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Articles 1 - 27 of 27
Full-Text Articles in Nanoscience and Nanotechnology
Enabling Nanoimprint Lithography Techniques Across Multiple Manufacturing Processes, Vincent Einck
Enabling Nanoimprint Lithography Techniques Across Multiple Manufacturing Processes, Vincent Einck
Doctoral Dissertations
Advanced nanooptics in the areas of flat lenses, diffractive elements, and tunable emissivity require a route to high throughput manufacturing. Nanooptics are often demanding of high refractive index materials, nanometer precision and ease of fabrication. Nanoimprint lithography (NIL) is a low-cost, high throughput manufacturing technique beginning to be realized in commercial industry.1,2 The NIL process is an ideal manufacturing candidate due to its ability to have a fast process time, efficient use of materials, repeatability and high precision while also having wide diversity of potential structures and material choices. Appling NIL techniques to other facets of manufacturing enable the …
Thermoelectric Transport In Disordered Organic And Inorganic Semiconductors, Meenakshi Upadhyaya
Thermoelectric Transport In Disordered Organic And Inorganic Semiconductors, Meenakshi Upadhyaya
Doctoral Dissertations
The need for alternative energy sources has led to extensive research on optimizing the conversion efficiency of thermoelectric (TE) materials. TE efficiency is governed by figure-of-merit (ZT) and it has been an enormously challenging task to increase ZT > 1 despite decades of research due to the interdependence of material properties. Most doped inorganic semiconductors have a high electrical conductivity and moderate Seebeck coefficient, but ZT is still limited by their high lattice thermal conductivity. One approach to address this problem is to decrease thermal conductivity by means of alloying and nanostructuring, another is to consider materials with an inherently low …
Nano- And Micro-Structured Temperature-Sensitive Hydrogels For Rapidly Responsive Devices, Qi Lu
Nano- And Micro-Structured Temperature-Sensitive Hydrogels For Rapidly Responsive Devices, Qi Lu
Doctoral Dissertations
This thesis aims to extend the understanding and explore the application of temperature-responsive hydrogel systems by integrating microelectromechanical systems (MEMS). Stimuli-responsive hydrogel systems are immensely investigated and applied in numerous fields, and interfacing with micro- and nano-fabrication techniques will open up more possibilities. In Chapter 2, the first biologically relevant, in vitro cell stretching device based on hydrogel surface instability was developed. This dynamic platform is constructed by embedding micro-heater devices under temperature-responsive surface-attached hydrogels. The fast and regional temperature change actuates the stretching and relaxation of the seeded human artery smooth muscle cell (HASMC) via controllable surface creasing instability. …
Resistive Switching Characteristics Of Nanostructured And Solution-Processed Complex Oxide Assemblies, Zimu Zhou
Doctoral Dissertations
Miniaturization of conventional nonvolatile (NVM) memory devices is rapidly approaching the physical limitations of the constituent materials. An emerging random access memory (RAM), nanoscale resistive RAM (RRAM), has the potential to replace conventional nonvolatile memory and could foster novel type of computing due to its fast switching speed, high scalability, and low power consumption. RRAM, or memristors, represent a class of two terminal devices comprising an insulating layer, such as a metal oxide, sandwiched between two terminal electrodes that exhibits two or more distinct resistance states that depend on the history of the applied bias. While the sudden resistance reduction …
Engineered Nanoparticles For Site-Specific Bioorthogonal Catalysis: Imaging And Therapy, Riddha Das
Engineered Nanoparticles For Site-Specific Bioorthogonal Catalysis: Imaging And Therapy, Riddha Das
Doctoral Dissertations
Bioorthogonal catalysis offers a strategy for chemical transformations complementary to bioprocesses and has proven to be a powerful tool in biochemistry and medical sciences. Transition metal catalysts (TMCs) have emerged as a powerful tool to execute selective chemical transformations, however, lack of biocompatibility and stability limits their use in biological applications. Incorporation of TMCs into nanoparticle monolayers provides a versatile strategy for the generation of bioorthogonal nanocatalysts known as “nanozymes”. We have fabricated a family of nanozymes using gold nanoparticles (AuNPs) as scaffolds featuring diverse chemical functional groups for controlled localization of nanozymes in biological environments, providing unique strategies for …
Top-Down And Bottom-Up Fabrication Of Key Components In Miniature Energy Storage Devices, Wenhao Li
Top-Down And Bottom-Up Fabrication Of Key Components In Miniature Energy Storage Devices, Wenhao Li
Doctoral Dissertations
