Glucose Solvation by the Ionic Liquid 1,3-Dimethylimidazolium Chloride: A Simulation Study

Effect of different ionic liquids and organic solvents on the structural and physicochemical properties of cellulose-protein complexes extracted from Se-enriched peanut leaves

Abundant cellulose and insoluble protein were contained in the Se-enriched peanut leaf residue, a by-product from leaf protein extraction. Ionic liquids (ILs) were used to extract the cellulose-protein complexes (CPCs) from Se-enriched peanut leaf residue. The effects of various ILs as extractants and organic solvents as regenerant on the physicochemical properties of CPCs were compared. The results showed that the yield of CPCs and recovery yield of [AMIM]Cl (1-allyl-3-methylimidazole chloride) were better than those of [BMIM]Cl (1-butyl-3-methylimidazolium chloride). Simultaneously, it could be seen from the infrared absorption peaks and secondary structure fitting results that [BMIM]Cl seemed stronger than [AMIM]Cl in destroying the secondary structure of CPCs. Scanning electron microscope (SEM) showed that the CPCs extracted by [BMIM]Cl were lamellate with holes on the surface, and the CPCs extracted by [AMIM]Cl were rough, almost without holes on the surface. Furthermore, the transmittance and tensile strength of the film which contained BA-CPC ([BMIM]Cl as extractant and acetonitrile as regenerant) film were better than those contained AA-CPC ([AMIM]Cl as extractant and acetonitrile as regenerant) film, which might be mainly because the types of ILs and regenerants affect the particle size of CPCs, thereby influencing the mechanical properties of the film.

Toward the Proactive Design of Sustainable Chemicals: Ionic Liquids as a Prime Example

The tailorable and often unique properties of ionic liquids (ILs) drive their implementation into a broad variety of seminal technologies. The modular design of ILs allows in this context a proactive selection of structures that favor environmental sustainability─ideally without compromising their technological performance. To achieve this objective, the whole life cycle must be taken into account and various aspects considered simultaneously. In this review, we discuss how the structural design of ILs affects their environmental impacts throughout all stages of their life cycles and scrutinize the available data in order to point out knowledge gaps that need further research activities. The design of more sustainable ILs starts with the selection of the most beneficial precursors and synthesis routes, takes their technical properties and application specific performance into due account, and considers its environmental fate particularly in terms of their (eco)toxicity, biotic and abiotic degradability, mobility, and bioaccumulation potential. Special emphasis is placed on reported structure-activity relationships and suggested mechanisms on a molecular level that might rationalize the empirically found design criteria.

Optimization of OPEFB lignocellulose transformation process through ionic liquid [TEA][HSO4] based pretreatment

Research on the transformation of Oil Palm Empty Fruit Bunches (OPEFB) through pretreatment process using ionic liquid triethylammonium hydrogen sulphate (IL [TEA][HSO₄]) was completed. The stages of the transformation process carried out were the synthesis of IL with the one-spot method, optimization of IL composition and pretreatment temperature, and IL recovery. The success of the IL synthesis stage was analyzed by FTIR, H-NMR and TGA. Based on the results obtained, it showed that IL [TEA][HSO₄] was successfully synthesized. This was indicated by the presence of IR absorption at 1/λ = 2814.97 cm^-1, 1401.07 cm^-1, 1233.30 cm^-1 and 847.92 cm^-1 which were functional groups for NH, CH₃, CN and SO₂, respectively. These results were supported by H-NMR data at δ (ppm) = 1.217-1.236 (N-CH₂-CH₃), 3.005-3.023 (-H), 3.427-3.445 (N-H⁺) and 3.867 (N⁺H₃). The TGA results showed that the melting point and decomposition temperature of the IL were 49 °C and 274.3 °C, respectively. Based on pretreatment optimization, it showed that the best IL composition for cellulose production was 85 wt%. Meanwhile, temperature optimization showed that the best temperature was 120 °C. In these two optimum conditions, the cellulose content was obtained at 45.84 wt%. Testing of IL [TEA][HSO₄] recovery performance for reuse has shown promising results. During the pretreatment process, IL [TEA][HSO₄] recovery effectively increased the cellulose content of OPEFB to 29.13 wt% and decreased the lignin content to 32.57%. The success of the recovery process is indicated by the increasing density properties of IL [TEA][HSO₄]. This increase occurs when using a temperature of 80-100 °C. The overall conditions obtained from this work suggest that IL [TEA][HSO₄] was effective during the transformation process of OPEFB into cellulose. This shows the potential of IL [TEA][HSO₄] in the future in the renewable energy sector.

