Preparation method of high-strength flexible self-supporting hydrophobic electromagnetic shielding film

Abstract

The application discloses a preparation method of a high-strength flexible self-supporting hydrophobic electromagnetic shielding film, which comprises the following steps: weighing a certain amount of carbon titanium-aluminum, slowly adding the carbon titanium-aluminum into a lithium fluoride / hydrochloric acid etching solution, magnetically stirring in a water bath at a certain temperature for a period of time, obtaining an etched carbon titanium-aluminum dispersion liquid, carrying out acid pickling on the carbon titanium-aluminum dispersion liquid by using dilute hydrochloric acid, and then washing the carbon titanium-aluminum dispersion liquid until neutral, so as to obtain multi-layer titanium carbide; carrying out ultrasonic treatment on the multi-layer titanium carbide, so as to obtain few-layer titanium carbide; mixing the prepared few-layer titanium carbide and bacterial cellulose with nano-iron oxide respectively; alternately performing vacuum filtration on the mixed solutions of bacterial cellulose / nano-iron oxide and few-layer titanium carbide / nano-iron oxide; and naturally airing the obtained film at room temperature. Finally, methyltrimethoxysilane is deposited on the surface of the film to form a hydrophobic network. The film prepared by the method has the characteristics of good flexibility, high electromagnetic shielding performance and high mechanical strength.

Description

A method for preparing a high-strength, flexible, self-supporting hydrophobic electromagnetic shielding film Technical Field

[0001] This invention belongs to the field of electromagnetic shielding material preparation technology, specifically relating to a method for preparing a high-strength, flexible, self-supporting, hydrophobic electromagnetic shielding film. Background Technology

[0002] With the development of science and technology, electromagnetic waves have become an indispensable part of fields such as communication, medicine, military, and scientific research. However, while bringing us convenience, electromagnetic waves have also produced some adverse effects. When the intensity of electromagnetic radiation reaches a certain level, electromagnetic waves can produce thermal and non-thermal effects on biological organisms, thus causing significant harm. Secondly, electromagnetic waves with similar frequencies can affect the performance of electronic and electrical equipment, transmission channels, and systems, causing malfunctions and interference. Simultaneously, information may be leaked in the form of electromagnetic signals, leading to information leakage.

[0003] Simultaneously, with the development of 5G technology, electronic devices are becoming increasingly integrated and miniaturized, leading to the widespread adoption of lightweight and convenient electronic products in households. However, these seemingly portable products can generate significant electromagnetic radiation hazards. Therefore, designing and developing lightweight electromagnetic shielding materials with stable mechanical properties is extremely important. Traditional metallic shielding materials, due to their high conductivity, can provide satisfactory electromagnetic shielding effects. However, their inherent high density, poor corrosion resistance, and high cost limit their application in small, lightweight electronic devices. Over the past few decades, carbon-based materials such as graphene, reduced graphene oxide, and carbon nanotubes, with their corrosion resistance and low density, have been widely used for electromagnetic shielding.

[0004] In recent years, novel two-dimensional transition metal carbides / nitrides (MXenes) have attracted much attention due to their layered structure, light weight, high conductivity, and good electromagnetic interference shielding performance. MXene Ti3C2T... x Using this material as the main component, an ultra-thin electromagnetic shielding film is prepared, which can be perfectly adapted to small, lightweight electronic devices. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing a high-strength, flexible, self-supporting, hydrophobic electromagnetic shielding film. This method uses nano-iron oxide mixed with bacterial cellulose and few-layer titanium carbide to prepare a heterogeneous film layer, thereby improving the electromagnetic shielding performance.

[0006] To achieve the above objectives, the technical solution of the present invention is summarized as follows:

[0007] A method for preparing a hydrophobic, high-strength, flexible, self-supporting electromagnetic shielding film, the method comprising the following steps:

[0008] (1) Weigh a certain amount of aluminum carbide and slowly add it to a polytetrafluoroethylene beaker containing lithium fluoride / hydrochloric acid etching solution under magnetic stirring in an ice-water bath for 30 minutes.

[0009] (2) After the reaction is complete, the polytetrafluoroethylene beaker is transferred to a water bath and magnetically stirred for 36 hours to obtain an etched aluminum carbide dispersion.

