Dissolving Microcrystalline Cellulose Research Articles

Preparation of hydrogels with self-reinforced mechanical properties using ball-milled microcrystalline cellulose and regenerated cellulose from deep eutectic solvent

Choline chloride–lactic acid deep eutectic solvent assisted by ball milling effectively dissolved microcrystalline cellulose. Regenerated cellulose was used to prepare novel cellulose hydrogel with self-reinforced mechanical properties.

Oxygen-Containing Quaternary Phosphonium Salts (oxy-QPSs): Synthesis, Properties, and Cellulose Dissolution.

In the present study, the synthesis of oxygen-containing quaternary phosphonium salts (oxy-QPSs) was described. Within this work, structure-property relationships of oxy-QPSs were estimated by systematic analysis of physical-chemical properties. The influence of the oxygen-containing substituent was examined by comparing the properties of oxy-QPSs in homology series as well as with phosphonium analog-included alkyl side chains. The crystal structure analysis showed that the oxygen introduction influences the conformation of the side chain of the oxy-QPS. It was found that oxy-QPSs, using an aprotic co-solvent, dimethylsulfoxide (DMSO), can dissolve microcrystalline cellulose. The cellulose dissolution in oxy-QPSs appeared to be dependent on the functional group in the cation and anion nature. For the selected conditions, dissolution of up to 5 wt% of cellulose was observed. The antimicrobial activity of oxy-QPSs under study was expected to be low. The biocompatibility of oxy-QPSs with fermentative microbes was tested on non-pathogenic Saccharomyces cerevisiae, Lactobacillus plantarum, and Bacillus subtilis. This reliably allows one to safely address the combined biomass destruction and enzyme hydrolysis processes in one pot.

STUDY OF THE PRODUCTION PARAMETERS INFLUENCE OF HIGHLY POROUS CELLULOSIC MATERIALS ON THEIR STRUCTURAL CHARACTERISTICS

Highly porous materials based on natural polymers are present of particular interest in various applications. Among them, for example, biomedicine, water purification, thermal insulation. This paper describes the developed method for obtaining highly porous materials based on cellulose, which include: dissolving microcrystalline cellulose in an aqueous solution of sodium hydroxide with urea; cross-linking cellulose using epichlorohydrin; drying the resulting gels. The influence of the concentrations of cellulose and the crosslinking agent and the drying method – freeze-drying (obtaining cryogels) and supercritical drying (obtaining aerogels) – on the final structural characteristics of the obtained materials has been studied. Cryogels and aerogels based on cellulose have been characterized by helium pycnometry, nitrogen porosimetry, and scanning electron microscopy. It was found that with an increase in the concentration of cellulose and epichlorohydrin, the porosity of the samples significantly decreases (from 84% to 22% for aerogels). For samples with the highest concentration of the crosslinking agent, the porosity of cryogels is higher (63%) than that of aerogels (22%). The specific surface area and mesopore volume were determined by nitrogen porosimetry, and nitrogen adsorption-desorption isotherms were obtained. Despite the fact that aerogels have a lower porosity, they are characterized by a higher specific surface area than cryogels (162 m2/g for aerogel and 65 m2/g for cryogel containing 6 wt.% cellulose and 4 wt.% epichlorohydrin). Scanning electron microscopy images were obtained, from which it can be seen that aerogels have a porous fibrous structure, while cryogels are characterized by a layered macroporous structure. The use of supercritical drying using CO2 avoids the destruction of the mesoporous structure of the material. For citation: Fedotova O.V., Trofimova K.V., Tsygankov P.Y., Safarov R.R. Study of the production parameters influence of highly porous cellulosic materials on their structural characteristics. ChemChemTech [Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol.]. 2023. V. 66. N 2. P. 107-113. DOI: 10.6060/ivkkt.20236602.6736.

