5th Australasian Symposium on Ionic Liquids

Mucosal barriers are a natural defense system for preventing the entry of foreign objects into the body; however, they pose obstacles for effective drug delivery. Coated polymer nanoparticles (NPs) have been shown to possess improved rates of diffusion across mucus compared to their uncoated, or bare, counterparts. Choline carboxylic acid-based ionic liquids (ILs) are highly tunable and show high biocompatibility and mucus modulation properties, making them an ideal choice for the improvement of NP diffusion through mucosal barriers. This study aimed to investigate whether the use of choline-based ILs has a positive effect on the dispersibility of poly(lactic-co-glycolic acid) (PLGA), poly(ethylene glycol) methyl ether-block-poly(lactide-co-glycolide) (PEG-PLGA), and poly(ethylene glycol)-poly(lactic acid) (PEG-PLA) NPs through nasal mucus by using a multiple particle tracking method. The samples, according to the IL used, showed altered rates of diffusion in both aqueous and mucosal environments. The use of CA2HE 1:1 with PEG-PLGA NPs slowed NP diffusion, while the use of the same IL increased diffusion for PEG-PLA. Additionally, UV-vis spectroscopy was used to identify the possible formation of complexes between the mucin polymer and NPs. Circular dichroism (CD) spectroscopy was used to analyze any potential changes in the secondary structure of mucin as a result of the introduction of polymeric NPs. It was demonstrated that the use of an IL can stabilize the interactions between polymer NPs and mucin polymers. Isothermal titration calorimetry was used to obtain quantitative measurement of the binding energies between NPs and mucus and serves to confirm the results obtained from CD spectroscopy. Last, an ex vivo porcine nasal mucosa model was used to explore their use in a nasal delivery context, disclosing a possible connection between the use of zwitterionic transport materials and more effective drug delivery. This research demonstrates the potential of choline carboxylic acid-based ILs to control the transport behavior of polymer NPs for intranasal drug delivery.

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 withmore » 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.« less

Copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reactions are of extensive interest in chemical synthesis. While the use of ionic liquids (ILs) as solvents for synthesis has been widely explored in recent years, the understanding of their influence on the mechanism and reactivity of CuAAC reactions remains poorly understood. Here, we investigate the kinetics of a phenylacetylene-benzylazide and acetylene-benzylazide CuAAC reaction to probe the influence of IL structure, including the role of the base used to promote the reaction and the importance of water content. The use of 'wet' ILs led to remarkable changes in the kinetic profile of the reaction by eliminating the initial induction period. The reaction rate was found to be dependent on the copper(I) source. The effect of an added base was also studied, with the use of a tertiary amine-bearing IL leading to high conversions in under 5 min at ambient temperature. The results of this study highlight the nature and complexity of CuAAC reactions in ILs. As more ILs are getting involved in industrial processes, the data obtained from this study are valuable for better understanding processes that affect the CuAAC reaction in IL media and for creating customized systems for organic synthesis, thus improving the efficiency and sustainability of such processes.

Ionic systems in materials research : new materials and processes based on ionic polymerizations and/or ionic liquids

Ionic liquids (ILs), a class of compounds composed entirely of ions, are prominent candidates for battery electrolytes, as they allow for increased safety due to their negligible vapor pressure, non-flammability and high thermal and electrochemical stability. Another benefit of ILs is their tunable properties, including solvating power, polarity and surface tension. Those could be used to influence the SEI formation as well as modify the overpotential on the electrodes. This effect can be used in different metal-air batteries, where the use of IL-based electrolyte allows for high electrolyte stability combined with the use of a normal gas diffusion electrode. [1] Further advantages that ILs bring, especially in the context of lithium sulphur batteries are their ability to reduce the formation of soluble polysulfides and to reduce dendrite formation. [2] This feature can be also beneficial for other types of lithium metal batteries. The major problem of using ILs as electrolytes - their high viscosity - can be overcome by using mixtures of selected ILs in specific ratios, thus reducing viscosity and increasing performance of the electrolyte. [3] In connection with that, our latest developments on use of ILs as electrolytes for different types of batteries will be presented. We will focus on physicochemical properties of selected ILs, their mixtures and possible additives, designed for specific batteries applications. The compatibility of the particular ILs with battery materials will be also discussed.

Ionic-liquid-enhanced solvent extraction mechanism: A novel concept

Review: 122 refs.

