Lightweight porous MXene-polyimide composite film and preparation method and application thereof

Abstract

This invention belongs to the field of new materials technology and discloses a lightweight porous MXene polyimide composite film, its preparation method, and its applications. The composite film has a structure consisting of a polyimide nanofiber membrane layer, a porous MXene layer, and another polyimide nanofiber membrane layer from top to bottom. The technical solution of this invention involves treating MXene with cobalt acetate to obtain MXene with a porous structure. Using a polyamic acid nanofiber membrane prepared by electrospinning as a substrate, a PAA / p-MXene / PAA composite film is obtained through vacuum filtration. Finally, thermal imidization yields a PI / p-MXene / PI film. The film prepared by this invention endows MXene with lightweight characteristics and possesses excellent electromagnetic shielding and mechanical properties, while also exhibiting multifunctionality, such as thermal insulation properties, showing great application potential in aerospace and electronic communication fields.

Description

Technical Field

[0001] This invention belongs to the field of new materials technology, specifically relating to a lightweight porous MXene polyimide composite film, its preparation method, and its application. Background Technology

[0002] Electromagnetic interference (EMI) shielding materials are commonly used in electronic devices, communication equipment, aerospace, and other fields. However, these devices have strict limitations on the weight and load of the materials. Choosing lightweight EMI shielding materials can significantly reduce the load on the equipment, resulting in a reduction in weight. This greatly improves the ease of use and adaptability of electronic and communication equipment. Meanwhile, many precision electronic components and devices are highly sensitive to temperature changes; excessively high or low temperatures can severely affect their performance and lifespan. EMI shielding materials with good thermal insulation properties can minimize the transfer of external heat, ensuring that electronic equipment operates normally, efficiently, and stably over a wide range of ambient temperatures. This property effectively avoids the adverse effects of temperature variations on equipment performance and reliability.

[0003] MXene is a novel two-dimensional transition metal carbonitride with high specific surface area, excellent hydrophilicity, and metallic conductivity, making it widely used in electromagnetic shielding. Currently, to endow MXene with more functions, such as thermal management, corrosion resistance, oxidation resistance, and superior mechanical properties, researchers often combine it with polymer materials to improve overall performance. However, the dense structure of composite materials results in high density, making it difficult to achieve lightweight design. Therefore, to avoid the weight of electromagnetic shielding materials becoming a bottleneck limiting their application, there is an urgent need to develop a lightweight and efficient electromagnetic shielding material.

[0004] Therefore, providing a flexible electromagnetic shielding material that integrates lightweight, heat insulation, and shielding properties is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a lightweight porous MXene polyimide composite film, its preparation method, and its application.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A lightweight porous MXene polyimide composite film, wherein the structure of the composite film, from top to bottom, consists of a polyimide nanofiber membrane layer, a porous MXene layer, and a polyimide nanofiber membrane layer.

[0008] Preferably, the thickness of the polyimide nanofiber membrane is 50-70 μm, and the thickness of the porous MXene layer is 50-70 μm.

[0009] Preferably, the porous MXene layer is prepared by reacting MXene with cobalt acetate.

[0010] Preferably, the mass ratio of MXene to cobalt acetate is 1:5-5:1, more preferably 1:5, 1:3, 1:1, 3:1, or 5:1. During the preparation of the porous MXene solution, the amount of MXene is kept constant while different proportions of cobalt acetate are added to the MXene solution for reaction. After washing and centrifugation, the porous MXene solution is obtained.

[0011] Preferably, the porous MXene contains a large number of mesopores with a pore size of 4 nm and a small number of micropores with a pore size of 1-2 nm.

[0012] Preferably, the polyimide nanofiber membrane is obtained by preparing a polyamic acid solution through electrospinning followed by thermal imidization.

[0013] The method for preparing a lightweight porous MXene polyimide composite film as described above is characterized by comprising the following specific steps:

[0014] (1) React MXene solution with cobalt acetate to obtain porous MXene solution for later use;

[0015] (2) Polyamic acid nanofiber membranes were prepared by electrospinning of polyamic acid solution;

[0016] (3) Vacuum filtration is performed on the porous MXene solution with a polyamic acid nanofiber membrane as the base. When the water is about to be removed, the polyamic acid nanofiber membrane is placed on top of the porous MXene and filtration is continued to obtain a composite film. Then, after thermal imidization treatment, it becomes a lightweight porous MXene polyimide composite film.

