Thesis (PhD (Chemistry and Polymer Science))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: Positron annihilation lifetime spectroscopy (PALS) is well established as a novel method currently available for the study of polymers at a molecular level because of its sensitivity to the microstructural changes in the polymer matrix. The technique provides unique, but limited, information of the solid state structure – primarily on the nature of the free volume (or unoccupied space) in the polymer due to the less dense packing of polymer chains relative to in other solid materials. In the case of completely homogeneous polymer materials the measurement and interpretation of the positron annihilation parameters is relatively simple. However, in the case of polymers with more complex morphologies the situation becomes less clear. This is due to the possibility of the formation, localization and subsequent annihilation of o-Ps (ortho-positronium) within different areas of the complex morphology. This can result in more than one o-Ps lifetime component being present, and each of the different components corresponds to areas with differing types and amounts of 'open spaces'. In this study a detailed and systematic approach was taken to study the positron annihilation parameters in various semi-crystalline polymers and to correlate these to the chain structure and morphology of the materials. The study focused specifically on polyolefin polymers as these are the most widely used semi-crystalline materials, but more importantly, they offer the possibility to produce a variety of morphological complexity by simple manipulation of the chain structure – while there is essentially no difference in the chemical composition of the materials. The copolymers were selected to study the influence of short-chain branching (amount and length), short-chain branching distribution and tacticity on the morphology, and subsequent positron annihilation lifetime parameters. Three separate topics were addressed. First, preparative temperature rising elution fractionation was used to isolate polymer samples that are homogeneously crystallisable and to produce a series of polymers with differing chain structure and resultant morphologies. Second, additional series were produced by removing specific crystallisable fractions from the bulk materials. Third, the temperature variation of the samples as they approach and go through the crystalline melting point was studied. All the raw positron data were found to be best fitted with a four-component positron annihilation lifetime analysis. The longest lifetime (which is attributed to annihilation of o-Ps in the amorphous phase of the materials) showed systematic variations with the degree and nature of the short-chain branding, tacticity variation, a combination of both short-chain branching and tacticity, and changes in the amorphous phase as a result of heating. The third lifetime component (which is attributed to o-Ps annihilation in or around the crystalline areas of the materials) showed less variation across the sample series. Typically, greater variations were observed in the propylene copolymers than in the ethylene copolymers, which are reflective of the more complex chain structure and corresponding morphology in the propylene copolymer series. Direct evidence for a contribution from the nature of the amorphous phase to the bulk microhardness of the sample was also found. / AFRIKAANSE OPSOMMING: Positronvernietigingsleeftydspektroskopie (PALS) is goed gevestig as ‘n nuwe metode vir die studie van polimere op molekulêrevlak agv die sensitiwiteit van die metode vir mikrostrukturele veranderings in die polimeermatriks. Hierdie tegniek verskaf unieke, maar beperkte, inligting aangaande die vastetoestandstruktuur – veral aangaande die aard van die vryevolume (of onbesette spasie) in die polimeer as gevolg van die minder digte verpakking van polimeerkettings relatief tot in ander vastestowwe. In die geval van volledig homogene polimeriese materiale is die meet en interpretasie van die positronvernietigingsparameters relatief eenvoudig. Maar in die geval van polimere met meer komplekse morfologieë is die situasie minder duidelik. Die rede hiervoor is die moontlikheid vir die formasie, lokalisering en gevolglike vernietiging van o-Ps (orto-positronium) in die verskillende areas van die komplekse morfologie. Dit kan tot gevolg hê dat meer as een o-Ps komponent teenwoordig is en waar elk van die verskillende komponente ooreenstem met areas met verskillende tipes en hoeveelhede 'oop spasies'. In hierdie studie is ‘n sistematiese, in-diepte benadering gebruik om die positronvernietigingsparameters in verskeie semikristallyne polimere te bestudeer en hulle te korreleer met dié van die kettingstruktuur en die morfologieë van die materiale. Hierdie studie het spesifiek gefokus op poliolefiene aangesien hulle die mees algemene semikristallyne materiale is wat gebruik word en, nog meer belangrik, hulle bied die geleentheid om verskeie komplekse morfologieë te lewer dmv eenvoudige manipulasie van die kettingstrukture – terwyl daar basies geen verandering in die chemiesesamestelling van die materiale is nie. Die kopolimere is gekies om die invloed van kort-ketting vertakking (lengte en hoeveelheid), kort-ketting vertakking verspreiding en taktisiteit op die morfologie en vervolgens die positronvernietigingsleeftyd parameters te bestudeer. Drie onderwerpe is aangespreek. Eerstens, preparatiewe temperatuurstygingelueringsfraksionering (prep-TREF) is gebruik om polimeermonsters wat homogeenkristalliseerbaar is te isoleer om sodoende 'n reeks polimere met verskillende kettingstrukture, en gevolglike morfologieë, te lewer. Tweedens, 'n addisionele reekse monsters is berei deur die verwydering van spesifieke kristalliseerbare fraksies vanaf die grootmaatmonsters. Derdens, die temperatuurverandering van die monsters wanneer die monsters naby aan die kristallyne smeltpunt is en wanneer hulle deur die kristallyne smeltpunt gaan is bestudeer. Daar is bevind dat alle rou positrondata ten beste gepas het in 'n vier-komponent positronvernietigingsleeftydanalise. Die langste leeftyd (wat toegeskryf is aan vernietiging van o-Ps in die amorfe fase van die materiaal) het sistematiese variasies getoon met die volgende: hoeveelheid en aard van die kort-kettingvertaking, verandering in taktisiteit, 'n kombinasie van beide kort-kettingvertakking en taktisiteit en veranderings in die amorfiesefase as gevolg van verhitting. Die derde leeftyd komponent (wat toegeskryf is aan die o-Ps vernietiging in of rondom die kristallyne areas van die materiale) het minder variasie in hierdie reeks monsters getoon. Daar is tipies meer variasie waargeneem in die propileenkopolimere as in die etileenkopolimere, wat ’n weerspieëling is van die meer komplekse kettingstruktuur en ooreenstemmende morfologie in die propileenkopolomeerreeks. Direkte bewys vir 'n bydrag van die aard van die amorfe fase tot die grootmaat mikrohardheid van monsters is ook bevind.

