CNTs / MXene / PI aerogel flexible conductive composite material based on bionic structure design as well as preparation method and application of CNTs / MXene / PI aerogel flexible conductive composite material

Abstract

The invention discloses a CNTs / MXene / PI aerogel flexible conductive composite material based on bionic structure design as well as a preparation method and application of the CNTs / MXene / PI aerogel flexible conductive composite material. The invention aims to solve the problem that a flexible sensing material fails at a high temperature and cannot carry out flexible sensing at the high temperature, which limits the application of the flexible sensing material in the field of flexible sensing. According to the preparation method, 4, 4 '-diamino diphenyl ether, 3, 3', 4, 4 '-biphenyl tetracarboxylic dianhydride and triethylamine are taken as raw materials, and a water-soluble polyamide acid salt material is prepared. According to the preparation method, the CNTs and MXene materials are doped into a polyimide salt solution by utilizing the self-assembly effect of the CNTs and MXene materials, and finally, the polyimide-based flexible aerogel sensing material with high temperature resistance is prepared through a thermal imidization process. The composite material disclosed by the invention can be used for carrying out flexible sensing monitoring at high temperature and has huge application potential in the field of high-temperature flexible sensing application.

Description

Technical Field

[0001] The present invention belongs to the technical field of flexible sensors, and specifically relates to a CNTs / MXene / PI aerogel flexible conductive composite material based on bionic structure design, and a preparation method and application thereof. Background Art

[0002] A sensor is a device that converts physical, chemical or biological signals into measurable electrical signals, and is widely used in fields such as environmental monitoring, healthcare, intelligent manufacturing, and the Internet of Things. Flexible sensors, due to their characteristics of being thin, light, bendable, and highly sensitive, show unique advantages especially in wearable devices, electronic skin, and flexible robots. In modern industry, sensors and flexible sensors, as key components, can achieve precise monitoring, intelligent control, and automated operation, and are important technical bases for promoting the development of intelligent manufacturing and Industry 4.0.

[0003] In recent years, significant progress has been made in flexible sensors in the fields of materials, structural design, and applications. In terms of materials, the research focus has shifted from traditional conductive materials to nanomaterials with excellent flexibility and processability, such as graphene, MXene, carbon nanotubes, and their composites, which can significantly improve the sensitivity, reliability, and durability of sensors. In terms of structural design, micro-nano structure regulation and multi-functional integration strategies have further enhanced the performance adaptability of flexible sensors in complex environments. For example, through bionic structure design, dynamic responses in a high strain range can be achieved. In terms of applications, flexible sensors have been widely used in wearable devices, health monitoring, and intelligent robots, and in particular, the development of new sensing materials and devices in extreme environments such as high temperature and high pressure has received much attention. Summary of the Invention

[0004] The present invention aims to solve the problem that flexible sensing materials fail at high temperatures and cannot perform flexible sensing at high temperatures, which limits their application in the field of flexible sensing.

[0005] To solve the above technical problems, the present invention adopts the following technical solutions:

[0006] The present invention provides a unique CNTs / MXene / PI aerogel flexible conductive composite material based on bionic structural design. The core design idea of ​​the present invention is to obtain the multi-tentacle structure of the sea anemone. The composite material provides a rich micro-nanoscale conductive path, which significantly improves the conductive performance and strain sensitivity of the material, thereby obtaining a sensing system for sensing changes in the external environment. By coating CNTs on the surface of MXene, the specific surface area of ​​the conductive material is expanded, and the signal transmission with the outside world is increased. MXene acts as a signal transfer station, and transmits electrical signals through the external "tentacles" - CNTs, and then quickly transmits electrical signals to all directions through the central processing unit - MXene, thereby increasing the overall conductivity of the material. The CNTs / MXene / PI aerogel flexible conductive composite material of the present invention has a high surface area and a complex network structure, which helps to enhance the bonding force with the matrix and improve the mechanical stability and durability of the composite material. The multi-tentacle structure of the sea anemone of the present invention can maintain excellent conductive properties within a large strain range, so that it has excellent performance in flexible sensors, especially suitable for detecting small deformations and complex dynamic environments. Combined with its structural adjustability and functional integration potential, the conductive filler structure design of the bionic anemone structure of the present invention provides an innovative path for the development of high-performance flexible electronic devices. At the same time, by selecting polyimide as the flexible substrate, it can also provide the material with a higher heat resistance level, ensuring the flexible sensing of the material at high temperatures.

