Preparation method of self-adaptive electromagnetic interference resistant composite material

Abstract

This invention discloses a method for preparing an adaptive electromagnetic interference-resistant composite material, comprising the following steps: First, preparing few-layer MXene powder by etching a Ti3AlC2 precursor with LiF / HCl solution; then preparing carbon nanotubes / Ti3C2T by chemical crosslinking. x MXene powder / chitosan / polyethyleneimine dispersion; finally, carbon nanotubes / Ti3C2T were obtained through a freeze-drying process. x MXene powder / chitosan / polyethyleneimine composite aerogel. Carbon nanotubes / Ti3C2T prepared in this invention. x The MXene powder / chitosan / polyethyleneimine composite aerogel exhibits excellent electromagnetic shielding performance and strong absorption capacity, meeting the application requirements of aerospace, electronic packaging, and other fields. It also possesses strain sensing capabilities, demonstrating outstanding sensitivity under different strains, good repeatability and linearity, and the ability to distinguish between different strain levels, making it suitable for scenarios requiring dynamic and quantitative strain monitoring. This composite material combines highly efficient electromagnetic shielding performance with excellent sensing properties, showing broad application prospects in practical applications.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of composite material preparation, and particularly relates to a preparation method of a self-adaptive electromagnetic interference resistant composite material. BACKGROUND

[0002] With the rapid development of communication technology and the wide popularity of wearable electronic products, electromagnetic radiation pollution problems are increasingly prominent. Electromagnetic radiation not only interferes with the normal operation of adjacent electronic equipment, but also poses a potential threat to human health and national security. Developing efficient electromagnetic shielding materials has become a key strategy to solve this problem. At the same time, the miniaturization and multi-functional integration requirements of electronic products have driven composite materials to develop towards "single material with multiple properties", especially in the fields of wearable devices, intelligent electronic skin and aerospace, composite materials with electromagnetic shielding and strain sensing functions have important application value.

[0003] Traditional electromagnetic shielding materials (such as metal thin films) have excellent shielding effectiveness, but have defects such as heavy weight, poor flexibility, and inability to integrate sensing functions. Carbon nanotubes (CNT) and Ti3C2Tx MXene as emerging one-dimensional / two-dimensional conductive fillers, due to their high electrical conductivity and unique layered structure, have become a research hotspot. CNT can build conductive paths, and the two-dimensional plane of MXene provides abundant conductive contact points, which can significantly improve the electrical conductivity of the material. However, MXene itself lacks gelation ability and is difficult to form a stable three-dimensional skeleton, limiting its application in complex environments.

[0004] The selection of the polymer matrix is crucial to the performance of the composite material. Carboxymethyl chitosan (CCS) has biocompatibility and functional group richness, but the aerogel prepared alone lacks flexibility and cannot meet the demand of dynamic strain monitoring. The flexible segment of polyethyleneimine (PEI) can endow the material with elasticity, but it needs to be modified through the interface to enhance the combination with inorganic fillers. Silane coupling agent KH560 can graft PEI to the surface of CCS through chemical cross-linking, optimize the cross-linking network density, and enhance the interface combination with CNT and MXene through hydrogen bonding to form a stable organic-inorganic composite system.

[0005] In the prior art, it is necessary to provide a preparation method of a self-adaptive electromagnetic interference resistant composite material to balance the electromagnetic shielding effectiveness and sensing performance of the composite material, and to improve the dispersion and interface compatibility of the filler. SUMMARY

[0006] The purpose of the present application is to provide a preparation method of an adaptive anti-electromagnetic interference composite material, by constructing a "one-dimensional CNT + two-dimensional MXene" synergistic conductive network, combining a PEI / CCS elastic matrix with KH560 interface modification, developing a composite aerogel with high-efficiency electromagnetic shielding (SET highest 36.96 dB) and wide-range strain sensing (10%~90% strain response), providing a new path for the design of multifunctional composite materials, and solving the problems in the prior art that the electromagnetic shielding performance of the composite material is not adjustable and the composite material is difficult to apply in special demand fields.

[0007] The technical principle adopted by the present application is that carbon nanotubes (CNT) and Ti3C2T x (MXene) as typical one-dimensional and two-dimensional conductive fillers are widely used in the preparation of various shielding materials due to their unique electrical properties and structural characteristics. However, MXene itself has weak gelation ability, and it is difficult to build a solid and stable three-dimensional skeleton structure in practical application, which limits the full play of its performance. In contrast, carboxylated carbon nanotubes (CNT) with high conductivity and high mechanical strength can effectively bridge MXene by constructing a conductive path, making up for its structural defects. The large two-dimensional planar structure of MXene can provide abundant conductive contact points and a wide conductive area, and the synergistic effect with CNT can make the conductive network more dense and perfect, greatly promoting electron transmission and significantly improving the electrical conductivity of the material, thereby enhancing the electromagnetic shielding effectiveness.

[0008] Carboxymethyl chitosan (CCS) as a natural polysaccharide has attracted much attention in related research fields due to its good biodegradability, hydrophilicity and rich functional groups. However, the aerogel prepared by using CCS alone has poor flexibility and is difficult to achieve accurate sensing in complex environments. Polyvinyl imidazole (PEI) as a water-soluble polyelectrolyte polymer containing primary amine, secondary amine and tertiary amine groups, its flexible molecular chain segment can endow the material with good elasticity and deformation recovery ability. By grafting PEI onto the surface of CCS through silane coupling agent (KH560), the crosslinking network density can be effectively controlled, and the elastic properties of the aerogel can be optimized. In addition, the rich hydroxyl groups on the surface of MXene can form hydrogen bonds with the amino groups of PEI and the hydroxyl groups of CCS, and the carboxyl groups of CNT can also form hydrogen bond interactions with the amino groups of PEI, the hydroxyl groups of CCS and MXene. The synergy of excellent elasticity and conductive network can realize the recognition and discrimination of external pressure signals by the aerogel, and meet the application of the aerogel as a flexible pressure-sensing in practice.

