Composite nanofiber membrane and preparation method and application thereof

Abstract

The application relates to a composite nanofiber membrane and a preparation method and application thereof, and belongs to the technical field of wearable electromagnetic shielding materials. The preparation method comprises the following steps: dissolving polyacrylonitrile in a solvent, spinning, and obtaining a polyacrylonitrile nanofiber membrane; then immersing the polyacrylonitrile nanofiber membrane in a tris-hydroxymethyl aminomethane hydrochloride solution containing dopamine; then immersing the dopamine-coated fiber membrane in a mixed solution containing a copper salt or a silver salt, and then immersing the dopamine-coated fiber membrane in a reaction solution, so as to obtain a modified nanofiber membrane; then spraying a dispersion liquid containing a conductive filler on the modified nanofiber membrane, so as to obtain a conductive filler modified nanofiber membrane; and finally dissolving polyurethane in a solvent, spinning the conductive filler modified nanofiber membrane as a receiver, and obtaining a composite nanofiber membrane. The composite nanofiber membrane has excellent electromagnetic shielding performance, directional sweat-removal capability, air permeability, light-heat conversion capability, antibacterial property, mechanical strength and flexibility.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of wearable electromagnetic shielding materials, and particularly relates to a composite nanofiber membrane, a preparation method and application thereof, and especially relates to the application of the composite nanofiber membrane in wearable electromagnetic shielding materials. BACKGROUND

[0002] With the rapid development and popularization of communication electronic devices and wearable flexible electronic devices, the electromagnetic radiation generated thereby not only interferes with the normal operation of electronic devices, but also poses a serious threat to human health, and therefore it is urgent to develop flexible wearable electromagnetic shielding materials to cope with the related electromagnetic pollution.

[0003] Electrospinning technology is a simple and universal method for preparing nanofiber. The polymer-based nanofiber membrane prepared by electrospinning method has the advantages of high flexibility, high porosity and strong self-supporting property, and provides an effective substrate for the loss of electromagnetic waves in the material. In recent years, various conductive fillers, including carbon fillers (carbon nanotubes, graphene, carbon fibers, etc.), metal nanoparticles or nanowires (silver nanoparticles or silver nanowires, etc.), transition metal carbides (MXene), have been grown or coated on flexible nanofiber membranes to develop flexible electromagnetic shielding materials. However, the research in the prior art mainly focuses on improving the electromagnetic shielding performance of the material, and often overlooks the challenges faced by wearable electromagnetic shielding materials during long-term wearing, such as the problem of stuffiness caused by sweat accumulation and bacterial growth. For example, Yang et al. prepared a stearic acid modified silver coated polyacrylonitrile nanofiber membrane (APAN-Ag-SA) (Superhydrophobic and Corrosion-Resistant Electrospun Hybrid Membrane for High-Efficiency Electromagnetic Interference Shielding, ACS Applied Electronic Materials (2021, 3, 2067-2078)), which has excellent shielding performance, but long-term wearing accumulates sweat, making people feel uncomfortable in a humid environment for a long time, and even bacteria can grow. Therefore, it has better practical application potential to develop a composite nanofiber membrane that can direct sweat, has antibacterial properties and is integrated with electromagnetic shielding.

[0004] In addition, most of the electromagnetic shielding nanofiber membranes prepared based on electrospinning cannot simultaneously consider mechanical strength and flexibility. SUMMARY

[0005] The present application provides a composite nanofiber membrane, a preparation method and application thereof, in order to solve the problem that the nanofiber membrane in the prior art cannot simultaneously consider electromagnetic shielding performance, wearing comfort (directional perspiration) and health protection (antibacterial property). The composite nanofiber membrane of the present application can simultaneously improve the electromagnetic shielding performance, moisture absorption and perspiration capacity, light-heat conversion capacity and antibacterial property by simulating the transpiration of plants and utilizing the synergistic effect of fillers, and can be applied as a wearable electromagnetic shielding material and has a wide application prospect in wearable devices.

[0006] The present application solves the above technical problems, and the technical solutions adopted are as follows.

[0007] In a first aspect, the present application provides a composite nanofiber membrane composed of a hydrophilic layer, an adhesive layer and a hydrophobic layer arranged in sequence.

[0008] The material of the hydrophilic layer is nanometer particle modified polyacrylonitrile, the material of the adhesive layer is conductive filler, and the material of the hydrophobic layer is polyurethane.

[0009] Preferably, the nanometer particles include but are not limited to one or more of copper sulfide nanometer particles, silver nanometer particles and gold nanometer particles.

[0010] Preferably, the conductive filler is MXene, acidified carbon nanotube or graphene; more preferably, the acidified carbon nanotube is a carbon nanotube acidified by a mixed acid of concentrated sulfuric acid and concentrated nitric acid.

[0011] Preferably, the thickness of the hydrophilic layer is 20-32 μm, and the pore size is 0.15-0.85 μm.

[0012] The thickness of the adhesive layer is 25-41 μm.

[0013] The thickness of the hydrophobic layer is 22-43 μm, and the pore size is 1-4.5 μm.

[0014] In a second aspect, the present application provides a preparation method of a composite nanofiber membrane, comprising the following steps:

[0015] Step one: dissolving polyacrylonitrile in a solvent to obtain polyacrylonitrile spinning solution, spinning to obtain polyacrylonitrile nanofiber membrane;

[0016] Step two: soaking the polyacrylonitrile nanofiber membrane obtained in step one in a dopamine-containing Tris-HCl solution, oscillating after reaction, taking out, repeatedly washing with deionized water and ethanol alternately, and drying to obtain dopamine-coated fiber membrane;

[0017] Step three: first immerse the dopamine-coated fiber membrane obtained in step two in an aqueous solution containing a copper salt for 2-6 h, then transfer the obtained immersed dopamine-coated fiber membrane into a mixed solution containing a copper salt, after complete immersion, add sodium thiosulfate, stir uniformly, react, after the reaction stops, take out, repeatedly alternate washing with water and ethanol, dry, and obtain a modified nanofiber membrane;

[0018] Alternatively, first immerse the dopamine-coated fiber membrane obtained in step two in an aqueous solution containing a silver salt for 2-6 h, then transfer the obtained immersed dopamine-coated fiber membrane into a silver amine solution, after complete immersion, add glucose, stir uniformly, react, after the reaction stops, take out, repeatedly alternate washing with water and ethanol, dry, and obtain a modified nanofiber membrane;

[0019] Step four: spray the dispersion liquid containing the conductive filler onto the modified nanofiber membrane prepared in step three, and dry to obtain a conductive filler modified nanofiber membrane;

[0020] Step five: dissolve the polyurethane into a solvent to obtain a polyurethane spinning solution, and spin with the conductive filler modified nanofiber membrane prepared in step four as a receiver to obtain a composite nanofiber membrane.

[0021] Preferably, in step one, the mass fraction of polyacrylonitrile in the polyacrylonitrile spinning solution is 10%-20%, the solvent is N,N-dimethylformamide, N-methyl pyrrolidone or tetrahydrofuran, the spinning voltage is 16-17 kV, and the spinning distance is 15-18 cm.

