Efficient optical-to-electrical conversion is a fundamental requirement of a range of silicon devices such as those which employ photodetection, solid-state-imaging and photovoltaic power generation. This thesis investigates the effects of using indium, a deep-level acceptor in silicon, as a dopant for thin film single crystalline silicon solar cells and UV-A detectors. Indium acts as a p-type dopant in silicon and has been proposed previously as a substitutional lattice defect that would enable sub-band gap transitions as described by the so-called impurity photovoltaic (IPV) effect. The physical mechanisms responsible for operation of the devices presented in this work are described. Models for electrical performance, optical absorbance and device fabrication are used as methods to interpret data and optimize device parameters. Specifically, a two-diode model is used to account for the electrical loss mechanisms within a device, while modeling optical absorption by a multilayer structure consisting of Silicon-On-Insulator (SOI) is approached using a novel multi-wavelength numerical model that describes the reflections and transmissions at each of the device’s layers. Additionally, Technology Computer Aided Design (TCAD) simulations were used to optimize the critical fabrication parameters associated with the ion implantation and thermal annealing techniques used during the device fabrication process. Selected from multiple devices fabricated during the course of this work, the most efficient solar cells in SOI (2.5 μm thick active layer) exhibited a maximum conversion efficiency of 4.74 % for indium-doped and 4.16 % for boron-doped layers. The most efficient UV-A detector fabricated in SOI (100 nm thick) exhibited a maximum responsivity to 365 nm light of 20 mA/W for indium-doped and 16 mA/W for boron-doped devices. In both types of devices, indium doping consistently resulted in a relative increase in efficiency when compared to equivalently fabricated, boron doped devices, despite experimental carrier decay measurements confirming the action of the indium as a recombination centre. External and internal quantum efficiency measurements confirm a relative enhancement in absorption, for solar cells and detectors doped with indium, which is correlated with the p-type dopant concentration and the ratio of n-type to p-type concentrations. The origin of the enhancement is postulated to be caused by a relaxation of the momentum-space restrictions associated with undoped silicon, a postulate supported by previously reported absorption data. This thesis presents the first comprehensive data from indium doped silicon devices designed for optical-to-electrical conversion. The implications for a range of widely deployed devices may be significant. / Thesis / Doctor of Philosophy (PhD)

The Sacramento Mountains, a metamorphic core complex that lies in the Colorado River extensional corridor of southeastern California, contains complex lithologic and structural relationships. Detailed mapping and petrographic analysis of lower plate rocks from the central part of the range show that three deformation events have been recorded. An amphibolite facies-grade foliation (Sg), which represents the oldest deformational event (D1), is the predominant fabric in the quartzofeldspathic country rock (grey gneiss). The second deformational event (D2) produced a variably developed greenschist facies-grade fabric (Sm) in the grey gneiss and in two post-D1 plutonic suites. Both of these plutons are thought to be Cretaceous or Tertiary in age. Variations in mylonitic development throughout the lower plate can be attributed to the ratio of strong minerals to weak minerals. Those with high strong-to-weak ratios (eg. granodiorite, diorite, tonalite, quartz diorite) do not form foliations as easily as rocks with low strong-to-weak ratios (eg. granite). This results in a diffuse distribution of mylonitic fabrics and many small scale shear zone boundaries. There is no evidence, however, for a major shear zone boundary (mylonitic front) in the Sacramento Mountains. Northeastward-directed Tertiary extension (D3) resulted in development of multiple high-angle and low-angle faults within and adjacent to the lower plate. Chloritic breccia is found along many of these faults and always cross-cuts the mylonitic fabric. Stage 1 of chloritic breccia evolution was the development of low-angle brittle shear zones and oblique fractures, and was accompanied by deposition of cryptocrystalline epidote. Stage 2 was the formation of conjugate fracture sets at a high-angle to the brittle shear zone accompanied by precipitation of chlorite as well as epidote and other propylitic minerals. Evidence for the importance of both high- and low-angle faulting during the structural evolution of the Sacramento Mountains is found in the many faults both within and adjacent to the lower plate. The upper and lower plates are separated by the Sacramento fault system that includes gently, moderately, and steeply dipping, dip-slip to oblique-slip fault segments. Recent models of core complex development hint at the complexity of fault systems and recognize the importance of high-angle faulting in upper plate rocks. However, most lower plate structures are attributed to low-angle faulting and folding of the fault surface. In the Sacramento Mountains, the lack of evidence for folding of the lower plate plus the development of multiple subvertical faults, both within and between plates, suggests that high-angle faulting was important throughout the evolution of the core complex, and not just in the final stages. / Ph. D.