[0009] In summary, it is a potential innovative strategy to introduce conductive fillers with different dimensions (one-dimensional CNT and two-dimensional MXene) into the framework to construct a conductive network with the aid of CCS / PEI auxiliary framework, and then form a stable and excellent elastic three-dimensional composite aerogel. The synergistic effect of improved impedance matching and perfect conductive network of the composite aerogel makes it have excellent electromagnetic shielding efficiency; the excellent elasticity and the second coexistence of the conductive network can detect and identify external signals, which is expected to be used as flexible sensing. The simultaneous realization of electromagnetic shielding efficiency and flexible sensing performance realizes the multifunctionality of the composite aerogel, which lays a foundation for expanding its application field.

[0010] The technical scheme adopted by the present application is a preparation method of a self-adaptive anti-electromagnetic interference composite material, and the specific steps are as follows:

[0011] Step 1, using a replacement HF method (LiF and HCl mixed solution) to etch and remove the Al layer in the Ti3AlC2 precursor to prepare an accordion-shaped Ti3C2T x MXene powder;

[0012] Step 2, ultrasonic oscillation, centrifugal washing and freeze-drying are performed on the accordion-shaped powder to prepare single (few) layer Ti3C2T x MXene powder;

[0013] Step 3, dissolve chitosan (CCS) in deionized water to prepare a CCS aqueous solution with a concentration of 2wt%;

[0014] Step 4, a certain amount of KH560 is added to the 2wt% CCS aqueous solution for ultrasonic dispersion to obtain a KH560 / CCS mixed solution;

[0015] Step 5, a proper amount of PEI is added to the KH560 / CCS mixed solution and magnetic stirring is performed to obtain a KH560 / CCS / PEI mixed solution;

[0016] Step 6, a proper amount of CNT and few-layer MXene are added to the above KH560 / CCS / PEI mixed solution for ultrasonic stirring to prepare a composite material precursor solution;

[0017] Step 7, the composite material precursor solution is transferred to a mold, and then the mold is placed in an oven for crosslinking to obtain a pre-polymerized CNT / MXene / CCS / PEI mixed solution;

[0018] Step 8, the pre-polymerized CNT / MXene / CCS / PEI mixed solution is freeze-dried to obtain a CNT / MXene / CCS / PEI aerogel.

[0019] As a preferred, in step 1, the specific steps are as follows:

[0020] First, LiF and HCl are mixed to obtain a LiF / HCl solution, and then MAX phase precursor powder is slowly added to the LiF / HCl mixed solution under ice bath conditions to obtain a mixed solution; the mass ratio of LiF, HCl and MAX phase precursor powder is 1:15-20:1. The manufacturer of the MAX phase precursor powder (Ti3AlC2 powder) is Beijing Fosman Science and Technology Co., Ltd. The purity of the MAX phase precursor powder is 98%, and the particle size of the MAX phase precursor powder is 200-500 mesh.

[0021] Then, the mixed solution is continuously stirred magnetically at 35-45 degrees Celsius for 24-48 hours to obtain multi-layer Ti3C2T x MXene suspension, and then repeatedly centrifuged with deionized water until the solution pH is 6-7 to obtain an accordion-shaped Ti3C2T x MXene precipitate, which is Ti3C2T x MXene powder. During centrifugal washing, the centrifugal rate is 3500-4000 r / min.

[0022] As preferred, in step 2, the specific steps are as follows:

[0023] First, disperse the multi-layer Ti3C2T x MXene powder in deionized water, and ultrasonic treat for 15-20 min to promote the exfoliation of the multi-layer MXene, and then continue to centrifuge at a rate of 3500-4000 r / min for 15-20 min, for several cycles, and take the supernatant to obtain a few-layer MXene dispersion liquid;

[0024] Then, freeze-dry the few-layer MXene dispersion liquid obtained above in a freeze dryer to obtain a few-layer MXene powder.

[0025] As preferred, in step 3, the specific steps are as follows:

[0026] Under the action of magnetic stirring, carboxymethyl chitosan (CCS) is fully dissolved in deionized water to prepare a CCS aqueous solution. The magnetic stirring speed is 500-800 rpm / min, and the time is 1-2 hours.

[0027] As preferred, in step 4, the specific steps are as follows:

[0028] Add KH560 to the above CCS aqueous solution and magnetically stir at room temperature to obtain a KH560 / CCS mixed solution. The magnetic stirring speed is 500-800 rpm / min, and the time is 1-2 hours.

[0029] As preferred, in step 5, the specific steps are as follows:

[0030] Polyethyleneimine (PEI) is added to the uniformly mixed KH560 / CCS mixed solution, and a uniform KH560 / CCS / PEI mixed solution is obtained by ultrasonic stirring. The ultrasonic stirring power is 360 W, and the time is 1 hour.

[0031] As preferred, in step 6, the specific steps are as follows:

[0032] An appropriate amount of carboxylated carbon nanotubes (CNT) and MXene are added to the above-mentioned uniformly mixed KH560 / CCS / PEI mixed solution, and ultrasonic stirring is used to uniformly disperse them. The ultrasonic stirring power is 360-500 W, and the time is 2-3 hours. The mass ratio of CCS, PEI, CNT, MXene and deionized water is 1:0.4:1:0.5:0-1:49.

[0033] As preferred, in step 7, the specific steps are as follows:

[0034] First, the precursor solution is equally divided into a six-hole mold;

[0035] Then, the mold containing the precursor solution is transferred to an oven to promote crosslinking. Through crosslinking, a pre-polymerized CNT / MXene / CCS / PEI mixed solution is obtained. The oven temperature is set to 60-80 degrees Celsius, and the time is set to 3-5 hours.

