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Sample records for room-temperature ionic liquid

  1. A room temperature spin crossover ionic liquid.

    PubMed

    Fitzpatrick, Anthony J; O'Connor, Helen M; Morgan, Grace G

    2015-12-28

    Two new paramagnetic ionic liquids (ILs) comprising a mononuclear iron(iii) or manganese(iii) complex cation, charge balanced by a dicyanamide anion are reported which show a range of spin states. Both are liquids at room temperature and the Fe(iii) based IL exhibits a spin crossover close to 300 K. The spin crossover profile is independent of the solvation, and is both air and moisture stable. PMID:26599842

  2. Water in Room Temperature Ionic Liquids

    NASA Astrophysics Data System (ADS)

    Fayer, Michael

    2014-03-01

    Room temperature ionic liquids (or RTILs, salts with a melting point below 25 °C) have become a subject of intense study over the last several decades. Currently, RTIL application research includes synthesis, batteries, solar cells, crystallization, drug delivery, and optics. RTILs are often composed of an inorganic anion paired with an asymmetric organic cation which contains one or more pendant alkyl chains. The asymmetry of the cation frustrates crystallization, causing the salt's melting point to drop significantly. In general, RTILs are very hygroscopic, and therefore, it is of interest to examine the influence of water on RTIL structure and dynamics. In addition, in contrast to normal aqueous salt solutions, which crystallize at low water concentration, in an RTIL it is possible to examine isolated water molecules interacting with ions but not with other water molecules. Here, optical heterodyne-detected optical Kerr effect (OHD-OKE) measurements of orientational relaxation on a series of 1-alkyl-3-methylimidazolium tetrafluoroborate RTILs as a function of chain length and water concentration are presented. The addition of water to the longer alkyl chain RTILs causes the emergence of a long time bi-exponential orientational anisotropy decay. Such decays have not been seen previously in OHD-OKE experiments on any type of liquid and are analyzed here using a wobbling-in-a-cone model. The orientational relaxation is not hydrodynamic, with the slowest relaxation component becoming slower as the viscosity decreases for the longest chain, highest water content samples. The dynamics of isolated D2O molecules in 1-butyl-3-methylimidazolium hexafluorophosphate (BmImPF6) were examined using two dimensional infrared (2D IR) vibrational echo spectroscopy. Spectral diffusion and incoherent and coherent transfer of excitation between the symmetric and antisymmetric modes are examined. The coherent transfer experiments are used to address the nature of inhomogeneous broadening by observing ~ 100 fs time scale oscillations in the shape of the 2D IR spectra.

  3. BIOELECTROCATALYTIC REACTIONS IN ROOM TEMPERATURE IONIC LIQUIDS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The direct electrochemical reduction of hemin, protopophyrin(IX) iron(III) chloride, ligated with strong or weak heterocyclic bases, was investigated in the ionic liquids (ILs), 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) and 1-octyl-3-methylimidazolium hexafluorophosphate ([omim][...

  4. Room-Temperature Ionic Liquids for Electrochemical Capacitors

    NASA Technical Reports Server (NTRS)

    Fireman, Heather; Yowell, Leonard; Moloney, Padraig G.; Arepalli, Sivaram; Nikolaev, P.; Huffman, C.; Ready, Jud; Higgins, C.D.; Turano, S. P.; Kohl, P.A.; Kim, K.

    2009-01-01

    A document discusses room-temperature ionic liquids (RTILs) used as electrolytes in carbon-nanotube-based, electrochemical, double-layer capacitors. Unlike the previous electrolyte (EtNB4 in acetonitrile), the RTIL used here does not produce cyanide upon thermal decomposition and does not have a moisture sensitivity.

  5. Radiation stability of some room temperature ionic liquids

    NASA Astrophysics Data System (ADS)

    Jagadeeswara Rao, Ch.; Venkatesan, K. A.; Tata, B. V. R.; Nagarajan, K.; Srinivasan, T. G.; Vasudeva Rao, P. R.

    2011-05-01

    Radiation stability of some room temperature ionic liquids (RTILs) that find useful electrochemical applications in nuclear fuel cycle has been evaluated. The ionic liquids such as protonated betaine bis(trifluoromethylsulfonyl)imide (HbetNTf 2), aliquat 336 (tri-n-octlymethylammonium chloride), 1-butyl-3-methylimidazolium chloride (bmimCl), 1-hexyl-3-methylimidazolium chloride (hmimCl), N-butyl-N-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BMPyNTf 2) and N-methyl-N-propylpiperidinium bis(trifluoromethylsulfonyl)imide (MPPiNTf 2) have been irradiated to various absorbed dose levels, up to 700 kGy. The effect of gamma radiation on these ionic liquids has been evaluated by determining the variations in the physical properties such as color, density, viscosity, refractive index and electrochemical window. The changes in density, viscosity and refractive index of these ionic liquids upon irradiation were insignificant; however, the color and electrochemical window varied significantly with increase of absorbed dose.

  6. Dynamics and structure of room temperature ionic liquids

    NASA Astrophysics Data System (ADS)

    Fayer, Michael D.

    2014-11-01

    Room temperature ionic liquids (RTIL) are intrinsically interesting because they simultaneously have properties that are similar to organic liquids and liquid salts. In addition, RTILs are increasingly being considered for and used in technological applications. RTILs are usually composed of an organic cation and an inorganic anion. The organic cation, such as imidazolium, has alkyl chains of various lengths. The disorder in the liquid produced by the presence of the alkyl groups lowers the temperature for crystallization below room temperature and can also result in supercooling and glass formation rather than crystallization. The presence of the alkyl moieties also results in a segregation of the liquid into ionic and organic regions. In this article, experiments are presented that address the relationship between RTIL dynamics and structure. Time resolved fluorescence anisotropy measurements were employed to study the local environments in the organic and ionic regions of RTILs using a nonpolar chromophore that locates in the organic regions and an ionic chromophore that locates in the ionic regions. In the alkyl regions, the in plane and out of plane orientational friction coefficients change in different manners as the alkyl chains get longer. Both friction coefficients converge toward those of a long chain length hydrocarbon as the RTIL chains increase in length, which demonstrates that for sufficiently long alkyl chains the RTIL organic regions have properties similar to a hydrocarbon. However, putting Li+ in the ionic regions changes the friction coefficients in the alkyl regions, which demonstrates that changes of the ion structural organization influences the organization of the alkyl chains. Optical heterodyne detected optical Kerr effect (OHD-OKE) experiments were used to examine the orientational relaxation dynamics of RTILs over times scales of a hundred femtoseconds to a hundred nanoseconds. Detailed temperature dependent studies in the liquid and supercooled state and analysis using schematic mode coupling theory (MCT) show that RTILs have bulk liquid orientational relaxation dynamics that are indistinguishable in their nature from common nonpolar organic liquids that supercool. This behavior of the RTILs occurs in spite of the segregation into ionic and organic regions. However, when small amounts of water are added to RTILs at room temperature, novel dynamics are observed for the RTILs with long alkyl chains that have not been observed in OHD-OKE experiments on organic liquids. The results are interpreted as water induced structure in the ionic regions that causes the long alkyl chains to organize and 'lock up.' The dynamical measurements indicate that this lock up is involved in the formation of RTIL gels that occur over a narrow range of water concentrations.

  7. Pressure-responsive mesoscopic structures in room temperature ionic liquids.

    PubMed

    Russina, Olga; Celso, Fabrizio Lo; Triolo, Alessandro

    2015-11-28

    Among the most spectacular peculiarities of room temperature ionic liquids, their mesoscopically segregated structural organization keeps on attracting attention, due to its major consequences for the bulk macroscopic properties. Herein we use molecular dynamics simulations to explore the nm-scale architecture in 1-octyl-3-methylimidazolium tetrafluoroborate, as a function of pressure. This study reveals an intriguing new feature: the mesoscopic segregation in ionic liquids is characterized by a high level of pressure-responsiveness, which progressively vanishes upon application of high enough pressure. These results are in agreement with recent X-ray scattering data and are interpreted in terms of the microscopic organization. This new feature might lead to new methods of developing designer solvents for enhanced solvation capabilities and selectivity. PMID:26498176

  8. Acoustic Desorption from a Room Temperature Ionic Liquid.

    NASA Astrophysics Data System (ADS)

    Harris, Peter; Tracy, Eugene; Cooke, William

    2007-06-01

    We use laser induced acoustic pulses to efficiently desorb ions from a Room Temperature Ionic Liquid (RTIL) in vacuum. Our RTIL, 1-butyl-3-methylimidazolium hexafluorophosphate, remains a stable liquid at pressures exceeding 10-9 torr. We use the 2^nd harmonic of a Nd:YAG laser, 2ns pulse time, to generate acoustic pulses via laser ablation of the backside of a metal foil. Both negative and positive ions are desorbed from the liquid RTIL surface on the front side of the foil. The m/q of ejected ions is detected via TOF measurements from an imaging micro-channel plate detector. We measure the time our acoustic pulse reaches the RTIL surface by detecting the ejected electron signal. We present data showing the variation of desorbed ion yield as a function of the amplitude and shape of the incident acoustic pulse.

  9. Contracting cardiomyocytes in hydrophobic room-temperature ionic liquid

    SciTech Connect

    Hoshino, Takayuki; Department of Bio-Application and System Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei-shi, Tokyo 184-8588 ; Fujita, Kyoko; Higashi, Ayako; Sakiyama, Keiko; Ohno, Hiroyuki; Morishima, Keisuke; Department of Bio-Application and System Engineering, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei-shi, Tokyo 184-8588

    2012-10-19

    Highlights: Black-Right-Pointing-Pointer Biocompatible room-temperature ionic liquid was applied on beating cardiomyocyte. Black-Right-Pointing-Pointer The lifetime of beating cardiomyocytes was depended on anion functional group. Black-Right-Pointing-Pointer A longer lifetime was recorded for no functional group on alkyl chain on their anion. Black-Right-Pointing-Pointer Amino group on alkyl chain and fluorine in anion induced fatal condition changes. Black-Right-Pointing-Pointer We reported liquid electrolyte interface to stimulate cardiomyocytes. -- Abstract: Room-temperature ionic liquids (RTILs) are drawing attention as a new class of nonaqueous solvents to replace organic and aqueous solvents for chemical processes in the liquid phase at room temperature. The RTILs are notable for their characteristics of nonvolatility, extremely low vapor pressure, electric conductivity, and incombustibility. These distinguished properties of RTILs have brought attention to them in applications with biological cells and tissue in vacuum environment for scanning electron microscopy, and in microfluidic devices for micro-total analysis system (micro-TAS). Habitable RTILs could increase capability of nonaqueous micro-TAS for living cells. Some RTILs seemed to have the capability to replace water in biological applications. However, these RTILs had been applied to just supplemental additives for biocompatible test, to fixed cells as a substitute for an aqueous solution, and to simple molecules. None of RTILs in which directly soaks a living cell culture. Therefore, we demonstrated the design of RTILs for a living cell culture and a liquid electrolyte to stimulate contracting cardiomyocytes using the RTILs. We assessed the effect of RTILs on the cardiomyocytes using the beating lifetime to compare the applicability of RTILs for biological applications. Frequent spontaneous contractions of cardiomyocytes were confirmed in amino acid anion RTILs [P{sub 8,8,8,8}][Leu] and [P{sub 8,8,8,8}][Ala], phosphoric acid derivatives [P{sub 8,8,8,8}][MeO(H)PO{sub 2}], and [P{sub 8,8,8,8}][C{sub 7}CO{sub 2}]. The anion type of RTILs had influence on applicable characteristics for the contracting cardiomyocyte. This result suggested the possibility for biocompatible design of hydrophobic group RTILs to achieve biological applications with living cells.

  10. Acoustic Desorption from a Room Temperature Ionic Liquid.

    NASA Astrophysics Data System (ADS)

    Harris, Peter; Tracy, Eugene; Cooke, William

    2007-11-01

    We report on the acoustic desorption of ions from the surface of a room temperature ionic liquid (RTIL) under vacuum. Our RTIL, 1-butyl-3-methylimidazolium hexafluorophosphate, remains a stable liquid at extremely low pressures (<10-9 torr). Using the 2^nd harmonic of a Nd:YAG laser, 2ns pulse time, we ablate the backside of a metal foil, generating an acoustic pulse that propagates through the foil, desorbing ions off the surface of the RTIL. We determine the m/q of desorbed ions via time of flight (TOF) measurements from an imaging micro-channel plate detector. We detect both positive and negative ion species, depending on the extraction and acceleration voltages. Our TOF spectra demonstrate our acoustic pulses are of short duration (<20ns), generating mass spectra with good temporal resolution (<40ns FWHM @ t=9000ns), that are stable and reproducible. We discuss the variation of desorbed ion yield as a function of acoustic pulse strength, metal foil properties and extraction fields.

  11. Proactive aquatic ecotoxicological assessment of room-temperature ionic liquids

    USGS Publications Warehouse

    Kulacki, K.J.; Chaloner, D.T.; Larson, J.H.; Costello, D.M.; Evans-White, M. A.; Docherty, K.M.; Bernot, R.J.; Brueseke, M.A.; Kulpa, C.F.; Lamberti, G.A.

    2011-01-01

    Aquatic environments are being contaminated with a myriad of anthropogenic chemicals, a problem likely to continue due to both unintentional and intentional releases. To protect valuable natural resources, novel chemicals should be shown to be environmentally safe prior to use and potential release into the environment. Such proactive assessment is currently being applied to room-temperature ionic liquids (ILs). Because most ILs are water-soluble, their effects are likely to manifest in aquatic ecosystems. Information on the impacts of ILs on numerous aquatic organisms, focused primarily on acute LC50 and EC50 endpoints, is now available, and trends in toxicity are emerging. Cation structure tends to influence IL toxicity more so than anion structure, and within a cation class, the length of alkyl chain substituents is positively correlated with toxicity. While the effects of ILs on several aquatic organisms have been studied, the challenge for aquatic toxicology is now to predict the effects of ILs in complex natural environments that often include diverse mixtures of organisms, abiotic conditions, and additional stressors. To make robust predictions about ILs will require coupling of ecologically realistic laboratory and field experiments with standard toxicity bioassays and models. Such assessments would likely discourage the development of especially toxic ILs while shifting focus to those that are more environmentally benign. Understanding the broader ecological effects of emerging chemicals, incorporating that information into predictive models, and conveying the conclusions to those who develop, regulate, and use those chemicals, should help avoid future environmental degradation. ?? 2011 Bentham Science Publishers Ltd.

  12. Alkylsulfuric acid ionic liquids: a promising class of strongly acidic room-temperature ionic liquids.

    PubMed

    Dupont, David; Renders, Evelien; Binnemans, Koen

    2016-03-17

    Strongly acidic (pKa ≈ -3.5) room-temperature ionic liquids (ILs) with -OSO3H functionalized cations are introduced. The strong acidity, easy synthesis, and better physical properties of these R-OSO3H ILs make them excellent alternatives to the well-known sulfonic acid (R-SO3H) ILs, especially in the domain of metal processing. PMID:26947544

  13. Applications of room temperature ionic liquids in interfacial polymerization

    NASA Astrophysics Data System (ADS)

    Zhu, Lining

    2006-12-01

    Room temperature ionic liquids (ILs), with their unique physical and chemical properties, have been of great interest in various areas of chemical science and engineering during the last decade. In this dissertation, polyurea and polyamide films with surface nanostructures were synthesized by interfacial polymerization (IP) with ILs without stirring. Both polymers were prepared at the interface between n-hexane and a series of 1-alkyl-3-methylimidazolium ILs. Nanoporous or nanofibrous polymer morphologies with various sizes ranging from 50 to 500 nm and geometries, depending on the ILs used, were observed by scanning electron microscopy (SEM). A correlation length of 20nm and a suppression of three-dimensional (3-D) crystalline structure of the polyurea were found by small angle X-ray scattering (SAXS) and X-ray diffraction (XRD), respectively. FTIR spectra showed no significant changes in the chemical composition of the polymer by the employment of ILs. The peculiar nanostructure of the polymer could be ascribed to the intermolecular interactions between the ILs and the polymer, which affected the development of the polymer morphology. The polyamides prepared with ILs showed larger intrinsic viscosities, and consequently higher molecular weights, compared to the one prepared without ILs; this could be due to the prevention of the side reaction between sebacoyl chloride and water. The enhancement of the molecular weight renders a better thermal stability to the polyamide film, as revealed by thermogravimetric analysis (TGA) which showed a higher decomposition temperature. Coating of fine particulates with polyurea by IP has been developed. With increasing stirring speed in the coating process, a decreased mean particle size and a narrower particle size distribution, as well as a lower coating weight percentage were found by particle size analysis and TGA, respectively. A Porous coating layer was formed in the IP coating in the presence of ILs. The reaction kinetics of Nylon 610 film formation with ILs were studied by measuring the product mass at different reaction times. The polymer film ceased to grow in the late stage of the reaction due to the diffusion barrier formed by the film. The characteristic time marking the cessation of the film growth was found to be dependent on the initial reactant concentrations. The evolution of the polymer molecular weight with reaction time was monitored by intrinsic viscosity measurements. It is found that the molecular weight leveled off faster than the film growth under the same reactant concentrations. Based on our experimental studies, a simplified diffusion-controlled mathematical model of IP with ILs was developed, in which the effective diffusivity in the polymer film decayed with the square of time. The model was used to fit the measured growth rate of the polymer film and the fitting results showed a conspicuously good agreement between the model and the experimental data. Physical properties of ILs relevant to the biphasic systems were also studied in this work. The interfacial tensions between organic solvents and ILs were found to decrease with ascending alkyl chain length attached to the imidazolium cations. In general, the interfacial tensions between ILs and aromatic solvents are lower than the ones with aliphatic solvents; this is attributed to the pi-pi interactions between ILs and the aromatic solvent. Self-aggregation of IL molecules in aqueous solutions and self-aggregation of ethanol in ILs are suggested based on the interfacial tension measurements. These properties are important in multi-phase chemical processes. Our study has demonstrated the potential application of ionic liquids in the interfacial polymerization of polymers with nanoscale structures.

  14. Are Room-Temperature Ionic Liquids Dilute Electrolytes?

    PubMed

    Lee, Alpha A; Vella, Dominic; Perkin, Susan; Goriely, Alain

    2015-01-01

    An important question in understanding the structure of ionic liquids is whether ions are truly "free" and mobile, which would correspond to a concentrated ionic melt, or are rather "bound" in ion pairs, that is, a liquid of ion pairs with a small concentration of free ions. Recent surface force balance experiments from different groups have given conflicting answers to this question. We propose a simple model for the thermodynamics and kinetics of ion pairing in ionic liquids. Our model takes into account screened ion-ion, dipole-dipole, and dipole-ion interactions in the mean-field limit. The results of this model suggest that almost two-thirds of the ions are free at any instant, and ion pairs have a short lifetime comparable to the characteristic time scale for diffusion. These results suggest that there is no particular thermodynamic or kinetic preference for ions to reside in pairs. We therefore conclude that ionic liquids are concentrated, rather than dilute, electrolytes. PMID:26263105

  15. Isomer effect of propanol on liquid-liquid equilibrium in hydrophobic room-temperature ionic liquids

    NASA Astrophysics Data System (ADS)

    Ozawa, Shinichiro; Kishimura, Hiroaki; Kitahira, Shota; Tamatani, Kentaro; Hirayama, Kentaro; Abe, Hiroshi; Yoshimura, Yukihiro

    2014-10-01

    The cloud-point temperature determined the liquid-liquid phase equilibrium (LLE) of binary systems comprising hydrophobic room-temperature ionic liquids (RTILs) and propanol. The RTILs were 1-alkyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, [Cxmim][TFSI] (2 ? x ? 10). Upper critical solution temperatures in LLE are inversely proportional to the Cxmim+ cation alkyl chain length, x. The propanol isomer effect indicates the critical alkyl chain length (xcritical = 6-7). UNIQUAC model determined the interaction parameters (with crossing points at x = 6). In pure RTILs, conformation stability of TFSI- by Raman spectroscopy changed between x = 6 and 7, corresponding to the simulation-determined 90-torsion angle at x = 6.

  16. Static and transport properties of alkyltrimethylammonium cation-based room-temperature ionic liquids.

    PubMed

    Seki, Shiro; Tsuzuki, Seiji; Hayamizu, Kikuko; Serizawa, Nobuyuki; Ono, Shimpei; Takei, Katsuhito; Doi, Hiroyuki; Umebayashi, Yasuhiro

    2014-05-01

    We have measured physicochemical properties of five alkyltrimethylammonium cation-based room-temperature ionic liquids and compared them with those obtained from computational methods. We have found that static properties (density and refractive index) and transport properties (ionic conductivity, self-diffusion coefficient, and viscosity) of these ionic liquids show close relations with the length of the alkyl chain. In particular, static properties obtained by experimental methods exhibit a trend complementary to that by computational methods (refractive index ? [polarizability/molar volume]). Moreover, the self-diffusion coefficient obtained by molecular dynamics (MD) simulation was consistent with the data obtained by the pulsed-gradient spin-echo nuclear magnetic resonance technique, which suggests that computational methods can be supplemental tools to predict physicochemical properties of room-temperature ionic liquids. PMID:24702446

  17. Photoinduced intermolecular electron transfer in a room temperature imidazolium ionic liquid: An excitation wavelength dependence study

    NASA Astrophysics Data System (ADS)

    Sarkar, Souravi; Pramanik, Rajib; Ghatak, Chiranjib; Rao, Vishal Govind; Sarkar, Nilmoni

    2011-04-01

    In this work we have reported the photoinduced intermolecular electron transfer reaction from N, N-dimethylaniline to different Coumarin dyes in a neat room temperature imidazolium ionic liquid, 1-ethyl-3-methylimidazolium-bis (trifluoromethylsulfonyl) imide ([Emim][Tf 2N]) and observed a difference in electron transfer rate with the variation of excitation wavelengths. We have also observed an excitation wavelength dependent solvation dynamics in this ionic liquid media. The excitation wavelength dependence is attributed to the presence of structural heterogeneity in this neat ionic liquid media. The electron transfer rate vs free energy correlation curve show a retardation in the electron transfer rate at higher free energy region.

  18. NafionxAE-based polymer actuators with ionic liquids as solvent incorporated at room temperature

    NASA Astrophysics Data System (ADS)

    Kikuchi, Kunitomo; Tsuchitani, Shigeki

    2009-09-01

    Nafion-based ionic polymer-metal composites (IPMCs), with ionic liquids as solvent, were fabricated by exchanging counterions to ionic liquids at room temperature. Ion exchange is performed by only immersing IPMC in a mixture of de-ionized water and ionic liquids at room temperature for 48 h. The fabricated IPMCs exhibited a bending curvature the same as or larger than that of conventional IPMCs with ionic liquids, formed by ion exchange to ionic liquids at an elevated temperature up to about 100 C, and also had long-term stability in operation in air, with a fluctuation smaller than 21% in bending curvature during a 180 min operation. The effective ion exchange to ionic liquids in the present method is probably due to an increase in diffusion speed of ionic liquids into IPMC by adsorption of water in a Nafion membrane. It is a surprise that among IPMCs with ionic liquids 1-ethyl-3-methyl-imidazolium tetrafluoroborate, 1-buthyl-3-methyl-imidazolium tetrafluoroborate (BMIBF4), and 1-buthyl-3-methyl-imidazolium hexafluorophosphate (BMIPF6), IPMC with water-insoluble BMIPF6 exhibited a larger bending curvature than that IPMC with water-miscible BMIBF4. This might be due to effective incorporation of BMIPF6 into IPMC, since BMIPF6 has a higher affinity with IPMC than with water in the mixture of water and BMIPF6. From measurements of complex impedance and step voltage response of the driving current of IPMCs with ionic liquid, they are expressed by an equivalent circuit of a parallel combination of a serial circuit of membrane resistance of Nafion and electric double layer capacitance at metal electrodes, with membrane capacitance of Nafion, in a frequency range higher than about 0.1 Hz. The difference in magnitude of bending curvature in three kinds of IPMCs with ionic liquids is mainly due to the difference in bending response speed coming from the difference in the membrane resistance.

  19. Anion pairs in room temperature ionic liquids predicted by molecular dynamics simulation, verified by spectroscopic characterization

    SciTech Connect

    Schwenzer, Birgit; Kerisit, Sebastien N.; Vijayakumar, M.

    2014-01-01

    Molecular-level spectroscopic analyses of an aprotic and a protic room-temperature ionic liquid, BMIM OTf and BMIM HSO4, respectively, have been carried out with the aim of verifying molecular dynamics simulations that predict anion pair formation in these fluid structures. Fourier-transform infrared spectroscopy, Raman spectroscopy and nuclear magnetic resonance spectroscopy of various nuclei support the theoretically-determined average molecular arrangements.

  20. Decoupling charge transport from the structural dynamics in room temperature ionic liquids

    SciTech Connect

    Griffin, Phillip; Agapov, Alexander L; Kisliuk, Alexander; Sun, Xiao-Guang; Dai, Sheng; Novikov, Vladimir; Sokolov, Alexei P

    2011-01-01

    Light scattering and dielectric spectroscopy measurements were performed on the room temperature ionic liquid (RTIL) [C4mim][NTf2] in a broad temperature and frequency range. Ionic conductivity was used to estimate self-diffusion of ions, while light scattering was used to study structural relaxation. We demonstrate that the ionic diffusion decouples from the structural relaxation process as the temperature of the sample decreases toward Tg. The strength of the decoupling appears to be significantly lower than that expected for a supercooled liquid of similar fragility. The structural relaxation process in the RTIL follows well the high-temperature mode coupling theory (MCT) scenario. Using the MCT analysis we estimated the dynamic crossover temperature in [C4mim][NTf2] to be Tc 225 5 K. However, our analysis reveals no sign of the dynamic crossover in the ionic diffusion process.

  1. Polymer electrolytes based on room temperature ionic liquid: 2,3-dimethyl-1-octylimidazolium triflate.

    PubMed

    Singh, Boor; Sekhon, S S

    2005-09-01

    Room temperature ionic liquid (DMOImTf) based upon 2,3-dimethyl-1-octylimidazolium cation and trifluoromethanesulfonate or triflate (CF(3)SO(3))(-) anion has been synthesized and shows conductivity of 5.68 mS/cm and viscosity of 26.4 cP at 25 degrees C. Ion conducting polymer electrolytes based on polymers (poly(ethylene oxide) (PEO) and polyvinylidenefluoride-co-hexafluoropropylene (PVdF-HFP)) and ionic liquid (DMOImTf) were prepared in film form by the casting technique. The conductivity of polymer electrolytes containing 0.5 M LiCF(3)SO(3) in PEO:DMOImTf taken in equal weight ratio increases with the addition of propylene carbonate (PC) while its mechanical stability improved by dispersing nanosize fumed silica. However, polymer electrolytes containing PVdF-HFP and ionic liquid show a high value of conductivity (10(-4)-10(-3) S/cm) alongwith better mechanical stability. PMID:16853102

  2. DEVELOPMENT OF ROOM TEMPERATURE IONIC LIQUIDS FOR APPLICATIONS IN ACTINIDE CHEMISTRY

    SciTech Connect

    W. OLDHAM; D. COSTA; W. SMITH

    2001-05-01

    One area of on-going research in our group at Los Alamos National Laboratory is directed toward characterization of the basic coordination chemistry and electrochemical behavior of f-element ions dissolved in room temperature ionic liquids (RTILs). The ultimate goal of this work is to introduce advanced, environmentally sustainable, nuclear processing and purification strategies into both the DOE complex and the civilian nuclear industry. Efforts to develop ambient temperature electrorefining and/or electrowinning technologies are focused on the design of ionic liquids characterized by extended cathodic stability. In this chapter a summary of the synthesis, physical properties and electrochemical behavior of the ionic liquids used in this work is presented. The feasibility of efficient electrochemical production of high electropositive metals is demonstrated through reversible plating and stripping of sodium and potassium metals.

  3. Supported Room Temperature Ionic Liquid Membranes for CO{sub 2}/CH{sub 4} Separation

    SciTech Connect

    Iarikov, D. D.; Hacarlioglu, P.; Oyama, S. T.

    2011-01-01

    Room temperature ionic liquids (RTILs) are organic salts which are liquid at or around room temperature. These compounds exhibit many outstanding physical properties such as great thermal stability and no measurable vapor pressure. In this work supported ionic liquid membranes (SILMs) were prepared by impregnating pores of α-alumina inorganic supports with various ionic liquids. In addition to membranes prepared with pure RTILs we were able to synthesize membranes with RTIL mixtures using 1-aminopyridinium iodide dissolved in 1-butyl-4-methylpyridinium tetrafluoroborate or methyltrioctylammonium bis(trifluoromethylsulfonyl)imide. This combination of an RTIL with an organic salt containing an amine group dramatically improved the membrane separation properties. The SILMs displayed CO{sub 2} permeance on the order of 5 × 10{sup −10} to 5 × 10{sup −9} mol m{sup −2} s{sup −1} Pa{sup −1} combined with CO{sub 2}/CH{sub 4} selectivity of 5–30. Although these values are comparable with the current systems for CO{sub 2} purification, CO{sub 2} permeance is still rather low for these compounds.

  4. Reversible swelling of the cell wall of poplar biomass by ionic liquid at room temperature.

    PubMed

    Lucas, Marcel; Wagner, Greg L; Nishiyama, Yoshiharu; Hanson, Leif; Samayam, Indira P; Schall, Constance A; Langan, Paul; Rector, Kirk D

    2011-03-01

    Time-resolved autofluorescence, Raman microspectroscopy, and scanning microprobe X-ray diffraction were combined in order to characterize lignocellulosic biomass from poplar trees and how it changes during treatment with the ionic liquid 1-n-ethyl-3-methylimidazolium acetate (EMIMAC) at room temperature. The EMIMAC penetrates the cell wall from the lumen, swelling the cell wall by about a factor of two towards the empty lumen. However, the middle lamella remains unchanged, preventing the cell wall from swelling outwards. During this swelling, most of the cellulose microfibrils are solubilized but chain migration is restricted and a small percentage of microfibrils persist. When the EMIMAC is expelled, the cellulose recrystallizes as microfibrils of cellulose I. There is little change in the relative chemical composition of the cell wall after treatment. The action of EMIMAC on the poplar cell wall at room temperature would therefore appear to be a reversible swelling and a reversible decrystallization of the cell wall. PMID:21247757

  5. Reversible swelling of the cell wall of poplar biomass by ionic liquid at room temperature

    PubMed Central

    Lucas, Marcel; Wagner, Greg L.; Nishiyama, Yoshiharu; Hanson, Leif; Samayam, Indira P.; Schall, Constance A.; Langan, Paul; Rector, Kirk D.

    2012-01-01

    Time-resolved autofluorescence, Raman microspectroscopy, and scanning microprobe X-ray diffraction were combined in order to characterize lignocellulosic biomass from poplar trees and how it changes during treatment with the ionic liquid 1-n-ethyl-3-methylimidazolium acetate (EMIMAC) at room temperature. The EMIMAC penetrates the cell wall from the lumen, swelling the cell wall by about a factor of two towards the empty lumen. However, the middle lamella remains unchanged, preventing the cell wall from swelling outwards. During this swelling, most of the cellulose microfibrils are solubi-lized but chain migration is restricted and a small percentage of microfibrils persist. When the EMIMAC is expelled, the cellulose recrystallizes as microfibrils of cellulose I. There is little change in the relative chemical composition of the cell wall after treatment. The action of EMIMAC on the poplar cell wall at room temperature would therefore appear to be a reversible swelling and a reversible decrystallization of the cell wall. PMID:21247757

  6. Room Temperature Ionic Liquids as Green Solvent Alternatives in the Metathesis of Oleochemical Feedstocks.

    PubMed

    Thomas, Priya A; Marvey, Bassy B

    2016-01-01

    One of the most important areas of green chemistry is the application of environmentally friendly solvents in catalysis and synthesis. Conventional organic solvents pose a threat to the environment due to the volatility, highly flammability, toxicity and carcinogenic properties they exhibit. The recently emerged room temperature ionic liquids (RTILs) are promising green solvent alternatives to the volatile organic solvents due to their ease of reuse, non-volatility, thermal stability and ability to dissolve a variety of organic and organometallic compounds. This review explores the use of RTILs as green solvent media in olefin metathesis for applications in the oleochemical industry. PMID:26861282

  7. Polyoxometalate-lyotropic liquid crystal hybrid material formed in room-temperature ionic liquids.

    PubMed

    Jiang, Wenqing; Liu, Liping; Hao, Jingcheng

    2011-03-01

    Manganese(II)-substituted polyoxometalate, Na6(NH4)4[(Mn(II)(H2O)3)2(WO2)2(BiW9O33)2] x 37H2O (POM-Mn), was assembled within lyotropic hexagonal liquid crystal (LLC) formed in the room-temperature ionic liquids (RT-ILs), ethylammonium nitrate (EAN), fabricating the POM-LLC inorganic-organic hybrid materials. Polarized optical microscope images combined with small-angle X-ray scattering (SAXS) results indicate that the introduction of POM-Mn does not destroy the structure of hexagonal LLCs. The increase of d spacing demonstrates the integration of POM-Mn within the basic unit of the hexagonal LLCs. The FTIR spectra of the POM-LLC hybrid material show the characteristic absorption peaks of W-O bond. The rheological results indicate POM-LLC hybrid materials are highly viscoelastic and that the apparent viscosity is enhanced due to the introduction of the POM-Mn. The tribological properties were explored to greatly extend the applications of POM-LLC composites in RT-ILs as lubricating materials. The research of magnetic properties indicates the POM-LLC composite is ferromagnetic, therefore illuminating the potential application in the fields of magnetic materials. PMID:21449365

  8. SEM Observation of Hydrous Superabsorbent Polymer Pretreated with Room-Temperature Ionic Liquids

    PubMed Central

    Tsuda, Tetsuya; Mochizuki, Eiko; Kishida, Shoko; Iwasaki, Kazuki; Tsunashima, Katsuhiko; Kuwabata, Susumu

    2014-01-01

    Room-temperature ionic liquid (RTIL), which is a liquid salt at or below room temperature, shows peculiar physicochemical properties such as negligible vapor pressure and relatively-high ionic conductivity. In this investigation, we used six types of RTILs as a liquid material in the pretreatment process for scanning electron microscope (SEM) observation of hydrous superabsorbent polymer (SAP) particles. Very clear SEM images of the hydrous SAP particles were obtained if the neat RTILs were used for the pretreatment process. Of them, tri-n-butylmethylphosphonium dimethylphosphate ([P4, 4, 4, 1][DMP]) provided the best result. On the other hand, the surface morphology of the hydrous SAP particles pretreated with 1-ethyl-3-methylimidazolium tetrafluoroborate ([C2mim][BF4]) and 1-butyl-3-methylimidazolium tetrafluoroborate ([C4mim][BF4]) was damaged. The results of SEM observation and thermogravimetry analysis of the hydrous SAP pretreated with the RTILs strongly suggested that most water in the SAP particles are replaced with RTIL during the pretreatment process. PMID:24621609

  9. Structure of Room Temperature Ionic Liquids on Charged Graphene: An integrated experimental and computational study

    NASA Astrophysics Data System (ADS)

    Uysal, Ahmet; Zhou, Hua; Lee, Sang Soo; Fenter, Paul; Feng, Guang; Li, Song; Cummings, Peter; Fulvio, Pasquale; Dai, Sheng; McDonough, Jake; Gogotsi, Yury

    2014-03-01

    Electrical double layer capacitors (EDLCs) with room temperature ionic liquid (RTIL) electrolytes and carbon electrodes are promising candidates for energy storage devices with high power density and long cycle life. We studied the potential and time dependent changes in the electric double layer (EDL) structure of an imidazolium-based room temperature ionic liquid (RTIL) electrolyte at an epitaxial graphene (EG) surface. We used in situ x-ray reflectivity (XR) to determine the EDL structure at static potentials, during cyclic voltammetry (CV) and potential step measurements. The static potential structures were also investigated with fully atomistic molecular dynamics (MD) simulations. Combined XR and MD results show that the EDL structure has alternating anion/cation layers within the first nanometer of the interface. The dynamical response of the EDL to potential steps has a slow component (>10 s) and the RTIL structure shows hysteresis during CV scans. We propose a conceptual model that connects nanoscale interfacial structure to the macroscopic measurements. This material is based upon work supported as part of the Fluid Interface Reactions, Structures and Transport (FIRST) Center, an Energy Frontier Research Center funded by the U.S. Department of Energy (DOE), Office of Science (SC), Office of Basic Energy

  10. Equilibrium and dynamic charge storage in nanopores with room temperature ionic liquids

    NASA Astrophysics Data System (ADS)

    Wu, Peng

    Electrochemical capacitors store electrical energy physically in the electrical double layers at the electrode/electrolyte interfaces. In spite of their high power density and extraordinary cyclability, the widespread deployment of electrochemical capacitors is limited by their moderate energy density. The current surge in interest in electrochemical capacitors is driven by recent breakthroughs in developing novel electrode and electrolyte materials. In particular, electrodes featuring sub-nanometer pores and room-temperature ionic liquids are promising materials for next-generation electrochemical capacitors. To realize the full potential of these materials, a basic understanding of the charge storage mechanisms in them is essential. In this dissertation, using atomistic simulations, we investigated the charge storage in sub-nanometer pores using room-temperature ionic liquids as electrolytes. These simulations of the equilibrium charge storage in slit-shaped nanopores in contact with room-temperature ionic liquids showed that the capacitance of the nanopores exhibits a U-shaped scaling behavior in pores with width from 0.75 to 1.26 nm. The left branch of the capacitance scaling curve directly corresponds to the anomalous capacitance increase and thus confirms prior experimental observations. The right branch of the curve indirectly agrees with experimental findings that so far have received little attention. We also found that the charge storage in sub-nanometer pores follows a distinct voltage dependent behavior. At low voltages, charge storage is achieved by swapping co-ions in the pore with counter-ions in the bulk electrolytes. As voltage increases, further charge storage is due mainly to the removal of co-ions from the pore, leading to a capacitance increase. The capacitance eventually reaches a maximum when all co-ions are expelled from the pore. At even higher electrode voltages, additional charge storage is realized by counter-ion insertion into the pore, accompanied by a reduction of capacitance. The molecular origins of these phenomena were elucidated by a new theoretical framework we developed specifically for the charge storage in nanopores using solvent-free electrolytes. These simulations of the charging dynamics of sub-nanometer pores in contact with room-temperature ionic liquids showed that the charging of ionophilic pores, of width comparable to the size of ion, is a diffusive process. Such a process is often accompanied by overfilling and followed by de-filling. In sharp contrast to conventional expectations, charging is fast because ion diffusion during charging can be an order of magnitude faster than in the bulk, and charging itself is accelerated by the onset of collective modes. Further acceleration can be achieved using ionophobic pores by eliminating overfilling/de-filling and thus leading to charging behavior qualitatively different from that in conventional, ionophilic pores. Overall, our studies indicated that electrodes with sub-nanometer pores and room-temperature ionic liquids can potentially enable the development of electrochemical capacitors with concurrently high power and energy densities. The fundamental insights gained in our studies help guide the rational design and optimization of these materials to realize their full potentials.

  11. Orientational dynamics of room temperature ionic liquid/water mixtures: water-induced structure.

    PubMed

    Sturlaugson, Adam L; Fruchey, Kendall S; Fayer, Michael D

    2012-02-16

    Optical heterodyne detected optical Kerr effect (OHD-OKE) measurements on a series of 1-alkyl-3-methylimidazolium tetrafluoroborate room-temperature ionic liquids (RTILs) as a function of chain length and water concentration are presented. The pure RTIL reorientational dynamics are identical in form to those of other molecular liquids studied previously by OHD-OKE (two power laws followed by a single exponential decay at long times), but are much slower at room temperature. In contrast, the addition of water to the longer alkyl chain RTILs causes the emergence of a long time biexponential orientational anisotropy decay. Such distinctly biexponential decays have not been seen previously in OHD-OKE experiments on any type of liquid and are analyzed here using a wobbling-in-a-cone model. The slow component for the longer chain RTILs does not obey the Debye-Stokes-Einstein (DSE) equation across the range of solutions, and thus we attribute it to slow cation reorientational diffusion caused by a stiffening of cation alkyl tail-tail associations. The fast component of the decay is assigned to the motions (wobbling) of the tethered imidazolium head groups. The wobbling-in-a-cone analysis provides estimates of the range of angles sampled by the imidazolium head group prior to the long time scale complete orientational randomization. The heterogeneous dynamics and non-DSE behavior observed here should have a significant effect on reaction rates in RTIL/water cosolvent mixtures. PMID:22224942

  12. Solvation dynamics in room temperature ionic liquids studied by ultrafast vibrational spectroscopy

    NASA Astrophysics Data System (ADS)

    Garrett-Roe, Sean; Ren, Zhe; Couchot-Vore, Duane; Brinzer, Thomas

    2014-03-01

    Room temperature ionic liquids are a challenging new area for understanding solvation dynamics. These solvent systems are liquids with a delicate balance of electrostatic, dispersion, and hydrogen-bonding forces which lead to complex structure and dynamics on many time- and length-scales. Here we probe the dynamics of thiocyanate ions in several imidazolium bis(trifluoromethylsulfonyl)amide ionic liquids from femtoseconds to 100 ps using ultrafast vibrational spectroscopy. Two-dimensional infrared (2D-IR) spectroscopy of thiocyanate ions detects both intertial motion (on the hundreds of femtosecond timescale) as well as slower, diffusive motions (on the tens of picosecond timescale). The 2D-IR experiments show that the rate of fluctuation of the electrostatic environment around the thiocyanate is sensitive to hydrogen bonding at the 2-position of the imidazolium ring, depends mildly on water concentration, changes with counter-ion, and is roughly independent of the thiocyanate concentration (up to 30 mM). The results are compared to ab initio simulations which predicted a 10 - 15 picosecond hydrogen bond lifetime. The implications for topics such as the concept of ionicity, the effect of hydrogen bonding on viscosity, and structural and dynamical heterogeneity will be discussed.

  13. Terahertz and Infrared Spectroscopy of Room-Temperature Imidazolium-Based Ionic Liquids.

    PubMed

    Yamada, Toshiki; Tominari, Yukihiro; Tanaka, Shukichi; Mizuno, Maya

    2015-12-24

    The terahertz- and infrared-frequency vibrational modes of various room-temperature imidazolium-based ionic liquids with molecular anions were examined extensively. We found that the molar-concentration-normalized absorption coefficient spectra in the low-wavenumber range for imidazolium cations with different alkyl-chain lengths were nearly identical for the same anion. Regarding the overall view of a wide range of imidazolium-based ionic liquids, we found that the reduced mass of the combination of an imidazolium-ring cation and the anion and the force constant play significant roles in determining the central frequency of the broad absorption band. In addition to these findings, we also discuss the correlation between the (+)C-H stretching vibrational modes in the 3000-3300 cm(-1) range of the infrared spectra and the intermolecular vibrational band in the low-wavenumber range. Finally, we describe some interesting characteristics of the intermolecular vibrational band observed in a wide range of imidazolium-based ionic liquids. PMID:26625193

  14. Translation-rotation decoupling and nonexponentiality in room temperature ionic liquids

    SciTech Connect

    Griffin, Phillip; Agapov, Alexander L; Sokolov, Alexei P

    2012-01-01

    Using a combination of light scattering techniques and broadband dielectric spectroscopy, we have measured the temperature dependence of structural relaxation time and self diffusion in three imidazolium-based room temperature ionic liquids: [bmim][NTf2], [bmim][PF6], and [bmim][TFA]. A detailed analysis of the results demonstrates that self diffusion decouples from structural relaxation in these systems as the temperature is decreased toward Tg. The degree to which the dynamics are decoupled, however, is shown to be surprisingly weak when compared to other supercooled liquids of similar fragility. In addition to the weak decoupling, we demonstrate that the temperature dependence of the structural relaxation time in all three liquids can be well described by a single Vogel-Fulcher-Tamann function over 13 decades in time from 10 11 s up to 102 s. Furthermore, the stretching of the structural relaxation is shown to be temperature independent over the same range of time scales, i.e., time temperature superposition is valid for these ionic liquids from far above the melting point down to the glass transition temperature.We suggest that these phenomena are interconnected and all result from the same underlying mechanism strong and directional intermolecular interactions.

  15. Existence of optical phonons in the room temperature ionic liquid 1-ethyl-3-methylimidazolium trifluoromethanesulfonate

    PubMed Central

    Burba, Christopher M.; Frech, Roger

    2011-01-01

    The technologically important properties of room temperature ionic liquids (RTILs) are fundamentally linked to the ionion interactions present among the constituent ions. These ionion interactions in one RTIL (1-ethyl-3-methylimidazolium trifluoromethanesulfonate, [C2mim]CF3SO3) are characterized with transmission FTIR spectroscopy and polarized attenuated total reflection (ATR) FTIR spectroscopy. A quasilattice model is determined to be the best framework for understanding the ionic interactions. A novel spectroscopic approach is proposed to characterize the degree of order that is present in the quasilattice by comparing the dipole moment derivative calculated from two independent spectroscopic measurements: (1) the TOLO splitting of a vibrational mode using dipolar coupling theory and (2) the optical constants of the material derived from polarized ATR experiments. In principle, dipole moment derivatives calculated from dipolar coupling theory should be similar to those calculated from the optical constants if the quasilattice of the RTIL is highly structured. However, a significant disparity for the two calculations is noted for [C2mim]CF3SO3, indicating that the quasilattice of [C2mim]CF3SO3 is somewhat disorganized. The potential ability to spectroscopically characterize the structure of the quasilattice, which governs the long-range ionion interactions in a RTIL, is a major step forward in understanding the interrelationship between the molecular-level interactions among the constituent ions of an ionic liquid and the important physical properties of the RTIL. PMID:21476760

  16. Cellulose gels produced in room temperature ionic liquids by ionizing radiation

    NASA Astrophysics Data System (ADS)

    Kimura, Atsushi; Nagasawa, Naotsugu; Taguchi, Mitsumasa

    2014-10-01

    Cellulose-based gels were produced in room temperature ionic liquids (RTILs) by ionizing radiation. Cellulose was dissolved at the initial concentration of 20 wt% in 1-ethyl-3-methylimidazolium (EMI)-acetate or N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium (DEMA)-formate with a water content of 18 wt%, and irradiated with ?-rays under aerated condition to produce new cellulose gels. The gel fractions of the cellulose gels obtained in EMI-acetate and DEMA-formate at a dose of 10 kGy were 13% and 19%, respectively. The formation of gel fractions was found to depend on the initial concentration of cellulose, water content, and irradiation temperature. The obtained gel readily absorbed water, methanol, ethanol, dichloromethane, N,N-dimethylacetamide, and RTILs.

  17. Positronium bubble oscillation in room temperature ionic liquids-Temperature dependence

    NASA Astrophysics Data System (ADS)

    Hirade, T.

    2015-06-01

    The temperature dependent oscillation of the ortho-positronium pick-off annihilation rate was successfully observed for a room temperature ionic liquid (IL), N,N,N-trimethyl-N- propylammonium bis(trifluoromethanesulfonyl)imide (TMPA-TFSI). The fundamental frequencies at 25C and 30C were 5.85GHz and 4.00GHz, respectively. The decay of the oscillation was faster at higher temperature, 30C. Moreover, the higher harmonic frequencies could explain the change of ortho-positronium pick-off annihilation rate successfully. The macroscopic viscosity of the IL could not explain the appearance of the oscillation. It indicated that the positron annihilation methods were very strong tools to study the properties of IL's in sub-nanometer scale that must be very different from the macroscopic properties.

  18. Preparation of Biopolymer Fibers by Electrospinning from Room Temperature Ionic Liquids

    PubMed Central

    Viswanathan, Gunaranjan; Murugesan, Saravanababu; Pushparaj, Victor; Nalamasu, Omkaram; Ajayan, Pulickel M.; Linhardt, Robert J.

    2016-01-01

    Electrospinning is a versatile process used to prepare micro- and nano- sized fibers from various polymers dissolved in volatile solvents. In this report, cellulose and celluloseheparin composite fibers are prepared from nonvolatile room temperature ionic liquid (RTIL) solvents by electrospinning. RTILs are extracted from the biopolymer fiber after the fiber formation using a cosolvent. Micron to nanometer sized, branched fibers were obtained from 10% (w/w) concentration of polysaccharide biopolymer in RTIL solution with an applied voltage of 1520 kV. Celluloseheparin composite fibers showed anticoagulant activity, demonstrating that the bioactivity of heparin remained unaffected even on exposure to a high voltage involved in electrospinning. PMID:16471910

  19. Study on the reaction of chlorophenols in room temperature ionic liquids with ionizing radiation

    NASA Astrophysics Data System (ADS)

    Kimura, Atsushi; Taguchi, Mitsumasa; Kondoh, Takafumi; Yang, Jinfeng; Yoshida, Yoichi; Hirota, Koichi

    2008-10-01

    The effects of cations and anions of room temperature ionic liquids (RTILs) on the decomposition of chlorophenols and formation of phenol were investigated by gamma and pulse radiolyses. Absorption bands were observed for aliphatic RTILs just after pulsed electron irradiation, and were assigned as solvated electrons. The decomposition yield of chlorophenol (CP), G(-CP), and the formation yield of phenol, G(Phenol), in RTILs, in which solvated electrons were observed, were higher than those in RTILs, in which the solvated electrons were not detected. G(-CP) and G(Phenol) increased with the viscosity of the RTILs which have diethylmethyl(2-methoxyethyl)ammonium (DEMMA) as cation. G(Phenol) in DEMMA-bis(trifluoromethylsulfonyl)imide (TFSI) having high viscosity was higher than that in trimethylpropylammonium (TMPA)-TFSI having low viscosity. The ratios of G(Phenol)/ G(-CP) were not affected by the substituted position of chlorine on CP in RTILs.

  20. Electrochemistry of Hg(II) salts in room-temperature ionic liquids.

    PubMed

    Manan, Ninie S A; Aldous, Leigh; Alias, Yatimah; Compton, Richard G; Lagunas, M Cristina; Hardacre, Christopher

    2011-03-24

    The electrochemistry of HgCl(2) and [Hg(NTf(2))(2)] ([NTf(2)](-)=bis-{(trifluoromethyl)sulfonyl}imide) has been studied in room temperature ionic liquids. It has been found that the cyclic voltammetry of Hg(II) is strongly dependent on a number of factors (e.g., concentration, anions present in the mixture, and nature of the working electrode) and differs from that found in other media. Depending on conditions, the cyclic voltammetry of Hg(II) can give rise to one, two, or four reduction peaks, whereas the reverse oxidative scans show two to four peaks. Diffuse reflectance UV-vis spectroscopy and X-ray powder diffraction have been used to aid the assignment of the voltammetric waves. PMID:21355596

  1. The room temperature ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate: Electrochemical couples and physical properties

    SciTech Connect

    Fuller, J.; Carlin, R.T.; Osteryoung, R.A.

    1997-11-01

    Room temperature molten salts composed of the 1-ethyl-3-methylimidazolium cation and a chloroaluminate anion have received much attention for use in a variety of commercial applications such as batteries, photovoltaics, metal deposition, and capacitors. The room temperature ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF{sub 4}) was demonstrated as a versatile electrolyte by examining three representative electrochemical couples: ferrocene and tetrathiafulvalene oxidations and lithium ion reduction. Square-wave voltammetric data for ferrocene oxidation were fit to a reversible one-electron process using the COOL algorithm to give a half-wave potential of 0.490 V vs. Al/Al(III) and a diffusion coefficient of 5.1 {times} 10{sup {minus}7} cm{sup 2}/s. The two-electron oxidation of tetrathiafulvalene was reversible and proceeded through two consecutive one-electron steps; although data collected at lower square-wave frequencies indicated a slow precipitation of the TTF{sup +} species. Lithium ion was reduced to lithium metal at a Pt electrode following the addition of water to the EMIBF{sub 4} electrolyte, whereas lithium ion reduction at an Al wire produced the {beta}-LiAl alloy. Conductivities and kinematic viscosities of EMIBF{sub 4} were measured from 20 to 100 C and had values of 14 mS/cm and 0.275 cm{sup 2}/s, respectively, at 25 C.

  2. Ion transport and structural dynamics in homologous ammonium and phosphonium-based room temperature ionic liquids

    NASA Astrophysics Data System (ADS)

    Griffin, Philip J.; Holt, Adam P.; Tsunashima, Katsuhiko; Sangoro, Joshua R.; Kremer, Friedrich; Sokolov, Alexei P.

    2015-02-01

    Charge transport and structural dynamics in a homologous pair of ammonium and phosphonium based room temperature ionic liquids (ILs) have been characterized over a wide temperature range using broadband dielectric spectroscopy and quasi-elastic light scattering spectroscopy. We have found that the ionic conductivity of the phosphonium based IL is significantly enhanced relative to the ammonium homolog, and this increase is primarily a result of a lower glass transition temperature and higher ion mobility. Additionally, these ILs exhibit pronounced secondary relaxations which are strongly influenced by the atomic identity of the cation charge center. While the secondary relaxation in the phosphonium IL has the expected Arrhenius temperature dependence characteristic of local beta relaxations, the corresponding relaxation process in the ammonium IL was found to exhibit a mildly non-Arrhenius temperature dependence in the measured temperature rangeindicative of molecular cooperativity. These differences in both local and long-range molecular dynamics are a direct reflection of the subtly different inter-ionic interactions and mesoscale structures found in these homologous ILs.

  3. Non-Faradaic Energy Storage by Room Temperature Ionic Liquids in Nanoporous Electrodes.

    PubMed

    Vatamanu, Jenel; Vatamanu, Mihaela; Bedrov, Dmitry

    2015-06-23

    The enhancement of non-Faradaic charge and energy density stored by ionic electrolytes in nanostructured electrodes is an intriguing issue of great practical importance for energy storage in electric double layer capacitors. On the basis of extensive molecular dynamics simulations of various carbon-based nanoporous electrodes and room temperature ionic liquid (RTIL) electrolytes, we identify atomistic mechanisms and correlations between electrode/electrolyte structures that lead to capacitance enhancement. In the symmetric electrode setup with nanopores having atomically smooth walls, most RTILs showed up to 50% capacitance increase compared to infinitely wide pore. Extensive simulations using asymmetric electrodes and pores with atomically rough surfaces demonstrated that tuning of electrode nanostructure could lead to further substantial capacitance enhancement. Therefore, the capacitance in nanoporous electrodes can be increased due to a combination of two effects: (i) the screening of ionic interactions by nanopore walls upon electrolyte nanoconfinement, and (ii) the optimization of nanopore structure (volume, surface roughness) to take into account the asymmetry between cation and anion chemical structures. PMID:26038979

  4. Ion transport and structural dynamics in homologous ammonium and phosphonium-based room temperature ionic liquids.

    PubMed

    Griffin, Philip J; Holt, Adam P; Tsunashima, Katsuhiko; Sangoro, Joshua R; Kremer, Friedrich; Sokolov, Alexei P

    2015-02-28

    Charge transport and structural dynamics in a homologous pair of ammonium and phosphonium based room temperature ionic liquids (ILs) have been characterized over a wide temperature range using broadband dielectric spectroscopy and quasi-elastic light scattering spectroscopy. We have found that the ionic conductivity of the phosphonium based IL is significantly enhanced relative to the ammonium homolog, and this increase is primarily a result of a lower glass transition temperature and higher ion mobility. Additionally, these ILs exhibit pronounced secondary relaxations which are strongly influenced by the atomic identity of the cation charge center. While the secondary relaxation in the phosphonium IL has the expected Arrhenius temperature dependence characteristic of local beta relaxations, the corresponding relaxation process in the ammonium IL was found to exhibit a mildly non-Arrhenius temperature dependence in the measured temperature range-indicative of molecular cooperativity. These differences in both local and long-range molecular dynamics are a direct reflection of the subtly different inter-ionic interactions and mesoscale structures found in these homologous ILs. PMID:25725739

  5. Ion transport and structural dynamics in homologous ammonium and phosphonium-based room temperature ionic liquids

    SciTech Connect

    Griffin, Philip J.; Holt, Adam P.; Tsunashima, Katsuhiko; Sangoro, Joshua R.; Kremer, Friedrich; Sokolov, Alexei P.

    2015-02-28

    Charge transport and structural dynamics in a homologous pair of ammonium and phosphonium based room temperature ionic liquids (ILs) have been characterized over a wide temperature range using broadband dielectric spectroscopy and quasi-elastic light scattering spectroscopy. We have found that the ionic conductivity of the phosphonium based IL is significantly enhanced relative to the ammonium homolog, and this increase is primarily a result of a lower glass transition temperature and higher ion mobility. Additionally, these ILs exhibit pronounced secondary relaxations which are strongly influenced by the atomic identity of the cation charge center. While the secondary relaxation in the phosphonium IL has the expected Arrhenius temperature dependence characteristic of local beta relaxations, the corresponding relaxation process in the ammonium IL was found to exhibit a mildly non-Arrhenius temperature dependence in the measured temperature range—indicative of molecular cooperativity. These differences in both local and long-range molecular dynamics are a direct reflection of the subtly different inter-ionic interactions and mesoscale structures found in these homologous ILs.

  6. Electroless Deposition of III-V Semiconductor Nanostructures from Ionic Liquids at Room Temperature.

    PubMed

    Lahiri, Abhishek; Borisenko, Natalia; Olschewski, Mark; Gustus, Ren; Zahlbach, Janine; Endres, Frank

    2015-09-28

    Group III-V semiconductor nanostructures are important materials in optoelectronic devices and are being researched in energy-related fields. A simple approach for the synthesis of these semiconductors with well-defined nanostructures is desired. Electroless deposition (galvanic displacement) is a fast and versatile technique for deposition of one material on another and depends on the redox potentials of the two materials. Herein we show that GaSb can be directly synthesized at room temperature by galvanic displacement of SbCl3 /ionic liquid on electrodeposited Ga, on Ga nanowires, and also on commercial Ga. In situ AFM revealed the galvanic displacement process of Sb on Ga and showed that the displacement process continues even after the formation of GaSb. The bandgap of the deposited GaSb was 0.90.1 eV compared to its usual bandgap of 0.7 eV. By changing the cation in the ionic liquid, the redox process could be varied leading to GaSb with different optical properties. PMID:26290478

  7. Exploring electrochemical windows of room-temperature ionic liquids: a computational study.

    PubMed

    Tian, Yong-Hui; Goff, George S; Runde, Wolfgang H; Batista, Enrique R

    2012-10-01

    Room-temperature ionic liquids (RTILs) are regarded as green solvents due to their low volatility, low flammability, and thermal stability. RTILs exhibit wide electrochemical windows, making them prime candidates as media for electrochemically driven reactions such as electro-catalysis and electro-plating for separations applications. Therefore, understanding the factors determining edges of the electrochemical window, the electrochemical stability of the RTILs, and the degradation products is crucial to improve the efficiency and applicability of these systems. We present here computational investigations of the electrochemical properties of a variety of RTILs covering a wide range of electrochemical windows. We proposed four different approaches with different degrees of approximation and computational cost from gas-phase calculations to full explicit solvation models. It was found that, whereas the simplest model has significant flaws in accuracy, implicit and explicit solvent models can be used to reliably predict experimental data. The general trend of electrochemical windows of the RTILs studied is well reproduced, showing that it increases in the order of imidazolium < ammonium < pyrrolidinium < phosphonium giving confidence to the methodology presented to use it in screening studies of ionic liquids. PMID:22946441

  8. Physical and chemical absorptions of carbon dioxide in room-temperature ionic liquids.

    PubMed

    Yokozeki, A; Shiflett, Mark B; Junk, Christopher P; Grieco, Liane M; Foo, Thomas

    2008-12-25

    Gaseous solubilities of carbon dioxide (CO2) in 18 room-temperature ionic liquids (RTILs) have been measured at an isothermal condition (about 298 K) using a gravimetric microbalance. The observed pressure-temperature-composition (PTx) data have been analyzed by use of an equation-of-state (EOS) model, which has been successfully applied for our previous works. Henry's law constants have been obtained from the observed (PTx) data directly and/or from the EOS correlation. Ten RTILs among the present ionic liquids results in the physical absorption, and eight RTILs show the chemical absorption. The classification of whether the absorption is the physical or chemical type is based on the excess Gibbs and enthalpy functions as well as the magnitude of the Henry's constant. In the chemical absorption cases, the ideal association model has been applied in order to interpret those excess thermodynamic functions. Then, two types of the chemical associations (AB and AB2, where A is CO2 and B is RTIL) have been observed with the heat of complex formations of about -11 (for AB) and from -27 to -37 (for AB2) kJ x mol(-1), respectively. PMID:19053217

  9. Heats of vaporization of room temperature ionic liquids by tunable vacuum ultraviolet photoionization

    SciTech Connect

    Chambreau, Steven D.; Vaghjiani, Ghanshyam L.; To, Albert; Koh, Christine; Strasser, Daniel; Kostko, Oleg; Leone, Stephen R.

    2009-11-25

    The heats of vaporization of the room temperature ionic liquids (RTILs) N-butyl-N-methylpyrrolidinium bistrifluorosulfonylimide, N-butyl-N-methylpyrrolidinium dicyanamide, and 1-butyl-3-methylimidazolium dicyanamide are determined using a heated effusive vapor source in conjunction with single photon ionization by a tunable vacuum ultraviolet synchrotron source. The relative gas phase ionic liquid vapor densities in the effusive beam are monitored by clearly distinguished dissociative photoionization processes via a time-of-flight mass spectrometer at a tunable vacuum ultraviolet beamline 9.0.2.3 (Chemical Dynamics Beamline) at the Advanced Light Source synchrotron facility. Resulting in relatively few assumptions, through the analysis of both parent cations and fragment cations, the heat of vaporization of N-butyl-N-methylpyrrolidinium bistrifluorosulfonylimide is determined to be Delta Hvap(298.15 K) = 195+-19 kJ mol-1. The observed heats of vaporization of 1-butyl-3-methylimidazolium dicyanamide (Delta Hvap(298.15 K) = 174+-12 kJ mol-1) and N-butyl-N-methylpyrrolidinium dicyanamide (Delta Hvap(298.15 K) = 171+-12 kJ mol-1) are consistent with reported experimental values using electron impact ionization. The tunable vacuum ultraviolet source has enabled accurate measurement of photoion appearance energies. These appearance energies are in good agreement with MP2 calculations for dissociative photoionization of the ion pair. These experimental heats of vaporization, photoion appearance energies, and ab initio calculations corroborate vaporization of these RTILs as intact cation-anion ion pairs.

  10. Hydrogen peroxide biosensor based on a myoglobin/hydrophilic room temperature ionic liquid film.

    PubMed

    Safavi, Afsaneh; Farjami, Fatemeh

    2010-07-01

    The composite film based on Nafion and hydrophilic room temperature ionic liquid (RTIL) 1-butyl-3-methyl-imidazolium chloride ([bmim]Cl) was used as an immobilization matrix to entrap myoglobin (Mb). The study of ionic liquid (IL)-Mb interaction by ultraviolet-visible (UV-vis) spectroscopy showed that Mb retains its native conformation in the presence of IL. The immobilized Mb displayed a pair of well-defined cyclic voltammetric peaks with a formal potential (E(o)(')) of -0.35 V in a 0.1 M phosphate buffer solution (PBS) of pH 7.0. The immobilized Mb exhibited excellent electrocatalytic response to the reduction of hydrogen peroxide, based on which a mediator-free amperometric biosensor for hydrogen peroxide was designed. The linear range for the determination of hydrogen peroxide was from 1.0 to 180 microM with a detection limit of 0.14 microM at a signal/noise ratio of 3. The apparent Michaelis constant (K(m)(app)) for the electrocatalytic reaction was 22.6 microM. The stability, repeatability, and selectivity of the sensor were evaluated. The proposed biosensor has a lower detection limit than many other IL-heme protein-based biosensors and is free from common interference in hydrogen peroxide biosensors. PMID:20230770

  11. Ionic liquid pretreatment of poplar wood at room temperature: swelling and incorporation of nanoparticles

    SciTech Connect

    Lucas, Marcel; Macdonald, Brian A; Wagner, Gregory L; Joyce, Steven A; Rector, Kirk D

    2010-01-01

    Lignocellulosic biomass represents a potentially sustainable source of liquid fuels and commodity chemicals. It could satisfy the energy needs for transportation and electricity generation, while contributing substantially to carbon sequestration and limiting the accumulation of greenhouse gases in the atmosphere. Potential feedstocks are abundant and include crops, agricultural wastes, forest products, grasses, and algae. Among those feedstocks, wood is mainly constituted of three components: cellulose, hemicellulose, and lignin. The conversion process of lignocellulosic biomass typically consists of three steps: (1) pretreatment; (2) hydrolysis of cellulose and hemicellulose into fermentable sugars; and (3) fermentation of the sugars into liquid fuels (ethanol) and other commodity chemicals. The pretreatment step is necessary due to the complex structure of the plant cell wall and the chemical resistance of lignin. Most current pretreatments are energy-intensive and/or polluting. So it is imperative to develop new pretreatments that are economically viable and environmentally friendly. Recently, ionic liquids have attracted considerable interest, due to their ability to dissolve biopolymers, such as cellulose, lignin, native switchgrass, and others. Ionic liquids are also considered green solvents, since they have been successfully recycled at high yields for further use with limited efficiency loss. Also, a few microbial cellulases remain active at high ionic liquid concentration. However, all studies on the dissolution of wood in ionic liquids have been conducted so far at high temperatures, typically above 90 C. Development of alternative pretreatments at room temperature is desirable to eliminate the additional energy cost. In this study, thin sections of poplar wood were swollen at room temperature by a 3 h ionic liquid (1-ethyl-3-methylimidazolium acetate or EMIMAc) pretreatment. The pretreated sample was then exposed to an aqueous suspension of nanoparticles that resulted in the sample contraction and the deposition of nanoparticles onto the surface and embedded into the cell wall. To date, both silver and gold particles ranging in size from 40-100 nm have been incorporated into wood. Penetration of gold nanoparticles of 100 nm diameter in the cell walls was best confirmed by near-infrared confocal Raman microscopy, since the deposition of gold nanoparticles induces a significant enhancement of the Raman signal from the wood in their close proximity, an enhancement attributed to the surface-enhanced Raman effect (SERS). After rinsing with water, scanning electron microscopy (SEM) and Raman images of the same areas show that most nanoparticles remained on the pretreated sample. Raman images at different depths reveal that a significant number of nanoparticles were incorporated into the wood sample, at depths up to 4 {micro}m, or 40 times the diameter of the nanoparticles. Control experiments on an untreated wood sample resulted in the deposition of nanoparticles only at the surface and most nanoparticles were removed upon rinsing. This particle incorporation process enables the development of new pretreatments, since the nanoparticles have a high surface-to-volume ratio and could be chemically functionalized. Other potential applications for the incorporated nanoparticles include isotope tracing, catalysis, imaging agents, drug-delivery systems, energy-storage devices, and chemical sensors.

  12. Magnetomotive room temperature dicationic ionic liquid: a new concept toward centrifuge-less dispersive liquid-liquid microextraction.

    PubMed

    Beiraghi, Asadollah; Shokri, Masood; Seidi, Shahram; Godajdar, Bijan Mombani

    2015-01-01

    A new centrifuge-less dispersive liquid-liquid microextraction technique based on application of magnetomotive room temperature dicationic ionic liquid followed by electrothermal atomic absorption spectrometry (ETAAS) was developed for preconcentration and determination of trace amount of gold and silver in water and ore samples, for the first time. Magnetic ionic liquids not only have the excellent properties of ionic liquids but also exhibit strong response to an external magnetic field. These properties provide more advantages and potential application prospects for magnetic ionic liquids than conventional ones in the fields of extraction processes. In this work, thio-Michler's ketone (TMK) was used as chelating agent to form Ag/Au-TMK complexes. Several important factors affecting extraction efficiency including extraction time, rate of vortex agitator, pH of sample solution, concentration of the chelating agent, volume of ionic liquid as well as effects of interfering species were investigated and optimized. Under the optimal conditions, the limits of detection (LOD) were 3.2 and 7.3ngL(-1) with the preconcentration factors of 245 and 240 for Au and Ag, respectively. The precision values (RSD%, n=7) were 5.3% and 5.8% at the concentration level of 0.05?gL(-1) for Au and Ag, respectively. The relative recoveries for the spiked samples were in the acceptable range of 96-104.5%. The results demonstrated that except Hg(2+), no remarkable interferences are created by other various ions in the determination of Au and Ag, so that the tolerance limits (WIon/WAu or Ag) of major cations and anions were in the range of 250-1000. The validated method was successfully applied for the analysis of Au and Ag in some water and ore samples. PMID:25528072

  13. Kinetics and Thermodynamics of Hydrogen Oxidation and Oxygen Reduction in Hydrophobic Room-Temperature Ionic Liquids

    PubMed Central

    Rollins, Julie B.; Conboy, John C.

    2010-01-01

    In this study 1-dodecyl-3-methylimidazolium (C12mim) bis(pentafluoroethylsulfonyl)imide (BETI) and 1-dodecylimidazolium (C12im) BETI hydrophobic room-temperature ionic liquids (RTILs) were synthesized and used as proton-conducting electrolytes in a nonhumidified feed gas electrochemical cell. The ionic conductivities of C12mimBETI and C12imBETI were similar and increased linearly with an increase in temperature from 20 to 130°C. However, when used in the electrochemical system the protic water-equilibrated C12imBETI had a larger maximum current and power density compared to the aprotic water-equilibrated C12mimBETI. The effect of water content on the reaction rates and thermodynamics of these hydrophobic RTILs was also examined. The efficiency of the C12mimBETI increased upon removal of water while that of the C12imBETI decreased in efficiency when water was removed. The water structure in these RTILs was examined using attenuated total internal reflection Fourier transform IR spectroscopy and depended on the chemical structure of the cation. These studies give further insight into the possible mechanism of proton transport in these RTIL systems. PMID:20414470

  14. Supported Phospholipid Bilayer Defects Created by a Cation or Anion of a Room-Temperature Ionic Liquid

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In this work, the independent effects on a supported phospholipid bilayer (SPB) caused by a cation and anion of a room-temperature ionic liquid (RT-IL) were studied via atomic force microscopy (AFM). The supported phospholipid bilayer was composed only of 1,2-dielaidoylphosphatidylcholine (DEPC) an...

  15. Fission-Product Separation Based on Room-Temperature Ionic Liquids

    SciTech Connect

    Luo, Huimin; Hussey, Charles L.

    2005-09-30

    The objectives of this project are (a) to synthesize new ionic liquids tailored for the extractive separation of Cs + and Sr 2+; (b) to select optimum macrocyclic extractants through studies of complexation of fission products with macrocyclic extractants and transport in new extraction systems based on ionic liquids; (c) to develop efficient processes to recycle ionic liquids and crown ethers; and (d) to investigate chemical stabilities of ionic liquids under strong acid, strong base, and high-level-radiation conditions.

  16. Fission-Product Separation Based on Room-Temperature Ionic Liquids

    SciTech Connect

    Luo, Huimin

    2006-11-15

    The objectives of this project are (a) to synthesize new ionic liquids tailored for the extractive separation of Cs + and Sr 2+; (b) to select optimum macrocyclic extractants through studies of complexation of fission products with macrocyclic extractants and transport in new extraction systems based on ionic liquids; (c) to develop efficient processes to recycle ionic liquids and crown ethers; and (d) to investigate chemical stabilities of ionic liquids under strong acid, strong base, and high-level-radiation conditions.

  17. Evidence for laser-induced formation of solvated electrons in room temperature ionic liquids.

    PubMed

    Chandrasekhar, N; Endres, F; Unterreiner, A-N

    2006-07-21

    The photolytic generation of solvated electrons was observed for the first time in two room temperature ionic liquids (RTILs), trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imide (IL) and 1-butyl-1-methyl-pyrrolidinium bis(trifluoromethylsulfonyl)imide (IL). A 70 fs UV-pulse was used to excite the RTILs, while the transient response was monitored in the visible and near-infrared spectral regions. Immediately after excitation, a pulse duration limited rise of the induced absorption indicated the formation of solvated electrons suggesting the existence of pre-formed traps in RTILs. A broad transient absorption spectrum with a full width at half maximum of about 0.9 eV, typical for solvated electrons, was reconstructed from the transient profiles. Wavelength-independent relaxation dynamics at longer delay times suggest a lifetime of solvated electrons in the ns regime in agreement with results from pulse radiolysis studies. Adding 1,1-dimethylpyrrolidinium iodide to IL led to an increase of the UV absorbance and consequently, to an increase of the yield of solvated electrons. Furthermore, this solute is an efficient electron scavenger causing the transients to decay within about 40 ps. PMID:16902711

  18. Electroless deposition of platinum nanoparticles in room-temperature ionic liquids.

    PubMed

    Zhang, Da; Okajima, Takeyoshi; Lu, Dalin; Ohsaka, Takeo

    2013-09-24

    The electroless deposition of Pt nanoparticles (Pt-NPs) could be carried out by dissolving potassium tetrachloroplatinate(II) (K2[PtCl4]) in 1-ethyl-3-methylimidazolium (EMI(+)) room-temperature ionic liquids (RTILs) containing bis(trifluoromethylsulfonyl) imide (NTf2(-)) or tetrafluoroborate (BF4(-)) anion and small cations, such as H(+), K(+), and Li(+). In this case, no deposition of Pt-NPs occurred in RTILs without such small cations. The formation of Pt-NPs was only observed in RTILs containing trifluoromethanesulfonimide (HNTf2) and protons at high temperature (?80 C) when potassium hexachloroplatinate(IV) (K2[PtCl6]) was dissolved in the RTILs. The obtained Pt-NPs gave a characteristic absorption spectrum of ultrasmall Pt-NPs. The ultrasmall and uniform Pt-NPs of ca. 1-4 nm in diameter were produced and the Pt-NPs/EMI(+)NTf2(-) dispersion was kept stably for several months without adding any additional stabilizers or capping molecules. The identified Fourier-transform patterns along the [0 1 1] zone axis were observed for the TEM images of Pt-NPs. On the basis of the results obtained, a probable mechanism of the electroless formation of Pt-NPs is discussed. PMID:23985068

  19. Surface tension of room temperature ionic liquids measured by dynamic light scattering

    NASA Astrophysics Data System (ADS)

    Osada, R.; Hoshino, T.; Okada, K.; Ohmasa, Y.; Yao, M.

    2009-05-01

    Using dynamic light scattering techniques, we obtained the surface tension ?, surface excess entropy S(?), surface excess enthalpy H(?), and viscosity ? for the following seven room temperature ionic liquids in a wide temperature range from 30 to around 140 C: 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, 1-hexyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)imide, N,N,N-trimethyl-N-propylammonium bis(trifluoromethanesulfonyl)imide, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-hexyl-3-methylimidazolium hexafluorophosphate, and 1-octyl-3-methyl imidazolium hexafluorophosphate. We have found that ? increases systematically with decreasing the anion size and the alkyl side chain length. On the other hand, S(?) and ? increase with decreasing the anion size but decrease with decreasing the alkyl chain length. H(?) seems to decrease with increasing the anion size, but it has no clear dependence on the alkyl chain length. We discuss the bulk and surface properties, referring to the Coulomb interactions and van der Waals interactions.

  20. Effects of Room-Temperature Ionic Liquids on Zebra Mussels (Dreissena polymorpha)

    NASA Astrophysics Data System (ADS)

    Costello, D. M.; Bernot, R. J.; Lamberti, G. A.

    2005-05-01

    Zebra mussels (Dreissena polymorpha) are exotic bivalves that are widely distributed in eastern North America. We propose that this nuisance organism could serve as a model species for studies of aquatic toxicology. We tested zebra mussels response to room-temperature ionic liquids (ILs), which are being synthesized as environmentally friendly alternatives to volatile organic solvents. Volatile organic solvents contribute to atmospheric pollution and ozone depletion, whereas ILs are non-volatile and less harmful to the atmosphere. Although ILs would contribute significantly less to air pollution, little is known about their potential effects on aquatic ecosystems. In 72-hour toxicity tests, we determined the acute effects of three imidazolium-based ILs (1-butyl-3-methylimidazolium bromide (bmimBr), 1-hexyl-3-methylimidazolium bromide (hmimBr), and 1-octyl-3-methylimidazolium bromide (omimBr)) on the survival of zebra mussels. As alkyl chain length decreased, median lethal concentration (LC50) decreased from 1291 mg L-1 for bmimBr, to 105 mg L-1 for hmimBr, and 21.2 mg L-1 for omimBr. For bivalve mussels, the toxicities of these ILs are comparable to the toxicities of commonly used industrial solvents (e.g., toluene, benzene). This study presents a foundation for using zebra mussels in toxicity studies as well as possible models for less common Unionid mussels.

  1. Ideal gas solubilities and solubility selectivities in a binary mixture of room-temperature ionic liquids

    SciTech Connect

    Finotello Alexia; Bara Jason E.; Narayan Suguna; Campder Dean; Noble Richard D.

