Theses and Dissertations from UMD
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Item Impact of Polymeric Drops on Drops and Films of a Different but Miscible Polymer(2024) Bera, Arka; Das, Siddhartha; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The fluid mechanics of a liquid drop impacting on another stationery (or spreading) liquid drop or on a liquid film (of thickness comparable, or smaller, or larger than the impacting drop) has attracted significant attention over the past several years. Such problems represent interesting deviations from the more widely studied problems of liquid drops impacting on solid surfaces having different wettabilities with respect to the impacting drops. These deviations stem from the fact that the resting liquid (in the form of the drop or the film) itself undergoes deformation on account of the drop impact and can significantly affect the overall combined drop-drop or drop-film dynamics. The problem becomes even more intriguing depending on the rheology of the drop(s) and the film as well as the (im)miscibility of the impacting drop with the underlying drop or the film. Interestingly, the majority of such drop-impact-on-drop or drop-impact-on-film studies have considered Newtonian drop(s) and films, with little attention to polymeric drop(s) and films. This thesis aims to bridge that void by studying, using Direct Numerical Simulation (DNS) based computational methods, the impact-driven dynamics of one polymeric drop on another (different but miscible) polymeric drop or film. As specific examples, we consider two separate problems. In the first problem, we consider the impact of a PMMA (poly-methyl methacrylate) drop on a resting PVAc (polyvinyl acetate) drop as well as the impact of a PVAc drop on a resting PMMA drop. In the second problem, we consider the impact of a PMMA drop on a PVAc film as well as the impact of a PVAc drop on a PMMA film. For the first problem, the wettability of the resting drop (on the resting surface), the Weber number of the impacting drop, the relative surface tension values of the two polymeric liquids (PVAc and PMMA), and the miscibility (or how fast the two liquids mix) dictate the overall dynamics. PVAc has a large wettability on silicon (considered as the underlying solid substrate); as a result, during the problem of the PMMA drop impacting on the PVAc drop, the PVAc drop spreads significantly and the slow mixing of the two liquids ensures that the PMMA drop spreads as a thin film on top of the PVAc film (formed as the PVAc drop spreads quickly on silicon). Depending on the Weber number, such a scenario leads to the formation of transient liquid films (of multitudes of shapes) with stratified layers of PMMA (on top) and PVAc (on bottom) liquids. On the other hand, for the case of the PVAc drop impacting on the PMMA drop, a combination of the weaker spreading of the PMMA drop on silicon and the “engulfing” of the PMMA drop by the PVAc drop (stemming from the PVAc having a smaller surface tension than PMMA) ensures that the impacting PVAc drop covers the entire PMMA drop and itself interacts with the substrate giving rise to highly intriguing transient and stratified multi-polymeric liquid-liquid structures (such as core-shell structure with PMMA core and PVAc shell). For both these cases, we thoroughly discuss the dynamics by studying the velocity field, the concentration profiles (characterizing the mixing), the progression of the mixing front, and the capillary waves (resulting from the impact-driven imposition of the disturbance). In the second problem, we consider a drop of the PMMA (PVAc) impacting on a film of the PVAc (PMMA). In addition to the factors dictating the previous problem, the film thickness (considered to be either identical or smaller than the drop diameter) also governs the overall droplet-impact-driven dynamics. Here, the impact, being on the film, the dynamics is governed by the formation of crown (signifying the pre-splashing stage) and a deep cavity (the depth of which is dictated by the film thickness) on the resting film. In addition to quantifying these facets, we further quantify the problem by studying the velocity and the concentration fields, the capillary waves, and the progression of the mixing front. For the PMMA drop impacting on the thin film, a noticeable effect is the quick thinning of the PMMA drop on the PVAc film (or the impact-driven cavity formed on the PVAc film), which gives rise to a situation similar to the previous study (development of transient multi-polymeric-liquid structures with stratified polymeric liquid layers). For the case of the PVAc drop impacting on the PMMA film, the PVAc liquid “engulfs” the deforming PMMA film, and this in turn, reduces the depth of the cavity formed, the extent of thinning, and the amplitude of the generated capillary waves. All these fascinating phenomena get captured through the detailed DNS results that are provided. The specific problems considered in this thesis have been motivated by the situations often experienced during the droplet-based 3D printing