Nanocellulose-based fibers, methods for their production and use

Abstract

The application discloses nanocellulose-based fiber and a preparation method and application thereof, and belongs to the technical field of cellulose spinning, and solves the problem of unsatisfactory fire-retardant and antibacterial performance of nanocellulose-based fiber in the prior art.The method comprises the following steps: uniformly mixing an oxidized bacterial cellulose dispersion liquid and a sodium alginate / natural polyphenol-iron solution to obtain a spinning stock solution; wherein the mass ratio of the oxidized bacterial cellulose and the sodium alginate is 1:0.5-2.0; extruding the spinning stock solution into a coagulation bath to form continuous gel filaments, and then cleaning the continuous gel filaments in deionized water after immersion in the coagulation bath; and drying to obtain nanocellulose-based fiber.The nanocellulose-based fiber provided by the application has excellent fire-retardant and photothermal antibacterial performance, and the preparation process is pollution-free and green and environment-friendly, and the technology has great reference significance for functionalization development, green processing and deep development of cellulose fiber.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of cellulose spinning, and more particularly to a nanocellulose-based fiber and a preparation method and application thereof. BACKGROUND

[0002] The development of high-performance and functional fiber products has greatly enriched people's daily life, but at the same time, the non-degradable chemical fiber fabrics have caused serious environmental pollution. Therefore, it is of great significance to find and develop alternative biodegradable fibers. The research on the fiberization of biomass such as cellulose has gradually attracted more attention from the academic and industrial circles. However, the commercial regenerated cellulose fibers have problems such as complex production process, high production cost, and serious solvent system pollution, which makes it difficult to realize the real green processing and development of cellulose fibers. In recent years, researchers have prepared nanocellulose through physical or chemical methods. Based on its excellent mechanical properties, high specific surface area, high hydrophilicity and biocompatibility, nanocellulose has been widely used in various fields. Among them, the nanocellulose prepared by TEMPO oxidation has a high aspect ratio and uniform size distribution. The repulsion between the negative charges on the surface of the nanocellulose not only promotes the exfoliation of the nanocellulose, but also facilitates its uniform dispersion in water. Using oxidized cellulose nanofiber as the matrix and adding biomass polymers to improve the continuity of spinning, it has the possibility to form high-strength fibers.

[0003] However, in the application of medical materials such as biological adjuvants, the requirements for the flame retardant and photo-thermal antibacterial properties of nanocellulose and fibers are higher than those of ordinary fibers, and the existing products are difficult to achieve ideal effects. Therefore, nanocellulose-based fibers with flame retardant and photo-thermal antibacterial properties and their preparation methods need to be explored. SUMMARY

[0004] The present application provides a nanocellulose-based fiber and a preparation method and application thereof, to solve the problem of unsatisfactory flame retardant and antibacterial performance of the nanocellulose-based fiber in the prior art.

[0005] In a first aspect, the present application provides a method for preparing a nanocellulose-based fiber, comprising the following steps: oxidizing a bacterial cellulose dispersion to obtain an oxidized bacterial cellulose dispersion; dissolving sodium alginate in ultrapure water, adding natural polyphenol under continuous stirring, stirring until the solution is uniform, adding elemental iron, continuously stirring until the solution turns dark purple to obtain a sodium alginate / natural polyphenol-iron solution; uniformly mixing the oxidized bacterial cellulose dispersion and the sodium alginate / natural polyphenol-iron solution to obtain a spinning dope; wherein the mass ratio of oxidized bacterial cellulose to sodium alginate is 1:0.5-2.0; extruding the spinning dope into a coagulation bath to form continuous gel filaments, and after soaking in the coagulation bath, washing in deionized water; and drying to obtain the nanocellulose-based fiber. The elemental iron can be in different forms such as iron nails, iron rods, iron blocks, iron sheets, etc., which are not limited in the present application.

[0006] As a possible implementation manner, the bacterial cellulose dispersion is a non-derivatized bacterial cellulose dispersion with a mass percentage of 3wt%-8wt% obtained by mechanical shearing and homogenization treatment; and / or, the sodium alginate is dissolved in ultrapure water with a mass percentage of 3wt%-8wt% in the ultrapure water; and / or, the natural polyphenol is added with a mass percentage of 0.3wt%-0.8wt% in the ultrapure water; and / or, the continuous stirring is performed for 20-30h until the solution turns dark purple; and / or, the mass percentage of the spinning dope is 3wt%-8wt%.

