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Cellulose extracted from printed paper wastes were selectively depolymerized under controlled conditions into cello-oligomers of controllable chain lengths via dissolution in an ionic liquid, 1-allyl-3-methylimidazolium chloride (AMIMCl), and in the presence of an acid catalyst, Amberlyst 15DRY. The depolymerization process was optimized against reaction temperature, concentration of acid catalyst, and reaction time. Despite rapid initial depolymerization process, the rate of cellulose depolymerization slowed down gradually upon prolonged reaction time, with 75.0 wt% yield of regenerated cello-oligomers (mean Viscosimetric Degree of Polymerization value of 81) obtained after 40 min. The depolymerization of cellulose fibers at 80 °C appeared to proceed via a second-order kinetic reaction with respect to the catalyst concentration of 0.23 mmol H3O(+). As such, the cellulose depolymerization process could afford some degree of control on the degree of polymerization or chain lengths of cello-oligomers formed., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Cellulose-based aerogel (CBA) was prepared from waste newspaper (WNP) without any pretreatment using 1-allyl-3-methyimidazolium chloride (AmImCl) as a solvent via regeneration and an environmentally friendly freeze-drying method. After being treated with trimethylchlorosilane (TMCS) via a simple thermal chemical vapor deposition process, the resulting CBAs were rendered both hydrophobic and oleophilic. Successful silanization on the surface of the porous CBA was verified by a variety of techniques including scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), and water contact angle (WCA) measurements. As a result, the silane-coated, interconnected CBAs not only exhibited good absorption performance for oils (e.g., waste engine oil), but also showed absorption capacity for organic solvents such as chloroform (with a representative weight gain ranging from 11 to 22 times of their own dry weight), making them diversified absorbents for potential applications including sewage purification., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Waste newspapers, composed of cellulose (>60wt%), lignin (∼15wt%), hemicellulose (∼10wt%) and other additives, are one kind of low-cost, easily collected and abundant resources. In order to get value-added products from this waste, in this work an attempt was made to directly convert waste newspapers into cellulose-based films by employing an ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl) as a solvent. Most of the organic substances in this waste were dissolved quickly in AmimCl under mild conditions, and then coagulated and dried. Although containing lignin, hemicellulose and inorganic additives, the regenerated cellulose-based films were smooth, compact and semi-transparent, and exhibited good mechanical properties. If the newspaper/AmimCl solution was filtered to remove undissolved inorganic substances, the regenerated films became transparent and had a tensile strength of 80MPa. Thus, this work provides a new, simple and highly efficient way to achieve a high-valued utilization of waste newspapers for packaging and wrapping., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Highlights • Combination of SAILs and nanofibrillated kenaf cellulose was used for exfoliation. • SAILs shows enhanced graphene-compatibility over commercial surfactant. • BMIM-DBS provide highest dispersion stability and exfoliation efficiency. • Electrical conductivities of GCP related to the SAILs structure and concentration. Abstract A facile electrochemical exfoliation method was established to efficiently prepare conductive paper containing reduced graphene oxide (RGO) with the help of single chain anionic surfactant ionic liquids (SAILs). The surfactant ionic liquids are synthesized from conventional organic surfactant anions and a 1-butyl-3-methyl-imidazolium cation. For the first time the combination of SAILs and cellulose was used to directly exfoliate graphite. The ionic liquid 1-butyl-3-methyl-imidazolium dodecylbenzenesulfonate (BMIM-DBS) was shown to have notable affinity for graphene, demonstrating improved electrical properties of the conductive cellulose paper. The presence of BMIM-DBS in the system promotes five orders of magnitude enhancement of the paper electrical conductivity (2.71 × 10−5 S cm−1) compared to the native cellulose (1.97 × 10−10 S cm−1). A thorough investigation using electron microscopy and Raman spectroscopy highlights the presence of uniform graphene incorporated inside the matrices. Studies into aqueous aggregation behavior using small-angle neutron scattering (SANS) point to the ability of this compound to act as a bridge between graphene and cellulose, and is responsible for the enhanced exfoliation level and stabilization of the resulting dispersion. The simple and feasible process for producing conductive paper described here is attractive for the possibility of scaling-up this technique for mass production of conductive composites containing graphene or other layered materials. [ABSTRACT FROM AUTHOR]