processes (e.g., Aerosol jet printing or inkjet printing). In such printing applications, it is commonplace to find one polymeric drop interacting with an already deposited polymeric drop or a polymeric film (e.g., through the co-deposition of multiple materials during multi-material printing). The scientific background for explaining these specific scenarios routinely encountered in 3D printing problems, unfortunately, has been very limited. Our study aims to fill this gap. Also, the prospect of rapidly solidifying these polymeric systems (via methods such as in-situ curing) can enable us to visualize the formation of solidified multi-polymeric structures of different shapes (by rapidly solidifying the different transient multi-polymeric-liquid structures described above). Specifically, both PMMA and PVAc are polymers well-known to be curable using in-situ ultraviolet curing, thereby establishing the case where the present thesis also raises the potential of developing PMMA-PVAc multi-polymeric solid structures of various shapes and morphologies.Item INVESTIGATION AND ENGINEERING OF HfZrO2 INTERFACES FOR FERROELECTRIC BASED NEUROMORPHIC DEVICES(2024) Pearson, Justin Seth; Takeuchi, Ichiro; Najmaei, Sina; Material Science and Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This dissertation describes the study of ferroelectric hafnium zirconium oxide (HZO) and its integration into ferroelectric field effect transistors (FeFET). Ferroelectric HZO is uniquely situated for energy efficient, non-volatile memory applications such as FeFETs due to its CMOS compatibility and ferroelectricity at scaled thicknesses less than 10 nm[1]. This work covers material growth of HZO via atomic layer deposition (ALD), as well as electrode metallization (W and Pt) via sputtering and electron beam physical vapor deposition, to optimize ferroelectricity in capacitive structures. Preliminary results show Pt-based devices were sufficient in producing ferroelectric HZO, but had issues in electrode degradation at high thermal processing > 450 °C. In contrast, HZO capacitors in W devices showed drastic improvement in the ferroelectric response reaching remnant polarization values > 40 μC/cm2. To integrate into a FET structure, gate dielectrics (Al2O3 and HfO2) and the 2D semiconductor tungsten diselenide (WSe2) are introduced to the HZO stack. Material and electrical characterization was performed and gave indication of challenges such as: low remnant polarization (<10 μC/cm2), surface roughness (> 20 nm), and high trap characteristics in FeFET modulation. Electrical characterization was performed via variable pulsing, high frequency cycling, current vs voltage, capacitance vs voltage, and polarization vs voltage testing. Challenges such as low remnant polarization, leaky dielectrics, and surface roughness are identified through transmission electron microscopy, atomic force microscopy, and electrical characterization. These challenges were addressed by altering the growth conditions, scaling the thickness of each material, and thermally processing within the bounds of material stability. Upon integration of these various materials into FETs, the challenges of reliability, stochasticity, and consistency were evaluated on through various means of electrically testing such as, variable pulsing, high frequency cycling, current vs voltage, capacitance vs voltage, and polarization vs voltage. A greater depth of understanding of fundamental aspects of these device architectures is required to untangle the complex electrical characteristics of the fabricated devices. Characterization of material properties is performed by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). Throughout the studies performed in this dissertation, the phase landscape of HZO was investigated on inert Ti/Pt electrodes. While the ferroelectric nature of the HZO was sufficiently explored at CMOS compatible temperatures, yielding remanent polarization values of 20 μC/cm2 and demonstrating multi state memory within Ferroelectric field effect devices (3.5 order of magnitude conductivity change), due to the phase landscape evolution under thermal processing. Higher temperatures were found to be incompatible with the electrode choice as the interdiffusion and breakdown resulted in poor device performance. W electrode HZO capacitors were then used to study the higher temperature ferroelectric devices as well as incorporate scaling of the ferroelectric films to better match the needs of modern device architectures. The optimal ferroelectric films were found to have remanent polarization values > 40 μC/cm2 and when implemented in a FEFET were able to demonstrate a memory window of 6.3 volts, allowing for a large range of modulation for neuromorphic devices.Item Insulating Materials for an Extreme Environment in a Supersonically Rotating Fusion Plasma(2024) Schwartz, Nick Raoul; Koeth, Timothy W; Material Science and Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Fusion energy has long been sought as the “holy grail” of energy sources. One of the most critical remaining challenges in