Multifunctional polyimide composite film with layered structure and preparation method thereof

Abstract

The invention relates to the technical field of electronic packaging materials, in particular to a multifunctional polyimide composite film with a layered structure and a preparation method of the multifunctional polyimide composite film. The composite film is composed of a polyimide matrix and alloy powder, the polyimide matrix at least contains one imide ring structure, and the alloy powder is distributed in a certain layer thickness range close to one surface of the polyimide composite film to form a layered structure; the preparation method of the composite membrane comprises the following steps: preparing a polyamide acid solution, adding alloy powder, uniformly mixing, and adjusting the solid content; and then coating the mixed solution on a flat plate, preheating, and carrying out programmed thermal imidization treatment to finally form the multifunctional polyimide composite film. The method is simple in process, low in cost and suitable for large-scale production, and the prepared polyimide composite film has excellent photothermal conversion performance, electromagnetic shielding performance and in-plane heat conduction performance.

Description

Technical Field

[0001] This invention relates to the field of electronic packaging materials technology, and in particular to a multifunctional polyimide composite film with a layered structure and its preparation method. Background Technology

[0002] Polymer membrane materials are finding increasingly wider applications in industries such as biomedicine, packaging and printing, electronic packaging, new energy, and separation and filtration. With the application of composite technology in polymer membranes, the functional requirements for polymer membranes in electronic packaging materials, electromagnetic compatibility, and thermal management materials are becoming increasingly stringent. Polyimide (PI) refers to a class of polymers containing imide rings (-CO-N-CO-) in their main chain, and is one of the organic polymer materials with the best overall performance. Polyimide can withstand temperatures above 400℃, with a long-term operating temperature range of -200 to 300℃. It not only possesses radiation resistance, flame retardancy, and non-toxicity, but also excellent electrical insulation, mechanical properties, chemical stability, aging resistance, and low dielectric loss. Furthermore, it exhibits superior mechanical properties, dimensional stability, chemical stability, and biocompatibility. Polyimide films, as one of its application forms, are highly suitable for applications in flexible substrates, electromagnetic shielding, and microelectronics.

[0003] In high-power-density packaging, chip hotspot temperatures rise, leading to significant electromagnetic interference (EMI) issues. However, polyimide itself has very low thermal conductivity and high electrical insulation properties, which cannot meet the requirements for rapid heat dissipation and electromagnetic compatibility. Generally, high thermal and electrical conductivity fillers, such as carbon materials and metals, are introduced into polyimide to simultaneously improve its thermal conductivity and electromagnetic shielding performance. For example, a lightweight, flexible, amino-functionalized multi-walled carbon nanotube-graphene nanosheet / poly(p-phenylbenzodioxazole) / poly(ether ether ketone) composite film, prepared using a vacuum-assisted, layer-by-layer filtration method, exhibits a sandwich structure with a thickness of 0.05 mm and demonstrates excellent electromagnetic shielding performance and low in-plane thermal conductivity. Small(2025, 21, 2503573). However, this vacuum-assisted filtration preparation method is time-consuming and labor-intensive, and the thickness of the composite membrane is difficult to control, making industrial continuous production impossible. Compared to carbon materials, metal materials are more affordable; however, their high density means that excessive polymer filling reduces the film's flexibility. Therefore, commercially, metal nanoparticles, such as aluminum, are often sputtered onto the surface of polyimide films to improve their electromagnetic shielding performance. However, this coating cannot achieve thermal conductivity, and the sputtered metal layer, located on the film surface, is not resistant to acid corrosion and is also at risk of wear and detachment. Researchers often achieve electromagnetic shielding properties by coating polymer fibers with metallic materials. For example, a novel lightweight, flexible metallized polyimide nonwoven fabric was prepared by roughening with polydopamine, activating with palladium-free chloroplatinic acid, electroless nickel plating, and corrosion-resistant treatment with octadecyl mercaptan, achieving excellent Joule heating and electromagnetic shielding properties (Chemical Engineering Journal, 2024, 480, 148000). This film has a porous structure, and the metal coating on the fiber surface maintains the mechanical properties of the composite film. However, the preparation process is complex, and the presence of pores cannot effectively conduct heat. Furthermore, as applications expand to extreme and cold conditions such as deep sea and deep space, the multifunctionality of polyimides is imperative. There is an urgent need for a simple and convenient method to prepare and produce polyimides that can meet the multifunctional requirements of metallic materials. Summary of the Invention

