Theoretical And Experimental Investigation Of Matrix Inclusions On The Fracture Toughness Of Composite Material, 2017 University of Colorado at Boulder
Theoretical And Experimental Investigation Of Matrix Inclusions On The Fracture Toughness Of Composite Material, Shahlaa Al Wakeel
Civil Engineering Graduate Theses & Dissertations
This dissertation studies the impact of microstructure on macro-scale fracture parameters. Experimental and theoretical investigations of fracture toughness are carried out on a representative particulate composite material and reconciled by explicitly considering inclusions within the matrix. The reliability of any structure is a function of its resistance to fracture. Cracks resulting from stress concentrations are the major sources of fracture whether the material is classified as ductile, brittle, or quasi-brittle. The spatial distribution of inclusions in particulate composite materials, such as concrete and other heterogeneous materials, plays an important role in determining material fracture behavior due to the localized stress ...
Synthesis And Development Of Zwitterionic Pei (Zpei) For Optimized Delivery Of Nucleic Acids, 2017 University of Kentucky
Synthesis And Development Of Zwitterionic Pei (Zpei) For Optimized Delivery Of Nucleic Acids, Joseph Raleigh Duke Iii
Theses and Dissertations--Chemistry
Gene therapy holds promise for the treatment a wide range of diseases ranging from cystic fibrosis to cardiovascular disease to cancer. The need for safe and efficient gene delivery methods remains the primary barrier to human gene therapy. Non-viral vector materials, including polymers, can be designed to be biocompatible and non-immunogenic, but lack the efficiency to be clinically relevant. Gene therapy awaits the development of new materials that are both safe and efficient. Here, we have synthesized a series of modified zwitterionic polymers based on the common transfecting agent polyethylenimine (PEI). Using a variety of biochemical and biophysical methods we ...
Structure-Property Relationship Study Of Polyimine-Based Dynamic Covalent Networks And Their Applications Towards Functional Composites, 2017 University of Colorado at Boulder
Structure-Property Relationship Study Of Polyimine-Based Dynamic Covalent Networks And Their Applications Towards Functional Composites, Chengpu Zhu
Chemistry & Biochemistry Graduate Theses & Dissertations (1986-2018)
This thesis aimed to address fundamental study and related applications of covalent adaptable networks (CANs), focusing on polyimine materials. Crosslinked polyimine represents a novel class of covalent adaptable network, which exhibits room temperature repairability, catalyst-free malleability, recyclability, and robust mechanical properties. Polyimine network prepared from commercially available monomers (terephthaldehyde, diamine and triaminotriethylamine) have been investigated including solvent and concentration effect on their physical properties. Monomer concentration and solvent properties directly control reaction rates and influence solvent diffusion into polymer chains and interfacial interactions during the polymerization progress, a range of mechanical properties can be obtained in different solvents from the ...
Influence Of Biomimetic Chelating Packaging On Natural Antimicrobial Efficacy, 2017 University of Massachusetts Amherst
Influence Of Biomimetic Chelating Packaging On Natural Antimicrobial Efficacy, Paul Castrale
The iron chelating molecule, ethylenediaminetetraacetic acid (EDTA) is used in food applications for the preservation of oxidation prone ingredients. Research has suggested that EDTA is also capable of enhancing the antimicrobial effectiveness of various compounds including naturally-derived antimicrobials. With consumer demand for cleaner food labels, there remains an opportunity to introduce new chelating technology to replace synthetically-derived EDTA. Through photographting and chemical conversion, hydroxamic acid ligands were covalently bound to polypropylene films resulting in polypropylene-graft-poly(hydroxamic acid) (PP-g-PHA). The resulting films demonstrated an ability to chelate 64 nmol/cm2 from an iron saturated environment or ...
Nitric Oxide Release From Poly(Lactic-Co-Glycolic Acid) Nanoparticles And Titanium Alloy, 2017 Duquesne University
Nitric Oxide Release From Poly(Lactic-Co-Glycolic Acid) Nanoparticles And Titanium Alloy, Nina A. Reger
Electronic Theses and Dissertations
Current methods for the treatment of bacterial infection involve the use of systemic antibiotics, which are high concentrations of antibiotics delivered over a long period time. Unfortunately, the use of systemic antibiotics can cause harmful side effects to the patient and increases the possibility for antibiotic resistance. The delivery of antibiotics or alternative antimicrobial compounds, such as nitric oxide, directly to the site of infection would decrease the amount of antibiotic necessary to treat a bacterial infection.
Poly (lactic-co-glycolic acid)/polyvinyl alcohol nanoparticles and a titanium- aluminum-vanadium metal oxide alloy implant were surface functionalized to deliver nitric oxide. Polymer nanoparticles ...
