Cellulose Nanofibers Research Articles

Extraction of cellulose nanofibers from sugarcane bagasse at different hydrolysis conditions

This study investigated the effect of alkaline treatment and various acid hydrolysis conditions on the extraction of cellulose nanofibers from sugarcane bagasse. Alkaline treatments were conducted using sodium hydroxide and sodium hypochlorite solutions. After the alkaline treatment, acid hydrolysis was performed in solutions containing 60, 64, and 68% wt. of sulfuric acid at temperatures of 30 ± 1 °C and 45 ± 1 °C. The effectiveness of the alkaline treatment in removing non-cellulosic components was assessed by infrared spectrometry and scanning electron microscopy, which demonstrated satisfactory results in eliminating non-cellulosic components. Transmission electron microscopy revealed the impact of temperature on the dimensions of the extracted cellulose nanofibers, with acid hydrolysis at 45 °C yielding smaller nanofibers compared to hydrolysis at 30 °C. X-ray diffraction analysis showed a higher percentage of crystallinity for hydrolysis at 45 °C, which can be attributed to the removal of a substantial amount of amorphous cellulose content.

Synergistically Constructing High-Dielectric Poly(m-phenylene isophthalamide)/Silica/Cellulose Nanofiber Composite Insulation Paper through Dynamic Covalent Chemistry and Hydrogen Bonding.

The rapid advancement of modern power equipment and high-power devices has imposed increasingly stringent demands upon the mechanical and dielectric properties of electrical insulation materials. Herein, we report a poly(m-phenylene isophthalamide) (PMIA) composite insulating paper with excellent dielectric breakdown strength, reliable mechanical properties, and high thermal stability. Enhanced surface activity of PMIA is achieved through surface modification, facilitating the synergistic integration of modified PMIA (MPMIA), bovine serum albumin (BSA)/silica (SiO2), and cellulose nanofiber (CNF) into composite paper using dynamic covalent bonds and hydrogen bonding. The prepared MPMIA-BSA/SiO2-CNF composite paper exhibits a laminated stacked structure with high tensile strength (32.68 MPa) and strain at break (9.57%). Meanwhile, MPMIA-BSA/SiO2-CNF composites have excellent dielectric breakdown strength (24.75 kV/mm) and good temperature resistance. Therefore, the MPMIA-BSA/SiO2-CNF composite paper has a broad application prospect in the field of high-voltage and high-power electrical equipment insulation.

A Direct Current Self-Sustained Moisture-Electric Generator with 1D/2D Hierarchical Nanostructure for Continuous Operation of Off-Grid Electronics.

Ubiquitous moisture is a colossal reservoir of clean energy, and the emergence of moisture-electric generators (MEGs) is expected to provide direct power support for off-grid electronic devices anytime and anywhere. However, most MEGs rely on auxiliary energy storage devices and rectifier circuits to drive small electronic devices, which hinder scalability and widespread deployment, and the development of direct current (DC) MEGs with high power output that can directly drive off-grid electronic devices is highly promising but challenging. Herein, a self-sustained moisture-electric generator (SMEG) with a hierarchical nanostructure based on one-dimensional (1D) negatively charged nanofibers and two-dimensional (2D) conductive nanosheets was demonstrated to generate continuous DC electricity from atmospheric humidity. Sulfation of bacterial cellulose nanofibers lowers the surface potential and increases the surface charge energy, and reduced graphene oxide (rGO) provides a conduction pathway for electrons. The hierarchical nanostructures constructed by the combination of 1D nanofibers and 2D nanosheets endow the SMEG with self-sustained moisture gradients and structural anisotropy, which force the generation of a pseudocurrent. This combination also constructs microcapacitors that further enhance the moisture-electric power output. The SMEG can generate a continuous voltage in excess of 0.54 V for over 2160 h, with a power density of about 822 μW cm-3, demonstrating excellent operational durability. This research provides a feasible solution for the development of sustainable, versatile, and efficient power supplies for off-grid self-powered devices.

A Mussel-Inspired and Recyclable Coating with Integrated Daytime Radiative Cooling and Triboelectric Energy Harvesting for Intelligent and Sustainable Buildings.