[0004] To address the problems existing in the prior art, one objective of this invention is to provide a multifunctional polyimide composite film with a layered structure. In this composite film, alloy powder is distributed within a certain thickness range near one surface of the polyimide composite film, forming a layered structure. This layered composite film possesses photothermal conversion, electromagnetic shielding, and in-plane thermal conductivity properties, meeting the needs of complex application scenarios.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: a multifunctional polyimide composite film with a layered structure, wherein the composite film is composed of a polyimide matrix and alloy powder; The polyimide matrix contains at least one imide ring structure; The alloy powder is distributed within a certain thickness range near one surface of the polyimide composite film, forming a layered structure.

[0006] As a further improvement to the multifunctional polyimide composite film with a layered structure: Preferably, the thickness of the multifunctional polyimide composite film is 2μm-1mm, and the thickness of the film layer containing the alloy powder accounts for 5-90% of the total thickness of the composite film.

[0007] Preferably, the alloy powder contains at least two of the elements selected from nickel, iron, gold, silver, bismuth, aluminum, titanium, magnesium, tin, copper, zinc, cerium, indium, antimony, germanium, calcium, gallium, tellurium, selenium, lead, cobalt, and manganese, and the particle size of the alloy powder is 200 nm to 500 μm.

[0008] A second objective of this invention is to provide a method for preparing the above-mentioned multifunctional polyimide composite film with a layered structure, comprising the following steps: S1. Preparation of polyamic acid solution: Dissolve the diamine monomer in an organic solvent, add the dianhydride monomer under stirring, control the molar ratio of dianhydride monomer to diamine monomer to be (0.90~1.25):1, stir and react at room temperature for 1~4 hours to obtain a polyamic acid solution with a solid content of 10%~25%. S2. Preparation of polyamic acid mixture: Mix polyamic acid solution with alloy powder and stir evenly. The mixing mass ratio is 100:(0.4-2.4). Add organic solvent to adjust the solid content of the mixture to 18%~22%, and then perform degassing treatment. S3. Coating and preheating: Coat the degassed mixed solution onto a plate with a coating thickness of 1~1200 μm, and then place the plate in an oven at 60~90℃ for preheating for 30~180 minutes. S4. Thermal imidization: The preheated composite film is placed in a high-temperature oven and subjected to step-by-step heat treatment according to the following procedure: first, it is kept at 60~80℃ for 60 minutes, then at 180℃ for 20 minutes, then at 200~240℃ for 60 minutes, and finally at 370~390℃ for 10 minutes, thus obtaining the multifunctional polyimide composite film with a layered structure.

[0009] Further improvements were made to the preparation method of multifunctional polyimide composite films with layered structures: Preferably, the dianhydride monomer is selected from one or more of the following: pyromellitic dianhydride, hydrogenated pyromellitic dianhydride, biphenyl dianhydride, diphenyl ether dianhydride, benzophenone dianhydride, 4,4'-(acetylene-1,2-diyl)phthalic anhydride, hexafluorodianhydride, and compounds having two anhydride functional groups.

[0010] Preferably, the diamine monomer is selected from one or more of 4,4'-diaminodiphenyl ether, p-phenylenediamine, 4,4'-diaminodiphenylmethane, m-phenylenediamine, 2,2-bis(trifluoromethyl)benzidine, 4-aminophenyl disulfide, 4,4'-dithiodiphenylamine, and compounds containing two or more amino functional groups.

[0011] Preferably, the organic solvent is selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, methylpyrrolidone, and dimethyl sulfoxide.

[0012] Preferably, the equipment used in the degassing process in S2 is a vacuum oven, a centrifugal degassing machine, a self-made degassing device, or a vacuum degassing machine.

[0013] Preferably, the tool used for coating in S3 is a flatbed coating machine, a doctor blade coater, or a bar coater.

[0014] Preferably, the flat plate in S3 is a glass plate, marble plate, ceramic tile plate, stainless steel plate, mica plate, or aluminum silicate ceramic fiber plate.

