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- All Subjects: chemical engineering
- Creators: Green, Matthew
- Creators: Dai, Lenore L
Description
Liquid-liquid interfaces serve as ideal 2-D templates on which solid particles can self-assemble into various structures. These self-assembly processes are important in fabrication of micron-sized devices and emulsion formulation. At oil/water interfaces, these structures can range from close-packed aggregates to ordered lattices. By incorporating an ionic liquid (IL) at the interface, new self-assembly phenomena emerge. ILs are ionic compounds that are liquid at room temperature (essentially molten salts at ambient conditions) that have remarkable properties such as negligible volatility and high chemical stability and can be optimized for nearly any application. The nature of IL-fluid interfaces has not yet been studied in depth. Consequently, the corresponding self-assembly phenomena have not yet been explored. We demonstrate how the unique molecular nature of ILs allows for new self-assembly phenomena to take place at their interfaces. These phenomena include droplet bridging (the self-assembly of both particles and emulsion droplets), spontaneous particle transport through the liquid-liquid interface, and various gelation behaviors. In droplet bridging, self-assembled monolayers of particles effectively "glue" emulsion droplets to one another, allowing the droplets to self-assembly into large networks. With particle transport, it is experimentally demonstrated the ILs overcome the strong adhesive nature of the liquid-liquid interface and extract solid particles from the bulk phase without the aid of external forces. These phenomena are quantified and corresponding mechanisms are proposed. The experimental investigations are supported by molecular dynamics (MD) simulations, which allow for a molecular view of the self-assembly process. In particular, we show that particle self-assembly depends primarily on the surface chemistry of the particles and the non-IL fluid at the interface. Free energy calculations show that the attractive forces between nanoparticles and the liquid-liquid interface are unusually long-ranged, due to capillary waves. Furthermore, IL cations can exhibit molecular ordering at the IL-oil interface, resulting in a slight residual charge at this interface. We also explore the transient IL-IL interface, revealing molecular interactions responsible for the unusually slow mixing dynamics between two ILs. This dissertation, therefore, contributes to both experimental and theoretical understanding of particle self-assembly at IL based interfaces.
ContributorsFrost, Denzil (Author) / Dai, Lenore L (Thesis advisor) / Torres, César I (Committee member) / Nielsen, David R (Committee member) / Squires, Kyle D (Committee member) / Rege, Kaushal (Committee member) / Arizona State University (Publisher)
Created2013
Description
Identification of early damage in polymer composite materials is of significant importance so that preventative measures can be taken before the materials reach catastrophic failure. Scientists have been developing damage detection technologies over many years and recently, mechanophore-based polymers, in which mechanical energy is translated to activate a chemical transformation, have received increasing attention. More specifically, the damage can be made detectable by mechanochromic polymers, which provide a visible color change upon the scission of covalent bonds under stress. This dissertation focuses on the study of a novel self-sensing framework for identifying early and in-situ damage by employing unique stress-sensing mechanophores. Two types of mechanophores, cyclobutane and cyclooctane, were utilized, and the former formed from cinnamoyl moeities and the latter formed from anthracene upon photodimerization. The effects on the thermal and mechanical properties with the addition of the cyclobutane-based polymers into epoxy matrices were investigated. The emergence of cracks was detected by fluorescent signals at a strain level right after the yield point of the polymer blends, and the fluorescence intensified with the accumulation of strain. Similar to the mechanism of fluorescence emission from the cleavage of cyclobutane, the cyclooctane moiety generated fluorescent emission with a higher quantum yield upon cleavage. The experimental results also demonstrated the success of employing the cyclooctane type mechanophore as a potential force sensor, as the fluorescence intensification was correlated with the strain increase.
