119 leaves single sided printed, preliminary pages and numbered pages 1-101. Includes bibliography and a list of tables, figures, schemes and abbreviations. Digitized at 300 dpi (OCR), used Bizhub 250. / Thesis (MSc (Polymer Science))--University of Stellenbosch, 2006. / ENGLISH ABSTRACT: The properties and interactions of cellulose surfaces are of a great technical interest during papermaking and recycling. Sizing, the modification of fiber surfaces, e.g. with the purpose to reduce water penetration into the paper structure, plays an important role in obtaining paper with good printability and water resistance. Water resistance is the key end-property of paper being investigated in this study. Firstly a comparison was made between the degree of surface modification of cellulose by means of anionic, nonionic and reactive surfactants. The amount of surfactant adsorbed by the paperboard was determined and the paper surface evaluated via scanning electron microscopy (SEM). The sizing efficiency of the three industrial surfactants was evaluated in order to establish the surfactant structure best suited for sizing recycled paperboard. This was done via the Cobb test, an industrial method to measure water uptake by paper, and contact angle measurements. The reactive surfactant was found to have the best sizing efficiency and focus shifted to synthesizing selected copolymer surfactants via free radical copolymerization. Two copolymers were synthesized, with maleic anhydride as the polar part in both. Butyl methacrylate and lauryl methacrylate were selected as the hydrophobic parts in the respective copolymer systems. The unavailability of reactivity ratios for the respective copolymer systems led to the use of in situ proton nuclear magnetic resonance spectroscopy CH NMR) for the determination of the co-monomer incorporation in both copolymer systems. Quantitative 13C NMR spectroscopy was also employed in order to establish the co-monomer content of the isolated copolymers obtained during bench-scale (laboratory) experiments. Lastly, a comparison of the degree of surface modification of cellulose was made between that which was achieved with the industrial reactive surfactant and that with the two synthesized polymeric reactive surfactants. The two synthesized polymeric surfactants were found to have a better sizing efficiency than the industrial reactive surfactant, and the maleic anhydride-lauryl methacrylate copolymer system gave the best results. / AFRIKAANSE OPSOMMING: Die eienskappe en interaksies van sellulose-oppervlaktes is van groot tegniese belang gedurende die vervaardiging en hergebruik van papier. Oppervlakte behandeling, die modifikasie van vesel-oppervlaktes bv. met die doel om water indringing in die papierstruktuur te verminder, speel 'n belangrike rol in die daarstel van papier met goeie drukkwaliteit en waterweerstand. Waterweerstand is die sleuteleienskap van papier wat in hierdie werkstuk ondersoek word. Eerstens is daar 'n vergelyking getref tussen die verandering van sellulose-oppervlaktes deur middel van anioniese, nie-ioniese en reaktiewe sepe. Die hoeveelheid seep geabsorbeer deur die papierbord is bepaal en die papier-oppervlak ondersoek deur middel van skandeer-elektronmikroskopie (SEM). Die behandelingsdoeltreffendheid van die drie industriele sepe is ondersoek om vas te stel watter seep die beste struktuur het om hergebruikte papierbord effektief te behandel. Dit is gedoen deur middel van die Cobbtoets, 'n industriele metode om wateropname van papier te meet, asook kontakhoekmetings. Daar is gevind dat die reaktiewe seep die beste behandelingsdoeltreffendheid het en daar is vervolgens gekonsentreer op die bereiding van geselekteerde reaktiewe kopolimeersepe deur middel van vryeradikaalkopolimerisasie. Twee kopolimere is berei, met maleienanhidried as die polere gedeeite van albei. Butielmetakrilaat en laurielmetakrilaat is gekies vir die nie-polere gedeeltes van die onderskeie kopolimeersisteme. Die onbeskikbaarheid van reaktiwiteitsverhoudings vir die onderskeie kopolimeersisteme het gelei tot die gebruik van in situ proton kern magnetiese resonansie spektroskopie eH KMR) vir die bepaling van die ko-monomeer insluiting in beide kopolimeersisteme. Kwantitatiewe koolstofdertienkemmagnetieseresonansie spektroskopie (13C KMR) is ook gebruik om die ko-monomeerinhoud van die geisoleerde kopolimere, verkry tydens laboratoriumeksperimente, te bepaal. Laastens is 'n vergelyking getref tussen die graad van modifikasie van selluloseoppervlaktes deur middel van die industriele reaktiewe seep in vergelyking met die twee bereide polimeriese reaktiewe sepe. Daar is gevind dat die twee gesintetiseerde polimeriese sepe beter behandelingsdoeltreffendheid as die industriele reaktiewe seep het, met die maleienanhidried-laurielmetakrilaat-kopolimeersisteem wat die beste resultaat lewer.

