Cellulose最新文献

Microcrystalline cellulose was subjected to acetylation by different agents in solvent mixtures, composed of the ionic liquids (ILs) 1-butyl-3-methylimidazolium X (X = acetate, BuMeImAcO; chloride, BuMeImCl), and the molecular solvents (MSs), N,N-dimethylacetamide (DMAc) and dimethyl sulfoxide (DMSO). The reactions were carried out under homogeneous conditions using the following acetylation agents: acetic anhydride ((Ac)₂O), 1-acetyl-3-methylimidazolium acetate (AcMeImAcO), and vinyl acetate (VA). The efficiency of acetylation was judged by the degree of biopolymer substitution, DS. For all binary solvent mixtures, the order of DS was: AcMeImAcO > (Ac)₂O > VA. For the same acetylating agent, the order of DS was: BuMeImAcO-DMSO > BuMeImAcO-DMAc > BuMeImCl-DMSO. We rationalize this dependence of DS on reaction conditions by considering our experimental data and the results of molecular dynamics simulations (MD). Thus, solvent-induced separation of cellulose chains leads to higher acetylation rates, hence larger DS values. The order of biopolymer dissolution/chain separation is attributed to a combination of hydrogen-bonding of the IL anion with cellulose hydroxyl groups, and biopolymer-solvent hydrophobic interactions. The results of MD simulations showed an additional important point: the compositions of the cellulose solvation layers are different from those of bulk solvent mixtures; they are richer in IL ions; this difference affects the values of DS. Thus, theoretical calculations help in choosing the best solvents for cellulose dissolution/derivatization.

Spun-dyed lyocell fibers were prepared by mixing cellulose pulp with an indigo dye dispersion and subsequent spinning. The indigo dye dispersion was obtained by adding leuco indigo to N-methylmorpholine-N-oxide (NMMO) solution. The particle size of the indigo dye was controlled by adjusting the dispersion conditions. Furthermore, the application of ball milling resulted in a reduced average dye particle size of 222.3 nm. The structure and properties of the fibers were characterized using Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, and strength testing. Indigo dye particles were distributed in the interior and surface of the fibers. Relative to the undyed fiber, the crystal structure of the colored fibers was unchanged, but the crystallinity and mechanical properties improved. The color strength and color fastness of the spun-dyed lyocell fibers were assessed according to industry standards. Increasing the dye content and reducing the dye particle size (via ball milling) increased the color strength of the fibers, and the color fastness to sun and soap washing was high (Gray card grade 5). Additionally, the dye did not diffuse into the spinning coagulation bath and thus did not affect the recovery of NMMO solvent. The present study demonstrates a viable strategy for preparing spun-dyed lyocell fibers.

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Ramie fibers have poor flame-retardant properties, which limits their application. To improve the flame-retardant properties of ramie fabric (RF), a durable flame-retardant coating was successfully realized on RF by combining covalent bonding and electrostatic adsorption. Si/P/N flame-retardant coatings were constructed on RF using cationic polyethyleneimine (PEI) and anionic sodium hexametaphosphate (PSP) via the layer-by-layer (LBL) assembly approach with the introduction of 3-glycidoxypropyltrimethoxysilane (GPTMS) as an organic cross-linker. Compared with the untreated RF samples, the fabrics treated with the flame-retardant coating PEI/PSP via the LBL method presented reductions of 51.06%, 48.30%, and 40.05% in the fire growth rate, peak heat release rate, and total heat release, respectively, in the cone calorimeter test. In addition, at a weight gain of 31.57%, the fabric self-extinguished in the UL-94 test within 10 s after leaving the ignition source, resulting in a damaged length of 6.13 cm. G-3 retained the limiting oxygen index (LOI) of 26.40% after 6 laundering cycles (LCs). The TG results revealed that the char residue of G-3 at 800 °C reached 30.34 wt%. The surface of the flame-retardant coating of GPTMS-PEI/PSP had good char formation. This study provides a feasible method for realizing durable flame-retardant RFs.