[0015] The advantages of this invention compared to the prior art are as follows: (1) This invention provides a multifunctional polyimide composite film with a layered structure. Alloy powder is distributed within a certain thickness range of the composite film. The compact packing of the alloy powder provides a good continuous channel for the transport of electrons and phonons, endowing the material with high in-plane thermal conductivity and electromagnetic shielding performance. Moreover, the metal powder can absorb photon energy and convert it into heat energy under light. On the one hand, the metal contains a large number of free electrons. When the electromagnetic field of the incident light acts on these free electrons, it will drive them to undergo collective coherent oscillation. On the other hand, for metals, the localized surface plasmon resonance (LSPR) effect is the key mechanism. That is, when the incident light frequency matches the collective oscillation frequency of the free electrons on the surface of the metal nanoparticles, strong light absorption and hot electron generation are generated, which significantly improves the photothermal conversion efficiency. This composite film has multifunctional characteristics and simple composition, and has broad application prospects in the fields of electronic packaging materials, thermal management, electromagnetic shielding, and photothermal heating.

[0016] (2) This invention provides a method for preparing a multifunctional polyimide composite film with a layered structure. Pre-curing is performed before the thermal imidization of polyamic acid, allowing the metal filler to settle sufficiently, thus achieving a layered structure design for the composite film. This results in metal powder being distributed within a certain thickness range of the composite film. The layered structure design avoids the drawbacks of easy detachment and poor corrosion resistance of industrial metal nanoparticle sputtering coatings. This layered design also solves the problem of reduced flexibility of the composite film caused by excessive metal material filling. Furthermore, strict control of the thickness during coating and the preparation of the polyamic acid mixture allow for thickness regulation and component thickness design of the composite film, providing selectable preparation schemes for thermal conductivity, electromagnetic shielding, and photothermal conversion performance. This preparation method is simple, uses inexpensive raw materials, and is expected to achieve continuous industrial production. Attached Figure Description

[0017] Figure 1 These are schematic diagrams (a) and scanning electron microscope cross-sectional views (b) of the multifunctional polyimide composite film prepared according to embodiments of the present invention; reference numerals: 1, polyimide component; 2, alloy powder component.

[0018] Figure 2 (a) shows the photothermal conversion performance curves of the multifunctional polyimide composite films with different alloy powder contents prepared in Examples 1, 2, 3 and 4; (b) shows the photothermal conversion performance curves of the multifunctional polyimide composite film prepared in Example 2 under different laser powers.

[0019] Figure 3 In the table, (a) is the in-plane thermal conductivity of the multifunctional polyimide composite film prepared in Example 1; (b) is the electromagnetic shielding performance of the multifunctional polyimide composite films with different alloy powder contents prepared in Examples 1, 2, 3 and 4.

[0020] Figure 4 (a) is the curve showing the effect of composite film thickness on the photothermal conversion performance of the polyimide composite films prepared in Examples 1, 5, 6 and 7; (b) is the curve showing the effect of alloy powder particle size on the photothermal conversion performance of the polyimide composite films prepared in Examples 1, 8 and 9.

[0021] Figure 5 These are the effect curves of different alloy powder types on the photothermal conversion performance of the composite film in Examples 1 and 10. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0023] Example 1

[0024] This embodiment provides a method for preparing a multifunctional polyimide composite film with a layered structure, including the following steps: S1. Preparation of polyamic acid solution: 3.888 g of diamine monomer (4,4′-diaminodiphenyl ether) was dissolved in 34.8 g of organic solvent (N,N-dimethylacetamide). 4.812 g of dianhydride monomer (pyromellitic anhydride) was slowly added under stirring. The molar ratio of dianhydride monomer to diamine monomer was 1.13:1. After stirring at room temperature for 2 h, a polyamic acid solution with a solid content of 20% was obtained. S2. Preparation of polyamic acid mixture: Mix 10 g of polyamic acid solution with 0.08 g of alloy powder (tin-bismuth-silver alloy Sn). 64 Bi 35 Ag1 (average particle size 20 μm) was mixed and stirred evenly. 2.2 g of organic solvent (N,N-dimethylacetamide) was added to adjust the solid content of the mixed solution to 20%. The solution was then degassed using a vacuum drying oven. S3. Coating and preheating: Using a flatbed coating machine, the degassed mixed solution is coated onto a quartz glass plate with a coating thickness of 200 μm. The plate is then placed in an oven at 70°C for 2 hours to preheat. S4. Thermal imidization: The preheated composite film is placed in a high-temperature oven and subjected to step-by-step heat treatment according to the following procedure: first, it is kept at 80℃ for 60 minutes, then at 180℃ for 20 minutes, then at 240℃ for 60 minutes, and finally at 390℃ for 10 minutes, thus obtaining the multifunctional polyimide composite film with a layered structure, denoted as PI / 4AP-20μm-200μm.

