Polymer CNT carbon film and preparation method thereof

Abstract

The invention relates to a high-molecular CNT (carbon nanotube) carbon film and a preparation method thereof, and belongs to the technical field of carbon nanotube composite films. The dispersity and uniformity are improved through CNT modification, a carbon network structure with high conductivity and high strength is constructed through the synergistic effect of CNT and graphene, and the anti-static performance, electromagnetic shielding performance, microwave absorption performance and heat conduction and heat transfer performance of the material are improved; in addition, the mechanical strength and transparency of the film are both considered by regulating and controlling the ratio of the polyvinyl alcohol to the polymethyl methacrylate; and accurate control of the film thickness is realized through multi-layer assembly of the electrostatic layers, and the structural stability of the film is remarkably improved.

Description

Technical Field

[0001] The invention belongs to the technical field of carbon nanotube composite films and relates to a polymer CNT carbon film and a preparation method thereof. Background Art

[0002] Carbon nanotubes (CNTs) are a type of nanoscale tubular material made of single or multiple layers of carbon atoms curled in a hexagonal lattice structure, with many outstanding properties. According to the number of layers, CNTs can be divided into single-walled carbon nanotubes and multi-walled carbon nanotubes. Among them, single-walled carbon nanotubes are composed of a layer of carbon atoms, with a simpler structure, a very high specific surface area, and excellent electrical and thermal conductivity; while multi-walled carbon nanotubes are composed of multiple coaxial carbon tubes and have higher structural stability. CNT not only has extremely high mechanical strength and excellent electrical conductivity, but also has good thermal conductivity and chemical stability, which makes it a research hotspot in the field of nanotechnology. Due to its nanoscale characteristics, CNT has an extremely high specific surface area and unique electronic structure, so it has shown a wide range of application potential in many advanced technologies, such as high-performance composite materials, electronic devices, energy storage, sensors, etc.

[0003] With the continuous development of CNT, its application in thin film materials has gradually attracted widespread attention. CNT film is usually composed of CNT arranged in a specific direction or randomly dispersed. CNT nanotubes can be arranged into a thin film structure through different preparation methods, such as chemical vapor deposition, solution impregnation, spraying, etc. CNT film exhibits very excellent electrical conductivity, thermal conductivity and mechanical strength due to its unique three-dimensional carbon network structure, and is widely used in electronics, energy, sensors, thermal management and other fields. In the field of electronics, CNT films are widely used in transparent conductive films, flexible electronic devices and display screens; in the field of energy, CNT films have shown excellent performance in energy storage devices such as supercapacitors and lithium batteries; in sensors and detection equipment, CNT films can efficiently respond to external changes and have high sensitivity and selectivity; in addition, the thermal conductivity of CNT films has led to its increasing application in the fields of electronic heat dissipation and thermal management.

[0004] However, although CNT films have shown their superior performance in many fields, the existing CNT film preparation technology still has some shortcomings, which limits its further development in practical applications. First, the dispersion of CNT in the matrix is ​​poor, resulting in uneven distribution in the film, affecting the overall performance of the film. This poor dispersion problem makes it difficult for the conductivity and mechanical strength of CNT films to reach an ideal state. Secondly, due to the low surface energy of CNTs, they often lack good interface compatibility with other materials. Therefore, relying solely on the mechanical properties and conductive properties of CNTs may not fully realize their potential. In addition, the thickness and uniformity of CNT films are difficult to accurately control, which may lead to problems such as uneven film thickness or poor film quality in practical applications, further affecting the stability and performance of the film. Summary of the invention

[0005] The present invention relates to a polymer CNT carbon film and a preparation method thereof, and belongs to the technical field of carbon nanotube composite thin films. The present invention improves the dispersion and uniformity through CNT modification, and synergizes with graphene to construct a carbon network structure with high conductivity and high strength, thereby improving the antistatic, electromagnetic shielding, microwave absorption and thermal conductivity of the material; in addition, by adjusting the ratio of polyvinyl alcohol and polymethyl methacrylate, the mechanical strength and transparency of the film are taken into account; and the multi-layer assembly of the electrostatic layer realizes the precise control of the film thickness, and significantly improves the structural stability of the film.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A polymer CNT carbon film comprises the following raw materials in parts by weight: 5-15 parts of modified CNT, 5-10 parts of graphene, 1-3 parts of dispersant, 50-70 parts of polymer material, 2-8 parts of polyethyleneimine, and 2-8 parts of sodium polystyrene sulfonate.

