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Theses/Dissertations

Doctoral Dissertations

University of Massachusetts Amherst

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Full-Text Articles in Nanoscience and Nanotechnology

Top-Down And Bottom-Up Fabrication Of Key Components In Miniature Energy Storage Devices, Wenhao Li Jan 2019

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 and the ...


Function And Dissipation In Finite State Automata - From Computing To Intelligence And Back, Natesh Ganesh Jan 2019

Function And Dissipation In Finite State Automata - From Computing To Intelligence And Back, Natesh Ganesh

Doctoral Dissertations

Society has benefited from the technological revolution and the tremendous growth in computing powered by Moore's law. However, we are fast approaching the ultimate physical limits in terms of both device sizes and the associated energy dissipation. It is important to characterize these limits in a physically grounded and implementation-agnostic manner, in order to capture the fundamental energy dissipation costs associated with performing computing operations with classical information in nano-scale quantum systems. It is also necessary to identify and understand the effect of quantum in-distinguishability, noise, and device variability on these dissipation limits. Identifying these parameters is crucial to ...


Development Of Functional Biomaterials Using Protein Building Blocks, Li-Sheng Wang Jan 2019

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 ...


Parallel Algorithms For Time Dependent Density Functional Theory In Real-Space And Real-Time, James Kestyn Jan 2018

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 ...


Probing Local Vacancy-Driven Resistive Switching In Metal Oxide Nanostructures, Jiaying Wang Jan 2018

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 ...


Role Of Rigidity And Flexibility Of Functional Groups Within The Interior Of Supramolecular Assemblies And Their Implications, Oyuntuya Munkhbat Jan 2018

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 ...


Solution-Based Assembly Of Conjugated Polymers Into Nanofibers For Organic Electronics, Daniel E. Acevedo Cartagena Jan 2017

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 ...


Aliovalent Dopants In Zno Nanocrystals: Synthesis To Electronic Structure, Dongming Zhou Jan 2017

Aliovalent Dopants In Zno Nanocrystals: Synthesis To Electronic Structure, Dongming Zhou

Doctoral Dissertations

Semiconductor nanocrystal doping has stimulated broad interest for many applications including solar energy conversion, nanospintronics, and phosphors or optical labels. The study of the chemistry and physics of doped colloidal semiconductor nanocrystals has been dominated in the literature by isovalent dopants such as Mn2+ and Co2+ ions in II-VI semiconductors, in which the dopant oxidation state is the same as the cation ions. Until recently, aliovalent dopants has received much attention due to the plasmonic properties. Aliovalent is when the oxidation states of the dopant in the lattice differs from the cation ions. In the plasmonic semiconductor nanocrystals ...


Guiding The Self-Assembly Of Block Copolymers In 2d And 3d With Minimal Patterning, Jaewon Choi Jan 2017

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 ...


Modeling Of Nanoscale Transport In Mesoporous Membranes, Ashutosh Rathi Jan 2017

Modeling Of Nanoscale Transport In Mesoporous Membranes, Ashutosh Rathi

Doctoral Dissertations

Mesoporous membranes with pore sizes in the range 2-50 nm provide an energy efficient alternative for separation of mixtures such as CO2 from stack effluents and volatile organic compounds (VOC) from air. Transport mechanisms such as capillary condensation, Knudsen diffusion and surface adsorption help in enrichment of a more condensable component based on the bulk mixture thermodynamics, surface chemistry and geometry of the mesopores. Despite the progress in synthesis techniques, design of better mesoporous materials for targeted separations is still a challenge due to the absence of clear design rules. Modeling techniques can be used to quantify the relevant ...


The Rheology And Roll-To-Roll Processing Of Shear-Thickening Particle Dispersions, Sunilkumar Khandavalli Jan 2017

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 ...


Enzyme Stabilization In Hierarchical Biocatalytic Food Packaging And Processing Materials, Dana Erin Wong Jan 2016

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 Jan 2016

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 ...


Morphological And Material Effects In Van Der Waals Interactions, Jaime C. Hopkins Jan 2016

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 ...