[0025] A schematic diagram of the structure of the prepared multifunctional polyimide composite film is shown below. Figure 1 As shown in (a), the scanning electron microscope image of the cross-section of the composite membrane is shown in (b). The total thickness of the prepared composite membrane was measured to be 40 μm, with the layer containing the alloy powder having a thickness of 25 μm. The thickness of the layer containing the alloy powder accounts for 62.50% of the total thickness of the composite membrane.

[0026] Example 2

[0027] This embodiment provides a method for preparing a multifunctional polyimide composite film with a layered structure. The specific steps are the same as in Example 1, except that 0.04 g of alloy powder (tin-bismuth-silver alloy Sn) is added in S2. 64 Bi 35 Ag1 (average particle size 20 μm) powder.

[0028] A multifunctional polyimide composite membrane with a layered structure was finally obtained, denoted as PI / 2AP-20μm-200μm. Testing showed that the total thickness of the composite membrane was 40 μm, with the layer containing the alloy powder having a thickness of 22 μm, representing 55.00% of the total thickness of the composite membrane.

[0029] Example 3

[0030] This embodiment provides a method for preparing a multifunctional polyimide composite film with a layered structure. The specific steps are the same as in Example 1, except that 0.16 g of alloy powder (tin-bismuth-silver alloy Sn) is added in S2. 64 Bi 35 Ag1 (average particle size 20 μm) powder.

[0031] A multifunctional polyimide composite membrane with a layered structure was finally obtained, denoted as PI / 8AP-20μm-200μm. Testing showed that the total thickness of the composite membrane was 40 μm, with the layer containing the alloy powder having a thickness of 28 μm, representing 70.00% of the total thickness of the composite membrane.

[0032] Example 4

[0033] This embodiment provides a method for preparing a multifunctional polyimide composite film with a layered structure. The specific steps are the same as in Example 1, except that 0.24 g of alloy powder (tin-bismuth-silver alloy Sn) is added to S2. 64 Bi 35 Ag1 (average particle size 20 μm) powder.

[0034] A multifunctional polyimide composite membrane with a layered structure was finally obtained, denoted as PI / 12AP-20 μm-200 μm. Testing showed that the total thickness of the composite membrane was 40 μm, with the layer containing the alloy powder having a thickness of 30 μm. The alloy powder layer accounted for 75.00% of the total thickness of the composite membrane.

[0035] The polyimide composite films prepared in Examples 1-4 were irradiated with different powers of an 808 nm laser emitter, and data on the temperature change of the film surface over time were collected using an infrared camera. The results are as follows. Figure 2 As shown in Figure (a), at a power of 1W, the surface temperature of the polyimide composite film first increases and then decreases with increasing alloy powder content, exhibiting the best photothermal conversion performance when the alloy powder content is 4%. The photothermal conversion performance curves of the multifunctional polyimide composite film prepared in Example 2 under different laser powers are shown in Figure (a). Figure 2 As shown in (b), changing the laser power also adjusts the surface temperature of the polyimide composite film. When the laser power increases from 0.75W to 1.25W, the surface temperature of the PI / 2AP-20μm-200μm composite film increases from 70℃ to 158℃. Figure 1 As can be seen, the composite film has a fast photothermal conversion response and a wide range of adjustable temperature rise.

[0036] Figure 3 In Figure (a), the in-plane thermal conductivity of the multifunctional polyimide composite film prepared in Example 1 is shown; in Figure (b), the electromagnetic shielding performance of the multifunctional polyimide composite films with different alloy powder contents prepared in Examples 1, 2, 3, and 4 is shown. Figure 3 It can be seen that the bottom thermal conductivity of the composite film increases with the increase of alloy powder content, and the electromagnetic shielding effectiveness of the composite film is also positively correlated with the alloy powder content.

[0037] Example 5

[0038] This embodiment provides a method for preparing a multifunctional polyimide composite film with a layered structure. The specific steps are the same as in Example 1, except that the coating thickness in S3 is 300 μm.

[0039] A multifunctional polyimide composite membrane with a layered structure was finally obtained, denoted as PI / 4AP-20 μm-300 μm. Testing showed that the total thickness of the composite membrane was 60 μm, with the layer containing the alloy powder having a thickness of 25 μm. The alloy powder layer accounted for 41.67% of the total thickness of the composite membrane.

