ISSN:
0887-624X
Keywords:
half-sandwich metallocenes
;
mono-Cp-amido complexes
;
homogeneous catalysis
;
ethene-styrene copolymers
;
polymerization kinetics
;
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
Ethene was copolymerized with styrene using five different methylalumoxane (MAO) activated half-sandwich complexes of the general formula Me2Si(Cp)(N—R)MCl2, varying the substituents on the cyclopentadienyl ring and the substituent on the amide (Cp = tetramethylcyclopentadiene CBT, 1-indenyl IBT, 3-trimethylsilyl-1-indenyl SIBT, or fluorenyl FBZ, R = tert-butyl (complexes CBT, IBT, SIBT, FBZ) or benzyl CAT), as well as the metal center (M = Ti, except FBZ: M = Zr). Polymerization behavior was analyzed with respect to catalyst activity and polymerization kinetics, styrene incorporation, copolymer microstructure, and molecular weight. All complexes produced random poly(ethene-co-styrene) without any regioregular or stereoregular microstructure. Complex CBT showed the highest catalytic activity, the fluorenyl-substituted complex FBZ produced the highest molecular weight polymer, and complexes SIBT and CAT promoted high styrene incorporation. Cp-substitution pattern influenced deactivation of the catalytic system with bulky substituents of the Cp-ring slowing down deactivation at the expense of styrene incorporation. Moreover, deactivation was accelerated with increasing styrene concentration. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1571-1578, 1997
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
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