Carbon neutrality necessitates new technologies for renewable energy utilization, active regulation of heat exchange, and material recycling to promote green and intelligent building development. Currently, the integration of these functions and characteristics into a single coating material presents a significant challenge. Here, we demonstrate a novel triboelectric and radiative cooling coating with mussel-inspired architectures, fabricated using cellulose nanofibers and Mica-TiO2 as a functional mortar and brick, respectively. The abundant polar groups and specific surface area of cellulose nanofibers enable a high accumulation of induced electrostatic charges, allowing the coating to act as a tribolayer to generate triboelectric outputs. The regularly layered arrangement of Mica-TiO2 endows fire resistance to the coating, which exhibits self-extinguishing properties and maintains 45% of its original electrical output even after direct exposure to flame for 20 s. Additionally, the created multilayered stacking morphology, as well as intense group vibrations of Mica-TiO2, facilitates high reflectivity (Rsolar = 0.9) and long-wave infrared emissivity (ϵLWIR = 0.94), achieving a daytime subambient temperature drop of 5.3 °C. Notably, the coating can be recycled easily while maintaining its triboelectric, radiative cooling, and fire-resistant properties. This work provides an innovative strategy for unifying triboelectric and radiative cooling functions, as well as recyclability, into a single coating material, offering new insights for future sustainable and energy-efficient buildings.

Synergistic Effects of Polyethylene Glycol and Cellulose Nanofibers on the Isothermal and Non-isothermal Crystallization Behaviors of Polylactide

Synergistic Effects of Polyethylene Glycol and Cellulose Nanofibers on the Isothermal and Non-isothermal Crystallization Behaviors of Polylactide

Cellulose nanofiber aerogels: effect of the composition and the drying method

Cellulose nanofiber aerogels: effect of the composition and the drying method

High mechanical strength, flame retardant, and waterproof silanized cellulose nanofiber composite foam for thermal insulation

High mechanical strength, flame retardant, and waterproof silanized cellulose nanofiber composite foam for thermal insulation

LDH nanoparticles-doped cellulose nanofiber scaffolds with aligned microchannels direct high-efficiency neural regeneration and organized neural circuit remodeling through RhoA/Rock/Myosin II pathway

Spinal cord injury (SCI) triggers interconnected malignant pathological cascades culminating in structural abnormalities and composition changes of neural tissues and impairs spinal cord tissue function. Cellulose nanofibers (CNF) have considerable potential in mimicking tissue microstructure for nerve regeneration, but the effectiveness of CNF in repairing SCI remains poorly understood. In this study, we designed a Mg–Fe layered double hydroxide (LDH)-doped cellulose nanofiber (CNF) scaffold with aligned intact microchannels and homogeneously distributed pores (CNF-LDH), loaded with retinoic acid and sonic hedgehog (CNF-LDH-RS) for neuroregeneration. The aligned microchannel structure and chemical cues in the scaffold were designed further to enhance the differentiation of neural stem cells towards neurons and promote axon growth while inhibiting differentiation to astrocytes. Transplanting the scaffolds into a completely transected SCI mice model dramatically improved behavioral and electrophysiological outcomes underpinned by robust neuronal regeneration, significant axonal growth and orderly neural circuit remodeling. RNA-seq analysis revealed the pivotal roles of the RhoA/Rock/Myosin II pathway and neuroactive ligand-receptor interaction pathway in SCI repair by CNF-LDH-RS. Particularly, Myosin II emerged as a key gene for functional recovery, and its effect on negative regulation of axon growth was suppressed by the scaffolds, resulting in a distinctly oriented growth of the axons along the microchannel structure. The results indicate that CNF-LDH scaffolds rationally combined with physical and biochemical cues create promising tissue-engineered substrates to facilitate the repair of spinal cord injury.

Reversibly Compressible Silanated Cellulose Nanofibril Aerogel for Triboelectric Taekwondo Scoring Sensors.

The integration of bio-based materials into triboelectric nanogenerators (TENGs) for energy harvesting from human body motions has sparked considerable research attention. Here, a silanated cellulose nanofibril (SCNF) aerogel is reported for structurally reliable TENGs and reversely compressible Taekwondo scoring sensors under repeated impacts. The preparation of the aerogel involves silanizing cellulose nanofibers (CNFs) with vinyltrimethoxysilane (VTMS), following by freeze-drying and post-heating treatment. The SCNF aerogel with crosslinked physico-chemical bonding and highly porous network is found to exhibit superior mechanical strength and reversible compressibility as well as enhanced water repellency and electron-donating ability. The TENG having a tribo-positive SCNF layer exhibits exceptional triboelectric performances, generating a voltage of 270V, current of 11µA, and power density of 401.1mWm-2 under an applied force of 8N at a frequency of 5Hz. With its inherent merits in material composition, structural configuration, and device sensitivity, the SCNF TENG demonstrates the capability to seamlessly integrate into a Taekwondo protection gear, serving as an efficient self-powered sensor for monitoring hitting scores. This study highlights the significant potential of a facilely fabricated SCNF aerogel for the development of high-performance, bio-friendly, and cost-effective Bio-TENGs, enabling their application as self-powered wearable devices and sports engineering sensors.