Thesis (PhD)--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: The crystallization of polyolefins is an important parameter in determining the properties of such materials. The crystallization phenomenon generally depends on the molecular symmetry (tacticity) and molecular weight of the material. In this study, a series of polypropylenes was prepared using heterogeneous MgCl2-supported Ziegler catalysts with two different external donors, diphenyldimethoxysilane (DPDMS) and methyl-phenyldimethoxysilane (MPDMS), and two different homogeneous metallocene catalysts, racethylene- bis(indenyl) zirconium dichloride, Et(Ind)2ZrCl2 (EI), and rac-ethylene-bis(4,5,6,7- tetrahydro-1-indenyl) zirconium dichloride, Et(H4Ind)2ZrCl2 (EI(4H)). Molecular hydrogen was used as terminating agent. In order to establish a correlation between the molecular weight and the crystallization of these polymers, fractionation of the materials according to crystallizability was performed by means of temperature rising elution fractionation (TREF). This affords the opportunity of blending materials of different molecular weights but similar symmetry. These materials were characterized using various analytical techniques: differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), 13C nuclear magnetic resonance spectroscopy (13C-NMR), high temperature gel permeation chromatography (HT-GPC) and Fourier-transform infrared spectroscopy (FT-IR). DSC was used to study the bulk crystallization of different polypropylene blends, most of which showed only one melting peak. The latter is usually associated with a high degree of cocrystallization. Turbidity analysis of the different polypropylene polymers, obtained using solution crystallization analysis by laser light scattering (SCALLS), provided good crystallization information – similar to that provided by crystallization analysis fractionation (CRYSTAF) and TREF. It was also possible to differentiate between polypropylenes with similar chemical structure but different tacticity and molecular weight. SCALLS results also showed that the blends of different isotactic polypropylene polymers were miscible and cocrystallization had occurred, whereas, the blends of syndiotactic polypropylene and different isotactic polypropylenes were not miscible and some interaction between phases had occurred. Optical microcopy (OM) and scanning electronic microscopy (SEM) were used to study the morphological properties of different isotactic polypropylenes. Results revealed a welldefined and large spherulitic morphology of mixed a1 (disordered) and a2 (ordered) crystal form structures. OM and SEM images also clearly showed an effect of molecular weight and tacticity on the crystal structure of the different polypropylene samples. Finally, various homopolymers and blends were studied to investigate the effect of molecular weight on the mechanical properties of these materials. This was done using microhardness testing and dynamic mechanical analysis. / AFRIKAANSE OPSOMMING: Die kristallisasie van poliolefiene is ‘n belangrike faktor wat die eienskappe van hierdie tipe materiale bepaal. In die algemeen hang kristallisasie af van die molekulêre simmetrie (taktisiteit) en molekulêre massa van die materiaal. ‘n Reeks polipropilene is berei deur gebruik te maak van heterogene MgCl2-ondersteunde Ziegler-kataliste met twee verskillende elektron donors, difenieldimetoksisilaan (DPDMS) en metielfenieldimetoksisilaan (MPDMS), en twee verskillende homogene metalloseenkataliste, rac-etileen-bis(indeniel) sirkoniumdichloried, Et(Ind)2ZrCl2 (EI), en rac-etileen-bis(4,5,6,7-tetrahidro-1-indeniel) sirkoniumdichloried, Et(H4Ind)2ZrCl2 (EI(4H)). Molekulêre waterstof is gebruik as termineringssagent. Ten einde ‘n verband te bepaal tussen die molekulêre massa en kristallisasie van hierdie polimere is hulle gefraksioneer op die basis van hulle kristallisseerbaarheid deur gebruik te maak van temperatuurstyging-elueringsfraksionering (TREF). Deur hierdie tegniek verkry ons materiale van verskillende molekulêre massa maar met dieselfde taktisiteit wat ons kan vermeng. Verskeie tegnieke is gebruik om hierdie materiale te karakteriseer: differensiële skandeerkalorometrie (DSC), wyehoek X-straal diffraksie (WAXS), 13C-kernmagnetiese resonansspektroskopie (13C-KMR), hoë-temperatuur gelpermeasiechromotagrafie (HT-GPC) en Fourier-transform-infrarooispektroskopie (FT-IR). DSC is gebruik om die vaste-toestand kristallisasie van verskeie vermengde polipropilene te bestudeer., en net een smeltpunt is in meeste gevalle waargeneem. Laasgenoemde word gewoonlik verbind met ‘n hoë mate van kokristallisasie. Oplossingkristallisasie analise, dmv laserligverstrooiing (SCALLS), is gebruik om die turbiditeit van die verskillende polipropileen kopolimeervermengings te bepaal. Goeie inligting aangaande die kristallisasie in oplossing – soortgelyk aan dié wat dmv die kristallisasie-analise-fraksioneringstegniek (CRYSTAF) en TREF bepaal is, is verkry. Dit was ook moontlik om te onderskei tussen polipropilene met soortgelyke chemiese strukture maar verskillende taktisiteit en molekulêre massas. SCALLS data het ook getoon dat die vermengings van verskeie isotaktiese polipropileen polimere versoenbaar was en dat kokristallisasie plaasgevind het, terwyl vermengings van sindiotaktiese polipropileen en verskeie isotaktiese polipropilene nie versoenbaar was nie en dat ‘n mate van fase-skeiding plaasgevind het. Optiese mikroskopie (OM) en skandeer-elektronmikroskopie (SEM) is gebruik om die morfologiese eienskappe van verskillende isotaktiese polipropilene te bepaal. Goed gedefineerde en groot sferulitiese morfologie van gemengde a1 (onordelike struktuur) en a2 (ordelike struktuur) kristal-strukture is waargeneem. OM en SEM beelde het ook gewys dat molekulêre massa en taktisiteit ‘n effek het op die kristalstruktuur van die verskillende polipropileenmonsters. Laastens is die meganiese eienskappe van ‘n verskeidenheid homopolimere en vermengde materiale bestudeer, deur gebruik te maak van mikro-hardheid metings en dinamiesmeganiese analise (DMA).

Thesis (PhD)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The wine industry is an important sector of agriculture and wine analysis forms the basis of assessing compliance of its commodities with regulatory standards and research in this field. Liquid chromatography (LC) is extensively used for the determination of a wide range of nonvolatile wine components, but conventional detectors impose performance limitations on the technique that prevents its application to sophisticated analytical problems. In particular, conventional detectors for LC often lack the sensitivity and specificity for the determination of many wine compounds, especially trace level analytes, and furthermore, do not possess spectral capabilities for compound identification or structure elucidation. The hyphenation of mass spectrometry (MS) to LC has led to the introduction of a range of detectors that confers high levels of sensitivity and selectivity to the technique. In addition, a wide variety of MS architectures are available that are inherently suited for targeted analysis or structure elucidation studies. In this dissertation, the potential benefits of liquid chromatography – tandem quadrupole mass spectrometry (LC-MS/MS) to solve analytical problems relevant to the wine industry are explored. LC-MS/MS is a particularly versatile analytical technique because both mass analysers can be operated in full-spectrum mode or selected-ion monitoring, which, together with optional fragmentation, gives rise to four modes of operation that may be used for highly specific and sensitive targeted analysis or spectral investigations. In multiple reaction monitoring (MRM) mode, both analysers are set at single ion frequencies specific for the compound under investigation and one or more of its product fragments, respectively. MRM mode is ideally suited for trace level analysis in complex mixtures, even in cases where the target components are not resolved from interferences. In this study, MRM detection was used to solve challenges relevant to the wine industry for the selective quantitation of target analytes that could not be analysed by conventional LC methods. The application of this approach for the analysis of natamycin, ethyl carbamate (EC) and 3-alkyl-2- methoxypyrazines (MPs) in wine is demonstrated. Natamycin is an antimicrobial preservative that is not permitted in wine in the European Union. A rapid and sensitive method for the determination of natamycin was developed, and has been used since 2009 to regulate this vitally important sector of the South African wine export industry. EC is a natural carcinogen that occurs at trace level amounts in alcoholic products. It also has the potential to accumulate in wines and can occur in very high concentrations in some fruit brandies. The determination of EC is complicated by its physicochemical properties, and available analytical methods suffer from drawbacks such as the requirement for