Until recently, little research has been done on C-S bond formation in transition-metal catalyzed transformations compared to other carbon-heteroatom bonds such as C-N, C-O, and C-P. As sulfur-based coupling partners (thiol and disulfide for example) tend to poison transition-metal catalysts, development of C-S bond formation has been slow. However, a recent nickel-catalyzed system shed new light on this difficult transformation. In this context, C-H functionalization is a sustainable and straightforward approach to sulfur-containing heteroaromatic production. C-H activation is a process whereby a carbon-hydrogen bond is cleaved, thereby allowing the exposed carbon atom to form new bonds. Thus, in order to expand the above research of C-S bond formation toward development of short synthesis for fused thiophene systems, focus was placed on a palladium catalyzed cascade-type reaction system. C-H activation reactions can and have been manipulated to work in a cascade-type fashion. By combining cascade-type methodology with the reduced environmental impact of C-H activation, these fused thiophenes can be synthesized cleanly and efficiently. The test substrates in this work are O,O-diethyl S-phenyl phosphorothioate and 4,4,5,5-tetramethyl-2-(thiophen-2-yl)-1,3,2-dioxaborolane. Both substrates were chosen because they contain sulfur, thereby aiding the C-H activation process. By effecting a C-H activation with a palladium catalyst at one of the ortho carbons of the phenyl ring with the boronic ester of the thiophene, the first C-C bond will be formed. In the time immediately after this first transformation, the now-changed palladium complex is able to insert into the S-P bond of the phenyl-based compound. This step sets up the second reaction, whereby the phosphorothioate directing group is cleaved along the S-P bond and the resulting thiol is coupled to a carbon atom to close the ring. This molecule is known as benzo[b]thieno[2,3-d]thiophene.

A non-destructive inspection (NDI) technique that integrates mechanochromic fluorescent probe molecules into aerospace composite matrix resins was investigated. The NDI technique aims to allow quick and inexpensive inspection of aerospace composites that could reduce the need to over-design composite structures for undetected damage. This experiment was focused on determining the effect of the matrix resin mechanical properties on the activity of the fluorescent probe molecule. In the first step of this experiment, samples of epoxy (diglycidyl ether of bisphenol A (DGEBA)-diethylenetriamine (DETA)) functionalized with fluorescent probe molecules were fabricated. To change the mechanical properties of the epoxy samples, diglycidyl ether (polypropylene glycol) (DGE(PPG)) was added to the samples incrementally from 0-100 weight percent (wt%). To determine the effect of mechanical deformation on the probe in cured DGEBA/DGE(PPG)-DETA, fluorescence spectra were taken before and after incremental compression of the functionalized epoxy samples. The fluorescence testing revealed that the fluorescence activation increases with increasing compressive strain, strain energy, and stress, with a linear relation between fluorescence activation and strain. Furthermore, the fluorescence testing revealed that the fluorescence activation decreased as the modulus of the sample decreased, with the exception of the neat DGEBA-DETA sample. The fluorescence testing also revealed that, without exception, the fluorescence activation decreased as the glass transition temperature decreased and as the wt% DGE(PPG) increased, with no fluorescence activation for 40 wt% DGE(PPG) and above. These results suggest that the sample’s composition (wt% DGE(PPG)) and thermal properties (Tg) are more dominant factors affecting the probe’s response than the sample’s mechanical properties. Future work on this research will be aimed at determining why, on a molecular scale, the probe response decreases with increasing wt% DGE(PPG) and decreasing Tg.

Organic Photovoltaics (OPVs) provide a potentially cheap and clean option to harvest energy from the largest source of energy available - the sun - however they are still fairly inefficient when compared to inorganic photovoltaics. Attaching fluorine to the polymer backbone has been shown as an effective way to increase the open circuit voltage (Voc) and power conversion efficiency of the devices by lowering the highest occupied molecular orbital of the polymer. However, the impacts of fluorine attachments on the other properties of active layer, like morphology under different processing conditions and electrical properties, have not been fully studied. Knowing this information will help the future designs and processing of donor-acceptor polymers for OPV application. In this project, three structurally identical polymers, with zero, one, and two fluorine attachments (named P0F, P1F, and P2F) were studied. The morphological impact of fluorine attachments are studied by varying the ratio of PCBM (a widely used and promising acceptor) and these three polymers as well as the solvents used when processing through atomic for microscope (AFM). Hole features were found on the surface of the thin film. The density of and depth of the holes were found to correlate to the number of fluorine attachments and processing condition respectively. Future works are being done to investigate the reasoning behind the device efficiency with the attachment of fluorine and differentiating whether this is due to these physical morphologies or bandgap manipulation being the primary contributor to a higher efficiency. The influence of fluorine on the dielectric constant of the thin film and operation of OPVs will also be studied. 

