Copolymerization of propene with phenylnorbornene using ansa‐bridged metallocene catalysts

Abstract

AbstractPropene was copolymerized with phenylnorbornene using methylaluminumoxane (MAO)‐activated metallocene dichlorides exhibiting different symmetry: C2‐Symmetric rac‐ethylenebis(1‐ indenyl)zirconium dichloride (1), rac‐ dimethylsilylbis(1‐indenyl)zirconium dichloride (2), rac‐ethylenebis(1‐indenyl)hafnium dichloride (6), Cs‐symmetric isopropylidene(cyclopentadienyl‐9‐fluorenyl)zirconium dichloride (3), meso‐ethylenebis(1‐indenyl)zirconium dichloride (4), and C1‐symmetric ethylene(1‐ fluorenyl‐1‐phenyl‐2‐indenyl)zirconium dichloride (5) were chosen to evaluate the influence of the symmetry in copolymerization reactions. Experiments were done as batch polymerizations to produce homogeneous copolymers. By this setup, blend formation was avoided. The copolymers were characterized by NMR, GPC, and DSC. Catalysts 1 and 2 were the most active to copolymerize random, amorphous, copolymers with good activity. Cs‐symmetric, 3, showed decreased activity compared with 1 and 2 and produced a bimodal copolymer. Catalyst 4 showed even lower activity than that of 3. The activity of the hafnium complex 6, which produced a semicrystalline polymer with a high molecular weight (116,000 g/mol) was 320 kg/mol. Catalyst 1 produced the highest comonomer content (42%) in the copolymers measured by NMR. The least active catalyst was 5 (phenyl croup in the bridge), producing only 290 kg copolymer per mole of catalyst. All polymers had elevated glass transition temperatures compared to polypropylene. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2743–2752, 2002