elaborate extraction procedures and high solvent consumption. A novel method for the determination of EC in wines, fortified wines and spirits is described and it was applied to perform an audit of the South African industry as well as to investigate factors responsible for its accumulation in alcoholic beverages. This work forms an integral part of the food safety mandate of the State and it ensures that export products comply with international norms for trade. MPs are ultra-trace-level aroma compounds that contribute to the varietal character of Sauvignon blanc wines. Their analytical determination is challenging due to their low levels of occurrence. The loading capacity of LC combined with the sensitivity and resolving power of MS was exploited to analyse concentrated extracts, in order to achieve very low limits of detection. The performance of the LC-MS/MS method enabled the quantitation of these compounds at their natural levels of occurrence, including the first quantitation and spectral confirmation of 3- ethyl-2-methoxypyrazine in wine. Extensive data pertaining to South African Sauvignon blanc wines are reported and statistical analysis is performed, reporting the correlation of variables such as vintage and origin as well as wine parameters such as malic acid with wine MPs. Furthermore, the application of LC-MS/MS for structural elucidation and screening of target classes of analytes was demonstrated for the analysis of red wine anthocyanins. The anthocyanidin-glycosides are responsible for the colour of red grapes and wine, contribute to the sensory properties of wine, and are also of interest due to their beneficial biological properties. Their determination is complicated by their large numbers and structural diversity, further exacerbated by diverse reactions during wine ageing as well as the lack of reference standards for most members of this class of compounds. Tandem MS in scan mode was used for the highly selective detection of glycosylated anthocyanins and derivatives, exploiting the predictable elimination of the sugar moiety in neutral loss mode. Concurrent survey scan experiments were used to unambiguously identify neutral loss detected compounds. The method therefore follows a simplified and structured approach for unambiguous peak identification based on elution order and mass spectral information to impart a high level of certainty in compound identification. In summary, the work presented in this dissertation demonstrates that LC-MS/MS is a versatile and powerful analytical approach for the analysis of diverse compounds of relevance to the wine industry. The sensitivity and specificity of MRM mode, and the selectivity and spectral capabilities of neutral loss and survey scan modes of MS/MS detection, is amply demonstrated by the applications presented in the dissertation. / AFRIKAANSE OPSOMMING: Die wynbedryf is ‘n belangrike komponent van landbou en wyn-analise vorm ‘n integrale deel van gehalteversekering ten opsigte van toepaslike wetlike standaarde. Wyn-analise is ook belangrik in navorsing oor die samestelling van wyn. Vloeistofchromatografie word dikwels aangewend vir die bepaling van ‘n wye verskeidenheid nie-vlugtige wynkomponente, maar konvensionele detektors plaas beperkinge op die aanwending van die tegniek tot gesofistikeerde analitiese toepassings. Meer spesifiek, konvensionele detektors vir vloeistofchromatografie beskik nie oor die sensitiwiteit en selektiwiteit vir die bepaling van baie wynkomponente nie, veral in die geval van spoorvlakanalise, en beskik boonop ook nie oor spektrale vermoëns vir identifikasie van komponente en struktuurbepaling nie. Die koppeling van vloeistofchromatografie met massaspektrometrie het ‘n reeks detektors tot die tegniek toegevoeg wat hoë vlakke van sensitiwiteit en selektiwiteit bied. Verder bied die verskeidenheid van massaspektrometrie-konfigurasies ook instrumente wat inherent geskik is vir geteikende analise of struktuurbepaling, afhangende van die doel van die ondersoek. In hierdie dissertasie word die voordele ondersoek wat verbonde is aan die aanwending van vloeistofchromatografie – tandem kwadrupool massaspektrometrie om relevante analitiese vraagstukke in die wynbedryf op te los. Hiedie tegniek is besonder toepaslik aangesien beide massa-analiseerders in geselekteerde-ioon modus of in volle skandering gebruik kan word. Tesame met opsionele fragmentasie, gee hierdie uitleg aanleiding tot vier funksionaliteite wat vir hoogs sensitiewe geteikende analise of spektrale onledings gebruik kan word. Eerstens word beide massa analiseerders vir enkel-ioon frekwensies opgestel, spesifiek tot die teikenkomponent en een of meer van sy produkfragmente, wat verkry word deur komponentspesifieke fragmentasie. Hierdie modus is by uitstek geskik vir spoorvlakontleding van komplekse monsters, selfs wanneer die teikenkomponente nie chromatografies van die matriks geskei is nie. In hierdie studie is die tegniek aangewend vir die hoogs sensitiewe bepaling van spoorvlak komponente wat nie met konvensionele detektors gemeet kon word nie. Die aanwending van hierdie tegniek word gedemonstreer vir die spoorvlakbepaling van natamycin, etielkarbamaat en 3-alkiel-2-metoksiepierasiene in wyn. Natamycin is ‘n antimikrobiese preserveermiddel wat ontoelaatbaar is in wyn in die Europese Unie. ‘n Vinnige en sensitiewe metode vir die bepaling van natamycin is ontwikkel, en word reeds sedert 2009 aangewend om hierdie uiters belangrike sektor van die Suid-Afrikaanse wyn uitvoerbedryf te reguleer. Etielkarbamaat is ‘n karsinogeen wat natuurlik voorkom in spoorhoeveelhede in alkoholiese produkte. Dit kan ook onder sekere omstandighede akkumuleer in wyn en in hoë konsentrasies voorkom in vrugtebrandewyne. Die bepaling van etielkarbamaat word bemoeilik deur sy chemiese eienskappe, en gevolglik word analitiese metodes gekenmerk deur uitgebreide, arbeidsintensiewe monstervoorbereiding en die gebruik van groot hoeveelhede, meestal giftige, oplosmiddels. ‘n Nuwe metode vir die bepaling van etielkarbamaat in wyn, gefortifiseerde wyn en spiritualië word beskryf en word aangewend om die faktore vir vorming daarvan te ondersoek. Die metode word aangewend om die Suid-Afrikaanse bedryf te ouditeer in terme van die voedselveiligheid mandaat van die Staat, en om te verseker dat uitvoere voldoen aan standaarde vir internasionale handel. Metoksiepierasiene is vlugtige, ultraspoorvlak wynaromakomponente wat verantwoordelik is vir die kenmerkede kultivarkarakter van Sauvignon blanc wyne. Hul analitiese bepaling word bemoeilik deur hulle lae konsentrasies in wyn. Die ladingskapasiteit van vloeistofchromatografie tesame met die sensitiwiteit en selektiwiteit van massaspektrometrie was benut om hoogs gekonsentreerde ekstrakte te ontleed. Baie hoë vlakke van sensitiwiteit word sodoende verkry. Die verrigting van die metode was voldoende om hierdie komponente teen hulle natuurlike konsentrasies te kwantifiseer, insluitende die eerste kwantifisering en spektrale bevestiging van 3-etiel-2-metoksiepierasien. Omvattende data van die vlakke van hierdie komponente in Suid- Afrikaanse Sauvignon blanc wyne word getoon en statistiese ontleding is gedoen om korrelasies tussen veranderlikes soos oorsprong en oesjaar sowel as basiese wyn veranderlikes soos byvoorbeeld appelsuur, met metoksiepierasienvlakke te ondersoek. Verder was die toepassing van vloeistofchromatografie – tandem massaspektrometrie tot struktuurbepaling en skandering vir groepe van komponente gedemonstreer vir die ontleding van rooiwyn antosianiene. Die antosianien-glukosiede is verantwoordelik vir die kleur van rooi druiwe en wyn, dra by tot die sensoriese eienskappe daarvan, en is ook relevant as gevolg van die voordelige biologiese eienskappe daarvan. Die bepaling van hierdie komponente word gekompliseer deur hulle groot getalle en strukturele diversiteit, verder bemoeilik deur die wye verskeidenheid van reaksies wat hulle ondergaan tydens veroudering. Daar is ook ‘n gebrek aan beskikbaarheid van standaarde vir die meeste van die lede van hierdie klas van komponente. Tandem massaspektrometrie was in skanderingsmodus gebruik vir hoogs selektiewe deteksie van die antosianien-glukosiede deur die voorspelbare eliminasie van die suiker komponent in neutrale verliesskandering te benut. Gelyktydige skanderings van die komponente wat met neutraleverliesskandering waargeneem word, is gebruik vir ondubbelsinnige komponent identifikasie. Die metode volg daarom ‘n eenvoudige en gestruktureerde benadering vir piek identifikasie wat gebaseer is op chromatografiese orde, sowel as massaspektrale inligting, om ‘n hoë vlak van sekerheid aan die identifikasie van komponente te verleen. Samevattend, word daar getoon deur die werk wat in hierdie dissertasie uiteengesit is dat vloeistofchromatografie – tandem massaspektrometrie ‘n veelsydige en kragtige tegniek bied vir chemiese analise relevant tot die wynbedryf. Die sensitiwiteit, selektiwiteit en spektrale vermoëns van die tegniek word duidelik deur toepassings in die dissertasie getoon.

