The kinetics of 3-methyl-, 3-chloromethyl-oxetane polymerization on the catalyst system Al(iso-C 4H 9) 3-H 2O and the molecular weight characteristics of polymethylchloromethyloxetane

Abstract

The kinetics of 3-methyl-, 3-chloromethyl-oxetane polymerization have been investigated on the catalyst system Al(iso-C 4H 9) 3−H 2O⩾2·0 as well as the molecular weight characteristics of the resulting polymer. It is shown that the molecular weight and polydispersity of the polymer do not depend on the degree of polymerization or on the initial monomer and catalyst concentrations. The molecular weight reaches high values (∼6–8 × 10 −5) in the earliest stages of polymerization, and does mot vary up to the very end of the process. The molecular weight distribution is relatively narrow; the Mw / Mn ratio is equal to ·29 ± 0·01, and likewise does not vary with conversion. The experimental values of Mn) exceed the calculated ones by a factor of 600–700, which points to a very low degree of catalyst utilization in initiation steps. The polymer formed inhibits the process as a result of interaction with catalyst. The kinetic scheme of polymerization proposed in the light of the data obtained involves four elementary stages: slow initiation, rapid propagation, spontaneous monomolecular termination and the inhibiting stage.