[0036] As preferred, in step 8, the specific steps are as follows:

[0037] First, the six-hole mold containing the pre-polymerized CNT / MXene / CCS / PEI mixed solution is frozen at -50 to -60 degrees Celsius for 12-24 hours to obtain a CNT / MXene / CCS / PEI hydrogel;

[0038] Then, the CNT / MXene / CCS / PEI hydrogel is freeze-dried to obtain a CNT / MXene / CCS / PEI aerogel. The freeze-drying temperature is -60 to -80 degrees Celsius, and the time is 72-96 hours.

[0039] The beneficial effects of the present application are:

[0040] 1. The CNT / MXene / CCS / PEI composite aerogel prepared by the application realizes the synergistic integration of high-efficiency electromagnetic shielding and precise strain sensing performance. A three-dimensional conductive network is constructed by one-dimensional carbon nanotubes (CNT) and two-dimensional few-layer MXene, and the multiple reflection, scattering and polarization loss mechanisms of electromagnetic waves of the porous structure, and the electromagnetic shielding effectiveness (SET) can reach 36.96 dB, which is much higher than the commercial standard (20 dB), and can effectively meet the protection needs in strong electromagnetic environments such as aerospace, electronic packaging, etc. At the same time, the elastic network (PEI flexible chain segment + chemical cross-linking structure) of the aerogel and the conductive network synergistically act in the strain range of 10%~90%, and exhibit sensitive and linear current signal response, which can clearly distinguish different strain levels, and provide a new scheme for dynamic deformation monitoring of wearable devices.

[0041] 2. The application realizes the synergistic design of multi-dimensional fillers, one-dimensional CNT as a conductive bridge to compensate for the defects of insufficient gelation ability of MXene, and constructs an efficient electron transmission path; the large planar structure of two-dimensional few-layer MXene provides rich conductive contact points, and the two form a dense conductive network, which significantly improves the electrical conductivity of the material. At the same time, the silane coupling agent KH560 covalently connects carboxymethyl chitosan (CCS) and polyethyleneimine (PEI) through chemical cross-linking, and forms hydrogen bonds with the carboxyl group of CNT and the hydroxyl group of MXene, which effectively enhances the interfacial bonding force between inorganic fillers and organic matrix, inhibits the agglomeration of fillers, and improves the structural stability and conductive uniformity of the composite material.

[0042] 3. The application adopts a preparation process combining chemical cross-linking and freeze-drying, which is simple and controllable, does not require high temperature and high pressure or special equipment, and can be prepared through only 8 core steps. From LiF / HCl etching MXene to freeze-drying forming, the process parameters (such as etching temperature of 35~45℃, centrifugal speed of 3500~4000r / min, cross-linking temperature of 60~80℃, etc.) are clear and easy to reproduce, which ensures the consistency of batch production. In addition, LiF / HCl is used instead of the highly toxic HF for etching, which significantly improves the process safety, and the main raw materials (CCS, PEI, etc.) are all commercial and easily available materials, which are low in cost and have the feasibility of industrial production.

[0043] 4、The present application realizes the directional optimization of the electromagnetic shielding efficiency of the composite aerogel by flexibly regulating the content of MXene (0.1-1 times the mass of CCS): when the content of MXene is 0, the shielding efficiency is only 7.99 dB; when the content of MXene increases to 1, the shielding efficiency jumps to 36.96 dB, meeting the differentiated shielding needs in different scenarios. At the same time, the strain sensing performance of the aerogel can be adjusted by the filler ratio, and significant differences in current signal are shown in the low strain (10%) and high strain (90%) intervals, especially in the 70%-90% high strain interval, which is suitable for deformation monitoring under complex working conditions, such as human joint movement tracking or real-time stress detection of intelligent equipment.

[0044] 5、In terms of electromagnetic shielding mechanism, the composite aerogel optimizes impedance matching through porous structure, guides electromagnetic waves into the interior, and realizes efficient attenuation of electromagnetic waves through the synergistic effect of conductive loss (CNT / MXene), multiple reflection and scattering loss (three-dimensional network) and polarization loss (heterogeneous interface). In terms of strain sensing mechanism, the flexible molecular chain segments of PEI give the aerogel high elasticity (can withstand 90% strain), and the conductive network can be reconstructed reversibly during deformation, while the protonated amino groups of PEI fix CNT / MXene through electrostatic adsorption, ensuring the stability of the conductive path, so that the aerogel can maintain sensitive current signal response in compression or stretching state, providing a reliable theoretical basis for the design of multifunctional composite materials. BRIEF DESCRIPTION OF DRAWINGS

[0045] Figure 1 is the total electromagnetic shielding efficiency (SE T ) of the CNT / MXene / CCS / PEI composite aerogel under different MXene contents in the method of the present application;

[0046] Figure 2 is the SE A of the CNT / MXene / CCS / PEI composite aerogel under different MXene contents in the method of the present application;

[0047] Figure 3 is the SE R of the CNT / MXene / CCS / PEI composite aerogel under different MXene contents in the method of the present application;

[0048] Figure 4 is the current signal response curve of the CNT / MXene / CCS / PEI composite aerogel under different MXene contents in the method of the present application. DETAILED DESCRIPTION

[0049] The technical solutions of the present application will be described clearly and completely below in combination with specific embodiments and drawings. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0050] Embodiment 1

[0051] The embodiment provides a preparation method of an adaptive anti-electromagnetic interference composite material, and the specific steps are as follows:

[0052] Step 1, using a replacement HF method (LiF and HCl mixed solution) to etch and remove the Al layer in the Ti3AlC2 precursor to prepare an accordion-shaped Ti3C2T x MXene powder, and the specific steps are as follows:

[0053] First, LiF and HCl are fully mixed to obtain a LiF / HCl solution, and then MAX phase precursor powder is slowly added to the LiF / HCl mixed solution under ice bath conditions to obtain a mixed solution;

[0054] The mass ratio of LiF, HCl and MAX phase precursor powder is 1:15:1.

