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ansa ‐Zirconocenes with Bridge‐tethered Donors: Synthesis and Application as Catalysts in Solution Polymerization of Ethylene
Author(s) -
Rau A.,
Wieczorek T.,
Dornik H.,
Luft G.
Publication year - 2013
Publication title -
chemical engineering and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.403
H-Index - 81
eISSN - 1521-4125
pISSN - 0930-7516
DOI - 10.1002/ceat.201200393
Subject(s) - polymer chemistry , ethylene , polymerization , catalysis , polymer , alkoxy group , side chain , metallocene , chemistry , molar mass distribution , materials science , organic chemistry , alkyl
Four new donor‐functionalized ansa ‐zirconocenes have been synthesized from the XMeSiCp 2 ZrCl 2 and X 2 SiCp 2 ZrCl 2 general formula (where X = (CH 2 ) 3 OEt, C 8 H 4 SCH 2 OMe, and CH 2 (2‐MeO‐3‐Me‐C 6 H 3 )). In each of these metallocenes, alkoxy groups are linked by a three‐carbon chain to the silicon atom. To study the influence of the functionalized side chains, these metallocenes were activated with methylalumoxane (MAO) and utilized in solution polymerization of ethylene. The molecular weight distributions of the polymers formed show a bimodal shape which can be described as a superposition of two Schultz‐Flory distributions, synonymous to at least two different catalytic species. Unimodal polymers with M w / M n = 2 were formed with the Me 2 SiCp 2 ZrCl 2 /MAO catalyst system, indicating that the unusual bimodal molecular weight distributions are due to the functionalized side chains tethered to the Si‐bridge.