Bimodal composite nanofiber membranes, methods of making and applications thereof

Abstract

The present application relates to a kind of dual-mode composite nanofiber membrane and its preparation method and application, belong to fiber membrane technical field.The problem that nanofiber membrane cannot simultaneously realize dual-mode heat management, sweat management and electromagnetic protection in prior art is solved.The dual-mode composite nanofiber membrane of the present application is composed of cooling hydrophilic layer, intermediate adhesive conductive layer and heating hydrophobic layer arranged in sequence;The material of the cooling hydrophilic layer is polyacrylonitrile fiber membrane blended with silicon dioxide, the material of the intermediate adhesive conductive layer is carbon nanotube film modified by silane coupling agent, and the material of the heating hydrophobic layer is polyurethane fiber membrane blended with reduced graphene oxide.The composite nanofiber membrane can simultaneously realize dual-mode heat management, sweat management and electromagnetic protection, meet the diversified demand under different application scenarios.

Description

Technical Field

[0001] This invention belongs to the field of fiber membrane technology, specifically relating to a dual-mode composite nanofiber membrane, its preparation method and application, and particularly to the application of the dual-mode composite nanofiber membrane in wearable electromagnetic shielding materials. Background Technology

[0002] With the rapid development of wireless communication base stations and wearable electronic devices, the density of electromagnetic radiation in urban environments is increasing, and prolonged exposure to electromagnetic fields poses a serious threat to human health. However, existing wearable electromagnetic shielding materials generally suffer from poor breathability and insufficient moisture and heat comfort, easily leading to stuffy and uncomfortable skin.

[0003] At the same time, the accelerated pace of global industrialization has exacerbated the greenhouse effect and led to more frequent extreme weather events, exposing outdoor enthusiasts to health risks such as heatstroke or hypothermia. While existing temperature control devices (such as electric heaters and air conditioners) can alleviate discomfort to some extent by regulating the indoor environment, these devices suffer from high energy consumption and limitations in outdoor use.

[0004] Therefore, there is an urgent need to develop smart wearable materials that can simultaneously achieve efficient electromagnetic protection and dynamic humidity-heat management to address the multiple challenges of electromagnetic pollution, poor wearing comfort, and climate change.

[0005] Electrospinning is a highly efficient method for preparing nanofiber membranes. By controlling spinning parameters (such as voltage and polymer concentration), fiber membranes with differences in pore size and diameter can be obtained. Electrospun nanofiber membranes possess excellent flexibility and self-supporting properties, making them ideal substrates for electromagnetic wave attenuation and demonstrating great application potential in the field of electromagnetic shielding. However, most electromagnetic shielding nanofiber membranes prepared based on electrospinning cannot simultaneously achieve both mechanical strength and flexibility.

[0006] Therefore, there is an urgent need to develop a composite nanofiber membrane that can simultaneously achieve dual-mode thermal management, sweat management, and electromagnetic protection through electrospinning technology to meet the diverse needs of different application scenarios. Summary of the Invention

[0007] To address the problem that existing nanofiber membranes cannot simultaneously achieve dual-mode thermal management, sweat management, and electromagnetic protection, this invention provides a dual-mode composite nanofiber membrane, its preparation method, and its applications.

[0008] The present invention addresses the above-mentioned technical problems by adopting the following technical solution.

[0009] In a first aspect, the present invention provides a dual-mode composite nanofiber membrane, which is composed of a cooling hydrophilic layer, an intermediate adhesive conductive layer and a heating hydrophobic layer that are fixedly arranged in sequence.

[0010] The cooling hydrophilic layer is made of a silica-blended polyacrylonitrile fiber membrane, the intermediate adhesive conductive layer is made of a silane coupling agent-modified carbon nanotube film, and the heating hydrophobic layer is made of a reduced graphene oxide-blended polyurethane fiber membrane.

[0011] Preferably, the cooling hydrophilic layer has a reflectivity of 0.9 to 0.99 at 0.3 to 2.5 μm, an emissivity of 0.9 to 0.95 at 3 to 16 μm, a water contact angle of 40 to 50°, and a pore size of 0.3 to 0.5 μm.

[0012] Preferably, the intermediate adhesive conductive layer has an absorption rate of 0.8-0.9 at 0.3-2.5 μm, an emissivity of 0.8-0.85 at 3-16 μm, a water contact angle of 50-55°, and a pore size of 0.5-0.7 μm.

[0013] Preferably, the heated hydrophobic layer has an absorptivity of 0.7-0.8 in the 0.3-2.5 μm range, an emissivity of 0.75-0.8 in the 3-16 μm range, a water contact angle of 120-130°, and a pore size of 1.0-1.5 μm.

[0014] Preferably, the silane coupling agent is 3-aminopropyltriethoxysilane.

[0015] Preferably, the thickness of the intermediate adhesive conductive layer is 10~50μm.

[0016] Preferably, the thickness of the cooling hydrophilic layer is 12~50μm.

[0017] Preferably, the thickness of the heated hydrophobic layer is 5~10μm.

[0018] The method for preparing the composite nanofiber membrane of the present invention is characterized by comprising the following steps:

[0019] Step 1: First, the carbon nanotube film is subjected to plasma surface treatment. Then, the treated carbon nanotube film is immersed in a silane coupling agent treatment solution for reaction. After the reaction stops, it is taken out, rinsed repeatedly with water and ethanol, and dried to obtain a silane coupling agent modified carbon nanotube film.

[0020] Step 2: First, add polyacrylonitrile to the solvent and stir evenly. Then, add silica nanoparticles and stir for 10-15 hours to obtain the spinning solution. Finally, use one side of the silane coupling agent modified carbon nanotube film prepared in Step 1 as the receiver for spinning to form a silica-blended polyacrylonitrile fiber film.

[0021] Step 3: Add polyurethane to the solvent and stir evenly, then add reduced graphene oxide and stir for 20-24 hours to obtain the spinning solution. Finally, use the other side of the carbon nanotube film modified by the silane coupling agent prepared in Step 1 as the receiver for spinning to form a polyurethane fiber film mixed with reduced graphene oxide, thus obtaining a composite nanofiber film.

[0022] Preferably, in step one, the carbon nanotube film is subjected to plasma surface treatment using a plasma sputtering instrument.

[0023] Preferably, in step one, the silane coupling agent treatment solution is a mixed solution of ethanol, water and 3-aminopropyltriethoxysilane in a volume ratio of 2:18:5.

[0024] Preferably, in step one, the reaction time is 13 hours.

[0025] Preferably, in step two, the solvent is N,N-dimethylformamide (DMF).

[0026] Preferably, in step two, the mass fraction of polyacrylonitrile in the spinning solution is 10%, and the mass fraction of silica nanoparticles is 10% to 70% of polyacrylonitrile.

[0027] Preferably, in step two, the diameter of the silica nanoparticles is 50~500nm.

[0028] Preferably, in step two, the method for preparing the silica nanoparticles is as follows: first, ethanol, deionized water and ammonia are stirred at 50°C for 5 minutes, and then tetraethyl silicate is added dropwise to the resulting mixed solution, stirred for 2 hours, centrifuged and dried to obtain silica nanoparticles; the volume ratio of ethanol, deionized water, ammonia and tetraethyl silicate is 28:4:1:1.

