Determination of Free-Radical Propagation Rate Coefficient of N-Vinylindole by the Pulsed-Laser Polymerization Method

Summary

The pulsed-laser polymerization method was applied to determine the propagation rate constant k _p of N-vinylindole (VI), and the Arrhenius parameters were evaluated in the range of 30-70 °C. One of the characteristics of the VI monomer was its low activation energy (17.5 kJ mol^-1) compared with other vinyl monomers, indicating that the propagating radical has a high reactivity. Although the reaction rate constant k _p = 86 L mol^-1 s^-1 at 30 °C was relatively small and similar to that of styrene, the Q-value and the products of photochemical reactions suggested again that it has a higher reactivity than styrene monomer. This property of VI radical probably gives rise to high termination probability and the cyclic structure at the chain end of the linear polymer.