Copolymerization of ethene with styrene using different methylalumoxane activated half-sandwich complexes

✍ Scribed by Friedrich G. Sernetz; Rolf Mülhaupt; Francisco Amor; Thomas Eberle; Jun Okuda

• Publisher: John Wiley and Sons
• Year: 1997
• Tongue: English
• Weight: 197 KB
• Volume: 35
• Category: Article
• ISSN: 0887-624X
• DOI: 10.1002/(sici)1099-0518(199706)35:8<1571::aid-pola26>3.0.co;2-3

✦ Synopsis

Ethene was copolymerized with styrene using five different methylalumoxane (MAO) activated half-sandwich complexes of the general formula Me 2 Si(Cp)(N-R)MCl 2 , varying the substituents on the cyclopentadienyl ring and the substituent on the amide (Cp Å tetramethylcyclopentadiene CBT, 1-indenyl IBT, 3-trimethylsilyl-1indenyl SIBT, or fluorenyl FBZ, R Å tert-butyl (complexes CBT,IBT, SIBT, FBZ ) or benzyl CAT ), as well as the metal center (M Å Ti, except FBZ: M Å 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 fluorenylsubstituted 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.