Conductive hydrogels have been widely used in wearable electronics due to their flexible, conductive and adjustable properties. With ever-growing demand for sustainable and biocompatible sensing materials, biopolymer-based hydrogels have drawn significant attention. Among them, starch-based hydrogels have a great potential for wearable electronics. However, it remains challenging to develop multifunctional starch-based hydrogels with high stretchability, good conductivity, excellent durability and high sensitivity. Herein, amylopectin and ionic liquid were introduced into a hydrophobic association hydrogel to endow it with versatility. Benefiting from the synergistic effect of amylopectin and ionic liquid, the hydrogel exhibited excellent mechanical properties (the elongation of 2540 % with a Young's modulus of 12.0 kPa and a toughness of 1.3 MJ·m -3 ), self-recovery, good electrical properties (a conductivity of 1.8 S·m -1 and electrical self-healing), high sensitivity (gauge factor up to 26.85) and excellent durability (5850 cycles). The above properties of the hydrogel were closely correlated to its internal structure from hydrophobic association, H-bonding and electrostatic interaction, and can be regulated by changing the component contents. A wireless wearable sensor based on the hydrogel realized accurate and stable monitoring of joint motions and expression changes. This work demonstrates a kind of promising biopolymer-based materials as candidates for high-performance flexible wearable sensors., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The plasticizing and antibacterial effects of ionic liquids (ILs) in the preparation of tapioca starch-IL films were studied for the first time. 1-Ethyl-3-methylimidazolium acetate ([Emim][OAc]) caused complete disruption of starch crystallites during thermal compression, while some crystallites remained after the plasticization of starch with choline acetate ([Ch][OAc]). Compared to native tapioca starch (NTS), the plasticization of acetylated tapioca starch (ATS) and cross-linked tapioca (CTS) was slightly promoted and inhibited, respectively. Starch-[Emim][OAc] films exhibited higher hydrophobicity and mechanical properties but lower antibacterial activity than starch-[Ch][OAc] films. CTS-[Ch][OAc] films presented higher mechanical strength and antibacterial activity than NTS-[Ch][OAc] and ATS-[Ch][OAc] films. From this study, we conclude that ILs can be used in the preparation of antibacterial starch films to play the roles of plasticization and antibacterial activity. The antibacterial activity of starch films depends on types of ILs and their interactions with starch during film preparation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier Ltd.)

Synthetic efforts are being made to produce electrical conductive films based on a combination of cellulose matrix with conducting polymers. Improved mechanical properties and processability of the conducting polymers can be attained by promoting this combination, allowing the production of electrical conductive membranes or sheet of paper-like forms that have many technological uses. Cellulose films containing different amounts of polyaniline combined to silver nanoparticles were prepared in homogenous conditions by the dissolution of microcrystalline cellulose in 1-butyl-3-methylimidazolium chloride ionic liquid, followed by the mixing with dispersion of silver nanoparticles and polyaniline also prepared in an ionic liquid. Films with high electrical conductivities (23–34 S·cm−1) and homogeneous distribution of the constituents were produced. The high conductivity was promoted by the presence of polyaniline in its most conductivity state with the silver nanoparticles affording the electrical contact among these chains creating a conductive network spread throughout the insulating cellulose matrix. [ABSTRACT FROM AUTHOR]

Separation of water and oil from water-in-oil (W/O) emulsion before transportation and refining is very important and critical. Ionic liquids (ILs) and their derivatives have recently attracted much attention as efficient chemical agents for breaking emulsions. So, here, a series of microcrystalline cellulose (MCC) grafted with imidazolium-based ionic liquids (IM-ILs) were synthesized, named as MCC@IM-ILs, and evaluated as eco-friendly surface-active agents for the separation of water from the crude oil. Structure of the synthesized compounds was confirmed by different characterization techniques. Dehydration efficiency percent (DE%) of the synthesized demulsifiers was measured and compared with each other. Synthesized MCC@IM-ILs showed an acceptable DE% to demulsify three kinds of W/O emulsions with different water content after 5 min. Concentration, alkyl chain length, and counter-anion of the synthesized MCC@IM-ILs play a key role in separating water from crude oil. Demulsifier with C10 alkyl chain length showed better DE% than the corresponding demulsifier with C6 alkyl chain length in the W/O (30:70 v/v) emulsion. Also, demulsifier with Br counter anion showed lower DE% than the corresponding BF 4 ion-exchanged compound with higher hydrophilicity. Synthesized demulsifiers immobilized on ILs have significant advantages compared to unsupported ILs due to the use of green and economical cellulosic substrate., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Imidazolium-based ionic liquids are important solvents for the processing of natural cellulose. Little is known about their use in synthesizing cellulose via bottom-up polymerization of β-1,4-d-glucosyl chains in solution. Here, we analyzed cellodextrin phosphorylase-catalyzed synthesis of cello-oligosaccharides, and the subsequent spontaneous self-assembly of the chains, in the presence of cellulose-dissolving ionic liquid, 1,3-dimethylimidazolium dimethyl phosphate ([Dmim]DMP) or 1-ethyl-3-methylimidazolium acetate ([Emim]OAc). The average chain length dropped from ~7.4 in buffer to ~6.4 in ionic liquid (30 vol%). The synthetic cellulose exhibited allomorph II crystal structure and showed nanosheet morphology of 4-5 nm thickness and several μm length. Its suspensions were hydrogels with viscoelastic properties dependent on solvent conditions used. Reactions in 10 vol% [Dmim]DMP or [Emim]OAc gave a hydrogel with elastic modulus of ~13 kPa and loss factor of ~0.18. Collectively, interactions of the ionic liquid with enzyme and cello-oligosaccharides delimit the polymerization and tune the assembly into cellulose networks., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Attempt to broaden the application of ionic liquids (ILs) towards synthesis and modification of polysaccharides as adsorbent have gained more attention in the last two decades. This development has been aimed mainly on the use of environmentally friendly chemicals for improving the physical, chemical and adsorptive features of polysaccharides-based adsorbents for various applications. In the build-up to improve the polysaccharides-based adsorbents' characteristics through modification, ILs have been utilised by researcher either as a solvent medium or as a component of the modified natural polymer-based adsorbent. Findings revealed that the imidazolium-based ILs have been the prominent ILs type utilised for polysaccharides modification owing to its ease of preparation and its solvation capability for most commonly applied natural polymer. This review uniquely summarised the trend in the use of imidazolium based ILs to improve the adsorptive features of various polysaccharides adsorbents for adsorption and solid-phase extraction applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

