Physical Sciences and Mathematics Commons^™

Vibrational Imaging At The Nanoscale: Surpassing The Diffraction Limit Using Tip-Enhanced Raman Spectroscopy, Farshid Pashaee

Electronic Thesis and Dissertation Repository

A deep understanding of the chemical composition of surfaces, interfaces or nanoscale structure with a high spatial resolution is an important goal in nanoscience and nanotechnology. Structural information can be collected using a variety of high spatial resolution techniques such as atomic force microscopy (AFM), scanning tunneling microscopy (STM), scanning electron microscopy (SEM), or transmission electron microscopy (TEM). Nevertheless, these methods do not offer molecular information such as vibrational spectroscopy techniques that allow one to collect molecular or lattice vibrations yielding to a precise picture of the molecular interactions in bulk materials as well as in surfaces and interfaces. Unfortunately …

Solvothermal Synthesis And Characterization Of Cuins2, Cuinse2 And Agins2 Nanoparticles From Single Source Precursors, Xuzhao Zhao

Electronic Thesis and Dissertation Repository

Nanoscale semiconductors have emerged as alternative candidates for the absorber layer in solar cells. Group 11-13-16 semiconductors have received a lot attention because of their direct band gap energies, high absorption coefficients and environmental friendly nature. To date, CuInS₂, CuInSe₂ and AgInS₂ semiconductors are three of the main ternary nanomaterials investigated. Besides the application in solar cells, these nanoscale semiconductors can also be applied in areas such as biosensors and hydro catalysis.

However, it is often challenging to prepare small-sized nanoparticles with uniform size and shape, especially for large scale production. In this thesis, the synthesis …

The Influence Of Alloying Elements On The Crevice Corrosion Behaviour Of Ni-Cr-Mo Alloys, Nafiseh Ebrahimi

Electronic Thesis and Dissertation Repository

To enhance its corrosion resistance in aggressive media, Ni is alloyed with various amounts of Cr and Mo along with small amounts of other alloying elements such as W, Cu, and Fe. While the resulting alloys (known as Ni superalloys) show excellent passive behaviour, the function of individual alloying elements in resisting localized corrosion processes, in particular crevice corrosion is not fully understood. This study focuses on the electrochemistry and corrosion of a series of Ni-Cr-Mo (W) alloys with various Cr and Mo contents. Several electrochemical and surface characterization techniques were used to investigate the role of major alloying elements …

The Corrosion Behaviour Of Cu In Irradiated And Non-Irradiated Humid Air, Balsam Ibrahim

Electronic Thesis and Dissertation Repository

The present management scenario for the permanent disposal of high level nuclear waste in Canada is to seal it in metallic containers and bury it in a deep stable geologic repository. For thick-walled containers radiation fields on the outside of the container would have a negligible influence on container corrosion. However, to overcome fabrication issues and to reduce costs, steel containers with a thin outer copper coating are being designed making a reassessment of the influence of gamma radiation on container corrosion a potential licensing requirement.

The behaviour of Cu in an aerated vapour phase environment in equilibrium with condensed …

Dynamic Studies Of Guest Molecules In Metal-Organic Frameworks Using Solid-State Nmr, Yuanjun Lu

Electronic Thesis and Dissertation Repository

Metal-organic frameworks (MOFs) are a new class of porous materials that possess large three-dimensional voids in their structures. In this work, Solid-state NMR (SSNMR) is used to examine the dynamics of guest molecules at various temperatures in MOFs that possess different types of channels. Chapter 2 introduces the ¹³CO₂ adsorption behavior in α-Mg formate studied by ¹³C SSNMR in conjunction with molecular dynamic simulation. ¹H-¹³C cross polarization technique has successfully determined the adsorption sites of CO₂ in this type of MOF to be hydrogen atoms. The dynamic analysis detects that at low temperature, …

Design And Fabrication Of Integrated Plasmonic Platforms For Ultra-Sensitive Molecular And Biomolecular Detections, Mohammadali Tabatabaei

Electronic Thesis and Dissertation Repository

One of the major challenges in analytical and biological sciences is to develop a device to obtain unambiguous chemical and structural properties of a material or a probe biomolecule with high reproducibility and ultra-high sensitivity. Moreover, in addition to such a high sensitivity, other cases such as minimum intrusiveness, small amounts of analyte, and short acquisition time and high reproducibility are key parameters that can be valued in any analytical measurements. Among the promising methods to achieve such endeavor, plasmon-mediated surface-enhanced spectroscopic techniques, such as surface-enhanced Raman spectroscopy (SERS), are considered as suitable options. Such techniques take advantage of the …

X-Ray Absorption Fine Structure Studies Of Calcium Silicate Hydrate Biomaterials In Drug Delivery, Xiaoxuan Guo

Electronic Thesis and Dissertation Repository

Calcium silicate hydrate (CSH), a new type of bioceramics, has gained significant attention in hard tissue restoration because of their impressive role in the stimulation of osteoblast proliferation and differentiation in vitro. The further development of mesoporous bioceramics opens up new opportunities for drug delivery in hard tissue therapies. In this thesis, interaction mechanisms of drug molecules with CSH of different morphologies and CSH/polymer composites, imaging of drug distributions in CSH carriers in nanoscale, and the biomineralization mechanisms of CSH in vitro during drug release are extensively investigated using X-ray absorption near edge structure (XANES) and scanning transmission X-ray …

In Situ High-Pressure Study Of Metal-Organic Frameworks And Their Performance For Co2 Storage Probed By Vibrational Spectroscopy, Yue Hu