[0017] Preferably, the porous MXene solution in step (1) has a concentration of 1-10 mg / mL.

[0018] Preferably, the MXene solution in step (1) is prepared by adding Ti3AlC2 powder to a mixed solution of hydrochloric acid / lithium fluoride for etching, and then obtaining the MXene solution by ultrasonic centrifugation.

[0019] Preferably, the parameters of the electrospinning method in step (2) are: injection speed of 0.4-1 mL / h, spinning voltage of 10-20 kV, distance of 10-20 cm, and spinning time of 8-20 h.

[0020] Preferably, the polyamic acid solution is obtained by polycondensation of dianhydride and diamine.

[0021] Preferably, the polyamic acid solution is prepared by dissolving a diamine in an aprotic polar solvent, then adding dianhydride in an ice bath and stirring for 4-8 hours to obtain the polyamic acid solution.

[0022] Preferably, the dianhydride includes at least one of pyromellitic dianhydride (PMDA), biphenyl dianhydride (BPDA), benzophenone tetracarboxylic dianhydride (BPDA), and 4,4'-oxobisphthalic anhydride (ODPA); the diamine includes at least one of 4,4'-diaminodiphenyl ether (ODA) and p-phenylenediamine (PDA).

[0023] Preferably, the molar ratio of the diamine to the dianhydride is 1:1.

[0024] Preferably, the aprotic polar solvent is at least one of N,N-dimethylformamide (DMF), N,N-dimethylformamide (DMAc), N-methylpyrrolidone (NMP), and dimethyl sulfoxide (DMSO).

[0025] Preferably, the temperature of the thermal imidization reaction in step (3) is 280-350℃, the reaction time is 2-10h, and the reaction heating rate is 1-2℃ / min. Thermal imidization can dehydrate and cyclize polyamic acid into polyimide, and can also remove water molecules between MXene layers to improve the conductivity of the composite film.

[0026] Preferably, the heating rate of the thermal imidization in step (3) is 1℃ / min, and the temperature is maintained at 80℃, 120℃, 180℃, 250℃, 300℃ and 350℃ for 30-50min respectively.

[0027] Preferably, in step (3), the polyimide fiber layer and the porous MXene layer of the lightweight porous MXene polyimide composite film are composited by the driving force of vacuum negative pressure and the interaction of hydrogen bonds.

[0028] The application of the composite film described above or the composite film prepared by the preparation method described above in shielding electromagnetic waves.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] This invention provides a lightweight porous MXene polyimide composite film, its preparation method, and its application. The invention reacts MXene with cobalt acetate, creating a porous structure on the MXene surface, which increases the multiple reflections of electromagnetic waves. The PI / p-MXene / PI composite film exhibits excellent electromagnetic interference shielding performance in the early X-band. Furthermore, due to the multi-layer porous structure design, the PI / p-MXene / PI composite film demonstrates lightweight characteristics.

[0031] Furthermore, due to the presence of polyimide nanofibers, the PI / p-MXene / PI composite film exhibits excellent thermal insulation properties. The lightweight polyimide MXene composite film prepared in this invention can be widely used in aerospace, electronic communications and other fields. Attached Figure Description

[0032] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0033] Figure 1 The image shown is a scanning electron microscope (SEM) image of the PI / p-MXene4 / PI composite film prepared in Example 4.

[0034] Figure 2 This is a transmission electron microscope (TEM) image of the p-MXene4 layer in Example 4;

[0035] Figure 3 The pore size distribution of p-MXene in Examples 1-5 with different ratios of MXene and cobalt acetate is shown in the broken line graph.

[0036] Figure 4 Density diagrams of PI / p-MXene / PI composite films with different ratios of MXene and cobalt acetate in Examples 1-5;

[0037] Figure 5 The graphs show the electromagnetic shielding values ​​of PI / p-MXene / PI composite films with different ratios of MXene and cobalt acetate in Examples 1-5.