Organic electronics is a growing area of research that investigates the properties and applications of conjugated polymers and conductive small molecules. Devices made from organic electronic materials can be flexible, inexpensive to process, and have lower weight compared to inorganic devices. Prominent synthetic techniques for conjugated polymers, including the Suzuki reaction, Heck reaction, and Kumada coupling, utilize a palladium or nickel complex as the catalyst. When the reaction completes, organometallic molecules and metal nanoparticles remain stuck in the polymer, decreasing the efficiency of resulting devices by acting as charge trappers or photo quenchers. The potential commercial success of organic electronics is highly dependent on their efficiency, and so the impurities need to be removed. A palladium-catalyzed model Suzuki coupling reaction of bromobenzene and phenylboronic acid was analyzed by 31P-NMR both before and after the post-synthetic addition of thiuram disulfide (TMTD). Pd(PPh₃)₂Br₂ dibromide was present in the solution prior to the post-synthetic disulfide addition, but not after. When TMTD or diphenyl disulfide were added directly to metal catalyst in chloroform, the resulting product precipitated out; the solubility of the product was different from the reactants. The change in solubility indicates that disulfide molecules can behave as metal scavenger for residual palladium or nickel catalyst. In order to restore the performance of organic polymers, scavenger molecules are used post-synthesis. This additional step isolates palladium or nickel atoms and changes their solubility, allowing them to be separated from the polymer. The performance of disulfide-based metal scavengers added to catalyst-metal-contaminated conjugated polymers is discussed.

Solar energy is arguably the most promising source of renewable energy because it is thought to be both the cleanest and most abundant source. There are several types of solar cells including organic, inorganic, and hybrid organic-inorganic solar cells. While inorganic solar cells have high efficiencies, good charge carrier mobilities, and relatively long charge carrier times, their expensive production and materials competition with the microelectronics industry has kept their prices high. Organic solar cells are solution processable, applicable to flexible substrates, and have the promise of being relatively cheap to produce. However, their relatively low charge carrier mobilities and short exciton diffusion lengths prevent them from being used as an alternative to inorganic solar cells. Hybrid organic-inorganic solar cells have been introduced as a substitute to both organic and inorganic solar cells in order to overcome the short-comings of each. Inorganic semiconductors are used in hybrid photovoltaics as the acceptor in the solar cell due to the ease of changing the size and shape, and therefore the bandgap, of these semiconductors, which allows them to contribute to the photocurrent of the cell while enhancing the conductivity. This project addresses the synthesis of cadmium selenide (CdSe) nanotetrapods, which may facilitate control of direction of electron motion in the active layer of the cell. The reaction time, growth temperature, ligand type, and monomer concentration were used to control the synthesis, and the effects of each variable on the size and shape of the tetrapods were studied via transmission electron microscopy (TEM).

Iron-oxide magnetic nanoparticles (MNPs) with tuned magnetic properties can enable novel diagnostic and therapeutic technologies such as magnetic particle imaging and hyperthermia. In order to optimize the magnetic properties of MNPs, organic synthesis methods are required. However, these organic synthesis methods render the nanoparticles hydrophobic and unusable for biomedical applications. To make MNPs functional in biomedical applications whilst retaining their magnetic functionality, they must be transferred to the aqueous phase using a biocompatible polymer. In this work, MNPs will be coated using a biocompatible PEG-ylated amphiphilic polymer: poly (maleic anhydride-alt-1-octadecene) or PMAO-PEG. To ensure the PMAO-PEG is a well suited polymer coating for MNPs, various molecular weights and molar ratios of PMAO-PEG are synthesized and characterized to study the effects of PEG surface density and molecular weight on MNPs. By altering the density of the polymer used to coat and phase transfer MNPs, effects such as the solubility, circulating life, colloidal stability, dosage frequency, and proteolytic degradation rates of MNPs in the biomedical applications are studied using data obtained from Gel Permeation Chromatography (GPC) and Fourier Transform Infrared Spectroscopy (FTIR). Molecular weight distributions of the various polymers are obtained from the GPC to evaluate the conjugation success after PEG-ylation. In addition, FTIR was used to identify known and unknown materials in the samples, determine the quality and consistency of samples, and to determine the amount of components in samples.

