Carbon-containing flexible phenolic aerogel electromagnetic shielding material and preparation method thereof

Abstract

The invention discloses a carbon-containing flexible phenolic aerogel electromagnetic shielding material and a preparation method, and relates to the field of phenolic aerogel preparation.The method comprises the steps that a phenolic compound and an aldehyde compound are subjected to a condensation reaction with hydroxyl-terminated polydimethylsiloxane under the catalysis of sodium hydroxide, and the carbon-containing flexible phenolic aerogel electromagnetic shielding material is obtained; and then compounding with graphite, carbon nanotubes, graphene or fullerene to obtain the carbon-containing flexible phenolic aerogel electromagnetic shielding material. According to the preparation method, the problems of insufficient mechanical properties, complex preparation process and insufficient electromagnetic shielding performance of graphene oxide compounded phenolic aerogel are solved, the steps are simple, and the obtained carbon-containing flexible phenolic aerogel electromagnetic shielding material has the characteristics of high structural strength, low density and high electromagnetic shielding performance.

Description

Technical Field

[0001] The present invention relates to the field of preparation of phenolic aerogels, and particularly to a carbon-containing flexible phenolic aerogel electromagnetic shielding material and a preparation method thereof. Background Art

[0002] With the increasing popularity of 5G communication technology and portable electronic devices in recent years, while bringing people an unprecedented high-speed and low-latency wireless communication experience, the electromagnetic waves generated by their radiation have also caused increasingly serious electromagnetic pollution. These electromagnetic pollutions not only affect the operation of other precision electronic devices, but some also pose certain hazards to human health. Some studies have shown that long-term electromagnetic radiation will have an adverse impact on the human central nervous system, such as causing symptoms like headache, nausea, insomnia, anxiety, and palpitation. Long-term and excessive electromagnetic radiation may even cause a series of diseases such as reproductive system damage, Alzheimer's disease, and cancer.

[0003] Therefore, designing and preparing an efficient and lightweight electromagnetic shielding functional material has gradually become a hot topic in recent years. Currently, traditional electromagnetic shielding functional materials on the market include metals, alloy materials, and conductive polymers, etc. Among them, metals and alloy materials have defects such as high density, high rigidity, difficult processing, and poor corrosion resistance; the conductivity of conductive polymers is not high, and their processing technology is not yet perfect. Compared with the above materials, aerogels have the characteristics of light weight, high porosity, and easy processing, and are expected to become a new carrier for electromagnetic shielding functional materials.

[0004] In the aerogel family, phenolic aerogels are widely used in various fields due to their high specific surface area, low density, and good thermal stability. However, pure phenolic aerogels have relatively high brittleness and are easy to break, especially prone to structural collapse when compressed or impacted, which limits their application in flexible or load-bearing scenarios. And pure phenolic aerogels are insulators with extremely low conductivity, making it difficult for them to be applied in the fields of electromagnetic shielding and sensors.

[0005] Currently, the above defects of phenolic aerogels are mainly improved by a composite method, and the main material is graphene oxide. Graphene oxide composite phenolic aerogel is prepared by adding graphene oxide to phenolic sol and going through steps such as gelation, aging, solvent replacement, and autoclave treatment. This composite material combines the excellent thermal stability of phenolic aerogel and the high conductivity of graphene oxide, but there are problems of insufficient mechanical properties, complex preparation process, and insufficient electromagnetic shielding performance. When graphene oxide is dispersed in phenolic sol, it is not easy to be dispersed evenly, and the interfacial binding force is insufficient, which is not conducive to the improvement of electromagnetic shielding performance and mechanical properties. Summary of the Invention

[0006] In view of the problems existing in the prior art, the present invention provides a carbon-containing flexible phenolic aerogel electromagnetic shielding material and a preparation method thereof, so as to solve the problems of insufficient mechanical properties, complex preparation process and insufficient electromagnetic shielding performance of the phenolic aerogel compounded with graphene oxide. The steps are simple, and the obtained carbon-containing flexible phenolic aerogel electromagnetic shielding material has the characteristics of high structural strength, low density and high electromagnetic shielding performance.

[0007] The present invention is realized through the following technical solutions: A preparation method of a carbon-containing flexible phenolic aerogel electromagnetic shielding material, in which a phenolic compound and an aldehyde compound are subjected to a condensation reaction with hydroxyl-terminated polydimethylsiloxane under the catalysis of sodium hydroxide, and then are compounded with graphite, carbon nanotubes, graphene or fullerenes to obtain a carbon-containing flexible phenolic aerogel electromagnetic shielding material.