[0010] (3) First, acid wash with dilute hydrochloric acid, then wash with water until neutral to obtain multilayer titanium carbide;

[0011] (4) The multilayer titanium carbide is subjected to ultrasonic treatment to open up the stacked nanosheets and obtain a few-layer titanium carbide.

[0012] (5) Disperse the few-layer titanium carbide obtained in step (4) into an aqueous solution to prepare a few-layer titanium carbide aqueous dispersion of a certain concentration; then add nano-iron oxide to the few-layer titanium carbide aqueous dispersion and stir to prepare a few-layer titanium carbide / nano-iron oxide mixed solution.

[0013] (6) Prepare a bacterial cellulose aqueous dispersion of a certain concentration; then add nano-iron oxide to the bacterial cellulose aqueous dispersion and stir to prepare a bacterial cellulose / nano-iron oxide mixed solution;

[0014] (7) The mixed solution of few-layer titanium carbide / nano iron oxide prepared in step (5) and the mixed solution of bacterial cellulose / nano iron oxide prepared in step (6) are subjected to multiple vacuum-assisted filtrations. The specific steps are as follows:

[0015] First, the bacterial cellulose / nano-ferric oxide mixed solution is filtered. After the filtrate has solidified, a few layers of titanium carbide / nano-ferric oxide mixed solution are added and filtered again. Then, the bacterial cellulose / nano-ferric oxide mixed solution is added again, and the process is repeated layer by layer. Finally, the filtrated membrane is allowed to air dry at room temperature.

[0016] (8) Methyltrimethoxysilane is deposited on the surface of the film prepared in step (7) to form a hydrophobic network. The film is dried at 60°C for 12 hours to obtain the final product, a high-strength flexible self-supporting hydrophobic electromagnetic shielding film.

[0017] Preferably, the temperature in the water bath in step (2) is 55-60℃.

[0018] Furthermore, the mass concentration of few-layer titanium carbide in the mixed solution of few-layer titanium carbide / nano-iron oxide is 1-4 mg / ml.

[0019] Furthermore, the mass ratio of nano-ferric oxide to few-layer titanium carbide in the few-layer titanium carbide / nano-ferric oxide mixed solution is 1:2 to 1:8.

[0020] Furthermore, the bacterial cellulose concentration in the bacterial cellulose / nano-iron oxide mixed solution is 1-4 mg / ml.

[0021] Furthermore, the mass ratio of nano-ferric oxide to bacterial cellulose in the bacterial cellulose / nano-ferric oxide mixed solution is 1:2 to 1:8.

[0022] Preferably, the bacterial cellulose / nano-iron oxide layer is the outer layer, and the few-layer titanium carbide / nano-iron oxide layer is the inner layer.

[0023] Preferably, the mass ratio of methyltrimethoxysilane to few-layer titanium carbide is 1:2 to 1:8.

[0024] Preferably, the number of layers in the final product film is n, where n = 3, 5, 7, 9, 11...

[0025] Furthermore, the hydrophobic, high-strength, flexible, self-supporting electromagnetic shielding film obtained according to the above preparation method also falls within the protection scope of this invention.

[0026] Advantages of this invention:

[0027] (1) One of the main raw materials used in this invention, bacterial cellulose, is a biomass-based material with good biocompatibility and is non-toxic. The addition of bacterial cellulose significantly improves the mechanical properties of the film, allowing the maximum stress-strain to reach 86.09 MPa. According to classical electromagnetic theory, the reflection of electromagnetic waves depends on the impedance difference between the two materials at the interface. Bacterial cellulose is almost non-conductive, meaning it matches the impedance of air. Therefore, it can reduce electromagnetic wave reflection and prevent secondary pollution. Simultaneously, the bacterial cellulose layer can prevent the MXene layer from contacting the air, ensuring the film's performance remains stable over a long period.

[0028] (2) After the thin film prepared by the present invention is hydrophobically treated with methyltrimethoxysilane, the contact angle increases from the original 17° to 115°, so that it can still maintain stable performance in a humid and complex environment.

[0029] (3) This invention uses an alternating vacuum filtration process, which results in close contact between the thin film layers due to the vacuum pressure. With a fixed thickness, increasing the number of heterogeneous interfaces can increase the refraction of incident electromagnetic waves, allowing the electromagnetic shielding value of a multilayer composite thin film with a thickness of only 30 μm to reach up to 68 dB. Increasing the number of heterogeneous interfaces also increases interface polarization, causing electromagnetic waves to be absorbed and consumed.