fusion is that of plasma-facing materials, even denoted by the National Academies of Science. The materials challenge is particularly acute for centrifugal mirrors, an alternative concept to the industry-standard tokamak that may offer a more efficient scheme with a faster path to development. The centrifugal mirror incorporates supersonic rotation into a conventional magnetic mirror scheme, providing three primary benefits: (1) increased confinement, (2) suppression of instabilities, and (3) plasma heating through shear flow. However, this rotation, which is driven by an axial magnetic field and a radial electric field, requires the magnetic field lines to terminate on electrically insulating surfaces to avoid “shorting” the plasma. This unique requirement presents a novel materials challenge: the insulator must not only resist irradiation and thermal damage, but also be an excellent electrical insulator and thermal conductor that can be actively cooled. To address this materials challenge, the Centrifugal Mirror Fusion Experiment (CMFX) was developed at the University of Maryland. CMFX serves as a test bed for electrically insulating materials in a fusion environment, as well as a proof-of-concept for the centrifugal mirror scheme. To guide the design of future power plants and better understand the neutronand ion flux on the insulators, a zero-dimensional (0-D) scoping tool, called MCTrans++, was developed. This software, discussed in Chapter 2, demonstrates the ability to rapidly model experimental parameter sets in CMFX and predict the scaling to larger devices, informing material selection and design. Assuming the engineering challenges have been met, the centrifugal mirror has been demonstrated as a promising scheme for electricity production via fusion energy. One of the key aspects to the operation of CMFX is the high voltage system. This system, discussed in Chapter 3, was developed in incremental stages, beginning with a 20 kV, then 50 kV pulsed power configuration, and finally culminating in a 100 kV direct current power supply to drive rotation at much higher voltages, creating an extreme environment for materials testing. This work identified hexagonal boron nitride (hBN) as a promising insulator material. Computational modeling (Chapter 4) demonstrated hBN’s superior resistance to ion-irradiation damage compared to other plasma-facing materials. Additionally, fusion neutrons are crucial for assessing both material damage and power output. Chapter 5 details the neutronics for CMFX, including 3He proportional counters, which have been installed on CMFX to measure neutron production. In parallel, Monte Carlo computational methods were used to predict neutron transport and material damage in the experiment. Ultimately, a materials test stand was installed on CMFX to expose electrically insulating materials to high energy fusion plasmas (Chapter 6). Comparative analysis of hBN and silicon carbide after exposure revealed superior performance of hBN as a plasma-facing material. Two primary erosion mechanisms were identified by surface morphology and roughness measurements: grain ejection and sputtering, both more pronounced in silicon carbide. This work advances our understanding of insulating material behavior in fusion environments and paves the way for the development of the next-generation centrifugal mirror fusion reactors. Chapter 7 discusses conclusions and proposes future work. In particular this section suggests some changes that may allow CMFX to operate at much higher voltages, unlocking higher plasma density and temperature regimes for further material testing.Item Phonon Transport and Nonequilibrium Kinetics with Stimulation Modeling in Molecular Crystals(2024) Liu, Zhiyu; Chung, Peter W.; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)An important family of materials known as molecular crystals has been used extensively in fields such as organic semiconductors, energy, optoelectronics, and batteries. Due to their periodic crystal structure, phonons are the predominant heat and energy carriers. Phonons and their transport behaviors are crucial to the performance of semiconductors, the figure of merit of thermoelectrics, shock-induced properties of molecular crystals, and light-matter interactions of materials. Recent decades have seen significant advancements in the understanding of the phonon transport behaviors in inorganic crystals. However, a comprehensive understanding of phonon properties in molecular crystals is still lacking. While various theoretical models and computational simulations have been developed to study vibrational energy transfer in molecular crystals and to correlate vibrational structure with the stability of materials, these approaches often suffer from limitations. Many of these studies either neglect anharmonic scattering entirely or rely on simplified representations of phonon scattering. In this dissertation, we focus on investigating the phonon transport and nonequilibrium kinetics in molecular crystals. In the first work, we study the harmonic phonon properties of