Thesis (PhD)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: Tuberculosis (TB) is a major cause of morbidity and mortality across the world, affecting adults and children. Children infected with TB differ from adults, as their immunological and patho-physiological response to the disease is different. Although there are a variety of tests available for TB diagnosis, they have limitations when used to diagnose paediatric TB. Children are also unable to generate sputum spontaneously when required for the use in culture or microscopy as diagnostic method. Children however do produce sputum, containing the TB bacilli, which they swallow. If the TB bacilli can therefore be retrieved from the stomach and tested, TB can be diagnosed using gastric samples. In this thesis, a variety of styrene maleimide copolymer (SMI) derivatives were prepared as potential M. tuberculosis-capturing platforms. This was done by modifying poly(styrene-co-maleic anhydride) (SMA) with a variety of primary amine compounds, selected based on possible chemical interactions with the M. tuberculosis cell wall. All the prepared copolymer derivatives were electrospun into nanofibrous mats using the single needle electrospinning technique to yield SMI nanofibers, functionalized with different compounds. Some of the functionalized SMI nanofibers were prepared by surface-functionalization of the polymer nanofibers after electrospinning and some by modification of the polymer before electrospinning. Affinity studies were conducted at neutral and low pH between the different functionalized SMI nanofibers and two mycobacterium strains, namely the bacillus Calmette-Guérin strain of Mycobacterium bovis (BCG) and M. tuberculosis, to evaluate the surfaces of the modified SMI nanofibers as mycobacterium-capturing platforms. The successful capture of BCG onto the surfaces of the various functionalized nanofibers was confirmed by SEM and fluorescence microscopy (FM). Analysis of the SEM and FM images indicated that the SMI nanofibers, functionalized with a C12 aliphatic quaternary ammonium moiety (SMI-qC12), captured BCG the most effectively through a combination of ionic and hydrophobic interaction. Concentration and time studies revealed that the extent of this interaction was dependent on incubation time and concentration of BCG. The affinity studies with BCG also concluded that the polymer used for the nanofibrous-capturing platform should not be too hydrophobic in character as this caused poor wetting of the functionalized nanofibers, thus preventing close contact with the mycobacteria and a reduction in the capture effectivity of the polymer nanofibers. The successful capture of M. tuberculosis onto the SMI-qC12 nanofibrous surface was confirmed by FM, light microscopy (LM) and polymerase chain reaction (PCR). The extent of this interaction was dependent on the concentration of M. tuberculosis. The detection of M. tuberculosis using FM and LM as detection methods was simplified by the tendency of M. tuberculosis to clump together in clusters on the hydrophobic surface of the SMI-qC12 nanofibers. As a result of this clustering, FM and LM were therefore regarded as feasible detection methods to image M. tuberculosis on the surface of the SMI-qC12 nanofibers, even at relatively low concentration of M. tuberculosis. / AFRIKAANSE OPSOMMING: Tuberkulose (TB) is 'n groot oorsaak van morbiditeit en mortaliteit regoor die wêreld en affekteer volwassenes en kinders. Kinders wat met TB geïnfekteer is, se immunologiese en patofisiologiese reaksie op die siekte verskil van die van volwassenes en dit het belangrike implikasies vir die diagnose van TB in kinders. Alhoewel daar 'n verskeidenheid van toetse beskikbaar is vir die diagnose van TB, het hulle beperkings wanneer dit gebruik word om pediatriese TB te diagnoseer. Kinders kan ook nie spontaan sputum produseer as dit nodig is vir die gebruik in kultuur of mikroskopie as diagnostiese metode. Kinders produseer egter wel sputum, wat die TB basille bevat, wat hulle dan insluk. As die TB basille uit die maag versamel kan word en getoets kan word, kan TB gediagnoseer word met behulp van maag monsters. In hierdie tesis is 'n verskeidenheid van stireen maleimied kopolimeer (SMI) afgeleides voorberei as potensiële Mycobacterium tuberkulose (Mtb)-vaslegging platforms. Dit is gedoen deur die modifikasie van poli(stireen-ko-maleïen anhidried) (SMA) met 'n verskeidenheid primêre amien verbindings as oppervlak-funksionaliseringsagente. Hierdie primêre amien verbindings is gekies op grond van moontlike chemiese interaksies met die Mtb selwand. Al die voorbereide kopolimeer afgeleides is elektrogespin in nanoveselagtige matte met behulp van die enkel-naald elektrospin tegniek om SMI nanovesels te lewer wat gefunksionaliseer is met verskillende verbindings. Sommige van die gefunksionaliseerde SMI nanovesels is berei deur oppervlak-funksionalisering van die polimeer nanovesels na elektrospin, en sommige deur die modifikasie van die polimeer voor elektrospin. Affiniteitstudies is uitgevoer, by neutrale en lae pH, tussen die verskillende gefunksionaliseerde SMI nanovesels en twee mikobakterium rasse, naamlik die basillus Calmette-Guérin ras van Mycobacterium bovis (BCG) en M. tuberculosis, om die oppervlaktes van die gewysigde SMI nanovesels te evalueer as mikobakterium-vaslegging platforms. Ontleding van die SEM en FM beelde het aangedui dat die SMI nanovesels, gefunksionaliseer met 'n C12 alifatiese kwaternêre ammonium groep (SMI-qC12), BCG die doeltreffendste vasgevang het deur 'n kombinasie van ioniese en hidrofobiese interaksie. Konsentrasie- en tydstudies tussen BCG en SMI-qC12 het aangedui dat die omvang van hierdie interaksie afhanklik is van inkubasietyd en konsentrasie van BCG. Die affiniteitstudies met BCG het ook aangedui dat die polimeer wat gebruik word vir die nanoveselagtige-vaslegging platform nie te hidrofobiese moet wees nie, aangesien dit swak benatting van die gefunksionaliseerde nanovesels veroorsaak, en dus noue kontak met die mikobakterieë voorkom met ʼn gevolglike vermindering in die vasvang-effektiwiteit van die polimeer nanovesels. Die suksesvolle vasvang van M. tuberculosis op die SMI-qC12 nanovesels is bevestig deur FM, lig mikroskopie (LM) en polimerase kettingreaksie (PKR). Die opsporing van Mtb deur die gebruik van FM en LM as opsporingmetodes is vergemaklik deur die tendens van Mtb om in groepies saam te pak op die hidrofobiese oppervlak van die SMI-qC12 nanovesels. As gevolg van hierdie groepering, is FM en LM dus haalbare opsporingmetodes om M. tuberculosis op die oppervlak van die SMI-qC12 nanovesels waar te neem, selfs by relatief lae konsentrasie van M. tuberculosis.

Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: In this study an economical, environmentally friendly, selective and efficient process for the extraction and recovery of [AuCl4]- from aqueous acidic chloride-rich solutions, particularly those aqueous solutions having low concentrations of the precious metal complexes has been investigated. Functionalized poly(styrene-co-maleimide) (PSMI) nanoparticles were synthesized by thermal imidization of the poly(styrene-co-maleic anhydride) (PSMA) copolymer with 3-N,N-dimethylaminopropylamine. Stable water-based dispersions were obtained containing spherical, monodisperse PSMI nanoparticles with a narrow size-distribution and average diameters of 50 ± 5 nm. The specific surface area of the bulk PSMI nanoparticles is 88.1 ± 2.2 m2/g with an average pore diameter of 82.3 Å. 13C NMR, FTIR and elemental analyses confirmed the successful and complete conversion of PSMA into the PSMI derivative. The functionalized PSMI nanoparticles synthesized were investigated as a novel anion-exchange material for the extraction of [AuCl4]- ions from aqueous acidic solutions. Batch sorption studies were carried out as a function of various parameters, such as initial gold concentration, PSMI mass, contact time and agitation rate. The [AuCl4]- extraction occurred with extremely fast sorption kinetics and is dependent on the rate of agitation during the batch sorption process. The functionalized PSMI nanoparticles show a maximum gold loading capacity of 1.76 mmol/g (347.7 mg/g). Langmuir and Freundlich isotherm models were applied to analyze the experimental sorption data. The best model describing the sorption process is given by the Langmuir model. Desorption efficiencies of about 80 % and 93 % were obtained using acidified thiourea (0.25 M thiourea/2 M HCl) and a mixture of 10 M HNO3/0.5 HCl as elutant solutions, respectively. X-ray photoelectron spectroscopy (XPS) analysis unambiguously confirms that the immobilized gold species exists in several oxidation states of 0, +I and +III on the PSMI nanoparticles. This proves that the [AuCl4]- ions initially present in the gold feed solutions unfortunately are subject to a reduction phenomenon on the surface of the functionalized PSMI nanoparticles. The existence of the various gold species contributed significantly to poor desorption efficiencies. In addition to PSMI nanoparticles, micro- to millimeter size PSMI resin beads was prepared by an electrospray methodology. This allows for a wide range of PSMI spherical and quasi-spherical bead diameters of shape to be prepared by manipulation of the experimental conditions employed during the electrospray process, such as the concentration of the PSMI in solution, the capillary tip-to-collector distance, flow rate and the applied voltage. 13C NMR and FTIR spectroscopy analyses show that the electrospray methodology allows PSMI resin beads preparation without any change in chemical composition of the PSMI material. Surface area and porosity analysis shows that 450 μm and 1620 μm PSMI beads selected for use in the gold extraction experiments are microporous and have BET specific surface areas of 2.8 ± 0.4 m2/g and 2.0 ± 0.1 m2/g, respectively. Micro- to millimeter size PSMI resin beads of 450 μm and 1620 μm diameter were tested as potential anion-exchange resins for the extraction of [AuCl4]- from aqueous acidic solutions. The time-dependent studies reveal that the extent of gold uptake increases with an increase in contact time and is dependent on the gold concentration in the [AuCl4]- feed solutions. A maximum loading capacity of 120.7 mg/g and 98.16 mg/g was attained for the 450 μm and 1620 μm resin beads, respectively. The experimental sorption data followed a linear trend consistent with a Freundlich sorption model. This sorption trend for [AuCl4]- suggests that a multi-layer sorption process predominates. Desorption of immobilized gold species from the loaded PSMI resin beads was investigated using various elutants such as HCl, HNO3, thiourea, NaCN and NaOH solutions. The best results were obtained using a mixture of 10 M HNO3/0.5 M HCl as elutant with a desorption efficiency of about 97%. Finally, superparamagnetic magnetite (Fe3O4) nanoparticles with a high degree of crystallinity and phase purity were synthesized by a chemical co-precipitation of Fe2+ and Fe3+ salts. The average diameters of the obtained Fe3O4 nanoparticles were about 7 – 8 nm. The Fe3O4 nanoparticles were coated with oleic acid surfactant molecules and used as seed particles for the preparation of 50 nm diameter magnetic PSMI nanoparticles via an in situ imidization reaction. TEM analysis confirmed that the magnetically responsive PSMI nanoparticles consist of magnetite core-polymer shell structure, although more work is required to perfect such materials. / AFRIKAANSE OPSOMMING: In hierdie studie is ‘n ekonomiese, omgewings vriendelike, seleketiewe en effektiewe proses vir die ekstraksie en herwinning van [AuCl4]- uit suur chloried-ryke oplossings, spesifiek oplossings van lae konsentrasies van edel metal komplekse was bestudeer. Gefunksionaliseerde poli(stireen-ko-maleïmied) (PSMI) nanopartikels was gesintetiseer deur middel van termiese imidisasie van die poli(stireen-ko-maleïk anhidried) kopolimeer met 3-N,N-dimetielaminopropielamien. Stabiele dispersies in water was gevind wat soos sweriese mono-disperse PSMI nanopartikels met ‘n noue partikel-grootte verspreiding met ‘n gemiddelde deursnee van 50 ± 5 nm. Die spesifieke oppervlak area van die massa PSMI nanopartikels is 88.1 ± 2.2 m2/g met ‘n gemiddelde porie-grootte van 82.3 Å. 13C NMR, FTIR en elementêre analiese bevestig die suksesvolle en volledige omskakeling van PSMA na PSMI. Die