Concentration Of Cellulose Solution Research Articles

Production of Cellulose Beads with Tetraethylammonium Hydroxide-Urea Solvent and Dropping Technique : Effects of Concentration of Cellulose Solution

Production of Cellulose Beads with Tetraethylammonium Hydroxide-Urea Solvent and Dropping Technique : Effects of Concentration of Cellulose Solution

Preparation of Diameter‐Controlled Cellulose Aerogel Spheres via Atomization Method and Their Load Performance

AbstractCellulose aerogel spheres (CASs) are potential carriers due to their low‐cost and large‐scale features. In this paper, uniform CASs with precisely controlled diameters are prepared and their performance is characterized. The results show that the optimum conditions for the preparation of CASs are as follows: coagulation bath composition: Vtrichloromethane: Vethyl acetate: Vacetic acid = 10:10:3, cellulose solution concentration: 2%, and stirring rate: 500 r min−1. The CASs prepared under optimum conditions have smooth spherical surfaces with 3D inner network structures. The diameter of the CASs gradually decreases with increasing air pump pressure and can be controlled between 30 and 1500 µm. Moreover, the loading performance of the CASs with different diameter is investigated. The results show that the load capacity of the CASs for the energetic material cyclotrimethylenetrinitramine (RDX) decreases as the diameter decreases. The diameter of CASs directly determines the balance between energy density, safety performance, and energy output of energetic materials. These CASs with controllable diameters, as well as facile production method give them a series of potential applications in high energy material loading.

Eco-friendly and thermally stable cellulose film prepared by phase inversion as supercapacitor separator

The transparent and renewable porous cellulose separators (ACR-3, ACR-5, ACR-7, ACR-9) with different concentration of cellulose solution (3 wt%, 5 wt%, 7 wt%, 9 wt%) were prepared via a phase-inversion process with 1-allyl-3-methylimidazolium chloride (AMIM-Cl) as the solvent. Cellulose separators displayed high thermal stability, strong mechanical properties and excellent apparent properties. ACR-7 separator showed a higher porosity of 74.90% and electrolyte uptake of 323.68% with a smaller pore size and a more uniform pore structure compared with the other cellulose separators. The assembled supercapacitors (electrode/separator/electrode, SCD-7) showed good electrochemical performances in many aspects, including a lower equivalent series resistance of 0.5Ω, a higher charge-discharge efficiency of 98.58% at 3 A/g and areal capacitance of 1.15 F cm−2 at 5 mV/s than the SCD-3, SCD-5, SCD-9 and the assembled SCDs with two commercial separators (TF4040 for SCD-40 and MPF30AC for SCD-30). SCD-7 showed a high retention of 81.99% after 4000 charge-discharge tests at 1 A/g, showing a good charge-discharge cycle stability. Compared with SCD-40 and SCD-30, SCD-7 showed a lower voltage drop below 0.03 V, a higher specific capacitance of 130 F/g, energy density of 25.94 Wh/kg and power density of 0.36 kW/kg at 0.5 A/g. Overall, ACR-7 is expected to be applied as a separator in the field of supercapacitors.

Cellulose dissolution in diallylimidazolium methoxyacetate\u2009+\u2009N-methylpyrrolidinone mixture

The utilization of cellulose in industrial applicat is of great significance to sustainable development of human society and reducing dependence on dwindling fossil resources. Nevertheless, this utilization of cellulose has actually been limited due to its insolubilization. Here, novel solvents consisting of diallylimidazolium methoxy acetate ([A2im][CH3OCH2COO]) and N-methylpyrrolidinone (NMP) were developed. The solubility of cellulose in [A2im][CH3OCH2COO]/NMP was determined, and the influence of [A2im][CH3OCH2COO]/NMP molar ratio on cellulose dissolution was systematically investigated. Meanwhile, we also presented the affecting factors of the cellulose material fabrication including preparation approach, [A2im][CH3OCH2COO] and cellulose solution concentration. Attractively, the [A2im][CH3OCH2COO]/NMP solvents display much powerful dissolution capacity for cellulose even at 25 °C (25.4 g 100 g−1). This is mainly ascribed to the combined factors: The hydrogen bond interactions of the H2, H4 and H6 in [A2im]+ and carboxyl O atom in [CH3OCH2COO]− with the hydroxyl H atom and O atom in cellulose; the dissociation of NMP towards [A2im][CH3OCH2COO]; the stabilization of NMP towards the dissolved cellulose chains. In addition, the thermostability and chemical structure of the regenerated cellulose from the solvents was also estimated.

Development of Diallylimidazolium Methoxyacetate/DMSO (DMF/DMA) Solvents for Improving Cellulose Dissolution and Fabricating Porous Material.