ContributorsZou, Jin (Author) / Dai, Lenore L (Thesis advisor) / Chattopadhyay, Aditi (Thesis advisor) / Lind, Mary L (Committee member) / Mu, Bin (Committee member) / Yu, Hongyu (Committee member) / Arizona State University (Publisher)
Created2014
Description
The mitigation and conversion of carbon dioxide (CO2) to more useful carbon chemicals is a research topic that is at the forefront of current engineering and sustainability applications. Direct photocatalytic reduction of CO2 with water (H2O) vapor to C1-C4 hydrocarbons has significant potential in setting substantial groundwork for meeting the increasing energy demands with minimal environmental impact. Previous studies indicate that titanium dioxide (TiO2) containing materials serve as the best photocatalyst for CO2 and H2O conversion to higher-value products. An understanding of the CO2-H2O reaction mechanism over TiO2 materials allows one to increase the yield of certain products such as carbon monoxide (CO) and methane (CH4). The basis of the work discussed in this thesis, investigates the interaction of small molecules (CO, CH4,H2O) over the least studied TiO2 polymorph - brookite. Using the Gaussian03 computational chemistry software package, density functional theory (DFT) calculations were performed to investigate the adsorption behavior of CO, H2O, and CH4 gases on perfect and oxygen-deficient brookite TiO2 (210) and anatase TiO2 (101) surfaces. The most geometrically and energetically favorable configurations of these molecules on the TiO2 surfaces were computed using the B3LYP/6-31+G(2df,p) functional/basis set. Calculations from this theoretical study indicate all three molecules adsorb more favorably onto the brookite TiO2 (210) surface. Diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) was used to investigate the adsorption and desorption behavior of H2O and CH4 on Evonik P25 TiO2. Results from the experimental studies and theoretical work will serve as a significant basis for reaction prediction on brookite TiO2 surfaces.
ContributorsRollins, Selisa F (Author) / Andino, Jean M (Thesis advisor) / Dai, Lenore L (Committee member) / Forzani, Erica S (Committee member) / Arizona State University (Publisher)
Created2012
Description
Environmentally responsive microgels have drawn significant attention due to their intrinsic ability to change volume in response to various external stimuli such as pH, temperature, osmotic pressure, or electric and magnetic fields. The extent of particle swelling is controlled by the nature of the polymer-solvent interaction. This thesis focuses on design and synthesis of environmentally responsive microgels and their composites, and encompasses methods of utilizing microgel systems in applications as vehicles for the adsorption, retention, and targeted delivery of chemical species. Furthermore, self-assembled microgel particles at ionic liquid (IL)-water interfaces demonstrate responsive colloidal lattice morphology. The thesis first reports on the fundamental aspects of synthesis, functionalization, and characteristic properties of multifunctional environmentally responsive microgels derived from poly(N-isopropylacrylamide) (PNIPAm) and other functional co-monomers. In particular, the uptake and release of active chemical species such as rheology modifiers into and from these ionic microgels is demonstrated. Moreover, a facile tunable method for the formation of organic-inorganic composites with Fe3O4 nanoparticles adsorbed and embedded within ionic microgel particles is explored. Additionally, the development of zwitterionic microgels (ZI-MG) is presented. These aqueous ZI-MG dispersions exhibit reversible parabolic swelling as a function of pH and display a minimum hydrodynamic diameter at a tunable isoelectric point (IEP). This study also elucidates the controlled uptake and release of surfactants from these particle systems. The extent of surfactant loading and the ensuing relative swelling/deswelling behaviors within the polymer networks are explained in terms of their binding interactions. The latter part of this thesis highlights the versatility of fluorescently labeled microgel particles as stabilizers for IL-water droplets. When the prepared particles form monolayers and equilibrate at the liquid-liquid interface, the colloidal lattice organization may re-order itself depending on the surface charge of these particles. Finally, it is shown that the spontaneously formed and densely packed layers of microgel particles can be employed for extraction applications, as the interface remains permeable to small active species.
ContributorsChen, Haobo (Author) / Dai, Lenore L (Committee member) / Chen, Kangping (Committee member) / Forzani, Erica (Committee member) / Lind, Mary Laura (Committee member) / Mu, Bin (Committee member) / Arizona State University (Publisher)
Created2015
Description
Graphene oxide membranes have shown promising gas separation characteristics specially for hydrogen that make them of interest for industrial applications. However, the gas transport mechanism for these membranes is unclear due to inconsistent permeation and separation results reported in literature. Graphene oxide membranes made by filtration, the most common synthesis method, contain wrinkles affecting their gas separation characteristics and the method itself is difficult to scale up. Moreover, the production of graphene oxide membranes with fine-tuned interlayer spacing for improved molecular separation is still a challenge. These unsolved issues will affect their potential impact on industrial gas separation applications.
In this study, high quality graphene oxide membranes are synthesized on polyester track etch substrates by different deposition methods and characterized by XRD, SEM, AFM as well as single gas permeation and binary (H2/CO2) separation experiments. Membranes are made from large graphene oxide sheets of different sizes (33 and 17 micron) using vacuum filtration to shed more light on their transport mechanism. Membranes are made from dilute graphene oxide suspension by easily scalable spray coating technique to minimize extrinsic wrinkle formation. Finally, Brodie’s derived graphene oxide sheets were used to prepare membranes with narrow interlayer spacing to improve their (H2/CO2) separation performance.