[0008] Preferably, it includes the following steps: S1, Mix a phenolic compound, an aldehyde compound, an aqueous sodium hydroxide solution and hydroxyl-terminated polydimethylsiloxane. The molar ratio of the phenolic compound, the aldehyde compound to the hydroxyl-terminated polydimethylsiloxane is: (0.2~2):(0.5~4):(1~6). Then add graphite, carbon nanotubes, graphene or fullerenes, and then add a nonionic surfactant and disperse evenly to obtain a gel emulsion; S2, Place the gel emulsion at room temperature for 3.5~4.5 h to obtain a solid product, and then remove the impurities on the surface of the solid product and dry it to obtain the carbon-containing flexible phenolic aerogel electromagnetic shielding material.

[0009] Preferably, the phenolic compound in S1 is phenol, o-cresol, m-cresol, p-cresol, resorcinol, p-tert-butylphenol, nonylphenol, xylenol or phenylphenol.

[0010] Preferably, the aldehyde compound in S1 is formaldehyde, paraformaldehyde, furfural, acetaldehyde, benzaldehyde, glyoxal, butyraldehyde or glutaraldehyde.

[0011] Preferably, the nonionic surfactant in S1 is Tween 20, Tween 40, Tween 80, lauryl alcohol polyoxyethylene ether, octylphenol polyoxyethylene ether, polyoxyethylene stearate, glycerol monostearate, Span 20, Span 80, coconut oil diethanolamide or ethoxylated amine.

[0012] Preferably, the molar ratio of the nonionic surfactant to the phenolic compound in S1 is: (0.2~2):(0.2~2).

[0013] Preferably, the concentration of the sodium hydroxide aqueous solution in S1 is 1 to 1.5 mol / L, and the molar ratio of sodium hydroxide to the phenolic compound in the sodium hydroxide aqueous solution is (0.2 to 2):(0.5 to 1).

[0014] Preferably, the graphite, carbon nanotubes, graphene or fullerenes in S1 account for 0.5% to 5% of the total mass of the gel emulsion.

[0015] Preferably, in S2, the solid product is rinsed with deionized water and then vacuum dried at 55 to 65 °C for 1.5 to 2.5 h to obtain the carbon-containing flexible phenolic aerogel electromagnetic shielding material.

[0016] A carbon-containing flexible phenolic aerogel electromagnetic shielding material is prepared based on the preparation method of any one of the above carbon-containing flexible phenolic aerogel electromagnetic shielding materials.

[0017] Compared with the prior art, the present invention has the following beneficial technical effects: In the preparation method of the carbon-containing flexible phenolic aerogel electromagnetic shielding material of the present invention, under the catalysis of sodium hydroxide, the phenolic compound and the aldehyde compound undergo a condensation reaction, and the Si-O bond of polydimethylsiloxane is grafted onto the side chain of the phenolic benzene ring, further promoting the cross-linking of the gel network and promoting the cross-linking process to form an aerogel; when compounded with carbon-based materials such as graphite, carbon nanotubes, graphene or fullerenes, which are spherical particles, when the amount of the added carbon-based materials is small, they will be wrapped by the phenolic aerogel to form smooth-surfaced stacked particles; as the content of the carbon-based materials increases, the spherical particles will be closely arranged, filling the gaps between the composite flexible phenolic aerogels, and their corresponding surface layers are connected into a coated wrinkled plane, which can not only improve the mechanical properties of the aerogel, increase the conductivity, but also endow the aerogel with excellent electromagnetic shielding performance. Different from the traditional metal and alloy electromagnetic shielding materials with large density, large rigidity, difficult processing and poor corrosion resistance, the carbon-based composite flexible phenolic aerogel electromagnetic shielding material has the characteristics of light weight, high porosity, easy processing and excellent electromagnetic shielding performance, and has broad potential in practical applications. The synthesis process of the present invention is simple, energy-consuming is small, and the performance is excellent. The carbon-based material is compounded with the phenolic aerogel to improve the problems of high brittleness and poor conductivity. Because the phenolic aerogel material is cross-linked by high molecular polymers and has high reaction activity, it is widely used as a support material to improve the matrix strength. Interacting with the carbon-based material to construct a tightly cross-linked polymer network structure to prepare a carbon-based composite aerogel material with high mechanical properties, good conductivity and high electromagnetic shielding performance. Description of the Drawings

[0018] Figure 1 It is a macroscopic photograph of the carbon-based composite flexible phenolic aerogel emulsion prepared in Example 1.