Cellulose is the most abundant natural biopolymer, with unique properties such as biodegradability, biocompability, nontoxicity, and so on. However, its extensive application has actually been hindered, because of its insolubility in water and most solvents. Herein, highly efficient cellulose solvents were developed by coupling diallylimidazolium methoxyacetate ([A2im][CH3OCH2COO]) with polar aprotic solvents dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), and N,N-dimethylacetamide (DMA). Attractively, these solvents showed extraordinarily powerful dissolution performance for cellulose (e.g., 26.1 g·100g−1) in [A2im][CH3OCH2COO]/DMSO(RDMSO = 1.01 solvent even at 25 °C), which is much more advantageous over previously reported solvents. To our knowledge, such powerful cellulose solvents have not been reported before. The cellulose dissolution mechanism is proposed to be of three combined factors: (1) The hydrogen bond interactions of the H2, H4 and H6 in [A2im]+ and the carboxyl O atom in [CH3OCH2COO]−, along with the hydroxyl H atom and O atom in cellulose, are main driving force for cellulose dissolution; (2) the dissociation of [A2im][CH3OCH2COO] by DMF increases the anion and cation concentrations and thus promotes cellulose dissolution; (3) at the same time, DMF also stabilizes the dissolved cellulose chains. Meanwhile, the porous cellulose material with a varying morphologic structure could be facially fabricated by modulating the cellulose solution concentration. Additionally, the dissolution of cellulose in the solvents is only a physical process, and the regenerated cellulose from the solvents retains sufficient thermostability and a chemical structure similar to the original cellulose. Thus, this work will provide great possibility for developing cellulose-based products at ambient temperatures or under no extra heating/freezing conditions.

Dissolution performance of cellulose in [A2im][MOA]/MIM solvents.

Cellulose solvents ([A2im][MOA]/MIM) were developed by combining diallylimidazolium methoxyacetate ([A2im][MOA]) with N-methylimidazole (MIM). The cellulose solubilities in the ([A2im][MOA]/MIM) solvents were determined at 25 °C, and the effect of the MIM/[A2im][MOA] molar ratio on cellulose solubility was systematically investigated. Attractively, the solvents show cellulose solubility as high as 25.2 g 100 g−1 even at 25 °C. It is proposed that the H2, H4 and H6 in [A2im]+ and the carboxyl O atom in [MOA]− primarily contribute to the dissolution of cellulose; MIM mainly acts to dissociate [A2im][MOA] into [A2im]+ and [MOA]−, and stabilize the dissolved cellulose chains. Moreover, the porous cellulose materials with varying morphological structures could be tailored by simply tuning the cellulose solution concentration, and the formation mechanism of the cellulose material was discussed.

In situ controllable synthesis of Ag@AgCl in cellulose film and its effect on anti-fouling properties

Cellulose–Ag@AgCl composite films were fabricated by one-step coagulation of the cellulose/1-Butyl-3-methylimidazolium chloride (BmimCl)solution with AgNO3. AgCl was firstly formed when AgNO3 was added into cellulose/BmimCl solution, and then the formed AgCl was further reacted with excess Cl−, leading to the complete dissolution of AgCl. The AgCl crystal would grow again from cellulose matrix in the air after the film formation. Meanwhile, AgCl could be partly decomposed into Ag° and formed Ag@AgCl under visible-light irradiation. The morphology of Ag@AgCl in cellulose matrix could be regulated by changing the molar ratio of BmimCl and AgNO3, the growth time of AgCl crystal and the concentration of cellulose solution. The cellulose composite film with stamen-like Ag@AgCl showed the best anti-fouling properties for methyl orange reagent under visible-light irradiation. This work also provided a simple pathway to regulate the morphology of Ag@AgCl in cellulose or other polymer matrices.

Cellulose hydrogel with tunable shape and mechanical properties: From rigid cylinder to soft scaffold

Cellulose hydrogel from aqueous solution of lithium bromide demonstrated excellent tunability of mechanical property and shape. A series of compression tests showed that cellulose hydrogel covered a wide range of mechanical property, where the compressive Young's modulus was controllable from 30 kPa to 1.3 MPa by changing the initial concentration of cellulose solution. Meanwhile, the diameter of the building block of gel, namely nano-fibrous cellulose, was constant at 15–20 nm irrelevant of the initial concentration of cellulose solution. Moreover, thanks to the biocompatibility of cellulose, the cultivation of cartilage tissue was successful in the micro-porous sponge-like cellulose hydrogel prepared by salt-leaching process. These findings show that this environmentally-benign versatile gel offers a new substrate for the biomaterial-based nanomaterial in biomedical applications.