[0008] As a preferred technical solution of the present invention, the modified CNT preparation method is: adding CNT to a mixed acid of 70% nitric acid and 98% sulfuric acid in a volume ratio of 1:3, heating to 70-90°C and stirring for 2-6h, obtaining carboxylated CNT by centrifugation, washing and drying, adding the carboxylated CNT to a 0.5-2wt% silane coupling agent ethanol solution, stirring at 70-90°C for 1-3h, and obtaining modified CNT by centrifugation, washing and drying; the mass ratio of the CNT, the mixed acid and the silane coupling agent is 1:100-200:1-2.

[0009] As a preferred technical solution of the present invention, the dispersant is sodium dodecyl sulfate or polyvinyl pyrrolidone.

[0010] As a preferred technical solution of the present invention, the polymer material is polyvinyl alcohol and polymethyl methacrylate, and the mass ratio of the polyvinyl alcohol to polymethyl methacrylate is 1:1-2.

[0011] Furthermore, the method for preparing a polymer CNT carbon film comprises the following steps:

[0012] (1) dispersing the modified CNT and graphene in anhydrous ethanol, adding a dispersant and ultrasonically treating for 30-60 min, and then removing the undispersed large particles by high-speed centrifugation;

[0013] (2) depositing a uniform CNT film by vacuum filtration and drying at 60-80°C for 2-4h;

[0014] (3) dissolving the polymer material in anhydrous ethanol to form a polymer solution, immersing the dried CNT film in the polymer solution so that the polymer material enters the network pores of the CNT film through capillary action and interacts with the CNT surface to form a polymer film;

[0015] (4) immersing the polymer film in a positively charged polyethyleneimine solution and allowing it to stand for 5-10 minutes to allow the polyethyleneimine molecules to be deposited on the film surface by electrostatic adsorption to form a positively charged layer; rinsing it with deionized water and then immersing it in a negatively charged sodium polystyrene sulfonate solution and allowing it to stand for 5-10 minutes to form a negatively charged layer, and rinsing it with deionized water to obtain a polymer electrostatic layer;

[0016] (5) Repeat step (4) to assemble multiple layers of polymer electrostatic layers according to the required thickness, and then vacuum dry at 50-80° C. for 1-2 hours to obtain a polymer CNT carbon film.

[0017] As a preferred technical solution of the present invention, the mass ratio of the modified CNT and anhydrous ethanol in step (1) is 1:100-300.

[0018] As a preferred technical solution of the present invention, the thickness of the CNT film after drying in step (2) is 80-120 nm.

[0019] As a preferred technical solution of the present invention, the mass ratio of the polymer material to anhydrous ethanol in step (3) is 1:20-100.

[0020] As a preferred technical solution of the present invention, the method for preparing the polyethyleneimine solution in step (4) is to dissolve polyethyleneimine in deionized water to a concentration of 1-2wt%, and adjust the pH to 6-8 with 0.1M dilute hydrochloric acid; the method for preparing the sodium polystyrene sulfonate solution is to dissolve sodium polystyrene sulfonate in deionized water to a concentration of 1-2wt%, and adjust the pH to 6-8 with 0.1M sodium hydroxide solution.

[0021] As a preferred technical solution of the present invention, the thickness of the polymer electrostatic layer in step (5) is 2-8 nm.

[0022] Beneficial effects of the present invention:

[0023] (1) Carbon nanotubes (CNTs) and graphene are both carbon-based nanomaterials with unique electrical conductivity, mechanical properties, and thermal properties. The high longitudinal conductivity of CNTs and the in-plane conductivity of graphene complement each other to construct a three-dimensional conductive network, making the film highly conductive; the two-dimensional layer structure of graphene can effectively fill the gaps between CNTs, enhance the density and uniformity of the material, and further improve the electromagnetic shielding and microwave absorption performance. The high conductivity of CNTs and graphene enables the rapid conduction and release of charges to avoid static electricity accumulation; the three-dimensional carbon network structure can effectively absorb and reflect electromagnetic waves to form a shielding effect; the high electrical conductivity of CNTs and graphene further enhances the shielding effectiveness; the nanostructure of CNTs and graphene can introduce multiple scattering and absorption of microwaves, and the high electrical conductivity of the material helps to convert electromagnetic waves into thermal energy; both CNTs and graphene have extremely high thermal conductivity (CNTs can reach 3000W / m·K, and graphene can reach 5000W / m·K), and their three-dimensional network structure can effectively improve the overall thermal conductivity of the film. By modifying CNT, its dispersibility is improved, so that it can be evenly distributed in the matrix and form a stable network structure with graphene.