[0030] (4) The most important inventive point of this invention is that, based on the electromagnetic wave shielding and absorption mechanism, a thin film heterostructure is prepared by mixing nano-iron oxide with bacterial cellulose and MXene. Electromagnetism tells us that electromagnetic wave absorption is divided into the absorption of electric waves and magnetic waves. In the bacterial cellulose layer, nano-iron oxide acts as a magnetic filler, absorbing incident magnetic waves through natural resonance. Since the content of nano-iron oxide is low, only 5% of the bacterial cellulose mass, it does not significantly improve the conductivity of the bacterial cellulose layer. Therefore, it is compatible with air impedance, minimizing electromagnetic wave reflection and reducing secondary electromagnetic pollution. In the MXene layer, while absorbing incident magnetic waves, nano-iron oxide effectively prevents the flocculation of MXene nanosheets, forming a good conductive path, which is beneficial for MXene to absorb a large amount of electric waves through dielectric loss. Most importantly, since the heterostructure contains trace amounts of nano-iron oxide, it facilitates the formation of a complete magnetic absorption network. Magnetic waves are continuously consumed as they pass through the entire thin film layer, accumulating layer by layer until finally absorbed.

[0031] (5) The few-layer titanium carbide prepared by etching in this invention is a novel two-dimensional material with a layered structure, light weight, high conductivity, and good electromagnetic interference shielding performance. This invention is simple to operate, has widely available resources, is easy to implement, has little environmental pollution, and is easy to industrialize. Attached Figure Description

[0032] Figure 1 is a schematic diagram of the method flow of the present invention;

[0033] Figure 2 is a cross-sectional scanning electron microscope image of the composite thin films with different numbers of layers according to the present invention;

[0034] Figure 3 is a characterization diagram of the electromagnetic shielding performance of embodiments 1-4 of the present invention;

[0035] Figure 4 shows the films prepared without bacterial cellulose (a) and with bacterial cellulose (b);

[0036] Figure 5 shows the contact angles of the films without methyltrimethoxysilane treatment (a) and with methyltrimethoxysilane treatment (b). Detailed Implementation

[0037] The present invention will be further described below with reference to specific embodiments, and the advantages and features of the present invention will become clearer with the description. However, unless otherwise specified, the specific experimental methods involved in the following embodiments are conventional methods or implemented according to the conditions recommended in the manufacturer's instructions.

[0038] Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the experimental methods in the following embodiments are all conventional methods. Unless otherwise specified, the reagents and materials used can be purchased commercially.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as are familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be used in this invention. The preferred embodiments and materials described herein are for illustrative purposes only.

[0040] Example

[0041] (1) Weigh a certain amount of aluminum carbide powder and slowly add it to a polytetrafluoroethylene beaker containing lithium fluoride / hydrochloric acid etching solution under magnetic stirring in an ice water bath for 30 min.

[0042] (2) After the reaction is complete, the polytetrafluoroethylene beaker is transferred to a water bath and magnetically stirred for 36 hours to obtain an etched aluminum carbide dispersion.

[0043] (3) First, acid wash with dilute hydrochloric acid, then wash with water until neutral to obtain multilayer titanium carbide;

[0044] (4) The multilayer titanium carbide is subjected to ultrasonic treatment to open up the stacked nanosheets and obtain a few-layer titanium carbide.

[0045] (5) Disperse the few-layer titanium carbide obtained in step (4) into an aqueous solution to prepare a few-layer titanium carbide aqueous dispersion of a certain concentration; then add nano-iron oxide to the few-layer titanium carbide aqueous dispersion and stir to prepare a few-layer titanium carbide / nano-iron oxide mixed solution.

[0046] (6) Prepare a bacterial cellulose aqueous dispersion of a certain concentration; then add nano-iron oxide to the bacterial cellulose aqueous dispersion and stir to prepare a bacterial cellulose / nano-iron oxide mixed solution;

[0047] (7) The mixed solution of few-layer titanium carbide / nano iron oxide prepared in step (5) and the mixed solution of bacterial cellulose / nano iron oxide prepared in step (6) are subjected to vacuum-assisted filtration multiple times.

[0048] (8) MTMS is deposited on the surface of the film prepared in step (7) to form a hydrophobic network. The film is dried at 60°C for 12 hours to obtain the final product, a high-strength flexible self-supporting hydrophobic electromagnetic shielding film.