[0007] The object of the present invention is to provide a method for preparing a CNTs / MXene / PI aerogel flexible conductive composite material based on a bionic structure design, comprising the following steps:

[0008] Step 1: Add nanocellulose (CNF) powder into deionized water and stir magnetically until dissolved, add MXene powder, ultrasonicate until evenly dispersed, then add CNTs, ultrasonicate until evenly dispersed, to obtain a mixed solution;

[0009] Step 2: After mixing polyamic acid salt (PAAs) and TEA, stir magnetically for 2 h to 4 h to obtain a PAAs solution.

[0010] Step 3: Add the mixed solution obtained in step 1 to the PAAs solution obtained in step 2, stir magnetically for 3 hours, pour into a mold, freeze into a block, freeze-dry, and then heat gradually under argon protection for imidization to obtain the aerogel flexible conductive composite material.

[0011] Further limitation: The polyamic acid salt (PAAs) described in step 2 is prepared according to the following steps: Dissolve 4,4'-diaminodiphenyl ether (ODA) in an organic solvent under nitrogen protection, then add 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), stir in a water bath at 0°C for 6 h, add triethylamine (TEA) dropwise, and continue stirring for 3 - 4 h after the addition; then slowly drop it into deionized water, then stir at high speed at room temperature, filter by suction, repeatedly wash with deionized water, freeze after suction filtration, and then freeze-dry to obtain polyamic acid salt (PAAs).

[0012] Even further limitation: The molar ratio of ODA, BPDA, and TEA is 1∶1.01∶1.

[0013] Even further limitation: The organic solvent is N,N-dimethylacetamide (DMAc) or N-methylpyrrolidone (NMP).

[0014] Even further limitation: The temperature of the deionized water for washing is 0°C.

[0015] Even further limitation: The number of times of repeated washing is 3 - 5 times.

[0016] Even further limitation: The dropping rate of triethylamine (TEA) is 0.2 ml / min - 0.5 ml / min.

[0017] Even further limitation: Freezing can be carried out in a refrigerator or in the deep trap of a freeze dryer.

[0018] Even further limitation: The conditions for freeze-drying are -60°C to -80°C and the pressure is 2 Pa.

[0019] Further limitation: In step 1, the mass ratio of CNF, MXene, and CNTs is 1∶(0.4 - 2)∶4.

[0020] Further limitation: In step 2, the molar ratio of polyamic acid salt (PAAs) and TEA is 1:1.

[0021] Further limitation: In step 3, add the mixed solution obtained in step 1 to the PAAs solution obtained in step 2 according to the mass ratio of CNTs, MXene, and PI of 0.25∶(0.05 - 0.25)∶1. The mass ratio of CNTs, MXene, and PI can be 0.25∶0.05∶1, 0.25∶0.10∶1, 0.25∶0.15∶1, 0.25∶0.20∶1, 0.25∶0.25∶1.

[0022] Further limitation: In step three, the freezing method is ultrasonic freezing. An ultrasonic cleaner is used for ultrasonic freezing. The freezing liquid in the ultrasonic cleaner is absolute ethanol, and liquid nitrogen is used to cool the absolute ethanol to -20°C.

[0023] Further limitation: In step three, freeze-dry at -60°C and 2 Pa.