cellulose Iβ using tapered reactive force fields (ReaxFF). While geometry optimization with the original ReaxFF potential often results in structures with negative eigenvalues, indicating structural instability, the modified potential with a tapering function yields structures with no associated negative eigenvalues. Three ReaxFF parameterizations are evaluated by comparing lattice properties, elastic constants, phonon dispersion, temperature-dependent entropy, and heat capacity with experimental results from the literature. In the second study, we study the phonon transport behavior of Si, Cs2PbI2Cl2, cellulose Iβ, and α-RDX by calculating the thermal conductivity using different thermal transport models including the Phonon gas model, Cahill-Watson-Pohl, and the Allen-Feldman model and the Wigner formulation. By comparing the calculated thermal conductivity with experimental values, we highlight the significant contributions of wave-like heat carriers in cellulose Iβ and α-RDX. We show how different phonon properties influence particle-like and wave-like behavior in various materials and reveal unusual mechanisms present in molecular crystals. Lastly, we investigate nonequilibrium phonon kinetics resulting from direct vibrational excitations by employing the phonon Boltzmann transport equations. The results of our mid-IR pump-probe spectroscopy simulations align closely with experimental data from the literature. Additionally, by exciting different phonon modes at varying frequencies, we uncover distinct stages and pathways of vibrational energy transfer. To gain insights into the decomposition mechanism of RDX under excitation, we further calculate the bond activities of the N-N and N-O bonds, identifying possible stimuli that could trigger bond cleavage.Item HIGH-THROUGHPUT COMBINATORIAL EXPLORATION OF QUANTUM MATERIALS AND DEVICES FOR SPINTRONIC AND TOPOLOGICAL COMPUTING APPLICATIONS(2024) Park, Jihun; Takeuchi, Ichiro; Material Science and Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)This doctoral dissertation aims to explore via high-throughput methodologies heavy-element-based quantum materials and devices for spintronic and topological computing applications. It is organized into three parts: (1) the development of spin wave devices based on magnetic insulators for magnon spintronics, (2) the search for spin-triplet superconductors based on Bi alloys (Bi–Ni and Bi–Pd) for superconducting spintronics, and (3) fabricating Josephson junctions based on topological insulators for topological quantum computing.The first part of this dissertation is to develop spin wave devices based on acoustically driven ferromagnetic resonance (ADFMR) using magnetic materials, including yttrium iron garnet (YIG). Spintronic devices based on ferromagnetic metals entail Joule heating and energy loss due to the moving of charge carriers. On the other hand, spin waves can be used without resistive losses. ADFMR is an efficient platform for generating and detecting spin waves via magneto-elastic coupling. While numerous ADFMR studies in ferromagnetic metals have been reported, there is no such report on magnetic insulators. This is due to (1) thermal degradation of piezoelectric substrates (e.g., LiNbO3) during the film crystallization (T > 800°C for YIG), (2) reaction between substrate and film materials, and (3) low ADFMR signals due to intrinsically low magnetostriction. The first part of this thesis attempts to address these issues to achieve YIG ADFMR devices by utilizing rapid thermal annealing to minimize thermal damage, a SiO2 buffer layer to avoid unwanted chemical reactions during crystallization, and a time-gating method for enhanced signal-to-noise ratio. YIG thin films deposited via pulsed laser deposition and crystallized by rapid thermal annealing show decent ferromagnetic behavior. YIG devices show exotic angle- and field-dependent absorption features, indicative of ADFMR. The observed ADFMR pattern is consistent with simulations. This result indicates the first demonstration of ADFMR in magnetic insulators. The second part of this work performs combinatorial synthesis of Bi–Ni and Bi–Pd alloys, which possibly show spin-triplet superconductivity. Such spin-triplet Cooper pairing would allow field-controllable spin polarization in superconductors, enabling superconducting spintronic applications. Furthermore, this type of device possibly provides evidence of superconducting pairing symmetries. In Bi–Ni spread study, Bi3Ni acts as a superconducting host material, where the superconductivity is identified to be varied according to two competing mechanisms: carrier doping and impurity scattering. These results can provide useful guidance in studying superconducting materials with stoichiometric defects. In the Bi–Pd spread films, two superconducting phases are identified with maximum Tc of 3.1 and 3.7 K, corresponding to BiPd and Bi2Pd phases, respectively. With Bi2Pd thin films, spin injection devices are fabricated and characterized. The Bi2Pd spin injection device showed unusual pair-breaking behavior where the superconductivity