Preparation method and application of a high-performance, long-life two-dimensional nanostructured multilayer stable electromagnetic shielding composite film

Abstract

The present application discloses a preparation method and application of a high-efficiency, long-life two-dimensional nanostructured multilayer stable electromagnetic shielding composite film. A vacuum-assisted fluid-guided self-assembly method is adopted to disperse one-dimensional nanowires and two-dimensional nanosheets and / or an organic reinforcing agent in water to prepare a uniform suspension A. A MXene aqueous solution is used as solution B. According to the size of the self-assembly device, the suspension A is poured into the device for self-assembly into a lower composite protective film. Subsequently, the solution B is poured into the device and self-assembled on top of the lower protective film into a pure MXene film as an intermediate high-efficiency electromagnetic shielding layer. Finally, an upper protective film with the same material and thickness as the lower protective film is assembled on the upper surface of the MXene layer. After vacuum drying, a sandwich-structured multilayer stable electromagnetic shielding composite film with excellent mechanical flexibility, environmental stability and high-efficiency electromagnetic shielding performance is finally obtained. The film preparation method is simple and can be prepared in batches to solve the problem of electromagnetic interference.

Description

Technical Field

[0001] The present invention relates to the field of electromagnetic shielding technology, and in particular to a preparation method and application of a high-efficiency, long-life, two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film. Background Art

[0002] With the increasing prevalence of telecommunications systems and wireless electronic devices, electromagnetic waves are being emitted by an increasing number of devices and equipment, including wireless equipment, antenna systems, communication equipment, radar, sensors, portable digital hardware, and various electronic terminals. These tools have become an integral part of modern life and social development. However, certain electromagnetic waves can disrupt the operation of electronic devices to a certain extent, a phenomenon known as electromagnetic interference (EMI). EMI can affect the transmission of communication signals, increase energy consumption in electronic devices, and reduce device efficiency. Furthermore, high-energy electromagnetic radiation poses a threat to human health. Electromagnetic radiation energy can be transmitted to cells, causing abnormal body temperatures, protein inactivation, and increasing the likelihood of genetic mutations. To address the increasingly serious problem of EMI, high-performance electromagnetic shielding materials are needed.

[0003] Graphene oxide (GO), due to its lamellar structure and rich oxygen-containing functional groups at its edges, possesses excellent hydrophilicity and is easy to process and assemble. It also offers relatively good flexibility and low cost. However, GO generally suffers from poor electromagnetic interference (EMI) shielding performance, failing to meet common military EMI shielding requirements. Introducing nanowire structures into GO is expected to improve the film's flexibility. The conductive network formed by the nanowires also allows for tighter connections between layers.

[0004] MXene is a new type of two-dimensional layered material developed in recent years. It has good electrical conductivity and excellent electrochemical storage performance, as well as good processability and designability. It is a very promising material for controlling electromagnetic pollution. The presence of pores promotes multiple attenuation of electromagnetic waves, but it is easily oxidized, resulting in a decrease in shielding performance. If a GO mixed layer is introduced into MXene, the flexibility of the film will inevitably be improved without significantly increasing the density, thereby obtaining satisfactory electromagnetic shielding performance. At the same time, the GO mixed layer can effectively prevent MXene from contacting with air.

[0005] Play an anti-oxidation role.

