Functionalization of polyethylenes via metallocene/methylaluminoxane catalyst

Ethylene was copolymerized with 1,1-dimethyl-2-propen-1-ol, 5-hexen-1-ol, 10-undecen-1-ol, methyl-9-decenoate and 10-undecenoic acid in the presence of the catalyst system ( n -BuCp) 2 ZrCl 2 /MAO. The addition of a polar comonomer resulted in a rapid deactivation of the catalyst, which was mainly due to the interactions between polar comonomer and Lewis acid catalyst components. A comparison between 5-hexen-1-ol and 10-undecen-1-ol revealed that the increase in the number of carbon atoms between the functional group and double bond did not influence the polymerization rate decreasing effect of the polar comonomer, but increased its incorporation to the copolymer. Steric hindrance in the vicinity of the hydroxyl group hindered the 1,1-dimethyl-2-propen-1-ol from reacting with the catalyst components but, on the other hand, the steric protection made the comonomer unable to copolymerize. Compared with 10-undecen-1-ol, methyl-9-decenoate and 10-undecenoic acid showed lower reactivities in the polymerizations. The GPC profiles of the samples showed a reduction in the molar masses and a marked broadening in the molar mass distributions of the polymers with the addition of the polar comonomer indicating the presence of multiple active sites in the catalyst.