[0038] Figure 6 Line graphs showing the thermal conductivity of PI / p-MXene / PI composite films with different ratios of MXene and cobalt acetate in Examples 1-5; Detailed Implementation

[0039] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0040] Example 1

[0041] A method for preparing a lightweight porous MXene polyimide composite film includes the following specific steps:

[0042] (1) Place 5 mL of deionized water and 15 mL of hydrochloric acid (12M) in a polytetrafluoroethylene container, add 1.6 g of lithium fluoride, react at 35 °C for 30 min, then slowly add 1 g of Ti3AlC2 powder, react for 24 h, then wash with deionized water until the pH of the supernatant is greater than 6, sonicate the lower precipitate under argon protection for 30 min, and centrifuge at 3500 rpm for 30 min to obtain a monolayer MXene solution (4 mg / mL);

[0043] Place 40 mL of MXene solution in an Erlenmeyer flask, add 800 mg of cobalt acetate powder, inject protective argon gas for 15 min, react at 25 °C for 48 h, and wash 5 times with deionized water to obtain p-MXene1 solution;

[0044] (2) 2.4 g ODA and 20 g DMF were added to a 100 mL three-necked flask and stirred. After the ODA dissolved, 2.616 g PMDA and 25.144 g DMF were added. The mixture was mechanically stirred at 400 r / min for 30 min in an ice-water bath and then stirred at 150 r / min for 3 h to obtain a yellow viscous gel-like PAA solution. The PAA solution was placed in a 10 mL disposable syringe and subjected to high-voltage electrospinning to obtain a PAA nanofiber membrane. The electrospinning parameters were: injection speed 0.5 mL / h, spinning voltage 16 kV, spinning distance 15 cm, and spinning time 12 h.

[0045] (3) The p-MXene1 solution was vacuum filtered on the PAA nanofiber membrane. When the water was about to be removed, another layer of PAA fiber membrane was placed on top of p-MXene1 and the filtration was continued for 10 min. The PAA / p-MXene1 / PAA composite film was dried in a vacuum drying oven at 60℃ for 1 h. The composite film was then thermally imidized in a tube furnace and protected with argon gas throughout the process to obtain the PI / p-MXene1 / PI composite film. The thermal imidization program was: 80℃ / 0.5h + 120℃ / 0.5h + 180℃ / 0.5h + 250℃ / 0.5h + 300℃ / 0.5h + 350℃ / 0.5h, with a heating rate of 1℃ / min.

[0046] Example 2

[0047] A method for preparing a lightweight porous MXene polyimide composite film includes the following specific steps:

[0048] (1) The specific preparation process of the monolayer MXene solution in this embodiment is the same as in Example 1;

[0049] Place 40 mL of MXene solution in an Erlenmeyer flask, add 480 mg of cobalt acetate powder, inject protective argon gas for 15 min, react at 25 °C for 48 h, and wash 5 times with deionized water to obtain p-MXene2 solution.

[0050] (2) The specific preparation process of the polyamic acid solution in this embodiment is the same as in Example 1;

[0051] PAA solution was placed in a 10mL disposable syringe and subjected to high-voltage electrospinning to obtain PAA nanofiber membranes. The electrospinning parameters were: injection rate 0.5mL / h, spinning voltage 15kV, spinning distance 15cm, and spinning time 12h.

[0052] (3) The p-MXene2 solution was vacuum filtered on the PAA nanofiber membrane. When the water was about to be removed, another layer of PAA fiber membrane was placed on top of p-MXene2 and the filtration was continued for 10 min. The PAA / p-MXene2 / PAA composite film was dried in a vacuum drying oven at 60℃ for 1 h. The composite film was then thermally imidized in a tube furnace and protected with argon gas throughout the process to obtain the PI / p-MXene2 / PI composite film. The thermal imidization program was: 80℃ / 0.5h + 120℃ / 0.5h + 180℃ / 0.5h + 250℃ / 0.5h + 300℃ / 0.5h + 350℃ / 0.5h, with a heating rate of 1℃ / min.

[0053] Example 3

[0054] A method for preparing a lightweight porous MXene polyimide composite film includes the following specific steps:

[0055] (1) The specific preparation process of the monolayer MXene solution in this embodiment is the same as in Example 1;

[0056] 40 mL of MXene solution was placed in an Erlenmeyer flask, 160 mg of cobalt acetate powder was added, and argon gas was injected for 15 min. The mixture was reacted at 25 °C for 48 h. The solution was washed 5 times with deionized water to obtain p-MXene3 solution.