[0024] (2) Polyvinyl alcohol is a polymer material with good mechanical strength and flexibility, but its transparency is poor. Polymethyl methacrylate is a transparent material with good optical properties, but its mechanical strength is relatively low. Through reasonable ratio control, a balance can be achieved between the two, so that the film has both high mechanical strength and good optical transparency.

[0025] (3) The multilayer assembly technology of electrostatic layers is a self-assembly method based on electrostatic effects. Materials with opposite charges are deposited alternately layer by layer on the substrate surface to form a multilayer film. By controlling the number of assembly cycles, the thickness of the film can be precisely controlled while maintaining the uniformity and stability of the film. This method can also enhance the binding force between molecules or nanomaterials within the film, thereby further improving the structural stability of the film. DETAILED DESCRIPTION

[0026] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.

[0027] In the following embodiments and comparative examples, the CNT was purchased from Shanghai Kaishefeng Industrial Co., Ltd. with the item number 200898769; graphene was purchased from Nangong Dinghong Metal Materials Co., Ltd.; silane coupling agent was purchased from Shanyi Plastic Co., Ltd. with the item number KH-570; polyvinyl alcohol was purchased from Langfang Feitai New Materials Technology Co., Ltd. with the model number 2488; polymethyl methacrylate was purchased from Guangye Plastic Raw Materials Co., Ltd. with the item number CM211; polyethyleneimine was purchased from Shanghai Hanluo New Materials Co., Ltd.; sodium polystyrene sulfonate was purchased from Zibo Yaodong Chemical Co., Ltd.

[0028] Example 1

[0029] A polymer CNT carbon film comprises the following raw materials in parts by weight: 10 parts of modified CNT, 7 parts of graphene, 2 parts of dispersant, 60 parts of polymer material, 5 parts of polyethyleneimine, and 5 parts of sodium polystyrene sulfonate.

[0030] The modified CNT preparation method is as follows: CNT is added to a mixed acid of 70% nitric acid and 98% sulfuric acid in a volume ratio of 1:3, heated to 80°C and stirred for 4 hours, carboxylated CNT is obtained by centrifugation, washing and drying, carboxylated CNT is added to a 1wt% silane coupling agent ethanol solution, stirred at 80°C for 2 hours, and modified CNT is obtained by centrifugation, washing and drying; the mass ratio of CNT, mixed acid and silane coupling agent is 1:150:1.5.

[0031] The dispersant is sodium dodecyl sulfate.

[0032] The polymer material is polyvinyl alcohol and polymethyl methacrylate, and the mass ratio of the polyvinyl alcohol to polymethyl methacrylate is 1:1.5.

[0033] The method for preparing a polymer CNT carbon film comprises the following steps:

[0034] (1) Dispersing the modified CNT and graphene in anhydrous ethanol, adding a dispersant and ultrasonically treating for 45 min, and then removing the undispersed large particles by high-speed centrifugation;

[0035] (2) depositing a uniform CNT film by vacuum filtration and drying at 70 °C for 3 h;

[0036] (3) dissolving the polymer material in anhydrous ethanol to form a polymer solution, immersing the dried CNT film in the polymer solution so that the polymer material enters the network pores of the CNT film through capillary action and interacts with the CNT surface to form a polymer film;

[0037] (4) immersing the polymer film in a positively charged polyethyleneimine solution and allowing it to stand for 7 minutes to allow the polyethyleneimine molecules to be deposited on the film surface by electrostatic adsorption to form a positively charged layer; rinsing it with deionized water, immersing it in a negatively charged sodium polystyrene sulfonate solution and allowing it to stand for 7 minutes to form a negatively charged layer, and rinsing it with deionized water; a polymer electrostatic layer is obtained;

[0038] (5) Repeat step (4) to assemble multiple layers of polymer electrostatic layers according to the required thickness, and then vacuum dry at 65° C. for 1.5 hours to obtain a polymer CNT carbon film with a thickness of 100 nm.

[0039] The mass ratio of the modified CNT and anhydrous ethanol in step (1) is 1:200.

[0040] The thickness of the CNT film after drying in step (2) is 90 nm.

