Off-campus UMass Amherst users: To download dissertations, please use the following link to log into our proxy server with your UMass Amherst user name and password.
Non-UMass Amherst users, please click the view more button below to purchase a copy of this dissertation from Proquest.
(Some titles may also be available free of charge in our Open Access Dissertation Collection, so please check there first.)
Novel group 4 complexes for the polymerization and copolymerization of olefins
A new synthetic route to C-2 bridged indenyl metallocenes utilizing the anion of 1-indanone has been developed. Two new ansa-zirconocene complexes, isopropylidene(cyclopentadienyl)(2-indenyl)ZfCl2 ( 1a) and isopropylidene (cyclopentadienyl)(2-(1-methyl-indenyl))ZrCl 2 (1b) were synthesized and examined as precursors for the polymerization of α-olefins. These metallocenes were shown to be active for the polymerization of ethylene and for the oligiomerization of propylene when activated with excess methylaluminoxane (MAO). ^ A new route to isopropylidene bridged 2-indenyl metallocenes has been developed. Two new C-2 bridged ansa-zirconocenes, isopropylidene(1-indenyl)(2-indenyl)ZrCl 2 (10) and isopropylidene-bis(2-indenyl)ZrCl2 (11) have been synthesized and examined as pre-catalysts for the polymerization of ethylene and propylene. Both metallocenes were highly active for the polymerization of ethylene and the oligiomerzation of propylene when activated with excess methylaluminoxane (MAO) or [CPh3]+[B(C6F 5)4]−/Al(CH2CH(CH3) 2)3. The new pre-catalysts 10 and 11 were examined for the copolymerization of ethylene and styrene when activated with excess MAO. Both complexes 10 and 11 were highly productive for the copolymerization of ethylene and styrene with styrene incorporations of 29.2% and 21.0% by weight, respectively. 13C NMR studies indicated that there were no sequential or alternating styrene insertions in the copolymers, giving a unique polymer microstructure. X-ray diffraction studies indicated that the styrene units were excluded from the polymer lamella and that π-π interactions were taking place between the aromatic rings. ^ The effect ansa-phenyl coordination in indenyl titanium half-sandwich complexes on α-olefin polymerization has been tested using indenyl titanium trichloride (19), 3-benzyl-indenyl titanium trichloride (20), and 3-benzhydryl-indenyl titanium trichloride (21). For styrene polymerization, the presence of pendant phenyl substituents decreases polymerization activity, decreases percent syndiotacticity, increases molecular weight, and decreases the observed melting point of the polymer. For ethylene polymerizations, the presence of pendant phenyl substituents decreases polymerization activity and generally increases molecular weight. ^
Chemistry, Inorganic|Chemistry, Organic|Chemistry, Polymer
Matthew Nathaniel Herzog,
"Novel group 4 complexes for the polymerization and copolymerization of olefins"
(January 1, 2003).
Doctoral Dissertations Available from Proquest.