Crystalline and Liquid Structure of Zinc Chloride Trihydrate: A Unique Ionic Liquid
Abstract not provided
Wilcox, Robert J.↗
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Results for “ionic liquid”
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Thermodynamic Framework for Water in Deep Eutectic Solvents and Ionic Liquids
Water is widely recognized as critical to the tunability and electrochemical stability of nonaqueous solvents such as deep eutectic solvents (DESs) and ionic liquids (ILs). Traditionally, the water content of these solvents has been controlled by either drying or adding small amounts of water to control their bulk properties to meet specific application requirements. The total water content by itself, does not provide sufficient information about the chemical reactivity and molecular interactions within DES– and IL–water mixtures. In this concept article, water activity is highlighted as a thermodynamically more rigorous descriptor to quantify the influence of the co‐solvent water on DES– and IL–water mixtures. Water activity relates measurable physical properties, such as vapor pressure, density, viscosity, electrochemical stability, and conductivity of DESs and ILs to the underlying molecular interactions between their components. Furthermore, water activity of DESs and ILs correlates with changes in local solvent structures and thermodynamic excess properties, including excess molar volume, enthalpy, and Gibbs energy.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Hierarchical Sol-Gel Transition Induced by Thermosensitive Self-Assembly of an ABC Triblock Polymer in an Ionic Liquid
Here we investigate a hierarchical morphology change and accompanying sol–gel transition using a doubly thermosensitive ABC-triblock copolymer in an ionic liquid (IL). The triblock copolymer contains two different lower critical solution temperature (LCST) thermosensitive polymers, poly(benzyl methacrylate) (PBnMA) and poly(2-phenylethyl methacrylate) (PPhEtMA), as the end blocks and poly(methyl methacrylate) (PMMA) as the middle block (PBnMA-b-PMMA-b-PPhEtMA: BMP). BMP undergoes a hierarchical phase transition corresponding to the self-assembly of each of the thermosensitive blocks in the IL, and a sol–gel transition was observed in concentrated, above 10 wt %, polymer solutions. The gelation behavior was affected by polymer concentration, and at 20 wt %, the BMP/IL composite showed a phase transition, with increasing temperature, from solution through a jammed micelle suspension to a physically cross-linked gel. For each phase was formed reversibly and rapidly over the corresponding temperature range. Finally, the jammed micelle and cross-linked gel states were characterized using viscoelastic measurements and small-angle X-ray scattering (SAXS).
36 MATERIALS SCIENCE↗
Small-angle neutron scattering study of a dense microemulsion system formed with an ionic liquid
Mixtures of water, octane and 1-octanol with 1-tetradecyl-3-methylimidazolium chloride (C14MIM·Cl), often referred to as a surface active ionic liquid (SAIL), form water-in-oil microemulsions that have potential application as extraction media for various metal ions. Here in this work, we present a structural study by small-angle neutron scattering (SANS) of dense microemulsions formed by surfactant-rich mixtures of these four compounds to understand how the SAIL can be used to tune the structures and properties of the microemulsions. The SANS experiments revealed that the microemulsions formed are composed of two phases, a water-in-oil microemulsion and a bicontinuous microemulsion, which becomes the dominant phase at high surfactant concentration. In this concentration regime, the surfactant film becomes more rigid, having a higher bending modulus that results from the parallel stacking of the imidazolium ring of the SAIL. At lower surfactant concentrations, the molecular packing of the SAIL does not change with the water content of the microemulsion. Finally, the results presented here correlate well with previously observed changes in the interaction between the IL cation and metal ions (Y. Tong, L. Han and Y. Yang, Ind. Eng. Chem. Res., 2012, 51, 16438–16443), while the capacity of the microemulsion system for water remains high enough for using the system as an extraction medium.
36 MATERIALS SCIENCE↗
A role for ion homeostasis in yeast ionic liquid tolerance
The model yeast Saccharomyces cerevisiae is being developed as a biocatalyst for the conversion of renewable lignocellulosic biomass into biofuels. The ionic liquid 1-ethyl-3-methylimidazolium chloride (EMIMCl) solubilizes lignocellulose for deconstruction into fermentable sugars, but it inhibits yeast fermentation. EMIMCl tolerance is mediated by the efflux pump Sge1p and uncharacterized protein Ilt1p. Through genetic investigation, we found that disruption of ion homeostasis through mutations in genes encoding the Trk1p potassium transporter and its protein kinase regulators, Sat4p and Hal5p, causes EMIMCl sensitivity. These results suggest that maintenance of ion homeostasis is important for tolerance to EMIMCl.