The advent of miniature electronic devices demands power sources of commensurate form factors. This spurs the research of micro energy storage devices, e.g., 3D microbatteries. A 3D microbattery contains nonplanar microelectrodes with high aspect ratio and high surface area, separated by a nanoscale electrolyte. The device takes up a total volume as small as 10 mm3, allowing it to serve on a chip and to provide power in-situ. The marriage of nanotechnology and electrochemical energy storage makes microbattery research a fascinating field with both scientific excitement and application prospect. However, successful fabrication of well-functioned key components …
Bioinspired Complex Nanoarchitectures By Dna Supramolecular Polymerization, Laura A. Lanier
Bioinspired Complex Nanoarchitectures By Dna Supramolecular Polymerization, Laura A. Lanier
Doctoral Dissertations
Bioinspired nanoarchitectures are of great interest for applications in fields such as nanomedicine, tissue engineering, and biosensing. With this interest, understanding how the physical properties of these complex nanostructures relate to their function is increasingly important. This dissertation describes the creation of complex nanoarchitectures with controlled structure and the investigation of the effect of nanocarrier physical properties on cell uptake for applications in nanomedicine. DNA self-assembly by supramolecular polymerization was chosen to create complex nanostructures of controlled architectures. We demonstrated that the supramolecular polymerization of DNA known as hybridization chain reaction (HCR) is in fact a living polymerization. The living …
Engineering Nanomaterials For Imaging And Therapy Of Bacteria And Biofilm-Associated Infections, Akash Gupta
Engineering Nanomaterials For Imaging And Therapy Of Bacteria And Biofilm-Associated Infections, Akash Gupta
Doctoral Dissertations
Infections caused by multidrug-resistant (MDR) bacteria pose a serious global burden of mortality, causing thousands of deaths each year. The “superbug” risk is further exacerbated by chronic infections generated from antibiotic-resistant biofilms that are highly resistant to available treatments. Synthetic macromolecules such as polymers and nanoparticles have emerged as promising antimicrobials. Moreover, ability to modulate nanomaterial interaction with bacterial cellular systems plays a pivotal role in improving the efficacy of the strategy. In the initial studies on engineering nanoparticle surface chemistry, I investigated the role played by surface ligands in determining the antimicrobial activity of the nanoparticles. In further study, …
Rheological Investigations Of Self-Assembled Block Copolymer Nanocomposites With Complex Architectures, Benjamin Yavitt
Rheological Investigations Of Self-Assembled Block Copolymer Nanocomposites With Complex Architectures, Benjamin Yavitt
Doctoral Dissertations
The self-assembly of block copolymers (BCP) into microphase separated structures is an attractive route to template and assemble functional nanoparticles (NP) into highly ordered nanocomposites and is central to the “bottom up” fabrication of future materials with tunable electronic, optical, magnetic, and mechanical properties. The optimization of the co-assembly requires an understanding of the fundamentals of phase behavior, intermolecular interactions and dynamics of the polymeric structure. Rheology is a novel characterization tool to investigate these processes in such systems that are not accessible by other means. With the combination of X-ray scattering techniques, structure-property relationships are determined as a function …
Probing Quantized Excitations And Many-Body Correlations In Transition Metal Dichalcogenides With Optical Spectroscopy, Shao-Yu Chen
Probing Quantized Excitations And Many-Body Correlations In Transition Metal Dichalcogenides With Optical Spectroscopy, Shao-Yu Chen
Doctoral Dissertations
Layered transition metal dichalcogenides (TMDCs) have attracted great interests in recent years due to their physical properties manifested in different polytypes: Hexagonal(H)-TMDC,which is semiconducting, exhibits strong Coulomb interaction and intriguing valleytronic properties; distorted octahedral(T’)-TMDC,which is semi-metallic, is predicted to exhibit rich nontrivial topological physics. In this dissertation,we employ the polarization-resolved micron-Raman/PL spectroscopy to investigate the optical properties of the atomic layer of several polytypes of TMDC. In the first part for polarization-resolved Raman spectroscopy, we study the lattice vibration of both H and T’-TMDC, providing a thorough understanding of the polymorphism of TMDCs. We demonstrate that Raman spectroscopy is a …
Development Of Functional Biomaterials Using Protein Building Blocks, Li-Sheng Wang
Development Of Functional Biomaterials Using Protein Building Blocks, Li-Sheng Wang
Doctoral Dissertations
Proteins have intrinsic molecular properties that are highly useful for materials applications, especially for biomaterials. My research has focused on translating these molecular properties to materials surface behavior. In one approach, I developed a fluorous-based thermal treatment strategy to generate stable thin films from a variety of naturally abundant proteins. The different surface properties generated from the choice of protein were utilized to modulate cell-surface interactions, prevent bacterial adhesions, and control drug loading/release. I have used nanoimprint lithography to generate patterned protein films for cell alignment. Coupling with inkjet printing deposition, I have fabricated mixed protein films with spatial and …
