Preparation method of flexible polyaniline / biomass carbon electromagnetic shielding material

Abstract

The present invention discloses a method for preparing a flexible polyaniline / biomass carbon electromagnetic shielding material. After high-temperature carbonization of a fiber fabric, a structurally ordered biomass carbon matrix is ​​obtained. Under the synergistic action of an oxidant and a dopant, aniline monomer is in situ oxidatively polymerized to generate polyaniline that is adsorbed on the surface of the biomass carbon matrix, thereby obtaining the polyaniline / biomass carbon electromagnetic shielding material. The electromagnetic shielding material of the present invention has an intricate and ordered two-dimensional network structure, which helps to establish a conductive network and exhibits excellent electromagnetic shielding effectiveness. In addition, the unique flexibility can fully meet the special requirements of flexible wearable electronic devices, electromagnetic shielding clothing fillers, etc. for the performance of electromagnetic shielding materials. The synthesis process of this method is safe and environmentally friendly, and the required consumables are cheap and abundant, making it suitable for commercialization and industrialization requirements.

Description

Technical Field

[0001] The invention relates to the technical field of composite wave-absorbing materials, in particular to a method for preparing a flexible polyaniline / biomass carbon electromagnetic shielding material. Background Art

[0002] With the rapid development of information technology, electromagnetic radiation pollution is becoming increasingly serious. Electromagnetic shielding technology is an effective way to protect precision instruments and components from electromagnetic radiation pollution and signal interference. The widespread application of flexible wearable technology places increasingly stringent demands on the comprehensive performance of electromagnetic shielding materials. Research and development of flexible and multifunctional electromagnetic shielding materials with high performance is urgent. Existing electromagnetic shielding materials suffer from numerous issues, including high density, limited functionality, low shielding effectiveness, and expensive raw materials.

[0003] Chinese patent CN201611125165.7 (CN106589360B) discloses a method for preparing a core-shell sugarcane fiber-doped polyaniline electromagnetic shielding material. This electromagnetic shielding material uses sugarcane fiber as the core and polyaniline as the shell. The material's overall electromagnetic shielding performance is adjusted by varying the size of the sugarcane fiber and the type of oxidant. The resulting electromagnetic shielding material exhibits high shielding effectiveness and a wide shielding range. Chinese patent 202210969543.9 (CN115386337A) discloses a method for preparing a chiral polyaniline / biomass-derived porous carbon composite absorbing material. This method uses biomass, such as peanut shells, as the carbon source. The absorbing material is prepared through high-temperature carbonization and in-situ oxidative polymerization. This method features a simple synthesis process, abundant material resources, and environmental friendliness. However, the above-mentioned electromagnetic functional materials are all in powder form, do not have the characteristics of macroscopic structural continuity, flexibility and order, and are difficult to distribute evenly and orderly in practical applications, which affects the final electromagnetic shielding or absorption performance. Therefore, it is difficult to meet the development needs of flexible wearable electronic components, electromagnetic shielding clothing fillings, etc. for special performance of electromagnetic shielding materials.

[0004] Chinese patent CN201610537259.9 (CN106183211B) discloses the preparation and application of an electromagnetic shielding fabric. This electromagnetic shielding fabric is formed by bonding and curing a carbon nanotube / graphene composite film, a polyaniline film, and a base fabric in a certain order using an adhesive. It exhibits excellent electromagnetic shielding performance and is breathable, flexible, and foldable. However, the electromagnetic shielding fabric uses an expensive and complex carbon source during its preparation, which, to a certain extent, restricts the commercialization and industrialization of this material. Furthermore, the carbon nanotubes and graphene easily agglomerate, thus affecting its electromagnetic shielding performance. Summary of the Invention

[0005] The purpose of the present invention is to solve the problem that electromagnetic shielding materials in the prior art lack flexible functional properties or have poor flexibility and are not wearable, and to provide a method for preparing a flexible polyaniline / biomass carbon electromagnetic shielding material that is inexpensive and easy to industrialize.

