Ethene/Norbornene Copolymerization using the Catalyst System Pri[(3-Pri-Cp)Flu]ZrCl2: Determination of the Copolymerization Parameters and Mechanistic Considerations

✍ Scribed by Ralf A. Wendt; Richard Mynott; Gerhard Fink

• Publisher: John Wiley and Sons
• Year: 2002
• Tongue: English
• Weight: 131 KB
• Volume: 203
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.200290048

✦ Synopsis

Abstract

The ^13^C NMR spectra of ethene/norbornene copolymers in which there are no norbornene microblocks are much simpler than those of copolymers in which norbornene microblocks are present, making it possible to completely assign all the ^13^C resonances to the corresponding pentads in the copolymer chain. However, there is disagreement in the literature over several assignments of the ethene ^13^C NMR signals. In this paper these discrepancies are summarized and discussed. This contribution also reports ethene/norbornene copolymerizations carried out at various temperatures using the homogeneous catalyst system Pr^i^[(3‐Pr^i^‐Cp)Flu]ZrCl~2~. The ^13^C NMR spectra of the copolymers were analyzed in the light of the discussion above and the triad distributions were used to determine the copolymerization parameters by Markov first‐ and second‐order statistical models. On the basis of these results, the mechanism generating such an alternating microstructure in these copolymers is discussed and compared with the mechanism previously proposed in the literature.

The ^13^C NMR spectrum with signal assignments of an ethene/norbornene copolymer without norbornene microblocks.

magnified imageThe ^13^C NMR spectrum with signal assignments of an ethene/norbornene copolymer without norbornene microblocks.