Ion transport of electrolytes determines the performance of many electroactive devices, from fuel cells to batteries to soft mechanical actuators. This dissertation aims to address some fundamental issues regarding ion transport of ion dense electrolytes using electrophoretic NMR and NMR diffusometry. I first describe the design and fabrication of the first instrumentation capable of reliable ENMR on highly ion-dense electrolytes such as ionic liquids and electrolytes for zinc-air batteries. I design a new electrophoretic NMR sample cell using parallel capillaries to investigate the electrophoretic mobilities of pure ionic liquids. It shows the first study of a highly ion-dense electrolyte with electrophoretic NMR. Then I employ NMR diffusometry and electrophoretic NMR to investigate ion association of pure ionic liquids. Then I use electrophoretic NMR technique to investigate the electrophoretic mobilities of electrolytes for zinc-air batteries. For Zn2+ salt added dicyanamide (dca) based ionic liquids, I investigate the effects of Zn2+ salt on chemical shift of dca and ion motion. The combination of mobilities measurements and diffusion measurements provides some new insight of ion aggregation. We explore ion transport of ionic liquids inside the ionic polymer Nafion as a function of hydration level. When ionic liquids diffuse inside ionic polymers, isolated anions diffuse faster (e 4X) than cations at high hydration whereas ion associations result in substantially faster cation diffusion (d 3X) at low hydration inside membranes, revealing prevalent anionic aggregates. Finally, we compare diffusion activation energy measurements in a hydrated perfluorosulfonate ionomer and aqueous solutions of triflic acid, which provides insight into water transport dynamics on sub-nm lengthscales. And we explore the physical meaning of activation energy, characterizing local intermolecular interactions that occur on the pre-diffusional (~ 1 ps) timescale. / Ph. D.

In this study we present the results of electroless deposition of silver (Ag) and electrophoretic deposition (EPD) of Al2O3 layers on glass for application in thin film transistor (TFT). Since Ag exhibits excellent resistivity, it is selected to be the material of conductive layer. Ag thin film electrical and physical parameters are studied as a function of the deposition time and working temperature. We study the thin-film electrical and mechanical properties using 4-point Probe, surface analyzer and nano indenter. The Ag film, thicker than 200 nm, exhibited a specific electrical sheet resistivity of about 500 m£[/¡¼. We also study the thin-film morphology and composition using SEM and FTIR, respectively. In this study, Mechanism and kinetics of the electrophoretic process in an Al2O3 cell are also studied. Al2O3 concentration levels are set from 1.25 to 7.5%, and deposition time from 5~20 seconds. Deposition time and Al2O3 particle concentration is experimentally discussed and characterized. The result shows that a linear relationship between the deposition rate and applied voltage is obtained. Besides, in this study, deposition of conductive layer silver and insulating layer Al2O3 for TFT are studied. A new process to deposit Ag layer and Al2O3 layer to be the conductivity layer and insulating layer of TFT is presented. First, the circuit pattern is defined by lithography process. Then, Ag is deposited with thickness of 200 nanometers. Second, the wafer is immersed in the stripper solution to remove the resist. After the deposition of the Ag on glass is finished, Al2O3 nano-scale particle concentration is prepared for electrophoretic deposition.

