Materials Chemistry Commons^™

Halide Exchange And Transport In Halide Perovskite Lattices, Temban Acha Billy

Department of Chemistry: Dissertations, Theses, and Student Research

In recent years, metal-halide perovskites (MHPs) have risen quickly to prominence as promising materials across a variety of fields, from photovoltaics to optoelectronics in general. We show here a facile solution growth for creating a variety of mixed halide MAPbBr_3-xI_x crystals, which we will use to study halide exchange and transport in halide perovskites. We generated a calibration curve between the optical response and chemical composition in mixed Br/I MHPs at room temperature. All mixed Br/I MHP crystals were subjected to measurements of photoluminescence (PL) and Raman spectroscopy. A subset of mixed-halide MHP crystals exhibited multiple emission …

Harnessing Surface Chemistry And Instabilities In Silicone Elastomers To Synthesize Adaptive Systems With Mechanically Tunable Surface Properties And Functionality, Ali Jamal Mazaltarim

Department of Chemistry: Dissertations, Theses, and Student Research

Material interfaces are of critical importance to numerous fields, including nanomaterials, electronics, microfluidics, synthesis, bioanalysis, pharmaceuticals, and catalysis, and they have been extensively researched. The materials used in these fields are often rigid/hard (such as silicon wafers) resulting in static surface properties. Consequently, the chemical/morphological properties of a surface may be modified using synthetic or mechanical means to tailor the interfacial properties of a material (i.e., surface energy, adhesion, topography, and reactivity). Recently, emphasis has been placed on designing dynamic materials with adaptive interfacial properties that respond to a variety of environmental stimuli. To this end, the surface chemistry and …

Surface Functionalization Of Elastomers For Tunable Crystal Growth And Smart Adhesives, John Kapitan

Department of Chemistry: Dissertations, Theses, and Student Research

Silicone rubbers have seen extensive work on modulation of their surface environments for use in microfluidics, cell adhesion, and sensing. Most surface procedures utilize a common initial step of oxidation of the surface to increase the number of active surface functional groups. Following oxidation more permanent functionalities can be imparted on the surface using silanization, grafting polymer brushes, or creating ionic bonds to the surface. Of these three, silanization proves to be the most pervasive due to the range of procedures available and how easy the procedures prove to be. However, the mechanism by which silanization is performed heavily involves …

Electropolymerization And Characterization Of Thin Film Dielectrics, Christopher White Ii

Department of Chemistry: Dissertations, Theses, and Student Research

Graphene is a two-dimensional allotrope of carbon, with several superlative properties, including high electron and hole conductivities, high tensile strength, and chemical robustness. Its chemical and physical properties make it attractive for in use in a myriad of applications, including transistors. However, graphene’s chemical inertness and its physical and electrical properties’ dependency on its conjugated structure make building composite materials with graphene difficult. In 2015, Lipatov, et. al. demonstrated that a film derived from electropolymerized phenol could be used as a dielectric layer on transistor devices fabricated from exfoliated graphene. This thesis extends that research, detailing experiments of phenol and …

Synthesis, Characterization, And Catalytic Activity Of Copper Palladium Oxide Solid Solutions., Gregory L. Christensen

Department of Chemistry: Dissertations, Theses, and Student Research

Cu_xPd_1-xO forms a homogeneous solid solution over the wide range of 0 ≤ x ≤ 0.725 in which compositional variation can be correlated with structural and chemical environmental changes. After a small lag at low Cu²⁺ concentrations, where the lattice cell parameters are pinned to that of the pure PdO structure, Cu_xPd_1-xO lattice parameters follow Vegard’s law in which the cell volume decreases linearly with x, indicating a homogenous solution in which Cu²⁺ randomly replaces the larger Pd²⁺ cation. The crystal structure also undergoes an increase in the c/a …

Design And Synthesis Of Novel Octacarboxy Porphyrinic Metal–Organic Frameworks, Jacob A. Johnson

Department of Chemistry: Dissertations, Theses, and Student Research

Metal-Organic Frameworks (MOFs) are a class of nanoporous crystalline materials constructed via the interconnection between metal-ions/inorganic clusters and organic ligands. Since the surface area, pore size and distribution, and chemical functionalities of MOFs are highly tunable via the judicious combinations of inorganic clusters and organic ligands, MOFs have attracted intensive interests for a variety of applications including gas adsorption and separation, catalysis, chemical sensing, and drug delivery among others. Porphyrin based ligands are of particular interest for building functional MOFs due to their unique photo-, electro-, and catalytic properties. In addition, the four-fold symmetry of porphyrin ligands offers an effective …

Synthesis And Applications Of Lanthanide Sulfides And Oxides, Christopher Marin

Department of Chemistry: Dissertations, Theses, and Student Research

This dissertation focuses on two of the key fields where lanthanides find ready application: as optically active materials with a focus on the lanthanide sulfides, and as catalytic materials with a focus on cerium oxide.

