Cellulose Solvent Research Articles

Dissolving Cellulose in 1,2,3-Triazolium- and Imidazolium-Based Ionic Liquids with Aromatic Anions.

We present 1,2,3-triazolium- and imidazolium-based ionic liquids (ILs) with aromatic anions as a new class of cellulose solvents. The two anions in our study, benzoate and salicylate, possess a lower basicity when compared to acetate and therefore should lead to a lower amount of N-heterocyclic carbenes (NHCs) in the ILs. We characterize their physicochemical properties and find that all of them are liquids at room temperature. By applying force field molecular dynamics (MD) simulations, we investigate the structure and dynamics of the liquids and find strong and long-lived hydrogen bonds, as well as significant – stacking between the aromatic anion and cation. Our ILs dissolve up to 8.5 wt.-% cellulose. Via NMR spectroscopy of the solution, we rule out chain degradation or derivatization, even after several weeks at elevated temperature. Based on our MD simulations, we estimate the enthalpy of solvation and derive a simple model for semi-quantitative prediction of cellulose solubility in ILs. With the help of Sankey diagrams, we illustrate the hydrogen bond network topology of the solutions, which is characterized by competing hydrogen bond donors and acceptors. The hydrogen bonds between cellulose and the anions possess average lifetimes in the nanosecond range, which is longer than found in common pure ILs.

Recent Progress in High-Strength and Robust Regenerated Cellulose Materials.

High-strength petroleum-based materials like plastics have been widely used in various fields, but their nonbiodegradability has caused serious pollution problems. Cellulose, as the most abundant sustainable polymer, has a great chance to act as the ideal substitute for plastics due to its low cost, wide availability, biodegradability, etc. Herein, the recent achievements for developing cellulose "green" solvents and regenerated cellulose materials with high strength via the "bottom-up" route are presented. Cellulose can be regenerated to produce films/membranes, hydrogels/aerogels, filaments/fibers, microspheres/beads, bioplastics, etc., which show potential applications in textiles, biomedicine, energy storage, packaging, etc. Importantly, these cellulose-based materials can be biodegraded in soil and oceans, reducing environmental pollution. The cellulose solvents, dissolving mechanism, and strategies for constructing the regenerated cellulose functional materials with high strength and performances, together with the current achievements and urgent challenges are summarized, and some perspectives are also proposed. The near future will be an exciting era for high-strength biodegradable and renewable materials. The hope is that many environmentally friendly materials with good properties and low cost will be produced for commercial use, which will be beneficial for sustainable development in the world.

A cautionary note on \u201cexothermic events\u201d upon contact of carbodiimide coupling agents and the cellulose solvent N-methylmorpholine-N-oxide

The cellulose solvent N-methylmorpholine-N-oxide monohydrate (NMMO) reacts violently with carbodiimide coupling agents, such as the widely used DCC (dicyclohexylcarbodiimide) and EDC (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide), which can cause explosions, heavy smoke generation and complete charring of the reaction mixtures. For this reason it is clear that cellulose or other carbohydrates dissolved in NMMO (“Lyocell conditions”) cannot be safely esterified or amidified under DCC/EDC conditions. It is important to note that cellulosic material regenerated from NMMO solutions also poses a risk if it contains residual NMMO, which can then come into contact with DCC-type coupling agents in non-aqueous media, as recent accidents have unfortunately shown. Similarly, EDC/DCC traces in cellulose can have detrimental effects when trying to dissolve the material in NMMO. Working in aqueous systems generally reduces the risk of uncontrolled reactions, while alcohols or aprotic solvents are not very effective in this regard. Washing for NMMO removal or EDC/DCC removal should therefore always be carried out by aqueous media, if any possible, if there is a potential risk that the reagents might come into contact later. This warning describes the potential hazards of the reagent combination, highlights the underlying degradation mechanism and explains the precautions to be taken to avoid any “exothermic events”.Graphic abstract

All-Cellulose Composites: A Review of Recent Studies on Structure, Properties and Applications.

