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AB diblock copolymers via RAFT-mediated miniemulsion polymerization
Thesis (MSc (Chemistry and Polymer Science))--Stellenbosch University, 2008.
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| Format: | Thesis |
| Language: | English |
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Stellenbosch : Stellenbosch University
2008
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| _version_ | 1867613990066061312 |
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| access_status_str | Open Access |
| author | Bailly, Nathalie |
| author2 | Sanderson, R. D. |
| author_browse | Bailly, Nathalie Sanderson, R. D. |
| author_facet | Sanderson, R. D. Bailly, Nathalie |
| author_sort | Bailly, Nathalie |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MSc (Chemistry and Polymer Science))--Stellenbosch University, 2008. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/2707 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:44:55.028Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2008 |
| publishDateRange | 2008 |
| publishDateSort | 2008 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/2707 AB diblock copolymers via RAFT-mediated miniemulsion polymerization Bailly, Nathalie Sanderson, R. D. Tonge, M. P. Stellenbosch University. Faculty of Science. Dept. of Chemistry and Polymer Science. RAFT polymerization Miniemulsion Copolymers Dissertations -- Polymer science Theses -- Polymer science Thesis (MSc (Chemistry and Polymer Science))--Stellenbosch University, 2008. The Reversible addition fragmentation chain transfer (RAFT) technique is a robust and versatile technique that enables the synthesis of polymers of controlled molecular weight and polydispersity. The application of the RAFT technique in heterogeneous aqueous media has attracted great interest in academics and industry due to it being more environmentally friendly, besides its other advantages. To date, the synthesis of well-defined high molecular weight polymers via the RAFT process under industrially relevant conditions still remains a challenge for polymer chemists. The study addresses the application of the RAFT process in heterogeneous media, namely in miniemulsion polymerization, for the synthesis of AB diblock copolymers of n-butyl methacrylate and styrene. AB diblock copolymers of high molecular weight were successfully prepared via a twostep method. In the first step, a dithiobenzoate monofunctional RAFT agent was used in bulk polymerization with the first monomer, n-butyl methacrylate. After the polymerization, the majority of the polymer chains contained the thiocarbonyl-thio RAFT agent functionality, which makes the chains potentially active for chain extension. The polymeric RAFT agent (also referred to as the starting block) obtained in the first step was chain extended in the second step, in miniemulsion, upon further addition of fresh initiator and the second monomer, styrene. The effects of the initiator/RAFT agent concentration ratio on the miniemulsion systems were investigated. The miniemulsion systems used for the high molecular weight AB diblock copolymers exhibited living features despite the high polydispersity indices. Kinetic results showed an increase in the rate of polymerization throughout the polymerization. Size exclusion chromatography (SEC) results indicated significant broadening in the molecular weight distributions and a steep increase in the polydispersity during the polymerization. It was concluded that the broad molecular weight distributions and steep increase in the polydispersity was not only related to the initiator concentration but possibly due to other factors such as inhomogeneity in the miniemulsion system and a transition in the kinetic behavior during the polymerization. Secondary particle formation emerged from kinetic data and transmission electron microscopy (TEM) results, but this were not supported by the SEC results. The effect of the use of a water-soluble initiator on the miniemulsion system was also investigated. Results indicated a similar behavioral pattern as observed in the AIBNinitiated systems, and not much improvement in terms of the molecular weight distributions and polydispersity was seen. The effect of the molecular weight of the diblock copolymers on the miniemulsion system was investigated. Poly(n-butyl methacrylate)-b-poly(styrene) diblock copolymers of lower molecular weight were synthesized via the two-step process. Kinetic results indicated a similar behavioral trend as to that of the high molecular weight diblock copolymers synthesized, however SEC chromatograms showed narrower molecular weight distributions and low polydispersity indices. 2008-12-02T07:01:19Z 2010-06-01T08:56:18Z 2008-12-02T07:01:19Z 2010-06-01T08:56:18Z 2008-12 Thesis http://hdl.handle.net/10019.1/2707 en Stellenbosch University application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | RAFT polymerization Miniemulsion Copolymers Dissertations -- Polymer science Theses -- Polymer science Bailly, Nathalie AB diblock copolymers via RAFT-mediated miniemulsion polymerization |
| title | AB diblock copolymers via RAFT-mediated miniemulsion polymerization |
| title_full | AB diblock copolymers via RAFT-mediated miniemulsion polymerization |
| title_fullStr | AB diblock copolymers via RAFT-mediated miniemulsion polymerization |
| title_full_unstemmed | AB diblock copolymers via RAFT-mediated miniemulsion polymerization |
| title_short | AB diblock copolymers via RAFT-mediated miniemulsion polymerization |
| title_sort | ab diblock copolymers via raft mediated miniemulsion polymerization |
| topic | RAFT polymerization Miniemulsion Copolymers Dissertations -- Polymer science Theses -- Polymer science |
| url | http://hdl.handle.net/10019.1/2707 |
| work_keys_str_mv | AT baillynathalie abdiblockcopolymersviaraftmediatedminiemulsionpolymerization |