The polymerization of methyl isopropenyl ketone.

The polymerization of methyl isopropenyl ketone initiated by nbutyllithium and triethylaluminium in hydrocarbon solvent has been studied. The nbutyllithium initiated polymerization gives rise to a large quantity of oligomer and some high molecular weight material, which is a normal vinyl polymer containing some intramolecular cyclized units. The process of cyclization gives rise to water in the reaction mixture, which slows down the polymerization and limits the molecular weight of the high polymer. The triethylaluminium initiated polymerization also gives rise to a mixture of oligomer and normal vinyl polymer, but with this initiator the polymer is not cyclized, and the degree of polymerization is much greater than in the nbutyllithium system. In order to obtain useful kinetic data for the triethylaluminium initiated polymerization of methyl isopropenyl ketone, it has been shown necessary to pre-mix equimolar quantities of the triethylaluminium and monomer under carefully controlled conditions to produce the initiator species, followed by the subsequent addition of the further monomer, after the pre-mixing period. The polymerization was shown to follow first order kinetics with respect to methyl isopropenyl ketone and triethylaluminium concentrations.