IL Content Research Articles

Thermal and spectral characterization and stability of mixtures of ionic liquids [EMIM]Ac and [BMIM]Ac with ethanol, methanol, and water at ambient conditions and at elevated temperatures and pressures

The ionic liquids 1-ethyl-3-methylimidazolium acetate, [EMIM]Ac, and 1-butyl-3-methylimidazolium acetate, [BMIM]Ac, were characterized using TGA, FTIR, and UV–vis spectroscopy. Their mixtures with the protic solvents ethanol, methanol, and water were characterized with FTIR and UV–vis spectroscopy. Absorbance versus concentration calibration curves over the full concentration range from 0 to 100 wt % IL content were generated for the mixtures. The thermal stability of the ionic liquids was evaluated by dynamic TGA runs through the assessment of the onset of decomposition and peak decomposition temperatures. Additionally, isothermal TGA runs were performed at 100, 120, and 150 °C over a period of 24 h. The results show that these ionic liquids are not stable over long time exposures, displaying significant weight loss over time above 100 °C. The thermal stability of mixtures of these ILs with ethanol, methanol, water and an aprotic solvent, DMF, were assessed further with time-lapsed UV–vis spectroscopy using a high-pressure view-cell at temperatures in the range 100–150 °C at 35 and 350 bar over a 24 h exposure time. The UV spectra for the ethanol and methanol mixtures shifted over time at 120 and 150 °C. The mixtures with water did not demonstrate significant changes at any of these temperatures. This was in contrast to mixtures with DMF, in which spectral shifts occurred almost immediately at all studied temperatures. These ionic liquids and their mixtures in these solvents are important in biomass processing and their thermal stability under process conditions must therefore be given due consideration in rational process design.

Cage-like cross-linked membranes with excellent ionic liquid retention and elevated proton conductivity for HT-PEMFCs

Polybenzimidazole/ionic liquid (IL) composite membranes with cage-like cross-linked structure were prepared based on polybenzimidazole containing hydroxyl groups (PBIOH30), 3-(triethoxysilyl) propyl isocyanate (IPTS) and 1-butyl-3-methylimidazolium dihydrogen phosphate (BMI-DHPH). The basic characteristic of imidazole rings in IL enhanced the phosphoric acid (PA) doping ability of the obtained cPBI-IL X membranes, thus, the proton conductivity of which was elevated. The cage-like cross-linked structure was formed under acidic conditions, and such structure can not only strengthen the mechanical properties of cPBI-IL X membranes but also prevent the leakage of the IL to some extent. The IL retention ability of cPBI-IL 10 was significantly improved, the residual weight percentage of IL was 71.6 wt%, while that of PBI-IL 10 membrane without cage-like cross-linked structure was only 2 wt%. The membrane with 8 wt% IL content exhibited the highest proton conductivity of 0.133 S cm−1 at 160 °C.

Morphology and pervaporation performance of ionic liquid and waterborne polyurethane composite membranes.

Blending an aromatic-selective ionic liquid (IL, namely 1-ethyl-3-methylimidazolium hexafluorophosphate, [emim][PF6]) with waterborne polyurethane (WPU) enabled us to obtain [emim][PF6]-modified waterborne polyurethane composite membranes. We characterized the structure and properties of the [emim][PF6]/WPU composite membranes by ATR-FTIR, DSC, UV, SEM, EDX, swelling tests, and pervaporation testing. Characterization of the change in the morphology of the membranes in response to the IL loading indicated that a preferential interaction between the IL and soft segments of WPU was induced by hydrogen bonding. This interaction inhibited a potential interaction with benzene (Bz), which initially lowered the permeability. However, at high IL loading, the IL incorporation became ineffective owing to macrophase separation, which caused an increase in the permeability, as indicated by the SEM results. Swelling testing of the [emim][PF6]/WPU composite membranes showed that the membranes exhibited preferential adsorption of Bz, and the swelling degree of the composite membranes in Bz solvent increased from 58% to 98% and remained almost constant in cyclohexane solvent as the IL content was increased. The [emim][PF6]/WPU composite membranes enhanced the separation selectivity of Bz/Cy for an IL loading < 10 wt%. The best separation factor was 8.4, and the total flux was 0.19 kg (m2 h)−1 (50 wt% Bz/Cy mixtures at 50 °C) at w([emim][PF6]) : w(WPU) = 10 : 100. In addition, the composite membrane exhibited excellent stability over long-term operation. These results demonstrated that the [emim][PF6]/WPU composite membranes could be effective for separation of Bz/Cy mixtures by the pervaporation method.