[0024] Further limitation: In step three, the gradient heating process: Heat at a rate of 10°C / min to 80°C, hold for 30 min, heat at a rate of 10°C / min to 150°C, hold for 30 min, heat at a rate of 10°C / min to 200°C, hold for 30 min, heat at a rate of 10°C / min to 250°C, hold for 30 min, heat at a rate of 10°C / min to 300°C, hold for 30 min, heat at a rate of 10°C / min to 350°C, hold for 30 min.

[0025] Another object of the present invention is to provide an aerogel flexible conductive composite material prepared by any of the above methods.

[0026] The CNTs / MXene / PI composite aerogel flexible material with a bionic filler structure prepared by the above method is mainly used in the field of flexible sensing.

[0027] The present invention uses 4,4'-diaminodiphenyl ether, 3,3’,4,4’-biphenyltetracarboxylic dianhydride, and triethylamine as raw materials to prepare a water-soluble polyamic acid salt material. By utilizing the self-assembly effect of CNTs and MXene materials, they are doped into the polyimide salt solution, and finally a polyimide-based flexible aerogel sensing material with high-temperature resistance is prepared through a thermal imidization process. The composite material of the present invention can perform flexible sensing monitoring at high temperatures and has great application potential in the field of high-temperature flexible sensing applications.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The method of the present invention uses CNTs to modify the surface of MXene to improve the conductivity of the conductive filler. At the same time, by selecting polyimide as the flexible matrix resin, the material is given more excellent environmental stability. By using the ultrasonic-assisted freeze-drying method, the dispersion effect of the conductive material in the polymer matrix can be optimized, and at the same time, the energy of ultrasonic waves can be used to limit the growth of ice crystals during the pre-freezing process, making the pore distribution inside the aerogel more uniform and having more excellent mechanical properties. The composite aerogel flexible strain sensor material prepared by the present invention has the advantages of simple preparation method and low cost, and at the same time has great development potential in the field of flexible sensing under extreme environments.

[0030] To further understand the features and technical content of the present invention, please refer to the following detailed description of the present invention and the accompanying drawings. However, the accompanying drawings are only for reference and illustration purposes and are not used to limit the present invention. Description of the Drawings

[0031] Figure 1 is a scanning electron microscope image of CNTs-modified MXene;

[0032] Figure 2 is the compressive stress-strain curve of the composite aerogel;

[0033] Figure 3 is the sensitivity curve of the flexible strain piezoresistive sensing material prepared by the method of Example 4;

[0034] Figure 4 is the thousand-cycle stability curve of the flexible strain piezoresistive sensing material prepared by the method of Example 4 under 20% compressive deformation. Detailed Embodiments

[0035] The present invention will be described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, and at the same time do not limit the present invention in any form. It should be noted that for those of ordinary skill in the art, without departing from the inventive concept of the present invention, several modifications and improvements can be made. These all fall within the protection scope of the present invention.

[0036] The following embodiments describe the implementation schemes of the present invention. For those not specified in the embodiments, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For those reagents or instruments not specified in the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0037] The preparation method of the PAAs precursor in the embodiments of this patent is carried out according to the following steps:

[0038] Step 1: Put 30 g of N-methylpyrrolidone (NMP) into a three-necked flask. Under nitrogen protection (the flow rate of nitrogen is 0.05 m 3 / h), dissolve 1.81 g of 4,4'-diaminodiphenyl ether (ODA) in 30 g of N-methylpyrrolidone (NMP);

[0039] Step 2: Then add 2.65 g of 3,3’,4,4’-biphenyltetracarboxylic dianhydride (BPDA), mix evenly, and stir at a speed of 40 rpm / min for 6 h in a water bath atmosphere at zero degree.

