Carboxylated Cellulose Nanofibers Research Articles

High‐performance carboxylated cellulose nanofibers‐based electro‐responsive ionic artificial muscles toward bioinspired applications

AbstractHighly electro‐responsive soft actuators have aroused immense attention due to their large bending deformation, fast response time, and long durability under low driving voltage. Herein we present a high‐performance ionic soft actuator using carboxylated cellulose nanofiber (CCNF), ionic liquid (IL), and polyvinyl alcohol (PVA). The proposed actuator displayed excellent actuation performances such as a large bending strain of 0.41% (peak‐to‐peak displacement of 13.6 mm), specific capacitance up to 43%, long working ability (95% maintain for 2.5 h), significantly reduced phase delay, and broad frequency bandwidth (0.1–3.0 Hz), all of which were ascribed to the strong ionic interactions of CCNF with PVA and IL. Simultaneously, bionic applications of the actuators were achieved including the active stent, bionic gripper, and bionic fingers for sliding electronic photos and human‐robot interactions. Thus, the proposed actuator provides a way for the advancement of next‐generation artificial muscles, soft robots, and human‐robot interactions.Highlights Preparing an electro‐ionic actuator using carboxylated cellulose nanofibers. Ionic interactions and cross‐linking promoting ion transport capability. The actuator displaying excellent actuation responses and bioinspired applications.

Synergistic cobalt‑copper metal-organic framework anchored amino-functionalized cellulose for antibiotic degradation: Interfacial engineering and mechanism insight.

Improving electron transfer rate of Co species and inhibiting aggregation of metal-organic frameworks (MOFs) particles are essential prerequisites for activating advanced oxidation process in wastewater treatment field. Here, we exploit Cu species with variable valence states to accelerate electron transfer of Co species and then to boost the unsatisfactory degradation efficiency for refractory pharmaceuticals via in-situ growth of copper and cobalt species on l-lysine functionalized carboxylated cellulose nanofibers. Utilizing the synergistic interplay of Co sites and deliberately exposed Cu0/Cu1+ atoms, the subtly designed catalyst exhibited a surprising degradation efficiency (~100 %) toward tetracycline hydrochloride within 10 min (corresponding to a catalytic capacity of 267.71 mg/g) without adjusting temperature and pH. Meanwhile, the catalyst displays good recyclability, well tolerance for coexisting ions and excellent antibacterial performance derived from the intrinsic antibacterial property of Cu-MOF. This research provided a novel strategy to construct MOFs-cellulose materials toward degrading various stubborn antibiotic pollutants.

Enhancing the mechanical and barrier properties of biobased polyester incorporated with carboxylated cellulose nanofibers

Most conventional plastic wraps for food packing and preservation have limited flexibility and relatively unique functions, seriously limiting their practical uses. However, smart and sustainable polyethylene 2,5-furandicarboxylate (PEF) polyester is currently employed for construction composite films to overcome this limitation. Herein, the fabrication of bio-based PEF/carboxylated cellulose nanofibers (CCNFs) blends films using PEF and CCNFs by a simple method involving layer-by-layer (LBL) assembly polymerization with exceptional mechanical and interfacial properties. In particular, the mechanical results revealed that the CP3 (1.0 wt% CCNFs) composite film had excellent mechanical properties like tensile strength (69.0 MPa), Young’s modulus (4.3 GPa), and toughness (1.26 MJ/m3), which is markedly higher than that of pure PEF film. Besides, the barrier results also demonstrated that CP3 blend film reduced the CO2 and O2 barriers by 13.4% and 11.2%, respectively, compared to pure PEF film. Consequently, FTIR, XPS, SEM/EDS, and AFM characterizations provide insight into the chemical composition, elemental distribution, morphology, and structural properties of CCNF that directly affect the PEF/CCNF composite. Notably, the barrier properties and fruit experiments revealed CP3 composite film, and the shelf life of fresh mangoes was extended by at least one week under ambient conditions (i.e., a relative humidity of 90–95%, a temperature of 30 °C, and natural light). These results indicate the practical use of CP3 composite film as a food packaging in next-generation, well-coated preservation films.