Carbon Dioxide Mediated Cellulose Dissolution and Derivatization to Cellulose Carbonates in a Low-pressure System

An effective switchable solvent system using carbon dioxide (CO2) and 2-tert-butyl-1,1,3,3-tetramethylguanidine (BTMG) for cellulose dissolution and derivatization was developed. High concentration cellulose solution (up to 10 wt%) could be achieved by dissolving microcrystalline cellulose rapidly, within 5 min, into DMSO in presence of BTMG and 1 atm CO2 at room temperature. The cellulose-carbonate anion intermediate was characterized by 1H and 13C NMR spectroscopies, emphasizing the generation of cellulose carbonate anions and protonated BTMG. Addition of organochlorides into the cellulose solution triggers a nucleophilic substitution with cellulose-carbonate anions, producing various cellulose benzyl carbonates and a cellulose-carbonate-ester with degree of substitution (DS) up to 1.83 at 1 atm CO2 pressure and room temperature. The activation energy (Ea) and Gibbs free energy change (ΔG) of CO2-mediated dissolution and nucleophilic substitution were calculated by density functional theory. The results showed that the nucleophilic substitution is the rate-limiting step.

Aqueous N,N-dimethylmorpholinium hydroxide as a novel solvent for cellulose

• NDMM-OH(aq) was used for the first time to dissolve cellulose. • MCC 3 wt% could be dissolved in 1-2M NDMM-OH(aq) with maximum dissolution of 7 wt%. • Two different pulps showed clear microscopy images with traces of fiber ballooning. • SEC and NMR showed high stability of cellulose solutions over refrigeratin. • DLS indicated molecular dissolution of majority of cellulose. N,N -dimethylmorpholinium hydroxide was synthesized and its ability to dissolve microcrystalline cellulose and pulp was assessed for the first time. Microscopy and UV–Vis measurements showed that dissolution occurred over a range of 1–2 M concentration of the solvent and a maximum solubility of 7 wt% microcrystalline cellulose could be achieved. The stability of cellulose solutions was evaluated by size exclusion chromatography, which did not detect degradation to any noticeable extent. This observation was further confirmed by 13 C NMR measurements. Finally, DLS studies confirmed that most of the cellulose was molecularly dissolved, with intrinsic viscosity values indicating cellulose chains expansion in this solvent.

Education for Sustainable Development: An Undergraduate Chemistry Project on Cellulose Dissolution, Regeneration, and Chemical Recycling of Polycotton

We introduced an undergraduate chemistry project within the framework of education for sustainable development (ESD). The objective of the first part was to demonstrate the efficiency of an ionic liquid (IL)- 1-(n-butyl)-3-methylimidazolium acetate (BuMeImAcO)- as solvent for the dissolution, and subsequent regeneration of cellulose as fiber. Under mechanical stirring, the students dissolved microcrystalline cellulose in a mixture of BuMeImAcO-dimethyl sulfoxide (DMSO) at 80°C. Subsequently, they dyed the dissolved cellulose with a reactive dye, and regenerated (pink) colored fibers by injecting the resulting biopolymer solution into water (a non-solvent for cellulose). The objective of the second experiment was to show the potential application of BuMeImAcO-DMSO for the chemical recycling of the cellulosic component of polycotton (cellulose: polyethylene terephthalate; PET). Cellulose dissolves under the above-mentioned experimental conditions, leaving a mat of PET. The students dyed the dissolved cellulose, and then regenerated the biopolymer as fiber. This project fits the following aspects of ESD: fiber production from renewable sources other than cotton (wood-based cellulose); recycling of cellulose from its blends with synthetic polymers, when their reuse is not feasible. We recommend this project for senior science students of, e.g., chemistry, engineering and pharmacy, because of its simplicity, safety and socioeconomic relevance.

