Engineering Commons^™

Harnessing Nanocellulose For Sustainable Carbon Capture: Synthesis, Processing, And Performance Evaluation, Jerred C. Wassgren

Doctoral Dissertations

Scientists and governments have recognized the need for environmental remediation, most notably with the adoption of the Paris Agreement in 2016. One of the major concerns is the production of greenhouse gases (GHGs). The major GHG is carbon dioxide (CO₂) in which humans emit over 36 gigatons yearly. Atmospheric CO₂ is responsible for 60% of the heat retained by the earth – resulting in rising temperatures, melting ice caps, and increasing ocean acidification. Therefore, a major goal of the Paris Agreement was to reduce GHG emissions as well as the capture of CO₂ from the atmosphere. …

Optimizing Channel Formation In Peg Maleimide Hydrogels, Bakthavachalam Kannadasan

Masters Theses

Blood vessels including the arteries, veins, and capillaries are a critical and indispensable component of various organisms. Some studies estimate that if all the blood vessels present in our body are arranged in line, they would amount to a total length of approximately 60,000 miles. This distance is enough to circle the world two and a half times! In addition to being all pervasive, blood vessels perform certain key functions such as delivery of oxygen and nutrients to various tissues in the body. They also assist in the spread of diseases such as cancer. Therefore, it is important to study …

Machine Learning Modeling Of Polymer Coating Formulations: Benchmark Of Feature Representation Schemes, Nelson I. Evbarunegbe

Masters Theses

Polymer coatings offer a wide range of benefits across various industries, playing a crucial role in product protection and extension of shelf life. However, formulating them can be a non-trivial task given the multitude of variables and factors involved in the production process, rendering it a complex, high-dimensional problem. To tackle this problem, machine learning (ML) has emerged as a promising tool, showing considerable potential in enhancing various polymer and chemistry-based applications, particularly those dealing with high dimensional complexities.

Our research aims to develop a physics-guided ML approach to facilitate the formulations of polymer coatings. As the first step, this …

Polyesters Derived From Biobased 1,5-Pentanediol For Coatings, Adhesives, And Biodegradable Plastics, Lei Zheng

Doctoral Dissertations

Biomass-derived polymers are drawing increased attention from researchers due to unique performance attributes, potential for biodegradability, new low-cost feedstocks, and improved sustainability. Biobased feedstocks are employed in both major applications of polymers thermosets and thermoplastics. For thermoset coatings and adhesives, biobased resins such as biobased alkyds, epoxy resins, benzoxazine resins, starch derivatives, and proteins from plants and animals, are promising candidates to replace petroleum-derived counterparts. Thermoplastics such as polyethylene are mainly produced from fossil resources, generally have poor degradability and are difficult to effectively recycle. Currently, in the United States, less than 10% plastics are recycled, and more than 70% …

Polymer Based Energy Storage And Thermal Management On Textile Devices, Wesley A. Viola

Doctoral Dissertations

Humans developed textiles to manage thermal energy transfer with the environment and support homeostasis in a wide range of climates. With the anticipation of wearable technologies to transform healthcare via early, pre-symptomatic detection of illness, there is now a demand for electrical energy storage to support such on-body devices. Finding energy materials to merge seamlessly with textiles is basic requirement to ensure widespread adoption of wearable health monitors. Here we use a vapor deposition process to conformally coat ordinary fabrics with the doped conjugated polymer poly(3,4 ethylenedioxythiophene) (PEDOT-Cl), a soft material which possesses electronic and redox capabilities. We demonstrate PEDOT-Cl …

Effect Of Chemical Identity And Morphology On Amphiphilic-Zwitterionic Block Copolymer Membranes, Ria Ghosh

Doctoral Dissertations

Amphiphilic block copolymers have gained a broad research interest attributed to their self-assembly properties over a range of pH, temperature, and ionic strength. Polyzwitterions have attracted special attention due to their hydrophilicity, charge sensitivity and coulombic attraction of the opposite charges over a range of environments making them a popular material of study in the field of stimuli responsive systems, for example in self-healing hydrogels, and water transport membranes. Combining the stimuli responsiveness and higher hydrophilicity of zwitterionic polymers with self-assembly behavior of amphiphilic block copolymers created an interest to study the effect of composition and identity of the zwitterionic …

Supplementary Code For "Chain Trajectories, Domain Shapes And Terminal Boundaries In Block Copolymers", Benjamin R. Greenvall, Michael S. Dimitriyev, Gregory M. Grason

Data and Datasets

Supplementary code used for the publication "Chain trajectories, domain shapes and terminal boundaries in block copolymers" by Benjamin R. Greenvall, Michael S. Dimitriyev, and Gregory M. Grason. Includes code for extracting and analyzing polar order and chain trajectories from self-consistent field calculations of block copolymers.

