Physical Sciences and Mathematics Commons^™

Hypervalent Iodine Compounds With Carboxylate And Tetrazolate Ligands, Avichal Vaish

Chemistry Theses and Dissertations

In modern organic chemistry, hypervalent (HV) iodine(III) compounds are frequently used as oxidizing agents but application of λ³-iodanes in polymer and material chemistry is still underexplored. This dissertation describes the preparation of dynamic and self-healing materials by employing ligand exchange reactions involving HV iodine(III) compounds of the type ArIL₂ (Ar = Aryl, L = ligand, e.g., carboxylate or (pseudo)halide). These compounds can undergo ligand exchange reactions in presence of nucleophiles (Nu^-) to form ArINu₂. Diacetoxyiodo benzene was successfully employed as a crosslinker to prepare dynamic and self-healing gels derived from carboxylate-containing polymers. Furthermore, …

Polyarylenes: Synthesis And Characterization Towards Advanced Applications, Stephen Budy

Chemistry Theses and Dissertations

A series of semi-fluorinated and non-fluorinated Diels−Alder step-growth polyarylene polymers and co-polymers were synthesized via typical oil bath heating (days/weeks) and more rapid microwave-assisted polymerization (hours). The polymers were characterized by multi-nuclear (¹H, ¹³C, and ¹⁹F) NMR and ATR−FTIR spectroscopy, thermal analysis (TGA, DSC, and DMA), GPC, XRD, water contact analysis (WCA), and refractive index (RI) measurements. The NMR spectra indicated a mixture of para and meta conformations through the polymer backbone increasing to more para with greater fluorine content. Thermal gravimetric analysis revealed the fluorine-containing polyarylenes possessed the highest char yields at almost 80% at …

Greening Of Catalytic Processes Using First-Row Transition Metals For Atom Transfer Radical Addition And Transfer Hydrogenation, Gabrielle Pros

Electronic Theses and Dissertations

This work focused on “greening” catalytic processes, atom transfer radical addition (ATRA), which adds an alkyl halide across and alkene, and transfer hydrogenation/dehydrogenation, which reduces a carbonyl without needing direct H₂ gas. Part of “greening” of these processes is through using abundant first row metals, Cu and Ni for catalysis. One aim was to design new ligands which would be more active in these systems; the second was investigation of additives for catalyst regeneration to reduce the catalyst loading necessary for high yields.

The TPMA^* family was investigated in ATRA. Rate constants followed the expected trend, which increased …

Influencing Factors On The Velocity And Temperature Of Propagating Fronts In Acrylate Composites, Samuel Morris Bynum

LSU Doctoral Dissertations

Thermal frontal polymerization is a type of polymerization in which a localized reaction zone propagates through an unstirred system. It is incumbent upon the production and transport of heat produced as a result of the exothermic reaction associated with free-radical polymerization. First discovered in the 1970s, frontal polymerization has been since utilized to produce a variety of different materials, utilizing a variety of different chemistries. The temperature of the propagating front and the velocity at which it propagates can be influenced via chemical or physical means. We show that through careful selection of monomers and control of the concentration of …

Adsorption Of Polyisobutylene-Based Dispersants Onto Carbon Black, Travis Paul Holbrook

Dissertations

The formation of carbonaceous by-products (e.g. soot) during the operation of an internal combustion engine is unavoidable and the aggregation of this soot leads to deleterious effects including abrasive wear of the engine, increased oil viscosities, and sludge deposition. Dispersants, which are composed of a hydrophobic tail and a polar headgroup, are used as oil additives to aid in the suspension and stabilization of the soot particles. Polyisobutylene succinimide (PIBSI) is the most well-studied class of dispersants and is characterized by a linear architecture and polyamine headgroup that interacts with soot by acid-base and dipole-dipole interactions. As such, there remains …

The Antimicrobial Activity And Cellular Targets Of Plant Derived Aldehydes And Degradable Pro-Antimicrobial Networks In Pseudomonas Aeruginosa, Yetunde Adewunmi

Dissertations

Essential oils (EOs) are plant-derived products that have been long exploited for their antimicrobial activities in medicine, agriculture, and food preservation. EOs represent a promising alternative to conventional antibiotics due to the broad-range antimicrobial activity, low toxicity to human commensal bacteria, and the capacity to kill microorganisms without promoting resistance. Despite the progress in the understanding of the biological activity of EOs, many aspects of their mode of action remain inconclusive. The overarching aim of this work was to address these gaps by studying molecular interactions between antimicrobial plant aldehydes and the opportunistic human pathogen Pseudomonas aeruginosa. We initiated …

