Copolymerization of propylene and methyl vinyl ketone with metallocene catalysts: Synthesis, properties, and thermal and photooxidation of modified polypropylene

Abstract

The copolymers of propylene and methyl vinyl ketone are synthesized at 60°С by copolymerization in the propylene bulk in the presence of the polymethylaluminoxane-activated metallocene catalysts, namely, the isospecific С2-symmetric metallocene catalyst rac-Me2Si(2-Me-4-PhInd)2ZrCl2 and the syndiospecific Сs-symmetric metallocene catalyst Ph2ССpFluZrCl2, and characterized. It is shown that a noticeable insertion of methyl vinyl ketone into a polypropylene chain is possible during copolymerization initiated by the syndiospecific catalytic system, whereas in the case of the isospecific system, the insertion of methyl vinyl ketone is hindered. The thermal oxidation of the resulting polymers is studied. With the use of chemiluminescence, the accumulation of peroxy macroradicals under the action of daylight in samples based on isotactic and syndiotactic polypropylene is detected. It is found that even a low (0.2 mol %) content of methyl vinyl ketone endows polypropylene with the capability to undergo rapid and controlled degradation under natural conditions.