Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.

Not available / text

Thesis (Ph.D.) -- McMaster University, 2003. / Includes bibliographical references (p. 154-172). Also available via World Wide Web.

Thesis (Ph.D) -- McMaster University, 1997. / Includes bibliographical references. Also available via World Wide Web.

Thesis (Ph.D.) -- McMaster University, 1998. / Includes bibliographical references. Also available via World Wide Web.

Thesis (Ph.D.) -- McMaster University, 2003. / Includes bibliographical references (p. 154-172). Also available via World Wide Web.

Thesis (MSc)--University of Stellenbosch, 2006. / Bibliography. Also available via the Internet.

The study of the polymerization of alkyl vinyl ethers initiated by HI/I₂ catalyst is directed into two areas: the kinetics of the polymerization and the strategy of amine functionalized prepolymer synthesis. The polymerization reactions show living behavior in nonpolar solvents at low temperatures. The observed rate of polymerization under reaction conditions is linearly dependent on the initial concentration of hydrogen iodide and iodine, respectively. However, the monomer concentration does not influence the rate of polymerization(apparent zero-order). Two possible reaction schemes are proposed from the observed rate equation and attempts are made to distinguish them by using UV/visible spectroscopy and carbon-13 NMR spectroscopy. In both schemes a reversible interaction between a monomer and an iodine molecule is postulated as a necessary elemental reaction to fit the observed expression for the rate of polymerization. From spectroscopic analysis results, the interaction between the iodide compound(chain end) and the iodine molecule seems to be very weak compared to the interaction between the monomer and the iodine molecule. A synthetic strategy for amine functionalized prepolymer synthesis has been developed via a series of model reactions. Incorporation of a styrenic monomer at the propagating chain end of living poly(alkyl vinyl ethers) provides a convenient intermediate synthesis of a relatively stable amine functionalized prepolymer. Proper selection of substituents at the styrenic monomer optimizes the cross addition reaction and amination reactions. Linear alkylamines with lower carbon numbers are used in the amination reaction in order to promote the nucleophilic substitution reaction and to minimize possible elimination reactions. A series of amine functionalized oligomers are synthesized by employing the synthetic strategy in combination with the previous kinetic result of the homopolymerization. For oligomers, incorporation of a few units of ethyl vinyl ethers at the chain end facilitates the cross addition reaction. Synthesized amines are characterized by various spectroscopic methods. Then, titrated molecular weights show good agreement with their theoretical molecular weights in several cases. / Ph. D.

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.