Synthesis Of Polycarbamate‒Based Nanoassemblies And Previously Inaccessible Polyglyoxylates, Rebecca Yardley

Electronic Thesis and Dissertation Repository

Self-immolative polymers (SIPs) are a subclass of degradable polymers that can be triggered to depolymerize when exposed to a specific stimulus. The main advantages of SIPs are the controlled and predictable depolymerization, signal amplification, and tunability of the polymer regarding which stimuli it responds to. The work presented in this thesis details the synthesis, characterization, and applications of two different families SIPs: polycarbamates (PCBs) and polyglyoxylates (PGs). PCBs are known to have depolymerization rates that are sensitive to environmental conditions surrounding them. In efforts to modify the depolymerization, PCB was incorporated into amphiphilic diblock copolymers, first with multi-stimuli-responsive poly(2-(dimethylamino)ethyl methacrylate) …

Towards Completely Automated Glycan Synthesis, Matteo Panza

Dissertations

Carbohydrates are ubiquitous both in nature as biologically active compounds and in medicine as pharmaceuticals. Although there has been continued interest in the synthesis of carbohydrates, chemical methods require specialized knowledge and hence remain cumbersome. The need for development of rapid, efficient and operationally simple procedures has come to the fore. This dissertation focuses on the development of a fully automated platform that will enable both experts and non-specialists to perform the synthesis of glycans. Existing automated methods for the synthesis of oligosaccharides are highly sophisticated, operationally complex, and require significant user know-how. By contrast, high performance liquid chromatography (HPLC) …

Modeling And Simulations Of Peptoids, Pu Du

LSU Doctoral Dissertations

Polypeptoids, or poly-N-substituted glycines, are a class of sequence defined polymers that are structural mimics of polypeptides. Polypeptoids currently have received a growing interest due to their improved thermal stability, larger chemical diversity, and easier synthetic pathways as compared to peptides. Their lack of backbone hydrogen bonding and stereochemistry coupled with their easily tunability make them an ideal prototypical model system to study the effect of secondary/non-covalent interactions on self-assembly in solution. In order to develop a molecular level understanding of the effect of secondary interactions on polypeptoid self-assembly, systematic studies were carried out using molecular dynamics simulations on several …

Hierarchical Conjugated Polymer Systems Prepared By Controlled Chain-Growth Polymerization, Chunwa Peter Kei

LSU Doctoral Dissertations

π-Conjugated polymer materials may have a significant economic impact on society by providing means for designing affordable, flexible, and portable organic electronic devices. Their successful commercialization will depend on major scientific advancements, which will challenge human society to seek out ever more detailed and fundamental processes to command. Controlled polymerization affords such a power; allowing for the design of meticulous and precisely defined systems granting detailed insight into structure-property relationships in the polymer materials and bettering understanding of novel physical phenomena.

This dissertation primarily focuses on development and preparation of well-defined hierarchically organized macromolecular systems. The novel chain-growth polymerization methodologies …

Formulation To Application: Thermomechanical Characterization Of Flexible Polyimides And The Improvement Of Their Properties Via Chain Interaction, Alejandro Rivera Nicholls

USF Tampa Graduate Theses and Dissertations

In this work, Polyimides were synthesized by incorporating an aromatic diamine monomer with a methylene linker, 4,4'-methylenebis(2,6-dimethylaniline) (MBDMA), to make a robust main chain along with aliphatic polyetherdiamine backbone linkers to reduce rigidity. The polymers were designed to exhibit thermal properties in between those of conventional aromatic polyimides and polymers with wholly aliphatic ether diamine links. Through dynamic mechanical analysis and differential scanning calorimetry, it is shown that control of the molar ratios of the aromatic MBDMA and the composition and size of the aliphatic polyetherdiamine can be used to tune the glass transition temperature. The materials were characterized and …

Thermo-Oxidative Degradation Of Hdpe Geomembranes: Effect Of Phenolic Antioxidant And Hindered Amine Light Stabilizer Concentrations, Yasin Kocak

USF Tampa Graduate Theses and Dissertations

High density polyethylene (HDPE) geomembrane is most common geomembrane which is mainly used for civil engineering applications. However, HDPE geomembrane loses its properties under oxidative degradation progress. This study aims to assess geomembranes which have different percentage of phenolic antioxidant and hindered amine light stabilizer (HALS) with under the six months of the thermal-oxidative degradation. The interactions between phenolic antioxidant, HALS and carbon black can affect the mechanical, physical and chemical properties. To monitor these properties, Differential Scanning Calorimetry (DSC), Fourier-transform Infrared Spectroscopy (FTIR), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy coupled with Energy Dispersive X-ray spectroscopy (SEM/EDX), Melt Index tests, …