[0022] Preferably, in step two, the concentration of the tris-hydroxymethyl aminomethane hydrochloride solution containing dopamine is 7.9 mg·mL -1 , the pH is 8.5-9, the oscillation rate is 60-90 rpm, the reaction temperature is 40-60℃, and the reaction time is 12-24 h.

[0023] Preferably, in step two, the drying temperature is 338 K.

[0024] Preferably, in step two, the fiber diameter of the dopamine-coated fiber membrane is 150-290 nm.

[0025] Preferably, in step three, the concentration of the aqueous solution containing a copper salt is 0.025-0.175 mol / L, and the copper salt is copper acetate, copper sulfate, copper chloride or copper nitrate, more preferably, the copper salt is copper acetate.

[0026] Preferably, in step three, the copper salt in the mixed solution is copper acetate, copper sulfate, copper chloride or copper nitrate, the concentration of the copper salt is 0.025-0.175 mol / L, the mixed solution is a mixture of water and ethylene glycol in a volume ratio of 1:1-1:3, the molar ratio of the copper salt to sodium thiosulfate is 1:1-1:3, the reaction time is 4-7 h, and the reaction temperature is 70-180℃; more preferably, the copper salt is copper acetate.

[0027] Preferably, in step three, the concentration of the silver salt in the aqueous solution is 0.1-0.3 mol / L, and the silver salt is silver nitrate.

[0028] Preferably, in step three, the concentration of the silver nitrate is 0.1-0.3 mol / L, the molar ratio of silver ions in the silver ammine solution to glucose is 1:2, the reaction time is 0.5-4 h, and the reaction temperature is 70-90℃.

[0029] Preferably, in step three, after the dopamine-coated fiber membrane obtained in step two is soaked in the aqueous solution containing the copper salt for 2-6 h, the dopamine-coated fiber membrane is dried, and then the dried dopamine-coated fiber membrane is transferred into the mixed solution containing the copper salt for soaking.

[0030] Preferably, in step three, after the dopamine-coated fiber membrane obtained in step two is soaked in the aqueous solution containing the silver salt for 2-6 h, the dopamine-coated fiber membrane is dried, and then the dried dopamine-coated fiber membrane is transferred into the silver ammine solution for soaking.

[0031] It should be noted that the silver ammine solution is a prior art, and its preparation process is as follows: first, prepare a silver nitrate solution, then add sodium hydroxide to the silver nitrate solution until the solution becomes turbid, at this time, add ammonia water (25wt%-28wt%) dropwise to the solution until the solution becomes clear, and obtain the silver ammine solution. Because the preparation of the silver ammine solution is stopped by the clarification phenomenon, the concentration of the silver ammine solution is calculated based on the concentration of silver nitrate.

[0032] Preferably, in step four, the concentration of the conductive filler in the dispersion is 8-20 mg / L, and the spraying rate is 10-20 ml / h.

[0033] Preferably, in step five, the mass fraction of polyurethane in the polyurethane spinning solution is 20%-25%, the spinning voltage is 14-15 kV, and the spinning distance is 15-18 cm; the solvent is one of N,N-dimethylformamide, N-methylpyrrolidone or tetrahydrofuran.

[0034] In a third aspect, the application further provides a use of the composite nanofiber membrane in a wearable electromagnetic shielding material.

[0035] Compared with the prior art, the application has the following beneficial effects:

[0036] The composite nanofiber membrane of the application has excellent electromagnetic shielding performance, can be used in smart wearable clothes, reduces the radiation exposure of electronic devices to the human body, and protects the health of the human body.

[0037] The composite nanofiber membrane of the application has excellent air permeability and directional moisture absorption and sweat release capacity, ensuring the comfort during long-term wearing.

[0038] The composite nanofiber membrane of the application also has excellent light-heat conversion capacity, ensuring the thermal comfort of the body in a cold environment, and the composite nanofiber membrane has antibacterial capacity for Escherichia coli and Staphylococcus aureus, avoiding bacterial breeding in a humid environment.

[0039] The combination of polyacrylonitrile and polyurethane nanofiber in the composite nanofiber membrane of the application not only improves the elongation at break of the polyacrylonitrile electrospun fiber membrane but also improves the mechanical strength of the polyurethane electrospun fiber membrane, so that the composite nanofiber membrane exhibits good mechanical strength and flexibility and still maintains excellent electromagnetic shielding performance after 100 times of bending and folding.

[0040] The preparation method of the composite nanofiber membrane of the application can control the loading amount of the conductive filler by adjusting the concentration of the dispersion liquid containing the conductive filler, so as to maintain the excellent moisture absorption and sweat release performance of the material while giving it excellent electromagnetic shielding performance.

[0041] The preparation method of the composite nanofiber membrane of the application is simple in process and has wide application prospects in wearable devices. BRIEF DESCRIPTION OF DRAWINGS

[0042] In order to more clearly illustrate the technical solutions of the embodiments of the application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0043] Figure 1 The cross-sectional scanning electron microscope (SEM) image of the composite nanofiber membrane prepared for the application example 1;

[0044] Figure 2 The electromagnetic shielding performance diagram of the composite nanofiber membrane prepared for the application example 1;

[0045] Figure 3 The water contact angle change diagram of the composite nanofiber membrane prepared for the application example 1 under the condition of anti-gravity;

[0046] Figure 4The photothermal cycle curve of the composite nanofiber membrane prepared for the embodiment 1 of the present application;

[0047] Figure 5 The plate test chart of the composite nanofiber membrane prepared for the embodiment 1 of the present application, wherein a is the E. coli colony photo (without adding the composite nanofiber membrane), b is the E. coli colony photo with the composite nanofiber membrane added, c is the S. aureus colony photo (without adding the composite nanofiber membrane), and d is the S. aureus colony photo with the composite nanofiber membrane added. DETAILED DESCRIPTION

[0048] In order for those skilled in the art to better understand the technical solutions of the present application, the present application will be further described in detail below in combination with embodiments.

[0049] In the following embodiments, various processes and methods that are not described in detail are conventional methods known in the art.

[0050] The materials, reagents, devices, instruments, equipment, etc. used in the following embodiments can be obtained from commercial channels unless otherwise specified.

[0051] In the present application, the scanning electron microscope testing instrument used is HITACHI-SU8020. The electromagnetic shielding performance testing instrument is a vector network analyzer Agilent PNA-N5244A. The conductivity testing instrument is a four-probe tester Keithley2450. The mechanical property testing instrument is a Japanese Shimadzu AG-1KN type electronic universal material testing machine. The constant temperature and humidity box is HWS-80. The water contact angle testing instrument is Germany-Dataphysics-OCA20. The antibacterial detection method is as follows: first, 10 μL of bacterial solution (E. coli or S. aureus bacterial solution) is added to a centrifuge tube containing 20 mL nutrient broth, and then the centrifuge tube is placed in a constant temperature incubator at 37°C at a speed of 200 rpm / min for 24 h. Then the obtained bacterial solution is diluted to 10 6 CFU / mL, and 10 μL of the diluted bacterial solution is added to the nutrient broth containing the composite nanofiber membrane, and then the material is irradiated with NIR laser (50 mW / cm 2 ) for 5 min, and then placed in a constant temperature incubator for 24 h. Finally, the bacterial solution after 24 h of reaction is diluted to 10 5 CFU / mL, and 10 μL is taken for plate counting.

