Ethene/propene copolymerisation by [Me2C(3-RCp)(Flu)]ZrCl2/MAO (R = H, Me, isoPr, tertBu)

Ethene/propene copolymerisations were carried out at 30°C and 60°C using four different metallocenes [Me2C(3-RCp)(Flu)]ZrCl 2 (R = H, Me, iso Pr, tert Bu). With increasing size of the substituent distinct changes in the copolymerisation behaviour and polymer microstructure were observed. A copolymerisation model taking into account the heterotopic nature of the metallocenes has been developed which fits the experimental triad distributions obtained. It is concluded that copolymerisation proceeds via chain migratory insertion for R = H and Me whereas a retention mechanism is found for R = tert Bu. For R = iso Pr especially at 60 °C a defective alternating mechanism seems to be operative.