59 BASIC BIOLOGICAL SCIENCES↗
Exploring the Nature of f-Element Soft Donor Interactions Using Electronically Tunable Azolate Ionic Liquids
This project was undertaken to advance the understanding of how f-elements interact with moderately soft donors, a heavily investigated yet open question which is of prime importance in spent nuclear fuel processing and fundamental inorganic chemistry. During the course of the project, based on exciting results, a stretch goal was developed to study the hydrolysis products of transuranic actinide metals, a somewhat understudied field even with its significance in nuclear fuel cycle and impacts in environmental chemistry. The stretch goal was to take our serendipitous discovery of an easy route to isolation of crystalline multinuclear ƒ-element hydrolysis products, and apply it to gaining a mechanistic understanding of Pu(III/IV) colloid formation. The simplicity of our techniques should lend themselves to the remote handling required for study of many transuranic elements. We developed several methodologies using azolium azolate chemistry to overcome ƒ-element hydrolysis problems that prohibit the isolation of ƒ-element soft donor complexes and to build a crystallographic library of ƒ-element N-donor complexes as a means to understand the fundamental differences between actinide and lanthanide interactions with moderately soft donor ligands. Our next major endeavor will be to transfer this chemistry from 4ƒ elements to transuranic elements, particularly in the study of hydrolysis of Pu(III/IV). While our work is fundamental in nature, applications of the knowledge we are generating should be felt in such diverse fields as catalysis, separations in general, nuclear waste remediation specifically, and many other applications in f-element magnetic and luminescent properties. The potential ramifications of the consistent and robust formation of hydrolysis controlled hexanuclear lanthanide structures are enormous, with future uses being catalyst formation, higher-nuclearity structure synthesis using our hexanuclear motif as a fundamental building block, Pu waste remediation, separations, and many other potential applications resulting from characteristic magnetic and luminescent properties of lanthanide polynuclear structures. Three synthetic methodologies (direct mixing with variable stoichiometries, use of volatile solvent, metathesis) were developed starting with 7 acidic and 6 basic azoles to obtain ionic liquids suitable for f-element coordination. Proton transfer by acidic/basic azole combination led to suitable low melting salts and two cocrystals. Acid/base reaction of azoles with soft-donor permanent cations of ([X 4444 ][OH] (where [X 4444 ] + = tetrabutylammonium [N 4444 ] + or tetrabutylphosphonium [P 4444 ] + ) with weakly acidic azoles including imidazole, 1,2,3-triazole, 1,2,4-triazole, 5-aminotetrazole, 4,5-dicyanoimidazole, and 2-amino-4,5-dicyanoimidazole) revealed several suitable low-melting salts. Metathesis reactions of Na(azolate) were conducted by first using weakly acidic azoles including 4,5-dicyanoimidazole, 2-amino-4,5-dicyanoimidazole, 5-aminotetrazole, and 1,2,4-triazole to form sodium or lithium salts using group(I) hydroxides in methanolic solutions. The best results were obtained by reacting the basic and acidic azoles directly in 1:1 or 3:1 ratios at elevated temperatures. Twenty-two azole mixtures were identified which are either low melting solids or room temperature liquids. Each of the low melting solids was confirmed to be a new solid phase, each of which is being further characterized. The liquids and solids are anticipated to be ILs, eutectics, or partially ionized systems, all of which will be suitable for the dissolution of f-element salts. Five new synthetic methodologies were developed to finding suitable crystallization conditions for f-element complexation with the goal of finding simple one pot reaction syntheses and crystallization strategies that could be used under the demanding conditions of transuranic chemistries. These synthetic methods yield many new crystalline phases which were studied by single crystal X-ray diffraction.
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
Strategy for Extending the Stability of Bio‐oil‐Derived Phenolic Oligomers by Mild Hydrotreatment with Ionic‐Liquid‐Stabilized Nanoparticles
Abstract The development of catalytic transformations and processes is essential to utilize bio‐oil and lignin derivatives. Metal nanoparticles (M‐NPs) stabilized in ionic liquids (ILs) are promising for the catalytic hydrotreatment of bio‐oil because the properties of the catalyst system can be customized by combining the appropriate IL and metal nanoparticles. Herein, we demonstrate an experimental approach to stabilize lignin‐derived phenolics isolated from bio‐oil with ruthenium NPs stabilized by an ionic copolymer in 1‐ethyl‐3‐methylimidazolium acetate ([C 2 C 1 Im][OAc]). The mild hydrotreatment of phenolic oligomers (POs) was performed with the synthesized M‐NP catalyst at 100 °C for 6 h. Hydrotreatment of the POs resulted in enhanced thermal stability of the POs by as much as a factor of three, as determined by the aging index and by reducing reactive functionalities, which was also confirmed by NMR spectroscopy and GC analysis. The results support our hypothesis that M‐NPs stabilized in ILs can effectively stabilize POs under mild conditions, which could be applicable to any lignin‐derived phenolic.