[0040] Step 3: Then, 0.912 g of triethylamine (TEA) was added dropwise at a rate of 0.2 ml / min. After uniform mixing, the mixture was continuously stirred at a speed of 40 rpm / min for 3 - 4 h to obtain a polyamic acid salt solution (PAAs) solution;

[0041] Step 4: Finally, the synthesized polyamic acid salt solution (PAAs) solution was slowly added dropwise into 500 g of deionized water at 0 °C at a rate of 1 ml / min. Then, it was vigorously stirred at a speed of 400 rpm / min at room temperature for 0.2 h. After filtration, it was repeatedly washed three times with deionized water at 0 °C, and PAAs was obtained by filtration;

[0042] Step 5: Then, the PAAs was filtered out and placed in a petri dish, and freeze-dried in the deep trap of a freeze dryer at -80 °C;

[0043] Step 6: The frozen PAAs was placed in a freeze dryer and freeze-dried at -60 °C and a pressure of 2 Pa for 72 h to obtain polyamic acid salt (PAAs), which was stored frozen.

[0044] Example 1: In this example, the preparation method of the CNTs / MXene / PI aerogel flexible conductive composite material based on the bionic structure design was carried out according to the following steps:

[0045] Step 1: 6.25 mg of nanocellulose (CNF) powder was added to 10 g of deionized water and magnetically stirred until dissolved (taking 3 h). 2.5 mg of single-layer MXene powder (Xinxi Technology Co., Ltd., single-layer Ti 3 C 2 T x powder) was added, and it was ultrasonicated until uniformly dispersed (taking 10 min) under ultrasonic conditions (ultrasonic power of 200 W). Then, 25 mg of CNTs was added, and it was ultrasonicated until uniformly dispersed (taking 20 min) under ultrasonic conditions (ultrasonic power of 200 W) to obtain a mixed solution, which was left for later use;

[0046] Step 2: After mixing 50 mg of polyamic acid salt (PAAs) and 15 μl of TEA, it was magnetically stirred at a speed of 200 rpm / min for 4 h to obtain a PAAs solution.

[0047] Step 3: Under nitrogen protection, the mixed solution obtained in Step 1 was added to the PAAs solution obtained in Step 2, and it was magnetically stirred at a speed of 200 rpm / min for 3 h. It was transferred to a mold using a disposable pipette, frozen into a block, and then freeze-dried at -60 °C and 2 Pa for 72 h. It was placed in a tubular furnace, and then imidized by gradient heating under argon protection to obtain the aerogel flexible conductive composite material;

[0048] In Step 3, the gradient heating process is as follows: Heat up at a rate of 10 °C / min to 80 °C, hold for 30 min, heat up at a rate of 10 °C / min to 150 °C, hold for 30 min, heat up at a rate of 10 °C / min to 200 °C, hold for 30 min, heat up at a rate of 10 °C / min to 250 °C, hold for 30 min, heat up at a rate of 10 °C / min to 300 °C, hold for 30 min, heat up at a rate of 10 °C / min to 350 °C, and hold for 30 min.

[0049] In Step 3, the freezing method is ultrasonic freezing. Use an ultrasonic cleaner for ultrasonic freezing. The freezing liquid in the ultrasonic cleaner is absolute ethanol, and liquid nitrogen is used to cool the absolute ethanol to -20 °C.

[0050] Example 2: In this example, the preparation method of the CNTs / MXene / PI aerogel flexible conductive composite material based on the bionic structure design is carried out according to the following steps:

[0051] Step 1: Add 6.25 mg of nanocellulose (CNF) powder to 10 g of deionized water and stir magnetically until dissolved (takes 3 h). Add 5 mg of single-layer MXene powder (Xinxi Technology Co., Ltd., single-layer Ti 3 C 2 T x powder), and ultrasonically disperse it evenly (takes 10 min) under ultrasonic conditions (ultrasonic power is 200 W). Then add 25 mg of CNTs and ultrasonically disperse it evenly (takes 20 min) under ultrasonic conditions (ultrasonic power is 200 W) to obtain a mixed solution, and set it aside for use.

[0052] Step 2: After mixing 50 mg of polyamic acid salt (PAAs) and 15 μl of TEA, stir magnetically at a speed of 200 rpm for 4 h to obtain a PAAs solution.

