Ionic liquids and their interaction with cellulose (original) (raw)
Potential applications of natural origin polymer-based systems in soft tissue regeneration
Critical Reviews in Biotechnology, 2010
Despite the many advances in tissue engineering approaches, scientists still face significant challenges in trying to repair and replace soft tissues. Nature-inspired routes involving the creation of polymer-based systems of natural origins constitute an interesting alternative route to produce novel materials. The interest in these materials comes from the possibility of constructing multi-component systems that can be manipulated by composition allowing one to mimic the tissue environment required for the cellular regeneration of soft tissues. For this purpose, factors such as the design, choice, and compatibility of the polymers are considered to be key factors for successful strategies in soft tissue regeneration. More recently, polysaccharide-protein based systems have being increasingly studied and proposed for the treatment of soft tissues. The characteristics, properties, and compatibility of the resulting materials investigated in the last 10 years, as well as commercially available matrices or those currently under investigation are the subject matter of this review.
Suberin isolation from cork using ionic liquids: characterisation of ensuing products
New Journal of Chemistry, 2012
Cholinium alkanoates, a class of benign ionic liquids, were demonstrated to efficiently extract suberin domains from cork. A detailed characterisation of the extracted material has yet to be attained. In the present study the significance of the alkylic chain length of the anion and the ionic liquid's basicity was investigated. The results obtained emphasise cholinium hexanoate's selection; it proved to be a straightforward process, also ensuring the recyclability and reusability of the ionic liquid. The extracted suberinic material has been thoroughly characterised for the first time by ATR-FTIR, NMR, GC-MS and thermal analyses. Data showed that it is mainly composed of oligomeric or polymeric aliphatic esterified structures, resulting from suberin partial cleavage. More than 40 wt% of the extracted suberinic material was found to be cross-linked. Even though, the composing monomeric units were similar to those usually identified in suberin samples obtained by the conventional extraction processes. These data pave the way for advanced studies of suberin monomers/oligomers as building-blocks for the development of novel biopolymers and biomaterials.
The use of ionic liquids in the processing of chitosan/silk hydrogels for biomedical applications
Green Chemistry, 2012
Natural polymers are adequate renewable resources for the processability of well-defined architectures for several applications. Combinations of polysaccharides and proteins may mimic the naturally occurring environment of certain tissues. The main goal of this work renders the application of green chemistry principles, namely the use of ionic liquids (ILs) and biorenewable sources, such as chitosan (CHT) and silk fibroin (SF), to process new hydrogel-based constructs. Although the solubilization of both materials in ILs has been studied individually, this work reports, for the first time, the role of ILs as solvent, for the production of hydrogels from blends of chitosan and silk fibroin (CSF). These systems offer the advantage of being homogeneous and presenting easy and short dissolution time of both biomacromolecules. Moreover, the use of chitosan obtained from αand β-chitin allowed the production of blended hydrogels with distinct physical-chemical properties. In vitro assays demonstrated that these hydrogels supported the adhesion and growth of primary human dermal fibroblasts. Taken these properties together, the CSF hydrogels might be promising biomaterials to be explored for skin tissue engineering approaches.
A critical review of all-cellulose composites
Journal of Materials Science, 2012
Cellulose is a fascinating biopolymer of almost inexhaustible quantity. While being a lightweight material, it shows outstanding values of strength and stiffness when present in its native form. Unsurprisingly, cellulose fibre has been rigorously investigated as a reinforcing component in biocomposites. In recent years, however, a new class of monocomponent composites based on cellulosic materials, so-called all-cellulose composites (ACCs) have emerged. These new materials promise to overcome the critical problem of fibre-matrix adhesion in biocomposites by using chemically similar or identical cellulosic materials for both matrix and reinforcement. A number of papers scattered throughout the polymer, composites and biomolecular science literature have been published describing non-derivatized and derivatized ACCs. Exceptional mechanical properties of ACCs have been reported that easily exceed those of traditional biocomposites. Several different processing routes have been applied to the manufacture of ACCs using a broad range of different solvent systems and raw materials. This article aims to provide a comprehensive review of the background chemistry and various cellulosic sources investigated, various synthesis routes, phase transformations of the cellulose, and mechanical, viscoelastic and optical properties of ACCs. The current difficulties and challenges of ACCs are clearly outlined, pointing the way forward for further exploration of this interesting subcategory of biocomposites.
Ionic Liquids for the Production of Man-Made Cellulosic Fibers: Opportunities and Challenges
Advances in Polymer Science, 2015
The constant worldwide increase in consumption of goods will also affect the textile market. The demand for cellulosic textile fibers is predicted to increase at such a rate that by 2030 there will be a considerable shortage, estimated at~15 million tons annually. Currently, man-made cellulosic fibers are produced commercially via the viscose and Lyocell™ processes. Ionic liquids (ILs) have been proposed as alternative solvents to circumvent certain problems associated with these existing processes. We first provide a comprehensive review of the progress in fiber spinning based on ILs over the last decade. A summary of the reports on the preparation of pure cellulosic and composite fibers is complemented by an overview of the rheological characteristics and thermal degradation of cellulose-IL solutions. In the second part, we present a non-imidazolium-based ionic liquid, 1,5-diazabicyclo[4.3.0]non-5-enium acetate, as an excellent solvent for cellulose fiber spinning. The use of moderate process temperatures in this process avoids the otherwise extensive cellulose degradation. The structural and morphological properties of the spun fibers are described, as determined by WAXS, birefringence, and SEM measurements. Mechanical properties are also reported.
A facile method for the recovery of ionic liquid and lignin from biomass pretreatment
Green Chemistry, 2011
In the biochemical conversion of lignocellulosic biomass to biofuels, the process of pretreatment is currently one of the most difficult and expensive operations. The use of ionic liquids (ILs) in biomass pretreatment has received considerable attention recently because of their effectiveness at decreasing biomass recalcitrance to subsequent enzymatic hydrolysis. In addition, ILs have the potential for decreasing the need for corrosive or toxic chemicals and associated waste streams that can be generated by other pretreatment methods that utilize acids and/or bases. In this article, we address two significant challenges to the realization of a practical IL pretreatment process. First, we describe a mixture containing specific proportions of a ketone and an alcohol that precipitates cellulose and lignocellulosic biomass from solutions of the IL 1-ethyl-3-methylimidazolium acetate without the formation of intermediate gel phases. Second, an IL recovery process is described that removes lignin and most residual IL solutes and that minimizes energy and solvent use. These two techniques are demonstrated by the pretreatment of 100 g of corn stover with the recovery of 89% of the initial IL and separate corn stover fractions rich in glucans, xylans, lignin, and non-polar substances. These results highlight one potential approach towards the realization of a scalable ionic liquid pretreatment process technology that enables ionic liquid recovery and reuse.
RSC Advances, 2013
Based on shikimic acidthe starting material for the important anti-influenza drug Tamiflu (oseltamivir phosphate)we present that the dissolution properties of ionic liquids can lead to better access to the valuable ingredient embedded in the biopolymer. Different imidazolium-based ionic liquids were investigated, and the extraction yield of shikimic acid was correlated with their hydrogen-bonding properties via polarizable MD simulations, indicating that the hydrogen bonding of the IL anion to shikimic acid is responsible for a good extraction performance. A scale-up strategy for the isolation of shikimic acid with the ionic liquid 1-ethyl-3-methylimidazolium acetate ([C 2 mim]OAc) was developed based on ion-exchange resins, thus allowing isolation of shikimic acid in up to 10 wt% yield with complete recovery of the ionic liquid. ; Tel: +43 1 4277 52711 † Electronic supplementary information (ESI) available: Calibration curves for the determination of shikimic acid, representative HPLC chromatograms and NMR spectra of recovered ionic liquid and of isolated shikimic acid. See
Molecules, 2012
Micro/mesoporous chromium, aluminium-containing silicates of the type TUD-1 (Al-TUD-1, Cr-TUD-1, CrAl-TUD-1) and zeolite BEA, Cr-BEA, and related composites BEA/TUD-1 and Cr-BEA/TUD-1, were prepared, characterised, and tested as solid acids coupled with the ionic liquid (IL) 1-butyl-3-methylimidazolium chloride ([bmim]Cl) as solvent, in the transformation of D-glucose into 5-(hydroxymethyl)-2-furaldehyde (Hmf), at 120 °C. The chromium-containing catalytic systems lead to considerably higher Hmf yields in comparison to the related systems without chromium. The IL is a favourable solvent for this target reaction (in terms of Hmf yields reached) compared to water or dimethylsulfoxide. A detailed study on the stabilities of the nanoporous solid acids in the IL medium is presented.