Kim, Kwang Ho↗
Charging-driven coarsening and melting of a colloidal nanoparticle monolayer at an ionic liquid–vacuum interface
In this work, we induce and investigate the coarsening and melting dynamics of an initially static nanoparticle colloidal monolayer at an ionic liquid–vacuum interface, driven by a focused, scanning electron beam. Coarsening occurs through grain interface migration and larger-scale motions such as grain rotations, often facilitated by sliding dislocations. The progressive decrease in area fraction that drives melting of the monolayer is explained using an electrowetting model whereby particles at the interface are solvated once their accumulating charge recruits sufficient counterions to subsume the particle. Subject to stochastic particle removal from the monolayer, melting is recapitulated in simulations with a Lennard-Jones potential. This new driving mechanism for colloidal systems, whose dynamical timescales we show can be controlled with the accelerating voltage, opens the possibility to manipulate particle interactions dynamically without need to vary particle intrinsic properties or surface treatments. Furthermore, the decrease in particle size availed by electron imaging presents opportunities to observe force and time scales in a lesser-explored regime intermediate between typical colloidal and molecular systems.
36 MATERIALS SCIENCE↗
Ionic Liquids as Multi-Functional Lubricant Additives to Enhance Engine Efficiency (final report NFE-12-03876)
This ORNL-Shell CRADA developed and investigated ionic liquids (ILs) as multifunctional additives for next-generation low-viscosity engine oils. Several groups of oil-miscible ILs were successfully designed and synthesized with high thermal stability, non-corrosiveness, excellent wettability, and most importantly effective anti-scuffing/anti-wear and friction reduction characteristics. Synergistic effects between the common anti-wear additive zinc dialkyldithiophosphate (ZDDP) and a particular group of ILs were discovered with > 30% friction reduction and 70% wear reduction compared with using ZDDP or IL alone. The IL+ZDDP tribofilm distinguishes itself from the IL or ZDDP tribofilms with substantially higher contents of metal phosphates but less metal oxides and sulfur compounds. Notably, it was revealed that the actual concentrations of functional elements on the droplet surface of the oil containing IL+ZDDP are one order magnitude higher than their nominal values. Such significantly increased concentrations of anti-wear agents are presumably expected for the oilsolid interface and believed to be responsible for the superior lubricating performance. A prototype SAE 0W-16 engine oil using a synergistic IL+ZDDP pair as the anti-wear additive has been formulated based on the compatibility between the IL and other additives. Sequence VIE full-scale engine dynamometer tests demonstrated fuel economy improvement (FEI) for this prototype oil and revealed the individual contributions from the lower oil viscosity and reduced boundary friction. The impact of IL and IL+ZDDP on exhaust emission catalyst was investigated using an accelerated small engine aging test and results were benchmarked against ZDDP.
33 ADVANCED PROPULSION SYSTEMS↗
Preparation of graphene-Fe{sub 3}O{sub 4} nanocomposites using Fe{sup 3+} ion-containing magnetic ionic liquid
Graphene-Fe{sub 3}O{sub 4} (GN-Fe{sub 3}O{sub 4}) magnetic nanocomposites were prepared, GN-coated magnetic ionic liquid (MIL) as its precursors, which were used as both a magnetic resource and solvent. The method has proved to be valuable for the Fe{sub 3}O{sub 4} nanoparticles (NPs) well dispersed in the solution through strong interactions with GN, which are of interest because of their stability and chemical properties. In the process, strong interactions creates a condition for uniform dispersion in GN and [BMIm]FeCl{sub 4} (MIL) solution, and accelerate the formation of Fe{sub 3}O{sub 4} NPs. A transmission electron microscopy image has shown that the as-formed Fe{sub 3}O{sub 4} NPs with a diameter as small as 5–7 nm were deposited on GN sheets. Furthermore, the final material showed a superior properties than conventional method, which can be ascribed to the fact that [BMIm]FeCl{sub 4} plays a vital role in the process of producing small NPs size.