[0055] The purity of the MAX phase precursor powder (Ti3AlC2 powder) is 98%, and the particle size of the MAX phase precursor powder is 200 mesh.

[0056] Then, the mixed solution is continuously magnetically stirred at 35°C for 24 hours to obtain multi-layer Ti3C2T x suspension, and then repeatedly centrifuged and washed with deionized water until the solution pH is 6 to obtain an accordion-shaped Ti3C2T x precipitate; during centrifugal washing, the centrifugal speed is 3500r / min.

[0057] Step 2, ultrasonic oscillation, centrifugal washing and freeze-drying are performed on the accordion-shaped powder to prepare single (few) layer Ti3C2T x MXene powder, and the specific steps are as follows:

[0058] First, the multi-layer Ti3C2T x precipitate is dispersed in deionized water and ultrasonically treated for 15 min to promote the exfoliation of the multi-layer MXene, and then centrifuged at a speed of 3500r / min for 15 min for several cycles, and the supernatant is taken to obtain a few-layer MXene dispersion liquid;

[0059] Then, the few-layer MXene dispersion liquid obtained above is freeze-dried in a freeze dryer to obtain a few-layer MXene powder.

[0060] Step 3, dissolve chitosan (CCS) in deionized water to prepare a 2wt% CCS aqueous solution, the specific steps are as follows:

[0061] Under the action of magnetic stirring, carboxymethyl chitosan (CCS) is fully dissolved in deionized water to prepare a CCS aqueous solution. The magnetic stirring speed is 500 rpm / min, and the time is 1 hour.

[0062] Step 4, add a certain amount of KH560 to the 2wt% CCS aqueous solution and ultrasonic dispersion to obtain a KH560 / CCS mixed solution, the specific steps are as follows:

[0063] Add 5% of the mass of chitosan KH560 to the above CCS aqueous solution and magnetically stir at room temperature to obtain a uniform KH560 / CCS mixed solution. The magnetic stirring speed is 500 rpm / min, and the time is 1 hour.

[0064] Step 5, add an appropriate amount of PEI to the KH560 / CCS mixed solution and magnetically stir to obtain a KH560 / CCS / PEI mixed solution, the specific steps are as follows:

[0065] Add polyethyleneimine (PEI) to the uniform KH560 / CCS mixed solution, and the addition amount of polyethyleneimine is 40% of the mass of chitosan. Through ultrasonic stirring, a uniform KH560 / CCS / PEI mixed solution is obtained. The ultrasonic stirring power is 360W, and the time is 1 hour.

[0066] Step 6, add an appropriate amount of CNT and few-layer MXene to the above KH560 / CCS / PEI mixed solution and ultrasonic stir to prepare a composite precursor solution, the specific steps are as follows:

[0067] Add an appropriate amount of carboxylated carbon nanotubes (CNT) and MXene to the above uniform KH560 / CCS / PEI mixed solution and ultrasonic stir to make it uniformly dispersed. The ultrasonic stirring power is 360W, and the time is 2 hours. The mass ratio of CCS, PEI, CNT, MXene and deionized water is 1:0.4:1:0.1:49.

[0068] Step 7, transfer the composite precursor solution to the mold, then put the mold into the oven for crosslinking to obtain a pre-polymerized CNT / MXene / CCS / PEI mixed solution, the specific steps are as follows:

[0069] First, divide the mixed solution into six-hole molds;

[0070] Then, the mold containing the mixed solution is transferred to an oven to promote crosslinking. Through crosslinking, a pre-polymerized CNT / MXene / CCS / PEI mixed solution is obtained. The oven temperature is set to 60 degrees Celsius, and the time is set to 3 hours.

[0071] Step 8, the pre-polymerized CNT / MXene / CCS / PEI mixed solution is freeze-dried to obtain a CNT / MXene / CCS / PEI aerogel.

[0072] First, the six-hole mold containing the pre-polymerized CNT / MXene / CCS / PEI mixed solution is frozen at -50 degrees Celsius for 12 hours to obtain a CNT / MXene / CCS / PEI hydrogel;

[0073] Then, the CNT / MXene / CCS / PEI hydrogel is freeze-dried to obtain a CNT / MXene / CCS / PEI aerogel.

[0074] The freeze-drying temperature is -60 degrees Celsius, and the time is 72 hours.

[0075] The electromagnetic shielding effectiveness of the CNT / MXene / CCS / PEI composite aerogel prepared in Example 1 is 21.99 dB, which has reached the requirement of commercial electromagnetic shielding application (20 dB).

[0076] Example 2

[0077] The present embodiment provides a preparation method of a self-adaptive anti-electromagnetic interference composite material, and the specific steps are as follows:

[0078] Step 1, using the replacement HF method (LiF and HCl mixed solution) to etch and remove the Al layer in the Ti3AlC2 precursor to prepare an accordion-shaped Ti3C2T x MXene powder, and the specific steps are as follows:

[0079] First, LiF and HCl are fully mixed to obtain a LiF / HCl solution, and then MAX phase precursor powder is slowly added to the LiF / HCl mixed solution under ice bath conditions to obtain a mixed solution;

[0080] The mass ratio of LiF, HCl and MAX phase precursor powder is 1:18:1.

[0081] The purity of the MAX phase precursor powder is 98%, and the particle size of the MAX phase precursor powder is 350 mesh.