High performance mixed-dimensional assembled MXene composite membranes for molecular sieving

Two-dimensional (2D) separation membranes have proved their superiorities in addressing global water scarcity and recycling resources. However, current 2D membranes usually suffer from swelling and irregular stacking issues, which result in poor separation performance. Herein, we developed novel mix-dimensional assembled MXene composite membranes with high permeability and selectivity by intercalating 1D carboxylated cellulose nanofibers (CNFs) into 2D lamellar MXene nanosheets. The effects of chain length of CNFs and MXene/CNFs mass ratios on the morphologies, physicochemical properties, and separation performances of composite membranes were systematically investigated. The optimized MXC-3-L membrane exhibited superior rejection to Congo red (CR, >99%) and remarkable separation efficiency of dye/salt. The separation factors for the CR/NaCl and CR/Na2SO4 mixtures were 512.0 and 517.2, respectively. Moreover, the MXC-3-L membrane showed distinct rejections to perfluoroalkyl substances (PFAS) (>95%) with a nearly 8-fold increase of permeance in comparison with the commercial polyamide membrane. The 2D X-ray diffraction analysis verified that the intercalation of 1D CNFs into 2D MXene nanosheets via strong hydrogen bonding can regulate the nanochannel into more stable and regularly stacking lamellar structures, which plays a key role in high permeance and excellent molecular separation efficiency. In addition, 1D CNFs play an essential role as “threading” and “stitching”, shielding the defects between adjacent MXene nanosheets and improving the separation efficiencies. Our work provides new insights into design of defect-free and highly selective 2D materials-based membranes for enhanced wastewater treatment and molecular sieving.

Extended H-bonds/π-bonds networks for boosting electron transfer over polydopamine-covered nanocellulose/g-C3N4 toward efficient photocatalytic H2O2 production

Photocatalytic hydrogen peroxide production (PHP) from H2O and O2 is a promising solar-to-chemical conversion technology. However, conventional doping, heterojunction and defect engineering of catalyst modification for enhanced PHP process is unable to meet the highly requirements of efficient oxygen reduction reaction (ORR), while also damaging the intrinsic crystal structure of the catalysts. Herein, we demonstrate a rationally extended H-bonds/π-bonds intermolecular networks between carbon nitride (g-C3N4, CN) and carboxylated cellulose nanofibers (CNF) with a small quantity of polydopamine (PDA) for solar H2O2 production. Ultimately, CN/CNFP exhibits an extraordinary PHP of 130.7 μmol·L−1·h−1, surpassing CN/CNF (75.2 μmol·L−1·h−1) and pure CN (20.1 μmol·L−1·h−1). Experimental and density function theory (DFT) have validated that CNFP increases the adsorption capabilities of O2, enhancing the efficiency of photogenerated charge transfer and separation via multiple hydrogen bonding/π-π stacking with g-C3N4, thereby facilitating the superior PHP via a two-step single-electron ORR pathway. This work offered a viable route to modulate directed transfer of photogenerated charges with multiple intermolecular interactions and presented an encouraging strategy to obtain high-efficient PHP.

Sodium Alginate Aerogel as a Carrier of Organogelators for Effective Oil Spill Solidification and Recovery.

