New initiators and catalysts for radical, living radical and ring opening polymerizations

Date of Completion

January 2008

Keywords

Chemistry, Polymer

Degree

Ph.D.

Abstract

This thesis focuses on the development of new initiators and catalysts for the living radical polymerization (LRP) of styrene, the living ring opening polymerization (LROP) of ϵ-caprolactone and the development of room temperature initiating systems for the polymerization of gaseous, fluorinated monomers. ^ The Cp2TiCl catalyzed single electron transfer reduction of aldehydes was successfully introduced as novel initiating methodology for both LRP and LROP mediated by Cp2TiCl and respectively aldehyde-derived Ti alkoxides. The Cp2TiCl mediated styrene LRP was also demonstrated from both activated and inactivated halides. The effect of reaction parameters (aldehyde structure, temperature, reagent ratios) was investigated in depth and optimized conditions were elaborated. The living character was supported by the linear dependence of molecular weight on conversion, narrow polydispersity and linear first order kinetics. The initiation was demonstrated by the presence of the aldehyde or halide fragment on the polymer chain end. ^ A room temperature initiating system was developed for the (co)polymerization of fluorinated monomers. Kinetic investigations revealed a UV and peroxide prerequisite, and the free radical character of the polymerization. A series of fluorinated (co)polymers were subsequently successfully synthesized and characterized. ^ Gold halides were also investigated as superior catalysts for ϵ-caprolactone LROP. Living polymerizations were observed under a very wide range of reaction conditions. Mechanistic investigations revealed a strong complexation of the monomer with the catalyst, resulting in fast cationic polymerizations via either the activated chain end or monomer mechanism even under catalytic conditions. ^

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