Intramolecular Chain Transfer Termination Followed by Reinitiation

Cationic polymerization of propylene sulfide provides a good example of a ocess in which, at the first, non-stationary stage, the originally formed active species (strained tertiary sulphonium fons holding a monomer molecule) are converted into the dormant species (non-strained sulfonium fons) which are at equilibrium with the strained ones  

for reinitiation proceeding as an intramotecular reaction we have the following scheme  

This scheme can be solved in a straightforward way and without any assumptkrn, leading to the following expression for IP ]  

Only a small portion of the originally formed active species persists in this form when equilibrium is reached. Thus, it can be assumed that ktt ri- Eventually we have 

On the other hand, at the early stages of polymerization, when reinitiation can be neglected, we have (assuming fast and quantitative initiation) the following scheme of reactions  

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Fig. 16. Dependence of In (kp/kt) on the effective volume (-Eg) for N-substituted aziridines 5.3.6 Intramolecular Chain Transfer (Termination) Followed by Reinitiation...

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