An inter-sheet and inner-sheet two-pathway model is proposed to explain the permeation and separation results of graphene oxide membranes obtained in this study. At room temperature, large gas molecules (CH4, N2, and CO2) permeate through inter-sheet pathway of the membranes, exhibiting Knudsen like diffusion characteristics, with the permeance for the small sheet membrane about twice that for the large sheet membrane. The small gases (H2 and He) exhibit much higher permeance, showing significant flow through an inner-sheet pathway, in addition to the flow through the inter-sheet pathway. Membranes prepared by spray coating offer gas characteristics similar to those made by filtration, however using dilute graphene oxide suspension in spray coating will help reduce the formation of extrinsic wrinkles which result in reduction in the porosity of the inter-sheet pathway where the transport of large gas molecules dominates. Brodie’s derived graphene oxide membranes showed overall low permeability and significant improvement in in H2/CO2 selectivity compared to membranes made using Hummers’ derived sheets due to smaller interlayer space height of Brodie’s sheets (~3 Å).
In this study, high quality graphene oxide membranes are synthesized on polyester track etch substrates by different deposition methods and characterized by XRD, SEM, AFM as well as single gas permeation and binary (H2/CO2) separation experiments. Membranes are made from large graphene oxide sheets of different sizes (33 and 17 micron) using vacuum filtration to shed more light on their transport mechanism. Membranes are made from dilute graphene oxide suspension by easily scalable spray coating technique to minimize extrinsic wrinkle formation. Finally, Brodie’s derived graphene oxide sheets were used to prepare membranes with narrow interlayer spacing to improve their (H2/CO2) separation performance.
An inter-sheet and inner-sheet two-pathway model is proposed to explain the permeation and separation results of graphene oxide membranes obtained in this study. At room temperature, large gas molecules (CH4, N2, and CO2) permeate through inter-sheet pathway of the membranes, exhibiting Knudsen like diffusion characteristics, with the permeance for the small sheet membrane about twice that for the large sheet membrane. The small gases (H2 and He) exhibit much higher permeance, showing significant flow through an inner-sheet pathway, in addition to the flow through the inter-sheet pathway. Membranes prepared by spray coating offer gas characteristics similar to those made by filtration, however using dilute graphene oxide suspension in spray coating will help reduce the formation of extrinsic wrinkles which result in reduction in the porosity of the inter-sheet pathway where the transport of large gas molecules dominates. Brodie’s derived graphene oxide membranes showed overall low permeability and significant improvement in in H2/CO2 selectivity compared to membranes made using Hummers’ derived sheets due to smaller interlayer space height of Brodie’s sheets (~3 Å).
ContributorsIbrahim, Amr Fatehy Muhammad (Author) / Lin, Jerry Y.S. (Thesis advisor) / Mu, Bin (Committee member) / Lind, Mary (Committee member) / Green, Matthew (Committee member) / Wang, Qing (Committee member) / Arizona State University (Publisher)
Created2018
Description
In this study, the differences in delivery of methylated and unmethylated prokaryotic
DNA in mammalian cells was investigated. 3 plasmids, DH5-α, ER2925 and
GM272 were extracted and transformed from E. coli bacteria. DH5-α is the regular
methylated plasmid, however,ER2925 and GM272 lack Dam and Dcm enzymes which
methylate adenine and internal cytosine in prokaryotes respectively, hence they are
unmethylated. The 3 plasmids were delivered via different delivery vectors in two
cell lines, UMUC3 and MDA-MB-231 which are human bladder cancer cell line and
human triple negative breast cancer cell line, respectively.
Luciferase and BCA assay were carried out to quantify transgene expression to
compare the efficacy of gene delivery in three aforementioned plasmids. In addition,
hydrodynamic diameter and zeta potential was measured for all delivery vectors, to
correlate with other transgene expression data. The results show that methylated
plasmid has significantly higher transgene expression in mammalian cell lines. This
can be either a result of smaller size and more positive zeta potential that the methylated
plasmid had, or a result of having Dam and Dcm enzymes which enhance binding
of DNA and transcription factors and enhance gene expression. Having smaller size
and more positive zeta potential was proven to be the case for the methylated plasmid
in this study. However the latter hypothesis should be investigated furthermore.