Molecular Design, Characterization, And Implementation Of Organic Semiconducting Oligothiophenes, 2017 University of Massachusetts Amherst
Molecular Design, Characterization, And Implementation Of Organic Semiconducting Oligothiophenes, Benjamin Cherniawski
This work describes new self-assembly strategies and realizes new directions for rational side chain design in organic semiconductors. I examined the synthesis and structure property relations of monomers and dimers of a benchmark organic semiconductor system using a variety of linear alkyl side chains. I observed critical onsets for packing trends based on alkyl side chain length in both monomers and dimers. Monomer systems exhibited a pronounced even-odd effect manifesting directly from side chain length. In the dimer systems, I observed spontaneous bimolecular crystal formation with PC61BM which undergoes an order-to-disorder transition at small side chain lengths. Combining ...
Synthesis And Characterization Of Imidazole-Containing Conjugated Polymers, 2017 University of Massachusetts Amherst
Synthesis And Characterization Of Imidazole-Containing Conjugated Polymers, Jared D. Harris
Semiconducting conjugated polymers hold tremendous promise as active layers for transformative electronic devices. This materials class benefits from the structural variety provided by organic chemistry such that highly tunable band structures are attainable for as-synthesized polymers. This dissertation describes the synthesis and characterization of novel imidazole-containing conjugated polymers for the purposes of (de)protonating the as-synthesized materials gaining conjugated poly(ionomer)s. (De)protonation easily enables band structure modification through manipulation of the materials’ ionization potential and electron affinity. Controlled exposure to acids and bases led to reversible (de)protonation observable via UV-visible and photoluminescence spectroscopies. (De)protonation’s effects ...
Polyorganosiloxanes: Molecular Nanoparticles, Nanocomposites And Interfaces, 2017 University of Massachusetts Amherst
Polyorganosiloxanes: Molecular Nanoparticles, Nanocomposites And Interfaces, Daniel H. Flagg
Five research projects described. First, a reproducible, lab-scale synthesis of MQ silicone copolymers is presented. MQ copolymers are commercially important materials that have been ignored by the academic community. One possible reason for this is the difficulty of controlling and reproducing the preparative copolymerizations that have been reported. A reproducible method for lab-scale preparation was developed that controls molecular weight by splitting the copolymerization into the discrete steps of sol growth from silicate precursor and end-capping by trimethylsiloxy groups. Characterization of MQ products implicates that they are composed of highly condensed, polycyclic structures.
The MQ copolymers prepared in the first ...
Thiol-Ene Chemistry As An Enabler Of New Polymer Structures And Architectures, 2017 University of Massachusetts - Amherst
Thiol-Ene Chemistry As An Enabler Of New Polymer Structures And Architectures, Joel M. Sarapas
This dissertation focuses on two distinct projects: the synthesis and design of novel cell penetrating peptides mimics (CPPMs), and the implementation of the thiol-ene click reaction to generate new polymer architectures and chemistries. Guanidinium-rich CPPMs were generated through both ROMP and RAFT polymerizations, allowing for a comparison to be made across polymer backbone chemistries with respect to both siRNA and protein cellular internalization. A particularly effective methacrylate derived block copolymer was able to deliver siRNA to nearly an entire Jurkat T cell population.
The thiol-ene reaction was implemented initially within the context of improving material design for solid polymer electrolytes ...
Synthesis Of Multifunctional Polyacrylates And A Binding Group To Hemoglobin For The Treatment Of Traumatic Brain Injuries, 2017 Georgia Southern University
Synthesis Of Multifunctional Polyacrylates And A Binding Group To Hemoglobin For The Treatment Of Traumatic Brain Injuries, Marina Michaud
University Honors Program Theses
Hemoglobin based oxygen carriers (HBOCs) hold promise as an effective emergency treatment of severe traumatic brain injuries (TBI). In the latest generation of HBOCs, polynitroxyl-pegylated hemoglobin (PNPH), cell-free hemoglobin is modified with TEMPO and PEG which reduce the toxicities associated with earlier generations of HBOCs. In our efforts to optimize the economic and therapeutic impacts of PNPH’s we have synthesized polydimethylaminoethyl methacrylate (poly-DMAEMA) under controlled living conditions via reverse addition-fragmentation chain transfer (RAFT) polymerization. The poly-DMAEMA was then successfully functionalized via quaternization of its NMe2 groups using chloroacetate derivatives of the TEMPO and PEG. This process was quantitative ...