Fast and highly efficient acetylation of xylans in ionic liquid systems
Cellulose, 2013
In this study high molecular weight pure rye arabinoxylan and spruce arabinoglucuronoxylan were acetylated in ionic liquid (IL) systems. Two different ILs were used in our study. In both IL, using optimized procedures, it was possible to achieve acetylation within 5 min. The first system involved direct dissolution into 1-ethyl-3-methylimidazolium dimethylphosphate ([emim][Me 2 PO 4 ]), followed by addition of acetyl chloride/pyridine (AcCl/Pyr) and additional chloroform (CHCl 3 ), as co-solvent. The other system involved direct dissolution into the novel protic IL 1,5-diazabicyclo[4.3.0]non-5-enium acetate ([DBNH][OAc]), followed by acetic anhydride/1,5diazabicyclo[4.3.0]non-5-ene (Ac 2 O/DBN) and no cosolvent added. The full acetyl substitution of the xylans was confirmed by FT IR and 1 H NMR. The acetylated xylans maintained a high molecular weight, which was confirmed by gel permeation chromatography. The products were soluble in CHCl 3 and dimethyl carbonate, which is considered as a 'green' reagent or solvent. This allowed for the casting of the materials into clear transparent films, opening opportunity for further processing and evaluation of these materials.
From plant to drug: ionic liquids for the reactive dissolution of biomass
Green Chemistry, 2011
We present an ionic liquid (IL) strategy for the reactive dissolution of star anise seeds using different Brønsted-acidic ionic liquids as the solvent and reaction media towards the isolation of important pharmaceutical intermediates; this procedure provides a single-step, higher yielding and environmentally benign strategy towards the synthesis of the anti-influenza drug Tamiflu TM .
Ionic liquids and fragrances – direct isolation of orange essential oil
Green Chemistry, 2011
We present the dissolution of fresh fragrance biomass in ionic liquids for the isolation of essential oils and compare direct distillation with solvent extraction. Orange essential oil was distilled from orange peels dissolved in ionic liquid media, thus allowing a simple, efficient, and mild isolation of fragrance and flavor components with complete recovery of the ionic liquid.
Journal of Biomedical Materials Research Part A, 2013
We have successfully developed a simple and totally recyclable method to synthesize novel, biocompatible, and biodegradable composite materials from cellulose (CEL) and chitosan (CS). In this method, [BMIm þ Cl À ], an ionic liquid (IL), was used as a green solvent to dissolve and synthesize the [CELþCS] composites. Since, the IL can be removed from the composites by washing them with water, and recovered by distilling the washed solution, the method is totally recyclable. Spectroscopic and imaging techniques including XRD, FTIR, NIR, and SEM were used to monitor the dissolution, to characterize and to confirm that CEL and CS were successfully regenerated. More importantly, we have successfully demonstrated that [CELþCS] composite is particularly suited for many applications including antimicrobial property. This is because the composites have combined advantages of their components, namely superior chemical and mechanical stability (from CEL) and bactericide (from CS). Results of tensile strength measurements clearly indicate that adding CEL into CS substantially increase its tensile strength. Up to 5Â increase in tensile strength can be achieved by adding 80% of CEL into CS. Results of in vitro antibacterial assays confirm that CS retains its antibacterial property in the composite. More importantly, the composites reported here can inhibit growth of wider range of bacteria than other CS-based materials prepared by conventional methods; that is over 24 h period, the composites substantially inhibited growth of bacteria such as MRSA, VRE, S. aureus, E. coli. These are bacteria that are often found to have the highest morbidity and mortality associated with wound infections.
Ionic liquids studied across different scales: A computational perspective
Faraday Discussions, 2012
For theoreticians, ionic liquids represent a major challenge. This is due to the fact that intermolecular interactions are particularly strong because of ionic liquids' ionicity. This, in turn, causes a subtle interplay between different scales which is encoded in the measured macro-and mesoscopic properties and also in the molecular electrostatic characteristics. Therefore, force fields have to describe the microscopic processes correctly in order to reproduce macroscopic properties accurately over a large range of state variables. Herein, imidazolium-based ionic liquids were studied at different scales, going from the detailed quantum electronic scale to the classical atomistic scale. It is indicated how the information gained at each level could be used for the other scales. In particular, the issue of deriving suitable partial charges for use in classical force fields is addressed. The Bl€ ochl method was employed to generate partial charges reproducing the multipole distribution accurately for bulk systems. This led naturally to absolute ionic charges of less than |1 e|, i.e. charge scaling. So, the monopole structure of the herein introduced force field mimics the quantum chemical behaviour observed in the liquid phase. This led to a substantial improvement in the description of dynamical properties of immediate experimental interest, such as electric conductivity. For further insight, the electric dipole moment of the ions was taken as physical indicator of their electronic structure. The electric dipole moment was found to fluctuate strongly and to depend on polarisation. Hence, our scale-combined study offers a gateway to rational design of models, based on the relevant underlying physics rather than on mere numerical parameterisation, and thereby to (possibly) more direct physical interpretation of experimental results.
Journal of Bioactive and Compatible Polymers, 2015
This study describes the microenvironmental changes due to various non-covalent interactions occurring in collagen/polyvinyl alcohol blends in the presence of ionic liquid, 1-butyl-3methylimidazolium chloride, using spectroscopic techniques. These non-covalent interactions alter the hydration network of collagen. Electronic spectral analysis of collagen/polyvinyl alcohol/ionic liquid blends exhibited movement of tyrosine amino acid from the hydrophilic to hydrophobic core of collagen. Conformational studies investigating the influence of 1-butyl-3methylimidazolium chloride on the intramolecular H-bonds revealed increased helicity packing and reorientation of H-bonds. This signifies that 1-butyl-3-methylimidazolium chloride is likely to be involved in reorienting the hydration dynamics of collagen, namely, by altering the existing and promoting formation of new intramolecular H-bonds between collagen and polyvinyl alcohol. Surface morphology of collagen/polyvinyl alcohol/ionic liquid blends revealed porous matrix, indicating 1-butyl-3-methylimidazolium chloride could act as a pore generator. This phenomenon can be employed for developing novel biomaterials with tunable porosity.
ChemEngineering
The most frequent polymer on nature is cellulose that is present together with lignin and hemicellulose in vegetal biomass. Cellulose can be, in the future, sustainable raw matter for chemicals, fuels, and materials. Nevertheless, only 0.3% of cellulose is processed nowadays due to the difficulty in dissolving it, and only a small proportion is used for the production of synthetic cellulosic fibers especially esters and other cellulose derivatives, normally in extremely polluting processes. The efficient and clean dissolution of cellulose is a major objective in cellulose research and development. Ionic liquids (ILs) are considered "green" solvents due to their low vapor pressure, that prevents them evaporating into the atmosphere. In addition, these molten salts present advantages in process intensification, leading to more than 70 patents in lignocellulosic biomass in ILs being published since 2005, most of them related to the production of cellulose derived polymers, e.g., acetates, benzoylates, sulfates, fuorates, phthalates, succinates, tritylates, or silylates. In this work, the use of ILs for production of cellulose derived polymers is thoroughly studied. To do so, in the first place, a brief summary of the state of the art in cellulose derivatives production is presented, as well as the main features of ILs in cellulose processing applications. Later, the main results in the production of cellulose derivatives using ILs are presented, followed by an analysis of the industrial viability of the process, considering aspects such as environmental concerns and ILs' recyclability. Figure 1. Cellulose structure.
Comparison of Bioethanol Preparation from Triticale Straw Using the Ionic Liquid and Sulfate Methods
Energies
Triticale straw constitutes a potential raw material for biofuel production found in Poland in considerable quantities. Thus far, production of bioethanol has been based on food raw materials such as cereal seeds, sugar beets or potatoes, and the biofuel production methods developed for these lignocellulose raw materials can threaten the environment and are inefficient. Therefore, this study aimed to compare of methods for pretreatment of triticale straw using 1-ethyl-3-methylimidazolium acetate and the sulfate method in the aspect of ethanol production intended for fuel. Based on the conducted experiments it has been determined that the use of 1-ethyl-3-methylimidazolium acetate for the pretreatment of triticale straw resulted in an increase of reducing sugars after enzymatic hydrolysis and ethyl alcohol after alcoholic fermentation. Furthermore, the study compared the efficiency of enzymatic hydrolysis of triticale straw without pretreatment, after processing with ionic liquid, re...
Soft matter, 2018
Water added to a solution of microcrystalline cellulose (MCC) in 1-allyl-3-methylimidazolium chloride (AmimCl) reduces the solvent quality and causes significant changes in the flow properties and microstructure due to restructuring and aggregation of cellulose molecules. We report an experimental investigation by means of polarization optical microscopy (POM) and rheology of the distinct phases formed in 5-20 wt% MCC/AmimCl solutions due to the addition of water. With increase in the cellulose concentration, the MCC/AmimCl/water mixtures showed different morphologies such as the non-aligned cholesteric liquid crystalline (LC) domain, the coexistence of spherulite-like structures within the LC domain and a space-spanning network of spherulite-like structures at high concentrations of water. In situ microscopy during shear and POM observations pre and post shear revealed a significant increase in the size of the birefringent domains as the shear rate is increased, which continued to ...