Melt polymerization and novel monomers enabled the synthesis of polyesters for electronic and biological applications. Inspiration from nature and a passion for environmental preservation instigated an emphasis on the incorporation of renewable resources into polymeric materials. Critical analysis of current research surrounding bisphenol-A replacements and ioncontaining segmented polyurethanes aided in identifying benchmark polymers, including limitations, challenges, and future needs. Structure-property-morphology relationships were investigated to evaluate the polymers for success in the proposed applications as well as to improve understanding of polyester compositions to further design and develop sophisticated polymers for emerging applications. Aiming to utilize the reported [2 + 2] cycloaddition of the known mesogen 4,4’-dimethyltrans-stilbene dicarboxylate (SDE) to overcome ultraviolet (UV) induced degradation issues in electronic encasings, the synthesis of copolyesters containing SDE ensued. 1,6-Hexanediol (HD) and 1,4-butanediol comonomers in varying weight ratios readily copolymerized with SDE under melt transesterification conditions to afford a systematic series of copolyesters. Differential scanning calorimetry revealed all copolyesters exhibited liquid crystalline transitions and melting temperatures ranged from 196 °C – 317 °C. Additionally, melt rheology displayed shear thinning to facilitate melt processing. Compression molded films exhibited high storage moduli, a glassy plateau until the onset of flow, and tensile testing revealed a Young’s iii modulus of ~900 MPa for poly(SDE-HD). These properties enable a wide range of working temperatures and environments for electronic applications. Adding complexity to linear liquid crystalline copolyesters, copolymerization with oligomeric hydroxyl-functionalized polyethers afforded segmented liquid crystalline copolyesters. 4,4’-Biphenyl dicarboxylate (BDE), commercially available diols containing 4, 5, 6, 8, or 10 methylene units, and introducing poly(tetramethylene oxide) or a Pluronic® triblock oligoethers in varying weight % were used to synthesize multiple series of segmented copolyesters. Comparing melting transitions as a function of methylene spacer length elucidated the expected even-odd effect and melting temperatures ranged from 150 °C to 300 °C. Furthermore, incorporating the flexible soft segment did not prevent formation of a liquid crystalline morphology. Complementary findings between differential scanning calorimetry and small-angle X-ray scattering confirmed a microphase-separated morphology. Thermomechanical analysis revealed tunable plateau moduli and temperature windows based on both soft segment content and methylene spacer length, and tensile testing showed the strain at break doubled from 75 weight % to 50 weight % hard segment content. The same compositions Young’s moduli decreased from 107 ± 12 MPa at 75 weight % hard segment to 19 ± 1 MPa with 50 weight % hard segment, demonstrating the mechanical trade-off and range of properties possible with small compositional changes. These segmented copolyesters could find use in high-performance applications including electronic and aerospace industries. A two-step synthesis transformed caffeine into a novel caffeine-containing methacrylate (CMA). Conventional free radical copolymerization with a comonomer known to provide a low glass transition temperature (Tg), 2-ethylhexyl methacrylate (EHMA), allowed the investigation of the effect of small amounts of pendant caffeine on polymer properties. Thermal and iv thermomechanical testing indicated CMA incorporation dramatically increased the storage modulus, however, a microphase-separated morphology was not attained. Association of the pendant caffeine groups through non-covalent π-π stacking could present opportunities for novel thermoplastics and it is proposed that placing the pendant group further from the backbone, and potentially increasing the concentration, could aid in promoting microphase-separation. Alkenes are reactive sites for placing functional groups, particularly those required for polyester synthesis. Methyl 9-decenoate (9-DAME), a plant-based fatty acid, provided a platform for novel biodegradable, renewable, polyesters. A formic acid hydration reaction generated an isomeric mixture of AB hydroxyester or AB hydroxyacid