of Bi2Pd is destroyed significantly by unpolarized current injection. These superconducting spintronic studies demonstrate prompt device exploration via combinatorial methods, efficiently providing insight into spin-triplet superconductivity and its applications. Lastly, this dissertation aims to fabricate topological Josephson junctions based on Yb6/SmB6/Yb6 trilayers. SmB6 is a topological insulator characterized by a robust insulating bulk state and topological surface states. Superconducting proximity effects on the topological surface states can generate topological superconductivity, which can be utilized for fault-tolerant topological quantum computing. This dissertation addresses challenges in fabricating topological Josephson devices. With statistical analysis, device failure mechanisms are identified and addressed, allowing for improved design and fabrication. The improved devices showed Josephson junction-like behavior. The junction characterization revealed that 100% of measured samples showed Josephson features with prominent statistical reproducibility, possibly induced by the Klein effect. The dependence of SmB6 dimensions on the junction behavior is also investigated, along with possible proposed scenarios. These results demonstrate that the combinatorial approaches allow for efficient and prompt investigation of novel quantum materials and devices, facilitating phase diagram studies, materials screening, and stoichiometric controls.Item NOVEL GRAPHENE HETEROSTRUCTURES FOR SENSITIVE ENVIRONMENTAL AND BIOLOGICAL SENSING(2024) Pedowitz, Michael Donald; Daniels, Kevin; Electrical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The COVID-19 pandemic has underscored the need for rapid, mobile, and adaptable sensing platforms to respond swiftly to pandemic-level emergencies. Additionally, smog and volatile organic compounds (VOCs), which posed significant health risks during last year’s wildfires, highlight the critical need for environmental air quality monitoring. Graphene, with its high sensitivity and fast response times, shows promise as a powerful sensing platform. However, it faces challenges related to low selectivity and the complexities of device fabrication using conventional chemical vapor-deposited graphene grown on metal foil, which requires exfoliation and transfer to suitable substrates.This dissertation explores the use of epitaxial graphene, which is graphene grown from the sublimation of silicon from silicon carbide, and forming heterostructures with legacy functional materials, such as transition metal oxides and selective capture probes like antibodies and aptamers to develop rapid, ultrasensitive, and selective sensors to address critical environmental and public health challenges. Epitaxial graphene provides a single-crystal, lithography-compatible graphene substrate that retains the desirable electronic properties of graphene without the drawbacks associated with transferred materials. This work focuses on creating heterostructures using traditional functional materials, such as manganese dioxide and antibodies, to develop high-quality, selective sensors for both biological and environmental applications. The practical applications of these sensors are demonstrated and validated using techniques such as Raman spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy, scanning electron microscopy, and electrical characterization. Additionally, detailed material analysis on producing these heterostructures is provided, emphasizing their ability to be modified without damaging the underlying graphene surface. This highlights epitaxial graphene's robust and versatile nature and its potential for creating high-quality devices with relatively simple designs. Finally, these biosensors are applied to alternate antibody-antigen systems, including influenza, to enhance disease-tracking capabilities. We also explore advanced functional materials, such as protease-peptide systems, which enable the creation of on-chip chemistry systems previously unattainable with current material systems.Item Scalable Rapid Fabrication of Low-Cost, High-Performance, Sustainable Thermal Insulation Foam for Building Energy Efficiency(2024) Siciliano, Amanda Pia; Hu, Liangbing; Material Science and Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Bio-based thermal insulation materials offer a promising path towards energy savings in the buildings sector. However, these materials face competitiveness challenges against conventional petroleum-based alternatives due to issues with inferior insulation performance, poor compressive strength, and limited manufacturing scalability. Various fabrication methods such as freeze drying, thermal bonding, and chemical treatment have been proposed to enhance the material’s internal structure by introducing additional pores, creating a more complex path for heat transfer, and improving insulation efficiency. Despite advancements, the manufacturing scalability of these methods and their integration into industrial production remain unachieved.This thesis aims to bridge the gap