Palladium is a part of the Platinum Group Metals (PGM), and is highly used as a catalyst in many applications such as in an automobile’s catalytic converter. It has also been successfully used for hydrogen gas sensing devices. Employing low-cost, efficient means to synthesize palladium nanowhiskers in the lab has been the focus of my research thus far. Hydrothermal synthesis and dislocation mechanisms have been used for the growth of palladium nanowhiskers using a palladium (II) chloride charge. The hydrothermal synthesis involved chemical reactions as well as thermal reactions in the growth of the nanowhiskers. In the dislocation mechanism, the growth of the whiskers is the result of the thermal decomposition of palladium chloride to palladium plus chlorine gas. Scanning electron micrographs from the first four runs of the hydrothermal synthesis showed little to no nanowhiskers. The first run of the dislocation mechanism grown samples is currently awaiting characterization. Future work for my research involves many more dislocation mechanism growths of the palladium nanowhiskers, as well as an attempt to use electrochemical deposition as a third technique in producing these whiskers. The application of these nanowhiskers in hydrogen gas sensing is based on the change in the conductance of the whiskers upon absorption of hydrogen. This allows for highly sensitive sensors to be made.

This investigation focused on the unique electrical behavior of exfoliated graphene; planar sheets of carbon atoms stripped from bulk graphite flakes. Specifically, the doping effect from self-assembled monolayers (SAMs) on the graphene surface was examined. Previous research has found that certain peptide SAMs are capable of influencing the electrical nature of graphene as both n-type and p-type dopants. This phenomenon can likely aid in development of biosensing and “lab on a chip” technologies. Graphene prepared by the scotch tape method was exposed to chemical solutions of tyrosine (Y) and phenylalanine (F) amino acids. These results are compared with the behavior of similarly deposited GrBP5, a peptide sequence selected for its high binding affinity to graphite. To measure the conductivity and current-voltage profile of graphene doped with each material, graphene field effect transistors (g-FETs) were fabricated on a silicon oxide substrate. Previous research has confirmed GrBP5 is a p-type dopant (electron acceptor). Data collected in this investigation suggests that the tyrosine binding group of GrBP5 is likely the electron acceptor, based on its highly similar doping effect. This p-type nature may be due to the aromatic functional group of tyrosine and would be recommended for future investigation. Furthermore, phenylalanine was found to be an n-type dopant, exhibiting a lower magnitude of doping despite its chemical similarity to tyrosine. By understanding the role of specific amino acids in peptide SAMs for g-FET applications, a large range of peptides may be integrated into this technology, leading eventually to novel biosensing devices.

Titanium Oxide (TiO₂) nanotubes, nanowires, and coreshell structures have the potential to be implemented in new unique devices. TiO₂ has a variety of gas-sensing, photovoltaic, and semiconductor properties. TiO₂ has multiple forms such as TiO₂(B) and anatase, which could be surface modified. These forms are synthesized depending on the hydrothermal treatment. The ultimate goal was to create a thin film, out of nanowires, for a top contact field effect transistor. For an efficient top contract, the film must be homogeneous and be composed of one or two layers of nanowire. The creation of nanowires started with anatase or p25 combined with a 10 M NaOH solution that underwent a hydrothermal process for 48 hours. With two autoclaves, two reactions can be done simultaneously. Keeping one reaction constant as control, the other autoclave had its parameters slightly modified. The modifications in thermal ramp rate, solution molarity, hydrothermal duration, and amount of starting material, helped understand the titante nanostructures and growth mechanism. 170°F was the established temperature where nanotubes started turning into nanowires while 200°F was the control. There were several treatments, post-hydrothermal, to acquire TiO₂(B). An ion-exchange transformed Na₂Ti₃O₇ into H₂Ti₃O₇ then calcination produced TiO₂-B. With these materials, several methods, such as spin-coating and drop-casting, were tested to create a thin film.  For a consistent film, the nanowires must be uniform and the fabrication process reproducable. 

The aerospace industry today utilizes composite materials for a number of structural components due to their high strength to weight properties. Assembling these composite parts to an airplane currently requires fasteners such as bolts or rivets, even though they add weight and reduce the mechanical properties of the composite parts. Integrated monolithic composite structures not requiring bonding or fastening could improve the strength, fuel efficiency, and ease of assembly of a commercial airplane. Cellular Core Technology (CCT) has been used to create double-box beam composite structures that do not require traditional fastening. The cellular cores provide an internal surface which can apply heat and pressure to all surfaces of a part allowing for high consolidation of complex structures. The consolidation at joints within integrated structures has been a prospective problem, leading to high void content and stress concentrations causing premature failure. The effect of fiber orientation on the expansion of the cellular cores was studied to determine if the fibers restrict the pressure provided by expansion. Double box beams were fabricated while altering the fiber orientation of the carbon fiber plies between 0/90 degrees and +/-45 degrees. After curing, the expansion of the cellular cores for each structure was investigated in order to determine the effect of fiber direction on the restriction of cellular cores and subsequent porosity in the joints. Optical microscopy was used to assess porosity around the joints of each double box beam. Mechanical tests were performed using Digital Image Correlation (DIC) to evaluate the effect of fiber orientation on the stress and strain fields throughout the T-joint geometry. Future work will include determining additional factors that affect the porosity of the joints such as the relationship between the number of plies and the expansion capabilities and the expansion limits for the cellular cores.