[0006] Chinese patent CN108615582A discloses a method for preparing a flexible transparent conductive film based on silver nanowires and graphene composites, comprising the following steps: S10, providing a substrate; S20, applying a graphene dispersion onto the substrate to obtain a graphene layer, and then hot-pressing the graphene layer; S30, applying PEDOTPH1000 onto the graphene layer to obtain a PEDOTPH1000 layer of at least 30 nm; S40, applying a silver nanowire suspension onto the PEDOTPH1000 layer to obtain a silver nanowire layer, and then hot-pressing the silver nanowire layer. This method has simple process steps, and the resulting flexible transparent conductive film has improved conductivity and transmittance, and a longer service life. Chinese patent CN113087972A discloses a MXene / silver nanowire / nanocellulose composite film and its preparation method. The main steps of the method are: (1) etching MAX to prepare a single-layer MXene colloidal solution; (2) preparing a silver nanowire colloidal solution; (3) preparing a carboxylated nanocellulose colloidal solution by TEMPO oxidation; (4) mixing the above three colloidal solutions in a certain mass ratio, stirring, and ice-bath ultrasonication to obtain a uniform mixed solution; (5) vacuum filtering the mixed solution and hot-pressing and drying to obtain a MXene / silver nanowire / nanocellulose composite film. A method for preparing a MXene / silver nanowire / nanocellulose composite film is provided. The prepared composite film has good flexibility, electrochemical properties, electromagnetic shielding properties, and antibacterial properties, and has broad application prospects in aerospace, weaponry, flexible wearable devices, and other fields. Chinese patent CN114914100A discloses a graphene / MXene composite film and its preparation method. The preparation method comprises: preparing a MXene aqueous solution, a graphene oxide aqueous solution, and a polystyrene nanosphere dispersion; mixing the MXene aqueous solution, the graphene oxide aqueous solution, and the polystyrene nanosphere dispersion, ultrasonically dispersing the mixture, applying the mixture to a film surface by vacuum filtration to obtain a composite film; and calcining the composite film under an inert atmosphere to obtain a graphene / MXene composite film. The provided preparation method is simple, has mild reaction conditions, and is easily scalable. The prepared graphene / MXene composite film has a multi-level mesoporous structure, which reduces the aggregation of graphene and MXene, resulting in good capacitance performance. The graphene / MXene composite film also has good bending flexibility and is expected to be directly used as an electrode material for flexible supercapacitors.Chinese patent CN111883314A discloses a method for preparing an oxidized cellulose-graphene nanoribbon-MXene composite conductive film, comprising the following steps: 1) treating cellulose with TEMPO oxidation to obtain an oxidized cellulose dispersion; 2) dispersing multi-walled carbon nanotubes in concentrated sulfuric acid, oxidizing with potassium permanganate, and decompressing to obtain graphene nanoribbons; 3) preparing a MXene aqueous solution of a certain concentration and dispersing it with liquid nitrogen to obtain a monolayer MXene dispersion; and 4) blending the oxidized cellulose dispersion with the graphene nanoribbons and MXene dispersion in a certain proportion, and vacuum filtration to obtain the oxidized cellulose-graphene nanoribbon-MXene composite conductive film. The process is simple, easy to operate, and environmentally friendly. The prepared film exhibits excellent flexibility and conductivity, good biocompatibility, and mechanical properties, making it suitable for wearable sensor fabrication and bioassay applications. However, due to the limited flexibility, structural instability, and susceptibility of MXene to oxidation, the existing technology has some shortcomings. Summary of the Invention

[0007] Technical problem to be solved: This application proposes a preparation method and application of a high-efficiency, long-life two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film to solve the problems in the prior art that electromagnetic interference can affect the transmission of communication signals, increase the energy consumption of electronic devices and reduce the working efficiency of equipment, high-energy electromagnetic radiation can also threaten human health, and MXene is easily oxidized. One-dimensional nanowires and GO or organic reinforcing agents play a self-supporting role and can improve the flexibility of the composite film, with good electromagnetic shielding performance to solve the existing electromagnetic pollution problem.

[0008] Technical solution:

[0009] A method for preparing a high-efficiency, long-life two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film, wherein the high-efficiency, long-life two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film is made of two or three materials selected from the group consisting of one-dimensional nanowires, two-dimensional nanosheets, and an organic reinforcing agent. The one-dimensional nanowires are one or more selected from the group consisting of MnO2, TiO2, SiO2, V2O5, Al2O3, SiC, and SiN nanowires; the two-dimensional nanosheets are graphene oxide and MXene; and the organic reinforcing agent is latex, polyaniline, or bacterial cellulose.

[0010] Furthermore, the preparation method of the high-performance, long-life two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film comprises the following specific steps:

[0011] Step 1: Weigh one-dimensional nanowires, graphene oxide, and / or an organic reinforcing agent and dissolve them in 50 mL of ultrapure water while stirring continuously. After stirring evenly, sonicate the mixed aqueous solution for 5 minutes, then let it stand for 10 minutes. Repeat the sonication and standing steps 5 times to prepare a mixed suspension solution.

[0012] Step 2: vacuum-assisted fluid-guided self-assembly of the mixed suspension solution in the first step into a lower composite protective film;

[0013] Step 3: Based on the second step, pour the MXene aqueous solution onto the top of the lower composite protective film to self-assemble into a middle high-efficiency electromagnetic shielding layer film;

[0014] Step 4: Based on the third step, prepare another portion of the mixed suspension from the first step and pour it on top of the middle high-efficiency electromagnetic shielding layer film, and self-assemble into an upper composite protective film to obtain the target product, a high-efficiency, long-life two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film.