DNA in mammalian cells was investigated. 3 plasmids, DH5-α, ER2925 and
GM272 were extracted and transformed from E. coli bacteria. DH5-α is the regular
methylated plasmid, however,ER2925 and GM272 lack Dam and Dcm enzymes which
methylate adenine and internal cytosine in prokaryotes respectively, hence they are
unmethylated. The 3 plasmids were delivered via different delivery vectors in two
cell lines, UMUC3 and MDA-MB-231 which are human bladder cancer cell line and
human triple negative breast cancer cell line, respectively.
Luciferase and BCA assay were carried out to quantify transgene expression to
compare the efficacy of gene delivery in three aforementioned plasmids. In addition,
hydrodynamic diameter and zeta potential was measured for all delivery vectors, to
correlate with other transgene expression data. The results show that methylated
plasmid has significantly higher transgene expression in mammalian cell lines. This
can be either a result of smaller size and more positive zeta potential that the methylated
plasmid had, or a result of having Dam and Dcm enzymes which enhance binding
of DNA and transcription factors and enhance gene expression. Having smaller size
and more positive zeta potential was proven to be the case for the methylated plasmid
in this study. However the latter hypothesis should be investigated furthermore.
ContributorsMeraji, Seyedehmelika (Author) / Rege, Kaushal (Thesis advisor) / Nannegna, Brent (Committee member) / Green, Matthew (Committee member) / Arizona State University (Publisher)
Created2018
Description
Encapsulant is a key packaging component of photovoltaic (PV) modules, which protects the solar cell from physical, environmental and electrical damages. Ethylene-vinyl acetate (EVA) is one of the major encapsulant materials used in the PV industry. This work focuses on indoor accelerated ultraviolet (UV) stress testing and characterization to investigate the EVA discoloration and delamination in PV modules by using various non-destructive characterization techniques, including current-voltage (IV) measurements, UV fluorescence (UVf) and colorimetry measurements. Mini-modules with glass/EVA/cell/EVA/backsheet construction were fabricated in the laboratory with two types of EVA, UV-cut EVA (UVC) and UV-pass EVA (UVP).
The accelerated UV testing was performed in a UV chamber equipped with UV lights at an ambient temperature of 50°C, little or no humidity and total UV dosage of 400 kWh/m2. The mini-modules were maintained at three different temperatures through UV light heating by placing different thickness of thermal insulation sheets over the backsheet. Also, prior to thermal insulation sheet placement, the backsheet and laminate edges were fully covered with aluminum tape to prevent oxygen diffusion into the module and hence the photobleaching reaction.
The characterization results showed that mini-modules with UV-cut EVA suffered from discoloration while the modules with UV-pass EVA suffered from delamination. UVf imaging technique has the capability to identify the discoloration region in the UVC modules in the very early stage when the discoloration is not visible to the naked eyes, whereas Isc measurement is unable to measure the performance loss until the color becomes visibly darker. YI also provides the direct evidence of yellowing in the encapsulant. As expected, the extent of degradation due to discoloration increases with the increase in module temperature. The Isc loss is dictated by both the regions – discolored area at the center and non-discolored area at the cell edges, whereas the YI is only determined at the discolored region due to low probe area. This led to the limited correlation between Isc and YI in UVC modules.
In case of UVP modules, UV radiation has caused an adverse impact on the interfacial adhesion between the EVA and solar cell, which was detected from UVf images and severe Isc loss. No change in YI confirms that the reason for Isc loss is not due to yellowing but the delamination.
Further, the activation energy of encapsulant discoloration was estimated by using Arrhenius model on two types of data, %Isc drop and ΔYI. The Ea determined from the change in YI data for the EVA encapsulant discoloration reaction without the influence of oxygen and humidity is 0.61 eV. Based on the activation energy determined in this work and hourly weather data of any site, the degradation rate for the encaspulant browning mode can be estimated.
The accelerated UV testing was performed in a UV chamber equipped with UV lights at an ambient temperature of 50°C, little or no humidity and total UV dosage of 400 kWh/m2. The mini-modules were maintained at three different temperatures through UV light heating by placing different thickness of thermal insulation sheets over the backsheet. Also, prior to thermal insulation sheet placement, the backsheet and laminate edges were fully covered with aluminum tape to prevent oxygen diffusion into the module and hence the photobleaching reaction.
