Synthesis and characterization of graft and block copolymers using hydroboration

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dc.contributor.advisorMallon, P. E.
dc.contributor.authorBaleg, Abd-Almonamen_ZA
dc.contributor.otherUniversity of Stellenbosch. Faculty of Science. Dept. of Chemistry and Polymer Science.
dc.date.accessioned2008-01-22T10:06:31Zen_ZA
dc.date.accessioned2010-06-01T09:01:52Z
dc.date.available2008-01-22T10:06:31Zen_ZA
dc.date.available2010-06-01T09:01:52Z
dc.date.issued2006-12en_ZA
dc.descriptionThesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2006.
dc.description.abstractGraft and block copolymers were synthesized using multifunctional and monofunctional macroinitiators to produce the copolymers. The process involved hydroboration of commercially available unsaturated rubbers and chain-end unsaturated macromonomers with 9-borabicyclo [3.3.1] nonane (9-BBN). The resulting secondary alkyl 9-BBN moieties in the starting materials were subsequently exposed to oxygen in the presence of free radical polymerizable monomers to facilitate the formation of graft and block copolymers. This research was initiated by first studying the hydroboration of a model compound, 2-hexene, in order to determine the optimal conditions for the graft reactions. The model compound was subsequently used as a macroinitiator to initiate the polymerization of methylmethacrylate (MMA). The same borane chemistry was extended to the synthesis of polystyrene (PS) block copolymers. Chain-end unsaturated PS macromonomers, synthesized by anionic polymerization, were effectively hydroborated and then polymerized to produce PS-b-PMMA block copolymers. The synthesis of polyolefin graft copolymers was subsequently achieved by hydroboration. Several commercial rubbers with different levels of unsaturated segments were efficiently grafted with vinyl monomers MMA and styrene (St) following the “graft from” approach. The grafted reactions were carried out under various reaction conditions to determine the effect of the following factors: concentration of oxygen, amount of borane and monomer concentration. By controlling these factors, different graft densities were achieved with high graft efficiencies. All reactions produced mixed products including unreacted (non-functional) macroinitiator, homopolymer, graft copolymer and in case of the highly unsaturated polymer a crosslinked gel. Finally, the chemical compositions as well as the molar mass distribution of the graft copolymers were fully characterized by different chromatographic techniques. 1H-NMR and FTIR were also used to confirm the structure of these copolymers. Gradient HPLC was developed and extensively used to characterize the graft copolymers.en_ZA
dc.format.extent1411953 bytesen_ZA
dc.format.mimetypeapplication/pdfen_ZA
dc.identifier.urihttp://hdl.handle.net/10019.1/2931
dc.language.isoenen_ZA
dc.publisherStellenbosch : University of Stellenbosch
dc.rights.holderUniversity of Stellenbosch
dc.subjectGraft copolymersen_ZA
dc.subjectBlock copolymersen_ZA
dc.subjectHydroborationen_ZA
dc.subjectDissertations -- Polymer scienceen_ZA
dc.subjectTheses -- Polymer scienceen_ZA
dc.subject.otherChemistry and Polymer Scienceen_ZA
dc.titleSynthesis and characterization of graft and block copolymers using hydroborationen_ZA
dc.typeThesisen_ZA
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