[0007] As a possible implementation manner, the natural polyphenol is any one of tannic acid, gallic acid, catechin and catechol; and / or, the coagulation bath is a calcium chloride aqueous solution; and / or, the mass concentration of the coagulation bath is 1wt%-5wt%.

[0008] As a possible implementation manner, the oxidation treatment comprises the following steps: adjusting the pH of the bacterial cellulose dispersion to 10-10.5 with an alkali solution, adding 2,2,6,6-tetramethylpiperidine-n-oxide and sodium bromide, adding a sodium hypochlorite solution with a pH of 10-10.5; stirring at room temperature and maintaining the pH at 10-10.5 with an alkali solution, adding ethanol for quenching after the reaction is sufficiently completed, and then performing suction filtration to obtain the oxidized bacterial cellulose dispersion.

[0009] As a possible implementation manner, the mass ratio of the bacterial cellulose in the bacterial cellulose dispersion solution, the 2,2,6,6-tetramethylpiperidine-nitrogen-oxide, the sodium bromide and the sodium hypochlorite in the sodium hypochlorite solution is 1:0.016-0.02:0.1-0.125:0.2235-0.2794; and / or, the stirring rate at room temperature is 450-550 rpm; and / or, the alkali solution is a sodium hydroxide solution.

[0010] In a second aspect, the present application provides the nanocellulose-based fiber prepared by the method of any possible implementation manner of the first aspect.

[0011] As a possible implementation manner, the nanocellulose-based fiber has significantly better flame-retardant performance than cotton fiber.

[0012] As a possible implementation manner, the nanocellulose-based fiber has an antibacterial effect of ≥99%.

[0013] As a possible implementation manner, the antibacterial effect is an effect of resisting Staphylococcus aureus and / or Escherichia coli.

[0014] In a third aspect, the present application provides the nanocellulose-based fiber prepared by the method of any possible implementation manner of the first aspect or the nanocellulose-based fiber of any possible implementation manner of the second aspect in medical materials.

[0015] As a possible implementation manner, the medical material includes a biological auxiliary material.

[0016] The nanocellulose-based fiber provided by the present application uses oxidized bacterial nanocellulose fiber, sodium alginate, natural polyphenol and metallic iron as raw materials. The natural polyphenol can etch the metallic iron, and the metallic iron is complexed with iron ions to form a metallic phenolic network, so as to endow the target product with antibacterial and flame-retardant functions. Meanwhile, the iron ions can also be crosslinked with oxidized cellulose and sodium alginate to enhance the overall strength of the target product.

[0017] The nanocellulose-based fiber provided by the present application has excellent flame-retardant and photo-thermal antibacterial performance, and the preparation process is pollution-free and green and environmentally friendly. The technology has great reference significance for the functionalization development, green processing and deep development of cellulose fiber. BRIEF DESCRIPTION OF DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings described below are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0019] Figure 1 The ultraviolet spectrum detection results and physical pictures of the Alg / TA-Fe solution provided by the embodiments of the present application.

[0020] Figure 2 The pictures of each spinning dope (top) and the pictures of each product fiber (bottom) provided by the embodiments of the present application, wherein a represents product A, b represents product B, and c represents product C.

[0021] Figure 3 The strength test results of each fiber provided by the embodiments of the present application, wherein a is the breaking strength curve, and b is the elongation at break.

[0022] Figure 4 The fiber surface and cross-section morphology pictures measured by electron microscope of each fiber provided by the embodiments of the present application, wherein a represents sodium alginate fiber D, b represents sodium alginate fiber E, c represents Alg / TAFe2-TOBC1 fiber, d represents Alg / TAFe1-TOBC1 fiber, and e represents Alg / TAFe2-TOBC2 fiber.

[0023] Figure 5 The flame retardant test results of each fiber provided by the embodiments of the present application.

[0024] Figure 6 The microcalorimetric test results of each fiber provided by the embodiments of the present application.

[0025] Figure 7 The antibacterial efficiency results of each fiber provided by the embodiments of the present application. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, but not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application.

[0027] In order to solve the problem that the flame retardant and antibacterial performance of the nanocellulose-based fiber in the prior art is not ideal, the embodiments of the present application provide a preparation, characterization and test experiment of a nanocellulose-based fiber.

