A preparation method of a PDMS-AgNW / MXene / AgNW composite film

Abstract

The present application relates to a kind of preparation methods of PDMS-AgNW / MXene / AgNW composite film, it includes the following steps, S1 AgNW aqueous solution and MXene aqueous solution are alternately passed through vacuum-assisted filtration each other, after assembly is completed, post-processing is obtained AgNW / MXene / AgNW film;S2 PDMS is pre-cured in the presence of curing agent, and PDMS film is obtained;S3 the PDMS film obtained by S2 is transferred to at least one side surface of the AgNW / MXene / AgNW film obtained by S1, after bonding is completed, post-processing is obtained PDMS-AgNW / MXene / AgNW composite film.The present application realizes the purpose of high electromagnetic interference shielding, high mechanical stability and integrated excellent strain sensing function using ultrathin functional layer, realizes the application of composite film in electromagnetic interference shielding and human motion detection field.

Description

Technical Field

[0001] This invention relates to the technical field of electromagnetic shielding materials, and in particular to a method for preparing a PDMS-AgNW / MXene / AgNW composite film. Background Technology

[0002] Sensors are important devices that convert chemical, physical, and biological stimuli from the external environment into electrical signals that can be recognized by circuits or systems. Strain sensors are an important type of sensor; they deform under external force, causing changes in their resistance or capacitance, and thus monitor the magnitude of strain. In recent years, with the rise and development of flexible electronics, flexible strain sensors, with their good stability, high sensitivity, and considerable repeatability, have shown great promise in personal healthcare, human motion detection, and soft robotics. Furthermore, the rapid development of computer information and the Internet of Things has quickly made flexible strain sensors a research hotspot.

[0003] To achieve whole-body monitoring, numerous flexible strain sensors with specially designed structures have been developed. While improving people's living standards, these sensors also generate significant electromagnetic radiation and interference, severely impacting data accuracy and communication quality, and even threatening human health. Furthermore, the complex design structure exponentially increases the difficulty of fabricating the membrane materials on these flexible strain sensors, making it challenging to simultaneously achieve high electromagnetic interference shielding, high mechanical stability, and excellent integrated strain sensing functionality. This makes their commercial application extremely difficult.

[0004] Currently, significant progress has been made in the preparation of materials based on AgNW (silver nanowires) and MXene (transition metal carbides, nitrides, or carbonitrides). For example, Chinese Patent CN113913952B discloses a sandwich-structured polyimide-based electromagnetic shielding film, comprising an outer layer and an intermediate layer; the outer layer is a composite fiber of silver nanowires and polyimide, and the intermediate layer is an MXene thin layer; Chinese Patent CN111132533B discloses an MXene / silver nanowire composite electromagnetic shielding film, wherein the composite electromagnetic shielding film is made of MXene, silver nanowires, and a binder; wherein the mass ratio of MXene to silver nanowires is 0.05~20, and the mass amount of binder is 0.001~10% of the total mass amount of MXene and silver nanowires; Chinese Patent CN110993145B discloses a method for preparing a stretchable flexible conductive composite material, comprising: 1) mixing a silver nanowire solution and a stabilizer solution, adding an organic solvent, and mixing to form an emulsion; 2) freeze-drying the emulsion to obtain a silver nanowire content of 5~100 mg / cm³. 33) Dilute polydimethylsiloxane with an organic solvent to obtain a polydimethylsiloxane diluent; 4) Mix the silver nanowire aerogel with the polydimethylsiloxane diluent, evacuate the air, and then solidify to obtain a stretchable flexible conductive composite material.