Glucose in dry and moist ionic liquid: vibrational circular dichroism, IR, and possible mechanisms

Ionic liquids and their mixtures with water show remarkable features in cellulose processing. For this reason, understanding the behavior of carbohydrates in ionic liquids is important. In the present study, we investigated three d-glucose isomers (α, β and open-chain) in 1-ethyl-3-methylimidazolium acetate in the presence and absence of water, through ab initio molecular dynamics simulations. In the complex hydrogen bonding network of these mixtures, the most interesting observation is that upon water addition every hydrogen bond elongates, except the glucose-glucose hydrogen bond for the open-chain and the α-form which shortens, clearly showing the beginning of the crystallization process. The ring glucose rearranges from on-top to in-plane and the open form changes from a coiled to a more linear arrangement when adding water which explains the contradiction that the center of mass distances of the glucose molecules with other glucose molecules grow while the hydrogen bonds shorten. The appearance of coiled open forms indicates that the previously suggested isomerization between these forms is possible and might play a role in the solubility of the related carbohydrates. The calculated IR and VCD spectra reveal insight into the intermolecular interactions, with good to excellent agreements with experimental spectra. Investigating the role of the cation, distances between the acidic carbon atom of the cation and the glucose carbon atom where ring closure and opening occurs are found, which are way shorter than dispersion-like interactions between aliphatic hydrocarbons.

Insight into Cellulose Dissolution with the Tetrabutylphosphonium Chloride-Water Mixture using Molecular Dynamics Simulations

All-atom molecular dynamics simulations are utilized to determine the properties and mechanisms of cellulose dissolution using the ionic liquid tetrabutylphosphonium chloride (TBPCl)–water mixture, from 63.1 to 100 mol % water. The hydrogen bonding between small and large cellulose bundles with 18 and 88 strands, respectively, is compared for all concentrations. The Cl, TBP, and water enable cellulose dissolution by working together to form a cooperative mechanism capable of separating the cellulose strands from the bundle. The chloride anions initiate the cellulose breakup, and water assists in delaying the cellulose strand reformation; the TBP cation then more permanently separates the cellulose strands from the bundle. The chloride anion provides a net negative pairwise energy, offsetting the net positive pairwise energy of the peeling cellulose strand. The TBP–peeling cellulose strand has a uniquely favorable and potentially net negative pairwise energy contribution in the TBPCl–water solution, which may partially explain why it is capable of dissolving cellulose at moderate temperatures and high water concentrations. The cellulose dissolution declines rapidly with increasing water concentration as hydrogen bond lifetimes of the chloride–cellulose hydroxyl hydrogens fall below the cellulose’s largest intra-strand hydrogen bonding lifetime.

Methyl Ketones from Municipal Solid Waste Blends by One-Pot Ionic-Liquid Pretreatment, Saccharification, and Fermentation