[0028] The bacterial cellulose dispersion liquid is subjected to oxidation treatment to obtain an oxidized bacterial cellulose dispersion liquid; sodium alginate is dissolved in ultrapure water, and natural polyphenol is added under continuous stirring, and the solution is stirred until uniform, and iron is added, and the solution is continuously stirred until it turns dark purple to obtain a sodium alginate / natural polyphenol-iron solution; the oxidized bacterial cellulose dispersion liquid and the sodium alginate / natural polyphenol-iron solution are uniformly mixed to obtain a spinning dope; wherein the mass ratio of the oxidized bacterial cellulose and the sodium alginate is 1:0.5-2.0; the spinning dope is extruded into a coagulation bath to form continuous gel filaments, and after immersion in the coagulation bath, it is washed in deionized water; and after drying, a nanocellulose-based fiber is obtained.

[0029] In the present application, the bacterial cellulose dispersion liquid is a non-derivatized bacterial cellulose dispersion liquid with a mass percentage of 3wt%-8wt% obtained by mechanical shearing and homogenization treatment; the natural polyphenol is added with a mass percentage of 0.3wt%-0.8wt% in ultrapure water; the solution is continuously stirred until it turns dark purple, and the stirring time is 20-30h; and the mass percentage of the spinning dope is 3wt%-8wt%.

[0030] The technical solutions of the present application under the above conditions can obtain the target product, and the mechanical properties, flame retardant properties, photothermal properties and antibacterial efficiency of the target product can all achieve ideal effects. In specific experiments, the preparation of product A, product B and product C is taken as an example for characterization and testing. It is proved that the nanocellulose-based fiber provided by the present application has excellent mechanical properties, flame retardant properties, photothermal properties and antibacterial efficiency.

[0031] The technical solutions of the present application under the above conditions can obtain the target product, and the mechanical properties, flame retardant properties, photothermal properties and antibacterial efficiency of the target product can all achieve ideal effects. In specific experiments, the preparation of product A, product B and product C is taken as an example for characterization and testing. It is proved that the nanocellulose-based fiber provided by the present application has excellent mechanical properties, flame retardant properties, photothermal properties and antibacterial efficiency.

[0032] Example 1

[0033] This example provides a preparation experiment of a nanocellulose-based fiber.

[0034] Bacterial cellulose colloid was used as raw material, and was treated by mechanical shearing and drying, and then was sheared and broken by high pressure homogenizer (600 MPa) for 30 times to obtain a bacterial cellulose dispersion solution with a mass fraction of 3 wt%. A sufficient amount of sodium hydroxide solution was added to the bacterial cellulose dispersion solution (100 g) until the pH reached about 10, and 2,2,6,6-tetramethylpiperidine-N-oxide (TEMPO, 0.016 g, 0.1 mmol) and sodium bromide (NaBr, 0.1 g, 1 mmol) were added. A 5 wt% sodium hypochlorite (NaClO) solution was added by adjusting the pH to 10 with hydrochloric acid. The NaClO solution was added at a dose of 3 mmol NaClO per gram of cellulose, and the TEMPO-mediated oxidation was started, and the pH was maintained at 10-10.5 by continuously adding sodium hydroxide solution at 500 rpm. After 6 hours of reaction, ethanol was added for quenching. Filtration was performed to obtain an oxidized bacterial cellulose dispersion solution, which was thoroughly washed with water and stored at 4°C. 900 mg of sodium alginate (Alg) was dissolved in 30 mL of ultrapure water (3 wt%). Then, 90 mg of tannic acid (TA) was added to the Alg solution under continuous stirring, and the mixed solution was stirred until it was uniform, and then was transferred to a 50 mL centrifuge tube. A clean iron nail was immersed in the mixed solution, and continuous stirring was performed for 24 hours. The color of the solution gradually changed from light yellow to pink, and finally to dark purple, to obtain a sodium alginate / tannic acid-iron solution (Alg / TA-Fe solution). The prepared Alg / TA-Fe solution was detected by ultraviolet spectroscopy, and the TA-Fe solution without adding Alg was used as a control to obtain the results as shown in Figure 1 . It can be seen from Figure 1 that the colors of the Alg / TA-Fe and TA-Fe solutions gradually changed from colorless to dark black and dark purple, indicating that the TA etched the iron nail and released Fe 3+ to form a TA-Fe complex; by observing the ultraviolet spectrum, it can be seen that the presence of the Alg-Fe network caused a blue shift of the ligand-to-metal charge transfer (LMCT) band of TA-Fe; the Alg / TA-Fe system collectively realized the continuous assembly of the TA-Fe network, forming a metal phenolic aldehyde network and a sodium alginate-metal network structure.