[0005] The shortcomings of the existing technologies are as follows: 1) The functional layer thickness of the aforementioned films is relatively large, generally around tens of micrometers, making it difficult to achieve efficient electromagnetic interference shielding with extremely thin functional layer thicknesses; 2) While simple film structures can achieve considerable shielding efficiency at relatively thin thicknesses, their poor mechanical stability hinders functional expansion, especially making them unsuitable for strain sensing integration; 3) Polymer films based on conductive fillers struggle to overcome the issue of a high proportion of conductive fillers, lacking economic advantages. Therefore, it is necessary to develop PDMS-AgNW / MXene / AgNW composite films with ultra-thin functional layers, high mechanical stability, and integrated high-efficiency strain sensing functions to achieve efficient shielding against electromagnetic radiation and motion detection of the human body in complex electromagnetic environments. Summary of the Invention

[0006] The problem to be solved by the present invention is to provide a method for preparing a PDMS-AgNW / MXene / AgNW composite film in order to address the above-mentioned deficiencies in the prior art. This method utilizes an ultra-thin functional layer to achieve high electromagnetic interference shielding, high mechanical stability and integrated excellent strain sensing function, thereby realizing the application of the composite film in the fields of electromagnetic interference shielding and human motion detection.

[0007] The above-mentioned objective of this invention is achieved through the following technical solutions:

[0008] A method for preparing a PDMS-AgNW / MXene / AgNW composite membrane includes the following steps:

[0009] S1 alternately passes AgNW aqueous solution and MXene aqueous solution through vacuum-assisted filtration, and after assembly and post-processing, obtains AgNW / MXene / AgNW membrane;

[0010] S2 pre-cures PDMS in the presence of a curing agent to obtain a PDMS film;

[0011] S3 transfers the PDMS film obtained in S2 to at least one side of the AgNW / MXene / AgNW film obtained in S1. After bonding, post-processing is performed to obtain the PDMS-AgNW / MXene / AgNW composite film.

[0012] Specifically, in the PDMS-AgNW / MXene / AgNW composite membrane of the present invention, PDMS, AgNW, and MXene refer to polydimethylsiloxane, silver nanowires, and transition metal carbides, nitrides, or carbonitrides, respectively.

[0013] Furthermore, in S1, the mass ratio of AgNW to MXene is controlled to be 1.32~3.54:0.44~2.66.

[0014] Furthermore, in S1, the vacuum-assisted filtration process includes, after the filter membrane of the vacuum-assisted filtration device is wetted, first adding an AgNW aqueous solution, filtering for 1 to 10 minutes to form a lower AgNW layer, then adding an MXene aqueous solution and filtering for 1 to 10 minutes to form an MXene layer on the lower AgNW layer, then adding an AgNW aqueous solution and filtering for 1 to 10 minutes to form an upper AgNW layer on the MXene layer.

[0015] Furthermore, in S1, the vacuum-assisted filtration device is a Shinwell mobile phase filter.

[0016] Furthermore, in S1, the post-treatment is constant temperature drying, and the temperature of constant temperature drying is controlled at 40~120℃ and the time is controlled at 8~25min.

[0017] Further, in S2, the mass ratio of PDMS to curing agent is controlled to be 1.00~7.00:0.10~0.35.

[0018] Furthermore, in S2, the curing agent is Dow Corning DC184.

[0019] Furthermore, in S2, the pre-curing process includes first adding a curing agent to PDMS, stirring and mixing it, then pouring it into a mold and letting it stand, and then drying it at a constant temperature for pre-curing.

[0020] Furthermore, in S2, the stirring time is controlled to be 8 to 30 minutes and the stirring speed is controlled to be 200 to 800 rpm / min.

[0021] Furthermore, in S2, the settling time is controlled to be 30-60 minutes.

[0022] Furthermore, in S2, the temperature for constant temperature drying is controlled at 40~120℃ and the time is controlled at 8~25min.

[0023] Furthermore, in S3, the post-treatment is constant temperature drying, and the temperature of constant temperature drying is controlled at 40~120℃ and the time is controlled at 4~24h.

[0024] In summary, the beneficial technical effects of the present invention are as follows:

[0025] 1. The multifunctional PDMS-AgNW / MXene / AgNW composite film prepared by the present invention has a simple preparation process. Through the design of AgNW / MXene sandwich structure, it can achieve an electromagnetic interference shielding efficiency of up to 50.82dB with a functional layer thickness of 1µm, and integrates excellent strain sensing performance.