    2008-07-01

    This study focuses on the solubility behaviors of CO{sub 2}, CH{sub 4}, and N{sub 2} gases in binary mixtures of imidazolium-based room-temperature ionic liquids (RTILs) using l-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)-imide ((C{sub 2}mim)(Tf{sub 2}N)) and l-ethyl-3-methylimidazolium tetrafluoroborate ((C{sub 2}mim)(BF{sub 4})) at 40{sup o}C and low pressures (about 1 atm). The mixtures tested were 0, 25, 50, 75, 90, 95, and 100 mol % (C{sub 2}mim)(BF{sub 4}) in (C{sub 2}-mim)(Tf2{sub N}). Results show that regular solution theory (RST) can be used to describe the gas solubility and selectivity behaviors in RTIL mixtures using an average mixture solubility parameter or an average measured mixture molar volume. Interestingly, the solubility selectivity, defined as the ratio of gas mole fractions in the RTIL mixture, of CO{sub 2} with N{sub 2} or CH{sub 4} in pure (C{sub 2}mim)(BF4) can be enhanced by adding 5 mol% (C{sub 2}-mim)(Tf{sub 2}N).

  2. Hydrogen-bonding interactions and protic equilibria in room-temperature ionic liquids containing crown ethers.

    SciTech Connect

    Marin, T.; Shkrob, I.; Dietz, M.

    2011-04-14

    Nuclear magnetic resonance (NMR) spectroscopy has been used to study hydrogen-bonding interactions between water, associated and dissociated acids (i.e., nitric and methanesulfonic acids), and the constituent ions of several water-immiscible room-temperature ionic liquids (ILs). In chloroform solutions also containing a crown ether (CE), water molecules strongly associate with the IL ions, and there is rapid proton exchange between these bound water molecules and hydronium associated with the CE. In neat ILs, the acids form clusters differing in their degree of association and ionization, and their interactions with the CEs are weak. The CE can either promote proton exchange between different clusters in IL solution when their association is weak or inhibit such exchange when the association is strong. Even strongly hydrophobic ILs are shown to readily extract nitric acid from aqueous solution, typically via the formation of a 1:1:1 {l_brace}H{sub 3}O{sup +} {center_dot} CE{r_brace}NO{sub 3}{sup -} complex. In contrast, the extraction of methanesulfonic acid is less extensive and proceeds mainly by IL cation-hydronium ion exchange. The relationship of these protic equilibria to the practical application of hydrophobic ILs (e.g., in spent nuclear fuel reprocessing) is discussed.

  3. Stability of the Liquid State of Imidazolium-Based Ionic Liquids under High Pressure at Room Temperature.

    PubMed

    Yoshimura, Yukihiro; Shigemi, Machiko; Takaku, Mayumi; Yamamura, Misaho; Takekiyo, Takahiro; Abe, Hiroshi; Hamaya, Nozomu; Wakabayashi, Daisuke; Nishida, Keisuke; Funamori, Nobumasa; Sato, Tomoko; Kikegawa, Takumi

    2015-06-25

    To understand the stability of the liquid phase of ionic liquids under high pressure, we investigated the phase behavior of a series of 1-alkyl-3-methylimidazolium tetrafluoroborate ([Cnmim][BF4]) homologues with different alkyl chain lengths for 2 ≤ n ≤ 8 up to ∼7 GPa at room temperature. The ionic liquids exhibited complicated phase behavior, which was likely due to the conformational flexibility in the alkyl chain. The present results reveal that [Cnmim][BF4] falls into superpressed state around 2-3 GPa range upon compression with an implication of multiple phase or structural transitions to ∼7 GPa. Remarkably, a characteristic nanostructural organization in ionic liquids largely diminishes at the superpressed state. The behaviors of imidazolium-based ionic liquids can be classified into, at least, three patterns: (1) pressure-induced crystallization, (2) superpressurization upon compression, and (3) decompression-induced crystallization from the superpressurized glass. Interestingly, the high-pressure phase behavior was relevant to the glass transition behavior at low temperatures and ambient pressure. As n increases, the glass transition pressure (pg) decreases (from 2.8 GPa to ∼2 GPa), and the glass transition temperature increases. The results indicate that the p-T range of the liquid phase is regulated by the alkyl chain length of [Cnmim][BF4] homologues. PMID:25988295

  4. Understanding the impact of nanoscale aggregation on charge transport and structural dynamics in room temperature ionic liquids

    NASA Astrophysics Data System (ADS)

    Griffin, Philip; Holt, Adam; Wang, Yangyang; Sokolov, Alexei

    2015-03-01

    Amphiphilic room temperature ionic liquids (ILs) segregate on the nanoscale, forming intricate networks of charge-rich ionic domains intercalated with charge-poor aliphatic domains. While this structural phenomenon has been well established through x-ray diffraction studies and atomistic MD simulations, the precise effects of nanophase segregation on ion transport and structural dynamics in ILs remains poorly understood. Using a combination of broadband dielectric spectroscopy, light scattering spectroscopy, and rheology, we have characterized the ionic conductivity, structural dynamics, and shear viscosity of a homologous series of quaternary ammonium ionic liquids over a wide temperature range. Upon increasing the length and volume fraction of the alkyl side chains of these quaternary ammonium ILs, ionic conductivity decreases precipitously, although no corresponding slowing of the structural dynamics is observed. Instead, we identify the dynamical signature of supramolecular aggregates. Our results directly demonstrate the role that chemical structure and ionic aggregation plays in determining the charge transport properties of amphiphilic ILs.

  5. Synthesis and Characterization of Thiazolium-Based Room Temperature Ionic Liquids for Gas Separations

    SciTech Connect

    Hillesheim, PC; Mahurin, SM; Fulvio, PF; Yeary, JS; Oyola, Y; Jiang, DE; Dai, S

    2012-09-05

    A series of novel thiazolium-bis(triflamide) based ionic liquids has been synthesized and characterized. Physicochemical properties of the ionic liquids such as thermal stability, phase transitions, and infrared spectra were analyzed and compared to the imidazolium-based congeners. Several unique classes of ancillary substitutions are examined with respect to impacts on overall structure, in addition to their carbon dioxide absorption properties in supported ionic-liquid membranes for gas separation.

  6. An electrochemical gas sensor based on paper supported room temperature ionic liquids.

    PubMed

    Dossi, Nicolò; Toniolo, Rosanna; Pizzariello, Andrea; Carrilho, Emanuel; Piccin, Evandro; Battiston, Simone; Bontempelli, Gino

    2012-01-01

    A sensitive and fast-responding membrane-free amperometric gas sensor is described, consisting of a small filter paper foil soaked with a room temperature ionic liquid (RTIL), upon which three electrodes are screen printed with carbon ink, using a suitable mask. It takes advantage of the high electrical conductivity and negligible vapour pressure of RTILs as well as their easy immobilization into a porous and inexpensive supporting material such as paper. Moreover, thanks to a careful control of the preparation procedure, a very close contact between the RTIL and electrode material can be achieved so as to allow gaseous analytes to undergo charge transfer just as soon as they reach the three-phase sites where the electrode material, paper supported RTIL and gas phase meet. Thus, the adverse effect on recorded currents of slow steps such as analyte diffusion and dissolution in a solvent is avoided. To evaluate the performance of this device, it was used as a wall-jet amperometric detector for flow injection analysis of 1-butanethiol vapours, adopted as the model gaseous analyte, present in headspace samples in equilibrium with aqueous solutions at controlled concentrations. With this purpose, the RTIL soaked paper electrochemical detector (RTIL-PED) was assembled by using 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide as the wicking RTIL and printing the working electrode with carbon ink doped with cobalt(II) phthalocyanine, to profit from its ability to electrocatalyze thiol oxidation. The results obtained were quite satisfactory (detection limit: 0.5 μM; dynamic range: 2-200 μM, both referring to solution concentrations; correlation coefficient: 0.998; repeatability: ±7% RSD; long-term stability: 9%), thus suggesting the possible use of this device for manifold applications. PMID:22076475

  7. Structure and dynamics of POPC bilayers in water solutions of room temperature ionic liquids

    NASA Astrophysics Data System (ADS)

    Benedetto, Antonio; Bingham, Richard J.; Ballone, Pietro

    2015-03-01

    Molecular dynamics simulations in the NPT ensemble have been carried out to investigate the effect of two room temperature ionic liquids (RTILs), on stacks of phospholipid bilayers in water. We consider RTIL compounds consisting of chloride ([bmim][Cl]) and hexafluorophosphate ([bmim][PF6]) salts of the 1-buthyl-3-methylimidazolium ([bmim]+) cation, while the phospholipid bilayer is made of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC). Our investigations focus on structural and dynamical properties of phospholipid and water molecules that could be probed by inelastic and quasi-elastic neutron scattering measurements. The results confirm the fast incorporation of [bmim]+ into the lipid phase already observed in previous simulations, driven by the Coulomb attraction of the cation for the most electronegative oxygens in the POPC head group and by sizeable dispersion forces binding the neutral hydrocarbon tails of [bmim]+ and of POPC. The [bmim]+ absorption into the bilayer favours the penetration of water into POPC, causes a slight but systematic thinning of the bilayer, and further stabilises hydrogen bonds at the lipid/water interface that already in pure samples (no RTIL) display a lifetime much longer than in bulk water. On the other hand, the effect of RTILs on the diffusion constant of POPC (DPOPC) does not reveal a clearly identifiable trend, since DPOPC increases upon addition of [bmim][Cl] and decreases in the [bmim][PF6] case. Moreover, because of screening, the electrostatic signature of each bilayer is only moderately affected by the addition of RTIL ions in solution. The analysis of long wavelength fluctuations of the bilayers shows that RTIL sorption causes a general decrease of the lipid/water interfacial tension and bending rigidity, pointing to the destabilizing effect of RTILs on lipid bilayers.

  8. Structure and dynamics of POPC bilayers in water solutions of room temperature ionic liquids

    SciTech Connect

    Benedetto, Antonio; Bingham, Richard J.; Ballone, Pietro

    2015-03-28

    Molecular dynamics simulations in the NPT ensemble have been carried out to investigate the effect of two room temperature ionic liquids (RTILs), on stacks of phospholipid bilayers in water. We consider RTIL compounds consisting of chloride ([bmim][Cl]) and hexafluorophosphate ([bmim][PF{sub 6}]) salts of the 1-buthyl-3-methylimidazolium ([bmim]{sup +}) cation, while the phospholipid bilayer is made of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC). Our investigations focus on structural and dynamical properties of phospholipid and water molecules that could be probed by inelastic and quasi-elastic neutron scattering measurements. The results confirm the fast incorporation of [bmim]{sup +} into the lipid phase already observed in previous simulations, driven by the Coulomb attraction of the cation for the most electronegative oxygens in the POPC head group and by sizeable dispersion forces binding the neutral hydrocarbon tails of [bmim]{sup +} and of POPC. The [bmim]{sup +} absorption into the bilayer favours the penetration of water into POPC, causes a slight but systematic thinning of the bilayer, and further stabilises hydrogen bonds at the lipid/water interface that already in pure samples (no RTIL) display a lifetime much longer than in bulk water. On the other hand, the effect of RTILs on the diffusion constant of POPC (D{sub POPC}) does not reveal a clearly identifiable trend, since D{sub POPC} increases upon addition of [bmim][Cl] and decreases in the [bmim][PF{sub 6}] case. Moreover, because of screening, the electrostatic signature of each bilayer is only moderately affected by the addition of RTIL ions in solution. The analysis of long wavelength fluctuations of the bilayers shows that RTIL sorption causes a general decrease of the lipid/water interfacial tension and bending rigidity, pointing to the destabilizing effect of RTILs on lipid bilayers.

  9. High-Permeance Room-Temperature Ionic-Liquid-Based Membranes for CO2/N-2 Separation

    SciTech Connect

    Zhou, JS; Mok, MM; Cowan, MG; McDanel, WM; Carlisle, TK; Gin, DL; Noble, RD

    2014-12-24

    We have developed and fabricated thin-film composite (TFC) membranes with an active layer consisting of a room-temperature ionic liquid/polymerized (room-temperature ionic liquid) [i.e., (RTIL)/poly(RTIL)] composite material. The resulting membrane has a CO2 permeance of 6100 +/- 400 GPU (where 1 GPU = 10(-6) cm(3)/(cm(2) s cmHg)) and an ideal CO2/N-2 selectivity of 22 +/- 2. This represents a new membrane with state-of-the-art CO2 permeance and good CO2/N-2 selectivity. To our knowledge, this is the first example of a TFC gas separation membrane composed of an RTIL-containing active layer.

  10. Room-temperature ionic liquids and composite materials: platform technologies for CO(2) capture.

    PubMed

    Bara, Jason E; Camper, Dean E; Gin, Douglas L; Noble, Richard D

    2010-01-19

    Clean energy production has become one of the most prominent global issues of the early 21st century, prompting social, economic, and scientific debates regarding energy usage, energy sources, and sustainable energy strategies. The reduction of greenhouse gas emissions, specifically carbon dioxide (CO(2)), figures prominently in the discussions on the future of global energy policy. Billions of tons of annual CO(2) emissions are the direct result of fossil fuel combustion to generate electricity. Producing clean energy from abundant sources such as coal will require a massive infrastructure and highly efficient capture technologies to curb CO(2) emissions. Current technologies for CO(2) removal from other gases, such as those used in natural gas sweetening, are also capable of capturing CO(2) from power plant emissions. Aqueous amine processes are found in the vast majority of natural gas sweetening operations in the United States. However, conventional aqueous amine processes are highly energy intensive; their implementation for postcombustion CO(2) capture from power plant emissions would drastically cut plant output and efficiency. Membranes, another technology used in natural gas sweetening, have been proposed as an alternative mechanism for CO(2) capture from flue gas. Although membranes offer a potentially less energy-intensive approach, their development and industrial implementation lags far behind that of amine processes. Thus, to minimize the impact of postcombustion CO(2) capture on the economics of energy production, advances are needed in both of these areas. In this Account, we review our recent research devoted to absorptive processes and membranes. Specifically, we have explored the use of room-temperature ionic liquids (RTILs) in absorptive and membrane technologies for CO(2) capture. RTILs present a highly versatile and tunable platform for the development of new processes and materials aimed at the capture of CO(2) from power plant flue gas and in natural gas sweetening. The desirable properties of RTIL solvents, such as negligible vapor pressures, thermal stability, and a large liquid range, make them interesting candidates as new materials in well-known CO(2) capture processes. Here, we focus on the use of RTILs (1) as absorbents, including in combination with amines, and (2) in the design of polymer membranes. RTIL amine solvents have many potential advantages over aqueous amines, and the versatile chemistry of imidazolium-based RTILs also allows for the generation of new types of CO(2)-selective polymer membranes. RTIL and RTIL-based composites can compete with, or improve upon, current technologies. Moreover, owing to our experience in this area, we are developing new imidazolium-based polymer architectures and thermotropic and lyotropic liquid crystals as highly tailorable materials based on and capable of interacting with RTILs. PMID:19795831

  11. Metal-air cell comprising an electrolyte with a room temperature ionic liquid and hygroscopic additive

    DOEpatents

    Friesen, Cody A.; Krishnan, Ramkumar; Tang, Toni; Wolfe, Derek

    2014-08-19

    An electrochemical cell comprising an electrolyte comprising water and a hydrophobic ionic liquid comprising positive ions and negative ions. The electrochemical cell also includes an air electrode configured to absorb and reduce oxygen. A hydrophilic or hygroscopic additive modulates the hydrophobicity of the ionic liquid to maintain a concentration of the water in the electrolyte is between 0.001 mol % and 25 mol %.

  12. Modern Room Temperature Ionic Liquids, a Simple Guide to Understanding Their Structure and How It May Relate to Dynamics.

    PubMed

    Araque, Juan C; Hettige, Jeevapani J; Margulis, Claudio J

    2015-10-01

    Modern room temperature ionic liquids are structurally defined by symmetries on different length scales. Polar-apolar alternation defines their nanoscale structural heterogeneity, whereas positive-negative charge alternation defines short length scale order. Much progress has been made in the past few years as it pertains to the theoretical interpretation of X-ray scattering experiments for these liquids. Our group has contributed to the development of theoretical interpretation guidelines for the analysis of their structure function. Perhaps less well developed is our understanding of how transport and dynamics in general couple to the very unique structure of ionic liquids which are often dynamically and structurally heterogeneous. This article attempts to present our most current understanding of ionic liquid structure in general and its coupling to transport and dynamics in minimally technical terms for the benefit of the broadest audience. PMID:26244375

  13. Dispersion interactions in room-temperature ionic liquids: Results from a non-empirical density functional

    NASA Astrophysics Data System (ADS)

    Kohanoff, Jorge; Pinilla, Carlos; Youngs, Tristan G. A.; Artacho, Emilio; Soler, José M.

    2011-10-01

    The role of dispersion or van de Waals (VDW) interactions in imidazolium-based room-temperature ionic liquids is studied within the framework of density functional theory, using a recently developed non-empirical functional [M. Dion, H. Rydberg, E. Schröder, D. C. Langreth, and B. I. Lundqvist, Phys. Rev. Lett. 92, 246401 (2004), 10.1103/PhysRevLett.92.246401], as efficiently implemented in the SIESTA code [G. Román-Pérez and J. M. Soler, Phys. Rev. Lett. 103, 096102 (2009), 10.1103/PhysRevLett.103.096102]. We present results for the equilibrium structure and lattice parameters of several crystalline phases, finding a general improvement with respect to both the local density (LDA) and the generalized gradient approximations (GGA). Similar to other systems characterized by VDW bonding, such as rare gas and benzene dimers as well as solid argon, equilibrium distances and volumes are consistently overestimated by ≈7%, compared to -11% within LDA and 11% within GGA. The intramolecular geometries are retained, while the intermolecular distances and orientations are significantly improved relative to LDA and GGA. The quality is superior to that achieved with tailor-made empirical VDW corrections ad hoc [M. G. Del Pópolo, C. Pinilla, and P. Ballone, J. Chem. Phys. 126, 144705 (2007), 10.1063/1.2715571]. We also analyse the performance of an optimized version of this non-empirical functional, where the screening properties of the exchange have been tuned to reproduce high-level quantum chemical calculations [J. Klimes, D. Bowler, and A. Michaelides, J. Phys.: Condens. Matter 22, 074203 (2010), 10.1088/0953-8984/22/7/074203]. The results for solids are even better with volumes and geometries reproduced within 2% of experimental data. We provide some insight into the issue of polymorphism of [bmim][Cl] crystals, and we present results for the geometry and energetics of [bmim][Tf] and [mmim][Cl] neutral and charged clusters, which validate the use of empirical force fields.

  14. Dynamics of water, methanol, and ethanol in a room temperature ionic liquid

    NASA Astrophysics Data System (ADS)

    Kramer, Patrick L.; Giammanco, Chiara H.; Fayer, Michael D.

    2015-06-01

    The dynamics of a series of small molecule probes with increasing alkyl chain length: water, methanol, and ethanol, diluted to low concentration in the room temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, was investigated with 2D infrared vibrational echo (2D IR) spectroscopy and polarization resolved pump-probe (PP) experiments on the deuterated hydroxyl (O-D) stretching mode of each of the solutes. The long timescale spectral diffusion observed by 2D IR, capturing complete loss of vibrational frequency correlation through structural fluctuation of the medium, shows a clear but not dramatic slowing as the probe alkyl chain length is increased: 23 ps for water, 28 ps for methanol, and 34 ps for ethanol. Although in each case, only a single population of hydroxyl oscillators contributes to the infrared line shapes, the isotropic pump-probe decays (normally caused by population relaxation) are markedly nonexponential at short times. The early time features correspond to the timescales of the fast spectral diffusion measured with 2D IR. These fast isotropic pump-probe decays are produced by unequal pumping of the OD absorption band to a nonequilibrium frequency dependent population distribution caused by significant non-Condon effects. Orientational correlation functions for these three systems, obtained from pump-probe anisotropy decays, display several periods of restricted angular motion (wobbling-in-a-cone) followed by complete orientational randomization. The cone half-angles, which characterize the angular potential, become larger as the experimental frequency moves to the blue. These results indicate weakening of the angular potential with decreasing hydrogen bond strength. The slowest components of the orientational anisotropy decays are frequency-independent and correspond to the complete orientational randomization of the solute molecule. These components slow appreciably with increasing chain length: 25 ps for water, 42 ps for methanol, and 88 ps for ethanol. The shape and volume of the probe, therefore, impact reorientation far more severely than they do spectral diffusion at long times, though these two processes occur on similar timescales at earlier times.

  15. Dynamics of water, methanol, and ethanol in a room temperature ionic liquid.

    PubMed

    Kramer, Patrick L; Giammanco, Chiara H; Fayer, Michael D

    2015-06-01

    The dynamics of a series of small molecule probes with increasing alkyl chain length: water, methanol, and ethanol, diluted to low concentration in the room temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, was investigated with 2D infrared vibrational echo (2D IR) spectroscopy and polarization resolved pump-probe (PP) experiments on the deuterated hydroxyl (O-D) stretching mode of each of the solutes. The long timescale spectral diffusion observed by 2D IR, capturing complete loss of vibrational frequency correlation through structural fluctuation of the medium, shows a clear but not dramatic slowing as the probe alkyl chain length is increased: 23 ps for water, 28 ps for methanol, and 34 ps for ethanol. Although in each case, only a single population of hydroxyl oscillators contributes to the infrared line shapes, the isotropic pump-probe decays (normally caused by population relaxation) are markedly nonexponential at short times. The early time features correspond to the timescales of the fast spectral diffusion measured with 2D IR. These fast isotropic pump-probe decays are produced by unequal pumping of the OD absorption band to a nonequilibrium frequency dependent population distribution caused by significant non-Condon effects. Orientational correlation functions for these three systems, obtained from pump-probe anisotropy decays, display several periods of restricted angular motion (wobbling-in-a-cone) followed by complete orientational randomization. The cone half-angles, which characterize the angular potential, become larger as the experimental frequency moves to the blue. These results indicate weakening of the angular potential with decreasing hydrogen bond strength. The slowest components of the orientational anisotropy decays are frequency-independent and correspond to the complete orientational randomization of the solute molecule. These components slow appreciably with increasing chain length: 25 ps for water, 42 ps for methanol, and 88 ps for ethanol. The shape and volume of the probe, therefore, impact reorientation far more severely than they do spectral diffusion at long times, though these two processes occur on similar timescales at earlier times. PMID:26049428

  16. 81929 - Fission-Product Separation Based on Room - Temperature Ionic Liquids

    SciTech Connect

    Robin D. Rogers

    2004-12-09

    This project has demonstrated that Sr2+ and Cs+ can be selectively extracted from aqueous solutions into ionic liquids using crown ethers and that unprecedented large distribution coefficients can be achieved for these fission products. The volume of secondary wastes can be significantly minimized with this new separation technology. Through the current EMSP funding, the solvent extraction technology based on ionic liquids has been shown to be viable and can potentially provide the most efficient separation of problematic fission products from high level wastes. The key results from the current funding period are the development of highly selective extraction process for cesium ions based on crown ethers and calixarenes, optimization of selectivities of extractants via systematic change of ionic liquids, and investigation of task-specific ionic liquids incorporating both complexant and solvent characteristics.

  17. NOVEL FISSION PRODUCT SEPARATION BASED ON ROOM-TEMPERATURE IONIC LIQUIDS

    SciTech Connect

    Hussey, Charles L.

    2004-06-01

    The DoE/NE underground storage tanks at Hanford, SRS, and INEEL contain liquid wastes with high concentrations of radioactive species, mainly 137Cs and 90Sr. Because the other components of the liquid waste are mainly sodium nitrate and sodium hydroxide, most of this tank waste can be treated inexpensively as low-level waste if 137Cs and 90Sr can be selectively removed. Many ionophores (crown ether and calixarene compounds) have been synthesized for the purpose of selectively extracting Cs+ and Sr2+ from an aqueous phase into an immiscible organic phase. Recent studies conducted at ORNL1,2 reveal that hydrophobic ionic liquids might be better solvents for extracting metal ions from aqueous solutions with these ionophores than conventional immiscible organic solvents, such as benzene, toluene, and dichloromethane, because both Cs+ and Sr2+ exhibit larger distribution coefficients in the ionic liquids. In addition, the vapor pressures of these ionic liquids are insignificant. Thus, there is little or no vaporization loss of these solvents. Most of the ionic liquids under investigation are relatively nontoxic compared to the hydrocarbon solvents that they replace, classifying them as ''green'' solvents.

  18. Electrodeposition of platinum nanoparticles in a room-temperature ionic liquid.

    PubMed

    Zhang, Da; Chang, Wan Cheng; Okajima, Takeyoshi; Ohsaka, Takeo

    2011-12-01

    The electrochemistry of the [PtCl(6)](2-)-[PtCl(4)](2-)-Pt redox system on a glassy carbon (GC) electrode in a room-temperature ionic liquid (RTIL) [i.e., N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium tetrafluoroborate (DEMEBF(4))] has been examined. The two-step four-electron reduction of [PtCl(6)](2-) to Pt, i.e., reduction of [PtCl(6)](2-) to [PtCl(4)](2-) and further reduction of [PtCl(4)](2-) to Pt, occurs separately in this RTIL in contrast to the one-step four-electron reduction of [PtCl(6)](2-) to Pt in aqueous media. The cathodic and anodic peaks corresponding to the [PtCl(6)](2-)/[PtCl(4)](2-) redox couple were observed at ca. -1.1 and 0.6 V vs a Pt wire quasi-reference electrode, respectively, while those observed at -2.8 and -0.5 V were found to correspond to the [PtCl(4)](2-)/Pt redox couple. The disproportionation reaction of the two-electron reduction product of [PtCl(6)](2-) (i.e., [PtCl(4)](2-)) to [PtCl(6)](2-) and Pt metal was also found to occur significantly. The electrodeposition of Pt nanoparticles could be carried out on a GC electrode in DEMEBF(4) containing [PtCl(6)](2-) by holding the potential at -3.5 or -2.0 V. At -3.5 V, the four-electron reduction of [PtCl(6)](2-) to Pt can take place, while at -2.0 V the two-electron reduction of [PtCl(6)](2-) to [PtCl(4)](2-) occurs. The results obtained demonstrate that the electrodeposition of Pt at -3.5 V may occur via a series of reductions of [PtCl(6)](2-) to [PtCl(4)](2-) and further [PtCl(4)](2-) to Pt and at -2.0 V via a disproportionation reaction of [PtCl(4)](2-) to [PtCl(6)](2-) and Pt. Furthermore, the deposition potential of Pt nanoparticles was found to largely influence their size and morphology as well as the relative ratio of Pt(110) and Pt(100) crystalline orientation domains. The sizes of the Pt nanoparticles prepared by holding the electrode potential at -2.0 and -3.5 V are almost the same, in the range of ca. 1-2 nm. These small nanoparticles are "grown" to form bigger particles with different morphologies: In the case of the deposition at -2.0 V, the GC electrode surface is totally, relatively compactly covered with Pt particles of relatively uniform size of ca. 10-50 nm. On the other hand, in the case of the electrodeposition at -3.5 V, small particles of ca. 50-100 nm and the grown-up particles of ca. 100-200 nm cover the GC surface irregularly and coarsely. Interestingly, the Pt nanoparticles prepared by holding the potential at -2.0 and -3.5 V are relatively enriched in Pt(100) and Pt(110) facets, respectively. PMID:21995596

  19. Metal electrodeposition and electron transfer studies of uranium compounds in room temperature ionic liquids.

    SciTech Connect

    Stoll, M. E.; Oldham, W. J.; Costa, D. A.

    2004-01-01

    Room temperature ionic liquids (RTIL's) comprised of 1,3-dialkylimidazolium or quaternary ammonium cations and one of several anions such as PF{sub 6}{sup -}, BF{sub 4}{sup -}, or {sup -}N(SO{sub 2}CF{sub 3}){sub 2}, represent a class of solvents that possess great potential for use in applications employing electrochemical procedures. Part of the intrigue with RTIL's stems from some of their inherent solvent properties including negligible vapor pressure, good conductivity, high chemical and thermal stability, and non-flammability. Additionally, a substantial number of RTIL's can be envisioned simply by combining different cation and anion pairs, thereby making them attractive for specific application needs. We are interested in learning more about the possible use of RTIL's within the nuclear industry. In this regard our research team has been exploring the electron transfer behavior of simple metal ions in addition to coordination and organometallic complexes in these novel solvents. Results from our research have also provided us with insight into the bonding interactions between our current anion of choice, bis(trifluoromethylsulfonyl)imide = NTf{sub 2}, and open coordination sites on actinide and transition metal fragments. This presentation will focus on recent results in two areas: the electrodeposition of electropositive metal ions from RTIL solutions and the electron transfer behavior for several uranium complexes. Details concerning the cathodic electrodeposition and anodic stripping of alkali metals (Na, K) from various working electrode surfaces (Pt, Au, W, Glassy Carbon) will be discussed. Figure 1 displays typical behavior for the electrodeposition of potassium metal from an RTIL containing potassium ions produced through the reaction of KH with H[NTf{sub 2}]. Our efforts with other metal ions, including our results to date with uranium electrodeposition, will be covered during the presentation. The electron transfer behavior for a number of uranium complexes have been studied with various electrochemical methods including cyclic and square-wave voltammetry, chronoamperometry, and bulk coulometry. Results from these studies will be presented to show the general electron transfer behavior of metal complexes in the RTIL's. As an example, Figure 2 shows the difference in chemical stability of an electrogenerated U(V) anion for two uranyl (U(VI)O{sub 2}{sup 2+}) complexes due to the difference in ancillary ligands about the uranyl moiety. Figure 2a shows a cyclic voltammogram (CV) for the U(VI)/U(V) couple of a uranyl complex containing a multi-dentate chelating nitrogen/oxygen ligand (inset in figure). The couple is both chemically and electrochemically reversible. The CV in Figure 2b is that of [UO{sub 2}Cl{sub 4}]{sup 2-} in which the electrogenerated U(V) derivative is unstable yielding a chemically irreversible wave. For the compound giving rise to the CV in Figure 2a its electrochemical behavior in a conventional nonaqueous electrolyte medium is very similar to that obtained in the RTIL. While this result does not illustrate a distinct advantage for employing the RTIL solvent in this particular case, we believe it effectively demonstrates the ability of the RTIL to be utilized as a solvent/electrolyte medium for detailed electrochemical studies without severe limitations.

  20. NOvel Fission Product Separation Based on Room-Temperature Ionic liquids

    SciTech Connect

    Hussey, Charles L.

    2005-11-13

    The effective extraction of Cs+ and Sr2+ into a relatively new and heretofore untested hydrophobic ionic liquid, tri-n-butylmethylammonium bis[(trifluoromethyl)sulfonyl]imide was demonstrated with calix[4]arene-bis(tert-octylbenzo-crown-6) and dicyclohexano-18-crown-6, respectively. The coordinated Cs+ and Sr2+ were subsequently removed from the ionic liquid extraction solvent by an electrochemical reduction process carried out at mercury electrodes. This process is non-destructive, permitting the ionic liquid and ionophores to be recycled. Although the process is based on mercury electrodes, this is a benefit rather than a detriment because the liquid mercury containing the Cs and Sr can be easily transported to another electrochemical cell where the Cs and Sr could be electrochemically recovered from the mercury amalgam and concentrated into a minimum volume of water or some other inexpensive solvent. This should facilitate the development of a suitable waste form for the extracted Cs+ and Sr2+. Thus, the feasibility of the proposed ionic liquid-based extraction cycle for the removal of 137Cs+ and 90Sr2+ from simulated aqueous tank waste was demonstrated.

  1. DETERMINATION OF HENRY'S LAW CONSTANTS FOR VOCS IN ROOM TEMPERATURE IONIC LIQUIDS

    EPA Science Inventory

    Ionic liquids (ILs) have been shown to be a newer medium for a wide variety of chemical reactions and are considered as the potential replacements for traditional volatile organic solvents. However, the separation and recovery of organic compounds from ILs has not been systematic...

  2. FISSION-PRODUCT SEPARATION BASED ON ROOM-TEMPERATURE IONIC LIQUIDS

    EPA Science Inventory

    The objectives of this project are (a) to synthesize new ionic liquids tailored for the extractive separation of Cs + and Sr 2+; (b) to select optimum macrocyclic extractants through studies of complexation of fission products with macrocyclic extractants and transport in new ext...

  3. Visible photoluminescence of gold nanoparticles prepared by sputter deposition technique in a room-temperature ionic liquid

    NASA Astrophysics Data System (ADS)

    Iimori, Toshifumi; Hatakeyama, Yoshikiyo; Nishikawa, Keiko; Kato, Masako; Ohta, Nobuhiro

    2013-10-01

    Photoluminescence (PL) is observed for gold nanoparticles prepared by using sputter deposition technique and stably dispersed in a room-temperature ionic liquid of 1-butyl-3-methylimidazolium hexafluorophosphate. PL spectrum in the visible region depends on the excitation wavelength; the spectrum is shifted to longer wavelengths, as the excitation wavelength becomes longer, which probably comes from the size distribution of nanoparticles. Decay profiles as well as quantum yields of PL are measured at different excitation wavelengths. PL intensity shows a multiexponential decay, and the average lifetime, which depends on the excitation wavelength, is shorter than 3 ns.

  4. Electrochemistry and spectroscopy of electrolytes and cathode materials in room-temperature ionic liquids

    NASA Astrophysics Data System (ADS)

    Ryan, David Martin

    The demonstration of a stable, reversible, alkali metal anode is an important step in the development of practical secondary batteries using room temperature chloroaluminate molten salts as electrolytes. Such melts are made by mixing 1-ethyl-3-methylimidazolium chloride (EMIC) with aluminum chloride, and can be Lewis buffered by adding LiCl or NaCl. It has been shown previously that protons added to a sodium chloride buffered melt as 1-ethyl-3-methyfimidazolium hydrogen dichloride (EMIHCl2) provide a more negative voltage window and nearly reversible deposition-stripping behavior for sodium. It is reported here that triethanolamine hydrogen chloride is effective in widening the voltage window, allows the plating and stripping of both lithium and sodium, and is stable in buffered EMIC/AlCl3 melts for months. It is suggested that deprotonation of one ethanolic group of triethanolamine HCl is responsible for the effect. The electrochemistry and UV-visible spectroscopy of several vanadium oxides have been examined in room temperature melts. By varying the mole ratio of the two components, Lewis basic, neutral and acidic melts were made. Most oxides have very low solubility: V2O4 and V2O3 are insoluble and V2O5 has a solubility limit less than 5 mM, but the solubilities of the salts NaVO 3, Na3VO4, and NH4VO3, VOCl 3 and VOF3 are significantly higher. The electrochemistry of V2O5, NaVO3, Na3VO4, NH4VO3, VOCl3 and VOF3 is similar in neutral and acidic melts. In the neutral melt each compound shows an irreversible reduction at about 0.45V vs. an Al wire reference electrode. In an acidic melt (mole fraction AlCl3 = 0.55) each of these compounds exhibit additional reduction peaks at more positive potentials. Coulometric and spectroscopic data for the 0.45V reduction suggest that mixed oxidation state polyvanadates may be formed. Controlled potential coulometry demonstrated that the reduction at 0.45V was the reduction of V(V) to V(IV) and the more positive reduction peaks were caused by the reduction of some other species of V(V) present in the acidic melts. New room temperature melts have been prepared by mixing Lewis acidic, VOCl3, with Lewis basic, EMIC. The new melts are dark red homogeneous liquids that are very conductive and easily reduced.

  5. Electrochemical deposition of germanium sulfide from room-temperature ionic liquids and subsequent Ag doping in an aqueous solution.

    PubMed

    Murugesan, Sankaran; Kearns, Patrick; Stevenson, Keith J

    2012-04-01

    A facile room-temperature electrochemical deposition process for germanium sulfide (GeS(x)) has been developed with the use of an ionic liquid as an electrolyte. The electrodeposition mechanism follows the induced codeposition of Ge and S precursors in ionic liquids generating GeS(x) films. The electrodeposited GeS(x) films were characterized by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) and Raman and X-ray photoelectron spectroscopy (XPS). An aqueous-based Ag doping method was used to dope electrochemically grown GeS(x) films with controlled doping compared to the conventional process, which can be used in next-generation solid-state memory devices. PMID:22413744

  6. Characterization of a novel intrinsic luminescent room-temperature ionic liquid based on [P6,6,6,14 ][ANS].

    PubMed

    Delgado, Joana M; Raymundo, Anabela; Vilarigues, Mrcia; Branco, Lus C; Laia, Csar A T

    2015-01-01

    Intrinsically luminescent room-temperature ionic liquids (RTILs) can be prepared by combining a luminescent anion (more common) or cation with appropriate counter ions, rendering new luminescent soft materials. These RTILs are still new, and many of their photochemical properties are not well known. A novel intrinsic luminescent RTIL based on the 8-anilinonaphthalene-1-sulfonate ([ANS]) anion combined with the trihexyltetradecylphosphonium ([P6,6,6,14 ]) cation was prepared and characterized by spectroscopic techniques. Detailed photophysical studies highlight the influence of the ionic liquid environment on the ANS fluorescence, which together with rheological and (1) H?NMR experiments illustrate the effects of both the viscosity and electrostatic interactions between the ions. This material is liquid at room temperature and possesses a glass transition temperature (Tg ) of 230.4?K. The fluorescence is not highly sensitive to factors such as temperature, but owing to its high viscosity, dynamic Stokes shift measurements reveal very slow components for the IL relaxation. PMID:25124894

  7. Azoniaspiro salts: towards bridging the gap between room-temperature ionic liquids and molten salts.

    PubMed

    Clough, Matthew T; Geyer, Karolin; Hunt, Patricia A; McIntosh, Alastair J S; Rowe, Rebecca; Welton, Tom; White, Andrew J P

    2016-01-20

    In a continued effort to improve the suitability of ionic liquids in applications operating at raised temperatures, novel spirocyclic 'azoniaspiro' salts (with cations derived from five-, six-, seven- and eight-membered rings) are prepared and characterised. The structural and thermal properties of these salts are compared against those of established analogues. The stable geometries and ion pairing behaviour of these species are investigated via a combined experimental/computational approach, employing X-ray crystallography and Density Functional Theory (DFT) methods. Subsequently, the thermal stabilities of these organic salts are characterised and compared using a broad range of techniques. Hyphenated Thermogravimetry-Mass Spectrometry investigations enable complex mechanisms underlying thermal decomposition to be elucidated. Lastly, transition state structures are optimised, corresponding to plausible decomposition mechanisms of the azoniaspiro salt, 6-azoniaspiro[6.5]dodecanium chloride, and one prototypical monocyclic species 1-butyl-1-methylpiperidinium chloride, using DFT. The observed improved thermal stabilities of the azoniaspiro salts, and their potential higher-temperature stable-liquid ranges, render them promising candidates for future ionic liquid applications. PMID:26752136

  8. Preparation of nano/macroporous polycaprolactone microspheres for an injectable cell delivery system using room temperature ionic liquid and camphene.

    PubMed

    Kim, Seong Yeol; Hwang, Ji-Young; Shin, Ueon Sang

    2016-03-01

    The nano/macroporous polycaprolactone (PCL) microspheres with cell active surfaces were developed as an injectable cell delivery system. Room temperature ionic liquid (RTIL) and camphene were used as a liquid mold and a porogen, respectively. Various-sized spheres of 244-601?m with pores of various size and shape of 0.02-100?m, were formed depending on the camphene/RTIL ratio (0.8-2.6). To give cell activity, the surface of porous microspheres were further modified with nerve growth factors (NGF) containing gelatin to give a thin NGF/gelatin layer, to which the neural progenitor cells (PC-12) attached and extended their neurites on to the surface layers of the microspheres. The developed microspheres may be potentially applicable as a neuronal cell delivery scaffold for neuron tissue engineering. PMID:26641560

  9. Photodetachment, electron cooling, and recombination, in a series of neat aliphatic room temperature ionic liquids

    NASA Astrophysics Data System (ADS)

    Molins i Domenech, Francesc; Healy, Andrew T.; Blank, David A.

    2015-08-01

    Transient absorption following photodetachment of a series of neat methyl-alkyl-pyrrolidinium bis(trifluoromethylsulfonyl)amides at 6.20 eV was measured with sub-picosecond time resolution in the visible and near-IR portions of the spectrum. This series spans the onset of structuring in the liquids in the form of polarity alternation. Excitation promotes the electron into a delocalized state with a very large reactive radius. Strong transient absorption is observed in the visible spectrum with a 700 fs lifetime, and much weaker, long-lived absorption is observed in the near-IR spectrum. Absorption in the visible is shown to be consistent with the hole, and absorption in the near-IR is assigned to the free solvated electron. Yield of free electrons is estimated at 4%, is insensitive to the size of the cation, and is determined in less than 1 ps. Solvation of free electrons depends strongly on the size of the cation and correlates well with the viscosity of the liquid. In addition to radiolytic stability of the aliphatic cations, ultrafast, efficient recombination of separated charge in NTf2 - based ionic liquids following photo-excitation near the band-gap may prevent subsequent reactive damage associated with anions.

  10. Photodetachment, electron cooling, and recombination, in a series of neat aliphatic room temperature ionic liquids.

    PubMed

    Molins i Domenech, Francesc; Healy, Andrew T; Blank, David A

    2015-08-14

    Transient absorption following photodetachment of a series of neat methyl-alkyl-pyrrolidinium bis(trifluoromethylsulfonyl)amides at 6.20 eV was measured with sub-picosecond time resolution in the visible and near-IR portions of the spectrum. This series spans the onset of structuring in the liquids in the form of polarity alternation. Excitation promotes the electron into a delocalized state with a very large reactive radius. Strong transient absorption is observed in the visible spectrum with a ∼700 fs lifetime, and much weaker, long-lived absorption is observed in the near-IR spectrum. Absorption in the visible is shown to be consistent with the hole, and absorption in the near-IR is assigned to the free solvated electron. Yield of free electrons is estimated at ∼4%, is insensitive to the size of the cation, and is determined in less than 1 ps. Solvation of free electrons depends strongly on the size of the cation and correlates well with the viscosity of the liquid. In addition to radiolytic stability of the aliphatic cations, ultrafast, efficient recombination of separated charge in NTf2 (-) based ionic liquids following photo-excitation near the band-gap may prevent subsequent reactive damage associated with anions. PMID:26277144

  11. Electrochemistry of room temperature protic ionic liquids: a critical assessment for use as electrolytes in electrochemical applications.

    PubMed

    Lu, Xunyu; Burrell, Geoff; Separovic, Frances; Zhao, Chuan

    2012-08-01

    Ten room temperature protic ionic liquids (RTPILs) have been prepared from low-molecular-weight Brnsted acids and amines with high purity and minimal water content, and their electrochemical characteristics determined using cyclic, microelectrode, and rotating disk electrode voltammetries. Potential windows of the 10 RTPILs were established at glassy carbon, gold, and platinum electrodes, where the largest potential window is generally observed with glassy carbon electrodes. The two IUPAC recommended internal potential reference systems, ferrocene/ferrocenium and cobaltocenium/cobaltocene, were determined for the 10 RTPILs, and their merits as well as limitations are discussed. Other electrochemical properties such as mass transport and double layer capacitances were also investigated. The potential applications of these RTPILs as electrolytes for electrochemical energy devices were discussed, and two novel applications using PILs for metal deposition and water electrolysis were demonstrated. PMID:22784243

  12. Highly Efficient Extraction of Phenolic Compounds by Use of Magnetic Room Temperature Ionic Liquids for Environmental Remediation

    PubMed Central

    Deng, Ning; Li, Min; Zhao, Lijie; Lu, Chengfei; de Rooy, Sergio L.; Warner, Isiah M.

    2011-01-01

    A hydrophobic magnetic room temperature ionic liquid (MRTIL), trihexyltetradecylphosphonium tetrachloroferrate(III) ([3C6PC14][FeCl4]), was synthesized from trihexyltetradecylphosphonium chloride and FeCl36H2O. This MRTIL was investigated as a possible separation agent for solvent extraction of phenolic compounds from aqueous solution. Due to its strong paramagnetism, [3C6PC14][FeCl4] responds to an external neodymium magnet, which was employed in the design of a novel magnetic extraction technique. The conditions for extraction, including extraction time, volume ratio between MRTIL and aqueous phase, pH of aqueous solution, and structures of phenolic compounds were investigated and optimized. The magnetic extraction of phenols achieved equilibrium in 20 min and the phenolic compounds were found to have higher distribution ratios under acidic conditions. In addition, it was observed that phenols containing a greater number of chlorine or nitro substitutents exhibited higher distribution ratios. For example, the distribution ratio of phenol (DPh) was 107. In contrast, 3,5-dichlorophenol distribution ratio (D3,5-DCP) had a much higher value of 6372 under identical extraction conditions. When compared with four selected traditional non-magnetic room temperature ionic liquids, our [3C6PC14][FeCl4] exhibited significantly higher extraction efficiency under the same experimental conditions used in this work. Pentachlorophenol, a major component in the contaminated soil sample obtained from a superfund site, was successfully extracted and removed by use of [3C6PC14][FeCl4] with high extraction efficiency. Pentachlorophenol concentration was dramatically reduced from 7.8 ?g.mL?1 to 0.2 ?g.mL?1 after the magnetic extraction by use of [3C6PC14][FeCl4]. PMID:21783320

  13. Room temperature ionic liquids: A simple model. Effect of chain length and size of intermolecular potential on critical temperature

    NASA Astrophysics Data System (ADS)

    Chapela, Gustavo A.; Guzmn, Orlando; Daz-Herrera, Enrique; del Ro, Fernando

    2015-04-01

    A model of a room temperature ionic liquid can be represented as an ion attached to an aliphatic chain mixed with a counter ion. The simple model used in this work is based on a short rigid tangent square well chain with an ion, represented by a hard sphere interacting with a Yukawa potential at the head of the chain, mixed with a counter ion represented as well by a hard sphere interacting with a Yukawa potential of the opposite sign. The length of the chain and the depth of the intermolecular forces are investigated in order to understand which of these factors are responsible for the lowering of the critical temperature. It is the large difference between the ionic and the dispersion potentials which explains this lowering of the critical temperature. Calculation of liquid-vapor equilibrium orthobaric curves is used to estimate the critical points of the model. Vapor pressures are used to obtain an estimate of the triple point of the different models in order to calculate the span of temperatures where they remain a liquid. Surface tensions and interfacial thicknesses are also reported.

  14. Room temperature ionic liquids: A simple model. Effect of chain length and size of intermolecular potential on critical temperature.

    PubMed

    Chapela, Gustavo A; Guzmn, Orlando; Daz-Herrera, Enrique; del Ro, Fernando

    2015-04-21

    A model of a room temperature ionic liquid can be represented as an ion attached to an aliphatic chain mixed with a counter ion. The simple model used in this work is based on a short rigid tangent square well chain with an ion, represented by a hard sphere interacting with a Yukawa potential at the head of the chain, mixed with a counter ion represented as well by a hard sphere interacting with a Yukawa potential of the opposite sign. The length of the chain and the depth of the intermolecular forces are investigated in order to understand which of these factors are responsible for the lowering of the critical temperature. It is the large difference between the ionic and the dispersion potentials which explains this lowering of the critical temperature. Calculation of liquid-vapor equilibrium orthobaric curves is used to estimate the critical points of the model. Vapor pressures are used to obtain an estimate of the triple point of the different models in order to calculate the span of temperatures where they remain a liquid. Surface tensions and interfacial thicknesses are also reported. PMID:25903898

  15. Surface adsorption and vesicle formation of dilauroylphosphatidylcholine in room temperature ionic liquids.

    PubMed

    Inoue, Tohru; Aburai, Kenichi; Sakai, Hideki; Abe, Masahiko

    2012-07-01

    Surface chemical properties of a phospholipid, dilauroylphosphatidylcholine (DLPC), in two ionic liquids (ILs), 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF(4)) and hexafluorophosphate (bmimPF(6)), were investigated by means of surface tension, dynamic light-scattering, and freeze-fracture transmission electron microscopy. It was found that DLPC shows finite solubility in the ILs and spontaneously forms vesicles with size distribution around 400 nm in diameter above the critical vesicular concentration (CVC) of 0.040 wt.% (in bmimBF(4)) and approx. 0.08 wt.% (in bmimPF(6)). Other than the CVC value, anion specificity of the ILs was also seen in the temperature effect on the vesicular aggregation; that is, a temperature-induced reversible aggregation was observed in bmimPF(6), but not in bmimBF(4). The differences in the vesicular stability against the temperature-induced aggregation could be attributed to differences in the interaction between anion species of the ILs and zwitterionic phosphatidylcholine head groups. The apparent molecular area occupied by DLPC at the air/solution interface was estimated to be 0.37 nm(2) in bmimBF(4) and 0.20 nm(2) in bmimPF(6) by applying the Gibbs adsorption equation. These values are much smaller than the molecular area of 0.69 nm(2) reported for the hydrated DLPC bilayer of lamellar liquid-crystalline phase. This result is not consistent with the traditional Gibbs adsorption model, but can be interpreted in terms of a picture for the surface adsorption of soluble amphiphiles proposed by Moroi et al. Differential scanning calorimetric study is also reported regarding the phase transition behavior of DLPC bilayer solvated by the ILs. PMID:22542478

  16. Dynamics of electrical double layer formation in room-temperature ionic liquids under constant-current charging conditions

    SciTech Connect

    Jiang, Xikai; Huang, Jingsong; Zhao, Hui; Sumpter, Bobby G; Qiao, Rui

    2014-01-01

    We report detailed simulation results on the formation dynamics of an electrical double layer (EDL) inside an electrochemical cell featuring room-temperature ionic liquids (RTILs) enclosed between two planar electrodes. Under relatively small charging currents, the evolution of cell potential during charging can be suitably predicted by the Landau-Ginzburg-type continuum model proposed recently (M. Z. Bazant, B. D. Storey, and A. A. Kornyshev, Phys. Rev. Lett., 106, 046102, 2011). Under very large charging currents, the cell potential shows pronounced oscillation during the initial stage of charging, a feature not captured by the continuum model. Such oscillation originates from the sequential growth of the ionic space charge layers near the electrode surface, allowing the evolution of EDLs in RTILs with time, an atomistic process difficult to visualize experimentally, to be studied by analyzing the cell potential under constant current charging conditions. While the continuum model cannot predict the potential oscillation under such far-from-equilibrium charging conditions, it can nevertheless qualitatively capture the growth of cell potential during the later stage of charging. Improving the continuum model by introducing frequency-dependent dielectric constant and density-dependent ion diffusion coefficients may help to further extend the applicability of the model. Keywords: ionic

  17. Facile pretreatment of lignocellulosic biomass at high loadings in room temperature ionic liquids.

    PubMed

    Wu, Hong; Mora-Pale, Mauricio; Miao, Jianjun; Doherty, Thomas V; Linhardt, Robert J; Dordick, Jonathan S

    2011-12-01

    Ionic liquids (ILs) have emerged as attractive solvents for lignocellulosic biomass pretreatment in the production of biofuels and chemical feedstocks. However, the high cost of ILs is a key deterrent to their practical application. Here, we show that acetate based ILs are effective in dramatically reducing the recalcitrance of corn stover toward enzymatic polysaccharide hydrolysis even at loadings of biomass as high as 50% by weight. Under these conditions, the IL serves more as a pretreatment additive rather than a true solvent. Pretreatment of corn stover with 1-ethyl-3-methylimidizolium acetate ([Emim] [OAc]) at 125 ± 5°C for 1 h resulted in a dramatic reduction of cellulose crystallinity (up to 52%) and extraction of lignin (up to 44%). Enzymatic hydrolysis of the IL-treated biomass was performed with a common commercial cellulase/xylanase from Trichoderma reesei and a commercial β-glucosidase, and resulted in fermentable sugar yields of ∼80% for glucose and ∼50% for xylose at corn stover loadings up to 33% (w/w) and 55% and 34% for glucose and xylose, respectively, at 50% (w/w) biomass loading. Similar results were observed for the IL-facilitated pretreatment of switchgrass, poplar, and the highly recalcitrant hardwood, maple. At 4.8% (w/w) corn stover, [Emim][OAc] can be readily reused up to 10 times without removal of extracted components, such as lignin, with no effect on subsequent fermentable sugar yields. A significant reduction in the amount of IL combined with facile recycling has the potential to enable ILs to be used in large-scale biomass pretreatment. PMID:21769858

  18. Electrochemical gas sensors based on paper-supported room-temperature ionic liquids for improved analysis of acid vapours.

    PubMed

    Toniolo, Rosanna; Dossi, Nicolò; Pizzariello, Andrea; Casagrande, Alice; Bontempelli, Gino

    2013-04-01

    A prototype of a fast-response task-specific amperometric gas sensor based on paper-supported room-temperature ionic liquids (RTILs) is proposed here for improved analysis of volatile acid species. It consists of a small filter paper foil soaked with a RTIL mixture containing an ionic liquid whose anion (acetate) displays a basic character, upon which three electrodes are screen printed by carbon ink profiting from a suitable mask. It takes advantage of the high electrical conductivity and negligible vapour pressure of RTILs and of their easy immobilization into a porous and inexpensive supporting material such as paper. The performance of this device, used as a wall-jet amperometric detector for flow injection analyses of headspace samples in equilibrium with aqueous solutions at controlled concentrations, was evaluated for phenol and 1-butanethiol vapours which were adopted as model acid gaseous analytes. The results obtained showed that the quite high potentials required for the detection of these analytes are lowered significantly, thanks to the addition of the basic acetate RTIL. In such a way, overlap with the medium discharge is avoided, and the possible adverse effect of interfering species is minimised. The sensor performance was quite satisfactory (detection limits, ca. 0.3 μM; dynamic range, ca. 1-200 μM, both referred to solution concentrations; correlation coefficients in the range 0.993-0.997; repeatability, ± 6% RSD; long-term stability, 9%); thus suggesting the possible use of this device for manifold applications. PMID:23232956

  19. Screening out the non-Arrhenius behaviour of nematic-isotropic transition by room temperature ionic liquid.

    PubMed

    Dan, K; Datta, A; Yoshida, Y; Saito, G; Yoshikawa, K; Roy, M

    2016-02-28

    Differential Scanning Calorimetry (DSC) and optical polarization microscopy of a mixture of the liquid crystalline material (N-(4-methoxybenzylidene)-4-butylaniline, MBBA) and a Fe-based room temperature ionic liquid 1-ethyl-3-methylimidazolium tetrachloroferrate ([Emim](+) [FeCl4](-), EMIF) indicate a decrease in the nematic-isotropic (N-I) phase transition temperature (TNI) with an increase in EMIF concentration, explained by a proposed model of Coulomb "screening" of MBBA quadrupoles by the EMIF ions along with ionic "self screening." DSC studies of EMIF-MBBA and pure EMIF and comparison with pure MBBA results show that the major transitions in pure EMIF have Arrhenius behaviour, but more importantly the previously found convex Arrhenius behaviour of the pristine MBBA [K. Dan et al., Europhys. Lett. 108, 36007 (2014)] becomes Arrhenius in the mixture, indicating a conversion of the entropic N-I activation barrier to an enthalpic one. In presence of EMIF, a drastic decrease in the intensity of out-of-plane distortions of benzene rings in MBBA is found from Fourier transform infrared spectroscopy, consistent with significant reduction in the conformational states of MBBA. This suppression of large amplitude motion is again consistent with a Coulomb screening and gives a molecular basis for the entropic-to-enthalpic conversion of the N-I activation barrier. PMID:26931723

  20. Room-temperature ionic liquid-amine solutions: tunable solvents for efficient and reversible capture of CO{sub 2}

    SciTech Connect

    Dean Camper; Jason E. Bara; Douglas L. Gin; Richard D. Noble

    2008-11-05

    Solutions of room-temperature ionic liquids (RTILs) and commercially available amines were found to be effective for the capture of CO{sub 2} as carbamate salts. RTIL solutions containing 50 mol % (16% v/v) monoethanolamine (MEA) are capable of rapid and reversible capture of 1 mol of CO{sub 2} per 2 moles MEA to give an insoluble MEA-carbamate precipitate that helps to drive the capture reaction (as opposed to aqueous amine systems). Diethanolamine (DEA) can also be used in the same manner for CO{sub 2} capture in RTILs containing a pendant hydroxyl group. The captured CO{sub 2} in the resulting RTIL-carbamate salt mixtures can be readily released by either heating and/or subjecting them to reduced pressure. Using this unprecedented and industrially attractive mixing approach, the desirable properties of RTILs (i.e., nonvolatility, enhancedCO{sub 2} solubility, lower heat capacities) can be combined with the performance of amines for CO{sub 2} capture without the use of specially designed, functionalized 'task-specific' ionic liquids. By mixing RTILs with commercial amines, reactive solvents with a wide range of amine loading levels can be tailored to capture CO{sub 2} in a variety of conditions and processes. These RTIL-amine solutions behave similarly to their water-based counterparts but may offer many advantages, including increased energy efficiency, compared to current aqueous amine technologies.

  1. Dynamics of electrical double layer formation in room-temperature ionic liquids under constant-current charging conditions.

    PubMed

    Jiang, Xikai; Huang, Jingsong; Zhao, Hui; Sumpter, Bobby G; Qiao, Rui

    2014-07-16

    We report detailed simulation results on the formation dynamics of an electrical double layer (EDL) inside an electrochemical cell featuring room-temperature ionic liquids (RTILs) enclosed between two planar electrodes. Under relatively small charging currents, the evolution of cell potential from molecular dynamics (MD) simulations during charging can be suitably predicted by the Landau-Ginzburg-type continuum model proposed recently (Bazant et al 2011 Phys. Rev. Lett. 106 046102). Under very large charging currents, the cell potential from MD simulations shows pronounced oscillation during the initial stage of charging, a feature not captured by the continuum model. Such oscillation originates from the sequential growth of the ionic space charge layers near the electrode surface. This allows the evolution of EDLs in RTILs with time, an atomistic process difficult to visualize experimentally, to be studied by analyzing the cell potential under constant-current charging conditions. While the continuum model cannot predict the potential oscillation under such far-from-equilibrium charging conditions, it can nevertheless qualitatively capture the growth of cell potential during the later stage of charging. Improving the continuum model by introducing frequency-dependent dielectric constant and density-dependent ion diffusion coefficients may help to further extend the applicability of the model. The evolution of ion density profiles is also compared between the MD and the continuum model, showing good agreement. PMID:24919471

  2. Ion Transport and Local Structural Dynamics in Analogous Quaternary Ammonium and Phosphonium-Based Room Temperature Ionic Liquids

    NASA Astrophysics Data System (ADS)

    Holt, Adam; Griffin, Philip; Tsunashima, Katsuhiko; Sangoro, Joshua; Sokolov, Alexei

    2015-03-01

    The ion transport and structural dynamics in a homologous pair of quaternary ammonium and phosphonium based room temperature ionic liquids (IL), [N2228][NTF2] and [P2228][NTF2], are investigated by depolarized dynamic light scattering and dielectric spectroscopy. The atomic identity of the cation center has a pronounced effect on both long-range ion conduction as well as structural relaxation in these quaternary ILs. The dc conductivity is significantly higher in the phosphonium based IL. While the increase in dc conductivity can be attributed to a lower glass transition temperature, i.e. faster structural dynamics, of the phosphonium IL, we also have found the atomic identity of the cation center strongly influences the local secondary relaxations. The secondary relaxations in the ammonium IL exhibit an unexpected non-Arrhenius temperature dependence -in stark contrast to its phosphonium counterpart. In addition to structural dynamics, changes in the secondary relaxations suggest the differences in dc conductivity may also be attributed to a change in counter-ion coordination and could lead to a difference in the mesoscale aggregation of alkyl moieties which is known to exist in these ILs. Therefore, subtle changes of inter-ionic interactions have a direct consequence on local, structural, and long-range dynamics in these analogous ILs.

  3. Supported phospholipid bilayer interaction with components found in typical room-temperature ionic liquids - a QCM-D and AFM study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Quartz crystal microbalance with dissipation monitoring and atomic force microscopy were combined to evaluate the defects created by room-temperature ionic liquid anion and cation in a supported phospholipid bilayer composed of Zwitterionic lipids on a silica surface. The cation 1-octyl-3-methyl im...

  4. Radiation and radical chemistry of NO3(-), HNO3, and dialkylphosphoric acids in room-temperature ionic liquids.

    PubMed

    Shkrob, Ilya A; Marin, Timothy W; Chemerisov, S D; Wishart, J F

    2011-09-22

    Hydrophobic room-temperature ionic liquids (ILs) are considered as possible replacements for molecular diluents for nuclear separations, as well as the basis of new separations processes. Such applications may put the solvents both in high radiation fields and in contact with aqueous raffinate containing 1-6 M HNO(3). In this study, we address the effect of the extracted nitrate and nitric acid on the radiation chemistry of hydrophobic ILs composed of 1-alkyl-3-methylimidazolium cations (and closely related systems). We demonstrate that the nitrate anion competes with the solvent cation as an electron scavenger, with most of the primary radical species converted to NO(3)(2-) and NO(2)() that initiate a complex sequence of radical reactions. In hydrophobic ILs equilibrated with 3 M HNO(3), nearly all electrons released by the ionizing radiation are converted to NO(2)(). While the reductive pathway is strongly affected by the nitrate and there is also some N-O bond scission via direct excitation, the extent of interference with the oxidative pathway is relatively small; the cation damage is not dramatically affected by the presence of nitrate as most of the detrimental radiolytic products are generated via the oxidative pathway. These results are contrasted with the behavior of dialkylphosphoric acids (a large class of extraction agents for trivalent metal ions). We demonstrate that IL solvents protect these dialkylphosphoric acids against radiation-induced dealkylation. PMID:21823651

  5. Kinetic Effect on Pressure-Induced Phase Transitions of Room Temperature Ionic Liquid, 1-Ethyl-3-methylimidazolium Trifluoromethanesulfonate.

    PubMed

    Li, Haining; Wang, Zheng; Chen, Liucheng; Wu, Jie; Huang, Haijun; Yang, Kun; Wang, Yongqiang; Su, Lei; Yang, Guoqiang

    2015-11-01

    Room temperature ionic liquids (RTILs) have intriguing high-pressure phase behavior, and investigation of how pressure affects phase transitions of RTILs might yield interesting results. We here present kinetically driven phase transitions of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([Emim][CF3SO3]) at different rates of ?0.3 and ?1.2 GPa/h up to ?5 GPa. Two crystalline phases formed at ?1.3 and ?1.7 GPa with increasing pressure at lower compression rate of ?0.3 GPa/h; however, the amorphous phase solidified with superpressurized glass above ?3.3 GPa at higher compression rate of ?1.2 GPa/h. Notably, crystal polymorphism is discussed in view of the conformational isomerism of [Emim](+) cation and an unknown cation conformer is observed. These facts indicate that kinetic effect on pressure-induced phase transitions of [Emim][CF3SO3] might be dependent on compression rate, which needs to be considered as a non-negligible factor for phase transitions of RTILs under high pressure. PMID:26465251

  6. Effect of a room-temperature ionic liquid on the structure and properties of electrospun poly(vinylidene fluoride) nanofibers.

    PubMed

    Xing, Chenyang; Guan, Jipeng; Li, Yongjin; Li, Jingye

    2014-03-26

    Novel anti-static nanofibers based on blends of poly(vinylidene fluoride) (PVDF) and a room-temperature ionic liquid (RTIL), 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6], were fabricated using an electrospinning approach. The effects of the RTIL on the morphology, crystal structure, and physical properties of the PVDF nanofibers were investigated. Incorporation of RTIL leads to an increase in the mean fiber diameter and the rough fiber surface of the PVDF/RTIL composite nanofibers compared with the neat PVDF nanofibers. The PVDF in the PVDF/RTIL nanofibers exhibits an extremely high content (almost 100%) of ? crystals, in contrast to the dominance of PVDF ? crystals in bulk melt-blended PVDF/RTIL blends. Nonwoven fabrics produced from the electrospun PVDF/RTIL composite nanofibers show better stretchability and higher electrical conductivity than those made from neat PVDF without RTIL, and are thus excellent antielectrostatic fibrous materials. In addition, RTIL greatly improved the hydrophobicity of the PVDF fibers, enabling them to effectively separate a mixture of tetrachloromethane (CCl4) and water. The extremely high ? content, excellent antielectrostatic properties, better stretchability, and hydrophobicity of the present PVDF/RTIL nanofibers make them a promising candidate for micro- and nanoscale electronic device applications. PMID:24598382

  7. An electrochemical study of the oxidation of hydrogen at platinum electrodes in several room temperature ionic liquids.

    PubMed

    Silvester, Debbie S; Aldous, Leigh; Hardacre, Christopher; Compton, Richard G

    2007-05-10

    The electrochemical oxidation of dissolved hydrogen gas has been studied in a range of room-temperature ionic liquids (RTILs), namely [C(2)mim][NTf(2)], [C(4)mim][NTf(2)], [N(6,2,2,2)][NTf(2)], [P(14,6,6,6)][NTf(2)], [C(4)mpyrr][NTf(2)], [C(4)mim][BF(4)], [C(4)mim][PF(6)], [C(4)mim][OTf], and [C(6)mim]Cl on a platinum microdisk electrode of diameter 10 microm. In all cases, except [C(6)mim]Cl, a broad quasi-electrochemically reversible oxidation peak between 0.3 to 1.3 V vs Ag was seen prior to electrode activation ([C(6)mim]Cl showed an almost irreversible wave). When the electrode was pre-anodized ("activated") at 2.0 V vs Ag for 1 min, the peak separations became smaller, and the peak shape became more electrochemically reversible. It is thought that the electrogenerated protons chemically combine with the anions (A-) of the RTIL. The appearance and position of the reverse (reduction) peak on the voltammograms is thought to depend on three factors: (1) the stability of the protonated anion, HA, (2) the position of equilibrium of the protonation reaction HA<==> H+ + A- , and (3) any follow-up chemistry, e.g., dissociation or reaction of the protonated anion, HA. This is discussed for the five different anions studied. The reduction of HNTf(2) was also studied in two [NTf(2)]- -based RTILs and was compared to the oxidation waves from hydrogen. The results have implications for the defining of pKa in RTIL media, for the development of suitable reference electrodes for use in RTILs, and in the possible amperometric sensing of H2 gas. PMID:17284067

  8. The joint effects of room temperature ionic liquids and ordered media on fluorescence characteristics of estrogens in water and methanol.

    PubMed

    Wang, Huili; Duan, Ailian; Dahlgren, Randy A; Li, Yanyan; Li, Changli; Wang, Wenwei; Zeng, Aibing; Wang, Xuedong

    2014-07-15

    This study investigated the steady-state and time-resolved fluorescence properties of 17?-ethinylestradiol (EE2) and 17?-estradiol (E2) in the presence of ordered media (?-cyclodextrins (?-CD) and cetyltrimethylammonium bromide (CTAB)). In addition, we analyzed the effects of four room temperature ionic liquids (RTILs) on the fluorescence intensities (FIs) of EE2/?-CD and E2/?-CD inclusion complexes in methanol. Both ?-CD and CTAB enhanced the fluorescence of EE2 and E2. The FIs of EE2 and E2 with ?-CD or CTAB in methanol were greater than those in water, possibly resulting from decreased oxygen-quenching in H2O molecules. ?-CD and CTAB may form inclusion complexes with estrogen in both water and methanol. The inclusion ratio of the complex was 1:1 and the inclusion constant (K) values in water were greater than those in methanol. The fluorescence lifetimes were 2.50 and 4.13 ns for EE2 and 2.58 and 4.03 ns for E2 in aqueous solution and methanol, respectively. The changing trend of fluorescence lifetimes for EE2 and E2 in ?-CD or CTAB was similar to the steady-state FIs. The four RTILs had a significant quenching effect on the FIs of EE2/?-CD and E2/?-CD, and the quenching process for EE2/?-CD and E2/?-CD by RTILs was demonstrated to be a dynamic quenching mechanism. Fluorescent data obtained from these complex systems provide a theoretical foundation for understanding the interaction mechanisms between ordered media and RTILs in the analysis of estrogens. PMID:24685901

  9. The joint effects of room temperature ionic liquids and ordered media on fluorescence characteristics of estrogens in water and methanol

    NASA Astrophysics Data System (ADS)

    Wang, Huili; Duan, Ailian; Dahlgren, Randy A.; Li, Yanyan; Li, Changli; Wang, Wenwei; Zeng, Aibing; Wang, Xuedong

    2014-07-01

    This study investigated the steady-state and time-resolved fluorescence properties of 17α-ethinylestradiol (EE2) and 17β-estradiol (E2) in the presence of ordered media (β-cyclodextrins (β-CD) and cetyltrimethylammonium bromide (CTAB)). In addition, we analyzed the effects of four room temperature ionic liquids (RTILs) on the fluorescence intensities (FIs) of EE2/β-CD and E2/β-CD inclusion complexes in methanol. Both β-CD and CTAB enhanced the fluorescence of EE2 and E2. The FIs of EE2 and E2 with β-CD or CTAB in methanol were greater than those in water, possibly resulting from decreased oxygen-quenching in H2O molecules. β-CD and CTAB may form inclusion complexes with estrogen in both water and methanol. The inclusion ratio of the complex was 1:1 and the inclusion constant (K) values in water were greater than those in methanol. The fluorescence lifetimes were 2.50 and 4.13 ns for EE2 and 2.58 and 4.03 ns for E2 in aqueous solution and methanol, respectively. The changing trend of fluorescence lifetimes for EE2 and E2 in β-CD or CTAB was similar to the steady-state FIs. The four RTILs had a significant quenching effect on the FIs of EE2/β-CD and E2/β-CD, and the quenching process for EE2/β-CD and E2/β-CD by RTILs was demonstrated to be a dynamic quenching mechanism. Fluorescent data obtained from these complex systems provide a theoretical foundation for understanding the interaction mechanisms between ordered media and RTILs in the analysis of estrogens.

  10. Excess electron solvation in an imidazolium-based room-temperature ionic liquid revealed by ab initio molecular dynamics simulations.

    PubMed

    Wang, Zhiping; Zhang, Liang; Chen, Xiaohua; Cukier, Robert I; Bu, Yuxiang

    2009-06-18

    We present the first approach to the excess electron solvation in a novel medium, room-temperature ionic liquid, using ab initio molecular dynamics simulation techniques in this work. Results indicate that an excess electron can be solvated in the [dmim](+)Cl(-) IL as long-lived delocalized states and two short-lifetime localized states, one a single-cation-residence parasitical type and the other a double-cation-based solvated type state. The presence of a low-lying pi*-LUMO as the site of excess electron residence in the cation moiety disables the C-H unit as a H-bond donor, while the aromaticity requirement of the rings and the effect of the counterion Cl(-)'s make the resulting ion pairs a weak stabilizer for an excess electron. Although no large solvent reorganization in IL was found at the picosecond scale, the IL fluctuations sufficiently modify the relative energy levels of the excess electron states to permit facile state-to-state conversion and adiabatic migration. The binding energy of the excess electron is only approximately 0.2 eV, further indicating that it is in a quasi-free state, with a large drift mobility, suggesting that ILs are unreactive and promising mediators for transport of excess electrons, in agreement with the experimental findings. The present study provides insight into the novel electron solvation character in a new class of promising media for physical and chemical processes, which are fundamental for understanding of electron migration mechanisms in IL-based applications. PMID:19469567

  11. Effect of nitrate, perchlorate, and water on uranyl(VI) speciation in a room-temperature ionic liquid: a spectroscopic investigation.

    PubMed

    Pasilis, Sofie P; Blumenfeld, Alexander

    2011-09-01

    Room-temperature ionic liquids form potentially important solvents in novel nuclear waste reprocessing methods, and the solvation, speciation, and complexation behaviors of lanthanides and actinides in these solvents are of great current interest. In the study reported here, the coordination environment of uranyl(VI) in solutions of the room-temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][Tf(2)N]) containing perchlorate, tetrabutylammonium nitrate, and water was investigated using Raman, ATR-FTIR, and NMR spectroscopies in order to better understand the role played in uranyl(VI) solution chemistry in room-temperature ionic liquids by water and other small, weakly complexing ligands. The (2)H NMR chemical shift for water in a solution of uranyl perchlorate hexahydrate in [EMIM][Tf(2)N] appears at 6.52 ppm, indicating that water is coordinated to uranyl(VI). A broad ?(OH) stretching mode at 3370 cm(-1) in the ATR-FTIR spectrum shows that this coordinated water is engaged in hydrogen bonding with water molecules in a second coordination sphere. A significant upfield shift in the (2)H NMR signal for water and the appearance of distinct ?(as)(HOH) (at 3630 cm(-1)) and ?(s)(HOH) (at 3560 cm(-1)) vibrational bands in the ATR-FTIR spectra show that coordinated water is displaced by nitrate upon formation of the UO(2)(NO(3))(2) and UO(2)(NO(3))(3)(-) complexes. The Raman spectra indicate that perchlorate complexed to uranyl(VI) is also displaced by nitrate. Our results indicate that perchlorate and water, though weakly complexing ligands, do have a role in uranyl(VI) speciation in room-temperature ionic liquids and that Raman, infrared, and NMR spectroscopies are valuable additions to the suite of tools currently used to study the chemical behavior of uranyl(VI)-ligand complexes in these solvents. PMID:21786806

  12. Sum frequency generation spectroscopy of dicyanamide based room-temperature ionic liquids. Orientation of the cation and the anion at the gas-liquid interface.

    PubMed

    Aliaga, Cesar; Baldelli, Steven

    2007-08-23

    The orientation of the cation and the anion of room-temperature ionic liquids using sum frequency generation vibrational spectroscopy is reported. The ionic liquids are based on butyl-methyl imidazolium [BMIM]+ and hexyl-tributyl ammonium [N6444]+ together with dicyanamide [DCA]- as the anion. The tilt angle of the C3 axis of the methyl group from the alkyl chain in the cations was found to vary from 52 degrees to 80 degrees as a function of the distribution width sigma (which ranges from 0 degrees to 30 degrees with respect to the surface normal) for [BMIM][DCA] and similarly for [N6444][DCA]. The orientation of the C2 axis in the dicyanamide anion as a function of the twist angle phi, varied between 46 degrees and 90 degrees for [BMIM][DCA] and from 53 degrees to 90 degrees for [N6444][DCA]. These results suggest the presence of both ionic species at the gas-liquid interface and help describe the behavior of a simple inorganic anion at the surface. PMID:17661511

  13. Autocatalytic sonolysis of iron pentacarbonyl in room temperature ionic liquid [BuMeIm][Tf2N].

    PubMed

    Lartigue, Lenac; Pflieger, Rachel; Nikitenko, Sergey I; Guari, Yannick; Stievano, Lorenzo; Sougrati, Moulay T; Larionova, Joulia

    2011-02-14

    The autocatalytic sonochemical reaction of Fe(CO)(5) decomposition in [BuMeIm][Tf(2)N] provides iron nanoparticles in higher yields than in tetralin. Such a difference is explained by the higher decomposition of the intermediate Fe(3)(CO)(12) according to the two-sites model of the sonochemical reactions and the specific properties of the ionic liquid. PMID:21152579

  14. A protic ionic liquid catalyzes CO? conversion at atmospheric pressure and room temperature: synthesis of quinazoline-2,4(1H,3H)-diones.

    PubMed

    Zhao, Yanfei; Yu, Bo; Yang, Zhenzhen; Zhang, Hongye; Hao, Leiduan; Gao, Xiang; Liu, Zhimin

    2014-06-01

    The chemical fixation of CO2 under mild reaction conditions is of significance from a sustainable chemistry viewpoint. Herein a CO2-reactive protic ionic liquid (PIL), [HDBU(+)][TFE(-)], was designed by neutralization of the superbase 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) with a weak proton donor trifluoroethanol (TFE). As a bifunctional catalyst for simultaneously activating CO2 and the substrate, this PIL displayed excellent performance in catalyzing the reactions of CO2 with 2-aminobenzonitriles at atmospheric pressure and room temperature, thus producing a series of quinazoline-2,4(1H,3H)-diones in excellent yields. PMID:24788820

  15. Self-assembly of imidazolium-based surfactants in magnetic room-temperature ionic liquids: binary mixtures.

    PubMed

    Klee, Andreas; Prevost, Sylvain; Gradzielski, Michael

    2014-12-15

    The phase behaviour of binary mixtures of ionic surfactants (1-alkyl-3-imidazolium chloride, C(n)mimCl with n=14, 16 and 18) and imidazolium-based ionic liquids (1-alkyl-3-methylimidazolium tetrachloroferrate, C(n)mimFeCl4, with n=2 and 4) over a broad temperature range and the complete range of compositions is described. By using many complementary methods including differential scanning calorimetry (DSC), polarised microscopy, small-angle neutron and X-ray scattering (SANS/SAXS), and surface tension, the ability of this model system to support self-assembly is described quantitatively and this behaviour is compared with common water systems. The existence of micelles swollen by the solvent can be deduced from SANS experiments and represent a possible model for aggregates, which has barely been considered for ionic-liquid systems until now, and can be ascribed to the rather low solvophobicity of the surfactants. Our investigation shows that, in general, C(n)mimCl is a rather weak amphiphile in these ionic liquids. The amphiphilic strength increases systematically with the length of the alkyl chain, as seen from the phase behaviour, the critical micelle concentration, and also the level of definition of the aggregates formed. PMID:25314359

  16. Usefulness of reversed-phase HPLC enriched with room temperature imidazolium based ionic liquids for lipophilicity determination of the newly synthesized analgesic active urea derivatives.