[0041] The mass ratio of the polymer material to anhydrous ethanol in step (3) is 1:60.

[0042] The method for preparing the polyethyleneimine solution in step (4) is to dissolve polyethyleneimine in deionized water to a concentration of 1.5wt%, and adjust the pH to 7 with 0.1M dilute hydrochloric acid; the method for preparing the sodium polystyrene sulfonate solution is to dissolve sodium polystyrene sulfonate in deionized water to a concentration of 1.5wt%, and adjust the pH to 7 with 0.1M sodium hydroxide solution.

[0043] The thickness of the polymer electrostatic layer in step (5) is 5 nm.

[0044] Example 2

[0045] A polymer CNT carbon film comprises the following raw materials in parts by weight: 5 parts of modified CNT, 5 parts of graphene, 1 part of dispersant, 50 parts of polymer material, 2 parts of polyethyleneimine, and 2 parts of sodium polystyrene sulfonate.

[0046] The modified CNT preparation method is as follows: CNT is added to a mixed acid of 70% nitric acid and 98% sulfuric acid in a volume ratio of 1:3, heated to 70°C and stirred for 2 hours, carboxylated CNT is obtained by centrifugation, washing and drying, carboxylated CNT is added to a 0.5wt% silane coupling agent ethanol solution, stirred at 70°C for 1 hour, and then modified CNT is obtained by centrifugation, washing and drying; the mass ratio of CNT, mixed acid and silane coupling agent is 1:100:1.

[0047] The dispersant is sodium dodecyl sulfate.

[0048] The polymer material is polyvinyl alcohol and polymethyl methacrylate, and the mass ratio of the polyvinyl alcohol to polymethyl methacrylate is 1:1.

[0049] The method for preparing a polymer CNT carbon film comprises the following steps:

[0050] (1) Dispersing the modified CNT and graphene in anhydrous ethanol, adding a dispersant and ultrasonically treating for 30 min, and then removing the undispersed large particles by high-speed centrifugation;

[0051] (2) depositing a uniform CNT film by vacuum filtration and drying at 60 °C for 2 h;

[0052] (3) dissolving the polymer material in anhydrous ethanol to form a polymer solution, immersing the dried CNT film in the polymer solution so that the polymer material enters the network pores of the CNT film through capillary action and interacts with the CNT surface to form a polymer film;

[0053] (4) immersing the polymer film in a positively charged polyethyleneimine solution and allowing it to stand for 5 minutes to allow the polyethyleneimine molecules to be deposited on the film surface by electrostatic adsorption to form a positively charged layer; rinsing it with deionized water and then immersing it in a negatively charged sodium polystyrene sulfonate solution and allowing it to stand for 5 minutes to form a negatively charged layer, and rinsing it with deionized water to obtain a polymer electrostatic layer;

[0054] (5) Repeat step (4) to assemble multiple layers of polymer electrostatic layers according to the required thickness, and then vacuum dry at 50° C. for 2 hours to obtain a polymer CNT carbon film with a thickness of 100 nm.

[0055] The mass ratio of the modified CNT and anhydrous ethanol in step (1) is 1:100.

[0056] The thickness of the CNT film after drying in step (2) is 80 nm.

[0057] The mass ratio of the polymer material to anhydrous ethanol in step (3) is 1:100.

[0058] The method for preparing the polyethyleneimine solution in step (4) is to dissolve polyethyleneimine in deionized water to a concentration of 1wt%, and adjust the pH to 6 with 0.1M dilute hydrochloric acid; the method for preparing the sodium polystyrene sulfonate solution is to dissolve sodium polystyrene sulfonate in deionized water to a concentration of 1wt%, and adjust the pH to 6 with 0.1M sodium hydroxide solution.

[0059] The thickness of the polymer electrostatic layer in step (5) is 2 nm.

[0060] Example 3

[0061] A high molecular CNT carbon film comprises the following raw materials in parts by weight: 15 parts of modified CNT, 10 parts of graphene, 3 parts of dispersant, 70 parts of high molecular material, 2-8 parts of polyethyleneimine, and 2-8 parts of sodium polystyrene sulfonate.

[0062] The modified CNT preparation method is as follows: CNT is added to a mixed acid of 70% nitric acid and 98% sulfuric acid in a volume ratio of 1:3, heated to 70-90°C and stirred for 2-6 hours, carboxylated CNT is obtained by centrifugation, washing and drying, carboxylated CNT is added to a 0.5-2wt% silane coupling agent ethanol solution, stirred at 70-90°C for 1-3 hours, and then centrifuged, washed and dried to obtain modified CNT; the mass ratio of CNT, mixed acid and silane coupling agent is 1:200:2.