As a green solvent, alkylimidazolium salt has attracted much attention due to high antibacterial activity and excellent biocompatibility. In this work, 1-allyl-3-alkylimidazolium bromide ionic liquids (AIMB) were synthesized in a closed system. Using carboxymethyl cellulose (CMC) and starch (SR) as carriers, 1-allyl-3-dodecylimidazolium bromide ionic liquid (AIMC12)/CMC/SR (AIMCS) films were prepared via solution casting method. The AIMC12 exhibited the highest antibacterial activity. Under the optimized ratio of CMC to SR, the AIMCS-1-1 film showed effective antibacterial properties for E. coli and S. aureus with the inhibition zone of 3.50 cm and 3.02 cm, respectively. In addition, the tensile strength and elongation at break of AIMCS-1-1 reached to 4.5 MPa and 111.6 %, and its Young's modulus was 1.4 GPa. Therefore, as-prepared AIMB will be expected to replace traditional antibacterial agents in antibacterial applications, and as-prepared AIMCS films as the green packaging materials have potential application in antibacterial packaging., Competing Interests: Declaration of interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier Ltd.)

One-step conversion of cellulose to HMF (5-hydroxymethylfurfural) has been achieved by using metal chlorides (CrCl 3 , CuCl 2 , SnCl 4 , WCl 6 ) in [BMIM]Cl. The effects of temperature, reaction time, amount of catalysts, and the purity of [BMIM]Cl on the performance have been studied and discussed in detail. More than 63% yield of HMF and 80% yield of TRS (total reducing sugar) were obtained in [BMIM]Cl with CrCl 3 at 120 °C under atmospheric pressure. Filter paper and cotton were also used as a source for cellulose degradation to HMF, but only a moderate yield of HMF was obtained (40% for filter paper and 12% for cotton). The reutilization of this system was examined and the reaction mechanism was also discussed. [ABSTRACT FROM AUTHOR]

Cellulose conversion into 5-hydroxymethylfurfural (5-HMF) is difficult because of the strong hydrogen bonding existed in cellulose chains. Brønsted/Lewis (B/L) biacidic functionalized ionic liquids (ILs) have great advantages in acid-catalyzed tandem reactions, but the catalytic effect of ILs differs considerably depending on B/L acid ratios. Therefore, this work designed a series of reactions with different proportions of biacidic ILs for the preparation of 5-HMF from cellulose. The tandem reaction is often performed in the presence of a solvent, and the activity of the catalyst is also affected by the solvent. Therefore, in this work, the solvation model density(SMD) model was introduced into the quantum chemical calculation method for molecular design to predict the catalytic effect and explore the catalytic mechanism. The calculation results and experiments jointly showed that [(HSO 3 -P) 2 im]Cl·ZnCl 2 had the highest efficiency, with a 5-HMF yield of 65.66%. This study facilitates the directional optimization design of the catalyst., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

In this paper, a reinforced Biomass Gel Artificial Muscle (BGAM) was fabricated by natural polysaccharide of Sodium Alginate (SA) doped with an Ionic Liquid (IL) of 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIm][BF 4 ]). Micro-nano regulation effect and reinforcement mechanism of IL doping content on electromechanical response performance of BGAM were researched during a single cycle and repeated cycles. Then, a green fabrication process and a set of valid test methods for BGAM were proposed in detail. The experimental results showed that when IL doping content was 4 mL, the BGAM achieved optimal modification, with a porosity of 70.47%, where it internally adopted the porous polymer structure of ion channels. Additionally, specific capacitance of BGAM attained a maximum value of 126.98 mF/g, and the inner resistance and elastic modulus reached minimum values of 2.018 Ω and 1.871 MPa, separately. Thus, the optimal working life and output-force density values, namely, 1720 s and 13.072 mN/g, respectively, were also determined for the BGAM., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