[0029] More preferably, the concentration of the ammonia water is 25 wt%.

[0030] Preferably, in step two, the silica nanoparticles are mesoporous silica nanoparticles.

[0031] More preferably, the preparation method of the mesoporous silica nanoparticles is as follows: first, hexadecyltrimethylammonium bromide, deionized water and ammonia are magnetically stirred at 35°C until the solution is clear, then tetraethyl silicate is added to the obtained mixed solution, and stirring is continued for 8 hours. Subsequently, the mixture is transferred to a hydrothermal reactor at 100°C and reacted for 24 hours. After centrifugation and drying, powder is obtained, and finally calcined at 550°C for 5 hours to obtain mesoporous silica nanoparticles; the ratio of hexadecyltrimethylammonium bromide, deionized water, ammonia and tetraethyl silicate is 0.16~0.32g:43.5mL:1.5mL:0.8mL.

[0032] Particularly preferred is that the concentration of the ammonia water is 25 wt%.

[0033] Preferably, in step two, the spinning voltage is 15~17kV and the spinning time is 6~12h.

[0034] Preferably, in step three, the method for preparing the reduced graphene oxide is as follows:

[0035] The graphene oxide and hydrobromic acid were mixed in a ratio of 1~3g:10~30mL. The graphene oxide was placed in hydrobromic acid and reacted for 12~24 hours. After centrifugation, the reduced graphene oxide was obtained.

[0036] Alternatively, the graphene oxide, water, and hydrazine hydrate are mixed in a ratio of 0.58~1.74g:100~300mL:2~6mL. The graphene oxide is ultrasonically stirred in a mixed solution of water and hydrazine hydrate for 30 minutes, then reacted at 200℃ for 24 hours. After centrifugation and drying, reduced graphene oxide is obtained.

[0037] Preferably, in step three, the solvent is N,N-dimethylformamide.

[0038] Preferably, in step three, the mass fraction of polyurethane in the spinning solution is 25%, and the mass fraction of reduced graphene oxide is 5% to 20% of the polyurethane.

[0039] Preferably, in step three, the spinning voltage is 14~15kV and the spinning time is 0.5~2h.

[0040] Thirdly, the present invention also provides the application of the above-mentioned composite nanofiber membrane in wearable electromagnetic shielding materials.

[0041] The principle of this invention is as follows: In the composite nanofiber membrane of this invention, the cooling hydrophilic layer is a polyacrylonitrile (PAN) fiber membrane blended with silica (SiO2). High reflectivity (0.3~2.5μm) and a reflectance of 0.9~0.99 are achieved through the synergistic effect of Mie scattering of SiO2 and diffuse reflection of PAN's porous structure. Simultaneously, high emissivity (3~16μm) and an emissivity of 0.9~0.95 are achieved through the synergistic effect of SiO2 and PAN. Passive radiative cooling can be achieved in hot environments, providing a cooling effect. The intermediate adhesive conductive layer (ACNT) uses a silane coupler. The carbon nanotube (CNT) film modified with a binder has an absorptivity of 0.8-0.9 (0.3-2.5 μm) and an emissivity of 0.8-0.85 (3-16 μm). The heating hydrophobic layer is a polyurethane (TPU) fiber membrane blended with reduced graphene oxide (rGO), with an absorptivity of 0.7-0.8 (0.3-2.5 μm) and an emissivity of 0.75-0.8 (3-16 μm). By utilizing the synergistic absorption of CNTs and rGO, solar heating is achieved in cold environments, providing a warming effect. Therefore, the composite nanofiber membrane of this invention has optical differences, and dual-mode thermal management can be achieved by simply flipping it over.

[0042] The composite nanofiber membrane of the present invention first performs plasma surface treatment on the carbon nanotube film, which on the one hand modifies the carbon nanotube film to be hydrophilic, and on the other hand forms amino groups on the surface of the carbon nanotube film, which then form hydrogen bonds with the cooled hydrophilic layer and the heated hydrophobic layer.

[0043] In the composite nanofiber membrane of the present invention, the water contact angle of the cooling hydrophilic layer is 40~50° and the pore size is 0.3~0.5μm; the water contact angle of the intermediate adhesive conductive layer is 50~55° and the pore size is 0.5~0.7μm; the water contact angle of the heating hydrophobic layer is 120~130° and the pore size is 1.0~1.5μm. By utilizing the dual gradient structure of wettability and pore size between each fiber membrane layer, the directional transport of personal sweat is realized, avoiding sweat accumulation under hot conditions, and further enhancing the cooling capacity through sweat evaporation.

[0044] The composite nanofiber membrane of the present invention utilizes the conductivity of carbon nanotube thin films and reduced graphene oxide to achieve high electromagnetic shielding efficiency in the X-band, Ku-band, K-band and Ka-band, protecting the human body from electromagnetic interference.

[0045] Meanwhile, due to the stability of carbon nanotubes, the composite nanofiber membrane of the present invention can exhibit stable electromagnetic shielding performance under different humidity and temperature conditions, meeting the diverse needs of wearable materials in different application scenarios.

[0046] Furthermore, hydrogen bonding interactions exist between the amino groups of carbon nanotube films treated with silane coupling agents and the cyano groups of polyacrylonitrile, as well as between the amino groups of carbon nanotube films treated with silane coupling agents and the urethane groups of polyurethane. This not only solves the problem of layering in multilayer fiber membranes, but also improves the mechanical strength and elongation at break of the fiber membranes.

[0047] Electrospun fiber membranes are easily modified, so this invention can prepare nanofiber membranes with dual gradient structures of pore size and wettability as well as optical differences through electrospinning technology, thereby endowing the fiber membranes with sweat management and dual-mode thermal management functions.

[0048] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0049] The composite nanofiber membrane of the present invention has excellent electromagnetic shielding performance and can maintain excellent electromagnetic shielding performance after 500 bending and folding cycles. It has excellent stability and can be used in smart wearable clothing to protect the human body from electromagnetic interference.

[0050] The composite nanofiber membrane of the present invention has optical differences, enabling dynamic dual-mode personal thermal management. It can achieve excellent radiative cooling in hot conditions and excellent solar heating in cold conditions with just a simple flip, thereby improving the thermal comfort of outdoor athletes.

[0051] The composite nanofiber membrane of the present invention has wettability gradient and pore size gradient, which can achieve good sweat management under hot conditions, keep the wearer's skin dry during long-term wear, and can also work with radiative cooling under hot conditions to keep the skin microenvironment below the ambient temperature, thus improving the heat and humidity comfort of outdoor activities.

[0052] The composite nanofiber membrane of the present invention, due to the water adsorption-desorption capacity of the mesoporous silica nanoparticles, can provide additional cooling capacity through water evaporation in hot environments, thereby improving the thermal comfort of outdoor participants.