Tailoring Nanoscale Morphology Of Polymer: Fullerene Blends Using Electrostatic Field, 2017 Mansoura University
Tailoring Nanoscale Morphology Of Polymer: Fullerene Blends Using Electrostatic Field, Moneim Elshobaki, Ryan S. Gebhardt, John Carr, William Lindemann, Wenjie Wang, Eric Grieser, Swaminathan Venkatesan, Evan Ngo, Ujjal Bhattacharjee, Joseph Strzalka, Zhang Jiang, Qiquan Qiao, Jacob W. Petrich, David Vaknin, Sumit Chaudhary
To tailor the nanomorphology in polymer/fullerene blends, we study the effect of electrostatic field (E-field) on the solidification of poly(3-hexylthiophene-2, 5-diyl) (P3HT):[6,6]-phenyl-C61-butyric acid methyl ester (PC60BM) bulk heterojunction (BHJ). In addition to control; wet P3HT:PC60BM thin films were exposed to E-field of Van de Graaff (VDG) generator at three different directions—horizontal (H), tilted (T), and vertical (V)—relative to the plane of the substrate. Surface and bulk characterizations of the field-treated BHJs affirmed that fullerene molecules can easily penetrate the spaghetti-like P3HT and move up and down following the E-field. Using E-field treatment ...
Asymmetric Membranes For High Capacity Lithium-Ion Battery Electrodes, 2017 Georgia Southern University
Asymmetric Membranes For High Capacity Lithium-Ion Battery Electrodes, Ian Byrd
Electronic Theses and Dissertations
Lithium-Ion Batteries (LIBs) have broad applications such as portable electronic devices, electric vehicles, and for green energy storage from intermittent sources. Current LIBs are limited by their low capacity materials at both the anode and cathode. At the anode, graphite suffers from a low capacity of only 372 mAh g-1. The most commonly used cathode material is LiCoO2 which has a meager capacity of 140 mAh g-1. Thereby the broader applications of LIBs are limited due to these low capacities. It is imperative to develop higher capacity materials to further improve the performance of LIBs. Silicon is ...
Α-Eleostearic Acid Extraction By Saponification Of Tung Oil And Its Subsequent Polymerization, 2017 Georgia Southern University
Α-Eleostearic Acid Extraction By Saponification Of Tung Oil And Its Subsequent Polymerization, Amanda Murawski
Electronic Theses and Dissertations
The goal of environmentally sound research is to provide alternatives that are more sustainable and renewable, such as vegetable oil-based polymers, than the current petroleum-based products. Vegetable oil-based polymers have received a lot of attention recently due their multifaceted properties, which are simply achieved by adjusting the monomer or resin composition. The carbon-carbon double bonds in unsaturated oils are ideal reactive sites for the free radical or cationic polymerizations. Most vegetable oils must be modified before polymerization due to the low reactivity of their non-conjugated fatty acid chains. Tung oil (TO) contains ~83% of a triply conjugated fatty acid (α ...
Scanning Angle Raman Spectroscopy: A Nondestructive Method For Simultaneously Determining Mixed Polymer Fractional Composition And Film Thickness, 2016 Iowa State University and Ames Laboratory
Scanning Angle Raman Spectroscopy: A Nondestructive Method For Simultaneously Determining Mixed Polymer Fractional Composition And Film Thickness, Jonathan M. Bobbitt, Deyny Mendivelso-Perez, Emily A. Smith
A scanning angle (SA) Raman spectroscopy method was developed to simultaneously measure the chemical composition and thickness of waveguide mixed polymer films with varying fractional compositions. In order to test the method, six films of polystyrene-block-poly(methyl methacrylate), some mixed with poly(methyl methacrylate) homopolymer (PS-b-PMMA:PMMA), and two films of poly(2-vinylnapthalene)-block-poly(methyl methacrylate) (P2VN-b-PMMA) were prepared. The film thickness ranged from 495 to 971 nm. The chemical composition and thickness of PS-b-PMMA:PMMA films was varied by the addition of the PMMA homopolymer and annealing the films in acetone. SA Raman peak amplitude ratios (1001 cm−1 ...
Poly(Styrene)-B-Poly(Dimethylsiloxane)-B- Poly(Styrene)/Single Walled Carbon Nanotube Nanocomposites. Synthesis Of Triblock Copolymer And Nanocomposite Preparation, Ian Stubbs
Electronic Theses & Dissertations Collection for Atlanta University & Clark Atlanta University
Molecular weights of 2,000, 6,000 and 10,000 of silane functionalized atactic polystyrene (aPS) and α,ω-divinyl functionalized polydimethylsiloxane (PDMS) were prepared via living anionic polymerization and bulk anionic ring opening polymerization respectively. Functionalization of the homopolymers was confirmed by FT-IR and 1H-NMR spectroscopy and their molecular weights were determined via 1H-NMR end group analysis. A hydrosilylation reaction between the functionalized homopolymers of different molecular weights produced nine polystyrene-block-polydimethylsiloxane-block-polystyrene (aPS-b-PDMS-b-aPS) triblock copolymers. Field emission scanning electron microscopy observations revealed the copolymers self-assemble into supramolecular structures. Dynamic Light Scattering ...