Thesis (MSc)--Stellenbosch University, 2004. / ENGLISH ABSTRACT: Polydimethylsiloxane (PDMS) compounds are utilized in outdoor high voltage insulation due to their low weight, vandalism resistance, better anti-contamination performance and their superior hydrophobic nature. Under severe environmental conditions and over prolonged service time, however, the hydrophobic surface can gradually become hydrophilic and then recover with adequate resting period. In this study, room temperature vulcanized (RTV) PDMS samples were prepared with different formulations and then exposed to corona discharge to evaluate its effect. The influence of different additives, such as different types and amount of fillers and additionally added low molar mass silicone oils, on the hydrophobicity recovery of the material was investigated. The effects of two types of corona treatment were also evaluated. Hydrophobicity recovery of corona and UV-C aged PDMS samples was evaluated by means of static contact angle measurements. Positron annihilation spectroscopy (PAS) gave important information on the micro structural change after corona treatment of RTV PDMS as well as naturally aged high temperature vulcanized (HTV) PDMS samples. The different formulations of the RTV PDMS samples and the effect of the additives were studied with this technique. The formation of a thin, highly crosslinked inorganic silica-like (SiOx) layer was confirmed even at the early stage of degradation. It was also possible to estimate the thickness of the silica-like layer formed during corona exposure that is responsible for the loss and recovery of hydrophobicity. The surface hardness and hydrophilicity change of PDMS samples due to corona treatment were studied simultaneously with force distance measurements by atomic force microscopy (AFM). The adhesive force calculated from the pull-off force-distance curves showed that the adhesive force between the probe and the sample decreased with increasing corona treatment time, indicating hydrophobicity recovery. In addition to this, the increase in hardness after corona exposure provides indirect evidence of the formation of a silica-like layer. In all cases the hydrophilicity and the surface hardness of the PDMS samples increased directly after corona treatment and recovered with time. Two types of FTIR spectroscopy were used to analyse the surface of the polymer. / AFRIKAANSE OPSOMMINGS: Polidimetielsiloksaan (PDMS) word in buitelug hoogspanninginsulasie gebruik as gevolg van sy lae massa, weerstand teen vandalisme, verbeterde anti-kontaminasie werkverrigting en superieure hidrofobiese karakter. Die hidrofobiese oppervlakte kan egter gelydelik hidrofillies word onder uiterste omgewingsomstandighede en oor langdurige dienstyd. PDMS materiaal herstel egter nadat dit genoeg rustyd toegelaat is. Kamertemperatuur-gevulkaniseerde (KTV) PDMS met verskillende formulasies is in hierdie studie voorberei, aan korona ontlading blootgestel, geëvalueer en vergelyk. Die invloed van bymiddels soos verskillende tipes en hoeveelhede vuiler, asook addisionele lae molekulêre massa silikoonolie, op die herstel van hidrofobisiteit van die materiaal is ondersoek. Twee verskillende metodes van korona behandeling is ook geëvalueer. Die herstel van hidrofobisiteit van korona en UV-C verouderde PDMS monsters is met statiese kontakhoekmeting geëvalueer. Positronvernietigingspektroskopie (PVS) is 'n kragtige tegniek wat belangrike inligting oor die mikrostrukturele verandering van korona behandelde van KTV PDMS sowel as natuurlik-verouderde hoë temperatuur gevulkaniseerde (HTV) PDMS monsters gee. Die verskillende formulasies