ZIRCONOCENE-BASED CATALYSTS FOR THE ETHYLENE-STYRENE COPOLYMERIZATION- REACTIVITY RATIOS AND REACTION-MECHANISM

A kinetic study of the ethylene-styrene copolymerization in the presen ce 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. T he parallel investigation on the catalyst based on pylidene(l-cyclopen tadienyl)(9-fluorenyl)zirconium dichloride allows us to produce a ster eoregular nearly alternating ethylene-styrene copolymer also with this catalytic system. The same main tacticity seems to characterize the c opolymers obtained with the C-2 and C-s symmetric catalysts in accorda nce with the generally accepted mechanism of stereocontrol in the l-al kene polymerizations.