Direct Patterning Of Nature-Inspired Surfaces For Biointerfacial Applications, Feyza Dundar
Direct Patterning Of Nature-Inspired Surfaces For Biointerfacial Applications, Feyza Dundar
Doctoral Dissertations
There are three major challenges for the design of patterned surfaces for biointerfacial applications: (i) durability of antibacterial/antifouling mechanisms, (ii) mechanical durability, and (iii) lifetime of the master mold for mass production of patterned surfaces. In this dissertation, we describe our contribution for the development of each of these challenges. The bioinspired surface, Sharklet AFTM, has been shown to reduce bacterial attachment via a biocide-free structure-property relationship effectively. Unfortunately, the effectiveness of polymer-based sharkskin surfaces is challenged over the long term by both eventual bacteria accumulation and a lack of mechanical durability. To address these common modes of …
Probing Local Vacancy-Driven Resistive Switching In Metal Oxide Nanostructures, Jiaying Wang
Probing Local Vacancy-Driven Resistive Switching In Metal Oxide Nanostructures, Jiaying Wang
Doctoral Dissertations
Novel nonvolatile memory technologies garner intense research interest as conventional ash devices approach their physical limit. Memristors, often comprising an insulating thin film between two metal electrodes to constitute a class of two-terminal devices, enable a variety of important large data storage and data-driven computing applications. In addition to nonvolatile behavior, other features such as high scalability, low power consumption, and sub-nanosecond response times make memristors among the most attractive candidate systems. Their strength in electronic storage relies on the unique properties of the tunable variations in resistance induced from the accumulation of charged defects based on the applied bias …
Parallel Algorithms For Time Dependent Density Functional Theory In Real-Space And Real-Time, James Kestyn
Parallel Algorithms For Time Dependent Density Functional Theory In Real-Space And Real-Time, James Kestyn
Doctoral Dissertations
Density functional theory (DFT) and time dependent density functional theory (TDDFT) have had great success solving for ground state and excited states properties of molecules, solids and nanostructures. However, these problems are particularly hard to scale. Both the size of the discrete system and the number of needed eigenstates increase with the number of electrons. A complete parallel framework for DFT and TDDFT calculations applied to molecules and nanostructures is presented in this dissertation. This includes the development of custom numerical algorithms for eigenvalue problems and linear systems. New functionality in the FEAST eigenvalue solver presents an additional level of …
Role Of Rigidity And Flexibility Of Functional Groups Within The Interior Of Supramolecular Assemblies And Their Implications, Oyuntuya Munkhbat
Role Of Rigidity And Flexibility Of Functional Groups Within The Interior Of Supramolecular Assemblies And Their Implications, Oyuntuya Munkhbat
Doctoral Dissertations
Engineering of supramolecular assemblies at molecular level renders functional nanomaterials that present explicit response to certain environmental changes. Systematic structure-property correlation studies will unravel the fundamental design constraints of these functional nanomaterials that fulfill the emergent need. This dissertation will primarily focus on understanding the role of rigidity and flexibility of functional groups within amphiphilic assemblies and employing this basic concept in drug delivery and diagnostics applications. Supramolecular assemblies formed by amphiphilic dendrimers and polymers are preferred for this study as they exhibit high thermodynamic stability and structural flexibility. The role of aromatic interaction on the unimer-aggregate dynamic equilibrium was …
The Rheology And Roll-To-Roll Processing Of Shear-Thickening Particle Dispersions, Sunilkumar Khandavalli
The Rheology And Roll-To-Roll Processing Of Shear-Thickening Particle Dispersions, Sunilkumar Khandavalli
Doctoral Dissertations
Particle dispersions are ubiquitous in our daily lives ranging from food and pharmaceutical products to inks. There has been great interest in the recent years in formulation of functional inks to fabricate myriad flexible electronic devices through high-throughput roll-to-roll technologies. The formulations often contain several functional additives or rheological modifiers that can affect the microstructure, rheology and processing. Understanding the rheology of formulations is important for tuning the formulation for optimal processing. This thesis presents investigations on the rheology of particle dispersions and their impact on roll-to-roll technologies. Shear-thickening behavior is common in particle dispersions, particularly, concentrated particulate inks. We …
Solution-Based Assembly Of Conjugated Polymers Into Nanofibers For Organic Electronics, Daniel E. Acevedo Cartagena
