Thesis (PhD (Chemistry and Polymer Science)--University of Stellenbosch, 2008. / Xanthate-mediated polymerization was investigated as a tool for the preparation
of well-defined poly(N-vinylpyrrolidone) and copolymers of N-vinylpyrrolidone. Some
results regarding the monomer vinyl acetate are included, mostly for comparison
purposes. The structure of the leaving/reinitiating group of the xanthate mediating agent
was tuned to match the monomer reactivity. This was achieved by studying the
initialization behaviour of monomer-xanthate systems via in situ 1H-NMR spectroscopy.
Additionally, the latter technique was valuable to identify side reactions affecting the
monomer, xanthate and/or polymeric species. Subsequently, experimental conditions
were defined, and used to optimize the level of control achieved during polymerization.
Block copolymers were prepared from a xanthate end-functional poly(ethylene
glycol) with both vinyl acetate and N-vinylpyrrolidone. Finally, the preparation of
poly(N-vinylpyrrolidone) with a range of well-defined end groups was achieved via postpolymerization
treatment of the xanthate end-functional polymerization product. 3
different routes were investigated, which lead to poly(N-vinylpyrrolidone) with 1)
aldehyde or alcohol, 2) thiol or 3) unsaturated ω-chain-end functionality, in high yield,
while the α-chain-end functionality is defined by the structure of the xanthate leaving
group. The ω-aldehyde end-functional poly(N-vinylpyrrolidone) was successfully
conjugated to the lysine residues of the model protein lysozyme via reductive amination.
Particular attention was drawn to characterizing the polymerization products.
NMR spectroscopy, liquid chromatographic and mass-spectroscopic techniques were
used. The major achievements emerging from polymer analysis carried out in this study
included the following:
- a library of NMR chemical shifts for N-vinylpyrrolidone derivatives;
- an estimation of the critical conditions for poly(N-vinylpyrrolidone) relevant for
separation according to the polymer chain-ends;
- conditions for the separation of block-copolymers comprising a poly(ethylene
glycol) segment and a poly(N-vinylpyrrolidone) or poly(vinyl acetate) segment
via liquid chromatography; - valuable results on matrix-assisted laser ionization-desorption time-of-flight mass
spectroscopy (MALDI-ToF-MS) of poly(N-vinylpyrrolidone).
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/1296 |
| Date | 03 1900 |
| Creators | Pound, Gwenaelle |
| Contributors | Klumperman, Bert, University of Stellenbosch. Faculty of Science. Dept. of Chemistry and Polymer Science. |
| Publisher | Stellenbosch : University of Stellenbosch |
| Source Sets | South African National ETD Portal |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Rights | University of Stellenbosch |
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