[0006] In order to solve the above-mentioned technical problems, the present invention adopts a technical solution: a method for preparing a flexible polyaniline / biomass carbon electromagnetic shielding material, which specifically comprises the following steps:

[0007] S1: After the fiber fabric is washed, filtered and dried, a clean fiber fabric is obtained and set aside;

[0008] S2: pyrolyzing and carbonizing the clean fiber fabric obtained in S1 under an inert atmosphere, wherein the heating rate of the pyrolysis and carbonization process is 15-25°C / min, the calcination temperature is 1100-1200°C, the holding time is 30-60min, and then naturally cooling to room temperature to obtain a biomass carbon matrix for standby use;

[0009] S3: immersing the biomass carbon matrix prepared in S2 in an aqueous solution of a dopant containing aniline monomer and ultrasonically vibrating the matrix, followed by cooling in an ice-water bath and allowing the matrix to stand;

[0010] The mass ratio of the biomass carbon matrix to the aniline monomer is 5:1-1:20, and the volume ratio of the aniline monomer to the dopant aqueous solution is 1:50-1:500;

[0011] S4: dissolving the oxidant in the dopant aqueous solution at a molar ratio of 1:0.5 to 1:2.5 between the oxidant and the aniline monomer, slowly adding the solution dropwise to the solution prepared in S3, and then keeping the solution in an ice water bath. The polyaniline / biomass carbon electromagnetic shielding material is then obtained by filtering, washing, and freeze-drying.

[0012] As a further optimization of the preparation method of the flexible polyaniline / biomass carbon electromagnetic shielding material of the present invention: the fiber fabric in step S1 is pure cotton fabric, linen fabric or cotton and linen mixed fabric.

[0013] As a further optimization of the preparation method of the flexible polyaniline / biomass carbon electromagnetic shielding material of the present invention: the temperature of the ice water bath in steps S3 and S4 is 0-5°C.

[0014] As a further optimization of the preparation method of a flexible polyaniline / biomass carbon electromagnetic shielding material of the present invention: the dopant in steps S3 and S4 is a combined protonic acid solution formed by mixing hydrochloric acid and camphorsulfonic acid in a molar ratio of 1:1-4:1.

[0015] As a further optimization of the preparation method of the flexible polyaniline / biomass carbon electromagnetic shielding material of the present invention: the concentration of the dopant aqueous solution is 0.5-5 mol / L.

[0016] As a further optimization of the preparation method of the flexible polyaniline / biomass carbon electromagnetic shielding material of the present invention: the oxidant in step S4 is ammonium persulfate or ferric chloride.

[0017] As a further optimization of the preparation method of a flexible polyaniline / biomass carbon electromagnetic shielding material of the present invention: the dripping speed of the oxidant and dopant aqueous solution in step S4 is 0.5-10 ml / min, the solution stirring speed is 50-500 r / min, and after the dripping is completed, the reaction is allowed to stand for 5-24 hours.

[0018] A flexible polyaniline / biomass carbon electromagnetic shielding material is prepared by the above preparation method.

[0019] The present invention has the following beneficial effects:

[0020] First, the electromagnetic shielding material of the present invention can fully solve the many problems of existing electromagnetic shielding materials, such as high density, single function, low shielding effectiveness, and expensive raw materials, and meet the development needs of science and technology for the development of multifunctional electromagnetic shielding materials. A biomass carbon fabric is prepared by high-temperature carbonization of fiber fabric as a matrix, and polyaniline is generated by in-situ oxidative polymerization and adsorbed on the surface of the biomass carbon fabric, thereby preparing a flexible polyaniline / biomass carbon electromagnetic shielding material.

[0021] Second, the electromagnetic shielding material of the present invention has an intricate and orderly two-dimensional network structure, which helps to establish a conductive network and exhibits excellent electromagnetic shielding effectiveness. In addition, its unique flexibility can fully meet the special requirements of flexible wearable electronic devices for electromagnetic shielding materials. The synthesis process of this method is safe and environmentally friendly, and the consumables required are inexpensive and abundant, making it suitable for commercial and industrial applications.

[0022] 3. The electromagnetic shielding material of the present invention can use a biomass fabric with a natural helical structure chiral characteristics as a matrix, and perform a high-temperature carbonization treatment under specific conditions. The biomass carbon after carbonization perfectly inherits its chiral characteristics. Specifically, the applicant found that rapidly heating to a higher carbonization temperature at a higher heating rate can fully reduce the reactivity of the biomass and reduce the burn-out rate in a low-temperature environment, so that the carbonized biomass can perfectly inherit the chiral characteristics. The chiral superhelical structure of the biomass can exhibit special optical activity and circular dichroism, and produce a cross-polarization coupling effect under the action of an alternating electromagnetic field, thereby giving it multiple electromagnetic wave loss mechanisms. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a SEM image (200X) of the electromagnetic shielding material prepared in Example 1;

[0024] Figure 2This is a SEM image (10000X) of the electromagnetic shielding material prepared in Example 1;

[0025] Figure 3 This is a physical picture of the electromagnetic shielding material prepared in Example 1;

[0026] Figure 4 This is the Fourier infrared spectrum of the electromagnetic shielding material prepared in Example 1. DETAILED DESCRIPTION

[0027] In order to better understand the present invention, the content of the present invention is further illustrated below with reference to the examples, but the content of the present invention is not limited to the following examples.

