Abstract
M.Sc.
An annual production of approximately 46 million metric tons of polyolefins
worldwide, emphasizes the industrial importance of this product and the
polymerisation process. Olefins are the basic building block of the petrochemical
industry and are therefore readily available and cheap. Reactivity of olefins decreases
from ethylene to propylene to 1-octene and makes the study of polymerisation
catalysts more complex, seeing that the activity of a catalyst differs from monomer to
monomer.
In this study zirconocene complexes with bridged cyclopentadienyl ligands have been
prepared and investigated as , possible catalysts for the polymerisation of higher aolefins.
Fulvenes have been reductively coupled and used as ligands for zirconium
complexes. Steric bulk of the substituents on the ligand have been increased and
changes in the polymeric products have been studied. The tacticty, endgroups and
chain lengths of the polyolefins have been investigated. There is currently a considerable interest in the development of 'non-metallocene'
catalysts as alternatives for the polymerisation and oligomerisation of a-olefins.
Chelating diamide complexes of Group 4 metals have been the focus of much
attention and these compounds have shown moderate to high reactivity. However,
only a few examples of the corresponding chelating alkoxides are known. In this
study, alkoxide complexes of zirconium and titanium have been prepared with Schiff
bases as ligands. These complexes have been evaluated as polymerisation catalysts
and the products have been studied. The titanium complexes were more active than
the zirconium analogues. The narrow molecular weight distribution of the polyolefins
gave evidence that these catalysts are single-sited catalysts.