[0052] Embodiment 1

[0053] Step one: 1 g of polyacrylonitrile was first added to 9 g of N,N-dimethylformamide and stirred overnight until the solution was completely dissolved, then the obtained spinning solution was loaded into a syringe for spinning, obtaining polyacrylonitrile nanofiber membrane, wherein the voltage of the electrospinning machine was 16 kV, and the spinning distance was 18 cm.

[0054] Step two: the polyacrylonitrile nanofiber membrane was immersed in 100 mL of a Tris-HCl solution containing dopamine (concentration of 7.9 mg·mL -1 , pH = 8.5) and oscillated on a shaking table at 40°C for 24 h, the shaking table oscillation rate was 90 rpm, then deionized water and ethanol were repeatedly alternately washed, and then placed in an oven (338 K) for drying, obtaining dopamine-coated fiber membrane, the fiber diameter was 150-290 nm.

[0055] Step three: the dopamine-coated fiber membrane was first immersed in a copper acetate (0.15 mol / L) aqueous solution for 2 h, then the obtained immersed dopamine-coated fiber membrane was transferred into a mixed solution (the solution was a mixed solution of water and ethylene glycol, the volume ratio was 20 mL:60 mL) containing copper acetate (0.15 mol / L), after the membrane was completely immersed, sodium thiosulfate was added (the molar ratio of copper acetate to sodium thiosulfate was 1:1), after stirring uniformly, the reaction was carried out at 70°C in an oil bath for 4 h, after the reaction stopped, it was taken out, washed with water and ethanol alternately, and dried, obtaining a modified nanofiber membrane, i.e. a copper sulfide nanoparticle modified nanofiber membrane, wherein the diameter of the copper sulfide nanoparticle was about 20 nm, which could be well anchored on the fiber and did not affect the pore size between the fibers, and was not easy to fall off.

[0056] Step four: the modified nanofiber membrane was cut into 7x7 cm, and a MXene dispersion solution with a concentration of 9.8 mg / L was uniformly sprayed onto the modified nanofiber membrane at a rate of 10 ml / h, obtaining a conductive filler modified nanofiber membrane.

[0057] Step five: polyurethane was dissolved in DMF to obtain a 25wt% polyurethane spinning solution, and the conductive filler modified nanofiber membrane prepared in step four was used as a receiver for spinning, obtaining a composite nanofiber membrane, the spinning voltage was 14 kV, the spinning time was 1 h, and the spinning distance was 15 cm.

[0058] The hydrophilic layer (CuS@PDA / PAN) of the composite nanofiber membrane prepared in Example 1 had a thickness of about 27 μm, the adhesive layer (MXene) had a thickness of about 39 μm, and the hydrophobic layer (TPU) had a thickness of about 22 μm; the pore size of the hydrophilic layer was 0.25-0.65 μm, and the pore size of the hydrophobic layer was 1.05-4.05 μm.

[0059] Figure 1A cross-sectional scanning electron microscope (SEM) image of the composite nanofiber membrane prepared in Example 1; it can be seen from Figure 1 that the nanofiber membrane as a whole is a porous structure, and shows a difference in pore size in the thickness direction. It was detected that the electromagnetic shielding value of the composite nanofiber membrane prepared in Example 1 in the X-band was 50 dB Figure 2 , the conductivity was 54 S / cm, and after 100 times of bending and folding, it still maintained excellent electromagnetic shielding performance, with an electromagnetic shielding value of 48 dB. In order to verify the directional sweat-wicking ability and air permeability of the composite nanofiber membrane, a negative gravity water contact angle test Figure 3 and a water vapor transmission rate experiment were carried out, and the composite nanofiber membrane could quickly evaporate sweat within 10 s, and had excellent air permeability, with a water vapor transmission rate of 720 g·m -2 ·d -1 , which was much higher than the air permeability of human skin. In addition, the equilibrium temperature of the composite nanofiber membrane could quickly rise from 24°C to 50°C under the irradiation of a xenon lamp at 50 mW / cm 2 , and the photothermal curves after 5 cycles were almost identical, as shown in Figure 4 , indicating that the composite nanofiber membrane had excellent photothermal stability. The antibacterial rates of the composite nanofiber membrane against E. coli and S. aureus were 95% and 99%, respectively, as shown in Figure 5 . At the same time, the composite nanofiber membrane had good tensile strength and elongation at break, which were 9 MPa and 230%, respectively.

[0060] Example 2

[0061] Step 1: First, 1 g of polyacrylonitrile was added to 9 g of N,N-dimethylformamide and stirred overnight until the solution was completely dissolved, and then the obtained spinning solution was loaded into a syringe for spinning to obtain a polyacrylonitrile nanofiber membrane, wherein the voltage of the electrospinning machine was 16 kV, and the spinning distance was 18 cm.

[0062] Step 2: The polyacrylonitrile nanofiber membrane was immersed in 100 mL of a Tris-HCl solution containing dopamine (concentration of 7.9 mg·mL -1 , pH = 8.5) and oscillated on a shaking table at 40°C for 24 h, and the shaking table oscillation rate was 90 rpm, and then it was repeatedly washed with deionized water and ethanol, and then dried in an oven (338 K) to obtain a dopamine-coated fiber membrane, with a fiber diameter of 150-290 nm.

[0063] Step three: first, the dopamine-coated fiber membrane was immersed in a copper acetate (0.125 mol / L) aqueous solution for 2 h, then the obtained dopamine-coated fiber membrane after immersion was transferred into a mixed solution (the solution was a mixed solution of water and ethylene glycol, the volume ratio was 20 mL:60 mL) containing copper acetate (0.125 mol / L), after the membrane was completely soaked, sodium thiosulfate was added (the molar ratio of copper acetate to sodium thiosulfate was 1:1), after stirring uniformly, the reaction was carried out at 70°C in an oil bath for 4 h, after the reaction stopped, it was taken out, washed repeatedly with water and ethanol alternately, and dried to obtain a modified nanofiber membrane, that is, a copper sulfide nanoparticle modified composite nanofiber, wherein the diameter of the copper sulfide nanoparticle is about 20 nm, which can be well anchored on the fiber and does not affect the pore size between the fibers, and is not easy to fall off.

[0064] Step four: the modified nanofiber membrane was cut into 7x7 cm, and a dispersion liquid of MXene with a concentration of 8.9 mg / L was uniformly sprayed onto the modified nanofiber membrane at a rate of 10 ml / h to obtain a conductive filler modified nanofiber membrane.

[0065] Step five: polyurethane was dissolved in DMF to obtain a 25wt% polyurethane spinning solution, and the conductive filler modified nanofiber membrane prepared in step four was used as a receiver for spinning to obtain a composite nanofiber membrane, the spinning voltage was 14 kV, the spinning time was 4 h, and the spinning distance was 15 cm.