Philosophiae Doctor - PhD / High Temperature Polymer Electrolyte Membrane Fuel Cells (HT-PEMFC) have received renewed interest in recent years due to its inherent advantages associated with the limitations faced by Low Temperature Polymer Electrolyte Membrane Fuel Cells (LT-PEMFC). The high Pt loadings required for PEMFCs have significantly hindered its commercialisation. Electrophoretic Deposition (EPD) is a promising route to reduce the noble metal loading. EPD is a method in which charged colloidal particles are deposited onto a target substrate under the force of an externally applied electric field. To effectively study the EPD method, the methodology of this study was divided into two parts: (i) the EPD method was studied via known empirical methods to fabricate, test and characterise MEAs suitable for HT-PEMFCs. The feasibility of the EPD method was determined by comparing the performance of the fabricated EPD MEAs to MEAs fabricated via spraying methods, and (ii) due to the promising results obtained in part (i) of the methodology, a theoretical model was developed to obtain a deep understanding about nature of the interactions between the Pt/C particles in a colloidal suspension. The theoretical model will serve as a foundation for future studies. In part (i) of the methodology, the Pt/C particles were studied in organic solutions (i.e. Isopropyl Alcohol, IPA) via the Zetasizer Nano ZS instrument under various salt (NaCl) concentrations and pH conditions while introducing polymeric surfactants, i.e. Nafion® ionomer and Polytetrafluoroethylene (PTFE) to the suspension. The optimum catalyst suspensions were selected to fabricate GDEs via the EPD method. Physical characterisations revealed that the EPD GDEs exhibited cracked morphology with high porosity. Electrochemical characterisations revealed that the EPD MEA showed significantly better performance (i.e. 73% higher peak power) compared to the hand vi sprayed MEA due to lower charge transfer and mass transport resistance at high current densities. Compared to the ultrasonically sprayed MEA, the EPD MEA exhibited a peak power increase of ~12% at a slightly lower Pt loading (i.e. ~4 wt%). A comparative study between the Nafion® ionomer and PTFE in the CLs of two EPD MEAs revealed superior performance for the EPD MEA with the PTFE in the CLs. Part (ii) of the methodology deals with the electrical interfacial properties of the aqueous Pt/C suspension. The study consists of two sets of measurements (i.e. electrophoretic and coagulation dynamic studies) conducted for different electrolyte compositions. A theoretical background on determining the interfacial potential and charge from electrophoretic and coagulation dynamic measurements are provided. Detailed statements of the Standard Electrokinetic and Derjaguin, Landau, Vervey and Overbeek Models are given in the forms that are capable of addressing electrophoresis and the interaction of particles for an arbitrary ratio of the particle to Debye radius, interfacial potential and electrolyte composition. The obtained experimental data were processed by using numerical algorithms based on the formulated models for obtaining the interfacial potential and charge. While analysing the dependencies of interfacial potential and charge on the electrolyte compositions charge, conclusions were made regarding the mechanisms of charge formation. It was established that the behaviour of system stability is in qualitative agreement with the results computed from the electrophoretic data. The verification of quantitative applicability of the employed models was conducted by calculating the Hamaker constant from the experimental data. It was proposed how to explain the observed variations of the predicted Hamaker constant and its unusually high value.

This project aims to discover a new means of overcoming the drawbacks of traditional layer-by-layer dip coating through the use of polyelectrolyte complexes (PECs) and electrophoretic deposition. The layer-by-layer process, by which oppositely charged polyelectrolytes or other charged particle are alternately adsorbed onto a substrate to produce a thin film of precisely controllable thickness, is versatile and simple to implement but suffers from requiring numerous, long deposition steps to produce uniform micron thick films. PECs are small associations of oppositely charged polyelectrolytes that, when mixed in non-stoichiometric ratios, can form charged water- soluble particles. There is much still to be determined about the phase behavior of PECs. However, it has been shown that they can exist over a range of conditions. Electrophoretic deposition is a technique used in many commercial applications for the deposition of charged particles onto a conducting substrate. It has even been shown to enhance the deposition of polyelectrolyte single layers and multilayers. This study examines the phase behavior of PECs made of linear poly(ethyleneimine) (LPEI) and poly(acrylic acid) (PAA). PEC behavior is studied over a pH range of 4.0 to 6.0, with no salt added to the system. This study also reports the results of tests examining how soluble PECs responded to changes in pH and whether solid PECs could be made to dissolve through the addition of different salts. Light scattering is used to examine the particle size distribution and effective diameter of PECs in solution. This information is then used to electrophoretically deposit PECs with 10%, 30%, 70%, and 90% excess LPEI. Stylus profilometry is used to assess the thickness of deposited films. The results showing that PEC layers deposited under an applied voltage were 40% to 400% thicker than PECs deposited with no applied potential.

Thesis (Ph.D.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references.

Within this study, the focus will be on oligoglycines. Numerous studies pertaining to the mobility and conformations of oligoglycines have been completed, as this is a driving force for the study. The oligopeptide is modeled using a “coarse-grained” model created in the Allison lab at Georgia State University [Xin,Y.,et. al, J. Phys. Chem. B 2006, 110, 1038-1045], which will be briefly explained within this paper. Oligoglycines will be studied in a few different systems, as the overall charge on the peptide and system will affect its mobility. The conclusion drawn is that the peptide adopts three different conformations based on the temperature of the system and length of the peptide; random conformation at high temperatures, and compact conformations at low temperature. Oligoglycines of length three to five amino acids adopts a cyclic conformation at low temperatures. [Allison, S., et al., J. Sep. Sci. 2010, 33, 2430- 2438.]