The conversion of municipal solid waste (MSW) and lignocellulosic biomass blends to methyl ketones (MKs) was investigated by using bioderived ionic liquid (bionic liquid)-based hydrolysates followed by fermentation with an engineered Escherichia coli strain. The hydrolysates were produced by a one-pot process using six types of MSW-biomass blends, choline-based bionic liquids, and commercial enzymes. Based on the sugar yields, one blend (corn stover/MSW=95:5, w/w) and two bionic liquids {cholinium lysinate ([Ch][Lys]) and cholinium aspartate ([Ch]₂ [Asp])} were selected for scale-up studies. Maximum yields of 82.3 % glucose and 54.4 % xylose were obtained from the selected blend in the scale-up studies (6 L), which was comparable with 83.6 % glucose and 52.8 % xylose obtained at a smaller scale (0.2 L). Comparable or higher yields of medium-chain (C₁₁ -C₁₇ ) MKs were achieved by using the MSW-biomass blend-derived hydrolysates, relative to the sugar controls (glucose and xylose) with similar sugar feeding concentrations. Up to 1145 mg L^-1 of MKs was produced by using MSW-biomass-derived hydrolysates, and the MK titer decreased to 300 mg L^-1 when the bionic-liquid concentration in the hydrolysate increased from 1 to 2 %, indicative of bionic-liquid inhibition. Technoeconomic analysis was conducted to investigate the economic potential of using the selected MSW-biomass blend as a feedstock to produce MKs.

Effect of ionic liquids 1-octyl-3-methyl imidazolium bromide or 1-octyl-3-methyl imidazolium chloride on thermophysical properties and taste behavior of sucrose in aqueous media at different temperatures: Volumetric, compressibility and viscometric properties

The thermophysical properties and taste behavior of sucrose in aqueous ionic liquids {1-octyl-3-methyl imidazolium bromide and 1-octyl-3-methyl imidazolium chloride} solutions have been studied via volumetric, compressibility and viscometric properties at T = (288.15, 298.15, 308.15 and 318.15) K. The positive values of transfer volume and transfer partial molar isentropic compression indicated predominance of ionic-hydrophilic interactions in these systems. The calculated hydration number for sucrose demonstrated that dehydration of sucrose occurs in presence of both studied ionic liquids. Further, the effect of studied ionic liquids on the taste behaviour of sucrose has been discussed from ASV and ASIC parameters. Furthermore, interaction volume, V_int, and cavity volume, V_cav, have been computed from scaled particle theory (SPT).

Solvation structure of poly-m-phenyleneisophthalamide (PMIA) in ionic liquids

Polyaramids are a class of high-performance polymers, known for their high mechanical strength and chemical and thermal stability. Their ability to create a network of intermolecular hydrogen bonds causes them to be very poorly soluble in conventional solvents. Hazardous solvents such as N-methylpyrrolidone (NMP) and dimethylacetamide (DMA), in combination with an inorganic salt such as CaCl2, are currently used for the synthesis and processing of polyaramids. Ionic liquids are proposed as suitable greener alternatives. In this work, we studied the solubility and dissolution mechanism of the meta-oriented polyaramid poly-m-phenyleneisophthalamide (PMIA) in a wide range of ionic liquids. It was found that, similarly to cellulose, PMIA could be dissolved readily and in large amounts in ionic liquids containing a strongly coordinating anion (such as chloride, acetate and dialkylphosphate) and an imidazolium cation. Hydrogen bonding between the anion and the amide NH of PMIA is the main solvent-solute interaction. An odd-even effect in solubility occurred when altering the length of the side chains on the imidazolium cation. Furthermore, it was found that the presence of hydrogen bond donating CH moieties on the cation is a necessary condition for dissolution. The exact role of these hydrogen bond donors was investigated by FTIR and 13C NMR spectroscopy. It was found that there is no significant interaction between the hydrogen atoms of the imidazolium ring and the amide carbonyl groups. Rather, the hydrogen bond donors are needed to stabilize the solvation shell around PMIA through alternating cation-anion interactions.