High-Speed Electrospinning of Ethyl Cellulose Nanofibers via Taylor Cone Optimization

High-Speed Electrospinning of Ethyl Cellulose Nanofibers via Taylor Cone Optimization

The nanocellulose fiber scaffold to construct a hierarchical phenolic coating on cotton fiber surfaces for inactivating pathogens through an enhanced protein adsorption mechanism

Emerging pathogens present a significant societal threat, and biological protection textiles are expected to play a pivotal role in controlling their spread. However, incorporating highly effective pathogen transmission-blocking abilities into textiles while ensuring their large-scale production remains challenging. This work has successfully developed a hierarchically structured coating for cotton fibers, which exhibits enhanced antiviral and antibacterial functionalities compared to existing phenolic coating methods. The multilevel coating consisted of a cellulose nanofibers (CNFs) scaffold on cotton fibers, along with a phenolic layer constructed of 4,4-bis(4-hydroxyphenyl)valeric acid (DPA) on the CNF surfaces. The bioactive textile exhibited remarkable antiviral and antibacterial capabilities with exceptional durability, while demonstrating strong protein affinity for pathogen destruction. Especially, the CNFs with diameters below 10 nm show significant size effect in capturing phi6. This is primarily due to their complementary shape matching the spike proteins, resulting in an increased number of binding sites and improved inactivation effectiveness. Moreover, the modification process was demonstrated to be scalable in a pad-dry-cure line commonly employed by textile finishing factories, and the resultant coating ensured reliable safety for human skin without sacrificing wearing comfort. This approach opens up new possibilities for developing protective textiles that effectively block pathogen transmission.

Flexible, Multifunctional, and Durable MXene/CeO2/Cellulose Nanofibers for Efficient Energy Conversion‐Storage Capacity Toward Self‐Powered Monitoring of Ammonia

AbstractThe appeal of wearable gas sensors for Internet of Things (IoTs) necessitates flexible sensory units along with sustainable source of energy supply. The key factors required for emergence of these devices are choice of electroactive materials, flexibility, skin‐compatibility, and robustness against harsh environment. Considering this, the multifunctional MXene/CeO2 composites reinforced with electrospun cellulose nanofibers are constructed and investigated for energy conversion, energy storage, and gas sensing applications. Among the synthesized composites, MXene/CeO2 (10 wt%) coated onto cellulose nanofibers outperformed triboelectric nanogenerator (TENG) with open‐circuit voltage of 160 V and supercapacitor (SC) specific capacitance of 388.98 F g−1 and sensing response of 212% toward 10 ppm NH3. The fabricated devices show promising outlooks against practical challenges of influence of humid conditions and different bending states. Lastly, the self‐chargeable device is integrated and the practical implications of charging of SC through TENG and its utilization in sensor powering is demonstrated. The above findings are expected to contribute significantly in envisioning development of wearable health monitors, combining the flexibility features and facilitating autonomous measurements of NH3 pollutant and biomarker.

Structural evolution and stabilisation mechanism of foam fluids that contain cellulose nanofibres and cellulose nanocrystals: An experimental and modeling study

Foam fluids are thermodynamically metastable systems, and they evolve over timescales comparable to their time of use, which makes the study of their destabilisation mechanisms crucial for many industrial applications. In our study, foams were made from fluids that contained cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs). We explored the effects of nanocelluloses and oils (n-heptane and n-dodecane) on foam stability, bubble coarsening and liquid drainage. Results show that the evolution of the bubble size is strongly slowed by the synergistic effect of CNCs and CNFs, and the structural evolution of foam is greatly impacted. The main responsible mechanism is an increase in local yield stresses due to the presence of CNCs in the foam. The jammed CNCs in foam produce a drainage delay, which makes the foam 50 % drainage time (t50%) of the experimental value deviate by up to 400 % from the classical theory value. When the bubbles coarsen and grow above a threshold size, liquid can drain out of the foam. Finally, a predictive model for t50% that considers the drainage delay was proposed. The experimental results validated the proposed correlation and exhibited good reliability and predictive accuracy. The results enable us to elucidate the impact of CNCs and CNFs on the stability of foam fluids.

