Thesis (PhD)--Stellenbosch University, 2011. / ENGLISH ABSTRACT: Fully exfoliated polystyrene-clay nanocomposites were prepared via free radical polymerization in dispersion polymerization, in a mixture of ethanol and water. Sodium montomorillonite clay (MMT) was pre-modified using 3-(trimethoxysilyl) propyl methacrylate (MPTMS) before being used in a dispersion polymerization process. The particles obtained were not completely stable and TEM images showed that most of the clay platelets were distributed in the dispersing phase. A second objective included, the preparation of low molecular weight of polystyrene (PS) and amphiphilic block copolymers of poly(styrene-b-2-hydroxyethyl acrylate) (PS-b-PHEA)using reverse iodine transfer polymerization (RITP) living/controlled free radical polymerization.The reaction kinetic profile of the RITP process for styrene and 2-Hydroxyethyl acrylate (HEA) was also studied. The formation of the block copolymer PS-b-PHEA was confirmed by GPC and gradient HPLC. The resulting PS-I and (PS-b-PHEA)-I were chemically modified by dimethylethylamine and triethylamine respectively, ended with PS and PS-b-PHEA has quaternary ammonium end-chain functionality (PS-cationic and (PS-b-PHEA)-cationic). The obtained functional polymers (PS-cationic) and (PS-b-PHEA)-cationic) were then grafted onto MMT via a simple ion-exchange process to offer MMT with polymer chains on the surface (PS-MMT) and (PS-b-PHEA)-MMT). Furthermore, the ability of the interaction ofPS-b-PHEA with MMT by adsorption via several functional groups was also investigated. The third objectiveincluded the use of this new class of pre-modified clay PS-MMT in the preparation of PCNs as stabilizers, the clay particles were encapsulated into PS latexes with a partially exfoliated structure at 100% CEC, upon stoppage of the polymerization process, and the final dispersion found to be stable for up to 5 wt% of clay filler loading. The thermal and thermo-mechanical properties of PS-nanocomposites were found to be dependent on both nanocomposites morphology, and clay loading. (PS-b-PHEA)-MMT was also used as stabilizers in the preparation of PS via dispersion polymerization. PS colloidal particles obtained were found to be armoured by (PS-b-PHEA)-MMT layers, with particles sizes in the micro-size range, with fair stability were obtained for clay loadings up to 5%. Analysis of the structure and thermo-mechanical properties of the resulting PCNs revealed the efficiency of the clay surface pre-modification in stabilizing the system throughout the heterophasic polymerization process.The melt flow properties of final PCNs were found to be strongly dependent on the clay loading, with shift observed from liquid-like viscoelastic to solid-like viscoelastic behaviour as the clay content increased due to percolation of the clay network within the PS matrix taking place upon film formation above Tg. / AFRIKAANSE OPSOMMING: Die eerste doelwit was die voorbereiding van ten volle geëksfolieerde polistireen-klei nanosamestellings deur vrye radikaal polimerisasie in dispersie-polimerisasie, in 'n mengsel van etanol en water. Natrium montmorilloniet klei (MMT) is gemodifiseer deur gebruik te maak van 3-(trimetoksiesiliel) propiel metakrilaat (MPTMS), voordat dit gebruik is in die dispersie-polimerisasie. Die bekomde partikels was nie heeltemal stabiel nie. Transmissie elektronmikroskopie (TEM) resultate het getoon dat die meeste van die klei plaatjies in die dispersie-fase versprei is. Die tweede doelwit was die voorbereiding van polistireen (PS) met 'n lae molekulêre massa, gevolg deur die vorming van amfifiliese blok kopolimere van poli(stireen-b-2-hidroksie-etiel akrilaat) (PS-b-PHEA) met behulp van omgekeerde jodium oordrag polimerisasie (RITP) lewendige/gekontroleerde vrye radikaal polimerisasie. Die reaksie kinetiese profiel van die RITP proses was bestudeer met betrekking tot stireen en 2-hidroksie-etiel akrilaat (HEA). Die vorming van die blok kopolimeer PS-b-PHEA is bevestig deur GPC en gradiënt HPLC. Die gevolglike PS-I en (PS-b-PHEA)-I was chemies gewysig deur onderskeidelik dimetieletielamien en trietielamien, waardeur PS en PS-b-PHEA een kwaternêre ammonium ketting-endfunksionaliteit bekom het (PS-kationies en (PS-b- PHEA)-kationies). Laasgenoemde twee funksionele polimere was toe gekoppel aan MMT deur 'n eenvoudige ioon-ruilingsproses wat MMT met polimeerkettings op die oppervlak (PS-MMT) en (PS-b-PHEA)-MMT) tot gevolg het. Die interaksie van PS-b-PHEA met MMT deur middel van adsorpsie van verskeie funksionele groepe is ook ondersoek. Die derde doel was gerig op die gebruik van hierdie nuwe klas gemodifiseerde klei PS-MMT as stabiliseerders vir die voorbereiding van polimeer-klei-nanosamestellings (PCNs). Die 100% CEC gemodifiseerde klei deeltjies is ge-inkapsuleer in die PS emulsies met 'n gedeeltelik geëksfolieërde struktuur, na afloop van die polimerisasie proses. Die finale dispersie was stabiel tot en met 'n klei inhoud van 5 wt%. Daar is gevind dat die termiese en termo-meganiese eienskappevan die PS-nanosamestellings afhanklik is van beide die morfologie en die klei inhoud. (PS-b-PHEA)-MMT was ook gebruik as stabiliseerder in die voorbereiding van PS deur dispersie polimerisasie. Daar is gevind dat die PS kolloïdale partikels wat verkry is, versterk was deur (PS-b-PHEA)-MMT lae. Partikel groottes was in die mikro-grootte gebied, en voldoende stabiliteit is verkry vir 'n klei inhoud van tot 5%. Analise van die struktuur en die termo-meganiese eienskappe van die bekomde PCNs het getoon dat die vooraf modifisering van die klei oppervlak doeltreffend was in die stabilisering van die sisteem gedurende die heterofase polimerisasie proses. Daar is ook gevind dat die smelt vloei eienskappe van die finale PCNs sterk afhang van die klei inhoud; 'n verskuiwing vanaf vloeistof-agtige viskoelastiese tot vaste-agtige viskoelastiese gedrag is waargeneem soos die klei-inhoud verhoog. Hierdie verskynsel was te danke aan perkolasie van die klei netwerk binne die PS matriks wat plaasvind tydens film vorming by 'n hoër temperatuur as die glasoorgangstemperatuur (Tg).