[0015] As a preferred technical solution of the present application, the thickness of the high-performance, long-life two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film is 50um-500um.

[0016] As a preferred technical solution of the present application, the solvent of the mixed suspension in the first step is water.

[0017] As a preferred technical solution of the present application, the mass fraction ratio of the one-dimensional nanowires, graphene oxide and organic reinforcing agent in the first step is 80-40:40-10:20-0.

[0018] As a preferred technical solution of the present application, in the first step, one-dimensional nanowires, graphene oxide and / or organic reinforcing agent are dissolved in 50 mL of ultrapure water and mixed evenly by means of magnetic stirring at room temperature for 2-6 hours.

[0019] As a preferred technical solution of this application, the concentration of the MXene aqueous solution in the third step is 0.1-1 mg·mL -1 .

[0020] As a preferred technical solution of the present application, the film forming process in the second, third and fourth steps utilizes vacuum-assisted fluid-guided self-assembly, and the pore size of the filter membrane used in the vacuum-assisted fluid-guided self-assembly process is 0.2-0.8um.

[0021] As a preferred technical solution of the present application, the diameter of the one-dimensional nanowire is 20nm-50nm, and the length is 10um-30um.

[0022] As a preferred technical solution of the present application, the two-dimensional nanosheet is in the form of large-sized sheets, and the thickness of a single layer of the two-dimensional nanosheet is 1 nm-2 nm.

[0023] The present application also discloses the application of a high-performance, long-life, two-dimensional nanostructured multilayer stable electromagnetic shielding composite film prepared by any of the above-mentioned preparation methods in an electromagnetic shielding device. The prepared multilayer stable electromagnetic shielding composite film exhibits an electromagnetic shielding effect of up to 60dB and maintains stable electromagnetic shielding performance within two months. The electromagnetic shielding test process uses an E5071C RF network analyzer with a test frequency of 8.2GHz-12.5GHz.

[0024] The technical principle of this application is: the presence of pores in MXene materials promotes multiple attenuation of electromagnetic waves, has good electrical conductivity and excellent electrochemical storage performance, and is a very promising material for controlling electromagnetic pollution, but it has the problem of being easily oxidized. Two-dimensional nanosheets have good hydrophilicity, are easy to assemble and process, have relatively excellent electromagnetic wave absorption capacity, and can isolate the contact between the MXene layer in the sandwich structure and the air, playing an antioxidant role. The introduction of a GO mixed layer in MXene is bound to improve the flexibility of the film without significantly increasing the density, thereby obtaining satisfactory electromagnetic shielding performance. At the same time, the GO mixed layer can effectively prevent the contact between MXene and the air, playing an anti-oxidation role. A sandwich structure electromagnetic shielding composite film is prepared from one-dimensional nanowires, two-dimensional nanosheets, organic reinforcing agents and MXene materials, wherein the MXene material has good electrical conductivity and good ability to absorb and reflect electromagnetic waves. Due to its large layer structure, the two-dimensional nanosheet material has excellent flexibility. At the same time, it can effectively isolate MXene from the oxidation reaction with oxygen in the air and has anti-oxidation properties. One-dimensional nanowires and organic reinforcing materials can provide a favorable self-supporting skeleton and excellent flexibility for the multilayer film structure.

[0025] Beneficial effects:

[0026] 1. Compared with the existing technology for synthesizing electromagnetic shielding films, the preparation process of the present invention is simple and easy to operate. Through vacuum-assisted fluid-guided self-assembly, a high-performance, long-life, two-dimensional nanostructured, multi-layered, stable electromagnetic shielding composite film can be obtained.

[0027] 2. The prepared one-dimensional nanowires have an excellent length of tens of microns, providing more significant flexibility for the composite film.

[0028] 3. The films on both sides of the sandwich structure are used to prevent oxidation, providing a relatively complete oxygen-free environment for the MXene film in the middle layer, so that the electromagnetic shielding performance remains relatively stable.

[0029] 4. A high-performance, long-life, two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film prepared by the preparation method of the present invention shows an electromagnetic shielding performance of up to 60dB, and can maintain stable electromagnetic shielding performance within 2 months.