My senior research project consisted of the manufacturing and development of a composite structure for the encasement of the cooling pump for UW Eco Car II. The purpose of creating this structure was to discover the relationship between nanoscale elements (voids, impurities, toughening particles) and the mechanical performance of the composite while maintaining an acceptable strength-to-weight ratio. The composite box was constructed using S-glass fiber plies and a two-part epoxy resin matrix. The wetting of the plies was done using a hand lay up technique. Once each ply was fully impregnated with the resin matrix, the plies were then transferred onto a wood tool that was covered in fluorinated ethylene propylene (FEP). Subsequent wrapping of perforated FEP, bleeder material, and another layer of FEP was bagged under vacuum and left to cure at room temperature. Although this object was cured at room temperature, the use of an autoclave could enhance the mechanical stability of the composite. The combination of heat and pressure would eliminate nanoscale impurities such as voids or semi-crystalline regions as well as promote adhesion of the matrix and fibers. Moreover, the addition of thermoplastic nanoparticles such as polyester could effectively reduce interlaminar shear. Further analysis was conducted into finding the optimal size of these particles to maximize the performance of the composite structure. Through controlled techniques and a proper cure time, a uniform composite casing was fabricated and mounted in the trunk of the Eco Car II. The introduction of thermoplastic elastomeric nanoparticles into the epoxy resin matrix during the mixing process could effectively toughen the composite and would require an autoclave autoclave to ensure the particles were co-continuous within the matrix. At this stage, the thermoset keeps its high glass transition temperature while the thermoplastic increases toughness.

Thermoelectric materials have the ability of converting wasted heat into electricity. The energy conversion efficiency of thermoelectric materials is determined by its figure of merit- ZT. The equation of figure of merit is ZT = S2T/ρκ, where S is the thermopower, T is the absolute temperature, ρ is the electrical resistivity, and κ is the thermal conducivity. Currently, existing homogeneous bulk thermoelectric materials have the highest ZT, at around 1.5. This project consists of designing high efficiency hierarchical thermoelectric composites with a ZT value greater than 2 by using energy filtering at interfaces to block the low-energy charge carriers, and, thus, increase the average energy transported per charge carrier. This results in an increase in thermopower(S) and, hence, an increase in power factor of ZT. Using solution-based solvothermal chemistry, which allows for control of the dimensions and morphologies of the nanoparticles through variations of the reaction parameters, we prepared low-dimensional thermoelectric nanobulk Bi2Te3. The surfactant-free scalable synthesis of Bi2Te3 provides quick and bottom-up synthesis with 90% yield. After these chemical processes, a dry nanoparticle sample will be consolidated by Spark Plasma Sintering, and turn into a pellet. The lowest sintering temperature determination will benefit to define the processing limitation in the further nanocomposite design. More comparison of the electronic transport properties measurements in bulk and nano Bi2Te3 will be carried out later. If the high-yield synthesis with doping capability can be achieved; also, if the processing limitation is known, it has high potential to achieve thermoelectric material with ZT higher than 2.

For thermoelectric (TE) applications, oxides possess certain advantages over conventional intermetallics, including excellent high-temperature stability, low toxicity, and a complex structure, which aids in lowering the thermal conductivity. Recently, it has been found that SrxBa1-xNb2O6 (SBN) holds potential for use in high-temperature TE applications (e.g., waste heat recovery). In our work, a solution combustion synthesis (SCS) process was devised to fabricate SBN with a range of Sr:Ba ratios in order to ascertain an ideal SBN composition for optimum TE behavior. The SCS method, which is highly amenable to mass production, allowed for good control of the SBN stoichiometry, and the as-processed powders were found to possess good single phase purity. Powders processed with different SBN compositions were subject to conventional sintering followed by reduction. The TE properties of each SBN composition were then tested and compared. Preliminary results of our acquired data suggest a decrease in the thermal conductivity as the Ba content is increased, likely due to the larger mass of Ba when compared to Sr. From the obtained results, an ideal SBN composition was determined having the optimal TE performance. Field assisted sintering (FAST) was then employed to processed SBN powder having the optimum composition, and the TE properties of the SBN from both conventional sintering and FAST were compared.