Label-Free And Aptamer-Based Surface Enhanced Raman Spectroscopy For Detection Of Food Contaminants, Shintaro Pang Jan 2016

Label-Free And Aptamer-Based Surface Enhanced Raman Spectroscopy For Detection Of Food Contaminants, Shintaro Pang

Doctoral Dissertations

The development of analytical methods to detect food contaminants is a critical step for improving food safety. Surface enhanced Raman spectroscopy (SERS) is an emerging detection technology that has the potential to rapidly, accurately and sensitively detect a wide variety of food contaminants. However, SERS detection becomes a challenge in real complex matrix, such as food, since non-specific matrix signals have the potential to drown out target associated Raman peaks. In this dissertation, we focused on the development and application of label-free, aptamer-based SERS in order to improve the accuracy and specificity of target contaminant detection in food. To accomplish ...


Kinetics And Dynamics Of Electrophoretic Translocation Of Polyelectrolytes Through Nanopores, Harshwardhan Katkar Jan 2016

Kinetics And Dynamics Of Electrophoretic Translocation Of Polyelectrolytes Through Nanopores, Harshwardhan Katkar

Doctoral Dissertations

The idea of sequencing a DNA based on single-file translocation of the DNA through nanopores under the action of an electric field has received much attention over the past two decades due to the societal need for low cost and high-throughput sequencing. However, due to the high speed of translocation, interrogating individual bases with an acceptable signal to noise ratio as they traverse the pore has been a major problem. Experimental facts on this phenomenon are rich and the associated phenomenology is yet to be fully understood. This thesis focuses on understanding the underlying principles of polymer translocation, with an ...


Physically Equivalent Intelligent Systems For Reasoning Under Uncertainty At Nanoscale, Santosh Khasanvis Jan 2015

Physically Equivalent Intelligent Systems For Reasoning Under Uncertainty At Nanoscale, Santosh Khasanvis

Doctoral Dissertations

Machines today lack the inherent ability to reason and make decisions, or operate in the presence of uncertainty. Machine-learning methods such as Bayesian Networks (BNs) are widely acknowledged for their ability to uncover relationships and generate causal models for complex interactions. However, their massive computational requirement, when implemented on conventional computers, hinders their usefulness in many critical problem areas e.g., genetic basis of diseases, macro finance, text classification, environment monitoring, etc. We propose a new non-von Neumann technology framework purposefully architected across all layers for solving these problems efficiently through physical equivalence, enabled by emerging nanotechnology. The architecture builds ...


Functional Nanostructures From Nanoparticle Building Blocks, Jimmy Lawrence Jan 2015

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 with ...


Tunable Photonic Multilayers From Stimulus-Responsive, Photo-Crosslinkable Polymers, Maria C. Chiappelli Jan 2015

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 ...


Patterning And Mechanical Analysis Of Fiber-Based Materials, Samuel A. Pendergraph Sep 2014

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 ...


Engineering Surface Functionality Of Nanoparticles For Biological Applications, Yi-Cheun Yeh Sep 2014

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 ...


Structural, Electronic And Catalytic Properties Of Graphene-Supported Platinum Nanoclusters, Ioanna Fampiou Aug 2014

Structural, Electronic And Catalytic Properties Of Graphene-Supported Platinum Nanoclusters, Ioanna Fampiou

Doctoral Dissertations

Carbon materials are predominantly used as catalytic supports due to their high surface area, excellent electrical conductivity, resistance to corrosion and structural stability. Graphene, a 2D monolayer of graphite, with its excellent thermal, electronic and mechanical features, has been considered a promising support material for next generation metal-graphene nanocatalysts. The main focus of this dissertation is to investigate the properties of such metal-graphene nanocomposites using computational methods, and to develop a comprehensive understanding of the experimentally observed enhanced catalytic activity of graphene-supported Platinum (Pt) clusters.

In particular, we seek to understand the role of graphene supports on the ground-state morphology ...


Functional Nanocomposites From Self-Assembly Of Block Copolymers With Nanoparticles, Xinyu Wang Jun 2014

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 ...