[0026] 2. The multifunctional PDMS-AgNW / MXene / AgNW composite membrane prepared by this invention has excellent mechanical stability. Thanks to the reinforcing effect of AgNW on MXene, the composite membrane maintains its shielding efficiency at 93.67% and 90.18% of its initial values ​​after 1000 cycles of bending (-70%) and stretching (+10%).

[0027] 3. The multifunctional PDMS-AgNW / MXene / AgNW composite membrane prepared by this invention integrates excellent strain sensing performance, with features such as high strain sensitivity (GF=468), wide linear sensing range, low detection limit (0.1%), and fast response speed (0.2s). As a wearable sensor, it shows good prospects in applications such as human motion detection, especially voice recognition. Attached Figure Description

[0028] Figure 1 This is a SEM image of the composite membrane prepared in Example 1 of the present invention.

[0029] Figure 2 This is a mechanical stability test diagram of the composite membrane prepared in Example 1 of the present invention.

[0030] Figure 3 This is a strain sensing performance diagram of the composite membrane prepared in Example 1 of the present invention.

[0031] Figure 4 The graph shows the resistance change of the composite membrane obtained in Example 1 of the present invention during human movement; wherein, (a) knee joint bending, (b) finger bending.

[0032] Figure 5 The graph shows the resistance change of the composite membrane prepared in Example 1 of the present invention when recognizing the pronunciations "Z, J, U, T".

[0033] Figure 6The above are comparison charts of electromagnetic interference shielding data of the composite films prepared in Example 1 and Comparative Examples 1 to 3 of the present invention; wherein, (a) comparison of EMI SE values ​​of composite films in Example 1 and Comparative Examples 1 to 2, (b) comparison of EMI SE values ​​of composite films in Example 1 and Comparative Example 3, and (c) curves of relative resistance of composite films in Example 1 and Comparative Examples 1 to 2 changing with time.

[0034] Figure 7 The strain sensing data of the composite membranes prepared in Example 1 and Comparative Examples 1-2 of the present invention are compared; wherein, (a) the relative resistance change curves of the composite membranes of Example 1 and Comparative Examples 1-2 under the same strain conditions, and (b) the current change trend of the composite membranes of Example 1 and Comparative Examples 1-2 under 0-70% strain conditions. Detailed Implementation

[0035] To make the technical means, creative features, objectives and effects of this invention clearer and easier to understand, the invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0036] Example

[0037] Example 1: A method for preparing a PDMS-AgNW / MXene / AgNW composite membrane disclosed in this invention includes the following steps:

[0038] After the filter membrane of S1 in the vacuum-assisted filtration equipment (Xinweier mobile phase filter) is wetted, AgNW aqueous solution is first added. After filtration for 5 minutes, a lower AgNW layer is formed. Then, MXene aqueous solution is added and filtered for 5 minutes to form an MXene layer on the lower AgNW layer. Then, AgNW aqueous solution is added and filtered for 5 minutes to form an upper AgNW layer on the MXene layer. During this process, the mass ratio of AgNW in the AgNW aqueous solution to MXene in the MXene aqueous solution is controlled at 2.00g:1.00g. After assembly, it is dried in a constant temperature drying oven at a controlled temperature of 60℃ for 15 minutes. Vacuum-assisted filtration and pre-curing are then performed to obtain the AgNW / MXene / AgNW membrane.

[0039] S2 first adds curing agent (Dow Corning DC184) to PDMS, and controls the mass ratio of PDMS to curing agent to be 3.00g:0.15g. Then stir at 500rpm / min for 20min, pour into a mold and let stand for 30min. After standing, dry in a constant temperature drying oven, and control the constant temperature drying temperature to be 60℃ and the time to be 15min to pre-cur the PDMS film.

