Cellulose

Online ISSN: 1572-882X
Recent publications
Article
As a kind of melanin-like nanoparticles, poly(levodopa) nanoparticles have abundant reactive catechol groups, which provide the basis for the structure design of melanin-like nanoparticles. In this work, we synthesized silver/melanin-like nanoparticles (Ag-SMNPs) using a one-step method. The results of X-ray photoelectron spectroscopy (XPS) showed that the chemical structures of Ag-SMNPs were not only loaded with silver nanoparticles (Ag NPs), but also formed a complex structure with silver ions. Ag-SMNPs-modified fabrics (Ag-SMNPs@Cotton) had demonstrated excellent anti-ultraviolet radiation, photothermal, and antibacterial properties. UV protection levels of the modified fabrics had reached UPF50 + , and their surface temperatures had exceeded 100 °C when irradiated by a Xenon lamp for 1 min. As for the antibacterial activity, the survival rates of Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) on the surface of the modified fabrics were 1.94% and 5.92%, respectively, when the fabrics were irradiated by Xenon lamp for 10 min. Without Xenon lamp irradiation, the survival rates on the modified fabrics were 3.35% and 2.53% for E. coli and S. aureus, respectively, when bacteria were in contact with the fabric for 6 h. Additionally, the modified fabrics also maintained an outstanding air and moisture permeability. Multifunctional melanin-like nanoparticles provide a new option for material modification.

Article
Delignified wood (DW) was prepared from fast-growing poplar wood by delignification with a formic acid–water azeotropic system. Compressed wood (CW) was then obtained through a mechanical hot-pressing process. The effects of the delignification degree on the physical strength of the CW were studied. To further promote the strength of the wood, a new approach was proposed by embedding cellulose nanocrystals (CNCs) into DW followed by densification and producing the reinforced wood (RW). Here, CNCs were embedded in the wood, leading to reduced water uptake and remarkably enhanced dimensional stability, as well as generally improved mechanical properties. The test on the mechanical properties exhibited a significant improvement for the RW in contrast with the CW with maximum vickers hardness value (HV), flexural strength, tensile strength, and tensile elastic modulus of 800, 211 MPa, 183 MPa, and 14 GPa, which were increased by 12%, 22%, 11%, and 16%, respectively, compared to the CW. These results demonstrate that CNC is a promising enhancer to intensify the strength of wood. This work not only provides an effective and green approach to producing high-performance materials from fast-growing wood, but also improves the mechanical properties of wood without the introduction of heterocomponents. Graphical abstract The delignified wood (DW) was prepared using formic acid–water azeotropic system, and the degradation degrees of wood cellulose were further investigated by controlling the degree of delignification. Based on the preparation method of the compress wood (CW), the reinforced wood (RW) was obtained by combining delignification, embedding CNC and followed by densification.

Article
Degradation of formaldehyde (HCHO) in interior decoration has been an urgent issue due to its toxicity nature and potential threats to human health. In this work, manganese dioxide nanoparticles (MnO2 NPs) were in situ grown on the polydopamine (pDA)-templated cotton fabrics for environmentally friendly HCHO degradation applications. The morphology, elemental composition, and crystal structure of the cotton/pDA/MnO2 were characterized by scanning electron microscopy–energy dispersive X-ray spectrum, Fourier transform infrared, X-ray diffractometer and X-ray photoelectron spectroscopy, respectively. The degradation of HCHO by the as-developed cotton/pDA/MnO2 was measured in a self-made quartz reactor, and the stability of adsorption was evaluated by cyclic experiments. The results showed that the HCHO removal efficiency reached to 100% within 20 min after three cycles, suggesting that the as-prepared fabrics exhibited good stability for the degradation of HCHO. The development of MnO2 NPs coated fabrics provides new strategies in degradation HCHO in interior decoration.

Article
In the domain of energetic materials (EMs), the high-energy and high-safety EMs have infinite promising in modern defense weapons. Herein, this study prepared a novel nitrated bacterial cellulose/cyclotrimethylenetrinitramine (NBC/RDX) nanocomposite energetic material via a straightforward, mild and safe sol–gel method and freeze-drying technology. A unique and stable three-dimension (3D) porous network nanostructure of the composites was characterized by a series of analytical and test methods. It was found that the RDX crystals were distributed and imbedded uniformly in the NBC binder matrix, leading to the formation of nanometer-scale composites. The thermal properties presented remarkable decreased peak temperature (RDX: 236.60 °C → NBC/RDX-55%: 217.20 °C) and increased Ea (from 108.00 → 155.25 kJ/mol) during the decomposition process. Furthermore, thermal decomposition reaction kinetics and thermodynamics have also been calculated by two traditional methods: the Kissinger and Ozawa methods, indicating a promoted decomposition behavior compared with raw RDX and NBC. Moreover, TG-DSC-IR-GC–MS technology has been further conducted to probe the mechanism of decomposition, manifesting the formation of crosslinking structure of NBC gel matrix would decompose firstly and followed by the decomposition of RDX. Lastly, the sensitivity test demonstrated that the formation of 3D porous crosslinking network nanostructure of NBC gel matrix exerted remarkably desensitization effect when encountering external stimuli, and three categories of reduction sensitivity mechanism has been proposed. Hence, this synthesis strategy has profound basic theory research significance and may provide promising application of NBC/RDX nEMs used in high-energy and high-strength propellants.

Article
Ultraviolet (UV) protective cotton fabric is a convenient and reliable way to protect human body from sunlight. Herein, a polymerizable UV-absorber, 2-hydroxy-4-(3-methacryloxy-2-hydroxylpropoxy) benzophenone (BPMA) was prepared from the ring-opening addition reaction of 2,4-dihydroxybenzophenone (UV-0) with glycidyl methacrylate. The initiators tethered cotton fabric (CF-Br) was prepared by the immobilization of α-bromoisobutyryl groups. PBPMA grafted cotton fabric (CF-g-PBPMA) was fabricated via surface-initiated activators generated by electron transfer for atom transfer radical polymerization (SI-AGET ATRP). The results indicated that the structure of targeted polymerizable BPMA was defined, and PBPMA chains were successfully grafted from CF-Br to obtain CF-g-PBPMA. Compared with the UV protection factor (UPF) of the original cotton fabric (3.5), the UPF of CF-g-PBPMA achieved 79,630.2 at PBPMA polymerization degree of 404 due to the incorporation of 2-hydroxy benzophenone in repeating units of PBPMA. The as-prepared CF-g-PBPMA can be labeled as "Excellent UV Protection" according to the ASTM D 6603 with UPF values of above 40. Compared with the original cotton fabric, the CF-g-PBPMA displayed excellent superhydrophobicity with the water contact angle (WCA) increasing from 46° to 154° due to the increased surface roughness of cotton fabric induced by the accumulated PBPMA. After 200 washing cycles, the chemically bonded PBPMA enabled the CF-g-PBPMA outstanding durability with the WCA and UPF achieving 135° and 730.5, respectively. Graphical abstract

Article
Water-soluble polymers have been shown to improve the flow rigidity and water retention ability of highly-branched (flocculated) and polydisperse water-suspended MFC, thereby also modifying and controlling their rheological behaviour. The addition of hydroxyethyl (HEC) and carboxymethyl (CMC) celluloses of different content (5–10–20 w/w%), molecular weights (M W , 90.000–1.300.000 g/mol) and degrees of substitutions (DS, 0.7–1.2) to 1.5 wt% MFC suspension, have thus been studied by evaluating their microstructure (SEM imaging), strength and rheological properties, i.e. the yield stress and flow under rotational (viscosity vs. shear rate) and oscillatory (viscoelastic) regime, using cone-plate measuring geometry at a rather low truncation gap. The pure MFC suspension showed high-viscosity at lower shear stress and shear-thinning behaviour at higher rates, with two yielding zones, indicating a secondary deflocculation of smaller and more stiffly packed fibril structures and their orientation/aligning in the direction of flow. This behaviour was reduced substantially by the addition of high-M W HEC, or almost eliminated completely by medium-M W CMCs with higher DS, yielding suspensions with higher and stability-prolonged zero-shear viscosity, as well as a more linearly decreased and irreversible viscosity profile after the shear load removal at higher shear stresses. The carboxylic groups at CMC additionally decreased the interactions between the fibrils, and subsequently reduced the fibrils’ flocks, or formed larger aggregates with their integrations, while increasing the MFC suspension gel-strength, improving its flow and viscoelastic behaviour through higher water retention ability and surface tension properties, and also its recovery after deformation.