[0063] The dispersant is polyvinyl pyrrolidone.

[0064] The polymer material is polyvinyl alcohol and polymethyl methacrylate, and the mass ratio of the polyvinyl alcohol to polymethyl methacrylate is 1:2.

[0065] The method for preparing a polymer CNT carbon film is characterized by comprising the following steps:

[0066] (1) Dispersing the modified CNT and graphene in anhydrous ethanol, adding a dispersant and ultrasonically treating for 60 min, and then removing the undispersed large particles by high-speed centrifugation;

[0067] (2) depositing a uniform CNT film by vacuum filtration and drying at 80 °C for 2 h;

[0068] (3) dissolving the polymer material in anhydrous ethanol to form a polymer solution, immersing the dried CNT film in the polymer solution so that the polymer material enters the network pores of the CNT film through capillary action and interacts with the CNT surface to form a polymer film;

[0069] (4) immersing the polymer film in a positively charged polyethyleneimine solution and allowing it to stand for 10 minutes so that the polyethyleneimine molecules are deposited on the film surface by electrostatic adsorption to form a positively charged layer; rinsing it with deionized water and then immersing it in a negatively charged sodium polystyrene sulfonate solution and allowing it to stand for 10 minutes to form a negatively charged layer, and rinsing it with deionized water to obtain a polymer electrostatic layer;

[0070] (5) Repeat step (4) to assemble multiple layers of polymer electrostatic layers according to the required thickness, and then vacuum dry at 80° C. for 1 hour to obtain a polymer CNT carbon film with a thickness of 100 nm.

[0071] The mass ratio of the modified CNT and anhydrous ethanol in step (1) is 1:300.

[0072] The thickness of the CNT film after drying in step (2) is 80 nm.

[0073] The mass ratio of the polymer material to anhydrous ethanol in step (3) is 1:100.

[0074] The method for preparing the polyethyleneimine solution in step (4) is to dissolve polyethyleneimine in deionized water to a concentration of 2wt%, and adjust the pH to 8 with 0.1M dilute hydrochloric acid; the method for preparing the sodium polystyrene sulfonate solution is to dissolve sodium polystyrene sulfonate in deionized water to a concentration of 2wt%, and adjust the pH to 8 with 0.1M sodium hydroxide solution.

[0075] The thickness of the polymer electrostatic layer in step (5) is 4 nm.

[0076] Comparative Example 1

[0077] On the basis of Example 1, only polyvinyl alcohol is added to the polymer material, and the rest is consistent with Example 1.

[0078] Comparative Example 2

[0079] On the basis of Example 1, only polymethyl methacrylate is added to the polymer material, and the rest is consistent with Example 1.

[0080] Comparative Example 3

[0081] On the basis of Example 1, graphene was not added, the amount of modified CNT added was changed to 17 parts by weight, and the rest was the same as Example 1.

[0082] Comparative Example 4

[0083] On the basis of Example 1, no modification treatment of CNT is performed, and the rest is consistent with Example 1.

[0084] Performance Testing:

[0085] Transmittance test: Refer to GB / T 2410-2008 "Determination of light transmittance and haze of transparent plastics" standard to test transmittance, the unit is %;

[0086] Impact strength test: Performance test was carried out in accordance with GB / T1043.1-2008 standard, the sample size was 80mmx10mmx4mm, the impact test machine used was WKT-LC2000, and the unit was kJ / m2;

[0087] Electromagnetic shielding test: According to GB / T30142-2013 standard, the average electromagnetic shielding effectiveness of the material from 0.5MHz to 20GHz is measured. The shielding effectiveness of the material is expressed by shielding attenuation. The greater the shielding attenuation value, the better the shielding effectiveness. The unit is decibel (dB);

[0088] Antistatic performance test: test temperature 22±5℃, test humidity below 45%, test instrument is static tester;

[0089] Thermal conductivity: Thermal conductivity is measured according to ASTM E1461-2013 test method, and the unit is W / (m·K).