Membranes
Supported cellulose ultrafiltration membranes are cast from a cellulose-ionic liquid solution by the immersion precipitation technique. The effects of coagulation bath temperature and polymer concentration in the casting solution on the membrane morphology, wettability, pure water flux, molecular weight cut-off, and fouling resistance are studied. Scanning electron microscopy, contact angle measurements, atomic force microscopy, and filtration experiments are carried out in order to characterise the obtained ultrafiltration cellulose membranes. The results show the effect of coagulation bath temperature and polymer concentration on the surface morphology and properties of cellulose ultrafiltration membranes. Optimisation of the two parameters leads to the creation of dense membranes with good pure water fluxes and proven fouling resistance towards humic acid water solutions.
Advances in engineering microbial biosynthesis of aromatic compounds and related compounds
Bioresources and Bioprocessing
Aromatic compounds have broad applications and have been the target of biosynthetic processes for several decades. New biomolecular engineering strategies have been applied to improve production of aromatic compounds in recent years, some of which are expected to set the stage for the next wave of innovations. Here, we will briefly complement existing reviews on microbial production of aromatic compounds by focusing on a few recent trends where considerable work has been performed in the last 5 years. The trends we highlight are pathway modularization and compartmentalization, microbial co-culturing, non-traditional host engineering, aromatic polymer feedstock utilization, engineered ring cleavage, aldehyde stabilization, and biosynthesis of non-standard amino acids. Throughout this review article, we will also touch on unmet opportunities that future research could address.
Macromolecular Chemistry and Physics, 2011
The relevance of the structure of ILs for the dissolution and microwave-assisted acylation of eucalyptus cellulose is reported. The 1-R-3-methylimizadolium-X ILs with X = Cl, Ac and R = 1-butyl, 2-methoxyethyl, 1-heptyl, and 3,6-dioxa-(1-heptyl) are studied: C 4 MeImX, C 3 OMeImX, C 7 MeImX, and C 5 O 2 MeImX. The dissolution effi ciencies are C 3 OMeImAc > C 4 MeImAc and C 7 MeImAc > C 5 O 2 MeImAc, i.e., they depend on the length of the side chain. This surprising result is corroborated by (i) cellulose acylation by ethanoic, butanoic, and hexanoic anhydride; (ii) the energy of viscous fl ow of the ILs; (iii) the solvatochromic properties of the ILs. Our results show that C 3 OMeImAc and C 4 MeImAc are distinct from C 7 MeImAc and C 5 O 2 MeImAc, due to chain-dependent hydrogen bonding and hydrophobic interactions.
Cellulose-Multiwall Carbon Nanotube Fiber Actuator Behavior in Aqueous and Organic Electrolyte
Materials
As both consumers and producers are shifting from fossil-derived materials to other, more sustainable approaches, there is a growing interest in bio-origin and biodegradable polymers. In search of bio-degradable electro-mechanically active materials, cellulose-multi wall carbon nanotube (Cell-CNT) composites are a focus for the development of actuators and sensors. In the current study, our aim was to fabricate Cell-CNT composite fibers and study their electro-mechanical response as linear actuators in aqueous and propylene carbonate-based electrolyte solutions. While the response was (expectedly) strongly solvent dependent, the different solvents also revealed unexpected phenomena. Cell-CNT fibers in propylene carbonate revealed a strong back-relaxation process at low frequencies, and also a frequency dependent response direction change (change of actuation direction). Cell-CNT fibers operated in aqueous electrolyte showed response typical to electrochemical capacitors including ex...
REVIEWS ON ADVANCED MATERIALS SCIENCE
The scarcity of nonrenewable resource motivated inclination towards the environmental-friendly novel materials and development of waste natural filler-based hybrid composite is encouraged to fulfill the material demand. Epoxy resins-based composites are high-performing thermosetting polymers and have outstanding blending properties, good machinability, and low cost. Due to these advantages, thermoset plastic is largely used in a broad range of engineering applications; however, thermomechanical properties of neat epoxy are low. Thus, to enhance the thermomechanical properties of epoxy, it is interfaced materials such as graphite, graphene nanoplatelet, boron, carbon fiber, aluminium, silver, etc. Among various substances, graphene has been deliberated as an acceptable novel filler because of its exceptional properties. In addition to inorganic filler inclusion, natural filler/fiber like hemp, sisal, flax, bamboo, jute, etc. can be utilized in a higher percentage as biodegradable mat...
Preparation and properties of cellulose membranes with graphene oxide addition
Polish Journal of Chemical Technology
The paper presents results of research on the preparation of cellulose membranes with graphite oxide addition (GO/CEL). Initially, a cellulose (CEL) solution in 1-ethyl-3-methylimidazole acetate (EMIMAc) was obtained, to which graphene oxide (GO) dispersed in N,N-dimethylformamide (DMF) was added. From this solution, composite membranes were formed using phase inversion method. It was observed that the GO addition influences the physico-chemical properties of GO/CEL composite membranes, resulting in an increase in their mass per unit area, thickness and density, and a decrease in sorption properties. In addition, the study of transport properties has shown that GO/CEL membranes do not absorb BSA particles on their surface, which prevents the unfavorable phenomenon of fouling. An important feature of the obtained membranes is the specific permeate flux which reaches high values (~124 L/m2×h) at 3.8% of the GO addition to the cellulose matrix.
Scientific reports, 2017
Sweet potato, Ipomoea batatas, is a widely cultivated vegetable worldwide. The leaves contain polyphenolic natural products called caffeoylquinic acids (CQAs), which possess biological activities including inhibition of aggregation of amyloid peptides. The present study describes an efficient extraction and isolation procedure for CQAs from sweet potato leaves using a cellulose-dissolving ionic liquid. The results showed that, compared to methanol, use of 1-butyl-3-methylimidazolium chloride ([Cmim]Cl) allowed the extraction of a 6.5-fold greater amount of CQAs. This protocol will enable the efficient extraction of other organic compounds and biopolymers from natural materials.
Ionic Liquid-Mediated Homogeneous Esterification of Cinnamic Anhydride to Xylans
International journal of molecular sciences, 2017
A new functional biopolymer was synthesized through an ionic liquid-mediated homogeneous grafting of cinnamic anhydride to xylans. The ionic liquid used was 1-allyl-3-methylimidazolium chloride (AMIMCl) ionic liquid. Xylans with degrees of substitution (DS) between 0.11 and 0.57 were accessible in a completely homogeneous system by changing catalysts (NaOH, KOH and LiOH), time, reaction temperature, and cinnamic anhydride/xylan molar ratio. The chemical structure and the thermal stability of the derivatives were characterized by Fourier transform infrared spectroscopy (FT-IR), C-NMR spectroscopy, and thermogravimetry. The thermal stability of the derivatives was reduced compared with the original xylan. Possible applications of the cinnamic anhydride-acylated xylan derivatives include wet-end papermaking, organic-inorganic composite films, and hydrogels.
Use of Buckwheat Straw to Produce Ethyl Alcohol Using Ionic Liquids
Energies
Background: Common buckwheat (Fagopyrum esculentum Moench) is an annual spring-emerging crop that is classified among the dicotyledons, due to the manner of its cultivation, use, and chemical composition of seeds. The use of buckwheat straw for energy purposes—for example, for the production of second generation bioethanol—might enable its wider application and increase the cost-effectiveness of tillage. Methods: In this study, we examined the usability of buckwheat straw for the production of bioethanol. We pretreated the raw material with ionic liquids and subsequently performed enzymatic hydrolysis and alcoholic fermentation. The obtained chemometric data were analyzed using the Partial Least Squares (PLS) regression model. PLS regression in combination with spectral analysis within the near-infrared (NIR) spectrum allowed for the rapid determination of the amount of cellulose in the raw material and also provided information on the changes taking place in its structure. Results:...
Journal of Bioactive and Compatible Polymers, 2013
An alternative, green method was used to develop chitin-based biocomposite (ChHA) materials by an integrated strategy using ionic liquids, supercritical fluid drying, and salt leaching. ChHA matrices were produced by dissolving chitin in 1-butyl-methylimidazolium acetate along with salt and/or hydroxyapatite particles and then subsequent drying. The ChHA composite formed had a heterogeneous porous microstructure with 65%–85% porosity and pore sizes in the range of 100–300 µm. The hydroxyapatite was found to be well distributed within the composite structures and had a positive effect in the viability and proliferation of osteoblast-like cells, in vitro. Our findings indicate that these ChHA matrices have potential applications in bone tissue engineering.
Fabricating Sustainable All-Cellulose Composites
Applied Sciences
Climate change, waste disposal challenges, and emissions generated by the manufacture of non-renewable materials are driving forces behind the production of more sustainable composite materials. All-cellulose composites (ACCs) originate from renewable biomass, such as trees and other plants, and are considered fully biodegradable. Dissolving cellulose is a common part of manufacturing ACCs, and currently there is a lot of research focused on effective, but also more environmentally friendly cellulose solvents. There are several beneficial properties of ACC materials that make them competitive: light weight, recyclability, low toxicity, good optical, mechanical, and gas barrier properties, and abundance of renewable plant-based raw material. The most prominent ACC applications are currently found in the food packing, medical, technical and vehicle industries. All-cellulose nanocomposites (ACNCs) expand the current research field and can offer a variety of more specific and functional...