Nanoimprint lithography (NIL) has become a widely used technique in fabricating nanoparticles using a top-down approach with several advantages over bottom-up chemical methods, including being able to precisely control particle shape, size, structure, and composition. Using NIL, synthetic antiferromagnetic (SAF) nanoparticles can be fabricated using multilayer deposition techniques, imprinting, liftoff, and particle release into water with limited defects. The particles can also be coated with a functional polymer so that they can be used in a number of drug delivery systems. However, common NIL techniques often make it difficult to add functional coatings to the particles after the particles are released in water. Deposition methods for different layers, as well as using silicon molds that introduce defects and irregularity in particle size are other pitfalls that can be corrected using a new approach. The nanoparticles (~300 nm diameter) were homogeneously patterned using a mold to etch disk-shaped nanoparticles on a silicon substrate with layers of titanium and magnetite deposited on its surface via magnetron sputtering to contribute to the antiferromagnetic properties of the particles.  The fabrication process is extensive and utilizes many clean room processes, including nanoimprinting, dry etching, undercutting, multilayer deposition, liftoff, and polymer coating, though polymerization was not explored in this study.  Following, release techniques were used to produce a monodisperse and homogeneously-sized sample of high moment, multilayer particles in water with high saturation magnetization and low toxicity. Final results to determine the effectiveness of the particles were determined by studying the magnetic properties of the nanoparticle solution sample in the presence of an external magnetic field. With antiferromagnetic and useful imaging properties, functional biomagnetics could become a highly useful material system. Future work in this field includes biofunctionalizing the particles to modify in-solution behavior and implementing them into various biomedical systems, depending on how small the particles can be made using NIL.

Aerospace vehicles, such as reusable spacecraft and hypersonic flight vehicles, require materials that can both provide high thermal resistance and high mechanical strength. Thermal insulation is required to protect the vehicle interior including occupants from the high heat of reentry and mechanical strength is required to withstand the variety of loads including the forces experienced during launch. In general, it is difficult to meet both these requirements at a high level since the normal way to increase thermal resistance of porous ceramics is to increase the porosity but this reduces strength. We are currently developing and investigating anisotropic porous ceramics that have the potential to optimally meet both these requirements. We are making the anisotropic porous ceramics from through a route called polymer derived ceramics (PDCs). The class of PDC’s that is being investigated is siloxanes, which decompose at high temperatures (~800^oC) into a SiOC ceramic. These materials have excellent high temperature resistance including creep and low thermal conductivity. Polymethylphenylsilsesquioxane (Waker H44) is first cross-linked and milled into a fine powder. The powder is then pyrolyzed to a SiOC ceramic that is then milled into a fine ceramic powder. A water-based slurry is made and poured into a mold that sits on a cold copper rod that is cooled in a liquid nitrogen bath. This causes ice crystals to form in the slurry which grow perpendicular to the copper rod. The frozen component is then freeze dried, causing the ice to sublime leaving a highly anisotropic porous structure. The thermal and mechanical properties will be measured in the longitudinal and transverse directions and the properties of these anisotropic porous microstructures will be compared to those of isotropic porous ceramics of similar porosity.

Currently, one of the main challenges is the development of new technologies for the storage of energy. Hence, there exists a particular interest for a low-cost, safe, rechargeable battery with high capacity, voltage and rate capability. My project consists of developing a better understanding of the charge-discharge cycles and the factors constraining the electrochemical performance of the active material within a lithium-ion battery. Electrode efficiency depends highly on the active materials used. The chemical composition of the cathode material is one of the keys to optimize the performance of these batteries where three metal salts (Co, Ni & Mn) are combined under the following formula: (1-z) Li [Li_(1⁄3)Mn_(2⁄3) ] O₂ - (z) Li [Mn_(0.5-y)Ni_(0.5-y)Co_(2y)] O_2. Each metal has major downsides such as high cost, toxicity or reversibility loss, but they also offer high capacity or stability. In order to maximize the performance of the cell, an optimized battery must comprise a particular percentage of each metal. Under the supervision of Carolina Vinado, we have successfully synthetized several lithium-ion rechargeable coin cells which are currently being tested for reliability. For our first batch, we used an equivalent amount of cobalt and nickel, assigning the values of 0.4 and 1.6 for z and y respectively. The resultant formula is shown: Li_1.20Mn_0.54Ni_0.13Co_0.13O_2. The next phase of the project involves the modification of the cathode’s chemical composition for testing and future analysis. In addition, we are planning to analyze the surface of the cathode using Transmission Electron Microscopy (TEM). This facilitates the examination of the interface morphology, which after various charge/discharge cycles may develop defects on its surface. It is essential to understand these surface anomalies as they critically affect the battery’s ability to perform effectively.