[0035] Preparation of product A (Alg / TAFe2-TOBC1): The prepared Alg / TA-Fe solution was mixed with oxidized bacterial cellulose dispersion (3wt%) at a mass ratio of 2:1 at room temperature to obtain Alg / TAFe2-TOBC1 spinning dope, which was centrifuged to remove bubbles. The Alg / TAFe2-TOBC1 spinning dope was extruded through a syringe pump (11.6 m / min) and then washed in a multi-coagulation bath, and the coagulation bath was a 1wt% CaCl2 solution, to obtain Alg / TAFe2-TOBC1 fibers. The fibers were dried by hot air after passing through the guide roller out of the coagulation bath and finally collected by the winding roller.

[0036] Preparation of product B (Alg / TAFe1-TOBC1): The prepared Alg / TA-Fe solution was mixed with oxidized bacterial cellulose dispersion (3wt%) at a mass ratio of 1:1 at room temperature to obtain Alg / TAFe1-TOBC1 spinning dope, which was centrifuged to remove bubbles. The Alg / TAFe1-TOBC1 spinning dope was extruded through a syringe pump (11.6 m / min) and then washed in a multi-coagulation bath, and the coagulation bath was a 1wt% CaCl2 solution, to obtain Alg / TAFe1-TOBC1 fibers. The fibers were dried by hot air after passing through the guide roller out of the coagulation bath and finally collected by the winding roller.

[0037] Preparation of product C (Alg / TAFe2-TOBC2): The prepared Alg / TA-Fe solution was mixed with oxidized bacterial cellulose dispersion (3wt%) at a mass ratio of 1:2 at room temperature to obtain Alg / TAFe2-TOBC2 spinning dope, which was centrifuged to remove bubbles. The Alg / TAFe2-TOBC2 spinning dope was extruded through a syringe pump (11.6 m / min) and then washed in a multi-coagulation bath, and the coagulation bath was a 1wt% CaCl2 solution, to obtain Alg / TAFe2-TOBC2 fibers. The fibers were dried by hot air after passing through the guide roller out of the coagulation bath and finally collected by the winding roller.

[0038] The spinning dope and fibers in the prepared product A, product B and product C can be prepared as shown in Figure 2 As shown in the above table, the Alg / TAFe2-TOBC1 spinning dope, the Alg / TAFe1-TOBC1 spinning dope and the Alg / TAFe2-TOBC2 spinning dope; and the Alg / TAFe2-TOBC1 fibers, the Alg / TAFe1-TOBC1 fibers and the Alg / TAFe2-TOBC2 fibers were successfully prepared by the scheme provided in the present application.

[0039] Preparation of product D (Alg): 900 mg of sodium alginate was dissolved in 29.1 mL of deionized water to prepare a 3 wt% sodium alginate spinning dope. The sodium alginate spinning dope was extruded through a spinneret (11.6 m / min) into a coagulation bath, which was a 1 wt% CaCl2 aqueous solution. Washing was performed in a water bath to remove residual Ca 2+ After washing, hot drying and stretching were performed to obtain sodium alginate fiber D.

[0040] Preparation of product E (Alg / TA-Fe): The prepared Alg / TA-Fe solution was used as a spinning dope, which was extruded through a spinneret (11.6 m / min) into a coagulation bath, which was a 1 wt% CaCl2 aqueous solution. Washing was performed in a water bath to remove residual Ca 2+ After washing, hot drying and stretching were performed to obtain sodium alginate fiber E.

[0041] Example 2

[0042] This example provides a characterization experiment of nanocellulose-based fibers.

[0043] Spinning confirmation: In this example, wet spinning was used to perform spinning confirmation on the spinning dope to be tested.

[0044] UV absorption spectrum: A UV-visible spectrophotometer (U-3900, China) was used for testing.