Nowadays, there is greater demand for greener materials in societies due to environmental consciousness, depleting fossil fuels and growing ecological concerns. Within the foreseeable future, industries and suppliers will be required to be more aware of challenges faced due to the availability of resources and use more sustainable and renewable raw materials. In this context, cellulose can be expected to become a vital resource for materials owing to its abundance, versatility as a biopolymer, several different forms and potential applications. Thus, all-cellulose composites (ACCs) have gained significant research interest in recent years. ACC is a class of biocomposites in which the matrix is a dissolved and regenerated cellulose, while the reinforcement is undissolved or partly dissolved cellulose. This review paper is intended to provide a brief outline of works that cover recent progress in the manufacturing and processing techniques for ACCs, various cellulose sources, solvents and antisolvents, as well as their properties.

Probing Interactions in Combined Hydroxide Base Solvents for Improving Dissolution of Cellulose.

To further understand cellulose-solvent interactions in aqueous hydroxide solutions, cellulose behavior in aqueous solutions of NaOH combined with tetramethylammonium hydroxide (TMAH) or benzyltrimethylammonium hydroxide (Triton B), as well as urea, was investigated. The rheological properties of the solutions were assessed through flow sweeps at different temperatures, and the intermolecular interactions were probed using solvatochromic dyes. The results showed that NaOH combined with TMAH had synergistic effects on cellulose dissolution and was a better solvent for cellulose than the combination of NaOH with Triton B, in spite of the superior dissolution ability of Triton B alone. This somewhat unexpected finding shows that the base pair needs to be selected with care. Interestingly, addition of urea had no significant effect on the solvatochromic parameters or dissolution capacity of solutions of Triton B but rendered improved stability of solutions containing NaOH and/or TMAH. It seems that both urea and Triton B weaken the hydrophobic assembly effect of these solutions, but urea is excluded from interacting with cellulose in the presence of Triton B. This study provides further insight into dissolution of cellulose and the possibility of utilizing combinations of hydroxide bases to achieve improved solution properties.

Rapid allylation of cellulose without heating in tetra-n-butylphosphonium hydroxide aqueous solution

Allyl cellulose is an important intermediate for cellulose functionalization because of the high reactivity of the allyl group. In this work, a rapid allylation of cellulose with allyl bromide was realized under mild ambient conditions by using a cellulose solvent, tetra-n-butylphosphonium hydroxide aqueous solution, for the reaction medium. The allylation proceeded with a consecutive change in the state of the reaction system from the initial transparent liquid through a colloidal emulsion to the definitive suspension. The reaction conducted for 1 h yielded allyl cellulose showing a degree of substitution (DS) of ~ 2.0; virtually, however, the substitution to DS ≈ 1.9 was attained at the stage of 10 min elapsing. The reaction behavior was interpreted in terms of a model scheme proposed previously for cellulose benzylation using a similar reaction medium. The allyl products indexed with such a relatively high DS (> 1.8) were well soluble in various organic solvents. It was also shown that the present synthetic process gave rise to no serious degradation of the cellulose main chains nor cross-linking between the introduced allyl groups.

Non-covalent interactions of imidazolium-based ionic liquids with model pyrrolidones revealed by FTIR spectroscopy and quantum chemical model calculations

Certain ionic liquids (ILs), such as 1-butyl-3-methylimidazolium chloride (bmimCl) and 1-ethyl-3-methylimidazolium acetate (emimAc), are potent cellulose solvents, but the high viscosity of the resulting solutions is problematic in many applications. Organic co-solvents are often employed to alleviate this problem; however, our understanding of the intermolecular interactions determining the IL/co-solvent mixture performance is very limited, hampering the further development of this class of cellulose solvents. Herein, we applied infrared spectroscopy (IR), Raman spectroscopy, and quantum chemical model calculations to investigate the intermolecular interactions in differently concentrated mixtures of bmimCl and emimAc with amidic co-solvents, N-methyl-2-pyrrolidone (NMP) and N-vinyl-2-pyrrolidone (NVP). Based on the detailed analysis of the vibrational spectra of individual mixture components and the improved assignment of the relevant characteristic bands, we determined that bmim+-co-solvent and emim+-co-solvent associates, stabilized by the hydrogen bonds between amidic carbonyl oxygens and the CH groups of the imidazolium rings, are formed in the mixtures. In addition, the data pointed to concomitant disruption of the H-bonds between the IL counterions as the co-solvent concentration was increased, which may indicate partial dissociation of the IL ion pairs. Further, through an extensive deconvolution analysis, we quantified the molar fractions of the co-solvent molecules involved in the associate formation, finding that this fraction is significantly lower for emimAc than for bmimCl mixtures at all the studied concentrations. On the other hand, the influence of the amidic co-solvent structure was negligible, suggesting that also other (aprotic) amides may be applicable as co-solvents. Furthermore, the calculated molar ratio of IL to interacting co-solvent molecules highlighted the possible differences in the associate stoichiometry. The findings indicate that the lower affinity of the IL to co-solvents in emimAc-based mixtures may lead to the retaining of larger IL-rich clusters and, consequently, the comparatively better performance of the system in cellulose dissolution. Finally, increased temperature was found to influence all the studied systems similarly, inflicting about 20% decrease in the fraction of interacting co-solvent molecules at 85 °C as compared to room temperature. In summary, the results of this study provide important implications for the design of new solvent systems for cellulose dissolution.