[0049] Example 1

[0050] a. Slowly add 1g of aluminum carbide powder to a mixed solution containing 1g of lithium fluoride and 30ml of 9M hydrochloric acid to obtain an etched few-layer titanium carbide dispersion.

[0051] b. Add 0.5g of nano-iron oxide to the thin-layer titanium carbide dispersion and mix thoroughly.

[0052] c. Dissolve 1g of bacterial cellulose in 10ml of water and mix well. Add 0.5g of nano-ferric oxide to the bacterial cellulose aqueous dispersion.

[0053] d. A multilayer composite film is prepared by alternating vacuum filtration of the obtained mixed solutions of few-layer titanium carbide / nano-iron oxide and bacterial cellulose / iron oxide. In this method, the number of layers in the bacterial cellulose / nano-iron oxide and the few-layer titanium carbide / nano-iron oxide mixtures are 2 and 1, respectively.

[0054] e. MTMS is deposited on the film surface by drying at 60°C for 12 hours in a vacuum drying oven, wherein the amount of methyltrimethoxysilane is 1 mL.

[0055] Example 2

[0056] a. Slowly add 2g of aluminum carbide powder to a mixed solution containing 2g of lithium fluoride and 30ml of 10M hydrochloric acid to obtain an etched titanium carbide dispersion with few layers.

[0057] b. Add 1.0g of nano-iron oxide to the few-layer titanium carbide dispersion and mix thoroughly.

[0058] c. Dissolve 2g of bacterial cellulose in 10ml of water and mix well. Add 1.0g of nano-ferric oxide to the bacterial cellulose aqueous dispersion.

[0059] d. A multilayer composite film is prepared by alternating vacuum filtration of the obtained mixed solutions of few-layer titanium carbide / nano-iron oxide and bacterial cellulose / iron oxide. In this method, the number of layers in the bacterial cellulose / nano-iron oxide and the few-layer titanium carbide / nano-iron oxide mixtures are 3 and 2, respectively.

[0060] e. MTMS is deposited on the film surface by drying at 60°C for 12 hours in a vacuum drying oven; the amount of methyltrimethoxysilane is 2 mL.

[0061] Example 3

[0062] a. Slowly add 3g of aluminum carbide powder to a mixed solution containing 3g of lithium fluoride and 30ml of 11M hydrochloric acid to obtain a few-layer titanium carbide dispersion after etching.

[0063] b. Add 1.5g of nano-iron oxide to the few-layer titanium carbide dispersion and mix well.

[0064] c. Dissolve 3g of bacterial cellulose in 10ml of water and mix well. Add 1.5g of nano-ferric oxide to the bacterial cellulose aqueous dispersion.

[0065] d. A multilayer composite film is prepared by alternating vacuum filtration of the obtained mixed solutions of few-layer titanium carbide / nano-iron oxide and bacterial cellulose / iron oxide. In this method, the number of layers in the bacterial cellulose / nano-iron oxide and the few-layer titanium carbide / nano-iron oxide mixtures are 4 and 3, respectively.

[0066] e. MTMS is deposited on the film surface by drying at 60°C for 12 hours in a vacuum drying oven. The amount of methyltrimethoxysilane is 3 mL.

[0067] Example 4

[0068] a. Slowly add 4g of aluminum carbide powder to a mixed solution containing 4g of lithium fluoride and 30ml of 12M hydrochloric acid to obtain an etched few-layer titanium carbide dispersion.

[0069] b. Add 2.0g of nano-iron oxide to the thin-layer titanium carbide dispersion and mix thoroughly.

[0070] c. Dissolve 4g of bacterial cellulose in 10ml of water and mix well. Add 2.0g of nano-ferric oxide to the bacterial cellulose aqueous dispersion.

[0071] d. A multilayer composite film is prepared by alternating vacuum filtration of the obtained mixed solutions of few-layer titanium carbide / nano-iron oxide and bacterial cellulose / iron oxide. In this method, the number of layers in the bacterial cellulose / nano-iron oxide and the few-layer titanium carbide / nano-iron oxide mixtures are 5 and 4, respectively.

[0072] e. MTMS is deposited on the film surface by drying at 60°C for 12 hours in a vacuum drying oven; the amount of methyltrimethoxysilane is 4 mL.