[0053] The composite nanofiber membrane of the present invention, due to the hydrogen bond interaction between the amino groups of the carbon nanotube film treated with silane coupling agent and the cyano groups of polyacrylonitrile, and between the amino groups of the carbon nanotube film treated with silane coupling agent and the urethane groups of polyurethane, not only solves the problem of layering of multilayer fiber membranes, but also improves the mechanical strength and elongation at break of the fiber membrane.

[0054] The method for preparing the composite nanofiber membrane of the present invention can, by selecting fillers with optical differences, pore size differences and wettability differences to blend with polymers, thereby maintaining the electromagnetic shielding performance of the material while endowing it with excellent dual-mode thermal management performance, directional sweat management ability and water absorption-desorption ability.

[0055] The method for preparing the composite nanofiber membrane of the present invention is simple and has broad application prospects in wearable devices. Attached Figure Description

[0056] Figure 1 SEM images of the silica-blended polyacrylonitrile fiber membrane (SiO2 / PAN), the silane coupling agent-modified carbon nanotube film (APTES / CNT), and the reduced graphene oxide-blended polyurethane fiber membrane (rGO / TPU) prepared in Example 1 of this invention, where A is SiO2 / PAN, B is APTES / CNT, and C is rGO / TPU.

[0057] Figure 2 The water contact angle diagrams for the silica-blended polyacrylonitrile fiber membrane (SiO2 / PAN), the silane coupling agent-modified carbon nanotube film (APTES / CNT), and the reduced graphene oxide-blended polyurethane fiber membrane (rGO / TPU) prepared in Example 1 of this invention are shown, where A is SiO2 / PAN, B is APTES / CNT, and C is rGO / TPU.

[0058] Figure 3 The pore size distribution diagrams are for the silica-blended polyacrylonitrile fiber membrane (SiO2 / PAN), the silane coupling agent modified carbon nanotube film (APTES / CNT), and the reduced graphene oxide-blended polyurethane fiber membrane (rGO / TPU) prepared in Example 1 of this invention, where A is SiO2 / PAN, B is APTES / CNT, and C is rGO / TPU.

[0059] Figure 4 The image shows the electromagnetic shielding performance of the composite nanofiber membrane prepared in Example 1 of this invention.

[0060] Figure 5 The electromagnetic shielding performance of the composite nanofiber membrane prepared in Example 1 of this invention is shown in different humidity levels.

[0061] Figure 6 The image shows the electromagnetic shielding performance of the composite nanofiber membrane prepared in Example 1 of this invention at different temperatures.

[0062] Figure 7 This is a comparison of the moisture absorption and perspiration wicking properties of the composite nanofiber membrane prepared in Example 1 of the present invention and commercial cotton fabric, wherein A is the composite nanofiber membrane and B is commercial cotton fabric.

[0063] Figure 8 The composite nanofiber membrane prepared in Example 1 of this invention was compared with commercial cotton fabric on a sunny day (average solar power of 879 W / m). 2 The real-time temperature of ( ).

[0064] Figure 9The composite nanofiber membrane prepared in Example 1 of this invention was compared with commercial cotton fabric on a cloudy day (average solar power of 162 W / m). 2 The real-time temperature of ( ). Detailed Implementation

[0065] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described in detail below with reference to embodiments.

[0066] In the following embodiments, various processes and methods not described in detail are conventional methods known in the art.

[0067] Unless otherwise specified, all materials, reagents, apparatus, instruments, and equipment used in the following examples are commercially available.

[0068] In this invention, the scanning electron microscope used is a HITACHI-SU8020. The electromagnetic shielding performance testing instrument is an Agilent PNA-N5244A vector network analyzer. The mechanical property testing instrument is a Shimadzu AG-1KN electronic universal testing machine. The constant temperature and humidity chamber is an HWS-80. The water contact angle testing instrument is a Dataphysics-OCA20 from Germany. The solar power meter is a TES-1333R from Taiwan, China. The K-type thermocouple is a TA612C from China.

[0069] Example 1

[0070] Step 1: First, add 14 mL of ethanol, 2 mL of deionized water and 0.5 mL of ammonia water to a round-bottom flask and stir at 50 °C for 5 min. Then, slowly add 0.5 mL of tetraethyl silicate to the above solution and stir for 2 hours. After the reaction is complete, centrifuge and dry to obtain silica nanoparticles with a diameter of 200~500 nm.

[0071] Step 2: First, the carbon nanotube film is modified into a hydrophilic carbon nanotube film by plasma sputtering. Then, the treated carbon nanotube film is placed in a silane coupling agent treatment solution and reacted for 13 hours. After the reaction stops, it is taken out, rinsed repeatedly with water and ethanol, and dried to obtain a silane coupling agent modified carbon nanotube film. The silane coupling agent treatment solution is a mixed solution of ethanol, water and 3-aminopropyltriethoxysilane in a volume ratio of 2:18:5.

[0072] Step 3: First, add polyacrylonitrile to the DMF solution and stir. After the solution is stirred evenly, add silica nanoparticles and stir for 15 hours to obtain the spinning solution. Finally, use one side of the silane coupling agent modified carbon nanotube film prepared in Step 2 as the receiver for spinning. In the spinning solution, the mass fraction of polyacrylonitrile is 10%, the mass fraction of silica nanoparticles is 50% of polyacrylonitrile, the spinning voltage is 17kV, and the spinning time is 10 hours to form a silica-blended polyacrylonitrile fiber film.

[0073] Step 4: Weigh 1g of graphene oxide and react it in 10mL of hydrobromic acid for 24 hours. After the reaction, centrifuge and dry to obtain reduced graphene oxide.

[0074] Step 5: First, add polyurethane to DMF and stir. After the solution is stirred evenly, add reduced graphene oxide and stir for 24 hours to obtain a spinning solution. Finally, use the other side of the silane coupling agent modified carbon nanotube film prepared in Step 2 as a receiver for spinning to form a polyurethane fiber membrane mixed with reduced graphene oxide, thus obtaining a composite nanofiber membrane. In the spinning solution, the mass fraction of polyurethane is 25%, the mass fraction of reduced graphene oxide is 10% of polyurethane, the spinning voltage is 14kV, and the spinning time is 0.5h.

[0075] Scanning electron microscopy (SEM) was used to observe the silica-blended polyacrylonitrile fiber membrane, the silane coupling agent-modified carbon nanotube film, and the reduced graphene oxide-blended polyurethane fiber membrane prepared in Example 1. The water contact angle of the composite fiber membranes was measured using a water contact angle testing instrument. The reflectance and absorptivity of the composite fiber membranes were measured using a UV-Vis-NIR spectrophotometer. The emissivity of the composite fiber membranes was measured using a Fourier transform infrared spectrometer. The results are as follows: Figures 1-3 As shown, the composite nanofiber membrane prepared in Example 1 has a cooling hydrophilic layer (SiO2 / PAN) with a thickness of approximately 20 μm, a pore size of 0.4~0.5 μm, a reflectivity of 99%, an emissivity of 0.95, and a water contact angle of 48°; an intermediate conductive adhesive layer (APTES / CNT) with a thickness of approximately 10 μm, a pore size of 0.6~0.7 μm, an absorptivity of 0.82, an emissivity of 0.8, and a water contact angle of 51°; and a heating hydrophobic layer (rGO / TPU) with a thickness of approximately 8 μm, a pore size of 1~1.5 μm, an absorptivity of 0.7, an emissivity of 0.75, and a water contact angle of 121.8°.

