Rate constant of propagation reaction in stationary state of cationic polymerization. Part IV. Frequency factor (polymerisation of styrene catalyzed by iodine)

The pre‐exponential factor (Ap) and the activation energy (ΔEp ≠) of the propagation constant were determined on the cationic polymerization of styrene initiated by iodine in ethylene chloride, the obtained values being about 102l./mole·sec. and 6.5 kcal./mole respectively. The pre‐exponential factor obtained here is much smaller than that of the propagation constant of the radical polymerization. The extraordinarily small Ap value was considered to come from the interaction of the counter anion, and from the statistic consideration experimentally obtained kp value was proved to be reasonable.