Marine oil spills pose a serious threat to the marine ecological environment. Phase-selective organogelators (PSOGs) are ideal candidates for oil spill gelation when used in combination with a mechanical recovery method. However, the toxicity of an organic solvent carrier has become a key problem when it is applied in the remediation of marine oil pollution. In this study, through an inexpensive and nontoxic ionic cross-linking and freeze-drying method, we successfully developed composite oil gelling agents that used a biomass sodium alginate aerogel as the carrier of 12-hydroxystearic acid (12-HSA). Simultaneously, carboxylated cellulose nanofibers (CNF-C) with large specific surface area and graphene oxide (GO) with excellent mechanical properties as reinforcing fillers were combined with an alginate matrix. 12-HSA, as a green and inexpensive organic gelator, was uniformly loaded on the aerogels by vacuum impregnation. The sodium alginate aerogel was capable of absorbing and storing oil due to its three-dimensional network skeleton and high porosity. Rheological studies have demonstrated that the organic gelator 12-HSA can be released from the aerogel substrate and self-assemble to form an oleogel with the absorbed oil quickly. The synergistic effect between absorption and congelation endows the composite oil gelling agent with efficient oil spill recovery capability. Based on eco-friendly, biodegradable, and simple synthesis methods, this composite oil gelling agent shows great potential for application in marine oil spill recovery.

PH-responsive color-indicating film of pea protein isolate cross-linked with dialdehyde carboxylated cellulose nanofibers for pork freshness monitoring

The limited mechanical performance and responsiveness of protein-based smart packaging materials have hindered their development. To address these issues, this study prepared a pH-responsive smart film by introducing dialdehyde carboxylated cellulose nanofibers (DCCNFs) as the cross-linking agent capable of covalently reacting with proteins, and bilberry extract (BE) as a pH-responsive indicator into pea protein isolate (PPI) matrix. The results demonstrated that adding DCCNF and BE enhanced the PPI film's thermal stability, density, and UV barrier properties. Tensile tests revealed significant improvements in both tensile strength and elongation at the break for the resulting film. Furthermore, films containing DCCNF and BE exhibited lower moisture content, swelling ratio, water vapor permeability, and relative oxygen transmission compared to PPI films. Notably, the anthocyanins in BE endowed the film with visual color changes corresponding to different pH values. This feature enabled the film to monitor pork freshness; a transition from acidic to alkaline in pork samples was accompanied by a color change from brown to brownish green in the film as storage time increased. Overall, these findings highlight that this developed film possesses excellent physicochemical properties and sensitive pH response capabilities, making it a promising candidate for future smart packaging applications.

Surface-Modified Carboxylated Cellulose Nanofiber Hydrogels for Prolonged Release of Polyhexamethylene Biguanide Hydrochloride (PHMB) for Antimicrobial Applications.

The surface modification of cellulose nanofibers (CNFs) using a 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)/sodium bromide (NaBr)/sodium hypochlorite (NaClO) system was successful in improving their hydrophilicity. Following that, we fabricated hydrogels containing carboxylated cellulose nanofibers (c-CNFs) and loaded them with polyhexamethylene biguanide (PHMB) using a physical crosslinking method, aiming for efficient antimicrobial uses. The morphological and physicochemical properties of all hydrogel formulations were characterized, and the results revealed that the 7% c-CNFs-2 h loaded with PHMB formulation exhibited desirable characteristics such as regular shape, high porosity, good mechanical properties, suitable gel content, and a good maximum swelling degree. The successful integration of PHMB into the c-CNF matrix was confirmed by FTIR analysis. Furthermore, the 7% c-CNFs-2 h loaded with the PHMB formulation demonstrated PHMB contents exceeding 80% and exhibited a prolonged drug release pattern for up to 3 days. Moreover, this formulation displayed antibacterial activity against S. aureus and P. aeruginosa. In conclusion, the novel approach of c-CNF hydrogels loaded with PHMB through physical crosslinking shows promise as a potential system for prolonged drug release in topical drug delivery while also exhibiting excellent antibacterial activity.

