Cellulose最新文献

Nitrocellulose is industrially produced from cellulose by treatment with nitric and sulfuric acid. While sulfuric acid is known to catalyse the hydrolysis of cellulose, its effect on nitrated cellulose has not been reported before. Herein we show by gel permeation chromatography that hydrolysis of nitrocellulose derived from cotton linters over a one-week timescale reduces the length of the polymer chains via a two-stage reaction process similar to that observed for cellulose. Powder X-ray diffraction patterns and scanning electron microscopy images of nitrated cellulose samples originating from plant and bacterial sources are compared with highly processed nitrocellulose membranes and show a variation in morphology and an enhancement of sample crystallinity. This highlights a selective mechanism where the amorphous domains are preferentially hydrolysed over the crystalline domains, which is also common behaviour with cellulose. Overall, this work shows that the timescale for nitration exerts control over the resulting product crystallinity, morphology and polymer chain length.

Graphical abstract

A multifunctional cotton fabric with superior photocatalytic self-cleaning, antibacterial activity and UV protection was prepared through treatment with TiO₂/Pt/SiO₂ colloid, clarifying the influence of coating formulation on these functionalities. The photocatalytic activity of coated fabrics under UV and white-fluorescent light was tested and synergistic effects of Pt and silica in enhancing the self-cleaning property of fabrics were demonstrated. Various molar ratios of Pt:Ti (0.01%, 0.1%, 0.5%, and 1%) and Ti:Si (50/50 and 30/70) were utilised in synthesising the colloids. The self-cleaning performance of fabrics was assessed through monitoring coffee stain removal efficiency and methylene blue (MB) dye degradation kinetics. The results demonstrated an effective photocatalytic self-cleaning property on fabrics coated with TiO₂/Pt/SiO₂ colloids. Increasing the concentrations of Pt and silica both contributed to enhancing the self-cleaning property. The fabric coated with ternary TiO₂/Pt/SiO₂ 30/1/70 colloid resulted in 43.5% higher MB dye removal compared with pure TiO₂ after 3h irradiation under visible light. Moreover, the fabrics containing Pt 1% dopant possessed excellent bactericidal activity against both Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) bacteria, regardless of the presence of silica. While the addition of silica slightly reduced the UV protection of coated fabrics, increasing the concentration of Pt to 1% increased the protection level to 45 + . Various characterisation techniques including SEM, XPS, XRD, and TEM were employed to study the Pt-doping of TiO₂ nanoparticles, as well as the effect of Pt concentration, superhydrophilicity of silica, and the chemical composition of coatings on the functionalities of fabrics.

Cellulose cryogels (CA) with high porosity and environmental sustainability are expected to replace traditional petroleum-based insulation materials. However, the efficient thermal insulation and mechanical reinforcement of cellulose cryogel still face challenges. We develop zinc oxide/cellulose (ZnO/CA) cryogels through a straightforward strategy involving the dissolution of cellulose in a sodium hydroxide-urea solution followed by directional freezing. Specifically, the sodium hydroxide-urea solution disrupts the intermolecular and intramolecular hydrogen bonds within cellulose, converting its crystalline structure from cellulose I to cellulose II. The temperature gradient during directional freezing induces a uniformly ordered, three-dimensional layered porous structure with ultra-low density (0.071–0.102 g/cm³) and high porosity (95.75–93.47%). Importantly, the Young’s modulus of the ZnO/CA cryogel reaches 2.87 MPa, while its thermal conductivity is as low as 0.0138 W·m⁻¹·K⁻¹, indicating high compressive strength and excellent thermal stability. Within the ZnO/CA cryogel framework, the overall emissivity in the infrared band is below 0.5, effectively reducing thermal radiation intensity. On an 80 ℃ hot target, the surface radiation temperature of the cryogel drops to as low as 38 ℃. Furthermore, ZnO/CA cryogel-coated fabrics exhibit a 74% increase in insulation compared to untreated cotton fabric and demonstrate effective insulation for various heat sources. The lightweight, reinforced ZnO/CA cryogel offers new possibilities for developing wearable insulating devices and high-performance thermal insulation materials.