[0066] The hydrophilic layer (CuS@PP) of the composite nanofiber membrane prepared in Example 2 has a thickness of about 27 μm, the adhesive layer (MXene) has a thickness of about 30 μm, and the hydrophobic layer (TPU) has a thickness of about 42 μm; the pore size of the hydrophilic layer is 0.25-0.65 μm, and the pore size of the hydrophobic layer is 1.05-4.05 μm.

[0067] It was detected that the electromagnetic shielding value of the composite nanofiber membrane prepared in Example 2 in the X-band was 40 dB, the conductivity was 45 S / cm, and after 100 times of bending and folding, it could still maintain excellent electromagnetic shielding performance, and the electromagnetic shielding value was 38 dB. The composite nanofiber membrane can evaporate sweat within 60 s, and the water vapor transmission rate is 420 g·m -2 ·d -1 In addition, the equilibrium temperature of the composite nanofiber membrane can quickly rise from 24°C to 45°C under the irradiation of a 50 mW / cm 2 Xenon lamp, and the photothermal curve after 5 cycles is almost identical, indicating that the composite nanofiber membrane has excellent photothermal stability. The antibacterial rates of the composite nanofiber membrane on Escherichia coli and Staphylococcus aureus are 90% and 95%, respectively. At the same time, the composite nanofiber membrane has good tensile strength and elongation at break, which are 9.2 MPa and 230%, respectively.

[0068] Example 3

[0069] Step one: First, 1 g of polyacrylonitrile was added to 9 g of N,N-dimethylformamide and stirred overnight until the solution was completely dissolved, then the obtained spinning solution was loaded into a syringe for spinning to obtain a polyacrylonitrile nanofiber membrane, wherein the voltage of the electrospinning machine was 16 kV, and the spinning distance was 18 cm.

[0070] Step two: The polyacrylonitrile nanofiber membrane was immersed in 100 mL of a Tris-HCl solution containing dopamine (concentration of 7.9 mg·mL -1 , pH = 8.5) and shaken on a shaking table at 40°C for 24 h, with a shaking table shaking rate of 90 rpm, and then repeatedly washed with deionized water and ethanol alternately, and then placed in an oven (338 K) for drying to obtain a dopamine-coated fiber membrane with a fiber diameter of 150-290 nm.

[0071] Step three: The dopamine-coated fiber membrane was first immersed in a copper sulfate (0.175 mol / L) aqueous solution for 2 h, and then the obtained immersed dopamine-coated fiber membrane was transferred into a mixed solution (the solution was a mixed solution of water and ethylene glycol with a volume ratio of 20 mL:60 mL) containing copper sulfate (0.175 mol / L), and after the membrane was completely soaked, sodium thiosulfate was added (the molar ratio of copper sulfate to sodium thiosulfate was 1:1), and after stirring, the reaction was carried out at 70°C in an oil bath for 4 h. After the reaction stopped, it was taken out, washed with water and ethanol alternately, and dried to obtain a modified nanofiber membrane, i.e., a copper sulfide nanotube modified composite nanofiber, wherein the diameter of the copper sulfide nanotube was about 400 nm, which was not easy to anchor on the fiber and was easy to cover the surface of the fiber and easily fall off.

[0072] Step four: The modified nanofiber membrane was cut into 7x7 cm, and a dispersion liquid of MXene with a concentration of 9.8 mg / L was uniformly sprayed onto the modified nanofiber membrane at a rate of 10 ml / h to obtain a conductive filler modified nanofiber membrane.

[0073] Step five: Polyurethane was dissolved in DMF to obtain a 25 wt% polyurethane spinning solution, and the conductive filler modified nanofiber membrane prepared in step four was used as a receiver for spinning to obtain a composite nanofiber membrane, with a spinning voltage of 14 kV, a spinning time of 1 h, and a spinning distance of 15 cm.

[0074] The hydrophilic layer (CuS@PDA / PAN) of the composite nanofiber membrane prepared in Example 3 had a thickness of about 30 μm, the adhesive layer (MXene) had a thickness of about 39 μm, and the hydrophobic layer (TPU) had a thickness of about 22 μm; the pore size of the hydrophilic layer was 0.2-0.45 μm, and the pore size of the hydrophobic layer was 1.05-4.05 μm.

[0075] The composite nanofiber membrane prepared in Example 3 has an electromagnetic shielding value of 40 dB in the X-band, an electrical conductivity of 35 S / cm, and an electromagnetic shielding value of 28 dB after 100 bending and folding. The composite nanofiber membrane can evaporate sweat within 12 s, with a water vapor transmission rate of 570 g·m -2 ·d -1 The equilibrium temperature of the composite nanofiber membrane can quickly rise from 24°C to 40°C under 50 mW / cm 2 of xenon lamp irradiation, and the photothermal curves after 5 cycles are almost identical, indicating that the composite nanofiber membrane has excellent photothermal stability. The antibacterial rates of the composite nanofiber membrane against E. coli and S. aureus are 87% and 90%, respectively. At the same time, the composite nanofiber membrane has good tensile strength and elongation at break, which are 8.9 MPa and 200%, respectively.

[0076] Example 4

[0077] Step one: First, 1 g of polyacrylonitrile was added to 9 g of N,N-dimethylformamide and stirred overnight until the solution was completely dissolved, then the obtained spinning solution was loaded into a syringe for spinning to obtain a polyacrylonitrile nanofiber membrane, wherein the voltage of the electrospinning machine was 16 kV and the spinning distance was 18 cm.

[0078] Step two: The polyacrylonitrile nanofiber membrane was immersed in 100 mL of a Tris-HCl solution containing dopamine (concentration of 7.9 mg·mL -1 , pH = 8.5) and oscillated on a shaking table at 40°C for 24 h, with a shaking table oscillation rate of 90 rpm, then repeatedly washed with deionized water and ethanol alternately, and then dried in an oven (338 K) to obtain a dopamine-coated fiber membrane with a fiber diameter of 150-290 nm.

[0079] Step three: First, the dopamine-coated fiber membrane was immersed in a copper chloride (0.15 mol / L) aqueous solution for 2 h, then the obtained immersed dopamine-coated fiber membrane was transferred to a mixed solution containing copper chloride (0.15 mol / L) (the solution was a mixed solution of water and ethylene glycol with a volume ratio of 20 mL:60 mL), and after the membrane was completely immersed, sodium thiosulfate was added (the molar ratio of copper chloride to sodium thiosulfate was 1:1), and after stirring, the reaction was carried out at 70°C in an oil bath for 4 h. After the reaction stopped, it was taken out, washed with water and ethanol alternately, and dried to obtain a modified nanofiber membrane, i.e., a composite nanofiber modified by copper sulfide nanosheets, wherein the copper sulfide nanosheets have a thickness of about 25 nm and a diameter of about 70 nm, are not easy to anchor on the fiber, are easy to cover on the fiber surface, and are extremely easy to fall off.