    PubMed

    Flieger, Jolanta; Czajkowska-Żelazko, Anna; Rządkowska, Marzena; Szacoń, Elżbieta; Matosiuk, Dariusz

    2012-07-01

    Lipophilicity of several novel analgesic active 1-(1-arylimidazolidyn-2-ylidyn)-3-arylalkyl urea derivatives has been estimated by the use of chromatographic method. The investigated compounds were analyzed by reversed-phase high performance liquid chromatography (RP-HPLC) using mixtures of methanol or acetonitrile and water with addition of imidazolium based room temperature ionic liquids varying in an anion chaotropicity as the mobile phases. The relationships between log k values vs. concentration of organic solvent was used for determination of the log k(w) values by extrapolation technique. The partition coefficients (log P) values were calculated by means of the Pallas 3.1.1.2. and Spartan 10.0 softwares and further correlated with log k(w) measured experimentally in classical organic-aqueous eluent system and systems modified with ionic liquids addition. It was found that log k(w) values measured in eluent system modified with butyl-methyl imidazoilum chloride correlate the best with the logarithm of partition coefficient calculated by Pallas software (log P(calc.)). Furthermore, it was found that the examined compounds form H-bonding with imidazoilum cation of modifiers improving the chromatographic peak parameters (the symmetry factor, the theoretical plates number) especially when ionic liquid's anion was more chaotropic. Amphiphilic ionic liquid possessing longer alkyl chain substituent (OMIM BF(4)) can be considered as a new cationic surfactant. Micellar conditions improved separation selectivity of chloro- and methoxy substituted derivatives. PMID:22445825

  17. Quantitative prediction of physical properties of imidazolium based room temperature ionic liquids through determination of condensed phase site charges: a refined force field.

    PubMed

    Mondal, Anirban; Balasubramanian, Sundaram

    2014-03-27

    Quantitative prediction of physical properties of room temperature ionic liquids through nonpolarizable force field based molecular dynamics simulations is a challenging task. The challenge lies in the fact that mean ion charges in the condensed phase can be less than unity due to polarization and charge transfer effects whose magnitude cannot be fully captured through quantum chemical calculations conducted in the gas phase. The present work employed the density-derived electrostatic and chemical (DDEC/c3) charge partitioning method to calculate site charges of ions using electronic charge densities obtained from periodic density functional theory (DFT) calculations of their crystalline phases. The total ion charges obtained thus range between -0.6e for chloride and -0.8e for the PF6 ion. The mean value of the ion charges obtained from DFT calculations of an ionic liquid closely matches that obtained from the corresponding crystal thus confirming the suitability of using crystal site charges in simulations of liquids. These partial charges were deployed within the well-established force field developed by Lopes et al., and consequently, parameters of its nonbonded and torsional interactions were refined to ensure that they reproduced quantum potential energy scans for ion pairs in the gas phase. The refined force field was employed in simulations of seven ionic liquids with six different anions. Nearly quantitative agreement with experimental measurements was obtained for the density, surface tension, enthalpy of vaporization, and ion diffusion coefficients. PMID:24605817

  18. Trace determination of dichlorvos in environmental samples by room temperature ionic liquid-based dispersive liquid-phase microextraction combined with HPLC.

    PubMed

    Wang, Songhui; Xiang, Bingren; Tang, Qianqian

    2012-09-01

    Using 1-butyl-3-methylimidazolium hexa?uorophosphate ([BMIM][PF6]) room temperature ionic liquid (RTIL) as extraction solvent, tetrahydrofuran (THF) as disperser solvent, the organophosphorus pesticide dichlorvos in water was determined by dispersive liquid-liquid microextraction (DLLME) combined with high-performance liquid chromatography. Factors affecting RTIL-DLLME (type of disperser solvent, amount of RTIL, volume of disperser solvent, percentage of NaCl and volume and pH of water sample) were optimized by the single-factor method, obtaining the most favorable results when using 65 L of [BMIM][PF6] and 260 L of THF to extract the compound from an 8-mL water sample at pH 5.0 containing 25% (w/v) of NaCl. Under these optimum conditions, an enrichment factor of 215-fold was obtained. The calibration curves were linear in the concentration range of 2-1,000 g/L. The limit of detection calculated at a signal-to-noise ratio of 3 was 0.2 g/L. The relative standard deviations (RSD) for six replicate experiments at 20, 100 and 200 g/L concentration levels were 1.8%, 1.3% and 1.3 %, respectively. Then the proposed method was applied to the analysis of three different water sample sources (tap, farm and rain water) and the relative recoveries and RSD of spiked water samples were 95.6-102.4% and 0.6-3.1%, respectively, at three different concentration levels of 20, 100 and 200 g/L. PMID:22618021

  19. Bulk shear-mode contribution to thermally generated capillary waves on a room-temperature ionic-liquid surface.

    PubMed

    Ohmasa, Y; Hoshino, T; Osada, R; Yao, M

    2009-06-01

    In the present work, we show that the autocorrelation function of the capillary-wave displacement is expressed by the sum of the ordinary oscillator and the bulk shear-mode terms. The former is expressed by a simple damped oscillator form or a sum of exponentially damping functions depending on the extent of damping. The latter is also written by superposition of exponentially damping modes, and an analytically exact formulation is obtained. We performed surface dynamic light-scattering experiment for the surface of an ionic liquid, 1-butyl- 3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide, and compared the experimental autocorrelation function with the theoretical one. We observed for the first time the bulk shear-mode contribution, and confirmed that the experimental data is well explained by the theoretical autocorrelation function. PMID:19658509

  20. Carprofen-imprinted monolith prepared by reversible addition-fragmentation chain transfer polymerization in room temperature ionic liquids.

    PubMed

    Ban, Lu; Han, Xu; Wang, Xian-Hua; Huang, Yan-Ping; Liu, Zhao-Sheng

    2013-10-01

    To obtain fast separation, ionic liquids were used as porogens first in combination with reversible addition-fragmentation chain transfer (RAFT) polymerization to prepare a new type of molecularly imprinted polymer (MIP) monolith. The imprinted monolithic column was synthesized using a mixture of carprofen (template), 4-vinylpyridine, ethylene glycol dimethacrylate, [BMIM]BF4, and chain transfer agent (CTA). Some polymerization factors, such as template-monomer molar ratio, the degree of crosslinking, the composition of the porogen, and the content of CTA, on the column efficiency and imprinting effect of the resulting MIP monolith were systematically investigated. Affinity screening of structurally similar compounds with the template can be achieved in 200 s on the MIP monolith due to high column efficiency (up to 12,070 plates/m) and good column permeability. Recognition mechanism of the imprinted monolith was also investigated. PMID:23942589

  1. Atypical energetic and kinetic course of excited-state intramolecular proton transfer (ESIPT) in room-temperature protic ionic liquids.

    PubMed

    Manna, Arpan; Sayed, Mhejabeen; Kumar, Anil; Pal, Haridas

    2014-03-01

    The excited-state intramolecular proton-transfer (ESIPT) process in 1,8-dihydroxyanthraquinone (18DHAQ) dye has been investigated in protic ionic liquid (PIL) solvents using photochemical measurements. The results demonstrate noteworthy modulations in both steady-state and time-resolved emission characteristics of excited normal (N*) and tautomeric (T*) forms of the dye. That the emission of T* increases unexpectedly upon increasing solvent viscosity indicates that subsequent to the initial forward ESIPT, there is also a relatively slower back ESIPT process involved for the excited dye. It is inferred that the propensity of this back ESIPT process is determined by the dynamics of the diffusive solvent relaxation, a process that is known to be strongly viscosity-dependent in ionic liquids. Evidence of both forward and back ESIPT for the dye has been obtained from femtosecond fluorescence up-conversion measurements. While an unusually fast forward ESIPT is clearly observed in all of the PILs studied, the uncommon back ESIPT process is distinctly indicated in PIL solvents having lower viscosities, certainly due to reasonably fast diffusive solvent relaxation in these solvents that causes a temporal modulation in the energies of the normal and tautomeric forms within a reasonably short time and thereby brings down the energy of N* compared to that of T*, triggering the back ESIPT process. Observation of solvent-viscosity-dependent back ESIPT is an intriguing finding for the present study as to the best of our knowledge, such a behavior has so far not been reported in the literature for the ESIPT reaction. PMID:24524653

  2. Novel method of room temperature ionic liquid assisted Fe{sub 3}O{sub 4} nanocubes and nanoflakes synthesis

    SciTech Connect

    Ramalakshmi, M.; Shakkthivel, P.; Sundrarajan, M.; Chen, S.M.

    2013-08-01

    Graphical abstract: - Highlights: • First time [Bmim][TfO] IL is used for the Fe{sub 3}O{sub 4} nanoparticle synthesis. • Novel method tunes Fe{sub 3}O{sub 4} nanocubes and nanoflakes forms influenced by the base and IL. • Fe{sub 3}O{sub 4} oxidized topotactically into γ-Fe{sub 2}O{sub 3} nanoparticles by annealing and base. • Uniform morphology with average size of 33 nm negligible superstructure are formed. • Ms values are characterized by thin layer of γ-Fe{sub 2}O{sub 3} on the nanoparticle surface. - Abstract: For the first time, the nanomagnetite superparamagnetic particles are successfully synthesized by precipitation method using 1-n-butyl-3-methylimidazolium trifluoromethane sulfonate [Bmim][TfO] ionic liquid medium/surfactant. The obtained Fe{sub 3}O{sub 4} particles are nanocubes and nanoflakes and this formation is influenced by the base concentration and anisotropic circumstances produced by the ionic liquid and their size varies from 20 nm to 150 × 300 nm (width × length). The synthesized magnetite nanoparticles are characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, Field emission scanning electron microscopy (FE-SEM), Transmission electron microscopy (TEM) and Vibrating sample magnetometer (VSM) studies. The results show that the core of the Fe{sub 3}O{sub 4} nanoparticles is surrounded by a thin layer of γ-Fe{sub 2}O{sub 3} by topotactical partial oxidation, which is remarkably proceed with the subsequent calcination. The magnetite nanocubes have high saturation magnetization value and exhibit superparamagnetic hysteresis loop.

  3. Evaluation of solid-supported room-temperature ionic liquids containing crown ethers as media for metal ion separation and preconcentration.

    PubMed

    Hawkins, Cory A; Momen, M A; Garvey, Sarah L; Kestell, John; Kaminski, Michael D; Dietz, Mark L

    2015-04-01

    Extraction chromatographic (EXC) resins incorporating an appropriate crown ether in an oxygenated organic solvent such as 1-octanol are well established as sorbents for the analytical-scale separation and preconcentration of radiostrontium from a variety of sample types. Recent solvent extraction studies employing crown ethers in various 1-alkyl-3-methylimidazolium-based (CnC1im(+)) room-temperature ionic liquids (RTILs) indicate that under certain conditions, distribution ratios (DSr) for strontium far in excess of those observed with conventional organic solvents are observed. To determine if this increase in liquid-liquid extraction efficiency will lead to improved strontium sorbents, several EXC resins and sol-gel glasses incorporating di-tert-butylcyclohexano-18-crown-6 (DtBuCH18C6) in either 1-decyl-3-methylimidazolium bis[(trifluoromethyl)sulfonyl]imide (C10C1imTf2N) or the related hydroxyalkyl-functionalized IL 1-(12-hydroxydodecyl)-3-butylimidazolium bis[(trifluoromethyl)sulfonyl]imide (C12OHC4im Tf2N) were prepared and characterized. Unexpectedly the performance of these materials was not uniformly better than that of a conventional EXC resin, an apparent result of the greater viscosity of the ionic liquids and the lower solubility of the crown ether in ILs versus conventional organic solvents. PMID:25640134

  4. Low temperature and high pressure crystals of room temperature ionic liquid: N, N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium tetrafluoroborate

    NASA Astrophysics Data System (ADS)

    Abe, Hiroshi; Imai, Yusuke; Takekiyo, Takahiro; Yoshimura, Yukihiro; Hamaya, Nozomu

    2014-03-01

    Crystals of room temperature ionic liquid (RTIL) are obtained separately at low temperature or under high pressure. The RTIL is N, N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium tetrafluoroborate, [DEME][BF4]. At ambient pressure, low-temperature (LT) crystals appeared on slow cooling. By simultaneous X-ray diffraction and differential scanning calorimetry (DSC) measurements, metastable monoclinic and stable orthorhombic phases coexist in pure [DEME][BF4]. Furthermore, the DSC thermal trace indicates that the metastable monoclinic phase was stabilized by adding water. In contrast, on compression process up to 7.6 GPa, crystallization is completely suppressed even upon slow compression. Direct observations using optical microscopy also support no crystal domain growth on compression process. High-pressure (HP) crystals at room temperature were seen only on decompression process, where two different kinds of crystals appeared subsequently. By crystal structure analysis, the LT crystal structures have no relation with the HP ones. Moreover, both metastable monoclinic phase at low temperature and higher pressure crystal has a folding molecular conformation and anti-parallel pairing of the [DEME] cation as the instability factors.

  5. Application of room-temperature aprotic and protic ionic liquids for oxidative folding of cysteine-rich peptides.

    PubMed

    Heimer, Pascal; Tietze, Alesia A; Bhm, Miriam; Giernoth, Ralf; Kuchenbuch, Andrea; Stark, Annegret; Leipold, Enrico; Heinemann, Stefan H; Kandt, Christian; Imhof, Diana

    2014-12-15

    The oxidation of the conotoxin ?-SIIIA in different ionic liquids was investigated, and the results were compared with those obtained in [C2 mim][OAc]. Conversion of the reduced precursor into the oxidized product was observed in the protic ILs methyl- and ethylammonium formate (MAF and EAf, respectively), whereas choline dihydrogenphosphate and Ammoeng 110 failed to yield folded peptide. However, the quality and yield of the peptide obtained in MAF and EAF were lower than in the case of the product from [C2 mim][OAc]. Reaction conditions (temperature, water content) also had an impact on peptide conversion. A closer look at the activities of ?-SIIIA versions derived from an up-scaled synthesis in [C2 mim][OAc] revealed a significant loss of the effect on ion channel NaV 1.4 relative to the buffer-oxidized peptide, whereas digestion of either ?-SIIIA product by trypsin was unaffected. This was attributed to adherence of ions from the IL to the peptide, because the disulfide connectivity is basically the same for the differentially oxidized ?-SIIIA versions. PMID:25376613

  6. Ultrafast solvation response in room temperature ionic liquids: Possible origin and importance of the collective and the nearest neighbour solvent modes

    NASA Astrophysics Data System (ADS)

    Daschakraborty, Snehasis; Biswas, Ranjit

    2012-09-01

    Recent three-pulse photon echo peak shift (3PEPS) measurements [M. Muramatsu, Y. Nagasawa, and H. Miyasaka, J. Phys. Chem. A 115, 3886 (2011)], 10.1021/jp108282v with several room temperature ionic liquids (RTILs) have revealed multi-exponential dynamics with ultrafast solvation timescale in the range, 20 < ?1/fs < 250, for both imidazolium and phosphonium RTILs. This is striking for two reasons: (i) the timescale is much faster than those reported by the dynamic Stokes shift (DSS) experiments [S. Arzhantsev, H. Jin, G. A. Baker, and M. Maroncelli, J. Phys. Chem. B 111, 4978 (2007)], 10.1021/jp067273m and (ii) sub-hundered femtosecond solvation response in phosphonium ionic liquids is reported for the first time. Here, we present a mode coupling theory based calculation where such ultrafast solvation in 3PEPS measurements has been visualized to originate from the nearest neighbour solute-solvent interaction. Consideration of Lennard-Jones interaction for the nearest neighbour solute-solvent non-dipolar interaction leads to biphasic dynamics with a predicted ultrafast time constant in the 100-250 fs range, followed by a slower one similar to that reported by the 3PEPS measurements. In addition, the calculated fast time constants and amplitudes are found to be in general agreement with those from computer simulations. Different microscopic mechanisms for ultrafast solvation response measured by the 3PEPS and DSS experiments have been proposed and relative contributions of the collective and nearest neighbour solvent modes investigated. Relation between the single particle rotation and ultrafast polar solvation in these RTILs has been explored. Our analyses suggest 3PEPS and DSS experiments are probably sensitive to different components of the total solvation energy relaxation of a laser-excited dye in a given ionic liquid. Several predictions have also been made, which may be re-examined via suitable experiments.

  7. Ultrafast solvation response in room temperature ionic liquids: possible origin and importance of the collective and the nearest neighbour solvent modes.

    PubMed

    Daschakraborty, Snehasis; Biswas, Ranjit

    2012-09-21

    Recent three-pulse photon echo peak shift (3PEPS) measurements [M. Muramatsu, Y. Nagasawa, and H. Miyasaka, J. Phys. Chem. A 115, 3886 (2011)] with several room temperature ionic liquids (RTILs) have revealed multi-exponential dynamics with ultrafast solvation timescale in the range, 20 < ?(1)?fs < 250, for both imidazolium and phosphonium RTILs. This is striking for two reasons: (i) the timescale is much faster than those reported by the dynamic Stokes shift (DSS) experiments [S. Arzhantsev, H. Jin, G. A. Baker, and M. Maroncelli, J. Phys. Chem. B 111, 4978 (2007)] and (ii) sub-hundered femtosecond solvation response in phosphonium ionic liquids is reported for the first time. Here, we present a mode coupling theory based calculation where such ultrafast solvation in 3PEPS measurements has been visualized to originate from the nearest neighbour solute-solvent interaction. Consideration of Lennard-Jones interaction for the nearest neighbour solute-solvent non-dipolar interaction leads to biphasic dynamics with a predicted ultrafast time constant in the ?100-250 fs range, followed by a slower one similar to that reported by the 3PEPS measurements. In addition, the calculated fast time constants and amplitudes are found to be in general agreement with those from computer simulations. Different microscopic mechanisms for ultrafast solvation response measured by the 3PEPS and DSS experiments have been proposed and relative contributions of the collective and nearest neighbour solvent modes investigated. Relation between the single particle rotation and ultrafast polar solvation in these RTILs has been explored. Our analyses suggest 3PEPS and DSS experiments are probably sensitive to different components of the total solvation energy relaxation of a laser-excited dye in a given ionic liquid. Several predictions have also been made, which may be re-examined via suitable experiments. PMID:22998265

  8. Protein Crystallization Using Room Temperature Ionic Fluids

    NASA Technical Reports Server (NTRS)

    Pusey, Marc L.; Paley, Mark Steve; Turner, Megan B.; Rogers, Robin D.

    2006-01-01

    The ionic liquids (ILs) 1-butyl-3-methylimidizolium chloride (C4mim-C1), 1-butyl-3- methylimidizolium diethyleneglycol monomethylethersulfate ([C4mim]DEMGS), and 1-butyl-1 -methylpyrollidinium dihydrogenphosphate ([p1,4]dhp) were tested for their effects on the crystallization of the proteins canavalin, beta-lactoglobulin B, xylanase, and glucose isomerase, using a standard high throughput screen. The crystallization experiments were set up with the ILs added to the protein solutions at 0.2 and 0.4 M final concentrations. Crystallization droplets were set up at three proteixprecipitant ratios (1:1, 2:1, and 4:l), which served to progressively dilute the effects of the screen components while increasing the equilibrium protein and IL concentrations. Crystals were obtained for all four proteins at a number of conditions where they were not obtained from the IL-free control experiment. Over half of the protein-IL combinations tested had more successful outcomes than negative, where the IL-free crystallization was better than the corresponding IL-containing outcome, relative to the control. One of the most common causes of a negative outcome was solubilization of the protein by the IL, resulting in a clear drop. In one instance, we were able to use the IL-induced solubilizing to obtain beta-lactoglobulin B crystals from conditions that gave precipitated protein in the absence of IL. The results suggest that it may be feasible to develop ILs specifically for the task of macromolecule crystallization.

  9. Trace mercury determination in drinking and natural water samples by room temperature ionic liquid based-preconcentration and flow injection-cold vapor atomic absorption spectrometry.

    PubMed

    Martinis, Estefana M; Bertn, Paula; Olsina, Roberto A; Altamirano, Jorgelina C; Wuilloud, Rodolfo G

    2009-08-15

    A liquid-liquid extraction procedure (L-L) based on room temperature ionic liquid (RTIL) was developed for the preconcentration and determination of mercury in different water samples. The analyte was quantitatively extracted with 1-butyl-3-methylimidazolium hexafluorophosphate ([C(4)mim][PF(6)]) under the form of Hg-2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (Hg-5-Br-PADAP) complex. A volume of 500 microl of 9.0 mol L(-1) hydrochloric acid was used to back-extract the analyte from the RTIL phase into an aqueous media prior to its analysis by flow injection-cold vapor atomic absorption spectrometry (FI-CV-AAS). A preconcentration factor of 36 was achieved upon preconcentration of 20 mL of sample. The limit of detection (LOD) obtained under the optimal conditions was 2.3ngL(-1) and the relative standard deviation (RSD) for 10 replicates at 1 microg L(-1) Hg(2+) was 2.8%, calculated with peaks height. The method was successfully applied to the determination of mercury in river, sea, mineral and tap water samples and a certified reference material (CRM). PMID:19233554

  10. Ultrafast transient absorption spectrum of the room temperature Ionic liquid 1-hexyl-3-methylimidazolium bromide: Confounding effects of photo-degradation

    NASA Astrophysics Data System (ADS)

    Musat, Raluca M.; Crowell, Robert A.; Polyanskiy, Dmitriy E.; Thomas, Marie F.; Wishart, James F.; Katsumura, Yosuke; Takahashi, Kenji

    2015-12-01

    The photochemistry of the charge transfer (CT) band of the room temperature ionic liquid (RTIL) 1-hexyl-3-methylimidazolium bromide (HMIm+/Br-) is investigated using near-IR to vis ultrafast transient absorption (TA) and steady-state UV absorption spectroscopies. Continuous irradiation of the CT band at 266 nm results in the formation of photo-products that absorb strongly at 266 nm. It is shown that these photo-products, which are apparently very stable, adversely affect ultrafast TA measurements. Elimination of these effects reveals at least two transient species that exist within the TA detection window of 100 fs to 3 ns and 500-1250 nm. One of the components is a short-lived (<1 ps) species that absorbs at 1080 nm. The second band exhibits a multicomponent spectrum that is very broad with an absorption maximum around 600 nm and a lifetime that is longer than the 3 ns window of our TA spectrometer. Within the signal to noise ratio of the TA spectrometer little to no solvated electron is generated by the CT mechanism.

  11. Theinfluence of a hierarchical porous carbon network on the coherent dynamics of a nanoconfined room temperature ionic liquid: A neutron spin echo and atomistic simulation investigation

    SciTech Connect

    Banuelos, Jose Leo; Feng, Guang; Fulvio, Pasquale F; Li, Song; Rother, Gernot; Arend, Nikolas; Faraone, Antonio; Dai, Sheng; Cummings, Peter T; Wesolowski, David J

    2014-01-01

    The molecular-scale dynamic properties of the room temperature ionic liquid (RTIL) 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, or [C4mim+ ][Tf2N ], confined in hierarchical microporous mesoporous carbon, were investigated using neutron spin echo (NSE) and molecular dynamics (MD) simulations. Both NSE and MD reveal pronounced slowing of the overall collective dynamics, including the presence of an immobilized fraction of RTIL at the pore wall, on the time scales of these approaches. A fraction of the dynamics, corresponding to RTIL inside 0.75 nm micropores located along the mesopore surfaces, are faster than those of RTIL in direct contact with the walls of 5.8 nm and 7.8 nm cylindrical mesopores. This behavior is ascribed to the near-surface confined-ion density fluctuations resulting from the ion ion and ion wall interactions between the micropores and mesopores as well as their confinement geometries. Strong micropore RTIL interactions result in less-coordinated RTIL within the micropores than in the bulk fluid. Increasing temperature from 296 K to 353 K reduces the immobilized RTIL fraction and results in nearly an order of magnitude increase in the RTIL dynamics. The observed interfacial phenomena underscore the importance of tailoring the surface properties of porous carbons to achieve desirable electrolyte dynamic behavior, since this impacts the performance in applications such as electrical energy storage devices.

  12. Study of the translational diffusion of the benzophenone ketyl radical in comparison with stable molecules in room temperature ionic liquids by transient grating spectroscopy

    SciTech Connect

    Nishiyama, Y.; Fukuda, M.; Terazima, M.; Kimura, Y.

    2008-04-28

    Transient grating (TG) spectroscopy has been applied to the photoinduced hydrogen-abstraction reaction of benzophenone (BP) in various kinds of room temperature ionic liquids (RTILs). After the photoexcitation of BP in RTILs, the formation of a benzophenone ketyl radical (BPK) was confirmed by the transient absorption method, and the TG signal was analyzed to determine the diffusion coefficients of BPK and BP. For comparison, diffusion coefficients of carbon monoxide (CO), diphenylacetylene (DPA), and diphenylcyclopropenone (DPCP) in various RTILs were determined by the TG method using the photodissociation reaction of DPCP. While the diffusion coefficients of the stable molecules BP, DPA, and DPCP were always larger than those predicted by the Stokes-Einstein (SE) relation in RTILs, that of BPK was much smaller than those of the stable molecules and relatively close to that predicted by the SE relation in all solvents. For the smallest molecule CO, the deviation from the SE relation was evident. The diffusion coefficients of stable molecules are better represented by a power law of the inverse of the viscosity when the exponent was less than unity. The ratios of the diffusion coefficient of BP to that of BPK were larger in RTILs (2.7-4.0) than those (1.4-2.3) in conventional organic solvents. The slow diffusion of BPK in RTILs was discussed in terms of the fluctuation of the local electric field produced by the surrounding solvent ions.

  13. Electrodeposition of aluminium and aluminium-copper alloys from a room temperature ionic liquid electrolyte containing aluminium chloride and triethylamine hydrochloride

    NASA Astrophysics Data System (ADS)

    Suneesh, P. V.; Satheesh Babu, T. G.; Ramachandran, T.

    2013-09-01

    The electrodeposition of Al and Al-Cu binary alloys on to gold substrates from a room temperature ionic liquid electrolyte containing AlCl3-Et3NHCl was studied. The electrochemical behavior of the electrolyte and the mechanism of deposition were investigated through cyclic voltammetry (CV), and the properties of deposits obtained were assessed by scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDS) and X-ray diffraction (XRD). Al of 70 ?m in thickness and an Al-Cu alloy of 30 ?m in thickness with 8at% copper were deposited from the electrolyte. SEM images of the deposits indicate that the Al deposit was smooth and uniform, whereas the Al-Cu deposit was nodular. The average crystalline size, as determined by XRD patterns, was found to be (30 5) and (29 5) nm, respectively, for Al and Al-Cu alloys. Potentiodynamic polarization (Tafel plots) and electrochemical impedance spectroscopic (EIS) measurements showed that Al-Cu alloys are more corrosion resistant than Al.

  14. An electrochemical biosensor for alpha-fetoprotein based on carbon paste electrode constructed of room temperature ionic liquid and gold nanoparticles.

    PubMed

    Ding, Caifeng; Zhao, Fei; Ren, Rui; Lin, Jin-Ming

    2009-05-15

    A novel and effective electrochemical immunosensor for the rapid determination of alpha-fetoprotein (AFP) based on carbon paste electrode (CPE) consisting of room temperature ionic liquid (RTIL) N-butylpyridinium hexafluorophosphate (BPPF(6)) and graphite. The surface of the CPE was modified with gold nanoparticles for the immobilization of the alpha-fetoprotein antibody (anti-AFP). By sandwiching the antigen between anti-AFP on the CPE modified with gold nanoparticles and the secondary antibody, polyclonal anti-human-AFP labeled with horseradish peroxidase (HRP-labeled anti-AFP), the immunoassay was established. The concentration of AFP was determined based on differential pulse voltammetry (DPV) signal, which was generated in the reaction between O-aminophenol (OAP) and H(2)O(2) catalyzed by HRP labeled on the sandwich immunosensor. AFP concentration could be measured in a linear range of 0.50-80.00 ng mL(-1) with a detection limit of 0.25 ng mL(-1). The immunosensor exhibited high sensitivity and good stability, and would be valuable for clinical assay of AFP. PMID:19269485

  15. Physically Gelled Room-Temperature Ionic Liquid-Based Composite Membranes for CO2/N-2 Separation: Effect of Composition and Thickness on Membrane Properties and Performance

    SciTech Connect

    Nguyen, PT; Voss, BA; Wiesenauer, EF; Gin, DL; Nobe, RD

    2013-07-03

    An aspartame-based, low molecular-weight organic gelator (LMOG) was used to form melt-infused and composite membranes with two different imidazolium-based room-temperature ionic liquids (RTILs) for CO2 separation from N-2. Previous work demonstrated that LMOGs can gel RTILs at low, loading levels, and this aspartame-based LMOG was selected because it has been reported to gel a large number of RTILs. The imidazolium-based RTILs were used because of their inherent good properties for CO2/light gas separations. Analysis of the resulting bulk RTIL/LMOG physical gels showed that these materials have high sol-gel transition temperatures (ca. 135 degrees C) suitable for flue gas applications. Gas permeabilities and burst pressure measurements of thick, melt infused membranes revealed a trade-off between high CO2 permeabilities and good mechanical stability as a function of the LMOG loading. Defect-free, composite membranes of the gelled RTILs were successfully fabricated by choosing an appropriate porous membrane support (hydrophobic PTFE) using a suitable coating technique (roller coating). The thicknesses of the applied composite gel layers ranged from 10.3 to 20.7 mu m, which represents an order of magnitude decrease in active layer thickness, compared to the original melt-infused gel RTIL membranes.

  16. Quaternary ammonium room-temperature ionic liquid including an oxygen atom in side chain/lithium salt binary electrolytes: ab initio molecular orbital calculations of interactions between ions.

    PubMed

    Tsuzuki, Seiji; Hayamizu, Kikuko; Seki, Shiro; Ohno, Yasutaka; Kobayashi, Yo; Miyashiro, Hajime

    2008-08-14

    Interactions of the lithium bis(trifluoromethylsulfonyl)amide (LiTFSA) complex with N, N-diethyl-N-methyl-N-(2-methoxyethyl) ammonium (DEME), 1-ethyl-3-methylimidazolium (EMIM) cations, neutral diethylether (DEE), and the DEMETFSA complex were studied by ab initio molecular orbital calculations. An interaction energy potential calculated for the DEME cation with the LiTFSA complex has a minimum when the Li atom has contact with the oxygen atom of DEME cation, while potentials for the EMIM cation with the LiTFSA complex are always repulsive. The MP2/6-311G**//HF/6-311G** level interaction energy calculated for the DEME cation with the LiTFSA complex was -18.4 kcal/mol. The interaction energy for the neutral DEE with the LiTFSA complex was larger (-21.1 kcal/mol). The interaction energy for the DEMETFSA complex with LiTFSA complex is greater (-23.2 kcal/mol). The electrostatic and induction interactions are the major source of the attraction in the two systems. The substantial attraction between the DEME cation and the LiTFSA complex suggests that the interaction between the Li cation and the oxygen atom of DEME cation plays important roles in determining the mobility of the Li cation in DEME-based room temperature ionic liquids. PMID:18636771

  17. Study of the effect of tribo-materials and surface finish on the lubricant performance of new halogen-free room temperature ionic liquids

    NASA Astrophysics Data System (ADS)

    Saurín, N.; Minami, I.; Sanes, J.; Bermúdez, M. D.

    2016-03-01

    The present work evaluates different materials and surface finish in the presence of newly designed, hydrophobic halogen-free room temperature ionic liquids (RTILs) as lubricants. A reciprocating tribo-tester was employed with steel-ceramic and steel-thermosetting epoxy resin contacts under boundary lubrication conditions. Four different tetraalkylphosphonium organosilanesulfonate RTILs provided excellent lubricating performance, with friction coefficients as low as 0.057, and non-measurable wear for the higher roughness machine-finish stainless steel flat against sapphire balls, in the case of the lubricants containing the 2-trimethylsilylethanesulfonate anion. Higher friction coefficients of the order of 0.1 and wear volumes of the order of 10-4 mm3 were observed for the lower roughness fine-finished flat stainless steel surface. All RTILs prevent wear of epoxy resin against stainless steel balls, with friction coefficients in the range of 0.03-0.06. EDX analysis shows the presence of RTILs on the stainless steel surfaces after the tribological tests. Under the experimental conditions, no corrosive processes were observed.

  18. Structure and orientation of the imidazolium cation at the room-temperature ionic liquid/SiO2 interface measured by sum-frequency vibrational spectroscopy.

    PubMed

    Rollins, Julie B; Fitchett, Brian D; Conboy, John C

    2007-05-10

    In this study, we have examined both the effect of alkyl chain length and anion composition on the 1-alkyl-3-methylimidazolium (C(n)mim, n = 4, 6, 8, 10, and 12) structure and orientation at the room-temperature ionic liquid (RTIL)/SiO(2) interface by sum-frequency vibrational spectroscopy (SFVS). Four different anions were investigated in this study: tetrafluoroborate (BF(4)), hexafluorophosphate (PF(6)), bis(trifluoromethylsulfonyl)imide (BMSI), and bis(pentafluoroethylsulfonyl)imide (BETI). It was found that the alkyl chain in BMSI and BETI RTILs showed a decrease in gauche defects with an increase in chain length, whereas the alkyl chains of the BF(4) and PF(6) RTILs have virtually no gauche defects regardless of chain length. The tilt of the alkyl chain lies predominantly perpendicular to the surface for all the RTILs examined. A strong correlation between the HCCH vs tilt angle and alkyl chain length was observed; as the alkyl chain is lengthened the HCCH vs lies more perpendicular to the SiO(2) surface. The results of this study suggest that the length of the alkyl chain dictates to a large degree the orientation of the imidazolium cation at the surface, regardless of anion composition. To a lesser extent, the HCCH vs tilt of the imidazolium ring of the cation also appears to be correlated to the surface charge density of the SiO(2). As the SiO(2) surface charge density becomes more negative the HCCH vs tilt angle lies more parallel to the surface. PMID:17441750

  19. Synthesis and development of ordered, phase-separated, room-temperature ionic liquid-based AB and ABC block copolymers for gas separation applications

    NASA Astrophysics Data System (ADS)

    Wiesenauer, Erin F.

    CO2 capture process development is an economically and environmentally important challenge, as concerns over greenhouse gas emissions continue to receive worldwide attention. Many applications require the separation of CO 2 from other light gases such as N2, CH4, and H2 and a number of technologies have been developed to perform such separations. While current membrane technology offers an economical, easy to operate and scale-up solution, polymeric membranes cannot withstand high temperatures and aggressive chemical environments, and they often exhibit an unfavorable tradeoff between permeability and selectivity. Room-temperature ionic-liquids (RTILs) are very attractive as next-generation CO2-selective separation media and their development into polymerized membranes combat these challenges. Furthermore, polymers that can self-assemble into nanostructured, phase-separated morphologies (e.g., block copolymers, BCPs) have a direct effect on gas transport as materials morphology can influence molecular diffusion and membrane transport performance. In this thesis, nanophase-separated, RTIL-based AB and ABC di- and tri-BCPs were prepared via the sequential, living ring-opening metathesis polymerization (ROMP) of an IL-based monomer and one or more mutually immiscible co-monomers. This novel type of ion-containing BCP system forms various ordered nanostructures in the melt state via primary and secondary structure control. Monomer design and control of block composition, sequence, and overall polymer lengths were found to directly affect the ordered polymer assembly. Supported, composite membranes of these new BCPs were successfully fabricated, and the effect of BCP composition and nanostructure on CO2/light gas transport properties was studied. These nanostructured IL-based BCPs represent innovative polymer architectures and show great potential CO2/light gas membrane separation applications.

  20. Room-Temperature Liquid Crystal Blue Phases

    NASA Astrophysics Data System (ADS)

    Taushanoff, Stefanie; van Le, Khoa; Twieg, Robert; Jakli, Antal

    2009-03-01

    The ``blue phases'' of a highly chiral liquid crystal are defect-studded structures of double-twist cylinders that are laced together. The three phases, BPI*, BPII* and BPIII* differ only in the packing of the double-twist cylinders. Until recently, blue phases were of limited practical use because they appeared for only a very narrow temperature range. Mixtures that show BPI* and BPII* phases for wide temperature ranges at or around room temperature are now available [1]. Relatively wide temperature BPIII (the blue fog) phase so far was available only at very high temperatures [2]. Here we present mixtures with room-temperature wide range BPIII* phase and compare the ability of chiral dopants to form the different blue phases in a base nematic mixture. PDLC films cast with blue-phase material are also examined.[3pt] [1] H. Coles and M. Pivnenko, Nature 2005 436-18 997-1000 [0pt] [2] C. V. Yelamaggad, I. S. Shashikala, G. Liao, D.S. Shankar Rao, S. K. Prasad , Q. Li A. Jakli, Chem. Mater Comm, 2006, 18, 6100-6102

  1. Effect of Structure on Transport Properties (Viscosity, Ionic Conductivity, and Self-Diffusion Coefficient) of Aprotic Heterocyclic Anion (AHA) Room-Temperature Ionic Liquids. 1. Variation of Anionic Species.

    PubMed

    Sun, Liyuan; Morales-Collazo, Oscar; Xia, Han; Brennecke, Joan F

    2015-12-01

    A series of room temperature ionic liquids (RTILs) based on 1-ethyl-3-methylimidazolium ([emim](+)) with different aprotic heterocyclic anions (AHAs) were synthesized and characterized as potential electrolyte candidates for lithium ion batteries. The density and transport properties of these ILs were measured over the temperature range between 283.15 and 343.15 K at ambient pressure. The temperature dependence of the transport properties (viscosity, ionic conductivity, self-diffusion coefficient, and molar conductivity) is fit well by the Vogel-Fulcher-Tamman (VFT) equation. The best-fit VFT parameters, as well as linear fits to the density, are reported. The ionicity of these ILs was quantified by the ratio of the molar conductivity obtained from the ionic conductivity and molar concentration to that calculated from the self-diffusion coefficients using the Nernst-Einstein equation. The results of this study, which is based on ILs composed of both a planar cation and planar anions, show that many of the [emim][AHA] ILs exhibit very good conductivity for their viscosities and provide insight into the design of ILs with enhanced dynamics that may be suitable for electrolyte applications. PMID:26505641

  2. An efficient ultrasound assisted approach for the impregnation of room temperature ionic liquid onto Dowex 1×8 resin matrix and its application toward the enhanced adsorption of chromium (VI).

    PubMed

    Kalidhasan, S; Kumar, A Santhana Krishna; Rajesh, Vidya; Rajesh, N

    2012-04-30

    The work discussed in this paper is based on the utilization of ultrasound in conjunction with an ionic liquid (Aliquat 336) impregnated Dowex 1×8 resin for the effective adsorption of chromium. Ionic liquids are known for their selectivity toward metal extraction and ultrasonic medium offers efficient energy transfer for impregnating the ionic liquid in the resin matrix. The molecular interaction between the ionic liquid impregnated resin and chromium was studied through various physicochemical and spectroscopic techniques. The influence of various analytical parameters on the adsorption of Cr(VI) such as pH, adsorbent dosage, temperature and interference of foreign ions was studied in detail. Chromium (VI) was quantitatively adsorbed in the pH range of 3.5-4, with a high adsorption capacity of 230.9 mg g(-1) in conformity with the Langmuir isotherm model. The study of thermodynamic parameters showed that the adsorption process is exothermic and spontaneous. The adsorbent could be regenerated using 1 mol L(-1) HCl-0.28 mol L(-1) ascorbic acid mixture. Chromium could be effectively detoxified from an industrial effluent and finally the developed method was validated with the analysis of a certified reference material (BCR-715). The obtained results indicated that the ultrasonic assisted impregnation of the room temperature ionic liquid significantly enhances and improves the removal efficiency of Cr(VI). PMID:22365143

  3. Crystal polymorphism of a room-temperature ionic liquid, 1,3-dimethylimidazolium hexafluorophosphate: Calorimetric and structural studies of two crystal phases having melting points of 50 K difference

    NASA Astrophysics Data System (ADS)

    Endo, Takatsugu; Morita, Takeshi; Nishikawa, Keiko

    2011-12-01

    We found crystal polymorphism of a room-temperature ionic liquid (RTIL), 1,3-dimethylimidazolium hexafluorophosphate, by a laboratory-built calorimeter with a precise temperature controller. This polymorphism differs from hitherto reported phase behavior of other RTILs that the present RTIL lacks conformational flexibility in the associated ions. In addition, the observed difference between the melting points of two crystals, 364.3 and 314.3 K, is much larger than those reported for other polymorphic RTIL crystals. Their crystal structures were studied by Raman spectroscopy and X-ray powder diffraction. The origin of these characteristics is discussed in terms of entropy and cation-anion interactions.

  4. Photoinduced electron transfer (PET) from N, N-dimethylaniline to 7-amino Coumarin dyes in a room temperature ionic liquid (RTIL): Slowing down of electron transfer rate compared to conventional solvent

    NASA Astrophysics Data System (ADS)

    Sarkar, Souravi; Pramanik, Rajib; Seth, Debabrata; Setua, Palash; Sarkar, Nilmoni

    2009-07-01

    In this Letter we have investigated the photoinduced electron transfer (PET) in a protic room temperature ionic liquid (PRTIL) comprised of non-aromatic cation and anion, N, N-dimethyl ethanol ammonium formate (DAF) to investigate how the dynamics of PET is affected in RTIL compared to other solvents. The photoinduced electron transfer rate in the ionic liquid DAF decreases by an order of magnitude upon going from the conventional solvent acetonitrile. We have observed saturation, i.e., a Rehm-Weller type of behaviour in the electron transfer rate. The ET rate ( k q) vs. -?G 0 plot shows saturation to a diffusion-controlled value at the higher exergonicity region.

  5. Extraction and separation of thorium(IV) from lanthanides(III) with room-temperature ionic liquids containing primary amine N{sub 1923}

    SciTech Connect

    Zuo, Y.; Chen, J.; Bai, Y.; Li, D.Q.

    2008-07-01

    The extraction behavior of Th(IV) by primary amine N{sub 1923} in imidazolium-based ionic liquid namely 1-octyl-3-methylimidazolium hexafluorophosphate (N{sub 1923}/IL) was studied in this paper. Results showed that N{sub 1923}/IL had poorer extraction ability for Th(IV) than N{sub 1923} in n-heptane (N{sub 1923}/HEP). The separation coefficients between Th(IV) and lanthanides(III) ({beta}{sub Th/Ln}) were obtained and compared with those in the N{sub 1923}/HEP system. On this basis, we made a preliminary assessment for the possibility of using ionic liquids as solvents for the separation of Th(IV) from lanthanides(III) sulfate in a clean process. (authors)

  6. Li/LiFePO4 batteries with gel polymer electrolytes incorporating a guanidinium-based ionic liquid cycled at room temperature and 50 C

    NASA Astrophysics Data System (ADS)

    Li, Mingtao; Yang, Li; Fang, Shaohua; Dong, Siming; Jin, Yide; Hirano, Shin-ichi; Tachibana, Kazuhiro

    2011-08-01

    Gel polymer electrolytes composed of PVdF-HFP microporous membrane incorporating a guanidinium-based ionic liquid with 0.8 mol kg-1 lithium bis(trifluoromethanesulfonylimide) are characterized as the electrolytes in Li/LiFePO4 batteries. The ionic conductivity of these gel polymer electrolytes is 3.16 10-4 and 8.32 10-4 S cm-1 at 25 and 50 C, respectively. The electrolytes show good interfacial stability towards lithium metal and high oxidation stability, and the decomposition potential reaches 5.3 and 4.6 V (vs. Li/Li+) at 25 and 50 C, respectively. Li/LiFePO4 cells using the PVdF-HFP/1g13TFSI-LiTFSI electrolytes show good discharge capacity and cycle stability, and no significant loss in discharge capacity of the battery is observed over 100 cycles. The cells deliver the capacity of 142 and 150 mAh g-1 at the 100th cycling at 25 and 50 C, respectively.

  7. Probing solute-solvent interaction in 1-ethyl-3-methylimidazolium-based room temperature ionic liquids: A time-resolved fluorescence anisotropy study.

    PubMed

    Das, Sudhir Kumar; Sarkar, Moloy

    2013-10-26

    Rotational diffusion of two organic solutes, coumarin153 (C153) and 4-aminophthalimide (AP) has been investigated in four ionic liquids (ILs), viz. 1-ethyl-3-methylimidazolium trifluoroacetate (EMIMTFA), 1-ethyl-3-methylimidazolium ethylsulfate (EMIMESU), 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMTFB) and 1-ethyl-3-methylimidazolium tetracyanoborate (EMIMTCB), as a function of temperature. Between the two probes, AP can act as hydrogen-bond-donor to the solvents having hydrogen bond acceptor ability. The results indicate that the rotational dynamics of C153 is mainly governed by the viscosity of the medium. On the other hand, the rotational motion of AP is found to be significantly hindered in the ILs depending on the nature of anions of the ILs. Rotational coupling constant values for AP in the ILs follow the order TFA?>?ESU?>?TCB?>?TFB. The slower rotational motion of AP in these ILs has been attributed to the specific hydrogen bonding interaction between AP and anions of ILs. PMID:24158315

  8. Effect of Temperature on the Physico-Chemical Properties of a Room Temperature Ionic Liquid (1-Methyl-3-pentylimidazolium Hexafluorophosphate) with Polyethylene Glycol Oligomer

    PubMed Central

    Wu, Tzi-Yi; Chen, Bor-Kuan; Hao, Lin; Peng, Yu-Chun; Sun, I-Wen

    2011-01-01

    A systematic study of the effect of composition on the thermo-physical properties of the binary mixtures of 1-methyl-3-pentyl imidazolium hexafluorophosphate [MPI][PF6] with poly(ethylene glycol) (PEG) [Mw = 400] is presented. The excess molar volume, refractive index deviation, viscosity deviation, and surface tension deviation values were calculated from these experimental density, ρ, refractive index, n, viscosity, η, and surface tension, γ, over the whole concentration range, respectively. The excess molar volumes are negative and continue to become increasingly negative with increasing temperature; whereas the viscosity and surface tension deviation are negative and become less negative with increasing temperature. The surface thermodynamic functions, such as surface entropy, enthalpy, as well as standard molar entropy, Parachor, and molar enthalpy of vaporization for pure ionic liquid, have been derived from the temperature dependence of the surface tension values. PMID:21731460

  9. Direct electrochemistry and electrocatalysis of heme proteins immobilised in carbon-coated nickel magnetic nanoparticle-chitosan-dimethylformamide composite films in room-temperature ionic liquids.

    PubMed

    Wang, Ting; Wang, Lu; Tu, Jiaojiao; Xiong, Huayu; Wang, Shengfu

    2013-12-01

    The direct electrochemistry and electrocatalysis of heme proteins entrapped in carbon-coated nickel magnetic nanoparticle-chitosan-dimethylformamide (CNN-CS-DMF) composite films were investigated in the hydrophilic ionic liquid [bmim][BF4]. The surface morphologies of a representative set of films were characterised via scanning electron microscopy. The proteins immobilised in the composite films were shown to retain their native secondary structure using UV-vis spectroscopy. The electrochemical performance of the heme proteins-CNN-CS-DMF films was evaluated via cyclic voltammetry and chronoamperometry. A pair of stable and well-defined redox peaks was observed for the heme protein films at formal potentials of -0.151 V (HRP), -0.167 V (Hb), -0.155 V (Mb) and -0.193 V (Cyt c) in [bmim][BF4]. Moreover, several electrochemical parameters of the heme proteins were calculated by nonlinear regression analysis of the square-wave voltammetry. The addition of CNN significantly enhanced not only the electron transfer of the heme proteins but also their electrocatalytic activity toward the reduction of H2O2. Low apparent Michaelis-Menten constants were obtained for the heme protein-CNN-CS-DMF films, demonstrating that the biosensors have a high affinity for H2O2. In addition, the resulting electrodes displayed a low detection limit and improved sensitivity for detecting H2O2, which indicates that the biocomposite film can serve as a platform for constructing new non-aqueous biosensors for real detection. PMID:23632434

  10. Photorheological ionic liquids.

    PubMed

    Av, Joo; Cidade, M T; Rodriguez, Vincent; Lima, Joo C; Parola, A Jorge

    2015-06-01

    Two room temperature ionic liquids (ILs) bearing coumarin and p-hydroxycinnamic acid moieties are synthesized, and their photochemistry is studied in solution and neat conditions. Irradiation at absorption maxima leads to photochemical transformations and results in changes of their rheological properties which are evaluated by rotational rheometry. Samples of ionic liquids are also studied by Hyper-Rayleigh scattering, and the effect of their photochemistry on ionic nanoaggregation is discussed. PMID:25970078

  11. Synthesis of ionic liquids

    DOEpatents

    Dai, Sheng [Knoxville, TN; Luo, Huimin [Knoxville, TN

    2008-09-09

    Ionic compounds which are liquids at room temperature are formed by the method of mixing a neutral organic liqand with the salt of a metal cation and its conjugate anion. The liquids are hydrophobic, conductive and stable and have uses as solvents and in electrochemical devices.

  12. Synthesis of ionic liquids

    DOEpatents

    Dai, Sheng (Knoxville, TN); Luo, Huimin (Knoxville, TN)

    2011-11-01

    Ionic compounds which are liquids at room temperature are formed by the method of mixing a neutral organic ligand with the salt of a metal cation and its conjugate anion. The liquids are hydrophobic, conductive and stable and have uses as solvents and in electrochemical devices.

  13. Thermally stable AgI quantum-dot-based room-temperature fast ionic conductors.

    PubMed

    Xu, Biao; Wang, Xun

    2011-12-16

    AgI quantum dot (QD)-based room-temperature fast ionic conductors are prepared via an aqueous route. New phase behavior and good performance are found in this material. This is a prototype of quantum dot-ionics. PMID:22038711

  14. Surface exploration of a room-temperature ionic liquid-chitin composite film decorated with electrochemically deposited PdFeNi trimetallic alloy nanoparticles by pattern recognition: an elegant approach to developing a novel biotin biosensor.

    PubMed

    Gholivand, Mohammad-Bagher; Jalalvand, Ali R; Goicoechea, Hector C; Paimard, Giti; Skov, Thomas

    2015-01-01

    In this study, a novel biosensing system for the determination of biotin (BTN) based on electrodeposition of palladium-iron-nickel (PdFeNi) trimetallic alloy nanoparticles (NPs) onto a glassy carbon electrode (GCE) modified with a room-temperature ionic liquid (RTIL)-chitin (Ch) composite film (PdFeNi/ChRTIL/GCE) is established. NPs have a wide range of applications in science and technology and their sizes are often measured using transmission electron microscopy (TEM) or X-ray diffraction. Here, we used a pattern recognition method (digital image processing, DIP) for measuring particle size distributions (PSDs) from scanning electron microscopic (SEM) images in the presence of an uneven background. Different depositions were performed by varying the number of cyclic potential scans (N) during electroreduction step. It was observed that the physicochemical properties of the deposits were correlated to the performance of the PdFeNi/ChRTIL/GCE with respect to BTN assay. The best results were obtained for eight electrodeposition cyclic scans, where small-sized particles (19.54 ± 6.27 nm) with high density (682 particles µm(-2)) were obtained. Under optimized conditions, a linear range from 2.0 to 44.0 × 10(-9) mol L(-1) and a limit of detection (LOD) of 0.6 × 10(-9) mol L(-1) were obtained. The PdFeNi/ChRTIL nanocomposite showed excellent compatibility, enhanced electron transfer kinetics, large electroactive surface area, and was highly sensitive, selective, and stable toward BTN determination. Finally, the PdFeNi/ChRTIL/GCE was satisfactorily applied to the determination of BTN in infant milk powder, liver, and egg yolk samples. PMID:25281100

  15. New insight of coordination and extraction of uranium(VI) with N-donating ligands in room temperature ionic liquids: N,N'-diethyl-N,N'-ditolyldipicolinamide as a case study.

    PubMed

    Yuan, Li-Yong; Sun, Man; Mei, Lei; Wang, Lin; Zheng, Li-Rong; Gao, Zeng-Qiang; Zhang, Jing; Zhao, Yu-Liang; Chai, Zhi-Fang; Shi, Wei-Qun

    2015-02-16

    Room temperature ionic liquids (RTILs) represent a recent new class of solvents applied in liquid/liquid extraction based nuclear fuel reprocessing, whereas the related coordination chemistry and detailed extraction processes are still not well understood and remain of deep fundamental interest. The work herein provides a new insight of coordination and extraction of uranium(VI) with N-donating ligands, e.g., N,N'-diethyl-N,N'-ditolyldipicolinamide (EtpTDPA), in commonly used RTILs. Exploration of the extraction mechanism, speciation analyses of the extracted U(VI), and crystallographic studies of the interactions of EtpTDPA with U(VI) were performed, including the first structurally characterized UO2(EtpTDPA)2(NTf2) and UO2(EtpTDPA)2(PF6)2 compounds and a first case of crystallographic differentiation between the extracted U(VI) complexes in RTILs and in molecular solvents. It was found that in RTILs two EtpTDPA molecules coordinate with one U(VI) ion through the carbonyl and pyridine nitrogen moieties, while NTf2(-) and PF6(-) act as counterions. The absence of NO3(-) in the complexes is coincident with a cation-exchange extraction. In contrast, both the extracted species and extraction mechanisms are greatly different in dichloromethane, in which UO2(2+) coordinates in a neutral complex form with one EtpTDPA molecule and two NO3(-) cations. In addition, the complex formation in RTILs is independent of the cation exchange since incorporating UO2(NO3)2, EtpTDPA, and LiNTf2 or KPF6 in a solution also produces the same complex as that in RTILs, revealing the important roles of weakly coordinating anions on the coordination chemistry between U(VI) and EtpTDPA. These findings suggest that cation-exchange extraction mode for ILs-based extraction system probably originates from the supply of weakly coordinating anions from RTILs. Thus the coordination of uranium(VI) with extractants as well as the cation-exchange extraction mode may be potentially changed by varying the counterions of uranyl or introducing extra anions. PMID:25629464

  16. Stretchable microelectrode array using room-temperature liquid alloy interconnects

    NASA Astrophysics Data System (ADS)

    Wei, P.; Taylor, R.; Ding, Z.; Chung, C.; Abilez, O. J.; Higgs, G.; Pruitt, B. L.; Ziaie, B.

    2011-05-01

    In this paper, we present a stretchable microelectrode array for studying cell behavior under mechanical strain. The electrode array consists of gold-plated nail-head pins (250 µm tip diameter) or tungsten micro-wires (25.4 µm in diameter) inserted into a polydimethylsiloxane (PDMS) platform (25.4 × 25.4 mm2). Stretchable interconnects to the outside were provided by fusible indium-alloy-filled microchannels. The alloy is liquid at room temperature, thus providing the necessary stretchability and electrical conductivity. The electrode platform can withstand strains of up to 40% and repeated (100 times) strains of up to 35% did not cause any failure in the electrodes or the PDMS substrate. We confirmed biocompatibility of short-term culture, and using the gold pin device, we demonstrated electric field pacing of adult murine heart cells. Further, using the tungsten microelectrode device, we successfully measured depolarizations of differentiated murine heart cells from embryoid body clusters.

  17. Ionic liquid pillar[5]arene: its ionic conductivity and solvent-free complexation with a guest.

    PubMed

    Ogoshi, Tomoki; Ueshima, Naosuke; Yamagishi, Tada-aki; Toyota, Yoshiyuki; Matsumi, Noriyoshi

    2012-04-11

    A room-temperature ionic liquid containing macrocyclic compound pillar[5]arene in its core was synthesized. The ionic liquid showed high thermal stability, moderate ionic conductivity and solvent-free complexation ability with the guest tetracyanoethylene. PMID:22377801

  18. Crystal structures of frozen room temperature ionic liquids, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF 4), hexafluoroniobate (EMImNbF 6) and hexafluorotantalate (EMImTaF 6), determined by low-temperature X-ray diffraction

    NASA Astrophysics Data System (ADS)

    Matsumoto, Kazuhiko; Hagiwara, Rika; Mazej, Zoran; Benki?, Primo; emva, Boris

    2006-10-01

    The crystal structures of three salts, 1-ethyl-3-methylimidazolium tetrafluoroborate (EMImBF 4), hexafluoroniobate (EMImNbF 6) and hexafluorotantalate (EMImTaF 6), all of which form room-temperature ionic liquids (RTILs), have been determined by low-temperature X-ray diffraction studies of their single crystals. EMImBF 4 crystallizes in the monoclinic space group P2/c with a=8.653(5) , b=9.285(18) , c=13.217(7) , ?=121.358(15) , V=906.8(19) , Z=4 at 100 K. EMImBF 4 exhibits a unique structure wherein EMIm cations form one-dimensional pillars facing the imidazolium ring to the next ring linked by H(methylene)⋯ ? electron interaction. The BF 4 anion also forms one-dimensional pillars along the same direction with the nearest F⋯F contact distance of 3.368(3) . EMImNbF 6 and EMImTaF 6 are isostructural to each other and crystallize in the orthorhombic space group P222: EMImNbF 6, a=9.204(4) , b=9.770(15) , c=12.499(13) , V=1124(2) , Z=4 at 200 K; EMImTaF 6, a=9.216(5) , b=9.763(2) , c=12.502(17) , V=1124.9(17) , Z=4 at 200 K. In EMImNbF 6 and EMImTaF 6, EMIm cations also form a one-dimensional pillar structure and the hexafluorocomplex anions are located in a zig-zag arrangement along the same direction with the nearest F⋯F distance of 3.441(12) . This structure (Type-B(MF 6)) is different from the Type-A(MF 6) structure previously reported for EMImPF 6, EMImAsF 6 and EMImSbF 6. Hydrogen bonds in the Type-A(MF 6) (EMImPF 6 (333 K), EMImAsF 6 (326 K) and EMImSbF 6 (283 K)) crystal lattice are weaker than those in the Type-B(MF 6) (EMImNbF 6 (272 K) and EMImTaF 6 (275 K)) crystal lattice. This suggests that the strength of the hydrogen bond is not always a decisive and determining factor for the melting points of RTILs. The measurement of cell parameters for EMImBF 4 between 100 K and its melting point revealed that EMImBF 4 essentially preserves the same structure in this temperature range and increases its volume by only 4% due to the melting.

  19. [Electrochemical sensors based on carbon nanotubes and their use in biomedical research. Part 2: Sensors manufactured by dispersion of carbon nanotubes by means of polyethyleneimine, organic dyes, cyclodextrins, chitosan, proteins, room-temperature ionic liquids, gels, and thiols. Sensors manufactured by dispersion of carbon nanotubes by electropolymerization process. sensors manufactured by dispersion of carbon nanotubes by layer-by-layer deposition].

    PubMed

    Buzanovski?, V A

    2012-01-01

    Electrochemical sensors based on carbon nanotubes are widely distributed in biomedical researches. One group of these sensors contains the sensors manufactured by dispersion of carbon nanotubes on an electrode surface by means of polyethyleneimine, organic dyes, cyclodextrins, chitosan, proteins, room-temperature ionic liquids, gels, thiols, by electropolymerization process, and by layer-by-layer deposition. The development directions of such sensors are analyzed. The general information on manufacturing techniques of these sensors is submitted. The opportunities of these sensors for carrying out biomedical researches are demonstrated. PMID:22724355

  20. 3-Methylpiperidinium ionic liquids.

    PubMed

    Belhocine, Tayeb; Forsyth, Stewart A; Gunaratne, H Q Nimal; Nieuwenhuyzen, Mark; Nockemann, Peter; Puga, Alberto V; Seddon, Kenneth R; Srinivasan, Geetha; Whiston, Keith

    2015-04-28

    A wide range of room temperature ionic liquids based on the 3-methylpiperdinium cation core were produced from 3-methylpiperidine, which is a derivative of DYTEK A amine. First, reaction with 1-bromoalkanes or 1-bromoalkoxyalkanes generated the corresponding tertiary amines (Rm?pip, R = alkyl or alkoxyalkyl); further quaternisation reactions with the appropriate methylating agents yielded the quaternary [Rmm?pip]X salts (X(-) = I(-), [CF3CO2](-) or [OTf](-); Tf = -SO2CF3), and [Rmm?pip][NTf2] were prepared by anion metathesis from the corresponding iodides. All [NTf2](-) salts are liquids at room temperature. [Rmm?pip]X (X(-) = I(-), [CF3CO2](-) or [OTf](-)) are low-melting solids when R = alkyl, but room temperature liquids upon introduction of ether functionalities on R. Neither of the 3-methylpiperdinium ionic liquids showed any signs of crystallisation, even well below 0 C. Some related non-C-substituted piperidinium and pyrrolidinium analogues were prepared and studied for comparison. Crystal structures of 1-hexyl-1,3-dimethylpiperidinium tetraphenylborate, 1-butyl-3-methylpiperidinium bromide, 1-(2-methoxyethyl)-1-methylpiperidinium chloride and 1-(2-methoxyethyl)-1-methylpyrrolidinium bromide are reported. Extensive structural and physical data are collected and compared to literature data, with special emphasis on the systematic study of the cation ring size and/or asymmetry effects on density, viscosity and ionic conductivity, allowing general trends to be outlined. Cyclic voltammetry shows that 3-methylpiperidinium ionic liquids, similarly to azepanium, piperidinium or pyrrolidinium counterparts, are extremely electrochemically stable; the portfolio of useful alternatives for safe and high-performing electrolytes is thus greatly extended. PMID:25669485

  1. Phosphonium-based ionic liquids and uses

    DOEpatents

    Del Sesto, Rico E; Koppisch, Andrew T; Lovejoy, Katherine S; Purdy, Geraldine M

    2014-12-30

    Phosphonium-based room temperature ionic liquids ("RTILs") were prepared. They were used as matrices for Matrix-Assisted Laser Desorption Ionization (MALDI) mass spectrometry and also for preparing samples of dyes for analysis.

  2. New electrolytes for aluminum production: Ionic liquids

    NASA Astrophysics Data System (ADS)

    Zhang, Mingming; Kamavarum, Venkat; Reddy, Ramana G.

    2003-11-01

    In this article, the reduction, refining/recycling, and electroplating of aluminum from room-temperature molten salts are reviewed. In addition, the characteristics of several non-conventional organic solvents, electrolytes, and molten salts are evaluated, and the applicability of these melts for production of aluminum is discussed with special attention to ionic liquids. Also reviewed are electrochemical processes and conditions for electrodeposition of aluminum using ionic liquids at near room temperatures.

  3. Electrowetting of ionic liquids.

    PubMed

    Millefiorini, Stefano; Tkaczyk, Alan H; Sedev, Rossen; Efthimiadis, Jim; Ralston, John

    2006-03-01

    We have successfully demonstrated that imidazolium- and pyrrolidinium-based commercial room-temperature ionic liquids can electrowet (with a dc voltage) a smooth fluoropolymer (Teflon AF1600) surface. Qualitatively, the process is analogous to the electrowetting of aqueous electrolyte solutions: the contact angle versus voltage curve has a parabolic shape which saturates at larger voltages (positive or negative). On the other hand we observed several peculiarities: (i) the efficiency is significantly lower (by about an order of magnitude); (ii) the influence of the bulky cation is larger and the importance of the smaller anion is lesser, especially with respect to electrowetting saturation; (iii) there is an asymmetry in the saturation contact angles found for positive and negative voltages. The asymmetry may be correlated with the cation-anion asymmetry of the ionic liquids. The low efficiency may be caused by the presence of water and other impurities in these commercial materials. PMID:16506791

  4. Ionic liquids as novel solvents for ionic polymer transducers

    NASA Astrophysics Data System (ADS)

    Bennett, Matthew D.; Leo, Donald J.

    2004-07-01

    The use of ionic liquids as solvents for ionic polymer (specifically, Nafion) transducers is demonstrated. Ionic liquids are attractive for this application because of their high inherent stability. Ionic liquids are salts that exist as liquids at room temperature and have no measureable vapor pressure. Therefore, the use of ionic liquids as solvents for ionic polymer transducers can eliminate the traditional problem of water evaporation in these devices. Another benefit of the use of ionic liquids in this way is the reduction or elimination of the characteristic back-relaxation common in water-solvated ionic polymer actuators. The results demonstrate that the viscosity of the ionic liquid and the degree to which the ionic liquid swells the membrane are the important physical parameters to consider. Five ionic liquids were studied, based on substituted pyrrolidinium, phosphonium, or imidazolium cations and fluoroanions. Of these five ionic liquids, transduction is demonstrated in three of them and the best results are obtained with 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ionic liquid. This substance has an electrochemical stability window of 4.1 V, a melting point of -10 C, and a viscosity of 35-45 cP [19]. Results demonstrate that platinum-plated Nafion transducers solvated with this ionic liquid exhibit sensing and actuation responses and that these transducers are stable in air. Endurance testing of this sample reveals a decrease in the free strain of only 25 % after 250,000 actuation cycles in air.

  5. ELECTROCHEMICAL STUDIES OF HEMIN IN IONIC LIQUIDS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Ionic liquids (ILs), room temperature liquid organic salts, have gained prominence as alternative media for volatile organic solvents. Recent studies have shown that some enzymes tolerate ILs and have catalytic activities comparable to those obtained in molecular organic solvents. We have investig...

  6. Ionic Liquids Database- (ILThermo)

    National Institute of Standards and Technology Data Gateway

    SRD 147 Ionic Liquids Database- (ILThermo) (Web, free access)   IUPAC Ionic Liquids Database, ILThermo, is a free web research tool that allows users worldwide to access an up-to-date data collection from the publications on experimental investigations of thermodynamic, and transport properties of ionic liquids as well as binary and ternary mixtures containing ionic liquids.

  7. Catalytic Alkene Metathesis in Ionic Liquids

    NASA Astrophysics Data System (ADS)

    Fischmeister, Cdric

    Olefin metathesis has found a tremendous number of application in the past 25 years. Immobilisation of olefin metathesis (pre)catalysts in room temperature ionic liquids (RTILs) offers the opportunity to recover and reuse the catalyst and also to reduce the level of ruthenium (Ru) contaminants in the products.

  8. Room Temperature Bubble Point Tests on Porous Screens: Implications for Cryogenic Liquid Acquisition Devices

    NASA Technical Reports Server (NTRS)

    Hartwig, Jason; Mann, J. Adin, Jr.

    2012-01-01

    We present experimental results for room temperature bubble point tests conducted at the Cedar Creek Road Cryogenic Complex, Cell 7 (CCL-7) at the NASA Glenn Research Center. The purpose of these tests was to investigate the performance of three different fine mesh screens in room temperature liquids to provide pretest predictions in cryogenic liquid nitrogen (LN2) and hydrogen (LH2) as part of NASA's microgravity LAD technology development program. Bench type tests based on the maximum bubble point method were conducted for a 325 x 2300, 450 x 2750, and 510 x 3600 mesh sample in pure room temperature liquid methanol, acetone, isopropyl alcohol, water, and mixtures of methanol and water to cover the intermediate to upper surface tension range. A theoretical model for the bubble point pressure is derived from the Young-LaPlace equation for the pressure drop across a curved interface. Governing equations are reduced in complexity through a set of simplifying assumptions to permit direct comparison with the experimental data. Screen pore sizes are estimated from scanning electron microscopy (SEM) to make pretest predictions. Pore sizes based on SEM analysis are compared with historical data available in the literature for the 325 x 2300 and 450 x 2750 screens as well with data obtained from bubble point tests conducted in this work. Experimental results show that bubble point pressure is proportional to the surface tension of the liquid. We show that there is excellent agreement between data and model for pure fluids when the data is corrected for non-zero contact angle measured on the screens using a modified Sessile Drop technique. SEM image analysis of the three meshes indicated that bubble point pressure would be a maximum for the finest mesh screen. The pore diameters based on SEM analysis and experimental data obtained here are in excellent agreement for the 325 x 2300 and 450 x 2750 meshes, but not for the finest 510 x 3600 mesh. Therefore the simplified model can be used to interpolate predictions for low surface tension cryogenic liquids only when pore diameters are based on room temperature bubble point tests and not SEM analysis as presently implemented.

  9. Ionic Liquids to Replace Hydrazine

    NASA Technical Reports Server (NTRS)

    Koelfgen, Syri; Sims, Joe; Forton, Melissa; Allan, Barry; Rogers, Robin; Shamshina, Julia

    2011-01-01

    A method for developing safe, easy-to-handle propellants has been developed based upon ionic liquids (ILs) or their eutectic mixtures. An IL is a binary combination of a typically organic cation and anion, which generally produces an ionic salt with a melting point below 100 deg C. Many ILs have melting points near, or even below, room temperature (room temperature ionic liquids, RTILs). More importantly, a number of ILs have a positive enthalpy of formation. This means the thermal energy released during decomposition reactions makes energetic ILs ideal for use as propellants. In this specific work, to date, a baseline set of energetic ILs has been identified, synthesized, and characterized. Many of the ILs in this set have excellent performance potential in their own right. In all, ten ILs were characterized for their enthalpy of formation, density, melting point, glass transition point (if applicable), and decomposition temperature. Enthalpy of formation was measured using a microcalorimeter designed specifically to test milligram amounts of energetic materials. Of the ten ILs characterized, five offer higher Isp performance than hydrazine, ranging between 10 and 113 seconds higher than the state-of-the-art propellant. To achieve this level of performance, the energetic cations 4- amino-l,2,4-triazolium and 3-amino-1,2,4-triazolium were paired with various anions in the nitrate, dicyanamide, chloride, and 3-nitro-l,2,4-triazole families. Protonation, alkylation, and butylation synthesis routes were used for creation of the different salts.

  10. Measurement of the Order Parameter in a Room Temperature Liquid Crystal: An Experiment for the Physical Chemistry Laboratory.

    ERIC Educational Resources Information Center

    DuPre, Donald B.; Chapoy, L. Lawrence

    1979-01-01

    Presented here is a laboratory experiment for a course in physical chemistry. Students are requested to directly measure the degree of orientational order in a liquid crystal at room temperature. A minimum amount of equipment is necessary. (Author/SA)

  11. A room-temperature sodium rechargeable battery using an SO2-based nonflammable inorganic liquid catholyte

    NASA Astrophysics Data System (ADS)

    Jeong, Goojin; Kim, Hansu; Sug Lee, Hyo; Han, Young-Kyu; Hwan Park, Jong; Hwan Jeon, Jae; Song, Juhye; Lee, Keonjoon; Yim, Taeeun; Jae Kim, Ki; Lee, Hyukjae; Kim, Young-Jun; Sohn, Hun-Joon

    2015-08-01

    Sodium rechargeable batteries can be excellent alternatives to replace lithium rechargeable ones because of the high abundance and low cost of sodium; however, there is a need to further improve the battery performance, cost-effectiveness, and safety for practical use. Here we demonstrate a new type of room-temperature and high-energy density sodium rechargeable battery using an SO2-based inorganic molten complex catholyte, which showed a discharge capacity of 153?mAh g-1 based on the mass of catholyte and carbon electrode with an operating voltage of 3?V, good rate capability and excellent cycle performance over 300 cycles. In particular, non-flammability and intrinsic self-regeneration mechanism of the inorganic liquid electrolyte presented here can accelerate the realization of commercialized Na rechargeable battery system with outstanding reliability. Given that high performance and unique properties of Na-SO2 rechargeable battery, it can be another promising candidate for next generation energy storage system.

  12. Use of ionic liquids as coordination ligands for organometallic catalysts

    SciTech Connect

    Li, Zaiwei; Tang, Yongchun; Cheng; Jihong

    2009-11-10

    Aspects of the present invention relate to compositions and methods for the use of ionic liquids with dissolved metal compounds as catalysts for a variety of chemical reactions. Ionic liquids are salts that generally are liquids at room temperature, and are capable of dissolving a many types of compounds that are relatively insoluble in aqueous or organic solvent systems. Specifically, ionic liquids may dissolve metal compounds to produce homogeneous and heterogeneous organometallic catalysts. One industrially-important chemical reaction that may be catalyzed by metal-containing ionic liquid catalysts is the conversion of methane to methanol.

  13. Supramolecular Ionic-Liquid Gels with High Ionic Conductivity.

    PubMed

    Maravelski, Aleksandra; Smre?ki, Vilko; Vianello, Robert; ini?, Mladen; Mogu-Milankovi?, Andrea; anti?, Ana

    2015-08-17

    Supramolecular ionogels were prepared by the gelation of room-temperature ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIm][BF4 ]) with (S,S)-bis(leucinol)oxalamide. Remarkably, the ionic conductivity of solutions and ionogels with low gelator concentrations is higher than that of neat [BMIm][BF4 ]. On the basis of molecular dynamics simulations and quantum mechanical calculations, the origin of this phenomenon is attributed to the higher affinity of gelator molecules towards [BF4 ](-) ions, which reduces the electrostatic attraction between [BMIm](+) and [BF4 ](-) and thus increases their mobility. With increasing gelator concentration, the ionic conductivity decreases due to the formation of a denser gelator matrix, which hinders the pathways for ionic transport. However, even for very dense ionogels, this decrease is less than one order of magnitude relative to neat [BMIm][BF4 ], and thus they can be classified as highly conductive materials with strong potential for application as functional electrolytes. PMID:26178864

  14. Direct Writing of Flexible Electronics through Room Temperature Liquid Metal Ink

    PubMed Central

    Gao, Yunxia; Li, Haiyan; Liu, Jing

    2012-01-01

    Background Conventional approaches of making a flexible circuit are generally complex, environment unfriendly, time and energy consuming, and thus expensive. Here, we describe for the first time the method of using high-performance GaIn10-based electrical ink, a significantly neglected room temperature liquid metal, as both electrical conductors and interconnects, for directly writing flexible electronics via a rather easy going and cost effective way. Methods The new generation electric ink was made and its wettability with various materials was modified to be easily written on a group of either soft or rigid substrates such as epoxy resin board, glass, plastic, silica gel, paper, cotton, textiles, cloth and fiber etc. Conceptual experiments were performed to demonstrate and evaluate the capability of directly writing the electrical circuits via the invented metal ink. Mechanisms involved were interpreted through a series of fundamental measurements. Results The electrical resistivity of the fluid like GaIn10-based material was measured as 34.5 ?cm at 297 K by four point probe method and increased with addition of the oxygen quantity, which indicates it as an excellent metal ink. The conductive line can be written with features that are approximately 10 m thick. Several functional devices such as a light emitting diode (LED) array showing designed lighting patterns and electrical fan were made to work by directly writing the liquid metal on the specific flexible substrates. And satisfactory performances were obtained. Conclusions The present method opens the way to directly and quickly writing flexible electronics which can be as simple as signing a name or drawing a picture on the paper. The unique merit of the GaIn10-based liquid metal ink lies in its low melting temperature, well controlled wettability, high electrical conductivity and good biocompability. The new electronics writing strategy and basic principle has generalized purpose and can be extended to more industrial areas, even daily life. PMID:23029044

  15. A room-temperature sodium rechargeable battery using an SO2-based nonflammable inorganic liquid catholyte.

    PubMed

    Jeong, Goojin; Kim, Hansu; Lee, Hyo Sug; Han, Young-Kyu; Park, Jong Hwan; Jeon, Jae Hwan; Song, Juhye; Lee, Keonjoon; Yim, Taeeun; Kim, Ki Jae; Lee, Hyukjae; Kim, Young-Jun; Sohn, Hun-Joon

    2015-01-01

    Sodium rechargeable batteries can be excellent alternatives to replace lithium rechargeable ones because of the high abundance and low cost of sodium; however, there is a need to further improve the battery performance, cost-effectiveness, and safety for practical use. Here we demonstrate a new type of room-temperature and high-energy density sodium rechargeable battery using an SO2-based inorganic molten complex catholyte, which showed a discharge capacity of 153 mAh g(-1) based on the mass of catholyte and carbon electrode with an operating voltage of 3 V, good rate capability and excellent cycle performance over 300 cycles. In particular, non-flammability and intrinsic self-regeneration mechanism of the inorganic liquid electrolyte presented here can accelerate the realization of commercialized Na rechargeable battery system with outstanding reliability. Given that high performance and unique properties of Na-SO2 rechargeable battery, it can be another promising candidate for next generation energy storage system. PMID:26243052

  16. Room temperature ferromagnetism in liquid-phase pulsed laser ablation synthesized nanoparticles of nonmagnetic oxides

    NASA Astrophysics Data System (ADS)

    Singh, S. C.; Kotnala, R. K.; Gopal, R.

