No description available.

As research continues for the habitation of the Lunar and Martian surfaces, the need for materials for construction of structural parts, mechanical components, and tools remains as a major milestone. The use of in-situ resource utilization (ISRU) techniques is critical due to the financial, physical, and logistical burdens of sending supplies beyond low-Earth orbit. The Bosch process is currently in development as a life support system at the National Aeronautics and Space Administration’s (NASA) Marshall Space Flight Center (MSFC) to regenerate oxygen (O2) from metabolic carbon dioxide (CO2) with the byproduct of elemental carbon (C). The Bosch process presents a possible way of regenerating O2 without the disposal of hydrogen (H2) like the Sabatier. Ionic liquids (ILs) are also studied at MSFC as a means to harvest metallic elements from regolith oxides and meteorites. IL technology provides an energy efficient method of extracting critical manufacturing materials, such as iron (Fe) that could be used for ferrous alloy production. This dissertation seeks to explore the use of Bosch C and IL-Fe for ferrous alloy production through a series of studies. These studies included individually using Bosch C with commercial elements to cast low carbon steel and gray cast iron, investigating as-produced IL-Fe in a laser-based powder bed fusion (PBF-LB) printer to determine IL-Fe metallurgical characteristics, using the IL-Fe composition to design a ductile iron (DI) alloy of similar performance to a commercially available DI alloy, and lastly, refining this DI alloy to produce a DI alloy more representative of an alloy producible from IL-Fe and Bosch byproduct C in a Martian environment. The results presented here suggest that with advances in production rate and control of IL-Fe oxidation, and by providing a sufficient energy grid to operate equipment, a range of high quality DI materials could be manufactured with IL and Bosch process ISRU feedstocks.

Phosphonium ions readily compare to ammonium ions in regards to their aggregate characteristics, thermal stability, and antibacterial activity. Ionic aggregation in phosphonium-based polymers provides thermoreversible crosslinks, ideal for reversible self-assembly, self-healing, and smart response. In polymers, these ionic functionalities aggregate, providing improved moduli, and altering the size and structure of ionic aggregates regulates polymer melt processability. This dissertation highlights phosphonium-based chemistry for the synthesis of novel step-growth ionomers and structure-property relationships in ionic polymers. The synthesis of phosphonium endcapping reagents for melt polyester reactions afforded a thermally stable ionic functionality that controlled molecular weight. Weak association was present with phosphonium ions at low ion concentrations below 7.7 mole %. The use of novel ionic bisacetoacetate monomers in the formation of networks from Michael addition reactions led to the synthesis of ionic networks with increased and broadened glass transitions and improved tensile stresses at break and strains at break compared to those in the non-ionic networks. The first electrospun fibers from Michael addition crosslinking reactions are reported, and equilibrium ionic liquid uptake experimental results indicated that ionic functional networks absorb close to three times the amount of ionic liquid as non-ionic, poly(ethylene glycol)-based films. Chain-extending polyurethanes with a phosphonium diol and subsequently varying the hard segment content led to changes in ionic aggregation, crystallinity, and thermal transitions in the polymers. Additionally, novel phosphonium-based methacrylate monomers incorporated into diblock copolymers with styrene exhibited microphase separation. Overall, the inclusion of phosphonium ions pendant to or in the main chain of various types of polymers led to changes in morphology, improved tensile properties, enhanced moduli, broadened transitions, changes in crystalline melting points, changes in solubility, and appearance of ionic aggregation. / Ph. D.

