Propagation activation energy vinyl ethers

Estimated Propagation Rate Constants and the Activation Energies by the Radiation and Chemically Initiated Polymerization of Ethyl and Isopropyl Vinyl Ethers at 30°C. 

It can be seen from Table II, particularly with EVE, that there is a substantial activation energy associated with the propagation rate constants. This is a characteristic of the vinyl ethers and is in marked contrast to the free cationic polymerization of the hydrocarbon monomers which have activation energies close to zero. The reasons for this difference have been discussed at length by Hayashi et al. for example. Two explanations have been offered, (1) that the cation is solvated by its own monomer and (2) that the high activation energy is due to the resonance stabilization of the propagating cation, i.e., from carbonium to oxonium structures. 

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