Electronic Thesis and Dissertation Repository

Metal-organic frameworks (MOFs) are an important class of porous materials, owing to their potential applications in a variety of areas, including gas storage, molecular separations, catalysis, sensors and so on. Most importantly, their extraordinary surface areas, tunable pore properties and potential for industrial scale production have made MOFs a promising material for clean energy applications, such as CO₂ storage. The chemical and mechanical stabilities of MOFs play a crucial role in their CO₂ storage performance, which require extreme loading pressures that are far beyond ambient pressure at times. Application of high external pressure (e.g., in gigapascal range) on …

Self-Assembly And Stimuli-Responsive Properties Of Amphiphilic Self-Immolative Block Co-Polymers, Thomas Mackenzie Gungor

Electronic Thesis and Dissertation Repository

In recent years, degradable polymers have become increasingly researched for their applications in drug delivery systems, adhesives, and tissue engineering. Self-immolative polymers (SIPs) are of particular utility due to predictable end-to-end backbone depolymerization after a stimuli-responsive end-cap cleavage. There are examples of incorporating a hydrophobic SIP into an amphiphilic block-copolymer, followed by self-assembly in aqueous media forming various nanoparticle morphologies. However, their self-assembly behaviour has not been described in detail, and there are no general synthetic methods that allow for their synthesis with good control over the relative hydrophilic block ratio, the major factor controlling their morphology. This thesis presents …

Stimuli-Responsive Polymersomes And Surface Functionalized Dendrimersomes: Platforms For Biomedical Applications, J Trevor Mcintosh

Electronic Thesis and Dissertation Repository

Amphiphilic block copolymers (BCPs) and dendrimers are known to self-assemble in aqueous solution to form a number of aggregate morphologies. These different architectures are largely a function of the hydrophilic volume or weight fractions of the different components of the polymer system. One possible morphology is a vesicle, also referred to as a polymersome or dendrimersome when BCPs or dendrimers, respectively, are used. Vesicles are multi-functional, supramolecular, bilayer assemblies, whose potential for stimuli-responsiveness and surface functionalization make them promising materials for a variety of biomedical applications. This thesis demonstrates the use of UV-sensitive block copolymers forming photodegradable vesicles, as well …

Strategies For Photochemical And Thermal Modification Of Materials, Sara Ghiassian

Electronic Thesis and Dissertation Repository

The modification of materials/surfaces is central to numerous applications ranging from opto-electronic devices to biomedical implants and drug delivery. Thus, there exists a high motivation for improving the methodologies which can be employed in order to modify surfaces in a selective and efficient fashion. One of the major goals of surface engineering is to control the chemical composition at the material interface. The fine control of the surface properties is a field of intense research as the performance of functional materials is strongly related to the processes and interactions that are occurring at the materials’ interface.

In general, the modification …

Exploring The Chemistry Of Phosphorus For Photopolymer Applications, Ryan Guterman

Electronic Thesis and Dissertation Repository

Prior to this thesis, phosphorus-containing polymers and photopolymerization represented two distinct, non-overlapping fields of study. This thesis examined the prospect of combining these two approaches to create a system possessing the benefits of both techniques. By exploiting the chemistry of phosphorus, and using photopolymerization as a fabrication method, new materials were developed and assessed for their use in various applications.

Among the many phosphorus compounds that may be used in polymer science, phosphonium salts and primary phosphines were of specific focus. First, highly fluorinated phosphonium monomers were developed to create photopolymerized hydrophobic surfaces. A structure-activity relationship was established, as both …

Exploring The Chemistry Of Η5-Cyclopentadienyl-Cobalt-Η4-Cyclobutadiene Containing Polymers; Synthesis, Properties, And Self-Assembly, Mahboubeh Hadadpour

Electronic Thesis and Dissertation Repository

Metal containing polymers (metallopolymers) bring together the synthetic efficiency and versatility of conventional organic polymers with unique redox, responsive, and catalytic properties of inorganic metals. Over the last decade, metallopolymers have gained increased attention because of their unique physical and chemical properties that arise from the incorporation of metal centers into a polymer. Since the first report on a metallocene-based metallopolymer in 1955, there has been growing interest in this class of material. Ferrocene-based metallopolymers represent the vast majority of metallocene containing polymers in the literature. In 1992, the Manners Group established a major milestone in the field of metallopolymers …

Design, Synthesis, And Reactivity Of Bimetallic Complexes Of Dimethylplatinum(Ii) Containing Ditopic Ligands, Matthew S. Mccready

Electronic Thesis and Dissertation Repository

This thesis describes a study of monometallic and bimetallic dimethylplatinum(II) complexes containing ditopic nitrogen donor ligands. This work details the design and synthesis of side-to-side and cofacial arranged ligands and their respective coordination chemistry. The study of the synthesis, characterization and reaction mechanisms of the various dimethylplatinum(II) complexes is outlined in detail with special emphasis focused on the reactivity of the complexes towards oxidative addition.

The ditopic ligand 6-dppd, 1,4-di(2-pyridyl)-5,6,7,8,9,10-hexahydrocycloocta[d]pyridazine, was observed to coordinate only a single equivalent of a platinum(II) center. The inability to coordinate a second equivalent, even through an assisted bridging atom, is presumed to be due …

Gamma-Radiation Induced Redox Reactions And Colloidal Formation Of Chromium And Cobalt Oxide Nanoparticles, Leena M. Alrehaily

Electronic Thesis and Dissertation Repository

The main goal of this thesis research is to develop a mechanistic understanding of radiation-induced chromium oxide and cobalt oxide nanoparticle formation in aqueous solutions containing initially dissolved metal ions. When exposed to ionizing radiation, water decomposes to form a range of chemically reactive radical and molecular products. This redox agents can readily change the oxidation state of dissolved metal ions. The solubility of a transition metal ion can vary by several orders of magnitude depending on its oxidation state and the solution pH. Thus, reactions that can alter the oxidation state of a dissolved ion can lead to the …