[0082] Then, the mixed solution is continuously stirred with a magnetic force at 40°C for 36 hours to obtain a multi-layer Ti3C2T xThe suspension was then repeatedly centrifuged and washed with deionized water until the pH of the solution was 6.5 to obtain the accordion-shaped Ti3C2T x The precipitate was centrifuged at a rate of 3750 r / min.

[0083] Step 2, the accordion-shaped powder was ultrasonically vibrated, centrifugally washed, and freeze-dried to prepare single (few) layer Ti3C2T x The MXene powder was prepared according to the following specific steps:

[0084] First, the multi-layer Ti3C2T x The precipitate was dispersed in deionized water and ultrasonically treated for 18 min to promote the exfoliation of the multi-layer MXene, and then centrifuged at a rate of 3750 r / min for 18 min for several cycles. The supernatant was taken to obtain a few-layer MXene dispersion;

[0085] Then, the few-layer MXene dispersion obtained above was freeze-dried in a freeze dryer to obtain a few-layer MXene powder.

[0086] Step 3, chitosan (CCS) was dissolved in deionized water to prepare a 2wt% CCS aqueous solution according to the following specific steps:

[0087] Under the action of magnetic stirring, carboxymethyl chitosan (CCS) was fully dissolved in deionized water to prepare a CCS aqueous solution. The magnetic stirring speed was 650 rpm / min, and the time was 1.5 hours.

[0088] Step 4, a certain amount of KH560 was added to the 2wt% CCS aqueous solution and ultrasonically dispersed to obtain a KH560 / CCS mixed solution, according to the following specific steps:

[0089] KH560 was added to the above CCS aqueous solution and magnetically stirred at room temperature to obtain a uniform KH560 / CCS mixed solution. The magnetic stirring speed was 650 rpm / min, and the time was 1.5 hours.

[0090] Step 5, a proper amount of PEI was added to the KH560 / CCS mixed solution and magnetically stirred to obtain a KH560 / CCS / PEI mixed solution, according to the following specific steps:

[0091] Polyethyleneimine (PEI) was added to the uniform KH560 / CCS mixed solution and ultrasonically stirred to obtain a uniform KH560 / CCS / PEI mixed solution. The ultrasonic stirring power was 360 W, and the time was 1 hour.

[0092] Step 6, add an appropriate amount of CNT and few-layer MXene to the above KH560 / CCS / PEI mixed solution and stir ultrasonically to prepare a composite precursor solution, and the specific steps are as follows:

[0093] An appropriate amount of carboxylated carbon nanotubes (CNT) and MXene are added to the above uniform KH560 / CCS / PEI mixed solution, and are uniformly dispersed by ultrasonic stirring. The ultrasonic stirring power is 420 W, and the time is 2.5 hours. The mass ratio of CCS, PEI, CNT, MXene and deionized water is 1:0.4:1:0.5:49.

[0094] Step 7, transfer the composite precursor solution to a mold, and then place the mold in an oven for crosslinking to obtain a pre-polymerized CNT / MXene / CCS / PEI mixed solution, and the specific steps are as follows:

[0095] First, the mixed solution is equally divided into a six-hole mold;

[0096] Then, the mold containing the mixed solution is transferred to an oven to promote crosslinking. By crosslinking, a pre-polymerized CNT / MXene / CCS / PEI mixed solution is obtained. The oven temperature is set to 70 degrees Celsius, and the time is set to 4 hours.

[0097] Step 8, the pre-polymerized CNT / MXene / CCS / PEI mixed solution is freeze-dried to obtain a CNT / MXene / CCS / PEI aerogel.

[0098] First, the six-hole mold containing the pre-polymerized CNT / MXene / CCS / PEI mixed solution is frozen at -55 degrees Celsius for 18 hours to obtain a CNT / MXene / CCS / PEI hydrogel;

[0099] Then, the CNT / MXene / CCS / PEI hydrogel is freeze-dried to obtain a CNT / MXene / CCS / PEI aerogel.

[0100] The freeze-drying temperature is -70 degrees Celsius, and the time is 84 hours.

[0101] Compared with the commercial electromagnetic shielding material (20 dB), the electromagnetic shielding efficiency of the CNT / MXene / CCS / PEI composite aerogel prepared in Example 2 is 37.56 dB, which is increased by 87.8%.

[0102] Example 3

[0103] The preparation method of the self-adaptive anti-electromagnetic interference composite material is as follows:

[0104] Step 1, using the replacement HF method (LiF and HCl mixed solution) to etch and remove the Al layer in the Ti3AlC2 precursor to prepare the accordion-shaped Ti3C2T x MXene powder, the specific steps are as follows:

[0105] First, mix LiF and HCl to obtain a LiF / HCl solution, then slowly add the MAX phase precursor powder to the LiF / HCl mixed solution under ice bath conditions to obtain a mixed solution;

[0106] The mass ratio of LiF, HCl and MAX phase precursor powder is 1:20:1.

[0107] The purity of the MAX phase precursor powder is 98%, and the particle size of the MAX phase precursor powder is 500 mesh.

[0108] Then, continuously magnetically stir the mixed solution at 45 degrees Celsius for 48 hours to obtain multi-layer Ti3C2T x suspension, then repeatedly centrifugal wash with deionized water until the solution pH is 7 to obtain accordion-shaped Ti3C2T x precipitate; the centrifugal rate is 4000r / min during centrifugal washing.

[0109] Step 2, ultrasonic oscillation, centrifugal washing and freeze-drying of the accordion-shaped powder to prepare single (few) layer Ti3C2T x MXene powder, the specific steps are as follows:

[0110] First, disperse the multi-layer Ti3C2T x precipitate in deionized water, ultrasonic treatment for 20 min to promote the exfoliation of multi-layer MXene, then continue to centrifuge at a speed of 4000r / min for 20 min, cycle several times, take the supernatant to obtain a few-layer MXene dispersion liquid;

[0111] Then, freeze-dry the few-layer MXene dispersion liquid obtained above in a freeze dryer to obtain a few-layer MXene powder.