Synthesis And Assembly Of Polymer Materials At Interfaces, Xiaoshuang Wei

Doctoral Dissertations

The overarching goal of the thesis is to understand growth and assembly of polymer materials at interfaces. Chapter 2 and Chapter 3 study simultaneous polymer growth and assembly at fluid interfaces, where in-situ photopolymerization and vapor phase deposition were utilized to grow polymers, respectively. Chapter 4 leverages capillary condensation to pattern polymer growth at solid substrates. Chapter 1 provides background information on polymer materials at interfaces, and vapor phase deposition method (initiated chemical vapor deposition, iCVD) to grow polymers. This chapter also reviews polymer thin film wetting, and colloidal assemblies at interfaces. In Chapter 2, we demonstrate the preparation …

Frontiers In The Self-Assembly Of Charged Macromolecules, Khatcher O. Margossian

Doctoral Dissertations

The self-assembly of charged macromolecules forms the basis of all life on earth. From the synthesis and replication of nucleic acids, to the association of DNA to chromatin, to the targeting of RNA to various cellular compartments, to the astonishingly consistent folding of proteins, all life depends on the physics of the organization and dynamics of charged polymers. In this dissertation, I address several of the newest challenges in the assembly of these types of materials. First, I describe the exciting new physics of the complexation between polyzwitterions and polyelectrolytes. These materials open new questions and possibilities within the context …

Modeling Chain Packing In Complex Phases Of Self-Assembled Block Copolymers, Anugu Abhiram Reddy

Doctoral Dissertations

Block copolymer (BCP) melts undergo microphase seperation and form ordered soft matter crystals with varying domain shapes and symmetries. We study the con- nection between diblock copolymer molecular designs and thermodynamic selection of ordered crystals by modeling features of variable sub-domain geometry filled with individual blocks within non-canonical sphere-like and network phases that together with layered, cylindrical and canonical spherical phases forms “natural forms” of self- assembled amphiphilic soft matter at large. First, we present a model to revise our understanding of optimal Frank-Kasper sphere-like morphologies by advancing the- ory to account for varying domain volumes. We then develop generic …

New Isomeric Silicones: Synthesis, Compositions And Surface Properties, Yan Cong

Doctoral Dissertations

This dissertation presents research performed in the field of silicone polymer science, which refers to polymers with alternating silicon-oxygen backbones. Three research topics will be explored. The first topic involves the synthesis of trimethylsiloxysilsesquioxane (MT) copolymers with vinyl and hydride functionalities as reactive liquid silicone precursors. The second topic describes titration of dimethylsiloxy (D) composition into trimethylsiloxysilsesquioxane (MT) copolymers for the purpose of controlling the mechanical properties and thermal stabilities of the material. The last topic explores the modification of hydrophobic silicone surfaces with oxygen plasma to form silica-like, hydrophilic surfaces and the behaviors of hydrophobic recovery. The first chapter …

Development Of Crosslinking Technologies For Waterborne & Powder Coatings, Mengfei Huang

Doctoral Dissertations

Waterborne coatings and powder coatings are fast-growing sectors of the world coating market due to their environmentally friendliness as they have low or zero volatile organic compounds (VOCs) emission. However, compared with solventborne coatings, significant limitations need to be overcome to enable their broad applications. My dissertation will discuss several novel crosslinking strategies for waterborne and powder coating that could enable curing on-demand at ambient conditions, with facile polymerization and easy processing, and ultimately, exhibit a high degree of crosslinking and excellent performance that is comparable to solventborne coatings. We introduced and demonstrated the anionic polymerization mechanism and the high …

Synthesis Of Functionalized Acrylic Nanoparticles As A Precursor To Bifunctional Colloids, Guinevere E. Tillinghast

Masters Theses

Water-borne coatings have increased in popularity due to the recent environmental regulations being placed on coating formulation. The most readily available coatings without volatile organic compounds are thermoplastic polymer dispersions that rely on interdiffusion to form a film. These dispersions are reliant on toxic crosslinking chemistries to achieve adequate coating mechanical properties, but still have significantly inferior properties when compared with current thermosetting industrial coatings that contain volatile organic compounds. As a result, waterborne coatings made with conventional emulsion polymers cannot be considered for high-performance coatings. Polyurethane dispersions have been developed that can meet these demands, but require several lengthy …

Synthesis Of Hybrid Inorganic-Organic Microparticles, Shreyas Joshi

Masters Theses

The self-assembly of isotropic and anisotropic colloidal particles into higher-ordered structures has been of great interest recently due to the promise of creating metamaterials with novel macroscopic properties. The physicochemical properties of these metamaterials can be tailored to achieve composites with tunable functionalities. The formation of these metamaterials can be used as a pathway to emulating advanced biological systems. In particular, synthetically mimicking the surface of a moth’s eye, which consists of arrays of ellipsoidal protuberances, can be used as a strategy for fabricating antireflective coatings.