Article
The present study investigates the organosolv treatment of wheat straw, for the optimization of cellulose delignification, which will serve as raw material for the paper industry. The influence of temperature (130–180 °C) and reaction time (60–180 min) was investigated using an 87% acetic acid solvent concentration and a solid–liquid ratio of 1:25. The experiments were designed and evaluated using Response Surface Methodology with Central Composite Design (CCD). The response parameters were Kappa number and viscosity (ml/g). The optimal parameters of operation were 146.43 °C and 180 min of obtaining pulp with a Kappa number value of 16.30 and a viscosity value of 430.05 ml/g, with a value for holocellulose of 94.3% and 5.4% for Klason lignin. The samples were characterized by Fourier Transform Infrared (FTIR) and Scanning Electronic Microscopy (SEM). Visible effects of treatments were observed through SEM microscopy while the 1595 cm⁻¹ and 1510 cm⁻¹ peaks were reported to be bonds from lignin that presented a reduction in height and area peaks with the treatments. This study determined optimal temperature and time for the organosolv process at the lab scale and the viability of commercial delignification of cellulose from wheat straw with a constant solvent concentration and a constant solid–liquid ratio. Graphical abstract

Article
One interesting and sustainable method for the treatment of a large variety of surfaces is the atmospheric plasma technology. The use of plasma technologies can lead to physicochemical interactions between the plasma and the substrate material. Such interactions can result in a wide variety of molecular (creation of functional groups, radical formation, microscopic (roughness, etching, reduction of wood extractives and macroscopic (wettability, liquid penetration, surface energy) modifications of the substrate surface. Aim of this study was to take a deeper look on occurring molecular changes of cellulose by using spectroscopic methods. The treated materials were analyzed by Attenuated Total Reflection – Fourier Transform Infrared Spectroscopy (ATR-FTIR) and X-ray Photoelectron Spectroscopy (XPS). The evaluation of XPS detail-spectra and their separation into sub-spectra can be used to describe general changes in the chemical bonding states. For a better differentiation of the species produced by the plasma at the surface of the materials, specific derivatization reactions and subsequent analysis of the reaction products formed during derivatization are carried out in order to distinguish the different states of species that are present. The formation of oxygen-containing, polar functionalities on cellulose by plasma treatment could be confirmed. Chemical derivatization of cellulose in connection with subsequent XPS measurements showed the formation of O = C bonds in connection with the reduction of OH groups. In addition, the formation of carbonate groups on cellulose appears to be possible as a treatment effect, for which a corresponding reaction mechanism is discussed.

Article
Nanocellulose, a unique and promising nanosized cellulose fibers extracted from renewable biomass, has gained much attention from both the scientific and industrial communities due to abundant resources, good mechanical properties, distinct surface chemistry, and biological properties. Thus, nanocellulose is a appealing biomaterial for exciting applications, including super absorbent materials, electronic components, energy devices, and reinforcements. Cellulose nanocrystal (CNC), cellulose nanofibril (CNF), and bacterial cellulose (BC) are the three main kinds of typical nanocellulose from different routes, thus the comprehensive comparison of CNC, CNF, and BC is highly desirable. In order to better understand their special characteristics, we have described detailedly of CNC, CNF (including TEMPO oxidized CNF and mechanically ground CNF), and BC in current work. Meanwhile, this study systematically compared their preparation method, morphologies, chemical structure, surface chemistry, degree of polymerization, thermal behavior, mechanical property, and so on, all these are good for understanding the structure–property–function relationships of nanocellulose. The systematic comparative study can help to develop the criteria for selecting proper nanocellulose as biobased nanomaterials for high value-added applications. We believe that these detailed information presented here have the potential to achieve true sustainable, economic, and tailored production of nanocellulose at large scale, thus contributing to the advancement of biobased nanocellulose.

Article

Article
A bleached softwood kraft pulp was phosphorylated with (NH4)2HPO4 and urea at 150 ℃ for 0‒40 min, and the structures and properties of the resulting phosphorylated pulps were systematically investigated for the first time in terms of reaction time and the amount of (NH4)2HPO4 added. The phosphorous and weak acid group contents, and the weight recovery ratio increased with increasing reaction time, and were 1.9 and 4.5 mmol/g, and 114%, respectively, when the reaction time was 20 min. Therefore, numerous phosphate ester and weak acid groups were introduced into the pulp, maintaining its fibrous morphology and cellulose I crystal structure. It was found that almost all the ammonium phosphate groups in the phosphorylated pulp behaved as weak acids. The solid-state carbon-13 nuclear magnetic resonance (¹³C-NMR) spectrum of the phosphorylated pulp showed that neither carboxy nor carbamate groups were formed in the phosphorylated pulp; only phosphate ester groups were introduced into the pulp under the conditions used in the present study. The X-ray photoelectron spectra of the phosphorylated pulp surfaces suggested that ammonium phosphate groups were introduced into the pulp by phosphorylation. A longer reaction time or a greater amount of (NH4)2HPO4 added during phosphorylation resulted in lower water swelling behavior, indicating that some intrafiber and/or interfiber crosslinking occurred in the pulp under these conditions. The results obtained in the present study show that phosphorylated pulp fibers are suitable for the preparation of new functional cellulosic sheets and materials, in which large amounts of weak acid groups can be used as scaffolds for diverse ion-exchange sites. Graphical abstract

Article
Antimicrobial hydrogels have enticed a major concern for repairing soft tissues, particularly prohibiting bacterial infections that are frequently accompanied by impaired wound healing. Nevertheless, the development of new antibacterial hydrogel ingrained with excellent cell affinity is one of the robust challenges. This study aims for the first time to design a new class of antibacterial hydrogels with high biocompatibility through the formation of a water-soluble polyelectrolyte complex by performing a physical crosslinking reaction between the cationic trimethyl chitosan chloride (TMC) and anionic carboxymethyl starch (CMS) polymers. The structure of as-prepared hydrogels was characterized using different spectral and surface techniques including FTIR, ¹H-NMR, SEM, and XRD. The data stated that the hydrogels prepared with a high TMC content possess a high surface area and small pore size compared to other samples, suggesting more occurred interactions with CMS chains. Then, the antibacterial activity was investigated against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) as two pathogenic bacteria. The as-developed hydrogel with a high TMC mass achieved superior inhibition zones with diameters of 26 and 24 mm for E. coli and S. aureus, respectively, compared to that of pure TMC (20, and 18 mm). Moreover, the cytotoxicity of the hydrogels was examined against two normal cell lines such as VERO and lung (Wi38) cells lines. The cell viability of hydrogel was recorded 100% up to concentrations lower than 62.5, and 125 μg/mL for normal lung and VERO cell lines, respectively. Graphical abstract