A double cross-linked network structure hydrogel with CNF–C: Synergistically enhanced mechanical properties and sensitivity of flexible strain sensors

The utilization of conductive hydrogels, particularly in the domain of wearable technology, has garnered substantial attention. However, the limited mechanical properties, low sensitivity, and lack of multifunctionality in conventional conductive hydrogels constrain their potential applications. Thus, the endeavor to develop conductive hydrogels with exceptional comprehensive performance remains a formidable challenge. In this investigation, chitosan quaternary ammonium salts and the conductive polymer poly (3,4-ethylenedioxythiophene)-poly (styrenesulfonate) were employed as precursor materials, incorporating carboxylated cellulose nanofibers, to synthesize a novel double-crosslinked network hydrogel. The resulting hydrogel specimen exhibited noteworthy tensile strength (2.13 MPa), significantly enhanced elongation (547%), favorable strain sensitivity (Gauge Factor ranging from 0.91 to 9.78), and electrical self-healing capabilities. Additionally, it demonstrated accurate detection of subtle human movements and conversion of raw data into binary data. This research provides valuable insights into the advancement of conductive hydrogels for wearable soft electronics.

Multifunctional carboxylated cellulose nanofibers/exfoliated bentonite/Ti3C2 aerogel for efficient oil adsorption and recovery: The dual effect of exfoliated bentonite and MXene

Discharge of oily wastewater with poor fluidity could cause serious environmental pollution. Therefore, rapid and efficient removal and recovery of oil is still a global problem. Currently, two-dimensional (2D) Ti3C2 MXene materials with high photothermal performance have attracted extensive attention in photothermal-assisted crude oil wastewater treatment. However, the poor stability of Ti3C2 severely limits the application in the development of photothermal aerogels. In this study, porous CNF-C/BTex/Ti3C2 aerogel was constructed by synergistically introducing cost-effective exfoliated bentonite (BTex) and Ti3C2 MXene combined with carboxylated cellulose nanofibers (CNF-C) through a simple in situ co-precipitation coupling with microwave hydrothermal and solution impregnation processes. The introduced BTex efficiently restrained the oxidation of Ti3C2 during the preparation process, and synergistically enhanced the structural stability, mechanical and adsorption properties of aerogel. Specifically, CNF-C/BTex/Ti3C2 exhibited excellent stability (structural, thermal and chemical stability), thermal resistance, hydrophobic properties (water contact angle was 149°), and mechanical properties (full recovery at 60% strain), which was conducive to adsorption of common oils (up to 46–90 times than its original weight). In addition, CNF-C/BTex/Ti3C2 has outstanding photothermal conversion efficiency (light absorption efficiency was 99% and the surface temperature reached up to 75.2 °C under 1-sun irradiation:1 kW·m−2) and thermal conductivity (104 mW/m·K), which allows CNF-C/BTex/Ti3C2 to adsorb more than 48 times than its original weight of crude oil (adsorption capacity up to 48 g·g−1) under 1-sun irradiation (1 kW·m−2) within 25 s. Furthermore, enhanced adsorption mechanisms for common oils and high-viscosity crude oil have been proposed. The study provides a new option for the development of efficient and stable cellulose-based adsorbents for oily wastewater remediation by introducing low-cost bentonite and MXene.

A quaternized chitosan and carboxylated cellulose nanofiber-based sponge with a microchannel structure for rapid hemostasis and wound healing

A hemostatic sponge should perform rapid hemostasis and exhibit antibacterial properties, whilst being non-toxic, breathable, and degradable. This study prepared a hemostatic sponge (CQTC) with microchannels, specifically a microchannel structure based on quaternized chitosan (QCS) and carboxylated cellulose nanofibers (CCNF) obtained by using tannic acid and Cu2+ complex (crosslinking agent). The sponge had low density and high porosity, while being degradable. The combination of microchannels and three-dimensional porous structure of CQTC leads to excellent liquid absorption and hemostasis ability, based on a liquid absorption rate test and in vitro hemostasis experiment. In addition, CQTC exhibited excellent antibacterial activity against both gram-negative and gram-positive bacteria, and it promoted wound healing. In conclusion, this porous and microchannel hemostatic sponge has broad application prospects as a clinical wound hemostatic material.

A simple and efficient transfer method for fabricating stretchable AgNW patterns on PDMS using carboxylated cellulose nanofibers as a sacrificial layer.