36 MATERIALS SCIENCE↗
Using a Chromatographic Pseudophase Model To Elucidate the Mechanism of Olefin Separation by Silver(I) Ions in Ionic Liquids
Silver(I) ions undergo selective olefin complexation and have been utilized in various olefin/paraffin separation techniques such as argentation chromatography and facilitated transport membranes. Ionic liquids (ILs) are solvents known for their low vapor pressure, high thermal stability, low melting points, and ability to promote a favorable solvation environment for silver(I) ion–olefin interactions. To develop highly selective separation systems, a fundamental understanding of analyte partitioning to the stationary phase and the thermodynamic driving forces behind solvation is required. In this study, a chromatographic model treating silver(I) ions as a pseudophase is constructed and employed for the first time to investigate the olefin separation mechanism in silver(I) salt/IL mixtures. Stationary phases containing varying amounts of noncoordinated silver(I) salt ([Ag + ][NTf 2 – ]) dissolved in the 1-decyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide ([C 10 MIM + ][NTf 2 – ]) IL are utilized to determine the partition coefficients of various analytes including alkanes, alkenes, alkynes, aromatics, aldehyde, esters, and ketones. As ligand coordination to silver(I) ions is known to lower its olefin complexation capability, this study also examines two different types of coordinated silver(I) ion pseudophases, namely, monocoordinated silver(I) salt ([Ag + (1-decyl-2-methylimidazole, DMIM)][NTf 2 – ]) and dicoordinated silver(I) salt ([Ag + (1-methylimidazole, MIM)(DMIM)][NTf 2 – ]). The extent of olefin partitioning to the coordinated silver(I) ion pseudophases over the carrier gas and IL decreased by up to two orders of magnitude. Values for enthalpy, entropy, and free energy of solvation were determined for the three silver(I) ion-containing systems. Olefin retention was observed to be enthalpically dominated, while ligand coordination to the silver(I) ion pseudophase resulted in variations for both enthalpic and entropic contributions to the free energy of solvation. Furthermore, the developed model can be used to study chemical changes that occur in silver(I) ions over time as well as identify optimal silver(I) salt/IL mixtures that yield high olefin selectivity.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Methyl quantum tunneling in ionic liquid [DMIm][TFSI] facilitated by Bis(trifluoromethane)sulfonimide lithium salt
Here, we probe, for the first time, quantum tunneling in the methyl groups of the ionic liquid [DMIm][TFSI] facilitated by the presence of Bis(trifluoromethane)sulfonimide lithium salt. The observation of tunneling is made possible by crystallization, rather than vitrification, of [DMIm][TFSI] at low temperature. Neutron scattering measurements detect quantum tunneling excitations at ~27 μeV at temperatures below 30 K in the presence of LiTFSI at a concentration of 1 mol/kg, but not in salt-free [DMIm][TFSI]. This indicates that the methyl rotational potential barrier is reduced by the presence of LiTFSI, thus bringing the tunneling excitations into the measurable range. The salt-induced reduction of the rotational barrier is corroborated by quasi-elastic scattering data associated with stochastic re-orientation of methyl groups measured between 40 and 60 K.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Preparation and comparison of bulk and membrane hydrogels based on Kraft- and ionic-liquid-isolated lignins
In this work, lignin obtained from two different sources, from the Kraft process (KF-lignin) and from dissolution of wood using ionic liquid (IL-lignin), was dissolved in alkaline solution and crosslinked with different methods, attempting to form bulk and membrane hydrogels. Without a chemical crosslinker, no physical lignin gels could be formed. When employing three different chemically crosslinking routes, epichlorohydrin (ECH), polyethylene glycol (PEG)/ECH, and epoxide-terminated PEG (ETPEG), only the third route produced “hydrogels” with excellent water absorbency. To form a hydrogel, lower IL-lignin concentration (15 wt%) was needed than for KF-lignin (20 wt%). Once air-dried, both of the dense lignin/ETPEG gels showed comparable high tensile strength, independent of the type of lignin. However, while in the wet state, the IL-lignin/ETPEG hydrogels were much stronger than those from KF-lignin, thus facilitating their preparation and utilization. High water uptake was observed for all lignin/ETPEG gels, although a smaller swelling was observed with IL-lignin gels. Additionally, water vapor transmission (WVT), antioxidant efficiency, and antimicrobial activity of the membranes were determined and these data suggest their potential application as food packaging or wound dressing materials, especially for the IL-lignin membranes considering their easier formation, higher WVT, antioxidant efficiency, and wet strength.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗
Investigating the effect of ligand and cation on the properties of metal fluorinated acetylacetonate based magnetic ionic liquids
The effect of chemical structure on various physiochemical properties including thermal stability, solvent miscibility, magnetic susceptibility and viscosity is studied for acetylacetone based magnetic ionic liquids.