[0080] Step four: The modified nanofiber membrane was cut into 7x7cm, and the dispersion liquid containing MXene with a concentration of 10.5mg / L was uniformly sprayed onto the modified nanofiber membrane at a rate of 10ml / h to obtain a conductive filler modified nanofiber membrane.

[0081] Step five: The polyurethane was dissolved in DMF to obtain a 25wt% polyurethane spinning solution, and the conductive filler modified nanofiber membrane prepared in step four was used as a receiver to spin to obtain a composite nanofiber membrane, the spinning voltage was 14kV, the spinning time was 1h, and the spinning distance was 15cm.

[0082] The hydrophilic layer (CuS@PDA / PAN) of the composite nanofiber membrane prepared in Example 4 had a thickness of about 27μm, the adhesive layer (MXene) had a thickness of about 40μm, and the hydrophobic layer (TPU) had a thickness of about 22μm; the hydrophilic layer had a pore size of 0.2~0.42μm, and the hydrophobic layer had a pore size of 1.05~4.05μm.

[0083] It was detected that the electromagnetic shielding value of the composite nanofiber membrane prepared in Example 4 in the X-band was 54dB, the conductivity was 60S / cm, and the electromagnetic shielding value was 35dB after 100 times of bending and folding. The composite nanofiber membrane could evaporate sweat quickly within 23s, and the water vapor transmission rate was 490g·m -2 ·d -1 In addition, the equilibrium temperature of the composite nanofiber membrane could quickly rise from 24℃ to 55℃ under the irradiation of a xenon lamp at 50mW / cm 2 After 5 cycles, the photothermal curves were almost consistent, indicating that the composite nanofiber membrane had excellent photothermal stability. The antibacterial rates of the composite nanofiber membrane on E. coli and S. aureus were 95% and 99%, respectively. At the same time, the composite nanofiber membrane had good tensile strength and elongation at break, which were 8.7MPa and 210%, respectively.

[0084] Example 5

[0085] Step one: First, 1g of polyacrylonitrile was added to 9g of N,N-dimethylformamide and stirred overnight until the solution was completely dissolved, then the obtained spinning solution was loaded into a syringe for spinning to obtain a polyacrylonitrile nanofiber membrane, wherein the voltage of the electrospinning machine was 16kV, and the spinning distance was 18cm.

[0086] Step two: The polyacrylonitrile nanofiber membrane was immersed in 100mL of a Tris-HCl solution containing dopamine (the concentration was 7.9mg·mL -1, pH = 8.5) and oscillated on a shaker at 40℃ for 24h at a shaker oscillation rate of 90rpm, and then repeatedly washed with deionized water and ethanol alternately, and then dried in an oven (338K) to obtain a dopamine-coated fiber membrane with a fiber diameter of 150-290nm.

[0087] Step three: the dopamine-coated fiber membrane was first immersed in a copper nitrate (0.15mol / L) aqueous solution for 2h, and then the obtained immersed dopamine-coated fiber membrane was transferred into a mixed solution (the solution is a mixed solution of water and ethylene glycol with a volume ratio of 20mL:60mL) containing copper nitrate (0.15mol / L), and after the membrane was completely soaked, sodium thiosulfate was added (the molar ratio of copper nitrate to sodium thiosulfate was 1:1), and after stirring uniformly, the reaction was carried out at 180℃ in an oil bath for 4h, and after the reaction stopped, it was taken out, washed with water and ethanol alternately, and dried to obtain a modified nanofiber membrane, i.e. a copper sulfide nanotube modified composite nanofiber, wherein the diameter of the copper sulfide tube is about 500nm, which is not easy to anchor on the fiber, but easy to cover on the fiber surface, and easy to fall off.

[0088] Step four: the modified nanofiber membrane was cut into 7x7cm, and a dispersion liquid containing MXene with a concentration of 9.8mg / L was uniformly sprayed onto the modified nanofiber membrane at a rate of 10ml / h to obtain a conductive filler modified nanofiber membrane.

[0089] Step five: polyurethane was dissolved in DMF to obtain a 25wt% polyurethane spinning solution, and the conductive filler modified nanofiber membrane prepared in step four was used as a receiver to spin to obtain a composite nanofiber membrane, with a spinning voltage of 14kV, a spinning time of 1h, and a spinning distance of 15cm.

[0090] The hydrophilic layer (CuS@PDA / PAN) of the composite nanofiber membrane prepared in Example 5 has a thickness of about 30μm, the adhesive layer (MXene) has a thickness of about 39μm, and the hydrophobic layer (TPU) has a thickness of about 22μm; the pore size of the hydrophilic layer is 0.2-0.42μm, and the pore size of the hydrophobic layer is 1.05-4.05μm.

[0091] It was detected that the electromagnetic shielding value of the composite nanofiber membrane prepared in Example 5 in the X-band was 49dB, the conductivity was 52S / cm, and the electromagnetic shielding value was 32dB after 100 times of bending and folding. The composite nanofiber membrane can evaporate sweat quickly within 28s, and the water vapor transmission rate is 490g·m -2 ·d -1 In addition, the composite nanofiber membrane can evaporate sweat quickly within 28s, and the water vapor transmission rate is 490g·m 2The equilibrium temperature under the xenon lamp irradiation can be quickly increased from 24℃ to 50℃, and the photothermal curves after 5 cycles are almost consistent, indicating that the composite nanofiber membrane has excellent photothermal stability. The antibacterial rates of the composite nanofiber membrane against E. coli and S. aureus are 95% and 99%, respectively. Meanwhile, the composite nanofiber membrane has good tensile strength and elongation at break, which are 8.7 MPa and 210%, respectively.

[0092] Example 6

[0093] Step one: First, 1 g of polyacrylonitrile was added to 9 g of N,N-dimethylformamide and stirred overnight until the solution was completely dissolved, then the obtained spinning solution was loaded into a syringe for spinning to obtain a polyacrylonitrile nanofiber membrane, wherein the voltage of the electrospinning machine was 16 kV, and the spinning distance was 18 cm.

[0094] Step two: The polyacrylonitrile nanofiber membrane was immersed in 100 mL of a Tris-HCl solution containing dopamine (concentration of 7.9 mg·mL-1, pH=8.5) and shaken on a shaking table at 40℃ for 24 h, and the shaking table shaking rate was 90 rpm, then it was repeatedly washed with deionized water and ethanol alternately, and then dried in an oven (338 K) to obtain a dopamine-coated fiber membrane with a fiber diameter of 150-290 nm.

[0095] Step three: The dopamine-coated fiber membrane was first immersed in a copper nitrate (0.15 mol / L) aqueous solution for 2 h, then the obtained immersed dopamine-coated fiber membrane was transferred into a mixed solution (the solution was a mixture of water and ethylene glycol with a volume ratio of 20 mL:20 mL) containing copper nitrate (0.15 mol / L), after the membrane was completely immersed, sodium thiosulfate was added (the molar ratio of copper nitrate to sodium thiosulfate was 1:1), after stirring uniformly, the reaction was carried out at 70℃ in an oil bath for 4 h, after the reaction stopped, it was taken out, washed with water and ethanol alternately, and dried to obtain a modified nanofiber membrane, i.e. a copper sulfide nanotube modified composite nanofiber, wherein the diameter of the copper sulfide tube is about 600 nm, which is not easy to anchor on the fiber, but easy to cover on the fiber surface, and easy to fall off.