Spectroscopic Studies of Amino Acid Ionic Liquid-Supported Schiff Bases
Molecules, 2013
Amino acid ionic liquid-supported Schiff bases, derivatives of salicylaldehyde and various amino acids (L-threonine, L-valine, L-leucine, L-isoleucine and L-histidine) have been investigated by means of various spectroscopic techniques (NMR, UV-Vis, IR, MS) and deuterium isotope effects on 13 C-NMR chemical shifts. The results have shown that in all studied amino acid ionic liquid-supported Schiff bases (except the L-histidine derivative) a proton transfer equilibrium exists and the presence of the COO − group stabilizes the proton transferred NH-form.
Polymers, 2021
The impetus for the expanding interest in ionic liquids (ILs) is their favorable properties and important applications. Ionic liquid-based surfactants (ILBSs) carry long-chain hydrophobic tails. Two or more molecules of ILBSs can be joined by covalent bonds leading, e.g., to gemini compounds (GILBSs). This review article focuses on aspects of the chemistry and applications of ILBSs and GILBSs, especially in the last ten years. Data on their adsorption at the interface and micelle formation are relevant for the applications of these surfactants. Therefore, we collected data for 152 ILBSs and 11 biamphiphilic compounds. The head ions of ILBSs are usually heterocyclic (imidazolium, pyridinium, pyrrolidinium, etc.). Most of these head-ions are also present in the reported 53 GILBSs. Where possible, we correlate the adsorption/micellar properties of the surfactants with their molecular structures, in particular, the number of carbon atoms present in the hydrocarbon “tail”. The use of ILB...
Progress in bio-based plastics and plasticizing modifications
Journal of Materials Chemistry a, 2013
Over the coming few decades bioplastic materials are expected to complement and gradually replace some of the fossil oil based materials. Multidisciplinary research efforts have generated a significant level of technical and commercial success towards these bio-based materials. However, extensive application of these bio-based plastics is still challenged by one or more of their possible inherent limitations, such as poor processability, brittleness, hydrophilicity, poor moisture and gas barrier, inferior compatibility, poor electrical, thermal and physical properties. The incorporation of additives such as plasticizers into the biopolymers is a common practice to improve these inherent limitations. Generally, plasticizers are added to both synthetic and bio-based polymeric materials to impart flexibility, improve toughness, and lower the glass transition temperature. This review introduces the most common bio-based plastics and provides an overview of recent advances in the selection and use of plasticizers, and their effect on the performance of these materials. In addition to plasticizers, we also present a perspective of other emerging techniques of improving the overall performance of bio-based plastics. Although a wide variety of bio-based plastics are under development, this review focuses on plasticizers utilized for the most extensively studied bioplastics including poly(lactic acid), polyhydroxyalkanoates, thermoplastic starch, proteinaceous plastics and cellulose acetates. The ongoing challenge and future potentials of plasticizers for bio-based plastics are also discussed.
Superbase-based protic ionic liquids for cellulose filament spinning
Cellulose
Lyocell fibers have received increased attention during the recent years. This is due to their high potential to satisfy the rising market demand for cellulose-based textiles in a sustainable way. Typically, this technology adopts a dry-jet wet spinning process, which offers regenerated cellulose fibers of excellent mechanical properties. Compared to the widely exploited viscose process, the lyocell technology fosters an eco-friendly process employing green direct solvents that can be fully recovered with low environmental impact. N-methylmorpholine N-oxide (NMMO) is a widely known direct solvent that has proven its success in commercializing the lyocell process. Its regenerated cellulose fibers exhibit higher tenacities and chain orientation compared to viscose fibers. Recently, protic superbase-based ionic liquids (ILs) have also been found to be suitable solvents for lyocell-type fiber spinning. Similar to NMMO, fibers of high mechanical properties can be spun from the cellulose-...
Autex Research Journal, 2018
This paper presents the results of studies on the preparation of cellulosic membranes, from a solution in 1-ethyl-3methylimidazolium acetate (EMIMAc), using the phase inversion method. Initially, the membranes were obtained by coagulation of the polymer film in water and primary alcohols (methanol, ethanol, 1-propanol, 1-butanol, 1-pentanol), 1-hexanol, 1-octanol) resulting in membranes with significantly differing morphologies. Subsequently, composite membranes were produced, with the support layer being a membrane with the largest pores, and the skin layer a membrane with smaller pores. The resulting membranes were tested for physicochemical and transport properties. The morphology of the membrane surfaces and their cross-sections were investigated by using a scanning electron microscope (SEM). The structure of the membranes, on the other hand, was investigated by FTIR spectroscopy and WAXS structural analysis.
Cellulose
In this study cellulose-rich membranes were fabricated from untreated and treated hardwood biomass solutions in 1-ethyl-3-methylimidazolium acetate ([Emim][OAc])—dimetylsulfoxide (DMSO) system via wet phase separation. Wood treatment methods aimed to get purified cellulose fraction of wood. Treatment sequence was as followed: deep eutectic solvent pretreatment, sodium chlorite bleaching, and alkaline treatment. Resulted biomass after each treatment step was characterized by chemical composition and crystalline fraction content. Flat-sheet membranes were produced from biomass samples after each treatment step. Characterization of membranes included measurements of pure water permeability and (poly)ethyleneglycol 35 kDa retention, Fourier-transform infrared and Raman spectroscopy, X-ray diffraction measurements and thermogravimetric analysis. The study revealed that it was possible to fabricate membrane from untreated wood as well as from wood biomass after each of treatment steps. Th...
Advanced Sorption Process Applications [Working Title]
Biopolymers are polymeric materials derived from biological sources. Due to their renewability, abundance, biodegradability and other unique properties such as high adsorption capabilities and ease of functionalization they have been investigated for several industrial applications including sorption. Polysaccharides especially cellulose, chitin and chitosan are important biopolymers because of their high abundance, wide distribution and low cost of production. This chapter provides an overview of properties, common processing methods, and material characterization of three commonly studied biopolymers namely cellulose, chitin and chitosan. It provides a thorough review on recent developments on utilization of cellulose, chitin, and chitosan-based materials for various sorption applications. Specifically, their application and efficiency in organic dye removal, heavy metals removal, oil and solvent spillage cleanup, and CO 2 adsorption are presented and discussed.
International Journal of Molecular Sciences
Blended biocomposites created from the electrostatic and hydrophobic interactions between polysaccharides and structural proteins exhibit useful and unique properties. However, engineering these biopolymers into applicable forms is challenging due to the coupling of the material’s physicochemical properties to its morphology, and the undertaking that comes with controlling this. In this particular study, numerous properties of the Bombyx mori silk and microcrystalline cellulose biocomposites blended using ionic liquid and regenerated with various coagulation agents were investigated. Specifically, the relationship between the composition of polysaccharide-protein bio-electrolyte membranes and the resulting morphology and ionic conductivity is explored using numerous characterization techniques, including scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray scattering, at...
PLOS ONE
A number of ionic liquids have been shown to be excellent solvents for lignocellulosic biomass processing, and some of these are particularly effective in the production of the versatile chemical building block 5-hydroxymethylfurfural (HMF). In this study, the production of HMF from the simple sugar glucose in ionic liquid media is discussed. Several aspects of the selective catalytic formation of HMF from glucose have been elucidated using metal halide salts in two distinct ionic liquids, 1-butyl-3-methylimidazolium chloride and 1-butyl-3methylimidazolium hydrogen sulfate as well as mixtures of these, revealing key features for accelerating the desired reaction and suppressing byproduct formation. The choice of ionic liquid anion is revealed to be of particular importance, with low HMF yields in the case of hydrogen sulfate-based salts, which are reported to be effective for HMF production from fructose. The most successful system investigated in this study led to almost quantitative conversion of glucose to HMF (90% in only 30 minutes using 7 mol% catalyst loading at 120˚C) in a system which is selective for the desired product, has low energy intensity and is environmentally benign.
IOP Conference Series: Earth and Environmental Science, 2020
Ionic Liquids (ILs) are already recognized by the chemical industry as they possess a wide spectrum of physical and chemical properties (solubility, polarity, viscosity or solvent miscibility). However, a release of ILs from industrial processes into aquatic environments may lead to water pollution, because of their high solubilities in water. Due to these reasons, this work is conducted to investigate the photodegradation on ILs structure varies in alkyl chain length and anion group. The photocatalytic degradation was conducted based on fixed parameter optimized which includes pH = 6, [photocatalyst] = 1g/L, [ILo] = 0.11 mM and [H2O2] = 0.75 ml/L. The reaction for emimCl follows zero order whereas both bmimCl and bmimBF4 follow the first order reaction.