van die KTV PDMS monsters, sowel as die effek van die vullers, is met behulp van hierdie tegniek ondersoek. Die vorming van 'n dun, hoogskruisgebinde, anorganiese silika-agtige (SiOx) laag op die PDMS oppervlak, selfs tydens die vroeë stadium van degradasie, is bevestig. Dit was ook moontlik om die dikte van die silika-agtige laag wat gedurende die korona blootstelling gevorm het, en wat verantwoordelik is vir die verlies aan hidrofobisiteit, te bepaal. Die oppervlakhardheid en hidrofilisiteit verandering van PDMS monsters as gevolg van korona behandeling, was gelyktydig met krag-afstand metings deur middel van atoomkragmikroskopie (AKM) bestudeer. Die kleefkrag, soos bereken van aftrek kragafstandkurwes, dui daarop dat kleefkragte tussen die taster en die monster afneem met toenemende korona behandelingstyd, wat beduidend is op die herstel van hidrofobisiteit. Daarbenewens is die toename van oppervlakhardheid na korona blootstelling "n indirekte bewys van die formasie van 'n silika-agtige laag. In alle gevalle het die hidrofilisiteit en die oppervlakhardheid van die PDMS monsters toegeneem direk na afloop van korona behandeling en gevolglik herstel met tyd. Twee tipes IR spektroskopie metodes is gebruik vir die chemiese-oppervlak analises

Thesis (MSc (Chemistry and Polymer Science))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: In papermaking, fillers and additives are used to enhance paper properties. In this study spherical modified poly(vinyl alcohol) (PVA) particles were prepared for use as fillers. In order to determine the mechanism of adhesion of additives to cellulose (paper) fibres, these particles were modified to have surface functionality, with cationic and anionic surface charges, similar to charged polyelectrolyte additives. Typically, retention aids used to improve the fibre–fibre and fibre–filler bonding are able to conform to the surface of the fibres and fillers. Oppositely charged components show strong affinity for each other, e.g. cationic polyelectrolyte groups adhere to anionic surface charges on the fibres. The spherical PVA particles were prepared by the saponification of spherical poly(vinyl pivalate) (PVPi) precursor particles. These PVPi particles, prepared via suspension polymerisation, were cross-linked with a divinyl ether comonomer. The vinyl pivalate (VPi) suspension polymerisation was successfully carried out and afforded relatively uniformly distributed PVPi particles, with diameters of 0.5–10 mm. The cross-linked PVPi particles were then saponified in tetrahydrofuran (THF) as swelling solvent, to afford PVA with various degrees of saponification (DS). The spherical shape was lost and fibrous material was obtained when uncross-linked PVPi particles were saponified. Cross-linking the spherical PVPi particles (PVA precursor) proved innovative, and essential in maintaining the spherical form during saponification to PVA/PVPi. By varying the saponification time periods, various DS were obtained, as characterised by solid state NMR spectroscopy. Surface modification of the PVA/PVPi particles was carried out with cationic and anionic groups via the Williamson ether synthesis. Ionic modification of these rigid spherical PVA/PVPi particles was carried out in order to study their adherence to cellulose fibres, compared to the adherence of similarly modified starches with cellulose fibres. Fluorescent labelling of the different modified particles was carried out using two complimentary coloured fluorescent markers. Fluorescence imaging and scanning electron microscopy (SEM) enabled the observation of particle– fibre and particle–particle interaction. Results