To address the challenges of low fixation and poor resistance to staining on white ground of reactive dyes in the dyeing and printing industry, two new polyfunctional reactive dyes (MFA-1 and MFA-2) were developed. These dyes, which contained m-phenylenediamine derivatives with sulfonic and methyl groups as bridge groups, demonstrated high solubility (above 350 g/L) and low affinity to fibers. Detailed investigations were conducted to understand the factors affecting printing performance. The two dyes exhibited exceptionally high fixations of 94.35% and 95.75%, respectively, on cotton fabrics at a high dye concentration of 5.0%. This represented a 24% and 43% improvement over C.I. Reactive Red 111 and C.I. Reactive Red 120, respectively. Notably, MFA-2 achieved a fixation above 95% even at a higher dye concentration of 10.0%. Additionally, both MFA-1 and MFA-2 showed minimal staining on white ground, with fastness properties of grades 3 and 4, respectively, representing 2–3 grades higher than C.I. Reactive Red 111 and C.I. Reactive Red 120. The mechanism behind the exceptional fixation and low staining properties of these dyes was proposed, suggesting that the unique structure of the bridge group disrupted the co-planarity of the dye molecule and evenly distributed the negative charge in the dye molecule. Furthermore, the cotton fabrics printed with MFA-1 and MFA-2 demonstrated good color uniformity, with low ΔE values of 0.46 and 0.32, respectively. The printed fabrics also exhibited good dry and wet rubbing fastness (grades 4 and 3, respectively), wash fastness (grades 4–5), light fastness (grade 4), and perspiration fastness (grades 4 or 4–5).

This article provides a comprehensive review of innovative applications of nanocellulose combined with rare earth elements (REEs). The review includes various fields, from materials science to electronics, catalysis, sensors, substance adsorption, and medicine. Overall, 72 studies were found in dates ranging from 2013 to 2024, mostly combining REEs with cellulose nanocrystals (CNCs) or nanofibrils (CNFs), while only a few bacterial cellulose nanocrystals (BCNCs) or bacterial cellulose nanofibrils (BCNFs) studies were encountered. Lanthanum, cerium, europium, terbium and dysprosium were the most common occurrences in these combinations. Research has shown that properties from nanocellulose, such as high specific surface area and aspect ratio, can be exploited with the addition of REEs in low quantities. The luminescence of lanthanide ions, such as Eu³⁺, Dy³⁺ and Tb³⁺ stood out, offering innovative applications in security, such as counterfeit prevention in banknotes, labels and inks. The structural and UV resistance properties from REEs containing compounds can also be highlighted, especially being found in composites of nanocellulose and oxides. The use of these materials in medicine, adsorption and sensing of substances and in electronics was also discussed. No combinations of nanocellulose with scandium, praseodymium, promethium, holmium or thulium were found, indicating potential for novel materials. The significant increase in publications on this topic suggests a growing scientific interest, indicating vast potential for future interdisciplinary research and developments in these areas.

Cellulose nanocrystals (CNCs) have gained considerable attention due to their superior properties, i.e., high aspect ratio, high modulus and strength, low density, and have been widely studied as a key component in the development of green nanocomposites. In this study, electrospinning of CNC-loaded polymer blend of polylactide (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) is reported for the first time. The polymer blend ratio and solvent ratio of dichloromethane (DCM)/ dimethyl sulfoxide (DMSO) was optimized based on electrospinnability of the developed solution formulations, and successful fabrication of homogeneous bead-free nanofibers. Subsequently, CNCs were incorporated into PLA/PBAT polymer blends at various loading levels, i.e., from 1 to 5 wt%, in order to explore the influence of CNC incorporation on the key properties of PLA/PBAT nanocomposite nanofibrous webs, i.e., morphological and chemical structure, melting and crystallization behavior, thermal and hydrolytic degradation, mechanical performance and wettability characteristic. The main finding of this study was that well-distributed nanoparticles in the nanofibrous webs led to improved mechanical, thermal and wettability properties, even with a low CNC loading level, i.e., 1 wt%. The outcomes provide a groundwork for future studies on the design and fabrication of biodegradable nanocomposite nanofibers from PLA/PBAT blends for a variety of applications including tissue engineering, drug delivery, active/ intelligent food packaging, by clearly elucidating the structure–property relationships.

