First-principles molecular dynamics simulations in the canonical ensemble at temperatures of 333 and 363 K and at the corresponding experimental densities are carried out to investigate the behavior of the 1:2 choline chloride/urea (reline) deep eutectic solvent and its equimolar mixture with water. Analysis of atom-atom radial and spatial distribution functions and of the H-bond network reveals the microheterogeneous structure of these complex liquid mixtures. In neat reline, the structure is governed by strong H-bonds of the trans- and cis-H atoms of urea to the chloride ion. In hydrous reline, water competes for the anions, and the H atoms of urea have similar propensities to bond to the chloride ions and the O atoms of urea and water. The vibrational spectra exhibit relatively broad peaks reflecting the heterogeneity of the environment. Although the 100 ps trajectories allow only for a qualitative assessment of transport properties, the simulations indicate that water is more mobile than the other species and its addition also fosters faster motion of urea.

Hydrophobic deep eutectic solvents (DESs) are a new generation of water immiscible solvents that have been presented in the literature for the first time in 2015. These solvents have been used for many applications. Here, an overview is given regarding hydrophobic DESs with their physicochemical properties, applications, and the challenges and limitations that the field currently is experiencing. First, a general introduction and an introduction to hydrophobic DESs are presented to explain more about DESs, their origin, and hydrophobic ones. Here, also, an overview of all the hydrophobic DESs presented in the literature is given. After the introduction, physicochemical properties such as density, viscosity, melting point, degradation temperature, volatilities, and solvatochromic properties are discussed. It is continued with the discussion of 21 different applications of hydrophobic DESs. In general, applications related to liquid–liquid extractions, liquid–liquid microextractions, formation of two and three phase systems, removal of components from leaves, gas–liquid extractions, formation of hydrogels, membrane formation, centrifugal partition chromatography, formation of a ferrofluid, coating, photoluminescence, and dye-sensitized solar cells, and catalysis have been investigated. Finally, challenges and limitations of hydrophobic DESs are discussed.

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The role of typical hydrocarbon building blocks of gas-to-liquid (GTL) derived jet fuels on their physical and chemical properties have been investigated. The ultimate goal of our studies is to develop accurate composition−property relationships for synthetic fuels to be used in optimizing synthetic fuel properties as per the aviation industry standards. The composition−property analysis has been carried out through formulating in-house fuel blends using neat GTL fuel building blocks (normal-, iso-, and cyclo-paraffins). Typical properties of interest in this study are density, freezing point, flash point, and heat content, all of which are essential for jet fuel certification. The systematic approach developed in this study was to identify an optimized region, in which all major properties for aviation standards are met. Different techniques were used, including the development of ternary mapping of these aforementioned building blocks alongside their physical properties. This has been achieved through formulating 35 blends giving a broad spread across the ternary map and generating a database from the experimental results. The optimized region and the composition−property relationships were obtained through building a statistical model of artificial neutral networks (ANNs) using the data generated as its basis. The generated data show that some properties, such as freezing point, exhibit nonlinear results whereas others are strongly linear, such as density and heat content. Aromatics in jet fuels are impactful (and required) even though their environmental harms are evident, and as such, their role on certain properties was preliminarily investigated. Furthermore it has been observed that different crystal shapes exist within some areas in the freezing point ternary map. Finally, the use of mathematical models as predictive tools was investigated, and in most instances the model developed was accurate. The outcome of the current study has been used to develop a new visualization technique for the relationship between GTL synthetic paraffinic kerosene's and their building blocks (i.e., paraffinic hydrocarbons).

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