[0028] <Method for preparing electromagnetic shielding material>

[0029] Doped polyaniline is one of the most promising conductive polymers in the field of electromagnetic shielding due to its high conductivity, stable chemical properties, simple synthesis process and low cost. Cellulose is the most abundant and cheap biomass material on earth. After reasonable carbonization and pyrolysis, the fiber fabric made from it can not only maintain the original fabric morphology with certain mechanical properties, but also form an intricate and orderly conductive fiber network when converted into biomass carbon fibers, giving it extremely high electromagnetic shielding effectiveness. In addition, its rough surface provides abundant sites for the attachment and growth of polyaniline. Therefore, it is a very feasible research and development direction to select biomass carbon fabric prepared by high-temperature carbonization of fiber fabric as the matrix, and generate polyaniline adsorbed on its surface through in-situ oxidative polymerization to prepare flexible polyaniline / biomass carbon electromagnetic shielding materials.

[0030] A method for preparing a flexible polyaniline / biomass carbon electromagnetic shielding material, comprising the following steps:

[0031] S1: The fiber fabric is washed with ethanol and deionized water multiple times, filtered, and dried for later use;

[0032] S2: pyrolyzing and carbonizing the clean fiber fabric obtained in S1 under an inert atmosphere, and then naturally cooling to room temperature to obtain a biomass carbon matrix for later use;

[0033] Specifically, the clean fiber fabric is pyrolyzed and carbonized in an inert atmosphere, the heating rate of the pyrolysis and carbonization process is 15-25° C. / min, the calcination temperature is 1100-1200° C., and the holding time is 30-60 min.

[0034] S3: Immerse the biomass carbon matrix prepared in S2 in an aqueous solution of aniline monomer and dopant and ultrasonically vibrate, then cool in an ice-water bath and allow to stand;

[0035] In step S3, the mass ratio of the biomass carbon matrix to the aniline monomer is 5:1-1:20, and the volume ratio of the aniline monomer to the dopant aqueous solution is 1:50-1:500.

[0036] S4: dissolving the oxidant in the dopant aqueous solution, slowly adding the solution dropwise to the solution prepared in S3, and keeping the solution in an ice water bath, followed by filtering, washing, and freeze-drying to obtain a polyaniline / biomass carbon electromagnetic shielding material.

[0037] Wherein, the dopant in steps S3 and S4 is a combined protonic acid solution formed by mixing hydrochloric acid and camphorsulfonic acid in a molar ratio of 1:1-4:1, and the concentration of the dopant aqueous solution is 0.5-5 mol / L.

[0038] The temperature of the ice water bath in steps S3 and S4 is 0-5°C.

[0039] In step S4, the oxidant is ammonium persulfate or ferric chloride, the molar ratio of the oxidant to the aniline monomer is 1:0.5-1:2.5, the dropwise addition rate of the oxidant and dopant aqueous solution is 0.5-10 ml / min, the solution stirring speed is 50-500 r / min, and the reaction is allowed to stand for 5-24 hours after the dropwise addition is completed.

[0040] <Example 1>

[0041] A method for preparing a flexible polyaniline / biomass carbon electromagnetic shielding material comprises the following steps:

[0042] S1: The pure cotton fabric was washed with ethanol and deionized water multiple times to remove surface impurities, filtered, and dried.

[0043] S2: The obtained pure cotton fabric is placed in a tubular furnace and pyrolyzed and carbonized under the protection of N2 atmosphere. The heating rate is 20℃ / min, the pyrolysis temperature is 1150℃, the holding time is 45min, and after naturally cooling to room temperature, the biomass carbon matrix is ​​obtained.

[0044] S3: Dissolve 0.5 ml of aniline monomer in 30 ml of a 2 mol / L combined protonic acid solution (the molar ratio of hydrochloric acid to camphorsulfonic acid is 1:1), then immerse a 20 mm × 20 mm biomass carbon matrix in the above solution, cool to 0°C in an ice-water bath, and let it stand.