Cotton Cellulose-Derived Hydrogels with Tunable Absorbability: Research Advances and Prospects
Polymers and Polymeric Composites: A Reference Series, 2018
Cotton is an important, worldwide cash crop and is considered as a ubiquitous resource offering the purest form of cellulose in nature. By far, the most industrially exploited natural resources containing cellulose are wood and cotton. Cellulose derived from either wood or cotton has the same chemical structure. Hydrogels are jellylike materials consisting of substantially hydrophilic crosslinked network filled with water. Upon replacing water with air, hydrogels are able to form aerogels. Cellulose and its derivatives can be used to prepare hydrogels with tailored absorbability and adsorbability. In the first section of
Biomass deconstruction to sugars
Biotechnology Journal, 2011
The production of biofuels from lignocellulosic biomass relies on the depolymerization of its polysaccharide content into fermentable sugars. Accomplishing this requires pretreatment of the biomass to reduce its size, and chemical or physical alteration of the biomass polymers to enhance the susceptibility of their glycosidic linkages to enzymatic or acid catalyzed cleavage. Well-studied approaches include dilute and concentrated acid pretreatment and catalysis, and the dissolution of biomass in organic solvents. These and recently developed approaches, such as solubilization in ionic liquids, are reviewed in terms of the chemical and physical changes occurring in biomass pretreatment. As pretreatment represents one of the major costs in converting biomass to fuels, the factors that contribute to pretreatments costs, and their impact on overall process economics, are described.
Cellulose-based fiber spinning processes using ionic liquids
Cellulose, 2022
Cellulose, a natural, renewable, and environment friendly biopolymer, has been considered as a sustainable feedstock in the near future. However, only 0.3% of cellulose is today processed since it is not soluble in conventional solvents due to the strong hydrogen bonding network and highly ordered structure. Hence, the search of effective and eco-friendly solvents for cellulose dissolution has been a key pillar for decades. In the recent years, ionic liquids (ILs) have been proposed as green solvents for cellulose and have been applied for the production of cellulose-based fibers. This review aims to focus the attention toward fiber spinning methods of cellulose based on ILs, as well as recent progress in cellulose dissolution using ILs. Moreover, the development of cellulosic fibers blended with other biopolymers, and cellulose composites are presented. Finally, different applications of cellulose fibers and composites are summarized and discussed.
Proteins in Ionic Liquids: Reactions, Applications, and Futures
Frontiers in Chemistry, 2019
Biopolymer processing and handling is greatly facilitated by the use of ionic liquids, given the increased solubility, and in some cases, structural stability imparted to these molecules. Focussing on proteins, we highlight here not just the key drivers behind protein-ionic liquid interactions that facilitate these functionalities, but address relevant current and potential applications of protein-ionic liquid interactions, including areas of future interest.
Cellulose
The pretreatment or disruption of a cellulose I crystallite, was described from the atomistic interactions evaluated at room temperature within four deep eutectic solvents: choline-chloride ethylene glycol, choline-chloride oxalic acid, choline-chloride urea, and choline-chloride levulinic acid. The analysis was based on the obtained correlations for the Kamlet-Taft α and β parameters with a series of thermodynamic, structural, and energetic properties. The Kamlet-Taft parameters correlated with the thermodynamic properties of the solvent and their changes upon addition of the cellulose crystallite. Structural analysis revealed that the weaker the interactions within the molecules of solvent, the stronger the interactions between the hydroxyl group from cellulose with the chloride anion and with the hydrogen bond donor. Further analysis indicated that the − − moieties in the hydrogen bond donor within the solvent, interacted better with the cellulose. The hydrogen bond occupancies within the cellulose crystallite, displayed that the main 6 − 6 ⋯ 2/ 3 and 2 − 2 ⋯ 6 interchain hydrogen bonds in the glucan located at the edge of the solute were replaced by weak 6 − 6 ⋯ 4 hydrogen bonds in all solvents. This effect was related to the − ⋯ , − ⋯ , and ⋯ − HBs between cellulose and DES molecules and confirmed by the non-covalent interactions obtained through DFT calculations. Finally, the energetic interactions and the atomistic degree of disruption of the cellulose crystallite were not completely described by the Kamlet-Taft β or α parameters separately. Surprisingly, by using the net basicity (−) definition, such correlations were improved suggesting that both parameters must be considered in order to develop new, green, and sustainable solvents for cellulose pretreatment process.
Iridium-Functionalized Cellulose Microcrystals as a Novel Luminescent Biomaterial for Biocomposites
Biomolecules
Microcrystalline cellulose (MCC) is an emerging material with outstanding properties in many scientific and industrial fields, in particular as an additive in composite materials. Its surface modification allows for the fine-tuning of its properties and the exploitation of these materials in a plethora of applications. In this paper, we present the covalent linkage of a luminescent Ir-complex onto the surface of MCC, representing the first incorporation of an organometallic luminescent probe in this biomaterial. This goal has been achieved with an easy and sustainable procedure, which employs a Bronsted-acid ionic liquid as a catalyst for the esterification reaction of -OH cellulose surface groups. The obtained luminescent cellulose microcrystals display high and stable emissions with the incorporation of only a small amount of iridium (III). Incorporation of MCC-Ir in dry and wet matrices, such as films and gels, has been also demonstrated, showing the maintenance of the luminescen...
Holzforschung, 2016
In our recent studies, it was demonstrated that the IONCELL-P process selectively dissolves hemicelluloses from bleached birch kraft pulp in a mixture of 1-ethyl-3-methylimidazolium acetate ([emim][OAc]) and water as a solvent system. The IONCELL-P method refines paper-grade pulp to dissolving pulp with <5% hemicelluloses and allows isolation of polymeric xylan without yield losses or polymer degradation. This paper is a comparative study where paper-grade pine, birch, and eucalyptus pulps are subjected to the IONCELL-P process with two [emim]-based ionic liquids (ILs), i.e. [emim]acetate and [emim]dimethylphosphate. Also, the effect of an endoglucanase pretreatment was investigated to check whether 1) the pulp viscosity could be adjusted for the following process steps before the hemicellulose extraction and 2) the decreasing pulp viscosity would open the fiber structure and thus enhance the extraction. Under optimum conditions, the birch xylan content could be reduced from 25.4...
Carbohydrate Polymers
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Study of Progress on Nanocrystalline Cellulose and Natural Fiber Reinforcement Biocomposites
Journal of Nanomaterials
Cellulosic biomass hydrolysis yields a nanoscale substance known as nanocrystalline cellulose (NCC). Gel, liquid, or powder is adaptable to a variety of uses. Nanocrystalline cellulose has unique renewability, biodegradability, and mechanical and physicochemical qualities, and abundance boosts the material’s mechanical strength by many orders of magnitude when introduced into the material matrix (polymer, ceramic, or metal). Nanocrystalline cellulose is not related with any serious environmental issues because it is a natural substance. The progress of this biomaterial as a green and renewable biomaterial for the fabrication of lightweight and biodegradable composite materials gives further impetus. The current aim of nanocrystalline cellulose research is to optimise nanocrystalline cellulose characteristics for dispersion in hydrophilic and hydrophilic media. To assess the nanocrystalline cellulose reinforcing, antibacterial, stability, hydrophilicity, and biodegradability, imaging...
Holzforschung, 2019
Dissolution of microcrystalline cellulose (MCC) in pure ionic liquids (ILs) and IL/dimethyl sulfoxide (DMSO) mixtures (mole fraction χDMSO = 0.2–0.9) was quantified using a specially constructed mechanical stirring system that allows reproducible agitation speed; temperature control, and minimum solution-air contact. The electrolytes employed were: 1-(n-butyl)-3-methylimidazolium acetate (C4MeIm AcO), 1-(methoxyethyl)-3-methylimidazolium acetate (C3OMeIm AcO), 1,8-diazabicyclo[5.4.0]undec-7-enium acetate (DBU AcO), tetramethylguanidinium acetate (TMG AcO), and tetra(n-butyl)ammonium fluoride hydrate (TBAF·xH2O). The effects on MCC dissolution of IL/DMSO composition, and temperature (50, 70°C) were studied. C4MeIm AcO and C4MeIm AcO/DMSO were more efficient solvents than their C3OMeIm AcO counterparts, due to “deactivation” of the ether oxygen of C3OMeIm AcO. MCC dissolution by C4MeIm AcO/DMSO was compared with DBU AcO/DMSO, TMG AcO/DMSO at χDMSO = 0.6, and TBAF·xH2O/DMSO at χDMSO = ...