Thesis (PhD)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: New methods are described for the synthesis of polymer/graphite nanocomposites using the miniemulsion polymerization process. Natural graphite was functionalized by oxidation to produce graphite oxide (GO) nanosheets. Poly(styrene-co-butyl acrylate) (poly(St-co-BA)) nanocomposite latices containing GO nanosheets were successfully synthesized using miniemulsion as a one-step nano-incorporation technique. The approach followed included expanding the GO nanosheets in situ during the miniemulsification step and then polymerizing the monomers in the presence of these expanded nanosheets. Styrene (St) and butyl acrylate (BA) were mixed with GO and then emulsified in the presence of a surfactant and a hydrophobe to afford pre-miniemulsion latex particles. The stable pre-miniemulsions were then polymerized to yield poly(St-co-BA)/GO nanocomposite latices. The polymerization proceeded with relatively high monomer conversion and produced stable nanocomposite latex particles. The nanocomposites exhibited mainly an intercalated morphology, irrespective of the percentage of GO filler loading. The synthesis of exfoliated polymer nanocomposites made with modified GO is described. GO was modified with a surfmer (reactive surfactant), 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS), which widened the gap between the GO nanosheets and facilitated monomer intercalation between its nanogalleries. The AMPS-modified GO was used for the synthesis of poly(St-co-BA)/GO nanocomposite latices using a similar miniemulsion procedure. The obtained nanocomposites had exfoliated morphologies and the GO nanosheets were largely exfoliated (about 2–5 nm thick) in the resultant films obtained from the synthesized nanocomposite latices. The synthesized nanocomposites had enhanced thermal and mechanical properties compared to pure polymer as a result of the presence of AMPSmodified GO. Furthermore, the nanocomposites made with AMPS-modified GO had better thermal and mechanical properties than the unmodified GO. The mechanical properties of the nanocomposites depended on the AMPS-modified GO loading in the nanocomposites. The synthesis of polystyrene/GO (PS-GO) nanocomposites using the reversible additionfragmentation chain transfer (RAFT) mediated polymerization method is also described. The GO was synthesized and immobilized with a RAFT agent to afford RAFT-functionalized GO nanosheets. The RAFT-immobilized GO was used for the synthesis of PS nanocomposites in a controlled manner using miniemulsion polymerization. The molar mass and dispersity of the PS in the nanocomposites depended on the amount of RAFT-grafted GO in the system, in accordance with the features of the RAFT-mediated polymerization. X-ray diffraction and transmission electron microscopy analyses revealed that the nanocomposites had exfoliated morphology, even at relatively high GO content. The thermal stability and mechanical properties of the PS-GO nanocomposites were better than those of the neat PS polymer. Furthermore, the mechanical properties were dependent on the modified-GO content (i.e., the amount of RAFT-grafted GO). The hydrophobicity and barrier properties of the resulting films prepared from the synthesized poly(St-co-BA)/GO nanocomposite latices to water and water vapor were also investigated. The hydrophobicity of the synthesized nanocomposite films was determined using contact angle measurements. The water permeability was determined by measuring the moisture vapor transmission rate of the films. The GO in the nanocomposites was reduced to its original form (i.e., graphite), and the barrier properties of the obtained nanocomposite films were determined and compared to films containing the unmodified GO (as-prepared GO). Results showed that reduction of GO had a significant impact on the water affinity of the resultant films prepared from the synthesized nanocomposite latices. The presence of reduced-GO (RGO) instead of unmodified GO in the miniemulsion formulation significantly improved the hydrophobicity and barrier properties of the final films to water. However, the barrier properties of the nanocomposites were unaffected by the amount of RGO in the nanocomposites. / AFRIKAANSE OPSOMMING: Nuwe metodes is beskryf vir die sintese van polimeer/grafiet nanosamestellings deur gebruik te maak van die miniemulsie polimerisasieproses. Natuurlike grafiet is gefunksionaliseer dmv oksidasie om grafietoksied (GO) nanovelle te vorm. Polistireen-ko-butielakrilaat (poli[St-ko- BA]) nanosamestellinglatekse wat GO nanovelle bevat is suksesvol gesintetiseer deur gebruik te maak van miniemulsie polimerisasie as ‘n een-stap nano-insluitingstegniek. Die benadering wat gevolg is het die uitbreiding van die GO nanovelle, in situ, gedurende die miniemulsifiseringstap behels, gevolg deur die polimerisasie van die monomere in die teenwoordigheid van hierdie uitgebreide nanovelle. Stireen (St) en butielakrilaat (BA) is met GO gemeng en daarna emulgeer in die teenwoordigheid van ‘n seepmiddel (surfactant) en ‘n hidrofoob om pre-miniemulsielateksdeeltjies te lewer. Die stabiele pre-miniemulsies is gepolimeriseer om poli(St-ko-BA)/GO nanosamestellinglatekse te vorm. Die polimerisasie het met redelike hoë monomeeromskakeling verloop en het stabiele nanosamestellinglateksdeeltjies gelewer. Hierdie nanosamestellings het hoofsaaklik geïnterkaleerde morfologie, onafhanklik van die persentasie GO vullers, getoon. Die sintese van afgeskilferde polimeernanosamestellings berei met gewysigde GO is beskryf. GO is gewysig met ‘n ‘surfmer’ (reaktiewe seepmiddel), 2-akrielamido-2-metiel-1- propaansulfoonsuur (AMPS), wat die gapings tussen die GO nanovelle vergroot het en die monomeer interkalering tusssen sy nanogange fasiliteer. Die AMPS-gewysigde GO is gebruik vir die sintese van poli(St-ko-BA)/GO nanosamestellinglatekse deur gebruik te maak van ‘n soortgelyke miniemulsie prosedure. Die nanosamestelling sό verkry het ‘n afgeskilferde morfologie getoon en die GO nanovelle was grootendeels afgeskilfer (ongeveer 2–5 nm dik) in die films wat berei is van die gesintetiseerde nanosamestellinglatekse. Laasgenoemde het verhoogde termiese en meganiese eienskappe gehad in vergelyking met die suiwer polimeer, as gevolg van die teenwoordigheid van die AMPS-gewysigde-GO. Die meganiese eienskappe van die nanosamestellings hang af van persentasie AMPS-gewysigde GO vullers in die nanosamestellings. Die sintese van PSt/GO nanosamestellings dmv die omkeerbare-addisie-fragmentasieoordrag- (OAFO-, Eng. RAFT-) bemiddelde polimerisasie metode is ook beskryf. Die GO is berei en geïmmobiliseer met ‘n RAFT verbinding om GO nanovelle met RAFT funksionaliteit te lewer. Die RAFT-geïmmobiliseerde GO is gebruik vir die sintese van PSt nanosamestellings in ‘n gekontrolleerde manier mbv miniemulsie polimerisasie. Die molêre massa en dispersie van die PSt in die nanosamestellings hang af van die hoeveelheid RAFTgeënte GO in die sisteem, in ooreenstmming met die kenmerke van RAFT-bemiddelde polimerisasie. X-straaldiffraksie en transmissie-elektronmikroskopie analises het bewys dat die nanosamestellings, selfs by relatiewe hoë GO inhoud, ‘n afgeskilferde morfologie gehad het. Die termiese stabiliteit en meganiese eienskappe van die PSt-GO nanosamestellings was beter as dié van die suiwer PSt polimeer. Verder was die meganiese eienskappe afhanklik van die gewysigde-GO-inhoud (dws, die hoeveelheid RAFT-geënte-GO). Die hidrofobisiteit en spereienskappe van die films berei vanaf die gesintetiseerde poli(St-ko- BA)/GO nanosamestellinglatekse teenoor water en waterdamp is ook ondersoek. Die hidrofobisiteit is ondersoek deur gebruik te maak van kontakhoekmeting. Die waterdeurlaatbaarheid is bepaal deur die waterdampoordragtempo van die films te bepaal. Die GO in die nanosamestellings is gereduseer tot sy eenvoudigste vorm (grafiet) en die spereienskappe van die nanosamestellingfilms is bepaal en vergelyk met die films wat die ongewysigde GO bevat het. Resultate het getoon dat reduksie van GO ‘n groot invloed gehad het op die wateraffiniteit van die films wat berei is vanaf die gesintetiseerde nanosamestellinglatekse. Die teenwoordigheid van die gereduseerde-GO (RGO) in plaas van die onveranderde GO in die miniemulsie formulasie het die hidrofobisiteit en spereienskappe van die finale films, teenoor water, baie verbeter. Die spereienskappe van die nanosamestellings is egter nie beïnvloed deur die hoeveelheid RGO in die nanosamestellings nie.