Silver nanowire (AgNW) networks are one of the most promising materials of transparent electrodes in flexible applications. However, they still face challenges in fabricating AgNW transparent conductive films (TCFs) with excellent comprehensive performance on stretchable substrates. In this work, we developed an efficient and simple water-assisted method to completely transfer AgNW films from glass to polydimethylsiloxane (PDMS). Carboxylated cellulose nanofibers (CNF-C) are introduced between the AgNW network and glass as a sacrificial layer, which is dissolved in water in the transfer process, releasing the AgNW network on the PDMS. The transferred AgNW networks show an increase of sheet resistance less than 30% and a slight decrease of transmittance. The stretchable AgNW TCFs exhibited good opto-electrical performance with a figure of merit of about 200, low surface roughness, good film uniformity, long-term stability, electrical stability and mechanical performance. Two patterning approaches based on the transfer method were proposed and fine stretchable AgNW patterns with a linewidth of 200 μm were fabricated. The fabricated stretchable AgNW patterns were used in flexible wires, a film heater and sensors as a demonstration.

Hydrophobic carbon-based coating on metal tube with efficient and stable adsorption–desorption of CO2 from wet flue gas

In order to improve the heat transfer efficiency of the shaped activated carbon in CO2 adsorption, we proposed a rapid CO2 adsorption–desorption approach by coating the outer surface of the metal tube with a hydrophobic carbon layer. The coating layer was prepared by carboxylated cellulose nanofibers (CNF) as the binder, coconut shell-activated carbon as the carrier, and methyltrimethoxysilane (MTMS) as the hydrophobic modifier. The oxygenated groups can increase its surface polarity and adsorptivity for the weakly polar small molecules like carbon dioxide. The equilibrium adsorption capacity of SAC-6-1.0 for CO2 in dry (15 vol% CO2) and wet flue gas (15 vol% CO2 + 4.7 vol% H2O) is 39.4 mg/g and 34.3 mg/g, respectively, at 40 °C and 1.0 bar, which is 54.5% and 382.4% higher than that of the original activated carbon. After 10 cycled reuses, over 97% of its adsorption capacity can be retained. The CO2 adsorption performance of SAC-6-1.0 is better than most of the oxygenated and sulfur-doped activated carbons, albeit slightly worse than that of nitrogen-doped ones. The present hydrophobic carbon coating approach is of great industrial application in the field of CO2 capture and other gas separation.

Highly electro-responsive ionic soft actuator based on graphene nanoplatelets-mediated functional carboxylated cellulose nanofibers

Electro-responsive ionic soft actuators have attracted increasing interest owing to the promising applications for soft robots, biomimetic robots, active medical devices, flexible electronics, and wearable devices. However, existing ionic actuators still need a technology breakthrough for larger bending strain, faster response, and excellent actuation durability. Herein, we report a novel highly electro-responsive ionic actuator based on functional carboxylated cellulose nanofibers (CCNF) by doping with ionic liquid (IL) and graphene nanoplatelets (GN). The proposed CCNF-IL-GN actuator demonstrated a large tip displacement of 15.71 mm (peak-to-peak) at 2.0 V with 0.1 Hz, faster rise time (2.9s), broad frequency bandwidth (0.1–3.0 Hz), markedly reduced phase delay, and long actuation durability (98.6% retention for 3 h) without actuation response distortion, all of which were due to the fast-easy ion migration and massive charge transport ability of the designed ionically crosslinked electrolyte membrane, resulting from the strong ionic interactions and crosslinking of CCNF nanofibers with IL and GN. Furthermore, we investigated the actuator's bionic applications such as the bionic flower, bionic finger, and bionic window. These results elucidate the great potential of the designed CCNF-IL-GN actuators for bionic robots, soft robots, wearable electronics, and biomedical active devices.