Solution-Based Assembly Of Conjugated Polymers Into Nanofibers For Organic Electronics, Daniel E. Acevedo Cartagena
Doctoral Dissertations
Solution-based crystallization of conjugated polymers offers a scalable and attractive route to develop hierarchical structures for electronic devices. The introduction of well-defined nucleation sites into metastable solutions provides a way to regulate the crystallization behavior, and therefore the morphology of the material. A crystallization method for generating metastable solutions of poly(3-hexylthiophene) (P3HT) was established. These metastable solutions allow P3HT to selectively crystallize into nanofibers (NFs) on graphene-coated surfaces. It was found that the crystallization kinetics is faster with increasing P3HT molecular weight and concentration. Through in situ atomic force microscopy, it was confirmed that NFs grow vertically in a face-on …
Guiding The Self-Assembly Of Block Copolymers In 2d And 3d With Minimal Patterning, Jaewon Choi
Guiding The Self-Assembly Of Block Copolymers In 2d And 3d With Minimal Patterning, Jaewon Choi
Doctoral Dissertations
Directed self-assembly (DSA) of block copolymers (BCPs) based on topographic patterns is one of the most promising strategies for overcoming resolution limitations in the current lithographic process and fabricating the next generation data storage devices. While the DSA of BCPs with deep topographic patterning has been extensively studied both experimentally and theoretically over the past two decades, less attention has been paid to the development of the DSA process using minimal topographic patterning. This dissertation focuses on understanding the effect of minimal topographic patterning on guiding the self-assembly of BCPs in 2D and 3D. We demonstrate that minimal trench patterns …
Morphological And Material Effects In Van Der Waals Interactions, Jaime C. Hopkins
Morphological And Material Effects In Van Der Waals Interactions, Jaime C. Hopkins
Doctoral Dissertations
Van der Waals (vdW) interactions influence a variety of mesoscale phenomena, such as surface adhesion, friction, and colloid stability, and play increasingly important roles as science seeks to design systems on increasingly smaller length scales. Using the full Lifshitz continuum formulation, this thesis investigates the effects of system materials, shapes, and configurations and presents open-source software to accurately calculate vdW interactions. In the Lifshitz formulation, the microscopic composition of a material is represented by its bulk dielectric response. Small changes in a dielectric response can result in substantial variations in the strength of vdW interactions. However, the relationship between these …
Enzyme Stabilization In Hierarchical Biocatalytic Food Packaging And Processing Materials, Dana Erin Wong
Enzyme Stabilization In Hierarchical Biocatalytic Food Packaging And Processing Materials, Dana Erin Wong
Doctoral Dissertations
The partnership of biocatalysts and solid support materials provides many opportunities for bioactive packaging and bioprocessing aids beneficial to the agricultural and food industries. Biocatalysis, or reactions modulated by enzymes, allows bioactive materials to assist in bringing a substrate to product. Enzymes are proteins which catalyze reactions by lowering the activation energy required to drive the production of a desired product. Enzymes are commonly utilized in food processing as catalysts with specificity in order to enhance product quality through the production of beneficial food components, and to break down undesirable components that may be harmful or may decrease product quality. …
Refractive Index Engineering And Optical Properties Enhancement By Polymer Nanocomposites, Cheng Li
Refractive Index Engineering And Optical Properties Enhancement By Polymer Nanocomposites, Cheng Li
Doctoral Dissertations
The major part of this dissertation discusses the engineering of the refractive index of materials using solution-processable polymer nanocomposites and their applications in building optical components and devices. Three particular polymer nanocomposites have been introduced to achieve materials with tunable refractive indices and enhanced optical properties, which can be used to manipulate the behavior of light or electromagnetic radiations. In the first system, polyhedral oligomeric silsesquioxane (POSS)/polymer nanocomposites are developed. Thin films with tunable, low refractive indicies were fabricated from the composites. The mechanical strength of these films was characterized, and their application in antireflective coatings is discussed. In the …
(I) Polymer Nanocomposites: Rheology And Processing For Mesoporous Materials And (Ii) Nanopatterning Of Metal Oxides Using Soft Lithography, Rohit Kothari
Doctoral Dissertations
