Oxidized Cellulose Nanofibers Research Articles

Controlling the Magnetic Responsiveness of Cellulose Nanofiber Particles Embedded with Iron Oxide Nanoparticles.

2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofiber (TOCN) particles, an innovative biobased material derived from wood biomass, have garnered significant interest, particularly in the biomedical field, for their distinctive properties as biocompatible particle adsorbents. However, their microscopic size complicates their separation in liquid media, thereby impeding their application in various domains. In this study, superparamagnetic magnetite nanoparticles (NPs), specifically iron oxide Fe3O4 NPs with an average size of 15 nm, were used to enhance the collection efficiency of TOCN-Fe3O4 composite particles synthesized through spray drying. These composite particles exhibited a remarkable ζ-potential (approximately -50 mV), indicating their high stability in water, as well as impressive magnetization properties (up to 47 emu/g), and rapid magnetic responsiveness within 60 s in water (3 wt % Fe3O4 to TOCN, 1 T magnet). Furthermore, the influence of Fe3O4 NP concentrations on the measurement of the speed of magnetic separation was quantitatively discussed. Additionally, the binding affinity of the synthesized particles for proteins was assessed on a streptavidin-biotin binding system, offering crucial insights into their binding capabilities with specific proteins and underscoring their significant potential as functionalized biomedical materials.

Fabrication of Loose Nanofiltration Membrane by Crosslinking TEMPO-Oxidized Cellulose Nanofibers for Effective Dye/Salt Separation.

Dye/salt separation has gained increasing attention in recent years, prompting the quest to find cost-effective and environmentally friendly raw materials for synthesizing high performance nanofiltration (NF) membrane for effective dye/salt separation. Herein, a high-performance loose-structured NF membrane was fabricated via a simple vacuum filtration method using a green nanomaterial, 2,2,6,6-tetramethylpiperidine-1-oxide radical (TEMPO)-oxidized cellulose nanofiber (TOCNF), by sequentially filtrating larger-sized and finer-sized TOCNFs on a microporous substrate, followed by crosslinking with trimesoyl chloride. The resulting TCM membrane possessed a separating layer composed entirely of pure TOCNF, eliminating the need for other polymer or nanomaterial additives. TCM membranes exhibit high performance and effective dye/salt selectivity. Scanning Electron Microscope (SEM) analysis shows that the TCM membrane with the Fine-TOCNF layer has a tight layered structure. Further characterizations via Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) confirmed the presence of functional groups and chemical bonds of the crosslinked membrane. Notably, the optimized TCM-5 membrane exhibits a rejection rate of over 99% for various dyes (Congo red and orange yellow) and 14.2% for NaCl, showcasing a potential candidate for efficient dye wastewater treatment.

Soil-inspired multi-stage heterogeneous nanochannel membranes for enhanced osmotic energy conversion

The nanofluidic ion transporting channels for harvesting blue osmotic energy between river water and seawater have received great attentions recently. However, the design of excellent ion selective nanochannel membranes while retaining high mechanical strength and ion flux remains a challenge. Herein, we present a novel multi-stage heterogeneous nanochannel membranes consisting of alternating TEMPO oxidized cellulose nanofibers (TOCNFs) and MXene layers inspired by the multi-layer structure of natural soil. The ingenious binding of “soft layer” of TOCNFs acting as ion selective layer and “hard layer” of MXene acting as ion permeable/structural support layer contributes to the fast cationic transport through the robust nanochannel membranes. In hypersaline solutions, a remarkable power density of 95.13 W m−2 is produced. This work provides a new strategy for heterogeneous nanochannel membranes for osmotic energy generation.