Ion-containing segmented polyurethanes exhibit unique morphology and physical properties due to synergistic interactions of electrostatic, hydrogen bonding, and hydrophobic interactions. A fundamental investigation on a series of well-defined ion-containing polyurethanes elucidated the influence of charge placement, charge density, and soft segment structure on physical properties, hydrogen bonding, and morphologies. An unprecedented comparison of poly(ethylene oxide)(PEO)-based sulfonated polyurethanes containing sulfonate anions either in the soft segments or hard segments revealed that sulfonate charge placement dramatically influenced microphase separation and physical properties of segmented polyurethanes, due to altered hydrogen bonding and thermodynamic immiscibility between soft and hard segments. Moreover, studies on sulfonated polyurethanes with identical sulfonated hard segments but different soft segment structures indicated that soft segment structure tailored sulfonated polyurethanes for a wide range of mechanical properties. Sulfonated polyurethanes incorporated with ammonium-functionalized multi-walled carbon nanotubes (MWCNTs) generated novel polyurethane nanocomposites with significantly enhanced mechanical performance. Modification of MWCNTs followed a dendritic strategy, which doubled the functionality by incorporating two ammonium cations per acid site. Complementary characterization demonstrated successful covalent functionalization and formation of surface-bound ammonium salts. Upon comparison with pristine MWCNTs, ammonium-functionalized MWCNTs exhibited significantly enhanced dispersibility in both DMF and sulfonated polyurethane matrices due to good solvation of ammonium cations and intermolecular ionic interactions between anionic polyurethanes and cationic MWCNTs. Segmented polyurethanes containing sulfonated PEO-based soft segments and nonionic hard segments were incorporated with various contents of room temperature ionic liquid, 1-ethyl-3-methylimidazolium ethylsulfate (EMIm ES), to investigate the influence of ionic liquid on physical properties, morphologies, and ionic conductivity. Results indicated that EMIm ES preferentially located in the sulfonated PEO soft phase, leading to significantly enhanced ionic conductivity and well-maintained mechanical properties. These properties are highly desirable for electromechanical transducer applications. Electromechanical actuators fabricated with sulfonated polyurethane/IL composite membranes exhibited effective response under a low applied voltage (4 V). However, in the case of an imidazolium-containing segmented polyurethane with imidazolium ionic hard segments and hydrophobic poly(tetramethylene oxide) (PTMO) soft segments, EMIm ES selectively located into the imidazolium ionic hard domains, as evidenced with a constant PTMO soft segment glass transition temperature (Tg) and systematically reduced imidazolium hard segment Tg. Dielectric relaxation spectroscopy demonstrated that ionic conductivity of imidazolium-containing segmented polyurethanes increased by five orders of magnitude upon incorporation of 30 wt% EMIm ES. Imidazolium-containing sulfonated pentablock copolymers were also investigated to elucidate the influence of imidazolium counter cation structures on solution rheology, morphology, and thermal and mechanical properties. Combination of living anionic polymerization and post functionalization strategies provided well-defined sulfonated pentablock copolymers containing structured imidazolium cations in sulfonated polystyrene middle block. Varying alkyl substitute length on imidazolium cations tailored physical properties and morphologies of sulfonated pentablock copolymers. Results indicated that long alkyl substitutes (octyl and dodecyl) on imidazolium cations significantly influenced solution rheological behavior, morphology, and water uptake properties of sulfonated pentablock copolymers due to the altered characteristic of imidazolium cations. Imidazolium-containing sulfonated pentablock copolymers exhibited systematically tailored mechanical properties due to the plasticizing effect of alkyl substitutes. In addition, incorporation of ionic liquids into sulfonated pentablock copolymers further tailored their mechanical properties and ionic conductivity, which made these materials suitable for electromechanical transducer applications. All sulfonated pentablock copolymers were successfully fabricated into actuator devices, which exhibited effective actuation under a low applied voltage (4 V). / Ph. D.

The Abraham solvation model (ABSM) is an experimentally derived predictive model used to help predict various solute properties. This work covers various uses for the ABSM including predicting molar enthalpies of vaporization, predicting solvent coefficients for two new solvents (2,2,5,5-tetramethyloxolane and diethyl carbonate), predicting values for multiple new ionic liquids (ILs). This work also introduces a novel method for updating IL ABSM parameters by updating cation- and anion-specific values using linear algebra and binary matrices.