Visible‐Light Photocatalytic Activity of Ionic Liquid TiO2 Spheres: Effect of the Ionic Liquid's Anion Structure

AbstractThe effect of the ionic liquid's (IL) anion type ([BMIM][X], where BMIM=1‐butyl‐3‐methylimidazolium and X=[Br], [PF6], or octylsulfonate [OctSO4]) and IL content on the morphology, surface properties, and photoactivity of TiO2 obtained by the solvothermal method has been systematically investigated. Our results revealed that the presence of [Br] and [OctSO4] anions favor the formation of anatase phase, whereas the presence of [PF6] causes formation of anatase and Ti(OH)PO4 phase mixtures. The highest photocatalytic activity under visible radiation (approximately four times higher than pristine TiO2) was observed for the TiO2 sample grown in the presence of 1‐butyl‐3‐methylimidazolium bromide for ionic liquid to TiO2 precursor molar ratio 1:2. Visible‐light‐induced phenol degradation was found to be realized mainly by oxygen radical anions, whereas the contributions of the other processes involving reactions with trapped electrons, holes, and hydroxyl radical, are limited in the overall reaction mechanism. Quantum chemical calculations on a model of anatase vacancy suggest that the charge transfer between the bromide anion and molecular oxygen interacting with the vacancy is a source of photoactivity induced by visible photons.

Electrode-Impregnable and Cross-Linkable Poly(ethylene oxide)-Poly(propylene oxide)-Poly(ethylene oxide) Triblock Polymer Electrolytes with High Ionic Conductivity and a Large Voltage Window for Flexible Solid-State Supercapacitors.

We present cross-linkable precursor-type gel polymer electrolytes (GPEs) that have large ionic liquid uptake capability, can easily penetrate electrodes, have high ion conductivity, and are mechanically strong as high-performance, flexible all-solid-state supercapacitors (SC). Our polymer precursors feature a hydrophilic-hydrophobic poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock main-chain structure and trifunctional silane end groups that can be multi-cross-linked with each other through a sol-gel process. The cross-linked solid-state electrolyte film with moderate IL content (200 wt %) shows a well-balanced combination of excellent ionic conductivity (5.0 × 10-3 S cm-1) and good mechanical stability (maximum strain = 194%). Moreover, our polymer electrolytes have various advantages including high thermal stability (decomposition temperature > 330 °C) and the capability to impregnate electrodes to form an excellent electrode-electrolyte interface due to the very low viscosity of the precursors. By assembling our GPE-impregnated electrodes and solid-state GPE film, we demonstrate an all-solid-state SC that can operate at 3 V and provides an improved specific capacitance (112.3 F g-1 at 0.1 A g-1), better rate capability (64% capacity retention until 20 A g-1), and excellent cycle stability (95% capacitance decay over 10 000 charge/discharge cycles) compared with those of a reference SC using a conventional PEO electrolyte. Finally, flexible SCs with a high energy density (22.6 W h kg-1 at 1 A g-1) and an excellent flexibility (>93% capacitance retention after 5000 bending cycles) can successfully be obtained.

Synthesis, characterization, and CO2 separation performance of polyether sulfone/[EMIM][Tf2N] ionic liquid-polymeric membranes (ILPMs)

Abstract The objective of this research is to combine the superior features of polyethersulfone (PES) polymer and higher affinity of 1-ethyl-3-methyl imidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf2N]) ionic liquid for CO2 gas, in ionic liquid-polymeric membranes (ILPMs) at higher ionic liquid concentrations. The ionic liquid embedded membranes were characterized and tested for pure carbon dioxide and methane gases at 25 °C temperature and at a relatively higher pressure range of 5–25 bar. The morphology of the membranes was dense and defect free as deduced from FESEM analysis. The gas permeation studies confirmed that increasing IL content in ILPMs resulted in the enhancement of both CO2 permeability and CO2/CH4 selectivity simultaneously, due to high affinity of CO2 in IL. This was observed when the permeation of carbon dioxide increased significantly from 2.42 barrer for neat PES membrane to 298.84 barrer (124-fold increment) for ILPM containing 50 wt. % IL, at 25 °C and 25 bar. The resultant selectivity was improved from 15.91 to 57.53, which accounted for ∼3.6-fold increase in the ideal selectivity. The synthesized membranes are promising materials for industrial gas separation membranes for CO2 removal from CH4 gas at higher pressures and higher IL contents.