Rational design of MXene/MWCNT/TOCNF film for flexible supercapacitor

Two-dimensional (2D) MXenes are widely acknowledged as highly adaptable materials for flexible supercapacitors due to their high electronic conductivity, tunable surface chemistry, structural adaptability, and excellent mechanical strength. However, pure MXene nanosheets have a tendency to stack together, which decreases the mechanical and electrochemical properties for flexible devices. Herein, inspired by the structure of modern architecture, MXene/MWCNT/2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) radical-mediated oxidized cellulose nanofibers (TOCNFs) (MMT) composite film (MMT-X, the content of MWCNT and TOCNFs is X% of the total weight of the film) is manufactured using a simple vacuum filtration method. In MMT, two-dimensional (2D) MXene is severed as nanometer “bricks”, one-dimensional (1D) TOCNFs is used as a nanometer “mortar” between MWCNTs and MXene based on synergistic electrostatic forces and hydrogen bonding to build a three-dimensional (3D) composite structures with excellent mechanical strength. The flexible MMT-8 film is used as a supercapacitor electrode with specific capacity 856 F cm-3. Furthermore, at a volume power density of 335.5 W L-1, the assembled flexible all-solid-state supercapacitor (ASSC) could provide a volumetric energy density of 11.64 Wh L-1 with good cycle stability.

Revalorization of Yerba Mate Residues: Biopolymers-Based Films of Dual Wettability as Potential Mulching Materials.

Biodegradable mulching films are a very attractive solution to agronomical practices intended to achieve more successful crop results. And, in this context, the employment of agricultural and industrial food residues as starting material for their production is an alternative with economic and environmental advantages. This work reports the preparation of bilayer films having two different wettability characteristics from three bio-derived biopolymers: TEMPO-oxidized cellulose nanofibers isolated from infused Yerba Mate residues, Chitosan and Polylactic acid. The infused Yerba Mate residues, the isolated and oxidized cellulose nanofibers, and the films were characterized. Nanofibrillation yield, optical transmittance, cationic demand, carboxyl content, intrinsic viscosity, degree of polymerization, specific surface area and length were studied for the (ligno)cellulose nanofibers. Textural and chemical analysis, thermal and mechanical properties studies, as well as water and light interactions were included in the characterization of the films. The bilayer films are promising materials to be used as mulching films.

Pickering emulsions of thyme oil in water using oxidized cellulose nanofibers: Towards bio-based active packaging

The antioxidant and antimicrobial properties of thyme essential oil (TEO) are useful for active food packaging, but its poor aqueous solubility restricts its applications. This work involves anionic cellulose nanofibers (CNFs) as the sole stabilizing agent for TEO-in-water emulsions, with oil concentrations ranging from 10 mL/L to 300 mL/L. A double mechanism was proposed: the adsorption of CNFs at oil/water interfaces restricted coalescence to a limited extent, while thickening (rheological stabilization) was required to avoid the buoyance of large droplets (>10 μm). Thickening effects comprised both higher viscosity (over 0.1 Pa·s at 10 s−1) and yield stress (approximately 0.9 Pa). Dilute emulsions had good film-forming capabilities, whereas concentrated emulsions were suitable for paper coating. Regarding antimicrobial activity, CNF-stabilized TEO-in-water emulsions successfully inhibited the growth of both Gram-negative (E. coli, S. typhimurium) and Gram-positive bacteria (L. monocytogenes). As for the antioxidant properties, approximately 50 mg of paper or 3–5 mg of film per mL of food simulant D1 were required to attain 50 % inhibition in radical scavenging tests. Nonetheless, despite the stability and the active properties of these bio-based hydrocolloids, providing this antioxidant and antimicrobial activity was incompatible with maintaining the organoleptic properties of the foodstuff unaltered.

Decoration of carbohydrate nanocomposite with silver nanoparticles for highly efficient adsorption of methylene blue and antimicrobial against human pathogens