Evaluation of catalytic activity of cellulose films decorated with gold nanoparticles in the reduction of 4-nitrophenol

Cellulose, due to its low cost, abundance, and biodegradability, has been considered a good choice of support gold nanoparticles (AuNPs). AuNPs based nanomaterials are efficient catalysts for many reactions, including the 4-nitrophenol (4-NP) reduction, which is used in many preparations of chemical and pharmaceutical industries and has toxic effects in living organisms. The cellulose film containing gold nanoparticles was prepared by spin coating a viscous solution of dissolved microcrystalline cellulose in 1-butyl-3-methylimidazolium chloride, followed by regeneration of the cellulose matrix as a film with water addition. Then, the as-prepared film was immersed in an aqueous dispersion of AuNPs, resulting in a red film containing AuNPs with diameters around 10 nm homogeneously dispersed in the polymeric matrix. This film showed great catalytic activity for the reduction of 4-NP to 4-aminophenol using NaBH4, and it was efficient during five cycles. The catalyst prepared in this study has the advantage of being easily isolated from the reaction medium, avoiding processes of centrifugation or filtration for isolation and reuse.

Dissolution behavior of microcrystalline cellulose in DBU-based deep eutectic solvents: Insights from spectroscopic investigation and quantum chemical calculations

New solvents have been developed to dissolve microcrystalline cellulose by easily prepared DBU-based deep eutectic solvents (DESs), which have excellent solvent power for biopolymers. Cellulose/[DBU][MTU] as a typical example for detailed analysis, which was characterized (by means of FT-IR and NMR) and studied as potential cellulose dissolution media. Furthermore, selecting cellobiose as a model for density functional theory (DFT) calculation. The hydrogen bonds were explored to evaluate the strength of interaction between DESs and cellulose, which is by means of atoms in molecules (AIM), natural bond orbital (NBO) and reduced density gradient (RDG). Spectroscopic and theoretical analyses are conductive to in-depth understanding of the dissolution mechanism: both of hydrogen bond acceptor and donor in DESs interact with cellulose, contributed to the dissolution behavior. Intermolecular interactions in the complexes have been identified as non-covalent interactions, especially hydrogen bonds, which were considered to be the driving force of dissolution.

Free-standing cellulose film containing manganese dioxide nanoparticles and its use in discoloration of indigo carmine dye

In this study, we report the production of a free-standing film of non-modified cellulose impregnated with 12 wt.% of MnO2 nanoparticles with less than 100 nm in size. The method here described can be applied to the immobilization of different types of nanoparticles. The film was prepared by dissolving microcrystalline cellulose in an ionic liquid followed by its regeneration by adding water to the former solution. Then, the wet film was impregnated with the nanoparticles by dipping it in a MnO2 dispersion. Electron microscopy images revealed manganese dioxide nanoparticles distributed not only at the film surface but also in its interior. The cellulose film impregnated with MnO2 nanoparticles was capable of efficiently discolouring an Indigo Carmine dye solution in 25 min upon ambient light. The film was easily removed from the dye solution and repeatedly reused for at least 10 times without losing its discolouring efficiency.

Cellulose transparent and flexible films prepared from DMAc/LiCl solutions

Cellulose transparent and flexible film was prepared by dissolving micro-crystalline cellulose powder in Dimethylacetamide/Lithium Chloride (DMAc/LiCl) followed by regeneration in acetone and subsequent washing with water. The solution was cast on a glass plate. The interactions of water molecules and the swollen cellulose in the gel were examined by differential scanning calorimetry, DSC. An increased melting point of water in the gel indicated the presence of stronger bonding between water and cellulose than in the non-modified cellulose. The prepared dried films had 63 g/m2 weight and 0.06 mm thickness with 1.14 g/cm3 density.The prepared dry film exhibited high transparency, around 95% with visible light. The transparency and mechanical properties of the films were stable at high temperature (120°C) and exposure to UV irradiation. Thermal analysis of the prepared sample indicated film stability up to 275 °C. The tensile strength of the cellulose film was around 120 MPa with about 10% strain to break. The mechanical properties of the films were stable in alkali and acidic solutions.