[0096] Step four: The modified nanofiber membrane was cut into 7x7 cm, and a dispersion liquid containing MXene with a concentration of 9.8 mg / L was uniformly sprayed onto the modified nanofiber membrane at a rate of 10 ml / h to obtain a conductive filler modified nanofiber membrane.

[0097] Step five: Polyurethane was dissolved in DMF to obtain a 25wt% polyurethane spinning solution, and the conductive filler modified nanofiber membrane prepared in step four was used as a receiver for spinning to obtain a composite nanofiber membrane, the spinning voltage was 14 kV, the spinning time was 1 h, and the spinning distance was 15 cm.

[0098] The composite nanofiber membrane prepared in Example 6 has a hydrophilic layer (CuS@PDA / PAN) thickness of about 30 μm, an adhesive layer (MXene) thickness of about 39 μm, and a hydrophobic layer (TPU) thickness of about 22 μm; the hydrophilic layer has a pore size of 0.2-0.42 μm, and the hydrophobic layer has a pore size of 1.05-4.05 μm.

[0099] It is detected that the composite nanofiber membrane prepared in Example 6 has an electromagnetic shielding value of 49 dB in the X-band, an electrical conductivity of 52 S / cm, and an electromagnetic shielding value of 30 dB after 100 times of bending and folding. The composite nanofiber membrane can quickly evaporate sweat within 30 s, and has a water vapor transmission rate of 485 g·m -2 ·d -1 In addition, the composite nanofiber membrane can quickly increase the equilibrium temperature from 24℃ to 50℃ under the irradiation of a xenon lamp at 50 mW / cm 2 After 5 cycles, the photothermal curves are almost identical, indicating that the composite nanofiber membrane has excellent photothermal stability. The composite nanofiber membrane has an antibacterial rate of 95% and 99% against Escherichia coli and Staphylococcus aureus, respectively. At the same time, the composite nanofiber membrane has good tensile strength and elongation at break, which are 8.6 MPa and 210%, respectively.

[0100] Example 7

[0101] Step 1: First, 1 g of polyacrylonitrile is added to 9 g of N,N-dimethylformamide and stirred overnight until the solution is completely dissolved, and then the obtained spinning solution is loaded into a syringe for spinning to obtain a polyacrylonitrile nanofiber membrane, wherein the voltage of the electrospinning machine is 16 kV, and the spinning distance is 18 cm.

[0102] Step 2: The polyacrylonitrile nanofiber membrane is immersed in 100 mL of a Tris-HCl solution containing dopamine (concentration of 7.9 mg·mL -1 , pH=8.5) and oscillated on a shaking table at 40℃ for 24 h, and the shaking table oscillation rate is 90 rpm, and then repeatedly washed with deionized water and ethanol alternately, and then placed in an oven (338 K) for drying to obtain a dopamine-coated fiber membrane, and the fiber diameter is 150-290 nm.

[0103] Step three: the dopamine coated fiber membrane was first immersed in a copper acetate (0.15 mol / L) aqueous solution for 2 h, and then the obtained dopamine coated fiber membrane after immersion was transferred into a mixed solution (the solution was a mixed solution of water and ethylene glycol with a volume ratio of 20 mL:60 mL) containing copper acetate (0.15 mol / L). After the membrane was completely immersed, sodium thiosulfate was added (the molar ratio of copper acetate to sodium thiosulfate was 1:1). After stirring uniformly, the reaction was carried out at 70°C in an oil bath for 4 h. After the reaction stopped, the product was taken out, washed repeatedly with water and ethanol, and dried to obtain a modified nanofiber membrane, i.e. a copper sulfide nanoparticle modified composite nanofiber, wherein the diameter of the copper sulfide nanoparticles was about 20 nm, which could be well anchored on the fiber and did not affect the pore size between the fibers, nor was it easy to fall off.

[0104] Step four: the modified nanofiber membrane was cut into 7x7 cm, and a dispersion liquid containing acidified carbon nanotubes with a concentration of 9.8 mg / L was uniformly sprayed onto the modified nanofiber membrane at a rate of 10 ml / h to obtain a conductive filler modified nanofiber membrane, wherein the acidified carbon nanotubes were carbon nanotubes acidified by concentrated sulfuric acid and concentrated nitric acid with a volume ratio of 3:1, the acidification temperature was 60-120°C, and the acidification time was 2-8 h.

[0105] Step five: polyurethane was dissolved in DMF to obtain a 25wt% polyurethane spinning solution, and the conductive filler modified nanofiber membrane prepared in step four was used as a receiver for spinning to obtain a composite nanofiber membrane, with a spinning voltage of 14 kV, a spinning time of 1 h, and a spinning distance of 15 cm.

[0106] The hydrophilic layer (CuS@PDA / PAN) of the composite nanofiber membrane prepared in Example 7 had a thickness of about 27 μm, the adhesive layer (acidified carbon nanotubes) had a thickness of about 29 μm, and the hydrophobic layer (TPU) had a thickness of about 22 μm; the pore size of the hydrophilic layer was 0.3-0.65 μm, and the pore size of the hydrophobic layer was 1.05-4.05 μm.

[0107] It was detected that the electromagnetic shielding value of the composite nanofiber membrane prepared in Example 7 in the X-band was 42 dB, the conductivity was 24 S / cm, and after 100 times of bending and folding, the composite nanofiber membrane still maintained excellent electromagnetic shielding performance, with an electromagnetic shielding value of 38 dB. The composite nanofiber membrane could evaporate sweat quickly within 10 s, and the water vapor transmission rate of the composite nanofiber membrane was 693 g·m -2 ·d -1 In addition, the composite nanofiber membrane could maintain a temperature of 25°C for 50 mW / cm 2The equilibrium temperature under the xenon lamp irradiation can be quickly increased from 24 °C to 45 °C, and the photothermal curves after 5 cycles are almost consistent, indicating that the composite nanofiber membrane has excellent photothermal stability. The antibacterial rates of the composite nanofiber membrane against E. coli and S. aureus are 80% and 85%, respectively. At the same time, the composite nanofiber membrane has good tensile strength and elongation at break, which are 8.5 MPa and 200%, respectively.

[0108] Example 8

[0109] Step one: First, 1 g of polyacrylonitrile was added to 9 g of N,N-dimethylformamide and stirred overnight until the solution was completely dissolved, then the obtained spinning solution was loaded into a syringe for spinning to obtain a polyacrylonitrile nanofiber membrane, wherein the voltage of the electrospinning machine was 16 kV, and the spinning distance was 18 cm.