One-step rapid prototyping of recyclable ultrathin CNF/MWCNT/Fe-based spinel oxide asymmetric interdigital nanopaper electrodes for high performance flexible supercapacitors

Flexible asymmetric supercapacitors (FASCs) are potential energy storage devices for wearable electronics, considering that these have a wide operating voltage window, high specific capacity, and high energy density. However, achieving high energy density through the optimization of structure and electrode remains a challenge. Herein, two electrode inks with exceptional homogeneity nature and stability are prepared by using in-situ grown Fe-based spinel oxide (MFe2O4 = Fe3O4/MnFe2O4) on multi-walled carbon nanotubes (MWCNT) combined with eco-friendly and renewable cellulose nanofiber (CNF). Meanwhile, ultrathin flexible asymmetric interdigital nanopaper electrodes (NFT@MnFe and NFT@Fe) with customized patterns are fabricated through a one-step mask-assisted vacuum filtration strategy by using the obtained electrode inks. The planar interdigital FASC device based on the NFT@MnFe cathode and the NFT@Fe anode has excellent area specific capacity (309.8 mF cm−2), energy density (110.2 μW h cm−2), and power density (0.47 mW cm−2). The FASC maintain over 95 % of the original capacity after 5000 charge/discharge cycles. Noteworthy, a stacked interdigital FASC can be achieved with an energy density of up to 273.8 μW h cm−2 at 0.47 mW cm−2 power density, combining the structural benefits of planar interdigital and sandwich-type devices.

A fully nanofiber-based ultrathin electronic patch for self-powered and multifunctional on-skin applications

On-skin electronics that simultaneously ensure biocompatibility and stable electrical operation on soft tissue is still challenging. This study introduces a dual-layered and natural material based nanofiber platform designed for multifunctional on-skin operation (from energy harvesting to transdermal drug delivery). The ultrathin electronic patch consists of polyaniline (PANI)-coated cellulose nanofibers and silk fibroin nanofibers. The top PANI/cellulose nanofiber layer, exhibiting the resistivity of 0.315 Ω·m and over 90% light absorbance in full visible range, functions as a flexible electrode. The silk nanofiber layer offers the skin-compatibility and strong adhesion to biological tissues, along with the capability of drug-loading. The nanofiber mesh structure withstands mechanical deformation, including compression, stretching, and bending, while its porous nature enhances breathability and hygiene. The fully nanofiber-based electronic patch platform is flexible, adheres well to the skin, and conforms to curved surfaces. By integrating the conductive properties of PANI with the biocompatibility of silk fibroin, this dual-layered membrane enhances the efficacy of transdermal drug delivery while offering multifunctional capabilities such as energy harvesting in a triboelectric nanogenerator (TENG), programmable drug delivery, and thermal therapy. This innovative approach paves the way for advanced biomedical applications by combining multiple functionalities in a single platform.

One-step green synthesis of melamine-modified cellulose nanofiber composite aerogels for efficient removal of Pb(II) and Cu(II): Experiments and DFT calculations

A composite aerogel (CGMA) with high porosity (98.32 %) and multiple active sites was prepared for the adsorption of Pb(II) and Cu(II) by sol-gel combined with freeze-drying process using melamine and (3-Glycidyloxypropyl)trimethoxysilane as cellulose nanofiber modifying materials. Characterized by SEM-EDS, XPS, FTIR, BET, MIP and TG, CGMA has a hierarchical pore structure and abundant adsorption sites. At pH = 6, the adsorption reached equilibrium within 120 min, following the Pseudo second-order kinetic model and the Langmuir model, with maximum capacities of 268.1 mg/g for Pb(II) and 152.6 mg/g for Cu(II). The process was primarily governed by homogeneous chemisorption. The coexisting ion, organic matter, and water quality experiments confirmed the excellent anti-interference properties of CGMA. Competitive adsorption experiments showed that CGMA has excellent selective adsorption performance for Pb(II). After 5 cycles, Pb(II) and Cu(II) adsorption performance decreased to 79.21 % and 83.40 %, respectively. FTIR, XPS, DFT and RDG analysis showed that amino groups and oxygen-containing groups were the main sites of adsorption. CGMA forms coordination bonds and complexes with Pb(II) and Cu(II) via amine and oxygen groups and adsorbs via electron transfer, hydrogen bonding, and van der Waals forces, with Pb(II) being more selective. CGMA has good prospects for application in heavy metal ion treatment.