To enable this technology, it is necessary to design a synthesis scheme that produces …

Free Radical Polymerization Of Novel Copolymer; Ethylene-Co-Diethyl Methylene Malonate Copolymers, Sydney Foster

Masters Theses

Ethylene copolymers are widely used as packaging materials, adhesives and specialty polymers for well-regarded cost savings, durability, chemical resistance, and hot melt character. This work examines the use of diester monomers known as malonates to determine the plausibility of utilizing an uncommon monomer class for producing novel ethylene copolymers. Ethylene is copolymerized with diethyl methylene malonate—a simple malonate representative of more complex and highly modified malonate monomers and macromers—to produce ethylene-co-diethyl methylene malonate in a range of molecular weights. Ethylene-co-diethyl methylene malonate is analyzed to determine physical properties such as glass transition temperature, chain length and monomer incorporation. Successful copolymerization …

Advanced Materials Design Using Application-Based Processing Techniques, Daniel S. Camarda

Doctoral Dissertations

This dissertation pertains to generating advanced materials using application-based processing techniques. First, billets consisting of PTFE sintering powders are evaluated using Thermomechancal Analysis. It was found that both shape change and volume change are associated with enthalpic and entropic recoil, respectively. These phenomena, due to melting and stored energy during the powder compaction process, were found to be molecular weight dependent. Additionally, kinetics of the recovery and sintering process were found to be slower in blended specimens than pure samples. Next, the creation of graft copolymers by selectively grafting a second polymer to the amorphous fraction of a semi-crystalline polymer …

Understanding Complex Coacervation Of Low Charge Density Copolymers And Latexes, Nicholas Bryant

Masters Theses

Many coatings only need to either be durable or fast drying, usually sacrificing long term stability in favor of quick setting, or vice versa. One coating type that cannot afford to sacrifice either performance feature is traffic paint. These paints are made up of a weak polycation, an anionic latex, and a volatile base which evaporates upon application. The high pH in the initial formulation deprotonates the polycation, rendering it charge neutral. However, upon evaporation, the resulting drop in pH allows for the electrostatic complexation between the polycation and the latex. The electrostatic interactions used in these formulations parallels that …

Direct Printing/Coating/Plating Of Key Components For Electronic Devices, Xiyu Hu

Doctoral Dissertations

Miniaturization has been a technological trend for several decades for electronic devices. From the practical point of view, the successful miniaturization of fully integrated systems mainly depends on their components. This dissertation examines the inkjet printing of copper oxide inks on flexible substrates for applications in microfluidic valving systems. We expand the knowledge of low-cost and high-performance electrowetting valves and fabricate the microfluidic device for fluidic control, which is necessary to enable the next-generation microfluidic devices. In addition, we also study the electromagnetic interference (EMI) shielding material, which is a crucial part of electronic devices. The basic theory of EMI …

Surface Modification Of Cellulose Nanocrystals: Imparting Non-Native Properties On Sustainable Substrates, Allen C. Chang

Doctoral Dissertations

Governments and scientists all over the planet have recognized the importance of pursuing and achieving sustainability. As the human population grows and technologies advance, the planet’s limited resources become less and less able to support our taxing demands. In 2015, the United Nations set forth 17 Sustainable Development Global Goals. Goal 12 “Responsible Production and Consumption” can be addressed quite readily by the integration of sustainable materials into advanced technologies; however, such materials have yet to be developed. Cellulose nanocrystals (CNCs) – an abundant, well-known sustainable nanomaterial hydrolyzed from bulk cellulose with high surface functionality and high strength properties – …

Synthesis Of Inorganic Porous Materials With Tunable Morphology For Molecular Adsorption And Separation, Sanket Sabnis