The current study aims to prepare carbohydrate nanocomposite based on 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) oxidized cellulose nanofibers (CNFs) /chitosan chloride (Ch) decorated with silver nanoparticles (Ag-NPs) and designed as (TEMPO/CNF/Ch/Ag-NPs) that was investigated as antimicrobial materials and applied as efficient sorbent. CNF was prepared from cellulose through TEMPO oxidation-mechanical defibrillation technique. Anionic CNF and Ch were ironically interacted to prepare novel sustainable ionic nanofibers films. Ag-NPs having approximately 20 nm were prepared in situ to decorate the ionic fibers. The effects of experimental parameters including media pH (3.0–8.0), contact time (10–120 min), and initial methylene blue (MB) concentration (50–800 ppm) on the adsorption behavior of MB onto nanocomposite films were evaluated. The results exhibited similar and fast adsorption kinetic, as illustrated by the pseudo-second-order model. The adsorption results were best suited by the Langmuir isotherm model, and the maximum adsorption capacity for the TEMPO/CNF/Ch and TEMPO/CNF/Ch/Ag-NPs nanocomposite was 369 and 432 mg/g, respectively, at the optimized media pH of 7 with a contact time of 60 min at 88 to 90 mg/g of MB. In kinetic studies, the pseudo-second-order model for nanocomposite films provided the best fit (R2 = 0.98), than pseudo-first-order model (R2 = 0.82 and 0.77). The TEMPO/CNF/Ch and TEMPO/CNF/Ch/Ag-NPs nanocomposite retains 73 and 69% of its initial adsorption performance towards MB after five consecutive runs. The formed nanocomposite showed excellent efficacy against Escherichia coli (14.3 ± 0.57 mm), followed by Candida albicans (12 ± 1 mm), Staphylococcus aureus (11.3 ± 1.15 mm), and Streptococcus mutans (10.6 ± 1.15 mm), and their antimicrobial activity was enhanced by the incorporation of Ag-NPs. The formed nanocomposite might find applications in industrial and biomedical fields.

Hierarchical porous triboelectric aerogels enabled by heterointerface engineering

The concept of the "Internet of Things" has made smart materials essential for sensing, responding to, and adapting to real-time feedback from the external environment. Cellulose aerogels hold immense potential in the field of smart triboelectric materials. However, conventional cellulose aerogels often face issues such as structural fragility, which limits their potential as smart materials. In this study, a compressible cellulose triboelectric aerogel with a hierarchical porous structure was prepared through heterointerface engineering. By introducing a heterointerface between oxidized cellulose nanofibers (TCNF) and carbon nanotubes (CNT), the structural stability of the material was significantly improved. The aerogel exhibited a 40-fold improvement in compressive performance and demonstrated excellent porosity (97.23%). A triboelectric nanogenerator was constructed using this material to explore its potential as a smart material. Experimental results indicated that the aerogel exhibited high sensitivity to ammonia gas, accurately identifying variations in NH3 concentration within the range of 20–150 ppm, with excellent linearity (R2 =0.996). Moreover, utilizing this triboelectric gas sensor as a wireless sensing terminal in smart devices enabled successful real-time wireless detection of food spoilage processes. This research provides new insights into the development of smart materials made from aerogels and has significant research and practical value for expanding the utilization of cellulose-based aerogels.

Construction of metal-organic framework/cellulose nanofibers-based hybrid membranes and their ion transport property for efficient osmotic energy conversion

The development of advanced nanofluidic membranes with better ion selectivity, efficient energy conversion and high output power density remains challenging. Herein, we prepared nanofluidic hybrid membranes based on TEMPO oxidized cellulose nanofibers (T-CNF) and manganese-based metal organic framework (MOF) using a simple in situ synthesis method. Incorporated T-CNF endows the MOF/T-CNF hybrid membrane with a high cation selectivity up to 0.93. Nanoporous MOF in three-dimensional interconnected nanochannels provides massive ion transport pathways. High transmembrane ion flux and low ion permeation energy barrier are correlated with a superior energy conversion efficiency (36 %) in MOF/T-CNF hybrid membrane. When operating under 50-fold salinity gradient by mixing simulated seawater and river water, the MOF/T-CNF hybrid membrane achieves a maximum power density value of 1.87 W m−2. About 5-fold increase in output power density was achieved compared to pure T-CNF membrane. The integration of natural nanofibers with high charge density and nanoporous MOF materials is demonstrated an effective and novel strategy for the enhancement of output power density of nanofluidic membranes, showing the great potential of MOF/T-CNF hybrid membranes as efficient nanofluidic osmotic energy generators.