[0045] S4: Weigh 1.2g of ammonium persulfate and fully dissolve it in 20ml of a 2mol / L combined protonic acid solution (the molar ratio of hydrochloric acid to camphorsulfonic acid is 1:1), then add it dropwise to the aniline monomer and biomass carbon matrix solution at a constant pressure dropping funnel at a rate of 2ml / min, and stir slowly at 120r / min throughout the process. After the addition is completed, stop stirring and place it in an ice water bath for 12 hours to react, then filter, wash, and freeze-dry to obtain a polyaniline / biomass carbon electromagnetic shielding material (SEM figure as shown in FIG). Figure 1 and 2 As shown in the actual picture Figure 3 As shown, the Fourier infrared spectrum is as follows Figure 4 shown).

[0046] Electromagnetic shielding effectiveness: The polyaniline / biomass carbon electromagnetic shielding material prepared in this example was tested and found to have an electromagnetic shielding effectiveness of approximately 37 dB in the X-band (8.2-12.4 GHz). The material can be bent freely without structural damage, demonstrating excellent flexibility.

[0047] <Example 2>

[0048] A method for preparing a flexible polyaniline / biomass carbon electromagnetic shielding material. The preparation process is basically the same as that of <Example 1>, except that the pure cotton fabric is replaced by linen fabric.

[0049] Electromagnetic shielding effectiveness: The polyaniline / biomass carbon electromagnetic shielding material prepared in this example was tested and found to have an electromagnetic shielding effectiveness of approximately 32 dB in the X-band (8.2-12.4 GHz). The material can be bent freely without structural damage, demonstrating excellent flexibility.

[0050] <Example 3>

[0051] A method for preparing a flexible polyaniline / biomass carbon electromagnetic shielding material. The preparation process is basically the same as that of <Example 1>, except that the pure cotton fabric is replaced with a cotton and linen mixed fabric (the mass ratio of cotton and linen is 1:1).

[0052] Electromagnetic shielding effectiveness: The polyaniline / biomass carbon electromagnetic shielding material prepared in this example was tested and found to have an electromagnetic shielding effectiveness of approximately 34 dB in the X-band (8.2-12.4 GHz). The material can be bent freely without structural damage, demonstrating excellent flexibility.

[0053] <Example 4>

[0054] A method for preparing a flexible polyaniline / biomass carbon electromagnetic shielding material. The preparation process is basically the same as that of <Example 1>, except that the heating temperature rise rate is adjusted to 15°C / min, the pyrolysis temperature is adjusted to 1200°C, and the holding time is adjusted to 60min.

[0055] Electromagnetic shielding effectiveness: The polyaniline / biomass carbon electromagnetic shielding material prepared in this example was tested to have an electromagnetic shielding effectiveness of approximately 35 dB in the X-band (8.2-12.4 GHz). The material can be bent freely without structural damage, demonstrating excellent flexibility.

[0056] <Example 5>

[0057] A method for preparing a flexible polyaniline / biomass carbon electromagnetic shielding material. The preparation process is basically the same as that of <Example 1>, except that the combined protonic acid in the dopant is adjusted to a molar ratio of hydrochloric acid to camphorsulfonic acid of 3:1.

[0058] Electromagnetic shielding effectiveness: The polyaniline / biomass carbon electromagnetic shielding material prepared in this example was tested to have an electromagnetic shielding effectiveness of approximately 35 dB in the X-band (8.2-12.4 GHz). The material can be bent freely without structural damage, demonstrating excellent flexibility.

[0059] <Example 6>

[0060] A method for preparing a flexible polyaniline / biomass carbon electromagnetic shielding material. The preparation process is basically the same as that of <Example 1>, except that ammonium persulfate is replaced with ferric chloride.

[0061] Electromagnetic shielding effectiveness: The polyaniline / biomass carbon electromagnetic shielding material prepared in this example was tested and found to have an electromagnetic shielding effectiveness of approximately 34 dB in the X-band (8.2-12.4 GHz). The material can be bent freely without structural damage, demonstrating excellent flexibility.

[0062] Comparative Example 1

[0063] 1) The pure cotton fabric was washed with ethanol and deionized water multiple times to remove surface impurities, filtered, and dried.

[0064] 2) The obtained pure cotton fabric is placed in a tubular furnace and pyrolyzed and carbonized under the protection of N2 atmosphere at a heating rate of 20℃ / min, a pyrolysis temperature of 1150℃, a holding time of 45min, and naturally cooled to room temperature to obtain the electromagnetic shielding material.