Cellulose Dissolution and Biomass Pretreatment Using Quaternary Ammonium Ionic Liquids Prepared from H-, G-, and S-Type Lignin-Derived Benzaldehydes and Dimethyl Carbonate

The synthesis of novel benzyl alkylammonium ionic liquids (IL) from starting materials derived from grass, softwood, and hardwood lignin was performed using batch reactor systems followed by facile methyl carbonate ion exchange chemistry. Approximately 90% yields of the ILs were achieved over three synthetic steps, and all novel materials were fully characterized by 1H and 13C nuclear magnetic resonance spectroscopy and high-resolution mass spectrometry. The structure–activity relationships of the lignin-derived ILs were evaluated for their ability to dissolve microcrystalline cellulose and convert switchgrass to fermentable sugars (glucose and xylose). All ILs tested, including a 1:1:1 mixture of ILs prepared from vanillin, syringaldehyde, and p-anisaldehyde yielded 52–71% of the glucose and 50–71% of the xylose from the total amount of glucan and xylan available in the raw feedstock. These data compared well to the yields obtained from switchgrass pretreatment with the IL, 1-ethyl-3-methyl imidazolium a...

Transparent and Robust All-Cellulose Nanocomposite Packaging Materials Prepared in a Mixture of Trifluoroacetic Acid and Trifluoroacetic Anhydride.

All-cellulose composites with a potential application as food packaging films were prepared by dissolving microcrystalline cellulose in a mixture of trifluoroacetic acid and trifluoroacetic anhydride, adding cellulose nanofibers, and evaporating the solvents. First, the effect of the solvents on the morphology, structure, and thermal properties of the nanofibers was evaluated by atomic force microscopy (AFM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA), respectively. An important reduction in the crystallinity was observed. Then, the optical, morphological, mechanical, and water barrier properties of the nanocomposites were determined. In general, the final properties of the composites depended on the nanocellulose content. Thus, although the transparency decreased with the amount of cellulose nanofibers due to increased light scattering, normalized transmittance values were higher than 80% in all the cases. On the other hand, the best mechanical properties were achieved for concentrations of nanofibers between 5 and 9 wt.%. At higher concentrations, the cellulose nanofibers aggregated and/or folded, decreasing the mechanical parameters as confirmed analytically by modeling of the composite Young’s modulus. Finally, regarding the water barrier properties, water uptake was not affected by the presence of cellulose nanofibers while water permeability was reduced because of the higher tortuosity induced by the nanocelluloses. In view of such properties, these materials are suggested as food packaging films.

Enhanced properties of regenerated cellulose/corn cob biocomposite films

Abstract In this study, the effect of corn cob (CC) content and 2-ethylhexyl acrylate (EHA) as chemical modifier was studied. Biocomposite films on regenerated cellulose (RC) incorporated with CC at different loading were prepared by dissolving microcrystalline cellulose (MCC) and corn cob in N,N-dimethylacetamide/lithium chloride (DMAc/LiCl) using solution casting method. The effect of CC loading and EHA on tensile properties, crystallinity (CrI) and morphology of RC/CC were investigated. Tensile properties and crystallinity index (CrI) increases with the addition of corn cob. At similar CC loading, treated RC/CC films with EHA exhibit higher tensile properties and CrI than untreated RC/CC biocomposite films. The significant reinforcing effect of CC and improves interfacial interaction by EHA yielded better mechanical properties and crystallinity index of biocomposite films. The fracture surfaces and enhancement of RC/CC biocomposites films were inspected and revealed by morphological studies.

In situ synthesis of gold nanoparticles on pseudo-paper films as flexible SERS substrate for sensitive detection of surface organic residues