[0045] Colloidal rheological characterization: A digital viscometer (SNB-2, China) was used to test the spinning dope to be tested. 50 mL was taken in a beaker and allowed to stand for 24 h. Measurement was performed at room temperature (25°C) using an L4 rotor. The unit of measurement was mPa·s.

[0046] Single fiber mechanical property characterization: An electronic single yarn strength tester (YM061, China) was used to test the mechanical properties of the fiber to be tested. The clamp distance was set to 30 mm, the stretching speed was fixed at 10 mm / min, each sample was measured 5 times to take the average value, and the dry strength (cN / dtex) and elongation at break (%) were calculated and recorded.

[0047] Fiber surface morphology characterization: A scanning electron microscope (FEI Quanta 200, USA) was used to test the microstructure of the surface and cross section of the fiber to be tested. Liquid nitrogen brittle fracture treatment was used for complete sample preparation of the cross section of the fiber to be tested.

[0048] Flame retardant performance: A micro calorimeter (Gomac’s instrument MCC-2) was used to test the flame retardant performance of the fiber to be tested. The test weight of each sample was 5 mg. Cotton was used as a comparison.

[0049] Photothermal test: 10 mg of the fiber to be tested was cut into pieces approximately 1 cm long and placed in a 1.5 mL centrifuge tube. Infrared light (808 nm, 1 W / cm²) was used. 2 Irradiation.

[0050] Photothermal antibacterial treatment: Staphylococcus aureus and Escherichia coli were used as model bacteria; 10 mg of the test fiber was sterilized by UV irradiation for 15 min and then placed in a 1.5 mL centrifuge tube, and 0.2 mL of 10... 7 The bacterial suspension was prepared at CFU / mL and then irradiated with infrared light for 10 min. The experimental group was then incubated in a shaker at 37°C for 0.5 h, and then diluted to 10. 3 CFU / mL bacterial suspension was used for plate counting.

[0051] In this embodiment, Alg / TAFe2-TOBC1 spinning solution, Alg / TAFe1-TOBC1 spinning solution, Alg / TAFe2-TOBC2 spinning solution, sodium alginate spinning solution, and Alg / TA-Fe solution from Example 1 were used as the spinning solutions to be tested; Alg / TAFe2-TOBC1 fiber, Alg / TAFe1-TOBC1 fiber, Alg / TAFe2-TOBC2 fiber, sodium alginate fiber D, and sodium alginate fiber E were used as the fibers to be tested for various characterization and testing, and the results are shown in Table 1 and... Figure 2 The results are shown.

[0052] Table 1. Characterization and Test Results

[0053]

[0054] The characterization results of the single fiber mechanical properties of each fiber are shown in the figure. Figure 3 The fiber morphology characterization results for each fiber are shown in [the table below]. Figure 4 ,Depend on Figure 3 It can be seen that the tensile breaking strength of Alg / TAFe2-TOBC1 fiber, Alg / TAFe1-TOBC1 fiber, and Alg / TAFe2-TOBC2 fiber is 1.609–2.366 cN / dtex, which is significantly higher than that of sodium alginate fiber D and sodium alginate fiber E. This is because during the spinning process, the nanocellulose is highly oriented and assembled under tensile force. See [link to relevant documentation]. Figure 4 The fibers prepared using c, d, and e are highly oriented and have a dense structure; furthermore, as the proportion of cellulose increases, the fibers exhibit a more regular arrangement. Figure 4The surface of a single Alg / TAFe1-TOBC2 filament in e1 can be seen in close-up, observing a crumpled texture along its long axis, attributed to the lateral shrinkage during the drying process, which should further contribute to the orientation of the embedded fibers. In single alginate fiber D, the fibers are evenly distributed and oriented almost parallel along their long axis.

[0055] The results of the flame retardant test of each fiber are shown in Table 2. Figure 5 The results of the flame retardant test of each fiber are shown in Table 2. Figure 5 As can be seen, the cotton fiber has the largest integrated area of the exothermic curve, indicating that the cotton fiber is highly flammable; while the alginate fiber has a smaller total heat release (THR) and the highest heat release rate (PHRR), and the corresponding exothermic peak moves to 222°C; with the increase of the amount of nanocellulose, the total heat release and the highest heat release rate of the fiber increase as expected, but after adding 33% cellulose nanofiber, it is still lower than that of alginate fiber, even if the total solid content of cellulose reaches 66%, the total heat release (THR) and the highest heat release rate are still much lower than that of cotton fiber. It is speculated that the presence of Fe 3+ can significantly reduce the PHRR of CNF, and the presence of Fe 3+ catalyzes the thermal decomposition of nanocellulose, producing non-flammable gas and water, taking away most of the heat, thereby reducing the heat released by cellulose.