There is a need for sustainable and eco-friendly materials to drive innovation in the ever-evolving paper industry in producing high-quality paper. Conventional approaches use woody fibers for their better paper-forming properties and strength. However, with an increase in population and a ban on single-use plastics, a need exists to produce more paper at economical prices. This research aims to minimize the use of woody fibers in papermaking by blending miscanthus (non-woody) pulp in eucalyptus (woody) pulp, thereby achieving similar paper properties as virgin pulp. Cationic starch and sodium alginate were electrostatically deposited on fibers to enhance the strength of the paper produced. The addition of cationic starch and sodium alginate increased the water retention value while the freeness in terms of °SR remained constant. The Fourier-transform infrared spectroscopy confirmed the presence of cationic starch and alginate which reduced the carboxyl peaks on bonding with hydroxyl groups of cellulose fibers. The developed paper sheets made from pulp blend after adding cationic starch and alginate were more remarkable than those made from virgin eucalyptus pulp in terms of mechanical properties, justifying their application in the packaging sector. Moreover, the handsheets were completely recyclable without any micro-stickies or flocs. The developed paper can be a sustainable and cost-effective alternative for reducing the utilization of wood fibers in papermaking.

The anionic nature of both cellulose fibres and reactive dyes prevents substantial exhaustion of dye from the dyebath, which is at neutral pH before alkali is added to initiate dye fixation. Conventionally, salt is added to minimize the electrostatic repulsions that interfere with dye sorption, but that increases salt loads in effluents. An alternative is to affix cationic agents on the cellulose to overcome the inherent anionic charge, but that has generally been observed to result in uneven dye sorption. The focus of investigations in this work is to examine the influence of the ratio of charges on cellulose (of affixed cationic charges to inherent anionic charges) on the extents and evenness of dye sorption. The cationisation agent 3-chloro-2-hydroxypropyl-N,N,N-trimethylammonium chloride (CHPTAC) was grafted on loose viscose fibres to yield 12 to 185 mmol kg⁻¹ cationic group content on the fibre that exhibited an inherent carboxyl group content of 68 mmol kg⁻¹. Three different dyes (of varying molecular sizes and anionic group content) were employed for examination of sorption profiles. The results from both zeta potential measurements and dye sorption profiles showed evidence of limited dye uptake until the cationic group content in fibres exceeded that of the inherent carboxyl groups. Thereafter, an uptick in dye sorption was observed, with dye sorption levels increasing with rise in degree of cationisation. There were differences between the dyes in their degrees of sorption, which appear correlated with their molecular sizes.

The versatile applications of cellulose nanomaterials derived from natural sources that possess desirable physicochemical properties have garnered significant interest across various disciplines. This contribution focuses on cellulose nanoparticles, which exhibit considerable potential for various biomedical applications, including drug delivery and tissue regeneration, as well as interfacial applications such as catalysis. The ability to modify the surface properties of these nanoparticles by the application of specific and functional groups significantly broadens the range of potential biological applications, with a particular emphasis on cancer treatment. These functionalized nanoparticles exhibit desirable biocompatibility and possess the capability to control biodistribution patterns and are therefore highly appropriate for the advancement of innovative treatment strategies. We review anticancer applications from 2020 to 2024 of these cellulose nanoparticles from a structure-property-function perspective brought out by chemical modifications on the backbone of cellulose structure through various approaches, like carboxymethylation, oxidation, hydroxy propylation, amination reactions, nanogels, and so on. We also pay special attention to a much-overlooked aspect of understanding the interaction of these cellulose nanoparticles in cancerous cells through in vitro methods like MTT assay, western blotting, etc., and in vivo methods.

In recent years, wearable smart textiles with multifunctional properties have attracted great interest for use with a wide range of applications, including personal protection, sport, healthcare etc. In the present study, all-in-one multifunctional conductive hydrophobic coated cotton fabric with electromagnetic interference (EMI) shielding, joule heating, and antibacterial properties was prepared via in-situ chemical oxidative polymerization. A graphene oxide (GO)–polyaniline (PANI)–silver (Ag) composite was coated onto the cotton fabric, exhibiting a low electrical resistance of 24.3 Ω sq⁻¹ and strong hydrophobicity, with a water contact angle of ~ 139°. The high electrical conductivity of the composite coating resulted in excellent EMI shielding of ~ 52 dB in the X-band frequency region. Notably, the EMI shielding performance was tunable by simply changing the pH due to the acid- and alkali-sensitive nature of PANI. Furthermore, the fabricated conductive cotton fabric demonstrated excellent joule heating, achieving a temperature of 105.7 °C within 30 s at a voltage of 3.5 V. Additionally, in the presence of Ag, the cotton fabric exhibited excellent anti-bacterial properties against both Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria.