Thesis (PhD)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The primary aim of this study was to investigate the feasibility of the amphiphilic block copolymer poly((vinylpyrrolidone)-b-poly(vinyl acetate)) (PVP-b-PVAc) as a vehicle for hydrophobic anti-cancer drugs. PVP-b-PVAc block copolymers of constant hydrophilic PVP block length and varying hydrophobic PVAc block lengths were synthesized via xanthate-mediated controlled radical polymerization (CRP). The methodology consisted of growing the PVAc chain from a xanthate end-functional PVP. In an aqueous environment the amphiphilic block copolymers selfassembled into spherical vesicle-like structures consisting of a hydrophobic PVAc bilayer membrane, a hydrophilic PVP corona and an aqueous core. The self-assembly behaviour and the physicochemical properties of the self-assembled structures were investigated by 1H NMR spectroscopy, fluorescence spectroscopy, transmission electron microscopy (TEM) and dynamic and static light scattering. Drug loading studies were performed using a model hydrophobic drug, clofazimine, and a common anti-cancer drug paclitaxel (PTX) to evaluate the potential of the PVP-b-PVAc block copolymers for drug delivery,. Clofazimine and PTX were physically entrapped into the hydrophobic domain of the self-assembled PVP-b-PVAc block copolymers via the dialysis method. The drug-loaded PVP-b-PVAc block copolymers were characterized regarding particle size, morphology, stability and drug loading capacity in order to assess their feasibility as a drug vehicle. The polymer vesicles had a relatively high drug loading capacity of 20 wt %. The effect of the hydrophobic PVAc block length on the drug loading capacity and encapsulation efficiency were also studied. Drug loading increased with increasing the hydrophobic PVAc block length. The effect of the drug feed ratio of clofazimine and PTX on the drug loading capacity and encapsulation efficiency were also investigated. The optimal formulation for the drug-loaded PVP-b-PVAc was determined and further investigated in vitro. The size stability of the drugloaded PVP-b-PVAc block copolymers was also assessed under physiological conditions (PBS, pH 7.4, 37 °C) and were stable in the absence and presence of serum. PVP-b-PVAc block copolymers were tested in vitro on MDA-MB-231 multi-drug-resistant human breast epithelial cancer cells and normal MCF12A breast epithelial cells to provide evidence of their antitumor efficacy. In vitro cell culture studies revealed that the PVP-b-PVAc drug carrier exhibited no cytotoxicity towards MDA-MB-231 and MCF12A cells, confirming the biocompatibility of the PVP-b-PVAc carrier. In vitro cytotoxicity assays using clofazimine-PVPb- PVAc formulations showed that when MDA-MB-231 cells were exposed to the formulations, an enhanced therapeutic effect was observed compared to the free drug. Cellular internalization of the PVP-b-PVAc drug carrier was demonstrated by fluorescent labeling of the PVP-b-PVAc carrier. Fluorescence microscopy results showed that the carrier was internalized by the MDAMB- 231 cells after 3 hours and localized in the cytoplasm and the perinuclear region. Overall, it was demonstrated that PVP-b-PVAc block copolymers appear to be promising candidates for the delivery of hydrophobic anti-cancer drugs. / AFRIKAANSE OPSOMMING: Die studie is gebaseer op die gebruik van amfifieliese blokkopolimere van poli((Nvinielpirolidoon)- b-poli(vinielasetaat)) (PVP-b-PVAc) as potensiële geneesmiddeldraers. PVP-b-PVAc blokkopolimere van konstante hydrofiliese bloklengte en verskillende hydrofobiese bloklengte is voorberei via die RAFT/MADIX-proses. Blokkopolimere met vinielasetaat is vanaf poli(N-vinielpirolidoon) met ‘n xantaatendfunksie voorberei. In ‘n wateromgewing vorm die PVP-b-PVAc blokkopolimere vesikel strukture met ‘n hydrofobiese membraan en ‘n hydrofiliese mantel. Die fisies-chemiese eienskappe van die PVP-b-PVAc blokkopolimere is gekarakteriseerd met gebruik van KMR spektroskopie, fluoresent spektroskopie, transmissie elektronmikroskopie (TEM) en dinamiese en statiese lig verstrooiing. Die potensiaal van PVP-b-PVAc as ‘n geneesmiddeldraer is ondersoek deur gebruik te maak van die hydrofobiese geneesmiddel, clofazimine, en ‘n anti-kanker geneesmiddel, paclitaxel. Clofazimine en paclitaxel is ge-inkapsuleer in die hydrofobiese gedeelte van die blokkopolimere via die dialise-metode. Clofazimine-PVP-b-PVAc en paclitaxel-PVPb- PVAc blokkopolimere is gekarakteriseerd met betrekking tot die partikel grootte, morfologie, stabiliteit en laai kapasitiet om die PVP-b-PVAc blokkopolimere as geneesmiddeldraers te evalueer. Die PVP-b-PVAc geneesmiddeldraer het ‘n relatiewe hoë laai kapsiteit van 20 gew % aangetoon. Die invloed van die bloklengte op die laai kapasitiet is ook ondersoek en beskryf. ‘n Toename in die laai kapasitiet is gesien met ‘n toename in die hydrofobiese bloklengte. Die invloed van die hoeveelheid geneesmiddel op die laai kapasitiet en die inkapsuleer doeltreffendheid is ook ondersoek. Die optimale formulasie is gevind en verder gebruik vir in vitro studies. Die stabiliteit van die geneesmiddeldraer in fisiologiese omstandighede (pH 7.4, 37 °C) is ook beskryf. Resultate toon aan dat die sisteem stabiel is onder hierdie omstandighede in die afwesigheid en aanwesigheid van serum. In vitro eksperimente is op MCF12A epiteel-borsselle en MDA-MB-231 epiteelborskankerselle getoets om die anti-tumoraktiwiteit te ondersoek. Resultate toon aan dat die PVP-b-PVAc geen sitotoxiese effek op die selle het nie, wat aandui dat die polimere bioverenigbaar is. Verder is dit bewys dat die PVP-b-PVAc geneesmiddel formualsie ’n hoër sitotoxisiteit besit as die vry-geneesmiddel. Fluoresent studies het aangetoon dat die geneesmiddeldraer na 3 uur opgeneen word deur MDA-MB231 selle en gelokaliseerd is in die sitoplasma en in die omgewing van die kern van die selle. In die algemeen is dit aangetoon dat PVP-b-PVAc blokkopolimere potensiële kandidate vir die lewering van hydrofobiese geneesmiddels is.