A Hierarchical Model To Understand the Processing of Polysaccharides/Protein-Based Films in Ionic Liquids

In recent years, biomaterials from abundant and renewable sources have shown potential in medicine and materials science alike. In this study, we combine theoretical modeling, molecular dynamics simulations, and several experimental techniques to understand the regeneration of cellulose/silk-, chitin/silk-, and chitosan/silk-based biocomposites after dissolution in ionic liquid and regeneration in water. We propose a novel theoretical model that correlates the composite's microscopic structure to its bulk properties. We rely on modeling non-cross-linked biopolymers that present layer-like structures such as β-sheets and we successfully predict structural, thermal, and mechanical properties of a mixture of these biomolecules. Our model and experiments show that the solubility of the pure substance in the chosen solvent can be used to modulate the amount of crystallinity of the biopolymer blend, as measured by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). Thermogravimetric analysis (TGA) shows that the decomposition temperature of the blended biocomposites compared to their pure counterparts is reduced in accordance with our theoretical predictions. The morphology of the material is further characterized through scanning electron microscopy (SEM) and shows differently exposed surface area depending on the blend. Finally, differential scanning calorimetry (DSC) is performed to characterize the residual water content in the material, essential for explaining the regeneration process in water. As a final test of the model, we compare our model's prediction of the Young's modulus with existing data in the literature. The model correctly reproduces experimental trends observed in the Young's modulus due to varying the concentration of silk in the biopolymer blend.

Towards a molecular understanding of cellulose dissolution in ionic liquids: anion/cation effect, synergistic mechanism and physicochemical aspects

Cellulose is one of the most abundant bio-renewable materials on the earth and its conversion to biofuels provides an appealing way to satisfy the increasing global energy demand. However, before carrying out the process of enzymolysis to glucose or polysaccharides, cellulose needs to be pretreated to overcome its recalcitrance. In recent years, a variety of ionic liquids (ILs) have been found to be effective solvents for cellulose, providing a new, feasible pretreatment strategy. A lot of experimental and computational studies have been carried out to investigate the dissolution mechanism. However, many details are not fully understood, which highlights the necessity to overview the current knowledge of cellulose dissolution and identify the research trend in the future. This perspective summarizes the mechanistic studies and microscopic insights of cellulose dissolution in ILs. Recent investigations of the synergistic effect of cations/anions and the distinctive structural changes of cellulose microfibril in ILs are also reviewed. Besides, understanding the factors controlling the dissolution process, such as the structure of anions/cations, viscosity of ILs, pretreatment temperature, heating rate, etc., has been discussed from a structural and physicochemical viewpoint. At the end, the existing problems are discussed and future prospects are given. We hope this article would be helpful for deeper understanding of the cellulose dissolution process in ILs and the rational design of more efficient and recyclable ILs.

Statistical Mechanics-Based Theoretical Investigation of Solvation Effects on Glucose Anomer Preferences

The importance of solvation effects on the stability of glucose anomers has been studied by the combination of quantum mechanics and statistical mechanics, namely, the reference interaction site model self-consistent field spatial electron density distribution. The preferences of α- and β-glucose in H₂O are well reproduced with the obtained ratio of 35:65 for α- and β-glucose, respectively. Indirect interactions and bulk effects, described by the Onsager model, are relatively small compared to the direct solute-solvent interactions, especially in [DMIM]Cl and dimethyl sulfoxide. From the decomposition of solvation free energy and solvation structures, it can be seen that the interactions with the solvent molecules greatly contribute to the anomer preferences.

Is Solute Rotation in an Ionic Liquid Influenced by the Addition of Glucose?

