Studies on ethylene and styrene copolymerizations with dinuclear constrained geometry complexes; effects of length of bridge

The new dinuclear CGC (constrained geometry complexes) with indenyl and methyl substituted indenyl and polymethylene bridge have been synthesized, and the copolymerization of ethylene and styrene has been studied in the presence of methylalumionoxane. The activity of 12-methylene and 9-methylene bridged dinuclear CGC were 4 times higher than that of 6-methylene bridged dinuclear CGC. This result might be understood by the implication that the steric effect rather than the electronic effect may play a major role to direct the polymerization behavior of the dinuclear CGC. The dinuclear CGCs are very efficient to incorporate styrene in backbone. The styrene contents in the formed co-polymers ranged from 6 to 45 mol% according to the polymerization conditions. The melting temperature of copolymers disappeared at high content of styrene (about 11 mol%). There is no styrene-styrene diblock sequence in copolymers. This result indicates that the dinuclear CGC are very effective to generate random copolymer of ethylene and styrene.