[0076] The composite fiber membrane was cut into rectangular samples of 22.86 mm × 10.16 mm. Its original electromagnetic shielding effectiveness and electromagnetic shielding performance under different humidity / temperature and simulated acid rain conditions were tested using an electromagnetic shielding performance testing instrument. Simulated sweat was dripped onto the arm and absorbed by the composite fiber membrane; the time from absorption to arm dryness was recorded. Water vapor transmission rate was calculated by weighing the fiber membrane after 24 hours in a constant temperature and humidity chamber at 25°C and 50% relative humidity. On sunny and cloudy days, the composite fiber membrane was placed in a foam box wrapped in aluminum foil, with the opening sealed with polyethylene (PE) film. Solar power was measured using a solar power meter, and the sample temperature was monitored in real time using a K-type thermocouple. The tensile strength and elongation at break of the composite fiber membrane were tested using a mechanical property testing instrument.

[0077] Upon testing, the electromagnetic shielding value of the composite nanofiber membrane prepared in Example 1 in the X-band was as follows: Figure 4 As shown, the electromagnetic shielding value is 43 dB, and it maintains excellent electromagnetic shielding performance after 500 bending and folding cycles, with an electromagnetic shielding value of 41 dB. Furthermore, the composite nanofiber membrane prepared in Example 1 has an electromagnetic shielding value of 41 dB under different humidity / temperature conditions. Figure 5 and Figure 6 As shown, the electromagnetic shielding value under simulated acid rain conditions is also 41 dB, indicating that the electromagnetic shielding performance of the composite nanofiber membrane is environmentally stable. Furthermore, when simulated sweat droplets are placed on the arm, the composite nanofiber membrane can adsorb the simulated sweat onto the fiber surface within 3 seconds, keeping the arm dry. Figure 7 As shown. Simultaneously, the composite nanofiber membrane exhibits excellent air permeability, with a water vapor permeability of 847 g·m³. -2 ·d -1 In sunny weather testing (average solar power 879 W / m²),... 2 The average temperature of commercial cotton fabric is 69℃, while the average temperature of composite nanofiber membrane is 59℃. Figure 8 As shown, the temperature is 10°C lower than that of commercial cotton fabric, mainly attributed to the synergistic effect of radiative cooling and sweat evaporation of the composite nanofiber membrane. This indicates that the composite fiber membrane prepared by this invention has better cooling performance than commercial cotton fabric, achieving good cooling under hot conditions and creating a comfortable environment. In tests conducted under cloudy conditions (average solar power 162 W / m²),... 2 The average temperature of commercial cotton fabric is 31.3℃, and the average temperature of composite nanofiber membrane is 36℃. Figure 9 As shown, the temperature is 4.7°C higher than that of commercial cotton fabric, attributed to the synergistic effect of reduced graphene oxide and carbon nanotubes. This indicates that the fiber membrane prepared by this invention has better solar heating performance than commercial cotton fabric, achieving good solar energy performance under cold conditions and creating a comfortable environment for people. Simultaneously, this composite nanofiber membrane exhibits good tensile strength and elongation at break, at 11 MPa and 500%, respectively.

[0078] Example 2

[0079] Step 1: First, add 0.16g of hexadecyltrimethylammonium bromide, 43.5mL of deionized water, and 1.5mL of ammonia (25wt%) to a round-bottom flask and stir at 35℃ until the solution is clear. Then, slowly add 0.8mL of tetraethyl silicate to the above solution and stir for 8 hours. Next, transfer the solution to a hydrothermal reactor at 100℃ and react for 24 hours. After the reaction, centrifuge and dry to obtain powder. Finally, transfer the powder to a tube furnace at 550℃ and calcine for 5 hours to obtain mesoporous silica nanoparticles.

[0080] Step 2: First, the carbon nanotube film is modified into a hydrophilic carbon nanotube film by plasma sputtering. Then, the treated carbon nanotube film is placed in a silane coupling agent treatment solution and reacted for 13 hours. After the reaction stops, it is taken out, rinsed repeatedly with water and ethanol, and dried to obtain a silane coupling agent modified carbon nanotube film. The silane coupling agent treatment solution is a mixed solution of ethanol, water and 3-aminopropyltriethoxysilane in a volume ratio of 2:18:5.

[0081] Step 3: First, add polyacrylonitrile to the DMF solution and stir. After the solution is stirred evenly, add mesoporous silica nanoparticles and stir for 15 hours to obtain the spinning solution. Finally, use one side of the silane coupling agent modified carbon nanotube film prepared in Step 2 as the receiver for spinning. In the spinning solution, the mass fraction of polyacrylonitrile is 10%, the mass fraction of mesoporous silica nanoparticles is 50% of polyacrylonitrile, the spinning voltage is 17kV, and the spinning time is 10 hours to form a silica-blended polyacrylonitrile fiber membrane.

[0082] Step 4: Weigh 1g of graphene oxide and react it in 10mL of hydrobromic acid for 24 hours. After the reaction, centrifuge and dry to obtain reduced graphene oxide.

[0083] Step 5: First, add polyurethane to DMF and stir. After the solution is stirred evenly, add reduced graphene oxide and stir for 24 hours to obtain a spinning solution. Finally, use the other side of the silane coupling agent modified carbon nanotube film prepared in Step 2 as a receiver for spinning to form a polyurethane fiber membrane mixed with reduced graphene oxide, thus obtaining a composite nanofiber membrane. In the spinning solution, the mass fraction of polyurethane is 25%, the mass fraction of reduced graphene oxide is 20% of polyurethane, the spinning voltage is 14kV, and the spinning time is 0.5h.

[0084] The composite nanofiber membrane prepared in Example 2 has a cooling hydrophilic layer (Mes-SiO2 / PAN) with a thickness of approximately 20 μm, a pore size of 0.4–0.5 μm, a reflectivity of 98%, an emissivity of 0.93, and a water contact angle of 49°; an intermediate conductive adhesive layer (APTES / CNT) with a thickness of approximately 10 μm, a pore size of 0.6–0.7 μm, an absorptivity of 0.82, an emissivity of 0.8, and a water contact angle of 51°; and a heating hydrophobic layer (rGO / TPU) with a thickness of approximately 8 μm, a pore size of 1–1.5 μm, an absorptivity of 0.73, an emissivity of 0.78, and a water contact angle of 118°.