Thesis (PhD)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Synthetic polymers are complex compounds that have multiple distributions with regard to molar mass, chemical composition, functionality and molecular architecture. Therefore, the molecular complexity of these compounds can only be analysed using a combination of analytical techniques. Well-defined complex polymers can be prepared by different types of living radical polymerisation, including reversible addition–fragmentation chain transfer polymerisation (RAFT) and reverse iodine transfer polymerisation (RITP). Using these techniques, several different homopolymers and copolymers have been prepared. However, there is still space for some more extended research. Many different types of multifunctional RAFT agents have been reported in literature. A tetrafunctional RAFT agent was prepared in our laboratory and used for the first time in the polymerisation of styrene. The polymerisation reaction was followed using in situ 1H nuclear magnetic resonance (NMR) and the molar masses of the resultant polymers were determined using size exclusion chromatography (SEC). The molar masses of the star-shaped polystyrenes (PS) were found to be less than the theoretical molar masses. This was due to the fact that SEC was calibrated with linear PS standards, while the samples under investigation are branched. Linear and branched polymers have different hydrodynamic volumes at similar molar masses. In order to prove that the star-shaped polymers were in fact four-armed, the samples were cleaved by aminolysis to yield the linear PS arms. The molar masses of the arms were in agreement with the theoretical arm molar masses based in the fourarmed structure. RITP is a relatively new living radical polymerisation technique. Various monomers have been prepared using RITP, including acrylates, methacrylates and styrene. The polymers formed using this technique have been characterised by techniques such as SEC, NMR and mass spectrometry (MS). However, very little advanced characterisation work has been done on polymers synthesised via RITP. Polystyrene-block-poly(n-butyl acrylate) (PS-b-PBA) block copolymers were prepared via RITP and the microstructure analysed by in situ NMR and other advanced analytical techniques. The chromatograms from gradient HPLC of the PS-b-PBA block copolymers showed a separation based on chemical composition. The preparation of deuterated polymers via RITP has not been reported in literature. Hydrogenous-polystyrene-block-deuterated-polystyrene (hPS-b-dPS) was synthesised via RITP and analysed using liquid chromatography at critical conditions. An isotopic separation was achieved when critical conditions were established for hydrogenous PS (h-PS). A separation of the block copolymer from the first block was also achieved under chromatographic conditions where the block copolymer eluted in SEC mode while the first block eluted in LAC mode. The separation according to the block structure was confirmed by two-dimensional liquid chromatography. / AFRIKAANSE OPSOMMING: Sintetiese polimere is komplekse verbindings wat meervoudige verspreidings ten opsigte van molêre massa, chemiese samestelling, funksionaliteit en molekulêre argitektuur. Daarom kan die molekulêre kompleksiteit van hierdie verbindings net ontleed word met behulp van 'n kombinasie van analitiese tegnieke. Goed-gedefinieerde komplekse polimere kan voorberei word deur verskillende soorte lewende radikaal polimerisasie, insluitend omkeerbare addisie-fragmentasie kettingoordrag polimerisasie (OAFO) en omgekeerde jodium oordrag polimerisasie (OJOP). Met behulp van hierdie tegnieke, was verskeie homopolimere en kopolimeer opgestel. Maar daar is nog plek vir nog uitgebreide navorsing. Baie verskillende tipes multifunksionele OAFO agente is aangemeld in die letterkunde. Ons het 'n nuwe vier-armige OAFO agent in ons laboratorium voorberei en dit was vir die eerste keer in die polimerisasie van stireen gebruik. Die polimerisasie reaksie is gevolg met behulp van in situ 1H kernmagnetieseresonans (KMR) en die molêre massas van die gevolglike polimere was bepaal deur grootteuitsluitings chromatografie (SEC). Die molêre massas van die ster-polistireen (PS) is bevind as minder as teoretiese molêre massas. Dit is omdat SEC instrumente gekalibreer word met lineêre PS standaarde, terwyl die monsters wat tans ondersoek word vertakte polimere is. Lineêre en vertakte polimere het verskillende hidrodinamiese volumes by soortgelyke molêre massas. Ten einde te bewys dat die ster polimere in werklikheid vier-armig is, is die monsters gesny deur ‘n aminolisasiereaksie om die lineêre PS arms te lewer. Die molêre massas van die arms was ooreenkomstig met die teoretiese arm molêre massas gebaseer op die vier-armige struktuur. OJOP is 'n relatiewe nuuts lewende radikaal polimerisasie tegniek. Verskeie monomere is opgestel deur OJOP, insluitend akrilate, metakrilate en stireen. Die polimere wat gevorm is deur middel van die tegniek is al gekenmerk deur tegnieke soos SEC, KMR en massaspektrometrie (MS). Tog is daar baie min gevorderde karakterisering werk gedoen oor polimere gesintetiseer deur middel van OJOP. Polistireen-blok-poli(n-butylacrylaat) (PS-b-PBA) blokkopolimere was voorberei deur middel van OJOP en die mikrostruktuur ontleed met behulp van gevorderde analitiese tegnieke. Die chromatogramme van gradiënt HPLC van die PS-b-PBA blokkopolimere het 'n skeiding ondergaan gebaseer op die chemiese samestelling. Die voorbereiding van gedeutereerde polimere deur middel van OJOP word nie in die letterkunde gevind nie. Gehidrogeneerde-polistireen-blok-gedeutereerde-polistireen (hPS-b-dPS) is gesintetiseer deur middel van OJOP en ontleed met behulp van vloeistofchromatografie onder kritiese kondisies. 'n Isotopiese skeiding was bereik wanneer kritiese kondisies gestig is vir gehidrogeneerde PS (h-PS).'n Skeiding van die blok kopolimeer van die eerste blok was ook bereik onder chromatografiese omstandighede waar die blok kopolimeer elueer in SEC terwyl die eerste blok elueer in LAC. Die skeiding volgens die blok struktuur was bevestig deur twee-dimensionele vloeistofchromatografie.