monomers for melt polymerization. Thermal analysis elucidated the plant-based polyesters exhibited a single transition, a Tg of about -60 °C. Aliphatic polyesters commonly crystallize, thus the isomeric mixture of secondary alcohols seemed to introduce enough irregularity to prevent crystallization. These polyesters offer an amorphous, biodegradable, sustainable replacement for applications currently using semi-crystalline poly(ε-caprolactone), which is not obtained from renewable monomers and also exhibits a -60 °C Tg. Additional applications requiring low-Tg polymers such as pressure sensitive adhesives or thermoplastic elastomers could also benefit from these novel polyesters. 9-DAME also was transformed into an ABB’ monomer after an epoxidation and subsequent hydrolysis. Successful gelation under melt transesterification conditions provided evidence that the multifunctional monomer could perform as a renewable, biodegradable, branching and/or crosslinking agent. Novel copolyesters comprised of a bromomethyl imidazolium diol and adipic acid demonstrated potential as non-viral gene delivery vectors. Melt polycondensation produced water dispersible polyesters which bound deoxyribonucleic acid at low N/P ratios. The v polyplexes showed stability in water over 24 h and no cytotoxic effect on human cervical cancer cells (HeLa). A luciferase transfection assay revealed the copolyesters successfully underwent endocytosis and released the nucleic acid better than controls. The copolyesters with pendant imidazolium functionality also provided tunable Tgs, -41 °C to 40 °C, and the ability to electrospin into fibers upon blending with poly(ethylene oxide). These additional properties furthered potential applications to include pressure sensitive adhesives and biocompatible antibacterial bandages. / Ph. D.

Thermotropic liquid crystalline polymers (TLCPs) have attracted great interest because of the combination of their promising properties, which includes high stiffness and strength, excellent processability, and outstanding chemical resistance. TLCPs exhibit inherently low viscosity relative to many other conventional thermoplastics. The low melt viscosity is detrimental to processes requiring high melt strength, such as extrusion blow molding, film blowing, thermoforming and multilayer coextrusion. Our laboratory has developed a unique method to increase the viscosity of TLCPs by first raising the temperature above the melting point (Tm) to exclude all solid crystalline structure, and then lowering the temperature below Tm to super cool the materials. Additionally, the super-cooling behavior of TLCPs allows them to be blended with other thermoplastics possessing lower processing temperatures. The initial focus of this dissertation is to investigate the processing temperature of a representative TLCP in the super-cooled state, using the methods of small amplitude oscillatory shear (SAOS), the startup of shear flow and differential scanning calorimetry (DSC). The TLCP used in this work is synthesized from 4-hydroxybenzoic acid (HBA), terephthalic acid (TA), hydroquinone (HQ) and hydroquinone derivatives (HQ-derivatives). The TLCP of HBA/TA/HQ/HQ-derivatives has a melting point, Tm, of around 280 oC. Once melted, the TLCP can be cooled 30 oC below the Tm while still maintaining its processability. As the TLCP was cooled to 250 oC, a one order magnitude increase in viscosity was obtained at a shear rate of 0.1 s- 1. Additionally, super cooling the TLCP did not significantly affect the relaxation of shear stress after preshearing. However, the recovery of the transient shear stress in the interrupted shear measurements was suppressed to a great extent in the super-cooled state. The second part of this work is concerned with the extrusion blow molding of polymeric blends containing the TLCP of HBA/TA/HQ/HQ-derivatives and high density polyethylene (HDPE), using a single screw extruder. The blends were processed at a temperature of 260 oC which is 20 oC below Tm of the TLCP such that the thermal degradation of HDPE was minimized. Bottles were successfully produced from the blends containing 10, 20 and 50 wt% TLCP. The TLCP/HDPE blend bottles exhibited an enhanced modulus relative to pure HDPE. However, the improvement in tensile strength was marginal. At 10 and 20 wt% TLCP contents, the TLCP phase existed as platelets, which