Journal of Ionic Liquids最新文献

Understanding the molecular interaction of 1-butyl-3-methylimidazolium octyl sulfate i.e., [Bmim][OcOSO₃] in water and in aqueous NaCl solution is important for fabricating the new process. As it is already known that ionic liquids along with inorganic salt NaCl have significant potential in the tribology of lubricants and salting-out media for the separation of nicotine. It is known that ionic liquids exhibit characteristic behavior at solid−liquid interfaces. Although it is believed that the structure of ionic liquids at the interface contributes to the tribological properties in the region of boundary-mixed lubrication, this contribution has not been clarified yet. Thus, we study the molecular interaction of the ionic liquid in aqueous and ionic liquid in aqueous NaCl solutions through the thermodynamic approach. We have measured density as an important parameter for 1-butyl-3-methylimidazolium octyl sulfate i.e., [Bmim][OcOSO₃] in water and in aqueous NaCl solution within the concentration range of 0.04-0.12 mol/kg at different temperatures i.e. 293.15, 298.15, 303.15, 308.15, and 313.15 K and atmospheric pressure by using a densitometer (DSA5000M Anton Paar). The density ($\rho$) data were employed to measure some derived parameters such as apparent molar volume of solute ($V_{\varphi }$), limiting apparent molar volume of solute ($V_{\varphi }^0$), thermal expansion coefficient ($\alpha$), apparent molar expansivity of solute at finite concentration $\left(E_{\varphi }\right)$ and at infinite concentration $\left(E_{\varphi }^0\right)$ and transfer volume $\left({\Delta }_{tr}{V}_{\varphi }^0\right)$. Results have been discussed in terms of all the possible molecular interactions in systems.

The increasing need of portable electrical resources requires to develop post-Li batteries, in which redox reactions are then based on the different alkali or earth alkaline ions. Keeping in mind the specific advantages of electrolytes based on ionic liquid (electrochemical properties, safety, stability …), this paper focuses on the specific properties of those obtained by mixing alkali or earth alkaline salts (Li⁺, Na⁺, K⁺, Cs⁺ and Mg²⁺) in a prototypical ionic liquid, the 1-butyl-3-methyl imidazolium bis(trifluoromethyl sulfonyl) imide (BMImTFSI). Transport properties of these electrolytes are deciphered from viscosity, ionic conductivity and individual self-diffusion coefficients. At room temperature, change of electrolyte composition (nature of ion, concentration) induces some large variations of these transport properties. However, if these measurements are scaled towards glass transition temperatures, master curves are obtained with only slight differences between monovalent alkali and divalent earth alkaline ions. Further information is obtained from the Walden approach and evidences that these electrolytes are 'good ionic conductors'. These results are confirmed from self-diffusion coefficients which also allows to retrieve contributions of each species to ionic transport and then dissociation ratio inside these mixtures. Slight differences between alkali and earth alkali ions may be related to solvation mechanisms, as proposed from infrared spectroscopy measurements.

This paper describes the synthesis of a new ionic liquid (IL) monomer of 5-substituted cyclooctene 1,2,3-triazolium iodides salt via click chemistry, and an anion exchange reaction with two different counteranions: bis(trifluoromethylsulfonyl)imide [N(SO₂CF₃)₂]⁻(NTf₂⁻), and hexafluorophosphate ([PF₆]⁻). The structural properties of all monomers were determined by MALDI-TOF-MS, (¹H; ¹³C; ¹⁹F;)NMR spectroscopy. 1,2,3-triazolium-based poly(ionic liquid)s (TPILs) with the pendant triazolium moieties were also synthesized by Ring-Opening Metathesis Polymerization (ROMP) using Grubbs second generation (Grubbs II) ruthenium as a catalyst with good control during the polymerization process and gave viscous solutions. The Synthesis of the polymers (TPILs) was confirmed by ¹HNMR spectroscopy. The thermal properties were characterized by thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The thermal stability of monomers was found to be high (∼286°C). Furthermore, monomers salts with [NTf₂⁻] have low melting points below 100°C (25-99°C), and their TPILs are viscous liquids at room temperature, with a low glass transition temperature (T_g = -23°C). This result suggests that the 5-substituted cyclooctene 1,2,3-triazolium ionic liquid monomer offers high chain flexibility to the resulting polymers (TPILs). Hence this new class of IL monomer and TPILs may be potentially useful in electrolyte membrane applications.