Accelerated ageing of 3D printed water purification filters based on PLA reinforced with green nanofibers

This study investigates the ageing behavior of polylactic acid (PLA) and PLA-based biocomposites reinforced with either 2,2,6,6-tetramethylpiperidine 1-oxyl radical (TEMPO) - oxidized cellulose nanofibers (TCNF) or chitin nanofibers (ChNF) in water. Fused deposition modeling (FDM) was used to create water filters, which underwent aging tests at various temperatures over 19 weeks. Thermomechanical results show that while the addition of TCNF and ChNF improves the mechanical performance of PLA-based filters in dry conditions, it has the opposite effect after exposure to water. The impact of prolonged water exposure on Young's modulus and toughness was more significant in biocomposites than in unmodified PLA filters. The TCNF/PLA and ChNF/PLA filters saw a substantial ∼10 °C drop in glass transition temperature (Tg) after 3 weeks, while pure PLA remained nearly unaffected for up to 7 weeks. The mechanical tests allowed to estimate the service life of the 3D printed filters using the Arrhenius model. It was shown that the TCNF/PLA and ChNF/PLA filters can be utilized at room temperature water for up to 8 and 5 months, respectively, until they lose 50 % of their initial ability to resist deformation. In the same conditions, PLA filters can serve for up to 3.5 years. In conclusion, this study highlights the importance of considering the degradation behaviour of biocomposites when developing sustainable materials for water treatment applications.

Modification of TEMPO-oxidized cellulose nanofibers as a source of potassium and its impact on onion plant

This research study aims to improve the productivity and vegetative growth characteristics of onion to meet local demands and the volume of exports. This was done by the application of foliar nano-fertilizers based on cellulose nanofibers (CNF). TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) -oxidized cellulose nanofibers (TO-CNFs) were fabricated using the TEMPO-oxidized method in the presence of sodium or potassium hydroxide to obtain sodium carboxylate TO-CNFs (N-CNF) and potassium carboxylate TO-CNFs (K-CNF), respectively. Also, potassium acrylate was used in grafting N-CNF to get potassium polyacrylate-g-sodium carboxylate TO-CNFs (G-CNF). The prepared CNFs were described via various techniques such as FTIR, SEM, TGA, and XRD. X-ray analysis demonstrated that N-CNF, K-CNF, and G-CNF consisted of a crystalline domain of crystallinity index 0.45, 0.41, and 0.55, respectively. K-CNF showed marginally lower thermal stability than N-CNF influenced by its crystalline properties. The vegetative growth and the yield of onion plants, plus the content of photosynthetic pigments, minerals, cellulose, hemicellulose, and lignin, as well as total phenols, flavonoids, and indoles, were studied. The results showed that the application of K-CNF as a foliar nano-fertilizer improved the onion yield and the content of elements, protein, total soluble solid, phenols, and indoles as well as the content of cellulose and lignin

Structural and rheological insights of oxidized cellulose nanofibers in aqueous suspensions

Structural and rheological insights of oxidized cellulose nanofibers in aqueous suspensions

Incorporating of Oxidized Cellulose Nanofibers@d-Limonene Pickering Emulsion into Chitosan for Fully Biobased Coatings toward Fruits Protection

Incorporating of Oxidized Cellulose Nanofibers@<scp>d</scp>-Limonene Pickering Emulsion into Chitosan for Fully Biobased Coatings toward Fruits Protection

Effective electromagnetic interference shields based on cellulose nanofibers-carbon nanotubes layered composites