[0053] Under nitrogen protection, add the mixed solution obtained in Step 1 to the PAAs solution obtained in Step 2, stir magnetically at a speed of 200 rpm for 3 h, transfer it to a mold using a disposable pipette, freeze it into a block, then freeze-dry it at -60 °C and 2 Pa for 72 h, place it in a tube furnace, and then perform imidization under argon protection with gradient heating to obtain the aerogel flexible conductive composite material;

[0054] In Step 3, the gradient heating process: heat up at a rate of 10 °C / min to 80 °C, hold for 30 min, heat up at a rate of 10 °C / min to 150 °C, hold for 30 min, heat up at a rate of 10 °C / min to 200 °C, hold for 30 min, heat up at a rate of 10 °C / min to 250 °C, hold for 30 min, heat up at a rate of 10 °C / min to 300 °C, hold for 30 min, heat up at a rate of 10 °C / min to 350 °C, hold for 30 min.

[0055] In Step 3, the freezing method is ultrasonic freezing. Use an ultrasonic cleaner for ultrasonic freezing. The freezing liquid in the ultrasonic cleaner is absolute ethanol, and use liquid nitrogen to cool the absolute ethanol to -20 °C.

[0056] Example 3: In this example, the preparation method of the CNTs / MXene / PI aerogel flexible conductive composite material based on the bionic structure design is carried out according to the following steps:

[0057] Step 1: Add 6.25 mg of nanocellulose (CNF) powder to 10 g of deionized water and stir magnetically until dissolved (takes 3 h), add 7.5 mg of monolayer MXene powder (Xinxi Technology Co., Ltd., monolayer Ti 3 C 2 T x powder), ultrasonicate until evenly dispersed (takes 10 min) under ultrasonic conditions (ultrasonic power is 200 W), then add 25 mg of CNTs, and ultrasonicate until evenly dispersed (takes 20 min) under ultrasonic conditions (ultrasonic power is 200 W) to obtain a mixed solution, and set it aside for use;

[0058] Step 2: Mix 50 mg of polyamic acid salt (PAAs) and 15 μl of TEA, and stir magnetically at a speed of 200 rpm / min for 4 h to obtain a PAAs solution.

[0059] Under nitrogen protection, add the mixed solution obtained in Step 1 to the PAAs solution obtained in Step 2, stir magnetically at a speed of 200 rpm / min for 3 h, transfer it to a mold using a disposable pipette, freeze it into a block, then freeze-dry it at -60 °C and 2 Pa for 72 h, place it in a tubular furnace, and then carry out imidization under argon protection with gradient heating to obtain the aerogel flexible conductive composite material;

[0060] In Step 3, the gradient heating process: Heat at a rate of 10 °C / min to 80 °C, hold for 30 min, heat at a rate of 10 °C / min to 150 °C, hold for 30 min, heat at a rate of 10 °C / min to 200 °C, hold for 30 min, heat at a rate of 10 °C / min to 250 °C, hold for 30 min, heat at a rate of 10 °C / min to 300 °C, hold for 30 min, heat at a rate of 10 °C / min to 350 °C, hold for 30 min.

[0061] In Step 3, the freezing method is ultrasonic freezing. Use an ultrasonic cleaner for ultrasonic freezing. The freezing liquid in the ultrasonic cleaner is absolute ethanol, and liquid nitrogen is used to cool the absolute ethanol to -20 °C.

