Static measures such as density and entropy, which are intimately connected to structure, have featured prominently in modern thinking about the dynamics of the liquid state. In this dissertation, we explore the connections between self-diffusivity, density, available space, and excess entropy in two non-trivial problems in liquid state theory, confined and supercooled liquids. We present exact simulation data for the relationship between self-diffusivity and excess entropy for a wide range of simple of simple fluids (i.e. hard-sphere, Lennard-Jones and square-well) confined to pores with a variety of different sizes and fluid-wall interations. Our main finding is that, at a given temperature, self-diffusivity of the confined fluids collapses onto the bulk behavior when plotted versus excess entropy. In other words, the only information required to "predict" the implications of confinement for the single-particle dynamics is the bulk fluid behavior at a given temperature and the excess entropy of the confined fluid. This should prove practically useful given that the bulk behavior is well known for these fluid systems, and the excess entropy of the confined fluids can be readily estimated from classical density functional theory. We also show that the self-diffusivity of the confined fluids approximately collapses onto the data for the corresponding bulk fluid when plotted versus the average packing fraction (which is based on total, rather than center accessible volume). For continuous interaction potentials such as Lennard-Jones, calculation of effective packing fraction requires knowledge of both the number density of the fluid and a temperature-dependent Boltzmann diameter associated with the repulsive part of the interparticle interactions. We suggest a way to calculate this effective diameter, which to a very good approximation, collapse the temperature- and density-dependent data for the self-diffusivity of the bulk Lennard-Jones fluid onto hard-sphere fluid data plotted versus the fluid's effective packing fraction. Finally, we found that the self-diffusivities of several model systems in their supercooled state also scale exponentially not only with the excess entropy, but also with the two-body contribution to the excess entropy obtained from the pair correlation function of the fluid. The latter observation is particularly interesting because it provides direct evidence of a quantitative link between the dynamics and the average structural order of supercooled liquids. Whether such a connection could indeed be discovered is part of a long-standing question in the study of liquids. / text

Ionic liquids (ILs) were studied as solvents for electrochemical reactions with the intent to devise metallurgical processes for Al, Mg and Ti that are less energy intensive and operate at lower temperatures than current industrial practice. Tetra-alkyl phosphonium ILs are on the low end of the IL cost spectrum and are regarded as understudied compared with imidazolium and pyridinium ILs. They are also known to be more thermally stable. The density, viscosity and conductivity of the phosphonium ILs and metal salt-IL mixtures were measured. The conductivity of the phosphonium ILs tested were found to be roughly an order of magnitude lower than imidazolium ILs; this is attributed to the relatively large cation size and localized charge. Linear density-temperature functions are presented. The viscosity and conductivity temperature relationship was modeled using the Vogel-Tamman-Fulcher (VTF) equation. The electrochemical window of A10341'14,6,6,610 was studied on a Pt substrate over a wide range of A1C13 concentrations using cyclic voltammetry (CV). It was found that the tetra-alkyl phosphonium cation is on the order of 800 mV more electrochemically stable than the 1-ethyl-3-methyl imidazolium (EMI+). Cathodic and anodic polarization of Al in A1C13-[P14,6,6,6]C1 (Xmc13 = 0.67) was studied at temperatures ranging from 347 to 423 K. The Butler-Volmer equation was fitted to the plots by varying the kinetic parameters. The cathodic reaction was found to be diffusion limited and the anodic reaction is limited by passivation at lower temperatures. The overpotential required for electrodissolution of Al was found to be higher than for electrodeposition. Aluminium was electrodeposited using both an electrowinning setup (chlorine evolution anode reaction) and electrorefining setup (Al dissolution anode reaction). The deposits were characterized in terms of morphology, current efficiency and power consumption. A variety of deposit morphologies were observed ranging from smooth, to spherical to dendritic, and in some cases, the IL was occluded in the deposit. The current efficiency and power consumption were negatively impacted by the presence of H2O and HCl present in the as-received ILs and by C12(g) generated by the anode reaction in the case of the electrowinning setup. HC1 was removed by cyclic polarization or corrosion of pure Al, resulting in current efficiencies above 90%. Aluminium was electrodeposited using the electrorefining setup with anode-cathode spacing of 2 mm at power consumption as low as 0.6 kWhr/kg-Al. This is very low compared with industrial Al electrorefining and Al electroplating using the National Bureau of Standards bath, which require 15-18 kWhr/kg-Al and 18 kWhr/kg-Al, respectively. However, due to low solution conductivity the power consumption increases significantly with increased anode-cathode spacing. Titanium tetrachloride was found to be soluble in [P14,6,6,6]Cl and increases the conductivity of the solution. Attempts to reduce the Ti(IV) included corrosion of titanium metal, corrosion of magnesium metal powder and cathodic polarization. Despite a few attempts, the electro-deposition of Ti was not observed. At this point, titanium electrodeposition from phosphonium based ILs does not appear feasible.