Preparation and characterization of novel Ionic liquid/Pebax membranes for efficient CO 2 /light gases separation

Abstract In this study, the goal is to incorporate superior features of the Pebax 1657 copolymer, such as high mechanical resistance and exceptional gas permeability especially for polar gases, with the affinity of the 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF 4 ]) ionic liquid to CO 2 gas, which results in increasing the permselectivity of the membranes for CO 2 /light gases separation. Generally, the CO 2 solubility in ILs increases with pressure increment, and temperature decrement. Therefore, gas permeation results of prepared membranes were obtained at temperature of 35 °C and feed pressure range 2–10 bar. SEM, ATR and DSC analysis were carried out on different compositions of membranes and the results showed that adding the IL to the polymer make membranes more amorphous and less crystalline which lead to increase permeability for all tested gases. In addition, due to the high affinity of CO 2 in both polymer and IL, both CO 2 permeability and selectivity increased simultaneously with increasing IL content. This is confirmed by gas permeation results, where at 35 °C and 10 bar, the CO 2 permeability increased from 110 Barrer for neat Pebax to 190 Barrer in the blended membrane containing 50 wt.% IL (about 73%). The related CO 2 /CH 4 and CO 2 /N 2 selectivities were increased from 20.8 to 24.4 (about 17%) and from 78.6 to 105.6 (about 34%), respectively. Thus, these types of membranes are promising to be utilized in gas separation processes in industries for CO 2 separation in order to postpone the global warming, which is nowadays the biggest threat to the universe.

Thermal, mechanical and conductive properties of imidazolium-containing thiol-ene poly(ionic liquid) networks

Abstract A series of imidazolium-based bis(trifluoromethylsulfonyl)imide [NTf2] poly(ionic liquid)s (PILs) were prepared by conducting the solventless thiol-ene ‘click’ photopolymerization of bisallylimidazolium [NTf2] and pentaerythritol tetrakis(3-mercaptopropionate) (PTMP). The thiol:ene molar ratio was varied in order to examine changes in the thermal, mechanical and conductive properties of the resulting polymer networks. The 1.0:2.0 thiol-ene PIL network exhibited the highest glass transition temperature (Tg of −5.0 °C) and storage modulus (E′ of 9.24 MPa at 100 °C) values. Temperature-dependent ionic conductivities were found to rely on both the Tg/crosslink density as well as the IL content, with the highest ionic conductivity observed for the 1.0:3.0 thiol-ene PIL network (1.42 × 10−5 S/cm at 25 °C). Application of Vogel-Fulcher-Tammann and Williams-Landel-Ferry theories revealed the impact of both Tg/crosslink density and free ion concentration on temperature-dependent conductivity data, and indicated lower free volumes and fragilities for the thiol-ene networks relative to other non-network PILs.

Ionic Liquid Based Polymer Gel Electrolyte Membranes for Lithium Ion Rechargeable Batteries

Li-ion conducting polymer gel electrolyte membranes (PGEMs) based on polymer poly(vinylidene fluoride-co-hexafluoropropylene) PVdF-HFP, ionic liquid, 1-butyl-3-methylimidazolium tetrafluroborate BMIMBF4 and Lithium bis(trifluoromethanesulfonyl)imide) LiTFSI salt (having different anion i.e. BF4 - and TFSI-) have been synthesized and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), Differential scanning calorimetry (DSC), Thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), complex impedance spectroscopy and cyclic voltammetry. After incorporation of IL in polymer electrolyte, (i.e. PVdF-HFP+20wt.% LiTFSI) different physicochemical properties such as melting temperature (Tm), glass transition temperature (Tg), thermal stability, degree of crystallinity (Xc), and ionic transport behaviour of these materials are found to change. The pristine PVdF-HFP possessed a semi-crystalline structure and its amorphicity increased with the addition of LiTFSI salt and BMIMBF4 ionic liquid. An impedance measurement indicated that the room-temperature ionic conductivity of the membranes increased with increasing IL content and attains a maximum value of 3.2 *10-3 S/cm at 30 °C and ~ 8.7*10-3 S/cm at 130 °C. An schematic representation exhibiting increase in ionic conductivity with increasing amount of dopant ionic liquid has been shown in the given figure. In addition, temperature dependent ionic conductivity seems to obey Arrhenius type thermally activated behaviour. A high total ionic transference number > 0.99 and the cationic transference number (tLi +) ~0.33 with a wider electrochemical window (ECW) ~4.0–5.0 V for the PGEMs containing higher loading of IL have been obtained. Fig. Schematic representation exhibiting increase in ionic conductivity with increasing amount of dopant Ionic Liquid. Figure 1

Mass and Charge Transport in the Polymer-Ionic-Liquid System PEO-EMImI: From Ionic-Liquid-in-Polymer to Polymer-in-Ionic-Liquid Electrolytes.