    2015-08-01

    Intrinsic Room Temperature Ferromagnetism (RTF) has been observed in undoped/uncapped zinc oxide and titanium dioxide spherical nanoparticles (NPs) obtained by a purely green approach of liquid phase pulsed laser ablation of corresponding metal targets in pure water. Saturation magnetization values observed for zinc oxide (average size, 9 1.2 nm) and titanium dioxide (average size, 4.4 0.3 nm) NPs are 62.37 and 42.17 memu/g, respectively, which are several orders of magnitude larger than those of previous reports. In contrast to the previous works, no postprocessing treatments or surface modification is required to induce ferromagnetism in the case of present communication. The most important result, related to the field of intrinsic ferromagnetism in nonmagnetic materials, is the observation of size dependent ferromagnetism. Degree of ferromagnetism in titanium dioxide increases with the increase in particle size, while it is reverse for zinc oxide. Surface and volume defects play significant roles for the origin of RTF in zinc oxide and titanium dioxide NPs, respectively. Single ionized oxygen and neutral zinc vacancies in zinc oxide and oxygen and neutral/ionized titanium vacancies in titanium dioxide are considered as predominant defect centres responsible for observed ferromagnetism. It is expected that origin of ferromagnetism is a consequence of exchange interactions between localized electron spin moments resulting from point defects.

  17. A room-temperature sodium rechargeable battery using an SO2-based nonflammable inorganic liquid catholyte

    PubMed Central

    Jeong, Goojin; Kim, Hansu; Sug Lee, Hyo; Han, Young-Kyu; Hwan Park, Jong; Hwan Jeon, Jae; Song, Juhye; Lee, Keonjoon; Yim, Taeeun; Jae Kim, Ki; Lee, Hyukjae; Kim, Young-Jun; Sohn, Hun-Joon

    2015-01-01

    Sodium rechargeable batteries can be excellent alternatives to replace lithium rechargeable ones because of the high abundance and low cost of sodium; however, there is a need to further improve the battery performance, cost-effectiveness, and safety for practical use. Here we demonstrate a new type of room-temperature and high-energy density sodium rechargeable battery using an SO2-based inorganic molten complex catholyte, which showed a discharge capacity of 153 mAh g−1 based on the mass of catholyte and carbon electrode with an operating voltage of 3 V, good rate capability and excellent cycle performance over 300 cycles. In particular, non-flammability and intrinsic self-regeneration mechanism of the inorganic liquid electrolyte presented here can accelerate the realization of commercialized Na rechargeable battery system with outstanding reliability. Given that high performance and unique properties of Na–SO2 rechargeable battery, it can be another promising candidate for next generation energy storage system. PMID:26243052

  18. Formulation of a room temperature ferroelectric liquid crystal mixture with sub-millisecond switching time

    NASA Astrophysics Data System (ADS)

    Debnath, A.; Sinha, D.; Mandal, P. K.; Dabrowski, R.

    2015-06-01

    Ferroelectric liquid crystal (FLC) based display devices show faster response compared to nematic LC based devices. Since pure FLC compounds are high temperature LCs and do not possess optimum parameters necessary for display devices, a room temperature FLC mixture has been formulated, first time by any Indian group. The mixture is prepared by doping an appropriate chiral compound in a four-component LC based achiral host mixture. Resulting mixture was characterized using optical polarizing microscopy, frequency domain dielectric spectroscopy and electro-optic methods. It shows very wide range ferroelectric SmC* phase followed by paraelectric SmA* phase (Cr< 19CSmC*89C SmA* 108C I) which would facilitate attaining book shelf geometry alignment in display devices. Dielectric spectroscopy study reveals Goldstone (in kHz region) and soft mode (in hundred kHz region) relaxations in SmC* and SmA* phases respectively. The mixture possesses moderate tilt angle (34.5 - 13), low viscosity (0.9 - 0.05 N.s.m-2) and moderately high spontaneous polarization (112 - 36 nC.cm-2) which decrease with temperature. These result in very fast switching, slowest response time being 475 s at ambient temperature.

  19. A novel method for hydrogen production from liquid ethanol/water at room temperature.

    PubMed

    Sekine, Yasushi; Urasaki, Kohei; Asai, Shinjiro; Matsukata, Masahiko; Kikuchi, Eiichi; Kado, Shigeru

    2005-01-01

    We demonstrated that non-catalytic ethanol steam reforming proceeds efficiently and selectively without coking at the conditions of room temperature and atmospheric pressure using low-energy pulsed (LEP) discharge in combination with carbon fiber electrodes. PMID:15614378

  20. A room-temperature processed parylene-patterned helical ionic polymer-metal composite spring actuator with selectable active region

    NASA Astrophysics Data System (ADS)

    Feng, Guo-Hua; Zhan, Zhen-Hua

    2014-04-01

    This paper presents a novel helical ionic polymer metal composite (IPMC) spring actuator. A room-temperature fabrication process is developed to selectively grow in situ nickel metal electrode on a coiled Nafion strip, which is patterned with parylene as a masking layer to delineate the inactive region. This method allows the helical spring actuator to be shaped in a near-constant temperature environment and minimizes the residual stress effect on the Nafion polymer, compared to other processes using thermal treatment. The developed process ensures that short-circuiting never occurs between the outer and inner electrodes of the actuator, and the active region can be designed via parylene patterning. The motion of the fabricated spring actuator is measured, and the maximal displacement reaches 1 mm at the endpoint of the spring under a 0.1 Hz 6 V square wave actuation. A microtensile experiment is performed for characterizing the stress and strain relation. The resulting Youngs moduli of the Nafion and fabricated IPMC strips are 183 and 227 MPa, respectively. Analysis based on Castiglianos theorem is executed to derive equations related to the moment, force output, strain energy, and displacement of an arbitrary point of the fabricated spring actuator. Results show the produced moment, force, and strain energy of the operated spring actuator are in the level of 1.5 ?N m, 300 mN, and 20-100 ?J, respectively.

  1. FINAL REPORT: Room Temperature Hydrogen Storage in Nano-Confined Liquids

    SciTech Connect

    VAJO, JOHN

    2014-06-12

    DOE continues to seek solid-state hydrogen storage materials with hydrogen densities of ≥6 wt% and ≥50 g/L that can deliver hydrogen and be recharged at room temperature and moderate pressures enabling widespread use in transportation applications. Meanwhile, development including vehicle engineering and delivery infrastructure continues for compressed-gas hydrogen storage systems. Although compressed gas storage avoids the materials-based issues associated with solid-state storage, achieving acceptable volumetric densities has been a persistent challenge. This project examined the possibility of developing storage materials that would be compatible with compressed gas storage technology based on enhanced hydrogen solubility in nano-confined liquid solvents. These materials would store hydrogen in molecular form eliminating many limitations of current solid-state materials while increasing the volumetric capacity of compressed hydrogen storage vessels. Experimental methods were developed to study hydrogen solubility in nano-confined liquids. These methods included 1) fabrication of composites comprised of volatile liquid solvents for hydrogen confined within the nano-sized pore volume of nanoporous scaffolds and 2) measuring the hydrogen uptake capacity of these composites without altering the composite composition. The hydrogen storage capacities of these nano-confined solvent/scaffold composites were compared with bulk solvents and with empty scaffolds. The solvents and scaffolds were varied to optimize the enhancement in hydrogen solubility that accompanies confinement of the solvent. In addition, computational simulations were performed to study the molecular-scale structure of liquid solvent when confined within an atomically realistic nano-sized pore of a model scaffold. Confined solvent was compared with similar simulations of bulk solvent. The results from the simulations were used to formulate a mechanism for the enhanced solubility and to guide the experiments. Overall, the combined experimental measurements and simulations indicate that hydrogen storage based on enhanced solubility in nano-confined liquids is unlikely to meet the storage densities required for practical use. Only low gravimetric capacities of < 0.5 wt% were achieved. More importantly, solvent filled scaffolds had lower volumetric capacities than corresponding empty scaffolds. Nevertheless, several of the composites measured did show significant (>~ 5x) enhanced hydrogen solubility relative to bulk solvent solubility, when the hydrogen capacity was attributed only to dissolution in the confined solvent. However, when the hydrogen capacity was compared to an empty scaffold that is known to store hydrogen by surface adsorption on the scaffold walls, including the solvent always reduced the hydrogen capacity. For the best composites, this reduction relative to an empty scaffold was ~30%; for the worst it was ~90%. The highest capacities were obtained with the largest solvent molecules and with scaffolds containing 3- dimensionally confined pore geometries. The simulations suggested that the capacity of the composites originated from hydrogen adsorption on the scaffold pore walls at sites not occupied by solvent molecules. Although liquid solvent filled the pores, not all of the adsorption sites on the pore walls were occupied due to restricted motion of the solvent molecules within the confined pore space.

  2. Gallium-Based Room Temperature Liquid Metals and its Application to Single Channel Two-Liquid Hyperelastic Capacitive Strain Sensors

    NASA Astrophysics Data System (ADS)

    Liu, Shanliangzi

    Gallium-based liquid metals are of interest for a variety of applications including flexible electronics, soft robotics, and biomedical devices. Still, nano- to microscale device fabrication with these materials is challenging because of their strong adhesion to a majority of substrates. This unusual high adhesion is attributed to the formation of a thin oxide shell; however, its role in the adhesion process has not yet been established. In the first part of the thesis, we described a multiscale study aiming at understanding the fundamental mechanisms governing wetting and adhesion of gallium-based liquid metals. In particular, macroscale dynamic contact angle measurements were coupled with Scanning Electron Microscope (SEM) imaging to relate macroscopic drop adhesion to morphology of the liquid metal-surface interface. In addition, room temperature liquid-metal microfluidic devices are also attractive systems for hyperelastic strain sensing. Currently two types of liquid metal-based strain sensors exist for inplane measurements: single-microchannel resistive and two-microchannel capacitive devices. However, with a winding serpentine channel geometry, these sensors typically have a footprint of about a square centimeter, limiting the number of sensors that can be embedded into. In the second part of the thesis, firstly, simulations and an experimental setup consisting of two GaInSn filled tubes submerged within a dielectric liquid bath are used to quantify the effects of the cylindrical electrode geometry including diameter, spacing, and meniscus shape as well as dielectric constant of the insulating liquid and the presence of tubing on the overall system's capacitance. Furthermore, a procedure for fabricating the two-liquid capacitor within a single straight polydiemethylsiloxane channel is developed. Lastly, capacitance and response of this compact device to strain and operational issues arising from complex hydrodynamics near liquid-liquid and liquid-elastomer interfaces are described.

  3. Applications of ionic liquids.

    PubMed

    Patel, Divia Dinesh; Lee, Jong-Min

    2012-06-01

    Ionic liquids have recently gained popularity in the scientific community owing to their special properties and characteristics. One of the reasons why ionic liquids have been termed "green solvents" is due to their negligible vapour pressure. Their use in electrochemical, biological and metal extraction applications is discussed. Wide research has been carried out for their use in batteries, solar panels, fuel cells, drug deliveries and biomass pretreatments. This work aims to consolidate the various findings from previous works in these areas. PMID:22711528

  4. Water Contaminant Mitigation in Ionic Liquid Propellant

    NASA Technical Reports Server (NTRS)

    Conroy, David; Ziemer, John

    2009-01-01

    Appropriate system and operational requirements are needed in order to ensure mission success without unnecessary cost. Purity requirements applied to thruster propellants may flow down to materials and operations as well as the propellant preparation itself. Colloid electrospray thrusters function by applying a large potential to a room temperature liquid propellant (such as an ionic liquid), inducing formation of a Taylor cone. Ions and droplets are ejected from the Taylor cone and accelerated through a strong electric field. Electrospray thrusters are highly efficient, precise, scaleable, and demonstrate low thrust noise. Ionic liquid propellants have excellent properties for use as electrospray propellants, but can be hampered by impurities, owing to their solvent capabilities. Of foremost concern is the water content, which can result from exposure to atmosphere. Even hydrophobic ionic liquids have been shown to absorb water from the air. In order to mitigate the risks of bubble formation in feed systems caused by water content of the ionic liquid propellant, physical properties of the ionic liquid EMI-Im are analyzed. The effects of surface tension, material wetting, physisorption, and geometric details of the flow manifold and electrospray emitters are explored. Results are compared to laboratory test data.

  5. Phase-Changing Ionic Liquids: CO2 Capture with Ionic Liquids Involving Phase Change

    SciTech Connect

    2010-07-01

    IMPACCT Project: Notre Dame is developing a new CO2 capture process that uses special ionic liquids (ILs) to remove CO2 from the gas exhaust of coal-fired power plants. ILs are salts that are normally liquid at room temperature, but Notre Dame has discovered a new class of ILs that are solid at room temperature and change to liquid when they bind to CO2. Upon heating, the CO2 is released for storage, and the ILs re-solidify and donate some of the heat generated in the process to facilitate further CO2 release. These new ILs can reduce the energy required to capture CO2 from the exhaust stream of a coal-fired power plant when compared to state-ofthe- art technology.

  6. VOC and HAP recovery using ionic liquids

    SciTech Connect

    Michael R. Milota : Kaichang Li

    2007-05-29

    During the manufacture of wood composites, paper, and to a lesser extent, lumber, large amounts of volatile organic compounds (VOCs) such as terpenes, formaldehyde, and methanol are emitted to air. Some of these compounds are hazardous air pollutants (HAPs). The air pollutants produced in the forest products industry are difficult to manage because the concentrations are very low. Presently, regenerative thermal oxidizers (RTOs and RCOs) are commonly used for the destruction of VOCs and HAPs. RTOs consume large amounts of natural gas to heat air and moisture. The combustion of natural gas generates increased CO2 and NOx, which have negative implications for global warming and air quality. The aforementioned problems are addressed by an absorption system containing a room-temperature ionic liquid (RTIL) as an absorbent. RTILs are salts, but are in liquid states at room temperature. RTILs, an emerging technology, are receiving much attention as replacements for organic solvents in industrial processes with significant cost and environmental benefits. Some of these processes include organic synthesis, extraction, and metal deposition. RTILs would be excellent absorbents for exhausts from wood products facilities because of their unique properties: no measurable vapor pressure, high solubility of wide range of organic compounds, thermal stability to 200°C (almost 400°F), and immisciblity with water. Room temperature ionic liquids were tested as possible absorbents. Four were imidizolium-based and were eight phosphonium-based. The imidizolium-based ionic liquids proved to be unstable at the conditions tested and in the presence of water. The phosphonium-based ionic liquids were stable. Most were good absorbents; however, cleaning the contaminates from the ionic liquids was problematic. This was overcome with a higher temperature (120°C) than originally proposed and a very low pressure (1 kPa. Absorption trials were conducted with tetradecy(trihexyl)phosphonium dicyanamide as the RTIL. It was determined that it has good absorption properties for methanol and α-pinene, is thermally stable, and is relatively easy to synthesize. It has a density of 0.89 g/mL at 20°C and a molecular weight of 549.9 g/mol. Trials were conducted with a small absorption system and a larger absorption system. Methanol, formaldehyde, and other HAPs were absorbed well, nearly 100%. Acetaldehyde was difficult to capture. Total VOC capture, while satisfactory on methanol and α-pinene in a lab system, was less than expected in the field, 60-80%. The inability to capture the broad spectrum of total organics is likely due to difficulties in cleaning them from the ionic liquid rather than the ability of the ionic liquid to absorb. It’s likely that a commercial system could be constructed to remove 90 to 100% of the gas contaminates. Selecting the correct ionic liquid would be key to this. Absorption may not be the main selection criterion, but rather how easily the ionic liquid can be cleaned is very important. The ionic liquid absorption system might work very well in a system with a limited spectrum of pollutants, such as a paint spray line, where there are not very high molecular weight, non volatile, compounds in the exhaust.

  7. Ionic liquid ethanol sensor.

    PubMed

    Lee, Yuan Gee; Chou, Tse-Chuan

    2004-07-30

    Ionic liquids containing lithium methylsulfonyl group were prepared from the precursors poly(propylene glycol)-block-(ethylene glycol)-block-(propylene glycol)-bis(2-aminopropyl ether) with different molecular weight. These liquids revealed excellent electrical conductivity in the temperature range -25 to 85 degrees C. Also, they exhibited a high boiling temperature and hence a low vapor pressure in ambient condition. Additionally, they showed a high fluidity with their viscosities being comparative with that of water. To determine the sensitivity of an ethanol sensor by using these ionic liquids, these liquids were subjected into a sequential electrochemical tests with nickel electrodes which performed a high sensitivity for the ethanol sensor. It was found that only the derivative with low molecular weight could detect ethanol. Furthermore, a linear relationship between the response current and the concentration of ethanol was constructed. The detection limit was found to be 0.13% (v/v) and its response time was 336 s. PMID:15142574

  8. Ionic liquids in chemical engineering.

    PubMed

    Werner, Sebastian; Haumann, Marco; Wasserscheid, Peter

    2010-01-01

    The development of engineering applications with ionic liquids stretches back to the mid-1990s when the first examples of continuous catalytic processes using ionic liquids and the first studies of ionic liquid-based extractions were published. Ever since, the use of ionic liquids has seen tremendous progress in many fields of chemistry and engineering, and the first commercial applications have been reported. The main driver for ionic liquid engineering applications is to make practical use of their unique property profiles, which are the result of a complex interplay of coulombic, hydrogen bonding and van der Waals interactions. Remarkably, many ionic liquid properties can be tuned in a wide range by structural modifications at their cation and anion. This review highlights specific examples of ionic liquid applications in catalysis and in separation technologies. Additionally, the application of ionic liquids as working fluids in process machines is introduced. PMID:22432579

  9. Importance of liquid fragility for energy applications of ionic liquids.

    PubMed

    Sippel, P; Lunkenheimer, P; Krohns, S; Thoms, E; Loidl, A

    2015-01-01

    Ionic liquids (ILs) are salts that are liquid close to room temperature. Their possible applications are numerous, e.g., as solvents for green chemistry, in various electrochemical devices, and even for such "exotic" purposes as spinning-liquid mirrors for lunar telescopes. Here we concentrate on their use for new advancements in energy-storage and -conversion devices: Batteries, supercapacitors or fuel cells using ILs as electrolytes could be important building blocks for the sustainable energy supply of tomorrow. Interestingly, ILs show glassy freezing and the universal, but until now only poorly understood dynamic properties of glassy matter, dominate many of their physical properties. We show that the conductivity of ILs, an essential figure of merit for any electrochemical application, depends in a systematic way not only on their glass temperature but also on the so-called fragility, characterizing the non-canonical super-Arrhenius temperature dependence of their ionic mobility. PMID:26355037

  10. Importance of liquid fragility for energy applications of ionic liquids

    NASA Astrophysics Data System (ADS)

    Sippel, P.; Lunkenheimer, P.; Krohns, S.; Thoms, E.; Loidl, A.

    2015-09-01

    Ionic liquids (ILs) are salts that are liquid close to room temperature. Their possible applications are numerous, e.g., as solvents for green chemistry, in various electrochemical devices, and even for such exotic purposes as spinning-liquid mirrors for lunar telescopes. Here we concentrate on their use for new advancements in energy-storage and -conversion devices: Batteries, supercapacitors or fuel cells using ILs as electrolytes could be important building blocks for the sustainable energy supply of tomorrow. Interestingly, ILs show glassy freezing and the universal, but until now only poorly understood dynamic properties of glassy matter, dominate many of their physical properties. We show that the conductivity of ILs, an essential figure of merit for any electrochemical application, depends in a systematic way not only on their glass temperature but also on the so-called fragility, characterizing the non-canonical super-Arrhenius temperature dependence of their ionic mobility.

  11. Importance of liquid fragility for energy applications of ionic liquids

    PubMed Central

    Sippel, P.; Lunkenheimer, P.; Krohns, S.; Thoms, E.; Loidl, A.

    2015-01-01

    Ionic liquids (ILs) are salts that are liquid close to room temperature. Their possible applications are numerous, e.g., as solvents for green chemistry, in various electrochemical devices, and even for such exotic purposes as spinning-liquid mirrors for lunar telescopes. Here we concentrate on their use for new advancements in energy-storage and -conversion devices: Batteries, supercapacitors or fuel cells using ILs as electrolytes could be important building blocks for the sustainable energy supply of tomorrow. Interestingly, ILs show glassy freezing and the universal, but until now only poorly understood dynamic properties of glassy matter, dominate many of their physical properties. We show that the conductivity of ILs, an essential figure of merit for any electrochemical application, depends in a systematic way not only on their glass temperature but also on the so-called fragility, characterizing the non-canonical super-Arrhenius temperature dependence of their ionic mobility. PMID:26355037

  12. Dissolving Polymers in Ionic Liquids.

    NASA Astrophysics Data System (ADS)

    Hoagland, David; Harner, John

    2009-03-01

    Dissolution and phase behavior of polymers in ionic liquids have been assessed by solution characterization techniques such as intrinsic viscosity and light scattering (static and dynamic). Elevated viscosity proved the greatest obstacle. As yet, whether principles standard to conventional polymer solutions apply to ionic liquid solutions is uncertain, especially for polymers such as polyelectrolytes and hydrophilic block copolymers that may specifically interact with ionic liquid anions or cations. For flexible polyelectrolytes (polymers releasing counterions into high dielectric solvents), characterization in ionic liquids suggests behaviors more typical of neutral polymer. Coil sizes and conformations are approximately the same as in aqueous buffer. Further, several globular proteins dissolve in a hydrophilic ionic liquid with conformations analogous to those in buffer. General principles of solubility, however, remain unclear, making predictions of which polymer dissolves in which ionic liquid difficult; several otherwise intractable polymers (e.g., cellulose, polyvinyl alcohol) dissolve and can be efficiently functionalized in ionic liquids.

  13. Wettability by Ionic Liquids.

    PubMed

    Liu, Hongliang; Jiang, Lei

    2016-01-01

    Ionic liquids (ILs) have become particularly attractive recently because they have demonstrated themselves to be important construction units in the broad fields of chemistry and materials science, from catalysis and synthesis to analysis and electrochemistry, from functional fluids to clean energy, from nanotechnology to functional materials. One of the greatest issues that determines the performance of ILs is the wettability of correlated surfaces. In this concept article, the key developments and issues in IL wettability are surveyed, including the electrowetting of ILs in gas-liquid-solid systems and liquid-liquid-solid systems, ILs as useful probe fluids, the superwettability of Ils, and future directions in IL wettability. This should generate extensive interest in the field and encourage more scientists to engage in this area to tackle its scientific challenges. PMID:26619157

  14. Preparation for nitrocellulose membrane-poly (vinyl alcohol)-ionic imprinting and its application to determine trace copper by room temperature phosphorimetry.

    PubMed

    Li, Zhi-Ming; Liu, Jia-Ming; Liu, Zhen-Bo; Liu, Qin-Ying; Lin, Xuan; Li, Fei-Ming; Yang, Min-Lan; Zhu, Guo-Hui; Huang, Xiao-Mei

    2007-04-18

    Nitrocellulose membrane-poly (vinyl alcohol)-ionic imprinting (NCM-PVA-I-I) was prepared using Cu2+ as template. The cavity in NCM-PVA-I-I matched Cu2+ very well and the selectivity was high. Cu2+ entered the cavity and then could form ionic association ([Cu2+] x [(Fin-)2]) with the anion of fluorescein (Fin-) outside the cavity by electrostatic effect. [Cu2+] x [(Fin-)2] could emit strong and stable room temperature phosphorescence on NCM-PVA-I-I. Its DeltaI(p) was proportional to the content of Cu2+. Based on the above facts, a new method for the determination of trace copper by solid substrate-room temperature phosphorimetry (NCM-PVA-I-I-SS-RTP, SS-RTP is the abbreviation of solid substrate-room temperature phosphorimetry) using NCM-PVA-I-I technique has been established. The linear range of this method was 2.00-144.00 fg Cu2+ spot(-1) (sample volume: 0.40 microL spot(-1), corresponding concentration: 5.00-360.00 pg mL(-1)), and the detection limit calculated by 3Sb/k was 0.43 fg Cu2+ spot(-1) (corresponding concentration: 1.1 x 10(-12) g mL(-1), n=11). Samples containing 2.00 and 144.00 fg Cu2+spot(-1) were measured, respectively, for seven times and R.S.D.s were 3.5% and 4.7%. NCM-PVA-I-I-SS-RTP could combine very well the characteristics of both the high sensitivity of SS-RTP and the high match and selectivity of NCM-PVA-I-I, and it was rapid, accurate, sensitive and with good repeatability. It has been successfully applied to determine trace copper in human hair and tea samples. PMID:17397651

  15. New room-temperature thermotropic perylene-based bisimides: Synthesis, liquid crystalline, light-emitting and electrochemical properties

    NASA Astrophysics Data System (ADS)

    Bijak, Katarzyna; Janeczek, Henryk; Grucela-Zajac, Marzena; Schab-Balcerzak, Ewa

    2013-03-01

    Three N-alkoxy-substituted perylene-3,4,9,10-tetracarboxyldiimides (PBIs) were synthesized and characterized through the data from 1H nuclear magnetic resonance (NMR), infrared spectroscopy (IR), elemental analysis, UV-vis absorption spectroscopy, photoluminescence (PL), cyclic voltammetry (CV) and differential pulse voltammetry (DPV) measurements. The phase behavior of obtained bisimides was examined by differential scanning calorimetry (DSC) and polarized optical microscopy (POM). They possess liquid crystalline properties at room temperature and a single mesophase structure exists in wide range of temperatures. The presented bisimides are well soluble in common solvents. All of them are highly fluorescent in solution and in solid state as blend with PMMA. The electrochemical band gap energy (Eg), LUMO and HOMO energy values were in the range 1.46-2.11 eV, -3.74 to -3.98 V and -5.38 to -5.96 V, respectively.

  16. NMR investigation of ionic liquid-LiX mixtures: pyrrolidinium cations and TFSI- anions.

    PubMed

    Nicotera, Isabella; Oliviero, Cesare; Henderson, Wesley A; Appetecchi, Giovanni B; Passerini, Stefano

    2005-12-01

    In this paper is reported an extensive NMR characterization of N-methyl-N-propyl-pyrrolidinium bis(trifluoromethanesulfonyl)imide (PYR13TFSI) room-temperature ionic liquid and its mixtures with LiTFSI. NMR was used to investigate the interactions between the ionic liquid and lithium salt and the diffusion coefficients of all ionic species present in these mixtures. The results are compared with previous DSC, Raman, and electrochemical investigations. PMID:16853972

  17. Properties of Water Confined in Ionic Liquids

    PubMed Central

    Saihara, Koji; Yoshimura, Yukihiro; Ohta, Soichi; Shimizu, Akio

    2015-01-01

    The varying states of water confined in the nano-domain structures of typical room temperature ionic liquids (ILs) were investigated by 1H NMR and by measurements of self-diffusion coefficients while systematically varying the IL cations and anions. The NMR peaks for water in BF4-based ILs were clearly split, indicating the presence of two discrete states of confined water (H2O and HOD). Proton and/or deuterium exchange rate among the water molecules was very slowly in the water-pocket. Notably, no significant changes were observed in the chemical shifts of the ILs. Self-diffusion coefficient results showed that water molecules exhibit a similar degree of mobility, although their diffusion rate is one order of magnitude faster than that of the IL cations and anions. These findings provide information on a completely new type of confinement, that of liquid water in soft matter. PMID:26024339

  18. Symmetry breaking in a dense liquid: Why sodium melts at room temperature.

    NASA Astrophysics Data System (ADS)

    Raty, Jean-Yves; Schwegler, Eric; Bonev, Stanimir

    2007-03-01

    The melting curve of sodium measured in [1] exhibits unusual features under pressure : the melting temperature, Tm, reaches a maximum around 30 GPa followed by a sharp decline from 1000 K to 300 K in the pressure range from 30 to 120 GPa. In this study, the structural and electronic properties of molten sodium are studied using first principles theory. With increasing pressure, liquid sodium initially evolves by assuming a more compact local structure, which accounts for the maximum of Tm at 30 GPas. However, at pressure around 65 gigapascals a transition to a lower coordinated structure takes place, driven by the opening of a pseudogap at the Fermi level. Remarkably, the broken symmetry liquid phase emerges at rather elevated temperatures and above the stability region of a closed packed free electron-like metal. The theory explains the measured drop of the sodium melting temperature, down to 300 kelvin at 105 GPas. [1] Gregoryantz et al., Phys. Rev. Lett. 94, 185502 (2005).

  19. Liquid polystyrene: a room-temperature photocurable soft lithography compatible pour-and-cure-type polystyrene.

    PubMed

    Nargang, Tobias M; Brockmann, Lara; Nikolov, Pavel Mitkov; Schild, Dieter; Helmer, Dorothea; Keller, Nico; Sachsenheimer, Kai; Wilhelm, Elisabeth; Pires, Leonardo; Dirschka, Marian; Kolew, Alexander; Schneider, Marc; Worgull, Matthias; Giselbrecht, Stefan; Neumann, Christiane; Rapp, Bastian E

    2014-08-01

    Materials matter in microfluidics. Since the introduction of soft lithography as a prototyping technique and polydimethylsiloxane (PDMS) as material of choice the microfluidics community has settled with using this material almost exclusively. However, for many applications PDMS is not an ideal material given its limited solvent resistance and hydrophobicity which makes it especially disadvantageous for certain cell-based assays. For these applications polystyrene (PS) would be a better choice. PS has been used in biology research and analytics for decades and numerous protocols have been developed and optimized for it. However, PS has not found widespread use in microfluidics mainly because, being a thermoplastic material, it is typically structured using industrial polymer replication techniques. This makes PS unsuitable for prototyping. In this paper, we introduce a new structuring method for PS which is compatible with soft lithography prototyping. We develop a liquid PS prepolymer which we term as "Liquid Polystyrene" (liqPS). liqPS is a viscous free-flowing liquid which can be cured by visible light exposure using soft replication templates, e.g., made from PDMS. Using liqPS prototyping microfluidic systems in PS is as easy as prototyping microfluidic systems in PDMS. We demonstrate that cured liqPS is (chemically and physically) identical to commercial PS. Comparative studies on mouse fibroblasts L929 showed that liqPS cannot be distinguished from commercial PS in such experiments. Researchers can develop and optimize microfluidic structures using liqPS and soft lithography. Once the device is to be commercialized it can be manufactured using scalable industrial polymer replication techniques in PS--the material is the same in both cases. Therefore, liqPS effectively closes the gap between "microfluidic prototyping" and "industrial microfluidics" by providing a common material. PMID:24887072

  20. Ionic liquids, electrolyte solutions including the ionic liquids, and energy storage devices including the ionic liquids

    DOEpatents

    Gering, Kevin L.; Harrup, Mason K.; Rollins, Harry W.

    2015-12-08

    An ionic liquid including a phosphazene compound that has a plurality of phosphorus-nitrogen units and at least one pendant group bonded to each phosphorus atom of the plurality of phosphorus-nitrogen units. One pendant group of the at least one pendant group comprises a positively charged pendant group. Additional embodiments of ionic liquids are disclosed, as are electrolyte solutions and energy storage devices including the embodiments of the ionic liquid.

  1. Carboxyl-functionalized task-specific ionic liquids for solubilizing metal oxides.

    PubMed

    Nockemann, Peter; Thijs, Ben; Parac-Vogt, Tatjana N; Van Hecke, Kristof; Van Meervelt, Luc; Tinant, Bernard; Hartenbach, Ingo; Schleid, Thomas; Ngan, Vu Thi; Nguyen, Minh Tho; Binnemans, Koen

    2008-11-01

    Imidazolium, pyridinium, pyrrolidinium, piperidinium, morpholinium, and quaternary ammonium bis(trifluoromethylsulfonyl)imide salts were functionalized with a carboxyl group. These ionic liquids are useful for the selective dissolution of metal oxides and hydroxides. Although these hydrophobic ionic liquids are immiscible with water at room temperature, several of them form a single phase with water at elevated temperatures. Phase separation occurs upon cooling. This thermomorphic behavior has been investigated by (1)H NMR, and it was found that it can be attributed to the temperature-dependent hydration and hydrogen-bond formation of the ionic liquid components. The crystal structures of four ionic liquids and five metal complexes have been determined. PMID:18841931

  2. Hydrogen-Bond Dynamics in a Protic Ionic Liquid: Evidence of Large-Angle Jumps.

    PubMed

    Hunger, Johannes; Sonnleitner, Thomas; Liu, Liyuan; Buchner, Richard; Bonn, Mischa; Bakker, Huib J

    2012-10-18

    We study the molecular rotation of the protic room-temperature ionic liquid ethylammonium nitrate with dielectric relaxation spectroscopy and femtosecond-infrared spectroscopy (fs-IR) of the ammonium N-H vibrations. The results suggest that the rotation of ethylammonium ion takes place via large angular jumps. Such nondiffusive reorientational dynamics is unique to strongly hydrogen-bonded liquids such as water and indicates that the intermolecular interaction is highly directional in this class of ionic liquids. PMID:26292245

  3. Electron drift velocities and electron mobilities in fast room-temperature dielectric liquids and their corresponding vapors

    NASA Astrophysics Data System (ADS)

    Faidas, H.; Christophorou, L. G.; McCorkle, D. L.; Carter, J. G.

    1990-09-01

    The drift velocity, w, of excess electrons as a function of the applied uniform electric field, E, in liquid tetramethylsilane (TMS), 2,2,4,4-tetramethylpentane (TMP), tetramethyltin (TMT), and in mixtures of TMS with TMP (molar ratio, M = 1.31/1) and n-pentane ( M = 102/1; 17/1; 5.6/1) has been measured up to E-values of 10 5 V cm -1 or density ( N)-reduced ele ctric held E/ N-values of 3 10 -17 V cm 2. The maximum w attained for these liquids, and the corresponding values of E are: 7.2 10 6 cm s -1 at 125 kV cm -1 for TMS, 6.0 10 6 cm s -1 at 75 kV cm -1 for TMS, 2.6 10 6 cm s -1 at 115 kV cm -1 for TMP, 3.2 10 6 cm s -1 at 105 kV cm -1 for TMS/TMP ( M = 1.31/1), 6.8 10 6 cm s -1 at 105 kV cm -1 for TMS/n-pentane ( M = 102/1), 6.8 10 6 cm s -1 at 145 kV cm -1 for TMS/n-pentane ( M = 17/1), and 4.9 10 6 cm s -1 at 145 kV cm -1 for TMS/n-pentane ( M = 5.6/1). The thermal-electron mobilities in the above liquid media are respectively 119.3, 85.7, 31.8, 39.1, 118, 85, and 47.6 cm 2 s -1 V -1. Also, w was measured as a function of E/ N for TMS, TMP, and neopentane vapors at room temperature and is compared with that in the corresponding liquids. Properties of these media which make them desirable for radiation detectors are discussed.

  4. Electrodeposition in Ionic Liquids.

    PubMed

    Zhang, Qinqin; Wang, Qian; Zhang, Suojiang; Lu, Xingmei; Zhang, Xiangping

    2016-02-01

    Due to their attractive physico-chemical properties, ionic liquids (ILs) are increasingly used as deposition electrolytes. This review summarizes recent advances in electrodeposition in ILs and focuses on its similarities and differences with that in aqueous solutions. The electrodeposition in ILs is divided into direct and template-assisted deposition. We detail the direct deposition of metals, alloys and semiconductors in five types of ILs, including halometallate ILs, air- and water-stable ILs, deep eutectic solvents (DESs), ILs with metal-containing cations, and protic ILs. Template-assisted deposition of nanostructures and macroporous structures in ILs is also presented. The effects of modulating factors such as deposition conditions (current density, current density mode, deposition time, temperature) and electrolyte components (cation, anion, metal salts, additives, water content) on the morphology, compositions, microstructures and properties of the prepared materials are highlighted. PMID:26530378

  5. A New Class of Ionic Liquids: Anion Amphiprotic Ionic Liquids.

    PubMed

    Treskow, Marcel; Pitawala, Jagath; Arenz, Sven; Matic, Aleksandar; Johansson, Patrik

    2012-08-16

    We here present a new class of protic ionic liquids, anion amphiprotic ionic liquids (AAILs). These materials are protonation equilibrium free protic ionic liquids and interesting in their own right by not following the classical Brnsted acid-base neutralization concept. Due to the very simple synthesis route applied and their stable basic chemistry, we believe in a potential use for manifold applications. This is supported by the combination of practical material properties, foremost, a general intrinsic stability versus reversal of the formation reaction toward neutral species, broad liquidus ranges, long-term thermal stabilities, high conductivities, protic characteristics, and a general stability versus water. PMID:26295756

  6. Low-melting mixtures based on choline ionic liquids.

    PubMed

    Rengstl, Doris; Fischer, Veronika; Kunz, Werner

    2014-11-01

    In this article a strategy is proposed for the design of low toxic, room temperature liquid low-melting mixtures (LMMs) which are entirely composed of natural materials. From literature it is well known that, in general, deep eutectic solvents based on choline chloride and dicarboxylic acids are LMMs, but not liquids at room temperature, with one exception: a 1?:?1 molar mixture of malonic acid and choline chloride. Therefore, the starting point of this study was the decrease of the melting point of one of the components, namely the dicarboxylic acid, which is succinic, glutaric or adipic acid. For this purpose, one of the two protons of the acidic group was exchanged by a bulky unsymmetrical choline cation. The resulting ionic liquids (ILs) were still solid at room temperature, but have a reduced melting temperature compared to the corresponding acids. In the second step, mixtures of these ILs with choline chloride were prepared. It turned out that choline glutarate-choline chloride mixtures are liquids at room temperature at compositions containing 95-98 wt% of choline glutarate. Finally, urea was added as another hydrogen bond donor. Density, conductivity and viscosity measurements were performed for all obtained mixtures. Moreover, a Walden plot was drawn which indicates that all mixtures are liquids with fully dissociated ions moving independently. Therefore, they are considered as "good" ionic liquids and, thus, for example they can be used to exchange more toxic or less biodegradable ILs in application processes. A brief outlook containing application possibilities is given. It is demonstrated that choline dodecylsulfate is readily soluble in these mixtures, forming aggregates in the LMM at temperatures exceeding 55 C. PMID:25242504

  7. Ionic properties of liquid crystals dispersed with carbon nanotubes and montmorillonite nanoplatelets

    NASA Astrophysics Data System (ADS)

    Liu, Hsuan-Hung; Lee, Wei

    2010-10-01

    The ionic properties of liquid crystals doped with one-dimensional carbon nanotubes, two-dimensional montmorillonite, and a mixture of both are investigated. The results indicate that the relaxation times of electrode polarization and ionic conductivity are time-dependent after the cell fabrication regardless of doping. While all of the dopants are effective in capturing impurity ions, the cells containing the hybrid dopant exhibit the feeblest ionic effect at room temperature.

  8. Room temperature deposition of ZnSe thin films by successive ionic layer adsorption and reaction (SILAR) method

    SciTech Connect

    Kale, R.B.; Lokhande, C.D. . E-mail: rb_kale@yahoo.co.in

    2004-10-04

    The zinc selenide (ZnSe) thin films are deposited onto glass substrate using relatively simple and inexpensive successive ionic layer adsorption and reaction (SILAR) method. The films are deposited using zinc acetate sodium selenosulphate precursors. The concentration, pH, immersion and rinsing times and number of immersion cycles have been optimized to obtain good quality ZnSe thin films. The X-ray diffraction (XRD) study and scanning electron microscopy (SEM) studies reveals nanocrystalline nature alongwith some amorphous phase present in ZnSe thin films. Energy dispersive X-ray (EDAX) analysis shows that the films are Se deficient. From optical absorption data, the optical band gap 'E{sub g}' for as-deposited thin film was found to be 2.8 eV and electrical resistivity in the order of 10{sup 7} {omega} cm.

  9. Liquid-liquid extraction of neodymium(III) by dialkylphosphate ionic liquids from acidic medium: the importance of the ionic liquid cation.

    PubMed

    Rout, Alok; Kotlarska, Justyna; Dehaen, Wim; Binnemans, Koen

    2013-10-21

    The ionic liquids 1-hexyl-3-methylimidazolium bis(2-ethylhexyl)phosphate, [C6mim][DEHP], 1-hexyl-1-methylpyrrolidinium bis(2-ethylhexyl)phosphate, [C6mpyr][DEHP], and tetrabutylammonium bis(2-ethylhexyl)phosphate, [N4444][DEHP], were prepared and characterized using (1)H and (13)C NMR spectroscopy. The extraction behavior of neodymium(iii) from nitrate medium by these ionic liquids, diluted with the room temperature ionic liquids 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, [C6mim][NTf2], 1-hexyl-3-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, [C6mpyr][NTf2], and tributylmethylammonium bis(trifluoromethylsulfonyl)imide, [N1444][NTf2], was studied. The distribution ratio of neodymium(iii) was measured as a function of various parameters, such as pH, concentration of the ionic liquid extractant, nature of diluents, concentration of ionic liquid cations and nitrate anions in the aqueous phase. The extraction behavior was compared with that obtained for a solution of the molecular extractant bis(2-ethylhexyl)phosphoric acid (DEHPA) in an ionic liquid diluent. The extraction of neodymium(iii) in the ionic liquids [C6mim][DEHP] and [C6mpyr][DEHP] showed markedly different extraction properties in comparison with that of the quaternary ammonium analogue [N4444][DEHP], especially concerning the pH dependence of the extraction process. These results show that the extraction process can be tuned by the selection of the ionic liquid cation. The extraction experiments also included the trivalent rare-earth ions lanthanum(iii), cerium(iii), praseodymium(iii), ytterbium(iii) and yttrium(iii). Studies of the stripping behavior and the reusability of the ionic liquids were carried out, which indicate that the ionic liquids can be reused with no loss in activity. PMID:23949284

  10. Effective Energy Transfer via Plasmon-Activated High-Energy Water Promotes Its Fundamental Activities of Solubility, Ionic Conductivity, and Extraction at Room Temperature

    NASA Astrophysics Data System (ADS)

    Yang, Chih-Ping; Chen, Hsiao-Chien; Wang, Ching-Chiung; Tsai, Po-Wei; Ho, Chia-Wen; Liu, Yu-Chuan

    2015-12-01

    Water is a ubiquitous solvent in biological, physical, and chemical processes. Unique properties of water result from water’s tetrahedral hydrogen-bonded (HB) network (THBN). The original THBN is destroyed when water is confined in a nanosized environment or localized at interfaces, resulting in corresponding changes in HB-dependent properties. In this work, we present an innovative idea to validate the reserve energy of high-energy water and applications of high-energy water to promote water’s fundamental activities of solubility, ionic conductivity, and extraction at room temperature. High-energy water with reduced HBs was created by utilizing hot electrons with energies from the decay of surface plasmon excited at gold (Au) nanoparticles (NPs). Compared to conventional deionized (DI) water, solubilities of alkali metal-chloride salts in high-energy water were significantly increased, especially for salts that release heat when dissolved. The ionic conductivity of NaCl in high-energy water was also markedly higher, especially when the electrolyte’s concentration was extremely low. In addition, antioxidative components, such as polyphenols and 2,3,5,4’-tetrahydroxystilbene-2-O-beta-d-glucoside (THSG) from teas, and Polygonum multiflorum (PM), could more effectively be extracted using high-energy water. These results demonstrate that high-energy water has emerged as a promising innovative solvent for promoting water’s fundamental activities via effective energy transfer.

  11. Effective Energy Transfer via Plasmon-Activated High-Energy Water Promotes Its Fundamental Activities of Solubility, Ionic Conductivity, and Extraction at Room Temperature

    PubMed Central

    Yang, Chih-Ping; Chen, Hsiao-Chien; Wang, Ching-Chiung; Tsai, Po-Wei; Ho, Chia-Wen; Liu, Yu-Chuan

    2015-01-01

    Water is a ubiquitous solvent in biological, physical, and chemical processes. Unique properties of water result from water’s tetrahedral hydrogen-bonded (HB) network (THBN). The original THBN is destroyed when water is confined in a nanosized environment or localized at interfaces, resulting in corresponding changes in HB-dependent properties. In this work, we present an innovative idea to validate the reserve energy of high-energy water and applications of high-energy water to promote water’s fundamental activities of solubility, ionic conductivity, and extraction at room temperature. High-energy water with reduced HBs was created by utilizing hot electrons with energies from the decay of surface plasmon excited at gold (Au) nanoparticles (NPs). Compared to conventional deionized (DI) water, solubilities of alkali metal-chloride salts in high-energy water were significantly increased, especially for salts that release heat when dissolved. The ionic conductivity of NaCl in high-energy water was also markedly higher, especially when the electrolyte’s concentration was extremely low. In addition, antioxidative components, such as polyphenols and 2,3,5,4’-tetrahydroxystilbene-2-O-beta-d-glucoside (THSG) from teas, and Polygonum multiflorum (PM), could more effectively be extracted using high-energy water. These results demonstrate that high-energy water has emerged as a promising innovative solvent for promoting water’s fundamental activities via effective energy transfer. PMID:26658304

  12. Effective Energy Transfer via Plasmon-Activated High-Energy Water Promotes Its Fundamental Activities of Solubility, Ionic Conductivity, and Extraction at Room Temperature.

    PubMed

    Yang, Chih-Ping; Chen, Hsiao-Chien; Wang, Ching-Chiung; Tsai, Po-Wei; Ho, Chia-Wen; Liu, Yu-Chuan

    2015-01-01

    Water is a ubiquitous solvent in biological, physical, and chemical processes. Unique properties of water result from water's tetrahedral hydrogen-bonded (HB) network (THBN). The original THBN is destroyed when water is confined in a nanosized environment or localized at interfaces, resulting in corresponding changes in HB-dependent properties. In this work, we present an innovative idea to validate the reserve energy of high-energy water and applications of high-energy water to promote water's fundamental activities of solubility, ionic conductivity, and extraction at room temperature. High-energy water with reduced HBs was created by utilizing hot electrons with energies from the decay of surface plasmon excited at gold (Au) nanoparticles (NPs). Compared to conventional deionized (DI) water, solubilities of alkali metal-chloride salts in high-energy water were significantly increased, especially for salts that release heat when dissolved. The ionic conductivity of NaCl in high-energy water was also markedly higher, especially when the electrolyte's concentration was extremely low. In addition, antioxidative components, such as polyphenols and 2,3,5,4'-tetrahydroxystilbene-2-O-beta-d-glucoside (THSG) from teas, and Polygonum multiflorum (PM), could more effectively be extracted using high-energy water. These results demonstrate that high-energy water has emerged as a promising innovative solvent for promoting water's fundamental activities via effective energy transfer. PMID:26658304

  13. Synthesis and characterization of new class of ionic liquids containing phenolate anion

    NASA Astrophysics Data System (ADS)

    Lethesh, Kallidanthiyil Chellappan; Wilfred, Cecilia Devi; Taha, M. F.; Thanabalan, M.

    2014-10-01

    In these manuscript novel ionic liquids containing a new class of "phenolate" anions was synthesized and characterized. 1-methylmidazole with different alkyl chains such as butyl, hexyl and octyl groups was used as the cationic part. All the ionic liquids were obtained as liquids at room temperature. The synthesized ionic liquids were characterized using 1H NMR and 13C NMR spectroscopy. The thermal stability of the ionic liquids was studied using thermo gravimetric analysis (TGA). The effect of temperature on the density and viscosity of the ionic liquids were studied over a temperature range from 293.15 K to 373.15K at atmospheric pressure. From the experimental values of density, the molecular volume, standard molar entropy and the lattice energy of the ionic liquids were calculated.

  14. Solvent Extraction of Sr2+ and Cs+ Based on Hydrophobic Protic Ionic Liquids

    NASA Astrophysics Data System (ADS)

    Luo, Huimin; Yu, Miao; Dai, Sheng

    2007-06-01

    A series of new hydrophobic and protic alkylammonium ionic liquids with bis(trifluoromethylsulfonyl) imide or bis(perfluoroethylsulfonyl)imide as conjugated anions was synthesized in a one-pot reaction with a high yield. In essence our synthesis method involves the combination of neutralization and metathesis reactions. Some of these hydrophobic and protic ionic liquids were liquids at room temperature and therefore investigated as new extraction media for separation of Sr2+ and Cs+ from aqueous solutions. An excellent extraction efficiency was found for some of these ionic liquids using dicyclohexano-18-crown-6 and calix[4]arene-bis(tert-octylbenzo-crown-6) as extractants. The observed enhancement in the extraction efficiency can be attributed to the greater hydrophilicity of the cations of the protic ionic liquids. The application of the protic ionic liquids as new solvent systems for solvent extraction opens up a new avenue in searching for simple and efficient ionic liquids for tailored separation processes.

  15. Synthesis and characterization of new class of ionic liquids containing phenolate anion

    SciTech Connect

    Lethesh, Kallidanthiyil Chellappan; Wilfred, Cecilia Devi; Taha, M. F.; Thanabalan, M.

    2014-10-24

    In these manuscript novel ionic liquids containing a new class of 'phenolate' anions was synthesized and characterized. 1-methylmidazole with different alkyl chains such as butyl, hexyl and octyl groups was used as the cationic part. All the ionic liquids were obtained as liquids at room temperature. The synthesized ionic liquids were characterized using {sup 1}H NMR and {sup 13}C NMR spectroscopy. The thermal stability of the ionic liquids was studied using thermo gravimetric analysis (TGA). The effect of temperature on the density and viscosity of the ionic liquids were studied over a temperature range from 293.15 K to 373.15K at atmospheric pressure. From the experimental values of density, the molecular volume, standard molar entropy and the lattice energy of the ionic liquids were calculated.

  16. Ionic Liquids with Ammonium Cations as Lubricants or Additives

    SciTech Connect

    Qu, Jun; Blau, Peter Julian; Dai, Sheng; Luo, Huimin; Truhan, Jr., John J

    2006-01-01

    Friction and wear are estimated to cost 6% of the US gross national product, or around $700 billion annually. A new class of more effective lubricants could lead to huge energy savings. Limited recent literature has suggested potential for using room-temperature ionic liquids as lubricants, however only a few out of millions (or more) of species have been evaluated. Recent ORNL work discovered a new category of ionic liquids with ammonium cations that have demonstrated promising lubricating properties as net lubricants or lubricant additives, particularly in lubricating difficult-to-lubricate metals like aluminum. More than 30% friction reduction has been observed on ammonium-based ionic liquids compared to conventional hydrocarbon oils. The inherent polarity of ionic liquids is believed to provide strong adhesion to contact surfaces and form a boundary lubricating film leading to friction and wear reductions. Other advantages of ionic liquids include (1) negligible volatility, (2) high thermal stability, (3) non-flammability, and (4) better intrinsic properties that eliminate the necessity of many expensive lubricant additives. With very flexible molecular structures, this new class of lubricants, particularly ammonium-based ionic liquids, can be tailored to fit a big variety of applications including but not limited to bearings, combustion engines, MEMS, and metal forming.

  17. Hydrophobic ionic liquids

    DOEpatents

    Koch, V.R.; Nanjundiah, C.; Carlin, R.T.

    1998-10-27

    Ionic liquids having improved properties for application in non-aqueous batteries, electrochemical capacitors, electroplating, catalysis and chemical separations are disclosed. Exemplary compounds have one of the following formulas shown in a diagram wherein R{sub 1}, R{sub 2}, R{sub 3}, R{sub 4}, R{sub 5}, and R{sub 6} are either H; F; separate alkyl groups of from 1 to 4 carbon atoms, respectively, or joined together to constitute a unitary alkylene radical of from 2 to 4 carbon atoms forming a ring structure converging on N; or separate phenyl groups; and wherein the alkyl groups, alkylene radicals or phenyl groups may be substituted with electron withdrawing groups, preferably F-, Cl-, CF{sub 3}-, SF{sub 5}-, CF{sub 3}S-, (CF{sub 3}){sub 2}CHS- or (CF{sub 3}){sub 3}CS-; and X{sup {minus}} is a non-Lewis acid-containing polyatomic anion having a van der Waals volume exceeding 100 {angstrom}{sup 3}. 4 figs.

  18. Hydrophobic ionic liquids

    DOEpatents

    Koch, Victor R. (Lincoln, MA); Nanjundiah, Chenniah (Lynn, MA); Carlin, Richard T. (Nashua, NH)

    1998-01-01

    Ionic liquids having improved properties for application in non-aqueous batteries, electrochemical capacitors, electroplating, catalysis and chemical separations are disclosed. Exemplary compounds have one of the following formulas: ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5, and R.sub.6 are either H; F; separate alkyl groups of from 1 to 4 carbon atoms, respectively, or joined together to constitute a unitary alkylene radical of from 2 to 4 carbon atoms forming a ring structure converging on N; or separate phenyl groups; and wherein the alkyl groups, alkylene radicals or phenyl groups may be substituted with electron withdrawing groups, preferably F--, Cl--, CF.sub.3 --, SF.sub.5 --, CF.sub.3 S--, (CF.sub.3).sub.2 CHS-- or (CF.sub.3).sub.3 CS--; and X.sup.- is a non-Lewis acid-containing polyatomic anion having a van der Waals volume exceeding 100 .ANG..sup.3.

  19. Morphology-enhanced conductivity in dry ionic liquids.

    PubMed

    Erba?, Aykut; de la Cruz, Monica Olvera

    2016-03-01

    Ionic liquids exhibit fascinating nanoscale morphological phases and are promising materials for energy storage applications. Liquid crystalline order emerges in ionic liquids with specific chemical structures. Here, we investigate the phase behaviour and related ionic conductivities of dry ionic liquids, using extensive molecular dynamics simulations. Temperature dependence, properties of polymeric tail and excluded volume symmetry of the amphiphilic ionic liquid molecules are investigated in large scale systems with both short and long-range Coulomb interactions. Our results suggest that by adjusting stiffness and steric interactions of the amphiphilic molecules, lamellar or 3D continuous phases result in these molecular salts. The resulting phases are composed of ion rich and ion pure domains. In 3D phases, ion rich clusters form ionic channels and have significant effects on the conductive properties of the observed nano-phases. If there is no excluded-volume asymmetry along the molecules, mostly lamellar phases with anisotropic conductivities emerge. If the steric interactions become asymmetric, lamellar phases are replaced by complex 3D continuous phases. Within the temperature ranges for which morphological phases are observed, conductivities exhibit low-temperature maxima in accord with experiments on ionic liquid crystals. Stiffer molecules increase the high-conductivity interval and strengthen temperature-resistance of morphological phases. Increasing the steric interactions of cation leads to higher conductivities. Moreover, at low monomeric volume fractions and at low temperatures, cavities are observed in the nano-phases of flexible ionic liquids. We also demonstrate that, in the absence of electrostatic interactions, the morphology is distorted. Our findings inspire new design principles for room temperature ionic liquids and help explain previously-reported experimental data. PMID:26862598

  20. Additive polarizabilities in ionic liquids.

    PubMed

    Bernardes, Carlos E S; Shimizu, Karina; Lopes, Jos Nuno Canongia; Marquetand, Philipp; Heid, Esther; Steinhauser, Othmar; Schrder, Christian

    2016-01-21

    An extended designed regression analysis of experimental data on density and refractive indices of several classes of ionic liquids yielded statistically averaged atomic volumes and polarizabilities of the constituting atoms. These values can be used to predict the molecular volume and polarizability of an unknown ionic liquid as well as its mass density and refractive index. Our approach does not need information on the molecular structure of the ionic liquid, but it turned out that the discrimination of the hybridization state of the carbons improved the overall result. Our results are not only compared to experimental data but also to quantum-chemical calculations. Furthermore, fractional charges of ionic liquid ions and their relation to polarizability are discussed. PMID:26675139

  1. Ionic Liquid Epoxy Resin Monomers

    NASA Technical Reports Server (NTRS)

    Paley, Mark S. (Inventor)

    2013-01-01

    Ionic liquid epoxide monomers capable of reacting with cross-linking agents to form polymers with high tensile and adhesive strengths. Ionic liquid epoxide monomers comprising at least one bis(glycidyl) N-substituted nitrogen heterocyclic cation are made from nitrogen heterocycles corresponding to the bis(glycidyl) N-substituted nitrogen heterocyclic cations by a method involving a non-nucleophilic anion, an alkali metal cation, epichlorohydrin, and a strong base.

  2. Formation of Interconnected Aggregates in Aqueous Dicationic Ionic Liquid Solutions.

    PubMed

    Bhargava, B L; Klein, Michael L

    2010-03-01

    The structure and organization in an aqueous solution of a gemini surfactant, the dicationic ionic liquid 1,3-bis(3-decylimidazolium-1-yl) propane bromide, and its vapor-liquid interface have been studied using molecular dynamics simulations at room temperature. Starting from a uniform distribution of cations, the system is found to spontaneously evolve forming cross-linked cationic micellar aggregates. Alkyl tails are typically found buried inside the aggregates to minimize their unfavorable interactions with water, whereas the polar head groups are present at the micellar surfaces, exposed to water. Anions are found throughout the solution and are not strongly bound to the cations. Cationic micellar aggregates exhibit an interesting behavior: interconnection mediated by head groups, a phenomenon which is not observed in monocationic ionic liquid solutions. The structure of the vapor-liquid interface of the solution, the structure of the micellar aggregates, and the distribution of counterions are also discussed. PMID:26613314

  3. Limitations to the room temperature mobility of two- and three-dimensional electron liquids in SrTiO{sub 3}

    SciTech Connect

    Mikheev, Evgeny; Himmetoglu, Burak; Kajdos, Adam P.; Moetakef, Pouya; Cain, Tyler A.; Van de Walle, Chris G.; Stemmer, Susanne

    2015-02-09

    We analyze and compare the temperature dependence of the electron mobility of two- and three-dimensional electron liquids in SrTiO{sub 3}. The contributions of electron-electron scattering must be taken into account to accurately describe the mobility in both cases. For uniformly doped, three-dimensional electron liquids, the room temperature mobility crosses over from longitudinal optical (LO) phonon-scattering-limited to electron-electron-scattering-limited as a function of carrier density. In high-density, two-dimensional electron liquids, LO phonon scattering is completely screened and the mobility is dominated by electron-electron scattering up to room temperature. The possible origins of the observed behavior and the consequences for approaches to improve the mobility are discussed.

  4. Ionic Liquid Membranes for Carbon Dioxide Separation

    SciTech Connect

    Myers, C.R.; Ilconich, J.B.; Luebke, D.R.; Pennline, H.W.

    2008-07-12

    Recent scientific studies are rapidly advancing novel technological improvements and engineering developments that demonstrate the ability to minimize, eliminate, or facilitate the removal of various contaminants and green house gas emissions in power generation. The Integrated Gasification Combined Cycle (IGCC) shows promise for carbon dioxide mitigation not only because of its higher efficiency as compared to conventional coal firing plants, but also due to a higher driving force in the form of high partial pressure. One of the novel technological concepts currently being developed and investigated is membranes for carbon dioxide (CO2) separation, due to simplicity and ease of scaling. A challenge in using membranes for CO2 capture in IGCC is the possibility of failure at elevated temperatures or pressures. Our earlier research studies examined the use of ionic liquids on various supports for CO2 separation over the temperature range, 37°C-300°C. The ionic liquid, 1-hexyl-3methylimidazolium Bis(trifluoromethylsulfonyl)imide, ([hmim][Tf2N]), was chosen for our initial studies with the following supports: polysulfone (PSF), poly(ether sulfone) (PES), and cross-linked nylon. The PSF and PES supports had similar performance at room temperature, but increasing temperature caused the supported membranes to fail. The ionic liquid with the PES support greatly affected the glass transition temperature, while with the PSF, the glass transition temperature was only slightly depressed. The cross-linked nylon support maintained performance without degradation over the temperature range 37-300°C with respect to its permeability and selectivity. However, while the cross-linked nylon support was able to withstand temperatures, the permeability continued to increase and the selectivity decreased with increasing temperature. Our studies indicated that further testing should examine the use of other ionic liquids, including those that form chemical complexes with CO2 based on amine interactions. The hypothesis is that the performance at the elevated temperatures could be improved by allowing a facilitated transport mechanism to become dominant. Several amine-based ionic liquids were tested on the cross-linked nylon support. It was found that using the amine-based ionic liquid did improve selectivity and permeability at higher temperature. The hypothesis was confirmed, and it was determined that the type of amine used also played a role in facilitated transport. Given the appropriate aminated ionic liquid with the cross-linked nylon support, it is possible to have a membrane capable of separating CO2 at IGCC conditions. With this being the case, the research has expanded to include separation of other constituents besides CO2 (CO, H2S, etc.) and if they play a role in membrane poisoning or degradation. This communication will discuss the operation of the recently fabricated ionic liquid membranes and the impact of gaseous components other than CO2 on their performance and stability.

  5. Determination of the polarities of some ionic liquids using 2-nitrocyclohexanone as the probe.

    PubMed

    Angelini, Guido; Chiappe, Cinzia; De Maria, Paolo; Fontana, Antonella; Gasparrini, Francesco; Pieraccini, Daniela; Pierini, Marco; Siani, Gabriella

    2005-09-30

    Solute-solvent interactions on the keto-enol tautomerism of 2-nitrocyclohexanone in several organic solvents and room-temperature ionic liquids (RTILs) have been analyzed in terms of multiparameter equations. Permittivity and cohesive pressure values of the RTILs, unavailable by direct measurements, have been derived. PMID:16277347

  6. Glass transition of ionic liquids under high pressure.

    PubMed

    Ribeiro, Mauro C C; Pdua, Aglio A H; Gomes, Margarida F Costa

    2014-06-28

    The glass transition pressure at room temperature, pg, of six ionic liquids based on 1-alkyl-3-methylimidazolium cations and the anions [BF4](-), [PF6](-), and bis(trifluromethanesulfonyl)imide, [NTf2](-), has been obtained from the pressure dependence of the bandwidth of the ruby fluorescence line in diamond anvil cells. Molar volume, Vm(pg), has been estimated by a group contribution model (GCM) developed for the ionic liquids. A density scaling relation, TV(?), has been considered for the states Vm(pg, 295?K) and Vm(Tg, 0.1 MPa) using the simplifying condition that the viscosity at the glass transition is the same at pg at room temperature and at atmospheric pressure at Tg. Assuming a constant ? over this range of density, a reasonable agreement has been found for the ? determined herein and that of a previous density scaling analysis of ionic liquids viscosities under moderate conditions. Further support for the appropriateness of extrapolating the GCM equation of state to the GPa pressure range is provided by comparing the GCM and an equation of state previously derived in the power law density-scaling regime. PMID:24985661

  7. Nanoscale organization in aqueous dicationic ionic liquid solutions.

    PubMed

    Bhargava, B L; Klein, Michael L

    2011-09-01

    Coarse-grained molecular dynamics simulations have been performed on aqueous solutions of the gemini dicationic ionic liquid 1,5-bis(3-decylimidazolium-1-yl) pentane bromide at room temperature to study the structure and organization in the solution. Several trajectories corresponding to different concentrations of the ionic liquid (IL) in the solution were generated for about a microsecond. The 40% (w/w) aqueous mixture evolves to a hexagonal structure starting from a random distribution of ions. Spontaneous aggregation of cations was observed in solutions at lower concentrations. Unlike the monocationic ILs, which form spherical aggregates, the aggregates observed in the dicationic IL solution displayed a near-hexagonal arrangement of the hydrophobic cores that were connected to each other by hydrophilic head groups. Anions were found to be present close to the polar head groups. The formation of the interlinked aggregates from a random distribution and the organization at the vapor-liquid interface are also discussed. PMID:21797249

  8. Selective extraction of copper, mercury, silver and palladium ionsfrom water using hydrophobic ionic liquids.

    SciTech Connect

    Papaiconomou, Nicolas; Lee, Jong-Min; Salminen, Justin; VonStosch, Moritz; Prausnitz, John M.

    2007-06-25

    Extraction of dilute metal ions from water was performed near room temperature with a variety of ionic liquids. Distribution coefficients are reported for fourteen metal ions extracted with ionic liquids containing cations 1-octyl-4-methylpyridinium [4MOPYR]{sup +}, 1-methyl-1-octylpyrrolidinium [MOPYRRO]{sup +} or 1-methyl-1-octylpiperidinium [MOPIP]{sup +}, and anions tetrafluoroborate [BF{sub 4}]{sup +}, trifluoromethyl sulfonate [TfO]{sup +} or nonafluorobutyl sulfonate [NfO]{sup +}. Ionic liquids containing octylpyridinium cations are very good for extracting mercury ions. However, other metal ions were not significantly extracted by any of these ionic liquids. Extractions were also performed with four new task-specific ionic liquids. Such liquids containing a disulfide functional group are efficient and selective for mercury and copper, whereas those containing a nitrile functional group are efficient and selective for silver and palladium.

  9. Room-Temperature Ionic Liquids and Protective Phospholipid Membranes: Interactions on Surfaces

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Green chemistry is a growing area of research that involves reducing or eliminating hazardous materials (products and solvents) from chemical processes. An area of green chemistry that is quite interesting to us is bioelectrocatalytic transformation of lipids in non-aqueous solvents called room-tem...

  10. Room-temperature ionic liquids: temperature dependence of gas solubility selectivity

    SciTech Connect

    Alexia Finotello; Jason E. Bara; Dean Camper; Richard D. Noble

    2008-05-15

    This study focuses on bulk fluid solubility of carbon dioxide (CO{sub 2}), methane (CH{sub 4}), hydrogen (H{sub 2}), and nitrogen (N{sub 2}) gases in the imidazolium-based RTILs: 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ((emim)(Tf{sub 2}N)),1-ethyl-3-methylimidazolium tetrafluoroborate ((emim)(BF{sub 4})),1-n-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide((hmim)(Tf{sub 2}N)), and 1,3-dimethylimidazolium methyl sulfate ((mmim)(MeSO{sub 4})) as a function of temperature (25, 40, 55, and 70{sup o}C) at near-atmospheric pressures. The experimental behaviors are explained in terms of thermodynamic relationships that account for the negligible vapor pressure of the RTIL as well as the low solubilities of the gases. Results show that, as temperature increases, the solubility of CO{sub 2} decreases in all RTILs, the solubility of CH{sub 4} remains constant in (emim)(Tf{sub 2}N) and (hmim)(Tf{sub 2}N) but increases in(mmim)(MeSO{sub 4}) and (emim)(BF{sub 4}), and the solubility of N{sub 2} and H{sub 2} increases. Also, the ideal solubility selectivity (ratio of pure-component solubilities) increases as temperature decreases for CO{sub 2}/N{sub 2}, CO{sub 2}/CH{sub 4}, and CO{sub 2}/H{sub 2} systems. Experimental values for the enthalpy and entropy of solvation are reported.

  11. Spontaneous product segregation from reactions in ionic liquids: application in Pd-catalyzed aliphatic alcohol oxidation.

    PubMed

    Van Doorslaer, Charlie; Schellekens, Yves; Mertens, Pascal; Binnemans, Koen; De Vos, Dirk

    2010-02-28

    A methodology is introduced to separate polar reaction products from ionic liquids without the need for organic solvent extraction or distillation. We investigated product isolation after an alcohol oxidation performed in ionic liquids. Suitable ionic liquids were selected based on their mixing or demixing with a range of alcohols and the derived ketones. The aim was to obtain complete miscibility with the alcohol substrate at reaction temperature and a clear phase separation of the derived ketone product at room temperature. Six imidazolium based ionic liquids displayed this desired behaviour and were sufficiently stable to oxidation. These ionic liquids were then employed in the oxidation of non-activated aliphatic alcohols with molecular oxygen in the presence of palladium(II) acetate. In 1-butyl-3-methylimidazolium tetrafluoroborate, 2-ketone yields of 79 and 86% were obtained for, respectively, 2-octanol and 2-decanol. After cooling to room temperature the ionic liquid expels the immiscible ketone and the product phase can be isolated by decantation. In addition, the ionic liquid acts as an immobilization medium for the palladium catalyst, allowing efficient catalyst recycling. PMID:20145838

  12. Oxidative desulfurization of dibenzothiophene from model oil using ionic liquids as extracting agent

    NASA Astrophysics Data System (ADS)

    Taha, Mohd F.; Atikah, N.; Chong, F. K.; Shaharun, Maizatul S.

    2012-09-01

    The oxidative desulfurization of dibenzothiophene (DBT) from model oil (in n-dodecane) was carried out using ionic liquid as the extractant and catalyst, and hydrogen peroxide (H2O2) in combination with acetic acid (CH3COOH) and sulphuric acid (H2SO4) as the oxidant. The ionic liquids used were 1-butyl-3-methylimidazolium octyl sulphate ([Bmim][OcSO4]) and 1-butyl-3-methylimidazolium acetate ([Bmim][Ac]). The effect of the amounts of H2O2 on oxidative desulphurization of model oil was first investigated without the usage of ionic liquids at room temperature. The results indicate that greater amount of H2O2 give higher desulfurization and the maximum desulfurization in this study, i.e. 34 %, was occurred when the molar ratio of H2O2 to sulfur was 5:1. With the usage of ionic liquid and the molar ratio of 5:1 (H2O2:sulfur), the efficiency of DBT removal from model oil was increased significantly in terms of percent removal and removal time. Ionic liquid of [Bmim][OcSO4] performed better than [Bmim][Ac] with 72 % DBT removal. When molar ratio of H2O2 to sulphur was 5:1, volume ratio of ionic liquid to model oil was 1:1 and mixing time was 60 min at room temperature. The results indicate the potential of ionic liquids as the extractant and catalyst for oxidative desulfurization of hydrocarbon fuels.

  13. Ionic liquids in surface electrochemistry.

    PubMed

    Liu, Hongtao; Liu, Yang; Li, Jinghong

    2010-02-28

    Ionic liquids (IL) are widely used in electrochemistry due to their excellent properties such as good ionic conductivity, wide electrochemical potential window, high viscosity, high thermal stability, wide liquid range and tunable solvent properties. In electrochemistry, the performance of an electrochemical system is dependent on the properties of the interface at the IL/electrode. This review presents the surface electrochemistry in ILs, and the interfacial structures of IL/electrode and heterogeneous electron-transfer kinetics are detailed. Finally, the updated researches on the electrochemical applications of ILs such as electrode deposition, electrosynthesis, electrocatalysis, electrochemical biosensing, electrochemical capacitor and lithium batteries are demonstrated. PMID:20145833

  14. Surface Activity and Aggregation Behavior of Siloxane-Based Ionic Liquids in Aqueous Solution.

    PubMed

    Wang, Guoyong; Li, Ping; Du, Zhiping; Wang, Wanxu; Li, Guojin

    2015-08-01

    Six novel siloxane-based surface-active ionic liquids (SAILs)--siloxane ammonium carboxylate [Si(n)N(2)-CA(1), (n = 3, 4)]--were designed and synthesized. Their melting points, surface activities, and self-aggregation behavior in aqueous solution were studied. The results showed that because of the bulky hydrophobic siloxane chains at the end of the tail, all six siloxane-based SAILs are room-temperature ionic liquids (RT-SAILs). The introduction of the siloxane group can reduce the melting point of ionic liquids to below room temperature and can promote the micellization and aggregation behavior more efficiently. These siloxane-based SAILs can greatly reduce the surface tension of water, as shown by the critical aggregation concentration (?CAC) values of 20 mNm(-1); all six siloxane RT-SAILs can form a vesicle spontaneously in aqueous solution, indicating potential uses as model systems for biomembranes and vehicles for drug delivery. PMID:26172585

  15. Efficient and green synthesis of tetrasubstituted pyrroles promoted by task-specific basic ionic liquids as catalyst in aqueous media.

    PubMed

    Yavari, Issa; Kowsari, Elaheh

    2009-11-01

    Synthesis of tetrasubstituted pyrroles by the three-component condensation reaction of acid chlorides, dialkyl acetylenedicarboxylates, and amino acids in the presence of various room-temperature ionic liquids (RTILs) as catalysts in water is reported. Among the ionic liquids used, the basic functionalized ionic liquid, butyl methyl imidazolium hydroxide [bmim]OH, was the most effective catalyst. The influence of reaction temperature, reaction time, and amount of ionic liquid on the reaction was investigated. The [bmim]OH/H(2)O catalyst system could be reused for at least five recycles without appreciable loss of efficiency. PMID:19381850

  16. Ion pairing in ionic liquids

    NASA Astrophysics Data System (ADS)

    Kirchner, Barbara; Malberg, Friedrich; Firaha, Dzmitry S.; Hollczki, Oldamur

    2015-11-01

    In the present article we briefly review the extensive discussion in literature about the presence or absence of ion pair-like aggregates in ionic liquids. While some experimental studies point towards the presence of neutral subunits in ionic liquids, many other experiments cannot confirm or even contradict their existence. Ion pairs can be detected directly in the gas phase, but no direct method is available to observe such association behavior in the liquid, and the corresponding indirect experimental proofs are based on such assumptions as unity charges at the ions. However, we have shown by calculating ionic liquid clusters of different sizes that assuming unity charges for ILs is erroneous, because a substantial charge transfer is taking place between the ionic liquid ions that reduce their total charge. Considering these effects might establish a bridge between the contradicting experimental results on this matter. Beside these results, according to molecular dynamics simulations the lifetimes of ionion contacts and their joint motions are far too short to verify the existence of neutral units in these materials.

  17. Ionic liquids and their solid-state analogues as materials for energy generation and storage

    NASA Astrophysics Data System (ADS)

    Macfarlane, Douglas R.; Forsyth, Maria; Howlett, Patrick C.; Kar, Mega; Passerini, Stefano; Pringle, Jennifer M.; Ohno, Hiroyuki; Watanabe, Masayoshi; Yan, Feng; Zheng, Wenjun; Zhang, Shiguo; Zhang, Jie

    2016-02-01

    Salts that are liquid at room temperature, now commonly called ionic liquids, have been known for more than 100 years; however, their unique properties have only come to light in the past two decades. In this Review, we examine recent work in which the properties of ionic liquids have enabled important advances to be made in sustainable energy generation and storage. We discuss the use of ionic liquids as media for synthesis of electromaterials, for example, in the preparation of doped carbons, conducting polymers and intercalation electrode materials. Focusing on their intrinsic ionic conductivity, we examine recent reports of ionic liquids used as electrolytes in emerging high-energy-density and low-cost batteries, including Li-ion, Li–O2, Li–S, Na-ion and Al-ion batteries. Similar developments in electrolyte applications in dye-sensitized solar cells, thermo-electrochemical cells, double-layer capacitors and CO2 reduction are also discussed.

  18. Hydrogen bonding in ionic liquids.

    PubMed

    Hunt, Patricia A; Ashworth, Claire R; Matthews, Richard P

    2015-03-01

    Ionic liquids (IL) and hydrogen bonding (H-bonding) are two diverse fields for which there is a developing recognition of significant overlap. Doubly ionic H-bonds occur when a H-bond forms between a cation and anion, and are a key feature of ILs. Doubly ionic H-bonds represent a wide area of H-bonding which has yet to be fully recognised, characterised or explored. H-bonds in ILs (both protic and aprotic) are bifurcated and chelating, and unlike many molecular liquids a significant variety of distinct H-bonds are formed between different types and numbers of donor and acceptor sites within a given IL. Traditional more neutral H-bonds can also be formed in functionalised ILs, adding a further level of complexity. Ab initio computed parameters; association energies, partial charges, density descriptors as encompassed by the QTAIM methodology (?BCP), qualitative molecular orbital theory and NBO analysis provide established and robust mechanisms for understanding and interpreting traditional neutral and ionic H-bonds. In this review the applicability and extension of these parameters to describe and quantify the doubly ionic H-bond has been explored. Estimating the H-bonding energy is difficult because at a fundamental level the H-bond and ionic interaction are coupled. The NBO and QTAIM methodologies, unlike the total energy, are local descriptors and therefore can be used to directly compare neutral, ionic and doubly ionic H-bonds. The charged nature of the ions influences the ionic characteristics of the H-bond and vice versa, in addition the close association of the ions leads to enhanced orbital overlap and covalent contributions. The charge on the ions raises the energy of the Ylp and lowers the energy of the X-H ?* NBOs resulting in greater charge transfer, strengthening the H-bond. Using this range of parameters and comparing doubly ionic H-bonds to more traditional neutral and ionic H-bonds it is clear that doubly ionic H-bonds cover the full range of weak through to very strong H-bonds. PMID:25582457

  19. Keggin-type polyoxometalate-based ionic liquid gels.

    PubMed

    Huang, Tianpei; Tian, Naiqin; Wu, Qingyin; Yan, Wenfu

    2015-06-14

    A series of reversible phase transformation ammonium- and phosphonium-based polyoxometalate ionic liquid (POM-IL) gels were synthesized and studied with a focus on the correlation between their physicochemical properties and their chemical structure. The products were successfully characterized by IR, UV, XRD and TG-DTA, and their ionic conductivities were measured. The Keggin-type heteropolyanion clusters decorated with long alkyl chains demonstrated a tendency to exhibit a gel state at room temperature, while all the gels transformed into liquids after heating and then recovered after cooling. With a decrease in the alkyl chain length, a significant improvement in the thermal stability and conductivity of the ammonium-based POM-IL gels can be achieved. Moreover, compared with the corresponding ammonium compound, phosphonium-based POM-IL gel was found to be more stable at high temperature and exhibited better conductivity. PMID:25947074

  20. Synthesis and characterization of 5-cyanotetrazolide-based ionic liquids.

    PubMed

    Bergholz, Timm; Oelkers, Benjamin; Huber, Benedikt; Roling, Bernhard; Sundermeyer, Jrg

    2015-02-01

    New salts based on imidazolium, pyrrolidinium, phosphonium, guanidinium, and ammonium cations together with the 5-cyanotetrazolide anion [C2 N5 ](-) are reported. Depending on the nature of cation-anion interactions, characterized by XRD, the ionic liquids (ILs) have a low viscosity and are liquid at room temperature or have higher melting temperatures. Thermogravimetric analysis, cyclic voltammetry, viscosimetry, and impedance spectroscopy display a thermal stability up to 230?C, an electrochemical window of 4.5?V, a viscosity of 25?mPa?s at 20?C, and an ionic conductivity of 5.4 mS cm(-1) at 20?C for the IL 1-butyl-1-methylpyrrolidinium 5-cyanotetrazolide [BMPyr][C2 N5 ]. On the basis of these results, the synthesized compounds are promising electrolytes for lithium-ion batteries. PMID:25504790

  1. Room-Temperature-Cured Copolymers for Lithium Battery Gel Electrolytes

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann B.; Tigelaar, Dean M.