[0085] The composite nanofiber membrane prepared in Example 2 exhibits an electromagnetic shielding value of 43 dB in the X-band and maintains excellent electromagnetic shielding performance (41.3 dB) after 500 bending and folding cycles. Furthermore, the electromagnetic shielding value of the composite nanofiber membrane prepared in Example 2 remains essentially unchanged at 41 dB under different humidity / temperature and simulated acid rain conditions, indicating that the electromagnetic shielding performance of the composite nanofiber membrane is environmentally stable. The composite nanofiber membrane reaches saturation with a water absorption of 0.84 g / g after 4 hours. When simulated sweat is dripped onto the arm, the composite nanofiber membrane can absorb the simulated sweat onto the fiber surface within 12 seconds, keeping the arm dry. Simultaneously, the composite nanofiber membrane exhibits excellent air permeability, with a water vapor transmission rate of 836 g·m³. -2 ·d -1 In sunny weather testing (average solar power 879 W / m²),... 2 The average temperature of the composite nanofiber membrane was 58.6℃, 10.4℃ lower than that of commercial cotton fabric. This is mainly attributed to the synergistic effect of radiative cooling, sweat evaporation, and water absorption-desorption of the composite nanofiber membrane. In tests conducted under cloudy conditions (average solar power 162W / m²), the composite nanofiber membrane achieved a similar effect. 2 The average temperature of the composite nanofiber membrane was 39°C, which is 7.7°C higher than that of commercial cotton fabric, attributed to the synergistic effect of reduced graphene oxide and carbon nanotubes. Simultaneously, the composite nanofiber membrane exhibited good tensile strength and elongation at break, at 8 MPa and 430%, respectively. The testing method was the same as in Example 1.

[0086] Example 3

[0087] Step 1: First, add 14 mL of ethanol, 2 mL of deionized water and 0.5 mL of ammonia water to a round-bottom flask and stir at 50 °C for 5 min. Then, slowly add 0.5 mL of tetraethyl silicate to the above solution and stir for 2 hours. After the reaction is completed, centrifuge and dry to obtain silica nanoparticles with a diameter of 50~100 nm.

[0088] Step 2: First, the carbon nanotube film is modified into a hydrophilic carbon nanotube film by plasma sputtering. Then, the treated carbon nanotube film is placed in a silane coupling agent treatment solution and reacted for 13 hours. After the reaction stops, it is taken out, rinsed repeatedly with water and ethanol, and dried to obtain a silane coupling agent modified carbon nanotube film. The silane coupling agent treatment solution is a mixed solution of ethanol, water and 3-aminopropyltriethoxysilane in a volume ratio of 2:18:5.

[0089] Step 3: First, add polyacrylonitrile to the DMF solution and stir. After the solution is stirred evenly, add silica nanoparticles and stir for 15 hours to obtain the spinning solution. Finally, use one side of the silane coupling agent modified carbon nanotube film prepared in Step 2 as the receiver for spinning. In the spinning solution, the mass fraction of polyacrylonitrile is 10%, the mass fraction of silica nanoparticles is 50% of polyacrylonitrile, the spinning voltage is 17kV, and the spinning time is 10 hours to form a silica-blended polyacrylonitrile fiber film.

[0090] Step 4: Weigh 1g of graphene oxide and react it in 10mL of hydrobromic acid for 24 hours. After the reaction, centrifuge and dry to obtain reduced graphene oxide.

[0091] Step 5: First, add polyurethane to DMF and stir. After the solution is stirred evenly, add reduced graphene oxide and stir for 24 hours to obtain a spinning solution. Finally, use the other side of the silane coupling agent modified carbon nanotube film prepared in Step 2 as a receiver for spinning to form a polyurethane fiber membrane mixed with reduced graphene oxide, thus obtaining a composite nanofiber membrane. In the spinning solution, the mass fraction of polyurethane is 25%, the mass fraction of reduced graphene oxide is 20% of polyurethane, the spinning voltage is 14kV, and the spinning time is 0.5h.

[0092] The composite nanofiber membrane prepared in Example 3 has a cooling hydrophilic layer (SiO2 / PAN) with a thickness of approximately 20 μm, a pore size of 0.4–0.5 μm, a reflectivity of 85%, an emissivity of 0.83, and a water contact angle of 49°; an intermediate conductive adhesive layer (APTES / CNT) with a thickness of approximately 10 μm, a pore size of 0.6–0.7 μm, an absorptivity of 0.82, an emissivity of 0.8, and a water contact angle of 51°; and a heating hydrophobic layer (rGO / TPU) with a thickness of approximately 8 μm, a pore size of 1–1.5 μm, an absorptivity of 0.73, an emissivity of 0.78, and a water contact angle of 118°.

[0093] The composite nanofiber membrane prepared in Example 3 exhibits an electromagnetic shielding value of 43 dB in the X-band and maintains excellent electromagnetic shielding performance (41.3 dB) after 500 bending and folding cycles. Furthermore, the electromagnetic shielding value of the composite nanofiber membrane prepared in Example 3 remains essentially unchanged at 41 dB under different humidity / temperature and simulated acid rain conditions, indicating that the electromagnetic shielding performance of the composite nanofiber membrane is environmentally stable. When simulated sweat droplets are placed on the arm, the composite nanofiber membrane can absorb the simulated sweat onto the fiber surface within 5 seconds, keeping the arm dry. Simultaneously, the composite nanofiber membrane exhibits excellent air permeability, with a water vapor transmission rate of 836 g·m³. -2 ·d -1 In sunny weather testing (average solar power 879 W / m²),... 2 The average temperature of the composite nanofiber membrane was 63.6℃, ​​5.4℃ lower than that of commercial cotton fabric. This is mainly attributed to the synergistic effect of radiative cooling and sweat evaporation of the composite nanofiber membrane. In tests conducted under cloudy conditions (average solar power 162W / m²),... 2 The average temperature of the composite nanofiber membrane was 39°C, which is 7.7°C higher than that of commercial cotton fabric, attributed to the synergistic effect of reduced graphene oxide and carbon nanotubes. Simultaneously, the composite nanofiber membrane exhibited good tensile strength and elongation at break, at 8 MPa and 430%, respectively. The testing method was the same as in Example 1.

[0094] Example 4

[0095] Step 1: First, add 14 mL of ethanol, 2 mL of deionized water and 0.5 mL of ammonia water to a round-bottom flask and stir at 50 °C for 5 min. Then, slowly add 0.5 mL of tetraethyl silicate to the above solution and stir for 2 hours. After the reaction is complete, centrifuge and dry to obtain silica nanoparticles with a diameter of 200~500 nm.

[0096] Step 2: First, the carbon nanotube film is modified into a hydrophilic carbon nanotube film by plasma sputtering. Then, the treated carbon nanotube film is placed in a silane coupling agent treatment solution and reacted for 13 hours. After the reaction stops, it is taken out, rinsed repeatedly with water and ethanol, and dried to obtain a silane coupling agent modified carbon nanotube film. The silane coupling agent treatment solution is a mixed solution of ethanol, water and 3-aminopropyltriethoxysilane in a volume ratio of 2:18:5.

[0097] Step 3: First, add polyacrylonitrile to the DMF solution and stir. After the solution is stirred evenly, add silica nanoparticles and stir for 15 hours to obtain the spinning solution. Finally, use one side of the silane coupling agent modified carbon nanotube film prepared in Step 2 as the receiver for spinning. In the spinning solution, the mass fraction of polyacrylonitrile is 10%, the mass fraction of silica nanoparticles is 70% of polyacrylonitrile, the spinning voltage is 17kV, and the spinning time is 10 hours to form a silica-blended polyacrylonitrile fiber film.

