Browsing by Subject "ionic liquid"
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Item Auto Template Assembly of CaCO3-Chitosan Hybrid Nanoboxes and Nanoframes in Ionic Liquid Medium(2012-07-16) Chen, Hsingming AnnaRecently, there has been increased effort in researching methods for producing hollow nanostructures because of their potential impact in the fields of catalysis, separation processes, drug delivery, and energy storage and conversion devices. The purpose of this thesis is to describe a method for forming hollow inorganic-organic hybrid nanoboxes and nanoframes. This approach relies upon ionic liquid (1-butyl-3-methyl-imidazolium chloride) mediated auto-templating assembly of CaCO3 and chitosan to form nanoframes (two open faces) and nanoboxes (one open face). The average dimension of the nanostructures formed was 339 ? 95 x 299 ? 89 nm. Detailed structure of nanoboxes and nanoframes were obtained by 3-D electron tomography and X-ray diffraction. Chemical bonding was determined by FTIR, and the ratio of organics to inorganics in the nanostructures was determined by thermal gravimetric analysis. The chitosan to CaCO3 weigh ratio, mixing strength, temperature, and dialysis time were varied to further elucidate the method of formation. It was found that increasing the mixing power caused the equilibrium nanostructure dimension to decrease. On the other hand, varying the experimental temperature in the range of 80 to 160?C did not affect the nanostructure dimension. The dialysis study showed that during dialysis the nanostructure core was increasingly removed. Nanoframes were observed after 72 hours of dialysis. With further dialysis, there was continued erosion of nanoframes. Results indicate that the concentration gradient and the solubility difference between the mixture components were responsible for this transformation.Item Theoretical Investigations on Nanoporpus Materials and Ionic Liquids for Energy Storage(2012-02-14) Mani Biswas, MousumiIn the current context of rapidly depleting petroleum resources and growing environmental concerns, it is important to develop materials to harvest and store energy from renewable and sustainable sources. Hydrogen has the potential to be an alternative energy source, since it has higher energy content than petroleum. However, since hydrogen has very low volumetric energy density, hence it is important to design nano porous materials which can efficiently store large volumes of hydrogen gas by adsorption. In this regard carbon nanotube and Metal Organic Framework (MOFs) based materials are worth studying. Ionic liquids (IL) are potential electrolytes that can improve energy storage capacity and safety in Li ion batteries. Therefore it is important to understand IL's thermodynamic and transport properties, especially when it is in contact with electrode surface and mixed with Li salt, as happens in the battery application. This dissertation presents computation and simulation based studies on: 1. Hydrogen storage in carbon nanotube scaffold. 2. Mechanical property and stability of various nanoporous Metal Organic Frameworks. 3. Thermodynamic and transport properties of [BMIM][BF4] ionic liquid in bulk, in Li Salt mixture, on graphite surface and under nanoconfinement. In the first study, we report the effects of carbon nanotube diameter, tube chirality, tube spacer distance, tube functionalization and presence of Li on hydrogen sorption capacity and thermodynamics at different temperature and pressure. In the second one, we observe high pressure induced structural transformation of 6 isoreticular MOFs: IRMOF-1. IRMOF-3, IRMOF-6, IRMOF-8, IRMOF-10 and IRMOF-14, explore the deformation mechanism and effect of Hydrogen inside crystal lattice. In the third study, we observe the equilibrium thermodynamic and transport properties of [BMIM][BF4] ionic liquid. The temperature dependence of ion diffusion, conductivity, dielectric constant, dipole relaxation time and viscosity have been observed and found similar behavior to those of supercooled liquid. The ion diffusion on graphite surfaces and under nanoconfinement was found to be higher compared to those in bulk.Item Tribological Properties of Ionic Liquids Lubricants Containing Nanoparticles(2014-05-14) Lu, WeiRecently, there has been an increase in research in the application of ionic liquids containing nanoparticles as lubricants due to their properties such as thermally stability, non-volatility and non-flammability. The purpose of this thesis is to describe the tribological and rheological properties of mixtures of nanoparticles (NPs) and ionic liquids (ILs), specifically the mixture of bare SiO_(2) (silica) nanoparticles and ionic liquid 1-butyl-3-methylimidazolium (trifluoromethysulfony)imide and the mixture of SiO_(2) nanoparticles functionalized by octadecyltrichlorosilane (OTS) and ionic liquid1-butyl- 3-methylimidazolium (trifluoromethysulfony)imide. Functionalized SiO_(2) nanoparticles dispersion in ionic liquid was compared to that of the bare SiO_(2) nanoparticles, and shown that functionalized SiO_(2) nanoparticles led to improved colloidal stability. Friction force profiles, friction coefficients, viscosity behavior, wear behavior of these mixtures at various nanoparticles concentrations for a tribo-pair of stainless steel ball and a steel surface were also investigated. It was shown that the friction coefficient of the OTS functionalized SiO_(2) nanoparticles for the optimum concentration (0.1 wt.%) was 36% less than that of the pure ionic liquid, while the friction coefficient of the bare SiO_(2) nanoparticles and the ionic liquid mixture at the optimum concentration (0.05 wt.%) was 23% less than that for the pure ionic liquid. Moreover, friction surfaces of the two kinds of silica nanoparticles at the optimum concentration were examined by scanning electron microscopy (SEM) and friction traces. Eventually, it has been shown that promising tribological properties of ionic liquids can be further enhanced by incorporating bare SiO_(2) nanoparticles into ionic liquids. Moreover, the tribological performance of the mixture of the OTS functionalized SiO_(2) nanoparticles and ionic liquid could be better than that of the mixture of bare SiO_(2) nanoparticles in the same ionic liquid.