Nanoscience and nanotechnology has evolved rapidly in recent decades. It promises a greater understanding and higher degree of customization in future materials. One field of interest is the ability to mimic the biological composition of bone tissue using nanoscale hydroxyapatite (HA). With the ability to manufacture and impregnate with proteins, the mimicked tissue can be utilized in vivo without the side effects of traditional organ transplants and biocompatible materials. HA nanowires were fabricated using a hydrothermal synthesis process. First, the precursor composed of calcium phosphate was synthesized via a sol-gel process to create a powder. After suspending the powder in solution of DI water and ammonium hydroxide, the solution was loaded into an autoclave and heated at 170 degrees Celsius for various time periods. The product was then characterized using optical microscopy, scanning electron microscope (SEM) X-ray diffraction (XRD), and Raman spectroscopy. First, SEM was used to determine if particles were successfully synthesized. Next, the size of the nanowires was characterized. It was found that the nanowires had an aspect ratio of 5:1. XRD powder diffraction showed that the samples matched the industry standard peaks for HA. Lastly, Raman spectroscopy was conducted but the results are yet to be analyzed. The work has successfully synthesized nanowires of hydroxyapatite utilizing a hydrothermal process. Through use of the above characterization methods, we find that an alteration to the synthesis must be performed to obtain HA nanowires with larger aspect ratios. – 20:1. Successive syntheses are being conducted by varying pH levels and time periods to achieve the desired lengths.

In this study, we attempt to gain a better understanding of how poly(3-hexylthiophene) (P3HT) nanowires self assemble in solution. P3HT is used as the primary p-type donor in conjunction with phenyl-C61-butyric acid methyl ester (PCBM) in bulk heterojunction polymer solar cells. During self assembly, individual P3HT chains begin to kink after about 40 monomer units into an S-like shape. These S-shaped chains interact with one another via pi-pi interactions and form nanowires with widths typically between 20 and 70 nm and heights between 3 and 5 nm. In an attempt to improve device efficiency, we would like to exhibit greater control over the size of the nanowires. Controlling the morphology of the nanowires would allow us to improve the efficiency of the device. Thus, we demonstrate a method to create self-assembled nanowires from 12.5, 16, and 28 kDa molecular weight P3HT. P3HT solutions were made with a concentration of 1 mg of polymer to 2 mL of solvent (anisole and chloroform in a 4:1 ratio). These solutions were then heated at 80°C and thoroughly mixed for 16 h. After mixing, the solution is removed from heat and allowed to self-assemble for several days. Finally, the solution is then spin coated onto a silicon dioxide coated silica substrate. The samples were analyzed using atomic force microscopy to provide detailed information about the surface coverage, width, and height of the nanowires.

Glass sponge spicules (elements of the skeleton) have been shown to exhibit unique energy dissipating characteristics which may be extendable to applications such as earthquake protection, deep-sea fiber optics, and ceramic implants. Previous studies have revealed that a small volume (less than a few percent) of viscoelastic organic constituent is present throughout the spicule and acts as a key component in controlling the spicule’s mechanical behavior. However, the spatial distribution of the organic component within the bio-mineralized glass material has yet to be identified. This information may be critical to understanding the spicule’s energy dispersive behavior and, by extension, influence the design of new glass- or ceramic-based composites. Through the use of high resolution microscopy and other microscopic analysis techniques this study investigates the presence of organic material within the glass phase of these structures as a precursor for developing spicule-inspired synthetic composites.

The fabrication of nanoparticles in an array structure with specific geometries is critical for a variety of nano- and micro-technologies ranging from electronics to photonics. Metallic nanoparticles arrays organized on surfaces as a thin film are particularly promising for construction of sensing devices and systems. Although there are current methods in which control of nanoparticle pattern can be achieved, many come with harsh draw backs that range from high cost to the use of toxic chemicals that limit medical applications. This project focuses on a combined biological and material engineering approach to develop a bio-enabled fabrication method to control the nanoparticle arrays with desired geometry. Our research uses bi-functional quartz- and gold-binding peptide sequences (AuBP-QBP) to create gold patterns using soft lithography and self-assembly techniques. The multi-functionality of the peptide as well as its organic nature enable the peptide to self-assemble on the quartz surface within a short time while the assembled biomolecule provides the control of the gold nanoparticle array geometry within the desired structures. Overall, the gold thin film arrays are achieved under aqueous environment via single step bio-assembly process. Our evidence of the desired pattern control is verified by various microscopy techniques that include Dark Field Microscopy, Atomic Force Microscopy, and Scanning Electron Microscopy. The results of our research will contribute to develop metallic thin films arrays using a simple biologically relevant method in a controlled pattern. Future applications of this project will include developing variety of patterns having different nanoparticles size and shapes to follow various cellular and biomolecular responses on solid substrates.