indicated that the negative groups are sparse on the cellulose fibres, and therefore particles with low functionality but which are able change shape and conform and adhere to the surface of the cellulose fibres are required for effective adhesion. These modified spherical PVA/PVPi particles are unique as they mirror the chemistry of functionalised starch and cellulose particles, yet maintain their shape and have a fixed size, measurable by SEM and transmission electron microscopy (TEM). Field-flow fractionation was also used to characterise and measure these relatively large cross-linked and fixed diameter particles. / AFRIKAANSE OPSOMMING: In papierproduksie word vulstowwe en bymiddels gebruik om die eienskappe van papier te verbeter. In hierdie studie is sferiese poli(vinielalkohol) (PVA) partikels berei vir gebruik as vulstowwe. Om ten einde die meganisme van die bymiddelklewing aan die sellulose vesels (papier) te bepaal, is die oppervlakke van hierdie partikels gewysig met kationiese of anioniese groepe, om 'n oppervlak soortgelyk aan dié van funksionele poliëlektrolietbymiddels te verskaf. Die retensiemiddels wat gebruik word om die vesel–vesel en vesel–vulstof binding te verbeter is tipies in staat om te konformeer aan die oppervlak van die vesels en vulstowwe. Teenoorgesteldgelaaide komponente toon 'n sterk affiniteit vir mekaar, bv. kationiese poliëlektrolietgroepe is vasklewend aan die anioniesgelaaide oppervlakke van die vesel. Die sferiese PVA partikels is berei deur die verseping van sferiese poli(vinielpivalaat) (PVPi) partikels. Hierdie voorloper PVPi partikels, berei deur suspensiepolimerisasie, is gekruisbind met 'n divinieleter ko-monomeer. Die vinielpivalaat (VPi) suspensiepolimerisasie is suksesvol uitgevoer en relatief eenvormig verspreide sferiese PVPi partikels is berei, met deursnitte tussen 0.5–10 mm. Die gekruisbinde PVPi partikels is daarna gesaponifiseer in tetrahidrofuraan (THF) as oplosmiddel, om PVA met verskillende grade van verseping (DS) te berei. Die sferiese vorm raak verlore en veselagtige materiaal is verkry wanneer PVPi partikels met geen kruisbinding verseep is. Kruisbinding van die sferiese PVPi partikels (PVA voorloper) is voordelig en noodsaaklik om die sferiese vorm tydens die verseping tot PVA/PVPi te behou. Deur die tydsduur van verseping te verander, is verskeie grade van verseping verkry en bevestig deur vaste toestand KMR spektroskopie. Oppervlakwysiging van die PVA/PVPi partikels, om kationiese en anioniese groepe aan te heg, is uitgevoer via die Williamson etersintese. Ioniese wysiging van hierdie stram, sferiese PVA/PVPi partikels is uitgevoer om ten einde hul klewing met sellulose vesels te bestudeer en te vergelyk met die klewing van soortgelyk gewysigde stysels. Fluoressensie merking van die verskillende gewysigde partikels is uitgevoer met behulp van twee komplimentêre gekleurde fluoressensie merkers. Fluoressensie beeldvorming en SEM verskaf die waarneming van partikel–vesel en partikel–partikel interaksie. Die resultate dui daarop dat die negatiewe groepe van die sellulose vesels skaars is, en daarom is partikels met ‘n lae funksionaliteit, maar wat in staat is om van vorm te verander, aan te pas en te konformeer aan die oppervlak van die sellulose vesels, nodig vir effektiewe adhesie. Hierdie gewysigde sferiese PVA/PVPi partikels is uniek aangesien hulle die chemie van gewysigde stysel en sellulose partikels naboots, maar steeds hul vorm behou met 'n vaste grootte; meetbaar deur SEM en TEM. Veld-vloei-fraksionering is ook gebruik vir die karakterisering van hierdie relatief groot, stram, gekruisbinde partikels met bepaalde deursneë.