[0040] After cooling the PDMS film obtained in S2 to room temperature, S3 transfers it to the upper surface of the AgNW / MXene / AgNW film obtained in S1. After bonding, it is dried in a constant temperature drying oven at a controlled temperature of 60℃ for 4 hours to obtain a PDMS-AgNW / MXene / AgNW composite film.

[0041] In use, the AgNW / MXene / PDMS composite film can be cut into shape or connected with electrodes to obtain a multifunctional AgNW / MXene / PDMS composite film for electromagnetic interference shielding and strain sensing. The electromagnetic interference shielding efficiency of the composite film is 39.96 dB.

[0042] Example 2: A method for preparing a PDMS-AgNW / MXene / AgNW composite membrane disclosed in this invention includes the following steps:

[0043] After the filter membrane of S1 in the vacuum-assisted filtration equipment (Xinweier mobile phase filter) is wetted, AgNW aqueous solution is first added. After filtration for 1 minute, a lower AgNW layer is formed. Then, MXene aqueous solution is added and filtered for 9 minutes to form an MXene layer on the lower AgNW layer. Then, AgNW aqueous solution is added and filtered for 1 minute to form an upper AgNW layer on the MXene layer. During this process, the mass ratio of AgNW in the AgNW aqueous solution to MXene in the MXene aqueous solution is controlled at 3.54g:0.46g. After assembly, it is dried in a constant temperature drying oven at 70℃ for 15 minutes. Vacuum-assisted filtration and pre-curing are then performed to obtain the AgNW / MXene / AgNW membrane.

[0044] S2 first adds curing agent (Dow Corning DC184) to PDMS, and controls the mass ratio of PDMS to curing agent to be 6.00g:0.20g. Then stir at 700rpm / min for 30min, pour into a mold and let stand for 50min. After standing, dry in a constant temperature drying oven, and control the constant temperature drying temperature to be 70℃ and the time to be 15min to pre-cur the PDMS film.

[0045] After cooling the PDMS film obtained in S2 to room temperature, S3 transfers it to the upper surface of the AgNW / MXene / AgNW film obtained in S1. After bonding, it is dried in a constant temperature drying oven at a controlled temperature of 70°C for 12 hours to obtain a PDMS-AgNW / MXene / AgNW composite film.

[0046] In use, the AgNW / MXene / PDMS composite film can be cut into shape or connected with electrodes to obtain a multifunctional AgNW / MXene / PDMS composite film for electromagnetic interference shielding and strain sensing. The electromagnetic interference shielding efficiency of the composite film is 36.82 dB.

[0047] Example 3: A method for preparing a PDMS-AgNW / MXene / AgNW composite membrane disclosed in this invention includes the following steps:

[0048] After the filter membrane of S1 in the vacuum-assisted filtration equipment (Xinweier mobile phase filter) is wetted, AgNW aqueous solution is first added. After filtration for 10 minutes, a lower AgNW layer is formed. Then, MXene aqueous solution is added and filtered for 1 minute to form an MXene layer on the lower AgNW layer. Then, AgNW aqueous solution is added again and filtered for 10 minutes to form an upper AgNW layer on the MXene layer. During this process, the mass ratio of AgNW in the AgNW aqueous solution to MXene in the MXene aqueous solution is controlled to be 2.00g:2.00g. After assembly, it is dried in a constant temperature drying oven at a controlled temperature of 70℃ for 20 minutes. Vacuum-assisted filtration and pre-curing are then performed to obtain the AgNW / MXene / AgNW membrane.

[0049] S2 first adds curing agent (Dow Corning DC184) to PDMS, and controls the mass ratio of PDMS to curing agent to be 5.00g:0.30g. Then stir at 600rpm / min for 20min, pour into a mold and let stand for 50min. After standing, dry in a constant temperature drying oven, and control the constant temperature drying temperature to be 70℃ and the time to be 20min to pre-cur the PDMS film.