Thesis (PhD)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Please refer to full text for abstract / AFRIKAANSE OPSOMMING: Sien volteks vir opsomming

Thesis (PhD (Chemistry and Polymer Science))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Different click chemistry methods have been used together with Reversible Addition- Fragmentation chain Transfer (RAFT) mediated polymerization to synthesize macromolecular architectures. A new leaving group for RAFT was introduced. This triazole leaving group allows for easy conjugation of the RAFT agent to various substrates via the copperI catalyzed Huisgen 1,3-dipolar cycloaddition reaction. Subsequently monomer can be polymerized onto the substrate using the RAFT agent. This connects the polymer to the substrate via a hydrolytically stable 1,2,3-triazole. The Mitsunobu reaction was used to chain-end functionalize polymers. The Mitsunobu reaction allows for the substitution of primary and secondary alcohols with a nucleophile. The modification of polymer chain-ends was done in two ways. Firstly, thiol-functional chain-ends were used as the nucleophile in the Mitsunobu reaction using propargyl alcohol as the alcohol. This yielded alkyne-functional polymers. Thiol chain-end functional polymers were obtained by the aminolysis of polymers synthesized via RAFT. Secondly, alcohol-functional polymers were modified. In the case of poly(vinylpyrrolidone), the RAFT group was hydrolyzed and alcohols were obtained. Hydroxyl functional PEG was obtained commercially. The hydroxyl functionality was reacted in the Mitsunobu reaction using hydrazoic acid (HN3) as the nucleophile. Azide chain end functional polymers were obtained. These alkyne and azide chain end functional polymers were subsequently used in the copperI catalyzed Huisgen 1,3-dipolar cycloaddition reaction. Ultra Fast Hetero Diels-Alder click chemistry (UFHDA) was used to synthesizes norbornenelike structures (substituted 2-thiabicyclo[2.2.1]hept-5-ene moieties). Norbornene-like structures can be polymerized via Ring Opening Metathesis Polymerization (ROMP). Monomers were synthesized using phenethyl(diethoxyphosphoryl)dithioformate and cyclopentadiene. Macromonomers were obtained from the UFHDA of Polystyrene (PSTY) synthesized via RAFT, using phenethyl(diethoxyphosphoryl) dithioformate as the RAFT agent, and cyclopentadiene or cyclopentadienyl-terminated PEG as the dienes. The obtained (macro) monomers were homo- and copolymerized using Ring Opening Metathesis Polymerization (ROMP). For the ROMP, four different Grubbs type catalysts were tested.The ring-strain promoted Huisgen 1,3-dipolar cycloaddition reaction uses cyclooctynes as the alkyne. The ring-strain in this molecule allows for a fast reaction at room temperature. This reaction is potentially very interesting for biological applications because it doesn’t require the toxic copper catalyst. In this work three routes towards cyclooctynes are investigated. PEG was chain end functionalized with the obtained cyclooctyne derivatives. Overall, click chemistry methodologies were applied to synthesize different macromolecular architectures. Results include a new type of RAFT agent that allows for easy conjugation to substrates, reaction methods for chain end modification of polymers, and the synthesis of new monomers and polymers. / AFRIKAANSE OPSOMMING: Verskillende kliek chemie metodes, tesame met Omkeerbare Addisie Fragmentasie ketting Oordrag beheerde polimerisasie (OAFO), is gebruik vir die sintese van makromolekulêre argitekture. ʼn Nuwe verlatende groep vir OAFO was bekend gestel. Die triazool verlatende groep bied die moontlikheid vir gemaklike koppeling van die OAFO agente met ‘n verskeidenheid van substrate via die koperI gekataliseerde Huisgen 1,3-dipolêre siklo-addisie reaksie. Gevolglik kan monomere gepolimeriseer word op die substraat deur middel van die OAFO agent. Dit laat toe vir die koppeling van die polimeer op die substraat via a hidrolitiese stabiele 1,2,3-triazool. Die Mitsunobu reaksie was gebruik vir die funksionaliseering van die end groepe van die polimeer ketting. Die Mitsunobu reaksie laat toe vir die substitusie van primêre en sekondêre alkohole met ‘n nukleofiel. Die verandering van die polimeer ketting end groepe was uitgevoer op twee verskillende maniere. Eerstens is ketting end groepe met ‘n tiol funktionaliteit gebruik as a nukleofiel in die Mitsunobu reaksie deur gebruik te maak van propargiel alkohol as die alkohol. Dit het alkyn funktionele polimere opgelewer. Tiol ketting end funktionele polimere was verkry deur middel van aminolise van die polimere gesintetiseer via OAFA. Tweedens is alkohol funktionele polimere gemodifiseer. In die geval van poli(N-vinielpirolidoon) is die OAFA grope gehidroliseer en gevolglik is alkohole verkry op hierdie manier. Kommersiële funksionele PEG was gebruik. Die hidroksie funksionele groep was gereageer in die Mitsunobu reaksie deur gebruik te maak van waterstof asied (HN3) as die nukleofiel. Dit het asied funksionele ketting eindes opgelewer. Die alkyne en asied ketting end funksionele polimere was gevolglik gebruik in die koperI gekataliseerde Huisgen 1,3- dipolêre siklo-addisie reaksie. Ultra Vinnige Hetero Diels-Alder kliek chemie (UVHDA) was gebruik vir die sintese van norborneen agtige strukture (gesubstitueerde 2-tiabisiklo[2.2.1]hept-5-een groepe). Monomere was gesintetiseer deur gebruik te maak van fenieletiel(di-etoksifosforiel)di-tioformaat en siklopentadiëen of siklopentadiëen-getermineerde PEG. Die sintese van makromonomere is verkry via UVHDA deur gebruik te maak van polistireen, gesintetiseer deur middel van OAFO (waar fenieletiel(dietoksifosforiel) di-tioformaat gebruik is as OAFO agent), en siklopentadiëen of siklopentadiëengetermineerde PEG. Die makromonomere wat verkry is, is verder gebruik vir homo- en kopolimerisasie deur middel van Ring Opening Metatesis Polimerisasie, ROMP. Vir die ROMP is vier verskillende Grubbs tipe kataliste gebruik. Die ring-spanning bevorderde die Huisgen 1,3,-dipolêre siklo-addissie reaksie waar siklooketyne gebruik is as die alkyne. Die ring-spanning in die molekule laat toe vir vinninge reaksies by kamer temperatuur. Die reaksie het die potensiaal vir interessante biologiese toepassings aangesien dit nie ’n kopper katalis vereis nie wat toksies van aard is. In die studie word drie roetes ten einde to siko-oktyn ondersoek. PEG was geketting end gefunksionaliseerd met die gevolgde siko-oktyne afgeleides. Verskillende kliek chemie metodologiëe was toegepas vir die sintese van verskillende makromolekulêre argitekture. Resultate sluit in een nuwe tipe OAFO agent wat maklike konjugasie met substrate bewerkstellig, ketting einde modifikasie van polimere, nuwe monomere en polimere wat gesintetiseer is.

Thesis (PhD (Chemistry and Polymer Science))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Living chains prepared by RAFT polymerization and NMP reactions using Z-carboxylate and Z-phosphate RAFT agents, and X-phosphate NMP initiators, were efficiently attached to the surface of magnetic nanoparticles (MNPs) and used for the separation of dead chains formed in these polymerization reactions prior to the attachment of the RAFT agents and NMP initiators to the surface of MNPs. All the living chains that attach selectively to the surface of MNPs contained RAFT or NMP functionalities, had a low polydispersity index (PDI), and could be reactivated to form new polymer extensions or block copolymers with no detectable deviation from 100% efficiency. RAFT chains prepared by RAFT polymerization using the Z-carboxylate RAFT agent and an excess of free radical initiator were also attached to the surface of MNPs and separated in the presence of an external magnetic field. Separated RAFT-functional chains contained no dead chains formed by combination or disproportionation reactions, but a substantial amount of cross-terminated by-product with a low UV absorbance at 320 nm. The cross-termination of the intermediate radical formed in the RAFT polymerization reactions was also investigated in the monomer-excluded free radical reaction model of polystyryl benzyl-(4-carboxyl dithiobenzoate) and polystyryl ethyl-2-bromoisobutyrate. The Z-carboxylate 3- and 4-arm star polymers (formed by cross-termination reactions) were then efficiently attached to the surface of MNPs and separated from the remainder of the polymer solution. They were separated from MNPs and characterized by 1H and 13C-NMR spectroscopy, and MALDI-ToF-MS. Living chains prepared by a RAFT miniemulsion polymerization reaction using Z-carboxylate RAFT agent were attached to the surface of MNPs and used for the separation of all dead chains and uncontrolled high molecular weight polymer of secondary particle formations occur during a miniemulsion polymerization reaction prior to the attachment. Separated dead chains had high PDI values and contained a significant fraction of uncontrolled high molecular weight polymer that lacked RAFT functionality. Initiator-derived chains formed in RAFT polymerization reactions of styrene (St) and methyl methacrylate (MMA) using phosphate free radical (PFR) initiator were selectively attached to the surface of MNPs and separated from R-group-derived polymer chains in the presence of an external magnetic field. All separated initiator-derived chains contained large fractions of dead chains with weak UV absorbance, and which lacked RAFT functionality, and small fractions of