Fluorescence anisotropy measurements and molecular dynamics (MD) simulations have been performed to understand the specific interactions of two structurally similar nondipolar solutes, 2,5-dimethyl-1,4-dioxo-3,6-diphenylpyrrolo[3,4-c]pyrrole (DMDPP) and 1,4-dioxo-3,6-diphenylpyrrolo[3,4-c]pyrrole (DPP), with neat 1-butyl-3-methylimidazolium dicyanamide ([BMIM][N(CN)₂]) and also in the presence of glucose. It has been observed that the measured reorientation times of DMDPP in neat [BMIM][N(CN)₂] follow the predictions of the Stokes-Einstein-Debye hydrodynamic theory with slip boundary condition. Addition of glucose (0.075 and 0.15 mole fraction) has no bearing on the rotational diffusion of the solute apart from the viscosity related effects. In contrast, the reorientation times of DPP in neat [BMIM][N(CN)₂] obey stick boundary condition as the hydrogen bond donating solute experiences specific interactions with the dicyanamide anion. No influence of the additive can be noticed on the rotational diffusion of DPP at 0.075 mole fraction of glucose. However, at 0.15 mole fraction of glucose, the reorientation times of the solute at a given viscosity and temperature decrease by 15-40% compared to those obtained in the neat ionic liquid. MD simulations indicate that each DPP molecule hydrogen bonds with two dicyanamide anions in neat ionic liquid. The simulations also reveal that, at 0.15 mole fraction of glucose, the concentration of anions hydrogen bonded to glucose increases significantly; therefore, the percentage of solute molecules that can form hydrogen bonds with two dicyanamide anions decreases to 84, which leads to faster rotation of DPP.

Aqueous ionic liquids and their effects on protein structures: an overview on recent theoretical and experimental results

Ionic liquids (ILs) are used in a variety of technological and biological applications. Recent experimental and simulation results reveal the influence of aqueous ionic liquids on the stability of protein and enzyme structures. Depending on different parameters like the concentration and the ion composition, one can observe distinct stabilization or denaturation mechanisms for various ILs. In this review, we summarize the main findings and discuss the implications with regard to molecular theories of solutions and specific ion effects. A preferential binding model is introduced in order to discuss protein-IL effects from a statistical mechanics perspective. The value of the preferential binding coefficient determines the strength of the ion influence and indicates a shift of the chemical equilibrium either to the native or the denatured state of the protein. We highlight the role of water in order to explain the self-association behavior of the IL species and discuss recent experimental and simulation results in the light of the observed binding effects.

Proteins in Ionic Liquids: Current Status of Experiments and Simulations

In the last two decades, while searching for interesting applications of ionic liquids as potent solvents, their solvation properties and their general impact on biomolecules, and in particular on proteins, gained interest. It turned out that ionic liquids are excellent solvents for protein refolding and crystallization. Biomolecules showed increased solubilities and stabilities, both operational and thermal, in ionic liquids, which also seem to prevent self-aggregation during solubilization. Biomolecules can be immobilized, e.g. in highly viscous ionic liquids, for particular biochemical processes and can be designed to some extent by the proper choice of the ionic liquid cations and anions, which can be characterized by the Hofmeister series.

Ionic liquids and deep eutectic solvents for lignocellulosic biomass fractionation

State of the art overview of the fractionation of lignocellulosic biomass with ionic liquids and deep eutectic solvents.

The properties of residual water molecules in ionic liquids: a comparison between direct and inverse Kirkwood–Buff approaches

Atomistic molecular dynamics simulations of aqueous ionic liquid mixtures were performed in order to compare the resulting Kirkwood–Buff integrals with experimental data and the corresponding integrals derived by an inverse Kirkwood–Buff approach.

Solvation Structure of Uracil in Ionic Liquids

The local solvation environment of uracil dissolved in the ionic liquid 1-ethyl-3-methylimidazolium acetate has been studied using neutron diffraction techniques. At solvent:solute (ionic liquid:uracil) ratios of 3:1 and 2:1, little perturbation of the ion-ion correlations compared to those of the neat ionic liquid are observed. We find that solvation of the uracil is driven predominantly by the acetate anion of the solvent. While short distance correlations exist between uracil and the imidazolium cation, the geometry of these contacts suggest that they cannot be considered as hydrogen bonds, in contrast to other studies by Araújo et al. (J. M. Araújo, A. B. Pereiro, J. N. Canongia-Lopes, L. P. Rebelo, I. M. Marrucho, J. Phys. Chem. B 2013, 117, 4109-4120). Nevertheless, this combination of interactions of the solute with both the cation and anion components of the solvents helps explain the high solubility of the nucleobase in this media. In addition, favourable uracil-uracil contacts are observed, of similar magnitude to those between cation and uracil, and are also likely to aid dissolution.

