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Doctor of Philosophy




Dr. E. R. Gillies


Polyisobutylene (PIB) is a polymer well known for its desirable properties such as high chemical stability, impermeability to gases, and biocompatibility in certain applications. However in some applications it is limited by properties such as high hydrophobicity, lack of chemical functionalities, and the adsorption of proteins and organisms to its surface. Butyl rubber (IIR) is a copolymer of isobutylene (IB) with small percentages of isoprene (IP). Typically these IP units serve as sites for the covalent cross-linking of the IIR, in addition can serve as sites for further functionalization of IIR. These modifications can expand the potential applications of IIR. This thesis describes the development of different approaches to obtain both the attractive properties of the starting material in addition to new properties arising from its further modification. For example, antibacterial IIR surfaces were prepared using hyperthermal hydrogen induced cross-linking (HHIC) as a mean to covalently attach antibacterial polymers to the IIR surface. The antibacterial properties of the modified surfaces were investigated against Gram-positive and Gram-negative bacteria. In addition, using a synthetic method allowing for the clean modification of the double bonds of IIR and the grafting of poly(ethylene oxide) (PEO) chains along the polymer backbone, a library of linear PIB-PEO graft copolymers (lin-PIB-g-PEO) was successfully generated containing up to 83 wt% PEO content. The properties of the resulting graft copolymers were studied both on surfaces and in solution. These studies were further extended to generate arborescent PIB-PEO graft copolymers (arb-PIB-g-PEO) with the aim of comparing the effect of architectures on the properties of the PIB-PEO graft copolymers. Finally, a UV-cross-linkable IIR was synthesized by chemical modification of IIR backbones with cinnamate moieties. The physical and mechanical properties of the resulting UV-cured IIR polymers were studied.

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