Doctoral Dissertations

Global industrial and economic development over the past century has largely relied on combustion of non-renewable fossil fuels, such as petroleum, coal, and natural gas, which are also harmful to environment because of the release of CO₂, responsible for global warming and climate change. Establishing eco-friendly, energy-efficient and cost-effective processes to reduce environmental impact is currently one of the most urgent issues for the sustainable development of our society. Inorganic porous materials have found applications in the fields of renewable energy and environmental protection such as biomass conversion, fuel cells, thermal energy storage, CO₂ capture and conversion, …

Electrospinning Fibers Via Complex Coacervation, Xiangxi Meng

Doctoral Dissertations

Electrospun fibers are high-surface-area materials widely used in applications ranging from batteries to wound dressings. Typically, an electrospinning precursor solution is prepared by dissolving a high-molecular-weight polymer in an organic solvent to form a sufficiently entangled solution. Our approach bypasses the requirement for entanglements and completely avoids toxic chemicals by focusing on using an aqueous complex coacervates solution. Coacervates are a dense, polymer-rich liquid phase resulting from the associative electrostatic complexation of oppositely charged macroions. We were the first to demonstrate that liquid complex coacervates could be successfully electrospun into polyelectrolyte complex (PEC) fibers. A canonical coacervate system was formed …

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. …

Sequence Control Of Complex Coacervation, Li-Wei Chang

Doctoral Dissertations

Complex coacervation is a liquid-liquid phase separation driven by the complexation of oppositely charged polyelectrolytes. The resulting coacervate phase has been used for many applications, such as underwater adhesives, drug delivery, food and personal care products. There also has been increasing interest in coacervate-like droplets occurring in biological systems. The majority of these “membraneless organelles” involve a combination of intrinsically-disordered proteins and RNA, and phase separate due to long-range charge effects and short-range hydrophobic effects. While evolution has optimized the self-assembly of these types of biological polymers, our ability to design such materials remains limited, in part because the relevant …

Kinetics Of The Crystal-Melt Phase Transformation In Semicrystalline Polymers, Kiran Subramaniam Iyer

Doctoral Dissertations

The assembly of long-chain polymers into an ordered state is a process that has puzzled polymer scientists for several decades. A process that is largely controlled by the strength of intermolecular attractions in small molecular systems, this crystallization in the case of polymers is controlled by a competition between the aforementioned force of attraction between monomers and the formidable conformational entropy of polymer chains. Any factor that affects this conformational entropy, whether that is an equilibrium thermodynamic factor or a kinetic factor, has the ability to control polymer crystallization. In this thesis, we focus on understanding the underlying kinetic processes …

Characterizing Non-Linear Structural, Mechanical, And Volumetric Properties Of Aliphatic And Aromatic Thermosets, Brendan Robert Ondra

Doctoral Dissertations

A unifying theme throughout this dissertation employs advanced experimental mechanics, including the design and development of new instruments, testing techniques, and analysis strategies. Chapter 1 covers the design and development of a new instrument for polymer and composite characterization. More specifically, a bi-fluidic, confining-fluid, pressurizable dilatometer (referred to herein as the BFCF-PVT). Whereas both classical and contemporary confining-fluid type pressurizable dilatometers utilize a bellows and / or piston system along with a Linear Variable Displacement Transducer to apply pressure and track volume changes, the BFCF-PVT that was designed and built utilizes a fluid-fluid interface (composed of two immiscible fluids that …

Surface Driven Flows : Liquid Bridges, Drops And Marangoni Propulsion, Samrat Sur

Doctoral Dissertations

Molecules sitting at a free liquid surface against vacuum or gas have weaker binding than molecules in the bulk. The missing (negative) binding energy can therefore be viewed as a positive energy added to the surface itself. Since a larger area of the surface contains larger surface energy, external forces must perform positive work against internal surface forces to increase the total area of the surface. Mathematically, the internal surface forces are represented by surface tension, defined as the normal force per unit of length. One common manifestation of surface tension is the difference in pressure it causes across a …

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

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

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, …

Amorphous-Crystalline Brush Block Copolymers: Phase Behavior, Rheology And Composite Design, Gayathri Kopanati

Doctoral Dissertations

Bottlebrush block copolymers are polymers with chemically distinct polymer side chains grafted onto a common backbone. The unique architecture induced properties make these materials attractive for applications such as photonic materials, stimuli responsive actuators and drug delivery vehicles to name a few. This dissertation primarily investigates the phase transitions and rheological behavior of amorphous-crystalline bottlebrush brush block copolymers and their composites. The temperature induced phase behavior is investigated using time resolved synchrotron X-ray source. Irrespective of volume fraction and backbone length, the samples display strong segregation even at high temperatures (200 °C) and there is no accessible order-disorder transition in …