The lanthanide sulfides have attracted considerable interest for their potential as solar energy conversion materials, pigments, infrared window materials, and phosphor host media. However, applications of these materials remain limited due to their synthetic difficulty along with their not well understood properties compounded by both their difficulty in manufacturing as well as in simulating largely due to the need to take into account f-shell electrons. …

Uses Of Diaryliodonium Salts And Methods For Their Synthesis, Jordan M. Veness

Department of Chemistry: Dissertations, Theses, and Student Research

Diaryliodonium salts have been studied continuously since the first report of their synthesis in 1894. Diaryliodonium salts are I(III) derivatives that are air- and moisturestable. The reactivity of these compounds resembles the organometallic chemistry of heavy transition metal ions such as Pb(IV), Hg(II), Th(III), and Pd(II). A significant advantage of diaryliodonium salts is that they can carry undergo many of the aryl functionalization reactions of heavy metal organometallic complexes, yet they have little to no toxicity and they are relatively inexpensive to prepare. The DiMagno laboratory uses diaryliodonium salts as precursors in the final synthetic step of radiopharmaceuticals; given that …

Three-Dimensional Scaffolds Of Graphene, Carbon Nanotubes And Transition-Metal Oxides For Applications In Electronics, Sensors And Energy Storage, Gilbert N. Mbah

Department of Chemistry: Dissertations, Theses, and Student Research

Electronics, sensors and energy storage devices are the new waves behind economic development, security and communication¹. Engineering small sizes of electronic, sensors and energy storage devices is the hurdle limiting efficient, portable and vast applications of Nano-devices for economic, security and communication advancement². Silicon the major material used in transistors has approached its limit to fabricated Nano-devices³. The discovery of free standing, one atomic layer thick and two-dimensional graphene sheets with high conductivity, inert, high specific surface area, stable and high tensile strength material in 2004 has shown capabilities to replaced silicon in electronics, …

Syntheses Of Aminyl Diradicals And Nitroxide Tetra- And Octaradicals, Arnon Olankitwanit

Department of Chemistry: Dissertations, Theses, and Student Research

This dissertation comprises of two main research projects: aminyl diradicals and calix[4]arene nitroxide tetra- and octaradicals. The design, multi-step synthesis and characterization, including NMR, EPR spectroscopy, magnetic measurements and X-ray crystallography of precursors and target compounds will be discussed.

Aminyl radicals, nitrogen-centered radicals, are typically short-lived and considered as reactive intermediates. Because of their unique magnetic properties, aminyls are attractive building blocks for high-spin di-and polyradicals. The challenge is in the design and synthesis of aminyls with increased stability. In this chapter, we have prepared triplet (S = 1) ground state aminyl diradicals, which are derivatives of aza-m …

Preparation And Characterization Of Biomimetic Hydroxyapatite-Resorbable Polymer Composites For Hard Tissue Repair, Kristopher R. Hiebner

Department of Chemistry: Dissertations, Theses, and Student Research

Autografts are the orthopedic “gold standard” for repairing bone voids. Autografts are osteoconductive and do not elicit an immune response, but they are in short supply and require a second surgery to harvest the bone graft. Allografts are currently the most common materials used for the repair of segmental defects in hard tissue. Unlike autografts, allografts can cause an undesirable immune response and the possibility of disease transmission is a major concern. As an alternative to the above approaches, recent research efforts have focused on the use of composite materials made from hydroxyapatite (HA) and bioresorbable polymers, such as poly-L-lactide …

Resorbable Polymer-Hydroxyapatite Composites For Bone Trauma Treatment: Synthesis And Properties, Troy E. Wiegand

Department of Chemistry: Dissertations, Theses, and Student Research

Contemporary therapies for hard tissue replacement involve allographs, where the donor and recipient are of the same species, or the use of xenogenic transplants.  Intraspecies materials are often in short supply and interspecies materials are subject to immunological barriers such as disease and tissue rejection.  Synthetic composites are unencumbered by these limitations.  Poly lactic acid (PLLA) and its copolymers have been used in medicine due to their ability to be resorbed by the body without adverse effects.  PLLA’s are currently most commonly used in resorbable sutures and gauzes, but there is increasing interest in using them in conjunction with hydroxyapatite …

Fabrication And Catalytic Property Of Cerium Oxide Nanomaterials, Keren Jiang

Department of Chemistry: Dissertations, Theses, and Student Research

Cerium oxide, or ceria (CeO_x: x = 1.5 to 2), has been widely used as a heterogeneous catalyst. Ceria has several properties make it high catalytic active: the fluctuating valence of cerium, the high oxygen storage capacity and high oxygen mobility in the nonstoichiometric ceria. With the high abundance of cerium on earth crust, ceria is a highly effective alternative of the noble metal catalysts. Research has been focused on designing nanostructured ceria and ceria related materials in recent years. The catalytic activity of ceria can be enhanced by the nanoscale effect which can be applied for various …

High Temperature Rare Earth Compounds: Synthesis, Characterization And Applications In Device Fabrication, Joseph R. Brewer

Department of Chemistry: Dissertations, Theses, and Student Research

As the area of nanotechnology continues to grow, the development of new nanomaterials with interesting physical and electronic properties and improved characterization techniques are several areas of research that will be remain vital for continued improvement of devices and the understanding in nanoscale phenomenon. In this dissertation, the chemical vapor deposition synthesis of rare earth (RE) compounds is described in detail. In general, the procedure involves the vaporization of a REClx (RE = Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho) in the presence of hydride phase precursors such as decaborane and ammonia at high temperatures and low …

Classification, Synthesis And Characterization Of Pyridyl Porphyrin Frameworks, Lucas D. Devries

Department of Chemistry: Dissertations, Theses, and Student Research

Structural analysis of a solid-state material is vital because the structure often determines the physical (or chemical) properties of the material. An understanding of the relationship between structural components and bulk properties can be used to design materials with specific properties. To achieve such understanding, two things are required: a rigorous structural analysis method and a study of the properties of materials with noteworthy structural features. In this thesis, the author reviews 44 pyridyl porphyrin frameworks in an effort to determine how these framework structures are formed, and if any overreaching trends can be observed. The observed trends are used …