[0040] Example 6

[0041] This embodiment provides a method for preparing a multifunctional polyimide composite film with a layered structure. The specific steps are the same as in Example 1, except that the coating thickness in S3 is 400 μm.

[0042] A multifunctional polyimide composite membrane with a layered structure was finally obtained, denoted as PI / 4AP-20 μm-400 μm. Testing showed that the total thickness of the composite membrane was 80 μm, with the layer containing the alloy powder having a thickness of 25 μm, representing 31.25% of the total thickness of the composite membrane.

[0043] Example 7

[0044] This embodiment provides a method for preparing a multifunctional polyimide composite film with a layered structure. The specific steps are the same as in Example 1, except that the coating thickness in S3 is 500 μm.

[0045] A multifunctional polyimide composite membrane with a layered structure was finally obtained, denoted as PI / 4AP-20 μm-500 μm. Testing showed that the total thickness of the composite membrane was 100 μm, with the layer containing the alloy powder having a thickness of 25 μm, representing 25.00% of the total thickness of the composite membrane.

[0046] The polyimide composite films prepared in Examples 1, 5, 6, and 7 were irradiated with different powers of an 808 nm laser emitter. Infrared cameras were used to collect data on the temperature change of the film surface over time to investigate the effect of the polyimide composite film thickness on its photothermal conversion performance. The results are as follows: Figure 4 As shown in (a), when the particle size of the alloy powder is 20 μm, the thickness of the composite film affects the photothermal conversion effect. The surface temperature of the composite film first increases and then decreases as the thickness of the composite film increases. The composite film exhibits the best photothermal conversion effect when the thickness is 60 μm.

[0047] Example 8

[0048] This embodiment provides a method for preparing a multifunctional polyimide composite film with a layered structure. The specific steps are the same as in Example 1, except that 0.08 g of alloy powder (tin-bismuth-silver alloy Sn) is added to S2. 64 Bi 35Ag1 (average particle size 25 μm).

[0049] A multifunctional polyimide composite membrane with a layered structure was finally obtained, denoted as PI / 4AP-25μm-200 μm. Testing showed that the total thickness of the composite membrane was 40 μm, with the layer containing the alloy powder having a thickness of 28 μm, representing 70.00% of the total thickness of the composite membrane.

[0050] Example 9

[0051] This embodiment provides a method for preparing a multifunctional polyimide composite film with a layered structure. The specific steps are the same as in Example 1, except that 0.08 g of alloy powder (tin-bismuth-silver alloy Sn) is added to S2. 64 Bi 35 Ag1 (average particle size 30 μm).

[0052] A multifunctional polyimide composite membrane with a layered structure was finally obtained, denoted as PI / 4AP-30μm-200 μm. Testing showed that the total thickness of the composite membrane was 40 μm, with the layer containing the alloy powder having a thickness of 32 μm. The alloy powder layer accounted for 80.00% of the total thickness of the composite membrane.

[0053] The polyimide composite films prepared in Examples 1, 8, and 9 were irradiated with different powers of an 808 nm laser emitter. Infrared cameras were used to collect data on the temperature changes of the film surface over time. The effect of alloy powder particle size on the photothermal conversion performance of the composite films was studied, and the results are as follows: Figure 4 As shown in (b), when Sn 64 Bi 35 When the particle size of Ag1 alloy powder LMPA exceeds 25 μm, the surface temperature of the composite film is minimally affected by changes in particle size.

[0054] Example 10

[0055] This embodiment provides a method for preparing a multifunctional polyimide composite film with a layered structure. The specific steps are the same as in Example 1, except that 0.08 g of alloy powder (tin-bismuth alloy Sn) is added in S2. 42 Bi 58 (Average particle size 20 μm).

[0056] A multifunctional polyimide composite membrane with a layered structure was finally obtained, denoted as PI / 4AP-20μm-200μm-1. Testing showed that the total thickness of the composite membrane was 40 μm, with the layer containing the alloy powder having a thickness of 25 μm. The alloy powder layer accounted for 62.50% of the total thickness of the composite membrane.

[0057] like Figure 5 As shown, the curves show the influence of different alloy powder types on the photothermal conversion performance of the composite film in Examples 1 and 10. When the type of alloy powder is changed, the polyimide composite film still has excellent photothermal conversion performance, with slight differences in the maximum temperature rise. When the laser irradiates the surface of the composite film, the surface temperature of the composite film rises rapidly, and after the laser irradiation is removed, the surface temperature of the composite film drops rapidly.