Cellulose Nanofiber-Reinforced Ionic Conductors for Multifunctional Sensors and Devices.

Ionic conductors are normally prepared from water-based materials in the solid form and feature a combination of intrinsic transparency and stretchability. The sensitivity toward humidity inevitably leads to dehydration or deliquescence issues, which will limit the long-term use of ionic conductors. Here, a novel ionic conductor based on natural bacterial cellulose (BC) and polymerizable deep eutectic solvents (PDESs) is developed for addressing the abovementioned drawbacks. The superstrong three-dimensional nanofiber network and strong interfacial interaction endow the BC-PDES ionic conductor with significantly enhanced mechanical properties (tensile strength of 8 × 105 Pa and compressive strength of 6.68 × 106 Pa). Furthermore, compared to deliquescent PDESs, BC-PDES composites showed obvious mechanical stability, which maintain good mechanical properties even when exposed to high humidity for 120 days. These materials were demonstrated to possess multiple sensitivity to external stimulus, such as strain, pressure, bend, and temperature. Thus, they can easily serve as supersensitive sensors to recognize physical activity of humans such as limb movements, throat vibrations, and handwriting. Moreover, the BC-PDES ionic conductors can be used in flexible, patterned electroluminescent devices. This work provides an efficient strategy for making cellulose-based sustainable and functional ionic conductors which have broad application in artificial flexible electronics and other products.

Thermodynamic analysis of cellulose complex in NaOH–urea solution using reference interaction site model

Thermodynamic analysis of the empirical data for the solvation of cellulose in aqueous NaOH/urea solution was performed in this study; this was achieved by employing the three-dimensional Reference Interaction Site Model theory coupled with the Kovalenko–Hirata closure approximation. The preferential distributions of Na+, OH−, urea, and water that were in a close proximity to the cellulose molecule, enabled the calculation of the solvation energy and the contribution of each solvent species to the solvation energy. By dividing the solvation energy into the solvent potential energy under the consideration of the solvent–solute interaction and the solvent reorganization energy, cellulose solvation in the NaOH/urea solution was observed to be primarily due to reorganization of the water molecules around the cellulose molecule. The solvated structure was suggested to be composed of cellulose as an inclusion in helical clusters of Na+, OH−, urea, and water, wherein the clusters comprised a repeated arrangement of OH− hydrate, water molecules, urea hydrate, and water molecules. Cellulose is suspected to play the role of a water structure maker in the presence of NaOH and urea, and as a water structure breaker in the absence of NaOH and/or urea.

Nitrogen-doped activated carbons via melamine-assisted NaOH/KOH/urea aqueous system for high performance supercapacitors

Fabrication of carbon materials from biomass is a cost-effective and ecofriendly approach to solve the crisis of fossil resources. Herein, by melamine-assisted NaOH/KOH/urea aqueous system, nitrogen-doped activated carbon (NDAC) has been fabricated as high-performance electrode from Chinese fir sawdust. NaOH/KOH/urea aqueous is an activator and a solvent for cellulose, while urea and melamine are nitrogen sources. The effect of activation temperature and melamine dosage on the performance of NDAC was determined and discussed. The results showed that in the presence 10 g of melamine, the specific surface area (SBET) and nitrogen content of NDAC were greatly improved from 1040 to 1382 m2 g−1 and from 3.52 to 5.16%, respectively. In addition, NDAC had high N content and hierarchically interconnected porous structure, thus had good capacitive performance. Furthermore, NDAC prepared at an activation temperature of 850 °C and with 10 g of melamine had a specific capacitance of as high as 196 F g−1 at a current density of 1 A g−1. The NDAC showed satisfactory cycle capability; its capacitance retention rate could be maintained at 87.4% after 5000 galvanostatic cycles at 5A g−1. In addition, the 850°C-10-based symmetric SCs exhibit an energy density of 9.7 Wh kg−1 at a power density of 261.44 W kg−1, which enables it to be a promising electrode material for supercapacitors and renewable delivery devices.