INTRODUCTION The unique properties of ionic liquids (ILs) i.e. high thermal and chemical stability, non-flammability, low vapor pressure, and wider electrochemical window compared to traditional solvents, as well as the prospect that they can be tailored or custom designed for specific requirements make them all the more interesting. In recent years, ILs with organic cations have been suggested for electrolyte applications. Ionic liquids seems to be promising electrolytes in protonic systems as they exhibit good proton conducting properties.The motivation for the presented research was dictated by the growing interest in the field of the use of ionic liquids as electrolytes in metal-hydride batteries (Ni-MH) and other proton batteries (eg. based on the Si anode). The electrolytes based on ionic liquids can reduce the problem of the anode material (eg. AB5 alloy) corrosion in aqueous basic solutions, which may result in the improvement of the operation parameters of the proton batteries.The focus of this study was to check the applicability of ILs as non-aqueous electrolytes through the investigation of hydrogen sorption in Pd limited volume electrode (Pd-LVE) and AB5-LVE. Since protic ILs and their mixtures with other solvents have been recently proposed as electrolytes in metal-hydride batteries, Pd-LVE is a very good model system to carry out the preliminary study of hydrogen electrosorption in ionic liquids in view of the further research with the use of multicomponent alloys. EXPERIMENTAL The electrochemical experiments were conducted in selected, commercially available protic and aprotic ionic liquids (i.a. diethylmethylammonium triflate (DEMA-TFO), ethylammonium nitrate (EAN), 1-ethyl-3-methylimidazolium methanesulfonate (EMIm-MS) under inert gas (Ar) using three-electrode system. Pd-LVE (ca. 0.5 μm thick) or AB5-LVE (ca. 50 μm thick) was a working electrode, Ag wire was a quasi-reference electrode, and Pt or Au spiral was an auxiliary electrode. Pd-LVE were obtained electrochemically from the PdCl2 aqueous solution. AB5 alloy (LaMMNi4.1Al0.3Mn0.4Co0.45) was obtained from VARTA Microbatteries GmbH. To aprotic ionic liquid (EMIm-MS) organic acid of the same anion as in the IL (methanesulfonic acid, HMS) was added as a source of hydrogen and to increase the ionic conductivity of the obtained electrolyte. Cyclic voltammetry (CV), chronoamperometry (CA) and chronopotentiometry (CP) techniques were used to perform the electrochemical measurements. The electrodes were subjected to a hydrogen pretreatment procedure (HPP) and standard hydrogen cyclic voltammetry electrosorption experiment to obtain hydrogen absorption isotherms. RESULTS AND DISCUSSION It was observed, that the reversibility of the hydrogen sorption in Pd is significantly lower in ILs than in aqueous solutions, which may be caused by hindered proton transport due to few reasons. The first one is the high viscosity of IL, the second one is the difference of proton source, and finally the possible interactions of IL ions with the Pd electrode. Multiple hydrogen sorption in ILs (HPP) increases the reversibility of the investigated process. Preliminary HPP performed in aqueous solution of sulfuric acid facilitates further hydrogen sorption only in some cases (i.a. in EAN). Thus, it was found that the rate of hydrogen absorption is controlled rather by surface than the bulk processes. The maximum hydrogen sorption capacity (H/Mmax) obtained for Pd in protic IL (i.e. DEMA-TFO) and aprotic IL with addition of organic acid (EMIm-MS + 0.5 M HMS) is comparable with those obtained in aqueous solutions of acids and bases, reaching the value of ca 0.7. Our preliminary studies of hydrogen sorption in the AB5 alloy in a mixture of an aprotic IL with the organic acid (EMIm-MS + 1 M HMS) revealed that, as in case of Pd-LVE, the electrochemical reversibility of this process is much lower in comparison with the electrosorption measurements performed in concentrated base (Fig.1), which is due to the significant difference in ion conductivity and dynamic viscosity of the tested electrolytes. Fig. 1. Cyclic voltammetry behavior of AB5 electrode in EMIm-MS + 1 M HMS, inset: cyclic voltammetry of AB5 electrode in 6 M KOH; first cycles; 2 mVs-1. CONCLUSIONS Examined protic and aprotic ionic liquids can be effectively used as electrolytes in the hydrogen sorption process as we demonstrated by the exemplary Pd-LVE electrode. The max. H/Pd ratios obtained for DEMA-TFO and nitrate protic ILs are similar (0.6-0.7) and comparable with those measured in aqueous solutions of acids and bases. Hydrogen electrosorption from aprotic ionic liquids (eg. in EMIM-MS) with different concentration of acid gives ability to tune the maximum hydrogen capacity. The max. H/Pd ratios obtained for EMIm-MS (acid concentration ca. 0.5 M) equals to ca. 0.74 (this is the same value that was obtained for this type of electrode from acidic aqueous media). Figure 1

This chapter reviews the roles of ionic liquids (ILs) in pharmaceutical manufacturing processes, including the use of ILs as solvents in the synthesis of drugs or isolation of drug intermediates, the use of ILs in pharmaceutical crystallization, in pharmaceutical separation, for the extraction of drugs from natural products, to deliver drugs, to detect drugs, and even as active pharmaceutical ingredients (APIs). ILs have also been considered as alternatives to organic solvents in the pharmaceutical industry. A large volume of volatile organic solvents (VOCs) is used in the process of drug extraction from natural products, resulting in serious environmental problems and replacement of conventional solvents by ILs might prevent the emission of VOCs. While ILs have been shown to be efficient vehicles in transdermal drug delivery, until recently they were not studied as transdermal drugs themselves because ionized salts normally diffuse poorly through lipid membranes.