The characterization results showed that mini-modules with UV-cut EVA suffered from discoloration while the modules with UV-pass EVA suffered from delamination. UVf imaging technique has the capability to identify the discoloration region in the UVC modules in the very early stage when the discoloration is not visible to the naked eyes, whereas Isc measurement is unable to measure the performance loss until the color becomes visibly darker. YI also provides the direct evidence of yellowing in the encapsulant. As expected, the extent of degradation due to discoloration increases with the increase in module temperature. The Isc loss is dictated by both the regions – discolored area at the center and non-discolored area at the cell edges, whereas the YI is only determined at the discolored region due to low probe area. This led to the limited correlation between Isc and YI in UVC modules.
In case of UVP modules, UV radiation has caused an adverse impact on the interfacial adhesion between the EVA and solar cell, which was detected from UVf images and severe Isc loss. No change in YI confirms that the reason for Isc loss is not due to yellowing but the delamination.
Further, the activation energy of encapsulant discoloration was estimated by using Arrhenius model on two types of data, %Isc drop and ΔYI. The Ea determined from the change in YI data for the EVA encapsulant discoloration reaction without the influence of oxygen and humidity is 0.61 eV. Based on the activation energy determined in this work and hourly weather data of any site, the degradation rate for the encaspulant browning mode can be estimated.
ContributorsDolia, Kshitiz (Author) / Tamizhmani, Govindasamy (Thesis advisor) / Green, Matthew (Thesis advisor) / Srinivasan, Devarajan (Committee member) / Arizona State University (Publisher)
Created2018
Description
An urgent need for developing new chemical separations that address the capture of dilute impurities from fluid streams are needed. These separations include the capture of carbon dioxide from the atmosphere, impurities from drinking water, and toxins from blood streams. A challenge is presented when capturing these impurities because the energy cost for processing the bulk fluid stream to capture trace contaminants is too great using traditional thermal separations. The development of sorbents that may capture these contaminants passively has been emphasized in academic research for some time, producing many designer materials including metal-organic frameworks (MOFs) and polymeric resins. Scaffolds must be developed to effectively anchor these materials in a passing fluid stream. In this work, two design techniques are presented for anchoring these sorbents in electrospun fiber scaffolds.
The first technique involves imbedding sorbent particles inside the fibers: forming particle-embedded fibers. It is demonstrated that particles will spontaneously coat themselves in the fibers at dilute loadings, but at higher loadings some get trapped on the fiber surface. A mathematical model is used to show that when these particles are embedded, the polymeric coating provided by the fibers may be designed to increase the kinetic selectivity and/or stability of the embedded sorbents. Two proof-of-concept studies are performed to validate this model including the increased selectivity of carbon dioxide over nitrogen when the MOF ZIF-8 is embedded in a poly(ethylene oxide) and Matrimid polymer blend; and that increased hydrothermal stability is realized when the water-sensitive MOF HKUST-1 is embedded in polystyrene fibers relative to pure HKUST-1 powder.
The second technique involves the creation of a pore network throughout the fiber to increase accessibility of embedded sorbent particles. It is demonstrated that the removal of a blended highly soluble polymer additive from the spun particle-containing fibers leaves a pore network behind without removing the embedded sorbent. The increased accessibility of embedded sorbents is validated by embedding a known direct air capture sorbent in porous electrospun fibers, and demonstrating that they have the fastest kinetic uptake of any direct air capture sorbent reported in literature to date, along with over 90% sorbent accessibility.
The first technique involves imbedding sorbent particles inside the fibers: forming particle-embedded fibers. It is demonstrated that particles will spontaneously coat themselves in the fibers at dilute loadings, but at higher loadings some get trapped on the fiber surface. A mathematical model is used to show that when these particles are embedded, the polymeric coating provided by the fibers may be designed to increase the kinetic selectivity and/or stability of the embedded sorbents. Two proof-of-concept studies are performed to validate this model including the increased selectivity of carbon dioxide over nitrogen when the MOF ZIF-8 is embedded in a poly(ethylene oxide) and Matrimid polymer blend; and that increased hydrothermal stability is realized when the water-sensitive MOF HKUST-1 is embedded in polystyrene fibers relative to pure HKUST-1 powder.
The second technique involves the creation of a pore network throughout the fiber to increase accessibility of embedded sorbent particles. It is demonstrated that the removal of a blended highly soluble polymer additive from the spun particle-containing fibers leaves a pore network behind without removing the embedded sorbent. The increased accessibility of embedded sorbents is validated by embedding a known direct air capture sorbent in porous electrospun fibers, and demonstrating that they have the fastest kinetic uptake of any direct air capture sorbent reported in literature to date, along with over 90% sorbent accessibility.