[0073] Comparative Example 1 (Bacterial cellulose-free)

[0074] a. Slowly add 3g of aluminum carbide powder to a mixed solution containing 3g of lithium fluoride and 30ml of 11M hydrochloric acid to obtain a few-layer titanium carbide dispersion after etching.

[0075] b. Add 1.5g of nano-iron oxide to the few-layer titanium carbide dispersion and mix well.

[0076] c. The obtained few-layer titanium carbide / nano-iron oxide film was prepared by alternating vacuum filtration.

[0077] d. MTMS is deposited on the film surface by drying at 60°C for 12 hours in a vacuum drying oven. The amount of methyltrimethoxysilane is 3 mL.

[0078] Comparative Example 2 (without few-layer titanium carbide)

[0079] a. Dissolve 3g of bacterial cellulose in 10ml of water and mix well. Add 1.5g of nano-ferric oxide to the bacterial cellulose aqueous dispersion;

[0080] d. Prepare a thin film by vacuum filtration of a bacterial cellulose / ferric oxide mixed solution.

[0081] e. MTMS is deposited on the film surface by drying at 60°C for 12 hours in a vacuum drying oven. The amount of methyltrimethoxysilane is 3 mL.

[0082] Comparative Example 3 (without nano-iron oxide)

[0083] a. Slowly add 3g of aluminum carbide powder to a mixed solution containing 3g of lithium fluoride and 30ml of 11M hydrochloric acid to obtain a few-layer titanium carbide dispersion after etching.

[0084] c. Dissolve 3g of bacterial cellulose in 10ml of water and mix well.

[0085] d. The obtained few-layer titanium carbide and bacterial cellulose solutions were used to prepare multilayer composite films by alternating vacuum filtration. In this method, the number of layers of bacterial cellulose and few-layer titanium carbide were 4 and 3, respectively.

[0086] e. MTMS is deposited on the film surface by drying at 60°C for 12 hours in a vacuum drying oven. The amount of methyltrimethoxysilane is 3 mL.

[0087] Comparative Example 4 (without methyltrimethoxysilane)

[0088] a. Slowly add 3g of aluminum carbide powder to a mixed solution containing 3g of lithium fluoride and 30ml of 11M hydrochloric acid to obtain a few-layer titanium carbide dispersion after etching.

[0089] b. Add 1.5g of nano-iron oxide to the few-layer titanium carbide dispersion and mix well.

[0090] c. Dissolve 3g of bacterial cellulose in 10ml of water and mix well. Add 1.5g of nano-ferric oxide to the bacterial cellulose aqueous dispersion.

[0091] d. A multilayer composite film is prepared by alternating vacuum filtration of the obtained mixed solutions of few-layer titanium carbide / nano-iron oxide and bacterial cellulose / iron oxide. In this method, the number of layers in the bacterial cellulose / nano-iron oxide and the few-layer titanium carbide / nano-iron oxide mixtures are 4 and 3, respectively.

[0092] e. Dry in a vacuum drying oven at 60°C for 12 hours.

[0093] Table 1 Performance test results of each embodiment

[0094]

[0095]

[0096] Table 2 shows the performance test results of each comparative example.

[0097]

[0098] As can be seen from Examples 1-4, the electromagnetic shielding performance of the composite film first increases and then decreases with the increase of the mass of the few-layer titanium carbide, with the electromagnetic shielding performance reaching its best in Example 3. This may be because excessive few-layer titanium carbide and nano-ferric oxide will flocculate inside the film, reducing the polarization point, decreasing the specific surface area, and hindering charge propagation, thus preventing further increase in the electromagnetic shielding value.

[0099] As can be seen from Comparative Example 1, bacterial cellulose is the matrix of the composite film, providing excellent mechanical properties. Without the addition of bacterial cellulose, film formation is impossible.

[0100] As can be seen from Comparative Example 2, the electromagnetic shielding performance and conductivity of the composite film are mainly due to the few-layer titanium carbide. Without the few-layer titanium carbide, the electromagnetic shielding value is only 3dB, which hardly produces any electromagnetic interference.

[0101] As can be seen from Comparative Example 3, the electromagnetic shielding performance of the composite film is also affected by the content of nano-ferric oxide. This is because ferric oxide, as a typical magnetic oxide, can absorb incident magnetic waves and undergo hysteresis. The lack of ferric oxide will cause the magnetic waves entering the film to be unable to be absorbed, thereby reducing the total electromagnetic shielding value.