The paper presents the results of a study on the preparation of cellulose-based composite fibres (CEL) with graphene oxide addition (GO). Composite fibres (GO/CEL) were prepared via the wet spinning method from CEL solutions in 1-ethyl-3-methylimidazolium acetate (EMIMAc) that contained a nano-addition of GO dispersion in N,N-dimethylformamide (DMF). The GO contents of the composite fibres were 0, 0.21, 0.50, 0.98, and 1.97 % w w. The fibres were coagulated in two solvents: distilled water and methanol. The results demonstrated that the amount of GO additive and the type of coagulant significantly impact the physicochemical, mechanical and structural properties of the CEL and GO/CEL fibres. The use of distilled water in a coagulation bath causes a degree of crystallinity of 31.0-40.8 % (WAXS) and a shift in the thermal decomposition temperature (by approximately 19 °C) towards higher temperatures (TGA). The results demonstrate improvements in the mechanical properties of the GO/CEL fibres, which were at the level of 9.43-14.18 cN/tex. In addition, the GO/CEL fibres exhibit satisfactory GO dispersion throughout their volume., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

An alternative transesterification with vinyl laurate (VL) was applied for chemical modification of hemicelluloses (HC) to prepare functional packaging films. Successful transesterification was confirmed by FT-IR and NMR. Semitransparent laurated HC (LHs) films were prepared by solvent casting method. SEM indicated the ordered honeycomb-patterned surface and the dense cross section of LHs films. The LHs films exhibited excellent hydrophobicity with water contact angle about 120° and the enhanced mechanical properties with tensile strength and elongation at break as 33.94 ± 3.09 MPa and 22.41 ± 2.87%, respectively. The water vapor permeability (WVP) and oxygen permeability (OP) values of LHs films ranged from 1.59 ± 0.07 to 2.23 ± 0.11 (10 -10 ·g/m·s·Pa) and 1.21 ± 0.04 to 4.24 ± 0.30 (cm 3 ·μm/m 2 ·d·kPa), respectively. Moreover, the films had acceptable antioxidant activity. In terms of these properties, the shelf life of green chilies could be largely extended to 15 days after packing with LHs films., (Copyright © 2019. Published by Elsevier Ltd.)

To overcome the natural recalcitrance of cellulose for glucose production in aqueous media catalyzed by enzyme, in this study, a dissolution pretreatment strategy was developed by using in situ formed CO 2 -based reversible ionic compounds (RICs)/DMSO mixed organic electrolytes under mild conditions. The influences of the constitution of RICs, CO 2 pressure, dissolution pretreatment time on the physic-chemical structure of cellulose were investigated systematically by FTIR, XRD, SEM, AFM towards in-depth understanding of the correlations between the pretreatment conditions, micro-scale structure and enzymatic saccharification of cellulose. The results showed that the tetramethyl guanidine (TMG) based RICs solvent system [TMGH] 2 + [O 2 COCH 2 CH 2 OCO 2 ] 2- /DMSO (X RICs  = 0.1, X RICs : the mole fraction of the formed RICs in the mixture) presented the best performance, which was evidenced by 100% glucose yield after the dissolution-regeneration pretreatment strategy under mild conditions (T = 60 °C, Pco 2  = 2.0 MPa, t = 2 h). Furthermore, the solvent system have good recyclability and usability., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

With the serious "white pollution" resulted from the non-biodegradable plastic films, considerable attention has been directed toward the development of renewable and biodegradable cellulose-based film materials as substitutes of petroleum-derived materials. In this study, environmentally friendly cellulose films were successfully prepared using different celluloses (pine, cotton, bamboo, MCC) as raw materials and ionic liquid 1-ethyl-3-methylimidazolium acetate as a solvent. The SEM and AFM indicated that all cellulose films displayed a homogeneous and smooth surface. In addition, the FT-IR and XRD analysis showed the transition from cellulose I to II was occurred after the dissolution and regeneration process. Furthermore, the cellulose films prepared by cotton linters and pine possessed the most excellent thermal stability and mechanical properties, which were suggested by the highest onset temperature (285°C) and tensile stress (120 MPa), respectively. Their excellent properties of regenerated cellulose films are promising for applications in food packaging and medical materials., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

This paper presents a novel environmentally friendly production of chitosan-crosslinked oxycellulose films by using ionic liquids (AmimCl and SmimHSO4). The effect of reaction parameters on chitosan contents and mechanical properties of chitosan-crosslinked oxycellulose films was also investigated. The results revealed that appropriate SmimHSO4 dosage and reaction time were 5% and 2h respectively. FTIR analysis of chitosan-crosslinked oxycellulose film suggested that the chitosan was crosslinked with oxycellulose through the reaction between the amino groups in chitosan and the aldehyde groups in oxycellulose, and the results of XPS analysis further confirmed the reaction between both polysaccharides. SEM images suggested that the developed chitosan-crosslinked oxycellulose films had a smooth and compact structure, and a highly inhibitory effect against the bacteria of Escherichia coli and Staphylococcus aureus. The developed materials and technologies could be further formulated for the production of various antimicrobial and biomedical products or water treatment membranes., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

The present study investigated the impact of regeneration process on the crystalline structure and enzymatic hydrolysis behaviors of microcrystalline cellulose (MCC) regenerated from ionic liquid 1-butyl-3-methylimidazolium chloride. The crystalline structures of these regenerated samples were analyzed by X-ray diffraction. Results suggested that almost amorphous cellulose was obtained by regenerating MCC in acetone (DRC-a), while partial cellulose II structure could be found in these regenerated samples from water and ethanol. Additionally, the enzymatic hydrolysis behaviors of MCC and its regenerated samples were comparatively studied. Results showed that above 90% of cellulose could be converted into glucose within 4h for DRC-a and regenerated cellulose without drying (WRC-w) as compared to that of MCC (9.7%). Therefore, the regeneration process could significantly influence the crystallinity and digestibility of cellulose., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