The design of nanoparticles in mesoporous supports is explored through synthetic strategies of electrophoretic deposition and electroless deposition with application towards energy storage. Electrophoretic deposition of nanoparticles into a mesoporous thin film is examined using charged nanocrystals in a low-permittivity solvent. To provide a basis for the deposition, the mechanism of particle charging in a low-permittivity solvent was studied. Dispersions of carbon black particles in toluene with an anionic surfactant were characterized using differential-phase optical coherence tomography with close electrode spacing to measure the electrophoretic mobility. The particle charge in concentrated dispersions was found to decrease as a function of increasing surfactant concentration. Partitioning of cations between the surfactant-laden particle surface and micelle cores in the double-layer was found to govern the dynamics of particle charging. Subsequently, charged Au nanocrystals were deposited by electrophoresis within perpendicular mesochannels of a TiO2 support. High loadings of 21 wt% Au with good dispersion were achieved within the mesoporous TiO2 support using electrophoretic deposition, which would otherwise be inhibited by the weak nanocrystal-support interaction. According to a modified Fokker-Planck equation, the mean penetration depth of a single nanocrystal inside of the perpendicular pores was found to be dependent on the electric field strength, electrophoretic mobility, pore diameter, nanocrystal size, and local deposition rate constant. Nanocomposites for electrochemical capacitors were designed via electroless deposition of redox-active MnO2 in a high surface area mesoporous carbon support. Disordered mesoporous carbon supports with a pore size of ~8 nm were used both in amorphous (AMC) and graphitic (GMC) form, with a ~1000-fold larger conductivity for GMC. High loadings of 30 wt% MnO2 were achieved in the AMC in the form of ~1 nm thick domains, which were highly dispersed throughout the support. Oxidation of the GMC was necessary to facilitate wetting and deposition of the MnO2 precursor in order to achieve high loadings of 35 wt% MnO2 with ~1 nm thickness. High gravimetric MnO2 pseudocapacitances of >500 F/gMnO2 were achieved at low loadings and low scan rate of 2 mV/s for both carbon supports. However, at high scan rates ≥100 mV/s, the MnO2 pseudocapacitance is twofold larger for MnO2/GMC, relative to MnO2/AMC. Sodium ion diffusion throughout both MnO2/AMC and MnO2/GMC was shown to be facile. For the GMC versus AMC support, the higher MnO2 pseudocapacitance is attributed to the higher electronic conductivity, which facilitates electron transport to the MnO2 domains. / text

No description available.

abstract: Disease prevention and personalized treatment will be impacted by the continued integration of protein biomarkers into medical practice. While there are already numerous biomarkers used clinically, the detection of protein biomarkers among complex matrices remains a challenging problem. One very important strategy for improvements in clinical application of biomarkers is separation/preconcentration, impacting the reliability, efficiency and early detection. Electrophoretic exclusion can be used to separate, purify, and concentrate biomarkers. This counterflow gradient technique exploits hydrodynamic flow and electrophoretic forces to exclude, enrich, and separate analytes. The development of this technique has evolved onto an array-based microfluidic platform which offers a greater range of geometries/configurations for optimization and expanded capabilities and applications. Toward this end of expanded capabilities, fundamental studies of subtle changes to the entrance flow and electric field configurations are investigated. Three closely related microfluidic interfaces are modeled, fabricated and tested. A charged fluorescent dye is used as a sensitive and accurate probe to test the concentration variation at these interfaces. Models and experiments focus on visualizing the concentration profile in areas of high temporal dynamics, and show strong qualitative agreement, which suggests the theoretical assessment capabilities can be used to faithfully design novel and more efficient interfaces. Microfluidic electrophoretic separation technique can be combined with electron microscopy as a protein concentration/purification step aiding in sample preparation. The integrated system with grids embedded into the microdevice reduces the amount of time required for sample preparation to less than five minutes. Spatially separated and preconcentrated proteins are transferred directly from an upstream reservoir onto grids. Dilute concentration as low as 0.005 mg/mL can be manipulated to achieve meaningful results. Selective concentration of one protein from a mixture of two proteins is also demonstrated. Electrophoretic exclusion is also used for biomarker applications. Experiments using a single biomarker are conducted to assess the ability of the microdevice for enrichment in central reservoirs. A mixture of two protein biomarkers are performed to evaluate the proficiency of the device for separations capability. Moreover, a battery is able to power the microdevice, which facilitates the future application as a portable device. / Dissertation/Thesis / Doctoral Dissertation Chemistry 2019

Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (leaves 143-154).