Surface enhanced Raman scattering (SERS) substrates that can be attached to rough, irregular surfaces and directly collect samples is especially useful for the detection of surface organic residues. Herein, novel AuNPs-pseudo-paper films (APPFs) with uniform structure, flexible properties and wicking capabilities were first fabricated and used as SERS substrate for the sensitive detection of surface pesticides residues. Gold nanoparticles (AuNPs) were in situ synthesized on pseudo-paper films (PPFs) by iterative seeding method to create lots of “hot-spots”, accordingly exhibiting high SERS activity (SERS enhancement factor of 3.02 × 106). By virtue of polyethylenimine (PEI) grafted onto the dissolved microcrystalline cellulose (MCC), AuCl4- and AuNPs can firmly be bonded to the surfaces of PPFs. The prepared APPFs show high reproducibility (relative standard deviation of 6.13%), which is attributed to the uniform surface of the films. The fabricated APPFs SERS substrate allows rapid detection of surface pesticides residues by a facile “swabbing-measure” detection mode avoiding tedious and time-consuming sampling and separation processes. Based on their inherent SERS spectra, thiram, parathion methyl, and malachite green (MG) can be simultaneously detected on apple peel, which demonstrates the potential applicability of this developed protocol for surface organic residues analysis in agriculture and food security.

Microstructures of cellulose coagulated in water and alcohols from 1-ethyl-3-methylimidazolium acetate: contrasting coagulation mechanisms

Coagulation of cellulose solutions is a process whereby many useful materials with variable microstructures and properties can be produced. This study investigates the complexity of the phase separation that generates the structural heterogeneity of such materials. The ionic liquid, 1-ethyl-3-methylimidazolium acetate ([C2mim][OAc]), and a co-solvent, dimethylsulfoxide (DMSO), are used to dissolve microcrystalline cellulose in concentrations from 5 to 25 wt%. The solutions are coagulated in water or 2-propanol (2PrOH). The coagulated material is then washed and solvent exchanged (water → 2PrOH → butanone → cyclohexane) in order to preserve the generated microstructures upon subsequent drying before analysis. Sweep electron microscopy images of 50 k magnification reveal open-pore fibrillar structures. The crystalline constituents of those fibrils are estimated using wide-angle X-ray spectroscopy and specific surface area data. It is found that the crystalline order or crystallite size is reduced by an increase in cellulose concentration, by the use of the co-solvent DMSO, or by the use of 2PrOH instead of water as the coagulant. Because previous theories cannot explain these trends, an alternative explanation is presented here focused on solid–liquid versus liquid–liquid phase separations.Graphical abstract

Potential application of medical cotton waste for self-reinforced composite

The present work mainly deals with the efficacy of the waste medical grade cotton (MGC) used for the sustainable self-reinforced composite (SRC). MGC waste was exposed in the autoclave for destroying all microorganisms including infected bacteria's and virus followed by scoured and bleached for removing blood stains and foreign materials. SRC film was prepared by selective dissolved fibre surface of waste MGC into a dissolved microcrystalline cellulose (DMCC) matrix solution prepared by lithium chloride/N,N-dimethylacetamide (LiCl/DMAc) solvent system. The tensile strength of SRC films was significantly improved up to 252 MPa, and it was higher than that of the DMCC film. In the FTIR study, no peak was found in 1620 cm−1 in SRC confirming that the LiCl/DMAc has been completely removed. SEM study also revealed the presence of partial dissolution of the surface of MGC which merged with DMCC matrix in the SRC. The XRD results displayed higher crystallinity SRC than DMCC film. The thermal stability of SRC as determined by TGA improved compared to the DMCC film from 225 °C for DMCC to 250–283 °C for SRC films. Therefore, these prominent results revealed the potential utilization of a sustainable resource, waste MGC in producing environmentally friendly SRC films with high-performance properties.

The Effect of Paddy Straw Content on Properties of Regenerated Cellulose Biocomposite Films

Regenerated cellulose (RC)/paddy straw (PS) biocomposite films was prepared by addition of PS powder in partially dissolving microcrystalline cellulose into an 8% lithium chloride/N,N-dimethylacetamide (LiCl/DMAc) solution. The effect of paddy straw on tensile properties and crystallinity index (CrI) of RC/PS biocomposite films were studied. The results obtained revealed that the tensile strength and modulus of elasticity of RC/PS biocomposite films compared with pure regenerated cellulose was significantly improved at 5 wt% PS loading but decrease with the increment of PS. The increase in crystallinity index at 5 wt% proved the enhancement affected by the incorporation of PS.