Article
There have been many kinds of research about nanocellulose isolation and its characterization. However, there are gaps in quantitative conclusion according to previous findings about the difference effects of the isolation method on nanocellulose properties. In this study, a meta-analysis was carried out from 28 scientific journals and gathered 404 treatments. Fibre diameter and length, crystallinity index, onset temperature, and temperature at maximum degradation were analyzed using the independent t-test method. In contrast, using the independent t-test method, while tensile strength, tensile modulus, and elongation at break were analyzed by applying the standard mean difference method. Fibre diameter (t = −2.18, df = 28, p = 0.038*, x¯\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\overline{\text{x}}}$$\end{document} = −13.246, σ = 6.07, 95% CI −25.682 to − 0.81) and temperature at maximum degradation (t = −2.18, df = 57, p = 0.033*, x¯\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\overline{\text{x}}}$$\end{document} = −19.93, σ = 9.139, 95% CI −38.227 to − 1.626) were significantly affected by the isolation method as well as Tensile strength (gDiff = −1.12, SEdiff = −0.09, Zdiff = 13.21, P-val = < 0.001), tensile modulus (gDiff = −0.59, SEdiff = −0.14, Zdiff = 4.17, P-val = < 0.001), and elongation at break (gDiff = 4.61, SEdiff = −0.09, Zdiff = −49.57, P-val = < 0.001). In the other hand, fibre length (t = −2.612, df = 3.01, p = 0.079NS, x¯\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\overline{\text{x}}}$$\end{document} = −1090.05, σ = 417.25, 95% CI −2415.452 to 235.344), crystallinity index (t = 1.758, df = 38, p = 0.087NS, x¯\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\overline{\text{x}}}$$\end{document} = 10.453, σ = 5.945, 95% CI −1.583 to 22.488), and onset temperature (t = −1.463, df = 48, p = 0.141NS, x¯\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\overline{\text{x}}}$$\end{document} = −25.81, σ = 17.634, 95% CI −61.263 to 9.648) were not significantly affected by the isolation method.

Article
Bacterial nanocellulose (BNC) is an indomitable biomaterial of utmost usage in different technological areas. Previously, the BNC production has been reported in the simplified bioreactors. Thus, pioneering bioreactor-assisted strategies are desirable for the commendable BNC production. Advanced bioreactors must be corroborated along with different bacterial strains to obtain creditable BNC yield. This study deals with BNC production in rotary disc bioreactor (RDBR) using Gluconacetobacter xylinus NCIM 2526 strain. RDBR-based production of BNC provided 189 ± 14 gL⁻¹ of wet BNC, i.e., equivalent to 6.6 ± 0.3 gL⁻¹ dry BNC yield in 10 days. However, in static cultivation mode, 56 ± 12 gL⁻¹ wet weight of BNC, corresponding to 2.4 ± 0.4 gL⁻¹ dry weight, was produced. Thus, BNC production was approximately 2.75 folds higher in RDBR than statically produced BNC from the same volume of the media. The sugar to BNC conversion yield (12.2 ± 0.8%) was doubled in RDBR-based production as compared to static BNC production (6.2 ± 1.4%) with efficient sugar consumption (90.0 ± 3.3%). The maximum amount of BNC was produced at 7 RPM and pH 6. RDBR-based BNC showed a more hydrophilic nature than statically produced BNC. The RDBR might be appropriate for large-scale BNC production, especially for wet-end applications, as an ample amount of BNC can be produced from a single fermentation process. These BNC pellicles might have the potential for biomedical applications like wound dressings, biofacial masks, hydrogels, and tissue engineering scaffolds.

Article
In recent years, a new strategy of using citric acid (CA) to produce carboxylic cellulose nanocrystals (CNCs) has received attractive interest. However, mainly due to the weak acidity of CA, the CNC yield (about 10% without other assistance) is extremely low, which is the key factor that slows its advancement. This research applied short-time high-pressure microfluidizing to reinforce the production of CNCs after CA hydrolysis and investigated the effect of microfluidizing cycles on the yield and morphology of the CNC products, affording CNCs with good nanoscales (5–10 nm in diameter, 386–639 nm in length, 66–100 in aspect ratio and high yield (up to 56.8%). The prepared cellulose nanopaper (CNP) using the obtained CNCs showed highly transparency, high tensile strength (up to 178.51 MPa) as well as toughness (18.54 MJ/m³), and increased with the aspect factor of CNCs. Moreover, the presence of carboxylic groups (up to 0.60 mmol/g) was favorable to their dispersion stability. Furthermore, cellulose nanofibrils (CNFs) with high aspect ratio (98–147) were produced simultaneously after the separation of CNCs and more than 90% of the CA was easily recovered, which highly saved the consumption of mechanical energy and costs by deducing multi-cycles of centrifugation and large amounts of water usage which other CNC producing processes usually strictly required. The strategy proposed in this work opened up a new environment-friendly and economic route for the high-yield production of carboxylated CNCs with high aspect ratios and non-toxic CNC-based products that can be potentially used as platforms in wide range of applications. Graphical abstract

Article
Fabric-based flexible sensors prepared from carbon materials as conductive media have promising prospects in human motion detection, gesture recognition, and telemedicine services. Their electro-mechanical properties are influenced by the microscopic nanostructure of the carbon material and the type of fabric substrate. However, choosing suitable carbon materials to fabricate strain sensors for joint movement monitoring has received little attention. In this work, we selected cotton knitted fabrics (CKF) with structures of plain, 1 × 1 rib and 2 × 2 rib as a flexible substrate and reduced graphene oxide (rGO), carboxylic multi-wall carbon nanotubes (c-MWCNTs), and carbon black (CB) as the conductive medium using a scalable impregnation method to prepare rGO/CKF, c-MWCNTs/CKF, and CB/CKF sensors respectively. The electro-mechanical characteristics of the three-carbon material decorated fabric sensors were investigated and compared. The different structures’ knitted fabric sensors showed a bimodal curve under the stretch-release cycle at large elongation. The resistance models were developed to explain the bimodal phenomenon. Among three carbon materials, the fabric sensor made by graphene as a conductive material has the best electro-mechanical property. The rGO/CKF sensors showed highly stretchable and durable performance for joint activity monitoring, capable of being applied in smart clothes. Graphical abstract

Article

Article
Microcrystalline cellulose (MCC), a cellulosic functional material, is widely used in food, pharmaceutical and cosmetics industries. However, conventional methods for MCC preparation are challenging due to economic and environmental concerns. In this study, p-toluenesulfonic acid (p-TsOH) treatment was used to remove hemicellulose and lignin from corncob in order to achieve green preparation of corncob MCC (CC-MCC). It demonstrated that corncob hemicellulose was removed effectively by low concentration p-TsOH treatment, and corncob lignin was removed effectively by high concentration p-TsOH treatment. After p-TsOH treatment and hydrogen peroxide bleaching, about 30.2% porous CC-MCC was obtained directly. Compared with commercial MCC, acetylsalicylic acid tablets prepared by porous CC-MCC exhibited better sustained release performance. This research not only provides a green method for the corncob MCC preparation, but also realizes the resource utilization of corncob. Graphical abstract

Article
To obtain high performance of nanocomposite films made of cellulose nanofibrils (CNFs) and montmorillonites (MMTs), highly ordered nanostructures and abundant interfacial interactions are of extreme importance, especially for CNF film with high MMT content. Here, we tend to unveil the influence of exfoliation degree of MMTs and their interfacial interactions with CNFs on the properties of ensuing nanocomposite films. Monolayer MMTs (ML-MMTs) prefer to form highly ordered nanostructure during water evaporation induced self-assembly. The obtained nanocomposite film with 30 wt% ML-MMTs exhibits a tensile strength of 132 MPa, a total light transmittance of 90.2% (550 nm), and water vapor transmission rate (WVTR) of 41.5 g mm/m² day, better than the film made of original MMTs (O-MMTs) and CNFs (30 MPa strength, 60% transparency, and 78.7 g mm/m² day WVTR). Moreover, the physical properties (153 MPa strength and 20.9 g mm/m² day WVTR) of nanocomposite film can be further enhanced by constructing ionic interactions between the ML-MMT and CNF using 0.5 wt% cationic polyethylenimine (PEI). However, as the amount of PEI continues to increase, its performance will be deteriorated dramatically because of the disordered orientation of ML-MMTs. This work could provide an insight into the fabrication of high performance MMT/CNF nanocomposite film for advanced applications. Graphical abstract