This thesis investigates the optimization of washing techniques before bleaching a pulp produced using ionic liquids. One pulp is from softwood and the other from wheat straw. Through experiments with varied temperatures and concentrations, the effectiveness of different washing conditions was evaluated, focusing on their impact on kappa number, viscosity, yield and reject amount for the softwood pulp. The wheat straw pulp was studied using the same optimal washing conditions that gave the best results for the softwood pulp. The results showed that washing at 75°C with 1.5% NaOH was the most effective. After washing, the softwood pulp had a kappa number of 20.0 and a viscosity of 162 mL/g. For the wheat straw pulp, the best result was a wash with 1.5% NaOH at 75°C, resulting in a kappa number of 16.2 and a viscosity of 446 mL/g. The washing process proved effective on a laboratory scale and the next step will be to conduct pilot-scale trials. The trials so far show that there is potential to scale up the washing of pulp produced by ionic liquid-based cooking. After washing, bleaching was performed using sodium chlorite. This method was suitable for laboratory-scale experiments, leading to a kappa number reduction from 20.0 down to 0.39 for the softwood pulp, with a viscosity loss from 162 mg/L down to 152 mL/g and a brightness of ISO 85%. For the wheat straw pulp, the kappa number decreased from 16.2 down to 0.62, the viscosity fall to 272 mL/g from 446 mg/L and the brightness reached ISO 76%. The study demonstrates that washing parameters can be optimized to achieve high brightness of the final bleached pulp without significantly altering its physical properties. The kappa number decreases while the viscosity remains relatively stable for the soft wood pulp, indicating that the process can consistently produce the same results. The wheat straw pulp lost viscosity from a high level. Loss of viscosity must be expected in some extent. The insights from this study reveal that pulp produced with ionic liquids can be washed and bleached effectively under control. The control of loss of viscosity is crucial for industrial applications. Future process development will require efficient chemical recovery. It is not possible to have wastes out of the process. It will be essential to close the process and it will ensure the sustainability of the process.

Ionic liquids (ILs) present new approaches for controlling interactions at the solid-liquid interface. ILs are defined as liquids consisting of bulky and asymmetric ions, with a melting point below 373 K. Owing to their amphiphilic character they are powerful solvents but also possess other interesting properties. For example, ILs can self-assemble and are attracted to surfaces due to their charged nature. As a result, they are capable of forming nanostructures both in bulk and at interfaces. This thesis describes how the solid-IL interface responds to external influences such as elevated temperatures, the addition of salt and polarisation. An improved understanding of how these factors govern the surface composition can provide tools for tuning systems to specific applications such as friction. Normal and friction forces are measured for ethylammonium nitrate (EAN) immersed between a mica surface and a silica probe, at different temperatures or salt concentrations. The results demonstrate that an increase in temperature or low concentrations of added salt only induce small changes in the interfacial structure and that the boundary layer properties remain intact. In contrast, at sufficiently large salt concentrations the smaller lithium ion prevails and the surface composition changes. The interfacial layer of a similar IL is also investigated upon the addition of salt and the results reveal that lithium ions affect the surface composition differently depending on the ion structure of the IL. This demonstrates that the surface selectivity strongly depends on the ion chemistry. Remarkably, a repulsive double layer force manifests itself for EAN at 393 K, which is not observed for lower temperatures. This indicates a temperature dependent change in EAN’s microscopic association behaviour and has general implications for how ILs are perceived. A new method is developed based on a quartz crystal microbalance to investigate how the surface compositions of ILs respond to polarisation. The approach demonstrates that interfacial layers of both a neat IL and an IL dissolved in oil can be controlled using potentials of different magnitudes and signs. Furthermore, the method enables two independent approaches for monitoring the charges during polarisation which can be used to