Thesis (DSc (Chemistry and Polymer Science))--University of Stellenbosch, 2009. / Unstabilised polyolefins are susceptible to degradation when exposed to molecular oxygen, heat, irradiation as well as chemical and mechanical stimuli. Oxidation leads to changes in molecular properties such as molecular weight, molecular weight distribution, chemical composition, chemical composition distribution and crystallisability. Conventional analytical techniques are of limited use when studying the degradation of heterogeneous materials such as impact polypropylene copolymers (ICPP). These copolymers consist of a number of components of different monomer contents, isotacticity and crystallinity, ranging from amorphous EPR to highly crystalline polypropylene. The individual components are affected differently by degradation, leading to heterogeneity within the degradation of impact copolymers. Novel analytical approaches that acknowledge the heterogeneity in sample composition are needed to study the degradation behaviour of such heterogeneous materials. This study describes the combination of fractionation and hyphenated techniques with conventional analyses for extensive structural characterisation of complex impact copolymers as well as their degradation behaviour. Temperature rising elution fractionation (TREF) coupled to conventional techniques such as size exclusion chromatography (SEC), Fourier-Transform infrared spectroscopy (FTIR), Carbon-13 nuclear magnetic resonance (13C-NMR) and differential scanning calorimetry (DSC) indicated the ICPPs in question to consist of four main components, namely ethylene-propylene random copolymers (EPR), isotactic PP (iPP), as well as semi-crystalline ethylene-propylene copolymers (EPC) and lower isotacticity PP. The degradation of an ICPP was studied by a multi-component analysis procedure consisting of TREF coupled to SEC, 13C-NMR, as well as SEC-FTIR. Results obtained by this procedure indicated the change in crystallisability of the bulk sample observed by TREF, crystallisation analysis fractionation (CRYSTAF) and DSC to be the result of the preferential degradation of the iPP phase. Degradation of ICPPs initiates within this phase where chain scission and carbonyl group insertion leads to a change in the crystallisability of iPP chains. During TREF of degraded bulk ICPPs, the degraded iPP molecules elute at lower elution temperatures, depending on their degree of degradation. The other components of the copolymer were degraded to a lesser extent. Degradation products were also found to be heterogeneously distributed across the molecular weight distribution of each fraction, with a higher concentration appearing at the low molecular weight side. The multi-component analysis procedure was also used to study the difference in degradation behaviour between ICPPs of different comonomer content, isotacticity and crystallinity. The spatial heterogeneity of degradation within ICPPs was studied by Fourier-Transform infrared microspectroscopy (FTIR-μS). A heterogeneous distribution of degradation products was found across the depth of thicker sample specimens. These results were compared to those obtained by conventional layer-by-layer milling followed by SEC, FTIR and CRYSTAF. The principles of degradation within thick samples were similar to that observed for thin films, although additional contributions by sample morphology and oxygen diffusion were detected.

Thesis (PhD (Chemistry and Polymer Science))--University of Stellenbosch, 2006. / The study described in this dissertation examines the synthesis of mainly acrylate-based surfactants and their subsequent use as emulsifiers/stabilisers in the emulsion polymerisation of styrene. Some acrylamide-based surfactants were also studied, for comparison purposes only. Two major types of surfactants, polymerisable (surfactant monomers or surfmers) and polymeric, were synthesised, characterised and used in emulsion polymerisation reactions. The prepared polymerisable surfactants, 12-acryloyloxydodecanoic acid (12-ADA) and 11-acrylamidoundecanoic acid (11-AAUA), and their sodium salts, had reactive acryloyl functionalities.

Thesis (PhD (Chemistry and Polymer Science)--University of Stellenbosch, 2005. / This study involves the synthesis and characterisation of PEG-based amphiphilic block copolymers for the hydrophilization of polysulphone ultrafiltration membranes. PEG based macro RAFT agents were synthesized and characterised. PEG-b-PS block copolymers were synthesized via the RAFT assisted controlled free radical polymerisation utilizing the synthesized PEG macro RAFT agents. The resulting polymerisation products were then analyzed by two-dimensional chromatography at the “critical conditions” for PS. In the second phase of this study PEG-b-PSU block copolymers were synthesized via the polycondensation of bis (4-chlorophenyl) sulphone, Bisphenol A, and PEG. The resulting products were characterised by NMR spectrometry. PEG-b-PS films and modified PSU membranes (modified by the addition of PEG-b-PSU block copolymer to the membrane casting solution) were prepared and analyzed. Surface analyses included static contact angle, AFM force-distance analysis, and FTIR-PAS analysis. Results showed the successful synthesis of both PEG-b-PS and PEG-b-PSU amphiphilic block copolymers. Surface analysis proved the successful hydrophilization of the surface of the modified PSU membranes.