Novel Solvent Systems for Biomass Fractionation Based on Hydrogen‐Bond Interaction: A Minireview
Advanced Sustainable Systems, 2020
cellulose (30-50 wt%), hemicellulose (20-35 wt%), and lignin (15-30 wt%). [3] CO -C bonds are the main connection bond in the components, but between different components hydrogen bond is the main connection. [2b,4] Cellulose is the most abundant component composed by d-glucose units linked to each other via β-1,4-glycosidic bonds, a certain amount of cellulose shows ordered crystal structure. [5] Hemicellulose is composed with various polymerized monosaccharides, mainly are C5 (xylose, arabinose) and C6 sugars (mannose, glucose, and galactose), and others, which acts as a linkage distributing between cellulose and lignin. [6] Lignin is one kind of highly complicated cross-linked 3D amorphous resin, which is composed of three monolignols (p-coumaryl, alcohol, coniferyl alcohol, and sinapyl alcohol) connected by different CO -O bonds. [1a] Lignin mainly lies on the surface of cellulose and hemicellulose that ensures the structural integrity and rigidity of biomass. [3,7] Currently biomass catalytic conversion has achieved great success in breaking CO -C bond, so converting single component to platform chemicals or materials is quite close to industrialization. The key of efficient application of whole biomass becomes the separation of different components with high efficiency. Owing to the complex structure of biomass, biomass fractionation is the key process for the full and efficient utilization of this renewable resource. [8] In the previous reports, various solvent systems, such as strong dilute acid treatment, [9] alkaline treatment, [10] the sulphite pulping process, [11] and organosolv isolation, [12] were used to separate cellulose, hemicelluloses, lignin, and their derivatives. However, most of those traditional methods always cause serious environmental consequences and result in more cost in waste disposal owing to the application of large amounts of acids and bases. [13] By contrast, ionic liquids (ILs) [8a,b,14] and deep eutectic solvents (DESs) [4,15] are widely regarded as a green alternative solvent for their near-zero vapor pressure, high thermal stability, devisable structure, and excellent solvent power for biomass. [4b,8b,16] Not like acid or base pretreatment methods that need destruction and then fractionation of biomass components, ILs and DESs methods can achieve highly selective fractionation of biomass by controlling the functional structure of ILs or composition of DESs. [4b,8a,14b,16] According to the existing reports, many ILs and
Dissolving Cellulose in 1,2,3-Triazolium- and Imidazolium-Based Ionic Liquids with Aromatic Anions
Molecules, 2020
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 π–π 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 solub...
IOP Conference Series: Materials Science and Engineering, 2018
As a prospective raw material, lignin containing papermaking fibers can be easily recycled, dissolved with proper solvents and reused. However, in order to utilize this material, more eco-friendly green dissolution methods are also required. As a green solvent, ionic liquids (ILs) have been attracted too much interest in processing of lignocellulosic biopolymers, but the practical effect of lignin on this process was not clear. In this due, production of lignocellulosic bio-composite films from bleached (lignin-free) and unbleached (lignincontaining) soda pulps was studied. First, fibers were dissolved in 1-Buthyl 3-Methyl Imidazolium Chloride (BMIMCL) at 85-95 °C. Following fabrication and preparation of the lignocellulosic films, certain mechanical and physical properties of cellulose composite films were analyzed. FESEM and XRD analytical methods were applied to study the product morphology and structure. Microscopic studies showed both fibers were disappeared in the ionic liquid in less than 1 h, although the unbleached fibers took more time for complete dissolution. The results indicated that the films produced from unbleached pulp had less tensile strength and more dynamic contact angle with water droplet than the ones produced from bleached pulp. Moreover, the optical tests revealed that the lignin resulted in less transparency of the films, but increased absorption of UV radiations. This implies that even impure lignocellulose feedstock can have promising features.
Fibers, 2021
This paper presents an optimized washing protocol for as-received natural fibers, prior to large-scale composite manufacturing, for the structural strengthening of historic masonry. The aim was to achieve a simple protocol for standard cleaning of fiber surfaces from low molecular weight constituents that may be detrimental towards interfacial strength without damaging the fibers. The proposed procedure employs the application of the solvent sequence: ethanol, acetone, hexane, with optimized incubation times and stirring conditions. Additionally, this procedure may change the surface of the fiber, thereby enhancing the durability of the fiber-matrix interface. The washing protocol resulted in an increase of tensile strength by 56%, 52% and 22% for flax, hemp and sisal fibers, respectively, as compared to the corresponding non-washed fibers, without loss of elongation. The static contact angle measurements confirmed exposure of a higher fraction of the hydrophilic crystalline cellulo...
Polymers, 2020
Ionic liquids have shown great potential in the last two decades as solvents, catalysts, reaction media, additives, lubricants, and in many applications such as electrochemical systems, hydrometallurgy, chromatography, CO2 capture, etc. As solvents, the unlimited combinations of cations and anions have given ionic liquids a remarkably wide range of solvation power covering a variety of organic and inorganic materials. Ionic liquids are also considered “green” solvents due to their negligible vapor pressure, which means no emission of volatile organic compounds. Due to these interesting properties, ionic liquids have been explored as promising solvents for the dissolution and fractionation of wood and cellulose for biofuel production, pulping, extraction of nanocellulose, and for processing all-wood and all-cellulose composites. This review describes, at first, the potential of ionic liquids and the impact of the cation/anion combination on their physiochemical properties and on thei...
Cellulose, 2014
Rate constants for the acetylation of microcrystalline cellulose (MCC), by ethanoic anhydride in the presence of increasing concentrations of the ionic liquid (IL), 1-allyl-3-methylimidazolium chloride in dipolar aprotic solvents (DAS), N,Ndimethylacetamide (DMAC), and acetonitrile (MeCN), have been calculated from conductivity data. The third order rate constants showed a linear dependence on [IL]. We explain this result by assuming that the reacting cellulose is hydrogenbonded to the IL. This is corroborated by kinetic data of the acetylation of cyclohexylmethanol, FTIR of the latter compound and of cellobiose in mixtures of IL/ DAS, and conductivity of the binary solvent mixtures in absence, and presence of MCC. Cellulose acetylation is faster in IL/DMAC than in IL/MeCN; this difference is explained based on solvatochromic data (empirical polarity and basicity) and molecular dynamics simulations. Results of the latter indicate hydrogen-bond formation between the hydroxyl groups of the anhydroglucose unit of MCC, (Cl-) of the IL, and the dipole of the DMAC. Under identical experimental conditions, acetylation in IL/DMAC is faster than that in LiCl/DMAC (2.7-8 times), due to differences in the enthalpies and entropies of activation. Keywords Kinetics of Cellulose acetylation Á Ionic liquids Á Mixtures of ionic liquids with molecular solvents Á 1-Allyl-3methylimidazolium chloride Á N,Ndimethylacetamide Á Acetonitrile Á Molecular dynamics simulation of cellulose dissolution
Ionic liquid assisted synthesis of six-membered oxygen heterocycles
SN Applied Sciences, 2019
Due to special properties of ionic liquids (ILs) like their wide liquid range, good solvating ability, negligible vapour pressure, non-inflammability, environment friendly medium, high thermal stability, easy recycling and rate promoters etc. they are used in organic synthesis. The investigation for replacement of organic solvents in organic synthesis is a growing area of interest due to increasing environmental issues. Therefore, ILs have attracted the attention of chemists and act as catalyst and reaction medium in organic reaction with high activity. There is no doubt that ILs have become a major subject of study for modern chemistry. In comparison to traditional processes the use of ILs resulted in improved, complimentary or alternative selectivities in organic synthesis. The aim of present review is to focus on the applications of ILs for the synthesis of six-membered oxygen heterocycles (pyrans, chromenes, coumarins and dioxanes).
Cellulose, 2019
We propose a mild and versatile synthesis protocol based on N-hydroxysuccinimide-activated esters for the introduction of new functionalities to cellulose, using as starting point established protocols for the tosylation of cellulose and its subsequent reaction with a diamine linker. As a proof of concept, we describe the functionalization of microcrystalline cellulose with a N-hydroxysuccinimide-activated ester of benzophenone, a photoreactive functional group. Irradiation of the final product with UV light yields a self-standing polymer film and is expected to result in cross-linking among cellulose chains. To monitor structural changes at the molecular level, each functionalization step is characterized by a multinuclear solid-state NMR approach. DNP-enhanced 15 N CP MAS NMR experiments reveal the formation of the amide bond to the photoreactive linker and deliver further information about the binding situation of nitrogen-containing groups in these materials. The flexible synthesis protocol described here can be easily extended to a broad range of other functionalities of interest, both for the cellulose and macromolecular research.
Evaluating the hazardous impact of ionic liquids – Challenges and opportunities
Journal of Hazardous Materials, 2021
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Wide-angle X-ray diffraction (WAXS) and mechanical testing techniques are used to track the dissolution of a regenerated commercial cellulose fibre (Cordenka) in the ionic liquid 1-ethyl-3-methyl-imidazolium acetate [C2mim]+ [OAc]− for different times and temperatures. In the dissolution process, the oriented cellulose II crystals in the regenerated cellulose fibres dissolve and then reform into randomly oriented crystals to form a matrix phase, and this change in orientation enables us to follow the dissolution process using WAXS, and hence determine the dissolved matrix volume fraction vm. The change in the average molecular orientation P2 determined from an azimuthal (α) X-ray scan, allows the growth of the matrix volume fraction vm to be calculated with time and temperature. The growth of vm was found to follow time temperature superposition, with an Arrhenius behaviour, giving a value for the activation energy of Ea= 149 ± 4 kJ/mol. Young’s modulus was measured on all the resul...
Applied Sciences, 2019
In this work, several kinds of quaternary ammonium-based room-temperature ionic liquids (QA RTILs) are synthesized by alkylation and ion-exchange reactions for the rapid dissolution of cellulose. The applications of cellulose materials have been limited due to their poor solubility in conventional organic solvents, because of a high degree of structural regularity and a large number of hydrogen bonds. The prepared ionic liquids were identified by nuclear magnetic resonance, elemental analysis, and liquid chromatography-mass spectrometry. The results indicated that N,N,N-triethylhexan-1-aminium acetate (N6222OAc), tetrahexylammonium acetate (N6666OAc), and N,N,N,N′,N′,N′-hexaethyldecane-1,10-diaminium acetate (C10(N222OAc)2) exhibited good cellulose-dissolution without any pretreatment. The regenerated cellulose films with a low degree of crystallization of the cellulose II phase were also prepared easily in this process using N6222OAc due to its polar and small cation. These QA RTIL...