quantify the surface composition. The technique also provides information on ion kinetics and surface selectivity. This work contributes to the fundamental understanding of the solid-IL interface and demonstrates that the surface composition of ILs can be controlled and monitored using different approaches. / Jonvätskor möjliggör nya tillvägagångssätt för att kontrollera interaktioner vid gränsskiktet mellan fasta ytor och vätskor. Jonvätskor definieras som vätskor som består av stora och asymmetriska joner med en smältpunkt under 373 K. På grund av sin amfifila karaktär är de starka lösningsmedel men har också andra intressanta egenskaper. Jonvätskor kan till exempel självorganisera sig och attraheras till ytor på grund av sin laddning. En följd av detta är att de bildar nanostrukturer både i bulk och på ytor. Denna avhandling beskriver hur gränsskiktet mellan fasta ytor och jonvätskor svarar på yttre påverkan såsom en ökning i temperatur, tillsättning av ett salt samt polarisering. En ökad förståelse för hur dessa faktorer styr ytkompositionen av jonvätskor kan bidra med verktyg för att kontrollera system till specifika applikationer såsom friktion. Normala- och friktionskrafter mäts för etylammonium nitrat (EAN) mellan en glimmeryta och en kolloidprob vid olika temperaturer eller saltkoncentrationer. Resultaten visar att en ökning av temperatur eller låga koncentrationer av tillsatt salt bara marginellt framkallar ändringar i strukturen på gränsytan och att det adsorberade lagret förblir intakt. När saltkoncentrationen emellertid var tillräckligt hög får den mindre litiumjonen överhanden och ytsammansättningen ändras. Ytlagret av en liknande jonvätska undersöks också vid tillsättning av salt och resultaten avslöjar att litiumjoner påverkar ytsammansättningen annorlunda beroende på jonstrukturen av jonvätskan. Detta visar att ytselektiviteten starkt beror på jonkemin. En repulsiv dubbellagerkraft yttrar sig anmärkningsvärt för EAN vid 393 K vilket inte observeras vid lägre temperaturer. Detta indikerar en ändring i EANs mikroskopiska sammansättningsbeteende och har generella återverkningar för hur jonvätskor uppfattas. En ny metod har utvecklats baserad på en kvartskristall mikrovåg för att undersöka hur ytsammansättningen av jonvätskor reagerar på polarisering. Denna metod visar att det adsorberade lagret av både en ren jonvätska och en jonvätska löst i olja kan kontrolleras genom att applicera spänningar med olika tecken och storlekar. Dessutom möjliggör metoden två oberoende tillvägagångssätt för att övervaka laddningarna under polarisering vilket kan användas för att kvantifiera ytsammansättningen. Tekniken ger också information om jonkinetik och ytselektivitet. Detta arbete bidrar till den grundläggande förståelsen av gränsskiktet mellan fasta ytor och jonvätskor och visar att ytsammansättningen av jonvätskor kan kontrolleras och övervakas med olika tillvägagångssätt. / <p>QC 20160518</p>

Palladium complexes of bis(di-tert-butylphosphinomethyl)benzene (DTBPMB) show remarkably high activity as alkene methoxycarbonylation catalysts, in addition to numerous other catalytic conversions, and are currently being commercialised by Lucite in ethene methoxycarbonylation to methyl propanoate. Any large-scale exploitation of this catalyst system for heavier products, however, is likely to be hindered by catalyst-product separation problems common to homogeneous catalysts; hence modification of this catalyst system to allow facile product separation was investigated. Tethering of DTBPMB residues onto polystyrene via Suzuki-type coupling of suitable precursors onto bromopolystyrene and boronic acid functionalised polystyrene resins was investigated and the phosphine was successfully immobilised. Phosphination of the resins was not complete however and as such there is concern that other phosphine residues may be present which do not exhibit a bidentate binding motif. The synthesis of a potassium sulfonate derivative of DTBPMB (KBPMBS) was successful and immobilisation of this onto ion exchange resins was also investigated. Some preliminary results from studies into 1-octene methoxycarbonylation using palladium complexes of these resins were obtained. Supporting of this diphosphine onto silica via a sol-gel co-condensation methodology was also investigated; the synthesis of a suitably functionalised precursor containing a sulfonamide linkage was successful via protection of the diphosphine using borane. Although formation of the silica support was successful, attempts to deprotect the phosphine-borane resulted in cleavage of the ligand from the support. An alternative route to this supported ligand was attempted and others