Article
In this work, a photocatalytic nanocomposite, Fe-doped ZnO/nanocellulose, was synthesized using an in-situ method and examined for methylene blue (MB) degradation. For this purpose, pure ZnO (PZ) was synthesized by the chemical precipitation method and then subjected to Fe⁺³ doping with different concentrations of Fe³⁺ (1, 3, and 5 mol%). The PZ and Fe-doped ZnO (FZ) samples were characterized using several standard analyses. UV–Vis DRS analysis was also used to investigate the effect of Fe³⁺ doping on the bandgap of PZ. The doping of Fe³⁺ enhanced the photocatalytic activity of ZnO under visible light. The degradation efficiency of FZ samples (> 50%) was enhanced compared to the pristine ZnO (36.91%) during the same period. The catalyst with the highest degradation efficiency (94.21%) was then conjugated with broom corn stalk-derived nanocellulose (NC) at varying NC/Zn²⁺ molar ratios (0.1, 0.2, 0.3, and 0.4) and characterized by various analyses. The NC enhanced the hydroxyl group at the surface of the nanocomposite, consequently improved the photocatalytic performance of the synthesized samples. The ability of the optimized photocatalyst for MB degradation was assessed. The effect of operating parameters such as pH, catalyst dosage, and initial MB concentration was investigated and degradation efficiency of 98.84% was achieved at the optimum condition. Besides, photocatalyst regeneration study indicated the great photocatalytic performance of this nanocomposite with no loss in its degradation efficiency. The facile synthesis and fast degradation rate of this nanocomposite make it a promising candidate for real-world wastewater treatment. Graphical abstract

Article
A short-length cellulose nanofiber (CNF) aqueous sol, prepared by a high-pressure homogenizer, showed a rapid longer relaxation time (T2) in the low-field ¹H-nuclear magnetic resonance (NMR) when diluted from 20 wt% to 1 wt%. Magnetic stirring for 30 min disentangled the fiber networks and the fragmented fibers appeared in the 1 wt% CNF sol. A decrease in the specific viscosity of the diluted sols changed the rheological behavior from exponential to linear below 1 wt%, suggesting a significant decrease in the inter-fibril interaction. The small angle x-ray scattering (SAXS) with the generalized indirect Fourier transformation (GIFT) also indicated similar changes in the fiber flocculation structure without a change in the fiber size. The increasing viscosity upon severe fiber fragmentation by a high-pressure homogenizer may be ascribed to tighter holding of the interfibril water molecules. The time-domain (TD)-NMR fully supported the estimation that the transverse relaxation time (T2) showed consistently short for the 2 wt%, became shorter with the stirring time when diluted from 5 wt% to 2 wt%, and showed long upon dilution from 20 wt% to 2 wt%. Understanding the complex behavior of the highly viscous CNF sols during a simple dilution process may pave the way for developing CNF-related technology.

Article
Cellulose microspheres are commonly chromatographic media yet seriously limited in biomacromolecules separation and purification due to the slow mass transfer kinetics resulting from their narrow nanopores. Herein, a macroporous cellulose microsphere (MCM) with enhanced mass transfer ability has been successfully developed by an oil-in-water-in-oil (O1/W/O2) double emulsion strategy. The evolution profile of the double emulsion was tracked and achieved the optimization of interconnected macroporous structure. The macroporous structure not only provide fast mass transfer pathways for proteins but also increase the accessibility of meso/micropores. Benefitting from the macropores, the obtained diethylaminoethyl-modified MCM (DEAE-MCM) exhibits high permeability (3.81 × 10–13 m²), and fast adsorption rate (reaching equilibrium within 40 min) and high adsorption capacity (334.21 mg/g) for bovine serum albumin, far superior to commercially DEAE Sepharose Fast Flow. More importantly, under the high flow rate, DEAE-MCM remains a high dynamic adsorption capacity, promising it for fast protein chromatography.

Article
Biopolymer hollow spheres have shown great promise for wastewater treatment due to their unique structure and properties. However, challenging issues like low efficiency and poor recyclability still exist for most hollow spheres. In this study, the modification of chitosan/carboxymethyl cellulose (CS/CMC) with Fe3O4 nanoparticles for the formation of bifunctional CS/CMC-Fe3O4 hybrid hollow spheres were prepared using a facile two stage mixing route, which exhibited excellent adsorption and catalytic degradation of dyes. The removal ability of the synthesized hollow spheres towards acid blue-113 (AB) and reactive orange C-3R (RO) using persulfate oxidation system was greatly improved compared with single adsorption or catalysis. The removal ratio of AB and RO could reach up to 96.2 and 97.5%, respectively. The kinetic process conformed to the quasi-second-order kinetics and the adsorption process was the controlling step of dye removal. In addition, the created hollow spheres showed excellent environmental adaptability and regenerative capability. This study provides a convenient and practical method for catalyst loading on biomass hollow spheres, which has perspective applications in wastewater purification.

Article
Magnetic bentonite (MB) is a cheap, effective and recyclable adsorbent for the removal of many pollutants. However, further enhancing the adsorption performance of pristine MB and eliminating the instability of Fe3O4 magnetic particles in MB are vital and urgent for practical applications. Based on the principles of washing mesh bag and octopus tentacle, mesh-bag-like modifiers with tentacle-like structure of octopus were synthesized via grafted reaction of polyethylenimine (PEI) and carboxymethyl cellulose (CMC) to cover MB. As compared with the pristine MB, CMC-MB and PEI-MB, the magnetic bentonite adsorbent co-modified by PEI and CMC (CMC/PEI-MB) exhibited more multi-adsorption sites, stronger capture effects of tentacle for heavy metals and more effective mesh-bag-protection for Fe3O4. Attributed to these fascinating properties, CMC/PEI-MB achieved faster adsorption rates (the values of k2 of Pb(II) and Cd(II) were 73.0 g mg‒1 min‒1 and 17.4 g mg‒1 min‒1) and elevated adsorption capacities (760 mg g‒1 and 470 mg g‒1) for 1500 mg L‒1 Pb(II) and 1000 mg L‒1 Cd(II) in a wider pH range (3–7). Moreover, the reutilization rate of Pb(II) and Cd(II) over CMC/PEI-MB still remained 90% after five successive recycles. XRD and FT-IR results indicated that the structure of CMC/PEI-MB was well persevered after desorption, and the corresponding maximum desorption capacities of Pb(II) and Cd(II) from CMC/PEI-MB were 624 mg g‒1 and 362 mg g‒1 within 1 h, respectively. The findings of this study provide an interesting and effective approach for the construction of superior adsorbents basing on customary phenomena for the remediation of heavy metals from wastewater. Graphical Abstract

Article
Nanocellulose (NC) is a new biomass nanomaterial with at least one dimension in the nanoscale, prepared from plant fibers, animal, and bacteria. Nanocellulose combines important cellulose properties with the features of nanomaterials and open new horizons for materials science and its applications, such as biomaterials, optoelectronic devices, magnetic and etc. Owing to particular structures, superb properties and natural abundance, Nanocellulose has been diffusely researched as critical ingredient in the design of aerogels, sensors, pharmaceuticals, chiral materials and catalysts. This review focuses on the preparation and applications of nanocellulose-based fluorescent materials. The first part begins with a brief introduction of the nanocellulose. Subsequently, the autofluorescence behavior of nanocellulose is thoroughly discussed. And a variety of methods that have been used to fabricate nanocellulose-based fluorescent materials are proposed. Then, the applications of nanocellulose-based fluorescent materials are introduced in the fields of biomedicine, environmental monitoring, anticounterfeiting, explosives, drug trace detection, and etc. Finally, the future development opportunities and challenges of nanocellulose-based fluorescent materials are prospected.