    2009-01-01

    Polyimide-PEO copolymers (PEO signifies polyethylene oxide) that have branched rod-coil molecular structures and that can be cured into film form at room temperature have been invented for use as gel electrolytes for lithium-ion electric-power cells. These copolymers offer an alternative to previously patented branched rod-coil polyimides that have been considered for use as polymer electrolytes and that must be cured at a temperature of 200 C. In order to obtain sufficient conductivity for lithium ions in practical applications at and below room temperature, it is necessary to imbibe such a polymer with a suitable carbonate solvent or ionic liquid, but the high-temperature cure makes it impossible to incorporate and retain such a liquid within the polymer molecular framework. By eliminating the high-temperature cure, the present invention makes it possible to incorporate the required liquid.

  2. PEROXIDASE ACTIVITY IN IONIC LIQUIDS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Only a few enzymes have been examined in ionic liquids (ILs) to date. Initial results suggest that at least some enzymes tolerate ILs at least as well as conventional molecular solvents. Our work further explores the possibility that ILs provide a suitable (i.e., non-denaturing, non-inhibitory) en...

  3. Nanoparticle enhanced ionic liquid heat transfer fluids

    DOEpatents

    Fox, Elise B.; Visser, Ann E.; Bridges, Nicholas J.; Gray, Joshua R.; Garcia-Diaz, Brenda L.

    2014-08-12

    A heat transfer fluid created from nanoparticles that are dispersed into an ionic liquid is provided. Small volumes of nanoparticles are created from e.g., metals or metal oxides and/or alloys of such materials are dispersed into ionic liquids to create a heat transfer fluid. The nanoparticles can be dispersed directly into the ionic liquid during nanoparticle formation or the nanoparticles can be formed and then, in a subsequent step, dispersed into the ionic liquid using e.g., agitation.

  4. Synthesis of new solid polymer electrolyte and actuator based on PEDOT/NBR/ionic liquid

    NASA Astrophysics Data System (ADS)

    Cho, M. S.; Seo, H. J.; Nam, J. D.; Choi, H. R.; Koo, J. C.; Lee, Y.

    2006-03-01

    The conducting polymer actuator was presented. The solid polymer electrolyte based on nitrile rubber (NBR) activated with different ionic liquids was prepared. The three different grades of NBR films were synthesized by emulsion polymerization with different amount of acrylonitrile, 23, 35, and 40 mol. %, respectively. The effect of acrylonitrile content on the ionic conductivity and dielectric constant of solid polymer electrolytes was characterized. A conducting polymer, poly(3,4-ethylenedioxythiophene) (PEDOT), was synthesized on the surface of the NBR layer by using a chemical oxidation polymerization technique, and room temperature ionic liquids (RTIL) based on imidazolium salts, e.g. 1-butyl-3-methyl imidazolium X [where X= BF 4 -, PF 6 -, (CF 3SO II) IIN -], were absorbed into the composite film. The effects of the anion size of the ionic liquids on the displacement of the actuator were examined. The displacement increased with increasing the anion-size of the ionic liquids.

  5. Ambiphilic dual activation role of a task-specific ionic liquid: 2-hydroxyethylammonium formate as a recyclable promoter and medium for the green synthesis of ?-nitrostyrenes.

    PubMed

    Alizadeh, Abdolhamid; Khodaei, Mohammad M; Eshghi, Ali

    2010-12-01

    A cost-effective task-specific ionic liquid, 2-hydroxyethylammonium formate, efficiently promotes the condensation of nitroalkanes with various aldehydes to produce ?-nitrostyrenes in high to excellent yields at room temperature. This reaction does not involve any hazardous organic solvent and toxic catalyst. The ionic liquid is recovered and recycled for subsequent reactions. In addition, a novel mechanism has been proposed invoking ambiphilic dual activation influence of the ionic liquid. PMID:21047089

  6. Surface tension of ionic liquids and ionic liquid solutions.

    PubMed

    Tariq, Mohammad; Freire, Mara G; Saramago, Benilde; Coutinho, Joo A P; Lopes, Jos N Canongia; Rebelo, Lus Paulo N

    2012-01-21

    Some of the most active scientific research fronts of the past decade are centered on ionic liquids. These fluids present characteristic surface behavior and distinctive trends of their surface tension versus temperature. One way to explore and understand their unique nature is to study their surface properties. This critical review analyses most of the surface tension data reported between 2001 and 2010 (187 references). PMID:21811714

  7. Low Temperature Reduction of Alumina Using Fluorine Containing Ionic Liquids

    SciTech Connect

    Dr. Ramana Reddy

    2009-01-31

    EXECUTIVE SUMMARY The major objective of the project is to establish the feasibility of using specific ionic liquids capable of sustaining aluminum electrolysis near room temperature at laboratory and batch recirculation scales. It will explore new technologies for aluminum and other valuable metal extraction and process methods. The new technology will overcome many of the limitations associated with high temperatures processes such as high energy consumption and corrosion attack. Furthermore, ionic liquids are non-toxic and could be recycled after purification, thus minimizing extraction reagent losses and environmental pollutant emissions. Ionic liquids are mixture of inorganic and organic salts which are liquid at room temperature and have wide operational temperature range. During the last several years, they were emerging as novel electrolytes for extracting and refining of aluminum metals and/or alloys, which are otherwise impossible using aqueous media. The superior high temperature characteristics and high solvating capabilities of ionic liquids provide a unique solution to high temperature organic solvent problems associated with device internal pressure build-up, corrosion, and thermal stability. However their applications have not yet been fully implemented due to the insufficient understanding of the electrochemical mechanisms involved in processing of aluminum with ionic liquids. Laboratory aluminum electrodeposition in ionic liquids has been investigated in chloride and bis (trifluoromethylsulfonyl) imide based ionic liquids. The electrowinning process yielded current density in the range of 200-500 A/m2, and current efficiency of about 90%. The results indicated that high purity aluminum (>99.99%) can be obtained as cathodic deposits. Cyclic voltammetry and chronoamperometry studies have shown that initial stages of aluminum electrodeposition in ionic liquid electrolyte at 30C was found to be quasi-reversible, with the charge transfer coefficient ? = 0.40. Nucleation phenomena involved in aluminum deposition on copper in AlCl3-BMIMCl electrolyte was found to be instantaneous followed by diffusion controlled three-dimensional growth of nuclei. Diffusion coefficient (Do) of the electroactive species Al2Cl7 ion was in the range from 6.5 to 3.9107 cm2?s1 at a temperature of 30C. Relatively little research efforts have been made toward the fundamental understanding and modeling of the species transport and transformation information involved in ionic liquid mixtures, which eventually could lead to quantification of electrochemical properties. Except that experimental work in this aspect usually is time consuming and expensive, certain characteristics of ionic liquids also made barriers for such analyses. Low vapor pressure and high viscosity make them not suitable for atomic absorption spectroscopic measurement. In addition, aluminum electrodeposition in ionic liquid electrolytes are considered to be governed by multi-component mass, heat and charge transport in laminar and turbulent flows that are often multi-phase due to the gas evolution at the electrodes. The kinetics of the electrochemical reactions is in general complex. Furthermore, the mass transfer boundary layer is about one order of magnitude smaller than the thermal and hydrodynamic boundary layer (ReL?10,000). Other phenomena that frequently occur are side reactions and temperature or concentration driven natural convection. As a result of this complexity, quantitative knowledge of the local parameters (current densities, ion concentrations, electrical potential, temperature, etc.) is very difficult to obtain. This situation is a serious obstacle for improving the quality of products, efficiency of manufacturing and energy consumption. The gap between laboratory/batch scale processing with global process control and nanoscale deposit surface and materials specifications needs to be bridged. A breakthrough can only be realized if on each scale the occurring phenomena are understood and quantified. Multiscale numerical modelin

  8. Characterization of PVdF(HFP) gel electrolytes based on 1-(2-Hydroxyethyl)-3-methyl imidazolium ionic liquids.

    PubMed

    Yeon, Sun-Hwa; Kim, Ki-Sub; Choi, Sukjeong; Cha, Jong-Ho; Lee, Huen

    2005-09-29

    Poly(vinylidenefluoride)-hexafluoropropylene (PVdF(HFP))-ionic liquid gel electrolytes were prepared using ionic liquids based on 1-(2-hydroxyethyl)-3-methyl imidazolium tetrafluoroborate and 1-(2-hydroxyethyl)-3-methyl imidazolium hexafluorophosphate. A conventional metathesis reaction was used to prepare these ionic liquids, which have high purity and exhibit a liquid state at room temperature. The prepared polymer-ionic liquid gel proved to be a free-standing and rubbery film in which the degree of transparency differed according to the ratio and type of ionic liquid used. TGA and FTIR analyses confirmed that the solvent, N,N-Dimethylacetamide (DMAC), used for mixing PVdF(HFP) polymer with ionic liquid was almost totally removed during the gelling and drying processes. SEM photographs were taken of the surface structure of the PVdF(HFP)-ionic liquid gel in order to evaluate the morphology of the film's surface according to the mixing ratio and the nature of the ionic liquid. The thermal behaviors of PVdF(HFP)-ionic liquid gels were observed to be similar to those of neat ionic liquids through DSC analysis, and the compatibility between the polymer and ionic liquid was investigated by XRD analysis. The ionic conductivities of all the gels were 10(-3)-10(-5) S cm(-1) in a temperature range of 20-70 degrees C. PMID:16853301

  9. Static and dynamic wetting behaviour of ionic liquids.

    PubMed

    Delcheva, Iliana; Ralston, John; Beattie, David A; Krasowska, Marta

    2015-08-01

    Ionic liquids (ILs) are a unique family of molecular liquids ('molten salts') that consist of a combination of bulky organic cations coupled to inorganic or organic anions. The net result of steric hindrance and strong hydrogen bonding between components results in a material that is liquid at room temperature. One can alter the properties of ionic liquids through chemical modification of anion and cation, thus tailoring the IL for a given application. One such property that can be controlled or selected is the wettability of an IL on a particular solid substrate. However, the study of wetting of ionic liquids is complicated by the care required for accurate and reproducible measurement, due to both the susceptibility of the IL properties to water content, as well as to the sensitivity of wettability measurements to the state of the solid surface. This review deals with wetting studies of ILs to date, including both static and dynamic wetting, as well as issues concerning line tension and the formation of precursor and wetting films. PMID:25103860

  10. Chemistry of polynuclear transition-metal complexes in ionic liquids.

    PubMed

    Ahmed, Ejaz; Ruck, Michael

    2011-10-01

    Transition-metal chemistry in ionic liquids (IL) has achieved intrinsic fascination in the last few years. The use of an IL as environmental friendly solvent, offers many advantages over traditional materials synthesis methods. The change from molecular to ionic reaction media leads to new types of materials being accessible. Room-temperature IL have been found to be excellent media for stabilising transition-metal clusters in solution and to crystallise homo- and heteronuclear transition-metal complexes and clusters. Furthermore, the use of IL as solvent provides the option to replace high-temperature routes, such as crystallisation from the melt or gas-phase deposition, by convenient room- or low-temperature syntheses. Inorganic IL composed of alkali metal cations and polynuclear transition-metal cluster anions are also known. Each of these areas will be discussed briefly in this contribution. PMID:21743925

  11. Pressure and temperature effects on intermolecular vibrational dynamics of ionic liquids.

    PubMed

    Penna, Tatiana C; Faria, Luiz F O; Matos, Jivaldo R; Ribeiro, Mauro C C

    2013-03-14

    Low frequency Raman spectra of ionic liquids have been obtained as a function of pressure up to ca. 4.0 GPa at room temperature and as a function of temperature along the supercooled liquid and glassy state at atmospheric pressure. Intermolecular vibrations are observed at ~20, ~70, and ~100 cm(-1) at room temperature in ionic liquids based on 1-alkyl-3-methylimidazolium cations. The component at ~100 cm(-1) is assigned to librational motion of the imidazolium ring because it is absent in non-aromatic ionic liquids. There is a correspondence between the position of intermolecular vibrational modes in the normal liquid state and the spectral features that the Raman spectra exhibit after partial crystallization of samples at low temperatures or high pressures. The pressure-induced frequency shift of the librational mode is larger than the other two components that exhibit similar frequency shifts. The lowest frequency vibration observed in a glassy state corresponds to the boson peak observed in light and neutron scattering spectra of glass-formers. The frequency of the boson peak is not dependent on the length scale of polar?non-polar heterogeneity of ionic liquids, it depends instead on the strength of anion-cation interaction. As long as the boson peak is assigned to a mixing between localized modes and transverse acoustic excitations of high wavevectors, it is proposed that the other component observed in Raman spectra of ionic liquids has a partial character of longitudinal acoustic excitations. PMID:23514505

  12. Ionic Liquids in Biomass Processing

    NASA Astrophysics Data System (ADS)

    Tan, Suzie Su Yin; Macfarlane, Douglas R.

    Ionic liquids have been studied for their special solvent properties in a wide range of processes, including reactions involving carbohydrates such as cellulose and glucose. Biomass is a widely available and renewable resource that is likely to become an economically viable source of starting materials for chemical and fuel production, especially with the price of petroleum set to increase as supplies are diminished. Biopolymers such as cellulose, hemicellulose and lignin may be converted to useful products, either by direct functionalisation of the polymers or depolymerisation to monomers, followed by microbial or chemical conversion to useful chemicals. Major barriers to the effective conversion of biomass currently include the high crystallinity of cellulose, high reactivity of carbohydrates and lignin, insolubility of cellulose in conventional solvents, as well as heterogeneity in the native lignocellulosic materials and in lignin itself. This combination of factors often results in highly heterogeneous depolymerisation products, which make efficient separation difficult. Thus the extraction, depolymerisation and conversion of biopolymers will require novel reaction systems in order to be both economically attractive and environmentally benign. The solubility of biopolymers in ionic liquids is a major advantage of their use, allowing homogeneous reaction conditions, and this has stimulated a growing research effort in this field. This review examines current research involving the use of ionic liquids in biomass reactions, with perspectives on how it relates to green chemistry, economic viability, and conventional biomass processes.

  13. Application of Ionic Liquids in Hydrometallurgy

    PubMed Central

    Park, Jesik; Jung, Yeojin; Kusumah, Priyandi; Lee, Jinyoung; Kwon, Kyungjung; Lee, Churl Kyoung

    2014-01-01

    Ionic liquids, low temperature molten salts, have various advantages manifesting themselves as durable and environmentally friendly solvents. Their application is expanding into various fields including hydrometallurgy due to their unique properties such as non-volatility, inflammability, low toxicity, good ionic conductivity, and wide electrochemical potential window. This paper reviews previous literatures and our recent results adopting ionic liquids in extraction, synthesis and processing of metals with an emphasis on the electrolysis of active/light, rare earth, and platinum group metals. Because the research and development of ionic liquids in this area are still emerging, various, more fundamental approaches are expected to popularize ionic liquids in the metal manufacturing industry. PMID:25177864

  14. Application of ionic liquids in hydrometallurgy.

    PubMed

    Park, Jesik; Jung, Yeojin; Kusumah, Priyandi; Lee, Jinyoung; Kwon, Kyungjung; Lee, Churl Kyoung

    2014-01-01

    Ionic liquids, low temperature molten salts, have various advantages manifesting themselves as durable and environmentally friendly solvents. Their application is expanding into various fields including hydrometallurgy due to their unique properties such as non-volatility, inflammability, low toxicity, good ionic conductivity, and wide electrochemical potential window. This paper reviews previous literatures and our recent results adopting ionic liquids in extraction, synthesis and processing of metals with an emphasis on the electrolysis of active/light, rare earth, and platinum group metals. Because the research and development of ionic liquids in this area are still emerging, various, more fundamental approaches are expected to popularize ionic liquids in the metal manufacturing industry. PMID:25177864

  15. Radiation Chemistry and Photochemistry of Ionic Liquids

    SciTech Connect

    Wishart, J.F.; Takahaski, K.

    2010-12-01

    As our understanding of ionic liquids and their tunable properties has grown, it is possible to see many opportunities for ionic liquids to contribute to the sustainable use of energy. The potential safety and environmental benefits of ionic liquids, as compared to conventional solvents, have attracted interest in their use as processing media for the nuclear fuel cycle. Therefore, an understanding of the interactions of ionizing radiation and photons with ionic liquids is strongly needed. However, the radiation chemistry of ionic liquids is still a relatively unexplored topic although there has been a significant increase in the number of researchers in the field recently. This article provides a brief introduction to ionic liquids and their interesting properties, and recent advances in the radiation chemistry and photochemistry of ionic liquids. In this article, we will mainly focus on excess electron dynamics and radical reaction dynamics. Because solvation dynamics processes in ionic liquids are much slower than in molecular solvents, one of the distinguishing characteristics is that pre-solvated electrons play an important role in ionic liquid radiolysis. It will be also shown that the reaction dynamics of radical ions is significantly different from that observed in molecular solvents because of the Coulombic screening effects and electrostatic interactions in ionic liquids.

  16. Thermoelectric Potential of Polymer-Scaffolded Ionic Liquid Membranes

    NASA Astrophysics Data System (ADS)

    Datta, R. S.; Said, S. M.; Sahamir, S. R.; Karim, M. R.; Sabri, M. F. M.; Nakajo, T.; Kubouchi, M.; Hayashi, K.; Miyazaki, Y.

    2014-06-01

    Organic thin films have been viewed as potential thermoelectric (TE) materials, given their ease of fabrication, flexibility, cost effectiveness, and low thermal conductivity. However, their intrinsically low electrical conductivity is a main drawback which results in a relatively lower TE figure of merit for polymer-based TE materials than for inorganic materials. In this paper, a technique to enhance the ion transport properties of polymers through the introduction of ionic liquids is presented. The polymer is in the form of a nanofiber scaffold produced using the electrospinning technique. These fibers were then soaked in different ionic liquids based on substituted imidazolium such as 1-ethyl-3-methylimidazolium chloride or 1-butyl-3-methylimidazolium bromide. This method was applied to electrospun polyacrylonitrile and a mixture of polyvinyl alcohol and chitosan polymers. The ion transport properties of the membranes have been observed to increase with increasing concentration of ionic liquid, with maximum electrical conductivity of 1.20 × 10-1 S/cm measured at room temperature. Interestingly, the maximum electrical conductivity value surpassed the value of pure ionic liquids. These results indicate that it is possible to significantly improve the electrical conductivity of a polymer membrane through a simple and cost-effective method. This may in turn boost the TE figures of merit of polymer materials, which are well known to be considerably lower than those of inorganic materials. Results in terms of the Seebeck coefficient of the membranes are also presented in this paper to provide an overall representation of the TE potential of the polymer-scaffolded ionic liquid membranes.

  17. COMPARISON OF PEROXIDASE ACTIVITIES OF HEMIN, CYTOCHROME C AND MICROPEROXIDASE-11 IN MOLECULAR SOLVENTS AND IMIDAZOLIUM-BASED IONIC LIQUIDS

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The ability of ferriprotoporphyrin(IX) chloride (hemin), microperoxidase-11 (MP-11), and cytochrome c (cyt-c) to oxidize guaiacol (2-methoxyphenol) was examined in the room-temperature ionic liquids (IL) 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide and the hexafluorophosphates of 1-...

  18. Exploring field effects on ionic liquid boundary lubrication

    NASA Astrophysics Data System (ADS)

    Capozza, Rosario; Benassi, Andrea; Vanossi, Andrea; Tosatti, Erio

    2014-03-01

    Ionic liquids, organic salts that are liquid at room temperature, are of great physical as well as of technological interest. Their adhesion properties to solid surfaces under pressure suggests their use as boundary lubricants. One potentially interesting feature would be the possibility that electrical charging of the solid plates or more generally an applied static or dynamic electric field could modify the nearby perpendicular and parallel ordering of ions, and in turn also modify the sliding friction. While these effects have just begun to be pursued by experimental groups, we have undertaken molecular dynamics simulations aimed at exploring some of these questions. Preliminary results obtained using very simple molten salt boundary lubrication models will be presented and discussed. Partly sponsored by SNSF Project CRSII2 136287/1, and by ERC Grant N. 320796 MODPHYSFRICT.

  19. Ionic liquid enabled FeS2 for high-energy-density lithium-ion batteries.

    PubMed

    Evans, Tyler; Piper, Daniela Molina; Kim, Seul Cham; Han, Sang Sub; Bhat, Vinay; Oh, Kyu Hwan; Lee, Se-Hee

    2014-11-19

    High-energy-density FeS2 cathodes en-abled by a bis(trifluoromethanesulfonyl)imide (TFSI-) anion-based room temperature ionic liquid (RTIL) electrolyte are demonstrated. A TFSI-based ionic liquid (IL) significantly mitigates polysulfide dissolution, and therefore the parasitic redox shuttle mechanism, that plagues sulfur-based electrode chemistries. FeS2 stabilization with a TFSI(-) -based IL results in one of the highest energy density cathodes, 542 W h kg(-1) (normalized to cathode composite mass), reported to date. PMID:25236752

  20. Early Events in Ionic Liquid Radiation Chemistry

    SciTech Connect

    Wishart, J.F.; Cook, A.; Rimmer, R.D.; Gohdo, M.

    2010-09-14

    Ionic liquids are interesting and useful materials whose solvation time scales are up to thousands of times longer than in conventional solvents. The extended lifetimes of pre-solvated electrons and other energetic species in ionic liquids has profound consequences for the radiolytic product distributions and reactivity patterns. We use a newly developed, multiplexed variation of pulse-probe spectroscopy to measure the kinetics of the early dynamical and reactive events in ionic liquids.

  1. Surface orientation in ionic liquids

    NASA Astrophysics Data System (ADS)

    Law, George; Watson, Philip R.

    2001-09-01

    New surface tension data supports models of surface orientations previously derived from direct recoil spectrometry (DRS) data for the cations of 1-alkyl-3-methylimidazolium ionic liquids. For shorter-chain hexafluorophosphate compounds the favored average orientation appears to be one where the cation is oriented vertically with the N atoms uppermost, but the alkyl substituents do not protrude out of the surface. For longer chains or for compounds containing the smaller tetrafluoroborate anion the surface tension and DRS data are consistent with a shift to an average orientation embodying a rotation that moves the methyl group towards the surface.

  2. A roadmap to uranium ionic liquids: Anti-crystal engineering

    DOE PAGESBeta

    Yaprak, Damla; Spielberg, Eike T.; Bäcker, Tobias; Richter, Mark; Mallick, Bert; Klein, Axel; Mudring, Anja -Verena

    2014-04-15

    In the search for uranium-based ionic liquids, tris(N,N-dialkyldithiocarbamato)uranylates have been synthesized as salts of the 1-butyl-3-methylimidazolium (C4mim) cation. As dithiocarbamate ligands binding to the UO22+ unit, tetra-, penta-, hexa-, and heptamethylenedithiocarbamates, N,N-diethyldithiocarbamate, N-methyl-N-propyldithiocarbamate, N-ethyl-N-propyldithiocarbamate, and N-methyl-N-butyldithiocarbamate have been explored. X-ray single-crystal diffraction allowed unambiguous structural characterization of all compounds except N-methyl-N-butyldithiocarbamate, which is obtained as a glassy material only. In addition, powder X-ray diffraction as well as vibrational and UV/Vis spectroscopy, supported by computational methods, were used to characterize the products. Differential scanning calorimetry was employed to investigate the phase-transition behavior depending on the N,N-dialkyldithiocarbamato ligand with the aim tomore » establish structure–property relationships regarding the ionic liquid formation capability. Compounds with the least symmetric N,N-dialkyldithiocarbamato ligand and hence the least symmetric anions, tris(N-methyl-N-propyldithiocarbamato)uranylate, tris(N-ethyl-N-propyldithiocarbamato)uranylate, and tris(N-methyl-N-butyldithiocarbamato)uranylate, lead to the formation of (room-temperature) ionic liquids, which confirms that low-symmetry ions are indeed suitable to suppress crystallization. As a result, these materials combine low melting points, stable complex formation, and hydrophobicity and are therefore excellent candidates for nuclear fuel purification and recovery.« less

  3. A roadmap to uranium ionic liquids: Anti-crystal engineering

    SciTech Connect

    Yaprak, Damla; Spielberg, Eike T.; Bäcker, Tobias; Richter, Mark; Mallick, Bert; Klein, Axel; Mudring, Anja -Verena

    2014-04-15

    In the search for uranium-based ionic liquids, tris(N,N-dialkyldithiocarbamato)uranylates have been synthesized as salts of the 1-butyl-3-methylimidazolium (C4mim) cation. As dithiocarbamate ligands binding to the UO22+ unit, tetra-, penta-, hexa-, and heptamethylenedithiocarbamates, N,N-diethyldithiocarbamate, N-methyl-N-propyldithiocarbamate, N-ethyl-N-propyldithiocarbamate, and N-methyl-N-butyldithiocarbamate have been explored. X-ray single-crystal diffraction allowed unambiguous structural characterization of all compounds except N-methyl-N-butyldithiocarbamate, which is obtained as a glassy material only. In addition, powder X-ray diffraction as well as vibrational and UV/Vis spectroscopy, supported by computational methods, were used to characterize the products. Differential scanning calorimetry was employed to investigate the phase-transition behavior depending on the N,N-dialkyldithiocarbamato ligand with the aim to establish structure–property relationships regarding the ionic liquid formation capability. Compounds with the least symmetric N,N-dialkyldithiocarbamato ligand and hence the least symmetric anions, tris(N-methyl-N-propyldithiocarbamato)uranylate, tris(N-ethyl-N-propyldithiocarbamato)uranylate, and tris(N-methyl-N-butyldithiocarbamato)uranylate, lead to the formation of (room-temperature) ionic liquids, which confirms that low-symmetry ions are indeed suitable to suppress crystallization. As a result, these materials combine low melting points, stable complex formation, and hydrophobicity and are therefore excellent candidates for nuclear fuel purification and recovery.

  4. Membrane separation of ionic liquid solutions

    DOEpatents

    Campos, Daniel; Feiring, Andrew Edward; Majumdar, Sudipto; Nemser, Stuart

    2015-09-01

    A membrane separation process using a highly fluorinated polymer membrane that selectively permeates water of an aqueous ionic liquid solution to provide dry ionic liquid. Preferably the polymer is a polymer that includes polymerized perfluoro-2,2-dimethyl-1,3-dioxole (PDD). The process is also capable of removing small molecular compounds such as organic solvents that can be present in the solution. This membrane separation process is suitable for drying the aqueous ionic liquid byproduct from precipitating solutions of biomass dissolved in ionic liquid, and is thus instrumental to providing usable lignocellulosic products for energy consumption and other industrial uses in an environmentally benign manner.

  5. Electronic functions of solid-to-liquid interfaces of organic semiconductor crystals and ionic liquid

    NASA Astrophysics Data System (ADS)

    Takeya, J.

    2008-10-01

    The environment of surface electrons at 'solid-to-liquid' interfaces is somewhat extreme, subjected to intense local electric fields or harsh chemical pressures that high-density ionic charge or polarization of mobile molecules create. In this proceedings, we argue functions of electronic carriers generated at the surface of organic semiconductor crystals in response to the local electric fields in the very vicinity of the interface to ionic liquid. The ionic liquids (ILs), or room temperature molten salts, are gaining considerable interest in the recent decade at the prospect of nonvolatile 'green solvents', with the development of chemically stable and nontoxic compounds. Moreover, such materials are also applied to electrolytes for lithium ion batteries and electric double-layer (EDL) capacitors. Our present solid-to-liquid interfaces of rubrene single crystals and ionic liquids work as fast-switching organic field-effect transistors (OFETs) with the highest transconductance, i.e. the most efficient response of the output current to the input voltage, among the OFETs ever built.

  6. Green synthesis of dipyrromethanes in aqueous media catalyzed by SO3H-functionalized ionic liquid.

    PubMed

    Senapak, W; Saeeng, R; Jaratjaroonphong, J; Kasemsuk, T; Sirion, U

    2016-01-28

    A mild, efficient and metal-free method was described for the green synthesis of dipyrromethanes from aldehydes and unsubstituted pyrrole catalyzed by SO3H-functionalized ionic liquids (SO3H-ILs) in aqueous media at room temperature. Notably, SO3H-ILs, 1-butylsulfonic-3-methylimidazolium hydrogen sulfate ([bsmim][HSO4]) was the most efficient catalyst for moderate to good yields of the corresponding desired products. PMID:26658884

  7. Ion field-evaporation from ionic liquids infusing carbon xerogel microtips

    NASA Astrophysics Data System (ADS)

    Perez-Martinez, C. S.; Lozano, P. C.

    2015-07-01

    Ionic liquid ion sources capable of producing positive and negative molecular ion beams from room-temperature molten salts have applications in diverse fields, from materials science to space propulsion. The electrostatic stressing of these ionic liquids places the liquid surfaces in a delicate balance that could yield unwanted droplet emission when not properly controlled. Micro-tip emitter configurations are required to guarantee that these sources will operate in a pure ionic regime with no additional droplets. Porous carbon based on resorcinol-formaldehyde xerogels is introduced as an emitter substrate. It is demonstrated that this material can be shaped to the required micron-sized geometry and has appropriate transport properties to favor pure ionic emission. Time-of-flight mass spectrometry is used to verify that charged particle beams contain solvated ions exclusively.

  8. Polymer Crystallization-Driven Gelation of an Ionic Liquid

    NASA Astrophysics Data System (ADS)

    Hoagland, David; Harner, John

    2008-03-01

    Polyethylene glycol dissolves in the room temperature ionic liquid 1-ethyl-3-methylimidiazolium ethyl sulfate [EMIM][EtSO4] when heated above about 60C, the neat polymer's melting temperature. At typical polymer molecular weight and concentration, the homogeneous, slightly viscous solution solidifies during subsequent cooling, forming a semitransparent gel. For example, a 5 wt. percent solution of 6000 MW polymer produces a gel with modulus exceeding 1 KPa at 45C; cooled further to room temperature, the gel's modulus rises to a temperature-insensitive plateau of over 100 KPa. By DSC, rheology, and optical microscopy, gelation of the liquid is traced to kinetically frustrated polymer crystallization, a phenomenon previously reported for many pairings of crystallizable polymer and traditional solvent. Polarized optical microscopy reveals nucleation and growth of fibrillar polymer crystals during cooling, and these crystals, here with largest dimenions of tens to hundreds of microns, act as junction points. Melting is at a temperature higher than for gelation. Surprisingly, gelation can occur even when the starting polymer concentration is an order of magnitude below coil overlap. [EMIM][EtSO4] is hygroscopic, and with water uptake, the modulus drops.

  9. Solvation and rotational dynamics of coumarin 153 in ionic liquids: comparisons to conventional solvents.

    PubMed

    Jin, Hui; Baker, Gary A; Arzhantsev, Sergei; Dong, Jing; Maroncelli, Mark

    2007-06-28

    Steady-state and time-resolved emission spectroscopy with 25 ps resolution are used to measure equilibrium and dynamic aspects of the solvation of coumarin 153 (C153) in a diverse collection of 21 room-temperature ionic liquids. The ionic liquids studied here include several phosphonium and imidazolium liquids previously reported as well as 12 new ionic liquids that incorporate two homologous series of ammonium and pyrrolidinium cations. Steady-state absorption and emission spectra are used to extract solvation free energies and reorganization energies associated with the S0 <--> S1 transition of C153. These quantities, especially the solvation free energy, vary relatively little in ionic liquids compared to conventional solvents. Some correlation is found between these quantities and the mean separation between ions (or molar volume). Time-resolved anisotropies are used to observe solute rotation. Rotation times measured in ionic liquids correlate with solvent viscosity in much the same way that they do in conventional polar solvents. No special frictional coupling between the C153 and the ionic liquid solvents is indicated by these times. But, in contrast to what is observed in most low-viscosity conventional solvents, rotational correlation functions in ionic liquids are nonexponential. Time-resolved Stokes shift measurements are used to characterize solvation dynamics. The solvation response functions in ionic liquids are also nonexponential and can be reasonably represented by stretched-exponential functions of time. The solvation times observed are correlated with the solvent viscosity, and the much slower solvation in ionic liquids compared to dipolar solvents can be attributed to their much larger viscosities. Solvation times of the majority of ionic liquids studied appear to follow a single correlation with solvent viscosity. Only liquids incorporating the largest phosphonium cation appear to follow a distinctly different correlation. PMID:17530885

  10. Partition coefficients of organic compounds between water and imidazolium-, pyridinium-, and phosphonium-based ionic liquids.

    PubMed

    Padr, Juan M; Pellegrino Vidal, Roco B; Reta, Mario

    2014-12-01

    The partition coefficients, P IL/w, of several compounds, some of them of biological and pharmacological interest, between water and room-temperature ionic liquids based on the imidazolium, pyridinium, and phosphonium cations, namely 1-octyl-3-methylimidazolium hexafluorophosphate, N-octylpyridinium tetrafluorophosphate, trihexyl(tetradecyl)phosphonium chloride, trihexyl(tetradecyl)phosphonium bromide, trihexyl(tetradecyl)phosphonium bis(trifluoromethylsulfonyl)imide, and trihexyl(tetradecyl)phosphonium dicyanamide, were accurately measured. In this way, we extended our database of partition coefficients in room-temperature ionic liquids previously reported. We employed the solvation parameter model with different probe molecules (the training set) to elucidate the chemical interactions involved in the partition process and discussed the most relevant differences among the three types of ionic liquids. The multiparametric equations obtained with the aforementioned model were used to predict the partition coefficients for compounds (the test set) not present in the training set, most being of biological and pharmacological interest. An excellent agreement between calculated and experimental log P IL/w values was obtained. Thus, the obtained equations can be used to predict, a priori, the extraction efficiency for any compound using these ionic liquids as extraction solvents in liquid-liquid extractions. PMID:25326892

  11. Vertical alignment of liquid crystal through ion beam exposure on oxygen-doped SiC films deposited at room temperature

    SciTech Connect

    Son, Phil Kook; Park, Jeung Hun; Kim, Jae Chang; Yoon, Tae-Hoon; Rho, Soon Joon; Jeon, Back Kyun; Shin, Sung Tae; Kim, Jang Sub; Lim, Soon Kwon

    2007-09-03

    The authors report the vertical alignment of liquid crystal (LC) through the ion beam exposure on amorphous oxygen-doped SiC (SiOC) film surfaces deposited at room temperature. The optical transmittance of these films was similar to that of polyimide layers, but much higher than that of SiO{sub x} films. The light leakage of a LC cell aligned vertically on SiOC films was much lower than those of a LC cell aligned on polyimide layers or other inorganic films. They found that LC molecules align vertically on ion beam treated SiOC film when the roughness of the electrostatic force microscopy (EFM) data is high on the SiOC film surface, while they align homogeneously when the roughness of the EFM data is low.

  12. Ionic liquids screening for desulfurization of natural gasoline by liquid-liquid extraction.

    PubMed

    Likhanova, Natalya V; Guzmn-Lucero, Diego; Flores, Eugenio A; Garca, Paloma; Domnguez-Aguilar, Marco A; Palomeque, Jorge; Martnez-Palou, Rafael

    2010-11-01

    Seventy five ionic liquids (ILs) were tested as a sequestering agent of sulfured compounds in natural gasoline (NG). Desulphurization of NG was performed by means of liquid-liquid extraction method at room temperature and atmospheric pressure. Experimental ILs containing imidazolium, pyridinium, and ammonium cations along with organic and inorganic anions were synthesized conventionally and under microwave and sonochemical conditions. The effect of the molecular structure of ILs on the desulfurization efficiency of NG with high sulfur content was evaluated. Analysis indicated that the anion type played a more important role than the cation on the desulphurization process. ILs based on halogen-ferrates and halogen-aluminates exhibited the highest efficiency in sulfur removal, and their efficiency is further improved when there is an excess of metallic salt in a ratio of at least 1:1.3 during the synthesis of the corresponding IL. An explanation for the ability of metallic ILs to remove sulfur-containing compounds from natural gasoline based on the ratio of the ionic charge to the atomic radius is proposed. Furthermore, a method to recover and reuse water-sensitive to halogenated precursors is described. PMID:20091120

  13. Room-temperature single-photon sources with definite circular and linear polarizations based on single-emitter fluorescence in liquid crystal hosts

    NASA Astrophysics Data System (ADS)

    Winkler, Justin M.; Lukishova, Svetlana G.; Bissell, Luke J.

    2013-02-01

    Definite circular and linear polarizations of room-temperature single-photon sources, which can serve as polarization bases for quantum key distribution, are produced by doping planar-aligned liquid crystal hosts with single fluorescence emitters. Chiral 1-D photonic bandgap microcavities for a single handedness of circularly polarized light were prepared from both monomeric and oligomeric cholesteric liquid crystals. Fluorescent emitters, such as nanocrystal quantum dots, nitrogen vacancy color centers in nanodiamonds, and rare-earth ions in nanocrystals, were doped into these microcavity structures and used to produce circularly polarized fluorescence of definite handedness. Additionally, we observed circularly polarized resonances in the spectrum of nanocrystal quantum dot fluorescence at the edge of the cholesteric microcavity's photonic stopband. For this polarization we obtained a ~4.9 enhancement of intensity compared to the polarization of the opposite handedness that propagates without photonic bandgap microcavity effects. Such a resonance is indicative of coupling of quantum dot fluorescence to the cholesteric microcavity mode. We have also used planar-aligned nematic liquid crystal hosts to align DiI dye molecules doped into the host, thereby providing a single-photon source of linear polarization of definite direction. Antibunching is demonstrated for fluorescence of nanocrystal quantum dots, nitrogen vacancy color centers, and dye molecules in these liquid crystal structures.

  14. Engineered microorganisms having resistance to ionic liquids

    DOEpatents

    Ruegg, Thomas Lawrence; Thelen, Michael P.

    2016-03-22

    The present invention provides for a method of genetically modifying microorganisms to enhance resistance to ionic liquids, host cells genetically modified in accordance with the methods, and methods of using the host cells in a reaction comprising biomass that has been pretreated with ionic liquids.

  15. Liquid metal alloy ion source based metal ion injection into a room-temperature electron beam ion sourcea)

    NASA Astrophysics Data System (ADS)

    Thorn, A.; Ritter, E.; Ullmann, F.; Pilz, W.; Bischoff, L.; Zschornack, G.

    2012-02-01

    We have carried out a series of measurements demonstrating the feasibility of using the Dresden electron beam ion source (EBIS)-A, a table-top sized, permanent magnet technology based electron beam ion source, as a charge breeder. Low charged gold ions from an AuGe liquid metal alloy ion source were injected into the EBIS and re-extracted as highly charged ions, thereby producing charge states as high as Au60 +. The setup, the charge breeding technique, breeding efficiencies as well as acceptance and emittance studies are presented.

  16. Liquid metal alloy ion source based metal ion injection into a room-temperature electron beam ion source

    SciTech Connect

    Thorn, A.; Ritter, E.; Zschornack, G.; Ullmann, F.; Pilz, W.; Bischoff, L.

    2012-02-15

    We have carried out a series of measurements demonstrating the feasibility of using the Dresden electron beam ion source (EBIS)-A, a table-top sized, permanent magnet technology based electron beam ion source, as a charge breeder. Low charged gold ions from an AuGe liquid metal alloy ion source were injected into the EBIS and re-extracted as highly charged ions, thereby producing charge states as high as Au{sup 60+}. The setup, the charge breeding technique, breeding efficiencies as well as acceptance and emittance studies are presented.

  17. New frontiers in materials science opened by ionic liquids.

    PubMed

    Torimoto, Tsukasa; Tsuda, Tetsuya; Okazaki, Ken-ichi; Kuwabata, Susumu

    2010-03-19

    Ionic liquids (ILs) including ambient-temperature molten salts, which exist in the liquid state even at room temperature, have a long research history. However, their applications were once limited because ILs were considered as highly moisture-sensitive solvents that should be handled in a glove box. After the first synthesis of moisture-stable ILs in 1992, their unique physicochemical properties became known in all scientific fields. ILs are composed solely of ions and exhibit several specific liquid-like properties, e.g., some ILs enable dissolution of insoluble bio-related materials and the use as tailor-made lubricants in industrial applications under extreme physicochemical conditions. Hybridization of ILs and other materials provides quasi-solid materials, which can be used to fabricate highly functional devices. ILs are also used as reaction media for electrochemical and chemical synthesis of nanomaterials. In addition, the negligible vapor pressure of ILs allows the fabrication of electrochemical devices that are operated under ambient conditions, and many liquid-vacuum technologies, such as X-ray photoelectron spectroscopy (XPS) analysis of liquids, electron microscopy of liquids, and sputtering and physical vapor deposition onto liquids. In this article, we review recent studies on ILs that are employed as functional advanced materials, advanced mediums for materials production, and components for preparing highly functional materials. PMID:20437507

  18. Effect of Embedded Pd Microstructures on the Flat-Band-Voltage Operation of Room Temperature ZnO-Based Liquid Petroleum Gas Sensors

    PubMed Central

    Ali, Ghusoon M.; Thompson, Cody V.; Jasim, Ali K.; Abdulbaqi, Isam M.; Moore, James C.

    2013-01-01

    Three methods were used to fabricate ZnO-based room temperature liquid petroleum gas (LPG) sensors having interdigitated metal-semiconductor-metal (MSM) structures. Specifically, devices with Pd Schottky contacts were fabricated with: (1) un-doped ZnO active layers; (2) Pd-doped ZnO active layers; and (3) un-doped ZnO layers on top of Pd microstructure arrays. All ZnO films were grown on p-type Si(111) substrates by the sol-gel method. For devices incorporating a microstructure array, Pd islands were first grown on the substrate by thermal evaporation using a 100 ?m mesh shadow mask. We have estimated the sensitivity of the sensors for applied voltage from 5 to 5 V in air ambient, as well as with exposure to LPG in concentrations from 500 to 3,500 ppm at room temperature (300 K). The current-voltage characteristics were studied and parameters such as leakage current, barrier height, reach-through voltage, and flat-band voltage were extracted. We include contributions due to the barrier height dependence on the electric field and tunneling through the barrier for the studied MSM devices. The Pd-enhanced devices demonstrated a maximum gas response at flat-band voltages. The study also revealed that active layers consisting of Pd microstructure embedded ZnO films resulted in devices exhibiting greater gas-response as compared to those using Pd-doped ZnO thin films or un-doped active layers.

  19. Liquid crystal self-assembly of halloysite nanotubes in ionic liquids: a novel soft nanocomposite ionogel electrolyte with high anisotropic ionic conductivity and thermal stability.

    PubMed

    Zhao, Ningning; Liu, Yulin; Zhao, Xiaomeng; Song, Hongzan

    2016-01-01

    We report a novel class of liquid crystalline (LC) nanohybrid ionogels fabricated via self-assembly of natural halloysite nanotubes (HNTs) in ionic liquids (ILs). The obtained ionogels are very stable and nonvolatile and show LC phases over a wide temperature range. Remarkably, the nanocomposite ionogels exhibit high anisotropic ionic conductivity after shear, and their room temperature ionic conductivity can reach 3.8 10(-3) S cm(-1) for aligned nanotubes perpendicular to the electrode even when the HNTs content increases to 40 wt%, which is 380 times higher than that obtained for aligned nanotubes parallel to the electrode, which is 1.0 10(-5) S cm(-1). Crucially, the obtained LC nanocomposite ionogels have very high thermal stability, which can sustain 400 C thermal treatment. The findings will promote the development of novel nanocomposite ionogel electrolytes with faster ion transport and larger anisotropic conductivity. PMID:26681209

  20. Electrocapillary Curves for the Hg/Ionic Liquid Interface

    NASA Astrophysics Data System (ADS)

    Lewandowski, Andrzej; Majkowski, Tomasz; Galinski, Maciej

    2009-04-01

    Electrocapillary curves (surface tension ? as a function of the electrode potential E) for a series of room-temperature ionic liquids (RTILs) were measured using a mercury dropping electrode with the drop-weight (drop-volume) technique. The curves ? = f (E) for the Hg/RTIL interface have one maximum and may be approximated with a polynomial of sixth-order. There are no `humps' in the curves. The interfacial tension of the Hg/RTIL system changes with potential E in a monotonic way. The second derivative of ? = f (E) leads to a polynomial of fourth order, indicating the capacitance of the Hg/RTIL interface. The potential of zero charge is within a relatively narrow range. The specific capacitance at the minimum is of the order 10 ?F/cm2

  1. Actinide chemistry in ionic liquids.

    PubMed

    Takao, Koichiro; Bell, Thomas James; Ikeda, Yasuhisa

    2013-04-01

    This Forum Article provides an overview of the reported studies on the actinide chemistry in ionic liquids (ILs) with a particular focus on several fundamental chemical aspects: (i) complex formation, (ii) electrochemistry, and (iii) extraction behavior. The majority of investigations have been dedicated to uranium, especially for the 6+ oxidation state (UO2(2+)), because the chemistry of uranium in ordinary solvents has been well investigated and uranium is the most abundant element in the actual nuclear fuel cycles. Other actinides such as thorium, neptunium, plutonium, americium, and curiumm, although less studied, are also of importance in fully understanding the nuclear fuel engineering process and the safe geological disposal of radioactive wastes. PMID:22873132

  2. Lipid Biomembrane in Ionic Liquids

    NASA Astrophysics Data System (ADS)

    Yoo, Brian; Jing, Benxin; Shah, Jindal; Maginn, Ed; Zhu, Y. Elaine; Department of Chemical and Biomolecular Engineering Team

    2014-03-01

    Ionic liquids (ILs) have been recently explored as new ``green'' chemicals in several chemical and biomedical processes. In our pursuit of understanding their toxicities towards aquatic and terrestrial organisms, we have examined the IL interaction with lipid bilayers as model cell membranes. Experimentally by fluorescence microscopy, we have directly observed the disruption of lipid bilayer by added ILs. Depending on the concentration, alkyl chain length, and anion hydrophobicity of ILs, the interaction of ILs with lipid bilayers leads to the formation of micelles, fibrils, and multi-lamellar vesicles for IL-lipid complexes. By MD computer simulations, we have confirmed the insertion of ILs into lipid bilayers to modify the spatial organization of lipids in the membrane. The combined experimental and simulation results correlate well with the bioassay results of IL-induced suppression in bacteria growth, thereby suggesting a possible mechanism behind the IL toxicity. National Science Foundation, Center for Research Computing at Notre Dame.

  3. Silver halide fiber-based evanescent-wave liquid droplet sensing with room temperature mid-infrared quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Chen, J. Z.; Liu, Z.; Gmachl, C. F.; Sivco, D. L.

    2005-08-01

    Quantum cascade lasers and unclad silver halide fibers were used to assemble mid-infrared fiber-optics evanescent-wave sensors suitable to measure the chemical composition of liquid droplets. The laser wavelengths were chosen to be in the regions which offer the largest absorption contrast between constituents inside the mixture droplets. A pseudo-Beer-Lambert law fits well with the experimental data. Using a 300μm diameter fiber with a 25 mm immersion length, the signal to noise ratios correspond to 1 vol.% for α-tocophenol in squalane and 2 vol.% for acetone in aqueous solution for laser wavenumbers of 1208 cm-1 and 1363 cm-1, respectively.

  4. Crosslinked polymer gel electrolytes based on polyethylene glycol methacrylate and ionic liquid for lithium battery applications

    SciTech Connect

    Liao, Chen; Sun, Xiao-Guang; Dai, Sheng

    2013-01-01

    Gel polymer electrolytes were synthesized by copolymerization polyethylene glycol methyl ether methacrylate with polyethylene glycol dimethacrylate in the presence of a room temperature ionic liquid, methylpropylpyrrolidinium bis(trifluoromethanesulfonyl)imide (MPPY TFSI). The physical properties of gel polymer electrolytes were characterized by thermal analysis, impedance spectroscopy, and electrochemical tests. The ionic conductivities of the gel polymer electrolytes increased linearly with the amount of MPPY TFSI and were mainly attributed to the increased ion mobility as evidenced by the decreased glass transition temperatures. Li||LiFePO4 cells were assembled using the gel polymer electrolytes containing 80 wt% MPPY TFSI via an in situ polymerization method. A reversible cell capacity of 90 mAh g 1 was maintained under the current density of C/10 at room temperature, which was increased to 130 mAh g 1 by using a thinner membrane and cycling at 50 C.

  5. Liquid-liquid equilibrium of cholinium-derived bistriflimide ionic liquids with water and octanol.

    PubMed

    Costa, Anabela J L; Soromenho, Mrio R C; Shimizu, Karina; Marrucho, Isabel M; Esperana, Jos M S S; Canongia Lopes, J N; Rebelo, Lus Paulo N

    2012-08-01

    The liquid-liquid equilibria of mixtures of cholinum-based ionic liquids (N-alkyl-N,N-dimethylhydroxyethylammonium bis(trifluoromethane)sulfonylimide, [N(11n2OH)][Ntf(2)], n = 1, 2, 3, 4, and 5) plus water or 1-octanol were investigated at atmospheric pressure over the entire composition range. The experiments were conducted between 265 and 385 K using the cloud-point method. The systems exhibit phase diagrams consistent with the existence of upper critical solution temperatures. The solubility of [N(1 1 n 2OH)][Ntf(2)] in water is lower for cations with longer alkyl side chains (larger n values). The corresponding trend in the octanol mixtures is reversed. The ([N(1 1 1 2OH)][Ntf(2)] + water + octanol) ternary system shows triple liquid-liquid immiscibility at room temperature and atmospheric pressure. A combined analytic/synthetic method was used to estimate the corresponding phase diagram under those conditions. Auxiliary molecular dynamics simulation data were used to interpret the experimental results at a molecular level. PMID:22770438

  6. Thermoreversible Ion Gels by Block Copolymer Self-assembly in Ionic Liquids

    NASA Astrophysics Data System (ADS)

    He, Yiyong; Lodge, Timothy

    2007-03-01

    Ion gels, formed by swelling a polymer network with ionic liquids, have been shown to be promising candidates towards highly conductive solid-state electrolytes. Through the self-assembly of triblock copolymers in room-temperature ionic liquids, transparent ion gels could be obtained. Due to the low copolymer concentration, the ionic conductivity of the resulting ion gels is only modestly affected by the triblock copolymer network. By further selecting thermo-responsive end blocks in the triblock copolymers, thermoreversible ion gels were developed. The gelation behavior, ionic conductivity, rheological properties, and microstructure of the ion gels were investigated in detail. The results presented here suggest that triblock copolymer gelation is a promising way to develop highly conductive ion gels.

  7. Analysis of cationic structure in some room-temperature molten fluorides and dependence of their ionic conductivity and viscosity on hydrofluoric acid concentration.

    PubMed

    Isogai, Tomohiro; Nakai, Takaaki; Inoue, Hidemi; Nakanishi, Kenta; Kohara, Shinji; Saito, Morihiro; Inaba, Minoru; Tasaka, Akimasa

    2011-08-11

    To understand the ionic and nonionic species in (CH(3))(4)NF·mHF, (CH(3))(3)N·mHF, (C(2)H(5))(4)NF·mHF, and (C(2)H(5))(3)N·mHF melts, the structures of these melts were investigated by infrared spectroscopy, NMR, and high-energy X-ray diffraction. Infrared spectra revealed that three kinds of fluorohydrogenate anions, (FH)(n)F(-) (n = 1, 2, and 3), and molecular hydrofluoric acid (HF) are present in every melt. Ionic conductivity and viscosity of these melts were measured and correlated with their cationic structure. The ionic conductivity of the R(4)N(+)-systems was higher than that of corresponding R(3)NH(+)-systems because a strong N-H···F(HF)(n) interaction prevents the motion of R(3)NH(+) cations in the R(3)N·mHF melts. (CH(3))(4)N(+) and (CH(3))(3)NH(+) cations gave higher ionic conductivity than (C(2)H(5))(4)N(+) and (C(2)H(5))(3)NH(+) cations, respectively, because the ionic radii of former cations were smaller than those of latter. It was concluded that these effects on ionic conductivity can be explained by the cationic structure and the concentration of molecular HF in the melts. PMID:21714521

  8. Nonlinear polarization of ionic liquids: theory, simulations, experiments

    NASA Astrophysics Data System (ADS)

    Kornyshev, Alexei

    2010-03-01

    Room temperature ionic liquids (RTILs) composed of large, often asymmetric, organic cations and simple or complex inorganic or organic anions do not freeze at ambient temperatures. Their rediscovery some 15 years ago is widely accepted as a ``green revolution'' in chemistry, offering an unlimited number of ``designer'' solvents for chemical and photochemical reactions, homogeneous catalysis, lubrication, and solvent-free electrolytes for energy generation and storage. As electrolytes they are non-volatile, some can sustain without decomposition up to 6 times higher voltages than aqueous electrolytes, and many are environmentally friendly. The studies of RTILs and their applications have reached a critical stage. So many of them can be synthesized - about a thousand are known already - their mixtures can further provide ``unlimited'' number of combinations! Thus, establishing some general laws that could direct the best choice of a RTIL for a given application became crucial; guidance is expected from theory and modelling. But for a physical theory, RTILs comprise a peculiar and complex class of media, the description of which lies at the frontier line of condensed matter theoretical physics: dense room temperature ionic plasmas with ``super-strong'' Coulomb correlations, which behave like glasses at short time-scale, but like viscous liquids at long-time scale. This talk will introduce RTILs to physicists and overview the current understanding of the nonlinear response of RTILs to electric field. It will focus on the theory, simulations, and experimental characterisation of the structure and nonlinear capacitance of the electrical double layer at a charged electrode. It will also discuss pros and contras of supercapacitor applications of RTILs.

  9. Protic ionic liquids with fluorous anions: physicochemical properties and self-assembly nanostructure.

    PubMed

    Shen, Yan; Kennedy, Danielle F; Greaves, Tamar L; Weerawardena, Asoka; Mulder, Roger J; Kirby, Nigel; Song, Gonghua; Drummond, Calum J

    2012-06-14

    A series of 11 new protic ionic liquids with fluorous anions (FPILs) have been identified and their self-assembled nanostructure, thermal phase transitions and physicochemical properties were investigated. To the best of our knowledge this is the first time that fluorocarbon domains have been reported in PILs. The FPILs were prepared from a range of hydrocarbon alkyl and heterocyclic amine cations in combination with the perfluorinated anions heptafluorobutyrate and pentadecafluorooctanoate. The nanostructure of the FPILs was established by using small- and wide-angle X-ray scattering (SAXS and WAXS). In the liquid state many of the FPILs showed an intermediate range order, or self-assembled nanostructure, resulting from segregation of the polar and nonpolar hydrocarbon and fluorocarbon domains of the ionic liquid. In addition, the physicochemical properties of the FPILs were determined including the melting point (T(m)), glass transition (T(g)), devitrification temperature (T(c)), thermal stability and the density ?, viscosity ?, air/liquid surface tension ?(LV), refractive index n(D), and ionic conductivity ?. The FPILs were mostly solids at room temperature, however two examples 2-pyrrolidinonium heptafluorobutyrate (PyrroBF) and pyrrolidinium heptafluorobutyrate (PyrrBF) were liquids at room temperature and all of the FPILs melted below 80 C. Four of the FPILs exhibited a glass transition. The two liquids at room temperature, PyrroBF and PyrrBF, had a similar density, surface tension and refractive index but their viscosity and ionic conductivity were very different due to dissimilar self-assembled nanostructure. PMID:22569799

  10. Liquid crystal self-assembly of halloysite nanotubes in ionic liquids: a novel soft nanocomposite ionogel electrolyte with high anisotropic ionic conductivity and thermal stability

    NASA Astrophysics Data System (ADS)

    Zhao, Ningning; Liu, Yulin; Zhao, Xiaomeng; Song, Hongzan

    2016-01-01

    We report a novel class of liquid crystalline (LC) nanohybrid ionogels fabricated via self-assembly of natural halloysite nanotubes (HNTs) in ionic liquids (ILs). The obtained ionogels are very stable and nonvolatile and show LC phases over a wide temperature range. Remarkably, the nanocomposite ionogels exhibit high anisotropic ionic conductivity after shear, and their room temperature ionic conductivity can reach 3.8 × 10-3 S cm-1 for aligned nanotubes perpendicular to the electrode even when the HNTs content increases to 40 wt%, which is 380 times higher than that obtained for aligned nanotubes parallel to the electrode, which is 1.0 × 10-5 S cm-1. Crucially, the obtained LC nanocomposite ionogels have very high thermal stability, which can sustain 400 °C thermal treatment. The findings will promote the development of novel nanocomposite ionogel electrolytes with faster ion transport and larger anisotropic conductivity.We report a novel class of liquid crystalline (LC) nanohybrid ionogels fabricated via self-assembly of natural halloysite nanotubes (HNTs) in ionic liquids (ILs). The obtained ionogels are very stable and nonvolatile and show LC phases over a wide temperature range. Remarkably, the nanocomposite ionogels exhibit high anisotropic ionic conductivity after shear, and their room temperature ionic conductivity can reach 3.8 × 10-3 S cm-1 for aligned nanotubes perpendicular to the electrode even when the HNTs content increases to 40 wt%, which is 380 times higher than that obtained for aligned nanotubes parallel to the electrode, which is 1.0 × 10-5 S cm-1. Crucially, the obtained LC nanocomposite ionogels have very high thermal stability, which can sustain 400 °C thermal treatment. The findings will promote the development of novel nanocomposite ionogel electrolytes with faster ion transport and larger anisotropic conductivity. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr06888f

  11. Influence of an ionic liquid on the conduction characteristics of lithium niobophosphate glass

    NASA Astrophysics Data System (ADS)

    Dabas, Prashant; Hariharan, K.

    2013-02-01

    A new solid electrolyte, mol% 1 [EMI]BF4-99(0.5Li2O-0.45P2O5-0.05Nb2O5), with room temperature ionic conductivity of 1.7 10-5 S/cm is reported for solid state device applications. Glass transition temperature of the hybrid system decreases by 20 K as compared to the pristine glass. Raman spectra in conjunction with thermal studies reveal that the addition of ionic liquid to the glass seems to increase the disorder in the glass leading to enhanced conductivity.

  12. Electrochemical transistors with ionic liquids for enzymatic sensing

    NASA Astrophysics Data System (ADS)

    Fraser, Kevin J.; Yang, Sang Yoon; Cicoira, Fabio; Curto, Vincenzo F.; Byrne, Robert; Benito-Lopez, Fernando; Khodagholy, Dion; Owens, Risn M.; Malliaras, George G.; Diamond, Dermot

    2011-10-01

    Over the past decade conducting polymer electrodes have played an important role in bio-sensing and actuation. Recent developments in the field of organic electronics have made available a variety of devices that bring unique capabilities at the interface with biology. One example is organic electrochemical transistors (OECTs) that are being developed for a variety of bio-sensing applications, including the detection of ions, and metabolites, such as glucose and lactate. Room temperature ionic liquids (RTILs) are organic salts, which are liquid at ambient temperature. Their nonvolatile character and thermal stability makes them an attractive alternative to conventional organic solvents. Here we report an enzymatic sensor based on an organic electro-chemical transistor with RTIL's as an integral part of its structure and as an immobilization medium for the enzyme and the mediator. Further investigation shows that these platforms can be incorporated into flexible materials such as carbon cloth and can be utilized for bio-sensing. The aim is to incorporate the overall platform in a wearable sensor to improve athlete performance with regards to training. In this manuscript an introduction to ionic liquids (ILs), IL - enzyme mixtures and a combination of these novel materials being used on OECTs are presented.

  13. Refined potential model for atomistic simulations of ionic liquid [bmim][PF6

    NASA Astrophysics Data System (ADS)

    Bhargava, B. L.; Balasubramanian, S.

    2007-09-01

    Refined parameters of an atomistic interaction potential model for the room temperature ionic liquid 1-n-butyl,3-methylimidazolium hexafluorophosphate are presented. Classical molecular dynamics simulations have been carried out to validate this fully flexible all-atom model. It predicts the density of the liquid at different temperatures between 300 and 500K within 1.4% of the experimental value. Intermolecular radial distribution functions and the spatial distribution functions obtained from the new model are in close agreement with ab initio simulations. The calculated diffusion coefficients of ions and the surface tension of the liquid agree well with experiment.

  14. Electrolyte-gated polymer thin film transistors making use of ionic liquids and ionic liquid-solvent mixtures

    NASA Astrophysics Data System (ADS)

    Sayago, Jonathan; Meng, Xiang; Quenneville, Francis; Liang, Shuang; Bourbeau, tienne; Soavi, Francesca; Cicoira, Fabio; Santato, Clara

    2015-03-01

    Electrolyte-Gated (EG) transistors, making use of electrolytes as the gating medium, are interesting for their low operation voltage. Furthermore, EG polymer transistors offer the advantage of solution processing, low cost, and mechanical flexibility. Despite the intense research activity in EG transistors, clear guidelines to correlate the properties of the materials used for the transistor channel and electrolytes with the doping effectiveness of the transistor channel are yet to be clearly established. Here, we investigate the use of room temperature ionic liquids (RTILs) based on the [TFSI] anion (namely, [EMIM][TFSI], [BMIM][TFSI], and [PYR14][TFSI]), to gate transistors making use of MEH-PPV as the channel material. Morphological studies of MEH-PPV and RTIL films showed a certain degree of segregation between the two components. All the EG transistors featured clear drain-source current modulations at voltages below 1 V. Polar solvent additives as propylene carbonate were used to improve the transistor response time.

  15. Bilayer membrane permeability of ionic liquid-filled block copolymer vesicles in aqueous solution.

    PubMed

    Bai, Zhifeng; Zhao, Bin; Lodge, Timothy P

    2012-07-19

    The bilayer membrane permeability of block copolymer vesicles ("polymersomes") with ionic liquid interiors dispersed in water is quantified using fluorescence quenching. Poly((1,2-butadiene)-b-ethylene oxide) (PB-PEO) block copolymer vesicles in water with their interiors filled with a common hydrophobic ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide, were prepared containing a hydrophobic dye, Nile Red, by intact migration of dye-encapsulated vesicles from the ionic liquid to water at room temperature. A small quencher molecule, dichloroacetamide, was added to the aqueous solution of the dye-loaded vesicles, and the permeation of the quencher passing through the membrane into the interior was determined from the fluorescence quenching kinetics. Rapid permeation of the quencher across the nanoscale membrane was observed, consistent with the high fluidity of the liquid polybutadiene membrane. Two different PB-PEO copolymers were employed, in order to vary the thickness of the solvophobic membrane. A significant increase in membrane permeability was also observed with decreasing membrane thickness, which is tentatively attributable to differences in quencher solubility in the membranes. Quantitative migration of the vesicles from the aqueous phase back to an ionic liquid phase was achieved upon heating. These microscopically heterogeneous and thermoresponsive vesicles with permeable and robust membranes have potential as recyclable nanoreactors, in which the high viscosity and capital expense of an ionic liquid reaction medium can be mitigated, while retaining the desirable features of ionic liquids as reaction media, and facile catalyst recovery. PMID:22765509

  16. Pentadecyl phenol- and cardanol-functionalized fluorescent, room-temperature liquid-crystalline perylene bisimides: effect of pendant chain unsaturation on self-assembly.

    PubMed

    Bhavsar, Ghanashyam A; Asha, S K

    2011-11-01

    A new perylene bisimide (PBI) building block based on pentadecyl phenol (PDP) or cardanol was developed, which upon esterification with 3,4,5-tridodecyloxy gallate resulted in highly emissive, room-temperature liquid-crystalline (LC) molecules. The self assembly in solution was studied in detail by NMR spectroscopy, UV/Vis absorption, and fluorescence spectroscopy. In solution both PDP- and cardanol-based PBI exhibited similar behavior. They were molecularly dissolved in chloroform (CHCl(3)) but formed rotationally displaced H-type aggregates that emitted at 640 nm in methylcyclohexane (MCH). Surface morphology in dropcast films were characterized using microscopic techniques such as SEM, TEM, and atomic force microscopy (AFM). The liquid-crystalline properties were studied using differential scanning calorimetry (DSC), polarized light microscopy (PLM), and variable-temperature X-ray (small-angle X-ray scattering (SAXS) and wide-angle X-ray diffraction (WXRD)) studies. Variable-temperature X-ray studies in the LC phase indicated strong π-π stacking interaction present in the PDP-based PBI derivative, whereas the stacking was absent in the LC phase of the cardanol-based PBI. The latter formed self-organized structures of extremely short length due to the presence of cis double bonds in the C15 alkyl side chain, whereas the saturated alkyl side chain in PDP could pack efficiently, thereby resulting in nanofibers that were several micrometers in length. PMID:21956257

  17. Polymer--Ionic liquid Electrolytes for Electrochemical Capacitors

    NASA Astrophysics Data System (ADS)

    Ketabi, Sanaz

    Polymer electrolyte, comprised of ionic conductors, polymer matrix, and additives, is one of the key components that control the performance of solid flexible electrochemical capacitors (ECs). Ionic liquids (ILs) are highly promising ionic conductors for next generation polymer electrolytes due to their excellent electrochemical and thermal stability. Fluorinated ILs are the most commonly applied in polymer-IL electrolytes. Although possessing high conductivity, these ILs have low environmental favorability. The aim of this work was to develop environmentally benign polymer-ILs for both electrochemical double layer capacitors (EDLCs) and pseudocapacitors, and to provide insights into the influence of constituent materials on the ion conduction mechanism and the structural stability of the polymer-IL electrolytes. Solid polymer electrolytes composed of poly(ethylene oxide) (PEO) and 1-ethyl-3-methylimidazolium hydrogen sulfate (EMIHSO4) were investigated for ECs. The material system was optimized to achieve the two criteria for high performance polymer-ILs: high ionic conductivity and highly amorphous structure. Thermal and structural analyses revealed that EMIHSO4 acted as an ionic conductor and a plasticizer that substantially decreased the crystallinity of PEO. Two types of inorganic nanofillers were incorporated into these polymer electrolytes. The effects of SiO2 and TiO2 nanofillers on ionic conductivity, crystallinity, and dielectric properties of PEO-EMIHSO 4 were studied over a temperature range from -10 C and 80 C. Using an electrochemical capacitor model, impedance (complex capacitance) and dielectric analyses were performed to understand the ionic conduction process with and without fillers in both semi crystalline and amorphous states of the polymer electrolytes. Despite their different nanostructures, both SiO2 and TiO2 promoted an amorphous structure in PEO-EMIHSO 4 and increased the ionic conductivity 2-fold. While in the amorphous state, the dielectric constant characteristic of the fillers contributed to the increased conductivity and cell capacitance. Leveraging the fillers, the ionic conductivity of the environmentally friendly polymer-ILs approached the level of the polymer-fluorinated IL at room temperature, and exceeded the latter at high temperature. Another approach to improve the performance of polymer electrolytes was undertaken through the development of protic ILs (PILs) and polymer-PIL electrolytes for pseudocapacitors. Binary eutectic systems of PILs were investigated, and the proton conduction of the eutectic systems was characterized in both liquid and polymer states. Devices enabled by PEO-EMIHSO4 and PEO-binary PILs demonstrated a comparable energy density to that with polymer-fluorinated ILs.

  18. Ionic liquids for rechargeable lithium batteries

    SciTech Connect

    Salminen, Justin; Papaiconomou, Nicolas; Kerr, John; Prausnitz,John; Newman, John

    2005-09-29

    We have investigated possible anticipated advantages of ionic-liquid electrolytes for use in lithium-ion batteries. Thermal stabilities and phase behavior were studied by thermal gravimetric analysis and differential scanning calorimetry. The ionic liquids studied include various imidazoliumTFSI systems, pyrrolidiniumTFSI, BMIMPF{sub 6}, BMIMBF{sub 4}, and BMIMTf. Thermal stabilities were measured for neat ionic liquids and for BMIMBF{sub 4}-LiBF{sub 4}, BMIMTf-LiTf, BMIMTFSI-LiTFSI mixtures. Conductivities have been measured for various ionic-liquid lithium-salt systems. We show the development of interfacial impedance in a Li|BMIMBF{sub 4} + LiBF{sub 4}|Li cell and we report results from cycling experiments for a Li|BMIMBF{sub 4} + 1 mol/kg LIBF{sub 4}|C cell. The interfacial resistance increases with time and the ionic liquid reacts with the lithium electrode. As expected, imidazolium-based ionic liquids react with lithium electrodes. We seek new ionic liquids that have better chemical stabilities.

  19. Physicochemical studies of PVdF-HFP-based polymer-ionic liquid composite electrolytes

    NASA Astrophysics Data System (ADS)

    Lalia, Boor Singh; Yamada, K.; Hundal, M. S.; Park, Jin-Soo; Park, Gu-Gon; Lee, Won-Yong; Kim, Chang-Soo; Sekhon, S. S.

    2009-08-01

    Polymer-ionic liquid composite electrolytes based on poly (vinylidenefluoride-co-hexafluoropropylene) (PVdF-HFP) and room temperature ionic liquid: 2,3-dimethyl-1-octylimidazolium hexafluorophosphate (DMOImPF6) have been synthesized and studied. The addition of dimethylacetamide (DMA) and propylene carbonate (PC), both with high dielectric constant and low viscosity, to polymer electrolytes has been found to result in an enhancement of conductivity by one order of magnitude. Composite polymer electrolytes containing ionic liquid have been found to be thermally stable upto 300C. Motional narrowing observed in the variation of line width of 1H and 19F NMR peaks with temperature suggests that both cations and anions are mobile in these electrolytes.

  20. Carbon dioxide in an ionic liquid: Structural and rotational dynamics.

    PubMed

    Giammanco, Chiara H; Kramer, Patrick L; Yamada, Steven A; Nishida, Jun; Tamimi, Amr; Fayer, Michael D

    2016-03-14

    Ionic liquids (ILs), which have widely tunable structural motifs and intermolecular interactions with solutes, have been proposed as possible carbon capture media. To inform the choice of an optimal ionic liquid system, it can be useful to understand the details of dynamics and interactions on fundamental time scales (femtoseconds to picoseconds) of dissolved gases, particularly carbon dioxide (CO2), within the complex solvation structures present in these uniquely organized materials. The rotational and local structural fluctuation dynamics of CO2 in the room temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EmimNTf2) were investigated by using ultrafast infrared spectroscopy to interrogate the CO2 asymmetric stretch. Polarization-selective pump probe measurements yielded the orientational correlation function of the CO2 vibrational transition dipole. It was found that reorientation of the carbon dioxide occurs on 3 time scales: 0.91 ± 0.03, 8.3 ± 0.1, 54 ± 1 ps. The initial two are attributed to restricted wobbling motions originating from a gating of CO2 motions by the IL cations and anions. The final (slowest) decay corresponds to complete orientational randomization. Two-dimensional infrared vibrational echo (2D IR) spectroscopy provided information on structural rearrangements, which cause spectral diffusion, through the time dependence of the 2D line shape. Analysis of the time-dependent 2D IR spectra yields the frequency-frequency correlation function (FFCF). Polarization-selective 2D IR experiments conducted on the CO2 asymmetric stretch in the parallel- and perpendicular-pumped geometries yield significantly different FFCFs due to a phenomenon known as reorientation-induced spectral diffusion (RISD), revealing strong vector interactions with the liquid structures that evolve slowly on the (independently measured) rotation time scales. To separate the RISD contribution to the FFCF from the structural spectral diffusion contribution, the previously developed first order Stark effect RISD model is reformulated to describe the second order (quadratic) Stark effect-the first order Stark effect vanishes because CO2 does not have a permanent dipole moment. Through this analysis, we characterize the structural fluctuations of CO2 in the ionic liquid solvation environment, which separate into magnitude-only and combined magnitude and directional correlations of the liquid's time dependent electric field. This new methodology will enable highly incisive comparisons between CO2 dynamics in a variety of ionic liquid systems. PMID:26979696

  1. Carbon dioxide in an ionic liquid: Structural and rotational dynamics

    NASA Astrophysics Data System (ADS)

    Giammanco, Chiara H.; Kramer, Patrick L.; Yamada, Steven A.; Nishida, Jun; Tamimi, Amr; Fayer, Michael D.

    2016-03-01

    Ionic liquids (ILs), which have widely tunable structural motifs and intermolecular interactions with solutes, have been proposed as possible carbon capture media. To inform the choice of an optimal ionic liquid system, it can be useful to understand the details of dynamics and interactions on fundamental time scales (femtoseconds to picoseconds) of dissolved gases, particularly carbon dioxide (CO2), within the complex solvation structures present in these uniquely organized materials. The rotational and local structural fluctuation dynamics of CO2 in the room temperature ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EmimNTf2) were investigated by using ultrafast infrared spectroscopy to interrogate the CO2 asymmetric stretch. Polarization-selective pump probe measurements yielded the orientational correlation function of the CO2 vibrational transition dipole. It was found that reorientation of the carbon dioxide occurs on 3 time scales: 0.91 ± 0.03, 8.3 ± 0.1, 54 ± 1 ps. The initial two are attributed to restricted wobbling motions originating from a gating of CO2 motions by the IL cations and anions. The final (slowest) decay corresponds to complete orientational randomization. Two-dimensional infrared vibrational echo (2D IR) spectroscopy provided information on structural rearrangements, which cause spectral diffusion, through the time dependence of the 2D line shape. Analysis of the time-dependent 2D IR spectra yields the frequency-frequency correlation function (FFCF). Polarization-selective 2D IR experiments conducted on the CO2 asymmetric stretch in the parallel- and perpendicular-pumped geometries yield significantly different FFCFs due to a phenomenon known as reorientation-induced spectral diffusion (RISD), revealing strong vector interactions with the liquid structures that evolve slowly on the (independently measured) rotation time scales. To separate the RISD contribution to the FFCF from the structural spectral diffusion contribution, the previously developed first order Stark effect RISD model is reformulated to describe the second order (quadratic) Stark effect—the first order Stark effect vanishes because CO2 does not have a permanent dipole moment. Through this analysis, we characterize the structural fluctuations of CO2 in the ionic liquid solvation environment, which separate into magnitude-only and combined magnitude and directional correlations of the liquid's time dependent electric field. This new methodology will enable highly incisive comparisons between CO2 dynamics in a variety of ionic liquid systems.

  2. Is the boundary layer of an ionic liquid equally lubricating at higher temperature?

    PubMed

    Hjalmarsson, Nicklas; Atkin, Rob; Rutland, Mark W

    2016-03-23

    Atomic force microscopy has been used to study the effect of temperature on normal forces and friction for the room temperature ionic liquid (IL) ethylammonium nitrate (EAN), confined between mica and a silica colloid probe at 25 °C, 50 °C, and 80 °C. Force curves revealed a strong fluid dynamic influence at room temperature, which was greatly reduced at elevated temperatures due to the reduced liquid viscosity. A fluid dynamic analysis reveals that bulk viscosity is manifested at large separation but that EAN displays a nonzero slip, indicating a region of different viscosity near the surface. At high temperatures, the reduction in fluid dynamic force reveals step-like force curves, similar to those found at room temperature using much lower scan rates. The ionic liquid boundary layer remains adsorbed to the solid surface even at high temperature, which provides a mechanism for lubrication when fluid dynamic lubrication is strongly reduced. The friction data reveals a decrease in absolute friction force with increasing temperature, which is associated with increased thermal motion and reduced viscosity of the near surface layers but, consistent with the normal force data, boundary layer lubrication was unaffected. The implications for ILs as lubricants are discussed in terms of the behaviour of this well characterised system. PMID:26976694

  3. Photochemical Schiemann Reaction in Ionic Liquids

    PubMed Central

    Heredia-Moya, Jorge; Kirk, Kenneth L.

