Zirconocene-catalysed propene polymerisation: kinetics, mechanism, and the role of the anion

Song, F, Hannant, MD, Cannon, RD and Bochmann, M (2004) Zirconocene-catalysed propene polymerisation: kinetics, mechanism, and the role of the anion. Macromolecular Symposia, 213 (1). pp. 173-186. ISSN 1022-1360

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Abstract

The olefin polymerisation activity of metallocene catalysts strongly depends on the counteranion provided by the activator system. The relative activities of a number of new diborate anions [Z(BAr3)2]- have been quantified (Z = CN, NH2, N(CN)2; Ar = C6F5 or o-C6F4C6F5). The kinetic parameters for the initiation, propagation and termination steps of propene polymerisations catalysed by (SBI)ZrCl2 have been determined using quenched-flow kinetic and batch techniques [SBI = rac-Me2Si(1-Ind)2]. Comparison of two activator systems, (i) CPh3[B(C6F5)4] / triisobutylaluminium (TIBA) and (ii) methylaluminoxane (MAO) shows, surprisingly, that the concentration of species actively involved in chain growth at any one time is comparable for both systems, although the MAO-activated catalyst is about 20 times less active than the borate system. It is concluded that the counteranion remains sufficiently strongly bound to the metal centre throughout the chain growth sequence to modulate the energetics of monomer insertion. A model suggesting that the monomer binding follows an associative interchange (Ia) mechanism is proposed.

Item Type: Article
Faculty \ School: Faculty of Science > School of Chemistry
Related URLs:
Depositing User: Rachel Smith
Date Deposited: 02 Nov 2010 17:48
Last Modified: 21 Apr 2020 20:13
URI: https://ueaeprints.uea.ac.uk/id/eprint/10497
DOI: 10.1002/masy.200450917

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