Article
Nylon-cotton (NYCO) blend fabrics have been widely used recently; however, they are susceptible to ignition when exposed to flame. Herein, 3-glycidyloxypropyl trimethoxy silane (GPTMS) associated with polyethyleneimine (PEI) and phytic acid (PA) was incorporated on NYCO fabrics through the facile sol–gel and dip-nip-dry method to prepare flame retardant NYCO fabrics with enhanced washing durability. The limiting oxygen index (LOI) value of treated NYCO fabrics was increased from 18.5 to 29.8% and the damaged length was reduced from 30 to 7.5 cm. Cone calorimeter test indicated that the peak heat release rate and total heat release were decreased by 73 and 79% respectively, compared with that of the control NYCO fabrics. The flame retardancy was well maintained and showed self-extinguishing behavior after 20 laundering cycles. The char formation ability was reinforced and the possible flame retardant mechanism was proposed. Moreover, the dermal irritation test showed good biological safety of the fabrics, which were incapable to cause erythema and edema on rabbit skin. This study proposed a feasible method to produce flame retardancy, durability, and bio-safety nylon-cotton blend fabrics by textile finishing. Graphic abstract

Article
Crab chitin was sulfated under heterogeneous conditions using sulfamic acid in N’N-dimethylformamide to selectively sulfate the microfibril surface. The degree of sulfation followed a first order kinetics assuming a limited available reaction sites on the surface, and leveled off at a bulk degree-of-substitution of 0.4, corresponding to 2 mol/kg of sulfate groups. The reaction rate was proportional to the square of sulfamic acid concentration, suggesting involvement of two sulfamic acid molecules in a reaction. When washed with water after sulfation, the crab shell chitin fragments swelled anisotropically in the helicoidal axis direction, revealing regular alternating birefringence under optical microscope. Further mechanical treatment with high-pressure homogenizer led to slender nanofibrils, whose diameters were of the order of 6 nm according to turbidimetric analysis, in agreement with the Scherrer size estimated from X-ray diffraction line broadening. Both atomic force microscopy and transmission electron microscopy measurement showed presence of further smaller fragments with diameter of 3–4 nm and contour length of 0.5–1 μm\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\upmu \hbox {m}$$\end{document} with a few kinks. The current approach presents a rapid and efficient modification to chitin, and a strategy for the preparation of stable nanochitin suspension.

Article
Surface modification of fabrics is a powerful strategy that can endow fabrics with desired effects while keeping the intrinsic properties. Herein, an ordinary strategy, dipping-drying based layer-by-layer self-assembly (LbL) coating, is reported to functionalize fabrics’ surfaces. Firstly, the novel cation waterborne polyurethanes (QAHDPU) and anion waterborne polyurethanes (HDPU) are successfully designed and synthesized. By incorporating targeted molecule, hydantoin diol (HD) and quaternary ammonium salt with long alkyl chain (DOQA), the QAHDPU are antibacterial and hydrophobically functionalized. Taking advantage of strong adhesion, waterborne polyurethanes (WPUs) are physically bonded to surfaces of fabrics to generate durable antibacterial and hydrophobic fabrics. The QAHDPU with long alkyl chain combined with rough and porous fabric surface fabricates hydrophobic fabric surface, which can prevent bacteria from adhering to the fabrics. Furthermore, the coated fabrics present excellent antibacterial properties after chlorination, forming a second barrier against bacteria. The chlorinated coated fabrics, can inactivate 85.0–99.9% of Staphylococcus aureus and 85.0–97.7% of Escherichia coli with contact time of 60 min. The hydrophobic properties of coated fabrics are greatly improved with water contact angles of 122.0°–141.1°. In addition, the proposed method is applicable for a variety of fibers and expected to be used for industrial production. Graphical abstract

Article
Due to their specific physicochemical, capillary, and porous properties, the cellulosic sorbents from macrophytes have a high number of possible uses. The number of studies of alternative sources of cellulose is nowadays increasing. One of the most interesting cellulose-containing components of brown algae biomass is protein-cellulose complexes (PCC). The capillary and porous structure of protein-cellulose complexes of brown algae Laminaria digitata and Saccharina latissima was studied. The mesoporous structure of PCC was revealed using the nitrogen adsorption method. The surface area of protein-cellulose complexes is 5.31 m²/g and 2.94 m²/g for PCC S. latissima and PCC L. digitata, respectively. The adsorption of cationic methylene blue was more effective (maximum uptake capacity 24 mg/g) than anionic methyl orange (maximum uptake capacity 11 mg/g), which could be explained by the surface properties of protein-cellulose complexes and their charge, as well as the acid–base features of the dyes. The obtained results highlight the potential of the studied materials for the adsorption of organic toxicants. Graphical abstract

Article
A variety of liquid energy exists in papermaking engineering and has not yet been developed and utilized. In addition, for the papermaking industry, the presence of slime can seriously affect the quality of the finished paper and can lead to paper breaking. The current slime control strategies cannot completely solve the problem and also have some low toxicity. In this study, a method of self-powered sterilization of cellulose fibers by using triboelectric pulsed direct current is reported. A liquid–solid triboelectric nanogenerator (L–S TENG) was used to convert the liquid energy of nanocellulose suspension into electrical energy and convert this electrical energy into pulsed direct current for self-powered sterilization of cellulose fiber. A hydrophobic coating material is used as solid triboelectric material and electrode for sterilization. Driven by L–S TENG, the electrodes exhibited an excellent sterilization rate against four microorganisms including Escherichia coli, Aspergillus niger, Candida albicans, and Klebsiella pneumoniae, which from slime in the papermaking industry. This study could provide a basic research theory for liquid energy harvesting in the papermaking industry, and also provide a new strategy for pulp sterilization. Graphical abstract

Article
• Ryen Frazier
• Franklin Zambrano
• Joel J. Pawlak
• [...]
• Ronalds Gonzalez
Paper dusting, which occurs when a tissue web releases unbound and loosely bound fibers or filler particles during tissue-making or product manufacturing, has an overall negative impact, causing safety hazards, machine runnability difficulties, and product quality issues. To date, there are no well-established industry standards to quantify dusting/linting propensities in finished tissue products, thus evaluating the effectiveness of dust/lint control programs is challenging yet intriguing. This research aims to fill this gap by developing a methodology to characterize dusting in tissue papers. We have developed a device prototype (named the Tissue Dust Collector) and a methodology that together have been named the Tissue Dust Analysis System (TDAS), which aims at quantifying the propensity for tissue-grade paper products to generate dust/lint in a controlled and reproducible manner. Two samples, corresponding to commercial products with a low and high linting propensity, were tested using the proposed device and methodology, and the released particles were quantified and characterized. The device and methodology provided reproducible results for simulated consumer handling and product manufacturing scenarios. By changing the instrument's motor frequency, the force of agitation changes, mimicking/simulating consumer (60 strokes per min, spm) and producer/manufacturing (180 spm) handling scenarios (though manufacturing processes are much faster in practice). Particle counts at each level for each product showed reproducible values differentiable at different agitation levels. Adopting the proposed Tissue Dust Analysis System may help to characterize and understand the mechanisms behind dusting to create dust-control strategies that can alleviate this issue at its various sources or simply allow tissue paper manufacturers to compare and advertise their products based on dusting propensity.