Thesis (PhD (Chemistry and Polymer Science)--University of Stellenbosch, 2008. / Xanthate-mediated polymerization was investigated as a tool for the preparation of well-defined poly(N-vinylpyrrolidone) and copolymers of N-vinylpyrrolidone. Some results regarding the monomer vinyl acetate are included, mostly for comparison purposes. The structure of the leaving/reinitiating group of the xanthate mediating agent was tuned to match the monomer reactivity. This was achieved by studying the initialization behaviour of monomer-xanthate systems via in situ 1H-NMR spectroscopy. Additionally, the latter technique was valuable to identify side reactions affecting the monomer, xanthate and/or polymeric species. Subsequently, experimental conditions were defined, and used to optimize the level of control achieved during polymerization. Block copolymers were prepared from a xanthate end-functional poly(ethylene glycol) with both vinyl acetate and N-vinylpyrrolidone. Finally, the preparation of poly(N-vinylpyrrolidone) with a range of well-defined end groups was achieved via postpolymerization treatment of the xanthate end-functional polymerization product. 3 different routes were investigated, which lead to poly(N-vinylpyrrolidone) with 1) aldehyde or alcohol, 2) thiol or 3) unsaturated ω-chain-end functionality, in high yield, while the α-chain-end functionality is defined by the structure of the xanthate leaving group. The ω-aldehyde end-functional poly(N-vinylpyrrolidone) was successfully conjugated to the lysine residues of the model protein lysozyme via reductive amination. Particular attention was drawn to characterizing the polymerization products. NMR spectroscopy, liquid chromatographic and mass-spectroscopic techniques were used. The major achievements emerging from polymer analysis carried out in this study included the following: - a library of NMR chemical shifts for N-vinylpyrrolidone derivatives; - an estimation of the critical conditions for poly(N-vinylpyrrolidone) relevant for separation according to the polymer chain-ends; - conditions for the separation of block-copolymers comprising a poly(ethylene glycol) segment and a poly(N-vinylpyrrolidone) or poly(vinyl acetate) segment via liquid chromatography; - valuable results on matrix-assisted laser ionization-desorption time-of-flight mass spectroscopy (MALDI-ToF-MS) of poly(N-vinylpyrrolidone).

Thesis (PhD (Chemistry and Polymer Science))--Stellenbosch University, 2008. / The research presented in this dissertation was concerned with the living radical polymerization (LRP) of an amphiphilic, water-soluble, bi-substituted and biologically compatible acrylamide derivative, namely n-acryloylmorpholine (NAM). The primary objective of this research was the synthesis of novel block copolymers containing poly(dimethylsiloxane) (PDMS) and various chain lengths of poly(acryloylmorpholine) (polyNAM) using a LRP technique, namely reversibleaddition fragmentation chain transfer (RAFT) polymerization. This is the first report on the synthesis of these block copolymers using RAFT polymerization. These novel siloxane block copolymers were synthesized using a monohydroxyterminated PDMS material which had to first be modified into a thiocarbonylthiocontaining moiety in order for it to be used as macromolecular chain transfer agent (macroCTA) in the RAFT copolymerization with NAM. Suitable reaction conditions for the synthesis of these novel block copolymers had to, firstly, be determined, and secondly, optimized. In order to determine suitable reaction conditions, a series of homopolymerizations with NAM were first performed in order to compare which chain transfer agent (CTA), solvent, temperature etc. could possibly be best suited for the block copolymerizations of PDMS-b-polyNAM. Reported in this work is the first account of the homopolymerization of NAM and 2-(dodecylsulfanyl)thiocarbonylsulfanyl-2-methyl propionic acid (DMP) as CTA using RAFT polymerization. The resulting novel siloxane block copolymers are amphiphilic in nature and the existence of these structures was confirmed by size exclusion chromatography/multiangle light scattering (SEC/MALS), proton nuclear magnetic resonance (1H-NMR) spectroscopy, gel elution chromatography (GEC) and transmission electron microscopy (TEM). Interesting phase behaviour was observed in the latter technique.