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No description available.

In recent years, ionic liquids have emerged as one of the most promising alternatives to traditional volatile organic solvents when it comes to catalytic reactions. Stable metal nanoparticles suspended in ionic liquids, are catalytic systems that mimic aspects of nanoparticles on solid supports, as well as traditional metal-ligand complexes used in organometallic catalysis. While alkylimidazolium ionic liquids, with or without appended functionalities, have been earmarked as the media of choice for the dispersal of nanoparticles, the tetraalkylphosphonium family of ionic liquids has largely been overlooked, despite their facile synthesis, commercial availability, chemical resemblance to surfactants traditionally used for nanoparticle stabilization, stability under basic conditions, and wide thermal as well as electrochemical windows. It is only recently that a number of research groups have given this family of novel alternative solvents the recognition it deserves, and used metal NPs dispersed in these ILs as catalysts in reactions such as hydrogenations, oxidations, C-C cross-couplings, hydrodeoxygenations, aminations, etc. This thesis investigates the synthesis, characterization, and catalytic applications of transition metal nanoparticles in tetraalkylphosphonium ionic liquids. The ionic liquids described in this thesis functioned as the reaction media as well as intrinsic nanoparticle stabilizers during the course of the catalytic processes. Metallic nanoparticles synthesized in these ionic liquids proved to be stable, efficient and recyclable catalytic systems for reactions of industrial significance, such as hydrodeoxygenations, hydrogenations, and oxidations. It was demonstrated that stability and catalytic activity of these systems were profoundly dependent on the properties of the ionic liquids, such as the nature of the alkyl chains attached to the phosphonium cation, and the coordination ability of the anion. Since heat-induced nanoparticle sintering was a problem, a procedure was devised to redisperse the aggregated and/or sintered nanoparticles so as to restore their initial sizes and catalytic activities. The presence of halides as counter-ions in tetraalkylphosphonium ionic liquids was seen to facilitate the oxidative degradation of agglomerated metal nanoparticles, which was a key step in our redispersion protocol. It was demonstrated that this redispersion protocol, when applied to heat-sintered nanoparticles, produces nanostructures that resemble the freshly made nanoparticles not only in size but also in catalytic activities. The presence of by-products from the borohydride reduction step used to generate the nanoparticles in the ionic liquids actually facilitated multistep reactions such as hydrodeoxygenation of phenol, where a Lewis Acid was necessary for a dehydration step. Finally, an attempt was made to utilize nanoparticles of an earth-abundant metal (iron) as a hydrogenation catalyst in a variety of alternative solvents (including tetraalkylphosphonium ionic liquids) in order to enhance the “green”ness of the catalyst systems. X-ray absorption spectroscopy (XAS) of the iron- nanoparticles/ionic liquid systems at the Canadian Light Source revealed significant details about the chemical interaction between iron and the ionic liquid matrices, which added to our understanding of this neoteric family of catalysts.

No description available.