Solubility and solvation of monosaccharides in ionic liquids

Herein, solubility experimental data for six monosaccharides, viz.d-(+)-glucose, d-(+)-mannose, d-(-)-fructose, d-(+)-galactose, d-(+)-xylose and l-(+)-arabinose, in four ionic liquids (ILs), at temperatures ranging from 288.2 to 348.2 K, were obtained aimed at gathering a better understanding of their solvation ability and molecular-level mechanisms which rule the dissolution process. To ascertain the chemical features that enhance the solubility of monosaccharides, ILs composed of dialkylimidazolium or tetraalkylphosphonium cations combined with the dicyanamide, dimethylphosphate or chloride anions were investigated. It was found that the ranking of the solubility of monosaccharides depends on the IL; yet, d-(+)-xylose is always the most soluble while d-(-)-fructose is the least soluble monosaccharide. The results obtained show that both the IL cation and the anion play a major role in the solubility of monosaccharides. Finally, from the determination of the respective thermodynamic properties of solution, it was found that enthalpic contributions are dominant in the solubilization process. However, the observed differences in the solubilities of monosaccharides in 1-butyl-3-methylimidazolium dicyanamide are ruled by a change in the entropy of solution.

Why are some cyano-based ionic liquids better glucose solvents than water?

Among different classes of ionic liquids (ILs), those with cyano-based anions have been of special interest due to their low viscosity and enhanced solvation ability for a large variety of compounds. Experimental results from this work reveal that the solubility of glucose in some of these ionic liquids may be higher than in water - a well-known solvent with enhanced capacity to dissolve mono- and disaccharides. This raises questions on the ability of cyano groups to establish strong hydrogen bonds with carbohydrates and on the optimal number of cyano groups at the IL anion that maximizes the solubility of glucose. In addition to experimental solubility data, these questions are addressed in this study using a combination of density functional theory (DFT) and molecular dynamics (MD) simulations. Through the calculation of the number of hydrogen bonds, coordination numbers, energies of interaction and radial and spatial distribution functions, it was possible to explain the experimental results and to show that the ability to favorably interact with glucose is driven by the polarity of each IL anion, with the optimal anion being dicyanamide.

Enhanced tunability afforded by aqueous biphasic systems formed by fluorinated ionic liquids and carbohydrates

This work unveils the formation of novel aqueous biphasic systems (ABS) formed by perfluoroalkylsulfonate-based ionic liquids (ILs) and a large number of carbohydrates (monosaccharides, disaccharides and polyols) aiming at establishing more benign alternatives to the salts commonly used. The respective ternary phase diagrams were determined at 298 K. The aptitude of the carbohydrates to induce phase separation closely follows their hydration capability, while the length of the IL cation/anion fluorinated chain also plays a crucial role. Finally, these systems were investigated as liquid-liquid extraction strategies for four food dyes. Single-step extraction efficiencies for the carbohydrate-rich phase up to 94% were obtained. Remarkably and contrarily to the most investigated IL-salt ABS, most dyes preferentially migrate for the most hydrophilic and biocompatible carbohydrate-rich phase - an outstanding advantage when envisaging the products recovery and further use. On the other hand, more hydrophobic dyes preferentially partition to the IL-rich phase, disclosing therefore these novel systems as highly amenable to be tuned by the proper choice of the phase-forming components.

Effect of cation structure on the oxygen solubility and diffusivity in a range of bis{(trifluoromethyl)sulfonyl}imide anion based ionic liquids for lithium–air battery electrolytes

Electrochemical measurements of oxygen mobility and solubility in a series of related [TFSI]⁻-based ILs relating to cation structure and physical properties of the ILs.