Article
• Fangfei Liu
• Ruxangul Jamal
• Tursun Abdiryim
• Xiong Liu
Low-cost polysaccharides, such as cellulose, chitosan, chitin and alginate, have come into sight for water treatment. Nevertheless, their treatment efficiency and capability are sometimes unsatisfactory because of the lack of active sites and functionalities. In recent years, more and more attention has been paid to the integration of polydopamine (PDA) into polysaccharide-based materials to develop high-performance products for wastewater treatment. PDA modification can endow polysaccharides with plentiful functional moieties (including catechol, amine, and phenyl groups) for binding heavy metals and organic pollutants. PDA coatings may increase interfacial stability and hydrophilicity for oil/water separation. PDA also may anchor various catalysts for catalytic degradation of organic pollutants. Furthermore, the good light-harvesting capability and photothermal transformation feature of PDA are available for solar-driven water purification. This review aims to give the comprehensive overview on the development of PDA-based polysaccharide materials for water treatment. PDA-based polysaccharide materials can be made into cost-effective and high-performance products (including hydrogels, aerogels, membranes, beads and nanocomposites) for adsorption of heavy metals and organic pollutants, oil/water separation, catalytic degradation of organic pollutants, and solar-driven water purification. This review will give valuable information for the design and exploitation of PDA-based polysaccharide materials in water treatment.

Article
Aerogels are materials comprising hierarchical designs and are of growing significance to acquire advanced structure-based functionality in future technical applications. Since the researchers have previously focused on a single freeze-casting strategy in the fabrication of aerogels, the correlation between processing routes and their integrated characteristics could not be determined. Herein, we constructed cellulose nanofiber (CNF)/chitosan (CS) based composite aerogels (CCSA) by employing random and directional freeze-casting strategies. The effect of such techniques has been explored as a source of an integrated freeze-cast dried porous structure. Random freeze-dried aerogels (r-CCSA) exhibited isotropic properties with high porosity (99.6%) and large pore volume (2.71 mL/g). Whereas, controlled freeze ice-cast nucleation endowed the directional aerogels with ultra-low thermal conductivity (0.027 Wm⁻¹ K⁻¹) in the radial direction and about 20% greater (0.033 Wm⁻¹ K⁻¹) in the axial direction. Moreover, high BET-specific surface area (342 m²/g) and 60% strain adherence was observed for these anisotropic aerogels. This composite bio-mass aerogel preparation approach can offer a clear insight into the adoption of the right methodology considering the potential applications and environmental safety. Graphical abstract

Article
• Liuting Mo
• Shifeng Zhang
Aerogels, as attractive absorbents, have played essential roles in water treatment due to their light weight, high porosity, and exceptional absorption capacity. Nevertheless, conventional synthetic aerogel usually shows isotropic architectures, unsatisfactory mechanical performance, complex preparation process, and scale-limited fabrication, greatly limiting its applications in water remediation. In this study, inspired by the anisotropic architecture of natural wood, a biomimetic strategy was reported to prepare anisotropic, robust and environmental resistant aerogel composites via assembling semi-interpenetrating polymer networks (semi-IPNs) into the delignified wood template. The anisotropic structure endows the aerogel with excellent anisotropic mechanical behavior. The intermolecular hydrogen bonds of the cellulose microfibrils, the strong interfacial hydrogen bonds between cellulose chains and PI polymer networks, as well as the covalent bonds of semi-IPNs systems enable the aerogel composites to have a high yield strength of 566 kPa and Young’s modulus of 56.335 MPa. The resulting aerogel composite exhibits a high saturation adsorption capacity of 296 mg g⁻¹ at about 100 min for Cu(II) ions. The composite is easily regenerated and recycled five cycles without apparent removal efficiency loss. This study presents a promising, eco-friendly, low-cost, and feasible strategy for scalable fabricating anisotropic, robust, highly efficient, and environmental resistant aerogel composites for heavy metal ions removal. Graphical abstract

Article
The employment of atomic layer deposition and spin coating techniques for preparing inorganic–organic hybrid multilayer structures of alternating ZnO-CNC layers was explored in this study. Helium ion microscopy and X-ray reflectivity showed the superlattice formation for the nanolaminate structures and atomic force microscopy established the efficient control of the CNCs surface coverage on the Al-doped ΖnO by manipulating the concentration of the spin coating solution. Thickness characterization of the hybrid structures was performed via both ellipsometry and X-ray reflectivity and the thermal conductivity was examined by time domain thermoreflectance technique. It appears that even the incorporation of a limited amount of CNCs between the ZnO laminates strongly suppresses the thermal conductivity. Even small, submonolayer amounts of CNCs worked as a more efficient insulating material than hydroquinone or cellulose nanofibers which have been employed in previous studies.

Article
Solid–solid phase change materials (SSPCMs) have drawn substantial interest due to their excellent thermal energy storage performances and shape stability. Herein, a series of solid–solid phase change nanoparticles were successfully synthesized by grafting poly (ethylene glycol) (PEG, phase change working substance) onto cellulose nanocrystals (CNCs) support in a solvent-free reaction system. The as-synthesized CNC-based solid–solid phase change nanoparticles (namely CNC-g-PEG) exhibited good thermal stability and high thermal energy storage capacity. Additionally, the latent heat and phase transition temperature of CNC-g-PEG could be adjusted by changing the molecular weight of PEG. In particular, the CNC-g-PEG4K possessed a relative high melting enthalpy and crystallization enthalpy of 120.4 and 121.9 J/g at 53.7 and 37.1 °C, respectively. The CNC-g-PEG4K also exhibited excellent thermal reliability after 100 thermal cycles and was suitable for long-term practical application. This study proposes a promising approach for constructing sustainable solid–solid phase change nanoparticles which shows considerable potential applications in thermal energy storage and temperature control. Graphical abstract

Article
2,2,6,6-Tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidized cellulose nanofiber (TEMPO-CNF)/poly (vinyl alcohol) (PVA) suspension can be used to prepare composite. Therefore, understanding the viscoelastic property of TEMPO-CNF/PVA suspension is necessary. The analysis of the rheological date from static and dynamic rheology indicates that the suspension is pseudoplastic fluid with thixotropic behavior. When the concentration of PVA is in the dilute regime, the gel like behavior of the suspensions turns to liquid like state with the increasing frequency. Such behavior is correlated with the entangled network among cellulose fibrils and the hydrogen bond interaction between TEMPO-CNFs and PVA. When the concentration of PVA is in semidilute and entangled regime, the suspensions show liquid character, because the viscosity of the suspensions are mainly determined by the entanglement of PVA molecules in homogeneous state. Furthermore, the TEMPO-CNF/PVA membranes were prepared by solution casting method. The Fourier transform infrared spectroscopy and atomic force microscope data proved the interaction between TEMPO-CNFs and PVA. This research reveals the importance of PVA concentration on the fluid characters of TEMPO-CNF/PVA suspensions, providing the approach to adjust the viscosity of TEMPO-CNF suspensions. Graphical abstract

Article
As an effective substitute for ionic liquids (ILs), deep eutectic solvents (DESs) are known as a new generation of green solvents. In addition, DESs are considered to be the best solvents to replace traditional organic solvents and ILs due to their advantages of economy, simple preparation and biodegradability, which can be used to further break through the technical bottleneck in the field of biomass pretreatment. This study synthesized a series of choline chloride-based (ChCl-based) DESs and used them to pretreat microcrystalline cellulose (MCC) without dissolution, in order to achieve the purpose of improving the saccharification effect. DES-9 (ChCl/hydroquinone), DES-12 (ChCl/acetamide) and DES-16 (ChCl/acetic acid) were better pretreatment solvents. The optimum conditions for the pretreatment of MCC by DES-9 and DES-12 were both at 110 °C for 4 h, and the optimum condition of DES-16 was at 90 °C for 4 h. Compared with untreated MCC (26.66%), the saccharification yield of pretreated MCC with DES-16 increased by 20.5%. Finally, the structure and morphology changes of MCC before and after pretreatment were investigated in detail through the degree of polymerization (DP), SEM and enzyme adsorption. The results showed that DESs pretreatment made the surface of MCC become rough, which enhanced the accessibility of cellulose and enzymes, improving the saccharification effect. Graphical abstract

Article
Cellulose aerogels have been used in widespread areas, such as absorbents, thermal insulation material and medical material. Herein, we propose an effective strategy to fabricate elastic cellulose aerogels by combining cellulose nanofibers with polyvinyl alcohol (PVA) “glue”. The CA not only had a robust chemical-bond cross-link network, but also had a strong H-bond, which enhanced underwater mechanical properties. Moreover, the compressible CA provided a large number of nucleation sites for the growth of Metal–organic framework nanoparticles (ZIF-67 and ZIF-8) through interface self-assemble. The obtained aerogels with a low density of 9.8–11.2 mg cm⁻³ and highly porous of 99.4–99.5% possessed excellent elasticity both in air and underwater. The adsorption capacities of the MOF@CA for Pb²⁺ and Cu²⁺ are up to 123 mg g⁻¹ and 70.53 mg g⁻¹, respectively. The novel MOF@CA adsorbents with excellent mechanical properties display application prospects in the removal of heavy metals from wastewater.