36 MATERIALS SCIENCE↗
Theory-augmented informatics of ionic liquid electrolytes for co-design with nanoporous electrode materials
We propose a figure of merit to evaluate electrochemical performance in nanoporous electrodes to screen ionic liquid candidates by combining density functional theory with informatics to co-optimize voltage window, viscosity, and pore-ion size matching.
25 ENERGY STORAGE↗
Methyl Ketones from Municipal Solid Waste Blends by One‐Pot Ionic‐Liquid Pretreatment, Saccharification, and Fermentation
Abstract The conversion of municipal solid waste (MSW) and lignocellulosic biomass blends to methyl ketones (MKs) was investigated by using bioderived ionic liquid (bionic liquid)‐based hydrolysates followed by fermentation with an engineered Escherichia coli strain. The hydrolysates were produced by a one‐pot process using six types of MSW–biomass blends, choline‐based bionic liquids, and commercial enzymes. Based on the sugar yields, one blend (corn stover/MSW=95:5, w / w ) and two bionic liquids {cholinium lysinate ([Ch][Lys]) and cholinium aspartate ([Ch] 2 [Asp])} were selected for scale‐up studies. Maximum yields of 82.3 % glucose and 54.4 % xylose were obtained from the selected blend in the scale‐up studies (6 L), which was comparable with 83.6 % glucose and 52.8 % xylose obtained at a smaller scale (0.2 L). Comparable or higher yields of medium‐chain (C 11 –C 17 ) MKs were achieved by using the MSW–biomass blend‐derived hydrolysates, relative to the sugar controls (glucose and xylose) with similar sugar feeding concentrations. Up to 1145 mg L −1 of MKs was produced by using MSW–biomass‐derived hydrolysates, and the MK titer decreased to 300 mg L −1 when the bionic‐liquid concentration in the hydrolysate increased from 1 to 2 %, indicative of bionic‐liquid inhibition. Technoeconomic analysis was conducted to investigate the economic potential of using the selected MSW–biomass blend as a feedstock to produce MKs.
Yan, Jipeng↗
Adhesion and Toxicity of Polymers Prepared Using Ionic Liquid Monomers
The focus of this research was to investigate possible applications of crosslinked polymers that could be prepared through free-radical polymerization of protic ionic liquid monomers. These monomers were synthesized through reactions of selected Bronsted acids and bases, and then polymerized with and without the aid of a free-radical initiator. It was discovered that these polymers had potential applications as adhesives, and bond strengths of various formulations were tested and compared with commercially available adhesives. Additionally, potential environmental toxicity of these polymers was investigated by performing zone of inhibition testing with select bacteria. It was determined that several of these polymers have comparable or superior bond strengths to other common adhesives, although monomer type and initiator concentration can impact these strengths. Toxicity was also dependent on these factors, with some formulations showing high toxicity and others showing few toxic effects.
36 MATERIALS SCIENCE↗
Comparison of autohydrolysis and ionic liquid 1-butyl-3-methylimidazolium acetate pretreatment to enhance enzymatic hydrolysis of sugarcane bagasse
The aim of this work was to evaluate the efficiency of an ionic liquid (IL) 1-butyl-3-methylimidazolium acetate ([C4mim][OAc]) pretreatment (110 C for 30 min) in comparison to high severity autohydrolysis pretreatment in terms of delignification, cellulose crystallinity and enzymatic digestibility. The increase in severity of autohydrolysis pretreatment had positive effect on glucan digestibility, but was limited by the crystallinity of cellulose. [C4mim][OAc] pretreated sugarcane bagasse exhibited a substantial decrease in lignin content, reduced cellulose crystallinity, and enhanced glucan and xylan digestibility. Glucan and xylan digestibility was determined as 97.4% and 98.6% from [C4mim][OAc] pretreated bagasse, and 62.1% and 57.5% from the bagasse autohydrolyzed at 205 C for 6 min, respectively. The results indicated the improved digestibility and hydrolysis rates after [C4mim][OAc] pretreatment when compared against a comparable autohydrolyzed biomass.
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