gefunksionaliseerde PSMI nanopartikels was bestudeer as ‘n nuwe anion-uitruil material vir die ekstraksie van [AuCl4]- ione uit suur oplossings. Stel sorpsie studies was uitgevoer as ‘n funksie van verskeie parameters soos onder andere die goud konentrasie in oplossing, PSMI massa, kontak tyd en ‘n mengings tempo. Die [AuCl4]- ekstraksie gebeur met ‘n geweldige sorpsie kinetika en is afhanklik van die mengings tempo gedurende die stel sorpsie proses. Die gefunksionaliseerde PSMI nanopartikels het ‘n maksimum goud sorpsie kapsiteit van 1.76 mmol/g (347.7 mg/g). Langmuir en Freundlich isoterm modelle was gepas en geanaliseer op die experimentele sorpsie data waarvan die Langmuir isoterm model die data die beste gepas het. De-sorpsie effektiwiteit van ongeveer 80 % en 93% was vekry vir die aangesuurde thiourea (0.25 M thiourea/2 M HCl) en ‘n mengsel van 10 M HNO3/0.5 M HCl as elueer oplossings, onderskeidelik. X-straal foto-elektron spektroskopie (XPS) analiese bevestig ongetwydeld die geimmobileerde goud spesies in oksidasietoestande van 0, +I, en +III op die PSMI nanopartikels. Hierdie is bewyse dat die [AuCl4]- oorspronklik teenwoordig in die goud oplossings is onderhewe auto-reduksie fenomeen op die oppervlak van die gefunksionalieerde PSMI nanopartikels. Die bestaan van verskeie goud spesies dra by tot die power de-sorpsie effektiwiteit van ge-immobiliseerde goud. Bykomend tot die nanopartikels is mikro- tot millimeter grootte PSMI partikels voorberei met ‘n elektro-sproei proses. Hierdie metode stel ons instaat om ‘n wye reeks sferiese en quasi-sferiese PSMI partikel se deersnee voorteberei. Deur die manupulasie van die eksperimentele kondisies gedurende die elektro-sproei proses, soos die konsentrasie van die PSMI in oplossing, die kapilêre punt-tot-ontvanger afstant, vloeispoed en die toegepasde potensiaal. 13C KMR en FTIR spectroskopiese analiese wys dat die elektro-sproei proses die PSMI partikel bereiding toelaat sonder enige veranderinge in die chemiese samestelling van die PSMI materiaal. Oppervlak area en porie-grootte analise wys dat 450lksdfhld en dskl jmm partikels gebruik in die goud ekstraksie eksperimente is mikro-porieës en het spesifieke oppervlak-areas van 2.8 ± 0.4 m2/g en 2.0 ± 0.1 m2/g onderskeidelik. Mikro- tot millimeter grootte poli(stireen-ko-maleimied) (PSMI) partikels van 450 μm en 1620 μm deursnee was getoets as potensieele anion-uitruilings-hars vir die ekstraksie van [AuCl4]- vanuit suur oplossings. Die tyd afhanklike studies gee aanduiding dat die mate van goud opname toeneem met ‘n toename in kontak-tyd en is afhanklik van die goud konsentrasie in die [AuCl4]- oplossings. ‘n Maksimum opname-kapasiteit van 120.7 mg/g en 98.2 mg/g was verkry vir die 450 μm en 1620 μm hars partikels onderskeidelik. Die eksperimentele sorpsie-data volg ‘n lineêre neiging in ooreenstemming met die Freundlich model. Die sorpsie neiging van [AuCl4]- dui aan dat ‘n meervuldige laag sorpsie proses domineer. De-sorpsie van die geimobiliseerde goud spesies vanaf die PSMI hars partikels was bestudeer deur gebruik te maak van verskeie elueermiddels soos HCl, HNO3, thiourea, NaCN en NaOH oplossings. Die beste resultate is verkry deur ‘n mengsel te gebruik van 10M HNO3/0.5M HCl as elueermiddel met n de-sorpsie effektiviteit van ongeveer 97%. Superparamagnetiese magnetiet (Fe3O4) nanopartikels met ‘n hoë graad van kristaliniteit en fase-reinheid was voorberei deur ‘n chemiese ko-neerslagvorming van Fe2+ en Fe3+ soute. Die gemiddelde deursnee van die Fe3O4 nanopartikels was ongeveer 7 – 8 nm. Die Fe3O4 nanopartikels was omhul met oleic suur benatter molekules wat gebruik word as saadjies vir voorbereiding van 50 nm deursnee-magnetiese PSMI nanopartikels deur middel van ‘n imidisasie reaksie. TEM analiese bevestig dat die magnetiese PSMI partikels nanopartikels bestaan uit ‘n magnetiet-kern polimeer-skil struktuur.

Thesis (MSc)--Stellenbosch University, 2013. / Aminoquinolines are important class of drugs that have been used for malaria chemotherapy for centuries. However, long-term exposure to these drugs leads to extensive spread of drug resistance. As such, modified chloroquinoline derivatives are being studied as alternative antimalarial agents with the possibility to overcome drug resistance associated with chloroquine analogues. In this study, 15 aminoquinoline derivatives that are linked by a 1,4-disubstituted 1,2,3-triazole ring to an ethyl and propyl carbon spacer with a distal amine motif were designed and synthesized as novel antimalarial agents using the Cu(I)-promoted Huisgen reaction. The compounds have been synthesized from the 7-chloro-N-(prop-2-yn-1-yl)quinolin-4-amine alkyne precursor and the azides of ethyl and propyl amino moieties using a 1,3-dipolar cycloadditioncoupling in the presence of CuI catalyst to obtain moderate to good yields (53 – 85%). These compounds have been characterized by the combination of NMR, ESI+ HRMS and IR spectroscopic methods. The antiplasmodial activity of the compounds was investigated in vitro against P. falciparum strain NF54 using chloroquine as a reference drug together with a standard antimalarial drug artesunate. Of the 15 novel chloroquinoline derivatives, 11 have demonstrated to possess promising potency by way of the inhibition concentrations less than 250 nM with the lowest being 28 nM. The observed activities have been ascribed to the overall modifications such as the introduction of a triazole linker and changing of carbon chain length as these were the variables. The compounds are accordingly under further biological investigations and only the chloroquine sensitive results are reported in this work.

Thesis (MSc)--Stellenbosch University, 2013. / Please refer to full text to view abstract.

Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Calixarenes are large cyclic molecules that have a distinctive bowl-shaped geometry. The nonplanar nature of these molecules means that, by selectively functionalizing the calixarene on one side of the symmetry plane, one introduces inherent chirality. As with other varieties of chirality, this asymmetry can be utilised to impart stereoselectivity to the formation of new bonds through asymmetric catalysis. The evaluation of inherently chiral calixarenes has been hindered thus far by the difficulty in obtaining enantiomerically pure samples. Using a recently developed stereoselective methodology, incorporating chiral oxazoline directed ortholithiation, the synthesis of a series of upper-rim meta-substituted inherently chiral calixarenes is described. With the use of this methodology, the desired calixarene ligands are synthesised in high diastereoselectivity (from 75% de to >99% de). The inherently chiral meta-substituted bidentate thioether-oxazoline calixarenes synthesised were subsequently investigated as asymmetric ligands for palladium catalysed allylic alkylation. The debutylated series of calixarenes showed good catalytic efficiency, achieving high levels of conversion (>90% isolated yield). A rate enhancement relative to a planar model system was observed. Moderate levels of enantioselectivity (31% ee to 89% ee) were achieved. The influence of the central chirality of the chiral oxazoline was determined to be the predominant stereoselective effect. Increasing the steric bulk on this chiral carbon resulted in a significant increase in the stereoselectivity. Inherent chirality was found to have a subtle but significant effect. Increasing the steric bulk on the calixarene bowl, through the use of analogous tert-butylated calixarene, had an adverse effect on the catalytic efficiency. These ligands formed unstable complexes that decomposed before any appreciable yield of the desired product could be formed. / AFRIKAANSE OPSOMMING: Calixarene is groot sikliese molekule met 'n kenmerkende bak-vormige meetkunde. Die nie-planêre aard van hierdie molekules beteken dat selektiewe functionaliseering van die calixareen op een kant van die simmetrievlak vorm 'n inherente chirale molekuul. Soos met ander soorte van chiraliteit, hierdie asymmetrie kan gebruik word om stereoselektiwiteit aan die vorming van nuwe bindings aan te dra, deur middel van asimmetriese katalise. Die evaluering van inherente chirale calixarene dusver is verhinder deur probleme in die verkryging van enantiomeerisesuiwer monsters. Met behulp van 'n onlangse ontwikkelde stereoselektief metodologie, waarin ‘n chirale oksasolien gerig ortolitiëring, die sintese van 'n reeks van boonste rand meta-gefunksionaliseerde inherent chirale calixarene word beskryf. Met die gebruik van hierdie metodologie, word die verlangde calixareen ligande gesintetiseer in hoë diastereoselektiwiteit (van 75% to t 99% do). Die inherente chirale meta-gefunktionaliseerde tio-eter oksasolien calixarene gesintetiseer is daarna as asimmetriese ligande vir palladium-gekataliseerde allyliese alkilering ondersoek. Die gedebutieleerde reeks van calixarene het goeie katalitiese effektiwiteit getoon, met die bereiking van hoë vlakke van omsetting (> 90% geïsoleerde opbrengs). ‘n Tempoverbetering relatief tot 'n planêre modelstelsel is waargeneem. Gematige vlakke van enantioselektiwiteit (31% eo tot 89% eo) is behaal. Die invloed van die sentrale chiraliteit van die chirale oksasolien is bepaal as die oorheersende stereoselektiewe effek. Die verhoging van die steriese massa op hierdie chirale koolstof het gelei tot 'n beduidende toename in die stereoselektiwiteit. Inherente chiraliteit is gevind om 'n subtiele, maar betekenisvolle uitwerking te hê. Die verhoging van die steriese grootmaat op die calixarene bak, deur die gebruik van analoog tert-butieleerde calixarene, het 'n nadelige uitwerking op die katalitiese effektiwiteit. Hierdie ligande vorm onstabiel komplekse dat ontbind voordat enige aansienlike opbrengs van die verlangde produk kan gevorm word.

Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The high-resolution 195Pt NMR signals (128.8 MHz) of most of the octahedral mixed-ligand Pt(IV) complexes in the series [PtCl6-n(OH)n]2-, n = 0-6, have been recorded in aqueous solutions at 293 K. These signals show characteristic 35/37Cl isotope-induced fine structure that results from the presence of several isotopologues in samples with a natural chlorine isotope distribution; each 37Cl isotope incorporated into the Pt coordination sphere of one of these complexes affords a fixed upfield (low frequency) isotope shift of between 0.17 and 0.22 ppm, depending on the particular complex. This assignment is confirmed by the excellent agreement between the natural abundances of the various isotopologues and the relative contributions of the corresponding signals to the overall area of the experimental spectrum of the particular isotoplogue set, obtained by a non-linear least-squares line fitting procedure. These results confirm that the 195Pt magnetic shielding in isotopomers differing only in the combination of the two chlorine isotopes coordinated in sites trans to hydroxido-ligands are indistinguishable under these experimental conditions, unlike those of similar isotopomers in the related series of aqua-complexes [PtCln(H2O)6-n]4-n, n = 3-5, as reported by Koch and co-workers. Moreover, the order of 195Pt shielding for the members of all stereoisomer pairs in the series of hydroxido-complexes is the reverse of that reported for the corresponding pairs in the aqua-series. These and other observations are interpreted qualitatively in terms of the relative strengths of the trans-influences of aqua-, hydroxido- and chlorido-ligands and the effect of these on bond displacements in these complexes. The 195Pt NMR spectra of especially the complexes cis-[PtCl2(OH)4]2- and [PtCl(OH)5]2- show remarkable fine structure in a ca. 45 % 18O-enriched aqueous solution; apart from additional signals resulting from 18O-containing isotopologues, the resonance signals of isotopomers differing in the combination of 16/18O isotopes in sites trans to chlorido-ligands are partially resolved. The effect of temperature on the 35/37Cl isotope-induced fine structure in the 195Pt signals of [PtCl6]2- and [PtCl(OH)5]2- was investigated in the range 283-308 K; some interesting differences are observed. 195Pt relaxation time measurements for [PtCl6]2- in this temperature range reveal that line-broadening is at least partially responsible for the loss of resolution between the signals of isotopologues of this complex as the temperature is increased, possibly due to the spin-rotation relaxation mechanism. The temperature coefficient of 195Pt shielding and the magnitude of isotope shifts in the spectra of the complexes in this series show interesting correlations with the 195Pt shielding itself; an interpretation of these observations is presented. / AFRIKAANSE OPSOMMING: Die hoëresolusie 195Pt NMR seine (128.8 MHz) van die oktaëdriese gemengde-ligand Pt(IV) komplekse in die reeks [PtCl6-n(OH)n]2- is waargeneem in waterige oplossing by ʼn temperatuur van 293 K. Hierdie seine toon ʼn karakteristieke 35/37Cl isotoop-geïnduseerde fynstruktuur as gevolg van die teenwoordigheid van verskeie isotopoloë in monsters met ʼn natuurlike chloor isotoopverspreiding. Die verplasing van ʼn 35Cl isotoop deur ʼn 37Cl isotoop in die Pt koördinasiesfeer van hierdie komplekse lei tot ʼn laefrekwensie isotoopverskuiwing van die 195Pt resonansiesein van tussen 0.17 en 0.22 ppm, afhangend van die spesifieke kompleks. Die toekenning van resonansieseine in hierdie spektra word ondersteun deur die goeie ooreenstemming tussen die berekende natuurlike verspreiding van isotopoloë en die persentasie area bydrae van die ooreenstemmende pieke tot die area van volledige stel seine van die chemiese spesie, soos bepaal deur ʼn nie-linieêre kleinste-kwadrate passingsmetode. Hierdie resultate bevestig dat vir isotopomere waarvan slegs die kombinasie van chloorisotope wat in posisies trans tot hidroksido-ligande gekoördineer is ʼn ononderskeibare 195Pt magnetiese skerming waargeneem word, m.a.w. ʼn enkele resonansiesein word vir hierdie isotopomere gemeet, anders as gerapporteer deur Koch en medewerkers vir die verwante aqua-komplekse [PtCln(H2O)6-n]4-n waar n = 3-5. Verder is die order van 195Pt magnetiese skerming vir stereoisomere in hierdie hidroksido-komplekse in elke stereoisomer paar die teenoorgestelde van dit waargeneem vir die ooreenstemmende aqua-komplekse. Hierdie waarnemings word kwalitatief geïnterpreteer in terme van die verskillende trans-invloede van die chlorido-, aqua- en hidroksido-ligande en die effekte daarvan op bindingslengtes in die komplekse. In ʼn ongeveer 45 % 18O-verrykte monster toon die 195Pt seine van veral die komplekse cis-[PtCl2(OH)4]2- en [PtCl(OH)5]2- uitsonderlike fynstruktuur vanweë die addisionele seine van 18O-bevattende isotopoloë en die parsiële resolusie van die seine van isotopomere wat verskil in die kombinasie van 16/18O isotope wat trans tot chlorido-ligande gekoördineer is. ʼn Studie is gemaak van die uitwerking van temperatuur op die 35/37Cl isotoop-geïnduseerde fynstruktuur in die 195Pt seine van die komplekse [PtCl6]2- en [PtCl(OH)5]2- in die gebied 283-308 K; interessante verskille is waargeneem. 195Pt magnetiese relaksasietyd metings vir die kompleks [PtCl6]2- in waterige oplossing in hierdie temperatuurgebied toon dat verbreeding van resonansieseine ten minste gedeeltelik verantwoordelik is vir die waargenome verlies aan resolusie tussen die seine van isotopoloë namate die temperatuur styg; die verbreeding van seine kan waarskynlik aan die spin-rotasie relaksasiemeganisme toegeskryf word. Die temperatuurkoëffisiënt van 195Pt magnetiese skerming en die grootheid van isotoopverskuiwings in die spektra van die hidroksido-komplekse in hierdie reeks toon interessante korrelasies tot die 195Pt magnetiese skerming; ʼn interpretasie van hierdie waarnemings word voorgestel.