[0050] After cooling the PDMS film obtained in S2 to room temperature, S3 transfers it to the upper surface of the AgNW / MXene / AgNW film obtained in S1. After bonding, it is dried in a constant temperature drying oven at a controlled temperature of 70°C for 20 hours to obtain a PDMS-AgNW / MXene / AgNW composite film.

[0051] Example 4: A method for preparing a PDMS-AgNW / MXene / AgNW composite membrane disclosed in this invention includes the following steps:

[0052] After the filter membrane of S1 in the vacuum-assisted filtration equipment (Xinweier mobile phase filter) is wetted, AgNW aqueous solution is first added. After filtration for 8 minutes, a lower AgNW layer is formed. Then, MXene aqueous solution is added and filtered for 6 minutes to form an MXene layer on the lower AgNW layer. Then, AgNW aqueous solution is added again and filtered for 8 minutes to form an upper AgNW layer on the MXene layer. During this process, the mass ratio of AgNW in the AgNW aqueous solution to MXene in the MXene aqueous solution is controlled to be 1.32g:2.66g. After assembly, it is dried in a constant temperature drying oven at a controlled temperature of 120℃ for 8 minutes. Vacuum-assisted filtration and pre-curing are then performed to obtain the AgNW / MXene / AgNW membrane.

[0053] S2 first adds curing agent (Dow Corning DC184) to PDMS, and controls the mass ratio of PDMS to curing agent to be 7.00g:0.35g. Then stir at 200rpm / min for 30min, pour into a mold and let stand for 40min. After standing, dry in a constant temperature drying oven, and control the constant temperature drying temperature to be 120℃ and the time to be 8min to pre-cur the PDMS film.

[0054] After cooling the PDMS film obtained in S2 to room temperature, S3 transfers it to the upper surface of the AgNW / MXene / AgNW film obtained in S1. After bonding, it is dried in a constant temperature drying oven at a controlled temperature of 120℃ for 10 hours to obtain a PDMS-AgNW / MXene / AgNW composite film.

[0055] Example 5: A method for preparing a PDMS-AgNW / MXene / AgNW composite membrane disclosed in this invention, comprising the following steps:

[0056] After the filter membrane of S1 in the vacuum-assisted filtration equipment (Xinweier mobile phase filter) is wetted, AgNW aqueous solution is first added. After filtration for 3 minutes, a lower AgNW layer is formed. Then, MXene aqueous solution is added and filtered for 4 minutes to form an MXene layer on the lower AgNW layer. Then, AgNW aqueous solution is added and filtered for 3 minutes to form an upper AgNW layer on the MXene layer. During this process, the mass ratio of AgNW in the AgNW aqueous solution to MXene in the MXene aqueous solution is controlled to be 3.54g:0.44g. After assembly, it is dried in a constant temperature drying oven at a controlled temperature of 40℃ for 25 minutes. Vacuum-assisted filtration and pre-curing are then performed to obtain the AgNW / MXene / AgNW membrane.

[0057] S2 first adds curing agent (Dow Corning DC184) to PDMS and controls the mass ratio of PDMS to curing agent to be 1.00g:0.10g. Then stir at 800rpm / min for 8min, pour into a mold and let stand for 60min. After standing, dry in a constant temperature drying oven and control the temperature of constant temperature drying to be 40℃ and the time to be 25min to pre-cur the PDMS film.

[0058] After cooling the PDMS film obtained in S2 to room temperature, S3 transfers it to the upper surface of the AgNW / MXene / AgNW film obtained in S1. After bonding, it is dried in a constant temperature drying oven at a controlled temperature of 40℃ for 15 hours to obtain a PDMS-AgNW / MXene / AgNW composite film.