[0056] The results of the photothermal test of each fiber are shown in Table 3. Figure 6 The results of the photothermal antibacterial performance of each fiber are shown in Table 4. Figure 7 As can be seen from Table 1, Figure 6 and Figure 7 Compared with alginate fiber, Alg / TAFe2-TOBC1 fiber, Alg / TAFe1-TOBC1 fiber and Alg / TAFe2-TOBC2 fiber all have excellent photothermal properties, and can be heated to above 60°C after 5 minutes of infrared light irradiation. And no matter what the proportion of nanocellulose-based fiber, the antibacterial effect is about 99%, showing good photothermal antibacterial performance, and the survival rate of cells growing on the fiber for 1 day is 99.9%. In summary, the prepared nanocellulose-based fiber with flame retardant and photothermal antibacterial properties has excellent functionality, and is expected to be used in the field of medical materials such as biological dressings.

[0057] Although preferred embodiments of the present application have been described, those skilled in the art, once they know the basic creative concept, can make additional changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of the present application.

[0058] Obviously, many modifications and variations of the present application are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims and their equivalents, the application can be practiced otherwise than as specifically described.

Claims

1. A method for preparing nanocellulose-based fibers, characterized in that, Includes the following steps: The bacterial cellulose dispersion was oxidized to obtain an oxidized bacterial cellulose dispersion. Sodium alginate was dissolved in ultrapure water, and natural polyphenols were added under continuous stirring. The mixture was stirred until the solution was homogeneous, and then elemental iron was added. The mixture was stirred continuously until the solution turned dark purple to obtain a sodium alginate / natural polyphenol-iron solution. The oxidizing bacterial cellulose dispersion and the sodium alginate / natural polyphenol-iron solution are uniformly mixed to obtain a spinning solution; wherein the mass ratio of oxidizing bacterial cellulose to sodium alginate is 1:0.5~2.

0. The spinning solution is extruded into a coagulation bath to form continuous gel filaments, which are then soaked in the coagulation bath and washed in deionized water; after drying, the nanocellulose-based fibers are obtained.

2. The preparation method according to claim 1, characterized in that, The bacterial cellulose dispersion is a non-derivative bacterial cellulose dispersion with a mass percentage of 3 wt% to 8 wt%, obtained by mechanical shearing and homogenization. And / or, the sodium alginate is dissolved in ultrapure water, wherein the sodium alginate has a mass percentage of 3 wt% to 8 wt% in the ultrapure water; And / or, the added natural polyphenols are present in the ultrapure water at a mass percentage of 0.3 wt% to 0.8 wt%; And / or, the continuous stirring until the solution turns dark purple takes 20-30 hours; And / or, the mass percentage of the spinning solution is 3 wt% to 8 wt%.

3. The preparation method according to claim 1, characterized in that, The natural polyphenols are any one of tannic acid, gallic acid, catechins and catechins; And / or, the coagulation bath is an aqueous solution of calcium chloride; And / or, the mass concentration of the coagulation bath is 1%wt to 5%wt.

4. The preparation method according to claim 1, characterized in that, The oxidation treatment includes the following steps: The pH of the bacterial cellulose dispersion was adjusted to 10-10.5 with an alkaline solution, and 2,2,6,6-tetramethylpiperidine-nitrogen oxides and sodium bromide were added, followed by the addition of a sodium hypochlorite solution with a pH of 10-10.

5. The mixture was stirred at room temperature and the pH was maintained at 10-10.5 with an alkaline solution. After the reaction was complete, ethanol was added to quench the reaction, and the mixture was filtered to obtain the oxidizing bacteria cellulose dispersion.

5. Nanocellulose-based fibers prepared by the preparation method according to any one of claims 1 to 4.

6. The nanocellulose-based fiber according to claim 5, characterized in that, Its flame retardant properties are significantly better than those of cotton fiber.

7. The nanocellulose-based fiber according to claim 5, characterized in that, Its efficacy against Staphylococcus aureus and / or Escherichia coli is ≥99%.

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