In the present paper, we test the suitability of ChCl/urea (DES-U) and ChCl/glycerol (DES-G) eutectic mixtures, each one prepared at 1:2 molar ratio, for the production of agar films. A three-step process is proposed: pre-solubilization of polymer in DES followed by compression-molding and subsequent drying. The mechanical properties, water resistance and microstructure of the films were evaluated at different polymer concentrations (i.e. 2-6%, w/w). DES-U showed by far, the best film forming ability. Agreeing with the diffusion and SEM data, films with the best mechanical properties were found at the lowest and highest agar concentrations (tensile strengths of 24.2-42 MPa and elongations of 15.4-38.9%). The water sorption and contact angle studies suggested increased hydrophilicity for the film containing the lowest concentration of agar. The use of choline chloride based ionic liquid analogues as solvent and plasticizer might be a promising tool for the development of new non-aqueous materials based on seaweed polysaccharides., (Published by Elsevier Ltd.)

A facile method is reported to prepare Maillard reaction products (MRPs) from chitosan and xylan in co-solvent ionic liquid. UV absorbance and fluorescence changes were regarded as indicators of the occurrence of Maillard reaction. FT-IR, NMR, XRD and TG were used to investigate the structure of chitosan-xylan conjugate. The results revealed that when chitosan reacted with xylan in ionic liquid, the hydrogen bonds in chitosan were destroyed, the facts resulted in the formation of chitosan-xylan MRPs. Moreover, when the mass ratio of chitosan to xylan was 1:1, the Maillard reaction proceeded easily. In addition, relatively high antioxidant property was also noted for the chitosan-xylan conjugate with mass ratio 1:1. So the obtained chitosan-xylan MRP is a promising antioxidant agent for food industry., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

In this study two imidazole-based ionic liquids (ILs), namely 1-butyl-3-methyl-1-imidazolium chloride ([BMIM]Cl) and 1,3-methyl imidazolium dimethyl sulfate ([DiMIM][MeSO4]), were used to dissolve ball-milled poplar wood (PW), chemi-mechanical pulp (CMP), and cotton linter (CEL). A set of comparative experiments was carried out, and physical and mechanical properties of the composite films from three different raw materials were determined by means of optical transparency (OT), scanning electron microscopy (SEM), water absorption (WA), thickness swelling (TS), water vapor permeability (WVP), and tensile strength (σb). The overall evaluation indicates the inability of [DiMIM][MeSO4] in complete dissolution of lignocellulosic materials, and sample treatment with this solvent did not lead to water soluble degradation products. However, dissolution trials using [BMIM]Cl were able to dissolve all used lignocellulosic materials by destroying inter and intramolecular hydrogen bonds between lignocelluloses. The OT, WA, TS, and σb of regenerated CEL films were much higher than those of CMP and PW composites. In addition, CEL film showed the lowest WVP compared to WF and CMP composite films. This work demonstrated a promising route for the preparation of biodegradable green cellulose composite films., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

The purposes of this article are to synthesize the biomass-based hybrid nanocomposites using green method in green solvent and evaluate its biological activity. In this paper, microwave-assisted ionic liquid method is applied to the preparation of cellulose/CaCO(3) hybrid nanocomposites in the alkali extraction cellulose using CaCl(2) and Na(2)CO(3) as starting reactants. The ionic liquid acts as the excellent solvent for absorbing microwave and the dissolution of cellulose, and the synthesis of cellulose/CaCO(3) nanocomposites. The influences of reaction parameters such as the cellulose concentration and the types of solvent on the products were investigated. The increasing cellulose concentration favored the growth of CaCO(3). The morphologies of CaCO(3) changed from polyhedral to cube to particle with increasing cellulose concentration. Moreover, the solvents had an effect on the shape and dispersion of CaCO(3). Cytotoxicity experiments demonstrated that the cellulose/CaCO(3) nanocomposites had good biocompatibility and could be a candidate for the biomedical applications., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Graphical abstract Highlights • Methylcellulose (MC)/imidazolium ionic liquids (ILs) mixtures were prepared. • The ILs increase the viscosity and change the rheological behavior of MC solutions. • The ILs display transition from the salt-out to the salt-in on the gelation temperature. • The presence of ILs (conventional or bolaform) decrease the gel strength. • The interaction MC/ILs depends on hydrophobicity and type of ILs (mono or dicationic). Abstract Thermoreversible hydrogels are suitable in food products in order to improve texture and in biomedical applications as drug delivery vehicles. The properties of hydrogels affect their performance in those applications. In this paper, it is presented the effect of mono- (C n MIMBr) and dicationic (C n (MIM) 2 Br 2) imidazolium ionic liquids (ILs) on the viscosity and gelation of methylcellulose (MC) using rheology, micro differential scanning calorimetric and small angle X-ray scattering (SAXS) techniques. Results show that the ILs affect the pattern of the sol-gel transition and display transition from the salt-out to the salt-in on the gelation temperature, decrease the gel strength and increase viscosity of MC solutions. This behavior can be explained by hydrophobic interaction between the ILs and the MC, which depends of the alkyl chain length of the ILs, type of ILs (conventional or bolaform) and the range of ILs concentration. In general, the presence of ILs decrease the MC gel strength, while dicationic ILs hampers their association on MC in comparison with monocationic ones. The findings highlight the role of ILs on gelation of MC opening possibilities for the design of new complex formulations. [ABSTRACT FROM AUTHOR]

