Effect of complexing agents on the polymerization of allyl monomers

IN SEVERAL papers [1-5] it was found that the radical polymerization of some vinyl monomers (methyl methacrylate, acrylonitrile, etc.) is accelerated in the presence of coordination-unsaturated metal halides (LiC1, ZnC12, A1Br3, etc.) which form complexes with functional groups of the monomer. I t was desired to s tudy the effect of complexing agents on the polymerization of allyl monomers. In this research we investigated the bulk polymerization of allylacetate (AA) and allyl alcohol (AS) in the presence of ZnCI~. The polymerization was initiated by e°Co F-irradiation, or photochemically. The monomers were purified by the usual methods, the criterion of puri ty being the agreement of the constants with those in the literature and the absence of alien peaks in the gas-liquid chromatogram. Zinc chloride of analytical puri ty was not subjected to further purification, but was dried in a vacuum by heating. The ZnC12 solutions in the monomers were prepared either by direct mixing of the ingredients or, in the case of high concentrations of ZnCI~, by vacuum distillation of the surplus monomer from a solution saturated at room temperature, as in this way the ZnC12 is not precipitated, and the system remains homogeneous. The kinetics of the polymerization were investigated by the dilatometric and gravitometric methods and the results were within the limits of measuring errors. With all the ZnCI~ concentrations the radiation polymerization and photochemical polymerization commenced immediately, without any induction period, and plots for degree of conversion versus time are linear right up to high degrees of conversion, which is characteristic of the radiation polymerization of allyl monomers [6]. A s tudy was made of the dependence of the rate of polymerization of AA on the concentration of ZnC12. The tests were carried out with close rates ranging from 160-620 r/sec, within limits of 20-55 °. In all cases the polymerization rate is increased 5.6-6 times in the change from pure AA to a 1 : 1 complex. The characteristic curve is shown in Fig. 1. The rate of polymerization is a function of the dose rate to a degree close to unity and is weakly dependent on tempera-