Physical Sciences and Mathematics Commons^™

The Investigation Of Asphaltene-Naphithenic Acid And Asphaltene-Surface Interactions, David Tristan Heaps

Dissertations

Asphaltenes represent a ubiquitous problem in the oil industry due to their adverse effects on recovery, production, and processing equipment. These problems have affected oil companies throughout the world, resulting in significant financial losses. In order to expand the existing body of knowledge related to asphaltenes, we have examined how the presence of naphthenic acids contributes to the particle aggregation and sedimentation behavior of asphaltene suspensions as well as how the physics and chemistry of a substrate affect asphaltene adsorption/deposition.

The flocculation of asphaltenes in the presence of naphthenic acids was investigated using dynamic light scattering (DLS), near-infrared spectroscopy (NIR), …

Design Of Covalently Dynamic Films And Coatings: Analysis Of Biocatalyzed Kinetic Behavior In Soft Condensed Matter, Pirro Cipi

Dissertations

Reversibly adjusting surface and bulk properties of materials is advantageous to many applications and will vastly expand current polymer capabilities. A novel strategy was developed to render materials capable of “smart” surface and bulk properties with the aid of embedded biocatalyst and latent functional groups that are selectively activated in the presence of biocatalyst to undergo chemical transformation. The research presented herein focused on systematically characterizing the activity of lipase catalysts embedded in poly (alkyl methacrylate)s simultaneously with functionalized components, either as diffusing within the polymeric matrix or tethered to the matrix. Lipase activity, ester forming (synthetic) or ester breaking …

Effects Of Molecular Architecture On Fluid Ingress Behavior Of Glassy Polymer Networks, Matthew Blaine Jackson

Dissertations

This manuscript demonstrates the synthesis of glassy polymer network isomers to control morphological variations and study solvent ingress behavior independent of chemical affinity. Well-controlled network architectures with varying free volume average hole-sizes have been shown to substantially influence solvent ingress within glassy polymer networks. Bisphenol-A diglycidyl ether (DGEBA), bisphenol-F diglycidyl ether (DGEBF), Triglycidyl p-aminophenol (pAP, MY0510), Triglycidyl maminophenol (mAP, MY0610), and tetraglydicyl-4,4’-diamino-diphenyl methane (TGDDM, MY721) were cured with 3,3’- and 4,4’-diaminodiphenyl sulfone (DDS) at a stoichiometric ratio of 1:1 oxirane to amine active hydrogen to generate a series of network architectures with an average free volume hole-size (V_h) …

Free Volume Studies Of Various Polymeric Systems Using Positron Annihilation And Pvt-Eos Analyses, Mukul Kaushik

Dissertations

The glass transition phenomenon and free volume behavior below and above the glass transition temperature of various polymeric systems have been investigated. Several novel polymeric systems were considered for this study. Two generations of hyperbranched polyols, H40 and H20, were selected due to large number of hydroxyl groups on the periphery and within the bulk. The effect of hydrogen bonds and molecular weight was related with the glass transition and free volume behavior for the whole range of experimental temperature. The free volume behavior was experimentally studied using PVT and PALS to determine occupied volume, fractional free volume and number …

Development And Utilization Of Digital Image Correlation Techniques For The Study Of Structural Isomerism Effects On Strain Development In Epoxy Network Glasses, Stephen Robert Heinz

Dissertations

The specific aim of this dissertation is to present the findings regarding the effects of molecular structure on macroscopic mechanical performance and strain development in epoxy networks. Network molecular structure was altered through monomer isomerism and crosslink density/molecular weight between crosslinks. The use of structural isomerism provided a pathway for altering mechanical performance while maintaining identical chemical composition within the network. Isomerism was investigated primarily by the curing of diglycidyl ether of bisphenol A (DGEBA) using either the para- or meta-substituted derivatives of diaminodiphenyl sulfone (DDS). Additional insights into isomerism were gained through the investigation of networks composed of either …

Chemical, Biological, And Preliminary In Vitro Studies Of Novel Vanadium(Iv) Complexes With Schiff Bases And Thiosemicarbazone Ligands, Nerissa Abigail Lewis

Master's Theses

9-Anthraldehyde-N(4)-methylthiosemicarbazone (MeATSC), potassium (E)-2-(2-hydroxybenzylideneamino)-3-(1H-indol-3-yl)propanoate (K[(Sal-L-tryp)] and 2-(2-hydroxybenzylamino)-3-(1H-indol-3-yl)propanoic acid (the reduced Schiff base) were prepared using known synthetic procedures. Two novel thiosemicarbazone ligands, (E)-N-ethyl-2-(4-hydroxy-3-methoxybenzylidene)hydrazinecarbothioamide (N-Ethhymethohcarbthio) and (E)-N-ethyl-2-(1-(thiazol-2-yl)ethylidene)hydrazinecarbothioamide (acetylethTSC), were also prepared. All ligands were characterized by FT IR and electrochemistry. N-Ethhymethohcarbthio were characterized by elemental analysis whereas the reduced Schiff base and K[(Sal-L-tryp)] were characterized by ESI MS. X-ray crystallography was also used to characterize acetylethTSC. The ligands were then reacted with [VO(Sal-L-tryp)(H2O)] (1) (Sal-L-tryp = N-salicylidene-L-tryptophanate) to produce the …