Conversion of cotton cellulose to ZnO/C anodes for lithium-ion batteries via a sustainable self-assembly process in a green solvent

Today, many efforts have been made in biomass for high-value products. In this article, conversion of cotton cellulose to ZnO/C anodes for lithium-ion batteries (LIBs) was achieved via a simultaneously hierarchical ‘bottom-up’ assembly in a sustainable solvent system. Cotton linter was dissolved in a newly developed aqueous NaOH/zinc nitrate solution, which avoided the usage of common toxic organic cellulose solvents. What is more, the zinc salts therein not only facilitated the cellulose dissolution but were also in situ utilized as the precursor to transform into ZnO nanoparticles; thus, no additional reagents or reactions were needed. Simultaneously, cellulose was regenerated from the solution by self-assembly of its macromolecules as fibrous microspheres encapsulating the ZnO. The self-driven assembly of cellulose molecules as the building block in the solution could provide a highly porous structure as the carbon source to ensure the better performance of the anode materials than the regular non-assembled bio-derived substrate, while most importantly, no waste or by-products would be produced during the self-assembly process. The final ZnO/C composites were characterized as a LIB anode, which exhibited stable charging and discharging performance. This work demonstrated a novel process for the biomass conversion via a sustainable and efficient strategy for high-value-added materials.

Aerogels from Cellulose Phosphates of Low Degree of Substitution: A TBAF·H2O/DMSO Based Approach.

Biopolymer aerogels of appropriate open-porous morphology, nanotopology, surface chemistry, and mechanical properties can be promising cell scaffolding materials. Here, we report a facile approach towards the preparation of cellulose phosphate aerogels from two types of cellulosic source materials. Since high degrees of phosphorylation would afford water-soluble products inappropriate for cell scaffolding, products of low DSP (ca. 0.2) were prepared by a heterogeneous approach. Aiming at both i) full preservation of chemical integrity of cellulose during dissolution and ii) utilization of specific phase separation mechanisms upon coagulation of cellulose, TBAF·H2O/DMSO was employed as a non-derivatizing solvent. Sequential dissolution of cellulose phosphates, casting, coagulation, solvent exchange, and scCO2 drying afforded lightweight, nano-porous aerogels. Compared to their non-derivatized counterparts, cellulose phosphate aerogels are less sensitive towards shrinking during solvent exchange. This is presumably due to electrostatic repulsion and translates into faster scCO2 drying. The low DSP values have no negative impact on pore size distribution, specific surface (SBET ≤ 310 m2 g−1), porosity (Π 95.5–97 vol.%), or stiffness (Eρ ≤ 211 MPa cm3 g−1). Considering the sterilization capabilities of scCO2, existing templating opportunities to afford dual-porous scaffolds and the good hemocompatibility of phosphorylated cellulose, TBAF·H2O/DMSO can be regarded a promising solvent system for the manufacture of cell scaffolding materials.

New insights into the air gap conditioning effects during the dry-jet wet spinning of an ionic liquid-cellulose solution

In this paper, we report new results related to the development of a novel regenerated cellulose fiber process of the Lyocell type, denoted Ioncell™, and characterized by the use of a powerful direct cellulose solvent, 1,5-diaza- bicyclo[4.3.0]non-5-enium acetate ([DBNH][OAc]) a superbase-based ionic liquid (IL). The focus of this work is on the effects of air gap conditioning (AGC) during the dry-jet wet spinning operation. The installation of an AGC system on the spinning line led to significant improvements of the fiber properties. The fiber titer variation decreased significantly, and the fiber toughness increased by approximately 50% when controlling the temperature and the relative humidity in the airgap using a convective air flow. The presence of water vapor in the air stream was a determinant factor for the improvement of the fiber elongation. The interaction of water vapor with the spinning dope was investigated using dynamic vapor sorption. The diffusion coefficient of water vapor inside the dope could be identified from those experiments and used in a numerical simulation model of the heat and water vapor transfer in the air gap between the spinning dope and the surrounding air. The experimental and simulation results suggest that dope convective cooling and surface hydration lead to a higher fiber toughness.