Protein Detection And Structural Characterization By Mass Spectrometry Using Supramolecular Assemblies And Small Molecules, Bo Zhao

Doctoral Dissertations

Mass spectrometry (MS) has played an increasingly prominent role in proteomics and structure biology because it shows superior capabilities in identification, quantification and structural characterization of proteins. To realize its full potential in protein analysis, significant progress has been made in developing innovative techniques and reagents that can couple to MS detection. This dissertation demonstrates the use of polymeric supramolecular assemblies for enhanced protein detection in complex biological mixtures by MS. An amphiphilic random co-polymer scaffold is developed to form functional supramolecular assemblies for protein/ peptide enrichment. The influences of charge density and functional group pK_a on host-guest interactions …

Providing Molecular Insight For Understanding Anion Exchange Membrane Conductivity, Michael Kwasny

Doctoral Dissertations

Anion exchange membranes (AEMs) are notorious for having both low alkaline stability and poor ion conductivity in fuel cell operation conditions, with solutions to these two challenges often being developed independent of each other. The chemical instability of an AEM is viewed through degradation of the polymer backbone and the cationic species and improving a material’s stability is approached by altering the polymer backbone, the cation, or both. On the other hand, poor ion conductivity is typically addressed by modifying bulk membrane properties such as increasing the ion exchange capacity (IEC), changing the morphology, or increasing the water uptake. These …

Designing Ion-Containing Polymers With Controlled Structure And Dynamics, Joshua Enokida

Doctoral Dissertations

Ion-containing polymers are a unique class of materials for which strong electrostatic interactions dictate physical properties. By altering molecular parameters, such as the backbone chemical structure, the ion content, and the ion-pair identity, the structure and dynamics of these polymers can be altered. Further investigation of the molecular parameters that govern their structure-property relationships is critical for the future development of these polymeric materials. Particularly, the incorporation of ammonium-based counterions into these polymers offers a facile method to tune their electrostatic interactions and hydrophobicity. Applying this concept, a bulky dimethyloctylammonium (DMOA) counterion was used to modify the organic solubility of …

Progress Toward Durable Icephobic Materials, Matthew J. Coady

Electronic Thesis and Dissertation Repository

Ice accumulation is a major engineering challenge in many fields including aerospace, power generation, transportation, and infrastructure. A variety of solutions are being researched to address this challenge. Perhaps the most promising method of combating ice accumulation is by applying coatings with low values of interfacial ice adhesion strength, τ_ice. Icephobic materials are those with ice adhesion below 100 kPa, and it has been shown that passive delamination can occur on surfaces with τ_ice below 20 kPa. While various low adhesion surfaces have been prepared, durability concerns pervade applications where surfaces experience repeated icing or freeze-thaw cycles, …

Methodologies For Metal Functionalization Of Phosphorus Based Photopolymer Networks, Vanessa Béland

Electronic Thesis and Dissertation Repository

Photopolymer networks with phosphonium cation, alkyl phosphine and olefin functionality were designed, synthesized and functionalized with metals by metathesis, coordination and hydrometallation reactions, respectively. The materials were strategically designed so that the metal functionalization step could be monitored and quantified. In some cases, this involved characterization by IR, NMR, or X-ray spectroscopic techniques, or by comparison to molecular analogues. It was found that by using a bi-functional photopolymer network, the material could be bi-metallized by orthogonal mechanisms. All metallized polymer networks were tested for their suitability as precursors to metal-containing ceramics. The polymers were pyrolyzed, and on analysis it was …

Synthesis Of Crosslinkable Poly(Ester Amide)S For Cell Encapsulation And Delivery, Yu Ting (Natalie) Liang

Electronic Thesis and Dissertation Repository

Tissue engineering using adipose-derived stromal cells (ASCs) shows promise for soft tissue regeneration. Biodegradable polymers are potential biomaterials as they support the growth and delivery of cells. Specifically, poly(ester amide)s (PEAs) are a class of biodegradable polymers with tunable structures that have been shown to exhibit low cytotoxicity and support the growth of various cell types. This thesis involved the development of new water soluble amino acid-based PEAs with crosslinkable moieties to enable formation of hydrogel scaffolds for ASC encapsulation. These hydrophilic phenylalanine-based and alanine-based PEAs were synthesized by solution polycondensation and photo-crosslinked into a series of hydrogels with and …

