,) 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.