The statistical mechanics of the interfacial region is studied using the Monte Carlo and molecular dynamics simulation techniques. The penetrable-sphere model of the liquid/vapour interface is simulated using the Monte Carlo method. The pressure equation of state is calculated in the one-phase region and compared to analytic virial expansions of the system. Density profiles of the gas/liquid surface in the two-phase region are calculated and are compared to profiles solved in the mean-field approximation. The effect of the profile near a hard wall is investigated and as a consequence the theory is modified to account for a hard wall. The theory agrees well with the computer result. This is a simple model for adsorption of a gas at a solid surface. A model for methane adsorbed on graphite is proposed. A number of simplifying assumptions are made. The surface is assumed to be perfectly smooth and rigid, and quantum effects are neglected. An effective site-site pair potential for the methane-graphite interaction is adjusted to fit the rotational barriers at OK. The isosteric enthalpy at zero coverage is predicted in the range OK to 200K, by averaging the configurational energy during a molecular dynamics simulation of one methane molecule. The surface second virial coefficients are calculated in the range 225K to 300K and agree with the experimental measurements. The effective pairwise potential predicts the height of the monolayer above the surface and the vibrational frequency against the surface. The translational and rotational behaviour of a single methane molecule are examined. Solid √3 x √3 epitaxial methane is studied at a constant coverage of θ = 0.87 by molecular dynamics simulation. The specific heat and configurational energy are monitored. A slow phase transition occurs between OK and 30K and a sharp transition is observed at 90K. Calculation of the centre-centre distribution functions and order parameters indicates the first transition is due to a slow rotational phase change. At 90K some molecules evaporate from the surface and the remaining bound molecules relax into a 2-d liquid. Between 10K and 25K the adsorbed methane floats across the surface and the question remains open whether this phenomenon is an artifact of the model system or does occur in nature. The dynamical behaviour of adsorbed methane is compared to incoherent inelastic neutron scattering. The principal peaks in the self part of the incoherent structure factor S_s (0,_ω) should correspond to the peaks in the Fourier transforms of the velocity and angular velocity auto-correlation functions. The peaks calculated from the Fourier transform of the auto-correlation functions agree with all the assignments in the experiments. The reorientational motion in the monolayer is monitored and the reorientational auto-correlation functions characterize the slow phase transition from UK to 30K. Three methane molecules are scattered on top of the θ = 0.87 monolayer at 30K. Reorientational correlation functions are compared for the single adsorbed molecule, the monolayer and a few particles in the bilayer. Rotation is less hindered in the monolayer than for a single adsorbed molecule and least hindered in the second layer. Adsorbed methane is studied at coverages of θ < 0.87 over a wide range of temperature in order to unravel various conflicting solid and liquid phases predicted by experiment. By careful monitoring of the structure via changes in the specific heat, the distribution functions and order parameters a liquid/gas coexistence is not observed in the region 56K to 75K. This result is confirmed by calculating the self diffusion coefficients over two isotherms at 65K and 95K. The diffusion coefficients decrease with increasing coverage over both isotherms. If liquid and gas coexist the diffusion coefficient should not change with increasing coverage. The statistical mechanical expression for the spreading pressure of an adsorbed fluid is derived and reported over a wide range of temperature and coverage. Experimental techniques are not as yet sufficiently highly developed to measure this quantity directly. An expression for the coherent neutron scattering structure factor for a model of liquid benzene adsorbed on graphite is derived. This expression is a function of the 2-dimensional centre-centre distribution function and we solve the Ornstein-Zernike equation in the Percus-Yevick approximation to obtain the 2-d distribution functions for hard discs. Agreement with present experimental results is reasonable, but a more highly orientated substrate needs to be used in experiment before a more exact comparison can be made.