Reducing energy consumption by industrial processes has become imperative because of rising energy costs and efforts toward decarbonisation. The continuous manufacturing of paper is energy intensive due in part to the water removal process required to convert pulp slurries to valuable paper products. This necessitates the development of energy conservation techniques, while simultaneously ensuring the quality of the product. A pilot-scale test unit was developed to quantify the effects of dwell time, vacuum pressure, and refining energy on the achievable pulp concentration or dryness level of three pulp types utilised in paper machines. Pulp dry matter was investigated as a means of gauging vacuum consumption and hence energy utilisation in paper machines, which could potentially reduce utility consumption of the overall drying process. A novel approach to simulate the pulsating high vacuum zone in the forming section of a paper machine was implemented, allowing the development of statistical correlations to explore vacuum dewatering conditions that may lead to energy efficiency. Bleached hardwood, mechanical/groundwood and recycled pulp were characterised to determine the effects of refining energy on fibre morphology and their drainage behaviour in pulp slurries. A dryness level of 21.8% at − 55 kPa gauge was achieved for bleached hardwood, whereas lower values of 19.8 and 18.3% were observed for recycled and mechanical pulps, respectively. This behaviour was attributed to the differences in drainability and morphology of the pulps due to their respective unique properties, further exaggerated by refining.

Molded fiber products are regaining popularity for food service applications due to growing concerns about plastic pollution and environmental sustainability. However, to render molded fiber products water and grease resistant, per- and polyfluoroalkyl substances are usually added. In this work, we have demonstrated that cellulose nanofibrils (CNFs) can play a dual role in molded fiber products, both as a binder and as a grease resistant layer. The objective of this work was to produce paper plates via a thermoforming process by hybridizing conventional bleached Kraft pulp (BKP) with lignocellulosic residues such as wood flour (WF) or thermomechanical pulp, using CNFs as a binder. Different formulations were prepared to screen the paper plate formulations and determine the optimal weight percentage ratio of raw materials based on the mechanical properties (tensile and flexural) of the product. The order in which lignocellulosic fibers were added was investigated prior to the experiments and found to have no impact on the mechanical properties of the paper plates. Replacing 35% of BKP with WF and using 10% CNF as a binder resulted in a 90–130% increase in tensile and flexural properties of the paper plates compared to control paper plates made from BKP. Paper plates laminated with 40 g/m² CNF exhibited a good grease barrier (Kit 12), a Cobb value of 36 ± 4 g/m², and tear resistance of 14 ± 4.0 (N/mm), and had a smooth surface confirmed through SEM analysis.

Energy derived from the salinity gradient between seawater and river water is recognized as a sustainable energy source and an alternative solution for meeting the growing energy demand. The ion exchange membrane is essential for efficiently converting the salt differential gradient energy of the salinity gradient into electrical energy. Herein, we reported a sustainable, porous cellulose membrane (PCM) by a doping-removing strategy of polyvinyl pyrrolidone (PVP) during the fabricating process of the cellulose membrane. Such a strategy effectively optimizes the structure of cellulose membrane, such as improved porosity (from 66.2 to 89%), enlarged specific surface area (from 7.99 to 12.86 m²/g), and increased water retention value (from 113.4 to 141.1%). As a result, the developed PCM shows excellent ion transport capacity and selectivity with a high t₊ of 0.88. The power density of PCM reaches up to 4.16 W/m², substantially exceeding that of the primary cellulose membrane. Moreover, the PCM harvests salt differential gradient energy very well with long-term stability, over 80,000 s with continuous operation. The PCM, utilizing sustainable and low-cost natural materials, shows considerable promise for renewable salt differential gradient energy harvesting.

Recently, various methods for cellulose dissolution without derivatization pretreatment have garnered attention for measuring the molecular weight of cellulose using gel permeation chromatography (GPC). However, conventional methods require complex pretreatment procedures or use substantial quantities of ionic liquids, which are expensive and exhibit high viscosities. Herein, we report a GPC method for the successful dissolution of cellulose in dimethyl sulfoxide (DMSO) containing 1 wt% 1-ethyl-3-methylimidazolium acetate (EmimOAc). The GPC method is simple, does not require special pretreatment steps, and dissolves cellulose at room temperature. Moreover, as the concentration of the ionic liquid was as low as 1 wt%, the method was robust at low pressures in the GPC system and had low operating costs for the ionic liquid. We demonstrate the applicability of this GPC method to various types of cellulose, including cotton, pulp, and rayon. The GPC profiles of EmimOAc/DMSO were comparable to those of the conventional GPC systems using lithium chloride/dimethyl acetamide in terms of the peak top molecular weight (and shoulder peak in the low-molecular-weight region). Therefore, this GPC method can contribute to the high-throughput evaluation of the molecular weights of native and regenerated cellulose.