between laboratory experiments and large-scale production by developing low-cost, sustainable cellulose-based thermal insulation. By investigating both aqueous and non-aqueous-based processing strategies, this work proposes several different fabrication techniques, leading to significant savings in energy, time, and cost. Establishing a comprehensive understanding of the interactions among the fabrication process, insulation foam, manufacturing scalability, and intended product application is imperative. This understanding accounts for variations in processing parameters (e.g., pretreatments, binders, temperature, time) and their impact on the insulation foam’s internal structure and overall performance. By examining the relationship between processing parameters and material structure, this thesis not only advances the fundamental understanding necessary for optimizing fabrication but also provides strategic guidance for selecting and designing scalable bio-based thermal insulation foams. Studying and characterizing commercially viable methods that seamlessly integrate with current industrial infrastructures is crucial for facilitating the transition from small-scale laboratory experimentation to large-scale industrial production. Through various technical strategies, this work illustrates how our understanding can be utilized to offer direction for fabrication method selection, design, and processing, ultimately optimizing the scalable rapid fabrication of low-cost, high-performance sustainable thermal insulation materials for building energy efficiency.Item INTERFACES IN THIN-FILM SOLID-STATE BATTERIES(2024) Castagna Ferrari, Victoria; Rubloff, Gary GWR; Material Science and Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The lack of a diagnostics approach to monitor interface kinetics in solid-state batteries (SSBs) results in an incomplete knowledge of the mechanisms affecting device performance. In this study, a new protocol for process control of SSB interface formation and their evolution during operation is presented. Thin-film SSBs and diagnostic test devices that are composed by a permutation of isolated layers were simultaneously fabricated using sequential sputtering deposition and in-situ patterning using shadow masks. Physics-based electric circuit models were designed for deconvolution of impedance profiles, which enabled an evaluation of bulk properties and space-charge layers at interfaces individually and during operation under different states-of-charge. Relative permittivity values of fundamental battery components (cathode, electrolyte and anode) were calculated as a function of the frequency and the applied voltage. Interfacial impedances, as well as space-charge layers formed at heterojunctions during charge and discharge processes, were successfully deconvoluted using the diagnostic test devices and electric circuit modeling. The cathode-electrolyte interphase was kinetically stable under a voltage window of 0 – 3.6 V vs Cu, and it had an estimated ionic conductivity of the order of 10-9 S/cm, hence it is a localized limiting factor for Li+ transfer. The anode-electrolyte interphase was thermodynamically stable upon completion of the fabrication process, but it became kinetically unstable during charge and discharge cycles. Hence, the proposed diagnostics protocol enlightened the necessity of implementing interfacial engineering on these interphases in the future for improvement of cyclability and stability of SSBs and ionic devices.Item BLANKET AND PATTERNED REPROGRAMMING OF AZOPOLYMER NANORIDGES AND APPLICATIONS TO CELLULAR BIOPHYSICS(2024) Abostate, Mona Hamdy Abdelrahman; Fourkas, John J; Chemistry; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The objective of this project is to tailor nanotopographies previously fabricated on large areas through photomodification. The original master patterns consist of nanoridges created using conventional lithography. Using an azopolymer as a photoresponsive material, replicas of the original master were prepared using soft lithography. The entire surface of the azopolymer nanoridges underwent photomodification using a 532 nm laser with varying polarizations and durations, in a process referred to as blanket reprogramming. This process resulted in controllable widening, buckling, or removal of the nanoridges due to photoisomerization and subsequent mass migration of the azopolymer. To replicate the reprogrammed surfaces, a molding procedure was employed using an acrylatic resin. The blanket reprogramming process was monitored in situ during exposure through diffraction of another reading laser beam. Cellular behaviors can be modulated in various biological contexts through interactions with their surroundings. The relationship between nanotopography and cell behavior is crucial, and has a wide range of biological consequences and medical applications. For example, nanotopography is employed to design antibacterial surfaces, preventing the adhesion of bacteria and biofilm formation, thereby reducing the risk of infections associated with medical