aligned along the machine direction. A co-continuous morphology was observed for the blend containing 50 wt% TLCP. The preliminary effectiveness of maleic anhydride grafted HDPE (MA-g-HDPE) as a compatibilizer for the TLCP/HDPE system was also studied. The injection molded ternary TLCP/HDPE/MA-g-HDPE blends demonstrated superior mechanical properties over the binary TLCP/HDPE blends, especially in tensile strength. Consequently, it is promising to apply the ternary blends of TLCP/HDPE/MA-g-HDPE in the blow molding process for improved mechanical properties. Finally, this work tends to determine how the isothermal crystallization behavior of a TLCP can be adjusted by blending it with another TLCP of lower melting point. One TLCP (Tm~350 oC) used is a copolyester of HBA/TA/HQ/HQ-derivatives with high HBA content. The other TLCP (Tm~280 oC) is a copolyesteramide of 60 mol% hydroxynaphthoic acid, 20 mol% terephthalic acid and 20 mol% 4-aminophenol. The TLCP/TLCP blends and neat TLCPs were first melted well above their melting points, then cooled to the predetermined temperatures below the melting temperatures at 10 oC/min to monitor the isothermal crystallization. As the content of the low melting TLCP increased in the blends, the temperature at which isothermal crystallization occurred decreased. Comparing with neat TLCPs, the blend of 75% low melting TLCP crystallized at a lower temperature than the pure matrices, and the blend remained as a stable super-cooled fluid in the temperature range from 220 to 280 oC. Under isothermal conditions, differential scanning calorimetry (DSC) was not capable of reliably detecting the the low energy released in the initial stage of crystallization. In contrast, small amplitude oscillatory shear (SAOS) was more sensitive to detecting isothermal crystallization than DSC. / Ph. D.

Polyrotaxanes are new polymers. Macrocyclic molecules, such as crown ethers, are threaded by linear or branched polymer chains. There is no covalent bond between the crown ethers and the polymer backbone. After the crown ethers are threaded onto the polymer backbone, both ends of the polymer can be blocked by large end groups. Polyrotaxanes are the topological isomers of blends of crown ethers and polymers. This architectural modification will produce interesting chemical and physical property changes in the polymer such as T_g and T_m, solubility, tensile strength, flexibility of the polymer. The study include crown ethers, blocking groups, poly(azomethine)s A and B, poly(azomethine)rotaxanes A and B synthesis, characterization, and property research. Crown ethers, 21-crown-7, 30-crown-10, 42-crown-14, and 60-crown-20, were synthesized from oligo(ethylene glycol)s and oligo(ethylene glycol) ditosylates with 22-40% yield. The high temperature synthetic method was developed so that the percentage yield of large crown and the small crowns in the same reaction could be controlled. A new purification method, low temperature recrystallization method was developed. The crown ethers properties included melting points, decomposition temperature, chemical shift on NMR spectra were studied. A series of blocking groups were synthesized and characterized. Several synthetic routes were studied, and the best route was the Grignard synthesis. The purification method was improved by recrystallization in cyclohexane or carbon tetrachloride. A by-product, bis(p-t-butylphenyl)methanol, was obtained. The new compounds, p-tri(p-t-butylphenyl)methylaniline and p-tri{(p-t-butylphenyl)methylphenol, were identified by ¹H NMR, FTIR, and elemental analysis. Poly(azomethine)s A and B are liquid crystalline polymers. They are rigid and strong. They have high T_m's and do not dissolve in general solvents. To check the reported information, the synthesis and characterization of these polymers were repeated. They precipitated from the reaction solution when their degree of polymerization reached 3-5. They were not thermally stable and were easily hydrolyzed in strong acids and in GPC column. In order to establish the effectiveness of the blocking groups, a monomeric rotaxane, a di(azomethine)rotaxane, was designed and synthesized. The compound was successfully isolated by multiple reprecipitations and recrystallizations. A 12% yield of this compound was obtained. The largest crown ether that the blocking group could block was 42-crown-14. / Master of Science