Thesis (PhD (Chemistry and Polymer Science))--Stellenbosch University, 2008. / Polysaccharides were modified with selected polymers via the grafting technique. Both anionic and cationic polysaccharides were prepared. Random and crosslinked graft copolymers were also prepared. The percentage grafting was determined by gravimetric analysis and results were confirmed by cross-polarization magic angle spinning carbon-13 nuclear magnetic resonance microscopy (CP/MAS 13C NMR). These modified biodegradable polymers were then used to flocculate precipitated calcium carbonate (PCC). The effects of pH, percentage grafting, crosslinker concentration and polysaccharide concentration on PCC flocculation were evaluated. Furthermore, the effects of anionic and cationic starch, either added to PCC sequentially or simultaneously, on PCC flocculation were also investigated. Generally, anionically modified starch showed excellent flocculation properties, which are desirable for the end application of PCC retention. The effect of polyacrylic acid (PAA) and polyacrylamide (PAM) modified cellulose fibers on calcium carbonate crystal nucleation and growth modification was investigated. When the heterogeneous crystallization of CaCO3 was carried out in the presence of modified cellulose fibers the CaCO3 crystals were found to be residing on the surface of the fibers. The morphologies of the crystallized CaCO3, polymorph and fiber surface coverage were different for cellulose materials grafted with polymers of different functionalities, meaning that there is interaction between the crystal growth modifier and the growing nuclei. The effect of the modified starch on the crystallization of calcium carbonate gave useful insight into designing CaCO3 filler morphologies. It was found that the filler size, morphology and surface properties of fillers can be tailor-made by choosing suitable CaCO3 crystallization conditions as well as a suitable crystal growth modifier. The crystallized CaCO3 had a negatively charged surface. Results of fluorescence studies showed that the PAA modified starch (polymeric additive used) resided on the surface of the crystals. Thus the presence of the polysaccharide on the surface of a filler could be advantageous for strengthening fiber–filler bonding in paper applications. Anionic starch materials were also used to prepare anionic-starch-coated starch particles. Both the anionic starch and anionic-starch-coated starch particles were evaluated for PCC retention and other properties of hand sheets. When anionic-starch-coated starch particles were used there was generally an improvement in the PCC retention, while the other paper properties remained desirable. The success achieved with the use of anionic-starch-coated starch particles now opens the way for the further preparation and testing of various modified starch particles, for optimization of filler retention.

Thesis (PhD (Chemistry and Polymer Science))--Stellenbosch University, 2008. / The synthesis of glycopolymers with various comonomers as prepared via the RAFT process is investigated. The macro-RAFT agent poly(3-O-methacryloyl-1,2:5,6-di-O-isopropylidene-D-glucofuranose) (PMAlpGlc) was prepared by polymerization of the glycomonomer with cumyl phenyl dithioacetate as the chain transfer agent. Chain extension with styrene or methyl acrylate or acrylic acid afforded novel diblock copolymers, (PMAlGlc-b-poly[styrene] or PMAGlc-b-poly[methyl acrylate] or PMAlGlc-b-poly[acrylic acid]), with predetermined molecular weights and narrow molecular weight distributions. The poly(acrylic acid) based glycopolymer was used to modify the surface of CaCO3, forming what will be referred to as a ‘sugar-coated CaCO3’ particle. This surface modifying effect was evaluated in depth; a schematic study of the effect of reaction temperature, pH, reaction time and glycopolymer concentration on CaCO3 crystallization was carried out. The analytical techniques Thermal Gravimetric Analysis (TGA) and Scanning Electron Microscopy (SEM) were used to verify that these ‘sugar-coated CaCO3’ particles have an increased adherence to cellulose compared to ‘non sugar-coated’ particles. A series of polymer configurations comprising various ratios of glycomoiety to poly(acrylic acid) was prepared. The effect of this polymer series on CaCO3 crystallization was evaluated and the ideal polymer configuration and its optimum synthesis conditions (i.e. reaction pH, temperature, time and polymer concentration) that gave maximum adherence of the ‘sugar-coated CaCO3’ particle onto cellulose were identified. The ability of these poly(acrylic acid) based glycopolymers to increase the interaction between CaCO3 and cellulose was then evaluated. This was done by simply mixing all three substrates, i.e. glycopolymer, cellulose and CaCO3 together. Analysis by TGA, SEM and Thin Layer Chromatography (TLC) revealed both the ideal polymer configuration that favoured increased adherence of the CaCO3 to cellulose and the optimum reaction conditions required for application and testing. In addition to studying the interaction between cellulose and CaCO3, the amphiphilic nature of the glycopolymers was determined. Transmission Electron Microscopy (TEM) confirmed that coreshell particles were prepared and that these particles are solvent exchangeable (in the case of styrene and methyl acrylate glyco-blocks) or pH exchangeable (in the case of acrylic acid glyco-blocks).