[0065] Electromagnetic Shielding Effectiveness: The electromagnetic shielding effectiveness of the electromagnetic shielding material prepared in this example was tested in the X-band (8.2-12.4 GHz), and its electromagnetic shielding effectiveness was approximately 22 dB. The material can be bent freely without structural damage, demonstrating good flexibility.

[0066] Comparative Example 2

[0067] 1) Dissolve 0.5 ml of aniline monomer in 30 ml of a 2 mol / L combined protonic acid solution (the molar ratio of hydrochloric acid to camphorsulfonic acid is 1:1), cool to 0°C in an ice-water bath, and allow to stand.

[0068] 2) Weigh 1.2 g of ammonium persulfate and fully dissolve it in 20 ml of a 2 mol / L combined protonic acid solution (the molar ratio of hydrochloric acid to camphorsulfonic acid is 1:1). Then, add it dropwise to the aniline monomer solution at a uniform rate of 2 ml / min through a constant pressure dropping funnel, stirring slowly at 120 r / min throughout the process. After the addition is complete, stop stirring and place the mixture in an ice water bath for 12 hours to react, then filter, wash, and freeze-dry to obtain the electromagnetic shielding material.

[0069] Electromagnetic shielding effectiveness: The electromagnetic shielding effectiveness of the electromagnetic shielding material prepared in this example was tested in the X-band (8.2-12.4 GHz), and was found to be approximately 27 dB. This material is in powder form and lacks flexibility.

[0070] Comparative Example 3

[0071] 1) The pure cotton fabric was washed with ethanol and deionized water multiple times to remove surface impurities, filtered, and dried.

[0072] 2) Dissolve 0.5 ml of aniline monomer in 30 ml of a 2 mol / L combined protonic acid solution (the molar ratio of hydrochloric acid to camphorsulfonic acid is 1:1). Then, immerse a 20 mm x 20 mm piece of pure cotton fabric in the solution, cool to 0°C in an ice-water bath, and allow to stand.

[0073] 3) Weigh 1.2 g of ammonium persulfate and fully dissolve it in 20 ml of a 2 mol / L combined protonic acid solution (the molar ratio of hydrochloric acid to camphorsulfonic acid is 1:1). Then, add it dropwise to the aniline monomer and pure cotton fabric solution at a constant pressure dropping funnel at a rate of 2 ml / min, stirring slowly at 120 r / min throughout the process. After the addition is completed, stirring is stopped and the mixture is placed in an ice water bath for reaction for 12 hours, filtered, washed, and freeze-dried to obtain the electromagnetic shielding material.

[0074] Electromagnetic Shielding Effectiveness: The electromagnetic shielding effectiveness of the electromagnetic shielding material prepared in this example was tested in the X-band (8.2-12.4 GHz), and its electromagnetic shielding effectiveness was approximately 24 dB. The material can be bent freely without structural damage, demonstrating good flexibility.

[0075] Comparative Example 1 shows that the biomass carbon matrix obtained by pyrolysis and carbonization of pure cotton fabric is not polymerized and coated with doped polyaniline, and the shielding effectiveness of the electromagnetic shielding material finally obtained is significantly reduced. Comparative Example 2 shows that the doped polyaniline prepared by oxidative polymerization is not attached to the biomass carbon matrix, but exists in a powder state, not only losing its flexibility, but also significantly reducing its shielding effectiveness. Comparative Example 3 shows that the shielding effectiveness of the electromagnetic shielding material finally obtained by directly polymerizing and coating the doped polyaniline without pyrolysis and carbonization of pure cotton fabric is not significantly reduced, but its shielding effectiveness is inferior to the polyaniline / biomass carbon electromagnetic shielding material prepared in Example 1. This shows that: the pyrolysis and carbonization of pure cotton fabric into a biomass carbon matrix can form an intricate and orderly two-dimensional conductive network, enhance the conductivity of the material, and thus help improve its shielding effectiveness. The doped polyaniline is uniformly and attached to the surface of the biomass carbon matrix. Under the synergistic effect of polyaniline and the biomass carbon matrix, the polyaniline / biomass carbon electromagnetic shielding material obtained exhibits excellent electromagnetic shielding effectiveness. In addition. Its unique flexibility can fully meet the special requirements of flexible wearable electronic devices for electromagnetic shielding materials.

[0076] Comparative Example 4

[0077] A method for preparing a flexible polyaniline / biomass carbon electromagnetic shielding material. The preparation process is basically the same as that of <Example 1>, except that the heating rate is adjusted to 5°C / min.

