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Title: NOVEL ELECTROLYTES FOR LITHIUM-ION BATTERIES
Creator: Ma, Qiang
Date: 2014, 2014-12
Description: With the increasing needs for creating new clean and sustainable energy sources to substitute traditional fossil fuel at present, lithium-ion...
Show moreWith the increasing needs for creating new clean and sustainable energy sources to substitute traditional fossil fuel at present, lithium-ion batteries as one of the most promising energy storage devices have been shown much attention. As a necessary and important component in a battery system, electrolytes need to be expanded according to the cell's requirements for varied applications. Especially nowadays, researches for safe, environmentally friendly and cost effective battery electrolyte systems are very challenging and active all around the world. This dissertation describes three different approaches to achieve an improved electrolyte system for lithium-ion batteries. For solid polymer electrolytes (SPEs), three different plasticizers have been synthesized and incorporated into a conventional poly(ethylene oxide) (PEO)-based SPEs. The room temperature ionic conductivity was significantly improved by decreasing the glass transition temperature of the polymer matrix. One new poly(ethylene glycol)-grafted-polybutadiene was designed and synthesized. Different weight ratios of new co-polymer and PEO mixtures were studied for using as polymer host for SPEs. For liquid electrolytes, two different strategies have been investigated. One is that series of small molecular weight molecular liquids were designed and synthesized to improve the low temperature performance and safety of commonly used organic carbonates systems. Different concentrations of lithium bis-trifluoromethanesulfonimide (LiTFSI) solutions were studied to find the optimized combinations. A series of new zwitterionic liquids (ZILs) were also designed and synthesized as ionic liquid electrolytes. However, this type of electrolytes is too viscous to provide a satisfied ionic conductivity, thus 2-nitropropane as a co-solvent was used here to reduce the viscosity. Last, a series of novel diphosphate-based tetra lithium salts was synthesized and studied. Solartron electrochemical analyzer was used to test ionic conductivity, electrochemical window and lithium cation transference number. The technologies of thermal gravimetric analysis and differential scanning calorimetry were used to study thermal properties of electrolytes. Furthermore, some future plans of studies in lithium-ion battery electrolyte field were also discussed.
Ph.D. in Chemistry, December 2014
Ph.D. in Chemistry, December 2014
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Title: SYNTHESIS AND STRUCTURAL INVESTIGATION OF POLYOXOVANADATE SYSTEMS FOR SEMICONDUCTOR NOx SENSING
Creator: Ravikanth Putrevu, Naga
Date: 2013, 2013-12
Description: Nitrogen oxides (NO and NO2 collectively termed as NOx) are the common air pollutants produced from various indoor and outdoor activities. It...
Show moreNitrogen oxides (NO and NO2 collectively termed as NOx) are the common air pollutants produced from various indoor and outdoor activities. It can cause several environmental problems like ground-level ozone, acid rain, particulate matter, smog formation and health problems like malfunctioning of lungs, damaging air flow passages and creating respiratory problems. To detect these gases, sensors with greater sensitivity, lower recovery time and longer life time are needed. Despite the advantages, of the most widely used NOx sensing materials, semiconducting metal oxides have the limitations like higher operating temperatures and unable to customize the materials with better sensitivity and selectivity. So the current research discusses about a new class of metal oxide systems called polyoxovanadates (POV) and its suitability for the ambient operating conditions. These POVs are basically the vanadium oxide clusters synthesized in top-down and bottom-up synthesis procedures. The main advantages of these systems are possible to synthesize in various sizes, shapes, geometries and dimensions which can help identifying the suitable material for a specific gas. The experimental part discusses about the synthesis, characterization and semiconducting sensing properties of different POV systems using various atomic and molecular spectroscopic techniques. In Chapter 2, a 3-D open framework polyoxovanadate material, [Cd3(H2O)12V16 IVV2 VO36(OH)6(AO4)]·24H2O, (A=V,S) (1), composed of secondary building blocks ({V18O42(AO4)} (A=V,S) clusters) interconnected by {-O-Cd-O-} bridging groups, was chosen for understanding the effect of atmospheric oxygen on 1 electronic properties like band gap and resistance, considering the oxygen as a common xiv interferent in ambient gas sensing. The results explain that 1 interacts with oxygen during the aging process and results changing the vanadium oxidation state from +4 to +5 and expanding the coordination sphere of vanadium from 5 to 6. This expansion can alter the band gap by overlapping the more number of O 2p orbitals with V 3d orbitals and resulting the decrease in resistance. The experiments conducted on molecular {V18O42(AO4)} (A=V,S) cluster, (NH4)8[VIV 12VV 6O42(SO4)]·10H2O, (2a), in Chapter 3, also shown the similar change in band gap and resistance during aging process. Based on the results obtained in Chapter 2 and Chapter 3, a {VO6} containing vanadium oxide cluster, (NH4)2[Ni(H2O)5(NH3)]2[V10O28]·4H2O (4), was synthesized and proved in Chapter 4, that the higher coordination number help lowering the band gap and the resistance without need of aging. In Chapter 5, the NOx sensing properties of 1, 2a, 3 and 4 were studied and compared with well studied NOx sensing material, WO3. Based on the sensing characteristics, 1 shows good sensitivity and response time towards both NO and NO2 under ambient conditions than all the other materials. The FTIR spectroscopy results indicated that the NO2 sensing mechanism occurs via nitrate formation.