Conventional polymer electrolytes based on inorganic salts are commonly characterized and utilized over a small salt-poor composition range because of phase transitions accompanied by loss of ion conductivity at high salt concentrations. By contrast, well-chosen polymer-ionic-liquid (IL) systems offer the possibility to vary the IL content from the IL-in-polymer to the polymer-in-IL domain. We have investigated the temperature-dependent ionic conductivity in PEOyEMImI systems consisting of poly(ethylene oxide) complexed with 1-ethyl-3-methylimidazolium iodide for y = EO/IL ratios ranging from 0.6 to 60 and compared diffusivity data with that arising from (1)H pulsed-field-gradient nuclear magnetic resonance for EMIm and (125)I radiotracer diffusion for iodine. Surprisingly, the diffusivity of cations and anions vary at most by 50% at fixed temperatures over the entire composition range. The much larger changes in the charge diffusivity Dσ relate to ion pairing exhibiting a minimum near the intermediate composition y = 10. Altogether, the results are relevant to application in dye-sensitized solar cells and show that a high ion density is crucial to enhance the iodine transport capacity.

An all-organic solid-state electrochromic device containing poly(vinylidene fluoride-co-hexafluoropropylene), succinonitrile, and ionic liquid

A high contrast, self-standing, and thermoplastic solid polymer electrolyte (PE) with electrochromic property is fabricated by utilizing N,N,N′,N′-tetramethyl-p-phenylenediamine (TMPD), heptyl viologen (HV(BF4)2), succinonitrile (SN), and poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP). Various amounts of the ionic liquid (IL, BMIMBF4) are added into the PE, and the amount of IL is found to play an important role in affecting the ionic conductivity, morphology, and thus electrochemical property of the obtained PE. The IL content in the PE is optimized in order to achieve a better electrochemical and electrochromic properties of the obtained electrochromic device (ECD). The effect of the IL content in PE on the electrochemical and electrochromic properties of the ECD is discussed in terms of the ionic conductivity and morphology of the PE. The optimized ECD, which uses the PE containing 5wt% IL, exhibits a reversible transmittance change of 60.1% at 615nm during the switching between 0 and 0.9V with a promising long-term stability; both the transmittance change and the long-term stability of the ECD using the PE containing 5wt% IL are much better than that using the PE without IL.

Solvent-Free Electrolytes for Electrical Double Layer Capacitors

A mechanically-stable non-aqueous inorganic gel polymer electrolyte that is based on association of sol-gel agents and Ionic Liquid is considered here for application in solid-state solvent free supercapacitors. The first part is devoted to the electrochemical characterization of the ionogel bulk properties. In the second part, an electrochemical cell using activated carbon as active materials and the new ionogel electrolyte has been characterized over a wide temperature range using cyclic voltammetry and electrochemical impedance spectroscopy. The use of high IL content (70%) has led to an increase of both the operating voltage window (up to 3 V) and the electrolyte ionic conductivity (around 4.7 mS/cm). The resulting double layer capacitance of the microporous activated carbon device was found to be as high as 80 F/g; even more important, this quasi solid electrolyte works well over a wide temperature range (namely, from −30 to more than 80°C).

Modeling of the volumetric properties and estimation of the solubility parameters of ionic liquid + ethanol mixtures with the Sanchez–Lacombe and Simha–Somcynsky equations of state: [EMIM]Ac + ethanol and [EMIM]Cl + ethanol mixtures