Sequence-Defined Ionic Peptoid Block Copolymers: Synthesis And Solution Self-Assembly, Garrett Leigh Sternhagen

LSU Doctoral Dissertations

This work covers efforts to develop a peptoid-based model system for systematically studying the role of ionic functional groups in determining the structure of ionic block copolymer (BCP) self-assemblies in water. A key challenge in the study of polyelectrolytes is the lack of synthetic control over the location of ionic monomers along a polymer chain. We developed a model system based on sequence-defined ionic peptoid BCPs having discrete chain length and precisely positioned ionic monomers along the chain to specifically address this issue. In Chapter 1, synthetic strategies to access well-defined polypeptoids and their application in BCP synthesis are reviewed. …

Synthesis And Characterization Of Multifunctional Transition Metal Oxide Nanoparticles Through A Modified Sol-Gel Method With Application In Energy Storage, Julien Lombardi

Dissertations, Theses, and Capstone Projects

The Synthesis of transition metal oxide nanoparticles has been studied in great detail over the many years. The most studied transition metal oxide nanoparticles are perovskites of the ABO₃ stoichiometry (A and B = transition metal) and more recently double perovskite crystal structures of the AA’BO₆ or A₂BB’O₆ stoichiometry due to the many different properties arising from the many different combinations of elements possible. These materials have proven potentially useful in many fields, but due to properties such as ferroelectricity and ferromagnetism, the desire to integrate these materials into electronics is ever growing. Many synthesis …

Self-Assembly Of Conducting Polymer Nano- And Microstructures For Energy Storage, Luciano Matteo Santino

Arts & Sciences Electronic Theses and Dissertations

Plastics are materials composed of many long chains of molecules with repeating subunits; strong interactions between neighboring molecules lead to the material used throughout the world. Plastics are commonly thought to be insulating, in stark contrast to the conductivity of metals. However, certain polymer structures were discovered to exhibit semiconducting properties, the subject of the Nobel Prize in Chemistry in 2000. Conducting polymers have a unique molecular structure with an electronically conjugated backbone, allowing electrons to freely travel both across the chain and in between chains. This work focuses on controlling the kinetics of the reaction between the vapors of …

Organic-Inorganic Hybrid Composites: Superhydrophobic Polymer Coatings With Photoreactive Perfluorinated Phthalocyanines, Abdul Azeez

Seton Hall University Dissertations and Theses (ETDs)

ABSTRACT

We report partly fluorinated and silicon-based polymers that incorporate inorganic/organic materials capable of generating reactive oxygen species (ROS) using only visible light and air. Polyvinylidene fluoride (PVDF), which incorporated a known perfluorinated phthalocyanine photosensitizer, F₆₄PcZn, supported on silicon and titanium oxides was further modified via chemical surface roughening to exhibit enhanced hydrophobicity when used as a coating. Water contact angles as high as ~159° have been observed, vs. ~ 92° for the unmodified polymer. The polymer matrix, however, does not resist the ROS it produces as evidenced by spectroscopic and SEM data. A polysiloxane matrix was similarly …

A Study In Molecular Recognition: Synthesis Of A Β-Sheet Mimic & Quantitation Of Metal Ions In Aqueous Solutions Through Solid Supported Semi-Selective Chemosensors, Tyler G. Fenske

Theses and Dissertations

From the hydrophobic effect, which is responsible for the organization of amphipathic molecules into cellular membranes, to the highly specific hydrogen binding patterns found in DNA base pairs that keeps our genetic material “zipped up”, non-covalent and reversible interactions are critical to properly functioning biological processes. Molecular recognition is an area of study that seeks to better understand these observed phenomena. In a general sense, association of “Host” and “Guest” molecules are based on ionic forces, hydrophobic interactions, cation-π effects, π-π stacking, conformational restriction, and many others. This dissertation will primarily focus on two projects that have an emphasis on …

Modification And Optimization Of Conducting Polymer-Modified, Redox-Magnetohydrodynamics (R-Mhd) Pumping For Enhanced And Sustained Microfluidics Applications, Md Foysal Zahid Khan

Graduate Theses and Dissertations

In this work, a novel microfluidic pumping approach, redox-magnetohydrodynamics (R-MHD) has improved by materials and device optimization to use in lab-on-a-chip applications. In R-MHD, magnetic flux (B) and ionic current density (j) interacts to generate body force (FB) in between active electrodes, according to the equation FB = j×B. This unique fluid pumping approach is scalable, tunable, generates flat flow profile, and does not require any channels or valves. Pumping performance, such as speed scales with the ionic current density (j) and duration depends on the total charge (Q). The ionic current density (j) results from the conversion of electronic …