PH.D in Chemistry, December 2013
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Title: SYNTHESIS OF TETRAZINE-BASED COVALENT ORGANIC NETWORKS
Creator: Han, Songyang
Date: 2015, 2015-05
Description: After comparison of inorganic, hybrid and organic porous materials, tetrazine based organic porous material was chosen as a target material...
Show moreAfter comparison of inorganic, hybrid and organic porous materials, tetrazine based organic porous material was chosen as a target material since it was rigid material providing micro- to mesoscale pores and could do post-synthetic modifications through inverse electron demand Diels-Alder Reaction with different dienophiles. Such networks own the potential as catalysts after modifying with different metal chelation sites. Here, three strategies were provided to synthesize such materials. During of construction of building blocks through double Diels-Alder Reaction, reactivities of tetrazines and dienophiles were studied. The coupling study provided the information of which type of coupling reaction could be used as well as how it was proceeded. The Direct synthesis of tetrazine-based network through formation of tetrazines then broadened the variety materials that could be synthesized.
M.S. in Chemistry, May 2015
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Title: BLOCK COPOLYMER BASED MICELLE FOR EFFICIENT IMMUNOSENSING
Creator: Li, Ying
Date: 2012-11-26, 2012-12
Description: This thesis demonstrates the formation of micelles from a block copolymer and the application in establishing the micelle based immunosensing...
Show moreThis thesis demonstrates the formation of micelles from a block copolymer and the application in establishing the micelle based immunosensing system. The utilization of polymeric micelle as probe container and antibody carrier increases the probe to antibody ratio, which is expected to leads to better detection efficiency. The substrate used in the immunosensing is a porous 0.45 μm PVDF membrane which allows the stable immobilization of proteins. Tetraphenylporphyrin, a hydrophobic fluorescent dye, was chosen as the probe encapsulated in micelles. The block copolymer is a self synthesized α-carboxyl-ω-hydroxyl terminated Poly(ethylene oxide)-Polycaprolactone with carboxyl group on the hydrophilic end, permitting the conjugation of antibody to the micelle surface. We choose mouse IgG and its antibody anti-IgG as the pair of protein conjugates to demonstrate the immunoassay. So far, the detection limit of mouse IgG is 1.5 μg/ml (10-8 M) in this immunosensing system, which is expected to improve by modifying the system.
M.S. in Chemistry, December 2012
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Title: MAGNETIC RESONANCE IMAGING (MRI) OF CALIBRATION PHANTOMS AND MRI CONTRAST TRENDS IN POLYNUCLEAR CHROMIUM COMPOUNDS
Creator: Sun, Wanlin
Date: 2012-04-25, 2012-05
Description: This thesis is composed of two projects. The first project involves the investigation of a series of Cr+++ compounds as potential magnetic...
Show moreThis thesis is composed of two projects. The first project involves the investigation of a series of Cr+++ compounds as potential magnetic resonance imaging (MRI) contrast agents. The second part of the thesis involves collaborative work with the National Institute of Standards and Technology (NIST) in the development of an MRI calibration phantom designed to correlate data from different MRI institutions for long term studies of diseases such as Alzheimer’s. Data from the Cr+++ project indicated that these compounds show some promise for enhancement of MRI images. The second project resulted in a NIST phantom being built based partly upon data obtained here at IIT.
M.S. in Chemistry, May 2012
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Title: SYNTHESIS AND POST-SYNTHETIC MODIFICATION OF TETRAZINE-BASED ORGANIC FRAMEWORKS
Creator: Kang, Lili
Date: 2016, 2016-05
Description: Porous organic polymers (POPs) have been studied extensively over the past decade. The intrinsic porosity and tunable chemical structures have...