Thesis (MSc)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: A comparative study of the chemical composition of linear low density polyethylene polymers, synthesised with 1 - hexene as comonomer was conducted. Catalyst trials were conducted on the linear low density 1 - hexene polymer grade material to evaluate alternative catalysts. A comparative analysis was performed in order to investigate if the samples synthesised under catalyst trial conditions showed any significant differences in terms of crystallinity and mechanical properties with the reference sample that was synthesised using the reference catalyst. The results showed that the macro product properties, namely melt flow Index, density, and level of hexene extractables are different for the trial samples in comparison with the reference sample. The differences observed implied that the trial samples were synthesised with differences on a molecular level. The differences in the chemical composition between the reference sample and the comparative samples were fully explored using a wide range of analytical techniques, namely crystallisation analysis by fractionation (CRYSTAF), temperature rising elution fractionation (TREF), differential scanning calorimetry (DSC), Carbon 13 nuclear magnetic resonance (13C NMR), Size exclusion chromatography (SEC), Positron analysis lifetime spectroscopy (PALS) and micro hardness analysis. The results of the characterisation studies indicated the following: - Crystallinity and hardness analysis of the reference sample, catalyst trial sample 1 and catalyst trial sample 2 indicate that the catalyst trial sample 2 having a low cocatalyst concentration is the most crystalline of all the samples. - The reference sample, catalyst trial sample 1 and catalyst trial sample 2 were further fractionated using TREF at fractionation temperature intervals of 10°C. TREF analysis indicates that the bulk of the material is observed to elute between 70°C - 10°C. - 13C NMR analyses of the TREF fractions identified four populations of fractions that could be selectively removed, allowing the bulk of the material to be recombined. As these highly crystalline fractions were removed, there was an observed decrease in the total crystallinity of the bulk recombined material. This trend was further verified by the free volume analysis. - Free volume analysis indicated of the bulk recombined material indicated a general increase in the T3 lifetime and T4 lifetime intervals. Free volume analysis further confirmed a decrease in crystallinity of the bulk recombined material as highly crystalline material was removed. - Micro hardness analysis of the polymers further verified the crystallinity trends observed. As the molecular composition of the polymer changed due to removal of highly crystalline fractions, the total mechanical strength of the material indicated by the hardness value decreased. The study showed that by changing the chemical composition of the polymer by removing highly crystalline fractions, there was an observed change in the mechanical properties of the polymer. It can be concluded that the samples synthesised under catalyst trial conditions show significant differences in terms of crystallinity and mechanical properties in comparison with the sample that was synthesised using the standard reference catalyst. / AFRIKAANSE OPSOMMING: ‘n Vergelykende analise studie is onderneem van die chemiese samestellings van lineêre lae digtheid poliëtileen polimere, gesintetiseer met 1-hekseen as ko-monomeer. Alternatiewe kataliste is ge-evavuleer ten opsigte van lineêre lae digtheid 1-hekseen Sasol polimeer graad materiaal. Die vergelykende analise is uitgevoer om die monsters onder katalis proef kondisies te evalueer en te merk of enige beduidende verskille in terme van kristalliniteit en meganiese eienskappe met die verwysings monster voorkom. Die resultate toon dat die makro-produk eienskappe, naamlik smelt vloei indeks, digtheid en vlak van hekseen onttrekking, verskillend is vir die proef monsters in vergelyking met die verwysings monster. Die waargenome verskille impliseer dat die proef monsters op molekulêre vlak verskil. Die verskille in chemiese samestelling tussen die verwysings monster en die vergelykende monsters is ten volle ondersoek deur gebruik te maak van 'n wye verskeidenheid van analitiese tegnieke, naamlik kristallisasie analise fraksionering (CRYSTAF), temperatuur stygende eluering fraksionering (TREF), differensiële skandeer kalorimetrie (DSC), koolstof 13 kernmagnetiese resonansie (13C KMR), gelpermeasie chromatografie (SEC), positron analise leeftyd spektroskopie (PALS) en mikro-hardheid analise. Die resultate van die karakterisering studies het die volgende aangedui:- Kristalliniteit en hardheid analises van die verwysings monster en katalis proef monsters 1 en 2 het getoon dat katalis proef monster 2, wat ‘n lae ko-katalis konsentrasie bevat, die mees kristallyn is. - Die verwysings monster en katalis proef monster 1 en 2 is gefraksioneer met behulp van ‘n TREF met temperatuur tussenposes van 10°C. TREF analise toon dat oormaat materiaal ge-elueer word tussen 70°C en 100°C. - 13C KMR analise van die TREF fraksies het 4 verskillende fraksies geidentifiseer wat selektief verwyder kan word. Dit laat ook toe dat die grootste deel van die materiaal weer geherkombineer kan word. Soos die hoogs kristallyne fraksies verwyder is, is ‘n afname in die totale kristalliniteit van die geherkombineerde materiaal waargeneem. Hierdie tendens is bevestig deur vrye volume analises. - Vrye volume analises van die geherkombineerde materiaal toon ‘n algemene toename in die T3en T4 leeftyd aan. Vrye volume analises toon verder dat ‘n afname in die kristalliniteit van die geherkombineerde materiaal plaasvind soos meer kristallyne fraksies verwyder word. - Verdere mikro-hardheid analises van die polimere bevestig die waargenome kristalliniteit tendense. Soos die molekulêre samestelling van die polimere verander as gevolg van die verwydering van die hoogs kristallyne fraksies, so neem die totale meganiese sterkte van die materiaal af; soos aangedui deur die afname in hardheid waarde. Die studie toon dat die verandering van die chemiese samestelling van die polimeer, deur die verwydering van hoogs kristallyne fraksies, 'n waargenome verandering in die meganiese eienskappe van die polimeer laat plaasvind. Daar kan afgelei word dat die monsters, vervaardig onder die katalis proef voorwaardes, beduidende verskille toon in terme van kristalliniteit en meganiese eienskappe in vergelyking met die monster vervaardig deur die huidige verwysings katalis.