Nanocellulose-intercalated MXene NF membrane with enhanced swelling resistance for highly efficient antibiotics separation

Two-dimensional (2D) nanomaterial-based membranes display attractive properties in molecular separation and transport, which holds their great promise for a host of applications. However, notorious swelling problem of 2D membranes result in unsatisfactory molecular/ions sieving performance, and the enhancement of structural stability for 2D membranes in aqueous solution is still challenging. Herein, we demonstrate how to efficiently stabilize the Ti3C2Tx MXene laminar architecture by the insertion of flexible and hydrophilic carboxylated cellulose nanofibers (CNFs). The importing of CNFs not only acted as a bridge to combine the adjacent 2D Ti3C2Tx sheets and enhance mechanical strength, but also assumed the role of pillar to fix the interlayer distance effectively and improve the anti-swelling properties of Ti3C2Tx membrane. Moreover, the intercalation of nanocelluloses into the interlayer of delaminated Ti3C2Tx is able to distinctly increase the interlayer spacing and create more open gaps for fast and selective molecular transport. When applied in antibiotics separative filtration process, the resultant membrane exhibits outperformed anti-swelling properties in water environment up to 76 h and simultaneously possesses satisfactorily high selectivity of antibiotics (∼99.0 % for azithromycin) with unprecedentedly high pure water permeance (∼26.0 L m−2h−1bar−1). Such 2D membranes can be easily fabricated by a facile and patternable vacuum-assisted filtration and nanocellulose induced self-assembly strategy, which holds great potential for their scalability that are applicable to many applications such as seawater desalination, industrial wastewater treatment and remediation of aquatic environment.

Preparation and adsorption properties of green cellulose-based composite aerogel with selective adsorption of methylene blue

Four green aerogels were prepared to remove the cationic dye methylene blue (MB), using the method of solution mixing and freeze-drying. Polyethylene glycol diglycidyl ether (PEGDE) was employed as a crosslinker. The structure and performance of the adsorbents were analyzed by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), Fourier transform infrared (FT-IR), zeta potential measurement and mechanic testing. The results identified that PEGDE efficiently assisted in forming network structure of the porous aerogels, and the removal rates of four aerogels were all higher than 90%. The aerogel composed of sodium carboxymethyl cellulose (CMC) and carboxylated cellulose nanofibers (CNF–C) performed best with adsorbance of 579.50 mg/g, which had a strong electrostatic attraction with MB, exhibited selective adsorption, and did not collapse after ten cycles of underwater compression tests. The adsorption process of CMC/CNF–C aerogel was compatible with the pseudo-second-order kinetic model and Langmuir isothermal model, and the maximal adsorption capacity was 917.43 mg/g. According to the calculation of thermodynamic parameters, the adsorption process was spontaneous and benefited from temperature rise in 20–40 °C. After five regenerations, the adsorption capacity of CMC/CNF–C aerogel decreased from 579.5 mg/g to 513.2 mg/g, indicating a reusable adsorbent in wastewater treatment.

Strengthened self-healable natural rubber composites based on carboxylated cellulose nanofibers participated in ionic supramolecular network

Cellulose, as a green reinforcing agent for rubber, has excellent improvement on the tensile strength but usually accompany with a deterioration of extensibility and self-healing property. Herein, we report an efficient method to prepare robust and self-healable natural rubber/zinc dimethacrylate/carboxylated cellulose nanofibers (NR/ZDMA/CNC) composites which are constructed by a CNC participated ionic supramolecular network. Ionic supramolecular network in NR is generated by the polymerization of ZDMA during a controlled peroxide-initiated vulcanization of NR. Interestingly, NR with massive ion clusters has strong affinity with CNC, which facilitates the uniform dispersion of CNC and the compatibility between CNC and NR. Meanwhile, CNC participates into the supramolecular network via non-covalent interaction with NR chains equipped with ionic crosslinks. This greatly reduces the adverse effect of CNC on the dynamic characteristics of supramolecular network. As a result, the tensile strength of NR/ZDMA composite with 20 phr CNC could reach 4.13 MPa, while its self-healing efficiency still maintains at >80 %. Thus, NR composites with non-covalent interaction between CNC and supramolecular network display improved strength, maintained extensibility, and excellent self-healing capability. This study thus demonstrates a feasible approach to reduce the negative effect of reinforcing fillers on a self-healing rubber based on supramolecular networks.