Highlights • Hydrogen bonds of cellulose might be cracked by two ways at different temperatures. • The O(3)H–O(5) bonds disruption could promote the dissolution at lower temperature. • The (O(2)H–O(6)) bonds might be responsible for dissolution at higher temperature. • Higher dissolving temperature might be a way to avoid cellulose degradation in ILs. Abstract Ionic liquids have been powerful solvents for cellulose. Mechanistic investigations of the dissolution processes have been extensively studied. In this paper, an experimental study has revealed that temperature also comes into play in cellulose dissolution. The supramolecular stuctrure of cellulose has been measured by X-ray diffraction, Fourier transform infrared spectroscopy, Solid-state CP/MAS 13C NMR, X-ray photoelectron spectroscopy and Gel permeation chromatography analysis, and the effects of temperature on hydrogen bonds of cellulose in ILs were investigated. These results indicated that hydrogen bonds of cellulose might be cracked by different ways at different temperature: The disruption of intramolecular hydrogen bonds (O(3) H-O (5)) could promote the dissolution process at lower temperature. And the disruption of intramolecular hydrogen bonds (O(2) H-O (6)) might be responsible for cellulose dissolution at higher temperature. It was suggested that higher dissolving temperature might be a way to avoid cellulose degradation with a high cellulose yield. [ABSTRACT FROM AUTHOR]

Presently flexibly transparent film or nanopaper from all cellulose was mostly fabricated by assembling cellulose nanofibers disintegrated from macroscopic wood fibers which mostly suffers from potential environmental toxicity or high cost. In this work, we firstly reported an all-cellulose transparent film fabricated by a novel microwave-assisted ionic liquids technology (MILT). The use of MILT for treating the original all-cellulose paper brings nearly 2.6 fold-increases in optical transmission, and 2.0 fold-increases in tensile property compared to those without microwave assistance. More importantly, by contrast with the partial dissolution of cellulose in typical DMAC/LiCl, ILs, NaOH/urea, the MILT is extremely time-saved with responding to the highest increase in mechanical property because the high efficient surface dissolution and welding bind individual sheets together under a micro environment. [ABSTRACT FROM AUTHOR]

Hemicellulose lean pulps are a raw material source for numerous high value products. We have previously presented the IONCELL-P(ulp) process, a hemicellulose extraction method, based on a binary mixture of ionic liquid and water. The IONCELL-P process does not suffer from yield losses or polymer degradation and retains the Cellulose I crystalline form. In this paper, a selection of cellulose dissolving ionic liquids is tested, in order to compare their applicability in the process. We demonstrate that the extraction selectivity towards low molar mass polymers is related to the anion’s ability to accept hydrogen bonds (Kamlet-Taft β-value), if divided by the water molar fraction of the solvent system. Pulp consistency, solvent system viscosity and pH are investigated in order to identify the factors affecting the extraction efficiency. The results show that all the tested ionic liquid-water mixtures were able to dissolve hemicelluloses, but there were differences in their efficiency, selectivity and the ability to process high pulp consistencies. [ABSTRACT FROM AUTHOR]

It’s challenging to dissolve natural cellulose in most solvents due to its highly ordered crystalline structure. In this paper, we developed an efficient cellulose dissolution system which incorporates solid acid (SA) with 1-butyl-3-methylimidizolium chloride (BmimCl). The results showed that addition of solid acid both Amberlyst ® 15 and Cs x H 3−x PW 12 O 40 could significantly enhance cellulose dissolution in BmimCl, which attributed to the synergistic action of free hydrogen proton from SA and chloride anion in BmimCl on hydroxyl groups of cellulose, and DMF as co-solvent also could facilitate cellulose dissolution in SA/BmimCl. In contrast to BmimCl system, the SA/BmimCl system for cellulose dissolution achieves better efficiency at mild treatment conditions and facile recovery of solvents. In addition, characterization of the regenerated celluloses showed that SA/BmimCl is a non-derivatizing solvent for cellulose, which helps achieve complete dissolution on crystalline cellulose. Attributed to its low cost and environmentally friendliness for biomass processing, SA/BmimCl systems is a promising and effective solvent system. [ABSTRACT FROM AUTHOR]