Continuous Analysis Of Photocatalytic Activity In Thin-Films And Coatings, Steven Michael Allee

Master's Theses

Materials that undergo photocatalytic reactions create evolved gases due to ultraviolet light decomposition. Current methods of measuring these gases typically result in destruction of the sample. A test fixture was developed to measure evolved gases in a nondestructive manner through the utilization of a flow-through sensor array system. Preliminary testing indicates responsive measurements down to parts-per-billion sensitivity for some gases and will be compared with mass spectrometry measurements. Further development of this process could lead to the ability to measure photocatalytic reaction gases on a continuous basis without interruption of the process or destruction of materials introduced to the system.

Exploration In Metallic Nitride Fullerenes And Oxometallic Fullerenes: A New Class Of Metallofullerenes, Mary Alice Mackey

Dissertations

Research groups around the world have taken an interest in the synthesis, purification, characterization, and functionalization of Metallic Nitride Fullerenes (MNFs) since their discovery in 1999. This dissertation details the discovery of another new class of molecules—Oxometallic Fullerenes (OMFs).

There are many groups worldwide doing research on MNFs, and there is a large database of published MNF research, but we have had a unique opportunity to fill a research void on OMFs as at present no one else is doing research on these molecules; herein we take molecules that we discover and perform seminal research relating to them. MNF research …

Synthesis And Characterization Of Acceptor: Donor Block Copolymers For Organic Photovoltaics, Brandon Cory Achord

Dissertations

Mankind needs sources of clean power. Photovoltaic (PV) cells, in use since 1839, have proven reliable and practical for certain applications. PV cell efficiency has changed over the years from 1-2% to ultra-high efficiency cells operating at efficiencies greater than 40%. Organic photovoltaics are a potential transformative technology platform. The potential for cell use, efficiency and cost are all parts of the research and development focus at the time this document was written. This research was initiated with a focus on the synthesis and understanding of the variables effecting acceptor-donor block copolymer. The self-assembled morphology resulting from varying volume ratios …

Physical And Electrical Properties Of Trimetallic Nitride Template Endohedral Metallofullerenes And Their Polymer Nanocomposites, Hanaa Mohammed Ahmed

Dissertations

The main objective of this study was characterization of pure metallic nitride fullerene, MNF, and MNF containing polymers to evaluate these materials as suitable devices for tunable applications. Polymer-fullerene nanocomposites consisting of linear polyurethane (PU) segments crosslinked via polyhydroxylated fullerenes (C₆₀ and Sc₃N@C₈₀, a metallic nitride fullerene) were prepared and characterized for their mechanical and dielectric properties using dynamic mechanical analysis (DMA) and broadband dielectric spectroscopic techniques. Polyhydroxylated fullerenes C₆₀(OH)₂₉ and Sc₃N@C₈₀(OH)₁₈ were synthesized in a high yield through a solid-state high sheer ball-milling procedure and were …

Detection Of Hydrogen In A Two-Phase Cryogen Flow Stream With Thermal Protection Design Configurations, Anton Dmitrievitch Netchaev

Master's Theses

All commercial liquid-propelled rockets use hydrogen as means to reach outer space. These rocket boosters are tested on the ground and use hydrogen as means of purging the remaining explosive gasses left in the test tanks. To conserve helium, a non-renewable resource, a test fixture was developed to characterize and test sensors that could improve the accuracy and response of the current system. By improving response time of the system, helium waste during the purge process can be minimized. The test fixture was constructed to simulate temperatures and pressures that are encountered at the testing facilities. The test fixture is …

Self-Repairable Polymeric Networks: Synthesis And Network Design, Biswajit Ghosh

Dissertations

This dissertation describes the design, synthesis and development of a new class of polymeric networks that exhibit self-repairing properties under UV exposure. It consists of two parts: (a) modification and synthesis of oxetane (OXE), and oxolane (OXO) substituted chitosan (CHI) macromonomer, and (b) design, and synthesis of self-repairing polyurethane (PUR) networks consisting of modified chitosan. Unmodified CHI consisting of acetamide (-NHCOCH₃), primary hydroxyl (-OH), and amine (-NH₂) functional groups were reacted with OXE or OXO compounds under basic conditions in order to substitute the 1° –OH groups, and at the same time, convert -NHCOCH₃ functionalities …