[0102] As can be seen from Comparative Example 4, methyltrimethoxysilane in the composite film mainly plays a hydrophobic role. When methyltrimethoxysilane is absent, the contact angle of the composite film is only 16.74°, which is much lower than the contact angle of the composite film coated with methyltrimethoxysilane.

[0103] The embodiments described above are merely preferred embodiments of the present invention and are only used to explain the present invention. They are not intended to limit the scope of the present invention. For those skilled in the art, other implementation methods can be easily made by substitution or modification based on the technical content disclosed in this specification. Therefore, all changes and improvements made on the principle of the present invention should be included within the scope of the patent application of the present invention.

Claims

1. A method for preparing a hydrophobic, high-strength, flexible, self-supporting electromagnetic shielding film, characterized in that, The preparation method includes the following steps: (1) Weigh a certain amount of aluminum carbide powder and slowly add it to a polytetrafluoroethylene beaker containing lithium fluoride / hydrochloric acid etching solution under magnetic stirring in an ice-water bath for 30 min; (2) After the reaction, transfer the polytetrafluoroethylene beaker to a water bath and stir magnetically for 36 h to obtain an etched aluminum carbide dispersion; (3) First, acid wash with dilute hydrochloric acid, then wash with water until neutral to obtain multilayer titanium carbide; (4) Perform ultrasonic treatment on the multilayer titanium carbide, and use ultrasound to open the stacked nanosheets to obtain few-layer titanium carbide; (5) Disperse the few-layer titanium carbide obtained in step (4) into an aqueous solution to prepare a few-layer titanium carbide aqueous dispersion of a certain concentration; and then perform few-layer titanium carbide etching. (6) Add nano-Fe3O4 to the titanium aqueous dispersion and stir to prepare a mixed solution of titanium carbide / nano-Fe3O4; (7) Prepare a bacterial cellulose aqueous dispersion of a certain concentration; then add nano-Fe3O4 to the bacterial cellulose aqueous dispersion and stir to prepare a mixed solution of bacterial cellulose / nano-Fe3O4; (8) Perform multiple vacuum-assisted filtrations on the mixed solution of titanium carbide / nano-Fe3O4 prepared in step (5) and the mixed solution of bacterial cellulose / nano-Fe3O4 prepared in step (6). The specific steps are as follows: First, the mixed solution of bacterial cellulose / nano-Fe3O4 is filtered. After the filtration is formed, the mixed solution of titanium carbide / nano-Fe3O4 is added to it and filtered again to form the filtration. Then, the bacterial cellulose / nano iron oxide mixed solution was added again, and the layers were filtered sequentially. Finally, the film formed by filtration was naturally dried at room temperature. (8) Methyltrimethoxysilane was deposited on the surface of the film prepared in step (7) to form a hydrophobic network. The film was dried at 60°C for 12 hours to obtain the final product, a high-strength flexible self-supporting hydrophobic electromagnetic shielding film.

2. The preparation method according to claim 1, characterized in that, Step (2) The temperature in the water bath is 55-60℃.

3. The preparation method according to claim 1, characterized in that, The mass concentration of the few-layer titanium carbide is 1-4 mg / ml.

4. The preparation method according to claim 1, characterized in that, The bacterial cellulose concentration is 1-4 mg / ml.

5. The preparation method according to claim 1, characterized in that, The mass ratio of nano-ferric oxide to few-layer titanium carbide in the mixed solution of titanium carbide / nano-ferric oxide is 1:2 to 1:

8.

6. The preparation method according to claim 1, characterized in that, The mass ratio of nano-ferric oxide to bacterial cellulose in the bacterial cellulose / nano-ferric oxide mixed solution is 1:2 to 1:

8.

7. The preparation method according to claim 1, characterized in that, The bacterial cellulose / nano-iron oxide layer is the outer layer, and the few-layer titanium carbide / nano-iron oxide layer is the inner layer.

8. The preparation method according to claim 1, characterized in that, The mass ratio of the added methyltrimethoxysilane to the few-layer titanium carbide is 1:2 to 1:

8.

9. The preparation method according to claim 1, characterized in that, The final product film obtained has n layers, where n = 3, 5, 7, 9...

10. A hydrophobic, high-strength, flexible, self-supporting electromagnetic shielding film, characterized in that, It is prepared according to the preparation method according to any one of claims 1-9.

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