Characterizing and preserving available groundwater resources within crystalline rocks is pertinent to understanding and predicting resources for ecosystems worldwide. Crystalline-rock aquifers, with favorable structure and climate, can be pumped year-round to meet local domestic demand. The Ploemeur hydrogeologic site, near the southern coast of Brittany, France, is characterized by a structurally complex fractured mica-schist and granite confined aquifer system. A contact zone, which acts as the main localized flow path through the aquifer, separates the two crystalline units, and a sub-vertical permeable fault zone cross-cuts the crystalline bedrock and contact zone. Using field observations, recharge estimates, and a calibrated three-dimensional numerical multi-zone MODFLOW 6 model, we present preferential flow paths of recharge infiltrating the complex geology of the Ploemeur hydrogeological site during pumping conditions. Using MODPATH to track groundwater and recharge path lines, we determine that water extracted from the aquifer originates from higher elevation areas west of the pumping site. Particle tracking analyses indicate that precipitation simulated over the pumping zone takes a minimum of two years to reach the pumping wells and travels up to 100 m in distance. Analyses of the water budget of the aquifer system using Zonebudget show that storage contributes significantly to the productivity of the system. Based on these analyses, we determine that recharge mechanisms such as piston flow and preferential flow play important roles in the Ploemeur hydrogeologic site. Though the Ploemeur site is unique in its composition and geometry, the methods used to characterize and monitor the aquifer can be applied to fractured crystalline-rock aquifers globally. Fractured crystalline-rock aquifers make up 10% of the region's freshwater sources, thus understanding their flow mechanisms contributes greatly to the management of freshwater resources. / Master of Science / Groundwater aquifers are a common source of freshwater worldwide as groundwater makes up 30% of Earth's freshwater resources. Porous, sedimentary aquifers, made of materials such as sand or gravel, are well studied; however, the less understood aquifers found in crystalline bedrock are also found all over the world. Generally, igneous and metamorphic crystalline rocks are not porous and have low permeabilities, but fractures and faults in the crystalline rock can increase the ability for water to travel through the system. The Ploemeur hydrogeologic site, located on the southern coast of Brittany, France, is a productive fractured crystalline-rock groundwater aquifer producing freshwater year round. The productivity of this aquifer is attributed to the increased hydraulic conductivity associated with the intersection of two permeable features: a subvertical fault zone and a sub-horizontal contact zone. Despite the aquifer's output, recharge travels very slowly into the system due to the depth, heterogeneity, and clay content in an overlying layer of weathered rock fragments and soil. In this study, we create a three-dimensional numerical model using MODFLOW to simulate precipitation in different locations to see how it travels through the aquifer to the site of groundwater pumping. We see that the recharge prefers to travel topographically from regions of higher elevation to lower elevation. The recharge preferentially travels through the geologic features with higher permeabilities, including the fault zone, regolith, and contact zone, but it does still travel through the less permeable, crystalline bedrock units. Even in the features with the higher permeabilities, simulated recharge requires a minimum of 2 years to travel from the land surface to the pumping wells. The pumping wells extract significant water from storage, as seen in our water budget calculations of each geologic unit. We see two recharge mechanisms present in the hydrogeologic site: piston flow, where young water displaces older water from the storage, and preferential flow, where recharge prefers to travel through regions with higher hydraulic conductivity. Understanding the recharge mechanisms in crystalline aquifers is pertinent to our knowledge of freshwater resources as crystalline aquifers make up approximately 10% of all groundwater supplies.