The rapid development of electronic devices and communication technologies has inadvertently led to the production of significant amounts of Electromagnetic Interference (EMI) and radiation, necessitating the development of sustainable, low-density, affordable, and high-performance EMI shielding materials. The present study involves fabricating a layered composite material comprising alternating substrate and conducting layer made primarily of TEMPO-mediated oxidized cellulose nanofibers (TCNF) and carbon nanotubes (CNT). For the substrate layer, TCNF is modified with optimized polydopamine and Fe3+ concentrations to produce mechanically strong film with a tensile modulus of 12.3 GPa. Furthermore, two CNT/TCNF ratios are used in the conducting film: 60% and 80%. In addition to absorption and reflection, the presence of TCNF in the conducting layer creates an impedance mismatch, resulting in a zigzag reflection mechanism for EMI losses. For a thickness of 212 μm, the 5-layered composite exhibited a notable tensile strength of 58 MPa and an efficient EMI shielding effectiveness (EMI SE) of 39 dB in X-band. The prepared composites meet the requirements for a commercial EMI shielding material, namely >20 dB, and outperform the mechanical strength of many other EMI shielding materials.

Tough and strong sustainable thermoplastic elastomers nanocomposite with self-assembly of SI-ATRP modified cellulose nanofibers

The ingenious design of sustainable thermoplastic elastomers (STPEs) is of great significance for the goal of the sustainable development. However, the preparation of STPEs with good mechanical performance is still complicated and challenging. Herein, to achieve a simple preparation of STPEs with strong mechanical properties, two biobased monomers (tetrahydrofurfuryl methacrylate (THFMA) and lauryl methacrylate (LMA)) were copolymerized into poly (THFMA-co-LMA) (PTL) and grafted onto TEMPO oxidized cellulose nanofiber (TOCN) via one-pot surface-initiated atom transfer radical polymerization (SI ATRP). The grafting modified TOCN could be self-assembled into nano-enhanced phases in STPEs, which are conducive to the double enhancement of the strength and toughness of the STPEs, and the size of nano-enhanced phases is mainly affected by TOCN fiber length and molecular weight of grafting chains. Especially, with the addition of 7 wt% TOCN, tensile strength, tensile strain, toughness, and glass transition temperature (Tg) of TOCN based STPEs (TOCN@PTL) exhibited 140 %, 36 %, 215 %, and 6.8 °C increase respectively, which confirmed the leading level in the field of bio-based elastomers. In general, this work constitutes a proof for the chemical modification and self-assembly behavior of TOCN by one-pot SI ATRP, and provides an alternative strategy for the preparation of high-performance STPEs.

Oxidized Cellulose Nanofibers Decorated with Magnetite as Efficient Bioadosrbent for Organic Dyes

Oxidized Cellulose Nanofibers Decorated with Magnetite as Efficient Bioadosrbent for Organic Dyes

Insight into TEMPO-oxidized cellulose-based composites as electrochemical sensors for dopamine assessment

The diagnosis and treatment of many neurological and psychiatric problems depend on establishing simple, inexpensive, and comfortable electrochemical sensors for dopamine (DA) detection. Herein, 2,2,6,6 tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibers (TOC) were successfully loaded with silver nanoparticles (AgNPs) and/or graphite (Gr) and crosslinked by tannic acid, producing composites. This study describes a suitable casting procedure for the composite synthesis of TOC/AgNPs and/or Gr for the electrochemical detection of dopamine. Electrochemical impedance spectra (EIS), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) were employed to characterize the TOC/AgNPs/Gr composites. In addition, the direct electrochemistry of electrodes treated with the prepared composites was examined using cyclic voltammetry. The TOC/AgNPs/Gr composite-modified electrode improved electrochemical performance towards detecting dopamine compared to TOC/Gr-modified electrodes. Upon employing amperometric measurement, our electrochemical instrument has a wide linear range (0.005–250 μM), a low limit of detection (0.0005 μM) at S/N = 3, and a high sensitivity (0.963 μA μM−1 cm−2). Additionally, it was demonstrated that DA detection seemed to have outstanding anti-interference characteristics. The proposed electrochemical sensors meet the clinical criteria regarding reproducibility, selectivity, stability, and recovery. The straightforward electrochemical method utilized in this paper may provide a potential framework for creating dopamine quantification biosensors.