Cellulose
Wide-angle X-ray diffraction (WAXS) and mechanical testing techniques are used to track the dissolution of a viscose rayon multifilament yarn in the ionic liquid 1-ethyl-3-methyl-imidazolium acetate [C2mim]+ [OAc]− for different times and temperatures. In the dissolution process, the oriented cellulose II crystals in the regenerated cellulose fibres dissolve and then reform into randomly oriented crystals to form a matrix phase, and this change in orientation enables us to follow the dissolution process using WAXS, and hence determine the dissolved matrix volume fraction {v}_{m}vm.Thechangeintheaveragemolecularorientationv m . The change in the average molecular orientationvm.Thechangeintheaveragemolecularorientation{P}_{2}P2determinedfromanazimuthalP 2 determined from an azimuthalP2determinedfromanazimuthal(\alpha(α)X−rayscan,allowsthegrowthofthematrixvolumefraction( α ) X-ray scan, allows the growth of the matrix volume fraction(α)X−rayscan,allowsthegrowthofthematrixvolumefraction{v}_{m}vmtobecalculatedwithtimeandtemperature.Thegrowthofv m to be calculated with time and temperature. The growth ofvmtobecalculatedwithtimeandtemperature.Thegrowthof{v}_{m}$$ v m was found to follow time temperature superposition, with an Arrhenius behaviour, giving a value for the activation energy of Ea = 149 ± 4 kJ...
Evaluation of four ionic liquids for pretreatment of lignocellulosic biomass
BMC biotechnology, 2014
Lignocellulosic biomass is highly recalcitrant and various pretreatment techniques are needed to facilitate its effective enzymatic hydrolysis to produce sugars for further conversion to bio-based chemicals. Ionic liquids (ILs) are of interest in pretreatment because of their potential to dissolve lignocellulosic materials including crystalline cellulose. Four imidazolium-based ionic liquids (ILs) ([C=C2C1im][MeCO2], [C4C1im][MeCO2], [C4C1im][Cl], and [C4C1im][HSO4]) well known for their capability to dissolve lignocellulosic species were synthesized and then used for pretreatment of substrates prior to enzymatic hydrolysis. In order to achieve a broad evaluation, seven cellulosic, hemicellulosic and lignocellulosic substrates, crystalline as well as amorphous, were selected. The lignocellulosic substrates included hybrid aspen and Norway spruce. The monosaccharides in the enzymatic hydrolysate were determined using high-performance anion-exchange chromatography. The best results, a...
Molecules (Basel, Switzerland), 2018
There is a sustained interest in developing solvents for physically dissolving cellulose, i.e., without covalent bond formation. The use of ionic liquids, ILs, has generated much interest because of their structural versatility that results in efficiency as cellulose solvents. Despite some limitations, imidazole-based ILs have received most of the scientific community's attention. The objective of the present review is to show the advantages of using quaternary ammonium electrolytes, QAEs, including salts of super bases, as solvents for cellulose dissolution, shaping, and derivatization, and as a result, increase the interest in further investigation of these important solvents. QAEs share with ILs structural versatility; many are liquids at room temperature or are soluble in water and molecular solvents (MSs), in particular dimethyl sulfoxide. In this review we first give a historical background on the use of QAEs in cellulose chemistry, and then discuss the common, relatively ...
Cellulose, 2018
Phase separation of polymer solutions initiated by the addition of a nonsolvent is the main method for the preparation of polymer membranes. Depending on the application, such membranes must have a different pore size, which depends on the numerous parameters of the forming process. The liquid-liquid phase separation has been considered for cellulose solutions in N-methylmorpholine N-oxide (NMMO) interacting with various alcohols (methyl, ethyl, isopropyl, and isobutyl). Kinetics of cellulose regeneration was investigated by laser interferometry technique to understand the mechanism of cellulose film structure formation in the NMMO process. Influence of temperature, coagulant nature, and cellulose content on the process kinetics and morphology of the films was studied and corresponding interdiffusion coefficients were calculated. Based on the solubility parameters, triple phase diagrams of the systems were calculated. Formation of different morphologies was explained primarily by the different position of the composition path, the bimodal curve, and the gelation line in the phase diagrams. The second important parameter was the different rate of mutual diffusion of the NMMO and coagulants, due to the difference in the viscosity of the latter. Using methanol or ethanol as coagulation baths leads to obtaining the nanoporous structure of cellulose films, whereas isopropanol and isobutanol favors macropore formation.
Cellulose, 2022
Three functionalized ionic liquids (ILs) of [HeMIM]Cl, [CeMIM]Cl, and [AeMIM]Br that can dissolve corn stalk were synthesized and characterized via Fourier transform infrared spectroscopy (FTIR) and 1 H NMR. The dissolved corn stalk was in situ blended with phenol and formaldehyde to produce modified phenolic resin composites. The resulting composites were characterized via FTIR, differential scanning calorimetry, and X-ray diffraction analysis, and tested for their mechanical properties. In addition, the effects of ILs on the dissolution rate of corn stalks and on the mechanical properties of the modified phenolic resin were investigated as well. The results showed that the synthesized ILs presented good solubility toward corn stalk at the optimum temperature of 90°C. After modification with corn stalk dissolved in ILs, the mechanical properties of phenolic resin were significantly improved. At the same conditions, the phenolic resin modified with [AeMIM]Br presented the lowest concentration of free formaldehyde and the best mechanical properties, in which the tensile strength and impact strength were improved from 3.28 MPa and 0.93 kJ/m 2 to 9.36 MPa and 5.74 kJ/m 2 , respectively, but the hardness only changed slightly.
Journal of The Textile Institute, 2016
In this work, all-cellulose composite (ACC) laminates were manufactured from lyocell fabric using a simple hand lay-up and compression molding-based surface-selective dissolution technique. In dissolution step, temperature and dissolution time were fixed and pressure varied. Subsequently, the dissolved cellulose was regenerated via solvent exchange and then dried by hot-pressing. The microstructures of ACC laminates were analyzed by scanning electron microscope micrographs and measuring void content. Optimum microstructure and mechanical properties were obtained with a pressure of 1 MPa, but slightly deteriorated with further increase in pressure. The highest tensile strength and modulus achieved were 44.24 ± 2.2 MPa and 1.78 ± 0.14 GPa, respectively, for ACC-3. Best flexural strength and modulus obtained were 48.95 ± 2.87 MPa and 0.96 ± 0.21 GPa, respectively, for the same sample. The T-peel strength of ACC-3 also was very high, 2.78 ± 0.34 MPa. Application of pressure during drying had a great role on controlling shrinkage and internal voids in ACC laminates.
PLOS ONE, 2021
Air-conditioning systems make the most significant part of energy consumption in the residential sector. There is no denying that it is essential to produce a comfortable indoor thermal environment for residents in a building. The actual goal is to achieve thermal comfort level without putting too much cost on the ecological system by trying to conserve the amount of energy consumed. An effective way to help achieve such a goal is by incorporating thermal insulation in buildings. Thermal insulations help reduce thermal energy gained during the implementation of a desired thermal comfort level. This study aims to use an environmentally friendly nanoparticle of date pits to create thermal insulations that can be used in buildings. Different ratios of the nanoparticle of the date pits and sand composite were investigated. Fourier transform infrared spectroscopy and scanning electron microscopy were used to characterize the new materials. The material with nanoparticles of date pits and...
High flux novel polymeric membrane for renal applications
Scientific Reports
Biocompatibility and the ability to mediate the appropriate flux of ions, urea, and uremic toxins between blood and dialysate components are key parameters for membranes used in dialysis. Oxone-mediated TEMPO-oxidized cellulose nanomaterials have been demonstrated to be excellent additives in the production and tunability of ultrafiltration and dialysis membranes. In the present study, nanocellulose ionic liquid membranes (NC-ILMs) were tested in vitro and ex vivo. An increase in flux of up to two orders of magnitude was observed with increased rejection (about 99.6%) of key proteins compared to that of polysulfone (PSf) and other commercial membranes. NC-ILMs have a sharper molecular weight cut-off than other phase inversion polymeric membranes, allowing for high throughput of urea and a uremic toxin surrogate and limited passage of proteins in dialysis applications. Superior anti-fouling properties were also observed for the NC-ILMs, including a > 5-h operation time with no sys...