A broad set of bis-imidazolium salts with long tails and short spacers (LTSS BIS) with odd and even number of carbons was synthesized and characterized with a number of experimental and computational methods, such as 1H and 13C NMR (2D techniques included), optical and electron microscopy, water content determinations, solubility in water assessments, melting points measurements, geometry and thermochemistry evaluation for model dications in PM6. Theoretically substantiated improvements for alkylimidazoles and bis-imidazolium dihalides synthesis have been proposed and experimentally verified. Good yields of LTSS BIS pure enough for physicochemical studies can be achieved in a fast and efficient manner, and factors essential for getting good results have been unveiled. The majority of LTSS BIS are prone to absorb water and retain it under usual conditions, but easily lose at heating. Large variety in crystal forms and thermal behavior of LTSS BIS subfamilies were found, depending mainly from spacer and anion. High thermal stability (more than 200°C) is typical for all LTSS BIS under study, but only a small part may be considered as a true ionic liquid. Fully stretched conformations were supposed for all alkyl fragments (tails and spacers) in solution, in accordance with experimental and computational results. Rotation around ordinary bonds is restricted only in 1,3-di(imidazolium-1-yl)-2-hydroxypropane dication, leading to unique four sorts of protons in three sp³-carbon chain. Due to specific structural features, bis-imidazolium salts cannot be represented as rod-like molecules. The concept of three principal structural motifs for LTSS BIS (U-shape, V-shape, and Z-shape) is proposed.

Hydrazine and its derivatives have been used as standard propellants for spacecraft propulsion systems since the 1960s, despite being highly toxic and carcinogenic. The propellant synthesis community has constantly been looking for green alternatives for the same. Hypergolic ionic liquids (HILs) with several attractive properties, such as high energy content, high bulk density, low vapor pressure, and low toxicity, have been proposed as an alternative to hydrazine and its derivatives. In the present study, the theoretical performance of sixty-eight HILs was studied at a combustion chamber pressure of 3 MPa and a nozzle expansion ratio of 40. The specific impulse and density specific impulse of the HILs were calculated with white fuming nitric acid (WFNA), inhibited red fuming nitric acid (IRFNA), and nitrogen tetroxide (NTO) as oxidizers. The specific impulse of 2,2-dimethyltriazanium nitrate (HIL-1) was found to be 23 s higher than monomethylhydrazine (MMH), whereas its density-specific impulse was found to be 123 g-s/cm³ higher than MMH. The gains in the specific impulse and density specific impulse coupled with other desirable “green” properties for several HILs are expected to establish them as potential replacements for hydrazine and its derivatives.

We report on a comparative study of three novel non-halogenated surface-active ionic liquids (SAILs), which contain a surface-active anion, 2-ethylhexyl sulfate ([EHS]⁻), and phosphonium or imidazolium cations: tetrabutylphosphonium ([P_4,4,4,4]⁺), trihexyl(tetradecyl)phosphonium ([P_6,6,6,14]⁺), and 1-methyl-3-hexylimidazolium ([C₆C₁Im]⁺). Thermal and electrochemical properties i.e., ionic conductivities at different temperatures and electrochemical potential windows of these SAILs were thoroughly studied. SAIL's electrochemical performance as electrolytes was also examined in a multi-walled carbon nanotubes (MWCNT)-based supercapacitor over a wide range of temperatures from 253 to 373 K. We observed that the electrode material in the supercapacitor cell with [C₆C₁Im][EHS] as an electrolyte has a higher specific capacitance (C_elec in F g⁻¹), a higher electric energy density (E in W h kg⁻¹), and a higher electric power density (P in kW kg⁻¹) as compared to the other studied SAILs, [P_4,4,4,4][EHS], [P_6,6,6,14][EHS] and [N_8,8,8,8][EHS] (from our preceding study) in a temperature range from 253 to 373 K: At the scan rate of 2 mV s⁻¹ a supercapacitor cell with a MWCNT-based electrode and [C₆C₁Im][EHS], [P_4,4,4,4][EHS] and [P_6,6,6,14][EHS] as electrolytes has the specific capacitance, C_elec = 148, 90 and 47 F g⁻¹ and the energy density, E = 82, 50 and 26 W h kg⁻¹, respectively, when measured at 298 K. For the named three SAILs at the scan rate of 2 mV s⁻¹, a two- to three-fold increase in the specific capacitance and the energy density values was measured at 373 K: C_elec = 290, 198 and 114 F g⁻¹ and E = 161, 110 and 63 Wh kg⁻¹, respectively. The solution resistance (R_s), charge transfer resistance (R_ct) and equivalent series resistance (ESR) all decreased two- to three-fold with an increase in temperature from 298 to 373 K. With the high specific capacitance and enhanced energy and power density and wider electrochemical potential window as compared to the molecular organic and aqueous electrolytes, these SAILs can be used for high-temperature electrochemical applications, such as high power and energy storage devices. In particular, up to now, [C₆C₁Im][EHS] and [P_4,4,4,4][EHS] are the most appropriate candidates for such applications.

Ionic Liquids commonly being referred to as designer solvents for the reason that they are accessible to have tailor-made properties by careful manipulation of both cation and anion, yet this approach still takes time and is also not cost-effective. Therefore, the use of ILs in the presence of appropriate additives is a typical way to circumvent the iterative synthesis and characterization process. Lately, Ionic Liquids are drawing massive attention in the field of research for their unique physicochemical properties. In addition to this, their self-organizing and micellization behaviour in aqueous as well as in the presence of different additives are quite useful in a variety of applications and they are economical as well. This review covers the various studies done by the researchers regarding the physicochemical properties of imidazolium based ILs in aqueous and in presence of different additives and also evaluated the various other interactions taking place between the ionic liquids and the additives which are leading their use in a variety of applications.