    2007-01-01

    Photochemical Schiemann reactions of imidazole derivatives 1 and 4 were carried out in 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid [bmim][BF4] as solvent. The effects of temperature, co-solvent and wavelength on the rate of the reaction and product yield were examined. The use of ionic liquid increases the yield of the photochemical fluorodediazoniation reaction of 2 at 0°C. Careful temperature control is necessary to minimize the photodecomposition of the ionic liquid in order to increase the yield of product. PMID:18079989

  4. Ion-pair evaporation from ionic liquid clusters.

    PubMed

    Hogan, Christopher J; Fernandez de la Mora, Juan

    2010-08-01

    A differential mobility analyzer (DMA) is used in atmospheric pressure N(2) to select a narrow range of electrical mobilities from a complex mix of cluster ions of composition (CA)(n)(C(+))(z). The clusters are introduced into the N(2) gas by electrospraying concentrated (approximately 20 mM) acetonitrile solutions of ionic liquids (molten salts) of composition CA (C(+) = cation, A(-) = anion). Mass analysis of these mobility-selected ions reveals the occurrence of individual neutral ion-pair evaporation events from the smallest singly charged clusters: (CA)(n)C(+)-->(CA)(n-1)C(+)+CA. Although bulk ionic liquids are effectively involatile at room temperature, up to six sequential evaporation events are observed. Because this requires far more internal energy than available in the original clusters, substantial heating (approximately 10 eV) must take place in the ion guides leading to the mass analyzer. The observed increase in IL evaporation rate with decreasing size is drastic, in qualitative agreement with the exponential vapor pressure dependence predicted by Kelvin's formula. A single evaporation event is barely detectable at n = 13, while two or more are prominent for n < or = 9. Magic number clusters (CA)(4)C(+) with singularly low volatilities are found in three of the four ionic liquids studied. Like their recently reported liquid phase prenucleation cluster analogs, these magic number clusters could play a key role as gas-phase nucleation seeds. All the singularly involatile clusters seen are cations, which may help understand commonly observed sign effects in ion-induced nucleation. No other charge-sign asymmetry is seen on cluster evaporation. PMID:20447834

  5. Ionic Liquids as Quasihydrostatic Pressure Media for Diamond Anvil Cell Experiments

    NASA Astrophysics Data System (ADS)

    Mayorga, Sierra; Moldowan, Kaela; Dan, Ioana; Forster, Paul; Iota, Valentin

    2012-02-01

    Ionic liquids (ILs) are salts in which the ions are poorly coordinated to the point where the eutectic mixture remains liquid at room temperature. In general, ILs exhibit high chemical and thermal stability, have extended liquid regions in the pressure-temperature domain, and can be easily obtained. Commercial ionic liquids are relatively inexpensive and custom ionic solutions can be easily synthesized by mixing common reactants. These properties make ionic liquids attractive candidates for high-pressure media in Diamond Anvil Cell (DAC) experiments. In this presentation we explore the use of ionic liquids as DAS quasihydrostatic pressure media for pressures up to 50 GPa. As a measure of hydrostaticity we monitor the splitting and peak-widths of the R1 andR 2 fluorescence lines from small ruby chips (Al2O3 :Cr^3+) imbedded in the pressure medium. We present results on a series of commercially available ionic fluids against standard pressure media: methanol-ethanol mixtures, silicone oil, sodium chloride (NaCl) and noble gases (Ar, Ne, He).

  6. Recent development of ionic liquid stationary phases for liquid chromatography.

    PubMed

    Shi, Xianzhe; Qiao, Lizhen; Xu, Guowang

    2015-11-13

    Based on their particular physicochemical characteristics, ionic liquids have been widely applied in many fields of analytical chemistry. Many types of ionic liquids were immobilized on a support like silica or monolith as stationary phases for liquid chromatography. Moreover, different approaches were developed to bond covalently ionic liquids onto the supporting materials. The obtained ionic liquid stationary phases show multi-mode mechanism including hydrophobic, hydrophilic, hydrogen bond, anion exchange, π-π, and dipole-dipole interactions. Therefore, they could be used in different chromatographic modes including ion-exchange, RPLC, NPLC and HILIC to separate various classes of compounds. This review mainly summarizes the immobilized patterns and types of ionic liquid stationary phases, their retention mechanisms and applications in the recent five years. PMID:26463427

  7. Conductance modulation in topological insulator Bi{sub 2}Se{sub 3} thin films with ionic liquid gating

    SciTech Connect

    Son, Jaesung; Banerjee, Karan; Yang, Hyunsoo; Brahlek, Matthew; Koirala, Nikesh; Oh, Seongshik; Lee, Seoung-Ki; School of Electrical and Electronic Engineering, Yonsei University, Seoul 120-749 ; Ahn, Jong-Hyun

    2013-11-18

    A Bi{sub 2}Se{sub 3} topological insulator field effect transistor is investigated by using ionic liquid as an electric double layer gating material, leading to a conductance modulation of 365% at room temperature. We discuss the role of charged impurities on the transport properties. The conductance modulation with gate bias is due to a change in the carrier concentration, whereas the temperature dependent conductance change is originated from a change in mobility. Large conductance modulation at room temperature along with the transparent optical properties makes topological insulators as an interesting (opto)electronic material.

  8. Surface confined ionic liquid as a stationary phase for HPLC

    SciTech Connect

    Wang, Qian; Baker, Gary A; Baker, Sheila N; Colon, Luis

    2006-01-01

    Trimethoxysilane ionosilane derivatives of room temperature ionic liquids based on alkylimidazolium bromides were synthesized for attachment to silica support material. The derivatives 1-methyl-3-(trimethoxysilylpropyl)imidazolium bromide and 1-butyl-3-(trimethoxysilylpropyl)imidazolium bromide were used to modify the surface of 3 {micro}m diameter silica particles to act as the stationary phase for HPLC. The modified particles were characterized by thermogravimetric analysis (TGA) and {sup 13}C and {sup 29}Si NMR spectroscopies. The surface modification procedure rendered particles with a surface coverage of 0.84 {micro}mol m{sup -2} for the alkylimidazolium bromide. The ionic liquid moiety was predominantly attached to the silica surface through two siloxane bonds of the ionosilane derivative (63%). Columns packed with the modified silica material were tested under HPLC conditions. Preliminary evaluation of the stationary phase for HPLC was performed using aromatic carboxylic acids as model compounds. The separation mechanism appears to involve multiple interactions including ion exchange, hydrophobic interaction, and other electrostatic interactions.

  9. Spatial-decomposition analysis of electrical conductivity in ionic liquid.

    PubMed

    Tu, Kai-Min; Ishizuka, Ryosuke; Matubayasi, Nobuyuki

    2014-12-28

    The electrical conductivity of room temperature ionic liquid (IL) is investigated with molecular dynamics simulation. A trajectory of 1 μs in total is analyzed for the ionic liquid [C4mim][NTf2] (1-n-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, and the anion is also called TFSI or TFSA), and the ion motions are examined in direct connection to the conductivity within the framework formulated previously [K.-M. Tu, R. Ishizuka, and N. Matubayasi, J. Chem. Phys. 141, 044126 (2014)]. As a transport coefficient, the computed electrical conductivity is in fair agreement with the experiment. The conductivity is then decomposed into the autocorrelation term of Nernst-Einstein form and the cross-correlation term describing the two-body motions of ions, and the cross-correlation term is further decomposed spatially to incorporate the structural insights on ion configurations into the dynamic picture. It is observed that the ion-pair contribution to the conductivity is not spatially localized and extends beyond the first coordination shell. The extent of localization of the cross-correlation effect in the conductivity is in correspondence to that of the spatial correlation represented by radial distribution function, which persists over nanometer scale. PMID:25554167

  10. Spatial-decomposition analysis of electrical conductivity in ionic liquid

    NASA Astrophysics Data System (ADS)

    Tu, Kai-Min; Ishizuka, Ryosuke; Matubayasi, Nobuyuki

    2014-12-01

    The electrical conductivity of room temperature ionic liquid (IL) is investigated with molecular dynamics simulation. A trajectory of 1 ?s in total is analyzed for the ionic liquid [C4mim][NTf2] (1-n-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, and the anion is also called TFSI or TFSA), and the ion motions are examined in direct connection to the conductivity within the framework formulated previously [K.-M. Tu, R. Ishizuka, and N. Matubayasi, J. Chem. Phys. 141, 044126 (2014)]. As a transport coefficient, the computed electrical conductivity is in fair agreement with the experiment. The conductivity is then decomposed into the autocorrelation term of Nernst-Einstein form and the cross-correlation term describing the two-body motions of ions, and the cross-correlation term is further decomposed spatially to incorporate the structural insights on ion configurations into the dynamic picture. It is observed that the ion-pair contribution to the conductivity is not spatially localized and extends beyond the first coordination shell. The extent of localization of the cross-correlation effect in the conductivity is in correspondence to that of the spatial correlation represented by radial distribution function, which persists over nanometer scale.

  11. Alkaline ionic liquids applied in supported ionic liquid catalyst for selective hydrogenation of citral to citronellal

    PubMed Central

    Salminen, Eero; Virtanen, Pasi; Mikkola, Jyri-Pekka

    2014-01-01

    The challenge in preparation of ionic liquids containing a strong alkaline anion is to identify a suitable cation which can tolerate the harsh conditions induced by the anion. In this study, a commercial quaternary ammonium compound (quat) benzalkonium [ADBA] (alkyldimethylbenzylammonium) was used as a cation in the synthesis of different alkaline ionic liquids. In fact, the precursor, benzalkonium chloride, is a mixture of alkyldimethylbenzylammonium chlorides of various alkyl chain lengths and is commonly used in the formulation of various antiseptic products. The prepared ionic liquids were utilized as Supported Ionic Liquid Catalysts (SILCAs). Typically, a SILCA contains metal nanoparticles, enzymes, or metal complexes in an ionic liquid layer which is immobilized on a solid carrier material such as an active carbon cloth (ACC). The catalysts were applied in the selective hydrogenation of citral to citronellal which is an important perfumery chemical. Interestingly, 70% molar yield toward citronellal was achieved over a catalyst containing the alkaline ionic liquid benzalkonium methoxide. PMID:24790972

  12. Alkaline ionic liquids applied in supported ionic liquid catalyst for selective hydrogenation of citral to citronellal

    NASA Astrophysics Data System (ADS)

    Salminen, Eero; Virtanen, Pasi; Mikkola, Jyri-Pekka

    2014-02-01

    The challenge in preparation of ionic liquids containing a strong alkaline anion is to identify a suitable cation which can tolerate the harsh conditions induced by the anion. In this study, a commercial quaternary ammonium compound (quat) benzalkonium [ADBA] (alkyldimethylbenzylammonium) was used as a cation in the synthesis of different alkaline ionic liquids. In fact, the precursor, benzalkonium chloride, is a mixture of alkyldimethylbenzylammonium chlorides of various alkyl chain lengths and is commonly used in the formulation of various antiseptic products. The prepared ionic liquids were utilized as Supported Ionic Liquid Catalysts (SILCAs). Typically, a SILCA contains metal nanoparticles, enzymes or metal complexes in an ionic liquid layer which is immobilized on a solid carrier material such as an active carbon cloth (ACC). The catalysts were applied in the selective hydrogenation of citral to citronellal which is an important perfumery chemical. Interestingly, 70 % molar yield towards citronellal was achieved over a catalyst containing the alkaline ionic liquid benzalkonium methoxide.

  13. system at room temperature

    NASA Astrophysics Data System (ADS)

    Li, Shaoyuan; Ma, Wenhui; Zhou, Yang; Chen, Xiuhua; Xiao, Yongyin; Ma, Mingyu; Zhu, Wenjie; Wei, Feng

    2014-04-01

    In this paper, the moderately and lightly doped porous silicon nanowires (PSiNWs) were fabricated by the `one-pot procedure' metal-assisted chemical etching (MACE) method in the HF/H2O2/AgNO3 system at room temperature. The effects of H2O2 concentration on the nanostructure of silicon nanowires (SiNWs) were investigated. The experimental results indicate that porous structure can be introduced by the addition of H2O2 and the pore structure could be controlled by adjusting the concentration of H2O2. The H2O2 species replaces Ag+ as the oxidant and the Ag nanoparticles work as catalyst during the etching. And the concentration of H2O2 influences the nucleation and motility of Ag particles, which leads to formation of different porous structure within the nanowires. A mechanism based on the lateral etching which is catalyzed by Ag particles under the motivation by H2O2 reduction is proposed to explain the PSiNWs formation.

  14. Use of Ionic Liquids in Rod-Coil Block Copolyimides for Improved Lithium Ion Conduction

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann B.; Tigelaar, Dean M.; Chapin, Kara; Bennett, William R.

    2007-01-01

    Solvent-free, solid polymer electrolytes (SPE) have the potential to improve safety, increase design flexibility and enhance performance of rechargeable lithium batteries. Solution based electrolytes are flammable and typically incompatible with lithium metal anodes, limiting energy density. We have previously demonstrated use of polyimide rod coil block copolymers doped with lithium salts as electrolytes for lithium polymer batteries. The polyimide rod blocks provide dimensional stability while the polyethylene oxide (PEO) coil portions conduct ions. Phase separation of the rods and coils in these highly branched polymers provide channels with an order of magnitude improvement in lithium conduction over polyethylene oxide itself at room temperature. In addition, the polymers have been demonstrated in coin cells to be compatible with lithium metal. For practical use at room temperature and below, however, at least an order of magnitude improvement in ion conduction is still required. The addition of nonvolatile, room temperature ionic liquids has been shown to improve the ionic conductivity of high molecular weight PEO. Herein we describe use of these molten salts to improve ionic conductivity in the rod-coil block copolymers.

  15. Ionic liquid polyoxometalates as light emitting materials

    SciTech Connect

    Ortiz-acosta, Denisse; Del Sesto, Rico E; Scott, Brian; Bennett, Bryan L; Purdy, Geraldine M; Muenchausen, Ross E; Mc Kigney, Edward; Gilbertson, Robert

    2008-01-01

    The low melting point, negligible vapor pressure, good solubility, and thermal and chemical stability make ionic liquids useful materials for a wide variety of applications. Polyoxometalates are early transition metal oxygen clusters that can be synthesized in many different sizes and with a variety of heterometals. The most attractive feature of POMs is that their physical properties, in particular electrical, magnetic, and optical properties, can be easily modified following known procedures. It has been shown that POMs can exhibit cooperative properties, as superconductivity and energy transfer. POM ionic liquids can be obtained by selecting the appropliate cation. Different alkyl ammonium and alkyl phosphonium salts are being used to produce new POM ionic liquids together with organic or inorganic luminescent centers to design light emitting materials. Ammonium and phosphonium cations with activated, polymerizable groups are being used to further polymerize the ionic liquid into transparent, solid materials with high metal density.

  16. Low Temperature Reduction of Alumina Using Fluorine Containing Ionic Liquids

    SciTech Connect

    Dr. R. G. Reddy

    2007-09-01

    The major objective of the project is to establish the feasibility of using specific ionic liquids capable of sustaining aluminum electrolysis near room temperature at laboratory and batch recirculation scales. It will explore new technologies for aluminum and other valuable metal extraction and process methods. The new technology will overcome many of the limitations associated with high temperatures processes such as high energy consumption and corrosion attack. Furthermore, ionic liquids are non-toxic and could be recycled after purification, thus minimizing extraction reagent losses and environmental pollutant emissions. Ionic liquids are mixture of inorganic and organic salts which are liquid at room temperature and have wide operational temperature range. During the last several years, they were emerging as novel electrolytes for extracting and refining of aluminum metals and/or alloys, which are otherwise impossible using aqueous media. The superior high temperature characteristics and high solvating capabilities of ionic liquids provide a unique solution to high temperature organic solvent problems associated with device internal pressure build-up, corrosion, and thermal stability. However their applications have not yet been fully implemented due to the insufficient understanding of the electrochemical mechanisms involved in processing of aluminum with ionic liquids. Laboratory aluminum electrodeposition in ionic liquids has been investigated in chloride and bis (trifluoromethylsulfonyl) imide based ionic liquids. The electrowinning process yielded current density in the range of 200-500 A/m2, and current efficiency of about 90%. The results indicated that high purity aluminum (>99.99%) can be obtained as cathodic deposits. Cyclic voltammetry and chronoamperometry studies have shown that initial stages of aluminum electrodeposition in ionic liquid electrolyte at 30°C was found to be quasi-reversible, with the charge transfer coefficient (0.40). Nucleation phenomena involved in aluminum deposition on copper in AlCl3-BMIMCl electrolyte was found to be instantaneous followed by diffusion controlled three-dimensional growth of nuclei. Diffusion coefficient (Do) of the electroactive species Al2Cl7¯ ion was in the range from 6.5 to 3.9×10–7 cm2∙s–1 at a temperature of 30°C. Relatively little research efforts have been made toward the fundamental understanding and modeling of the species transport and transformation information involved in ionic liquid mixtures, which eventually could lead to quantification of electrochemical properties. Except that experimental work in this aspect usually is time consuming and expensive, certain characteristics of ionic liquids also made barriers for such analyses. Low vapor pressure and high viscosity make them not suitable for atomic absorption spectroscopic measurement. In addition, aluminum electrodeposition in ionic liquid electrolytes are considered to be governed by multi-component mass, heat and charge transport in laminar and turbulent flows that are often multi-phase due to the gas evolution at the electrodes. The kinetics of the electrochemical reactions is in general complex. Furthermore, the mass transfer boundary layer is about one order of magnitude smaller than the thermal and hydrodynamic boundary layer (Re=10,000). Other phenomena that frequently occur are side reactions and temperature or concentration driven natural convection. As a result of this complexity, quantitative knowledge of the local parameters (current densities, ion concentrations, electrical potential, temperature, etc.) is very difficult to obtain. This situation is a serious obstacle for improving the quality of products, efficiency of manufacturing and energy consumption. The gap between laboratory/batch scale processing with global process control and nanoscale deposit surface and materials specifications needs to be bridged. A breakthrough can only be realized if on each scale the occurring phenomena are understood and quantified. Multiscale numerical modeling nevertheless can help to bridge this gap. In conjunction with various scale experimental efforts, this project was aim to construct the basis for a strategy for innovation, by developing a generally applicable modeling methodology for understanding and controlling the electrochemical processes of aluminum electrodeposition in ionic liquids with the unifying characteristic that they are based on charge-driven mass transfer. The approaches developed in this project will not only be essential for the mass production of aluminum on any pilot scale or industrial level production processes, leading to the development of a new aluminum production technology, but also bring significant benefits to the society in terms of saving energy, reducing pollutants emission and recovering valuable metals.

  17. Low Temperature Reduction of Alumina Using Fluorine Containing Ionic Liquids

    SciTech Connect

    Dr. Ramana G. Reddy

    2009-01-31

    EXECUTIVE SUMMARY The major objective of the project is to establish the feasibility of using specific ionic liquids capable of sustaining aluminum electrolysis near room temperature at laboratory and batch recirculation scales. It will explore new technologies for aluminum and other valuable metal extraction and process methods. The new technology will overcome many of the limitations associated with high temperatures processes such as high energy consumption and corrosion attack. Furthermore, ionic liquids are non-toxic and could be recycled after purification, thus minimizing extraction reagent losses and environmental pollutant emissions. Ionic liquids are mixture of inorganic and organic salts which are liquid at room temperature and have wide operational temperature range. During the last several years, they were emerging as novel electrolytes for extracting and refining of aluminum metals and/or alloys, which are otherwise impossible using aqueous media. The superior high temperature characteristics and high solvating capabilities of ionic liquids provide a unique solution to high temperature organic solvent problems associated with device internal pressure build-up, corrosion, and thermal stability. However their applications have not yet been fully implemented due to the insufficient understanding of the electrochemical mechanisms involved in processing of aluminum with ionic liquids. Laboratory aluminum electrodeposition in ionic liquids has been investigated in chloride and bis (trifluoromethylsulfonyl) imide based ionic liquids. The electrowinning process yielded current density in the range of 200-500 A/m2, and current efficiency of about 90%. The results indicated that high purity aluminum (>99.99%) can be obtained as cathodic deposits. Cyclic voltammetry and chronoamperometry studies have shown that initial stages of aluminum electrodeposition in ionic liquid electrolyte at 30°C was found to be quasi-reversible, with the charge transfer coefficient  = 0.40. Nucleation phenomena involved in aluminum deposition on copper in AlCl3-BMIMCl electrolyte was found to be instantaneous followed by diffusion controlled three-dimensional growth of nuclei. Diffusion coefficient (Do) of the electroactive species Al2Cl7¯ ion was in the range from 6.5 to 3.9×10–7 cm2∙s–1 at a temperature of 30°C. Relatively little research efforts have been made toward the fundamental understanding and modeling of the species transport and transformation information involved in ionic liquid mixtures, which eventually could lead to quantification of electrochemical properties. Except that experimental work in this aspect usually is time consuming and expensive, certain characteristics of ionic liquids also made barriers for such analyses. Low vapor pressure and high viscosity make them not suitable for atomic absorption spectroscopic measurement. In addition, aluminum electrodeposition in ionic liquid electrolytes are considered to be governed by multi-component mass, heat and charge transport in laminar and turbulent flows that are often multi-phase due to the gas evolution at the electrodes. The kinetics of the electrochemical reactions is in general complex. Furthermore, the mass transfer boundary layer is about one order of magnitude smaller than the thermal and hydrodynamic boundary layer (ReL≈10,000). Other phenomena that frequently occur are side reactions and temperature or concentration driven natural convection. As a result of this complexity, quantitative knowledge of the local parameters (current densities, ion concentrations, electrical potential, temperature, etc.) is very difficult to obtain. This situation is a serious obstacle for improving the quality of products, efficiency of manufacturing and energy consumption. The gap between laboratory/batch scale processing with global process control and nanoscale deposit surface and materials specifications needs to be bridged. A breakthrough can only be realized if on each scale the occurring phenomena are understood and quantified. Multiscale numerical modeling nevertheless can help to bridge this gap. In conjunction with various scale experimental efforts, this project was aim to construct the basis for a strategy for innovation, by developing a generally applicable modeling methodology for understanding and controlling the electrochemical processes of aluminum electrodeposition in ionic liquids with the unifying characteristic that they are based on charge-driven mass transfer. The approaches developed in this project will not only be essential for the mass production of aluminum on any pilot scale or industrial level production processes, leading to the development of a new aluminum production technology, but also bring significant benefits to the society in terms of saving energy, reducing pollutants emission and recovering valuable metals.

  18. Materials Named Ionic LiquidsHistory and Definition

    NASA Astrophysics Data System (ADS)

    Hirayama, Naoki

    In recent years, a series of materials named ionic liquids have attracted attention and been extensively studied in various fields of chemistry. What ionic liquids are, however, has not been yet standardized. This review presents the history of ionic liquid research and definition of the term ionic liquid from a viewpoint that it should be classified as a nonaqueous solvent.

  19. The Solubility Parameters of Ionic Liquids

    PubMed Central

    Marciniak, Andrzej

    2010-01-01

    The Hildebrand’s solubility parameters have been calculated for 18 ionic liquids from the inverse gas chromatography measurements of the activity coefficients at infinite dilution. Retention data were used for the calculation. The solubility parameters are helpful for the prediction of the solubility in the binary solvent mixtures. From the solubility parameters, the standard enthalpies of vaporization of ionic liquids were estimated. PMID:20559495

  20. Superbase-derived protic ionic liquids

    DOEpatents

    Dai, Sheng; Luo, Huimin; Baker, Gary A.

    2013-09-03

    Protic ionic liquids having a composition of formula (A.sup.-)(BH.sup.+) wherein A.sup.- is a conjugate base of an acid HA, and BH.sup.+ is a conjugate acid of a superbase B. In particular embodiments, BH.sup.+ is selected from phosphazenium species and guanidinium species encompassed, respectively, by the general formulas: ##STR00001## The invention is also directed to films and membranes containing these protic ionic liquids, with particular application as proton exchange membranes for fuel cells.

  1. Self-interaction error in DFT-based modelling of ionic liquids.

    PubMed

    Lage-Estebanez, Isabel; Ruzanov, Anton; Garca de la Vega, Jos M; Fedorov, Maxim V; Ivanitev, Vladislav B

    2016-01-21

    The modern computer simulations of potential green solvents of the future, involving the room temperature ionic liquids, heavily rely on density functional theory (DFT). In order to verify the appropriateness of the common DFT methods, we have investigated the effect of the self-interaction error (SIE) on the results of DFT calculations for 24 ionic pairs and 48 ionic associates. The magnitude of the SIE is up to 40 kJ mol(-1) depending on the anion choice. Most strongly the SIE influences the calculation results of ionic associates that contain halide anions. For these associates, the range-separated density functionals suppress the SIE; for other cases, the revPBE density functional with dispersion correction and triple-? Slater-type basis is suitable for computationally inexpensive and reasonably accurate DFT calculations. PMID:26690957

  2. Soft glassy colloidal arrays in an ionic liquid: colloidal glass transition, ionic transport, and structural color in relation to microstructure.

    PubMed

    Ueno, Kazuhide; Sano, Yuta; Inaba, Aya; Kondoh, Masashi; Watanabe, Masayoshi

    2010-10-21

    The colloidal glass transition, ionic transport, and optical properties of soft glassy colloidal arrays (SGCAs) that consist of poly(methyl methacrylate) (PMMA)-grafted silica nanoparticles (PMMA-g-NPs) and a room-temperature ionic liquid, 1-ethyl-3-methylimidazolium bis(trifluoromethane sulfonyl)amide ([C(2)mim][NTf(2)]), were investigated. At lower particle concentrations, PMMA-g-NPs were well-suspended in the IL without any aggregation or sedimentation, and the dilute suspensions showed liquid-like behavior. However, above a certain particle concentration, the suspensions became solidified and exhibited different structural colors depending on the particle concentrations. The liquid-solid transition of the SGCAs was essentially caused by colloidal glass transition. Due to the soft repulsive interaction between the particles, the effective volume fraction of the particle (?(eff)) required for colloidal glass transition was higher than that of the hard sphere system and found to be approximately 0.70-0.74. The SGCA had sufficient ionic conductivity, which was greater than 10(-3) S cm(-1) at room temperature, even in the highly concentrated region. For ionic transport of the cation and the anion in the SGCAs, the decrease in diffusivity observed with the addition of the particles (D(g)/D(0)) was slightly greater for the [NTf(2)] anion than that of the [C(2)mim] cation, suggesting that the [NTf(2)] anion preferentially interacts with the PMMA chains. The SGCAs showed homogeneous, nonbrilliant, and angle-independent structural colors above the glass transition volume fraction. In addition, the color of the SGCAs changed from red to green to blue as the particle concentration increased. A linear relationship was found between the maximum wavelength of the reflection spectra and the center-to-center distance in the SGCAs. PMID:20879726

  3. Lyotropic liquid crystal phases of phytantriol in a protic ionic liquid with fluorous anion.

    PubMed

    Shen, Yan; Greaves, Tamar L; Kennedy, Danielle F; Weerawardena, Asoka; Kirby, Nigel; Song, Gonghua; Drummond, Calum J

    2014-10-21

    The phase behaviour of phytantriol in the protic ionic liquid (PIL) 1-methylimidazolium pentadecafluorooctanoate (MImOF) and four different MImOF-water compositions was investigated by small- and wide-angle X-ray scattering (SAXS/WAXS), cross polarised optical microscopy (CPOM) and infrared spectroscopy (IR). MImOF is a distinct protic ionic liquid in that it contains a fluorocarbon anion and a hydrocarbon cation. This leads to MImOF having an unusual liquid nanostructure, such that it contains fluorocarbon, hydrocarbon and polar domains. No lyotropic liquid crystal phases were observed for phytantriol in neat MImOF. However, on addition of water, lamellar, cubic Ia3d and micellar phases were observed for specific MImOF-phytantriol-water compositions at room temperature, and up to 60 C. The phase behaviour for phytantriol in the solvent mixture of 25 wt%-MImOF-75 wt%-water was the most similar to the phytantriol-water phase diagram. Only this MImOF-water composition supported the Ia3d cubic phase, which had a lattice parameter between 100-140 compared to 86-100 in deionised water, indicating significant swelling due to the MImOF. IR spectroscopy showed that a percentage of the water molecules were hydrogen bonded to the N-H of the MIm cation, and this water decreased the hydrogen bonding present between the cation and anion of the ionic liquid. This investigation furthers our understanding of the interaction of ionic liquids with solutes, and the important role that the different IL nanostructures can have on influencing these interactions. PMID:25177837

  4. Task-Specific Ionic Liquids for Mars Exploration (Green Chemistry for a Red Planet)

    NASA Technical Reports Server (NTRS)

    Karr, L. J.; Curreri, P. A.; Paley, M. S.; Kaukler, W. F.; Marone, M. J.

    2012-01-01

    Ionic Liquids (ILs) are organic salts with low melting points that are liquid at or near room temperature. The combinations of available ions and task-specific molecular designability make them suitable for a huge variety of tasks. Because of their low flammability, low vapor pressure, and stability in harsh environments (extreme temperatures, hard vacuum) they are generally much safer and "greener" than conventional chemicals and are thus suitable for a wide range of applications that support NASA exploration goals. This presentation describes several of the ongoing applications that are being developed at MSFC.

  5. High current density electrodeposition from silver complex ionic liquids.

    PubMed

    Schaltin, Stijn; Brooks, Neil R; Stappers, Linda; Van Hecke, Kristof; Van Meervelt, Luc; Binnemans, Koen; Fransaer, Jan

    2012-02-01

    Liquid metal salts are electrolytes with the highest possible metal concentration for electrodeposition, because the metal ion is an integral part of the solvent. This paper introduces the new ionic silver complexes [Ag(MeCN)(4)](2)[Ag(Tf(2)N)(3)], [Ag(MeCN)][Tf(2)N] and [Ag(EtIm)(2)][Tf(2)N], where MeCN stands for acetonitrile, EtIm for 1-ethylimidazole and Tf(2)N is bis(trifluoromethylsulfonyl)imide. These complexes have been characterized by differential scanning calorimetry, single crystal X-ray crystallography, thermogravimetrical analysis, Raman spectroscopy and cyclic voltammetry. [Ag(MeCN)(4)](2)[Ag(Tf(2)N)(3)] is a room temperature ionic liquid. Smooth silver layers of good quality could be deposited from it, at current densities of up to 25 A dm(-2) in unstirred solutions. [Ag(EtIm)(2)][Tf(2)N] melts at 65 C and can be used as an electrolyte for silver deposition above this temperature. [Ag(MeCN)][Tf(2)N] has a melting point that is too high to be useful in electrodeposition. Addition of thiourea or 1H-benzotriazole to the electrolyte decreased the surface roughness of the silver coatings. The morphology of the metal layers was investigated by atomic force microscopy (AFM). Adsorption of 1H-benzotriazole on the silver metal surface has been proven by Raman spectroscopy. This work shows the usefulness of additives in improving the quality of metal films electrodeposited from ionic liquids. PMID:22193991

  6. Aqueous Solutions of Ionic Liquids: Microscopic Assembly.

    PubMed

    Vicent-Luna, Jose Manuel; Dubbeldam, David; Gmez-lvarez, Paula; Calero, Sofia

    2016-02-01

    Aqueous solutions of ionic liquids are of special interest, due to the distinctive properties of ionic liquids, in particular, their amphiphilic character. A better understanding of the structure-property relationships of such systems is hence desirable. One of the crucial molecular-level interactions that influences the macroscopic behavior is hydrogen bonding. In this work, we conduct molecular dynamics simulations to investigate the effects of ionic liquids on the hydrogen-bond network of water in dilute aqueous solutions of ionic liquids with various combinations of cations and anions. Calculations are performed for imidazolium-based cations with alkyl chains of different lengths and for a variety of anions, namely, [Br](-) , [NO3 ](-) , [SCN](-) , [BF4 ](-) , [PF6 ](-) , and [Tf2 N](-) . The structure of water and the water-ionic liquid interactions involved in the formation of a heterogeneous network are analyzed by using radial distribution functions and hydrogen-bond statistics. To this end, we employ the geometric criterion of the hydrogen-bond definition and it is shown that the structure of water is sensitive to the amount of ionic liquid and to the anion type. In particular, [SCN](-) and [Tf2 N](-) were found to be the most hydrophilic and hydrophobic anions, respectively. Conversely, the cation chain length did not influence the results. PMID:26641024

  7. Dual Ionic and Organic Nature of Ionic Liquids

    NASA Astrophysics Data System (ADS)

    Shi, Rui; Wang, Yanting

    2016-01-01

    Inherited the advantages of inorganic salts and organic solvents, ionic liquids (ILs) exhibit many superior properties allowing them promising green solvents for the future. Although it has been widely acknowledged that the unique features of ILs originate from their dual ionic and organic nature, its microscopic physical origin still remains blurry. In this work, by comparing the ion/molecule cage structures obtained from molecular dynamics simulations for seven prototypic liquidsa molten inorganic salt, four ILs, a strongly polar organic solvent, and a weakly polar organic solvent, we have revealed that the depth of the cage energy landscape characterizes the ionic nature of ILs, whereas the slope and curvature of its mimimum determine the organic nature of ILs. This finding advances our understanding of ILs and thus will help their efficient utilization as well as the systematic design of novel functionalized ILs.

  8. Dual Ionic and Organic Nature of Ionic Liquids.

    PubMed

    Shi, Rui; Wang, Yanting

    2016-01-01

    Inherited the advantages of inorganic salts and organic solvents, ionic liquids (ILs) exhibit many superior properties allowing them promising green solvents for the future. Although it has been widely acknowledged that the unique features of ILs originate from their dual ionic and organic nature, its microscopic physical origin still remains blurry. In this work, by comparing the ion/molecule cage structures obtained from molecular dynamics simulations for seven prototypic liquids-a molten inorganic salt, four ILs, a strongly polar organic solvent, and a weakly polar organic solvent, we have revealed that the depth of the cage energy landscape characterizes the ionic nature of ILs, whereas the slope and curvature of its mimimum determine the organic nature of ILs. This finding advances our understanding of ILs and thus will help their efficient utilization as well as the systematic design of novel functionalized ILs. PMID:26782660

  9. Ionomer-Liquid Electrolyte Hybrid Ionic Conductor for High Cycling Stability of Lithium Metal Electrodes

    PubMed Central

    Song, Jongchan; Lee, Hongkyung; Choo, Min-Ju; Park, Jung-Ki; Kim, Hee-Tak

    2015-01-01

    The inhomogeneous Li electrodeposition of lithium metal electrode has been a major impediment to the realization of rechargeable lithium metal batteries. Although single ion conducting ionomers can induce more homogeneous Li electrodeposition by preventing Li+ depletion at Li surface, currently available materials do not allow room-temperature operation due to their low room temperature conductivities. In the paper, we report that a highly conductive ionomer/liquid electrolyte hybrid layer tightly laminated on Li metal electrode can realize stable Li electrodeposition at high current densities up to 10 mA cm−2 and permit room-temperature operation of corresponding Li metal batteries with low polarizations. The hybrid layer is fabricated by laminating few micron-thick Nafion layer on Li metal electrode followed by soaking 1 M LiPF6 EC/DEC (1/1) electrolyte. The Li/Li symmetric cell with the hybrid layer stably operates at a high current density of 10 mA cm−2 for more than 2000 h, which corresponds to more than five-fold enhancement compared with bare Li metal electrode. Also, the prototype Li/LiCoO2 battery with the hybrid layer offers cycling stability more than 350 cycles. These results demonstrate that the hybrid strategy successfully combines the advantages of bi-ionic liquid electrolyte (fast Li+ transport) and single ionic ionomer (prevention of Li+ depletion). PMID:26411701

  10. Ionomer-Liquid Electrolyte Hybrid Ionic Conductor for High Cycling Stability of Lithium Metal Electrodes.

    PubMed

    Song, Jongchan; Lee, Hongkyung; Choo, Min-Ju; Park, Jung-Ki; Kim, Hee-Tak

    2015-01-01

    The inhomogeneous Li electrodeposition of lithium metal electrode has been a major impediment to the realization of rechargeable lithium metal batteries. Although single ion conducting ionomers can induce more homogeneous Li electrodeposition by preventing Li(+) depletion at Li surface, currently available materials do not allow room-temperature operation due to their low room temperature conductivities. In the paper, we report that a highly conductive ionomer/liquid electrolyte hybrid layer tightly laminated on Li metal electrode can realize stable Li electrodeposition at high current densities up to 10 mA cm(-2) and permit room-temperature operation of corresponding Li metal batteries with low polarizations. The hybrid layer is fabricated by laminating few micron-thick Nafion layer on Li metal electrode followed by soaking 1 M LiPF6 EC/DEC (1/1) electrolyte. The Li/Li symmetric cell with the hybrid layer stably operates at a high current density of 10 mA cm(-2) for more than 2000 h, which corresponds to more than five-fold enhancement compared with bare Li metal electrode. Also, the prototype Li/LiCoO2 battery with the hybrid layer offers cycling stability more than 350 cycles. These results demonstrate that the hybrid strategy successfully combines the advantages of bi-ionic liquid electrolyte (fast Li(+) transport) and single ionic ionomer (prevention of Li(+) depletion). PMID:26411701

  11. Vesicles and reverse vesicles of an ionic liquid in ionic liquids.

    PubMed

    Rao, K Srinivasa; So, Soonyong; Kumar, Arvind

    2013-09-21

    First evidence and the mechanism of formation of closed bilayer structures by a single chain amino acid ionic liquid (IL), L-proline isopropylester laurylsulfate in both hydrophilic and hydrophobic ILs, is reported. Such ionic self-assemblies are shown to be guided by fine balance of solvophobic effects and ionic arrangements via hydrogen bonding and electrostatic interactions. PMID:23917547

  12. Electrodeposition of nano- and microcrystalline aluminium in three different air and water stable ionic liquids.

    PubMed

    Zein El Abedin, S; Moustafa, E M; Hempelmann, R; Natter, H; Endres, F

    2006-07-17

    The present work shows, for the first time, a comparative experimental study on the electrodeposition of aluminium in three different water and air stable ionic liquids, namely 1-butyl-1-methylpyrrolidinium-bis(trifluoromethylsulfonyl)imide ([BMP]Tf2N), 1-ethyl-3-methylimidazolium-bis(trifluoromethylsulfonyl)imide ([EMIm] Tf2N), and trihexyl-tetradecyl-phosphoniumbis(trifluoromethylsulfonyl)imide (P(14,6,6,6) Tf2N). The ionic liquids [BMP]Tf2N and [EMIm]Tf2N show biphasic behaviour in the AlCl3 concentration range from 1.6 to 2.5 mol L(-1) and 2.5 to 5 mol L(-1), respectively. The biphasic mixtures become monophasic at temperatures >/=80 degrees C. It was found that nanocrystalline aluminium can be electrodeposited in the ionic liquid [BMP]Tf2N saturated with AlCl3. The deposits obtained are generally uniform, dense, shining, and adherent with very fine crystallites in the nanometer size regime. However, coarse cubic-shaped aluminium particles in the micrometer range are obtained in the ionic liquid [EMIm]Tf2N. In this liquid the particle size significantly increases as the temperature rises. A very thin, mirrorlike aluminium film containing very fine crystallites of about 20 nm is obtained in the ionic liquid [trihexyl-tetradecyl-phosphonium]Tf(2)N at room temperature. At 150 degrees C, the average grain size is found to be 35 nm. PMID:16789040

  13. Ionic liquid based electrolytes for sodium-ion batteries: Na+ solvation and ionic conductivity

    NASA Astrophysics Data System (ADS)

    Monti, Damien; Jnsson, Erlendur; Palacn, M. Rosa; Johansson, Patrik

    2014-01-01

    Ionic liquid (IL) based sodium-ion (Na+) battery electrolytes obtained by mixing imidazolium-TFSI ILs (EMIm-TFSI and BMIm-TFSI) with the corresponding sodium salt (NaTFSI) have been investigated using a wide range of characterization techniques: dielectric spectroscopy, differential scanning calorimetry, densitometry, viscometry, and Raman spectroscopy. The sodium ion conducting electrolytes exhibit excellent ionic conductivities, up to 5.5 mS cm-1 at room temperature, and a useful thermal window of -86 C to 150 C. In more detail, Raman data analysis supported by DFT calculations on Na+-TFSI complexes, allow us to determine the sodium ion solvation and charge carrier nature as a function of salt concentration. The results are compared to data for the corresponding Li systems and while such electrolytes essentially form [Li(TFSI)2]- as the main Li+ carrier, the sodium systems seem to dominantly form [Na(TFSI)3]2- complexes. The effects on conductivity and viscosity and the consequences for sodium-ion battery implementation are discussed.

  14. Electrorecovery of actinides at room temperature

    SciTech Connect

    Stoll, Michael E; Oldham, Warren J; Costa, David A

    2008-01-01

    There are a large number of purification and processing operations involving actinide species that rely on high-temperature molten salts as the solvent medium. One such application is the electrorefining of impure actinide metals to provide high purity material for subsequent applications. There are some drawbacks to the electrodeposition of actinides in molten salts including relatively low yields, lack of accurate potential control, maintaining efficiency in a highly corrosive environment, and failed runs. With these issues in mind we have been investigating the electrodeposition of actinide metals, mainly uranium, from room temperature ionic liquids (RTILs) and relatively high-boiling organic solvents. The RTILs we have focused on are comprised of 1,3-dialkylimidazolium or quaternary ammonium cations and mainly the {sup -}N(SO{sub 2}CF{sub 3}){sub 2} anion [bis(trif1uoromethylsulfonyl)imide {equivalent_to} {sup -}NTf{sub 2}]. These materials represent a class of solvents that possess great potential for use in applications employing electrochemical procedures. In order to ascertain the feasibility of using RTILs for bulk electrodeposition of actinide metals our research team has been exploring the electron transfer behavior of simple coordination complexes of uranium dissolved in the RTIL solutions. More recently we have begun some fundamental electrochemical studies on the behavior of uranium and plutonium complexes in the organic solvents N-methylpyrrolidone (NMP) and dimethylsulfoxide (DMSO). Our most recent results concerning electrodeposition will be presented in this account. The electrochemical behavior of U(IV) and U(III) species in RTILs and the relatively low vapor pressure solvents NMP and DMSO is described. These studies have been ongoing in our laboratory to uncover conditions that will lead to the successful bulk electrodeposition of actinide metals at a working electrode surface at room temperature or slightly elevated temperatures. The RTILs we have focused on thus far are based on 1,3-dialkylimidazolium or quaternary ammonium cations and {sup -}N(SO{sub 2}CF{sub 3}){sub 2} anions. Our results from XPS studies of e1ectrooxidized uranium metal surfaces indicate that uranium metal reacts with the anion from the RTIL, most likely through an initial f1uoride abstraction, forming decomposition products that inhibit the bulk electrodeposition of uranium metal. Similar results were found when the organic solvents were used with TBA[B(C{sub 6}F{sub 5}){sub 4}] as the supporting electrolyte, although the voltammetric data of uranium ions in these solutions is more encouraging in relation to electrodeposition of uranium metal. Preliminary results on the voltammetric behavior and bulk electrodeposition of plutonium species are also presented.

  15. Effects of hydrophobic aggregation on the charge transport mechanism of quaternary ammonium ionic liquids

    NASA Astrophysics Data System (ADS)

    Griffin, Philip; Holt, Adam; Wang, Yangyang; Novikov, Vladimir; Sangoro, Joshua; Sokolov, Alexei

    2014-03-01

    Aprotic quaternary ammonium ionic liquids (ILs) are an important class of ILs due to their large electrochemical window and hydrophobicity. However, many of these ILs suffer from relatively low conductivity at room temperature which limits their use in electrochemical applications. In order to understand the nature of this low conductivity and its relation to the chemical structure of the alkyl ammonium cation, we have measured the charge transport properties and structural dynamics of the room temperature ionic liquid methyltrioctylammonium bistriflimide [m3oa][ntf2] over a broad temperature range using dielectric spectroscopy, dynamic light scattering, rheology, and pulsed field gradient nuclear magnetic resonance. We demonstrate that the low values of dc conductivity are due to the combined effects of significantly reduced ion mobility as well as reduced free ion concentration relative to other types of ILs. Secondly we find evidence for a mesoscopic scale structural relaxation process that we attribute to the reorientational motion of nanometer sized alkyl nanodomains. These two findings indicate that hydrophobic aggregation plays an important role in the charge transport mechanism of aprotic ammonium ionic liquids with long aliphatic side chains.

  16. Synthesis of monodisperse Cu nanoparticles in Ionic Liquids: A synthetic and catalytic approach of in situ nanoparticles

    NASA Astrophysics Data System (ADS)

    Mohan, Balaji; Woo, Hyunje; Jang, Seongwan; Lee, Seungwan; Park, Sungkyun; Park, Kang Hyun

    2013-08-01

    We described herein the importance of Ionic Liquids to synthesize in situ monodisperse copper nanoparticles with high surface area at room temperature. The in situ formed nanoparticles were characterized by Transmission Electron Microscopy (TEM), Energy-dispersive spectrometer (EDS) and X-ray powder diffraction (XRD) and shows excellent catalytic activity for cycloaddition reaction between azides with terminal alkynes to furnish 1,4-triazoles in excellent yields under mild conditions. The present catalytic system can take advantage of both ionic liquids and nanoparticles. The proposed catalytic system can minimize the time to synthesize copper nanoparticles with stabilizer and eliminates additional additives as well.

  17. Isotachophoretic separation of selected imidazolium ionic liquids.

    PubMed

    Kosobucki, Przemys?aw; Buszewski, Bogus?aw

    2008-02-15

    Results of determination of selected imidazolium ionic liquids by isotachophoresis (ITP) with conductometric detection was presented. The effects of the molar mass of different ionic liquids on electrophoretic mobility was observed. The presented method was validated and basic validation parameters were determined. Limit of detection (LOD) in a 10 and 25ng/L for anions and cations, respectively, is very satisfied. Thanks to its low cost and high rate, the presented method can be used in qualitative routine analysis as an alternative technique to liquid chromatography. PMID:18371834

  18. Dual Ionic and Organic Nature of Ionic Liquids

    PubMed Central

    Shi, Rui; Wang, Yanting

    2016-01-01

    Inherited the advantages of inorganic salts and organic solvents, ionic liquids (ILs) exhibit many superior properties allowing them promising green solvents for the future. Although it has been widely acknowledged that the unique features of ILs originate from their dual ionic and organic nature, its microscopic physical origin still remains blurry. In this work, by comparing the ion/molecule cage structures obtained from molecular dynamics simulations for seven prototypic liquids—a molten inorganic salt, four ILs, a strongly polar organic solvent, and a weakly polar organic solvent, we have revealed that the depth of the cage energy landscape characterizes the ionic nature of ILs, whereas the slope and curvature of its mimimum determine the organic nature of ILs. This finding advances our understanding of ILs and thus will help their efficient utilization as well as the systematic design of novel functionalized ILs. PMID:26782660

  19. Water in ionic liquids at electrified interfaces: the anatomy of electrosorption.

    PubMed

    Feng, Guang; Jiang, Xikai; Qiao, Rui; Kornyshev, Alexei A

    2014-11-25

    Complete removal of water from room-temperature ionic liquids is nearly impossible. For the electrochemical applications of ionic liquids, how water is distributed in the electrical double layers when the bulk liquids are not perfectly dry can potentially determine whether key advantages of ionic liquids, such as a wide electrochemical window, can be harnessed in practical systems. In this paper, we study the adsorption of water on electrode surfaces in contact with humid, imidazolium-based ionic liquids using molecular dynamics simulations. The results revealed that water molecules tend to accumulate within sub-nanometer distance from charged electrodes. At low amount of water in the bulk, the distributions of ions and of electrostatic potential in the double layer are affected weakly by the presence of water, but the spatial distribution of water molecules is strongly dependent on both. The preferential positions of water molecules in double layers are determined by the balance of several factors: the tendency to follow the positions of the maximal absolute value of the electrical field, the association with their ionic surroundings, and the propensity to settle at positions where more free space is available. The balance between these factors changes with charging the electrode, but the adsorption of water generally increases with voltage. The ion specificity of water electrosorption is manifested in the stronger presence of water near positive electrodes (where anions are the counterions) than near negative electrodes (where cations are counterions). These predictions await experimental verification. PMID:25341189

  20. Ionic Liquids for Utilization of Waste Heat from Distributed Power Generation Systems

    SciTech Connect

    Joan F. Brennecke; Mihir Sen; Edward J. Maginn; Samuel Paolucci; Mark A. Stadtherr; Peter T. Disser; Mike Zdyb

    2009-01-11

    The objective of this research project was the development of ionic liquids to capture and utilize waste heat from distributed power generation systems. Ionic Liquids (ILs) are organic salts that are liquid at room temperature and they have the potential to make fundamental and far-reaching changes in the way we use energy. In particular, the focus of this project was fundamental research on the potential use of IL/CO2 mixtures in absorption-refrigeration systems. Such systems can provide cooling by utilizing waste heat from various sources, including distributed power generation. The basic objectives of the research were to design and synthesize ILs appropriate for the task, to measure and model thermophysical properties and phase behavior of ILs and IL/CO2 mixtures, and to model the performance of IL/CO2 absorption-refrigeration systems.

  1. Microwave-assisted liquid-liquid microextraction based on solidification of ionic liquid for the determination of sulfonamides in environmental water samples.

    PubMed

    Song, Ying; Wu, Lijie; Lu, Chunmei; Li, Na; Hu, Mingzhu; Wang, Ziming

    2014-12-01

    An easy, quick, and green method, microwave-assisted liquid-liquid microextraction based on solidification of ionic liquid, was first developed and applied to the extraction of sulfonamides in environmental water samples. 1-Ethy-3-methylimidazolium hexafluorophosphate, which is a solid-state ionic liquid at room temperature, was used as extraction solvent in the present method. After microwave irradiation for 90 s, the solid-state ionic liquid was melted into liquid phase and used to finish the extraction of the analytes. The ionic liquid and sample matrix can be separated by freezing and centrifuging. Several experimental parameters, including amount of extraction solvent, microwave power and irradiation time, pH of sample solution, and ionic strength, were investigated and optimized. Under the optimum experimental conditions, good linearity was observed in the range of 2.00-400.00 ?g/L with the correlation coefficients ranging from 0.9995 to 0.9999. The limits of detection for sulfathiazole, sulfachlorpyridazine, sulfamethoxazole, and sulfaphenazole were 0.39, 0.33, 0.62, and 0.85 ?g/L, respectively. When the present method was applied to the analysis of environmental water samples, the recoveries of the analytes ranged from 75.09 to 115.78% and relative standard deviations were lower than 11.89%. PMID:25271847

  2. Mesoporous silica/ionic liquid quasi-solid-state electrolytes and their application in lithium metal batteries

    NASA Astrophysics Data System (ADS)

    Li, Xiaowei; Zhang, Zhengxi; Yin, Kun; Yang, Li; Tachibana, Kazuhiro; Hirano, Shin-ichi

    2015-03-01

    In this work, the ordered mesoporous silica, SBA-15, is chosen as the matrix for the first time to prepare quasi-solid-state electrolytes (QSSEs) with an ionic liquid, LiTFSI salt and PVdF-HFP. The as-obtained QSSEs are evaluated by electrochemical methods. Lithium metal batteries containing these QSSEs exhibit high discharge capacity and good cycle performance at room temperature, indicating successful battery operation.

  3. Physicochemical Properties of Imidazolium-derived Ionic Liquids with Different C-2 Substitutions

    SciTech Connect

    Liao, Chen; Shao, Nan; Han, Kee Sung; Sun, Xiao-Guang; Jiang, Deen; Hagaman, Edward {Ed} W; Dai, Sheng

    2011-01-01

    Five room temperature ionic liquids based on C-2 substituted imidazolium cations and bis(trifluoromethanesulfonyl)imide (TFSI) anion were synthesized and their physicochemical properties: thermal property, density, viscosity, ionic conductivity, self-diffusion coefficients, and electrochemical stability were systematically investigated. The temperature dependence of both viscosity and ionic conductivities of these ionic liquids can be described by Vogel-Fulcher-Tamman (VFT) equation. Compared with the reference, 1-propyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide, the introduction of functional groups at the C-2 position generally increased the viscosity and lowered the ionic conductivity. The introduction of ether group ( CH2OCH2CH2CH2CH3) at the C-2 position not only enhanced the reduction stability of the ionic liquids but also exhibited the lowest solid electrolyte interfacial resistance (RSEI). On the contrary, the introduction of a cyano group ( CN) at the C-2 position not only decreased the reduction stability but also adversely increased the SEI resistance. The effect of the C-2 substitution on the reduction stability was explained by the change of the energy level of the lowest unoccupied molecular orbital. The self-diffusion coefficients (D) of each ion were measured by pulsed field gradient nuclear magnetic resonance (PFG-NMR). The lithium transference number (tLi) of 0.5 M LiTFSI/IL solutions calculated from the self-diffusion coefficients was in the range of 0.04 and 0.09.

  4. Enzyme activity in dialkyl phosphate ionic liquids

    SciTech Connect

    Thomas, M.F.; Dunn, J.; Li, L.-L.; Handley-Pendleton, J. M.; van der lelie, D.; Wishart, J. F.

    2011-12-01

    The activity of four metagenomic enzymes and an enzyme cloned from the straw mushroom, Volvariellavolvacea were studied in the following ionic liquids, 1,3-dimethylimidazolium dimethyl phosphate, [mmim][dmp], 1-ethyl-3-methylimidazolium dimethyl phosphate, [emim][dmp], 1-ethyl-3-methylimidazolium diethyl phosphate, [emim][dep] and 1-ethyl-3-methylimidazolium acetate, [emim][OAc]. Activity was determined by analyzing the hydrolysis of para-nitrobenzene carbohydrate derivatives. In general, the enzymes were most active in the dimethyl phosphate ionic liquids, followed by acetate. Generally speaking, activity decreased sharply for concentrations of [emim][dep] above 10% v/v, while the other ionic liquids showed less impact on activity up to 20% v/v.

  5. Polyester Spherulite Crystallization in Ionic Liquids

    NASA Astrophysics Data System (ADS)

    Singfield, Kathy; Mitchell, Shawna

    2009-03-01

    A series of polyesters have been crystallized in ionic liquids. Spherulites of the polyesters have been grown isothermally from different ionic liquids after cooling the single phase polymer/ionic liquid system from above the polymer melting point temperature. To the authors' best knowledge this is the first reported account of polyester spherulites grown from these non-traditional solvents. The combination of physical properties of the crystallizing system supports the un-restrained branching/splitting volume-filling growth in all radial directions of the suspended crystallizing entity. The morphology of the collected spherulites at various stages of their formation was examined using scanning electron microscopy (SEM). The SEM results provide a clear visual inspection of the early-stage growth forms and the branching/splitting patterns involved in their evolution to the final spherical form.

  6. TETRAALKYLPHOSPHONIUM POLYOXOMETALATES AS NOVEL IONIC LIQUIDS.

    SciTech Connect

    DIETZ,M.L.; RICKERT, P.G.; ANTONIO, M.R.; FIRESTONE, M.A.; WISHART, J.F.; SZREDER, T.

    2007-11-30

    The pairing of a Lindqvist or Keggin polyoxometalate (POM) anion with an appropriate tetraalkylphosphonium cation, [R{sub 3}R{prime}P]{sup +}, has been shown to yield an original family of ionic liquids (POM-ILs), among them salts liquid at or near ambient temperature. The physicochemical properties of several such 'inorganic liquids', in particular their thermal properties, suggests the possible application of these compounds as robust, thermally-stable solvents for liquid-liquid extraction. A preliminary evaluation of the potential of POM-ILs in this application is presented.

  7. Energy Efficient Electrochromic Windows Incorporating Ionic Liquids

    SciTech Connect

    Cheri Boykin; James Finley; Donald Anthony; Julianna Knowles; Richard Markovic; Michael Buchanan; Mary Ann Fuhry; Lisa Perrine

    2008-11-30

    One approach to increasing the energy efficiency of windows is to control the amount of solar radiation transmitted through a window by using electrochromic technology. What is unique about this project is that the electrochromic is based on the reduction/oxidation reactions of cathodic and anodic organic semi-conducting polymers using room temperature ionic liquids as ion transport electrolytes. It is believed that these types of coatings would be a lower cost alternative to traditional all inorganic thin film based electrochromic technologies. Although there are patents1 based on the proposed technology, it has never been reduced to practice and thoroughly evaluated (i.e. durability and performance) in a window application. We demonstrate that by using organic semi-conductive polymers, specific bands of the solar spectrum (specifically visible and near infrared) can be targeted for electrochemical variable transmittance responsiveness. In addition, when the technology is incorporated into an insulating glass unit, the energy parameters such as the solar heat gain coefficient and the light to solar gain ratio are improved over that of a typical insulating glass unit comprised of glass with a low emissivity coating. A minimum of {approx}0.02 quads of energy savings per year with a reduction of carbon emissions for electricity of {approx}320 MKg/yr benefit is achieved over that of a typical insulating glass unit including a double silver low-E coating. Note that these values include a penalty in the heating season. If this penalty is removed (i.e. in southern climates or commercial structures where cooling is predominate year-round) a maximum energy savings of {approx}0.05 quad per year and {approx}801 MKg/yr can be achieved over that of a typical insulating glass unit including a double silver low-E coating. In its current state, the technology is not durable enough for an exterior window application. The primary downfall is that the redox chemistry fails to recover to a bleached state upon exposure to heat and solar radiation while being cycled over time from the bleached to the dark state. Most likely the polymers are undergoing degradation reactions which are accelerated by heat and solar exposure while in either the reduced or oxidized states and the performance of the polymers is greatly reduced over time. For this technology to succeed in an exterior window application, there needs to be more work done to understand the degradation of the polymers under real-life application conditions such as elevated temperatures and solar exposure so that recommendations for improvements in to the overall system can be made. This will be the key to utilizing this type of technology in any future real-life applications.

  8. Hydrogen production by water electrolysis using tetra-alkyl-ammonium-sulfonic acid ionic liquid electrolytes

    NASA Astrophysics Data System (ADS)

    Fiegenbaum, Fernanda; Martini, Emilse M.; de Souza, Michle O.; Becker, Mrcia R.; de Souza, Roberto F.

    2013-12-01

    Triethylammonium-propanesulfonic acid tetrafluoroborate (TEA-PSBF4) is used as an electrolyte in the water electrolysis. The electrolysis of water with this ionic conductor produces high current densities with high efficiencies, even at room temperatures. A system using TEA-PSBF4 in an electrochemical cell with platinum electrodes has current densities (i) up to 1.77 A cm-2 and efficiencies between 93 and 99% in temperatures ranging from 25 C to 80 C. The activation energy observed with TEA-PSBF4 is ca. 9.3 kJ mol-1, a low value that can be explained by the facilitation of proton transport in the organised aqueous ionic liquid media. The unexpectedly high efficiency of this system is discussed by taking into account the high conductivities associated with the Brnsted and Lewis acidity characteristics associated with these ionic conductive materials.

  9. Improved adhesive for cryogenic applications cures at room temperature

    NASA Technical Reports Server (NTRS)

    Klinger, H. J.; Smith, M. B.

    1966-01-01

    Adhesive cured at room temperature provides an effective adhesive bond over the range from room temperature down to the temperature of liquid hydrogen. The adhesive consists of one part of 200-mesh powdered nylon filler to two parts of an epoxy-polyamine resin.

  10. Unusual redox stability of neptunium in the ionic liquid [Hbet][Tf(2)N].

    PubMed

    Long, Kristy; Goff, George; Runde, Wolfgang

    2014-07-25

    The behavior of neptunium in the ionic liquid betaine bistriflimide, [Hbet][Tf2N], has been studied spectroscopically at room temperature and 60 °C for the first time. An unprecedented complex redox chemistry is observed, with up to three oxidation states (iv, v and vi) and up to six Np species existing simultaneously. Both redox reactions and coordination of betaine are observed for Np(iv), (v) and (vi). Elevating the temperature accelerates the coordination of Np(v) with betaine and reduction reactions slow down. PMID:24752760

  11. The thiocyanate anion is a primary driver of carbon dioxide capture by ionic liquids

    NASA Astrophysics Data System (ADS)

    Chaban, Vitaly

    2015-01-01

    Carbon dioxide, CO2, capture by room-temperature ionic liquids (RTILs) is a vivid research area featuring both accomplishments and frustrations. This work employs the PM7-MD method to simulate adsorption of CO2 by 1,3-dimethylimidazolium thiocyanate at 300 K. The obtained result evidences that the thiocyanate anion plays a key role in gas capture, whereas the impact of the 1,3-dimethylimidazolium cation is mediocre. Decomposition of the computed wave function on the individual molecular orbitals confirms that CO2-SCN binding extends beyond just expected electrostatic interactions in the ion-molecular system and involves partial sharing of valence orbitals.

  12. Photoinduced anisotropy in an azo-containing ionic liquid-crystalline polymer

    NASA Astrophysics Data System (ADS)

    Pan, Xu; Xiao, Sufang; Wang, Changshun; Cai, Peng; Lu, Xuemin; Lu, Qinghua

    2009-03-01

    Photoinduced anisotropy in an azobenzene ionic liquid-crystalline polymer was investigated through dichroism, birefringence and polarization holography. A dichroism degree of 1.58 and a birefringence value ?n ? 10-2 were achieved in the polymer film at room temperature, and the polymer film was found to possess the characteristics of reversible and long-term optical storage. Particularly the stored birefringence could be enhanced to ?n ? 10-1 by annealing the film, and it is attributed to the thermal self-organization of the molecules. Furthermore, linear- and circular-polarization holographic recordings were accomplished in the polymer film and pure polarization gratings were produced.

  13. Unravelling nanoconfined films of ionic liquids

    SciTech Connect

    Lee, Alpha A.; Vella, Dominic; Goriely, Alain; Perkin, Susan

    2014-09-07

    The confinement of an ionic liquid between charged solid surfaces is treated using an exactly solvable 1D Coulomb gas model. The theory highlights the importance of two dimensionless parameters: the fugacity of the ionic liquid, and the electrostatic interaction energy of ions at closest approach, in determining how the disjoining pressure exerted on the walls depends on the geometrical confinement. Our theory reveals that thermodynamic fluctuations play a vital role in the squeezing out of charged layers as the confinement is increased. The model shows good qualitative agreement with previous experimental data, with all parameters independently estimated without fitting.

  14. Evaluation of Vapor Pressure and Ultra-High Vacuum Tribological Properties of Ionic Liquids (2) Mixtures and Additives

    NASA Technical Reports Server (NTRS)

    Morales, Wilfredo; Koch, Victor R.; Street, Kenneth W., Jr.; Richard, Ryan M.

    2008-01-01

    Ionic liquids are salts, many of which are typically viscous fluids at room temperature. The fluids are characterized by negligible vapor pressures under ambient conditions. These properties have led us to study the effectiveness of ionic liquids containing both organic cations and anions for use as space lubricants. In the previous paper we have measured the vapor pressure and some tribological properties of two distinct ionic liquids under simulated space conditions. In this paper we will present vapor pressure measurements for two new ionic liquids and friction coefficient data for boundary lubrication conditions in a spiral orbit tribometer using stainless steel tribocouples. In addition we present the first tribological data on mixed ionic liquids and an ionic liquid additive. Post mortem infrared and Raman analysis of the balls and races indicates the major degradation pathway for these two organic ionic liquids is similar to those of other carbon based lubricants, i.e. deterioration of the organic structure into amorphous graphitic carbon. The coefficients of friction and lifetimes of these lubricants are comparable to or exceed these properties for several commonly used space oils.

  15. CHARACTERIZATION AND COMPARISON OF HYDROPHILIC AND HYDROPHOBIC ROOM TEMPERATURE IONIC LIQUIDS INCORPORATING THE IMIDAZOLIUM CATION. (R828257)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  16. Saturation properties of 1-alkyl-3-methylimidazolium based ionic liquids.

    PubMed

    Rane, Kaustubh S; Errington, Jeffrey R

    2014-07-24

    We study the liquid-vapor saturation properties of room temperature ionic liquids (RTILs) belonging to the homologous series 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Cnmim][NTf2]) using Monte Carlo simulation. We examine the effect of temperature and cation alkyl chain length n on the saturated densities, vapor pressures, and enthalpies of vaporization. These properties are explicitly calculated for temperatures spanning from 280 to 1000 K for RTILs with n = 2, 4, 6, 8, 10, and 12. We also explore how the identity of the anion influences saturation properties. Specifically, we compare results for [C(4)mim][NTf2] with those for 1-butyl-3-methylimidazolium tetrafluoroborate ([C(4)mim][BF4]) and 1-butyl-3-methylimidazolium hexafluorophosphate ([C(4)mim][PF6]). Simulations are completed with a recently developed realistic united-atom force field. A combination of direct grand canonical and isothermal-isobaric temperature expanded ensemble simulations are used to construct phase diagrams. Our results are compared with experimental data and Gibbs ensemble simulation data. Overall, we find good agreement between our results and those measured experimentally. We find that the vapor pressures and enthalpies of vaporization show a strong dependence on the size of the alkyl chain at low temperatures, whereas no particular trend is observed at high temperatures. Finally, we also discuss the effect of temperature on liquid phase nanodomains observed in RTILs with large hydrophobic groups. We do not observe a drastic change in liquid phase structure upon variation of the temperature, which suggests there is not a sharp phase transition between a nanostructured and homogeneous liquid, as has been suggested in earlier studies. PMID:24986360

  17. Taylor cones of ionic liquids from capillary tubes as sources of pure ions: The role of surface tension and electrical conductivity

    NASA Astrophysics Data System (ADS)

    Garoz, D.; Bueno, C.; Larriba, C.; Castro, S.; Romero-Sanz, I.; Fernandez de la Mora, J.; Yoshida, Y.; Saito, G.

    2007-09-01

    The emissions of Taylor cones from a wide range of ionic liquids (ILs) have been tested in vacuo in an attempt to identify what physical properties favor the purely ionic regime (PIR). This regime is well known in the case of Taylor cones of liquid metals. For nonmetallic liquids, it has been previously observed in conventional (capillary tube) electrospray sources at room temperature only for the room temperature molten salt (ionic liquid) EMI -BF4 (EMI =1-ethyl-3-methylimidazolium). A large number of other ILs and their mixtures have been studied here, most of which (but not all) are unable to reach the PIR at room temperature. Based on these results and additional theoretical considerations, strong support is assembled for the notion that the PIR is favored by ILs not only of high electrical conductivity but also of high surface tension. This hypothesis is confirmed by tests with three recently synthesized ILs, EMI -GaCl4, EMI -C(CN)3, and EMI -N(CN)2, all of which combine exceptional surface tension and electrical conductivity, and all of which reach the PIR at room temperature far more readily than EMI -BF4.

  18. A novel mechanism for the extraction of metals from water to ionic liquids.

    PubMed

    Janssen, Camiel H C; Snchez, Antonio; Witkamp, Geert-Jan; Kobrak, Mark N

    2013-11-11

    We present a novel mechanism for the extraction of metals from aqueous phases to room-temperature ionic liquids (ILs) by use of a high-temperature salt as an extraction agent. The mechanism capitalizes on the fact that charged metal complexes are soluble in ILs; this allows for extraction of charged complexes rather than the neutral species, which are formed by conventional approaches. The use of a well-chosen extraction agent also suppresses the competing ion-exchange mechanism, thus preventing degradation of the ionic liquid. The approach permits the use of excess extractant to drive the recovery of metals in high yield. This work presents both a thermodynamic framework for understanding the approach and experimental verification of the process in a range of different ILs. The method has great potential value in the recovery of metals, water purification and nuclear materials processing. PMID:24590618

  19. Electrochemical and physicochemical properties of small phosphonium cation ionic liquid electrolytes with high lithium salt content.

    PubMed

    Girard, G M A; Hilder, M; Zhu, H; Nucciarone, D; Whitbread, K; Zavorine, S; Moser, M; Forsyth, M; MacFarlane, D R; Howlett, P C

    2015-04-14

    Electrolytes of a room temperature ionic liquid (RTIL), trimethyl(isobutyl)phosphonium (P111i4) bis(fluorosulfonyl)imide (FSI) with a wide range of lithium bis(fluorosulfonyl)imide (LiFSI) salt concentrations (up to 3.8 mol kg(-1) of salt in the RTIL) were characterised using a combination of techniques including viscosity, conductivity, differential scanning calorimetry (DSC), electrochemical impedance spectroscopy (EIS), nuclear magnetic resonance (NMR) and cyclic voltammetry (CV). We show that the FSI-based electrolyte containing a high salt concentration (e.g. 1?:?1 salt to IL molar ratio, equivalent to 3.2 mol kg(-1) of LiFSI) displays unusual transport behavior with respect to lithium ion mobility and promising electrochemical behavior, despite an increase in viscosity. These electrolytes could compete with the more traditionally studied nitrogen-based ionic liquids (ILs) in lithium battery applications. PMID:25820549

  20. Capacitive Energy Storage from - 50o to 100o Using an Ionic Liquid Electrolyte

    SciTech Connect

    Lin, Rongying; Taberna, Pierre-Louis; Santini, Sebastien; Presser, Volker; Perez, Carlos R.; Malbosc, Francois; Rupesinghe, Nalin L.; Teo, Kenneth B. K.; Gogotsi, Yury G.; Simon, Patrice

    2011-01-01

    Relying on redox reactions, most batteries are limited in their ability to operate at very low or very high temperatures. While performance of electrochemical capacitors is less dependent on the temperature, present-day devices still cannot cover the entire range needed for automotive and electronics applications under a variety of environmental conditions. We show that the right combination of the exohedral nanostructured carbon (nanotubes and onions) electrode and a eutectic mixture of ionic liquids can dramatically extend the temperature range of electrical energy storage, thus defying the conventional wisdom that ionic liquids can only be used as electrolytes above room temperature. We demonstrate electrical double layer capacitors able to operate from 50 to 100 C over a wide voltage window (up to 3.7 V) and at very high charge/discharge rates of up to 20 V/s.

  1. Synthesis and characterisations of Aliquat 336 and cetylpyridinium ionic liquids incorporated with sulfonate-based anions

    NASA Astrophysics Data System (ADS)

    Wilfred, Cecilia Devi; Nair, G. Divya; Ziyada, Abobakr Khidir

    2012-09-01

    A novel series of ionic liquids based on the tricaprylmethylammonium cation [C25H54N+], in Aliquat 336 and cetylpyridinium cation [C21H38N+] in cetylpyridinium chloride incorporating sulfonate-based anions were elegantly prepared by means of ion exchange between the Cl- cation with two different anions, namely, dioctylsulfosuccinate [DOSS-] and dihexylsulfosuccinate [HOSS-]. These ionic liquids were characterised using FTIR-ATR and NMR in order to identify the molecular structures of these compounds. The physical properties of these compounds, namely refractive index and thermal properties were measured at room temperature and are reported herein. ILs incorporating cetylpyridinium cations show higher thermal stability and refractive index values as compared to Aliquat ILs due to the effects of the aromatic ring on the cetylpyridinium cation as well as the longer alkyl chain on the anion of DOSS.

  2. Spectroscopic study on imidazolium-based ionic liquids: effect of alkyl chain length and anion.

    PubMed

    Binetti, Enrico; Panniello, Annamaria; Triggiani, Leonardo; Tommasi, Raffaele; Agostiano, Angela; Curri, Maria Lucia; Striccoli, Marinella

    2012-03-22

    Room temperature ionic liquids are currently used as functional materials in several application and their optical investigation can provide a better understanding of their physical and chemical behavior. Absorption and emission properties of imidazolium-based ILs have been attributed to the imidazolium moiety and related to the presence of energetically different aggregates. Here, time-integrated and time-resolved investigation has been carried out on 1-alkyl-3-methylimidazolium tetrafluoroborate and hexafluorophosphate ionic liquids with different chain lengths in order to probe the occurrence of energy transfer processes, and hence to disclose the presence of various states with different energy. Such a study contributes to provide relevant insight on the effect of alkyl chain and anion type on the emission characteristics, and, hence, on the presence of associated structures. PMID:22369210

  3. Ionic liquid assisted synthesis of Au-Pd bimetallic particles with enhanced electrocatalytic activity.

    PubMed

    Li, Zhonghao; Li, Rui; Mu, Tiancheng; Luan, Yuxia

    2013-05-01

    Morphology- and composition-controlled synthesis of Au-Pd bimetallic particles was realized by a facile ionic liquid assisted route at room temperature. The morphologies of the synthesized particles, such as nanoflake-constructed spheres with a core-shell structure, nanoparticle-constructed spheres, and nanoparticle-constructed dendrites, could be well controlled by the present route. The ionic liquid was found to play a key role in the formation of these interesting particles. Moreover, the composition (Au:Pd) of the particles could be modulated by means of the molar ratio of the metal precursors in the feeding solutions. The Au-Pd bimetallic particles exhibit high electrocatalytic activity toward oxidation of ethanol and formic acid. Furthermore, cyclic voltammetric studies on the as-prepared Au-Pd bimetallic particles revealed good electroactivity for H2O2, which results in an effective amperometric H2O2 sensor. PMID:23471860

  4. Aza-crown ether complex cation ionic liquids: preparation and applications in organic reactions.

    PubMed

    Song, Yingying; Cheng, Chen; Jing, Huanwang

    2014-09-26

    Aza-crown ether complex cation ionic liquids (aCECILs) were devised, fabricated, and characterized by using NMR spectroscopy, MS, thermogravimetric differential thermal analysis (TG-DTA), elemental analysis and physical properties. These new and room-temperature ILs were utilized as catalysts in various organic reactions, such as the cycloaddition reaction of CO2 to epoxides, esterification of acetic acid and alcohols, the condensation reaction of aniline and propylene carbonate, and Friedel-Crafts alkylation of indole with aldehydes were investigated carefully. In these reactions, the ionic liquid exhibited cooperative catalytic activity between the anion and cation. In addition, the aza-[18-C-6HK][HSO4]2 was the best acidic catalyst in the reactions of esterification and Friedel-Crafts alkylation under mild reaction conditions. PMID:25154312

  5. Anion effects in the extraction of lanthanide 2-thenoyltrifluoroacetone complexes into an ionic liquid

    SciTech Connect

    Jensen, Mark P.; Beitz, James V.; Rickert, Paul G.; Borkowski, Marian; Laszak, Ivan; Dietz, Mark L.

    2012-07-01

    The extraction of trivalent lanthanides from an aqueous phase containing 1 M NaClO{sub 4} into the room temperature ionic liquid 1-butyl-3-methylimidazolium nonafluoro-1-butane sulfonate by the beta-diketone extractant 2-thenoyltrifluoroacetone (Htta) was studied. Radiotracer distribution, absorption spectroscopy, time-resolved laser-induced fluorescence spectroscopy, and X-ray absorption fine structure measurements point to the extraction of multiple lanthanide species. At low extractant concentrations, fully hydrated aqua cations of the lanthanides are present in the ionic liquid phase. As the extractant concentration is increased 1:2 and 1:3 lanthanide:tta species are observed. In contrast, 1:4 Ln:tta complexes were observed in the extraction of lanthanides by Htta into 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide. (authors)

  6. Molecular mechanism of gas adsorption into ionic liquids: A molecular dynamics study

    SciTech Connect

    Dang, Liem X.; Chang, Tsun-Mei

    2012-01-19

    Room temperature ionic liquids (RTILs) have been shown to be versatile and tunable solvents that can be used in many chemical applications. In this study, we developed a dynamical, molecular-scale picture of the gas dissolution and interfacial processes in RTILs using molecular simulations. These simulations can provide the free energies associated with transporting a gas solute across various RTIL interfaces and physical insights into the interfacial properties and transport molecular mechanism of gas sorption processes. For CO2 sorption, the features in the potential of mean force (PMF) of CO2 using both polarizable and non-polarizable force fields are similar qualitatively. However, we observed some quantitative differences, and we describe the causes of these differences in this paper. We also show the significant impact of ionic-liquid chemical structures on the gas sorption process, and we discuss their influence on the H2O transport mechanism.