The Hanford Site in south-central Washington State has played a pivotal role in the history of the United States, and the world. The weapons grade Plutonium produced at the site from 1943 to 1987 became a critical component of the tens of thousands of nuclear warheads in the US arsenal. While this is a noteworthy legacy for any place to leave behind, there is another story to Hanford that will have implications for decades, centuries and millennia to come. Hanford is the most contaminated nuclear site in the United States, and is currently in the midst of the largest and most expensive clean-up effort in the world. This project explored the issues pertaining to the Hanford Site from the standpoint of radioactive waste management, complete with an overview of the nuclear fuel cycle and the complications that arose with managing the two million cubic meters of liquid radioactive waste. A plethora of miscalculations over the course of decades resulted in the ecological catastrophe that is Hanford, whether it’s the lack of foresight on the limitations of the waste tanks, extended delay of the $12 billion waste processing facility or an overall disregard of the waste itself. While this project explores key critical mistakes from a technical standpoint, it also focuses on the lessons learned, and the implications they will have on future cleanup efforts, and nuclear energy as a whole. The key question this project sought to resolve is how the inherent hazardous nature of nuclear fuel itself can be distinguished from unprecedented level of mismanagement, and how both of those factors will make or break the future of nuclear energy. 

As consumers - especially as consumers in the industrialized United States - we go through a considerable amount of material goods and create copious quantities of solid waste on a regular basis. Generally, after we dispose of waste (items no longer of value to us), the discarded materials are out of sight and out of mind. However, the effects of our solid waste are not negligible by any means. The materials that we put in the trash, recycling, or elsewhere, can have undesirable effects on human health, human society, the natural environment, and even the climate. The materials chosen to produce various goods can have substantial impacts that far outlive the lifespan of the consumer products. Waste materials break down - or in some cases, do not break down – and the components have the potential to go through phase changes leading to a risk of harming groundwater and air quality. On Earth, we have an ever-growing human population; a constant stream of mass-produced consumer goods; and a finite amount of land and raw material resources. Actively examining and modifying how we manage our waste – at various stages within the materials’ life cycles – is critical when regarding the future of human and environmental well-being. This research, by means of searching through various media resources and conducting interviews, investigates waste and management techniques with a materials-conscious lens. This presentation will delve into some of the main issues in landfills, such as the most problematic materials that don’t decompose well; the pros and cons of current waste management methods; and potential alternatives and solutions – often involving a materials focus - that fit into various parts of the product-to-waste life cycle.

Every year an estimated 6.4 million tons of plastic waste manifests itself in the world’s oceans through a number of avenues. Due to the fact that this plastic waste accumulates and covers large, mobile swatches known as “garbage patches,” tracking and studying them is a time and labor intensive process. This project focuses on examining the size and extent of the garbage patches in the oceans and considers the pros and cons of various solutions for “end of life” plastic processing for the plastic debris present in the patches. Sampling efforts have been concentrated in the North Pacific using a trawl system for collection. Analysis of these plastics reveals several types present, including polyethylene and polyvinyl chloride. Plastics are not able to fully degrade into the marine environment; they break up into smaller pieces until they become microplastics. There the plastic can mistakenly become a food source and potentially enter the marine life food chain, leading to digestive issues that commonly result in starvation. Plastic could potentially be reused upon collection by converting it into forms that could be used for fuel. There are companies that can take a variety of “end of life” plastic and have it undergo the process of pyrolysis, where the plastic experiences an extremely high temperature in a closed system. This process essentially mimics the Earth’s natural process of creating fossil fuels. The resulting product can be used as fuel or processed further for other uses. Another way to recycle plastic aims to create new, usable plastic for manufacture by heating the old plastic and adding “virgin polymers” that will strengthen new plastic and form resin beads which can be used to manufacture new products. Another process that is common to dispose of waste like plastic is by incineration. However, like all of these possible solutions, more research needs to be done about the potentially harmful by-products that could be released through these processes.