RAFT polymer chains. The separated initiator-derived chains had higher PDI values than the as-prepared polymer in the polymerization of St, but lower PDI values than the as-prepared polymer in the polymerization of MMA. RAFT agents attached to the surface of MNPs by the Z group were used as mediating agents for the synthesis of polymers grafted to the surface of MNPs. The polymers grafted to the surface of MNPs were separated from the solution of the free polymer by applying an external magnetic field. The amounts of the polymers grafted to the surface of MNPs greatly increased as the number of RAFT agents attached to the surface of MNPs decreased. When ethyl acetate was used as solvent, it reached 65% by weight and 50% by number of chains. Separated polymers grafted to the surface of MNPs had high PDI values and contained RAFT functionality. Investigations into the kinetics of the RAFT-mediated polymerization reaction on the surface of MNPs revealed that the polymerization reaction mediated using a RAFT agent attached by its Z group to the surface of MNPs had a faster polymerization rate than that mediated using a free Z group RAFT agent. The molecular weight of the grafted polymer increased linearly with conversion, and the reaction rate was pseudo-first-order. / AFRIKAANSE OPSOMMING: Lewende polimeerkettings, berei deur middel van RAFT-beheerde polimerisasie en NMP reaksies waarin Z-karboksilaat en Z-fosfaat RAFT-verbindings en 'n X-fosfaat NMP afsetter gebruik is, is geheg aan die oppervlaktes van magnetisenanopartikels (MNPs), en gebruik vir die skeiding van dooie kettings wat tydens die RAFT en NMP reaksies gevorm is. Alle lewende kettings wat aan die oppervlakte van die MNPs geheg is, is geskei van die oorblywende polimeeroplossing deur die aanwending van ‗n eksterne magnetise veld. Alle kettings wat selektief aan die oppervlaktes van die MNPs gekoppel is met RAFT of NMP funksionaliteit, het ‗n laë poliverspreidingswaarde (PDI) gehad en kon heraktiveer word om ‗n nuwe polimeerverlengings of blokkopolimere te vorm met geen merkbare afwyking van 100% doeltreffendheid nie. RAFT-kettings wat gedurende RAFT-polimerisasie met 'n Z-karboksilaat RAFT-agent en oormaat vrye-radikaalafsetter berei is, is ook geheg aan die oppervlaktes van MNPs en geskei in die teenwoordigheid van 'n eksterne magnetiese veld. Die geskeide RAFT-funksionele kettings het geen dooie kettings bevat nie (gevorm deur kombinasie reaksies), maar 'n aansienlike hoeveelheid ongekontroleerde hoë molekulêremassa polimeer (met lae UV absorpsie by 320 nm). Die kruis-beëindiging van die intermediêre radikaal wat gevorm is tydens die RAFT-proses is ondersoek in die monomeer-uitsluitende vrye-radikaalreaksiemodel van polistirielbensiel-4-karboksielditiobensoaat en polistirieletiel-2-bromoisobutiraat. Die Z-karboksilaat 3- en 4-arm sterpolimere (gevorm a.g.v. kruis-terminasiereaksies) is effektief geheg aan die oppervlaktes van MNPs en geskei van die res van die polimeeroplossing, en daarna gekarakteriseer met behulp van 1H en 13C KMR, en MALDI-ToF-MS. Lewende kettings, berei m.b.v. RAFT miniemulsiepolimerisasies met 'n Z-karboksilaat RAFT-agent, is geheg aan die oppervlaktes van MNPs en gebruik vir die skeiding van alle dooie kettings en sekondêre partikels wat tydens die reaksie voor die aanhegting gevorm het. Die geskeide dooie kettings wat agtergebly het, het 'n wye PDI getoon en het 'n aansienlike hoeveelheid ongekontroleerde hoë molekulêremassa polimeer, met geen RAFT-funksionaliteit nie, bevat. Afsetterafkomstigekettings wat gevorm is tydens die RAFT polimerisasiereaksies van stireen (St) en metielmetakrilaat (MMA) met 'n fosfaat-vrye vrye-radikaalafsetter is selektief geheg aan die oppervlaktes van MNPs en geskei van R-groep-afkomstige polimeerkettings in die teenwoordigheid van 'n eksterne magnetise veld. Alle geskeide afsetter-afkomstige kettings het 'n groot hoeveelheid dooie kettings gehad (met swak UV absorpsie) en met geen RAFT-funksionalilteit nie, en klein fraksies van RAFT-polimeerkettings. Die geskeide afsetter-afkomstige kettings het hoër PDI waardes gehad as die ('as-prepared') polimeer in die polimerisasie van St, maar laer PDI waardes as die ('as-prepared') polimeer in die polimerisasie van MMA. RAFT-verbindings wat aan die oppervlaktes van die MNPs geheg is deur middel van die Z-groep is as bemiddellingsagente (Eng: mediating agents) gebruik vir die sintese van polimere wat geënt is aan die oppervlakte aan MNPs. Die polimere wat aan die oppervlakte van die MNPs geënt is is geskei van die res van die polimeeroplossing deur die aanwending van ‗n eksterne magnetise veld. Die hoeveelhede van die polimere wat aan die oppervlaktes van die MNPs geënt is het sterk toegeneem namate die aantal RAFT-agente wat aan die oppervlaktes van MNPs geheg is afgeneem het. Wanneer etielasetaat as oplosmiddel gebruik is, was die waardes 55% m.b.t. gewig en 45% m.b.t. die aantal kettings. Die geskeide polimere wat aan die oppervlaktes van MNPs geënt is het hoë PDI getoon en het RAFT-funksionaliteit bevat. Die kinetika van die RAFT-beheerde polimerisasiereaksies van St, wat gebruik maak van ‗n RAFT-agent wat aan die oppervlakte van die MNPs geheg is deur middel van die Z-groep, is ook ondersoek. Die tempo van polimerisasie was vinniger in die geval waarin die RAFT-agent geheg is deur sy Z-groep aan die oppervlakte van die MNPs as die reaksie met 'n RAFT agent met 'n vrye Z-groep. Die molekulêremassas van die entpolimere het liniêr toegeneem met omsetting, en die reaksie was pseudo-eerste-orde.

Thesis (PhD (Chemistry and Polymer Science))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Polydimethylsiloxane–polyester (PDMS-PES) copolymers produce materials which have enhanced properties and take advantage of the unique properties of the two very dissimilar components. The dissimilar nature of the components results in these types of materials typically having complex morphologies in the solid state as a result of phase segregation. When the polyester component is crystallisable, an even richer variation in morphology can be expected. The chain structure of the copolymer in terms of the distribution of the various segments along the chain and the variation in the composition also has a dramatic impact on the solid state morphology. In this study, two different types of polyesters were used to synthesise five series of PDMS-PES segmented copolymers and one series of PDMS-PES branched copolymer. The two polyester segments selected were polybutyleneadipate (PBA) and polybuthylenecyclohexancarboxylate (PBCH). The copolymers were synthesised via polycondensation in the melt state. Insights on many variations in the PDMS-PES copolymer synthesis are given. The copolymer series synthesized gave systematic series where the influence of the polyester type, chain architecture, bulk composition, block length, crystallinity and processing condition on the bulk and surface morphology could be studied. The remarkable variations in the properties of the copolymer were attributed to the differences in the copolymers morphology in terms of the microphase segregation, crystallization and the free volume properties. These variations were also found to alter the nature of the surface compositions and the related surface properties. Multiphase morphology exhibited in all the PDMS-PES copolymers and the type of morphology observed was dependent on PDMS contents, PDMS segment length and the degree of branching. Three types of morphology were observed: spherical micro-domains of PDMS in a matrix of PES, bicontinuous double diamond type morphology, and spherical micro-domains of PES in a matrix of PDMS. Spherical domains of the PDMS were also observed for low PDMS content copolymers between the crystalline polyester lamellae. The complexity of the PDMS-PBCH copolymer morphology was further investigated, using an extensive set of experimental data that has been drawn together with using positron annihilation lifetime spectroscopy (PALS) and developing and applying a new type of hyphenated technique between fractionation (chromatography) and microscopy (atomic force microscopy) techniques. The outcome has provided a unique perspective regarding the complexity of the PDMS-PBCH copolymer morphology, which is believed to provide basis for a theoretical structure-properties relationship in this fascinating class of thermoplastic material. / AFRIKAANSE OPSOMMING: Polidimetielsiloksaan–poliëster (PDMS–PES) kopolimere lewer verbindings met goeie eienskappe en trek voordeel uit die unieke eienskappe van die twee baie verskillende komponente. Aangesien die aard van hierdie twee verbindings baie verskil het hulle ‘n gekompliseerde morfologie in die vastetoestand as gevolg van faseskeiding. Wanneer die poliëster komponent kristalliseerbaar is kan ‘n nog ryker variasie in morfologie verwag word. Die kettingstruktuur van die kopolimere in terme van die verspreiding van die verskillende segmente al langs die ketting en die variasie in samestelling, het ook ‘n groot invloed op die vastetoestandmorfologie. In hierdie studie is twee verskillende tipes poliëster gebruik om vyf reekse PDMS–PES gesegmenteerde kopolimere en een reeks vertakte PDMS–PES kopolimere te berei. Die twee poliëstersegmente is polibutileenadipaat (PBA) en polibutileensikloheksaankarboksilaat (PBCH). Die kopolimere is berei deur middel van polikondensasie in die smeltfase. Inligting aangaande verskeie faktore in the bereiding van