[0019] Figure 2 Microscopic morphology photograph of the carbon-based composite flexible phenolic aerogel electromagnetic shielding material prepared in Example 1.

[0020] Figure 3 Microscopic morphology photograph of the carbon-based composite flexible phenolic aerogel electromagnetic shielding material prepared in Example 2.

[0021] Figure 4 Stress-strain diagram of the carbon-based composite flexible phenolic aerogel electromagnetic shielding material prepared in Example 1 after multiple compression cycles.

[0022] Figure 5 Total shielding effectiveness of the carbon-based composite flexible phenolic aerogel electromagnetic shielding materials prepared in Examples 1-4 against electromagnetic waves. Specific embodiments

[0023] In order to enable those skilled in the art to better understand the solution of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0024] A preparation method of a carbon-containing flexible phenolic aerogel electromagnetic shielding material of the present invention includes the following steps: 1) Prepare a gel emulsion system: Add a certain mass of phenolic compounds and aldehyde compounds into a sample bottle, add 1-1.5 mol / L sodium hydroxide aqueous solution (as a catalyst) and hydroxyl-terminated polydimethylsiloxane, and mix well by shaking at room temperature. Weigh and add a carbon-based material thereto, add a non-ionic surfactant and disperse evenly by ultrasonic treatment. Under the action of the non-ionic surfactant, a thin film is formed on the particle surface, and the aggregation between particles is prevented through steric hindrance effect, making the particles more evenly dispersed in the liquid; at the same time, the contact angle with the particle surface is reduced, making it easier to wet the particle surface, which helps to better penetrate into the gaps between particles, thereby improving the dispersion effect, and obtaining a dark brown gel emulsion; 2) Prepare a carbon-based composite flexible phenolic aerogel electromagnetic shielding material: Place the gel emulsion prepared in step 1) at room temperature for 3.5-4.5 h, and a polycondensation reaction occurs between the phenolic compounds, aldehyde compounds and hydroxyl-terminated polydimethylsiloxane. The reaction conditions are mild, further promoting the cross-linking of the gel network. Taking resorcinol and furfural as examples, the reaction equation is as follows:

[0025] After rinsing with deionized water and vacuum drying at 60 °C for 2 h, a carbon-based composite flexible phenolic aerogel electromagnetic shielding material was finally obtained; 3) The carbon-based composite flexible phenolic aerogel material is applied to the field of electromagnetic shielding: The carbon-based composite flexible phenolic aerogel electromagnetic shielding material prepared in step 2) was cut into small pieces of 22.9 mm × 10.2 mm × 3.0 mm and fixed to an electrochemical workstation to test the electromagnetic shielding performance of the aerogel.

[0026] The phenolic compounds described in step 1) are: phenol, o-cresol, m-cresol, p-cresol, resorcinol, p-tert-butylphenol, nonylphenol, xylenol, phenylphenol, and the aldehyde compounds are: formaldehyde, paraformaldehyde, furfural, acetaldehyde, benzaldehyde, glyoxal, butyraldehyde, glutaraldehyde. The molar ratio of the phenolic compound, aldehyde compound, hydroxyl-terminated polydimethylsiloxane, sodium hydroxide, and nonionic surfactant is: (0.2~2):(0.5~4):(1~6):(0.5~1):(0.2~2).

[0027] The carbon-based material described in step 1) is graphite, carbon nanotubes, graphene, fullerenes, and the carbon-based material accounts for 0.5%~5% (i.e., mass fraction) of the total mass of the gel emulsion.

[0028] The surfactants described in step 1) are: Tween 20, Tween 40, Tween 80, lauryl alcohol polyoxyethylene ether, octylphenol polyoxyethylene ether, polyoxyethylene stearate, glycerol monostearate, Span 20, Span 80, coconut diethanolamide, ethoxylated amine.

[0029] Example 1 1) Preparation of a gel emulsion system: 1 mmol of resorcinol and 2 mmol of furfural were added to a sample bottle, 0.5 mL of an aqueous sodium hydroxide solution with a concentration of 1.25 mol / L and 5 mmol of hydroxyl-terminated polydimethylsiloxane were added, and the mixture was shaken and mixed evenly at room temperature. 0.5% by mass of graphite powder was weighed, and after adding 1 mmol of the surfactant Tween 40, it was ultrasonically dispersed evenly to obtain a black-brown gel emulsion; 2) Preparation of a carbon-based composite flexible phenolic aerogel electromagnetic shielding material: The gel emulsion prepared in step 1) was placed at room temperature for 4 h, and a polycondensation reaction occurred between the raw materials to further stabilize the gel network. After rinsing with deionized water and vacuum drying at 60 °C for 2 h, a carbon-based composite flexible phenolic aerogel electromagnetic shielding material was finally obtained.