[0110] Step two: The polyacrylonitrile nanofiber membrane was immersed in 100 mL of a Tris-HCl solution containing dopamine (concentration of 7.9 mg·mL -1 , pH = 8.5) and oscillated on a shaking table at 40 °C for 24 h, with a shaking table oscillation rate of 90 rpm, and then repeatedly washed with deionized water and ethanol alternately, and then placed in an oven (338 K) for drying to obtain a dopamine-coated fiber membrane with a fiber diameter of 150-290 nm.

[0111] Step three: The dopamine-coated fiber membrane obtained in step two was first immersed in an aqueous solution containing silver nitrate (0.2 mol / L) for 2 h, and then the obtained immersed dopamine-coated fiber membrane was transferred into a silver ammine solution (concentration of silver nitrate was 0.2 mol / L) for immersion, after the membrane was completely immersed, glucose was added, the molar ratio of silver ions to glucose in the silver ammine solution was 1:2, after uniform stirring, the reaction was carried out at 70 °C for 4 h, after the reaction stopped, it was taken out, washed with water and ethanol alternately, and dried to obtain a modified nanofiber membrane, i.e. a silver nanoparticle modified composite nanofiber, wherein the diameter of the silver nanoparticles was about 30 nm.

[0112] Step four: The modified nanofiber membrane was cut into 7x7 cm, and a dispersion liquid containing MXene with a concentration of 9.8 mg / L was uniformly sprayed onto the modified nanofiber membrane at a rate of 10 ml / h to obtain a conductive filler modified nanofiber membrane.

[0113] Step five: Polyurethane was dissolved in DMF to obtain a 25 wt% polyurethane spinning solution, and the conductive filler modified nanofiber membrane prepared in step four was used as a receiver for spinning to obtain a composite nanofiber membrane, with a spinning voltage of 14 kV, a spinning time of 1 h, and a spinning distance of 15 cm.

[0114] The composite nanofiber membrane prepared in Example 8 has a hydrophilic layer (Ag@PDA / PAN) thickness of about 28 μm, an adhesive layer (MXene) thickness of about 39 μm, and a hydrophobic layer (TPU) thickness of about 22 μm; the hydrophilic layer has a pore size of 0.25-0.65 μm, and the hydrophobic layer has a pore size of 1.05-4.05 μm.

[0115] It was detected that the composite nanofiber membrane prepared in Example 8 has an electromagnetic shielding value of 90 dB in the X-band, an electrical conductivity of 100 S / cm, and can still maintain excellent electromagnetic shielding performance after 100 times of bending and folding, with an electromagnetic shielding value of 85 dB. The composite nanofiber membrane can quickly evaporate sweat within 12 s, with a water vapor transmission rate of 690 g·m -2 ·d -1 In addition, the composite nanofiber membrane can quickly increase the equilibrium temperature from 24℃ to 60℃ under the irradiation of a xenon lamp at 50 mW / cm 2 After 5 cycles, the photothermal curves are almost identical, indicating that the composite nanofiber membrane has excellent photothermal stability. The composite nanofiber membrane has an antibacterial rate of 96% and 99% against Escherichia coli and Staphylococcus aureus, respectively. At the same time, the composite nanofiber membrane has good tensile strength and elongation at break, which are 9.2 MPa and 220%, respectively.

[0116] Comparative Example 1

[0117] Step one: First, 1 g of polyacrylonitrile was added to 9 g of N,N-dimethylformamide and stirred overnight until the solution was completely dissolved, then the obtained spinning solution was loaded into a syringe for spinning to obtain a polyacrylonitrile nanofiber membrane, wherein the voltage of the electrospinning machine was 16 kV, and the spinning distance was 18 cm.

[0118] Step two: the polyacrylonitrile nanofiber membrane was immersed in 100 mL of a Tris-HCl solution containing dopamine (concentration of 7.9 mg·mL -1 , pH=8.5) and oscillated on a shaking table at 40℃ for 24 h, the shaking table oscillation rate was 90 rpm, then deionized water and ethanol were repeatedly alternately washed, and then placed in an oven (338 K) for drying to obtain a dopamine-coated fiber membrane, with a fiber diameter of 150-290 nm.

[0119] Step three: first, the dopamine coated fiber membrane is immersed in copper acetate (0.15 mol / L) aqueous solution for 2h, then the obtained dopamine coated fiber membrane after immersion is transferred into a mixed solution containing copper acetate (0.15 mol / L) (the mixed solution is a mixed solution of water and ethylene glycol with a volume ratio of 20mL:60mL), after the membrane is completely soaked, sodium thiosulfate is added (the molar ratio of copper acetate to sodium thiosulfate is 1:1), after stirring uniformly, the reaction is carried out at 70℃ in an oil bath for 4h, after the reaction stops, it is taken out, washed repeatedly with water and ethanol alternately, and dried to obtain a modified nanofiber membrane, i.e. a copper sulfide nanoparticle modified nanofiber membrane, wherein the diameter of the copper sulfide nanoparticle is about 20nm, which can be well anchored on the fiber and does not affect the pore size between the fibers, and is not easy to fall off.

[0120] Step four: polyurethane is dissolved in DMF to obtain a 25wt% polyurethane spinning solution, and the modified nanofiber membrane is used as a receiver for spinning to obtain a composite nanofiber membrane, the spinning voltage is 14kV, and the spinning time is 1h.

[0121] The thickness of the hydrophilic layer (CuS@PDA / PAN) of the composite nanofiber membrane prepared in Comparative Example 1 is about 27μm, and the thickness of the hydrophobic layer (TPU) is about 22μm; the pore size of the hydrophilic layer is 0.25~0.65μm, and the pore size of the hydrophobic layer is 1.05~4.05μm.

[0122] It is detected that the electromagnetic shielding value of the composite nanofiber membrane prepared in Comparative Example 1 in the X-band is 28dB, the conductivity is 11.5S / cm, and after 100 times of bending and folding, the fiber membrane shows obvious delamination phenomenon, and the electromagnetic shielding value decreases to 14dB. The composite nanofiber membrane can quickly reduce the temperature of the surface of the xenon lamp from 50mW / cm 2 to 40℃, and the antibacterial rates of Escherichia coli and Staphylococcus aureus are 73% and 78% respectively. The tensile strength and elongation at break of the composite nanofiber membrane are 3.8MPa and 39% respectively.