[0112] Step 3, dissolve chitosan (CCS) in deionized water to prepare a 2wt% CCS aqueous solution, the specific steps are as follows:

[0113] Under the action of magnetic stirring, the carboxymethyl chitosan (CCS) is fully dissolved in deionized water to prepare a CCS aqueous solution. The magnetic stirring speed is 800rpm / min, and the time is 2 hours.

[0114] Step 4, add a certain amount of KH560 to the 2wt% CCS aqueous solution and ultrasonic disperse to obtain a KH560 / CCS mixed solution, the specific steps are as follows:

[0115] KH560 was added to the above CCS aqueous solution, and magnetic stirring was carried out at room temperature to obtain a KH560 / CCS uniform mixed solution. The magnetic stirring speed was 800 rpm / min, and the time length was 2 hours.

[0116] Step 5, a proper amount of PEI was added to the KH560 / CCS mixed solution and magnetic stirring was carried out to obtain a KH560 / CCS / PEI mixed solution. The specific steps are as follows:

[0117] Polyethyleneimine (PEI) was added to the uniform mixed KH560 / CCS mixed solution, and ultrasonic stirring was carried out to obtain a uniform KH560 / CCS / PEI mixed solution. The ultrasonic stirring power was 360 W, and the time length was 1 hour.

[0118] Step 6, a proper amount of CNT and few-layer MXene were added to the above KH560 / CCS / PEI mixed solution and ultrasonic stirring was carried out to prepare a composite precursor solution. The specific steps are as follows:

[0119] A proper amount of carboxylated carbon nanotubes (CNT) and MXene were added to the above uniform KH560 / CCS / PEI mixed solution, and ultrasonic stirring was carried out to uniformly disperse them. The ultrasonic stirring power was 500 W, and the time length was 3 hours. The mass ratio of CCS, PEI, CNT, MXene and deionized water was 1:0.4:1:1:49.

[0120] Step 7, the composite precursor solution was transferred to a mold, and then the mold was placed in an oven for crosslinking to obtain a pre-polymerized CNT / MXene / CCS / PEI mixed solution. The specific steps are as follows:

[0121] First, the mixed solution was equally transferred to a six-hole mold;

[0122] Then, the mold containing the mixed solution was transferred to an oven to promote crosslinking. Through crosslinking, a pre-polymerized CNT / MXene / CCS / PEI mixed solution was obtained. The oven temperature was set to 80 degrees Celsius, and the time was set to 5 hours.

[0123] Step 8, the pre-polymerized CNT / MXene / CCS / PEI mixed solution was freeze-dried to obtain a CNT / MXene / CCS / PEI aerogel.

[0124] First, the six-hole mold containing the pre-polymerized CNT / MXene / CCS / PEI mixed solution was frozen at -60 degrees Celsius for 24 hours to obtain a CNT / MXene / CCS / PEI hydrogel;

[0125] Then, the CNT / MXene / CCS / PEI hydrogel was freeze-dried to obtain CNT / MXene / CCS / PEI aerogel. The freeze-drying temperature was -80 degrees Celsius and the time was 96 hours.

[0126] Compared to commercially available electromagnetic shielding materials (20dB), the electromagnetic shielding effectiveness of the CNT / MXene / CCS / PEI composite aerogel prepared in Example 3 is 57.96dB, which is 189.8% higher.

[0127] The composite aerogels prepared in Examples 1-3 of this invention exhibit different performance characteristics under different MXene contents. For example... Figure 1 As shown, the SE of the CNT / MXene / CCS / PEI composite aerogel T As shown in the figure, the electromagnetic shielding effectiveness increases with the increase of MXene content in CNT / MXene / CCS / PEI composite aerogel. This is because a more complete conductive network is formed inside the composite aerogel with a high filler content. Figure 2 and Figure 3 SE of CNT / MXene / CCS / PEI composite aerogels at different MXene contents A and SE R The diagram shows that:

[0128] (1) SE A and SE R All increased with increasing MXene content. SE A The improvement is mainly due to the enhanced multiple reflection and scattering within the composite aerogel at high MXene content, resulting in increased SE. R The improvement is mainly attributed to the severe impedance mismatch caused by high MXene content.

[0129] (2) Compare SE A and SE R It can be observed that, at the same MXene content, SE A Much higher than SE R This indicates that SE A It is SE T The main source of contribution. Figure 4 The figures show the current signal response curves of the composite aerogel under different strains. It can be seen that the current signal increases with increasing strain, and the signal difference between low strain (e.g., 10%) and high strain (e.g., 90%) is significant, clearly distinguishing strains of different magnitudes and meeting the practical application requirements of this sensor. Meanwhile, in the high strain range (70%, 90%), the rising slope and amplitude of the signal are significantly higher than those at low strain, indicating that the prepared composite aerogel, when used as a sensor, can effectively resolve a wide range of strains.

[0130] The mechanism of the method of the present application is as follows:

[0131] (1) Electromagnetic shielding: When electromagnetic waves are incident on the CNT / MXene / CCS / PEI composite aerogel with a three-dimensional conductive network structure, the synergistic effect of the porous structure on the surface of the material and the three-dimensional conductive network can significantly optimize the impedance matching performance, making the incident electromagnetic waves easily enter the interior of the composite aerogel for dissipation and attenuation. The electromagnetic waves entering the interior rely on the internal multiple reflection scattering of the pore wall and the coupling effect of the multi-dimensional (one-dimensional CNT and two-dimensional MXene) conductive network to strengthen the dissipation of electromagnetic wave energy, thereby maximizing the dissipation of electromagnetic waves. In addition, the introduction of MXene and CNT forms a large number of heterojunctions in the interior of the composite aerogel, inducing the generation of polarization loss (interface polarization and dipole polarization) and further attenuating the electromagnetic waves. The combined effect of improved impedance matching and multiple dissipation mechanisms endows the prepared composite aerogel with excellent electromagnetic shielding performance.