[0030] 5. A high-performance, long-life, two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film prepared by the preparation method of the present invention has withstood more than 1,000 bending tests, proving that it has excellent flexibility.

[0031] 6. The process of the present invention is simple, has good reproducibility, and the raw materials used are easily available, making it easy to produce in batches.

[0032] 7. Compared to existing technologies, this application utilizes a multilayer structure, with a highly flexible protective film laminated above and below the MXene film, thereby protecting the integrity of the MXene structure and properties. This allows the multilayered, stable electromagnetic shielding composite film to provide high-performance electromagnetic shielding while maintaining stable shielding performance. Furthermore, the composite film possesses excellent hydrophilicity and flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a cross-sectional SEM image of the high-performance, long-life, two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film prepared in Example 1 of the present application;

[0034] Figure 2 This is a graph showing the electromagnetic shielding performance of the high-performance, long-life, two-dimensional nanostructured multi-layer stable electromagnetic shielding composite films prepared in Examples 1, 3, and 4 of the present application;

[0035] Figure 3 This is a graph showing the electromagnetic shielding performance retention of the high-performance, long-life, two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film prepared in Example 2 of the present application. DETAILED DESCRIPTION

[0036] The technical solutions of the present invention are further described below in conjunction with the accompanying drawings and specific embodiments. These embodiments are only used to illustrate the present invention and are not limited to the following embodiments. Any modification or equivalent replacement of the technical solutions of the present invention that does not depart from the spirit and scope of the technical solutions of the present invention shall be included in the scope of protection of the present invention.

[0037] In the following embodiments, a high-performance, long-life, two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film is prepared using one-dimensional nanowires, two-dimensional nanosheets or organic reinforcing agents, and is prepared by a vacuum-assisted fluid-guided self-assembly method.

[0038] The composite film was tested for electromagnetic shielding using an E5071C RF network analyzer. Two waveguide-coaxial converters were connected to port 1 and port 2 of the network analyzer, respectively. After calibration, the composite film was placed between the two waveguide-coaxial converters and the real and imaginary parameters of S21 were read. Using the formula:

[0039] SE=-20log|S21|

[0040] Calculate the corresponding electromagnetic shielding performance value.

[0041] Example 1:

[0042] A method for preparing a high-performance, long-life, two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film, the specific steps of which are as follows:

[0043] Step 1: Dissolve 50 mg of MnO2 nanowires and 10 mg of graphene oxide in 50 mL of ultrapure water while stirring continuously. After stirring evenly, ultrasonicate the mixed aqueous solution for 5 minutes, then let it stand for 10 minutes. Repeat the ultrasonication and standing steps 5 times.

[0044] Step 2: Using filter paper with a pore size of 0.8 μm, the product of the first step is subjected to vacuum-assisted fluid-guided self-assembly to form a lower composite protective film;

[0045] Step 3: Based on the second step, 50 mL of 0.1 mg / mL MXene aqueous solution is poured onto the top of the lower composite protective film to self-assemble into a middle high-efficiency electromagnetic shielding layer;

[0046] Step 4: Based on the third step, prepare another portion of the mixed suspension from the first step and pour it onto the top of the high-efficiency electromagnetic shielding layer film to self-assemble into an upper composite protective film to obtain the target product, the electromagnetic shielding composite film.

[0047] Example 2:

[0048] A method for preparing a high-performance, long-life, two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film, the specific steps of which are as follows:

[0049] Step 1: Dissolve 50 mg of MnO2 nanowires and 10 mg of graphene oxide in 50 mL of ultrapure water while stirring continuously. After stirring evenly, ultrasonicate the mixed aqueous solution for 5 minutes, then let it stand for 10 minutes. Repeat the ultrasonication and standing steps 5 times.

[0050] Step 2: Using filter paper with a pore size of 0.8 μm, the product of the first step is subjected to vacuum-assisted fluid-guided self-assembly to form a lower composite protective film;

[0051] Step 3: Based on the second step, 75 mL of 0.1 mg / mL MXene aqueous solution is poured onto the top of the lower composite protective film to self-assemble into a middle high-efficiency electromagnetic shielding layer;

[0052] Step 4: Based on the third step, prepare another portion of the mixed suspension from the first step and pour it onto the top of the high-efficiency electromagnetic shielding layer film to self-assemble into an upper composite protective film to obtain the target product, the electromagnetic shielding composite film.