Scientific Reports
The aim of the present study is to produce flexible, flame-retardant, water-resistant and biodegradable composite materials. The ultimate goal of this research is to develop simple processes for the production of bio-based materials capable of replacing non-degradable substrates in printed circuit board. Cellulose was chosen as a renewable resource, and dissolved in 1-ethyl-3-methylimidazolium acetate ionic liquid to prepare a cellulosic continuous film. Since flame retardancy is an important criterion for electronic device applications and cellulose is naturally flammable, we incorporated ammonium polyphosphate (APP) as a flame-retardant filler to increase the flame retardancy of the produced materials. The developed material achieved a UL-94 HB rating in the flammability test, while the cellulose sample without APP failed the test. Two hydrophobic agents, ethyl 2-cyanoacrylate and trichloro(octadecyl)silane were applied by a simple dip-coating technique to impart hydrophobicity to...
Separation Science and Technology, 2017
Over the last two decades, extraction chromatography, a form of liquid chromatography employing as the stationary phase any of a variety of extractants in an appropriate organic solvent sorbed on a solid support, has emerged as an important tool for a number of analyticaland preparative-scale metal ion separations. Recent studies in which ionic liquids (ILs) have been evaluated as replacements for the molecular solvents normally used in liquid-liquid extraction suggest that an improvement in the performance of extraction chromatographic materials might be effected by the use of an IL as the basis for the stationary phase. In this report, approaches to the preparation of new sorbents incorporating ILs are described and the performance of the resultant materials in various metal ion separations is reviewed. In addition, promising areas for future work are identified.
ChemistrySelect, 2018
One-pot synthesis of polyionic liquids (PILs) from pyridinium and phosphonium family was reported in the present investigation. The size exclusion chromatographic (SEC) method was employed for the determination of the molecular weight of the polymer and the dispersity during synthesis. The aggregation behavior of these PILs was investigated in polar-protic, polaraprotic and apolar-aprotic solvents. The FTIR spectroscopic analysis was utilized for the characterization of the functional groups in PILs, whereas 1 H-NMR analysis was employed for structural characterization of the PILs in terms of the existence of magnetically non-equivalent protons. UV-Vis spectroscopic characterization was also employed for these PILs. The anti-bacterial activity of these PILs were investigated using two gram positive bacteria staphylococcus aureus and pseudomonas aeruginosa. Plate reader method was used to determine the ratio of live to dead bacterial cell in presence of PILs as a function of time by monitoring the fluorescence wave length of the corresponding cells after tagging them suitably with the appropriate dye. The plate counting method was also employed for the direct counting of the number of colony of the bacteria as a function of time in presence of the synthesized PILs. A p-electron mediated separation was found to bring the selectivity in sorption of aromatics on these PILs.
Scientific Reports, 2017
NMR self-diffusion and relaxation, coupled with viscosity, were used to study the properties and structure of two imidazolium-based ionic liquids, 1-ethyl-3-methylimidazolium acetate [C 2 MIM][OAc] and 1-ethyl-3-methylimidazolium octanoate [C 2 MIM][OOct]. The experimental results point to the formation of different types of aggregates in each ionic liquid. These aggregates are small and stable under flow and temperature in [C 2 MIM][OAc], whereas the aggregates are large and sensitive to flow and temperature in [C 2 MIM][OOct]. In the latter case the size of aggregates decreases both under flow and temperature increase. Ionic liquid (IL) is the term used to describe a salt that is in a liquid state below 100 °C. ILs have found many applications in a variety of fields, including biomass extraction and dissolution 1 , electrolytes 2, 3 , biodiesel production 4 , CO 2 capture 5 , as well as in more novel uses such as Liquid Crystal Devices 6 and medical research into viruses 7 . The field continues to grow rapidly, with thousands of new papers each year, reporting a wide range of ILs, their synthesis, properties and applications 8 . One of the recent research directions in the field of ILs is their use as cellulose solvents . Cellulose, the main component of plant cell walls, is the most abundant biopolymer on the planet. As such, it has a huge potential as a renewable material and chemical feedstock. The development of an efficient, environmentally friendly and commercially viable process for the utilisation of cellulose from plant biomass and further processing has become somewhat of a 'Holy Grail' in the field of Green Chemistry 18 . The relative insolubility of cellulose in common industrial solvents is the biggest obstacle to this and is mainly due to the formation of large hydrogen-bonded networks between cellulose chains . Though, it is also thought that the amphiphilicity of cellulose may be a significant factor in its insolubility in most traditional solvents . The early IL-cellulose studies considered mainly 1-alkyl-3-methylimidazolium (C n MIM) cations (n = 4-8) and a variety of anions, finding [C 4 MIM]Cl (n = 4) to be most effective at dissolving cellulose in their first set of trialed ILs . It was shown that the length of the cation side-chain had significant effects on the properties of the IL and its ability to dissolve cellulose. Schubert et al. studied ILs with various [C n MIM] + cations and found an odd-even cation chain length effect on solubility, with n = 4 showing the optimum solubility for a range of anions . Ismail et al. continued this line of study, using molecular dynamics calculations to investigate the dissolution of cellulose in C n MIM-based ILs . They analysed the bonding patterns between the cations, anions and cellulose chains. It was found that increasing the cation chain length caused the dynamics of the system to slow slightly but had only a minor effect on the solvation process. In 2006, Fukaya et al. showed that formate anions, combined with imidazolium cations, result in low viscosity ILs and efficient dissolution of cellulose. One of the interesting features in imidazolium-based cations and carboxylate anions (for example, formate and acetate), is that the ion length can be varied in both the anion and the cation. [C 2 MIM][OAc] being liquid at room temperature with moderate viscosity, attracted a lot of interest with a huge number of publications regarding the properties and processing of these cellulose solutions . Xu et al. used the [C 4 MIM] + cation with various anion functional groups, including formate and acetate, and
Macromolecular Symposia, 2018
Natural fiber produced from the peach palm trees (PPF) as agricultural waste is used to prepare polyaniline (PAni)‐based hybrid conductive fibers, through the in situ emulsion polymerization of aniline in isopropanol/water medium in the presence of dodecyl benzenesulfonic acid as protonating agent. Polyaniline is uniformly deposited on the fiber surface during the synthesis, as indicated by scanning electron microscopy. The presence of ionic liquid, 1‐butyl‐3‐methyl imidazolium tetrafluoroborate (bmim.BF4) during the PAni synthesis results in conductive fiber with conductivity of around 1.2 × 10−1 S cm−1, which is slightly higher than those obtained for neat PAni samples. The hybrid fibers are compounded with poly(butylene adipate‐co‐terephthalate) (PBAT) in different proportion to develop conductive biodegradable composites. For the same composite composition, those prepared with polyaniline/ionic liquid‐fiber (PAni.IL‐PPF) display higher dielectric constant, higher dielectric low,...
ChemistrySelect, 2017
In the present work the formation of water complexes with ionic liquids (ILs) –1‐butyl‐3‐methylimidazolium chloride [bmim][Cl] and 1‐butyl‐3‐methylimidazolium tetrafluoroborate [bmim][BF4] in KBr matrix at ambient temperature by IR technique was studied. There was shown that between the components of the system the hydrogen bond, in which the heteroaromatic fragment and anion (Cl− or BF4−) can participate, arises. The ab initio calculation in terms of DFT predicts a possibility of an interaction between the hydrogen atoms of CH bond in heteroaromatic ring and CH3‐group with oxygen atom as well as between anion (Cl− or BF4−) with hydrogen atom of water molecule.
Waste and Biomass Valorization, 2016
In this study, a series of ionic liquids including conventional, protic and Brønsted acidic-type ionic liquids were evaluated as media for the pretreatment of Taiwan grass. The pretreatments were carried out in parallel format, for the first time, in a novel glass reactor known as Q-tube Ò . Based on the results, the Q-tube Ò was very efficient for the pretreatment of our lignocellulosic materials in comparison with the conventional equipment (round bottom flask). Pretreatments were completed in one hour with high yield of reducing and total sugars after enzymatic hydrolysis. Some protic and Brønsted acidic ionic liquids can depolymerize partially the cellulosic material in one step and after enzymatic hydrolysis the content of reducing sugars is up to 35 times higher in comparison with the material without pretreatment.
Polymers, 2019
This review is focused on assessment of solvents for cellulose dissolution and the mechanism of regeneration of the dissolved biopolymer. The solvents of interest are imidazole-based ionic liquids, quaternary ammonium electrolytes, salts of super-bases, and their binary mixtures with molecular solvents. We briefly discuss the mechanism of cellulose dissolution and address the strategies for assessing solvent efficiency, as inferred from its physico-chemical properties. In addition to the favorable effect of lower cellulose solution rheology, microscopic solvent/solution properties, including empirical polarity, Lewis acidity, Lewis basicity, and dipolarity/polarizability are determinants of cellulose dissolution. We discuss how these microscopic properties are calculated from the UV-Vis spectra of solvatochromic probes, and their use to explain the observed solvent efficiency order. We dwell briefly on use of other techniques, in particular NMR and theoretical calculations for the same purpose. Once dissolved, cellulose is either regenerated in different physical shapes, or derivatized under homogeneous conditions. We discuss the mechanism of, and the steps involved in cellulose regeneration, via formation of mini-sheets, association into "mini-crystals", and convergence into larger crystalline and amorphous regions. We discuss the use of different techniques, including FTIR, X-ray diffraction, and theoretical calculations to probe the forces involved in cellulose regeneration.