Dopamine (DA) modulation is important in treating neurological disorders such as Parkinson's disease. Available methods fail to deliver DA into the brain due to its inability to cross the blood brain barrier (BBB). Attempts have been made to overcome this limitation, such as the development of L-DOPA. Despite its ability to cross the BBB, the pro-drug still causes many unwanted side effects. The demand for new DA delivery led to the development of my DA nanoprobe. This newly designed nanoprobe is modified to cross the BBB and can be safely uptake into the brain. The addition of a fluorophore allows for in vitro detection while the iron oxide core allows for in vivo real-time magnetic resonance (MR) imaging. The ability for the DA nanoprobe to cross the BBB and to be detected through optical/MR imaging provides new applications to many diagnostics and therapeutics of central nervous system disorder.

Tissue engineered skin is a candidate for skin therapies since detrimental wounds require replacement of both the epidermal and dermal layers. For successful replacements, it is important to mimic the skin structure consisting of two layers: a top epidermis layer with a dermis layer beneath, which is made up of keratinocytes and fibroblasts respectively. In the present study, we developed the skin graft by seeding the two types of skin cells, keratinocytes (HeCat) and fibroblasts (hFF), on opposite sides of a porous, biodegradable, and biocompatible 3D natural polymer-based scaffold. The skin graft was investigated by using Alamar Blue Assay, Histology, and SEM. The results showed that (1) the HeCat and hFF proliferated better in co-culture on the scaffold, (2) HeCat forms differentiate into 5 layers, compared with control. This infers that the 3D structure of the scaffold not only acts as a mechanically sufficient substrate for cells to grow and receive nutrients, but also creates a good environment for signaling between the two types of skin cells. These findings indicate that the integration of a natural polymer-based scaffold with co-cultured HeCat and hFF in vitro can be used for a living skin graft in vivo.

Conventional methods of biomolecular immobilization on metal surfaces entail surface functionalization by chemically prepared self-assembled monolayers (SAMs) conjugated with the desired biomolecules. Many such methods require multistep reactions under harsh environments, lack material selectivity, have low biomolecule coupling efficiencies, and often result in random-orientation during the adsorption of target biomolecules. Furthermore, the behavior and the stability of these synthetic molecules under physiologic conditions are still not well understood. During the last decade, bio-functionalization of surfaces using material binding peptides has been demonstrated to avoid such limitations. These peptide-based biomimetic approaches were demonstrated to functionalize surfaces on a variety of materials under aqueous environments. They offer a promising alternative to conventional chemical surface functionalization techniques, while providing the additional advantage of material specificity that chemical-based linkers lack. Further bioconjugation with functional biomolecules to the materials binding peptides provides the self-assembly of the conjugated product on the material surface in a single step. Here, we design a peptide exhibiting a strong binding affinity to gold substrates while immobilizing antibodies on the surfaces. Biocombinatorily selected gold-binding peptides (AuBPs) were conjugated to an antibody-binding domain (FcBP). The binding characteristics of the resulting constructs, i.e. AuBP-FcBPs, on gold substrates were evaluated using Surface Plasmon Resonance (SPR) spectroscopy. The coupling of different peptide functional domains into a single fused peptide has the risk of inducing structural changes in the resulting molecule due to intermolecular interactions. It is therefore critical to determine whether functionality of each region was maintained. The SPR experiments were carried out at different concentrations and resulted in Langmuir adsorption behavior, allowing the calculation of the binding constants. The resulting bi-functional bioprobe molecule can be employed in a wide range of diagnostic and therapeutic applications.

Chitin is the second most abundant polysaccharide extracted from the cuticles of insects and crustaceans. Chitin is known for its biocompatibility and superior mechanical strength. Silk fibroin is produced by the Bombyx mori silkworm and is known for its biocompatibility and superior toughness. Composites of chitin and silk fibroin would possess each biomaterial's unmatched mechanical strength and toughness, making them ideal candidates for biomedical applications requiring such mechanical properties. Here, squid pen β-chitin and Bombyx mori silkworm cocoon silk were blended in Hexafluoroisopropanol (HFIP) solution in specified ratios to synthesize the nanocomposites. As a result, chitin/silk hybrid nanocomposite thin films were produced to test the mechanical properties. Studies of both X-Ray Diffraction (XRD) and Fourier Transform-Infrared (FTIR) Spectroscopy revealed a successful effective interaction between the chitin nanofibers and the silk proteins matrix, which was most likely caused by hydrogen bonding. Results of the self-assembled chitin nanofibers embedded in the silk matrix showed a noticeable enhancement in mechanical properties. The tensile strength, flexibility, and toughness of the biomaterial nanocomposites were enhanced compared to just pure chitin or pure silk fibroin. Due to the improvement in mechanical properties, these chitin/silk engineered nanocomposites can be utilized in biomedical applications such as hybrid scaffolds for bone tissue engineering or microneedles to serve as a new methodology for drug delivery systems.