In this paper, we demonstrated that acidic ionic liquids (ILs) can be used as “quasi-homogeneous” catalysts for the efficient acetylation of cellulose. Unlike existing techniques that use large amount of ILs as solvent to dissolve and acetylate cellulose, a small amount of acidic ILs was used as catalyst in this study to overcome the low efficiency associated with relatively high viscosity and costs of ILs during homogeneous acetylation. Fully substituted cellulose acetate with a conversion of 88.8% was obtained by using only 9 mol% IL 1-vinyl-3-(3-sulfopropyl) imidazolium hydrogen sulfate as catalyst, which is much higher than that of common commercialized solid acid catalysts. The degree of substitution and solubility of the obtained cellulose acetate can be facilely controlled by varying the concentration of ILs and reaction time. The dual function of swelling and catalyzing of acidic ILs for the acetylation of cellulose is responsible for the excellent catalytic performance. [ABSTRACT FROM AUTHOR]

This paper reports the plasticisation effect of the ionic liquid, 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]), as compared with the traditionally used plasticiser, glycerol, on the characteristics of starch-based films. For minimising the additional effect of processing, a simple compression moulding process (which involves minimal shear) was used for preparation of starch-based films. The results show that [Emim][OAc] was favourable for plasticisation, i.e., disruption of starch granules (by scanning electron microscopy), and could result in a more amorphous structure in the starch-based materials (by X-ray diffraction and dynamic mechanical analysis). 13C CP/MAS and SPE/MAS NMR spectroscopy revealed that not only was the crystallinity reduced by [Emim][OAc], but also the amorphous starch present was plasticised to a more mobile form as indicated by the appearance of amorphous starch in the SPE/MAS spectrum. Mechanical results illustrate that, when either glycerol or [Emim][OAc] was used, a higher plasticiser content could contribute to higher flexibility. In spite of the accelerated thermal degradation of starch by [Emim][OAc] as shown by thermogravimetric analysis, the biodegradation study revealed the antimicrobial effect of [Emim][OAc] on the starch-based materials. Considering the high-amylose starch used here which is typically difficult to gelatinise in a traditional plasticiser (water and/or glycerol), [Emim][OAc] is demonstrated to be a promising plasticiser for starch to develop "green" flexible antimicrobial materials for novel applications. [ABSTRACT FROM AUTHOR]

Abstract: The purposes of this article are to synthesize the biomass-based hybrid nanocomposites using green method in green solvent and evaluate its biological activity. In this paper, microwave-assisted ionic liquid method is applied to the preparation of cellulose/CaCO3 hybrid nanocomposites in the alkali extraction cellulose using CaCl2 and Na2CO3 as starting reactants. The ionic liquid acts as the excellent solvent for absorbing microwave and the dissolution of cellulose, and the synthesis of cellulose/CaCO3 nanocomposites. The influences of reaction parameters such as the cellulose concentration and the types of solvent on the products were investigated. The increasing cellulose concentration favored the growth of CaCO3. The morphologies of CaCO3 changed from polyhedral to cube to particle with increasing cellulose concentration. Moreover, the solvents had an effect on the shape and dispersion of CaCO3. Cytotoxicity experiments demonstrated that the cellulose/CaCO3 nanocomposites had good biocompatibility and could be a candidate for the biomedical applications. [Copyright &y& Elsevier]

Abstract: Cellulose resource has got much attention as a promising replacement of fossil fuel. The hydrolysis of cellulose is the key step to chemical product and liquid transportation fuel. In this paper a serials of chloride, acetate, and formate based ionic liquids were used as solvents to dissolve cellulose. The cellulose regenerated from ILs was characterized by FTIR and X-ray powder diffraction. From the characterization and analysis, it was found that the original close and compact structure has changed a lot. After enzymatic hydrolysis, different kinds of ionic liquids (ILs) have different yields of the reducing sugar (TRS). They are 100%, 90.72%, and 88.92% from 1-butyl-3-methylimidazolium chloride ([BMIM]Cl), 1-ethyl-3-methylimidazolium acetate ([EMIM][OAc]), 1-butyl-3-methylimidazolium formate ([BMIM][HCOO]) respectively after enzymatic hydrolysis at 50°C for 5h. The results indicated that the yields and the hydrolysis rates were improved apparently after ILs pretreatment comparing with the untreated substrates. [Copyright &y& Elsevier]

Abstract: Chemical modification is the most important means to obtain novel biopolymers and biomaterials from the abundant biomacromolecules. In this paper, hemicellulosic succinate, which is very important biomacromolecule for the preparation of functional materials, was homogeneously prepared in 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) ionic liquid. The influence of reaction conditions used in this work on the degree of substitution (DS) was investigated, and the chemical structure and the thermal stability of hemicellulosic succinate were characterized by FT-IR and 13C NMR spectroscopies as well as thermogravimetry. A high DS of up to 1.80 could be achieved at short time scale in [BMIM]Cl ionic liquid without any catalysts, which is probably due to the excellent dissolving capacity and catalytic effect of ionic liquid. These results indicate that ionic liquids open up totally new opportunities for chemically functionalization of hemicelluloses. [Copyright &y& Elsevier]