[0030] Example 2 Add 1 mmol of phenol and 3 mmol of glyoxal into a sample bottle, add 0.5 mL of sodium hydroxide aqueous solution with a concentration of 1.25 mol / L and 3 mmol of hydroxyl-terminated polydimethylsiloxane, and mix well by shaking at room temperature. Weigh graphite powder with a mass fraction of 1.5%, add 1 mmol of surfactant lauryl alcohol polyoxyethylene ether, and then disperse it evenly by ultrasonic treatment to obtain a black-brown gel emulsion. Other steps are the same as those in Example 1 to prepare a carbon-based composite flexible phenolic aerogel electromagnetic shielding material.

[0031] Example 3 Add 2 mmol of xylenol and 4 mmol of glutaraldehyde into a sample bottle, add 0.5 mL of sodium hydroxide aqueous solution with a concentration of 1.25 mol / L and 6 mmol of hydroxyl-terminated polydimethylsiloxane, and mix well by shaking at room temperature. Weigh carbon nanotubes with a mass fraction of 1.5%, add 1 mmol of surfactant Tween 80, and then disperse it evenly by ultrasonic treatment to obtain a black-brown gel emulsion. Other steps are the same as those in Example 1 to prepare a carbon-based composite flexible phenolic aerogel electromagnetic shielding material.

[0032] Example 4 Add 1 mmol of p-tert-butylphenol and 0.5 mmol of formaldehyde into a sample bottle, add 0.5 mL of sodium hydroxide aqueous solution with a concentration of 1.25 mol / L and 4 mmol of hydroxyl-terminated polydimethylsiloxane, and mix well by shaking at room temperature. Weigh graphene with a mass fraction of 1.5%, add 1 mmol of surfactant polyethylene glycol stearate, and then disperse it evenly by ultrasonic treatment to obtain a black-brown gel emulsion. Other steps are the same as those in Example 1 to prepare a carbon-based composite flexible phenolic aerogel electromagnetic shielding material.

[0033] Example 5 Add 2 mmol of phenylphenol and 2 mmol of butyraldehyde into a sample bottle, add 0.5 mL of sodium hydroxide aqueous solution with a concentration of 1.25 mol / L and 2 mmol of hydroxyl-terminated polydimethylsiloxane, and mix well by shaking at room temperature. Weigh graphite powder with a mass fraction of 2%, add 1 mmol of surfactant Span 80, and then disperse it evenly by ultrasonic treatment to obtain a black-brown gel emulsion. Other steps are the same as those in Example 1 to prepare a carbon-based composite flexible phenolic aerogel electromagnetic shielding material.

[0034] Example 6 Add 2 mmol of phenylphenol and 1 mmol of butyraldehyde into a sample bottle, add 0.5 mL of an aqueous sodium hydroxide solution with a concentration of 1.25 mol / L and 5 mmol of hydroxyl-terminated polydimethylsiloxane, and mix well by shaking at room temperature. Weigh graphite powder with a mass fraction of 3%, add 1 mmol of surfactant ethoxylated amine, and then disperse it evenly by ultrasonic treatment to obtain a black-brown gel emulsion. The other steps are the same as those in Example 1 to prepare a carbon-based composite flexible phenolic aerogel electromagnetic shielding material.

[0035] Example 7 Add 2 mmol of phenylphenol and 2 mmol of furfural into a sample bottle, add 0.5 mL of an aqueous sodium hydroxide solution with a concentration of 1.25 mol / L and 4 mmol of hydroxyl-terminated polydimethylsiloxane, and mix well by shaking at room temperature. Weigh carbon nanotubes with a mass fraction of 1.5%, add 1 mmol of surfactant Span 20, and then disperse it evenly by ultrasonic treatment to obtain a black-brown gel emulsion. The other steps are the same as those in Example 1 to prepare a carbon-based composite flexible phenolic aerogel electromagnetic shielding material.

[0036] Example 8 Add 2 mmol of xylenol and 4 mmol of furfural into a sample bottle, add 0.5 mL of an aqueous sodium hydroxide solution with a concentration of 1.25 mol / L and 6 mmol of hydroxyl-terminated polydimethylsiloxane, and mix well by shaking at room temperature. Weigh carbon nanotubes with a mass fraction of 3%, add 1 mmol of surfactant Tween 20, and then disperse it evenly by ultrasonic treatment to obtain a black-brown gel emulsion. The other steps are the same as those in Example 1 to prepare a carbon-based composite flexible phenolic aerogel electromagnetic shielding material.