[0123] Obviously, the above examples are only examples for clearly illustrating, but not limiting the examples. For ordinary skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Here, it is not necessary and impossible to exhaust all examples. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

Claims

1. A composite nanofiber membrane, characterized by, Composed of a hydrophilic layer, a bonding layer and a hydrophobic layer arranged in sequence; The material of the hydrophilic layer is nano-particle modified polyacrylonitrile, the material of the bonding layer is conductive filler, and the material of the hydrophobic layer is polyurethane; The nano-particles are one or more of copper sulfide nano-particles, silver nano-particles and gold nano-particles; The thickness of the hydrophilic layer is 20-32 microns, and the pore size of the hydrophilic layer is 0.15-0.85 microns; The thickness of the bonding layer is 25-41 microns; The thickness of the hydrophobic layer is 22-43 microns, and the pore size of the hydrophobic layer is 1-4.5 microns; The composite nanofiber membrane is prepared by the following method: The method comprises the following steps: Step one: polyacrylonitrile is dissolved in a solvent to obtain a polyacrylonitrile spinning solution, and spinning is performed to obtain a polyacrylonitrile nanofiber membrane; Step two: the polyacrylonitrile nanofiber membrane obtained in step one is soaked in a tris-hydroxymethyl aminomethane hydrochloride solution containing dopamine, oscillation reaction is performed, the product is taken out, and deionized water and ethanol are repeatedly and alternately washed, and then dried to obtain a dopamine-coated fiber membrane; Step three: the dopamine-coated fiber membrane obtained in step two is first soaked in an aqueous solution containing a copper salt for 2-6 hours, and then the soaked dopamine-coated fiber membrane is transferred into a mixed solution containing a copper salt for soaking, sodium thiosulfate is added after complete soaking, and then stirring and reaction are performed, the product is taken out after the reaction stops, and water and ethanol are repeatedly and alternately washed, and then dried to obtain a modified nanofiber membrane; Alternatively, the dopamine-coated fiber membrane obtained in step two is first soaked in an aqueous solution containing a silver salt for 2-6 hours, and then the soaked dopamine-coated fiber membrane is transferred into a silver ammine solution for soaking, glucose is added after complete soaking, and then stirring and reaction are performed, the product is taken out after the reaction stops, and water and ethanol are repeatedly and alternately washed, and then dried to obtain a modified nanofiber membrane; Step four: a dispersion liquid containing conductive filler is sprayed onto the modified nanofiber membrane prepared in step three, and then dried to obtain a conductive filler modified nanofiber membrane; Step five: polyurethane is dissolved in a solvent to obtain a polyurethane spinning solution, and spinning is performed with the conductive filler modified nanofiber membrane prepared in step four as a receiver to obtain a composite nanofiber membrane. The conductive filler is a transition metal carbonitride, acidified carbon nanotube or graphene.

2. The composite nanofiber membrane according to claim 1, wherein, The method comprises the following steps: Step one: polyacrylonitrile is dissolved in a solvent to obtain a polyacrylonitrile spinning solution, and spinning is performed to obtain a polyacrylonitrile nanofiber membrane; 3. The method of claim 1, wherein the composite nanofiber membrane is prepared by electrospinning. Step two: the polyacrylonitrile nanofiber membrane obtained in step one is soaked in a tris-hydroxymethyl aminomethane hydrochloride solution containing dopamine, oscillation reaction is performed, the product is taken out, and deionized water and ethanol are repeatedly and alternately washed, and then dried to obtain a dopamine-coated fiber membrane; Step three: the dopamine-coated fiber membrane obtained in step two is first soaked in an aqueous solution containing a copper salt for 2-6 hours, and then the soaked dopamine-coated fiber membrane is transferred into a mixed solution containing a copper salt for soaking, sodium thiosulfate is added after complete soaking, and then stirring and reaction are performed, the product is taken out after the reaction stops, and water and ethanol are repeatedly and alternately washed, and then dried to obtain a modified nanofiber membrane; ​ ​ Alternatively, the dopamine-coated fiber membrane obtained in step two is first immersed in an aqueous solution containing silver salt for 2-6 hours, and then the obtained dopamine-coated fiber membrane after immersion is transferred into a silver ammine solution for immersion. After complete immersion, glucose is added, stirred uniformly, and then reacted. After the reaction stops, it is taken out, washed repeatedly with water and ethanol alternately, and dried to obtain a modified nanofiber membrane. Step four: a dispersion liquid containing conductive fillers is sprayed onto the modified nanofiber membrane prepared in step three, and after drying, a conductive filler modified nanofiber membrane is obtained. Step five: polyurethane is dissolved in a solvent to obtain a polyurethane spinning solution, and spinning is performed with the conductive filler modified nanofiber membrane prepared in step four as a receiver to obtain a composite nanofiber membrane.

4. The method of claim 3, wherein the electrospinning is performed at a voltage of 10 to 30 kV. In step one, the mass fraction of polyacrylonitrile in the polyacrylonitrile spinning solution is 10%-20%, the solvent is N,N-dimethylformamide, N-methyl pyrrolidone or tetrahydrofuran, the spinning voltage is 16-17 kV, and the spinning distance is 1-18 cm.

5. The method of claim 4, wherein the electrospinning is performed at a voltage of 10 to 30 kV. In step two, the concentration of the solution of tris-hydroxymethylaminomethane hydrochloride containing dopamine is 7.9 mg·mL -1 , the pH is 8.5~9, the oscillation rate is 60~90 rpm, the reaction temperature is 40~60℃, and the reaction time is 12~24 h.

6. The method of claim 3, wherein the composite nanofiber membrane is prepared by electrospinning. In step three, the concentration of the aqueous solution containing copper salt is 0.025-0.175 mol / L; in the mixed solution containing copper salt, the concentration of copper salt is 0.025-0.175 mol / L, the mixed solution is a mixture of water and ethylene glycol in a volume ratio of 1:1-1:3, the molar ratio of copper salt to sodium thiosulfate is 1:1-1:3, the reaction time is 4-7 h, and the reaction temperature is 70-180℃; the copper salt is independently copper acetate, copper sulfate, copper chloride or copper nitrate; The concentration of the aqueous solution containing silver salt is 0.1-0.3 mol / L, and the silver salt is silver nitrate; The concentration of the silver ammine solution is calculated based on the concentration of silver nitrate, and the concentration of silver nitrate is 0.1-0.3 mol / L. The molar ratio of silver ions to glucose in the silver ammine solution is 1:2, the reaction time is 0.5-4 h, and the reaction temperature is 70-90℃; After the dopamine-coated fiber membrane obtained in step two is immersed in the aqueous solution containing copper salt for 2-6 h, the dopamine-coated fiber membrane after immersion is first dried, and then the dried dopamine-coated fiber membrane after immersion is transferred into the mixed solution containing copper salt for immersion. After the dopamine-coated fiber membrane obtained in step two is immersed in the aqueous solution containing silver salt for 2-6 h, the dopamine-coated fiber membrane after immersion is first dried, and then the dried dopamine-coated fiber membrane after immersion is transferred into the silver ammine solution for immersion.

7. The method of claim 3, wherein the electrospinning is performed at a voltage of 10 to 30 kV. In step four, the conductive filler is a transition metal carbon nitride, acidified carbon nanotube or graphene, and in the dispersion liquid containing the conductive filler, the concentration of the conductive filler is 8-20 mg / L, and the spraying rate is 10-20 ml / h.

8. The method of claim 3, wherein the composite nanofiber membrane is prepared by electrospinning a solution of the polymer and the inorganic material. In step five, the mass fraction of polyurethane in the polyurethane spinning solution is 20%-25%, the solvent is N,N-dimethylformamide, N-methyl pyrrolidone or tetrahydrofuran, the spinning voltage is 14-15 kV, and the spinning distance is 15-18 cm.

9. The composite nanofiber membrane according to any one of claims 1-2 or prepared by the preparation method according to any one of claims 4-8 is applied in wearable electromagnetic shielding materials.

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