A variable-volume view-cell equipped with a motorized pressure generator was utilized to collect PVT data for two different ionic liquids, [EMIM]Ac and [EMIM]Cl, and their mixtures with ethanol which are of interest as alternative solvents for processing of lignocellulosic materials. Continuous density data were generated from 10 to 40MPa at temperatures of 298, 323, 348, 373, and 398K. Pressure scans were performed on both ILs, ethanol, and their mixtures with 5, 25, 50, and 75wt% IL content. The density data were used to determine the parameters for the Sanchez–Lacombe (S-L) and Simha–Somcynsky (S-S) equations of state (EOS). The S-L EOS was then employed to estimate isobaric expansivity, isothermal compressibility, internal pressure, free-volume fractions, and the solubility parameters for these mixtures. The S-S EOS was also used to evaluate the free-volume fractions, and the solubility parameters as this EOS provides more direct assessments of these quantities. The manuscript provides for the first time solubility parameter values for [EMIM]Cl. The manuscript for the first time also provides solubility parameter values at pressures above ambient pressure for both of these ionic liquids, for ethanol, and for their mixtures. The solubility parameters estimated for [EMIM]Ac at 10MPa and 298K were around 22.7MPa0.5 by S-L EOS, and around 21.8MPa0.5 by S-S EOS as compared to the literature value of 23.1MPa0.5 reported at ambient pressure and at 313K.

Soft and flexible PEDOT/PSS films for applications to soft actuators

Stretchable and highly conductive PEDOT/PSS/Xyl films were prepared by casting an aqueous dispersion of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT/PSS) as colloidal gel particles containing xylitol (Xyl) and subsequent heating. The electrical conductivity of the PEDOT/PSS/Xyl film containing 50 wt% of xylitol significantly increased from 115 S cm−1 to 407 S cm−1 by heating at 140 °C in air for 1 h. It was found that the xylitol had two functions as (i) a plasticizer to weaken hydrogen bonds between PSS of colloidal particles by replacing with that between xylitol and PSS and (ii) the additional capability of increasing the mobility of charge carriers between the colloidal particles. The transparent ionic liquid/polyurethane (IL/PU) gels were fabricated by dissolving thermoplastic polyurethane and ionic liquid of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. By increasing the IL content from 0 wt% to 70 wt%, both ionic conductivity and electric-double-layer capacitance under an electric field increased, while Young’s modulus, strength and elongation at break decreased. The IL/PU/PEDOT/PSS/Xyl composites were fabricated by sandwiching the IL/PU gel between two soft and flexible PEDOT/PSS/Xyl films. Upon application of 2 V, the IL/PU/PEDOT/PSS/Xyl composite (IL = 70%) showed quick and intensive bending toward anode, where the bending displacement at 0.1 Hz attained 2.9 mm, corresponding to the strain of 0.15%, and still worked at frequencies higher than 50 Hz.

Tetraalkylphosphonium Ionic Liquid Encapsulation in Alginate Beads for Cd(II) Sorption from HCl Solutions

Cyphos IL 105 (tetraalkylphosphonium dicyanamide) was immobilized in alginate capsules (IL vesicle entrapped in a biopolymer layer, as shown by SEM-EDX analysis). This material was tested for efficient Cd(II) sorption from HCl solutions. The concentration of HCl and chloride ions hardly influenced metal sorption that proceeds through ion exchange between Cd(II) (under the form of CdCl42−) and 2 dicyanamide groups. The sorption capacity (at saturation of the resin) proportionally increased with IL content (respecting the 1:2 stoichiometry between Cd(II) and the phosphonium cation). The uptake kinetics are well described by the Crank’s equation (resistance to intraparticle diffusion) and by the pseudo-second order rate equation (chemical reaction rate).

Translational diffusion in mixtures of imidazolium ILs with polar aprotic molecular solvents.

Self-diffusion coefficients of cations and solvent molecules were determined with (1)H NMR in mixtures of 1-n-butyl-3-methylimidazolium (Bmim(+)) tetrafluoroborate (BF4(-)), hexafluorophosphate (PF6(-)), trifluoromethanesulfonate (TfO(-)), and bis(trifluoromethylsulfonyl)imide (TFSI(-)) with acetonitrile (AN), γ-butyrolactone (γ-BL), and propylene carbonate (PC) over the entire composition range at 300 K. The relative diffusivities of solvent molecules to cations as a function of concentration were found to depend on the solvent but not on the anion (i.e., IL). In all cases the values exhibit a plateau at low IL content (x(IL) < 0.2) and then increase steeply (AN), moderately (γ-BL), or negligibly (PC) at higher IL concentrations. This behavior was related to the different solvation patterns in the employed solvents. In BmimPF6-based systems, anionic diffusivities were followed via (31)P nuclei and found to be higher than the corresponding cation values in IL-poor systems and lower in the IL-rich region. The inversion point of relative ionic diffusivities was found around equimolar composition and does not depend on the solvent. At this point, a distinct change in the ion-diffusion mechanism appears to take place.