[0132] (2) Flexible sensing: The silanol generated by the hydrolysis of KH560 undergoes dehydration condensation to form siloxane, which undergoes ring-opening reaction with PEI and CCS at 60 degrees Celsius to form chemical cross-linking, while the carboxyl groups of CNT-COOH and the amino groups of PEI and the hydroxyl groups of CCS form hydrogen bonding forces, thereby enhancing the structural strength of the composite aerogel. In addition, the amino groups on the surface of PEI are easily protonated and exhibit a cationic state, which, under the action of electrostatic adsorption, makes the conductive fillers (CNT and MXene) more stable in combination with the polymer matrix, thereby helping to improve the electrical properties and mechanical strength of the composite aerogel, and the composite aerogel is expected to be applied as a compression-type flexible strain sensor in practice.

[0133] Comparative Example 1

[0134] The difference between Comparative Example 1 and Example 1 is only that no Ti3C2T x Addition of MXene powder.

[0135] The present comparative example provides a preparation method of a self-adaptive electromagnetic interference resistant composite material, and the specific steps are as follows:

[0136] Step 1: Dissolve chitosan (CCS) in deionized water to prepare a CCS aqueous solution with a concentration of 2wt%, and the specific steps are as follows:

[0137] Under the action of magnetic stirring, carboxymethyl chitosan (CCS) is fully dissolved in deionized water to prepare a CCS aqueous solution. The magnetic stirring speed is 500 rpm / min, and the time is 1 hour.

[0138] Step 2: Add a certain amount of KH560 to the 2wt% CCS aqueous solution and perform ultrasonic dispersion to obtain a KH560 / CCS mixed solution, and the specific steps are as follows:

[0139] KH560 was added to the above CCS aqueous solution, and magnetic stirring was performed at room temperature to obtain a KH560 / CCS uniform mixed solution. The magnetic stirring speed was 500 rpm / min, and the time length was 1 hour.

[0140] Step 3, a proper amount of PEI was added to the KH560 / CCS mixed solution and magnetic stirring was performed to obtain a KH560 / CCS / PEI mixed solution. The specific steps are as follows:

[0141] Polyethyleneimine (PEI) was added to the uniform KH560 / CCS mixed solution, and ultrasonic stirring was performed to obtain a uniform KH560 / CCS / PEI mixed solution. The ultrasonic stirring power was 360 W, and the time length was 1 hour.

[0142] Step 4, a proper amount of CNT was added to the above KH560 / CCS / PEI mixed solution and ultrasonic stirring was performed to prepare a composite precursor solution. The specific steps are as follows:

[0143] A proper amount of carboxylated carbon nanotubes (CNT) was added to the above uniform KH560 / CCS / PEI mixed solution, and ultrasonic stirring was performed to uniformly disperse it. The ultrasonic stirring power was 360 W, and the time length was 2 hours. The mass ratio of CCS, PEI, CNT and deionized water was 1:0.4:1:0.5:49.

[0144] Step 5, the composite precursor solution was transferred to a mold, and then the mold was placed in an oven for crosslinking to obtain a pre-polymerized CNT / CCS / PEI mixed solution. The specific steps are as follows:

[0145] First, the mixed solution was equally transferred to a six-hole mold;

[0146] Then, the mold containing the mixed solution was transferred to an oven to promote crosslinking. Through crosslinking, a pre-polymerized CNT / CCS / PEI mixed solution was obtained. The oven temperature was set to 60 degrees Celsius, and the time was set to 3 hours.

[0147] Step 6, the pre-polymerized CNT / CCS / PEI mixed solution was freeze-dried to obtain a CNT / CCS / PEI aerogel.

[0148] First, the six-hole mold containing the pre-polymerized CNT / CCS / PEI mixed solution was frozen at -50 degrees Celsius for 12 hours to obtain a CNT / CCS / PEI hydrogel;

[0149] Then, the CNT / CCS / PEI hydrogel was freeze-dried to obtain a CNT / CCS / PEI aerogel.

[0150] The freeze-drying temperature was -60 degrees Celsius and the duration was 72 hours.

[0151] The electromagnetic shielding effectiveness of the CNT / CCS / PEI composite aerogel prepared in Comparative Example 1 was 7.99 dB, which failed to meet the requirement of commercial electromagnetic shielding application (20 dB).

[0152] It will be obvious to a person skilled in the art that, without departing from the scope of the present application, the application is not limited to the details of the above-described exemplary embodiments, and that it can be implemented in other concrete forms. Consequently, in light of the foregoing disclosure, the embodiments disclosed herein should be regarded as being in all respects only exemplary, and should not be limiting on the scope of the application, which is defined by the appended claims rather than the above description and should be interpreted to encompass all alternatives falling within the meaning and scope of the equivalents of the claims.