[0058] Those skilled in the art should understand that the above descriptions are merely several specific embodiments of the present invention, and not all embodiments. It should be noted that many modifications and improvements can be made by those skilled in the art, and all modifications or improvements not exceeding the scope of the claims should be considered within the protection scope of the present invention.

Claims

1. A multifunctional polyimide composite film with a layered structure, characterized in that, The composite film is composed of a polyimide matrix and alloy powder. The polyimide matrix contains at least one imide ring structure; The alloy powder is distributed within a certain thickness range near one surface of the polyimide composite film, forming a layered structure.

2. The multifunctional polyimide composite film with a layered structure according to claim 1, characterized in that, The thickness of the multifunctional polyimide composite film is 2μm-1mm, and the thickness of the film layer containing the alloy powder accounts for 5-90% of the total thickness of the composite film.

3. The multifunctional polyimide composite film with a layered structure according to claim 1, characterized in that, The alloy powder contains at least two of the elements selected from nickel, iron, gold, silver, bismuth, aluminum, titanium, magnesium, tin, copper, zinc, cerium, indium, antimony, germanium, calcium, gallium, tellurium, selenium, lead, cobalt, and manganese, and the particle size of the alloy powder is between 200 nm and 500 μm.

4. A method for preparing a multifunctional polyimide composite film with a layered structure as described in any one of claims 1-3, characterized in that, Includes the following steps: S1. Preparation of polyamic acid solution: Dissolve the diamine monomer in an organic solvent, add the dianhydride monomer under stirring, control the molar ratio of dianhydride monomer to diamine monomer to be (0.90~1.25):1, stir and react at room temperature for 1~4 hours to obtain a polyamic acid solution with a solid content of 10%~25%. S2. Preparation of polyamic acid mixture: Mix polyamic acid solution with alloy powder and stir evenly. The mixing mass ratio is 100:(0.4-2.4). Add organic solvent to adjust the solid content of the mixture to 18%~22%, and then perform degassing treatment. S3. Coating and preheating: Coat the degassed mixed solution onto a plate with a coating thickness of 1~1200 μm, and then place the plate in an oven at 60~90℃ for preheating for 30~180 minutes. S4. Thermal imidization: The preheated composite film is placed in a high-temperature oven and subjected to step-by-step heat treatment according to the following procedure: first, it is kept at 60~80℃ for 60 minutes, then at 180℃ for 20 minutes, then at 200~240℃ for 60 minutes, and finally at 370~390℃ for 10 minutes, thus obtaining the multifunctional polyimide composite film with a layered structure.

5. The method for preparing the multifunctional polyimide composite film with a layered structure according to claim 4, characterized in that, The dianhydride monomer is selected from one or more of the following: pyromellitic dianhydride, hydrogenated pyromellitic dianhydride, biphenyl dianhydride, diphenyl ether dianhydride, benzophenone dianhydride, 4,4'-(acetylene-1,2-diyl)phthalic anhydride, hexafluorodianhydride, and compounds having two anhydride functional groups.

6. The method for preparing the multifunctional polyimide composite film with a layered structure according to claim 4, characterized in that, The diamine monomer is selected from one or more of 4,4'-diaminodiphenyl ether, p-phenylenediamine, 4,4'-diaminodiphenylmethane, m-phenylenediamine, 2,2-bis(trifluoromethyl)benzidine, 4-aminophenyl disulfide, 4,4'-dithiodiphenylamine, and compounds containing two or more amino functional groups.

7. The method for preparing the multifunctional polyimide composite film with a layered structure according to claim 4, characterized in that, The organic solvent is selected from one or more of N,N-dimethylformamide, N,N-dimethylacetamide, methylpyrrolidone, and dimethyl sulfoxide.

8. The method for preparing a multifunctional polyimide composite film with a layered structure according to claim 4, characterized in that, The equipment used for the degassing process in S2 is a vacuum oven, a centrifugal degassing machine, a self-made degassing device, or a vacuum degassing machine.

9. The method for preparing a multifunctional polyimide composite film with a layered structure according to claim 4, characterized in that, The tools used for coating as described in S3 are flatbed coating machines, doctor blade coaters, or bar coaters.

10. The method for preparing a multifunctional polyimide composite film with a layered structure according to claim 4, characterized in that, The flat plate mentioned in S3 is a glass plate, marble plate, ceramic tile plate, stainless steel plate, mica plate or aluminum silicate ceramic fiber plate.

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