Adsorption Studies of Ammonia, Protein, and Phytic Acid Using Chitosan Fiber Coated with Oxidized Cellulose Nanofiber

Herein, chitosan (CS) fibers coated with TEMPO-oxidized cellulose nanofibers (CS/TOCN fibers) were successfully prepared using a wet spinning technique; CS was dissolved in acetic acid to obtain a CS doping solution. The tensile strength and ammonia adsorption percentages increased with increasing TOCN concentration. The maximum ammonia adsorption percentage (41.39%, 8.3 mg/g) was obtained when 2% NaOH and 0.01% TOCN were used as the coagulation solution. Additionally, the adsorption of model proteins, including lysozyme (Lz), cytochrome C (Cyt C), and bovine serum albumin (BSA), were studied. In water, the CS/TOCN fibers with negative charges adsorbed more Lz with positive charges than CS fibers containing positive charges. Contrastingly, CS fibers adsorbed more Cyt C and BSA containing negative charges in phosphate-buffered saline solutions than CS/TOCN fibers. Furthermore, the adsorption percentage of phytic acid using the CS/TOCN fibers reached 64.18% (288 mg/g) within 60 min. Thus, TOCNs improved the tensile properties of CS fibers and preferred positively charged materials contaminated in water, such as ammonia, Lz, and phytic acid.

Comparison of cellulose and chitin nanofibers on Pickering emulsion stability—Investigation of size and surface wettability contribution

There is an increasing concern about developing biobased colloid particles for Pickering stabilization due to the environment-friendliness and health-safety needs. In this study, Pickering emulsions were formed by using TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical)-mediated oxidized cellulose nanofibers (TOCN) and chitin nanofibers prepared by TEMPO-mediated oxidation (TOChN) or partial deacetylation (DEChN). The physicochemical characterizations of Pickering emulsions demonstrated that the higher cellulose or chitin nanofiber concentrations, surface wettability, and zeta-potential, the higher effectiveness in Pickering stabilization. Specifically, even though DEChN was at a shorter size (with a length of 254 ± 72 nm) as compared to TOCN (with a length of 3050 ± 1832 nm), it showed an excellent stabilization effect on emulsions at the concentration of 0.6 wt% due to its higher affinity to soybean oil (water contact angle of 84.38 ± 0.08°) and large electrostatic repulsion between oil particles. Meanwhile, when the concentration was 0.6 wt%, long TOCN (water contact angle of 43.06 ± 0.08°) formed a three-dimensional network in the aqueous phase, which produced a superstable Pickering emulsion resulting from the limited moving of droplets. These results provided important information on the formulation of Pickering emulsions stabilized by polysaccharide nanofibers with suitable concentration, size and surface wettability.

Clearly transparent and air-permeable nanopaper with porous structures consisting of TEMPO-oxidized cellulose nanofibers.

Optically transparent materials that are air permeable have potentially numerous applications, including in wearable devices. From the perspective of sustainable development, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibers with widths of 3-4 nm have attracted considerable attention as starting materials for the preparation of clearly transparent nanofiber paper (denoted as conventional nanopaper). However, conventional nanopaper that is prepared from a water dispersion of TEMPO-oxidized cellulose nanofibers by direct drying exhibits poor air permeability owing to its densely packed layered structure. In this study, we prepared a clearly transparent and air-permeable nanopaper by applying filtration-based solvent exchange from high-surface-tension water to low-surface-tension ethanol and hexane, followed by drying under continuous vacuum filtration. The resulting hexane-exchanged nanopaper had a porous structure with individually dispersed and thin nanofiber networks and interlayer pore spaces. Owing to the tailored porous structures, the hexane-exchanged nanopaper provides similar clear transparency (total light transmittance and haze at 600 nm: 92.9% and 7.22%, respectively) and 106 times higher air permeability (7.8 × 106 mL μm m-2 day-1 kPa-1) compared to the conventional nanopaper. This study will facilitate the development of clearly transparent and air-permeable nanopapers to extend their functional applications.