Revision of the GROMOS 56A6(CARBO) force field: Improving the description of ring-conformational equilibria in hexopyranose-based carbohydrates chains

This article describes a revised version 56A6(CARBO_R) of the GROMOS 56A6(CARBO) force field for hexopyranose-based carbohydrates. The simulated properties of unfunctionalized hexopyranoses are unaltered with respect to 56A6CARBO . In the context of both O1 -alkylated hexopyranoses and oligosaccharides, the revision stabilizes the regular (4) C1 chair for α-anomers, with the opposite effect for β-anomers. As a result, spurious ring inversions observed in α(1→4)-linked chains when using the original 56A6(CARBO) force field are alleviated. The (4) C1 chair is now the most stable conformation for all d-hexopyranose residues, irrespective of the linkage type and anomery, and of the position of the residue along the chain. The methylation of a d-hexopyranose leads to a systematic shift in the ring-inversion free energy ((4) C1 to (1) C4 ) by 7-8 kJ mol(-1), positive for the α-anomers and negative for the β-anomers, which is qualitatively compatible with the expected enhancement of the anomeric effect upon methylation at O1. The ring-inversion free energies for residues within chains are typically smaller in magnitude compared to those of the monomers, and correlate rather poorly with the latter. This suggests that the crowding of ring substituents upon chain formation alters the ring flexibility in a nonsystematic fashion. In general, the description of carbohydrate chains afforded by 56A6(CARBO_R) suggests a significant extent of ring flexibility, i.e., small but often non-negligible equilibrium populations of inverted chairs, and challenges the "textbook" picture of conformationally locked carbohydrate rings.

Dissolving process of a cellulose bunch in ionic liquids: a molecular dynamics study

In recent years, a variety of ionic liquids (ILs) were found to be capable of dissolving cellulose and mechanistic studies were also reported. However, there is still a lack of detailed information at the molecular level. Here, long time molecular dynamics simulations of cellulose bunch in 1-ethyl-3-methylimidazolium acetate (EmimAc), 1-ethyl-3-methylimidazolium chloride (EmimCl), 1-butyl-3-methylimidazolium chloride (BmimCl) and water were performed to analyze the inherent interaction and dissolving mechanism. Complete dissolution of the cellulose bunch was observed in EmimAc, while little change took place in EmimCl and BmimCl, and nothing significant happened in water. The deconstruction of the hydrogen bond (H-bond) network in cellulose was found and analyzed quantitatively. The synergistic effect of cations and anions was revealed by analyzing the whole dissolving process. Initially, cations bind to the side face of the cellulose bunch and anions insert into the cellulose strands to form H-bonds with hydroxyl groups. Then cations start to intercalate into cellulose chains due to their strong electrostatic interaction with the entered anions. The H-bonds formed by Cl(-) cannot effectively separate the cellulose chain and that is the reason why EmimCl and BmimCl dissolve cellulose more slowly. These findings deepen people's understanding on how ILs dissolve cellulose and would be helpful for designing new efficient ILs to dissolve cellulose.

Multifilament cellulose/chitin blend yarn spun from ionic liquids

Cellulose and chitin, both biopolymers, decompose before reaching their melting points. Therefore, processing these unmodified biopolymers into multifilament yarns is limited to solution chemistry. Especially the processing of chitin into fibers is rather limited to distinctive, often toxic or badly removable solvents often accompanied by chemical de-functionalization to chitosan (degree of acetylation, DA, <50%). This work proposes a novel method for the preparation of cellulose/chitin blend fibers using ionic liquids (ILs) as gentle, removable, recyclable and non-deacetylating solvents. Chitin and cellulose are dissolved in ethylmethylimidazolium propionate ([C2mim](+)[OPr](-)) and the obtained one-pot spinning dope is used to produce multifilament fibers by a continuous wet-spinning process. Both the rheology of the corresponding spinning dopes and the structural and physical properties of the obtained fibers have been determined for different biopolymer ratios. With respect to medical or hygienic application, the cellulose/chitin blend fiber show enhanced water retention capacity compared to pure cellulose fibers.