[0062] Example 4: In this example, the preparation method of the CNTs / MXene / PI aerogel flexible conductive composite material based on the bionic structure design is carried out according to the following steps:

[0063] Step 1: Add 6.25 mg of nanocellulose (CNF) powder to 10 g of deionized water and stir magnetically until dissolved (it takes 3 h), add 10 mg of monolayer MXene powder (from Xinxi Technology Co., Ltd., monolayer Ti 3 C 2 T x powder), sonicate under ultrasonic conditions (ultrasonic power is 200 W) until uniformly dispersed (it takes 10 min), then add 25 mg of CNTs, and sonicate under ultrasonic conditions (ultrasonic power is 200 W) until uniformly dispersed (it takes 20 min) to obtain a mixed solution, and set it aside for use;

[0064] Step 2: After mixing 50 mg of polyamic acid salt (PAAs) and 15 μl of TEA, stir magnetically at a speed of 200 rpm for 4 h to obtain a PAAs solution.

[0065] Under nitrogen protection, add the mixed solution obtained in Step 1 to the PAAs solution obtained in Step 2, stir magnetically at a speed of 200 rpm for 3 h, transfer it to a mold using a disposable pipette, freeze it into a block, then freeze-dry it at -60 °C and 2 Pa for 72 h, place it in a tube furnace, and then perform imidization under argon protection with gradient heating to obtain the aerogel flexible conductive composite material (used as a flexible strain piezoresistive sensing material);

[0066] In Step 3, the gradient temperature increase process: increase the temperature at a rate of 10 °C / min to 80 °C, hold for 30 min, increase the temperature at a rate of 10 °C / min to 150 °C, hold for 30 min, increase the temperature at a rate of 10 °C / min to 200 °C, hold for 30 min, increase the temperature at a rate of 10 °C / min to 250 °C, hold for 30 min, increase the temperature at a rate of 10 °C / min to 300 °C, hold for 30 min, increase the temperature at a rate of 10 °C / min to 350 °C, hold for 30 min.

[0067] In Step 3, the freezing method is ultrasonic freezing. Use an ultrasonic cleaner for ultrasonic freezing. The freezing liquid in the ultrasonic cleaner is absolute ethanol, and use liquid nitrogen to cool the absolute ethanol to -20 °C.

[0068] Example 5: In this example, the preparation method of the CNTs / MXene / PI aerogel flexible conductive composite material based on the bionic structure design is carried out according to the following steps:

[0069] Step 1: Add 6.25 mg of nanocellulose (CNF) powder to 10 g of deionized water and stir magnetically until dissolved (takes 3 h), add 12.5 mg of monolayer MXene powder (Xinxi Technology Co., Ltd., monolayer Ti 3 C 2 T x powder), sonicate under ultrasonic conditions (ultrasonic power is 200 W) until evenly dispersed (takes 10 min), then add 25 mg of CNTs, and sonicate under ultrasonic conditions (ultrasonic power is 200 W) until evenly dispersed (takes 20 min) to obtain a mixed solution, and set it aside for use;

[0070] Step 2: Mix 50 mg of polyamic acid salt (PAAs) and 15 μl of TEA, and stir magnetically at a speed of 200 rpm / min for 4 h to obtain a PAAs solution.

[0071] Under nitrogen protection, add the mixed solution obtained in Step 1 to the PAAs solution obtained in Step 2, stir magnetically at a speed of 200 rpm / min for 3 h, transfer it to a mold using a disposable pipette, freeze it into a block, then freeze-dry it at -60 °C and 2 Pa for 72 h, place it in a tube furnace, and then perform imidization under argon protection with a gradient temperature increase to obtain the aerogel flexible conductive composite material;

[0072] In Step 3, the gradient heating process: Heat up at a rate of 10 °C / min to 80 °C, hold for 30 min, heat up at a rate of 10 °C / min to 150 °C, hold for 30 min, heat up at a rate of 10 °C / min to 200 °C, hold for 30 min, heat up at a rate of 10 °C / min to 250 °C, hold for 30 min, heat up at a rate of 10 °C / min to 300 °C, hold for 30 min, heat up at a rate of 10 °C / min to 350 °C, hold for 30 min.

[0073] In Step 3, the freezing method is ultrasonic freezing. Use an ultrasonic cleaner for ultrasonic freezing. The freezing liquid in the ultrasonic cleaner is absolute ethanol, and use liquid nitrogen to cool the absolute ethanol to -20 °C.

