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Chemistry

WWU Graduate School Collection

Theses/Dissertations

2020

Articles 1 - 11 of 11

Full-Text Articles in Physical Sciences and Mathematics

Polybenzoxazine-Grafted Composites: Accelerated Polymerization Of Benzoxazine Resins From Bulk- To Microscale Mesylated Materials, Cassidy L. Crickmore Jan 2020

Polybenzoxazine-Grafted Composites: Accelerated Polymerization Of Benzoxazine Resins From Bulk- To Microscale Mesylated Materials, Cassidy L. Crickmore

WWU Graduate School Collection

Benzoxazine-based resins often afford high modulus and high glass transition polymers that are desirable for creating safe and reliable thermoset parts and composites. However, benzoxazine resins have had limited widespread deployment into industry due to their high cure temperature. By blending functionalized glass substrates with the benzoxazine monomer, we hypothesize that the cure temperature of thermosetting resin can be lowered. The structure and purity of the particles, determined by NMR and FTIR, will be presented. DSC studies on the stability and cure accelerating properties of blends composed of functionalized glass substrates and benzoxazine monomer will be determined and compared against …

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Synthetic Studies On Guaipyridine Alkaloids: Rupestines B And C, Evangeline Starchman Jan 2020

Synthetic Studies On Guaipyridine Alkaloids: Rupestines B And C, Evangeline Starchman

WWU Graduate School Collection

The rupestines, a family of guaipyridine alkaloids, are isolated from the plant Artemisia rupestris. Historically, this plant was used intraditional Chinese medicine due to its reported antitumor, antibacterial, and antiviral activities as well as reported protection of the liver. The rupestines can only be isolated from their parent plant in small quantities, making the total synthesis of these guaipyridine alkaloids of particular interest. Cananodine, anotherguaipyridine alkaloid, is a biologically active compound that can be isolated in small quantities from the fruits of Cananga odorata and displays activity against two types of hepatocellular carcinoma cell lines. It is hypothesized that the …

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Allylic Benzoate Reductions: A Study On Stereospecificity, Michael A. Leitch Jan 2020

Allylic Benzoate Reductions: A Study On Stereospecificity, Michael A. Leitch

WWU Graduate School Collection

Herein we report results from experiments aimed at better understanding SmI2(H2O)n reductions of allylic benzoates adjacent to a trisubstituted alkene. When flanked by both a chelating group and stereodirecting group, these reactions can occur with complete regioselectivity and good diastereoselectivity (up to 90:10). Initial experiments suggested that the reaction was stereospecific to alkene geometry. However, further experimentation has revealed that the alkene stereospecificity is substrate dependent. For instance, if the geminal alkene substituents are alkyl, results show the reaction to be stereospecific, but if one of the substituents is a phenyl group the reaction is still stereoselective but not stereospecific. …

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Plasmonic-Based Hybrid Nanomaterial: From Synthesis To Application, Maggie Wang Jan 2020

Plasmonic-Based Hybrid Nanomaterial: From Synthesis To Application, Maggie Wang

WWU Graduate School Collection

Gold nanoparticles, particularly gold nanorods, have been widely used as sensors and imaging agents due to their unique and tunable morphology-dependent properties and intriguing plasmonic resonance. However, the increasing need of new materials with enhanced properties and functionality led scientists to discover novel hybrid nanomaterials, which involves the formation of two or more components into one nanoplatform. Hence, gold nanorod-based hybrid nanomaterials exhibit simultaneous synergistic effects between the phenomenal plasmonic properties from gold nanorods and the intrinsic properties of the other constituents. The functionality of gold nanorod-based hybrid nanomaterials greatly increases due to its enhanced performance characteristics, which directly impacts …

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Engineering Class A Sortases: Activity And Selectivity Of Hybrid And Ancestral Variants, Sarah Struyvenberg Jan 2020

Engineering Class A Sortases: Activity And Selectivity Of Hybrid And Ancestral Variants, Sarah Struyvenberg

WWU Graduate School Collection

Bacterial sortases are cysteine transpeptidases that anchor virulence factors to the surface of bacterial cells. Sortases are a powerful tool utilized for protein engineering that allow researchers to modify proteins at the protein level, not the DNA level. However, important limitations to utilization of sortases for engineering purposes exist; namely, SrtA from S. aureus is a relatively modest enzyme compared to other SrtA enzymes and is very specific for the LPXTG motif. Previous work from our collaborators and others revealed that sortases from different species can recognize alternative sequences and that activities can vary widely. We were curious about how …

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Synthesis And Characterization Of Earth Abundant Metal Phosphide Photocatalysts For The Reverse Water Gas Shift Reaction, John D. Springer Jan 2020

Synthesis And Characterization Of Earth Abundant Metal Phosphide Photocatalysts For The Reverse Water Gas Shift Reaction, John D. Springer