[0098] Step 4: Weigh 0.58g of graphene oxide into a mixed solution of water and hydrazine hydrate (volumes of water and hydrazine hydrate are 100mL and 2mL respectively), and sonicate for 30 minutes. Then, transfer the mixed solution into a reaction vessel at 200℃ and react for 24 hours. After the reaction, centrifuge and dry to obtain reduced graphene oxide.

[0099] Step 5: First, add polyurethane to DMF and stir. After the solution is stirred evenly, add reduced graphene oxide and stir for 24 hours to obtain a spinning solution. Finally, use the other side of the silane coupling agent modified carbon nanotube film prepared in Step 2 as a receiver for spinning to form a polyurethane fiber membrane mixed with reduced graphene oxide, thus obtaining a composite nanofiber membrane. In the spinning solution, the mass fraction of polyurethane is 25%, the mass fraction of reduced graphene oxide is 10% of polyurethane, the spinning voltage is 14kV, and the spinning time is 0.5h.

[0100] The composite nanofiber membrane prepared in Example 4 has a cooling hydrophilic layer (SiO2 / PAN) with a thickness of approximately 20 μm, a pore size of 0.4–0.5 μm, a reflectivity of 98.5%, an emissivity of 0.94, and a water contact angle of 48°; an intermediate conductive adhesive layer (APTES / CNT) with a thickness of approximately 10 μm, a pore size of 0.6–0.7 μm, an absorptivity of 0.82, an emissivity of 0.8, and a water contact angle of 51°; and a heating hydrophobic layer (rGO / TPU) with a thickness of approximately 8 μm, a pore size of 1–1.2 μm, an absorptivity of 0.7, an emissivity of 0.75, and a water contact angle of 120.2°.

[0101] The composite nanofiber membrane prepared in Example 4 exhibits an electromagnetic shielding value of 42 dB in the X-band and maintains excellent electromagnetic shielding performance of 40 dB after 500 bending and folding cycles. Furthermore, the electromagnetic shielding value of the composite nanofiber membrane prepared in Example 4 remains essentially unchanged at 40 dB under different humidity / temperature and simulated acid rain conditions, indicating that the electromagnetic shielding performance of the composite nanofiber membrane is environmentally stable. When simulated sweat droplets are placed on the arm, the composite nanofiber membrane can absorb the simulated sweat onto the fiber surface within 3 seconds, keeping the arm dry. Simultaneously, the composite nanofiber membrane exhibits excellent air permeability, with a water vapor transmission rate of 847 g·m³. -2 ·d-1 In sunny weather testing (average solar power 879 W / m²),... 2 The average temperature of the composite nanofiber membrane was 59.2℃, 9.8℃ lower than that of commercial cotton fabric. This is mainly attributed to the synergistic effect of radiative cooling and sweat evaporation of the composite nanofiber membrane. In tests conducted under cloudy conditions (average solar power 162W / m²),... 2 The average temperature of the composite nanofiber membrane was 36°C, which was 4.7°C higher than that of commercial cotton fabric, attributed to the synergistic effect of reduced graphene oxide and carbon nanotubes. Simultaneously, the composite nanofiber membrane exhibited good tensile strength and elongation at break, at 12 MPa and 510%, respectively. The testing method was the same as in Example 1.

[0102] Comparative Example 1

[0103] Step 1: First, the carbon nanotube film is treated with a plasma sputtering instrument to modify it into a hydrophilic carbon nanotube film. Then, the treated carbon nanotube film is placed in a silane coupling agent treatment solution and reacted for 13 hours. After the reaction stops, it is taken out, rinsed repeatedly with water and ethanol, and dried to obtain a silane coupling agent modified carbon nanotube film. The silane coupling agent treatment solution is a mixed solution of ethanol, water and 3-aminopropyltriethoxysilane in a volume ratio of 2:18:5.

[0104] Step 2: Add polyacrylonitrile to DMF solution and stir. After the solution is stirred evenly, use one side of the silane coupling agent modified carbon nanotube film prepared in Step 1 as a receiver for spinning. The mass fraction of polyacrylonitrile in the spinning solution is 10%, the spinning voltage is 17kV, and the spinning time is 10h to form a polyacrylonitrile fiber film.

[0105] Step 3: Weigh 1g of graphene oxide and react it in 10mL of hydrobromic acid for 24 hours. After the reaction, centrifuge and dry to obtain reduced graphene oxide.

[0106] Step four: First, add polyurethane to DMF and stir. After the solution is stirred evenly, add reduced graphene oxide and stir for 24 hours to obtain a spinning solution. Finally, use the other side of the silane coupling agent modified carbon nanotube film prepared in step one as a receiver for spinning to form a polyurethane fiber membrane mixed with reduced graphene oxide, thus obtaining a composite nanofiber membrane. In the spinning solution, the mass fraction of polyurethane is 25%, the mass fraction of reduced graphene oxide is 5% of polyurethane, the spinning voltage is 14kV, and the spinning time is 0.5h.

[0107] The composite nanofiber membrane prepared in Comparative Example 1 has a cooling layer (PAN) with a thickness of approximately 20 μm, a pore size of 0.4–0.5 μm, a reflectivity of 45%, an emissivity of 0.47, and a water contact angle of 49.3°; a conductive adhesive layer (APTES / CNT) with a thickness of approximately 10 μm, a pore size of 0.6–0.7 μm, an absorptivity of 0.82, an emissivity of 0.8, and a water contact angle of 51°; and a heating layer (rGO / TPU) with a thickness of approximately 8 μm, a pore size of 1–1.5 μm, an absorptivity of 0.64, an emissivity of 0.76, and a water contact angle of 125.3°.

[0108] The composite nanofiber membrane prepared in Comparative Example 1 exhibits an electromagnetic shielding value of 42 dB in the X-band and maintains excellent electromagnetic shielding performance with a shielding value of 41 dB after 500 bending and folding cycles. Furthermore, the electromagnetic shielding value of the composite nanofiber membrane prepared in Comparative Example 1 remains essentially unchanged at 40 dB under different humidity / temperature and simulated acid rain conditions, indicating that the electromagnetic shielding performance of the composite nanofiber membrane is environmentally stable. When simulated sweat droplets are placed on the arm, the composite nanofiber membrane can absorb the simulated sweat onto the fiber surface within 3 seconds, keeping the arm dry. Simultaneously, the composite nanofiber membrane demonstrates excellent air permeability, with a water vapor transmission rate of 886 g·m³. -2 ·d -1 In sunny weather testing (average solar power 879 W / m²),... 2 The composite nanofiber membrane had an average temperature of 66.7℃, which was 2.3℃ lower than that of commercial cotton fabric. In tests conducted under cloudy conditions (average solar power 162W / m²),... 2 The average temperature of the composite nanofiber membrane was 33°C, which is 2.7°C higher than that of commercial cotton fabric, attributed to the synergistic effect of reduced graphene oxide and carbon nanotubes. Simultaneously, the composite nanofiber membrane exhibited good tensile strength and elongation at break, at 11.8 MPa and 490%, respectively. The testing method was the same as in Example 1.