[0037] Example 9 Add 2 mmol of xylenol and 4 mmol of glyoxal into a sample bottle, add 0.5 mL of an aqueous sodium hydroxide solution with a concentration of 1.25 mol / L and 4 mmol of hydroxyl-terminated polydimethylsiloxane, and mix well by shaking at room temperature. Weigh graphene with a mass fraction of 3%, add 1 mmol of surfactant Tween 80, and then disperse it evenly by ultrasonic treatment to obtain a black-brown gel emulsion. The other steps are the same as those in Example 1 to prepare a carbon-based composite flexible phenolic aerogel electromagnetic shielding material.

[0038] Example 10 2 mmol of xylenol and 4 mmol of paraformaldehyde were added to a sample bottle, and 0.5 mL of an aqueous sodium hydroxide solution with a concentration of 1.25 mol / L and 4 mmol of hydroxyl-terminated polydimethylsiloxane were added, and the mixture was shaken and mixed evenly at room temperature. 3% by mass of graphene was weighed, and 1 mmol of surfactant Tween 80 was added and then ultrasonically dispersed evenly to obtain a black-brown gel emulsion. The other steps were the same as those in Example 1 to prepare a carbon-based composite flexible phenolic aerogel electromagnetic shielding material.

[0039] See Figure 1 , Figure 1 Figure 7 is a macroscopic photograph of the carbon-based composite flexible phenolic aerogel emulsion prepared in Example 1. It can be seen from the figure that the prepared gel emulsion does not flow when tilted, is uniformly stable as a whole, and has a black-brown appearance.

[0040] Figure 2 and Figure 3 Figures 13 and 14 are respectively the microscopic morphology photographs of the carbon-based composite flexible phenolic aerogel electromagnetic shielding materials prepared in Example 1 and Example 2. The microscopic structure was observed using a FEI Verios 460 high-resolution field emission scanning electron microscope. The surface of the sample needs to be sputter-coated with gold before testing. The acceleration voltage of the SEM test was 20 kV, and the emission current was 100 μA. It can be seen from Figures 13 and 14 that when the content of the carbon-based material added is small, it will be wrapped by the phenolic aerogel to form smooth stacked particles on the surface; but as the content of the carbon-based material increases, the spherical particles are closely arranged, filling the gaps between the composite flexible phenolic aerogels, and their corresponding surface layers are connected into a covered wrinkled plane. Figure 2 , Figure 3 Figures 13 and 14

[0041] See Figure 4 , Figure 4 Figure 24 is the stress-strain curve of the carbon-based composite flexible phenolic aerogel electromagnetic shielding material prepared in Example 1 during compression. The compression cycle performance of the carbon-based composite flexible phenolic aerogel electromagnetic shielding material prepared in Example 1 was tested using an AI-7000-NGD servo material multi-functional high and low temperature control testing machine. It can be seen from the figure that the compression strength of the block material is 90 KPa when the strain is nearly 30%, and after squeezing and recovering 5 times, the macroscopic structure of the block material is basically not damaged, and it can basically recover relative to the original height, and the cyclic attenuation is less than 8%.

[0042] See Figure 5 , Figure 5For the total electromagnetic shielding effectiveness of the carbon-based composite flexible phenolic aerogel electromagnetic shielding materials prepared in Examples 1-4, the prepared carbon-based composite flexible phenolic aerogel electromagnetic shielding materials were cut into small pieces of 22.9 mm×10.2mm×3 mm, fixed to an electrochemical workstation, and an electromagnetic shielding test was carried out on the carbon-based composite flexible phenolic aerogel electromagnetic shielding material samples using a vector network analyzer. Eight parameters, namely the intensities and phase parameters of S11, S21, S12, and S22, generated after the reflection and transmission of the electrical signal by the sample, were obtained using the waveguide method. The absorption loss (SEA) and reflection loss (SER) of the material calculated by the HFSS method were used to finally calculate the total shielding effectiveness (SET). The test frequency range was 8.2-12.4 GHz, with the unit of dB. It can be seen from the figure that the total electromagnetic shielding performance of the carbon-based composite flexible phenolic aerogel electromagnetic shielding material prepared in Example 1 showed a slow increase with the increase of the electromagnetic frequency, reaching a maximum of 39.19 dB; the total electromagnetic shielding performance of the carbon-based composite flexible phenolic aerogel electromagnetic shielding material prepared in Example 2 reached a maximum of 43.94 dB; the total electromagnetic shielding performance of the carbon-based composite flexible phenolic aerogel electromagnetic shielding material prepared in Example 3 reached a maximum of 51.21 dB, with excellent electromagnetic shielding performance; the total electromagnetic shielding performance of the carbon-based composite flexible phenolic aerogel electromagnetic shielding material prepared in Example 4 reached a maximum of 48.98 dB.