WWU Graduate School Collection

This thesis work focuses on the synthesis and characterization of photocatalysts composed of metal phosphide nanoparticles on a titania (TiO2) support for the conversion of carbon dioxide (CO2) to carbon monoxide (CO) via the reverse water gas shift (RWGS) reaction. The CO product can be subsequently converted to solar fuels such as methanol (CH3OH), thus lowering the carbon footprint associated with the combustion of liquid fuels. The photocatalysts are composed of a tunable light absorber, indium-gallium phosphide (InxGa1-xP), and nickel phosphide (Ni2P) as a co-catalyst, on TiO2. The photocatalysts are characterized using diffuse reflectance ultraviolet-visible (UV-Vis) spectroscopy to determine band …

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Carbodiimides: Templates For Covalent Adaptable Networks And Post Polymerization Modification, Alberto J Melchor Bañales Jan 2020

Carbodiimides: Templates For Covalent Adaptable Networks And Post Polymerization Modification, Alberto J Melchor Bañales

WWU Graduate School Collection

The global increase in plastic waste has negatively impacted the environment, human health, and economy. Plastics that lack recyclability, such as thermosets are some of the main culprits. To help address this issue, reactive functional groups can be incorporated in macromolecules, enabling straightforward post-polymerization modification (PPM) that can enhance their ability to be recycled. This thesis studied carbodiimides as a reactive functional group for facile PPM with amines through a catalyst-free transformation to N,Nʹ,Nʺ-trisubstituted guanidines. Small molecule studies showed that N,Nʹ,Nʺ-trisubstituted guanidines underwent a reversible thermal exchange reaction without a catalyst. The newly found thermal exchange reaction, termed thermal guanidine …

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Development Of Ti-Dftb: Transition Dipole Moment Calculations In A Time-Independent Density Functional Tight-Binding Framework, Megan Deshaye Jan 2020

Development Of Ti-Dftb: Transition Dipole Moment Calculations In A Time-Independent Density Functional Tight-Binding Framework, Megan Deshaye

WWU Graduate School Collection

Here we discuss the development of a time-independent excited state computational method that consists of three augmentations to the semi-empirical electronic structure package, DFTB+ 19.1. The density functional based tight binding method (DFTB) is an approximation of Kohn-Sham (KS) density functional theory (DFT) wherein the energy functional is expanded to second order with respect to density fluctuations. Application of a delta self-consistent field (delta-SCF) approach within DFTB has allowed for the variationally optimized calculation of spin-purified excited state (ES) properties, and forms the foundation of our time-independent DFTB (TI-DFTB) framework. Selection of KS spin orbitals based on the character of …

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Organic Molecular Crystal Engineering Via Organic Vapor-Liquid-Solid Deposition, Griffin Reed Jan 2020

Organic Molecular Crystal Engineering Via Organic Vapor-Liquid-Solid Deposition, Griffin Reed

WWU Graduate School Collection

Control over the size, shape, topology, orientation, and crystallographic phase of organic molecular materials is critical for a wide array of applications ranging from optoelectronics to pharmaceutical development. Herein, we demonstrate a relatively low-cost approach for fabricating single crystals with controlled sizes, shapes, microscale periodic features, preferred orientations and specific molecular packing modes. These features allow for the fabrication of intricate arrangements of single crystals for incorporation into complex device architectures, and potentially the endowment of tailored optical, electronic, thermal, and mechanical properties onto these materials. Patterning is achieved by utilizing an organic-vapor-liquid-solid (OVLS) deposition scheme paired with traditional photolithography …

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Activation Of Nitrite And Carbon Dioxide By Cobalt Centered Redox Active Ligand Featuring A Hemilabile Pendant Amine, Douglas F. Baumgardner Jan 2020

Activation Of Nitrite And Carbon Dioxide By Cobalt Centered Redox Active Ligand Featuring A Hemilabile Pendant Amine, Douglas F. Baumgardner

WWU Graduate School Collection

Carbon dioxide (CO2) and bioavailable nitrogen in the form of nitrates (NO3-) and nitrites (NO2-) are serious environmental pollutants. However, without economic incentives there is little interest in remediation of these pollutants outside of laboratory scale experiments. CO2 can be converted to carbon monoxide (CO), a valuable building block in Fischer-Tropsch sourced fuel, and NO3- and NO2- can be converted to ammonia, another important chemical building block. However, both require effective, low-cost catalysts to be financially viable options. This thesis seeks to demonstrate the conversion of CO …

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Lsc Fabrication And Design: Bulk Polymerization And Ultrathin Architectures, Justin T. Doyle Jan 2020

Lsc Fabrication And Design: Bulk Polymerization And Ultrathin Architectures, Justin T. Doyle

WWU Graduate School Collection

Renewable energy technologies that access underutilized spaces in the built environment will need to be implemented, on a large scale, to curtail trending increases in global temperature. Luminescent Solar Concentrators (LSCs) are one such technology. They employ luminophores doped into polymer sandwiched in between glass plates, that redirect sunlight to the device periphery where photovoltaics are attached, producing power. Current devices do not have high enough efficiencies for commercialization. One of the biggest barriers is fluorophore aggregation which causes waveguide refractive index fluctuations which result in parasitic losses from the waveguide. In this work Copper Indium Disulfide/Zinc Sulfide (CIS/ZnS) quantum …

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