[0109] Comparative Example 2

[0110] Step 1: First, add 14 mL of ethanol, 2 mL of deionized water and 0.5 mL of ammonia water to a round-bottom flask and stir at 50 °C for 5 min. Then, slowly add 0.5 mL of tetraethyl silicate to the above solution and stir for 2 hours. After the reaction is complete, centrifuge and dry to obtain silica nanoparticles with a diameter of 200~500 nm.

[0111] Step 2: First, add polyacrylonitrile to the DMF solution and stir. After the solution is stirred evenly, add silica nanoparticles and stir for 15 hours to obtain a spinning solution. Then, spin to obtain a silica-blended polyacrylonitrile fiber membrane. In the spinning solution, the mass fraction of polyacrylonitrile is 10%, the mass fraction of silica nanoparticles is 50% of polyacrylonitrile, the spinning voltage is 17kV, and the spinning time is 10 hours.

[0112] Step 3: Weigh 1g of graphene oxide and react it in 10mL of hydrobromic acid for 24 hours. After the reaction, centrifuge and dry to obtain reduced graphene oxide.

[0113] Step four: First, add polyurethane to DMF and stir. After the solution is stirred evenly, add reduced graphene oxide and stir for 24 hours to obtain a spinning solution. Finally, use one side of the silica-blended polyacrylonitrile fiber membrane prepared in step two as a receiver for spinning to form a reduced graphene oxide-blended polyurethane fiber membrane, thus obtaining a composite nanofiber membrane. In the spinning solution, the mass fraction of polyurethane is 25%, the mass fraction of reduced graphene oxide is 10% of polyurethane, the spinning voltage is 14kV, and the spinning time is 0.5h.

[0114] The composite nanofiber membrane prepared in Comparative Example 2 has a cooling hydrophilic layer (SiO2 / PAN) with a thickness of approximately 20 μm, a pore size of 0.4–0.5 μm, a reflectivity of 98%, an emissivity of 0.93, and a water contact angle of 49°; the heating hydrophilic layer (rGO / TPU) has a thickness of approximately 8 μm, a pore size of 1–1.5 μm, an absorptivity of 0.73, an emissivity of 0.78, and a water contact angle of 118°.

[0115] The composite nanofiber membrane prepared in Comparative Example 2 exhibited an electromagnetic shielding value of 7 dB in the X-band and maintained excellent electromagnetic shielding performance even after 500 bending and folding cycles, with an electromagnetic shielding value approaching 0 dB. Furthermore, the composite nanofiber membrane prepared in Comparative Example 2 showed almost no electromagnetic shielding effectiveness under different humidity / temperature and simulated acid rain conditions, indicating that the electromagnetic shielding performance of the composite nanofiber membrane lacks environmental stability. When simulated sweat droplets were placed on the arm, the composite nanofiber membrane could absorb the simulated sweat onto the fiber surface within 7 seconds, keeping the arm dry. Simultaneously, the composite nanofiber membrane possessed excellent air permeability, with a water vapor transmission rate of 898 g·m³. -2 ·d -1 In sunny weather testing (average solar power 879 W / m²),... 2 The average temperature of the composite nanofiber membrane was 54°C, 15°C lower than that of commercial cotton fabric. This is mainly attributed to the synergistic effect of radiative cooling and sweat evaporation of the composite nanofiber membrane. In tests conducted under cloudy conditions (average solar power 162 W / m²),... 2The average temperature of the composite nanofiber membrane was 32°C, which is 0.7°C higher than that of commercial cotton fabric. Simultaneously, the composite nanofiber membrane exhibited good tensile strength and elongation at break, at 3 MPa and 180%, respectively. The testing method was the same as in Example 1.

[0116] Comparative Example 3

[0117] Step 1: First, add 14 mL of ethanol, 2 mL of deionized water and 0.5 mL of ammonia water to a round-bottom flask and stir at 50 °C for 5 min. Then, slowly add 0.5 mL of tetraethyl silicate to the above solution and stir for 2 hours. After the reaction is complete, centrifuge and dry to obtain silica nanoparticles with a diameter of 200~500 nm.

[0118] Step 2: First, the carbon nanotube film is modified into a hydrophilic carbon nanotube film by plasma sputtering. Then, the treated carbon nanotube film is placed in a silane coupling agent treatment solution and reacted for 13 hours. After the reaction stops, it is taken out, rinsed repeatedly with water and ethanol, and dried to obtain a silane coupling agent modified carbon nanotube film. The silane coupling agent treatment solution is a mixed solution of ethanol, water and 3-aminopropyltriethoxysilane in a volume ratio of 2:18:5.

[0119] Step 3: First, add polyacrylonitrile to the DMF solution and stir. After the solution is stirred evenly, add silica nanoparticles and stir for 15 hours to obtain the spinning solution. Finally, use one side of the silane coupling agent modified carbon nanotube film prepared in Step 2 as the receiver for spinning to form a silica-blended polyacrylonitrile fiber film. In the spinning solution, the mass fraction of polyacrylonitrile is 10%, the mass fraction of silica nanoparticles is 50% of polyacrylonitrile, the spinning voltage is 17kV, and the spinning time is 24 hours.

[0120] Step 4: Add polyurethane to DMF and stir until homogeneous to obtain a spinning solution. Finally, use the other side of the silane coupling agent modified carbon nanotube film prepared in Step 2 as a receiver for spinning to form a polyurethane fiber membrane, thus obtaining a composite nanofiber membrane. In the spinning solution, the mass fraction of polyurethane is 25%, the spinning voltage is 14kV, and the spinning time is 0.5h.

[0121] The composite nanofiber membrane prepared in Comparative Example 3 has a cooling hydrophilic layer (SiO2 / PAN) with a thickness of approximately 38 μm, a pore size of 0.4–0.5 μm, a reflectivity of 99%, an emissivity of 0.96, and a water contact angle of 48°; an intermediate conductive adhesive layer (APTES / CNT) with a thickness of approximately 10 μm, a pore size of 0.6–0.7 μm, an absorptivity of 0.82, an emissivity of 0.8, and a water contact angle of 51°; and a heating hydrophobic layer (TPU) with a thickness of approximately 8 μm, a pore size of 1–1.5 μm, an absorptivity of 0.29, an emissivity of 0.74, and a water contact angle of 128°.

