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The investigation and analysis of RAFT-mediated block copolymers in aqueous dispersed media
Dissertation (MSc)--University of Stellenbosch, 2007.
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| Format: | Thesis |
| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2012
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| _version_ | 1867613976144117760 |
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| access_status_str | Open Access |
| author | Pretorius, Nadine O. |
| author2 | Sanderson, R. D. |
| author_browse | Pretorius, Nadine O. Sanderson, R. D. |
| author_facet | Sanderson, R. D. Pretorius, Nadine O. |
| author_sort | Pretorius, Nadine O. |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Dissertation (MSc)--University of Stellenbosch, 2007. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/21699 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:44:41.678Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2012 |
| publishDateRange | 2012 |
| publishDateSort | 2012 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/21699 The investigation and analysis of RAFT-mediated block copolymers in aqueous dispersed media Pretorius, Nadine O. Sanderson, R. D. McLeary, J. B. Stellenbosch University. Faculty of Science. Dept. of Chemistry and Polymer Science. Block copolymers Addition polymerization Theses -- Polymer science Dissertations -- Polymer science Dissertation (MSc)--University of Stellenbosch, 2007. ENGLISH ABSTRACT: Polymers prepared via radical techniques are very common in our every day environment. The technique is however limited by a lack of control over the polymerization and an inability to produce block copolymers. Block copolymers have a significant number of potential applications in advanced materials and as a result are a field in which significant research is being conducted. Reversible Addition-Fragmentation chain transfer (RAFT) is a living free radical process that overcomes the disadvantages inherent in the traditional process. In this study the mediation behaviour of two inherently different RAFT agents was investigated by the “living” free radical polymerization of model monomers via the RAFT process in homogeneous and aqueous dispersed media with the focus on differentiating between the two types of agents. To ensure that the agents were comparable a new RAFT agent had to be prepared which has not previously been documented. The efficiency of the RAFT agents was compared in terms of rate effects, the predictability of the molecular weights of the polymers, the polydispersities of the polymers and their ability to allow block copolymer formation via sequential addition of monomers. Block copolymerizations were conducted by the addition of new monomer to the already existing RAFT end-capped chains. Monomer addition was done via three different approaches; namely shot addition, feed addition and pre-swelling (in the case of emulsions). Chromatographic analysis was conducted on the resulting block copolymers via liquid chromatography at critical conditions (LCCC), and its online coupling with size-exclusion chromatography (SEC) to obtain two-dimensional information on the differences in heterogeneity of their molecular distributions. Other analyses included dynamic light scattering analysis (DLS) and transmission electron microscopy (TEM). The detailed analysis enabled the understanding of the different products that are produced via the two different classes of RAFT agent. Potential causes for the differences are discussed and possible areas for future research are highlighted. The work presented here is the most detailed investigation of this class of polymerization to date and will provide new insight for researchers working in this vibrant and important research field. AFRIKAANSE OPSOMMING: Polimere gesintetiseer deur die gebruik van radikaal tegnieke is algemeen in ons daaglikse omgewing. Die tegniek is egter beperk deur die gebrek aan beheer oor die polimerisasie en die onvermoë om blokkopolimere te sintetiseer. Blokkopolimere beskik oor ‘n aansienlike hoeveelheid potensiele aanwendinge in gevorderde materiale en is gevolglik ‘n belangrike navorsingsgebied. Omkeerbare addisie fragmentasie ketting oordrag (OAFO) is ‘n lewende vrye radikaal proses wat die inherente nadele van die tradisionele proses oorkom. In die betrokke studie is die mediasie gedrag van twee verskillende OAFO agente bestudeer deur die lewende vrye radikaal polimerisasie van model monomere deur die OAFO proses in homogene en waterig dispersie media met die fokus op differensiering tussen die twee tipes agente. Om te verseker dat die twee agente vergelykbaar is, is ‘n nuwe OAFO agent voorberei wat tot op hede nog nie gedokumenteer is nie. Die effektiwiteit van die OAFO agente is vergelyk in terme van tempo effekte, die voorspelbaarheid van die molekulêre massa van die polimere, die polidispersiteit van die polimere en die moontlikheid om blokkopolimerisasie deur kronologiese byvoeging van monomere te fasiliteer. Blokkopolimerisasie is uitgevoer deur die byvoeging van nuwe monomeer tot die alreeds bestaande OAFO eind-groep kettings. Monomeer byvoegings is uitgevoer deur drie verskillende metodes; naamlik vulskoot addisie, voer addisie en vooraf swelling (in die geval van emulsies). Chromatografiese analise is uitgevoer op die resulterende blokkopolimere deur vloeistof chromatografie by kritieke kondisie (LC-CC) en die aanlyn koppeling met grootte-uitsluiting vloeistof chromatografie, om twee-dimensionele informasie omtrent die verskille in heterogeniteit van hul molekulere verdeling te bepaal. Verdere analise sluit dinamiese verstrooing mikroskopie en transmissie elektron mikroskopie in. Die detaileerde analise onthul die samestelling van die verskillende produkte wat geproduseer is deur die verskillende klasse van OAFO agent. Potensiele oorsake vir die verskille is bespreek en moontlike areas vir toekomstige navorsing is benadruk. Die werk hier voorgestel is die mees gedetaileerde navorsing van hierdie tipe klas van polymerisasie tot op hede en beloof nuwe insig vir navorsers betrokke in hierdie dinamiese en belangrike navorsingsveld. 2012-07-13T13:56:17Z 2012-07-13T13:56:17Z 2007-12 Thesis http://hdl.handle.net/10019.1/21699 en_ZA Stellenbosch University xxiii, 150 leaves : ill. application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Block copolymers Addition polymerization Theses -- Polymer science Dissertations -- Polymer science Pretorius, Nadine O. The investigation and analysis of RAFT-mediated block copolymers in aqueous dispersed media |
| title | The investigation and analysis of RAFT-mediated block copolymers in aqueous dispersed media |
| title_full | The investigation and analysis of RAFT-mediated block copolymers in aqueous dispersed media |
| title_fullStr | The investigation and analysis of RAFT-mediated block copolymers in aqueous dispersed media |
| title_full_unstemmed | The investigation and analysis of RAFT-mediated block copolymers in aqueous dispersed media |
| title_short | The investigation and analysis of RAFT-mediated block copolymers in aqueous dispersed media |
| title_sort | investigation and analysis of raft mediated block copolymers in aqueous dispersed media |
| topic | Block copolymers Addition polymerization Theses -- Polymer science Dissertations -- Polymer science |
| url | http://hdl.handle.net/10019.1/21699 |
| work_keys_str_mv | AT pretoriusnadineo theinvestigationandanalysisofraftmediatedblockcopolymersinaqueousdispersedmedia AT pretoriusnadineo investigationandanalysisofraftmediatedblockcopolymersinaqueousdispersedmedia |