Copolymerization of propene and 1-hexene with isospecific and syndiospecific metallocene catalysts

摘要

Copolymerization of propene and 1-hexene has been carried out in toluene at 30 degrees C in the presence of homogeneous methylaluminoxane (MAO)-activated 3 ansa-metallocenes, highly syndiospecific iPr(Cp)(Flu)ZrMe2 ((1) under bar), lower syndiospecific Et(Cp)(Flu)ZrMe2 ((2) under bar), and isospecific rac-(EBTHI)/ZrMe2 ((3) under bar), in order to study the role of catalyst stereospecificity on comonomer incorporation. The incorporation of I-hexene decreases in the following order: highly syndiospecific (1) under bar/MAO catalyst > lower syndiospecific (2) under bar/MAO catalyst > isospecific (3) under bar/MAO catalyst. Ail copolymer chains contain the comonomer in nearly random distribution. The copolymers produced by (1) under bar/MAO and (3) under bar/MAO catalysts were composed of uniform chains, but that by (2) under bar/MAO was fractionated into many fractions in the solvent extraction. Considerable rate enhancements were recorded in the copolymerization when the feed ratio of 1-hexene to propene is around 0.6 for all catalysts. [References: 20]