Article
Phosphorus–nitrogen–silicon-containing coatings consisting of tris(hydroxymethyl)phosphine oxide (THPO), 3,5-diamino-1,2,4-triazole (guanazole), and polydimethylsiloxane (PDMS) were prepared via a simple spraying deposition technique and applied to the cotton fabric to impart flame retardancy and hydrophobicity. SEM image reveals that THPO/Guanazole/PDMS-coated fabric has a rough surface and XPS spectra confirm the composition of the coating on the cotton surface. Direct flame testing indicates that the as-prepared coating can protect the cotton from burning. The limiting oxygen index increased from 18.0% for the uncoated fabric to 32.0% for the THPO/Guanazole-treated sample and 27.0% for the THPO/Guanazole/PDMS-treated sample. Furthermore, with additional THPO/Guanazole, there was a gradual reduction in PHRR values, 60% (79.0 kW/m²) for C2 and 76% (48.2 kW/m²) for C3 lower than that of untreated cotton. After hydrophobic treatment of C2 with PDMS, the PHRR is reduced to 127.5 kW/m² (35.5% for C2-PDMS). Additionally, the coated cotton displays impressive hydrophobicity with a water contact angle of 133°. This unique approach provides a facile and effective flame retardant and hydrophobic treatment for cotton fabric.

Article
Corn fiber (CF) is an agroindustrial residue obtained from starch or corn syrup. Currently, there has been increasing research interest in lignocellulosic materials from these residual materials. Consequently, this paper is a novel approach that complements the structural and chemical characterizations already published in the literature for CF. In this study, isolation, chemical composition and characterization was conducted of hemicellulose by means of ¹H NMR and FTIR-ATR and Klason lignin by means of acid soluble lignin (ASL) and acid insoluble lignin (AIL) determination using UV spectrophotometry and Py–GC‒MS. Hemicellulose was obtained after aqueous extraction, lipid removal, delignification and alkaline extraction. The isolated hemicellulose from CF confirmed the presence of arabinoxylan, which was similar to the results reported in the literature. The CF contained 8.0% and 4.0% ASL and AIL, respectively. Regarding lignin, the study identified more than 47 primary pyrolysis products for ASL, with 17%, 20% and 59% relative molar abundance for lignin, carbohydrates, and other products, respectively, and 39 primary pyrolysis products with 44% and 7% relative molar abundance for lignin and carbohydrates, respectively. The main products derived from lignin were phenol, 4-methylphenol, guaiacol, 4-vinilguaiacol, syringol and syringylaldehyde. The peaks of lignin derivatives indicated that the Klason method is effective for lignin isolation, and the Py–GC‒MS technique allowed for the identification of the presence of residual lignin in AIL and ASL from CF. In this context, lignocellulosic components of CF are chemically suitable for use as raw materials to transform biomass into high value-added products. Graphical abstract

Article
This study compares two types of bioresorptive cellulose, i.e., calcium-sodium salt of oxidized cellulose (OC) and sodium salt of carboxymethylcellulose (CMC). It investigates which type would be preferable as an implant material in terms of biocompatibility, biomechanical and biological properties, and also in terms of its behavior in combination with collagen fibrils (Col) in composite Col/OC or Col/CMC scaffolds. OC significantly supported the stiffness and elasticity of Col fibrils, whereas CMC significantly reduced these properties. OC also enabled a strong interaction with Col fibrils even in a moist environment, accompanied by a significant drop in elastic modulus. The addition of cellulose did not significantly influence scaffold porosity; however, changes in surface morphology and the lower swelling capacity of OC, with a degree of oxidation of its chains between 16 and 24%, supported the idea of improved cell-material interaction. The elasticity and the stiffness of Col/OC guided human adipose-derived stem cells (hADSCs) to significantly higher adhesion, proliferation, and metabolic activity. On the contrary, the Col/CMC provided only limited mechanical support for the cells and inhibited their attachment and proliferation, although without any signs of cytotoxicity. This phenomenon could be used for future control of the differentiation of hADSCs towards a desired phenotype to generate advanced tissue replacements using modern methods of tissue engineering. The oxidation of cellulose resulted in a firmer scaffolding material, as required in vascular or skin tissue engineering. CMC is suitable for moist wound healing, e.g. as a mucoadhesive gel, where cell adhesion is not desirable. Graphical abstract

Article
Smart cotton fibers with temperature-driven sensitivity were developed by simple finishing with poly(N-vinylcaprolactam-co-tricyanofuranhydrazone);PVCH.Vinyl-bearing tricyanofuranhydrazone was prepared by an azo-coupling of 2-allyloxy-4-nitroaniline diazonium salt with tricyanofuran. Poly(N-vinylcaprolactam) labeled with tricyanofuranhydrazone probe was then prepared in situ by free radical polymerization. The chemical formulae of the hydrazone chromophore and PVCH were examined by FTIR, NMR and CHN elemental analysis. The PVCH-finished cotton functioned as a thermochromic assay producing an instantaneous colorimetric change from yellow to purple when the temperature increases from 34 to 49 °C. Changes in color were studied by the CIE Lab color parameters. The absorbance spectra showed a temperature-driven red shift from 429 to 564 nm. This can be attributed to the formation of push-π-pull hydrazone type chromophore due to temperature-driven proton abstraction leading to intramolecular charge transfer. The surface morphology of cotton immobilized with poly(VC–co–H) nanofibers was examined by scanning electron microscope (SEM) and infrared spectroscopy (FT-IR). The PVCH nanofibers were also inspected by transmission electron microscopy (TEM), showing fibers with diameter of 2–10 nm and length of 148–152 nm. No considerable defects were detected in bending length and permeability to air of the PVCH-finished fibers. In addition, high colorfastness properties were observed for the treated cotton substrates. Upon exposure to gaseous ammonia, the vapochromic cotton was able to rapidly change color from yellow to purple, and then recover back to yellow instantly when removing the vapochromic fabric away from the ammonia source. The current cotton assay showed a detection limit (LOD) of 10 to 250 ppm for aqueous ammonia. The cytotoxic properties of the thermochromic cotton fibers were also examined. Mechanistic study accounting for the thermochromic activity of poly(N-vinylcaprolactam-co-tricyanofuranhydrazone) is proposed.

Article
To explore polysaccharides for developing energetic biopolymers, a promising energy-rich nitrochitosan (NCS) was successfully prepared through electrophilic nitration of chitosan. The chemical structure and morphology of the synthesized NCS and its precursor were confirmed by infrared spectroscopy, elemental analysis, and scanning electron microscopy. The energetic performance, thermal behavior, and degradation kinetics of NCS were also evaluated. The results showed that the designed nitrogen-rich (Nc = 16.79 %) NCS presents excellent energetic features, such as a calorific value of 10573 J/g, a density of 1.708 g/cm3, an impact sensitivity of 15 J, and a detonation velocity of 7788 m/s, which are markedly better than those of NC and GAP. Meanwhile, the thermal investigation based on deconvoluted non-isothermal DSC experiments combined with isoconversional kinetic methods indicated that NCS displays two consecutive exothermic decomposition events within the temperature range of 133-180 °C and 185-240 °C, and exhibits apparent activation energies of 74 kJ/mol and 152 kJ/mol, respectively, which are lower than the common thermolysis energy range of NC (140-190 kJ/mol), demonstrating the improved reactivity of the aforementioned energetic NCS. Overall, this study established that NCS could serve as an outstanding energetic polysaccharide for potential application in high-performance composite explosives and solid rocket propellants.