[0074] The scanning electron microscope image of CNTs-modified MXene is as Figure 1 shown. It can be seen from Figure 1 that a layer of CNTs is coated on the surface of MXene, and the conductive filler CNTs@MXene with a high conductivity and an anemone-like structure is obtained.

[0075] The flexible strain compression stress-strain curves of the composite aerogels prepared by the methods of Examples 1-5 are as Figure 2 shown. It can be seen from Figure 2 that the stress-strain curves of the composite aerogel materials show a trend of first decreasing and then increasing.

[0076] The sensitivity curve of the piezoresistive sensing material of the composite aerogel prepared by the method of Example 2 is as Figure 3 shown. It can be seen from Figure 3 that the prepared piezoresistive flexible strain sensor has a GF = 11.65 under a deformation of 0-5%, and as the deformation further increases, the GF value shows a downward trend.

[0077] The thousand-cycle stability curve of the flexible strain piezoresistive sensing material prepared by the method of Example 2 under 20% compressive deformation is as Figure 4 shown. It can be seen from Figure 4 that the composite aerogel shows stability under long-term cycling, without obvious data fluctuations. The peak change of the resistance is almost maintained at a stable level, and the signal hardly attenuates.

[0078] The specific embodiments of the present invention have been described above. It should be noted that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various deformations 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 CNTs / MXene / PI aerogel flexible conductive composite material based on bionic structure design, characterized in that: The following steps are involved: Step 1: Add nanocellulose (CNF) powder into deionized water and stir magnetically until dissolved, add MXene powder, ultrasonicate until evenly dispersed, then add CNTs, ultrasonicate until evenly dispersed, to obtain a mixed solution; Step 2: After mixing polyamic acid salt (PAAs) and TEA, stir magnetically for 2 h to 4 h to obtain a PAAs solution. Step 3: Add the mixed solution obtained in step 1 to the PAAs solution obtained in step 2, stir magnetically for 3 hours, pour into a mold, freeze into a block, freeze-dry, and then heat gradually under argon protection for imidization to obtain the aerogel flexible conductive composite material.

2. The method according to claim 1, characterized in that The polyamic acid salt described in step 2 is prepared according to the following steps: 4,4'-diaminodiphenyl ether (ODA) is dissolved in an organic solvent under nitrogen protection, and then 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (BPDA) is added, stirred in a 0° water bath for 6 hours, triethylamine (TEA) is added dropwise, and stirring is continued for 3h-4h after the addition is completed, and then slowly dripped into deionized water, and then stirred at high speed at room temperature, filtered out and repeatedly washed with deionized water, filtered out and frozen, and then freeze-dried to obtain polyamic acid salt.

3. The method according to claim 2, characterized in that The molar ratio of ODA, BPDA and TEA is 1:1.01:

1.

4. The method according to claim 2, characterized in that: The temperature of the deionized water used for cleaning was 0°C.

5. The method according to claim 1, characterized in that In step 1, the mass ratio of CNF, MXene and CNTs is 1:(0.4-2):

4.

6. The method according to claim 1, characterized in that In step 2, the molar ratio of polyamic acid salt (PAAs) to TEA is 1:

1.

7. The method according to claim 1, characterized in that In step 3, the mixed solution obtained in step 1 is added to the PAAs solution obtained in step 2 at a mass ratio of CNTs, MXene and PI of 0.25:(0.05-0.25):

1.

8. The method according to claim 1, characterized in that Gradient heating process: 80℃30min, 150℃30min, 200℃30min, 250℃30min, 300℃30min, 350℃30min.

9. An aerogel flexible conductive composite material prepared by the method according to any one of claims 1 to 8.

10. An aerogel flexible conductive composite material prepared by the method according to any one of claims 1 to 8, applied in the field of flexible sensing.

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