[0053] Example 3:

[0054] A method for preparing a high-performance, long-life, two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film, the specific steps of which are as follows:

[0055] Step 1: Dissolve 50 mg of MnO2 nanowires and 10 mg of graphene oxide in 50 mL of ultrapure water while stirring continuously. After stirring evenly, ultrasonicate the mixed aqueous solution for 5 minutes, then let it stand for 10 minutes. Repeat the ultrasonication and standing steps 5 times.

[0056] Step 2: Using filter paper with a pore size of 0.8 μm, the product of the first step is subjected to vacuum-assisted fluid-guided self-assembly to form a lower composite protective film;

[0057] Step 3: Based on the second step, 100 mL of 0.1 mg / mL MXene aqueous solution is poured onto the top of the lower composite protective film to self-assemble into a middle high-efficiency electromagnetic shielding layer;

[0058] Step 4: Based on the third step, prepare another portion of the mixed suspension from the first step and pour it onto the top of the high-efficiency electromagnetic shielding layer film to self-assemble into an upper composite protective film to obtain the target product, the electromagnetic shielding composite film.

[0059] Example 4:

[0060] A method for preparing a high-performance, long-life, two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film, the specific steps of which are as follows:

[0061] Step 1: Dissolve 50 mg of MnO2 nanowires and 10 mg of graphene oxide in 50 mL of ultrapure water while stirring continuously. After stirring evenly, ultrasonicate the mixed aqueous solution for 5 minutes, then let it stand for 10 minutes. Repeat the ultrasonication and standing steps 5 times.

[0062] Step 2: Using filter paper with a pore size of 0.8 μm, the product of the first step is subjected to vacuum-assisted fluid-guided self-assembly to form a lower composite protective film;

[0063] Step 3: Based on the second step, 200 mL of 0.1 mg / mL MXene aqueous solution was poured onto the top of the lower composite protective film to self-assemble into a middle high-efficiency electromagnetic shielding layer;

[0064] Step 4: Based on the third step, prepare another portion of the mixed suspension from the first step and pour it onto the top of the high-efficiency electromagnetic shielding layer film to self-assemble into an upper composite protective film to obtain the target product, the electromagnetic shielding composite film.

[0065] Example 5:

[0066] A method for preparing a high-performance, long-life, two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film, the specific steps of which are as follows:

[0067] Step 1: Dissolve 30 mg of V2O5 nanowires, 10 mg of graphene oxide, and 1 mg of latex in 50 mL of ultrapure water while stirring continuously. After stirring evenly, sonicate the mixed aqueous solution for 5 minutes, then let it stand for 10 minutes. Repeat the sonication and standing steps 5 times.

[0068] Step 2: Using filter paper with a pore size of 0.8 μm, the product of the first step is subjected to vacuum-assisted fluid-guided self-assembly to form a lower composite protective film;

[0069] Step 3: Based on the second step, 120 mL of 0.1 mg / mL MXene aqueous solution is poured onto the top of the lower composite protective film to self-assemble into a middle high-efficiency electromagnetic shielding layer;

[0070] Step 4: Based on the third step, prepare another portion of the mixed suspension from the first step and pour it onto the top of the high-efficiency electromagnetic shielding layer film to self-assemble into an upper composite protective film to obtain the target product, the electromagnetic shielding composite film.

[0071] Example 6:

[0072] A method for preparing a high-performance, long-life, two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film, the specific steps of which are as follows:

[0073] Step 1: Dissolve 30 mg of V2O5 nanowires, 10 mg of graphene oxide, and 1 mg of latex in 50 mL of ultrapure water while stirring continuously. After stirring evenly, sonicate the mixed aqueous solution for 5 minutes, then let it stand for 10 minutes. Repeat the sonication and standing steps 5 times.

[0074] Step 2: Using filter paper with a pore size of 0.8 μm, the product of the first step is subjected to vacuum-assisted fluid-guided self-assembly to form a lower composite protective film;

[0075] Step 3: Based on the second step, 100 mL of 0.1 mg / mL MXene aqueous solution is poured onto the top of the lower composite protective film to self-assemble into a middle high-efficiency electromagnetic shielding layer;

[0076] Step 4: Based on the third step, prepare another portion of the mixed suspension from the first step and pour it onto the top of the high-efficiency electromagnetic shielding layer film to self-assemble into an upper composite protective film to obtain the target product, the electromagnetic shielding composite film.