Facile preparation of polymer electrolytes based on the polymerized ionic liquid poly((4-vinylbenzyl)trimethylammonium bis(trifluoromethanesulfonylimide)) for lithium secondary batteries

The polymer electrolytes based on a novel poly((4-vinylbenzyl)trimethylammonium bis(trifluoromethanesulfonylimide)) polymeric ionic liquid (PIL) as polymer host and containing DEME-TFSI ionic liquid, LiTFSI salt and nano silica are prepared. The polymer electrolyte is chemically stable even at a higher temperature of 60°C in contact with lithium anode. Particularly, the electrolyte exhibits high lithium ion conductivity, wide electrochemical stability window and good lithium stripping/plating performance. When the IL content reaches 60% (the weight ratio of DEME-TFSI/PIL), the PIL electrolyte presents a higher ionic conductivity, and it is 7.58×10−4 S cm−1 at 60°C. Preliminary battery tests show that Li/LiFePO4 cells with the PIL electrolytes are capable to deliver above 130 mAh g−1 at 60°C with very good capacity retention.

Drug delivery systems based on pharmaceutically active ionic liquids and biocompatible poly(lactic acid).

Poly(l-lactic acid) (PLLA) membranes containing pharmaceutically active ionic liquids (API-ILs) have been prepared by using a simple film casting from solvent evaporation method. Several sets of membranes were prepared from two different ionic liquids namely 1-methyl-3-butyl-imidazolium ibuprofenate (C4MImIbu) and lidocainium ibuprofenate (LidIbu) with different API-IL contents. Scanning Electron Microscopy (SEM), Differential Scanning Calorimetry (DSC), Wide-Angle and Small-Angle X-ray Scattering (WAXS and SAXS) revealed the strong influence of both the IL nature and content on the morphology and the crystallinity of the resulting PLLA. At 20 weight%, LidIbu was shown to act as a plasticizer for PLLA and homogeneous membranes were obtained. In contrast, at the same IL content, phase separation occurred using C4MImIbu, resulting in the formation of porous PLLA. An increase of LidIbu content to 50 weight% results also in phase separation. 1H and 1H-13C CP-MAS NMR measurements evidenced the influence of different morphologies and crystallinities on IL mobility. C4MImIbu was found to be highly mobile whereas the mobility of LidIbu was content dependent. At low percent, low mobility was observed while at higher content, two populations with respectively high and low mobility were observed. These PLLA-IL membranes were further tested as drug delivery systems. In accordance with the morphology and mobility obtained, we demonstrated that release kinetics from PLLA membranes can be tuned by the nature and the content of API-ILs. Sustainable release kinetics were obtained with API-IL acting as a plasticizer while the fastest release was obtained with API-IL acting as a porogenic agent.

Ionic liquid/polyurethane/PEDOT:PSS composites for electro-active polymer actuators

The transparent ionic liquid/polyurethane (IL/PU) gels were synthesized by addition reaction of polyol and diisocyanate in the presence of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. With increasing the IL content from 0wt% to 40wt%, both ionic conductivity and electric-double-layer capacitance increased from 3.1×10−5Scm−1 and 9.6pFcm−2 to 8.8×10−5Scm−1 and 277pFcm−2, respectively, while the compression modulus slightly decreased from 0.49MPa to 0.44MPa. The IL/PU/PEDOT:PSS composites were fabricated by sandwiching the IL/PU gel between two conductive polymer films made of poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonate) (PEDOT:PSS) as soft and flexible electrodes. Upon application of an electric field, the IL/PU/PEDOT:PSS composite showed quick and intensive bending toward anode, where the bending displacement attained 3.8mm at IL=40wt% and 2V, corresponding to the strain of 0.32%.

Enhanced Cu (II) Adsorption from Aqueous Solutions by Sawdust (&lt;i&gt;Quercus mongolica&lt;/i&gt;) Pretreated by Ionic Liquid-Water Mixture

This work investigated the feasibility of Quercus mongolica sawdust pretreated by an ionic liquid-water mixture as a biosorbent for Cu (II) removal from aqueous solutions. Maximum Cu (II) biosorption of 32.6 mg/g is obtained at initial pH 4.3 using sawdust pretreated by a 1-butyl-3-methylimidazolium chloride ([C4miCl)-water mixture (IL content 60%) at 90oC, which is higher than that of unpretreated sawdust (23.0 mg/g, initial pH 6.1). The proposed method is effective in enhancing adsorption capacity of the biomass in comparison to the conventional methods using sulfur acid or sodium hydroxide solutions.