The work in this thesis is primarily aimed at supporting the NBe (Nuclear, Biological and Chemical) aspect of Crusader 21, the military clothing programme for the early 21st Century. This aims to produce a multi-purpose, systems-orientated combat ensemble for the UK Armed Services. Conventional "wet" techniques for chemically modifying fabrics have certain disadvantages, however employing plasma technology may provide a route for many novel "multi-functional effects" fabrics such as repellency against toxic chemical agents. In order to produce repellent coatings the surface must have a low surface energy. To obtain this, inert chemical groups need to be attached to the solid substrate. In addition to chemistry, surface roughness plays an important role in repellency. Liquid repellent surfaces have been produced by the pulsed plasma polymerisation of I H, 1 H,2H,2H -heptadecafluorodecyl acrylate. These films have chemical functionalities indicative of polymerisation occurring through the acrylate double bond, as shown by Infrared Spectroscopy analysis. Structural retention was optimised using experimental design techniques and resulted in a critical surface tension of wetting as low as 4.3 mN m-I (c.f. Teflon 18.5 mN m-I). Plasma deposition of a functionalised surface followed by reaction with a fluorinated alcohol proved less affective. Enhanced deposition rates for 1 H, 1 H,2H-perfluorododec-I-ene, over the saturated analogue, have indicated that polymerisation can occur during the off-time of the pulsed plasma period, via free radical polymerisation pathways. X-ray Photoelectron Spectroscopy (XPS) has indicated greater structural group retention for monomers containing double bonds. In order to obtain super liquid repellency the effect of surface roughness was investigated, where both commercially available rough surfaces and plasma roughened substrates were utilised. Once optimised, the rough surfaces were coated with 1 H, 1 H,2H,2H-heptadecafluorodecyl acrylate and produced super repellent films.

Introduction: Electronic Nicotine Delivery Systems (ENDS) debuted in 2006 within the U.S market as novel tobacco products and have been gaining popularity since. Without enforced regulations, prevalence of awareness and use has significantly increased. The purpose of this study is to explore the evolving landscape of ENDS using the Host, Agent, Vector, Environment (HAVE) model with a focus on manufactured e-liquids and do it yourself (DIY) e-liquids as the Agent. Methods: Content analysis of e-cigarette web forums was conducted to identify popular brick and mortar point of sales (POS) for the purchase of ENDS products. POS were mapped out within a 1-, 2-, and 3- mile radius from three college campuses using Google Maps. An environmental scan was then conducted on randomly selected POS sites (N=17) where observations on e-liquid flavors and characteristics were identified. In addition, a content analysis of web forums was used to qualitatively characterize DIY e-liquids in depth. Results: A total of 602 flavors were profiled in the POS environmental scans and five main flavor categories of e-liquids were identified: 1) Tobacco and Menthol (16.6%); 2) Desserts and Candies (16.6%); 3) Fruits (20.6%); 4) Drinks (10.1%); 5) Other (36.0%). Most flavored e-liquids were sold in stand-alone vials (91.0%). When sold with manufactured products, flavored e-liquids were sold in E-Hookahs (10.6%) compared to E-Cigarettes (4.7%). Most (96.8%) flavored e-liquids were available with and without nicotine. Based on content analysis of e-cigarette web forums, the words with the highest frequency in the DIY transcripts were: “flavor”, “mixing”, “liquid”, “calculators”, and “nicotine”. Conclusions: Our findings indicate that for both manufactured and DIY e-liquids, flavors are a distinguishing and primary characteristic. Given these findings, increased surveillance efforts to monitor ENDS and e-liquids are necessary to inform regulatory science.

Structural effects in hydrogen and non-hydrogen bonded liquids and their mixtures have been studied using several experimental techniques and theoretical approaches. Apparent heat capacities and volumes of linear alcohols in hydrocarbons were determined at very low alcohol concentrations and their self-association in solution discussed in terms of the Treszczanowicz-Kehiaian theory. An extension of this theory was used to describe cholesterol self-association and its interactions with tripalmitin and lecithin. Heat capacities of water-organic mixtures are reported. It is found that water behaves as a lower alcohol at the organic-rich concentration range. At the water-rich end, Shinoda's views on water structuring around hydrophobes are supported. Thermal pressure coefficients of cyclohexane + normal and branched alkanes are consistent with the presence of orientational order in the long pure n-alkanes. Excess volumes for mixtures of alkanes with liquids of different internal pressures are predicted using Flory theory. The anomalous thermodynamic behaviour of cyclopentane mixed with cyclic and branched alkanes has been studied through the measurement of cyclopentane spin-lattice relaxation times in these mixtures. An extension of Sanchez-Lacombe theory for pure liquids is described and the molecular parameters obtained for sixty common substances. An equation of state for pure n-alkanes with correlations of molecular orientations is presented.