Synthesis Of New Aliphatic Pseudo-Branched Polyester Co-Polymers For Biomedical Applications, Zachary Shaw

Electronic Theses & Dissertations

In this study, a hyperbranched polyester co-polymer was designed using a proprietary monomer and diethylene glycol or triethylene glycol as monomers. The synthesis was carried out using standard melt polymerization technique and catalyzed by p-Tolulenesulfonic acid. The progress of the reaction was monitored with respect to time and negative pressure, with samples being subjected to standard characterization protocols. The resulting polymers were purified using the solvent precipitation method and characterized using various chromatographic and spectroscopic methods including GPC, MALDI-TOF, and NMR. We have observed polymers with a molecular weight of 29,643 kDa and 33,996 kDa, which is ideal to be …

Double-Network Materials Via Frontal Polymerization & Supercritical Co2 Processing, Matthew Joseph Lampe

Doctoral Dissertations

This dissertation presents work focused on producing materials in non-equilibrium states by taking advantage of novel processing techniques. First, epoxy-based resins which can undergo radically promoted, cationic, thermal, frontal polymerization are investigated for their potential use as adhesives. These resins are found to be capable of sustaining propagating polymerization fronts between several different substrate materials, resulting in high levels of adhesion in some cases. In addition, a similar frontal resin was developed that can undergo sequential gelation and frontal polymerization. The gels are formed by radically crosslinking acrylate monomers within the epoxy resin. These gels can then be manipulated, and …

Reactive And Stimuli-Responsive Sulfonium-Based Polymer Zwitterions, Cristiam Santa Chalarca

Doctoral Dissertations

This dissertation describes the synthesis and characterization of novel monomers and (co)polymer zwitterions that incorporate trialkylsulfonium cations. The novel materials presented herein constitute a unique type of polymer zwitterions that exhibit salt- and temperature-dependent water solubility as well as inherent reactivity. The behavior of these polymers in aqueous solutions, as nanostructures, and at liquid-liquid interfaces was studied; in all cases, the inherent reactivity of the polymers was harnessed towards the fabrication of novel polymers and soft materials. Following an introductory chapter, Chapter 2 describes the synthesis of sulfonium sulfonate monomers and polymer zwitterions. Both styrenic and methacrylic monomers were synthesized …

Design, Synthesis And Study Of Functional Amphiphilic Polymers And Their Applications, Huan He

Doctoral Dissertations

Amphiphilic homopolymers with high densities of functional groups are synthetically challenging. Thiol-yne nucleophilic click reactions have been investigated to introduce multiple functional groups in polymers with high density. An electron deficient alkyne group bearing methacrylate monomer was polymerized using reversible addition−fragmentation chain-transfer (RAFT) polymerization. Subsequently, the electron deficient alkyne group on polymer side chain was readily reacted with a thiol reagent using triethylamine (TEA) as the organocatalyst. This reaction was found to be very efficient under mild conditions. The resultant homopolymer bearing thiol vinyl ether functional groups could perform a second thiol addition with a stronger base, such as triazabicyclodecene(TBD), …

Modification Of 2d Materials Utilizing Functional Polymer Interfacial Layers, Ryan Selhorst

Doctoral Dissertations

This dissertation describes the modification of 2D transition metal dichalcogenides (TMDCs). These materials exhibit unique electronic properties, ranging from metallic to insulating, and can transport either electrons (n-type) or holes (p-type). Polymers containing electronically-active moieties offer a path to control the electronic properties of a 2D material without altering the inherent structure of the semiconductor. This dissertation focuses on the synthesis of polymers bearing chalcogen-rich or zwitterionic moieties to alter the electronic and solution properties of 2D materials. Chapter 2 describes polymers containing sulfur-rich tetrathiafulvalene (TTF) and their effects as electroactive coatings on the TMDC molybdenum disulfide (MoS₂). …

Implementation Of Multivariate Artificial Neural Networks Coupled With Genetic Algorithms For The Multi-Objective Property Prediction And Optimization Of Emulsion Polymers, David Chisholm

Master's Theses

Machine learning has been gaining popularity over the past few decades as computers have become more advanced. On a fundamental level, machine learning consists of the use of computerized statistical methods to analyze data and discover trends that may not have been obvious or otherwise observable previously. These trends can then be used to make predictions on new data and explore entirely new design spaces. Methods vary from simple linear regression to highly complex neural networks, but the end goal is similar. The application of these methods to material property prediction and new material discovery has been of high interest …