discussed. Synthesis of a suitable sol-gel precursor via alkene hydrosilation was also attempted and is discussed. Supporting of the sulfonated phosphine, KBPMBS onto silica functionalised with imidazolium tethered residues was also investigated, although complete leaching of the phosphine from the support by methanol washing was observed. Immobilisation of the synthesised KBPMBS ligand in an ionic liquid (IL) phase was investigated. Complex formation and catalytic activity were demonstrated and a positive effect on conversion was observed upon addition of carbon dioxide to the system; possibly due to the increased CO solubility within the IL phase. Efficient product separation from the IL-immobilised catalyst system was demonstrated, both by organic extraction and using supercritical carbon dioxide flow. However, poor catalyst stability under these conditions appears to present a barrier to recycling this system, with loss of conversion observed on catalyst recycling. Other attempts to immobilise the DTBPMB ligand are discussed and reduction of the sulfide derivative of DTBPMB was demonstrated using hexachlorodisilane, which could be used as a general synthetic strategy for protecting highly electron rich phosphines. It is possible that increasing the bulk of the DTBPMB ligand may increase catalyst stability and result in catalyst systems with higher turnover numbers. Therefore syntheses of bulky ligands based on the DTBPMB backbone were investigated. 1,2,4,5-tetrakis(di(tert-butyl)phosphinomethyl)benzene was successfully synthesised although palladium complexes of this showed no activity in catalytic methoxycarbonylation. Attempts to synthesise a related biphenyl-based tetraphosphine is also discussed, although isolation of this in a pure form was not achieved. Routes toward tetraphenyl and dimethyl-diphenyl functionalised derivatives of DTBPMB have also been explored, although only a monophosphine was isolated due to difficulties in obtaining an intermediate di(chloromethyl) precursor in both synthetic pathways, although this now appears to have been overcome.

Submitted in fulfillment of the requirements for the degree of Doctor of Technology: Chemistry, Durban University of Technology, Durban, South Africa, 2015. / This thesis forms part of the Council for Scientific and Industrial Research, Forestry and Forest Products Research Centre (CSIR-FFP) biorefinery project which aims at developing and implementing novel industrial processes production of cellulose textile fibres. The focus of this study is to investigate the dissolution of South African Eucalyptus raw (unbleached) and final (bleached) dissolving pulp and saw dust wood in an ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate [Emim][OAc] and the co-solvents [dimethylsulfoxide (DMSO)] or [dimethylformamide (DMF)] mixtures, to obtain regenerated cellulose by the further addition of water and acetone. The IL/co-solvent mixtures were able to dissolve the raw and final pulp samples at 120 ˚C for 6 hours whereas the sawdust wood dissolved in 10 hours. The IL/DMF mixture gave higher cellulose recoveries of 41.88 % for the raw pulp, 49.89 % for the final pulp sample and 32.50 % for sawdust wood while the IL/DMSO mixture gave a recovery of 15.25 % for the raw pulp sample, 36.25 % for the final pulp sample and 17.83 % for the sawdust wood sample. The regenerated cellulose materials were characterized by Fourier Transformer Infrared Spectroscopy (FTIR), Nuclear Magnetic Resonance (NMR), Scanning Electron Microscopy (SEM), Thermo gravimetric Analysis (TGA) and Powder X-Ray Diffraction (pXRD), and compared with a standard microcrystalline of cellulose. It was observed that the FTIR and NMR spectra of the regenerated cellulose and MCC were similar which then indicates that no chemical reaction occurred during the dissolution and regeneration process of cellulose. SEM and X-ray diffraction (XRD) patterns of the results showed that after dissolution the cellulose I (native form), the crystalline structure was completely converted into cellulose II (amorphous) structure, and this was due to the removal of lignin and decrease in cellulose crystallinity. TGA results showed that the regenerated cellulose samples have higher char yields compared to the MCC which is due to the IL remaining in the regenerated cellulose. It was also observed that the addition of the co-solvents decreased the viscosity of the IL mixture, facilitating dissolution of the cellulose that led to additional swelling and reduction of the recalcitrant nature of the cellulose crystalline structure and intermolecular interactions. This led to increased accessibility and dissolution of the cellulose. The findings in this study have the potential to bring ILs closer to applications for biomass technology in particular for an economically viable dissolution method for biomass because ILs have a benefit of being easily separated from the anti-solvent, which provides a simple solution for IL recycle ability and re-use. The novel aspect of this study is: . This is the first study in the South African context to examine the influence of the lignin on the dissolution and regeneration of Eucalyptus sawdust wood and dissolving pulp. / D

