Zirconocene-based catalysts for the ethylene-styrène copolymerization: Reactivity ratios and reaction mechanism

A kinetic study of the ethylene-styrene copolymerization in the presence of rac-(ethylenebis-(1-indenyl)zirconium dichloride activated by MAO shows the peculiar behavior of this catalytic system that is known to produce crystalline nearly alternating copolymers. Some inferences on the monomer-metal interactions are made on the basis of this study. The parallel investigation on the catalyst based on isopropylidene(1-cyclopentadienyl)(9-fluorenyl)zirconium dichloride allows us to produce a stereoregular nearly alternating ethylene-styrene copolymer also with this catalytic system. The same main tacticity seems to characterize the copolymers obtained with the C2 and Cs symmetric catalysts in accordance with the generally accepted mechanism of stereocontrol in the 1-alkene polymerizations.