[0059] Comparative Example

[0060] Comparative Example 1: This invention discloses a method for preparing a PDMS-AgNW / MXene / AgNW composite membrane, which includes the following steps. The difference from Example 1 is that in step S1, after the filter membrane of the vacuum-assisted filtration device (Xinweier mobile phase filter) is wetted, an AgNW aqueous solution is added first. After filtration for 5 minutes, an AgNW layer is formed. After assembly, the membrane is dried in a constant temperature drying oven, and the temperature is controlled at 60°C for 15 minutes. Vacuum-assisted filtration and pre-curing are then performed to obtain the AgNW membrane. Finally, the PDMS-AgNW composite membrane is obtained.

[0061] Comparative Example 2: This invention discloses a method for preparing a PDMS-AgNW / MXene / AgNW composite membrane, which includes the following steps. The difference from Example 1 is that in S1, after the filter membrane of the vacuum-assisted filtration device (Sinwell mobile phase filter) is wetted, an MXene aqueous solution is added and filtered for 5 minutes to form an MXene layer. After assembly, the membrane is dried in a constant temperature drying oven, and the temperature is controlled at 60°C and the time is controlled at 15 minutes. Vacuum-assisted filtration and pre-curing are then performed to obtain an MXene membrane; finally, a PDMS-MXene composite membrane is obtained.

[0062] Comparative Example 3: This invention discloses a method for preparing a PDMS-AgNW / MXene / AgNW composite membrane, comprising the following steps. The difference from Example 1 is that, in step S1, after the filter membrane of a vacuum-assisted filtration device (Sinwell mobile phase filter) is wetted, an AgNW aqueous solution is first added. After filtration for 5 minutes, a lower AgNW layer is formed. Then, an MXene aqueous solution is added and filtered for 5 minutes to form an MXene layer on the lower AgNW layer. After assembly, the membrane is dried in a constant temperature drying oven at a controlled temperature of 60°C for 15 minutes. Vacuum-assisted filtration and pre-curing are performed to obtain an AgNW / MXene membrane. Finally, a PDMS-AgNW / MXene composite membrane is obtained.

[0063] Performance testing

[0064] (1) The thickness of the PDMS-AgNW / MXene composite film prepared in step 1 was characterized by scanning electron microscopy (SEM), wherein, Figure 1 SEM images of the PDMS-AgNW / MXene composite membrane, from Figure 1 It can be seen that the thickness of the PDMS-AgNW / MXene composite film is about 1 µm, which is much smaller than that of the polyimide-based electromagnetic shielding film, the MXene / silver nanowire composite electromagnetic shielding film, and the stretchable flexible conductive composite material in the prior art.

[0065] (2) The PDMS-AgNW / MXene composite film prepared in Example 1 was subjected to tensile (+10%) and compressive (-70%) cyclic tests using a computer-controlled material testing machine (HZ-1007C). ​​Electromagnetic interference shielding tests were performed on the samples in the 8-12.4 GHz (X-band) range using a Ceyear vector network analyzer (3672C-S) based on the waveguide method. Four scattering parameters (S) were obtained from the vector network analyzer tests. 11 S 12 S 21 S 22 ), using their coefficients (R = S 11 = S 22 T = S 12 = S 21 The reflection (R) and transmission (T) values ​​are calculated using the following formula: R = |S 11 | 2 = |S 22 | 2 ;T = |S 12 | 2 = |S 21 | 2 .

[0066] Subsequently, the total EMI SE (SET) and its reflected (SER) and absorbed (SEA) components were calculated, and the results are as follows: Figure 2 As shown:

[0067] SE R = 10log [1 / (1-R)]

[0068] SE A = 10log[(1-R) / T]

[0069] SE T = SE R + SE A = 10log(1 / T)

[0070] from Figure 2 It can be seen that the EMI SE of the original composite film is 50.82dB, and its shielding efficiency remains at 93.67% and 90.18% respectively after 1,000 compression and stretching cycles.