The Striped Rock pluton of the late-Proterozoic Crossnore Plutonic-Volcanic suite is located beneath the Fries Thrust zone in the Blue Ridge province of southwest Virginia. The multiphase granite pluton has been affected by episodes of brittle and crystal plastic deformation at both the microscopic and mesoscopic scales. Brittle deformation preceded and postdated crystal plastic deformation. The pluton is cut by pervasive centimeter-scale cataclasite zones and ductile shear zones that vary in width from a few millimeters to several hundred meters. The majority of mylonite zones in the pluton strike east and northeast and are inclined moderately southeast. Cataclasite zones strike northeast and northwest. Deformation is most intense along the southern contact with the Cranberry gneiss where both pluton and country rock are deformed into a northeast-striking zone of mylonitic augen gneiss. The intensity of deformation decreases northwestward. Southeastdirected normal fault displacement is common to east and northeast-trending shear zones. A minor group of northwest-oriented shear zones dip moderately southwest and northeast and show sinistral, strike-slip displacement. Quartz-, chlorite- and stilpnomelane-filled cracks and veins with northeast and northwest trend uniformly overprint mylonite and cataclasite zones of all scales. Microstructure changes progressively with increasing strain. Feldspar grains are cut by at least two generations of mineralized, dilatant microcracks. Minerals precipitated in the early set of microcracks have undergone extensive crystal plastic deformation. Late-stage microcracks are filled with completely undeformed minerals. The spatial distribution of normal fault mylonite zones is geometrically consistent with generation during 1) late-Proterozoic extension, 2) Mesozoic extension, 3) rigid-body rotation during Paleozoic thrusting, or 4) "gravitational collapse" during Paleozoic thrusting. Field and microstructural evidence favor (4). The exact timing of deformation is not, however, well-constrained. / Master of Science

Step-growth polymerization facilitates the synthesis of a wide range of industrially applicable polymers, such as polyesters and polysulfones. The choice of backbone and end group structure within these polymers drastically impacts the final material properties and processability emphasizing the necessity for thorough understanding of structure-property relationships. Seemingly simple changes, such as exchanging a monomer for its regioisomer, affects the polymers fundamental packing structure triggering a domino effect ultimately influencing the morphological, thermal, mechanical and barrier properties. In conjunction, end groups provide a means by which tunable mechanical properties and application into unique processing methods can be achieved. Synthesizing polyesters with bibenzoate based monomers generates a large range of morphologies. Linear, 4,4' bibenzoate (4,4'BB), is widely considered a mesogenic monomer due to its ability to impart a liquid crystalline (LC) morphology on semi-aromatic polyesters with linear aliphatic spacers. In this body of work, semi-aromatic polyesters using one of 4,4'BB's regioisomers, either 3,4'BB or 3,3'BB, largely resulted in amorphous or semi-crystalline polymers depending on the selection of aliphatic diol. Incorporation of the meta isomer (3,4'BB) into traditionally LC polymers, such as poly(diethylene glycol 4,4'-bibenzoate) and poly(butylene 4,4'-bibenzoate), through copolymerization afforded two polymer series with tunable LC properties. The 3,4'BB exhibited selective disruption of crystalline domains over the LC phase generating a number of polymers with LC glass morphologies. The application of 3,4'BB to a fully-aromatic polyester enabled the synthesis of a novel melt-processable homopolyester with high thermal stability, poly(p-phenylene 3,4' bibenzoate). This structure afforded a nematic LC morphology which revealed beneficial shear-thinning properties similar to industrial standards. The unique LC morphology of this homopolyester inspired further characterization of the range of achievable properties using the basic structure, poly(phenylene bibenzoate), with all the possible regioisomers. This study afforded six polymers systematically varied in chain linearity from a completely meta to a completely para backbone configuration. A range of morphologies were achieved from high Tg amorphous polymers for the meta configurations to semi-crystalline or LC in the polymers with greater linearity. End group functionalization generates influence on polymer properties while limiting the impact on beneficial properties achieved through the backbone structure and packing. Post-polymerization reactions or the addition of a monofunctional endcapper to the polymerization both achieve end group control. In this dissertation, the addition of a monofunctional diester with a sulfonate moiety to a semi-aromatic LC polyester synthesis resulted in a telechelic ionomer. The non-covalent interaction of