The swelling properties of Bentonite are highly affected by clay content and the clay-water interactions that arise from the ion distribution in the diffuse double layer formed near the charged montmorillonite (or smectite) surfaces. Existing continuum models describing the electric double layers, such as classical Poisson-Boltzmann and DLVO theory, ignore the ion-ion correlations, which are especially important for multivalent ions at high surface charge and ionic strength. To better understand the clay-water interactions, atomistic models were developed using both density functional theory of fluids (DFT) as well as classical molecular dynamics (MD) methods. In order to increase our understanding of water-saturated, swelling smectite clays, a DFT, technique was initially developed that allowed more accurate predictions of important thermodynamic properties of the diffuse double layers. This DFT approach was then extended to handle systems with mixtures of different sizes and charges. The extended DFT model was verified against experiments and Monte-Carlo simulations. One practical application was to predict the ion exchange equilibria in Bentonite clays, which have wide practical usage in different areas. Nevertheless, in the DFT work it was realized that DFT demands that the particles, ions in this case, which are described as hard spheres, realistically cannot be described as such at low water loadings, when ion specific hydration forces govern the electric double layer properties. To study how the deformation of the hydration shells of Ca2+ influences the properties of compacted smectite clays, MD simulations using the CLAYFF forcefield were employed in order to account for the deformation of the hydration shells. Comparisons of DFT and MD modeling then allowed to demonstrate under which conditions DFT modeling becomes increasingly inaccurate and when it still can give accurate results. / Under senare år har mycket forskning ägnats åt att förstå egenskaperna hos svällande leror som används för att skydda mot läckage av föroreningar från kontaminerade områden och från framtida slutförvar av radionuklider. Den fria svällningen förorsakas av de starka osmotiska krafter som uppstår när vatten tränger in mellan de tunna elektriskt negativt laddade lermineralskikten och löser de laddningskompenserande jonerna i det diffusa dubbelskiktet. I flera arbeten användandes av sk. kontinuum-teori har vattenmolekylens form, specifika orientering och bindning till katjonerna i de nanometerstora utrymmen mellan lerpartiklarna ej beaktats samt ej heller hur de hydratiserade jonerna orienteras på de atomärt ojämna ytorna. Detta möjliggörs dock genom modellering av de enskilda atomernas och jonernas interaktioner med molekyldynamik simuleringar, MD. I detta arbete har programmet Gromacs använts tillsammans med kraftfältet CLAYFF för att studera dessa fenomen i montmorillonitleror med natrium- och kalciumjoner. Simuleringarna visar att natrium bildar transienta innersfärkomplex vilka orienterar sig i bi-triangulära fördjupningar på ytan, ungefär 3.8 Å från mitt-planet mellan lerytorna. Denna orientering observeras ända upp till att avståndet mellan ytorna ökat till större än motsvarande fem lager vattenmolekyler mellan lerpartiklarnas ytor. Detta sker inte med kalcium, oberoende av avståndet mellan ytorna. Natriumjoner koordineras med fyra vattenmolekyler och en syreatom på leran vid ett lager vatten mellan ytorna och med fem till sex vattenmolekyler, ortogonalt orienterade med ökande mängd vatten mellan ytorna, och med en hydratiserad jon-radie av 3.1 Å. Kalcium koordinerar till sju vattenmolekyler vid ett vattenlager mellan ytorna, men ökar till åtta ortogonalt orienterade vattenmolekyler med en jonradie på 3.3 Å vid större avstånd. Generellt visas att när avståndet mellan lerytorna är mindre än ca 10 Å, deformeras de annars symmetriskt hydratiserade jonerna. En jämförelse mellan MD simuleringar och med klassisk täthetsfunktionalteori, DFT, visar att den senare inte kan beskriva hur yttersfärkomplexen samverkar med laddningarna bundna närmast ytan, dvs i Stern-lagret. / <p>QC 20170403</p>