[0057] (2) The specific preparation process of the polyamic acid solution in this embodiment is the same as in Example 1;

[0058] PAA solution was placed in a 10mL disposable syringe and subjected to high-voltage electrospinning to obtain PAA nanofiber membranes. The electrospinning parameters were: injection rate 0.5mL / h, spinning voltage 16kV, spinning distance 15cm, and spinning time 12h.

[0059] (3) The p-MXene3 solution was vacuum filtered on the PAA nanofiber membrane. When the water was about to be removed, another layer of PAA fiber membrane was placed on top of p-MXene3 and the filtration was continued for 10 min. The PAA / p-MXene3 / PAA composite film was dried in a vacuum drying oven at 60℃ for 1 h. The composite film was then thermally imidized in a tube furnace and protected with argon gas throughout the process to obtain the PI / p-MXene3 / PI composite film. The thermal imidization program was: 80℃ / 0.5h + 120℃ / 0.5h + 180℃ / 0.5h + 250℃ / 0.5h + 300℃ / 0.5h + 350℃ / 0.5h, with a heating rate of 1℃ / min.

[0060] Example 4

[0061] A method for preparing a lightweight porous MXene polyimide composite film includes the following specific steps:

[0062] (1) The specific preparation process of the monolayer MXene solution in this embodiment is the same as in Example 1;

[0063] 40 mL of MXene solution was placed in an Erlenmeyer flask, 53 mg of cobalt acetate powder was added, and argon gas was injected for 15 min. The mixture was reacted at 25 °C for 48 h. The solution was washed 5 times with deionized water to obtain p-MXene4 solution.

[0064] (2) The specific preparation process of the polyamic acid solution in this embodiment is the same as in Example 1;

[0065] PAA solution was placed in a 10mL disposable syringe and subjected to high-voltage electrospinning to obtain PAA nanofiber membranes. The electrospinning parameters were: injection rate 0.5mL / h, spinning voltage 15kV, spinning distance 15cm, and spinning time 12h.

[0066] (3) The p-MXene4 solution was vacuum filtered on the PAA nanofiber membrane. When the water was about to be removed, another layer of PAA fiber membrane was placed on top of p-MXene4 and the filtration was continued for 10 min. The PAA / p-MXene4 / PAA composite film was dried in a vacuum drying oven at 60℃ for 1 h. The composite film was then thermally imidized in a tube furnace and protected with argon gas throughout the process to obtain the PI / p-MXene4 / PI composite film. The thermal imidization program was: 80℃ / 0.5h + 120℃ / 0.5h + 180℃ / 0.5h + 250℃ / 0.5h + 300℃ / 0.5h + 350℃ / 0.5h, with a heating rate of 1℃ / min.

[0067] in, Figure 1The images show scanning electron microscope (SEM) images of the prepared PI / p-MXene4 / PI composite film. (a) shows the surface morphology of the composite film, and (b) shows the cross-sectional morphology of the composite film. As can be seen from the images, the PI fiber film exhibits a porous structure, and the PI fibers are of uniform thickness. The PI / p-MXene4 / PI composite film exhibits a distinct three-layer structure.

[0068] Figure 2 The image shows a transmission electron microscope (TEM) image of the p-MXene4 layer. As can be seen from the image, the surface of p-MXene4 has a porous structure.

[0069] Example 5

[0070] A method for preparing a lightweight porous MXene polyimide composite film includes the following specific steps:

[0071] (1) The specific preparation process of the monolayer MXene solution in this embodiment is the same as in Example 1;

[0072] 40 mL of MXene solution was placed in an Erlenmeyer flask, 33 mg of cobalt acetate powder was added, and argon gas was injected for 15 min. The mixture was reacted at 25 °C for 48 h. The solution was washed 5 times with deionized water to obtain p-MXene5 solution.

[0073] (2) The specific preparation process of the polyamic acid solution in this embodiment is the same as in Example 1;

[0074] PAA solution was placed in a 10mL disposable syringe and subjected to high-voltage electrospinning to obtain PAA nanofiber membranes. The electrospinning parameters were: injection rate 0.5mL / h, spinning voltage 15kV, spinning distance 15cm, and spinning time 12h.