[0077] Example 7:

[0078] A method for preparing a high-performance, long-life, two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film, the specific steps of which are as follows:

[0079] Step 1: Dissolve 60 mg of V2O5 nanowires, 20 mg of graphene oxide, and 2 mg of latex in 50 mL of ultrapure water while stirring continuously. After stirring evenly, ultrasonicate the mixed aqueous solution for 5 minutes, then let it stand for 10 minutes. Repeat the ultrasonication and standing steps 5 times.

[0080] Step 2: Using filter paper with a pore size of 0.8 μm, the product of the first step is subjected to vacuum-assisted fluid-guided self-assembly to form a lower composite protective film;

[0081] Step 3: Based on the second step, 100 mL of 0.1 mg / mL MXene aqueous solution is poured onto the top of the lower composite protective film to self-assemble into a middle high-efficiency electromagnetic shielding layer;

[0082] Step 4: Based on the third step, prepare another portion of the mixed suspension from the first step and pour it onto the top of the high-efficiency electromagnetic shielding layer film to self-assemble into an upper composite protective film to obtain the target product, the electromagnetic shielding composite film.

[0083] Example 8:

[0084] A method for preparing a high-performance, long-life, two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film, the specific steps of which are as follows:

[0085] Step 1: Dissolve 50 mg of V2O5 nanowires, 30 mg of graphene oxide, and 3 mg of latex in 50 mL of ultrapure water while stirring continuously. After stirring evenly, sonicate the mixed aqueous solution for 5 minutes, then let it stand for 10 minutes. Repeat the sonication and standing steps 5 times.

[0086] Step 2: Using filter paper with a pore size of 0.8 μm, the product of the first step is subjected to vacuum-assisted fluid-guided self-assembly to form a lower composite protective film;

[0087] Step 3: Based on the second step, 200 mL of 0.1 mg / mL MXene aqueous solution was poured onto the top of the lower composite protective film to self-assemble into a middle high-efficiency electromagnetic shielding layer;

[0088] Step 4: Based on the third step, prepare another portion of the mixed suspension from the first step and pour it onto the top of the high-efficiency electromagnetic shielding layer film to self-assemble into an upper composite protective film to obtain the target product, the electromagnetic shielding composite film.

[0089] Example 9:

[0090] A method for preparing a high-performance, long-life, two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film, the specific steps of which are as follows:

[0091] Step 1: Dissolve 50 mg of TiO2 nanowires, 20 mg of graphene oxide, and 4 mg of latex in 50 mL of ultrapure water while stirring continuously. After stirring evenly, ultrasonicate the mixed aqueous solution for 5 minutes, then let it stand for 10 minutes. Repeat the ultrasonication and standing steps 5 times.

[0092] Step 2: Using filter paper with a pore size of 0.8 μm, the product of the first step is subjected to vacuum-assisted fluid-guided self-assembly to form a lower composite protective film;

[0093] Step 3: Based on the second step, 100 mL of 0.5 mg / mL MXene aqueous solution is poured onto the top of the lower composite protective film to self-assemble into a middle high-efficiency electromagnetic shielding layer;

[0094] Step 4: Based on the third step, prepare another portion of the mixed suspension from the first step and pour it onto the top of the high-efficiency electromagnetic shielding layer film to self-assemble into an upper composite protective film to obtain the target product, the electromagnetic shielding composite film.

[0095] Example 10:

[0096] A method for preparing a high-performance, long-life, two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film, the specific steps of which are as follows:

[0097] Step 1: Dissolve 50 mg of TiO2 nanowires, 10 mg of graphene oxide, and 3 mg of latex in 50 mL of ultrapure water while stirring continuously. After stirring evenly, ultrasonicate the mixed aqueous solution for 5 minutes, then let it stand for 10 minutes. Repeat the ultrasonication and standing steps 5 times.

[0098] Step 2: Using filter paper with a pore size of 0.8 μm, the product of the first step is subjected to vacuum-assisted fluid-guided self-assembly to form a lower composite protective film;

[0099] Step 3: Based on the second step, 60 mL of 0.8 mg / mL MXene aqueous solution is poured onto the top of the lower composite protective film to self-assemble into a middle high-efficiency electromagnetic shielding layer;

[0100] Step 4: Based on the third step, prepare another portion of the mixed suspension from the first step and pour it onto the top of the high-efficiency electromagnetic shielding layer film to self-assemble into an upper composite protective film to obtain the target product, the electromagnetic shielding composite film.