Claims

1. A method for preparing an adaptive electromagnetic interference-resistant composite material, characterized in that, Includes the following steps: Step 1: Use a mixture of LiF and HCl to etch and remove the Al layer from the Ti3AlC2 precursor to prepare Ti3C2T. x MXene powder; Step 2, for Ti3C2T x MXene powder was subjected to ultrasonic vibration, centrifugal washing, and freeze-drying to prepare 2-10 layers of few-layer Ti3C2T. x MXene powder; Step 3: Dissolve chitosan in deionized water to prepare a 2wt% chitosan aqueous solution. The chitosan is carboxymethyl chitosan. Under magnetic stirring, the carboxymethyl chitosan is fully dissolved in the deionized water. Step 4: Add an appropriate amount of silane coupling agent to a 2wt% chitosan aqueous solution and disperse it ultrasonically to obtain a silane coupling agent / chitosan mixed solution. The silane coupling agent is KH560, and the amount of KH560 added is 5% to 10% of the chitosan mass. Step 5: Add an appropriate amount of polyethyleneimine to the silane coupling agent / chitosan mixed solution and stir magnetically to obtain the silane coupling agent / chitosan / polyethyleneimine mixed solution. Step 6: Add an appropriate amount of carbon nanotubes and Ti3C2T x MXene powder was added to the silane coupling agent / chitosan / polyethyleneimine mixed solution prepared in step five and ultrasonically stirred to obtain the precursor solution of the composite material. Step 7: Transfer the precursor solution into a mold, then place the mold in an oven to allow the precursor solution to undergo a cross-linking reaction, thus obtaining prepolymerized carbon nanotubes / Ti3C2T. x The MXene powder / chitosan / polyethyleneimine mixed solution specifically includes the following steps: a) Transfer the precursor solution into a six-hole mold in equal portions; b) Transfer the mold containing the precursor solution to an oven to promote cross-linking. Through cross-linking, prepolymerized carbon nanotubes / Ti3C2T are obtained. x MXene powder / chitosan / polyethyleneimine mixed solution; The oven temperature is set to 60-80 degrees Celsius, and the time is set to 3-5 hours. Step 8: Combine the prepolymerized carbon nanotubes / Ti3C2T x Carbon nanotubes / Ti3C2T were prepared by freeze-drying a mixed solution of MXene powder, chitosan, and polyethyleneimine. x MXene powder / chitosan / polyethyleneimine mixed solution aerogel; The carbon nanotubes are carboxylated carbon nanotubes.

2. The method for preparing an adaptive electromagnetic interference-resistant composite material according to claim 1, characterized in that, Step one includes the following steps: a) Mix LiF with HCl solution thoroughly, and then slowly add Ti3AlC2 precursor powder under ice bath conditions to obtain a mixed solution; The mass ratio of LiF, HCl, and Ti3AlC2 precursor powder is 1:15 to 20:

1. The purity of the Ti3AlC2 precursor powder is 98%, and the particle size is 200~500 mesh. b) The mixed solution obtained in step a) is continuously magnetically stirred at 35-45 degrees Celsius for 24-48 hours to obtain multilayer Ti3C2T. x The suspension was then repeatedly centrifuged and washed with deionized water until the pH of the solution reached 6-7, yielding Ti3C2T. x The precipitate is Ti3C2T. x MXene powder; During centrifugal washing, the centrifugation rate is 3500~4000 r / min.

3. The method for preparing an adaptive electromagnetic interference-resistant composite material according to claim 1, characterized in that, Step two includes the following steps: a) Ti3C2T x MXene powder was dispersed in deionized water and ultrasonically treated for 15-20 minutes to promote the formation of Ti3C2T. x The MXene powder was peeled off, and then centrifuged at 3500-4000 r / min for 15-20 min, repeated several times. The supernatant was collected to obtain a few-layer Ti3C2T. x MXene powder dispersion; b) The few-layer Ti3C2T obtained above x The MXene powder dispersion was freeze-dried in a freeze dryer to obtain a few-layer Ti3C2T. x MXene powder.

4. The method for preparing an adaptive electromagnetic interference-resistant composite material according to claim 1, characterized in that, In step three, the magnetic stirring speed is 500~800 rpm / min, and the duration is 1~2 hours.

5. The method for preparing an adaptive electromagnetic interference-resistant composite material according to claim 1, characterized in that, In step four, KH560 is added to the carboxymethyl chitosan aqueous solution prepared in step three, and the mixture is magnetically stirred at room temperature to obtain a KH560 / chitosan mixed solution. The magnetic stirring speed is 500~800 rpm / min, and the duration is 1~2 hours.

6. The method for preparing an adaptive electromagnetic interference-resistant composite material according to claim 1, characterized in that, In step five, polyethyleneimine is added to a uniformly mixed KH560 / chitosan solution, and a uniform KH560 / chitosan / polyethyleneimine solution is obtained by ultrasonic stirring. The amount of polyethyleneimine added is 40% of the mass of chitosan, the ultrasonic stirring power is 360W, and the duration is 1 hour.

7. The method for preparing an adaptive electromagnetic interference-resistant composite material according to claim 6, characterized in that, In step six, an appropriate amount of carboxylated carbon nanotubes and Ti3C2T are added. x MXene powder was added to the above uniform KH560 / chitosan / polyethyleneimine mixed solution and then ultrasonically stirred to disperse it evenly. The ultrasonic stirring power is 360~500W, and the duration is 2~3 hours; Chitosan, polyethyleneimine, carbon nanotubes, Ti3C2T x The mass ratio of MXene powder to deionized water is 1:0.4:1:0.1~1:

49.

8. The method for preparing an adaptive electromagnetic interference-resistant composite material according to claim 1, characterized in that, Step eight includes the following steps: a) Packing prepolymerized carbon nanotubes / Ti3C2T x Carbon nanotubes / Ti3C2T were obtained by freezing a mixed solution of MXene powder / chitosan / polyethyleneimine in a six-hole mold at -50 to -60 degrees Celsius for 12 to 24 hours. x MXene powder / chitosan / polyethyleneimine hydrogel; b) Carbon nanotubes / Ti3C2T x MXene powder / chitosan / polyethyleneimine hydrogel was freeze-dried to obtain carbon nanotubes / Ti3C2T. x MXene powder / chitosan / polyethyleneimine aerogel; The freeze-drying temperature is -60 to -80 degrees Celsius, and the duration is 72 to 96 hours.

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