[0075] (3) The p-MXene4 solution was vacuum filtered on the PAA nanofiber membrane. When the water was about to be removed, another layer of PAA fiber membrane was placed on top of p-MXene5 and the filtration was continued for 10 min. The PAA / p-MXene5 / PAA composite film was dried in a vacuum drying oven at 60℃ for 1 h. The composite film was then thermally imidized in a tube furnace and protected with argon gas throughout the process to obtain the PI / p-MXene5 / PI composite film. The thermal imidization program was: 80℃ / 0.5h + 120℃ / 0.5h + 180℃ / 0.5h + 250℃ / 0.5h + 300℃ / 0.5h + 350℃ / 0.5h, with a heating rate of 1℃ / min.

[0076] Figure 3 The figures show line graphs of the pore size distribution of p-MXene in different ratios of MXene and cobalt acetate in Examples 1-5. As can be seen from the figures, p-MXene has a different number of mesopores with a pore size of 4 nm, and also has a small number of micropores of 1-2 nm.

[0077] Figure 4 The figures show the density of PI / p-MXene / PI composite films with different ratios of MXene and cobalt acetate in Examples 1-5. As can be seen from the figures, the PI / p-MXene / PI composite films have a low density and are lightweight.

[0078] Figure 5 The figures show the electromagnetic shielding values ​​of the PI / p-MXene / PI composite films with different ratios of MXene and cobalt acetate in Examples 1-5. As can be seen from the figures, the PI / p-MXene / PI composite films have good electromagnetic interference shielding performance. Among them, the electromagnetic shielding performance of the PI / p-MXene4 / PI composite film in Example 4 can reach the highest of 52.7dB.

[0079] Figure 6 The graphs show the thermal conductivity of PI / p-MXene / PI composite films with different ratios of MXene and cobalt acetate in Examples 1-5. As can be seen from the graphs, the PI / p-MXene / PI composite films have low thermal conductivity, which is similar to that of air, and thus have good thermal insulation performance.

[0080] The various embodiments are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between the various embodiments can be referred to each other.

[0081] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A lightweight porous MXene-polyimide composite film, characterized in that, The structure of the composite film is polyimide nanofiber film layer, porous MXene layer and polyimide nanofiber film layer from top to bottom; wherein the porous MXene layer is prepared by the reaction of MXene and cobalt acetate, and the mass ratio of the MXene and the cobalt acetate is 1:5-5:

1.

2. The lightweight porous MXene polyimide composite film according to claim 1, wherein, The thickness of the polyimide nanofiber film layer is 50-70μm, and the thickness of the porous MXene layer is 50-70μm.

3. The lightweight porous MXene polyimide composite film according to claim 1, wherein, The polyimide nanofiber film layer is prepared by electrospinning of a polyamide acid solution and then heat imidization treatment.

4. The method of claim 1-3, wherein the method is characterized by, The method comprises the following specific steps: (1) reacting MXene solution with cobalt acetate to obtain porous MXene solution for standby use; (2) preparing polyamide acid nanofiber film by electrospinning of a polyamide acid solution; (3) vacuum suction filtration of the porous MXene solution on the polyamide acid nanofiber film, and then heat imidization treatment after the composite film is obtained by placing the polyamide acid nanofiber film above the porous MXene and continuing the suction filtration when the moisture is about to be dried.

5. The method of claim 4, wherein the method is characterized by: The concentration of the MXene solution is 1-10mg / mL.

6. The method of claim 4, wherein the method is characterized by: The preparation method of the MXene solution is etching Ti3AlC2 powder in a mixed solution of hydrochloric acid and lithium fluoride, and then obtaining MXene solution by ultrasonic centrifugation.

7. The method of claim 4, wherein the method further comprises the step of: 7-1) adding a solvent to the mixture of step 6-1) to form a solution. The parameters of the electrospinning in step (2) are injection speed of 0.4-1mL / h, spinning voltage of 10-20kV, distance of 10-20cm, and spinning time of 8-20h. The preparation method of the polyamide acid solution in step (2) is dissolving diamine in an aprotic polar solvent, adding dianhydride in an ice bath, stirring for 4-8h to obtain polyamide acid solution.

8. The method of claim 4, wherein the method is characterized by: The temperature of the heat imidization reaction in step (3) is 280-350℃, the reaction heating rate is 1-2℃ / min, and the reaction time is 2-10h.

9. Application of the composite film according to any one of claims 1-3 or prepared by the method of any one of claims 4-5 in shielding electromagnetic waves.

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