The interfacial topography of biomaterials has been identified as a major biophysical regulator of cell behavior and function, a role played through the interplay with biochemical cues. In this work, we demonstrate the potential of laser as a versatile technology for the direct fine-tuning of the topography of Bacterial nanocellulose (BNC) with bioinspired topographies and micropatterns on a cell size scale. Two lasers were used, with different wavelengths—IR (CO₂, 10600 nm) and UV (tripled Nd: YVO₄, 355 nm) —attempting to reproduce the Pitcher-plant topography and to create cell-contact guidance patterns, respectively. Different topographies with parallel grooves featuring a 20–300 μm period were generated on the BNC surface with high fidelity and reliability of the generated microstructures, as demonstrated by 3D optical profilometry and scanning electron microscopy. Moreover, it was demonstrated by X-ray photoelectron spectroscopy that laser processing does not result in detectable chemical modification of BNC. The developed anisotropic microstructures can control cell behavior, particularly regarding morphology, alignment, and spatial distribution. Thus, this proof-of-concept study on the high-resolution laser patterning of BNC opens new perspectives for the development of cell-modulating laser-engineered BNC interfaces, scaffolds, and other advanced medical devices, which can potentially broaden the application of BNC in the biomedical field.

This work explored whether partial cellulose bioconversion with fungal mycelium can improve the properties of cellulose fibre-based materials. We demonstrate an efficient approach for producing cellulose-mycelium composites utilizing several cellulosic matrices and show that these materials can match fossil-derived polymeric foams on water contact angle, compression strength, thermal conductivity, and exhibit selective antimicrobial properties. Fossil-based polymeric foams commonly used for these applications are highly carbon positive, persist in soils and water, and are challenging to recycle. Bio-based alternatives to synthetic polymers could reduce GHG emissions, store carbon, and decrease plastic pollution. We explored several fungal species for the biofabrication of three kinds of cellulosic-mycelium composites and characterized the resulting materials for density, microstructure, compression strength, thermal conductivity, water contact angle, and antimicrobial properties. Foamed mycelium-cellulose samples had low densities (0.058 – 0.077 g/cm³), low thermal conductivity (0.03 – 0.06 W/m∙K at + 10 °C), and high water contact angle (118 – 140°). The recovery from compression of all samples was not affected by the mycelium addition and varied between 70 and 85%. In addition, an antiviral property against active MS-2 viruses was observed. These findings show that the biofabrication process using mycelium can provide water repellency and antiviral properties to cellulose foam materials while retaining their low density and good thermal insulation properties.

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In modern society, with the rapid increase in energy consumption, there is a growing interest in the effective utilization of bio-resources. Biomass aerogels have considerable academic research value due to their eco-friendly attributes and renewable nature. In this work, sodium alginate (SA) and sodium lignosulfonate (SLS) are employed as the matrix, which are dually cross-linked with Ca²⁺ and bis[tetrakis(hydroxymethyl)phosphonium] sulfate (THPS). Subsequently, a well-formed aerogel (CA-SP) is obtained through the lyophilization process. The formed dual crosslinking network and the “egg-box” structure endow the CA-SP aerogel with superior flame retardancy and thermal insulation properties, as evidenced by a limiting oxygen index value of 40.8%, achievement of the UL94 V-0 rating and low total heat release (1.35 MJ·m⁻²). Moreover, the THPS simultaneously endows the SA-SP aerogel with excellent flame retardancy and antimicrobial effect. The exceptional flame retardancy, smoke suppression capabilities, and antimicrobial effects of the CA-SP aerogel expand its prospects for application.