Preparation and properties of carboxylated cellulose nanofibers/monomer casting nylon composites

AbstractPolyisocyanate was used to chemically functionalize carboxylated cellulose nanofibers (CNF‐C). Composites of CNF‐C/ monomer casting nylon (MC nylon) and modified CNF‐C/MC nylon were fabricated by anionic ring‐opening polymerization. The mechanical characteristics of the MC nylon composites and the dispersion of the CNF‐C in the MC nylon were studied. The tensile strength and impact strength of composites were first increased with CNF‐C addition, but then decreased as further CNF‐C was added. The composites had good mechanical properties when CNF‐C was added to MC nylon at 1.0 wt%, and the tensile strength and impact strength were increased by 21.2% and 34.9%, respectively, compared to MC nylon. When modified CNF‐C was added at 1.5 wt%, the tensile strength of composites was increased by 47.90%. The addition of CNF‐C causes an increase in the melting point, crystallinity, and crystallization temperature, which was confirmed by differential scanning calorimetry (DSC). The modified CNF‐C had better dispersibility in MC nylon which was confirmed by scanning electron microscopy (SEM).

Internal friction properties of carboxylated cellulose nanofibers (CNF-C) modified aramid woven fabrics

The internal friction properties of the aramid woven fabrics modified by carboxylated cellulose nanofibers (CNF-C) were studied, in order to better investigate the effect of CNF-C on the internal friction properties of the aramid woven fabrics, the yarn pull-out force of the modified aramid fabrics were tested by single yarn pull-out test. The chemical structure and surface morphology of the aramid fibers were characterized by Fourier Transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The results show that the strong hydrogen bond between CNF-C and aramid fiber and the dipole–dipole interaction between the polar groups of the fiber (such as –NH, –C = O) and hydroxyl groups are the bond mechanism. Compared with the untreated fabrics, the yarn pull-out force and fiber surface roughness of the CNF-C modified aramid fabrics are significantly improved. When the impregnation time is 0.5 h and the CNF-C concentration is 1 wt%, the yarn pull-out force reaches the maximum of 13.3 N, which is increased by 133.3% compared with the untreated aramid fabrics. The internal friction properties of the aramid woven fabrics are obviously increased by modification.

The quality properties of frozen large yellow croaker fillets during temperature fluctuation cycles: improvement by cellobiose and carboxylated cellulose nanofibers

Frozen aquatic products undergo unavoidable quality changes owing to temperature fluctuations during frozen storage and distribution. This study investigated the effects of 1% cellobiose (CB), and 0.5 and 1% carboxylated cellulose nanofibers (CNF) on ice crystal growth and recrystallization of frozen large yellow croaker fillets exposed to temperature fluctuations. Denser and more uniformly distributed ice crystals were observed in the CB- and CNF-treated samples than in the water-treated samples. Furthermore, the addition of CB and CNF suppressed the conversion of bound water to frozen water in the samples during temperature fluctuation cycles, played a positive role in fixing the ionic and hydrogen bonds that stabilize the protein structure, limited the conformational transition from α-helix to β-sheet, and improved protein thermal stability. Based on turbidity, zeta potential, and confocal laser scanning microscopy (CLSM) analyses, the presence of CB and CNF restricted the protein aggregation. Compared with CB, CNF molecules with abundant carboxyl functional groups and longer morphology exhibited better cryoprotective effects. Moreover, the fillets were more improved protected from mechanical damage induced by large ice crystals at a higher CNF concentration. This study reveals the potential of CB and CNF as novel cryoprotectants.