[0071] (3) The strain sensing performance of the PDMS-AgNW / MXene composite film prepared in step 1 was tested using a computer-controlled material testing machine (HZ-1007C) and a digital source meter 2450. The strain performance of the composite film is the relationship between the relative resistance change (∆R / R0) and the tensile strain (ε=∆L / L0), where ∆R and ∆L are the resistance and length changes under a given strain, respectively, and R0 and L0 are the resistance and length changes under the initial conditions, respectively. The slope of the curve of relative resistance change versus tensile strain represents the sensitivity of the PDMS-AgNW / MXene composite film as a strain sensor (GF=(∆R / R0) / ε), and the results are as follows. Figure 3 As shown. From Figure 3 It can be seen that the composite membrane has a good linear sensing range and high sensitivity.

[0072] Subsequently, the PDMS-AgNW / MXene composite membrane prepared in step 1 was used to detect human motion, and the results were as follows: Figure 4 and Figure 5 As shown. From Figure 4 and Figure 5 It can be seen that the composite membrane exhibits excellent recognition ability in activities such as knee flexion, finger flexion, and vocal cord vocalization. Furthermore, from... Figure 6 and 7 It can be seen that the design of the PDMS-AgNW / MXene composite structure, compared with the use of a single material or the simple mixing of multiple materials, comprehensively improves the electromagnetic interference shielding performance and strain sensing performance.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A method for preparing a PDMS-AgNW / MXene / AgNW composite membrane, characterized in that: The method comprises the following steps: S1: AgNW aqueous solution and MXene aqueous solution are alternately passed through vacuum-assisted filtration, and after assembly, post-treatment is performed to obtain an AgNW / MXene / AgNW film; In the S1, the mass ratio of AgNW and MXene is controlled to be 1.32-3.54:0.44-2.66; In the S1, the process of vacuum-assisted filtration comprises the following steps: after the filter membrane of the vacuum-assisted filtration device is wetted, AgNW aqueous solution is first added, and after filtration for 1-10 min, a lower AgNW layer is formed; then MXene aqueous solution is added and filtered for 1-10 min, and a MXene layer is formed on the lower AgNW layer; then AgNW aqueous solution is added, and after filtration for 1-10 min, an upper AgNW layer is formed on the MXene layer; In the S1, the post-treatment is constant-temperature drying, and the temperature of the constant-temperature drying is controlled to be 40-120℃, and the time is controlled to be 8-25 min; S2: PDMS is pre-cured in the presence of a curing agent to obtain a PDMS film; S3: The PDMS film obtained in the S2 is transferred to at least one side surface of the AgNW / MXene / AgNW film obtained in the S1, and after adhesion, post-treatment is performed to obtain a PDMS-AgNW / MXene / AgNW composite film.

2. The preparation method of the PDMS-AgNW / MXene / AgNW composite film according to claim 1, characterized in that: In the S2, the mass ratio of PDMS and the curing agent is controlled to be 1.00-7.00:0.10-0.

35.

3. The method for preparing a PDMS-AgNW / MXene / AgNW composite membrane according to claim 2, characterized in that: In the S2, the process of pre-curing comprises the following steps: first, the curing agent is added to the PDMS and stirred uniformly, then poured into a mold and left to stand, and then constant-temperature drying is performed for pre-curing.

4. The method for preparing a PDMS-AgNW / MXene / AgNW composite membrane according to claim 3, characterized in that: In the S2, the stirring time is controlled to be 8-30 min, and the rotation speed is controlled to be 200-800 rpm / min.

5. The method for preparing a PDMS-AgNW / MXene / AgNW composite membrane according to claim 3, characterized in that: In the S2, the standing time is controlled to be 30-60 min.

6. The method for preparing a PDMS-AgNW / MXene / AgNW composite membrane according to claim 3, characterized in that: In the S2, the temperature of the constant-temperature drying is controlled to be 40-120℃, and the time is controlled to be 8-25 min.

7. The method for preparing a PDMS-AgNW / MXene / AgNW composite membrane according to claim 1, characterized in that: In the S3, the post-treatment is constant-temperature drying, and the temperature of the constant-temperature drying is controlled to be 40-120℃, and the time is controlled to be 4-24 h.

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