Precision Synthesis Of Functional Materials Via Raft Polymerization And Click-Type Chemical Reactions, Joel Diez Flores

Dissertations

The need to tailor polymeric architectures with specific physico-chemical properties via the simplest, cleanest, and most efficient synthetic route possible has become the ultimate goal in polymer synthesis. Recent progress in macromolecular science, such as the discoveries of controlled/“living” free radical polymerization (CRP) methods, has brought about synthetic capabilities to prepare (co)polymers with advanced topologies, predetermined molecular weights, narrow molecular weight distributions, and precisely located functional groups. In addition, the establishment of click chemistry has redefined the selected few highly efficient chemical reactions that become highly useful in post-polymerization modification strategies. Hence, the ability to make well-defined topologies afforded by …

Mechanisms Of Non-Enzymatic Peptide Bond Formation: Thioester And Transamidation Routes, Danielle Amie Landry

Master's Theses

The reaction mechanisms employed during non-ribosomal peptide (amide) synthesis in the non-ribosomal modular enzyme complex and in the enzyme glutaminyl cyclase were also used for spontaneous peptide (amide) synthesis in a buffered, abiotic solution. Analytical analyses revealed that spontaneous peptide (amide) bond formation occurred under mild prebiotic conditions during both the thioester-based production of phenylalanine peptides and peptidyl thioesters, and the spontaneous cyclization of glutamine t-butyl ester (Gln-tbe) into pyroglutamic acid t-butyl ester. Internal standard-based quantitative MS determined that 4.9 x 10-5 sec-1 was the rate constant for spontaneous Gln-tbe cyclization in imidazole buffer, pH 7, at 50°C, and that …

Modification And Evaluation Of Fuel Cell Membranes, Amol Prataprao Nalawade

Dissertations

The primary goals of this study were modification of existing Nafion^® membranes and characterization of newly developed hydrocarbon-based membranes for high temperature fuel cell applications. Various Nafion^®/silicate nanocomposites were formulated via in situ sol-gel reactions for tetraethylorthosilicate. Different silicate composition profiles generated across membrane cross-sections were investigated by EDAX/ESEM. Composite water uptake, proton conductivity and fuel cell performance were comparable to that of unmodified Nafion^®. Tafel analysis showed better electrode kinetics for composites having more silicate in the middle and less or no silicate at electrolyte-electrode interfaces. All composites showed reduced fuel cross-over and superior …

Sensitive Detection Of High Explosives Using Electrogenerated Chemiluminescence, Suman Parajuli

Dissertations

The core of this dissertation lies in the search of analytical tools which can be used to detect and quantify the high explosives confiscated from suspects in transportation hubs and from soil and water bodies where these explosives pose a greater threat to public health and safety. High explosives, namely, hexamethylene triperoxide diamine (HMTD), triacetone triperoxide (TATP), trinitrotoluene (TNT), and pentaerythritol tetranitrate (PETN), were detected and quantified by electrochemical methods such as electrogenerated chemiluminescence (ECL) and cyclic voltammetry (CV).

Sensitive detection and quantification of HMTD, one commonly used explosive by terrorists, was presented first in this dissertation on the basis …

Ruthenium-Based Olefin Metathesis Catalysts Bearing Ph-Responsive Ligands: External Control Of Catalyst Solubility And Activity, Shawna Lynn Balof

Dissertations

Sixteen novel, Ru-based olefin metathesis catalysts bearing pH responsive ligands were synthesized. The pH-responsive groups employed with these catalysts included dimethylamino (NMe₂) modified NHC ligands as well as N-donor dimethylaminopyridine (DMAP) and 3-(o-pyridyl)propylidene ligands. These pH-responsive ligands provided the means by which the solubility and/or activity profiles of the catalysts produced could be controlled via acid addition. The main goal of this dissertation was to design catalyst systems capable of performing ring opening metathesis (ROMP) and ring closing metathesis (RCM) reactions in both organic and aqueous media.

In an effort to quickly gain access to new …

Photopolymerized Thiol-Ene Networks For Gas Barrier And Membrane Applications, Luke Kwisnek

Dissertations

Gas transport and free volume properties of photopolymerized thiol-ene networks for various applications are reported. For basic, commercially-available thiol-ene formulations, oxygen permeation was strictly dependent on the difference between T_test (room temperature for this work) and network T_g. Networks with T_g near T_test demonstrated the lowest values of permeability, diffusivity, and solubility. A robust, high-barrier network was selected for further modification. New networks with embedded functionality were formed using a two-step approach. Thio-Michael addition of a tetrathiol to monofunctional acrylates formed new functional thiol monomers. These functional thiols were combined with an isocyanurate-based triene and …