[0043] The above content is only to illustrate the technical idea of the present invention and cannot be used to limit the protection scope of the present invention. Any modification made on the basis of the technical solution according to the technical idea proposed by the present invention falls within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a carbon-containing flexible phenolic aerogel electromagnetic shielding material, characterized in that: The phenolic compounds and aldehyde compounds are subjected to a condensation reaction with hydroxyl-terminated polydimethylsiloxane under the catalysis of sodium hydroxide, and then compounded with graphite, carbon nanotubes, graphene or fullerene to obtain a carbon-containing flexible phenolic aerogel electromagnetic shielding material.

2. The method for preparing the carbon-containing flexible phenolic aerogel electromagnetic shielding material according to claim 1, characterized in that: The following steps are involved: S1, mixing a phenolic compound, an aldehyde compound, a sodium hydroxide aqueous solution and a hydroxyl-terminated polydimethylsiloxane, wherein the molar ratio of the phenolic compound, the aldehyde compound and the hydroxyl-terminated polydimethylsiloxane is: (0.2-2): (0.5-4): (1-6), then adding graphite, carbon nanotubes, graphene or fullerene, and then adding a non-ionic surfactant to disperse uniformly to obtain a gel emulsion; S2, placing the gel emulsion at room temperature for 3.5 to 4.5 hours to obtain a solid product, then removing impurities on the surface of the solid product and drying it to obtain the carbon-containing flexible phenolic aerogel electromagnetic shielding material.

3. The method for preparing the carbon-containing flexible phenolic aerogel electromagnetic shielding material according to claim 2, characterized in that: The phenolic compound described in S1 is phenol, o-cresol, m-cresol, p-cresol, resorcinol, p-tert-butylphenol, nonylphenol, xylenol or phenylphenol.

4. The method for preparing the carbon-containing flexible phenolic aerogel electromagnetic shielding material according to claim 2, characterized in that: The aldehyde compound described in S1 is formaldehyde, paraformaldehyde, furfural, acetaldehyde, benzaldehyde, glyoxal, butyraldehyde or glutaraldehyde.

5. The method for preparing the carbon-containing flexible phenolic aerogel electromagnetic shielding material according to claim 2, characterized in that: The nonionic surfactant described in S1 is Tween 20, Tween 40, Tween 80, lauryl alcohol polyoxyethylene ether, octylphenol polyoxyethylene ether, polyoxyethylene stearate, glyceryl monostearate, Span 20, Span 80, coconut oil diethanolamide or ethoxylated amine.

6. The method for preparing the carbon-containing flexible phenolic aerogel electromagnetic shielding material according to claim 5, characterized in that: The molar ratio of the nonionic surfactant to the phenolic compound in S1 is: (0.2~2): (0.2~2).

7. The method for preparing the carbon-containing flexible phenolic aerogel electromagnetic shielding material according to claim 2, characterized in that: The concentration of the sodium hydroxide aqueous solution in S1 is 1-1.5 mol / L, and the molar ratio of sodium hydroxide to phenolic compounds in the sodium hydroxide aqueous solution is: (0.2-2): (0.5-1).

8. The method for preparing the carbon-containing flexible phenolic aerogel electromagnetic shielding material according to claim 1, characterized in that: The graphite, carbon nanotubes, graphene or fullerene described in S1 accounts for 0.5% to 5% of the total mass of the gel emulsion.

9. The method for preparing the carbon-containing flexible phenolic aerogel electromagnetic shielding material according to claim 1, characterized in that: S2: washing the solid product with deionized water, and then vacuum drying it at 55-65°C for 1.5-2.5 h to obtain the carbon-containing flexible phenolic aerogel electromagnetic shielding material.

10. A carbon-containing flexible phenolic aerogel electromagnetic shielding material, characterized in that: The carbon-containing flexible phenolic aerogel electromagnetic shielding material is prepared based on the preparation method of any one of claims 1-9.

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