UBC Theses and Dissertations
Transition metal-containing Brønsted acids as single component cationic initiators for olefin polymerization Bennett, Anna Louise
Butyl rubber is a polymer commonly found in everyday life and produced solely by cationic polymerization at −100 °C. The cationic polymerization of olefin monomers, like isobutylene and isoprene in butyl rubber, is very challenging. It is prone to side reactions which can lead to low molecular weight polymers with broad dispersities if the temperature of polymerization is not kept extremely low. Using Brønsted acids incorporating weakly coordinating anions (WCAs) as single component initiators has been an area of growing interest over recent years. WCAs are commonly comprised of main group elements, however in this thesis transition metal complexes are implemented instead to increase the steric bulk of the anions. A series of four Brønsted acids containing Group 5 metals have been synthesized, isolated and characterized. The cationic polymerization of n-butyl vinyl ether, styrene, α-methylstyrene and isoprene is studied for each of isolated single component initiators and have been shown to produce high molecular weight polymers at temperatures above −100 °C.
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