Ionic liquids as lubricants for the aluminium-steel system

Lubricant technology must keep pace with the ever increasing demands to reduce energy use and increase service intervals. Ionic liquids were evaluated as lubricants for aluminium in the neat state and as additives in base oils. The ionic liquids formed protective layers that reduced friction and wear

Characterization of decamethylferrocene and ferrocene in ionic liquids : Argon and vacuum effect on their electrochemical propertiesce

The electrochemistry of decamethylferrocene (DmFc) has been studied in organic solvent systems and proven to be a superior internal reference redox standard to ferrocene (Fc). However, the electrochemical information on this redox couple in ionic liquids is still limited. Therefore, the voltammetric and amperometric behaviour of DmFc was investigated under argon and vacuum conditions in six different ionic liquids and compared to that of Fc under the same experimental conditions. Consequently, the concentration, the heterogeneous electron-transfer rate constant (k0), volatility, and diffusion coefficients (D) of Fc and Fc+, as well as the solubility, k 0, and D values for DmFc and DmFc+ were determined under argon and vacuum conditions by fitting the experimental chronoamperometric and voltammetric data with numerical and digital simulations. The rate of mass transport of ferrocene and decamethylferrocene was observed to decreases between 6-37% by changing the working atmosphere from argon to vacuum. The D Fc/DFc+ ratios are in the range 1.31-2.01 in the different ILs. Importantly, the DDmFc/DDmFc+ ratio is ≈ 1 in 1-methyl-3-butylimidazolium bis(trifluoromethylsulfonyl)amide, 1-methyl-1-butylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate, and 1-methyl-3-ethylimidazolium tris(pentafluoroethyl)trifluorophosphate. The experimental mid-point potential and half-wave potential of Fc0/+ vs. DmFc0/+, as well as the formal potential obtained after correction for inequality in the respective diffusion coefficients of both redox processes are presented. Even though DmFc is not freely soluble in the different ILs, the results presented in this work suggest that the DmFc0/+ redox process is less dependent than Fc on the IL nature. This is a very relevant finding for the application of this transition-metal sandwich complex as an internal reference redox system in IL solutions. © 2014 Elsevier Ltd.

What happens during natural protein fibre dissolution in ionic liquids

Here, we monitor the dissolution of several natural protein fibres such as wool, human hair and silk, in various ionic liquids (ILs). The dissolution of protein-based materials using ILs is an emerging area exploring the production of new materials from waste products. Wool is a keratin fibre, which is extensively used in the textiles industry and as a result has considerable amounts of waste produced each year. Wool, along with human hair, has a unique morphology whereby the outer layer, the cuticle, is heavily cross linked with disulphide bonds, whereas silk does not have this outer layer. Here we show how ILs dissolve natural protein fibres and how the mechanism of dissolution is directly related to the structure and morphology of the wool fibre. © 2014 by the authors; licensee MDPI, Basel, Switzerland.

Insights into the reversible oxygen reduction reaction in a series of phosphonium-based ionic liquids

New findings supporting the stability of the superoxide ion, O2˙(-), in the presence of the phosphonium cation, [P6,6,6,14](+), are presented. Extended electrochemical investigations of a series of neat phosphonium-based ILs with different anions, including chloride, bis(trifluoromethylsulfonyl)imide and dicyanamide, demonstrate the chemical reversibility of the oxygen reduction process. Quantum chemistry calculations show a short intermolecular distance (r = 3.128 Å) between the superoxide ion and the phosphonium cation. NMR experiments have been performed to assess the degree of long term degradation of [P6,6,6,14](+), in the presence of superoxide and peroxide species, showing no chemically distinct degradation products of importance in reversible air cathodes.

Recycling textiles : The use of ionic liquids in the separation of cotton polyester blends

Textiles are commonly made from intimate blends of polyester and cotton, which makes recycling very difficult. We report for the first time the use of ionic liquid in the separation of polyester cotton blends. By selective dissolution of the cotton component, the polyester component can be separated and recovered in high yield. This finding presents an environmentally benign approach to recycling textile waste. © 2014 The Royal Society of Chemistry.

Ionic liquids for energy, materials, and medicine.

As highlighted by the recent ChemComm web themed issue on ionic liquids, this field continues to develop beyond the concept of interesting new solvents for application in the greening of the chemical industry. Here some current research trends in the field will be discussed which show that ionic liquids research is still aimed squarely at solving major societal issues by taking advantage of new fundamental understanding of the nature of these salts in their low temperature liquid state. This article discusses current research trends in applications of ionic liquids to energy, materials, and medicines to provide some insight into the directions, motivations, challenges, and successes being achieved with ionic liquids today.

Amyloid peptide self assembly in protic ionic liquids

Overall, this thesis presents the novel approach of using carefully selected PILs to both control amyloid fibril formation and inhibit/dissolve Aβ fibrils through induced helical transitions. These results provide insights into future PIL-mediated protein studies and the potential application of PILs in AD pathogenesis.

Electrochemical treatment of AA5083 aluminium alloy in ionic liquids

 Dr Huang was one of the first people to explore the possibility of reducing corrosion on aluminium alloys by electrochemical treatments in ionic liquids. Her study showed that the corrosion rates of aluminium alloys were indeed reduced after various electrochemical treatments in the target ionic liquids.