[0122] The composite nanofiber membrane prepared in Comparative Example 3 exhibited an electromagnetic shielding value of 40 dB in the X-band and maintained excellent electromagnetic shielding performance after 500 bending and folding cycles, with a shielding value of 38 dB. Furthermore, the electromagnetic shielding value of the composite nanofiber membrane prepared in Comparative Example 3 remained essentially unchanged at 40 dB under different humidity / temperature and simulated acid rain conditions, indicating that the electromagnetic shielding performance of the composite nanofiber membrane is environmentally stable. When simulated sweat droplets were placed on the arm, the composite nanofiber membrane could absorb the simulated sweat onto the fiber surface within 3 seconds, keeping the arm dry. Simultaneously, the composite nanofiber membrane possessed excellent air permeability, with a water vapor transmission rate of 821 g·m³. -2 ·d -1 In sunny weather testing (average solar power 879 W / m²),... 2 The average temperature of the composite nanofiber membrane was 59°C, 10°C lower than that of commercial cotton fabric. This is mainly attributed to the synergistic effect of radiative cooling and sweat evaporation of the composite nanofiber membrane. In tests conducted under cloudy conditions (average solar power 162 W / m²),... 2 The average temperature of the composite nanofiber membrane was 32.4℃, which is 1.1℃ higher than that of commercial cotton fabric. This is mainly due to the low absorptivity of the TPU layer, making it difficult to transfer heat to the carbon nanotube layer, thus achieving excellent solar heating performance. Simultaneously, the composite nanofiber membrane exhibited good tensile strength and elongation at break, at 10 MPa and 480%, respectively. The testing method was the same as in Example 1.

[0123] Obviously, the above embodiments are merely examples for clear illustration and are not intended to limit the embodiments. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all embodiments here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A composite nanofiber membrane, characterized in that, It consists of a cooling hydrophilic layer, an intermediate adhesive conductive layer, and a heating hydrophobic layer that are fixedly arranged in sequence. The material of the cooling hydrophilic layer is a polyacrylonitrile fiber membrane blended with silica; the material of the intermediate bonding conductive layer is a carbon nanotube film modified with silane coupling agent; and the material of the heating hydrophobic layer is a polyurethane fiber membrane blended with reduced graphene oxide. The cooling hydrophilic layer has a reflectivity of 0.9-0.99 in the 0.3-2.5 μm range, an emissivity of 0.9-0.95 in the 3-16 μm range, a water contact angle of 40-50°, and a pore size of 0.3-0.5 μm. The intermediate adhesive conductive layer has an absorption rate of 0.8-0.9 in the 0.3-2.5 μm range, an emissivity of 0.8-0.85 in the 3-16 μm range, a water contact angle of 50-55°, and a pore size of 0.5-0.7 μm. The heated hydrophobic layer has an absorptivity of 0.7-0.8 in the 0.3-2.5 μm range, an emissivity of 0.75-0.8 in the 3-16 μm range, a water contact angle of 120-130°, and a pore size of 1.0-1.5 μm. The silane coupling agent is 3-aminopropyltriethoxysilane; The thickness of the intermediate adhesive conductive layer is 10~50μm; The thickness of the cooling hydrophilic layer is 12~50μm; The thickness of the heated hydrophobic layer is 5~10μm; The method for preparing the composite nanofiber membrane includes the following steps: Step 1: First, the carbon nanotube film is subjected to plasma surface treatment. Then, the treated carbon nanotube film is immersed in a silane coupling agent treatment solution for reaction. After the reaction stops, it is taken out, rinsed repeatedly with water and ethanol, and dried to obtain a silane coupling agent modified carbon nanotube film. Step 2: First, add polyacrylonitrile to the solvent and stir evenly. Then, add silica nanoparticles and stir for 10-15 hours to obtain the spinning solution. Finally, use one side of the silane coupling agent modified carbon nanotube film prepared in Step 1 as the receiver for spinning to form a silica-blended polyacrylonitrile fiber film. In the spinning solution, the mass fraction of polyacrylonitrile is 10%, and the mass fraction of silica nanoparticles is 10%~70% of polyacrylonitrile. Step 3: Add polyurethane to the solvent and stir evenly, then add reduced graphene oxide and stir for 20-24 hours to obtain the spinning solution. Finally, use the other side of the carbon nanotube film modified by the silane coupling agent prepared in Step 1 as the receiver for spinning to form a polyurethane fiber film mixed with reduced graphene oxide, thus obtaining a composite nanofiber film. In the spinning solution, the mass fraction of polyurethane is 25%, and the mass fraction of reduced graphene oxide is 5% to 20% of the polyurethane.

2. The composite nanofiber membrane according to claim 1, characterized in that, In step one, one or more of the following characteristics are present: Plasma sputtering was used to perform plasma surface treatment on carbon nanotube films. The silane coupling agent treatment solution is a mixed solution of ethanol, water and 3-aminopropyltriethoxysilane in a volume ratio of 2:18:

5. The reaction time is 13 hours.

3. The composite nanofiber membrane according to claim 1, characterized in that, In step two, one or more of the following characteristics are present: The solvent is N,N-dimethylformamide; The diameter of the silica nanoparticles is 50~500nm; The method for preparing the silica nanoparticles is as follows: first, ethanol, deionized water and ammonia are stirred at 50°C for 5 minutes, then tetraethyl silicate is added dropwise to the resulting mixed solution, stirred for 2 hours, and then centrifuged and dried to obtain silica nanoparticles; the volume ratio of ethanol, deionized water, ammonia and tetraethyl silicate is 28:4:1:

1. The spinning voltage is 15~17kV, and the spinning time is 6~12h.

4. The composite nanofiber membrane according to claim 1, characterized in that, In step two, the silica nanoparticles are mesoporous silica nanoparticles.

5. The composite nanofiber membrane according to claim 4, characterized in that, The preparation method of the mesoporous silica nanoparticles is as follows: first, hexadecyltrimethylammonium bromide, deionized water and ammonia are magnetically stirred at 35°C until the solution is clear. Then, tetraethyl silicate is added to the resulting mixed solution, and stirring is continued for 8 hours. Subsequently, the mixture is transferred to a hydrothermal reactor at 100°C and reacted for 24 hours. After centrifugation and drying, powder is obtained. Finally, the mixture is calcined at 550°C for 5 hours to obtain mesoporous silica nanoparticles. The ratio of hexadecyltrimethylammonium bromide, deionized water, ammonia and tetraethyl silicate is 0.16~0.32g:43.5mL:1.5mL:0.8mL.

6. The composite nanofiber membrane according to claim 1, characterized in that, In step three, the method for preparing the reduced graphene oxide is as follows: The graphene oxide and hydrobromic acid were mixed in a ratio of 1~3g:10~30mL. The graphene oxide was placed in hydrobromic acid and reacted for 12~24 hours. After centrifugation, the reduced graphene oxide was obtained. Alternatively, the ratio of graphene oxide, water, and hydrazine hydrate is 0.58~1.74g:100~300mL:2~6mL. After ultrasonic stirring of graphene oxide in a mixed solution of water and hydrazine hydrate for 30 minutes, the mixture is reacted at 200℃ for 24 hours, centrifuged, and dried to obtain reduced graphene oxide.

7. The composite nanofiber membrane according to claim 1, characterized in that, In step three, one or more of the following characteristics are present: The solvent is N,N-dimethylformamide; The spinning voltage is 14~15kV, and the spinning time is 0.5~2h.

8. The application of the composite nanofiber membrane according to claim 1 in wearable electromagnetic shielding materials.

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