Article
Introducing deterrents improves the thermal stability of nitrocellulose of propellant surface, but is accompanied with inevitable problems, such as migration, residue, smoke flame, and so on. In this paper, sodium carboxymethyl function groups were chemically grafted to nitrocellulose molecular chains by reaction of denitration and following etherification, which provided thermal stability, flame suppression ion without deterrent migration. Various structure characterizations were conducted and confirmed the sodium carboxymethyl-nitrocellulose (CMNC) was prepared successfully. The number of sodium carboxymethyl groups linked to nitrocellulose chains was affected by both denitration and etherification. The results of thermal analysis showed that the thermal stability of CMNC improved with the increase of bearing sodium carboxymethyl groups and was better than that of original NC sample. Meanwhile, the thermal decomposition behaviors and decomposition products of CMNC are similar to that of NC at temperature of the first DTG peak Tmax and that of CMC at temperatures of the second DTG peak T2. This work provided a way for designing gun propellant with progressive burning, anti-migration and flame suppression simultaneously.

Article
Cotton fabrics are popular for their excellent properties, but their property of creasing easily largely limits the wide application of cotton fabrics. In this paper, an organosilicon resin emulsion containing disulfide bonds was prepared with epoxy-terminated silicone oil and 4,4-diaminodiphenyl disulfide (AFD) as raw materials, and it was used as a finishing agent for the elastic finishing of cotton fabrics. The effects of raw material ratio on the elastic properties of organosilicon polymer film and the effects of emulsifier dosage and emulsification time of emulsion polymerization on the properties of organosilicon resin emulsion were studied. In addition, the effects of organosilicon finishing agent dosage, curing temperature, and curing time on the elastic properties of cotton fabric were also studied. The research results show that the average particle size of the prepared organosilicon resin emulsion is about 250 nm, the particle size distribution is concentrated and the emulsion is stable. The delayed elastic recovery angle of the cotton fabric treated with an organosilicon finishing agent can reach 185°, showing excellent high delayed elasticity. At the same time, it was found that the finished cotton fabric exhibited an excellent and special temperature-responsive shape memory function based on the existence of disulfide bonds in the organosilicon polymer network structure.

Article
Cellulose nanocrystals (CNCs) are renewable, biodegradable and biocompatible nanomaterials that exhibit unique mechanical, optical, rheological and barrier properties useful for a variety of applications. Since CNCs remain an expensive product, coupling its production to pulp and paper products could reduce the production costs. However, pulp and paper mills do not always use a single wood species and so, differences in CNC properties based on the feedstock must be delineated. This work reports on the production and characterization of CNCs from three hardwoods, i.e. white oak, sweetgum and cottonwood, and one softwood, i.e. loblolly pine. Stable aqueous CNC dispersions were obtained from pre-extracted and fully bleached kraft wood pulps. CNC yield (with respect to pulp) ranged between 60 and 80% w/w, and a linear regression model explaining the relationship between CNC yield and pulp cellulose to lignin ratio was found significant (R² = 0.99 and p value = 0.0044). Sweetgum CNCs had the highest yield and purity, indicating the usefulness of this unconventional raw material for scalable production of high-quality CNCs. Pine CNCs were characterized by the largest length (150–200 nm vs 100–150 nm for the rest), whereas cottonwood CNCs displayed the lowest width (6 nm vs 14–17 nm for the rest) and consequently the highest aspect ratio (~ 20 vs ~8–13 for the rest) as well as the highest Young’s modulus (1780 GPa vs 100–300 GPa for the rest). A linear regression model explaining the relationship between Young’s modulus and CNC aspect ratio was found significant (R² = 0.92 and p value = 0.0387). Other physicochemical properties, such as crystallinity index, surface charge, polydispersity index and surface roughness, were similar for CNCs derived from all four species; however, thermal degradation behavior of oak CNCs was slightly different from that of the remaining CNCs (lower Thalf and residual weight). Findings in this study indicate the potential to tune the quantity (yield) and quality (purity and properties) of CNCs based on the type of wood species chosen as the feedstock, thus having a direct impact on production economics and end use in different applications. Graphical abstract

Article
In this study, calcium oxide (CaO) was used as an additive to form pores in a cellulose acetate (CA) and at the same time improve the thermal stability of the cellulose acetate. When the CA/CaO membrane was exposed to water pressure, the CA matrix area plasticized by the CaO particles became weakened and water channels were formed. In addition, the high melting point of CaO and its bonding with the carbonyl group of CA caused a crosslinking effect. We succeeded in manufacturing a porous separator with a high porosity of 73.1% and a high flux value of 92.25 L/m² h at 8 bar. Furthermore, TGA measurements revealed an increase of thermal stability by 50 °C. The pores generated in the cellulose acetate film were confirmed using a SEM and mercury porosimeter. Thermal stability and interactions in materials were measured using TGA and FT-IR. By improving the thermal stability of inexpensive and eco-friendly cellulose acetate, the potential for commercialization of battery separators was proposed.

Article
Micro crystalline cellulose is mostly used to improve thermo-mechanical properties of composites. This study aims to evaluate the creep behaviour of micro-cellulose epoxy-based composites, and the effect of silanization treatment on the reinforcements. A new viscoelastic model, based on the generalized logistic function was successfully tested. The results were directly associated with the material’s structure–property relationships. Rigid particles restricted the molecular chain’s motion, mainly on the amorphous segments. This difference achieved the needing of more energy, to achieve creep deformation. Then, MCC improved the structural integrity, when incorporated into an epoxy matrix. On one hand, the incorporation of silanized-MCC increased the mechanical behavior of the composite, due to the stiffer structure. Furthermore, the chemical modification provided an increment in the glassy plateau, associated with higher thermal energy required to initiate strain of the amorphous polymeric chains. This behaviour resulted in an abrupt decrease of load-bearing capability for the composites. Finally, the proposed model is suitable to be employed in creep curves, aiming to easily interpret the structure–property relationships of this test. Graphical abstract

Article
The study describes the preparation of nanocellulose from organosolv hemp pulp and its application in the production of food packaging paper as an alternative to petroleum products. OHP was obtained from renewable plant materials hemp fibers by extraction with NaOH solution and cooking using a mixture of acetic acid and hydrogen peroxide. A stable transparent nanocellulose gel was extracted from OHP by acid hydrolysis followed by ultrasonic treatment. It was found that an increase in the consumption of sulfuric acid, temperature and duration of the OHP hydrolysis process improved the quality indicators of hemp nanocellulose. A linear dependence of the tensile strength and transparency of nanocellulose films on their density has been established. Morphological (SEM), structural (FTIR and XRD) and thermal analysis (TGA) of hemp fibers, OHP and nanocellulose were carried out. Nanocellulose films had a density of up to 1.56 g/cm³, a tensile strength of up to 66.7 MPa, a transparency of up to 87.3%. Atomic force microscopy method showed that the transverse dimension of nanocellulose particles is from 8 to 23 nm. Hemp nanocellulose had a higher crystallinity index (87.2%) than OHP (72.0%), but lower thermal stability. The positive effect of adding nanocellulose from hemp on improving all quality parameters of paper for food packaging has been shown. The addition of 2% hemp nanocellulose makes it possible to obtain paper that exceeds the breaking force requirements of premium grade paper by 40%, and the breaking length increases by 42% compared to paper without chemical additives.

Top-cited authors
• Grenoble Institute of Technology
• Luleå University of Technology
• Universiti Kebangsaan Malaysia
• French National Centre for Scientific Research
• University of Tehran