Effect of H-Bonding on Brønsted Acid Ionic Liquids Catalyzed In Situ Transesterification of Wet Algae

Bronsted acid ionic liquids (BAILs) are effective to biodiesel production of in situ transesterification of wet algae due to their dual role as both solvents of cellulose and catalysts of transeste...

Pre-service chemistry teachers’ conceptions of ionic liquids as ionic solvents on the cellulose dissolution process

This study examines pre-service chemistry teachers’ understanding of concepts related to ionic liquids as cellulose solvents which include knowledge of cellulose, ionic compounds, and ionic liquids. This study used a descriptive method and involved 35 pre-service chemistry teachers from 6th semester who enrolled in the High School Chemistry unit. The research instruments of an open-ended questions which related to the concepts of ionic compounds, ionic liquids and cellulose. The results show that pre-service chemistry teachers have limited conceptions about of the concepts related to the dissolution of cellulose in ionic liquids. Based on the analysis of student answers to open-ended questions, students’ conceptions about definition of cellulose are quite good, but student have no sufficient knowledge about the structure and benefits of cellulose. Furthermore, students’ conceptions related to ionic compounds and ionic liquids are not good enough because student have not been able to mention the differences between ionic compounds and ionic liquids based on the structure, properties, and the constituent particles. This is because ionic liquids as cellulose solvents and the concepts related are not taught directly in the classroom so that it becomes an unfamiliar concept to student.

Identifying pre-service chemistry teachers’ view of the nature of science and technology’ for ionic liquids as cellulose solvent

This research aims to indentify the views of pre-service chemistry teachers about the nature of science and technology. This research was conducted using descriptive methods with participants consisting of 28 students of the Universitas Lampung. Data was collected using a view of the nature of science and technology (VNOST) questionnaire consisting of 4 aspects: Definition of science and technology, Epistemology of science, Sociology of Internal science, and external sociology of science. The results of this study indicate that pre-service teachers define science as a concept and technology as a science application. In the epistemology of science, they view scientific models as genuine objects and there are many ways to calcify. In internal science sociology, scientific decisions are based on previous theories and technological decisions based on their impact on society. For external sociology of science, pre-service teachers who agree with science-technology-society influence and influence each other. In general, the results also revealed that most of them had a good view. The results of this research will be made didactic design in the context of ionic liquids as cellulose solvents to improve the ability of VNOST pre-service chemistry teacher.

Dependence of cellulose dissolution in quaternary ammonium acetates/DMSO on the molecular structure of the electrolyte: use of solvatochromism, micro-calorimetry, and molecular dynamics simulations

We studied the dissolution of microcrystalline cellulose (MCC) at 60 °C in binary mixtures of dimethyl sulfoxide (DMSO) and the following quaternary ammonium acetates (QAAcOs): benzyl-trimethylammonium, NBzMe3AcO; diallyl-benzyl-methylammonium, NAl2BzMeAcO, tetra(n-butyl)ammonium (NBu4AcO), and tribenzyl-methylammonium, NBz3MeAcO (Al, Bu, Bz, Me, AcO refer to allyl, 1-butyl, benzyl, methyl and acetate group, respectively). We observed the following MCC dissolution order (given as wt%): NBu4AcO > NAl2BzMeAcO > NBz3MeAcO ≫ NBzMe3AcO. To explain this result we used the combined data of: (1) solvatochromism to calculate the following binary solvent (b-solvent) descriptors that are important for MCC dissolution: empirical polarity, Lewis acidity, Lewis basicity, dipolarity, polarizability; (2) isothermal titration micro-calorimetry to calculate the enthalpy of interaction (ΔH) of β-cyclodextrin (cellulose model) with QAAcO/DMSO-acetonitrile; (3) molecular dynamics simulations to calculate solvent-induced separation of cellulose chains; average number of hydrogen bonds between acetate ions and cellulose OH-groups, and average composition of the biopolymer solvation layer. We offer the following pieces of evidence to show the importance of hydrogen bonding for the efficiency of cellulose dissolution: the orders of b-solvent basicity and of |ΔH| are parallel to its cellulose dissolution efficiency; the biopolymer solvation layer of efficient b-solvents (e.g., NBu4AcO-DMSO) contains more ionic liquid ions and less DMSO molecules than that of NBz3MeAcO, leading to pronounced biopolymer chain separation, hence eventual dissolution. Our approach shows the power of the combined use of several techniques to rationalize the requirements for efficient cellulose solvents.