Some of the most critical issues facing the nanocomposite community include the need for multi-scale imaging of hierarchical structures, effective methods for controlling nanoparticle chemistry and surface-energy, and efficient processing methods for preparing nanoparticles and nanocomposites. Over the last decade we have employed a number of approaches to address some of these challenges. This paper will review our efforts centered on the use of ionic liquids and fluorescence microscopy to develop tools to enable industry to more quickly bring new nanocomposite-based products to market. Research results focused on polymer nanocomposite based on multiwalled-carbon-nanotube (MWCNT), Montmorillonite (MMT) and nanofibrillated-cellulose (NFC) will be presented.

Although the use of ionic liquids (IL) in polymeric membranes is known to elevate the electrochemical performance for proton exchange membrane-based fuel cells (PEMFC), they suffer from drawbacks such as IL drain and lowering in mechanical properties that lead to deterioration in PEMFC performance. To mitigate these issues, we report, for the first time, the use of polymeric ionic liquid (PIL), namely, poly(diallyl dimethyl ammonium trifluoride methane sulphonate) (P[DADMA][TFMS]) to be blended with polybenzimidazole (PBI-I) as a membrane material for PEMFC. PBI-I and (P[DADMA][TFMS]) were chosen because they form miscible blends and are suitable for acid doping as a matrix, which can eventually be used as proton conductor. The structure, miscibility and inter-polymer interactions were studied by infrared (IR) spectroscopy and differential scanning calorimetry (DSC). The increase in proton conduction in comparison to the PBI membranes was observed due to the presence of ionic groups of PILs in blend membranes. With the increase in PIL content, the proton conductivity of the composite membranes gradually increased from 0.04 S cm−1 for PBI to 0.07 S cm−1 for the blend membrane at 150 °C. The MEAs were fabricated with PBI-I, PBI-PIL15, PBI-PIL25 and PBI-PIL35. Corresponding single cells were successfully tested at temperatures of 160 °C. The maximum power density and current density obtained were 515 mW cm−2 and 1632 mA cm−2, respectively, for PBI-PIL25-based MEA.

Editorial: Australian Chemistry under the Spotlight

Asphaltene aggregation is a two-step process concerning phase separation and asphaltene particle growth which provoke crude oil destabilization and significant problems during the production, transport, and refining of heavy and extra heavy crude oils. A recent and innovative approach to overcome this problem is the use of ionic liquids (ILs) as inhibitors or stabilizers of asphaltene aggregation. Since the information concerning the properties of the studied ILs is scarce, we characterized some of their electronic properties and critical aggregation concentration (CAC) by quantum chemistry and spectrofluorometry, respectively. We found that the presence of a complex anion such as [AlCl4]−, [BF4]−, and [PF6]− incremented the HOMO−LUMO gap (ΔH−L), electronegativity (χ), absolute hardness (η), and dipole moment (μ) when compared to [Br]−-containing ILs. Moreover, the ILs’ CAC values showed a linear correlation with the dipole moment. Afterward, we studied the effect of various commercial ILs on the aggregation point (AP) of a heavy crude oil (HCO) due to the increment of (a) its concentration in toluene solutions or (b) the n-heptane volume by means of fluorescence spectroscopy. We have found that the aggregation of HCO occurs at larger crude oil concentration or n-heptane volume in the presence of some ILs. Here, ILs set a polar microenvironment around HCO asphaltenes, which stabilized them against further aggregation and precipitation. The better performance of ILs as inhibitors or stabilizers of asphaltene aggregation was found with those comporting a complex anion, a pyridinium ring, or a shorter alkyl substitution on the cation. Such ILs present the higher values of the calculated electronic properties.

This study describes the potential conversion of dried microalgae. Chlorella vulgaris (C. vulgaris) into fatty acid methyl ester (FAME) using the direct transesterification (DT) method and using ionic liquids (ILs) as a catalyst. In this work, the performance of monocationic IL, namely 1-butyl-1-methylpyrrolidinium bromide (IL 1), and dicationic IL, namely 1,4-bis(1-methylpyrrolidinium-1-yl) butane dibromide (IL 2), as catalysts was compared for DT of C. vulgaris under microwave irradiation. The results revealed that IL 2 showed a better performance in catalyzing the DT reaction by producing 87.9 mg/g% of FAME, while the use of IL 1 led to 74.3 mg/g% of FAME under optimum conditions. The kinetic study for direct transesterification of C. vulgaris showed that the reaction followed a first order kinetic reaction where the activation energies were calculated to be 22.2499 kJ mol−1 and 22.0413 kJ mol−1 for IL 1 and IL 2, respectively.

Ionic liquids as stable solvents for ionic polymer transducers