Lithium-functionalized TEMPO-oxidized cellulose nanofiber as a novel binder and its impact on the ionic conductivity performance of lithium-ion batteries

Lithium-functionalized TEMPO-oxidized cellulose nanofiber as a novel binder and its impact on the ionic conductivity performance of lithium-ion batteries

A bio-based, self-healable, conductive rubber film with oxidized cellulose nanofiber segregated network

Rubber composites are indispensable in all areas of our daily lives. However, the formation of permanent crosslinked networks in rubber materials makes it difficult to recycle, resulting in a non-negligible waste of resources. In this paper, a vulcanization-free, fully bio-sourced rubber composite was prepared by using oxidized natural rubber (oNR) and oxidized cellulose nanofibers (TOCFs). TOCFs are selectively dispersed between the latex particles to form a segregated network. Meanwhile, the formation of hydrogen-bonding between oxygenated polar groups of oNR and abundant hydroxyl and carboxyl groups of TOCFs improves their interfacial interactions. This special structure promotes strain-induced crystallization (SIC) behavior of oNR matrix, giving its tensile strength up to 14.7 MPa. Furthermore, the oNR/TOCFs film shows excellent self-healing efficiency (96 %) at 40 °C for 5 h. The hygroscopicity of the TOCFs segregated network can turn the oNR/TOCFs film to be a conductive film by regulating the absorbed water content. The film has high conductivity (0.05 S/m) at a water content of 8.99 wt%, and the resistance change (RV/R0) can be varied between 1–5.9 × 10−6 at a water content range of 0–8.99 wt%, which makes it have potential for a wide range of humidity monitoring applications.

A highly stretchable and self-adhesive cellulose complex hydrogels based on PDA@Fe3+ mediated redox reaction for strain sensor

As the application of conductive hydrogels in the field of wearable smart devices is gradually deepening, a variety of hydrogel sensors with high mechanical properties, strong adhesion, fast self-healing, and excellent conductivity are emerging. However, it is still a great challenge to manufacture hydrogel sensors combining multiple properties. Herein, we leveraged the dynamic redox reaction occurring between polydopamine (PDA) and Fe3+ to induce ammonium persulfate (APS) to generate free radicals, thereby initiating the copolymerization of hydroxyethyl methacrylate (HEMA) and acrylic acid (AA) monomers. Then, polypyrrole-encapsulated cellulose nanofibers (PPy@CNF) and carboxymethylcellulose (CMC) were incorporated as conductive reinforced nanofillers and interpenetrating network skeleton. The obtained hydrogel cross-linked through reversible metal-ligand bonds, π-π stacking and abundant hydrogen bonding demonstrated great mechanical properties (strength 240.4 kPa, strain 1175 %) and self-healing ability (88.96 %). Particularly, the gel displayed ultrahigh durability and skin adhesive ability (75 kPa after 10 cycles), surpassing previous skin adhesion hydrogels. Furthermore, through the synergistic conductive effect of PPy@CNF and Fe3+, the prepared hydrogel sensor possessed high sensitivity (GF = 1.89) with a wide sensing range (~1000 %), which could realize the human body's daily motion detection, and had a promising application in flexible wearable electronics.

Bacterial cellulose nanofiber reinforced self-healing hydrogel to construct a theranostic platform of antibacterial and enhanced wound healing

In order to promote wound healing, self-healing hydrogels with moisturizing property are employed as wound dressing. In this study, bacterial cellulose nanofibers (BCN) with high mechanical strength are used as reinforcement to improve the mechanical properties of self-healing hydrogels. A multifunctional self-healing hydrogel has been constructed by incorporating natural biomass, including Ag hybrid bacterial cellulose nanofiber (Ag-BCN), resveratrol (Res), and carbon nanodots (CNDs). The results of in vitro experiments demonstrate that the mechanical strength of the hybrid hydrogel was increased by 6 times with the addition of Ag-BCN, which also offers excellent antibacterial efficiency (S. aureus 99.99 % and E. coli 99.68 %). The hydrogel with CNDs can observe the healing process of the crack in real time and realize the controlled release of Res through photothermal effect. Moreover, the results of animal model experiments indicate that the prepared hydrogel could reduce the infection of the wound, effectively shorten the progress of wound healing (from 21d to 14 d). All the results imply that the prepared hydrogel has great promise in the application of skin wound healing.