End-Capping Strategies For Triggering End-To-End Depolymerization Of Polyglyoxylates, 2016 Western University
End-Capping Strategies For Triggering End-To-End Depolymerization Of Polyglyoxylates, Bo Fan, John Trant, Elizabeth Gillies
Polymers that undergo end-to-end depolymerization in response to the cleavage of a stimuli-responsive end-cap are promising for diverse applications from drug delivery to responsive coatings and plastics. It is critical that the end-cap is designed to respond to an appropriate stimulus for the application. In the current work, end-caps for triggering the depolymerization of poly(ethyl glyoxylate) (PEtG) were explored. First, a phenylboronate, a disulfi de, and an azobenzene were utilized to impart redox-responsive properties to PEtG. Then, methoxy-substituted trityl groups were used to provide sensitivity to mild acid. A multiresponsive platform was also introduced, allowing PEtG to respond to ...
Synthesis Of Metal-Containing Phosphines And Their Use In Coordination, Polymer, And Materials Chemistry, 2016 The University of Western Ontario
Synthesis Of Metal-Containing Phosphines And Their Use In Coordination, Polymer, And Materials Chemistry, Amir Rabiee Kenaree
Electronic Thesis and Dissertation Repository
This thesis describes the investigation of a novel strategy for the synthesis of metal-containing small molecules, polymers, and nanomaterials. In this context, a new family of air-stable, homo- and heterometallic primary, secondary, and tertiary phosphines were prepared via the radical-initiated hydrophosphination reaction of PH3 with vinylferrocene and/or vinylruthenocene. The full characterization of the phosphines confirmed their targeted structures and proved that the properties of the starting metallocenes are reflected in those of the resulting phosphines.
To study the coordination behavior of this family of phosphines, primary, secondary, and tertiary ethylferrocene phosphines were reacted with Group 6 metal carbonyl ...
Creating Functional Materials With Phosphorus, 2016 The University of Western Ontario
Creating Functional Materials With Phosphorus, Tyler John Cuthbert
Electronic Thesis and Dissertation Repository
Understanding the relationship between small molecules or polymers and how they affect the properties of materials they compose is the basis of materials science. Using unique and versatile components can impart useful and interesting properties to materials. Here, we aimed to extend this understanding to phosphorus, and the known properties it possesses. This included the production of photopolymerizable coatings containing phosphonium molecules and polymers for antifouling and antibacterial applications. The synthesis and characterization of these phosphonium components was completed and materials were produced utilizing UV curing technology. Addition of these components produced coatings that could resist bacteria attachment and efficiently ...
Synthesis Of Metal-Containing Polymers And Stable Organic Radical-Containing Polymers And Their Use As Advanced Functional Materials, 2016 The University of Western Ontario
Synthesis Of Metal-Containing Polymers And Stable Organic Radical-Containing Polymers And Their Use As Advanced Functional Materials, Joseph A. Paquette
Electronic Thesis and Dissertation Repository
The work presented in this thesis details the synthesis and characterization of two different families of multifunctional polymers. The first family involved the incorporation of stable 6-oxoverdazyl radicals into polymer scaffolds. This was originally achieved by the polymerization of the radical precursors, phenyl- and isopropyl-6-oxotetrazanes, followed by post-polymerization oxidation to afford the phenyl- and isopropyl-6-oxoverdazyl polymers. A second methodology involved the direct polymerization of isopropyl-6-oxoverdazyl radicals using ring-opening metathesis polymerization (ROMP) to afford polymers with controlled molecular weights and narrow molecular weight distributions. The polymers were characterized by the close comparison of the physical and spectroscopic properties ...
Synthesis And Behavior Of Stimuli-Responsive Shape-Changing Linear Molecular Bottlebrushes, 2016 University of Tennessee, Knoxville
Synthesis And Behavior Of Stimuli-Responsive Shape-Changing Linear Molecular Bottlebrushes, Daniel Mark Henn
Molecular bottlebrushes are composed of polymer side chains densely grafted to a macromolecular backbone. The main focus of this dissertation work is the synthesis and behavior of linear molecular brushes that can undergo unimolecular size and shape changes in response to environmental stimuli in dilute aqueous solution. Chapter 1 provides an introduction to molecular bottlebrushes and stimuli-responsive polymers.
Chapter 2 presents the development of a robust method for the synthesis of well-defined molecular brushes by a “grafting to” approach using copper-catalyzed azide-alkyne cycloaddition “click” reactions. Well-defined, new azide-containing backbone polymers with different lengths and high degrees of azide functionality were ...