the ionic groups will hopefully improve the compression and transverse mechanical properties of the LCP. In contrast, post-polymerization functionalization incorporated acrylate groups onto the ends of a basic polysulfones. These reactive groups provided a handle for photo-curing which enabled the 3D printing of the polysulfones using vat photopolymerization. / Doctor of Philosophy / The research within this dissertation encompasses the design of new plastics for consumer and high-performance applications. Since the emergence of synthetic plastics in the 1920’s, these materials have become a necessity in our everyday life with a range of applications in food packaging, microelectronics, architecture, medical devices, automotive, and aerospace. Benefits over metals and glass primarily result from their light weight and wide range of mechanical properties which allow a range of material properties from soft and flexible plastic grocery bags to tough car parts. Different classes of plastics (polymers) are based primarily on the chemicals used to produce the materials, for example polyesters and polysulfones. The chemical structure of these core materials drastically impacts the final properties of the polymers, which in turn influences their application space. This work focused on how subtle changes to these starting chemical structures allows us to tune the final polymer properties. Within the class of polyesters, a focus was placed on materials known as liquid crystalline (LC) polyesters. A liquid crystalline polymer can achieve a physical state between a solid and a liquid which imparts many beneficial properties on the material processing. Liquid-crystal television displays utilized these properties to provide drastically thinner TV’s with higher resolution. Alternatively, LC polyesters find applications traditionally as high-performance fibers, insulators in microelectronics, and stainless-steel replacements in medical applications. Studying the role of chemical structure on the properties of LC polyester enabled the design of materials which improve upon the current technological standards. These changes enabled the design of LC polyesters with lower processing temperatures and the use of fewer starting materials which will inevitably save energy and money during their production. In the case of polysulfones, changing the chemical structure at the end of the polymer chain facilitated the application of novel processing methods, such as 3D printing. The ability to process using this method reduces the amount of material waste during production and provides an opportunity to design novel parts with intricate structures, inaccessible through traditional means.

Recent models of groundwater flow in the Blue Ridge Province suggest multiple aquifers and flow paths may be responsible for springs and seeps appearing throughout the region. Deep confined aquifers and shallow variably confined aquifers may contribute water to spring outlets, resulting in vastly different water quality and suitability for potable water supplies and stock watering. A new Low Flow Recording System (LoFRS) was developed to measure the discharge of these springs that are so ubiquitous throughout the Blue Ridge Province. Analysis of spring discharge, combined with electrical resistivity surveying, aquifer tests, and water chemistry data reveal mixed shallow and deep aquifer sources for some springs, while other springs and artesian wells are sourced only in the deep aquifer. The technique is suitable for rapid characterization of flow paths leading to spring outlets. Rapid characterization is important for evaluation of potential water quality problems arising from contamination of shallow and deep aquifers, and for evaluation of water resource susceptibility to drought. The spring discharge technique is also suitable for use in other locations where fractured rock and crystalline rock aquifers are common. / Master of Science

No / The formation of crystalline molecular complexes of benzoic acid and isonicotinamide with 1:1 and 2:1 compositions has been investigated through solution cocrystallization. The 1:1 complex was solely obtained from ethanol solutions, while either complex could be grown from aqueous and methanol solution by variation of the initial composition. The crystal structures of the 2:1 complex and a monohydrate of isonicotinamide were determined by single crystal X-ray diffraction. The intermolecular interactions in the crystal structure of the complex were compared with other published carboxylic acid:isonicotinamide molecular complexes, which highlights the robust nature of the acid · · · pyridine and acid · · · amide hydrogen bond, which exist in most cases. Complementary computational studies into the binding of pairs of these molecules by ab initio calculations were found to support the experimental observations and highlight the role of solvent in controlling the final crystalline form for multicomponent systems, through altering the hierarchy of intermolecular interactions.