die PDMS–PES kopolimere is ingewin. Die reekse kopolimere wat berei is, het dit moontlik gemaak om die invloed van die tipe poliëster, kettingargitektuur, grootmaatsamestelling, bloklengte, kristalliniteit en reaksiekondisies op die oppervlakte en interne morfologie te bestudeer. Die opmerklike verskille in the eienskappe van die kopolimere word toegeskryf aan die verskille in die kopolimeermorfologie in terme van die mikrofaseskeiding, kristalliniteit en vryevolume eienskappe. Hierdie verskille het ook veranderings in die oppervlakte samestellings en verwante oppervlakte eienskappe teweeggebring. Multifase morfologie, in alle PDMS–PES kopolimere en die tipe morfologie wat waargeneem is, is afhanklik van die PDMS inhoud, die PDMS segmentlengte en die graad van vertakking. Drie tipes morfologie is waargeneem: sferiese mikro-gebiede van PDMS in ‘n PES matriks, ‘n bikontinueerlike dubbele-diamant tipe en sferiese mikro-gebiede van PES in ‘n PDMS matriks. Sferiese gebiede van die PDMS is ook waargeneem in kopolimere met ‘n lae PDMS inhoud tussen die kristallyne poliëster lae. Die kompleksiteit van die PDMS–PBCH kopolimeermorfologie is verder ondersoek deur gebruik te maak van ‘n wye reeks eksperimentele data afkomstig van positronvernietigingsleeftydspektroskopie (PALS), gevolg deur die ontwikkeling en toepassing van ‘n nuwe soort gekoppelde tegniek – tussen fraksionering (chromatografie) en mikroskopie (atoomkragmikroskopie) tegnieke. Die resultate het ‘n unieke perspektief gegee wat betref die kompleksiteit van die PDMS–PBCH kopolimeermorfologie en dien as ‘n basis vir die teoretiese struktuur–eienskapverwantskap van hierdie interessante klas termoplastiese materiale.

Thesis (PhD (Chemistry and Polymer Science))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Honeybush tea, also known as “South Africa’s sweetest tea”, is a herbal tea made from the leaves and twigs of Cyclopia spp., indigenous to the fynbos biome in the Western and Eastern Cape provinces of South Africa. The pleasant sweet aroma and taste of fermented honeybush, its low tannin content and the absence of caffeine have led to widespread interest in the commercial cultivation and processing of honeybush tea since the mid-1990s. Although more than 20 species of honeybush grow in the wild, only a few species are commercially exploited for the manufacture of tea. Currently the more prominent species are C. intermedia, C. subternata, C. genistoides, and C. sessiliflora. The present research contributes to a comprehensive honeybush research programme being conducted at the Agricultural Research Council (ARC) Infruitec-Nietvoorbij in South Africa. The first phase of the present study, using C. genistoides as representative species, was aimed at developing the necessary methodology for the analysis of extremely low concentrations of honeybush volatiles. A high-capacity headspace sample enrichment probe was applied successfully in conjunction with gas chromatography-mass spectrometry (GC-MS) to analyse the volatile organic compounds present in dry or infused unfermented and fermented honeybush. A total number of 255 volatile compounds were identified in unfermented and fermented honeybush, the majority of which are terpenoids (138; 54%) comprising mostly terpenes, terpene ketones, terpene alcohols and terpene ethers. Of the other compound classes, the aldehydes are the largest group, followed by esters, hydrocarbons and ketones. The stereochemistry of the identified compounds was determined whenever possible. This is the most comprehensive chemical characterisation of the volatile compounds in a South African herbal plant reported to date. A comparative study of green and fermented honeybush showed that the same compounds are, to a large extent, present in both, albeit in different relative concentrations. Not all of the identified honeybush volatiles are necessarily odour-active compounds contributing to the overall typical honeybush aroma. An important aspect of this research was thus the identification of the 46 odour-active compounds in fermented honeybush by means of gas chromatography-olfactometry (GC-O), using detection frequency and aroma extract dilution analysis methods. Fifteen of these compounds, mainly terpenoids, were singled out as the most intense individual contributors to the honeybush aroma based on consideration of all the relevant GC-O data. The odours of certain compounds, i.e. (6E,8Z)-megastigma-4,6,8-trien-3-one, (6E,8E)-megastigma- 4,6,8-trien-3-one, (7E)-megastigma-5,7,9-trien-4-one, 10-epi- -eudesmol, epi- -muurolol and epi- - cadinol, were perceived by GC-O assessors as typically honeybush-like. The quantitative GC-MS data of seven different Cyclopia samples (including four different species and variants thereof) were compared with respect to all the volatile components and particularly with respect to the odour-active compounds. Interesting variations were found in the concentrations of certain odour-active compounds in the various samples. The quantitative data obtained for the odour-active honeybush volatiles and data obtained from the sensory analysis of eight Cyclopia samples (including four different species and variants thereof) were subjected to statistical analysis and interesting associations between compounds with certain sensory aroma attributes were established. The present study has made a major contribution to the scientific knowledge regarding one of South Africa’s most popular indigenous herbal teas. / AFRIKAANSE OPSOMMING: Heuningbostee, wat ook bekend staan as “Suid-Afrika se soetste tee”, word gemaak van die blare en takkies van Cyclopia spp. wat inheems is en voorkom in die fynbosbioom van die Wes- en Oos-Kaapprovinsies van Suid-Afrika. Die aangename soet smaak en aroma van gefermenteerde heuningbos, die lae tannnien-inhoud en die feit dat die tee kafeïenvry is, het gelei tot belangstelling in die kommersiële verbouing en prosessering van heuningbostee gedurende die 1990s. Meer as 20 heuningbosspesies kom in die natuur voor, maar slegs ‘n paar spesies word kommersieel verbou vir die vervaardiging van heuningbostee waarvan C. intermedia, C. subternata, C. genistoides en C. sessiliflora tans die belangrikste spesies is. Die navorsing maak deel uit van ‘n omvattende heuningbos navorsingsprogram wat onder leiding staan van die Landbounavorsingsraad Infruitec- Nietvoorbij in Suid-Afrika. In die eerste fase van die huidige studie is die nodige analitiese metodologie ontwikkel vir die monsterneming en analise van die vlugtige organiese verbindings wat in uiters lae konsentrasies in heuningbos voorkom, deur van ‘n verteenwoordigende spesie, C. genistoides, gebruik te maak. ‘n Sogenaamde “sample enrichment probe” (SEP) is ontwikkel en suksesvol in kombinasie met gaschromatografie-massaspektrometrie (GC-MS) aangewend vir die analise van die vlugtige verbindings aanwesig in die bodamp van sowel droë plantmateriaal as infusies van ongefermenteerde en gefermenteerde heuningbos. ‘n Totaal van 255 vlugtige verbindings is geïdentifiseer, waarvan die meeste hoofsaaklik terpenoïede is (138, 54%) en terpene, terpeenketone, terpeenalkohole en terpeeneters insluit. Die ander verbindingsgroepe, waarvan die aldehiede die grootste groep is, sluit in esters, koolwaterstowwe en ketone. Indien haalbaar, is die stereochemie van die geïdentifiseerde verbindings ook bepaal. Hierdie studie is die mees omvattende chemiese karakterisering van die vlugtige verbindings in ‘n Suid-Afrikaanse kruieplant wat tot dusver onderneem is. ‘n Vergelykende studie het getoon dat ongefermenteerde en gefermenteerde heuningbos tot ‘n groot mate dieselfde verbindings, hoewel in verskillende relatiewe konsentrasies, bevat. Nie al die geïdentifiseerde vlugtige verbindings in heuningbos is noodwendig aroma-aktiewe verbindings wat ‘n bydrae tot die algehele tipiese heuningbosaroma lewer nie en daarom was die identifisering van die 46 aroma-aktiewe verbindings in geferementeerde heuningbos deur gebruik te maak van gaschromatografie-olfaktometrie (GC-O) deur middel van deteksiefrekwensie en aroma ekstrak verdunningsanalise, ‘n belangrike aspek van die navorsing. Na oorweging van al die tersaaklike GC-O data is 15 van hierdie verbindings, hoofsaaklik terpenoïede, uitgesonder as die verbindings wat die belangrikste bydrae tot die heuningbosaroma lewer. Die reuke van sekere van die verbindings, nl. (6E,8Z)-megastigma-4,6,8-triën-3-oon, (6E,8E)-megastigma-4,6,8-triën-3-oon, (7E)-megastigma-5,7,9-triën-4-oon, 10-epi- -eudesmol, epi- -muurolol, en epi- -cadinol, is deur sommige van die GC-O paneellede as tipies heuningbosagtig beskryf. Die kwantitatiewe GC-MS data van sewe verskillende Cyclopia monsters (insluitende vier verskillende spesies en variante daarvan) is vergelyk met betrekking tot al die vlugtige verbindings, asook veral met betrekking tot die aroma-aktiewe verbindings. Interessante variasies in die konsentrasies van sekere aroma-aktiewe verbindings is in die verskillende monsters waargeneem. Die kwantitatiewe data van die aroma-aktiewe heuningbosverbindings en data verkry uit die sensoriese analise van agt Cyclopia monsters (insluitende vier verskillende spesies en variante daarvan), is onderwerp aan statistiese analises waaruit interessante assosiasies tussen verbindings met sekere sensoriese aroma-eienskappe waargeneem is. Hierdie studie lewer ‘n groot bydrae tot die wetenskaplike kennis aangaande een van Suid- Afrika se mees populêre inheemse kruietees.