The research in this dissertation is categorized into two parts. The first part is focused on investigation of order-to-disorder transitions (ODT) in nanocomposites of an amphiphilic block copolymer containing various hydrogen-bonded additives, and fabrication of novel mesoporous silica based materials by utilizing such nanocomposites as templates. Disordered Pluronic®, poly(ethylene oxide) (PEO)−poly(propylene oxide) (PPO)−PEO triblock copolymer upon blending with small molecule additives containing hydrogen-bond-donating functional groups (carboxyl or hydroxyl) result into ordered nanoscale morphologies by preferentially interacting with the hydrophilic PEO chains in the Pluronic®. The dependence of ODT-temperature in these novel Pluronic®/small-molecule-additive complexes on composition, number and type of functional …
Tunable Photonic Multilayers From Stimulus-Responsive, Photo-Crosslinkable Polymers, Maria C. Chiappelli
Tunable Photonic Multilayers From Stimulus-Responsive, Photo-Crosslinkable Polymers, Maria C. Chiappelli
Doctoral Dissertations
This dissertation describes the synthesis of photo-crosslinkable copolymers and their utilization for the fabrication and testing of tunable and responsive one-dimensional (1D) photonic multilayers. Photonic multilayers exhibit structural color due to the interference of incident light at layer interfaces, providing a convenient route towards optically responsive materials that do not rely on potentially light- or oxygen-sensitive chromophore-containing pigments and dyes. A fabrication technique based on sequential spin-coating and crosslinking of photo-crosslinkable polymers is used to assemble tunable and responsive photonic multilayers. Chapter One introduces the fundamental underlying principles of 1D photonic structures and explores their importance in a variety of …
Functional Nanostructures From Nanoparticle Building Blocks, Jimmy Lawrence
Functional Nanostructures From Nanoparticle Building Blocks, Jimmy Lawrence
Doctoral Dissertations
Advances in the synthetic strategies of engineered nanomaterials, multifunctional molecules and polymers have opened pathways for the development of functional nanomaterials having unique optoelectronic, mechanical, and biological properties. By designing the chemistry of surface ligands, the organic interface of nanoparticles, one can further the versatility and utilization of engineered nanomaterials, opening pathways for breakthroughs in sensing, catalysis, and delivery using nanomaterials. This thesis describes the synthesis and characterization of small molecule and polymer ligand functionalized inorganic nanoparticles (e.g., metal, semiconducting). Embedding specific chemical functionality into the ligand periphery of nanoparticles enables the resulting functional nanoparticles to react selectively …
Functional Nanocomposites From Self-Assembly Of Block Copolymers With Nanoparticles, Xinyu Wang
Functional Nanocomposites From Self-Assembly Of Block Copolymers With Nanoparticles, Xinyu Wang
Doctoral Dissertations
This dissertation studied the proper distribution and location control of nanoparticles (NPs) within block copolymer (BCP) templates. A facile ligand exchange reaction was introduced for the hydrophilic magnetic NPs (MNPs) that are readily dispersed in polar solvents with outstanding stability. Small molecule ligands were selected to associate strongly with particle surfaces, provide hydrophilic termini for polarity matching with polar solvents, and offer the potential for hydrogen-bonding interactions to facilitate NP incorporation into polymers. Areal ligand densities of NPs indicated a significant increase in the ligand coverage after the exchange reaction. Hydrophilic MNPs were shown to drive the self-assembly of BCPs …
Engineering Surface Functionality Of Nanoparticles For Biological Applications, Yi-Cheun Yeh
Engineering Surface Functionality Of Nanoparticles For Biological Applications, Yi-Cheun Yeh
Doctoral Dissertations
Engineering the surface functionality of nanomaterials is the key to investigate the interactions between nanomaterials and biomolecules for potent biological applications such as therapy, imaging and diagnostics. My research has been orientted to engineer both of the surface monolayers and core materials to fabricate surface-functionalized nanomaterials through the synergistic multidisciplinary approach that combine organic chemistry, materials science and biology. This thesis illustrates the design and synthesis of the surface-funcitonalized quantum dots (QDs) and gold nanoparticles (AuNPs) for the fundamental studies and practical applications. For QDs, A new class of cationic QDs with quaternary ammonium derivatives was synthesized to provide permanent …
Patterning And Mechanical Analysis Of Fiber-Based Materials, Samuel A. Pendergraph
Patterning And Mechanical Analysis Of Fiber-Based Materials, Samuel A. Pendergraph
Doctoral Dissertations
The ability to define and control the topography of a surface has been studied extensively due to its importance in a wide variety of applications. The control of a non-planar topography would be very valuable since a number of structures that are pervasive in artificial applications (e.g. fibers, lenses) are curved interfaces. This potential of enabling applications that incorporate non-planar geometries was the motivation for this thesis. The first study of this thesis comprises the study of patterning the circumference of micrometer sized fibers. Specifically, a unique technique was described to pattern the fiber with a periodic array of colloids. …