Size controlled fabrication of cellulose nanoparticles for drug delivery applications

Spherically shaped cellulose nanoparticles with average particle diameter range between 70 and 365 nm were fabricated from cotton fibers by a simple nanoprecipitation method. The average particle diameter of cellulose nanoparticles could be precisely controlled by modulating the synthesis conditions such as cellulose solution concentration and volume ratio of solvent/non-solvent. Methylene blue (MB) as a model hydrophilic drug was loaded onto cellulose nanoparticles via the in-situ nanoprecipitation process. The loading efficiency and release profile of MB were observed to be affected by the average particle diameter of cellulose nanoparticles.

Cellulose gel dispersion: From pure hydrogel suspensions to encapsulated oil-in-water emulsions

Cellulose hydrogel particles were fabricated from molecularly-dissolved cellulose/IL solutions. The characteristics of the formed hydrogels (cellulose content, particles’ size and porosity) were determined as a function of cellulose concentration in the precursor solutions. There is a significant change in the hydrogel structure when the initial cellulose solution concentration increases above about 7–9%wt. These changes include increase of the cellulose content in the hydrogel, and decrease in its pore size. The finest cellulose particle dispersions can be obtained using low concentration cellulose/IL solutions (cellulose concentration in dispersion less than 2%wt.) or hydrogels (concentration less than 1%wt.) in a dispersing medium consisting of IL with no more than 20%wt. water. Stable paraffin oil-in-water emulsions are achieved by mixing oil and water with cellulose/IL solutions. The optimal conditions for obtaining the finest particles (about 20μm in diameter) are attained using cellulose solutions of concentration between 0.7 and 4%wt. at temperature of 70°C and oil/cellulose mass ratios between 1 and 1.5.

The Preparation and Characterization of Spherical Cellulose Aerogels with Core-Shell Structure

The spherical cellulose aerogels with core-shell structure were prepared through hanging drop method in a regenerated non-polar solution. The procedures of these aerogels' preparation include solidification in the acetic acid solution to form a hydrogel, solvent exchange with t-butyl alcohol and freeze drying. The spherical cellulose aerogels were obtained with different cellulose solution concentration, and characterized with BET analysis and electron microscopy. Their density and porosity varied linearly with different cellulose content in the initial solution. And the gel shrinkage upon drying was limited to, on average, 7.3%. The density of spherical cellulose aerogel could be reached down to 0.14 g·cm-3 with high specific surface areas up to 210 m2·g-1. The mesopores' diameter of spherical cellulose aerogel at the highest peak in the size distribution curve is focus on 15nm.

Study on the coagulation process of cellulose nascent fibers with ionic liquid AMIMCl as a solvent during dry-wet spinning

AbstractThe coagulation process of nascent fiber of cellulose with ionic liquid 1- allyl-3-methylimidazolium chloride (AMIMCI) as the solvent was studied during drywet spinning. The diffusion rate and the crystallization situation of nascent fiber were tested, its fracture morphology was observed, and the diffusion coefficient D of solvent and the crystallization degree of nascent fiber were calculated according to relevant equations. The diffusion rate and diffusion coefficient of ionic liquid decrease with cellulose concentration increasing in spinning solution and then remain almost the same when the cellulose mass fraction reaches 7%. With the increase of coagulation bath concentration, the diffusion rate and diffusion coefficient of the solvents increase first and then decrease. When the coagulation bath concentration reaches 5%, the diffusion rate and diffusion coefficient of the solvents are at their maximum. With the increase of coagulation bath temperature and the length of air gap, the diffusion rate and diffusion coefficient of ionic liquid increase slightly. The cellulose solution concentration and the spinning air gap have an influence on the crystallization degree of nascent fiber. With the increase of cellulose solution concentration and the spinning air gap, the crystallization degree of the produced nascent fiber increases slightly, but the coagulation bath temperature basically have no influence on the nascent fiber formation.

Hydrogels from polysaccharides. I. Cellulose beads for chromatographic support

Cellulosic hydrogels in bead form were prepared by dropwise addition of cellulose solutions in N,N-dimethylacetamide (DMAc) and lithium chloride (LiCl) to azeotropic methanol or isopropanol as nonsolvent. Bead properties were examined in relation to cellulose solution concentration, viscosity, and molecular weight. Bead properties were defined in terms of solids content, flow characteristics, mechanical strength, bead size, and pore dimensions. Results suggest that (a) beads can be prepared with solids content ranging from 2 to 12 wt %, depending on solution concentration; (b) uniform spherical shapes require a viscosity range between 100 and 300 cS: (c) beads can be produced in different sizes, within the diameter range of 100 to 1,500 μm; (d) linear flow velocities of packed bead columns are in the range of 70 to 350 cm/min; and (e) pore sizes of beads vary between 8 to 200 A. Beads with low cellulose concentration show a wide fractionation range of up to 200,000 g/mol for polyethylene oxide. © 1996 John Wiley & Sons, Inc.