Show morePorous organic polymers (POPs) have been studied extensively over the past decade. The intrinsic porosity and tunable chemical structures have seen applications in gas storage, separations, and even catalysis. However, a vast majority of the POPs rely on a narrow class of monomeric units and polymerization conditions which limit the diversity of functionality in the polymers, and hence their chemical properties. To get around these issues, a micro- and mesoporous tetrazine-based organic framework with BET surface area of 170 m2/g was synthesized through palladium catalyzed cross-coupling reaction. The structure of the polymer was confirmed by solid-state 13C NMR, ATR-IR, and EDX. The 1,2,4,5-tetrazine units on the struts of the framework were active toward inverse electron-demand Diels-Alder reactions, allowing for a post-synthetic introduction of different functionalities into the tetrazinebased organic frameworks (TzOF). The structures of modified polymers were verifed by solid-state 13C NMR and ATR-IR. To eliminate the use of transition metals during synthesis, a new class of sulfur-containing tetrazine-based organic framework was designed and synthesized by nucleophilic aromatic substitution reactions. The resulting mesoporous polymer framework, with 3,6-dithio-1,2,4,5-tetrazine unit on the struts, showed BET surface are of 38 m2/g. The structure of the framework was confirmed by ATR-IR and EDX. Post-synthetic modifications of the polymer were also achieved by reacting with dienophiles through inverse electron-demand Diels-Alder reactions. The structures of modified polymers were verified by ATR-IR. These two synthetic methods we have developed for tetrazine-based organic frameworks and their ability to introduce functionality post-synthetically brought additional functionalities to the POP family.
Ph.D. in Chemistry, May 2016
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Title: ENGINEERING 2D PHOTO-REACTING COF FOR PATTERNING AND DRUG DELIVERY
Creator: Chen, Kuo Hao
Date: 2017, 2017-07
Description: Covalent Organic Frameworks (COFs) are 2-dimensional polymers that exhibit rigid and large surface area as well as porous architectures....
Show moreCovalent Organic Frameworks (COFs) are 2-dimensional polymers that exhibit rigid and large surface area as well as porous architectures. Currently, COFs are tailored for gas storage applications, drug delivery, catalysis and they are used as filtering membranes for water treatment. It is well documented that at the nano/micro scale, COFs can form multi-layered architecture with respect to the basic molecular building blocks. In this picture, it is possible that the 2D intra-layer and 3D inter-layer interactions of the basic molecular units COFs may dictate the overall efficiency of the aforementioned applications. To understand the dimensionality-function relationship of COFs, we are engineering hybrid 1D-2D organic polymers. This hybrid architecture will allow us to study the propagation of energy/exciton transfer within the resulting materials among other applications such as drug delivery and light-induced nano/micro-patterning. To achieve our objectives, I exploited the photo-reacting properties of two molecular systems: The first system is used to prepare the 2D COF of interest and the other system is used to engineer a 1D crystalline solid. Although I have not tested the energy/exciton propagation with the desired material, I have successfully engineered a 1D crystalline solid and synthesized the expected 2D COFs. Using a combination of synthetic strategies, I prepared and characterized photoreacting tetra-phenyl ketone building block that was used to form the desired polymer. I have also engineered 1D needle-like crystals of bisphenyl cyclopropenone compound. Moreover, the two materials were characterized by optical and electron microscopy methods. This thesis will detail the synthesis and characterization of all precursors of the basic molecular units that were used to engineer the 1D crystalline solid and 2D COF materials. Condignly, the optical and scanning electron microscopy images highlight the microscale features of the materials of interest. I am certain that this preliminary investigation will pave the way to study the dimensionality of energy/exciton transfer and reaction propagation in the many organic materials.
M.S. in Chemistry, July 2017
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Title: BIOREMEDIATION VIA SILICA ENCAPSULATION
Creator: Li, Xiaohui
Date: 2011-04-25, 2011-05
Description: In this thesis, a new bioremediation concept is designed and implemented. Using copper (II) as a model pollutant, the concept involves the use...
Show moreIn this thesis, a new bioremediation concept is designed and implemented. Using copper (II) as a model pollutant, the concept involves the use of green algae Chlamydomonas reinhardtii to efficiently collect copper ions from the environment, followed by encapsulating copper loaded algae with silica, thus reducing the bioavailability of copper ions in the environment. A proof-of-concept was established for this concept. In Chapter 1, a brief overview of bioremediation, current state-of–the-art bioremediation methods, and the mechanisms and applications of biosorption is introduced. In Chapter 2, the potential of Chlamydomonas reinhardtii as a copper (II) absorbent is demonstrated by quantifying the copper toxicity, copper uptake rate, copper uptake capacity, copper uptake conditions and effect factors, as well as copper release process from Chlamydomonas reinhardtii. In Chapter 3, a method of encapsulating Chlamydomonas reinhardtii with silica shell using the biomimetic silicification process is described. The silica shell formation is confirmed by both scanning electron microscope (SEM) images and the fluorescence images. Finally in Chapter 4, the work in this thesis is summarized and the future research direction is discussed.
M.S. in Chemistry, May 2011
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