Solution isomerization of commercial C2-symmetric metallocene catalysts
Date
2006-03
Authors
Soltan, Omar
Journal Title
Journal ISSN
Volume Title
Publisher
Stellenbosch : University of Stellenbosch
Abstract
This study concerns the investigation of the isomerization of different
metallocene catalysts in solution, and the effects thereof on the microstructure
of polypropylenes prepared with these catalysts.
Two C2 symmetric ansa metallocenes, ethylene-bis(indenyl) zirconium
dichloride (EI) and dimethylsilyl-bis(2-methyl benzoindenyl) zirconium
dichloride (MBI) were exposed, in solution, to both sunlight and UV radiation.
The rac-meso isomerization of these catalysts were followed by 1H NMR
spectroscopy. The reaching of a photostationary state is described, as well as
the effect of isomerization of these catalysts in solution on the polymerization
of propylene.
Results show that metallocene structure has an effect on the isomerization
rate and photostationary state. Results also show that the wavelength of light
plays a role in the isomerization process.
Effects on stereochemistry and molecular weight of the formed polymer as
well as the catalyst activity is described and discussed. In addition the effect
of activating the catalysts with MAO before exposure to light is discussed.
Description
Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2006.
Keywords
Metallocene catalysts, Isomerization, Dissertations -- Polymer science, Theses -- Polymer science