devices. Nanostructured surfaces can inhibit the migration of cancer cells, offering insights into potential therapeutic strategies. Nanotopography is also used in nerve-regeneration scaffolds to guide neurite outgrowth, aiding in the repair of damaged neural tissue. We investigated the response of MCF10A breast epithelial cells to buckled acrylic nanoridges replicated from a master of azopolymer ridges photomodified by laser. The nanoridges became buckled after exposure to 532 nm light polarized parallel to the ridges. The impact of buckling on the dynamics and location of actin polymerization was investigated, as well as the distribution of lengths of contiguous polymerized regions. Azopolymers, known for their biocompatibility, have been employed by various research groups to create nanotopographies on which cells are plated and imaged. We conducted experiments using a spinning-disk confocal fluorescence microscope, testing exposure wavelengths ranging from 405 nm to 640 nm. Our objective was to assess the feasibility of live-cell imaging on azopolymer nanotopographies without inducing surface alterations. Our findings revealed the capability of live-cell imaging at high frame rates across a wide range of wavelengths. This result stands in contrast to prior studies, in which the selection of fluorescent dyes compatible with these materials was limited to those excited in the red spectrum and emitting in the near-infrared. I demonstrate that different patterns can be created through patterned reprogramming of the azopolymer nanoridges. A periodic arrangement of light strips was projected perpendicular to the ridges, thereby projecting an amplitude grating onto the azopolymer nanoridges. The spacing of this pattern can be adjusted by altering the mask or adjusting the magnification of the optical system. Furthermore, varying the direction of light polarization expands the potential for creating a wider variety of designs. Different types of reprogramming motifs can be implemented by projecting patterns at angles that are not perpendicular to the substrate, by tilting the incoming laser beam away from the horizontal. Various intriguing patterns, such as repeating curves, were observed, dependent on both the angle of the incident light and the direction of light polarization relative to the direction of the ridges.Item ELECTROLYTE AND INTERFACE DESIGNATION FOR HIGH-PERFORMANCE SOLID-STATE LITHIUM METAL BATTERIES(2024) Zhang, Weiran; Wang, Chunsheng; Material Science and Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The demand for advanced battery technology is intensifying as electric energy becomes the foundation of modern technologies, such as smart devices, transportation, and artificial intelligence. Batteries play a crucial role in meeting our increasing energy demands and transitioning towards cleaner and more sustainable energy sources. However, range anxiety and safety concerns still hinder the widespread application of battery technology.Current Li-ion batteries, based on graphite anode, have revolutionized battery technology but are nearing the energy density limits. This necessitates the development of metal batteries, employing lithium metal as anode which eliminates host materials that do not contribute to capacity, thereby offering 10 times higher specific capacity. Recent research on lithium metal batteries has seen a significant surge, with growing knowledge transitioning from Li+ intercalation chemistry (graphite) to Li metal plating/stripping. The electrolyte, which was previously regarded as an inert material and acting as a Li+ ion transportation mediator, has gradually attracted researchers’ attention due to its significant impact on the solid electrolyte interphase (SEI) and the Li metal plating/stripping behaviors. Compared to the traditional liquid electrolytes, solid-state lithium metal batteries (SSLMB) have been regarded as the holy grail, the future of electric vehicles (EVs), due to their high safety and potential for higher energy density. However, there are notable knowledge gaps between liquid electrolytes and solid-state electrolytes (SSEs). The transition from liquid-solid contact to solid-solid contact poses new challenges to the SSLMB. As a result, the development of SSLMB is strongly hindered by interface challenges, including not only the Li/SSE interfaces and SSE/cathode interfaces but also SSE/SSE interfaces. In this dissertation, I detailed our efforts to highlight the role of electrolytes and interfaces and establish our understanding and fundamental criteria for them. Building on this understanding, we propose effective and facile engineering solutions that significantly enhance batterie metrics to meet real-world application demand. Rather than simply introducing new compositions or new designations, we are dedicated to introducing our understanding and mechanism behind it, we hope the scientific understanding, the practical solution, and the applicability to various systems can further guide and inspire the electrolyte and interface designation for next-generation battery technology.