[0078] Electromagnetic shielding effectiveness: The polyaniline / biomass carbon electromagnetic shielding material prepared in this example was tested and found to have an electromagnetic shielding effectiveness of approximately 32 dB in the X-band (8.2-12.4 GHz). The material can be bent freely without structural damage, demonstrating excellent flexibility.

[0079] Comparative Example 5

[0080] A method for preparing a flexible polyaniline / biomass carbon electromagnetic shielding material. The preparation process is basically the same as that of <Example 1>, except that the carbonization temperature is adjusted to 800°C.

[0081] Electromagnetic shielding effectiveness: The polyaniline / biomass carbon electromagnetic shielding material prepared in this example was tested and found to have an electromagnetic shielding effectiveness of approximately 30 dB in the X-band (8.2-12.4 GHz). The material can be bent freely without structural damage, demonstrating excellent flexibility.

[0082] It can be seen from Comparative Examples 4 and 5 that when the high-temperature carbonization treatment is performed, the carbonization treatment is not performed according to the heating rate specified in the present invention or the carbonization temperature specified in the present invention. The electromagnetic shielding effectiveness of the electromagnetic shielding material finally obtained is lower than that of Example 1, and the absorbing performance of the absorbing material in Comparative Example 4 is better than that of Comparative Document 5. It can be seen that the influence of the carbonization temperature on the electromagnetic shielding effectiveness of the final electromagnetic shielding material is greater than the influence of the heating rate on the electromagnetic shielding effectiveness of the final electromagnetic shielding material.

[0083] It can be seen from this that: the present invention carbonizes the biomass fabric with natural helical structure chiral characteristics under specific conditions. The biomass carbon after carbonization perfectly inherits its chiral characteristics, and is quickly heated to a higher carbonization temperature at a higher heating rate, which can fully reduce the reactivity of the biomass and reduce the burn-loss rate in a low-temperature environment, so that the carbonized biomass can perfectly inherit the chiral characteristics.

[0084] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various variations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for preparing a flexible polyaniline / biomass carbon electromagnetic shielding material, characterized by: The specific steps include: S1: After the fiber fabric is washed, filtered and dried, a clean fiber fabric is obtained and set aside; The fiber fabric is pure cotton fabric, linen fabric or cotton and linen mixed fabric; S2: pyrolyzing and carbonizing the clean fiber fabric obtained in S1 under an inert atmosphere, wherein the heating rate of the pyrolysis and carbonization process is 15-25°C / min, the calcination temperature is 1100-1200°C, the holding time is 30-60min, and then naturally cooling to room temperature to obtain a biomass carbon matrix for standby use; S3: immersing the biomass carbon matrix prepared in S2 in an aqueous solution of a dopant containing aniline monomer and ultrasonically vibrating the matrix, followed by cooling in an ice-water bath and allowing the matrix to stand; The mass ratio of the biomass carbon matrix to the aniline monomer is 5:1-1:20, and the volume ratio of the aniline monomer to the dopant aqueous solution is 1:50-1:200; S4: dissolving the oxidant in the dopant aqueous solution at a molar ratio of oxidant to aniline monomer of 1:0.5-1:2.5, slowly adding the solution dropwise to the solution prepared in S3, and then keeping the solution in an ice water bath, followed by filtering, washing, and freeze-drying to obtain a polyaniline / biomass carbon electromagnetic shielding material; In steps S3 and S4, the dopant is a combined protonic acid solution formed by mixing hydrochloric acid and camphorsulfonic acid in a molar ratio of 1:1-4:1, and the concentration of the dopant aqueous solution is 0.5-5 mol / L; In step S4, the oxidant is ammonium persulfate or ferric chloride.

2. The method for preparing a flexible polyaniline / biomass carbon electromagnetic shielding material according to claim 1, wherein: The temperature of the ice water bath in steps S3 and S4 is 0-5°C.

3. The method for preparing a flexible polyaniline / biomass carbon electromagnetic shielding material according to claim 1, wherein: In step S4, the oxidant and dopant aqueous solution are added at a rate of 0.5-10 ml / min, and the solution is stirred at a rate of 50-500 r / min. After the addition is completed, the solution is allowed to react for 5-24 hours.

4. A flexible polyaniline / biomass carbon electromagnetic shielding material, characterized by: The invention is prepared by the preparation method described in any one of claims 1 to 3.

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