Thesis (PhD (Chemistry and Polymer Science))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The effects of the macromolecular composition and content of different wood species on the properties of wood-polymer composites (WPCs) achieved when using poly(vinyl alcohol-co-ethylene) (EVOH) as a compatibiliser and linear low density polyethylene (LLDPE) as a matrix, were investigated. Four wood different species (A. cyclops (acacia), E. grandis (eucalyptus), P. radiata (pine) and Q. alba (oak)) with different macromolecular composition and contents and average particle lengths were used. WPCs filled with these species and WPCs filled with the same species but without extractives were prepared using 10% wood content and different amounts (0, 2, 5, 7 and 10%) of EVOH. An EVOH content of 7% was found to be optimum. Unextracted woods produced WPCs with higher mechanical properties and better resistance to ultraviolet (UV) degradation, while the extracted woods produced WPCs with lower water absorption (WA) rates and better thermal stability. Use of unextracted A. cyclops resulted in composites with superior mechanical and thermal properties compared with the other unextracted species, most probably due to its higher cellulose and lignin contents and a favourable average wood particle length (0.225 mm). A. cyclops composites also had higher WA and thickness swelling (TS) rates most likely due to the greater number of free hydroxyl groups present in these composites because of higher cellulose content. Composites containing wood species with a high lignin and extractive content, such as A. cyclops and Q. alba, exhibited higher resistance to UV degradation. Poly(vinyl alcohol-co-ethylenes) (EVOHs) with different ethylene content (27, 32, 38 and 44%) and A. cyclops with different particle sizes (180, 250 and 450 ìm) were used to prepare WPCs with 10% A. cyclops content. The effect of the contact area between the A. cyclops particles and LLDPE achieved when using EVOHs as compatibilisers on the properties of WPCs was also investigated. The greatest improvements in the mechanical and thermal properties of composites made with A. cyclops with particle size 180 ìm were obtained when EVOH with 44% ethylene content was used. The greatest improvements in the composites made with A. cyclops with particle size 250 ìm were achieved when EVOH with 38% ethylene content was used. Composites made with A. cyclops with particle size 450 ìm exhibited better properties when EVOH with 27% ethylene content was used. All the composites that had better mechanical and thermal properties, also exhibited better compatibility and interface adhesion. Two successful approaches were used to impart more attractive ecological and economical advantages to WPCs. In the first approach, (0, 2, 5 and 7%) degraded LLDPE was used as a compatibiliser in WPCs at levels of 10, 30 and 50% wood content. The resulting mechanical properties, such as tensile strength and hardness, thermal and morphological properties of the compatibilised composites were slightly higher than those of noncompatibilised composites and virgin LLDPE. Elongation at break and impact properties of the compatibilised composites were lower than in virgin LLDPE, but higher than in noncompatibilised composites. In the second approach, polyethylene (PE) and various functionalised polyethylenes (PEs) were synthesised by copolymerising ethylene and 10-undecen-1-ol using a soluble metallocene/methylaluminoxane catalyst at room temperature. The incorporation of functional groups increased with increasing comonomer content. WPCs with 10 and 30% wood content were prepared. The composites prepared with functionalised PEs had better mechanical, thermal and morphogical properties than the composites prepared with PE. Composites made with functionalised PE with higher hydroxyl groups content exhibited better properties than composites made with functionalised PE with lower hydroxyl groups content. Composites with 10% wood content exhibited better properties and performance than composites with 30% wood content. / AFRIKAANSE OPSOMMING: Die gevolg van die makromolekulere samestelling van verskillende houtspesies op die eienskappe van hout-polimeer saamgestelde materiale (HPS) wanneer poli(viniel alcohol-ko-etileen) (EVOH) as versoeningsmiddel gebruik word saam met linieere lae digtheid poli(etileen) (LLDPE) as matriks is ondersoek. Vier houtspesies (A. cyclops (acacia), E. grandis (eucalyptus), P. radiata (pine) and Q. alba (oak)) met verskillende makromolekulere samestelling and partikelgrootte-verspreiding is gebruik in die studie. HPS materiale is berei met hierdie vesels, beide voor en na ekstraksie van die houtpartikels met onderskeidelik warm water en oplosmiddels (alleen en in kombinasie). In hierdie HPS materiale is 10% hout gebruik en 0, 2, 5, 7 en 10% EVOH. 'n EVOH inhoud van 7% is as optimum bepaal. Houtpartikels voor ekstraksie het HPS materiale met beter meganiese eienskappe en beter weerstand teen UV bestraling, terwyle partikels wat ekstraksie ondergaan het HPS materiale met laer water-absorpsie en beter hitte-stabiliteit to gevolg gehad het. Die gebruik van ongeekstraheerde A. cyclops het samegestelde materiale met die beste meganiese en termiese eienskappe tot gevolg gehad in vergelyking met die ander houtspesies (voor ekstraksie), as gevolg van die hoer sellulose en lignien inhoud van die spesie, sowel as 'n voordelige partikelgrootte-verspreiding. A. Cyclops saamgestelde materiale he took hoer waterabsorpsie (WA) en dikte-swelling (DS) tempos gehad, weens die groter hoeveelheid vrye hidroksielgroepe teenwoording in die materiale, direk in verwantskap met die sellulose-inhoud. Saamgestelde materiale met 'n hoe hoevellheid lignien en ekstraheerbare materiale (A. cyclops and Q. alba) het beter weerstand teen UV-degradasie geopenbaar. Verskillende poli(viniel alkohol-ko-etileen) polimere (EVOHs) met wisselende etileen-inhoud (27, 32, 38 en 44%) en A. Cyclops met verskillende partikel-groottes (180, 250 en 250 µm) is gebruik om HPS materiale met 10% hout te vervaardig. Die gevolg van die kontak-area tussen die houtpartikels en die LLDPE wanneer EVOHs as versoeningsmiddel gebruik is, is ook ondersoek. Die beste verbetering in die meganiese en termiese eienskappe van die saamgestelde materiale met A. cyclops met partikel-grootte 180 µm is gekry met EVOH met 44% etileen-inhoud, terwyl die beste resultate met 250 µm partikels verkry is met 'n EVOH met 38% etileen, en met 27% etileen in die geval van die 450 µm partikels. Twee benaderinge om meer aantreklike ekologiese en ekonomiese eienskappe by die HPS materiale te bewerkstellig was suksesvol. In die eerste geval is gedegradeerde LLDPE as versoeningsmiddel gebruik. Die resulterende meganiese eienskappe van die HPS materiale met LLDPE as versoeningsmiddel was beter as die HPS mateirale daarsonder. Samegestelde materiale met 10, 30 en 50% hout is vervaardig. Die trekverlenging by die breekpunt sowel as die impaksterkte van die HPS materiale was laer as LLDPE alleen, maar beter as die nie-versoende HPS materiale. In die tweede benadering is polietileen (PE) en gefunksionaliseerde PE gesintetiseer deur etileen en 10-undekeen-1-ol te koplimeriseer met ‘n oplosbare metalloseen/metiel alumoksaan katalis. Die hoeveelheid funskionele (OH) groepe is verhoog deur toenemend ekomonommer-inhoud. HPS materiale met 10 en 30% hout is vervaardig. Die saamgestelde materiale met funksionele PE het beter maganiese eienskappe gehad as die met gewone PE. Hoe hoër die hidroksielgroep-inhoud, hoe beter die eienskappe van die HPS materiale, terwyl die materiale met 10% hout beter eienskappe openbaar het as materiale met 30% hout.