  7. Anomalous Capacitance Maximum of the Glassy Carbon-Ionic Liquid Interface through Dilution with Organic Solvents.

    PubMed

    Bozym, David J; Uralcan, Betl; Limmer, David T; Pope, Michael A; Szamreta, Nicholas J; Debenedetti, Pablo G; Aksay, Ilhan A

    2015-07-01

    We use electrochemical impedance spectroscopy to measure the effect of diluting a hydrophobic room temperature ionic liquid with miscible organic solvents on the differential capacitance of the glassy carbon-electrolyte interface. We show that the minimum differential capacitance increases with dilution and reaches a maximum value at ionic liquid contents near 5-10 mol% (i.e., ?1 M). We provide evidence that mixtures with 1,2-dichloroethane, a low-dielectric constant solvent, yield the largest gains in capacitance near the open circuit potential when compared against two traditional solvents, acetonitrile and propylene carbonate. To provide a fundamental basis for these observations, we use a coarse-grained model to relate structural variations at the double layer to the occurrence of the maximum. Our results reveal the potential for the enhancement of double-layer capacitance through dilution. PMID:26266747

  8. Polyoxometalate ionic liquids as self-repairing acid-resistant corrosion protection.

    PubMed

    Herrmann, Sven; Kostrzewa, Monika; Wierschem, Andreas; Streb, Carsten

    2014-12-01

    Corrosion is a global problem for any metallic structure or material. Herein we show how metals can easily be protected against acid corrosion using hydrophobic polyoxometalate-based ionic liquids (POM-ILs). Copper metal disks were coated with room-temperature POM-ILs composed of transition-metal functionalized Keggin anions [SiW11 O39 TM(H2 O)](n-) (TM=Cu(II) , Fe(III) ) and quaternary alkylammonium cations (Cn H2?n+1 )4 N(+) (n=7-8). The corrosion resistance against acetic acid vapors and simulated "acid rain" was significantly improved compared with commercial ionic liquids or solid polyoxometalate coatings. Mechanical damage to the POM-IL coating is self-repaired in less than one minute with full retention of the acid protection properties. The coating can easily be removed and recovered by rinsing with organic solvents. PMID:25332068

  9. Testing Fundamental Properties of Ionic Liquids for Colloid Microthruster Applications

    NASA Technical Reports Server (NTRS)

    Anderson, John R.; Plett, Gary; Anderson, Mark; Ziemer, John

    2006-01-01

    NASA's New Millennium Program is scheduled to test a Disturbance Reduction System (DRS) on Space Technology 7 (ST7) as part of the European Space Agency's (ESA's) LISA Pathfinder Mission in late 2009. Colloid Micronewton Thrusters (CMNTs) will be used to counteract forces, mainly solar photon pressure, that could disturb gravitational reference sensors as part of the DRS. The micronewton thrusters use an ionic liquid, a room temperature molten salt, as propellant. The ionic liquid has a number of unusual properties that have a direct impact on thruster design. One of the most important issues is bubble formation before and during operation, especially during rapid pressure transitions from atmospheric to vacuum conditions. Bubbles have been observed in the feed system causing variations in propellant flow rate that can adversely affect thruster control. Bubbles in the feed system can also increase the likelihood that propellant will spray onto surfaces that can eventually lead to shorting high voltage electrodes. Two approaches, reducing the probability of bubble formation and removing bubbles with a new bubble eliminator device in the flow system, were investigated at Busek Co., Inc. and the Jet Propulsion Laboratory (JPL) to determine the effectiveness of both approaches. Results show that bubble formation is mainly caused by operation at low pressure and volatile contaminants in the propellant coming out of solution. A specification for the maximum tolerable level of contamination has been developed, and procedures for providing system cleanliness have been tested and implemented. The bubble eliminator device has also been tested successfully and has been implemented in recent thruster designs at Busek. This paper focuses on the propellant testing work at JPL, including testing of a breadboard level bubble eliminator device.

  10. EXPEDITIOUS SYNTHESIS OF IONIC LIQUIDS USING ULTRASOUND AND MICROWAVE IRRADIATION

    EPA Science Inventory

    Environmentally friendlier preparations of ionic liquids have been developed that proceed expeditiously under the influence of microwave or ultrasound irradiation conditions using neat reactants, alkylimidazoles and alkyl halides. A number of useful ionic liquids have been prepar...

  11. Reactions of Starch in Ionic Liquids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We found that starches are found to be soluble at 80 C in ionic liquids such as 1-butyl-3-methylimidazolium chloride (BMIMCl) and 1-butyl-3-methylimidazolium dicyanamide (BMIMdca) in concentration up to 10% (w/w). Higher concentrations of biopolymers in these novel solvents resulted in solutions w...

  12. Thermoresponsive poly(ionic liquid) hydrogels.

    PubMed

    Zi?kowski, Bartosz; Diamond, Dermot

    2013-11-11

    A new series of LCST ILs have been copolymerised with crosslinkers of varying length to afford the first ever thermoresponsive poly(ionic liquid)-based hydrogels. These hydrogels exhibit surprisingly broad LCST and volume transition behaviour compared to standard thermoresponsive gels and linear ILs. PMID:24064665

  13. Ionic liquid electrolytes for reversible magnesium electrochemistry.

    PubMed

    Kar, Mega; Ma, Zheng; Azofra, Luis Miguel; Chen, Kun; Forsyth, Maria; MacFarlane, Douglas R

    2016-03-01

    Mg has great potential as the basis for a safe, low cost energy storage technology, however, cycling of magnesium is difficult to achieve in most electrolytes. We demonstrate cycling of Mg from a novel alkoxyammonium ionic liquid. DFT calculations highlight the role that Mg coordination with [BH4](-) ions plays in the mechanism. PMID:26888053

  14. Cellulose regeneration and spinnability from ionic liquids.

    PubMed

    Hauru, Lauri K J; Hummel, Michael; Nieminen, Kaarlo; Michud, Anne; Sixta, Herbert

    2016-02-01

    Ionic liquid solutions of cellulose or dopes can be spun into Lyocell-type textile fibers by dry-jet wet spinning. An extruded dope is drawn over an air gap into water, where the water hydrates the ionic liquid and cellulose is regenerated. Spinnability studies have concentrated on the deformation and failure modes in the air gap and thus the rheology of the unhydrated spinning dope. Herein, a breach in the bath, another failure mode, is discussed. Dopes are prepared from the good spinning solvents NMMO·H2O and [DBNH]OAc and the poor spinning solvents [emim]OAc and [TMGH]OAc. The diffusion constants for water diffusing inwards and for ionic liquid diffusing outwards the emerging filament are measured offline. The resiliences and strengths of cellulose-ionic liquid solutions with different hydration stoichiometries are measured by means of rheometry. By calculating the diffusion dynamics, the resilience distribution of the forming filament is simulated. Gel strength distribution accounts for the tendency of [emim]OAc dopes to undergo a telescope-type breach, whereas the gelatinous solution state of [TMGH]OAc dopes accounts for their poor spinnability. PMID:26660047

  15. Solvation and Reaction in Ionic Liquids

    SciTech Connect

    Maroncelli, Mark

    2015-01-15

    The long-range goal of our DOE-sponsored research is to obtain a fundamental understanding of solvation effects on photo-induced charge transfer and related processes. Much of the focus during the past funding period has been on studies of ionic liquids and on characterizing various reactions with which to probe the nature of this interesting new solvent medium.

  16. Esterification of Starch in Ionic Liquids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We shall discuss the use of various ionic liquids in the preparation of starch esters. Starch was reacted with vinyl acetate in different 1-butyl-3-methylimidazolium (bmim) salts as solvents in an effort to produce starches with different acetylation patterns. Overall degree of substitution (DS) w...

  17. 1,2,3-triazolium ionic liquids

    SciTech Connect

    Luebke, David; Nulwala, Hunaid; Tang, Chau

    2014-12-09

    The present invention relates to compositions of matter that are ionic liquids, the compositions comprising substituted 1,2,3-triazolium cations combined with any anion. Compositions of the invention should be useful in the separation of gases and, perhaps, as catalysts for many reactions.

  18. Ionic Liquids and New Proton Exchange Membranes for Fuel Cells

    NASA Technical Reports Server (NTRS)

    Belieres, Jean-Philippe

    2004-01-01

    There is currently a great surge of activity in fuel cell research as laboratories across the world seek to take advantage of the high energy capacity provided by &el cells relative to those of other portable electrochemical power systems. Much of this activity is aimed at high temperature fie1 cells, and a vital component of such &el cells must be the availability of a high temperature stable proton-permeable membrane. NASA Glenn Research Center is greatly involved in developing this technology. Other approaches to the high temperature fuel cell involve the use of single- component or almost-single-component electrolytes that provide a path for protons through the cell. A heavily researched case is the phosphoric acid fuel cell, in which the electrolyte is almost pure phosphoric acid and the cathode reaction produces water directly. The phosphoric acid fie1 cell delivers an open circuit voltage of 0.9 V falling to about 0.7 V under operating conditions at 170 C. The proton transport mechanism is mainly vehicular in character according to the viscosity/conductance relation. Here we describe some Proton Transfer Ionic Liquids (PTILs) with low vapor pressure and high temperature stability that have conductivities of unprecedented magnitude for non-aqueous systems. The first requirement of an ionic liquid is that, contrary to experience with most liquids consisting of ions, it must have a melting point that is not much above room temperature. The limit commonly suggested is 100 C. PTILs constitute an interesting class of non-corrosive proton-exchange electrolyte, which can serve well in high temperature (T = 100 - 250 C) fuel cell applications. We will present cell performance data showing that the open circuit voltage output, and the performance of a simple H2(g)Pt/PTIL/Pt/O2(g) fuel cell may be superior to those of the equivalent phosphoric acid electrolyte fuel cell both at ambient temperature and temperatures up to and above 200 C. My work at NASA Glenn Research Center during this summer is to develop and characterize proton exchange membranes doped with ionic liquids. The main techniques used to characterize these materials are: Impedance Spectroscopy, NMR, DSC, TGA, DMA, IR, and SEM ...

  19. Liquid clathrate formation in ionic liquid-aromatic mixtures.

    PubMed

    Holbrey, John D; Reichert, W Matthew; Nieuwenhuyzen, Mark; Sheppard, Oonagh; Hardacre, Christopher; Rogers, Robin D

    2003-02-21

    1-Alkyl-3-methylimidazolium containing ionic liquids with hexafluorophosphate, bis(trifyl)imide, tetrafluoroborate, and chloride anions form liquid clathrates when mixed with aromatic hydrocarbons; in the system 1,3-dimethylimidazolium hexafluorophosphate-benzene, the aromatic solute could be trapped in the solid state forming a crystalline 2:1 inclusion compound. PMID:12638957

  20. Synthesis of electroactive ionic liquids for flow battery applications

    SciTech Connect

    Anderson, Travis Mark; Ingersoll, David; Staiger, Chad; Pratt, Harry

    2015-09-01

    The present disclosure is directed to synthesizing metal ionic liquids with transition metal coordination cations, where such metal ionic liquids can be used in a flow battery. A cation of a metal ionic liquid includes a transition metal and a ligand coordinated to the transition metal.

  1. Electrochemistry of magnesium electrolytes in ionic liquids for secondary batteries.

    PubMed

    Vardar, Gulin; Sleightholme, Alice E S; Naruse, Junichi; Hiramatsu, Hidehiko; Siegel, Donald J; Monroe, Charles W

    2014-10-22

    The electrochemistry of Mg salts in room-temperature ionic liquids (ILs) was studied using plating/stripping voltammetry to assess the viability of IL solvents for applications in secondary Mg batteries. Borohydride (BH4(-)), trifluoromethanesulfonate (TfO(-)), and bis(trifluoromethanesulfonyl)imide (Tf2N(-)) salts of Mg were investigated. Three ILs were considered: l-n-butyl-3-methylimidazolium (BMIM)-Tf2N, N-methyl-N-propylpiperidinium (PP13)-Tf2N, and N,N-diethyl-N-methyl(2-methoxyethyl)ammonium (DEME(+)) tetrafluoroborate (BF4(-)). Salts and ILs were combined to produce binary solutions in which the anions were structurally similar or identical, if possible. Contrary to some prior reports, no salt/IL combination appeared to facilitate reversible Mg plating. In solutions containing BMIM(+), oxidative activity near 0.8 V vs Mg/Mg(2+) is likely associated with the BMIM cation, rather than Mg stripping. The absence of voltammetric signatures of Mg plating from ILs with Tf2N(-) and BF4(-) suggests that strong Mg/anion Coulombic attraction inhibits electrodeposition. Cosolvent additions to Mg(Tf2N)2/PP13-Tf2N were explored but did not result in enhanced plating/stripping activity. The results highlight the need for IL solvents or cosolvent systems that promote Mg(2+) dissociation. PMID:25248147

  2. Silica particle stability and settling in protic ionic liquids.

    PubMed

    Smith, Jacob; Webber, Grant Bruce; Warr, Gregory G; Atkin, Rob

    2014-02-18

    Silica particle suspensions of 10 wt % have been investigated in the protic ionic liquids (ILs) ethylammonium nitrate (EAN), ethanolammonium nitrate (EtAN), propylammonium nitrate (PAN), and dimethylethylammonium formate (DMEAF). Static and dynamic light scattering reveal that single particles coexist in dynamic equilibrium with flocculated networks at room temperature. These types of systems are classified as weakly flocculated and are quite rare. As weakly flocculated systems generally exist only within a narrow range of conditions, the effect of temperature was probed. When temperature is increased, the thermal motion of suspended particles increases, favoring dispersion, but in ILs suspensions, heating reduces the stabilizing effect of the interfacial structure of the IL. When subjected to a small increase in temperature, particle suspensions in ILs become unstable, indicated by the absence of a peak corresponding to single particles in the light scattering data. For EAN and DMEAF, further increasing temperatures above 40 C returns the systems to a weakly flocculated state in which thermal energy is sufficient to break particles away from aggregates. Weakly flocculated suspensions in EAN and EtAN settle more rapidly than predicted by the Stokes equation, as the particles spend a significant portion of time in large, rapidly settling flocs. Surprisingly, suspensions in PAN and DMEAF settle slower than predicted. Oscillatory rheology indicates that these suspensions are viscoelastic, due to a persistent, long-range structure in the suspension that slows settling. In aggregated systems, settling is very rapid. PMID:24450614

  3. Functionalized ionic liquids as electrolytes for lithium-ion batteries

    NASA Astrophysics Data System (ADS)

    Pandian, Shanthi; Raju, S. G.; Hariharan, Krishnan S.; Kolake, Subramanya M.; Park, Da-Hye; Lee, Myung-Jin

    2015-07-01

    The design of potential and new electrochemically stable electrolytes for Li-ion batteries is an important task in the field of energy. Room temperature ionic liquids (RTILs) characterized by a wide electrochemical window (EW) are the commonly used electrolytes for Li battery applications. In this work, a novel quantum computational method is proposed to estimate the electrochemical stability of RTILs that accurately predicts the trends in EWs of ammonium based ILs and is computationally faster than the state-of-the-art methods. Subsequently, the EW of ILs with phosphonium and sulfonium cations are computed and compared against the well-established ammonium congeners. Based on the criterion of electrochemical stability defined with respect to Li, the increasing order of stability is found to be: sulfonium < ammonium < phosphonium based ILs. The effect of various substituents like butyl, phenyl and benzyl on the phosphonium and sulfonium based ILs is examined and a greater stability for the phenyl over other substituents is observed. The key factor influencing the reduction potential of the cations is inferred as the thermodynamic stability of the radical formed during decomposition. Based on the results, design guidelines to identify stable IL systems as electrolytes in high voltage Li-ion battery applications are provided.

  4. Organic electrical double layer transistors gated with ionic liquids

    NASA Astrophysics Data System (ADS)

    Xie, Wei; Frisbie, C. Daniel

    2011-03-01

    Transport in organic semiconductors gated with several types of ionic liquids has been systematically studied at charge densities larger than 1013 cm-2 . We observe a pronounced maximum in channel conductance for both p-type and n-type organic single crystals which is attributed to carrier localization at the semiconductor-electrolyte interface. Carrier mobility, as well as charge density and dielectric capacitance are determined through displacement current measurement and capacitance-voltage measurement. By using a larger-sized and spherical anion, tris(pentafluoroethyl)trifluorophosphate (FAP), effective carrier mobility in rubrene can be enhanced substantially up to 3.2 cm2 V-1 s -1 . Efforts have been made to maximize the charge density in rubrene single crystals, and at low temperature when higher gate bias can be applied, charge density can more than double the amount of that at room temperature, reaching 8*1013 cm-2 holes (0.4 holes per rubrene molecule). NSF MRSEC program at the University of Minnesota.

  5. Corneal storage at room temperature.

    PubMed

    Sachs, U; Goldman, K; Valenti, J; Kaufman, H E

    1978-06-01

    Short-term eye banking is based mainly on moist chamber and McCarey-Kaufman medium (M-K medium) preservation. Both involve a controlled 4 C temperature for storage. Warming the cornea to room temperature, however, drastically affects the endothelial viability. On enzymatic staining and histological study, the M-K medium-stored rabbit corneas had more normal endothelium than did "moist chamber" eyes when storage was prolonged for seven days at room temperature. In human corneas that were kept at 4 C for 24 hours and then exposed to a temperature of 25 C, destruction of organelles had occurred by six hours and was increased by 12 hours. Corneas that were kept in M-K medium had relatively intact endothelium after four days, but cell disruption and vacuolation was present by the seventh day. The M-K medium, therefore, affords protection to tissue warmed to room temperature, where metabolic activity is resumed. PMID:350203

  6. Electrofluorochromism in ?-conjugated ionic liquid crystals

    NASA Astrophysics Data System (ADS)

    Beneduci, Amerigo; Cospito, Sante; La Deda, Massimo; Veltri, Lucia; Chidichimo, Giuseppe

    2014-01-01

    Materials in which photoluminescence is modulated by redox processes are known as electrofluorochromic. Intrinsically switchable fluorophores, incorporating both redox and fluorescent moieties, could be ideal electrofluorochromic materials if they possess high fluorescence quantum yields in at least one of their redox states. Fluorescent liquid crystals with redox active centres could combine the above requirements with the advantage to work in bulk anisotropic phases. However, electrofluorochromic liquid crystals have not been reported yet because their synthesis is challenging due to aggregation-caused fluorescent quenching. Here we show the first examples of electrofluorochromic ?-conjugated ionic liquid crystals based on thienoviologens. These ordered materials, combining ionic and electronic functions, are highly fluorescence in the bulk state (quantum yield>60%). Their direct electrochemical reduction leads to fast and reversible bulk electrofluorochromic response in both columnar and smectic phases allowing for fluorescence intensity modulation and colour tuning.

  7. Twin-peaks absorption spectra of excess electron in ionic liquids

    NASA Astrophysics Data System (ADS)

    Musat, Raluca M.; Kondoh, Takafumi; Yoshida, Yoichi; Takahashi, Kenji

    2014-07-01

    The solvated electron in room temperature ionic liquids (RTILs) has been the subject of several investigations and several reports exist on its nature and absorption spectrum. These studies concluded that the solvated electron exhibits an absorption spectrum peaking in the 1000-1400 nm region; a second absorption band peaking in the UV region has been assigned to the hole or dication radicals simultaneously formed in the system. Here we report on the fate of the excess electron in the ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide, P14+/NTf2- using nanosecond pulse radiolysis. Scavenging experiments allowed us to record and disentangle the complex spectrum measured in P14+/NTf2-. We identified a bi-component absorption spectrum, due to the solvated electron, the absorption maxima located at 1080 nm and around 300 nm, as predicted by previous ab-initio molecular dynamics simulations for the dry excess electron. We also measured the spectra using different ionic liquids and confirmed the same feature of two absorption peaks. The present results have important implications for the characterization of solvated electrons in ionic liquids and better understanding of their structure and reactivity.

  8. Charging and softening, collapse, and crystallization of dipolar phospholipid membranes by aqueous ionic liquid solutions.

    PubMed

    Dvir, Tom; Fink, Lea; Schilt, Yaelle; Raviv, Uri

    2014-12-16

    Ionic liquids have a variety of unique controllable structures and properties. These properties may be used to tailor the self-assembly of charged and dipolar biomolecules. Using solution X-ray scattering, we measured the structure of Dilauryl(C12:0)-sn-glycero-3-phospho-l-choline (DLPC), a dipolar (or zwitterionic) lipid, in the water-soluble room temperature ionic liquid Ethyl Methyl Imidazolium Ethyl Sulfate (EMIES) and mixtures of EMIES and water. We find that the interaction between the lipid bilayers is dominated by the balance between the charging of the polar headgroups by the ionic liquid, softening of the bilayer, and the osmotic pressure induced by the solvent. This balance leads to the following changes with increasing ionic liquid concentration: an incomplete unbinding transition from an attractive regime to a swollen regime of the lamellar phase formed by the bilayers. The swollen phase is followed by a collapse of the bilayers into a highly desolvated lamellar phase at some critical EMIES concentration, and eventually formation of lipid-crystalline phase, at very high EMIES concentrations. The latter phase is revealed by wide-angle X-ray scattering (WAXS) from the lipid solutions, showing multiple Bragg peaks, consistent with highly ordered structures. These structures were not observed in any other type of aqueous solutions containing monovalent or multivalent ions. The kinetics and temperature dependence of these transitions were also determined. PMID:25386894

  9. Nanostructure of mixtures of protic ionic liquids and lithium salts: effect of alkyl chain length.

    PubMed

    Mndez-Morales, Trinidad; Carrete, Jess; Rodrguez, Julio R; Cabeza, scar; Gallego, Luis J; Russina, Olga; Varela, Luis M

    2015-02-21

    The bulk structure of mixtures of two protic ionic liquids, propylammonium nitrate and butylammonium nitrate, with a salt with a common anion, is analyzed at room temperature by means of small angle X-ray scattering and classical molecular dynamics simulations. The study of several structural properties, such as density, radial distribution functions, spatial distribution functions, hydrogen bonds, coordination numbers and velocity autocorrelation functions, demonstrates that increasing the alkyl chain length of the alkylammonium cation results in more segregated, better defined polar and apolar domains, the latter having a larger size. This increase, ascribed to the erosion of the H-bond network in the ionic liquid polar regions as salt is added, is confirmed by means of small angle X-ray scattering measurements, which show a clear linear increase of the characteristic spatial sizes of the studied protic ionic liquids with salt concentration, similar to that previously reported for ethylammonium nitrate (J. Phys. Chem. B, 2014, 118, 761-770). In addition, larger ionic liquid cations lead to a lower degree of hydrogen bonding and to more sparsely packed three-dimensional structures, which are more easily perturbed by the addition of lithium salts. PMID:25609558

  10. Phase behavior of ionic liquid crystals

    NASA Astrophysics Data System (ADS)

    Kondrat, S.; Bier, M.; Harnau, L.

    2010-05-01

    Bulk properties of ionic liquid crystals are investigated using density functional theory. The liquid crystal molecules are represented by ellipsoidal particles with charges located in their center or at their tails. Attractive interactions are taken into account in terms of the Gay-Berne pair potential. Rich phase diagrams involving vapor, isotropic and nematic liquid, as well as smectic phases are found. The dependence of the phase behavior on various parameters such as the length of the particles and the location of charges on the particles is studied.

  11. Room temperature terahertz polariton emitter

    SciTech Connect

    Geiser, Markus; Scalari, Giacomo; Castellano, Fabrizio; Beck, Mattias; Faist, Jerome

    2012-10-01

    Terahertz (THz) range electroluminescence from intersubband polariton states is observed in the ultra strong coupling regime, where the interaction energy between the collective excitation of a dense electron gas and a photonic mode is a significant portion of the uncoupled excitation energy. The polariton's increased emission efficiency along with a parabolic electron confinement potential allows operation up to room temperature in a nonresonant pumping scheme. This observation of room temperature electroluminescence of an intersubband device in the THz range is a promising proof of concept for more powerful THz sources.

  12. Understanding the large solubility of lidocaine in 1-n-butyl-3-methylimidazolium based ionic liquids using molecular simulation.

    PubMed

    Ley, Ryan T; Paluch, Andrew S

    2016-02-28

    Room temperature ionic liquids have been proposed as replacement solvents in a wide range of industrial separation processes. Here, we focus on the use of ionic liquids as solvents for the pharmaceutical compound lidocaine. We show that the solubility of lidocaine in seven common 1-n-butyl-3-methylimidazolium based ionic liquids is greatly enhanced relative to water. The predicted solubility is greatest in [BMIM](+)[CH3CO2](-), which we find results from favorable hydrogen bonding between the lidocaine amine hydrogen and the [CH3CO2](-) oxygen, favorable electrostatic interactions between the lidocaine amide oxygen with the [BMIM](+) aromatic ring hydrogens, while lidocaine does not interfere with the association of [BMIM](+) with [CH3CO2](-). Additionally, by removing functional groups from the lidocaine scaffold while maintaining the important amide group, we found that as the van der Waals volume increases, solubility in [BMIM](+)[CH3CO2](-) relative to water increases. PMID:26931706

  13. Understanding the large solubility of lidocaine in 1-n-butyl-3-methylimidazolium based ionic liquids using molecular simulation

    NASA Astrophysics Data System (ADS)

    Ley, Ryan T.; Paluch, Andrew S.

    2016-02-01

    Room temperature ionic liquids have been proposed as replacement solvents in a wide range of industrial separation processes. Here, we focus on the use of ionic liquids as solvents for the pharmaceutical compound lidocaine. We show that the solubility of lidocaine in seven common 1-n-butyl-3-methylimidazolium based ionic liquids is greatly enhanced relative to water. The predicted solubility is greatest in [BMIM]+[CH3CO2]-, which we find results from favorable hydrogen bonding between the lidocaine amine hydrogen and the [CH3CO2]- oxygen, favorable electrostatic interactions between the lidocaine amide oxygen with the [BMIM]+ aromatic ring hydrogens, while lidocaine does not interfere with the association of [BMIM]+ with [CH3CO2]-. Additionally, by removing functional groups from the lidocaine scaffold while maintaining the important amide group, we found that as the van der Waals volume increases, solubility in [BMIM]+[CH3CO2]- relative to water increases.

  14. Electrochemical properties of the polyethylene oxide-Li(CF3SO2)2N and ionic liquid composite electrolyte

    NASA Astrophysics Data System (ADS)

    Wang, H.; Imanishi, N.; Hirano, A.; Takeda, Y.; Yamamoto, O.

    2012-12-01

    The electrical conductivity and lithium ion transport properties of the polyethylene oxide (PEO) with lithium salt Li(CF3SO2)2N (LiTFSI) and a room temperature ionic liquid of N-methyl-N-propylpiperdinium bis(fluorosulfonyl)imide (PP13FSI) were examined as a function of the ionic liquid content. The electrical conductivity of PEO18LiTFSI-xPP13FSI increased and the lithium ion transport number decreased with increasing the ionic liquid content. The interface resistance between PEO18LiTFSI-xPP13FSI and lithium metal was dependent on x and the lowest interface resistance was observed in the range of x = 1.2-1.44. The critical current density of lithium deposition and dissolution on lithium metal was reduced and lithium dendrite formation was suppressed by the addition of PP13FSI into PEO18LiTFSI.

  15. Molecular dynamics simulation of imidazolium-based ionic liquids. II. Transport coefficients.

    PubMed

    Kowsari, M H; Alavi, Saman; Ashrafizaadeh, Mahmud; Najafi, Bijan

    2009-01-01

    A systematic molecular dynamics study is performed to determine the dynamics and transport properties of 12 room-temperature ionic liquids family with 1-alkyl-3-methylimidazolium cation, [amim](+) (alkyl = methyl, ethyl, propyl, and butyl), with counterions, PF(6)(-), NO(3)(-), and Cl(-). The goal of the work is to provide molecular level understanding of the transport coefficients of these liquids as guidance to experimentalists on choosing anion and cation pairs to match required properties of ionic liquid solvents. In the earlier paper (Part I), we characterized the dynamics of ionic liquids and provided a detailed comparison of the diffusion coefficients for each ion using the Einstein and Green-Kubo formulas. In this second part, other transport properties of imidazolium salts are calculated, in particular, the electrical conductivity is calculated from the Nernst-Einstein and Green-Kubo formulas. The viscosity is also determined from the Stokes-Einstein relation. The results of the calculated transport coefficients are consistent with the previous computational and experimental studies of imidazolium salts. Generally, the simulations give electrical conductivity lower than experiment while the viscosity estimate is higher than experiment. Within the same cation family, the ionic liquids with the NO(3)(-) counterion have the highest electrical conductivities: sigma[NO(3)](-)>sigma[PF(6)](-)>sigma[Cl](-). The [dmim][X] series, due to their symmetric cationic structure and good packing and the [bmim][X] series due to higher inductive van der Waals interactions of [bmim](+), have the highest viscosities in these ionic liquid series. Our simulations show that the major factors determining the magnitude of the self-diffusion, electrical conductivity, and viscosity are the geometric shape, ion size, and the delocalization of the ionic charge in the anion. PMID:19140627

  16. Interactions in ion pairs of protic ionic liquids: Comparison with aprotic ionic liquids

    NASA Astrophysics Data System (ADS)

    Tsuzuki, Seiji; Shinoda, Wataru; Miran, Md. Shah; Kinoshita, Hiroshi; Yasuda, Tomohiro; Watanabe, Masayoshi

    2013-11-01

    The stabilization energies for the formation (Eform) of 11 ion pairs of protic and aprotic ionic liquids were studied by MP2/6-311G** level ab initio calculations to elucidate the difference between the interactions of ions in protic ionic liquids and those in aprotic ionic liquids. The interactions in the ion pairs of protic ionic liquids (diethylmethylammonium [dema] and dimethylpropylammonium [dmpa] based ionic liquids) are stronger than those of aprotic ionic liquids (ethyltrimethylammonium [etma] based ionic liquids). The Eform for the [dema][CF3SO3] and [dmpa][CF3SO3] complexes (-95.6 and -96.4 kcal/mol, respectively) are significantly larger (more negative) than that for the [etma][CF3SO3] complex (-81.0 kcal/mol). The same trend was observed for the calculations of ion pairs of the three cations with the Cl-, BF4-, TFSA- anions. The anion has contact with the N-H bond of the dema+ or dmpa+ cations in the most stable geometries of the dema+ and dmpa+ complexes. The optimized geometries, in which the anions locate on the counter side of the cations, are 11.0-18.0 kcal/mol less stable, which shows that the interactions in the ions pairs of protic ionic liquids have strong directionality. The Eform for the less stable geometries for the dema+ and dmpa+ complexes are close to those for the most stable etma+ complexes. The electrostatic interaction, which is the major source of the attraction in the ion pairs, is responsible for the directionality of the interactions and determining the magnitude of the interaction energy. Molecular dynamic simulations of the [dema][TFSA] and [dmpa][TFSA] ionic liquids show that the N-H bonds of the cations have contact with the negatively charged (oxygen and nitrogen) atoms of TFSA- anion, while the strong directionality of the interactions was not suggested from the simulation of the [etma][CF3SO3] ionic liquid.

  17. Interactions in ion pairs of protic ionic liquids: comparison with aprotic ionic liquids.

    PubMed

    Tsuzuki, Seiji; Shinoda, Wataru; Miran, Md Shah; Kinoshita, Hiroshi; Yasuda, Tomohiro; Watanabe, Masayoshi

    2013-11-01

    The stabilization energies for the formation (E(form)) of 11 ion pairs of protic and aprotic ionic liquids were studied by MP2/6-311G** level ab initio calculations to elucidate the difference between the interactions of ions in protic ionic liquids and those in aprotic ionic liquids. The interactions in the ion pairs of protic ionic liquids (diethylmethylammonium [dema] and dimethylpropylammonium [dmpa] based ionic liquids) are stronger than those of aprotic ionic liquids (ethyltrimethylammonium [etma] based ionic liquids). The E(form) for the [dema][CF3SO3] and [dmpa][CF3SO3] complexes (-95.6 and -96.4 kcal/mol, respectively) are significantly larger (more negative) than that for the [etma][CF3SO3] complex (-81.0 kcal/mol). The same trend was observed for the calculations of ion pairs of the three cations with the Cl(-), BF4(-), TFSA(-) anions. The anion has contact with the N-H bond of the dema(+) or dmpa(+) cations in the most stable geometries of the dema(+) and dmpa(+) complexes. The optimized geometries, in which the anions locate on the counter side of the cations, are 11.0-18.0 kcal/mol less stable, which shows that the interactions in the ions pairs of protic ionic liquids have strong directionality. The E(form) for the less stable geometries for the dema(+) and dmpa(+) complexes are close to those for the most stable etma(+) complexes. The electrostatic interaction, which is the major source of the attraction in the ion pairs, is responsible for the directionality of the interactions and determining the magnitude of the interaction energy. Molecular dynamic simulations of the [dema][TFSA] and [dmpa][TFSA] ionic liquids show that the N-H bonds of the cations have contact with the negatively charged (oxygen and nitrogen) atoms of TFSA(-) anion, while the strong directionality of the interactions was not suggested from the simulation of the [etma][CF3SO3] ionic liquid. PMID:24206313

  18. Interactions in ion pairs of protic ionic liquids: Comparison with aprotic ionic liquids

    SciTech Connect

    Tsuzuki, Seiji; Shinoda, Wataru; Miran, Md. Shah; Kinoshita, Hiroshi; Yasuda, Tomohiro; Watanabe, Masayoshi

    2013-11-07

    The stabilization energies for the formation (E{sub form}) of 11 ion pairs of protic and aprotic ionic liquids were studied by MP2/6-311G{sup **} level ab initio calculations to elucidate the difference between the interactions of ions in protic ionic liquids and those in aprotic ionic liquids. The interactions in the ion pairs of protic ionic liquids (diethylmethylammonium [dema] and dimethylpropylammonium [dmpa] based ionic liquids) are stronger than those of aprotic ionic liquids (ethyltrimethylammonium [etma] based ionic liquids). The E{sub form} for the [dema][CF{sub 3}SO{sub 3}] and [dmpa][CF{sub 3}SO{sub 3}] complexes (?95.6 and ?96.4 kcal/mol, respectively) are significantly larger (more negative) than that for the [etma][CF{sub 3}SO{sub 3}] complex (?81.0 kcal/mol). The same trend was observed for the calculations of ion pairs of the three cations with the Cl{sup ?}, BF{sub 4}{sup ?}, TFSA{sup ?} anions. The anion has contact with the NH bond of the dema{sup +} or dmpa{sup +} cations in the most stable geometries of the dema{sup +} and dmpa{sup +} complexes. The optimized geometries, in which the anions locate on the counter side of the cations, are 11.018.0 kcal/mol less stable, which shows that the interactions in the ions pairs of protic ionic liquids have strong directionality. The E{sub form} for the less stable geometries for the dema{sup +} and dmpa{sup +} complexes are close to those for the most stable etma{sup +} complexes. The electrostatic interaction, which is the major source of the attraction in the ion pairs, is responsible for the directionality of the interactions and determining the magnitude of the interaction energy. Molecular dynamic simulations of the [dema][TFSA] and [dmpa][TFSA] ionic liquids show that the NH bonds of the cations have contact with the negatively charged (oxygen and nitrogen) atoms of TFSA{sup ?} anion, while the strong directionality of the interactions was not suggested from the simulation of the [etma][CF{sub 3}SO{sub 3}] ionic liquid.

  19. General impossibility to 'prescribe' diffusion for a geminate pair in a central force field and peculiarities of geminate in ionic liquids.

    SciTech Connect

    Shkrob, I. A.

    2011-05-12

    Given the difficulty of obtaining analytical solutions for the diffusion of interacting geminate pairs of (ion) radicals in liquids, it is common, following the original treatment of Mozumder, to 'prescribe' this diffusion. A demonstration is given that such a prescription is impossible for any interaction potential other than the Coulomb potential. This demonstration suggests the inadequacy of this common approach to modeling geminate pair and spur dynamics in the largest emerging class of organic solvents: room-temperature ionic liquids.

  20. Structural and Aggregation Study of Protic Ionic Liquids

    NASA Astrophysics Data System (ADS)

    Mattedi, S.; Martin-Pastor, M.; Iglesias, M.

    2011-12-01

    In this work there were studied structural and agreggation aspects of ionic liquids formed by the reaction between ethanolamines with low chain organic acids using NMR techniques. Three ionic liquids composed of pentanoic acid and (mono-, di- and tri-) ethanol amine were studied by 1H, and 13C solution NMR methods. NMR assisted the chemical and quantitative characterization of these three ionic liquids and provided insight in their structural arrangement of their components in the ionic liquid medium. The obtained results could be used to understand the structure and aggregation pattern of these ionic liquids and helps in the development of possible industrial applications.

  1. Employment of ionic liquid-imbibed polymer gel electrolyte for efficient quasi-solid-state dye-sensitized solar cells

    NASA Astrophysics Data System (ADS)

    Li, Qinghua; Tang, Qunwei; Du, Nan; Qin, Yuancheng; Xiao, Jin; He, Benlin; Chen, Haiyan; Chu, Lei

    2014-02-01

    Volatility of organic solvent in liquid electrolyte has been tremendous obstacle for its application in dye-sensitized solar cells (DSSCs), here we designed an ionic liquid-imbibed polymer gel electrolyte using 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) as solvent, 1-methyl-3-propylimidazolium iodide (MPII) as iodine source, and amphiphilic poly(hydroxyethyl methacrylate/glycerol) [poly(HEMA/GR)] as a placeholder. As an amphiphilic matrix, poly(HEMA/GR) material can swell in ionic liquid electrolyte to form a stable gel, benefiting from its extraordinary absorption. The imbibed ionic liquid electrolyte is stored into interconnected poly(HEMA/GR) framework. Resultant quasi-solid-state electrolyte is honored with high ionic conductivity (14.29 mS cm-1) at room temperature and good retention. The ionic liquid-imbibed poly(HEMA/GR) gel electrolyte-based DSSC gives an overall light-to-electric conversion efficiency of 7.15%. The new concept along with easy fabrication promises the ionic liquid-imbibed gel electrolytes good alternatives in efficient DSSCs.

  2. Molecular origin of high free energy barriers for alkali metal ion transfer through ionic liquid-graphene electrode interfaces.

    PubMed

    Ivanitev, Vladislav; Mndez-Morales, Trinidad; Lynden-Bell, Ruth M; Cabeza, Oscar; Gallego, Luis J; Varela, Luis M; Fedorov, Maxim V

    2015-12-23

    In this work we study mechanisms of solvent-mediated ion interactions with charged surfaces in ionic liquids by molecular dynamics simulations, in an attempt to reveal the main trends that determine ion-electrode interactions in ionic liquids. We compare the interfacial behaviour of Li(+) and K(+) at a charged graphene sheet in a room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate, and its mixtures with lithium and potassium tetrafluoroborate salts. Our results show that there are dense interfacial solvation structures in these electrolytes that lead to the formation of high free energy barriers for these alkali metal cations between the bulk and direct contact with the negatively charged surface. We show that the stronger solvation of Li(+) in the ionic liquid leads to the formation of significantly higher interfacial free energy barriers for Li(+) than for K(+). The high free energy barriers observed in our simulations can explain the generally high interfacial resistance in electrochemical storage devices that use ionic liquid-based electrolytes. Overcoming these barriers is the rate-limiting step in the interfacial transport of alkali metal ions and, hence, appears to be a major drawback for a generalised application of ionic liquids in electrochemistry. Some plausible strategies for future theoretical and experimental work for tuning them are suggested. PMID:26661060

  3. Adsorption of ionic liquid onto halloysite nanotubes: Thermal and mechanical properties of heterophasic PE-PP copolymer nanocomposites

    NASA Astrophysics Data System (ADS)

    Bischoff, E.; Simon, D. A.; Liberman, S. A.; Mauler, R. S.

    2016-03-01

    The surface adsorption of inorganic clays with ionic liquids has attracted much attention due to improve the interaction of hydrophilic clay with the hydrophobic polymers. However, successful organic adsorption strongly depends on the characteristics of ionic liquid (anion, chain size and concentration), and the reaction conditions (as polarity of solvent). In this study, such factors were analyzed and correlated with morphology, thermal and mechanical properties of the nanocomposites. The heterophasic ethylene-propylene copolymer nanocomposites were prepared by melt intercalation method in a twin screw co-rotating extruder. The halloysite nanotubes (HNT) was used as filler - natural and modified with different ionic liquids. The results showed that a better distribution and dispersion of the nanoparticles was achieved in the samples with modified HNT (m-HNT) and was more significant when the ionic liquid adsorption was conducted in a less polar solvent. The thermal stability of the nanocomposites with m- HNT was higher compared to the neat CP. Additionally, the better balance in the mechanical properties was obtained by the use of the more hydrophobic ionic liquid and higher concentration with improve of 27% in the Young Modulus without loss in the impact properties at room temperature. These superior behaviors of ionic liquid adsorption products exhibit properties suitable for many industrial applications.

  4. Triphenylene-Based Room-Temperature Discotic Liquid Crystals: A New Class of Blue-Light-Emitting Materials with Long-Range Columnar Self-Assembly.

    PubMed

    Gupta, Monika; Pal, Santanu Kumar

    2016-02-01

    A straightforward synthesis of multialkynylbenzene-bridged triphenylene-based dyad systems (via flexible alkyl spacers) that self-organize into room-temperature columnar structures over a long range is reported. The compounds with spacer lengths (n) of 8 and 10 exhibit a columnar rectangular mesophase whereas a compound with n = 6 shows a columnar rectangular plastic phase. Interestingly, the later compound (n = 6) shows the formation of well-nucleated spherulites of about several hundred micrometers that suggest the existence of a long-range uniform self-assembly of columns. All of these compounds show blue luminescence in solution and in the thin-film state under long-wavelength (365 nm) UV light. These compounds fulfill the described demands such as long-range columnar self-assembly at room temperature, a good yield with high purity, and blue-light emitters under the neat condition for possible potential applications in semiconductor devices. They also match the criteria of facile processing from the isotropic state because of their low isotropization temperature. This new class of materials is promising, considering the emissive nature and stabilization of the columnar mesophase at ambient temperature. PMID:26745267

  5. Increasing the intensity of protonated secondary ions in time-of-flight secondary ion mass spectrometry using a proton-conducting ionic liquid, diethylmethylammonium trifluoromethanesulfonate

    NASA Astrophysics Data System (ADS)

    Fujiwara, Yukio; Saito, Naoaki

    2015-07-01

    To increase the secondary ion intensities of organic molecules, room-temperature ionic liquids were investigated in two time-of-flight secondary ion mass spectrometry (TOF-SIMS) experiments. First, ionic liquids as well as glycerol were tested as liquid matrices of arginine. The secondary ion intensity of protonated arginine was increased 200-fold by using a proton-conducting ionic liquid, diethylmethylammonium trifluoromethanesulfonate ([dema][TfO]). The matrix effect of [dema][TfO] was higher than that of glycerol, which is a typical matrix in SIMS. Next, ionic liquids were tested as primary ion beams. The number of protonated secondary ions of arginine was significantly increased by using a primary ion beam of [dema][TfO].

  6. Furfural production using ionic liquids: A review.

    PubMed

    Peleteiro, Susana; Rivas, Sandra; Alonso, José Luis; Santos, Valentín; Parajó, Juan Carlos

    2016-02-01

    Furfural, a platform chemical with a bright future, is commercially obtained by acidic processing of xylan-containing biomass in aqueous media. Ionic liquids (ILs) can be employed in processed for furfural manufacture as additives, as catalysts and/or as reaction media. Depending on the IL utilized, externally added catalysts (usually, Lewis acids, Brönsted acids and/or solid acid catalysts) can be necessary to achieve high reaction yields. Oppositely, acidic ionic liquids (AILs) can perform as both solvents and catalysts, enabling the direct conversion of suitable substrates (pentoses, pentosans or xylan-containing biomass) into furfural. Operating in IL-containing media, the furfural yields can be improved when the product is continuously removed along the reaction (for example, by stripping or extraction), to avoid unwanted side-reactions leading to furfural consumption. These topics are reviewed, as well as the major challenges involved in the large scale utilization of ILs for furfural production. PMID:26708486

  7. Structural Transitions at Ionic Liquid Interfaces.

    PubMed

    Rotenberg, Benjamin; Salanne, Mathieu

    2015-12-17

    Recent advances in experimental and computational techniques have allowed for an accurate description of the adsorption of ionic liquids on metallic electrodes. It is now well-established that they adopt a multilayered structure and that the composition of the layers changes with the potential of the electrode. In some cases, potential-driven ordering transitions in the first adsorbed layer have been observed in experiments probing the interface on the molecular scale or by molecular simulations. This perspective gives an overview of the current understanding of such transitions and of their potential impact on the physical and (electro)chemical processes at the interface. In particular, peaks in the differential capacitance, slow dynamics at the interface, and changes in the reactivity have been reported in electrochemical studies. Interfaces between ionic liquids and metallic electrodes are also highly relevant for their friction properties, the voltage-dependence of which opens the way to exciting applications. PMID:26722704

  8. Checkerboard Self-Patterning of an Ionic Liquid Film on Mercury

    SciTech Connect

    Ocko, B.M.; Tamam, L.; Reichert, H.; Deutsch, M.

    2011-05-10

    {angstrom}-resolution studies of room temperature ionic liquid (RTIL) interfaces are scarce, in spite of their long-recognized importance for the science and many applications of RTILs. We present an {angstrom}-resolution x-ray study of a Langmuir film of an RTIL on mercury. At low (high) coverage [90 (50) {angstrom}{sup 2}/molecule] a mono-(bi)layer of surface-parallel molecules is found. The molecules self-assemble in a lateral ionic checkerboard pattern, unlike the uniform-charge, alternate-ion layers of this RTIL at its bulk-solid interface. A 2D-smectic order is found, with molecules packed in parallel stripes, forming long-range order normal to, but none along, the stripes.

  9. Checkerboard Self-Patterning of an Ionic Liquid Film on Mercury

    SciTech Connect

    L Tamam; B Ocko; H Reichert; M Deutsch

    2011-12-31

    {angstrom}-resolution studies of room temperature ionic liquid (RTIL) interfaces are scarce, in spite of their long-recognized importance for the science and many applications of RTILs. We present an {angstrom}-resolution x-ray study of a Langmuir film of an RTIL on mercury. At low (high) coverage [90 (50) {angstrom}{sup 2}/molecule] a mono-(bi)layer of surface-parallel molecules is found. The molecules self-assemble in a lateral ionic checkerboard pattern, unlike the uniform-charge, alternate-ion layers of this RTIL at its bulk-solid interface. A 2D-smectic order is found, with molecules packed in parallel stripes, forming long-range order normal to, but none along, the stripes.

  10. Conductivity Scaling Relationships in Nanostructured Membranes based on Protic Polymerized Ionic Liquids

    NASA Astrophysics Data System (ADS)

    Sanoja, Gabriel; Lynd, Nathaniel; Segalman, Rachel

    2015-03-01

    Nanostructured membranes based on protic polymerized ionic liquids are of great interest for a variety of electrochemical applications. Understanding the relationship between composition, structure, and ionic conductivity for these materials is essential for designing novel membranes with improved properties. In this work, we explore the effect of volume fraction of ionic liquid on conductivity, σ using a model system composed of poly[isoprene-block-(ethylene oxide-stat-histamine glycidyl ether) diblock copolymers [PI- b - P(EO-stat-HGE)] and the resulting [PI- b - P(EO-stat-IL)] obtained after treatment with trifluoroacetic acid. These materials self-assemble into lamellar structures with volume fractions of ionic liquid ranging from 0.50 to 0.90 as demonstrated by SAXS. PI- b - P(EO-stat-IL) membranes exhibit conductivities up to 4 x 10-3 S/cm at room temperature. In addition, PI- b - P(EO-stat-IL) based membranes have lower water uptake (λ = 8-10) in comparison with most proton conducting membranes reported elsewhere. The low λ in these membranes might translate into a stronger effect of morphology on transport properties. Joint Center for Artificial Photosynthesis.

  11. Electrochemical biosensing platform based on amino acid ionic liquid functionalized graphene for ultrasensitive biosensing applications.

    PubMed

    Lu, Xianbo; Wang, Xue; Jin, Jing; Zhang, Qing; Chen, Jiping

    2014-12-15

    In this study, a facile non-covalent method was developed for preparing water-soluble graphene with excellent electronic conductivity. Room temperature ionic liquids (ILs) with high ionic conductivity were used for the non-covalent surface functionalization of graphene through ?-? stacking interactions. Compared to other ILs used, amino acid ionic liquids (AAILs) were found to be the most effective for improving the dispersion of graphene in water phase. Electrochemical and spectroscopic results confirmed that the obtained AAIL functionalized GR can retain the excellent electronic conductivity of pristine graphene without damaging the graphene lattice. The obtained water-soluble graphene (GR-AAIL) was exemplified to fabricate an electrochemical biosensor using tyrosinase as a model enzyme, and the sensitivity (12,600 mA cm(-2) M(-1)) of GR-AAIL based biosensor was about 17 times higher than that of graphene oxide and other nanomaterial based biosensor, displaying its unprecedented high sensitivity for biosensing. The detection limit for catechol (one important environmental pollutant) reached as low as 8 nM with a response time of 3s and a linear range from 25 nM to 11,100 nM. The AAIL-GR based biosensor also demonstrated good reproducibility, repeatability, selectivity, long-term stability and high recovery for catechol detection. Amino acid ionic liquid functionalized graphene proves to be a robust and versatile electrochemical biosensing platform for fabricating biosensors with excellent performance. PMID:24997366

  12. Reversible Hydrophobic-Hydrophilic Transition of Ionic Liquids Driven by Carbon Dioxide.

    PubMed

    Xiong, Dazhen; Cui, Guokai; Wang, Jianji; Wang, Huiyong; Li, Zhiyong; Yao, Kaisheng; Zhang, Suojiang

    2015-06-15

    Ionic liquids (ILs) with a reversible hydrophobic-hydrophilic transition were developed, and they exhibited unique phase behavior with H2O: monophase in the presence of CO2, but biphase upon removal of CO2 at room temperature and atmospheric pressure. Thus, coupling of reaction, separation, and recovery steps in sustainable chemical processes could be realized by a reversible liquid-liquid phase transition of such IL-H2O mixtures. Spectroscopic investigations and DFT calculations showed that the mechanism behind hydrophobic-hydrophilic transition involved reversible reaction of CO2 with anion of the ILs and formation of hydrophilic ammonium salts. These unique IL-H2O systems were successfully utilized for facile one-step synthesis of Au porous films by bubbling CO2 under ambient conditions. The Au porous films and the ILs were then separated simultaneously from aqueous solutions by bubbling N2, and recovered ILs could be directly reused in the next process. PMID:25925191

  13. Self-propelled chemotactic ionic liquid droplets.

    PubMed

    Francis, Wayne; Fay, Cormac; Florea, Larisa; Diamond, Dermot

    2015-02-11

    Herein we report the chemotactic behaviour of self-propelled droplets composed solely of the ionic liquid trihexyl(tetradecyl)phosphonium chloride ([P(6,6,6,14)][Cl]). These droplets spontaneously move along an aqueous-air boundary in the direction of chloride gradients to specific destinations due to asymmetric release of [P(6,6,6,14)](+) cationic surfactant from the droplet into the aqueous phase. PMID:25562698

  14. Mirrorless dye doped ionic liquid lasers.

    PubMed

    Barna, Valentin; De Cola, Luisa

    2015-05-01

    The study of electromagnetic waves propagation in periodically structured dielectrics and the linear and nonlinear optical phenomena in disordered systems doped with gain media represent one of the most challenging and exciting scientific areas of the past decade. Lasing and Random Lasers (RL) are fascinating examples of topics that synergize multiple scattering of light and optical amplification and lately have been the subject of intense theoretical and experimental studies. In this manuscript we demonstrate laser action in a new category of materials, namely dye doped ionic liquids. Ionic liquids prove to be perfect candidates for building, as shown, a series of exotic boundaryless or confined compact laser systems. Lasing is presented in standard wedge cells, freely suspended ionic liquid films and droplets. The optical emission properties are investigated in terms of spectral analysis, below and above lasing energy threshold behavior, emission efficiency, far field spatial laser modes intensity profiling, temporal emission behavior etc. As demonstrated, these materials can be employed as optimal near future replacements of conventional flammable solvents in already available dye laser instruments. PMID:25969283

  15. Anharmonicity and Fragility of Protic Ionic Liquids

    NASA Astrophysics Data System (ADS)

    Kim, Jenny; Angell, Austen; Ueno, Kazuhide; Tyagi, Madhu; Soles, Christopher; Masser, Kevin

    2013-03-01

    Supercooled liquids are often characterized by their fragility which is associated with physicochemical properties. However, the origin of fragility is still controversial. Superfragile liquid, decahydroisoquinoline (DHiQ) is chosen as a parent molecule to systematically investigate the relationship between anharmonicity and fragility of supercooled liquids. Earlier study by Ueno et al. (J. Phys. Chem. B 2012, 116) demonstrated that the protonation of DHiQ by different Bronsted acids results in the loss of superfragility. To understand the nature of fragile liquids, we conducted inelastic/quasielastic (IE/QE) neutron scattering measurements to examine low frequency vibrational dynamics (boson peak) and the relaxation behavior of DHiQ (high fragility) and DHiQ-based ionic liquids with intermediate (formate, Fm) and low (trifluoromethansulfonimide, TFSI) fragilities. With the protonation, molecular acids will be hydrogen-deficient and the scattering will be dominated by cation, [DHiQ+]. This strategy simplifies our interpretation in terms of understanding the fitting result from IENS/QENS spectra. By protonating DHiQ with stronger acids, large shift in low frequency vibrational modes and smaller mean square displacements were examined at temperatures higher than Tg. We illustrate how the degree of protonation and ionicity plays a role in the loss in superfragility of DHiQ.

  16. A new proton conductive liquid with no ions: pseudo-protic ionic liquids.

    PubMed

    Doi, Hiroyuki; Song, Xuedan; Minofar, Babak; Kanzaki, Ryo; Takamuku, Toshiyuki; Umebayashi, Yasuhiro

    2013-08-26

    Liquids with no ions! Raman analysis and quantum calculations suggest that electrically neutral molecular species predominantly exist in an N-methylimidazole and acetic acid equimolar mixture, and that ionic species are rather minor. Nevertheless, the mixture has significant ionic conductivity, and shows "good ionic" or "superionic" behavior (see figure). It may be suitable to call such liquids "pseudo-ionic liquids" rather than "ionic liquids". PMID:23873834

  17. Ionic liquid based multifunctional double network gel

    NASA Astrophysics Data System (ADS)

    Ahmed, Kumkum; Higashihara, Tomoya; Arafune, Hiroyuki; Kamijo, Toshio; Morinaga, Takashi; Sato, Takaya; Furukawa, Hidemitsu

    2015-04-01

    Gels are a promising class of soft and wet materials with diverse application in tissue engineering and bio-medical purpose. In order to accelerate the development of gels, it is required to synthesize multi-functional gels of high mechanical strength, ultra low surface friction and suitable elastic modulus with a variety of methods and new materials. Among many types of gel ionic gel made from ionic liquids (ILs) could be used for diverse applications in electrochemical devices and in the field of tribology. IL, a promising materials for lubrication, is a salt with a melting point lower than 100 C. As a lubricant, ILs are characterized by an extremely low vapor pressure, high thermal stability and high ion conductivity. In this work a novel approach of making double network DN ionic gel using IL has been made utilizing photo polymerization process. A hydrophobic monomer Methyl methacrylate (MMA) has been used as a first network and a hydrophobic IL monomer, N,N-diethyl-N-(2-mthacryloylethyl)-N-methylammonium bistrifluoromethylsulfonyl)imide (DEMM-TFSI) has been used as a second network using photo initiator benzophenon and crosslinker triethylene glycol dimethacrylate (TEGDMA). The resulting DN ionic gel shows transparency, flexibility, high thermal stability, good mechanical toughness and low friction coefficient value which can be a potential candidate as a gel slider in different mechanical devices and can open a new area in the field of gel tribology.

  18. Effect of pyrrolidinium based ionic liquid on the channel form of gramicidin in lipid vesicles.

    PubMed

    Singh, Upendra Kumar; Dohare, Neeraj; Mishra, Prabhash; Singh, Prashant; Bohidar, Himadri B; Patel, Rajan

    2015-08-01

    The present work is focused on the interaction between membrane bound gramicidin and 1-butyl-1-methyl-2-oxopyrrolidinium bromide (BMOP) ionic liquid. Ionic liquids (ILs) are solvents that are often liquid at room temperature and composed of organic cation and appropriate anion. The gramicidin peptide forms prototypical ion channels for cations, which have been extensively used to study the organization, dynamics, and function of membrane spanning channels. The interaction was studied by circular dichroism, steady state, time-resolved fluorescence spectroscopy in combination with dynamic surface tension and field emission scanning electron microscopic methods (FESEM). The results obtained from circular dichroism shows that the BMOP interacts with the channel form of gramicidin in lipid vesicle without any considerable effect on its conformation. The Red-edge excitation shift (REES) also supported the above findings. In addition, the fluorescence studies suggested that BMOP makes ground state complex with ion channel, which was further supported by time resolved measurements. Furthermore, dynamic surface tension analysis shows the faster adsorption of BMOP with membrane bound gramicidin at the air-water interface. Additionally, FESEM results indicated that BMOP forms a film around the membrane bound gramicidin at higher concentration. These results are potentially useful to analyze the effect of ionic liquids on the behaviour of membrane proteins. PMID:26025771

  19. Slow and fast capacitive process taking place at the ionic liquid/electrode interface.

    PubMed

    Roling, Bernhard; Drschler, Marcel; Huber, Benediki

    2012-01-01

    Electrochemical impedance spectroscopy was used to characterise the interface between the ultrapure room temperature ionic liquid 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate and a Au(111) working electrode at electrode potentials more positive than the open circuit potential (-0.14 V vs. Pt pseudo-reference). Plots of the potential-dependent data in the complex capacitance plane reveal the existence of a fast and a slow capacitive process. In order to derive the contribution of both processes to the overall capacitance, the complex capacitance data were fitted using an empirical Cole-Cole equation. The differential capacitance of the fast process is almost constant between -0.14 V and +0.2 V (vs. Pt pseudo-reference) and decreases at more positive potentials, while the differential capacitance of the slower process exhibits a maximum at +0.2 V. This maximum leads to a maximum in the overall differential capacitance. We attribute the slow process to charge redistributions in the innermost ion layer, which require an activation energy in excess of that for ion transport in the room temperature ionic liquid. The differential capacitance maximum of the slow process at +0.2 V is most likely caused by reorientations of the 1-butyl-1l-methylpyrrolidinium cations in the innermost layer with the positively charged ring moving away from the Au(111) surface and leaving behind voids which are then occupied by anions. In a recent Monte Carlo simulation by Federov, Georgi and Kornyshev (Electrochem. Commun. 2010, 12, 296), such a process was identified as the origin of a differential capacitance maximum in the anodic regime. Our results suggest that the time scales of capacitive processes at the ionic liquid/metal interface are an important piece of information and should be considered in more detail in future experimental and theoretical studies. PMID:22455027

  20. How polar are ionic liquids? Determination of the static dielectric constant of an imidazolium-based ionic liquid by microwave dielectric spectroscopy.

    PubMed

    Wakai, Chihiro; Oleinikova, Alla; Ott, Magnus; Weingärtner, Hermann

    2005-09-15

    In a pilot study of the dielectric constant of room-temperature ionic liquids, we use dielectric spectroscopy in the megahertz/gigahertz regime to determine the complex dielectric function of five 1-alkyl-3-methylimidazolium salts, from which the static dielectric constant epsilon is obtained by zero-frequency extrapolation. The results classify the salts as moderately polar solvents. The observed epsilon-values at 298.15 K fall between 15.2 and 8.8, and epsilon decreases with increasing chain length of the alkyl residue of the cation. The anion sequence is trifluoromethylsulfonate > tetrafluoroborate approximately tetrafluorophosphate. The results indicate markedly lower polarities than found by spectroscopy with polarity-sensitive solvatochromic dyes. PMID:16853170

  1. Aggregation behavior of long-chain ionic liquids in an ionic liquid.

    PubMed

    Li, Na; Zhang, Shaohua; Zheng, Liqiang; Dong, Bin; Li, Xinwei; Yu, Li

    2008-08-14

    The aggregation behavior of long-chain ionic liquids 1-alkyl-3-methylimidazolium bromide (C(n)mimBr) in another ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF(4)), was studied for the first time. Surface tension measurements revealed that aggregates are formed by C(n)mimBr, and freeze fracture transmission electron microscopy (FF-TEM) observations suggested the aggregates are spheres with a size much larger than traditional micelles. The sizes of the aggregates were further confirmed by dynamic light scattering (DLS) measurements. PMID:18654675

  2. Novel room temperature ferromagnetic semiconductors

    SciTech Connect

    Gupta, Amita

    2004-11-01

    Today's information world, bits of data are processed by semiconductor chips, and stored in the magnetic disk drives. But tomorrow's information technology may see magnetism (spin) and semiconductivity (charge) combined in one 'spintronic' device that exploits both charge and 'spin' to carry data (the best of two worlds). Spintronic devices such as spin valve transistors, spin light emitting diodes, non-volatile memory, logic devices, optical isolators and ultra-fast optical switches are some of the areas of interest for introducing the ferromagnetic properties at room temperature in a semiconductor to make it multifunctional. The potential advantages of such spintronic devices will be higher speed, greater efficiency, and better stability at a reduced power consumption. This Thesis contains two main topics: In-depth understanding of magnetism in Mn doped ZnO, and our search and identification of at least six new above room temperature ferromagnetic semiconductors. Both complex doped ZnO based new materials, as well as a number of nonoxides like phosphides, and sulfides suitably doped with Mn or Cu are shown to give rise to ferromagnetism above room temperature. Some of the highlights of this work are discovery of room temperature ferromagnetism in: (1) ZnO:Mn (paper in Nature Materials, Oct issue, 2003); (2) ZnO doped with Cu (containing no magnetic elements in it); (3) GaP doped with Cu (again containing no magnetic elements in it); (4) Enhancement of Magnetization by Cu co-doping in ZnO:Mn; (5) CdS doped with Mn, and a few others not reported in this thesis. We discuss in detail the first observation of ferromagnetism above room temperature in the form of powder, bulk pellets, in 2-3 mu-m thick transparent pulsed laser deposited films of the Mn (<4 at. percent) doped ZnO. High-resolution transmission electron microscopy (HRTEM) and electron energy loss spectroscopy (EELS) spectra recorded from 2 to 200nm areas showed homogeneous distribution of Mn substituting for Zn a 2+ state in the ZnO lattice. Ferromagnetic Resonance (FMR) technique is used to confirm the existence of ferromagnetic ordering at temperatures as high as 425K. The ab initio calculations were found to be consistent with the observation of ferromagnetism arising from fully polarized Mn 2+ state. The key to observed room temperature ferromagnetism in this system is the low temperature processing, which prevents formation of clusters, secondary phases and the host ZnO from becoming n-type. The electronic structure of the same Mn doped ZnO thin films studied using XAS, XES and RIXS, revealed a strong hybridization between Mn 3d and O 2p states, which is an important characteristic of a Dilute magnetic Semiconductor (DMS). It is shown that the various processing conditions like sintering temperature, dopant concentration and the properties of precursors used for making of DMS have a great influence on the final properties. Use of various experimental techniques to verify the physical properties, and to understand the mechanism involved to give rise to ferromagnetism is presented. Methods to improve the magnetic moment in Mn doped ZnO are also described. New promising DMS materials (such as Cu doped ZnO are explored). The demonstrated new capability to fabricate powder, pellets, and thin films of room temperature ferromagnetic semiconductors thus makes possible the realization of a wide range of complex elements for a variety of new multifunctional phenomena related to Spintronic devices as well as magneto-optic components.

  3. Room temperature electrodeposition of molybdenum sulfide for catalytic and photoluminescence applications.

    PubMed

    Murugesan, Sankaran; Akkineni, Arunkumar; Chou, Brendan P; Glaz, Micah S; Vanden Bout, David A; Stevenson, Keith J

    2013-09-24

    An elegant method for the electrodeposition of MoS2 thin films using room temperature ionic liquids (RTIL) as an electrolyte was developed. Simple molecular precursors of Mo and S were added in different concentrations to tune the composition and deposition process. The electrodeposition of MoS2 was confirmed with both Raman spectroscopy and XPS. Analysis showed that the electrodeposited MoS2 films form a flower shape morphology with edge active sites that promote the hydrogen evolution reaction (HER). Furthermore, this technique enables selective tuning of the film thickness and demonstrates high photoluminescence activity with a decrease in the number of layers. PMID:23962095

  4. Application of ionic liquids in photopolymerizable holographic materials

    NASA Astrophysics Data System (ADS)

    Lin, Hechun; de Oliveira, Peter W.; Veith, Michael

    2011-04-01

    The influence of ionic liquids in photopolymerizable holographic materials was investigated extensively. The structures of ionic liquids have important effect on the properties of the materials. Although not all tested ionic liquids can improve the properties of the materials, the ionic liquids based on imidazolium, pyridium, or phosphonium with appropriate counter anions can be used as additives to increase the sensitivity, the diffraction efficiency, and the resolution of the materials in the thin hologram. Polymerizable ionic liquids have also been used as additives. Higher sensitivity, higher diffraction efficiency and higher resolution were obtained as well. These ionic liquids can carry out the photopolymerization during exposure to UV light to recording the hologram. They may assist to form a more stable hologram.

  5. Ionic liquids for soft functional materials with carbon nanotubes.

    PubMed

    Fukushima, Takanori; Aida, Takuzo

    2007-01-01

    A serendipitous finding that ionic liquids gel with carbon nanotubes has opened a new possibility of ionic liquids as modifiers for carbon nanotubes. Upon being ground into ionic liquids, carbon nanotube bundles are untangled, and the resultant fine bundles form a network structure. This is due to the possible specific interaction between the imidazolium ion component and the pi-electronic nanotube surface. The resultant gelatinous materials, consisting of highly electroconductive nanowires and fluid electrolytes, can be utilized for a wide variety of electrochemical applications, such as sensors, capacitors, and actuators. Ionic liquids allow for noncovalent and covalent modifications of carbon nanotubes and fabrication of polymer composites with enhanced physical properties. The processing of carbon nanotubes with ionic liquids is not accompanied by the disruption of the pi-conjugated nanotube structure and does not require solvents; therefore it can readily be scaled up. This article focuses on new aspects of ionic liquids for designer soft materials based on carbon nanotubes. PMID:17516613

  6. Molecular mechanisms of ionic liquid cytotoxicity probed by an integrated experimental and computational approach

    DOE PAGESBeta

    Yoo, Brian; Jing, Benxin; Jones, Stuart E.; Lamberti, Gary A.; Zhu, Yingxi; Shah, Jindal K.; Maginn, Edward J.

    2016-02-02

    Ionic liquids (ILs) are salts that remain liquid down to low temperatures, and sometimes well below room temperature. ILs have been called “green solvents” because of their extraordinarily low vapor pressure and excellent solvation power, but ecotoxicology studies have shown that some ILs exhibit greater toxicity than traditional solvents. A fundamental understanding of the molecular mechanisms responsible for IL toxicity remains elusive. Here we show that one mode of IL toxicity on unicellular organisms is driven by swelling of the cell membrane. Cytotoxicity assays, confocal laser scanning microscopy, and molecular simulations reveal that IL cations nucleate morphological defects in themore » microbial cell membrane at concentrations near the half maximal effective concentration (EC50) of several microorganisms. Lastly, cytotoxicity increases with increasing alkyl chain length of the cation due to the ability of the longer alkyl chain to more easily embed in, and ultimately disrupt, the cell membrane.« less

  7. Molecular mechanisms of ionic liquid cytotoxicity probed by an integrated experimental and computational approach

    PubMed Central

    Yoo, Brian; Jing, Benxin; Jones, Stuart E.; Lamberti, Gary A.; Zhu, Yingxi; Shah, Jindal K.; Maginn, Edward J.

    2016-01-01

    Ionic liquids (ILs) are salts that remain liquid down to low temperatures, and sometimes well below room temperature. ILs have been called “green solvents” because of their extraordinarily low vapor pressure and excellent solvation power, but ecotoxicology studies have shown that some ILs exhibit greater toxicity than traditional solvents. A fundamental understanding of the molecular mechanisms responsible for IL toxicity remains elusive. Here we show that one mode of IL toxicity on unicellular organisms is driven by swelling of the cell membrane. Cytotoxicity assays, confocal laser scanning microscopy, and molecular simulations reveal that IL cations nucleate morphological defects in the microbial cell membrane at concentrations near the half maximal effective concentration (EC50) of several microorganisms. Cytotoxicity increases with increasing alkyl chain length of the cation due to the ability of the longer alkyl chain to more easily embed in, and ultimately disrupt, the cell membrane. PMID:26831599

  8. Molecular mechanisms of ionic liquid cytotoxicity probed by an integrated experimental and computational approach.

    PubMed

    Yoo, Brian; Jing, Benxin; Jones, Stuart E; Lamberti, Gary A; Zhu, Yingxi; Shah, Jindal K; Maginn, Edward J

    2016-01-01

    Ionic liquids (ILs) are salts that remain liquid down to low temperatures, and sometimes well below room temperature. ILs have been called "green solvents" because of their extraordinarily low vapor pressure and excellent solvation power, but ecotoxicology studies have shown that some ILs exhibit greater toxicity than traditional solvents. A fundamental understanding of the molecular mechanisms responsible for IL toxicity remains elusive. Here we show that one mode of IL toxicity on unicellular organisms is driven by swelling of the cell membrane. Cytotoxicity assays, confocal laser scanning microscopy, and molecular simulations reveal that IL cations nucleate morphological defects in the microbial cell membrane at concentrations near the half maximal effective concentration (EC50) of several microorganisms. Cytotoxicity increases with increasing alkyl chain length of the cation due to the ability of the longer alkyl chain to more easily embed in, and ultimately disrupt, the cell membrane. PMID:26831599

  9. Conformational Properties of a Polymer in an Ionic Liquid: Computer Simulations and Integral Equation Theory of a Coarse-Grained Model.

    PubMed

    Choi, Eunsong; Yethiraj, Arun

    2015-07-23

    We study the conformational properties of polymers in room temperature ionic liquids using theory and simulations of a coarse-grained model. Atomistic simulations have shown that single poly(ethylene oxide) (PEO) molecules in the ionic liquid 1-butyl 3-methyl imidazolium tetrafluoroborate ([BMIM][BF4]) are expanded at room temperature (i.e., the radius of gyration, Rg), scales with molecular weight, Mw, as Rg ? Mw(0.9), instead of the expected self-avoiding walk behavior. The simulations were restricted to fairly short chains, however, which might not be in the true scaling regime. In this work, we investigate a coarse-grained model for the behavior of PEO in [BMIM][BF4]. We use existing force fields for PEO and [BMIM][BF4] and LorentzBerthelot mixing rules for the cross interactions. The coarse-grained model predicts that PEO collapses in the ionic liquid. We also present an integral equation theory for the structure of the ionic liquid and the conformation properties of the polymer. The theory is in excellent agreement with the simulation results. We conclude that the properties of polymers in ionic liquids are unusually sensitive to the details of the intermolecular interactions. The integral equation theory is sufficiently accurate to be a useful guide to computational work. PMID:25310685

  10. Electrotunable Lubricity with Ionic Liquid Nanoscale Films

    NASA Astrophysics Data System (ADS)

    Fajardo, O. Y.; Bresme, F.; Kornyshev, A. A.; Urbakh, M.

    2015-01-01

    One of the main challenges in tribology is finding the way for an in situ control of friction without changing the lubricant. One of the ways for such control is via the application of electric fields. In this respect a promising new class of lubricants is ionic liquids, which are solvent-free electrolytes, and their properties should be most strongly affected by applied voltage. Based on a minimal physical model, our study elucidates the connection between the voltage effect on the structure of the ionic liquid layers and their lubricating properties. It reveals two mechanisms of variation of the friction force with the surface charge density, consistent with recent AFM measurements, namely via the (i) charge effect on normal and in-plane ordering in the film and (ii) swapping between anion and cation layers at the surfaces. We formulate conditions that would warrant low friction coefficients and prevent wear by resisting ``squeezing-out'' of the liquid under compression. These results give a background for controllable variation of friction.

  11. Electrotunable Lubricity with Ionic Liquid Nanoscale Films

    PubMed Central

    Fajardo, O. Y.; Bresme, F.; Kornyshev, A. A.; Urbakh, M.

    2015-01-01

    One of the main challenges in tribology is finding the way for an in situ control of friction without changing the lubricant. One of the ways for such control is via the application of electric fields. In this respect a promising new class of lubricants is ionic liquids, which are solvent-free electrolytes, and their properties should be most strongly affected by applied voltage. Based on a minimal physical model, our study elucidates the connection between the voltage effect on the structure of the ionic liquid layers and their lubricating properties. It reveals two mechanisms of variation of the friction force with the surface charge density, consistent with recent AFM measurements, namely via the (i) charge effect on normal and in-plane ordering in the film and (ii) swapping between anion and cation layers at the surfaces. We formulate conditions that would warrant low friction coefficients and prevent wear by resisting squeezing-out of the liquid under compression. These results give a background for controllable variation of friction. PMID:25572127

  12. Metal ion adsorption at the ionic liquid-mica interface

    NASA Astrophysics Data System (ADS)

    McDonald, Samila; Elbourne, Aaron; Warr, Gregory G.; Atkin, Rob

    2015-12-01

    Mica has been employed in many studies of ionic liquid (IL) interfaces on account of its atomic smoothness and well defined surface properties. However, until now it has been unclear whether ions dissolved in ILs can compete with the IL cation and adsorb to mica charge sites. In this work amplitude modulated atomic force microscopy (AM-AFM) has been used to probe metal ion adsorption at the interface of mica with propylammonium nitrate (PAN), a room temperature IL. Lithium, sodium, potassium, magnesium and calcium nitrate salts were added to PAN at a concentration of ~60 mM. Aluminum nitrate was also investigated, but only at 5 mM because its solubility in PAN is much lower. The AM-AFM images obtained when the metal ions were present are strikingly different to that of pure PAN, indicating that the ions compete effectively with the propylammonium cation and adsorb to negatively charged sites on the mica surface despite their much lower concentration. This is a consequence of electrostatic attractions between the mica charge sites and the metal ions being significantly stronger than for the propylammonium cation; compared to the metal ions the propylammonium charged group is relatively constrained sterically. A distinct honeycomb pattern is noted for the PAN + Al3+ system, less obviously for the divalent ions and not at all for monovalent ions. This difference is attributed to the strength of electrostatic interactions between metal ions and mica charge sites increasing with the ion charge, which means that divalent and (particularly) trivalent ions are located more precisely above the charged sites of the mica lattice. The images obtained allow important distinctions between metal ion adsorption at mica-water and mica-PAN interfaces to be made.Mica has been employed in many studies of ionic liquid (IL) interfaces on account of its atomic smoothness and well defined surface properties. However, until now it has been unclear whether ions dissolved in ILs can compete with the IL cation and adsorb to mica charge sites. In this work amplitude modulated atomic force microscopy (AM-AFM) has been used to probe metal ion adsorption at the interface of mica with propylammonium nitrate (PAN), a room temperature IL. Lithium, sodium, potassium, magnesium and calcium nitrate salts were added to PAN at a concentration of ~60 mM. Aluminum nitrate was also investigated, but only at 5 mM because its solubility in PAN is much lower. The AM-AFM images obtained when the metal ions were present are strikingly different to that of pure PAN, indicating that the ions compete effectively with the propylammonium cation and adsorb to negatively charged sites on the mica surface despite their much lower concentration. This is a consequence of electrostatic attractions between the mica charge sites and the metal ions being significantly stronger than for the propylammonium cation; compared to the metal ions the propylammonium charged group is relatively constrained sterically. A distinct honeycomb pattern is noted for the PAN + Al3+ system, less obviously for the divalent ions and not at all for monovalent ions. This difference is attributed to the strength of electrostatic interactions between metal ions and mica charge sites increasing with the ion charge, which means that divalent and (particularly) trivalent ions are located more precisely above the charged sites of the mica lattice. The images obtained allow important distinctions between metal ion adsorption at mica-water and mica-PAN interfaces to be made. Electronic supplementary information (ESI) available: Ion diameter distribution (grain size analysis) for the PAN + metal ion solutions. See DOI: 10.1039/c5nr05833c

  13. Development of an Analytical Method Based on Temperature Controlled Solid-Liquid Extraction Using an Ionic Liquid as Solid Solvent.