[0101] Example 11:

[0102] A method for preparing a high-performance, long-life, two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film, the specific steps of which are as follows:

[0103] Step 1: Dissolve 40 mg of SiC nanowires, 20 mg of graphene oxide, and 2 mg of polyaniline in 50 mL of ultrapure water while stirring continuously. After stirring evenly, ultrasonicate the mixed aqueous solution for 5 minutes, then let it stand for 10 minutes. Repeat the ultrasonication and standing steps 5 times.

[0104] Step 2: Using filter paper with a pore size of 0.8 μm, the product of the first step is subjected to vacuum-assisted fluid-guided self-assembly to form a lower composite protective film;

[0105] Step 3: Based on the second step, 40 mL of 0.6 mg / mL MXene aqueous solution is poured onto the top of the lower composite protective film to self-assemble into a middle high-efficiency electromagnetic shielding layer;

[0106] Step 4: Based on the third step, prepare another portion of the mixed suspension from the first step and pour it onto the top of the high-efficiency electromagnetic shielding layer film to self-assemble into an upper composite protective film to obtain the target product, the electromagnetic shielding composite film.

[0107] The above is only a preferred embodiment of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A method for preparing a high-performance, long-life, two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film, characterized in that: The specific steps are as follows: Step 1: Weigh one-dimensional nanowires, graphene oxide, and an organic reinforcing agent and dissolve them in 50 mL of ultrapure water while stirring continuously. After stirring evenly, ultrasonically treat the mixed aqueous solution for 5 minutes, then let it stand for 10 minutes, and repeat the ultrasonic and standing steps 5 times to prepare a mixed suspension solution. The one-dimensional nanowires are one or more of MnO2, TiO2, SiO2, V2O5, Al2O3, SiC, and SiN nanowires, and the organic reinforcing agent is latex, polyaniline, or bacterial cellulose. Step 2: vacuum-assisted fluid-guided self-assembly of the mixed suspension solution in the first step into a lower composite protective film; Step 3: Based on the second step, pour the MXene aqueous solution onto the top of the lower composite protective film to self-assemble into a middle high-efficiency electromagnetic shielding layer film; Step 4: Based on the third step, prepare another portion of the mixed suspension from the first step and pour it on top of the middle high-efficiency electromagnetic shielding layer film, and self-assemble into an upper composite protective film to obtain the target product, a high-efficiency, long-life two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film.

2. The method for preparing a high-performance, long-life, two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film according to claim 1, characterized in that: The thickness of the high-performance, long-life two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film is 50 μm-500 μm.

3. The method for preparing a high-performance, long-life, two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film according to claim 1, characterized in that: The mass fraction ratio of the one-dimensional nanowire, graphene oxide and organic reinforcing agent in the first step is 80-40:40-10:20-0.

4. The method for preparing a high-performance, long-life, two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film according to claim 1, characterized in that: In the first step, one-dimensional nanowires, graphene oxide and organic reinforcing agent are dissolved in 50 mL of ultrapure water and mixed evenly by magnetic stirring at room temperature for 2-6 hours.

5. The method for preparing a high-performance, long-life, two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film according to claim 1, characterized in that: The concentration of the MXene aqueous solution in the third step is 0.1-1 mg·mL -1 .

6. The method for preparing a high-performance, long-life, two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film according to claim 1, characterized in that: The membrane forming processes in the second, third and fourth steps utilize vacuum-assisted fluid-guided self-assembly, and the pore size of the filter membrane used in the vacuum-assisted fluid-guided self-assembly process is 0.2-0.8 μm.

7. The method for preparing a high-performance, long-life, two-dimensional nanostructured multi-layer stable electromagnetic shielding composite film according to claim 1, characterized in that: The one-dimensional nanowire has a diameter of 20 nm-50 nm and a length of 10 μm-30 μm.

8. Use of a high-performance, long-life, two-dimensional nanostructured, multi-layered, stable electromagnetic shielding composite film prepared by the preparation method according to any one of claims 1 to 7 in an electromagnetic shielding device.

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