Water-soluble complexes of an acrylamide copolymer and ionic liquids for inhibiting shale hydration

Here, we report water-soluble complexes of an acrylamide copolymer and ionic liquids for inhibiting shale hydration. The copolymer, denoted as PAAT, was synthesised via copolymerisation of acrylamide (AM), acrylic acid (AA) and N,N-diallyl-4-methylbenzenesulfonamide (TCDAP), and the ionic liquids used were 3-methyl imidazoliumcation-based tetrafluoroborates. X-ray diffraction showed that compared with commonly used KCl, the water-soluble complex of PAAT with 2 wt% ionic liquid 1-methyl-3-H-imidazolium tetrafluoroborate (HmimBF4) could remarkably reduce the d-spacing of sodium montmorillonite in water from 19.24 to 13.16 Å and effectively inhibit clay swelling. It was also found that the PAAT-HmimBF4 complex with 2 wt% HmimBF4 could retain 75% of the shale indentation hardness and increase the anti-swelling ratio to 85%. 13C NMR revealed that there existed interactions between PAAT and HmimBF4. Moreover, the thermal stability of the PAAT-HmimBF4 complex is superior to PAAT, suggesting that this water-soluble complex can be used to inhibit clay and shale hydration in high-temperature oil and gas wells.

Water-soluble complexes of hydrophobically modified polymer and surface active imidazolium-based ionic liquids for enhancing oil recovery

The current study introduces the water-soluble complexes containing hydrophobically associating copolymer and a series of surface activity imidazolium-based ionic liquids (CnmimBr, n=6, 8, 10, 12, 14 and 16). The polymer, denoted as PAAD, was prepared with acrylamide (AM), acrylic acid (AA) and N,N-diallyl-2-dodecylbenzenesulfonamide (DBDAP). And the hydrophobic associative behavior of PAAD was studied by a combination of the pyrene fluorescence probe and viscosimetry. Incorporation of CnmimBr (n=10, 12, 14 and 16) in PAAD leaded to the white thick gel, while the pellucid solutions were obtained in complexes of PAAD and CnmimBr (n=6 and 8); addition of C6mimBr around critical micelle concentration resulted in a large decrease in viscosity of solution. Therefore, we particularly investigated the performance of PAAD/C8mimBr complex. The interfacial tension of PAAD/C8mimBr complex solution and crude oil under different conditions was examined. Moreover, PAAD/C8mimBr complex exhibited superior temperature resistance and shear reversible performance for enhancing oil recovery (EOR) by rheological test. The promising EOR of 21.65% can be obtained by PAAD/C8mimBr complex showing high potential to utilize this kind of new complex in EOR processes.

Biodegradable polyethylene glycol-based ionic liquids for effective inhibition of shale hydration

A series of ionic liquids based on polyethylene glycol (PEG) with different molecular weights were prepared for inhibiting shale hydration and swelling. The antiswelling ratio was measured to investigate the effect of different PEG-based ionic liquids on bentonite volume expansion, and it has shown that the ionic liquid based PEG200, i.e. PEG with molecular weight of 200, exhibited superior inhibition. The structures of the PEG200-based ionic liquids were characterized by ¹H NMR studies. The XRD results indicated that the PEG200-based ionic liquids intercalated into sodium montmorillonite (Na-MMT) reducing the water uptake by the clay. The formation of complexes of Na-MMT and PEG200-based ionic liquids was also verified by FTIR spectroscopy. Thermal degradation analysis suggested that the PEG200-based ionic liquids accessed the interlamellar spaces of Na-MMT and reduced the water content of the complexes obtained. Moreover, no breaks and collapse were observed on the shale samples after immersion in PEG200-based ionic liquid solutions. All the PEG200-based ionic liquids showed biodegradability and potential application in effective inhibition for clay hydration.

Electrochemistry of tris(2,2′-bipyridyl) cobalt(II) in ionic liquids and aprotic molecular solvents on glassy carbon and platinum electrodes

The tris(2,2′-bipyridyl) complexes of cobalt(II) and (III) ([Co(bpy)3]^2+/3+) produce a redox couple of great interest in thermoelectrochemical cells and dye sensitized solar cells including both types of devices based on ionic liquid electrolytes. We present a systematic study of the electrochemistry of [Co(bpy)3]²⁺ [NTf2]^-2 in two ionic liquids (ILs) based on the 1-ethyl-3-methylimidazolium (C2mim) cation and two ILs based on the 1-butyl-1-methylpyrrolidinium cation (C4mpyr), as well as three aprotic molecular solvents. Platinum (Pt) and glassy carbon (GC) working electrodes were compared. In all solvents better electrochemical responses were observed on GC, which yielded higher currents in the cyclic voltammograms and lower rate constants for the redox reaction. The [Co(bpy)3]^1+/2+ couple is also readily observed, but this redox reaction is chemically irreversible, possibly because the [Co(bpy)3]¹⁺ complex dissociates. However, the [Co(bpy)3]^1+/2+ reaction is chemically reversible in all of the solvents studied, except 3-methoxypropionitrile, if excess of 2,2′-bipyridyl is added to the solution.

Novel imidazolinium ionic liquids and organic salts

The preparation and physical properties of a novel family of ionic liquids and organic salts based on the imidazolinium cation are described, and compared with their imidazolium analogues in some cases. Ionic liquids were obtained with the triflate, formate and salicylate anions, while > 100 °C melting points were observed with acetate and several other benzoate derivatives. The triflate salt was less ion-conductive than the corresponding imidazolium salt, but less so than expected on the basis of its viscosity, suggesting a contribution from proton conductivity. The electrochemical window of the imidazolinium was slightly extended in the reductive direction, due to the lower proton activity produced by the cation in this case. Imidazolinium salts are also known to exhibit anti-corrosion properties and hence a preliminary study of this property is also reported; 2-methylimidazolinium 4-hydroxycinnamate was found to show strong anodic corrosion inhibition on mild steel.