Synthesis and Research of Rare Earth Nanocrystal Luminescent Properties for Security Labels Using the Electrohydrodynamic Printing Technique

YVO4:Eu3+ nanoparticles were successfully synthesized by two methods, namely the sonochemical method and hydrothermal method. The X-ray diffraction (XRD) patterns showed the tetragonal phase of YVO4 (JCPDS 17-0341) was indexed in the diffraction peaks of all samples. The samples synthesized by the sonochemical method had a highly crystalline structure (X-ray diffraction results) and luminescence intensity (photoluminescence results) than those synthesized by the hydrothermal method. According to the results of field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM), the average size of YVO4:Eu3+ nanoparticles was around 25–30 nm for the sonochemical method and 15–20 nm for the hydrothermal method. YVO4:Eu3+ nanoparticles in the case of the sonochemical method had a better crystalline structure and stronger emissivity at 618 nm. The Eu3+ ions’ average lifetime in YVO4:Eu3+ at 618 nm emission under 275 nm excitation were at 0.955 ms for the sonochemical method and 0.723 ms for the hydrothermal method. The security ink for inkjet devices contained YVO4:Eu3+ nanoparticles, the binding agent as polyethylene oxide or ethyl cellulose and other necessary solvents. The device used for security label printing was an inkjet printer with an electrohydrodynamic printing technique (EHD). In the 3D optical profilometer results, the width of the printed line was ~97–167 µm and the thickness at ~9.1–9.6 µm. The printed security label obtained a well-marked shape, with a size at 1.98 × 1.98 mm.

Tuning the properties of regenerated cellulose: Effects of polarity and water solubility of the coagulation medium

In this study, the effect of different alcohols and esters as a coagulation medium in the regeneration of cellulose dissolved in an aqueous LiOH-urea-based solvent was thoroughly investigated using various methods such as solid state NMR, X-ray diffraction, water contact angle, oxygen gas permeability, mechanical testing, and scanning electron microscopy. It was observed that several material properties of the regenerated cellulose films follow trends that correlate to the degree of cellulose II crystallinity, which is determined to be set by the miscibility of the coagulant medium (nonsolvent) and the aqueous alkali cellulose solvent rather than the nonsolvents’ polarity. This article provides an insight, thus creating a possibility to carefully tune and control the cellulose material properties when tailor-made for different applications. [Display omitted] [Display omitted]

Thermodynamic and Transport Properties of Tetrabutylphosphonium Hydroxide and Tetrabutylphosphonium Chloride–Water Mixtures via Molecular Dynamics Simulation

Thermodynamic, structural, and transport properties of tetrabutylphosphonium hydroxide (TBPH) and tetrabutylphosphonium chloride (TBPCl)–water mixtures have been investigated using all-atom molecular dynamics simulations in response to recent experimental work showing the TBPH–water mixtures capability as a cellulose solvent. Multiple transitional states exist for the water—ionic liquid (IL) mixture between 70 and 100 mol% water, which corresponds to a significant increase in water hydrogen bonds. The key transitional region, from 85 to 92.5 mol% water, which coincides with the mixture’s maximum cellulose solubility, reveals small and distinct water veins with cage structures formed by the TBP+ ions, while the hydroxide and chloride ions have moved away from the P atom of TBP+ and are strongly hydrogen bonded to the water. The maximum cellulose solubility of the TBPH–water solution at approximately 91.1 mol% water, appears correlated with the destruction of the TBP’s interlocking structure in the simulations, allowing the formation of water veins and channeling structures throughout the system, as well as changing from a subdiffusive to a near-normal diffusive regime, increasing the probability of the IL’s interaction with the cellulose polymer. A comparison is made between the solution properties of TBPH and TBPCl with those of alkylimidazolium-based ILs, for which water appears to act as anti-solvent rather than a co-solvent.