Abstract: This paper reports a homogeneous modification of microcrystalline cellulose (MCC) in ionic liquids via radiation-induced grafting. Thermosensitive poly (N-isopropylacrylamide) (PNIPAAm) was successfully grafted onto MCC in 1-butyl-3-methylimidazolium chloride ([Bmim]Cl) ionic liquid using γ-ray irradiation technique at room temperature. The grafting yield (GY) increased with dose up to 40kGy, while decreased slightly with dose rate from 22 to 102Gy/min. The results of TGA indicated that cellulose grafted PNIPAAm (cellulose-g-PNIPAAm) had higher thermal stability than that of ungrafted regenerated cellulose (reg-cellulose). The crystalline structure of original MCC was largely destroyed during the dissolution process according to the XRD profiles, and grafting PNIPAAm onto cellulose further decreased the intensity of crystallinity. SEM showed that reg-cellulose and cellulose-g-PNIPAAm films displayed dense and homogeneous morphology. Moreover, the resulting cellulose-g-PNIPAAm exhibited obvious thermal sensitivity with a lower critical solution temperature around 35°C, which was observed from the swelling behavior in water at different temperatures. [Copyright &y& Elsevier]

Abstract: This paper reports the preparation of a cellulose–starch composite gel from an ionic liquid solution. The gel was obtained by keeping the homogeneous mixture of cellulose (10% w/w) and starch (5% w/w) in 1-butyl-3-methylimidazolium chloride (BMIMCl) for several days at room temperature and characterized by elemental analysis, X-ray diffraction, and thermal gravimetric analysis. Furthermore, the production of the fibrous material composed of cellulose and starch by reconstitution from the homogeneous mixture (10% w/w each) in BMIMCl is demonstrated. [Copyright &y& Elsevier]

Abstract: The objective of this paper is to investigate if the swelling and dissolution mechanisms found for aqueous solvents are valid for non-aqueous ones. Three different ionic liquids were used and the swelling and dissolution mechanisms were investigated by optical methods. Native and enzymatically treated cellulose fibres (cotton and wood fibres) are dipped into three ionic liquids (1-N-butyl-3-methylimidazolium chloride ([C4mim]+Cl−)/DMSO, allylmethylimidazolium bromide ([Amim]+Br−) and butenylmethylimidazolium bromide ([Bmim]+Br−). ([C4mim]+Cl−)/DMSO shows a swelling of cellulose by ballooning and then dissolution. ([Amim]+Br−) and ([Bmim]+Br−) show a homogeneous swelling but no dissolution. The swelling and dissolution mechanisms of cellulose in ionic liquids are similar to those observed in aqueous solvents. It indicates that the swelling and dissolution mechanisms are entirely due to the way cellulose fibres are structured, not depending on the type of solvent. The quality of the solvent is giving the type of mechanism. [Copyright &y& Elsevier]

• Vibration amplitude of ultrasonication enhances the NCC thermal properties. • No derivational reactions occurred during hydrolysis and ultrasonication. • Ultrasonication treatment improves the NCC crystallinity and yield. Catalytic ionic liquid hydrolysis of cellulosic material have been considered as a green and highly efficient dissolution process. However, application of a pre-treatment process, i.e; ultrasonication enhances the hydrolysis of cellulose in ionic liquid by providing mechanical force. In this paper, we describe the impact of both chemical and mechanical approaches to produce nanocrytalline cellulose (NCC) with anticipated particle size, and crystallinity with improved yields. The ultrasonication treatment was evaluated in terms of treatment time and vibration amplitude. It was found that the lowest ultrasonication time (5 min) produced the NCC of highest crystallinity (73 %), but the lowest yield (84 %). In contrary, the highest ultrasonication vibration amplitude at 90 % produced NCC with highest crystallinity value (67 %) as well as yields (90 %). It concludes that ultrasonic pre-treatment improves the hydrolysis process of cellulose in ionic liquid with increasing yield and crystallinity of NCC. [ABSTRACT FROM AUTHOR]

• Flexible cellulose films were formed via gelation from its solution in ionic liquid. • The films showed good tensile strength and elongation by simple drying after gelation. • Processing conditions altered the degree of crystallinity of cellulose in the films. • The films were thermally transformed to the other shapes. It is still challenging to melt-process cellulose. In this paper, we proposed a method for the formation of thermally processable flexible cellulose films via gelation from its solution in ionic liquid (1-butyl-3-methylimidazolium chloride; BMIMCl). Cotton, as a source of cellulose, was dissolved (5 wt%) in BMIMCl and subsequently placed in different amounts of water. The obtained ion gels were dried at 60 °C for 24 h; during drying process, water was removed while BMIMCl was retained. It was found that the amount of retained BMIMCl had a critical role in determining the mechanical properties of the films. It was suspected that the processing conditions altered the degree of crystallinity of cellulose in the films as evidenced by X-ray diffraction measurement. The ionic liquid, i.e., BMIMCl induced the plasticity into the films, so that thermal processability to different shapes became possible. [ABSTRACT FROM AUTHOR]