Thesis (PhD (Chemistry and Polymer Science))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: Due to the commercial, nutritional and health value of vegetable oils, seeds and beans, the analysis of their components is of much interest. In this dissertation oil-containing food products, specifically vegetable oils, seeds and beans, were investigated. Selected minor components of three locally produced vegetable oils, namely apricot kernel, avocado pear and macadamia nut oils were investigated using 31P NMR spectroscopy. These minor components, including 1,2 diacylglycerols, 1,3 diacylglycerols and free fatty acids, were identified in the 31P NMR spectra of each of the three vegetable oils for the first time. Two approaches were used for the quantification of the minor components present in the spectra. A calibration curve approach used known concentrations of standard minor components to establish calibration curves while a direct correlation approach calculated the unknown concentration of minor components in the vegetable oils using a known amount of standard compound within the analysis solution. These approaches aided in determining the concentration of minor components during storage studies in which vegetable oils were stored in five different ways: exposed to light, in a cupboard, in a cupboard wrapped in tin foil, at -8 °C and at 5 °C. It was found that determining the best storage condition for each oil was difficult since individual minor components were affected differently by the various storage conditions. However, in general the best storage conditions appeared to be 5 °C and -8 °C. The oil, protein and carbohydrate contents of sesame, sunflower, poppy, and pumpkin seeds, and soy, mung, black and kidney beans were analysed by thermogravimetric analysis and 13C NMR solid state NMR spectroscopy. It was shown that the first derivative of TGA data for seeds and beans can give valuable information about the carbohydrate, moisture, protein and fat content. This has not been previously demonstrated. For the seeds, the integration of a region between 270–480 ºC was equal to the sum of the oil and protein content and compared well to quantitative results obtained by other conventional methods. For beans the integration of a region between 180-590 ºC, gave a value which represented the sum of the oil, protein and carbohydrate content. 13C solid state NMR spectroscopy, including SPE-MAS, CP-MAS and variable contact time experiments, was carried out on these seeds and beans and gave valuable information on the solid-like and liquid-like components. To our knowledge these seeds and beans have never been previously analysed using this technique. 13C SPE-MAS NMR spectroscopy indicated that the seeds contained more liquid-like components than the beans. In turn the 13C CP-MAS NMR spectra indicated that beans had higher levels of solid-like components than the seeds. These conclusions correlated well with the quantities of liquid-like components and solid-like components that were determined by conventional methods and TGA. Preliminary studies using T1pH experiments on the components present in the seeds and beans led to a few observations. Most interesting is that a model using a two- phase fit in order to determine T1pH values appears to be more accurate than a one-phase model. / AFRIKAANSE OPSOMMING: Groente olies, sade en bone is ‘n onderwerp van groot belang omrede hul kommersiële, voeding en gesondheidswaardes. In hierdie tesis is olie-bevattende voedselprodukte, spesifiek groente-olies, sade en bone geanaliseer. Geselekteerde komponente teenwoordig in klein hoeveelhede in drie lokaal geproduseerde groente-olies, naamlik appelkoos-pit, avokadopeer en makadamia-neut olies is geanaliseer met behulp van 31P KMR spektroskopie. Hierdie komponente, insluitend 1,2 diasielglyserole, 1,3 diasielglyserole en ongebonde vetsure, is vir die eerste keer geïdentifiseer in die 31P KMR spektra van die drie groente olies. Twee benaderings is gebruik vir die hoeveelheids-bepaling van die komponente in die spektra. ‘n Yking-kurwe metode het gebruik gemaak van bekende hoeveelhede konsentrasies standaard komponente vir die opstel van yking-kurwes, terwyl ‘n direkte korrelasie metode gebruik is om die onbekende konsentrasie van komponente in groente olies te bepaal met behulp van ‘n bekende hoeveelheid standaard verbinding teenwoordig in die oplossing. Hierdie metodes het gelei tot die bepaling van die konsentrasies van die komponente gedurende vyf verskillende berging toestande wat ingesluit het: Blootgestel aan lig, in ‘n donker kas, in ‘n donker kas toegevou in tin foelie, bevries by -8 °C en in ’n koelkas by 5 °C. Dit was bevind dat bepaling van die beste bergingstoestand vir elke olie moeilik is aangesien die individuele komponente verskillend geaffekteer word deur die verskeie berging toestande. Die beste bergings toestand oor die algemeen blyk egter om by 5 °C en -8 °C te wees. Sesamsaad, sonneblomsaad, papawersaad en pampoensaad sowel as sojaboontjie, mungboontjie, swartboontjie en pronkboontjie se olie, protein en koolhidraat komponente was geanaliseer met behulp van termogravimetriese analise (TGA) en 13C soliede toestand KMR spektroskopie. Dit was bevind dat die eerste afgeleide van die TGA data waardevolle inligting lewer oor die komponent inhoud van elk van die sade en bone. Hierdie is nog nie vantevore bevind nie. Vir die sade, was die integrasie van ‘n area tussen 270–480 ºC gelyk aan die som van die olie en proteïen inhoud en het goed vergelyk met die waardes verky deur algemene analitiese metodes. Vir die boontjies, was die integrasie van ‘n area tussen 180-590 ºC gelyk aan die som van die olie, protein en koolhidraat inhoud. 13C vaste staat KMR spektroskopie, insluitende SPE-MAS, CP-MAS en variëerbare kontak-tyd eksperimente, was gedoen en het waardevolle inligting gelewer omtrent die solied-agtige en mobiel-agtige komponente. Hierdie sade en bone is tot ons kennis nog nie van te vore met die tegnieke ondersoek nie. 13C SPE-MAS NMR spektroskopie het aangedui dat daar ‘n groter hoeveelheid mobiel-agtige komponente in sade as in bone teenwoordig is. 13C CP-MAS NMR spektroskopie het weer aangedui dat daar ‘n groter hoeveelheid solied-agtige komponente in bone as in sade teenwoordig is. Hierdie gevolgtrekkings het goed vergelyk met die waarnemings verkry deur konvensionele analitiese metodes en TGA. Voorlopige studies op die komponente van sade en bone deur T1pH eksperimente het tot ‘n paar gevolgtrekkings gelei waarvan die mees interessantste was dat ‘n twee-fase model vir die bepaling van T1pH waardes beter resultate lewer as ‘n een-fase model.