[0090] Light transmittance Impact strength Shielding effectiveness Thermal conductivity Example 1 94.4 21.4 41.2 1500 Example 2 94.6 20.8 40.3 1450 Example 3 93.9 21.1 40.8 1450 Comparative Example 1 88.4 15.3 3.81 1400 Comparative Example 2 87.7 14.9 37.6 1400 Comparative Example 3 93.1 20.2 29.4 1250 Comparative Example 4 92.2 20.4 29.1 1250

[0091] It can be seen from the test results that the present invention improves the electromagnetic shielding effectiveness and thermal conductivity of the carbon film through the synergistic effect of CNT and graphene, and takes into account the mechanical strength and transparency of the film by adjusting the ratio of polyvinyl alcohol and polymethyl methacrylate.

[0092] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any indirect modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A polymer CNT carbon film, characterized in that: The invention comprises the following raw materials in parts by weight: 5-15 parts of modified CNT, 5-10 parts of graphene, 1-3 parts of dispersant, 50-70 parts of polymer material, 2-8 parts of polyethyleneimine and 2-8 parts of sodium polystyrene sulfonate.

2. A polymer CNT carbon film according to claim 1, characterized in that: The modified CNT preparation method comprises the following steps: adding CNT to a mixed acid of 70% nitric acid and 98% sulfuric acid in a volume ratio of 1:3, heating to 70-90° C. and stirring for 2-6 hours, obtaining carboxylated CNT by centrifugation, washing and drying, adding the carboxylated CNT to a 0.5-2wt% silane coupling agent ethanol solution, stirring at 70-90° C. for 1-3 hours, and obtaining the modified CNT by centrifugation, washing and drying; the mass ratio of the CNT, the mixed acid and the silane coupling agent is 1:100-200:1-2.

3. A polymer CNT carbon film according to claim 1, characterized in that: The dispersant is sodium dodecyl sulfate or polyvinyl pyrrolidone.

4. The polymer CNT carbon film according to claim 1, characterized in that: The polymer material is polyvinyl alcohol and polymethyl methacrylate, and the mass ratio of the polyvinyl alcohol to polymethyl methacrylate is 1:1-2.

5. A method for preparing a polymer CNT carbon film according to any one of claims 1 to 4, characterized in that: The following steps are involved: (1) dispersing the modified CNT and graphene in anhydrous ethanol, adding a dispersant and ultrasonically treating for 30-60 min, and then removing the undispersed large particles by high-speed centrifugation; (2) depositing a uniform CNT film by vacuum filtration and drying at 60-80°C for 2-4h; (3) dissolving the polymer material in anhydrous ethanol to form a polymer solution, immersing the dried CNT film in the polymer solution so that the polymer material enters the network pores of the CNT film through capillary action and interacts with the CNT surface to form a polymer film; (4) immersing the polymer film in a positively charged polyethyleneimine solution and allowing it to stand for 5-10 minutes to allow the polyethyleneimine molecules to be deposited on the film surface by electrostatic adsorption to form a positively charged layer; rinsing it with deionized water and then immersing it in a negatively charged sodium polystyrene sulfonate solution and allowing it to stand for 5-10 minutes to form a negatively charged layer, and rinsing it with deionized water to obtain a polymer electrostatic layer; (5) Repeat step (4) to assemble multiple layers of polymer electrostatic layers according to the required thickness, and then vacuum dry at 50-80° C. for 1-2 hours to obtain a polymer CNT carbon film.

6. The method for preparing a polymer CNT carbon film according to claim 5, characterized in that: The mass ratio of the modified CNT and anhydrous ethanol in step (1) is 1:100-300.

7. The method for preparing a polymer CNT carbon film according to claim 5, characterized in that: The thickness of the CNT film after drying in step (2) is 80-120 nm.

8. The method for preparing a polymer CNT carbon film according to claim 5, characterized in that: The mass ratio of the polymer material to anhydrous ethanol in step (3) is 1:20-100.

9. The method for preparing a polymer CNT carbon film according to claim 5, characterized in that: The method for preparing the polyethyleneimine solution in step (4) is to dissolve polyethyleneimine in deionized water to a concentration of 1-2wt%, and adjust the pH to 6-8 with 0.1M dilute hydrochloric acid; the method for preparing the sodium polystyrene sulfonate solution is to dissolve sodium polystyrene sulfonate in deionized water to a concentration of 1-2wt%, and adjust the pH to 6-8 with 0.1M sodium hydroxide solution.

10. The method for preparing a polymer CNT carbon film according to claim 5, characterized in that: The thickness of the polymer electrostatic layer in step (5) is 2-8 nm.