Spinning Cellulose Hollow Fibers Using 1-Ethyl-3-methylimidazolium Acetate⁻Dimethylsulfoxide Co-Solvent.

The mixture of the ionic liquid 1-ethyl-3-methylimidazolium acetate (EmimAc) and dimethylsulfoxide (DMSO) was employed to dissolve microcrystalline cellulose (MCC). A 10 wt % cellulose dope solution was prepared for spinning cellulose hollow fibers (CHFs) under a mild temperature of 50 °C by a dry–wet spinning method. The defect-free CHFs were obtained with an average diameter and thickness of 270 and 38 µm, respectively. Both the XRD and FTIR characterization confirmed that a crystalline structure transition from cellulose I (MCC) to cellulose II (regenerated CHFs) occurred during the cellulose dissolution in ionic liquids and spinning processes. The thermogravimetric analysis (TGA) indicated that regenerated CHFs presented a similar pyrolysis behavior with deacetylated cellulose acetate during pyrolysis process. This study provided a suitable way to directly fabricate hollow fiber carbon membranes using cellulose hollow fiber precursors spun from cellulose/(EmimAc + DMSO)/H2O ternary system.

Novel composite films based on cellulose reinforced with chitosan and polyvinyl alcohol: Effect on mechanical properties and water vapour permeability

Novel composite films were prepared by dissolving microcrystalline cellulose (3–5% w/w) in NaOH/urea solution, followed by coagulation in acetic acid solution. The regenerated cellulose films were immersed in chitosan-polyvinyl alcohol solutions at concentrations of 0–1% w/w and 0–4% w/w, respectively. Tensile strength, percentage of elongation at break, Young's modulus and water vapour permeability were measured to assess the effect of each compound on the mechanical and barrier properties. Polynomial models were obtained to evaluate the effect of the formulation on the measured properties. The microstructure was analysed by scanning electron microscopy. Results showed tensile strength values in the range 27.75–78.48 MPa, similar to usual synthetic polymer films. Percentage of elongation at break ranged from 0.98 to 12.82%, increasing when polyvinyl alcohol and chitosan increased. Young's modulus ranged from 2727.04 to 4217.25 MPa, showing higher values than pure chitosan and polyvinyl alcohol films. The highest value was reached combining cellulose and polyvinyl alcohol without chitosan. The water vapour permeability (1.78·10−11-4.24·10−11 g/m s Pa) showed 2 orders of magnitude higher than that of synthetic polymers, but lower than pure chitosan and polyvinyl alcohol films. Results showed that it is feasible to obtain cellulose-chitosan-polyvinyl alcohol composite films with improved mechanical properties and water vapour permeability.

High alkaline tolerant electrolyte membrane with improved conductivity and mechanical strength via lithium chloride/dimethylacetamide dissolved microcrystalline cellulose for Zn-Air batteries

LiCl/DMAc (dimethylacetamide) solution dissolved microcrystalline cellulose (LD-MCC) showed potential benefits to the alkaline solid polymer electrolyte (ASPE). High alkali tolerance (up to 70wt% KOH loading), remarkable improvements in ionic conductivity (from 0.018Scm−1 to 0.153Scm−1) and mechanical properties (3-fold increase in tensile strength from 0.28MPa to 0.76MPa) were achieved just via an incorporation of 5wt% of LD-MCC into the ASPE matrix. Wide-angle X-ray diffraction indicated that LD-MCC entrapped KOH and hindered its aggregation. X-ray Energy Dispersive Spectrometer revealed that K+ was preferentially located on the LD-MCC surfaces rather than the polymeric matrix. Scanning Electron Microscopy of freeze-dry sample demonstrated a submicro-porous morphology with reduced average pore size (175nm) after the incorporation of LD-MCC in ASPE matrix. The incorporated LD-MCC acted as KOH stabilizer, hydrophilicity agent and OH− transport media. Distinct micro-structures before and after the incorporation of LD-MCC were investigated to reveal the special role of LD-MCC in the performance improvement of ASPE membrane.