    PubMed

    Pan, Zhongwei; Wang, Zhengquan; Zhu, Linna; Zhu, Zhiming; Cai, Jinying; Shen, Xiaoman; Fan, Tingli; Zhang, Yingnan; Chen, Zhixiu

    2015-01-01

    At the present paper, an analytical method based on temperature controlled solid-liquid extraction (TC-SLE) utilizing a synthesized ionic liquid, (N-butylpyridinium hexafluorophosphate, [BPy]PF₆), as solid solvent and phenanthroline (PT) as an extractant was developed to determine micro levels of Fe(2+) in tea by PT spectrophotometry. TC-SLE was carried out in two continuous steps: Fe(2+) can be completely extracted by PT-[BPy]PF₆ or back-extracted at 80 °C and the two phases were separated automatically by cooling to room temperature. Fe(2+), after back-extraction, needs 2 mol/L HNO₃ as stripping agent and the whole process was determined by PT spectrophotometry at room temperature. The extracted species was neutral Fe(PT)mCl₂ (m = 1) according to slope analysis in the Fe(2+)-[BPy]PF₆-PT TC-SLE system. The calibration curve was Y = 0.20856X - 0.000775 (correlation coefficient = 0.99991). The linear calibration range was 0.10-4.50 μg/mL and the limit of detection for Fe(2+) is 7.0 × 10(-2) μg/mL. In this method, the contents of Fe(2+) in Tieguanyin tea were determined with RSDs (n = 5) 3.05% and recoveries in range of 90.6%-108.6%. PMID:26690398

  14. Ionic Liquid assisted Synthesis of Zeolite-TON

    PubMed Central

    Tian, Yuyang; McPherson, Matthew J; Wheatley, Paul S; Morris, Russell E

    2014-01-01

    An ionic liquid assisted strategy for the synthesis of zeolitic material is reported. This strategy is a solid state synthetic method and the ionic liquid is employed as structure directing agent. A TON-type zeolite, which contains one-dimensional 10-member-ring, is successfully synthesized with the assistance of the ionic liquid, 1-ethyl-3-methylimidazolium bromide. This finding improves our understanding about the challenge of ionothermally synthesizing siliceous and aluminosilicate zeolites. PMID:26213423

  15. Layering of ionic liquids on rough surfaces.

    PubMed

    Sheehan, Alexis; Jurado, L Andres; Ramakrishna, Shivaprakash N; Arcifa, Andrea; Rossi, Antonella; Spencer, Nicholas D; Espinosa-Marzal, Rosa M

    2016-02-11

    Understanding the behavior of ionic liquids (ILs) either confined between rough surfaces or in rough nanoscale pores is of great relevance to extend studies performed on ideally flat surfaces to real applications. In this work we have performed an extensive investigation of the structural forces between two surfaces with well-defined roughness (<9 nm RMS) in 1-hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide by atomic force microscopy. Statistical studies of the measured layer thicknesses, layering force, and layering frequency reveal the ordered structure of the rough IL-solid interface. Our work shows that the equilibrium structure of the interfacial IL strongly depends on the topography of the contact. PMID:26821595

  16. Durable electrooptic devices comprising ionic liquids

    DOEpatents

    Agrawal, Anoop (Tucson, AZ); Cronin, John P. (Tucson, AZ); Tonazzi, Juan C. L. (Tucson, AZ); Warner, Benjamin P. (Los Alamos, NM); McCleskey, T. Mark (Los Alamos, NM); Burrell, Anthony K. (Los Alamos, NM)

    2005-11-01

    Electrolyte solutions for electrochromic devices such as rear view mirrors and displays with low leakage currents are prepared using inexpensive, low conductivity conductors. Preferred electrolytes include bifunctional redox dyes and molten salt solvents with enhanced stability toward ultraviolet radiation. The solvents include lithium or quaternary ammonium cations, and perfluorinated sulfonylimide anions selected from trifluoromethylsulfonate (CF3SO3-), bis(trifluoromethylsulfonyl)imide ((CF3SO2)2N-), bis(perfluoroethylsulfonyl)imide ((CF3CF2SO2)2N-) and tris(trifluoromethylsulfonyl)methide ((CF3SO2)3C-). Electroluminescent, electrochromic and photoelectrochromic devices with nanostructured electrodes include ionic liquids with bifunctional redox dyes.

  17. Characteristics of an ionic liquid electrolyte for sodium-ion batteries

    NASA Astrophysics Data System (ADS)

    Hasa, Ivana; Passerini, Stefano; Hassoun, Jusef

    2016-01-01

    We study the liquid mixture of sodium bis(trifluoromethanesulfonyl)imide in N-butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide (Pyr14TFSI-NaTFSI) for application in sodium-ion batteries. The ionic liquid-based electrolyte is characterized in terms of electrochemical and thermal properties. Ionic conductivity and electrochemical stability windows are evaluated through electrochemical impedance spectroscopy (EIS) measurements and voltammetry tests, respectively. The thermal stability is evaluated by differential scanning calorimetry (DSC) and thermo-gravimetric analysis (TGA). Moreover, the suitability of the IL-electrolyte is preliminary verified in half and in full-cells at room temperature, using P2-Na0.6Ni0.22Fe0.11Mn0.66O2 layered oxide cathode and nanostructured Sb-C composite anode. The cell shows promising characteristics with a working voltage of about 2.7V and a delivered capacity of about 100mAh g-1. Despite requiring further optimization in terms of cycle life and energy density, the data here reported suggest the suitability of the ionic liquid electrolyte for application in sodium-ion battery.

  18. Interactions in the ionic liquid [EMIM][FAP]: a coupled experimental and computational analysis.

    PubMed

    Voroshylova, Iuliia V; Teixeira, Filipe; Costa, Renata; Pereira, Carlos M; Cordeiro, M Natlia D S

    2016-01-20

    Gas-phase electronic and structural properties of the room temperature ionic liquid 1-ethyl-3-methylimidazolium tris(perfluoroethyl)trifluorophosphate ([EMIM][FAP]) were studied using density functional theory, and confirmed with results from infrared spectroscopy. A conformational analysis allowed the identification of several plausible conformers of the ion pairs. For the detected conformers, the infrared spectra were predicted and their thermodynamic properties were evaluated. The topology of the electronic density of the most stable conformers of [EMIM][FAP] ion pairs were characterised using the quantum theory of atoms in molecules. A number of possible hydrogen bonds between the cations and anions of the ionic liquid were identified. Excellent correspondence was found between the predicted spectra of gas-phase [EMIM][FAP] conformers and the experimental infrared spectrum, which in turn allowed a clear attribution of the vibration modes of [EMIM][FAP]. Finally, the contribution of the various conformers of both isomers of the [FAP](-) anion to the ionic liquid macro-properties is shown. PMID:26699428

  19. On the radiation stability of crown ethers in ionic liquids.

    PubMed

    Shkrob, Ilya A; Marin, Timothy W; Dietz, Mark L

    2011-04-14

    Crown ethers (CEs) are macrocyclic ionophores used for the separation of strontium-90 from acidic nuclear waste streams. Room temperature ionic liquids (ILs) are presently being considered as replacements for traditional molecular solvents employed in such separations. It is desirable that the extraction efficacy obtained with such solvents should not deteriorate in the strong radiation fields generated by decaying radionuclides. This deterioration will depend on the extent of radiation damage to both the IL solvent and the CE solute. While radiation damage to ILs has been extensively studied, the issue of the radiation stability of crown ethers, particularly in an IL matrix, has not been adequately addressed. With this in mind, we have employed electron paramagnetic resonance (EPR) spectroscopy to study the formation of CE-related radicals in the radiolysis of selected CEs in ILs incorporating aromatic (imidazolium and pyridinium) cations. The crown ethers have been found to yield primarily hydrogen loss radicals, H atoms, and the formyl radical. In the low-dose regime, the relative yield of these radicals increases linearly with the mole fraction of the solute, suggesting negligible transfer of the excitation energy from the solvent to the solute; that is, the solvent has a "radioprotective" effect. The damage to the CE in the loading region of practical interest is relatively low. Under such conditions, the main chemical pathway leading to decreased extraction performance is protonation of the macrocycle. At high radiation doses, sufficient to increase the acidity of the IL solvent significantly, such proton complexes compete with the solvent cations as electron traps. In this regime, the CEs will rapidly degrade as the result of H abstraction from the CE ring by the released H atoms. Thus, the radiation dose to which a CE/IL system is exposed must be maintained at a level sufficiently low to avoid this regime. PMID:21410191

  20. Metal ion adsorption at the ionic liquid-mica interface.

    PubMed

    McDonald, Samila; Elbourne, Aaron; Warr, Gregory G; Atkin, Rob

    2015-12-23

    Mica has been employed in many studies of ionic liquid (IL) interfaces on account of its atomic smoothness and well defined surface properties. However, until now it has been unclear whether ions dissolved in ILs can compete with the IL cation and adsorb to mica charge sites. In this work amplitude modulated atomic force microscopy (AM-AFM) has been used to probe metal ion adsorption at the interface of mica with propylammonium nitrate (PAN), a room temperature IL. Lithium, sodium, potassium, magnesium and calcium nitrate salts were added to PAN at a concentration of ?60 mM. Aluminum nitrate was also investigated, but only at 5 mM because its solubility in PAN is much lower. The AM-AFM images obtained when the metal ions were present are strikingly different to that of pure PAN, indicating that the ions compete effectively with the propylammonium cation and adsorb to negatively charged sites on the mica surface despite their much lower concentration. This is a consequence of electrostatic attractions between the mica charge sites and the metal ions being significantly stronger than for the propylammonium cation; compared to the metal ions the propylammonium charged group is relatively constrained sterically. A distinct honeycomb pattern is noted for the PAN + Al(3+) system, less obviously for the divalent ions and not at all for monovalent ions. This difference is attributed to the strength of electrostatic interactions between metal ions and mica charge sites increasing with the ion charge, which means that divalent and (particularly) trivalent ions are located more precisely above the charged sites of the mica lattice. The images obtained allow important distinctions between metal ion adsorption at mica-water and mica-PAN interfaces to be made. PMID:26661934

  1. Inhibition of amyloid formation by ionic liquids: ionic liquids affecting intermediate oligomers.

    PubMed

    Kalhor, Hamid Reza; Kamizi, Mostafa; Akbari, Jafar; Heydari, Akbar

    2009-09-14

    In searching for alternative ways to reduce or inhibit amyloid formation, we have studied this process using hen egg white lysozyme (HEWL) in the presence of a low concentration of protic ionic liquids. The ionic liquids were synthesized in a combinatorial fashion maintaining the cationic part (tetramethylguanidinium) with alteration of the anionic component of each compound tested. It was observed that one of these compounds (tetramethylguanidinium acetate) inhibited amyloid formation of HEWL in vitro by nearly 50%. Examination under transmission electron microscopy confirmed the fibril inhibition, and fibrils were observed to be morphologically thinner. To investigate the mechanism of inhibition, intrinsic fluorescence, ANS binding, and circular dichroism analyses were performed. These analyses indicated that the native structure of HEWL was maintained in the presence of the ionic liquid. Performing native PAGE and nondenaturing agarose electrophoresis, it became evident that some of the intermediate oligomers were not converted to protofibrils and that the oligomers were trapped in more stable conformations. Additionally, it was observed that this inhibitory effect was related to the ionic liquid itself and not the solvated ions. It also became evident that the carboxyl functional group was important in the inhibition. The size of the anions and kosmotropicity did not play significant roles in the fibril inhibition. PMID:19678699

  2. Highly luminescent and color-tunable salicylate ionic liquids

    DOE PAGESBeta

    Campbell, Paul S.; Yang, Mei; Pitz, Demian; Cybinska, Joanna; Mudring, Anja -Verena

    2014-03-11

    High quantum yields of up to 40.5 % can be achieved in salicylate-bearing ionic liquids. A range of these ionic liquids have been synthesized and their photoluminescent properties studied in detail. The differences noted can be related back to the structure of the ionic liquid cation and possible interionic interactions. It is found that shifts of emission, particularly in the pyridinium-based ionic liquids, can be related to cation–anion pairing interactions. Furthermore, facile and controlled emission color mixing is demonstrated through combining different ILs, with emission colors ranging from blue to yellow.

  3. Lipid extraction from microalgae using a single ionic liquid

    DOEpatents

    Salvo, Roberto Di; Reich, Alton; Dykes, Jr., H. Waite H.; Teixeira, Rodrigo

    2013-05-28

    A one-step process for the lysis of microalgae cell walls and separation of the cellular lipids for use in biofuel production by utilizing a hydrophilic ionic liquid, 1-butyl-3-methylimidazolium. The hydrophilic ionic liquid both lyses the microalgae cell walls and forms two immiscible layers, one of which consists of the lipid contents of the lysed cells. After mixture of the hydrophilic ionic liquid with a suspension of microalgae cells, gravity causes a hydrophobic lipid phase to move to a top phase where it is removed from the mixture and purified. The hydrophilic ionic liquid is recycled to lyse new microalgae suspensions.

  4. Highly luminescent and color-tunable salicylate ionic liquids

    SciTech Connect

    Campbell, Paul S.; Yang, Mei; Pitz, Demian; Cybinska, Joanna; Mudring, Anja -Verena

    2014-03-11

    High quantum yields of up to 40.5 % can be achieved in salicylate-bearing ionic liquids. A range of these ionic liquids have been synthesized and their photoluminescent properties studied in detail. The differences noted can be related back to the structure of the ionic liquid cation and possible interionic interactions. It is found that shifts of emission, particularly in the pyridinium-based ionic liquids, can be related to cationanion pairing interactions. Furthermore, facile and controlled emission color mixing is demonstrated through combining different ILs, with emission colors ranging from blue to yellow.

  5. Ionic Liquids and Ionizing Radiation: Reactivity of Highly Energetic Species

    SciTech Connect

    Wishart, J.F.

    2010-11-04

    Due to their unique properties, ionic liquids present many opportunities for basic research on the interactions of radiation with materials under conditions not previously available. At the same time, there are practical applied reasons for characterizing, understanding, and being able to predict how ionic-liquid-based devices and industrial-scale systems will perform under conditions of extreme reactivity, including radiation. This perspective discusses current issues in ionic liquid physical chemistry, provides a brief introduction to radiation chemistry, draws attention to some key findings in ionic liquid radiation chemistry, and identifies some current hot topics and new opportunities.

  6. Aprotic Heterocyclic Anion Triazolide Ionic Liquids - A New Class of Ionic Liquid Anion Accessed by the Huisgen Cycloaddition Reaction

    SciTech Connect

    Thompson, Robert L.; Damodaran, Krishnan; Luebke, David; Nulwala, Hunaid

    2013-06-01

    The triazole core is a highly versatile heterocyclic ring which can be accessed easily with the Cu(I)-catalyzed Huisgen cycloaddition reaction. Herein we present the preparation of ionic liquids that incorporate a 1,2,3-triazolide anion. These ionic liquids were prepared by a facile procedure utilizing a base-labile pivaloylmethyl group at the 1-position, which can act as precursors to 1H- 4-substituted 1,2,3-triazole. These triazoles were then subsequently converted into ionic liquids after deprotonation using an appropriate ionic liquid cation hydroxide. The densities and thermal decompositions of these ionic liquids were measured. These novel ionic liquids have potential applications in gas separations and in metal-free catalysis.

  7. Toxicity of ionic liquids prepared from biomaterials.

    PubMed

    Gouveia, W; Jorge, T F; Martins, S; Meireles, M; Carolino, M; Cruz, C; Almeida, T V; Arajo, M E M

    2014-06-01

    In search of environmentally-friendly ionic liquids (ILs), 14 were prepared based on the imidazolium, pyridinium and choline cations, with bromide and several amino acids as anions. Good yields were obtained in the synthesis of pyridinium ILs and those prepared from choline and amino acids. Four of the ILs synthesized from choline and the amino acids arginine, glutamine, glutamic acid and cystine are described here for the first time. The toxicity of the synthesized ILs was checked against organisms of various levels of organization: the crustacean Artemia salina; Human cell HeLa (cervical carcinoma); and bacteria with different types of cell wall, Bacillus subtilis and Escherichia coli. The toxicity was observed to depend on both the cation and anion. Choline-amino acid ILs showed a remarkable low toxicity to A. salina and HeLa cell culture, ten times less than imidazolium and pyridinium ILs. None of ionic liquids exhibited marked toxicity to bacteria, and the effect was 2-3 orders of magnitude smaller than that of the antibiotic chloramphenicol. PMID:24268343

  8. Oxygen Extraction from Regolith Using Ionic Liquids

    NASA Technical Reports Server (NTRS)

    Barrios, Elizabeth A.; Curreri, Peter A.; Karr, Laurel J.

    2011-01-01

    An important concern with long-duration manned space travel is the need to furnish enough materials to the vehicle, as well as the crew, for the duration of the mission. By extracting oxygen from the oxides present in regolith, propellant and life support could be supplied to the vehicle and the crew while in space, thereby limiting the amount of supplies needed prior to lift-off. Using a class of compounds known as ionic liquids, we have been able to lower the electrolysis operating temperature from 1600 C (molten oxide electrolysis) to less than 200 C, making this process much more feasible in terms of energy consumption and materials handling. To make this process ready for deployment into space, we have investigated what steps of the process would be affected by the low-gravity environment in space. In the lab, the solubilization of lunar regolith simulant in ionic liquid produces water vapor that is normally distilled out of solution and subsequently electrolyzed for oxygen production. This distillation is not possible in space, so we have tested a method known as pervaporation and have suggested a way this technique could be incorporated into a reactor design.

  9. Molecular dynamics studies of ionically conducting glasses and ionic liquids: Wave number dependence of intermediate scattering function

    NASA Astrophysics Data System (ADS)

    Habasaki, J.; Ngai, K. L.

    2010-09-01

    Dynamical heterogeneity is a key feature to characterize both acceleration and slowing down of the dynamics in interacting disordered materials. In the present work, the heterogeneous ion dynamics in both ionically conducting glass and in room temperature ionic liquids are characterized by the combination of the concepts of Lvy distribution and multifractality. Molecular dynamics simulation data of both systems are analyzed to obtain the fractional power law of the k-dependence of the dynamics, which implies the Lvy distribution of length scale. The multifractality of the motion and structures makes the system more complex. Both contributions in the dynamics become separable by using g(k,t) derived from the intermediate scattering function, Fs(k,t). When the Lvy index obtained from Fs(k,t) is combined with fractal dimension analysis of random walks and multifractal analysis, all the spatial exponent controlling both fast and slow dynamics are clarified. This analysis is generally applicable to other complex interacting systems and is deemed beneficial for understanding their dynamics.

  10. Performance of Multi Walled Carbon Nanotubes Grown on Conductive Substrates as Supercapacitors Electrodes using Organic and Ionic liquid electrolytes

    NASA Astrophysics Data System (ADS)

    Winchester, Andrew; Ghosh, Sujoy; Turner, Ben; Zhang, X. F.; Talapatra, Saikat

    2012-02-01

    In this work we will present the use of Multi Walled Carbon Nanotubes (MWNT) directly grown on inconel substrates via chemical vapor deposition, as electrode materials for electrochemical double layer capacitors (EDLC). The performance of the MWNT EDLC electrodes were investigated using two electrolytes, an organic electrolyte, tetraethylammonium tetrafluoroborate in propylene carbonate (Et4NBF4 in PC), and a room temperature ionic liquid, 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6). Cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy measurements to obtain values for the capacitance and internal resistance of these devices will be presented and compared.

  11. Structural and electrochemical properties of succinonitrile-based gel polymer electrolytes: role of ionic liquid addition.

    PubMed

    Suleman, Mohd; Kumar, Yogesh; Hashmi, S A

    2013-06-20

    Experimental studies on the novel compositions of gel polymer electrolytes, comprised of plastic crystal succinonitrile (SN) dispersed with pyrrolidinium and imidazolium-based ionic liquids (ILs) entrapped in a host polymer poly(vinylidine fluoride-co-hexafluoropropylene) (PVdF-HFP), are reported. The gel electrolytes are in the form of free-standing films with excellent mechanical, thermal, and electrochemical stability. The introduction of even a small content (~1 wt %) of ionic liquid (1-butyl-1-methylpyrrolidinium bis(trifluoromethyl-sulfonyl)imide (BMPTFSI) or 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMITf) in the PVdF-HFP/SN system (1:4 w/w) enhances the electrical conductivity by 4 orders of magnitude, that is, from ~10(-7) to ~10(-3) S cm(-1) at room temperature. The structural changes due to the entrapment of SN or SN/ILs mixtures and ion-SN-polymer interactions are examined by Fourier transform infrared (FTIR)/Raman spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimmetry (DSC). Various physicochemical properties and fast ion conduction in the gel polymer membranes show their promising characteristics as electrolytes in different ionic devices including supercapacitors. PMID:23758408

  12. Temperature-dependent structure of ionic liquids: X-ray scattering and simulations

    SciTech Connect

    Kashyap, Hemant K.; Santos, Cherry S.; Annapureddy, Harsha V.R.; Murthy, N. Sanjeeva; Margulis, Claudio J.; Castner, Jr., Edward W.

    2015-10-15

    In this article we determine the temperature-dependent structure of the tetradecyltrihexylphosphonium bis(trifluoromethylsulfonyl)amide ionic liquid using a combination of X-ray scattering and molecular dynamics simulations. As in many other room-temperature ionic liquids three characteristic intermolecular peaks can be detected in the structure function S(q). A prepeak or first sharp diffraction peak is observed at about q = 0.42 {angstrom}{sup -1}. Long range anion-anion correlations are the most important contributors to this peak. In all systems we have studied to date, this prepeak is a signature of solvation asymmetry. The peak in S(q) near q = 0.75 {angstrom}{sup -1} is the signature of ionic alternation and arises from the charge ordered separation of ions of the same charge. The most intense diffraction peak near q = 1.37 {angstrom}{sup -1} arises from short-range separation between ions of opposite charge combined with a significant contribution from cationic carbon-carbon interactions, indicating that cationic hydrophobic tails have significant contacts.

  13. Volatilisation of ferrocene from ionic liquids: kinetics and mechanism.

    PubMed

    Fu, Chaopeng; Aldous, Leigh; Dickinson, Edmund J F; Manan, Ninie S A; Compton, Richard G

    2011-07-01

    The evaporation of dissolved ferrocene from non-volatile ionic liquids under a flow of nitrogen gas has been monitored voltammetrically and modelled mathematically. The rate of volatilisation was found to depend on the surface tension of the ionic liquid, and a model is presented. PMID:21607282

  14. Ionic Liquids and Green Chemistry: A Lab Experiment

    ERIC Educational Resources Information Center

    Stark, Annegret; Ott, Denise; Kralisch, Dana; Kreisel, Guenter; Ondruschka, Bernd

    2010-01-01

    Although ionic liquids have been investigated as solvents for many applications and are starting to be used in industrial processes, only a few lab experiments are available to introduce students to these materials. Ionic liquids have been discussed in the context of green chemistry, but few investigations have actually assessed the degree of…

  15. Ionic Liquids and Green Chemistry: A Lab Experiment

    ERIC Educational Resources Information Center

    Stark, Annegret; Ott, Denise; Kralisch, Dana; Kreisel, Guenter; Ondruschka, Bernd

    2010-01-01

    Although ionic liquids have been investigated as solvents for many applications and are starting to be used in industrial processes, only a few lab experiments are available to introduce students to these materials. Ionic liquids have been discussed in the context of green chemistry, but few investigations have actually assessed the degree of

  16. Hydrophobic ionic liquids based on the 1-butyl-3-methylimidazolium cation for lithium/seawater batteries

    NASA Astrophysics Data System (ADS)

    Zhang, Yancheng; Urquidi-Macdonald, Mirna

    Two hydrophobic ionic liquids (room temperature molten salts) based on 1-butyl-3-methylimidazolium cation (BMI +), BMI +PF 6- and BMI +Tf 2N -, were used in developing a highly efficient lithium anode system for lithium/seawater batteries. The lithium anode system was composed of lithium metal/ionic liquid/Celgard membrane. Both BMI +PF 6-and BMI +Tf 2N - maintained high apparent anodic efficiency (up to 100%) under potentiostatic polarization (at +0.5 V versus open-circuit potential (OCP)) in a 3% NaCl solution. Eventually, traces of water contaminated the ionic liquid and a bilayer film (LiH and LiOH) on the lithium surface was formed, decreasing the rate of lithium anodic reaction and hence the discharge current density. BMI +Tf 2N - prevented traces of water from reaching the lithium metal surface longer than BMI +PF 6- (60 h versus 7 h). However, BMI +PF 6- was better than BMI +Tf 2N - in keeping a constant current density (0.2 mA cm -2) before the traces of water contaminated the lithium surface due to the non-reactivity of BMI +PF 6- with the lithium metal that kept the bare lithium surface. During the discharge process, BMI +PF 6- and BMI +Tf 2N - acted as ion transport media of Li +, Cl -, OH - and H 2O, but did not react with them because of the excellent chemical stability, high conductivity, and high hydrophobicity of these two ionic liquids. Both BMI +PF 6- and BMI +Tf 2N - gels were tentative approaches used to delay the traces of water coming in contact with the lithium surface.

  17. Synthesis and characterization of ionic liquid immobilized on magnetic nanoparticles: A recyclable heterogeneous organocatalyst for the acetylation of alcohols

    NASA Astrophysics Data System (ADS)

    Ghorbani-Choghamarani, Arash; Norouzi, Masoomeh

    2016-03-01

    Herein, we describe a simple and efficient procedure for the preparation of 3-((3-(trisilyloxy)propyl)propionamide)-1-methylimidazolium chloride ionic liquid supported on magnetic nanoparticle (TPPA-IL-Fe3O4). The structure of this magnetic ionic liquid is fully characterized by FT-IR, TGA, XRD, VSM, SEM, EDX and DLS techniques. TPPA-IL-Fe3O4 is employed as a catalyst for the acetylation of alcohols with acetic anhydride under mild and heterogeneous conditions at room temperature with good to excellent yields. The magnetic catalyst could be readily separate from the reaction media by simple magnetic decantation, and reused several times without significant loss of its catalytic activity.

  18. Interactions between water and 1-butyl-1-methylpyrrolidinium ionic liquids.

    PubMed

    Fadeeva, Tatiana A; Husson, Pascale; DeVine, Jessalyn A; Costa Gomes, Margarida F; Greenbaum, Steven G; Castner, Edward W

    2015-08-14

    We report experimental results on the diffusivity of water in two ionic liquids obtained using the pulsed-gradient spin-echo NMR method. Both ionic liquids have the same cation, 1-butyl-1-methylpyrrolidinium, but different trifluoromethyl-containing anions. One has a strongly hydrophobic anion, bis(trifluoromethylsulfonyl)amide, while the second has a hydrophilic anion, trifluoromethylsulfonate. Transport of water in these ionic liquids is much faster than would be predicted from hydrodynamic laws, indicating that the neutral water molecules experience a very different friction than the anions and cations at the molecular level. Temperature-dependent viscosities, conductivities, and densities are reported as a function of water concentration to further analyze the properties of the ionic liquid-water mixtures. These results on the properties of water in ionic liquids should be of interest to researchers in diverse areas ranging from separations, solubilizing biomass and energy technologies. PMID:26277141

  19. Interactions between water and 1-butyl-1-methylpyrrolidinium ionic liquids

    NASA Astrophysics Data System (ADS)

    Fadeeva, Tatiana A.; Husson, Pascale; DeVine, Jessalyn A.; Costa Gomes, Margarida F.; Greenbaum, Steven G.; Castner, Edward W.

    2015-08-01

    We report experimental results on the diffusivity of water in two ionic liquids obtained using the pulsed-gradient spin-echo NMR method. Both ionic liquids have the same cation, 1-butyl-1-methylpyrrolidinium, but different trifluoromethyl-containing anions. One has a strongly hydrophobic anion, bis(trifluoromethylsulfonyl)amide, while the second has a hydrophilic anion, trifluoromethylsulfonate. Transport of water in these ionic liquids is much faster than would be predicted from hydrodynamic laws, indicating that the neutral water molecules experience a very different friction than the anions and cations at the molecular level. Temperature-dependent viscosities, conductivities, and densities are reported as a function of water concentration to further analyze the properties of the ionic liquid-water mixtures. These results on the properties of water in ionic liquids should be of interest to researchers in diverse areas ranging from separations, solubilizing biomass and energy technologies.

  20. Ionic liquid assisted electrospun cellulose acetate fibers for aqueous removal of triclosan.

    PubMed

    Zhang, Gong; Sun, Meng; Liu, Yang; Liu, Huijuan; Qu, Jiuhui; Li, Jinghong

    2015-02-10

    The cellulose acetate (CA) membrane prepared via electrospun was innovatively utilized as fiber-adsorbent for the separation of aqueous triclson (TCS). It was found that the presence of the room temperature ionic liquid (RTIL) in the precursor amplified electric force toward the CA-solution, thereby benefiting the formation of CA fibers. The as-spun CA fibers exhibit excellent adsorptive performance toward TCS, with fast adsorption kinetics, and the maximum adsorption capacity achieved to 797.7 mg g(-1), which established much better performance in contrast to conventional adsorbents. We proposed that the adsorption of TCS onto CA fibers was primarily facilitated by the hydrogen bonding between the abundant carbonyl, hydroxyl groups of CA surface, and the hydrogen atoms of phenol functional groups in TCS molecular. PMID:25595432

  1. Creating nanoparticle stability in ionic liquid [C4mim][BF4] by inducing solvation layering.

    PubMed

    Gao, Jingsi; Ndong, Rose S; Shiflett, Mark B; Wagner, Norman J

    2015-03-24

    The critical role of solvation forces in dispersing and stabilizing nanoparticles and colloids in 1-butyl-3-methylimidazolium tetrafluoroborate [C4mim][BF4] is demonstrated. Stable silica nanoparticle suspensions over 60 wt % solids are achieved by particle surface chemical functionalization with a fluorinated alcohol. A combination of techniques including rheology, dynamic light scattering (DLS), transmission electron microscopy (TEM), and small angle neutron scattering (SANS) are employed to determine the mechanism of colloidal stability. Solvation layers of ?5 nm at room temperature are measured by multiple techniques and are thought to be initiated by hydrogen bonds between the anion [BF4](-) and the fluorinated group on the surface coating. Inducing structured solvation layering at particle surfaces through hydrogen bonding is demonstrated as a method to stabilize particles in ionic liquids. PMID:25758381

  2. Pressure-induced amorphization of ionic liquid [HMIM][PF6

    NASA Astrophysics Data System (ADS)

    Ren, Yufen; Li, Haining; Zhu, Xiang; Chen, Liucheng; Su, Lei; Yang, Kun; Yang, Guoqiang; Wang, Hua

    2015-06-01

    Phase behavior of ionic liquid [HMIM][PF6] has been investigated under high pressure up to 5.6 GPa at room temperature. The results indicated that [HMIM][PF6] might experience a phase transition at about 3.4 GPa upon compression, which could be identified as solidification to superpressurized glass by ruby R1 line broadening measurement and synchrotron X-ray diffraction (XRD) patterns. For conformational equilibrium, the fraction of all-anti (AAAA) conformer increased upon compression, while the conformational change was independent of temperature. These facts indicated that there were large differences of the structure in response to the extreme conditions, especially in the structure of the cation.

  3. Toward organization of cyano-bridged coordination polymer nanoparticles within an ionic liquid crystal.

    PubMed

    Larionova, Joulia; Guari, Yannick; Blanc, Christophe; Dieudonne, Philippe; Tokarev, Alexei; Guerin, Christian

    2009-01-20

    Size controlled cyano-bridged coordination polymer nanoparticles Mn1.5[Cr(CN)6] have been synthesized and organized at the nanolevel by using the room temperature ionic liquid crystal (ILC) C12-MIMBF4. The as-obtained material was studied by transmission electron microscopy (TEM), differential scanning calorimetry (DSC), optical microscopy, and X-ray diffraction. These analyses reveal the presence of a long-range organization of cyano-bridged nanoparticles at the nanoscale level within the ILC phase. The magnetic study of these nanoparticles reveals an appearance of a nanocluster-glass-like regime caused by magnetostatic interactions between neighboring nanoparticles. The properties of these organized nanoparticles have been compared with the properties of nanoparticles of the same composition and stoichiometry obtained and randomly dispersed into the isotropic IL C10-MIMBF4. PMID:19177655

  4. Non-aqueous aluminium-air battery based on ionic liquid electrolyte

    NASA Astrophysics Data System (ADS)

    Revel, Renaud; Audichon, Thomas; Gonzalez, Serge

    2014-12-01

    A promising metal-air secondary battery based on aluminium-oxygen couple is described. In this paper, we observed that an aluminium-air battery employing EMImCl, AlCl3 room temperature ionic liquid (RTIL) as electrolyte and aluminium as negative electrode, has an exceptional reduced self-discharged rate. Due to its new and innovative type of electrolyte, this aluminium-air battery can support relatively high current densities (up to 0.6 mA cm-2) and an average voltage of 0.6-0.8 V. Such batteries may find immediate applications, as they can provide an internal, built-in autonomous and self-sustained energy source.

  5. Ultrasound promoted synthesis of quinolines using basic ionic liquids in aqueous media as a green procedure.

    PubMed

    Kowsari, Elaheh; Mallakmohammadi, M

    2011-01-01

    The basic ionic liquid (BIL) based on imidazolum cation efficiently catalyzes the condensation reaction of isatin with ketones by ultrasonic irradiation in aqueous media for quinoline synthesis. When two different ?-protons are available in a ketone, a mixture of two quinolines is obtained. In this method, one of the quinolines with high selectivity is produced. Another significant advantage of this method is omission of subsidiary reactions, such as aldol condensation. Compared with conventional methods, the main advantages of the present procedure are its being a green method, its milder conditions, necessary shorter reaction time, and its higher yields and selectivity without the need for a transition metal catalyst. The use of BILs and ultrasound promoted this protocol under room temperature. By changing the type of BILs, ultrasonic irradiation time, and ultrasonic frequency, synthesis of quinolines is manageable. PMID:20719553

  6. Memory effect in an ionic liquid matrix containing single-walled carbon nanotubes and polystyrene

    NASA Astrophysics Data System (ADS)

    Wei, Di; Baral, Jayanta K.; Österbacka, Ronald; Ivaska, Ari

    2008-02-01

    We report the use of an ionic liquid (IL) gel matrix containing a blend of single-walled carbon nanotubes (SWNTs) and polystyrene (PS) as a memory device. SWNTs and PS beads were mixed in a room-temperature IL, 1-butyl-3-methyl-hexafluorophosphate ([BMIM][PF6]). The composite gel was sandwiched between a bottom ITO glass and a top aluminium electrode. By merely changing the concentrations of SWNTs in the inert insulating PS matrix, we observed several distinct electrical properties of the device, such as an insulator, a memory in terms of switching and negative differential resistance (NDR), and a conductor. The electric bistable switching hops between a higher impedance (OFF) state and a lower impedance (ON) state which is approximately equal to five orders of current decays.

  7. Binding Selectivity of Macrocycle Ionophores in Ionic Liquids versus Aqueous Solution and Solvent-free Conditions.

    PubMed

    Gámez, Francisco; Hortal, Ana R; Hurtado, Paola; Avilés-Moreno, Juan R; Hamad, Said; Martínez-Haya, Bruno

    2015-12-01

    The understanding of supramolecular recognition in room-temperature ionic liquids (RTILs) is key to develop the full potential of these materials. In this work, we provide insights into the selectivity of the binding of alkali metal cations by standard cyclodextrin and calixarene macrocycles in RTILs. A direct laser desorption/ionization mass spectrometry approach is employed to determine the relative abundances of the inclusion complexes formed through competitive binding in RTIL solutions. The results are compared with the binding selectivities measured under solvent-free conditions and in water/methanol solutions. Cyclodextrins and calixarenes in which the peripheral OH groups are substituted by bulkier side groups preferentially bind to Cs(+) . Such specific ionophoric behavior is substantially enhanced by solvation effects in the RTIL. This finding is rationalized with the aid of quantum mechanical calculations, in terms of the conformational features and steric interactions that drive the solvation of the inclusion complexes by the bulky RTIL counterions. PMID:26346407

  8. Homogeneous Liquid-Liquid Extraction of Metal Ions with a Functionalized Ionic Liquid.

    PubMed

    Hoogerstraete, Tom Vander; Onghena, Bieke; Binnemans, Koen

    2013-05-16

    Binary mixtures of the ionic liquid betainium bis(trifluoromethylsulfonyl)imide and water show an upper critical solution temperature. This solvent system has been used to extract metal ions by phase-transition extraction, using zwitterionic betaine as extractant. The system is efficient for the extraction of trivalent rare-earth, indium and gallium ions. This new type of metal extraction system avoids problems associated with the use of viscous ionic liquids, namely, the difficulty of intense mixing of the aqueous and ionic liquid phases by stirring. PMID:26282975

  9. New triazolium based ionic liquid crystals

    SciTech Connect

    Stappert, Kathrin; Unal, Derya; Mallick, Bert; Mudring, Anja-Verena

    2014-01-01

    A set of novel 1,2,3-triazolium based ionic liquid crystals was synthesized and their mesomorphic behaviour studied by DSC (differential scanning calorimetry), POM (polarizing optical microscopy) and SAXS (small angle X-ray scattering). Beside the variation of the chain length (C10, C12 and C14) at the 1,2,3-triazolium cation also the anion has been varied (Br−, I−, I3−, BF4−, SbF6−, N(CN)2−, Tf2N−) to study the influence of ion size, symmetry and H-bonding capability on the mesophase formation. Interestingly, for the 1,3-didodecyl-1,2,3-triazolium cation two totally different conformations were found in the crystal structure of the bromide (U-shaped) and the triiodide (rod shaped).

  10. Durable Electrooptic Devices Comprising Ionic Liquids

    DOEpatents

    Burrell, Anthony K. (Los Alamos, NM); Agrawal, Anoop (Tucson, AZ); Cronin, John P. (Tucson, AZ); Tonazzi, Juan C. L. (Tucson, AZ); Warner, Benjamin P. (Los Alamos, NM); McCleskey, T. Mark (Los Alamos, NM)

    2008-11-11

    Electrolyte solutions for electrochromic devices such as rear view mirrors and displays with low leakage currents are prepared using inexpensive, low conductivity conductors. Preferred electrolytes include bifunctional redox dyes and molten salt solvents with enhanced stability toward ultraviolet radiation. The solvents include lithium or quaternary ammonium cations, and perfluorinated sulfonylimide anions selected from trifluoromethylsulfonate (CF.sub.3SO.sub.3.sup.-), bis(trifluoromethylsulfonyl)imide ((CF.sub.3SO.sub.2).sub.2N.sup.-), bis(perfluoroethylsulfonyl)imide ((CF.sub.3CF.sub.2SO.sub.2).sub.2N.sup.-) and tris(trifluoromethylsulfonyl)methide ((CF.sub.3SO.sub.2).sub.3C.sup.-). Electroluminescent, electrochromic and photoelectrochromic devices with nanostructured electrodes include ionic liquids with bifunctional redox dyes. Some of the electrolyte solutions color to red when devices employing the solutions are powered, leading to red or neutral electrooptic devices.

  11. Microwave-assisted synthesis using ionic liquids.

    PubMed

    Martnez-Palou, Rafael

    2010-02-01

    The research and application of green chemistry principles have led to the development of cleaner processes. In this sense, during the present century an ever-growing number of studies have been published describing the use of ionic liquids (ILs) as solvents, catalysts, or templates to develop more environmentally friendly and efficient chemical transformations for their use in both academia and industry. The conjugation of ILs and microwave irradiation as a non-conventional heating source has shown evident advantages when compared to conventional synthetic procedures for the generation of fast, efficient, and environmental friendly synthetic methodologies. This review focuses on the advances in the use of ILs in organic, polymers and materials syntheses under MW irradiation conditions. PMID:19507045

  12. Metsulfuron-methyl-based herbicidal ionic liquids.

    PubMed

    Pernak, Juliusz; Niemczak, Micha?; Shamshina, Julia L; Gurau, Gabriela; G?owacki, Grzegorz; Praczyk, Tadeusz; Marcinkowska, Katarzyna; Rogers, Robin D

    2015-04-01

    Ten sulfonylurea-based herbicidal ionic liquids (HILs) were prepared by combining the metsulfuron-methyl anion with various cation types including quaternary ammonium ([bis(2-hydroxyethyl)methyloleylammonium](+), [2-hydroxyethyltrimethylammonium](+)), pyridinium ([1-dodecylpyridinium](+)), piperidinium ([1-methyl-1-propylpiperidinium](+)), imidazolium ([1-allyl-3-methylimidazolium](+), [1-butyl-3-methylimidazolium](+)), pyrrolidinium ([1-butyl-1-methylpyrrolidinium](+)), morpholinium ([4-decyl-4-methylmorpholinium](+)), and phosphonium ([trihexyltetradecylphosphonium](+) and [tetrabutylphosphonium](+)). Their herbicidal efficacy was studied in both greenhouse tests and field trials. Preliminary results for the greenhouse tests showed at least twice the activity for all HILs when compared to the activity of commercial Galmet 20 SG, with HILs with phosphonium cations being the most effective. The results of two-year field studies showed significantly less enhancement of activity than observed in the greenhouse; nonetheless, it was found that the herbicidal efficacy was higher than that of the commercial analog, and efficacy varied depending on the plant species. PMID:25734891

  13. Durable electrooptic devices comprising ionic liquids

    DOEpatents

    Burrell, Anthony K. (Los Alamos, NM); Agrawal, Anoop (Tucson, AZ); Cronin, John P. (Tucson, AZ); Tonazzi, Juan C. L. (Tucson, AZ); Warner, Benjamin P. (Los Alamos, NM); McCleskey, T. Mark (Los Alamos, NM)

    2009-12-15

    Electrolyte solutions for electrochromic devices such as rear view mirrors and displays with low leakage currents are prepared using inexpensive, low conductivity conductors. Preferred electrolytes include bifunctional redox dyes and molten salt solvents with enhanced stability toward ultraviolet radiation. The solvents include lithium or quaternary ammonium cations, and perfluorinated sulfonylimide anions selected from trifluoromethylsulfonate (CF.sub.3SO.sub.3.sup.-), bis(trifluoromethylsulfonyl)imide ((CF.sub.3SO.sub.2).sub.2N.sup.-), bis(perfluoroethylsulfonyl)imide ((CF.sub.3CF.sub.2SO.sub.2).sub.2N.sup.-) and tris(trifluoromethylsulfonyl)methide ((CF.sub.3SO.sub.2).sub.3C.sup.-). Electroluminescent, electrochromic and photoelectrochromic devices with nanostructured electrodes include ionic liquids with bifunctional redox dyes. Some of the electrolyte solutions color to red when devices employing the solutions are powered, leading to red or neutral electrooptic devices.

  14. Durable electrooptic devices comprising ionic liquids

    DOEpatents

    Warner, Benjamin P. (Los Alamos, NM); McCleskey, T. Mark (Los Alamos, NM); Burrell, Anthony K. (Los Alamos, NM)

    2006-10-10

    Electrolyte solutions for electrochromic devices such as rear view mirrors and displays with low leakage currents are prepared using inexpensive, low conductivity conductors. Preferred electrolytes include bifunctional redox dyes and molten salt solvents with enhanced stability toward ultraviolet radiation. The solvents include lithium or quaternary ammonium cations, and perfluorinated sulfonylimide anions selected from trifluoromethylsulfonate (CF.sub.3SO.sub.3.sup.-), bis(trifluoromethylsulfonyl)imide ((CF.sub.3SO.sub.2).sub.2N.sup.-), bis(perfluoroethylsulfonyl)imide ((CF.sub.3CF.sub.2SO.sub.2).sub.2N.sup.-) and tris(trifluoromethylsulfonyl)methide ((CF.sub.3SO.sub.2).sub.3C.sup.-). Electroluminescent, electrochromic and photoelectrochromic devices with nanostructured electrodes include ionic liquids with bifunctional redox dyes.

  15. Intermolecular vibrations and fast relaxations in supercooled ionic liquids

    NASA Astrophysics Data System (ADS)

    Ribeiro, Mauro C. C.

    2011-06-01

    Short-time dynamics of ionic liquids has been investigated by low-frequency Raman spectroscopy (4 < ? < 100 cm-1) within the supercooled liquid range. Raman spectra are reported for ionic liquids with the same anion, bis(trifluoromethylsulfonyl)imide, and different cations: 1-butyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium, 1-butyl-1-methylpiperidinium, trimethylbutylammonium, and tributylmethylammonium. It is shown that low-frequency Raman spectroscopy provides similar results as optical Kerr effect (OKE) spectroscopy, which has been used to study intermolecular vibrations in ionic liquids. The comparison of ionic liquids containing aromatic and non-aromatic cations identifies the characteristic feature in Raman spectra usually assigned to librational motion of the imidazolium ring. The strength of the fast relaxations (quasi-elastic scattering, QES) and the intermolecular vibrational contribution (boson peak) of ionic liquids with non-aromatic cations are significantly lower than imidazolium ionic liquids. A correlation length assigned to the boson peak vibrations was estimated from the frequency of the maximum of the boson peak and experimental data of sound velocity. The correlation length related to the boson peak (19 ) does not change with the length of the alkyl chain in imidazolium cations, in contrast to the position of the first-sharp diffraction peak observed in neutron and X-ray scattering measurements of ionic liquids. The rate of change of the QES intensity in the supercooled liquid range is compared with data of excess entropy, free volume, and mean-squared displacement recently reported for ionic liquids. The temperature dependence of the QES intensity in ionic liquids illustrates relationships between short-time dynamics and long-time structural relaxation that have been proposed for glass-forming liquids.

  16. Carbon Dioxide and Ionic Liquid Refrigerants: Compact, Efficient Air Conditioning with Ionic Liquid-Based Refrigerants

    SciTech Connect

    2010-10-01

    BEETIT Project: Notre Dame is developing an air-conditioning system with a new ionic liquid and CO2 as the working fluid. Synthetic refrigerants used in air conditioning and refrigeration systems are potent GHGs and can trap 1,000 times more heat in the atmosphere than CO2 alone—making CO2 an attractive alternative for synthetic refrigerants in cooling systems. However, operating cooling systems with pure CO2 requires prohibitively high pressures and expensive hardware. Notre Dame is creating a new fluid made of CO2 and ionic liquid that enables the use of CO2 at low pressures and requires minimal changes to existing hardware and production lines. This new fluid also produces no harmful emissions and can improve the efficiency of air conditioning systems— enabling new use of CO2 as a refrigerant in cooling systems.

  17. Retreating behavior of a charged ionic liquid droplet in a dielectric liquid under electric field

    NASA Astrophysics Data System (ADS)

    Ahn, Myung Mo; Im, Do Jin; Kang, In Seok

    2013-11-01

    Ionic liquids show great promise as excellent solvents or catalysts in energy and biological fields due to their unique chemical and physical properties. The ionic liquid droplets in microfluidic systems can also be used as a potential platform for chemical biological reactions. In order to control electrically the ionic liquid droplets in a microfluidic device, the charging characteristics of ionic liquid droplets need to be understood. In this work, the charging characteristics of various ionic liquids are investigated by using the parallel plate electrodes system. Under normal situation, a charged droplet shows bouncing motion between electrodes continuously. However, for some special ionic liquids, interesting retreating behavior of charged ionic liquid droplet has been observed. This retreating behavior of ionic liquid droplet has been analyzed experimentally by the image analysis and the electrometer signal analysis. Based on the hypothesis of charge leakage of the retreating ionic liquid droplets, FT-IR spectroscopy analysis has also been performed. The retreating behavior of ionic liquid droplet is discussed from the intermolecular point of view according to the species of ionic liquids. This research was supported by grant No. 2013R1A1A2011956 funded by the Ministry of Science, ICT and Future Planning (MSIP) and by grant No. 2013R1A1A2010483 funded by the Ministry of Education, Science and Technology (MEST) through the NRF.

  18. Electrodrift purification of materials for room temperature radiation detectors

    DOEpatents

    James, Ralph B.; Van Scyoc, III, John M.; Schlesinger, Tuviah E.

    1997-06-24

    A method of purifying nonmetallic, crystalline semiconducting materials useful for room temperature radiation detecting devices by applying an electric field across the material. The present invention discloses a simple technology for producing purified ionic semiconducting materials, in particular PbI.sub.2 and preferably HgI.sub.2, which produces high yields of purified product, requires minimal handling of the material thereby reducing the possibility of introducing or reintroducing impurities into the material, is easy to control, is highly selective for impurities, retains the stoichiometry of the material and employs neither high temperatures nor hazardous materials such as solvents or liquid metals. An electric field is applied to a bulk sample of the material causing impurities present in the sample to drift in a preferred direction. After all of the impurities have been transported to the ends of the sample the current flowing through the sample, a measure of the rate of transport of mobile impurities, falls to a low, steady state value, at which time the end sections of the sample where the impurities have concentrated are removed leaving a bulk sample of higher purity material. Because the method disclosed here only acts on the electrically active impurities, the stoichiometry of the host material remains substantially unaffected.

  19. Electrodrift purification of materials for room temperature radiation detectors

    DOEpatents

    James, R.B.; Van Scyoc, J.M. III; Schlesinger, T.E.

    1997-06-24

    A method of purifying nonmetallic, crystalline semiconducting materials useful for room temperature radiation detecting devices by applying an electric field across the material is disclosed. The present invention discloses a simple technology for producing purified ionic semiconducting materials, in particular PbI{sub 2} and preferably HgI{sub 2}, which produces high yields of purified product, requires minimal handling of the material thereby reducing the possibility of introducing or reintroducing impurities into the material, is easy to control, is highly selective for impurities, retains the stoichiometry of the material and employs neither high temperatures nor hazardous materials such as solvents or liquid metals. An electric field is applied to a bulk sample of the material causing impurities present in the sample to drift in a preferred direction. After all of the impurities have been transported to the ends of the sample the current flowing through the sample, a measure of the rate of transport of mobile impurities, falls to a low, steady state value, at which time the end sections of the sample where the impurities have concentrated are removed leaving a bulk sample of higher purity material. Because the method disclosed here only acts on the electrically active impurities, the stoichiometry of the host material remains substantially unaffected. 4 figs.

  20. Reaction of pharmacological active tris-(2-hydroxyethyl)ammonium 4-chlorophenylsulfanylacetate with ZnCl2 or NiCl2: first conversion of a protic ionic liquid into metallated ionic liquid.

    PubMed

    Mirskova, Anna N; Adamovich, Sergey N; Mirskov, Rudolf G; Schilde, Uwe

    2013-01-01

    The reaction of pharmacological active protic ionic liquid tris-(2-hydroxyethyl)ammonium 4-chlorophenylsulfanylacetate H+N(CH2CH2OH)3 ? (-OOCCH2SC6H4Cl-4) (1) with zinc or nickel chloride in a ratio of 2:1 affords stable at room temperature powder-like adducts [H+N(CH2CH2OH)3]2 ? [M(OOCCH2SC6H4Cl-4)2Cl2]2-, M = Zn (2), Ni (3). By recrystallization from aqueous alcohol compound 2 unexpectedly gives Zn(OOCCH2SC6H4Cl-4)2 ? 2H2O (4). Unlike 2, compound 3 gives crystals [N(CH2CH2OH)3]2Ni2+??[-OOCCH2SC6H4Cl-4]2 (5), which have a structure of metallated ionic liquid. The structure of 5 has been proved by X-ray diffraction analysis. It is the first example of the conversion of a protic ionic liquid into potentially biological active metallated ionic liquid (1???3???5). PMID:23421876

  1. Reaction of pharmacological active tris-(2-hydroxyethyl)ammonium 4-chlorophenylsulfanylacetate with ZnCl2 or NiCl2: first conversion of a protic ionic liquid into metallated ionic liquid

    PubMed Central

    2013-01-01

    The reaction of pharmacological active protic ionic liquid tris-(2-hydroxyethyl)ammonium 4-chlorophenylsulfanylacetate H+N(CH2CH2OH)3 ? (-OOCCH2SC6H4Cl-4) (1) with zinc or nickel chloride in a ratio of 2:1 affords stable at room temperature powder-like adducts [H+N(CH2CH2OH)3]2 ? [M(OOCCH2SC6H4Cl-4)2Cl2]2-, M = Zn (2), Ni (3). By recrystallization from aqueous alcohol compound 2 unexpectedly gives Zn(OOCCH2SC6H4Cl-4)2 ? 2H2O (4). Unlike 2, compound 3 gives crystals [N(CH2CH2OH)3]2Ni2+??[-OOCCH2SC6H4Cl-4]2 (5), which have a structure of metallated ionic liquid. The structure of 5 has been proved by X-ray diffraction analysis. It is the first example of the conversion of a protic ionic liquid into potentially biological active metallated ionic liquid (1???3???5). PMID:23421876

  2. Direct write dispenser printing of a zinc microbattery with an ionic liquid gel electrolyte

    NASA Astrophysics Data System (ADS)

    Ho, C. C.; Evans, J. W.; Wright, P. K.

    2010-10-01

    The need for energy dense microbatteries with miniature dimensions has prompted the development of unconventional materials, cell geometries, and processing methods. This work will highlight our materials investigations, deposition methods and the device performance of a printed zinc-manganese dioxide rechargeable microbattery utilizing an ionic liquid gel electrolyte. We have developed a direct write dispenser printing method with the ability to fabricate multilayer structures and precisely deposit and pattern these components onto any substrates. The use of a unique room-temperature ionic liquid swelled into a polymer to form a gel electrolyte with solid-like mechanical strength and liquid-like ion transport properties has enabled the simple fabrication of stacked microbattery structures with the potential to be easily integrated directly onto a microdevice substrate. Initial microbattery tests and cycle behavior are discussed, and after an initial activation of the cathode material, an experimental cell discharge capacity and energy density of 0.98 mA h cm-2 and 1.2 mW h cm-2 were measured, respectively.

  3. Preparation of magnetic ionic liquid/chitosan/graphene oxide composite and application for water treatment.

    PubMed

    Li, Leilei; Luo, Chuannan; Li, Xiangjun; Duan, Huimin; Wang, Xiaojiao

    2014-05-01

    Magnetic chitosan and graphene oxide-ionic liquid (MCGO-IL) composites as biodegradable biosorbents were synthesized by impregnating MCGO with ionic liquid. The characteristic results of FTIR, SEM, and XRD showed that MCGO-IL were successfully prepared with large surface area and good magnetic responsiveness. They were used for the removal of Cr(VI) from simulated wastewater with a fast solid-liquid separation in the presence of external magnetic field. The influence of various analytical parameters on the adsorption of Cr(VI) such as pH, contact time, and initial ion concentration were studied in detail. The adsorption followed a pseudo-second-order kinetics. The equilibrium adsorption was well-described by the Langmuir isotherm mode and the maximum adsorption capacity was 145.35 mg/g. The stronger intermolecular hydrogen bond between MCGO-IL and Cr(VI) and the hydroxyl and amine groups were believed to be the metal ion binding sites. Moreover, the MCGO-IL could be repeatedly used by simple treatment without obvious structure and performance degradation. The obtained results indicated that the impregnation of the room temperature IL significantly enhances the removal efficiency of Cr(VI). The MCGO-IL may be suitable materials in heavy metal ion pollution cleanup if they are synthesized in large scale and at low price in near future. PMID:24560948

  4. Silver halide fiber-based evanescent-wave liquid droplet sensing with thermoelectrically cooled room temperature mid-infrared quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Chen, Jian Z.; Liu, Zhijun; Gmachl, Claire F.; Sivco, Deborah L.

    2005-11-01

    Quantum cascade lasers coupled directly to unclad silver halide fibers were used to assemble mid-infrared fiber-optics evanescent-wave sensors suitable to measure the chemical composition of simple liquid droplets. Quantum cascade lasers can be designed to emit across a wide range of mid-infrared wavelengths by tailoring the quantum-well structure, and the wavelength can be fine tuned by a thermoelectric cooler. Here, laser wavelengths were chosen which offer the largest absorption contrast between two constituents of a droplet. The laser was coupled to an unclad silver halide fiber, which penetrates through the droplet resting on a hydrophobic surface. For the same liquid composition and droplet size, the transmitted intensity is weaker for a droplet on a 1H,1H,2H,2H-perfluoro-octyltrichlorosilane coated glass slide than for one on a hexadecanethiol (HDT) coated Au-covered glass slide because of the high reflectivity of the HDT/Au surface at mid-infrared wavelengths. The absorption coefficients of water, glycerol, α-tocophenol acetate, and squalane were measured by varying the immersion length of the fiber; i.e. the droplet size. A pseudo-Beer-Lambert law fits well with the experimental data. We tested both aqueous liquid mixtures (acetone/water and ethanol/water) and oil-base solutions (n-dodecane/squalane and α-tocophenol acetate/squalane); α-tocophenol acetate and squalane are common ingredients of cosmetics, either as active ingredients or for chemical stabilization. Using a 300μm diameter silver halide fiber with a 25mm immersion length, the detection limits are 1 vol.% for α-tocophenol in squalane and 2 vol.% for acetone in water for laser wavenumbers of 1208 cm -1 and 1363 cm -1, respectively. This work was previously been reported in J. Z. Chen et al. Optics Express 13, 5953 (2005).

  5. Nanostructural organization and anion effects on the temperature dependence of the optical Kerr effect spectra of ionic liquids.

    PubMed

    Xiao, Dong; Rajian, Justin Rajesh; Cady, Amanda; Li, Shengfu; Bartsch, Richard A; Quitevis, Edward L

    2007-05-10

    The intermolecular spectra of three imidazolium ionic liquids were studied as a function of temperature by the use of optical heterodyne-detected Raman-induced Kerr effect spectroscopy. The ionic liquids comprise the 1,3-pentylmethylimidazolium cation ([C(5)mim]+), and the anions, bromide (Br-), hexafluorophosphate (PF(6)-), and bis(trifluoromethanesulfonyl)imide (NTf(2)-). Whereas the optical Kerr effect (OKE) spectrum of [C(5)mim][NTf(2)] is temperature-dependent, the OKE spectra of [C(5)mim]Br and [C(5)mim][PF6] are temperature-independent. These results are surprising in light of the fact that the bulk densities of these room temperature ionic liquids (RTILs) are temperature-dependent. The temperature independence of the OKE spectra and the temperature dependence of the bulk density in [C(5)mim]Br and [C(5)mim][PF(6)] suggest that there are inhomogeneities in the densities of these liquids. The existence of density inhomogeneities is consistent with recent molecular dynamics simulations that show RTILs to be nanostructurally organized with nonpolar regions arising from clustering of the alkyl chains and ionic networks arising from charge ordering of the anions and imidazolium rings of the cations. Differences in the temperature dependences of the OKE spectra are rationalized on the basis of the degree of charge ordering in the polar regions of the RTILs. PMID:17474695

  6. Direct extraction of genomic DNA from maize with aqueous ionic liquid buffer systems for applications in genetically modified organisms analysis.

    PubMed

    Gonzalez García, Eric; Ressmann, Anna K; Gaertner, Peter; Zirbs, Ronald; Mach, Robert L; Krska, Rudolf; Bica, Katharina; Brunner, Kurt

    2014-12-01

    To date, the extraction of genomic DNA is considered a bottleneck in the process of genetically modified organisms (GMOs) detection. Conventional DNA isolation methods are associated with long extraction times and multiple pipetting and centrifugation steps, which makes the entire procedure not only tedious and complicated but also prone to sample cross-contamination. In recent times, ionic liquids have emerged as innovative solvents for biomass processing, due to their outstanding properties for dissolution of biomass and biopolymers. In this study, a novel, easily applicable, and time-efficient method for the direct extraction of genomic DNA from biomass based on aqueous-ionic liquid solutions was developed. The straightforward protocol relies on extraction of maize in a 10 % solution of ionic liquids in aqueous phosphate buffer for 5 min at room temperature, followed by a denaturation step at 95 °C for 10 min and a simple filtration to remove residual biopolymers. A set of 22 ionic liquids was tested in a buffer system and 1-ethyl-3-methylimidazolium dimethylphosphate, as well as the environmentally benign choline formate, were identified as ideal candidates. With this strategy, the quality of the genomic DNA extracted was significantly improved and the extraction protocol was notably simplified compared with a well-established method. PMID:25381609

  7. Ionic liquid of [Bmim]{sup +}Cl{sup -} for the preparation of hierarchical nanostructured rutile titania

    SciTech Connect

    Yu Ningya Gong Liming; Song Huijuan; Liu Yong; Yin Donghong

    2007-02-15

    The rutile titania with hierarchical nanostructure was conveniently prepared in a room temperature ionic liquid (RTIL) of [Bmim]{sup +}Cl{sup -} system. The obtained materials were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N{sub 2} adsorption-desorption analysis. XRD patterns revealed that only rutile phase was formed in the ionic liquid of [Bmim]{sup +}Cl{sup -}. The SEM and TEM micrographs as well as N{sub 2} adsorption-desorption measurements showed that the nanorods of rutile titania were interaggregated to fabricate a large mesoporous structure and the voids packed in the nanorods formed a small mesostructure. It was proposed that the formation of rutile crystal phase was due to high acidity and high Cl{sup -} content in the special reaction media, and also the combination of ionic liquid-templated effects with so-called reaction limited aggregation resulted in the hierarchical nanostructure. - Graphical abstract: Ionic liquid of [Bmim]{sup +}Cl{sup -} was employed to prepare rutile titania with hierarchical nanostructure, in which the nanorods were interaggregated to fabricate a large mesoporous structure and the voids packed in the nanorods formed a small mesostructure.

  8. Comparative study of bending characteristics of ionic polymer actuators containing ionic liquids for modeling actuation

    NASA Astrophysics Data System (ADS)

    Kikuchi, Kunitomo; Sakamoto, Takumi; Tsuchitani, Shigeki; Asaka, Kinji

    2011-04-01

    Ionic polymer metal composites (IPMCs) that can operate in air have recently been developed by incorporating an ionic liquid in ionic polymers. To understand transduction in these composites, it is important to determine the role of the ionic liquid in the ionic polymer (Nafion), to identify the counter cation, and to investigate the interaction of IPMCs with water vapor in the air. We used Fourier-transform infrared spectroscopy to analyze three Nafion membranes, which were soaked in mixtures of water and an ionic liquid (1-ethyl-3-methyl-imidazolium tetrafluoroborate (EMIBF4), 1-buthyl-3-methyl-imidazolium tetrafluoroborate (BMIBF4), and 1-buthyl-3-methyl-imidazolium hexafluorophosphate (BMIPF6)). The results demonstrate that only cations (EMI+ and BMI+) in the ionic liquids are taken into the Nafion membranes as counter ions and that the water content of the membranes in air is less than 4% that of Nafion swollen with water. Based on the experimental results, a transduction model is proposed for an IPMC with an ionic liquid. In this model, bending is caused by local swelling due to the volume effect of the bulky counter cations. This model can explain 30-50% of the experimentally observed bending curvature.

  9. Study of effective carrier lifetime and ideality factor of BPW 21 and BPW 34B photodiodes from above room temperature to liquid nitrogen temperature

    NASA Astrophysics Data System (ADS)

    Dalapati, P.; Manik, N. B.; Basu, A. N.

    2015-01-01

    In the present work we have studied the temperature dependence of two most important characteristics of the photodiodes (BPW 21and BPW 34B), namely, the ideality factor and the carrier lifetime; both of which are found to change significantly at low temperature. The effective carrier lifetime measured by the Open Circuit Voltage Decay method (OCVD) shows a gradual increase in value from 350 K to about 250 K then sharply decreases by about thirty percent of its highest value at liquid nitrogen temperature, the trend being similar for both the devices. The dark forward current-voltage characteristics over the same temperature range yield the value of ideality factor which increases nearly by a factor of three for both the photodiodes at the liquid nitrogen temperature. The nature of variation of both the parameters has been qualitatively accounted for in terms of the recent tunneling models. The data generated for the first time for the devices and their broad theoretical understanding will help to improve design and application of the photodiodes, particularly at low temperature.

  10. Soft ionization of thermally evaporated hypergolic ionic liquid aerosols

    SciTech Connect

    University of California; ERC, Incorporated, Edwards Air Force Base; Air Force Research Laboratory, Edwards Air Force Base; National Synchrotron Radiation Research Center; Institute of Chemistry, Hebrew University; Koh, Christine J.; Liu, Chen-Lin; Harmon, Christopher W.; Strasser, Daniel; Golan, Amir; Kostko, Oleg; Chambreau, Steven D.; Vaghjiani, Ghanshyam L.; Leone, Stephen R.

    2011-07-19

    Isolated ion pairs of a conventional ionic liquid, 1-Ethyl-3-Methyl-Imidazolium Bis(trifluoromethylsulfonyl)imide ([Emim+][Tf2N?]), and a reactive hypergolic ionic liquid, 1-Butyl-3-Methyl-Imidazolium Dicyanamide ([Bmim+][Dca?]), are generated by vaporizing ionic liquid submicron aerosol particles for the first time; the vaporized species are investigated by dissociative ionization with tunable vacuum ultraviolet (VUV) light, exhibiting clear intact cations, Emim+ and Bmim+, presumably originating from intact ion pairs. Mass spectra of ion pair vapor from an effusive source of the hypergolic ionic liquid show substantial reactive decomposition due to the internal energy of the molecules emanating from the source. Photoionization efficiency curves in the near threshold ionization region of isolated ion pairs of [Emim+][Tf2N?]ionic liquid vapor are compared for an aerosol source and an effusive source, revealing changes in the appearance energy due to the amount of internal energy in the ion pairs. The aerosol source has a shift to higher threshold energy (~;;0.3 eV), attributed to reduced internal energy of the isolated ion pairs. The method of ionic liquid submicron aerosol particle vaporization, for reactive ionic liquids such as hypergolic species, is a convenient, thermally ?cooler? source of isolated intact ion pairs in the gas phase compared to effusive sources.

  11. Soft ionization of thermally evaporated hypergolic ionic liquid aerosols

    SciTech Connect

    University of California; ERC, Incorporated, Edwards Air Force Base; Air Force Research Laboratory, Edwards Air Force Base; National Synchrotron Radiation Research Center; Koh, Christine J.; Liu, Chen-Lin; Harmon, Christopher W.; Strasser, Daniel; Golan, Amir; Kostko, Oleg; Chambreau, Steven D.; L.Vaghjiani, Ghanshyam; Leone, Stephen R.

    2012-03-16

    Isolated ion pairs of a conventional ionic liquid, 1-Ethyl-3-Methyl-Imidazolium Bis(trifluoromethylsulfonyl)imide ([Emim+][Tf2N?]), and a reactive hypergolic ionic liquid, 1- Butyl-3-Methyl-Imidazolium Dicyanamide ([Bmim+][Dca?]), are generated by vaporizing ionic liquid submicron aerosol particles for the first time; the vaporized species are investigated by dissociative ionization with tunable vacuum ultraviolet (VUV) light, exhibiting clear intact cations, Emim+ and Bmim+, presumably originating from intact ion pairs. Mass spectra of ion pair vapor from an effusive source of the hypergolic ionic liquid show substantial reactive decomposition due to the internal energy of the molecules emanating from the source. Photoionization efficiency curves in the near threshold ionization region of isolated ion pairs of [Emim+][Tf2N?] ionic liquid vapor are compared for an aerosol source and an effusive source, revealing changes in the appearance energy due to the amount of internal energy in the ion pairs. The aerosol source has a shift to higher threshold energy (~;;0.3 eV), attributed to reduced internal energy of the isolated ion pairs. The method of ionic liquid submicron aerosol particle vaporization, for reactive ionic liquids such as hypergolic species, is a convenient, thermally ?cooler? source of isolated intact ion pairs in the gas phase compared to effusive sources.

  12. Adsorption Kinetics at Silica Gel/Ionic Liquid Solution Interface.

    PubMed

    Flieger, Jolanta; Tatarczak-Michalewska, Ma?gorzata; Groszek, Anna; Blicharska, Eliza; Kocjan, Ryszard

    2015-01-01

    A series of imidazolium and pyridinium ionic liquids with different anions (Cl(-), Br(-), BF?(-), PF?(-)) has been evaluated for their adsorption activity on silica gel. Quantification of the ionic liquids has been performed by the use of RP-HPLC with organic-aqueous eluents containing an acidic buffer and a chaotropic salt. Pseudo-second order kinetic models were applied to the experimental data in order to investigate the kinetics of the adsorption process. The experimental data showed good fitting with this model, confirmed by considerably high correlation coefficients. The adsorption kinetic parameters were determined and analyzed. The relative error between the calculated and experimental amount of ionic liquid adsorbed at equilibrium was within 7%. The effect of various factors such as initial ionic liquid concentration, temperature, kind of solvent, kind of ionic liquid anion and cation on adsorption efficiency were all examined in a lab-scale study. Consequently, silica gel showed better adsorptive characteristics for imidazolium-based ionic liquids with chaotropic anions from aqueous solutions in comparison to pyridinium ionic liquids. The adsorption was found to decrease with the addition of organic solvents (methanol, acetonitrile) but it was not sensitive to the change of temperature in the range of 5-40 C. PMID:26690392

  13. Chelating ionic liquids for reversible zinc electrochemistry.

    PubMed

    Kar, Mega; Winther-Jensen, Bjorn; Forsyth, Maria; MacFarlane, Douglas R

    2013-05-21

    Advanced, high energy-density, metal-air rechargeable batteries, such as zinc-air, are of intense international interest due to their important role in energy storage applications such as electric and hybrid vehicles, and to their ability to deal with the intermittency of renewable energy sources such as solar and wind. Ionic liquids offer a number of ideal thermal and physical properties as potential electrolytes in such large-scale energy storage applications. We describe here the synthesis and characterisation of a family of novel "chelating" ILs designed to chelate and solubilize the zinc ions to create electrolytes for this type of battery. These are based on quaternary alkoxy alkyl ammonium cations of varying oligo-ether side chains and anions such as p-toluene sulfonate, bis(trifluoromethylsulfonyl)amide and dicyanoamides. This work shows that increasing the ether chain length in the cation from two to four oxygens can increase the ionic conductivity and reduce the melting point from 67 C to 15 C for the tosylate system. Changing the anion also plays a significant role in the nature of the zinc deposition electrochemistry. We show that zinc can be reversibly deposited from [N(222(20201))][NTf2] and [N(222(202020201))][NTf2] beginning at -1.4 V and -1.7 V vs. SHE, respectively, but not in the case of tosylate based ILs. This indicates that the [NTf2] is a weaker coordinating anion with the zinc cation, compared to the tosylate anion, allowing the coordination of the ether chain to dominate the behavior of the deposition and stripping of zinc ions. PMID:23558696

  14. How does lithium oxalyldifluoroborate enable the compatibility of ionic liquids and carbon-based capacitors?

    NASA Astrophysics Data System (ADS)

    Chen, Renjie; Chen, Yan; Xu, Bin; Zhang, Rong; He, Zhouying; Wu, Feng; Li, Li

    2015-02-01

    Lithium oxalyldifluoroborate (LiODFB) has several unique characteristics, such as high ionic conductivity over a wide temperature range and the ability to form and stabilize solid electrolyte interface films on graphite surfaces. A series of binary, room-temperature, molten electrolytes composed of LiODFB and organic compounds with acylamino groups (acetamide, oxazolidinone or OZO) have been synthesized. Fourier-transform infrared (FT-IR) spectroscopy indicates that Cdbnd O and N-H functional groups undergo blue or red shifts upon addition of LiODFB. The electrolytes have excellent thermal stabilities and electrochemical characteristics that allow them to be promising electrolytes for electrochemical double layer capacitors (EDLCs). Here, we examine 1:5 molar ratio LiODFB and acetamide/OZO ionic liquid (IL) electrolytes in EDLCs. IL compatibility with two types of carbon-based electrodes is investigated theoretically and experimentally. We simulate possible structures and ion diameters for the ILs, which must be compatible with pore sizes of the carbon electrodes. Mesoporous activated carbon AC2, with a pore size similar to the ionic diameter of LiODFB-acetamide, has a specific capacitance of 154.2 Fg-1 at 20 m Ag-1. Additionally, typical capacitive and reversibility behaviors can be seen in the charge-discharge curves over 0-2 V. Finally, the EDLCs exhibit good charging/discharging performances.

  15. Poly(dimethylsiloxane)-supported ionogels with a high ionic liquid loading.

    PubMed

    Horowitz, Ariel I; Panzer, Matthew J

    2014-09-01

    The immiscibility of poly(dimethylsiloxane) (PDMS) and ionic liquids (ILs) was overcome to create PDMS-supported IL gels (ionogels) with IL loadings of up to 80% by mass through a simple sol-gel reaction at room temperature. By stirring a mixture of a functionalized PDMS oligomer, formic acid, and an IL (or lithium-in-IL solution), a resin was formed that could be cast to create a freestanding, flexible ionogel. PDMS-supported ionogels exhibited favorable ionic conductivity (ca. 3?mS?cm(-1)) and excellent mechanical behavior (elastic modulus: ca. 60?kPa; fatigue life: >5000 cycles; mechanically stable at temperatures up to 200?C). The activation energy of ionic conductivity was shown to be nearly identical for the ionogel and the neat IL, in contrast to ionogel systems wherein the scaffold material is miscible with the IL. This similarity indicates that IL/scaffold chemical interactions are key to the understanding of ionogel electrical performance, especially at elevated temperatures. PMID:25044479

  16. Temperature dependence of the electrical conductivity of imidazolium ionic liquids.

    PubMed

    Leys, Jan; Wübbenhorst, Michael; Preethy Menon, Chirukandath; Rajesh, Ravindran; Thoen, Jan; Glorieux, Christ; Nockemann, Peter; Thijs, Ben; Binnemans, Koen; Longuemart, Stéphane

    2008-02-14

    The electrical conductivities of 1-alkyl-3-methylimidazolium tetrafluoroborate ionic liquids and of 1-hexyl-3-methylimidazolium ionic liquids with different anions were determined in the temperature range between 123 and 393 K on the basis of dielectric measurements in the frequency range from 1 to 10(7) Hz. Most of the ionic liquids form a glass and the conductivity values obey the Vogel-Fulcher-Tammann equation. The glass transition temperatures are increasing with increasing length of the alkyl chain. The fragility is weakly dependent on the alkyl chain length but is highly sensitive to the structure of the anion. PMID:18282058

  17. Temperature dependence of the electrical conductivity of imidazolium ionic liquids

    NASA Astrophysics Data System (ADS)

    Leys, Jan; Wübbenhorst, Michael; Preethy Menon, Chirukandath; Rajesh, Ravindran; Thoen, Jan; Glorieux, Christ; Nockemann, Peter; Thijs, Ben; Binnemans, Koen; Longuemart, Stéphane

    2008-02-01

    The electrical conductivities of 1-alkyl-3-methylimidazolium tetrafluoroborate ionic liquids and of 1-hexyl-3-methylimidazolium ionic liquids with different anions were determined in the temperature range between 123 and 393K on the basis of dielectric measurements in the frequency range from 1to107Hz. Most of the ionic liquids form a glass and the conductivity values obey the Vogel-Fulcher-Tammann equation. The glass transition temperatures are increasing with increasing length of the alkyl chain. The fragility is weakly dependent on the alkyl chain length but is highly sensitive to the structure of the anion.

  18. Thermal boundary conductance of hydrophilic and hydrophobic ionic liquids

    NASA Astrophysics Data System (ADS)

    Oyake, Takafumi; Sakata, Masanori; Yada, Susumu; Shiomi, Junichiro

    2015-03-01

    A solid/liquid interface plays a critical role for understanding mechanisms of biological and physical science. Moreover, carrier density of the surface is dramatically enhanced by electric double layer with ionic liquid, salt in the liquid state. Here, we have measured the thermal boundary conductance (TBC) across an interface of gold thin film and ionic liquid by using time-domain thermoreflectance technique. Following the prior researches, we have identified the TBC of two interfaces. One is gold and hydrophilic ionic liquid, N,N-Diethyl-N-methyl-N-(2-methoxyethyl) ammonium tetrafluoroborate (DEME-BF4), which is a hydrophilic ionic liquid, and the other is N,N-Diethyl-N-methyl-N-(2-methoxyethyl) ammonium bis (trifluoromethanesulfonyl) imide (DEME-TFSI), which is a hydrophobic ionic liquid. We found that the TBC between gold and DEME-TFIS (19 MWm-2K-1) is surprisingly lower than the interface between gold and DEME-BF4 (45 MWm-2K-1). With these data, the importance of the wetting angle and ion concentration for the thermal transport at the solid/ionic liquid interface is discussed. Part of this work is financially supported by Japan Society for the Promotion of Science (JSPS) and Japan Science and Technology Agency. The author is financially supported by JSPS Fellowship.

  19. Triphilic Ionic-Liquid Mixtures: Fluorinated and Non-fluorinated Aprotic Ionic-Liquid Mixtures

    PubMed Central

    Hollczki, Oldamur; Macchiagodena, Marina; Weber, Henry; Thomas, Martin; Brehm, Martin; Stark, Annegret; Russina, Olga; Triolo, Alessandro; Kirchner, Barbara

    2015-01-01

    We present here the possibility of forming triphilic mixtures from alkyl- and fluoroalkylimidazolium ionic liquids, thus, macroscopically homogeneous mixtures for which instead of the often observed two domainspolar and nonpolarthree stable microphases are present: polar, lipophilic, and fluorous ones. The fluorinated side chains of the cations indeed self-associate and form domains that are segregated from those of the polar and alkyl domains. To enable miscibility, despite the generally preferred macroscopic separation between fluorous and alkyl moieties, the importance of strong hydrogen bonding is shown. As the long-range structure in the alkyl and fluoroalkyl domains is dependent on the composition of the liquid, we propose that the heterogeneous, triphilic structure can be easily tuned by the molar ratio of the components. We believe that further development may allow the design of switchable, smart liquids that change their properties in a predictable way according to their composition or even their environment. PMID:26305804

  20. Triphilic Ionic-Liquid Mixtures: Fluorinated and Non-fluorinated Aprotic Ionic-Liquid Mixtures.

    PubMed

    Hollczki, Oldamur; Macchiagodena, Marina; Weber, Henry; Thomas, Martin; Brehm, Martin; Stark, Annegret; Russina, Olga; Triolo, Alessandro; Kirchner, Barbara

    2015-10-26

    We present here the possibility of forming triphilic mixtures from alkyl- and fluoroalkylimidazolium ionic liquids, thus, macroscopically homogeneous mixtures for which instead of the often observed two domains-polar and nonpolar-three stable microphases are present: polar, lipophilic, and fluorous ones. The fluorinated side chains of the cations indeed self-associate and form domains that are segregated from those of the polar and alkyl domains. To enable miscibility, despite the generally preferred macroscopic separation between fluorous and alkyl moieties, the importance of strong hydrogen bonding is shown. As the long-range structure in the alkyl and fluoroalkyl domains is dependent on the composition of the liquid, we propose that the heterogeneous, triphilic structure can be easily tuned by the molar ratio of the components. We believe that further development may allow the design of switchable, smart liquids that change their properties in a predictable way according to their composition or even their environment. PMID:26305804