ContributorsArmstrong, Mitchell (Author) / Mu, Bin (Thesis advisor) / Green, Matthew (Committee member) / Seo, Dong (Committee member) / Lackner, Klaus (Committee member) / Holloway, Julianne (Committee member) / Arizona State University (Publisher)
Created2018
Description
Carbon dioxide (CO2) levels in the atmosphere have reached unprecedented levels due to increasing anthropogenic emissions and increasing energy demand. CO2 capture and utilization can aid in stabilizing atmospheric CO2 levels and producing carbon-neutral fuels. Utilizing hollow fiber membranes (HFMs) for microalgal cultivation accomplishes that via bubbleless gas-transfer, preventing CO2 loss to the atmosphere. Various lengths and geometries of HFMs were used to deliver CO2 to a sodium carbonate solution. A model was developed to calculate CO2 flux, mass-transfer coefficient (KL), and volumetric mass-transfer coefficient (KLa) based on carbonate equilibrium and the alkalinity of the solution. The model was also applied to a sparging system, whose performance was compared with that of the HFMs. Typically, HFMs are operated in closed-end mode or open-end mode. The former is characterized by a high transfer efficiency, while the latter provides the advantage of a high transfer rate. HFMs were evaluated for both modes of operation and a varying inlet CO2 concentration to determine the effect of inert gas and water vapor accumulation on transfer rates. For pure CO2, a closed-end module operated as efficiently as an open-end module. Closed-end modules perform significantly worse when CO2-enriched air was supplied. This was shown by the KLa values calculated using the model. Finally, a mass-balance model was constructed for the lumen of the membranes in order to provide insight into the gas-concentration profiles inside the fiber lumen. For dilute CO2 inlet streams, accumulation of inert gases -- nitrogen (N2), oxygen (O2), and water vapor (H2O) -- significantly affected module performance by reducing the average CO2 partial pressure in the membrane and diminishing the amount of interfacial mass-transfer area available for CO2 transfer.
ContributorsShesh, Tarun (Author) / Rittmann, Bruce E. (Thesis advisor) / Green, Matthew (Committee member) / Torres, Cesar (Committee member) / Arizona State University (Publisher)
Created2018
Description
The large-scale anthropogenic emission of carbon dioxide into the atmosphere leads to many unintended consequences, from rising sea levels to ocean acidification. While a clean energy infrastructure is growing, mid-term strategies that are compatible with the current infrastructure should be developed. Carbon capture and storage in fossil-fuel power plants is one way to avoid our current gigaton-scale emission of carbon dioxide into the atmosphere. However, for this to be possible, separation techniques are necessary to remove the nitrogen from air before combustion or from the flue gas after combustion. Metal-organic frameworks (MOFs) are a relatively new class of porous material that show great promise for adsorptive separation processes. Here, potential mechanisms of O2/N2 separation and CO2/N2 separation are explored.
First, a logical categorization of potential adsorptive separation mechanisms in MOFs is outlined by comparing existing data with previously studied materials. Size-selective adsorptive separation is investigated for both gas systems using molecular simulations. A correlation between size-selective equilibrium adsorptive separation capabilities and pore diameter is established in materials with complex pore distributions. A method of generating mobile extra-framework cations which drastically increase adsorptive selectivity toward nitrogen over oxygen via electrostatic interactions is explored through experiments and simulations. Finally, deposition of redox-active ferrocene molecules into systematically generated defects is shown to be an effective method of increasing selectivity towards oxygen.
First, a logical categorization of potential adsorptive separation mechanisms in MOFs is outlined by comparing existing data with previously studied materials. Size-selective adsorptive separation is investigated for both gas systems using molecular simulations. A correlation between size-selective equilibrium adsorptive separation capabilities and pore diameter is established in materials with complex pore distributions. A method of generating mobile extra-framework cations which drastically increase adsorptive selectivity toward nitrogen over oxygen via electrostatic interactions is explored through experiments and simulations. Finally, deposition of redox-active ferrocene molecules into systematically generated defects is shown to be an effective method of increasing selectivity towards oxygen.
ContributorsMcIntyre, Sean (Author) / Mu, Bin (Thesis advisor) / Green, Matthew (Committee member) / Lind, Marylaura (Committee member) / Arizona State University (Publisher)
Created2019