STEREOREGULAR, ALTERNATING ETHYLENE-NORBORNENE COPOLYMERS FROM MONOCYCLOPENTADIENYL CATALYSTS ACTIVATED WITH NONCOORDINATING DISCRETE ANIONS

Cyclic olefins copolymerize efficiently with ethylene using metallocen e catalysts to make rigid engineering polyolefins with high chemical h omogeneity. Materials with a high chemical homogeneity have value beca use they show reduced light scattering resulting in excellent clarity. The ultimate chemical homogeneity in a two component copolymer occurs when an alternating sequence distribution is achieved. Low symmetry b is-metallocenes have been shown to make alternating, stereoregular cyc lic olefin copolymers under the right process conditions. These copoly mers are semicrystalline and have high melt temperatures. Herein we re port two group 4 monocyclopentadienyl catalyst systems that yield semi crystalline ethylene/norbornene copolymers over a range of reactor con ditions. The clear copolymers have glass transition temperatures over 110 degrees C and melt temperatures over 240 degrees C. Further charac terization data is presented and a short discussion of a plausible pol ymerization mechanism is given. (C) 1998 Elsevier Science B.V.