MXene / graphite-phase carbon nitride / aramid nanofiber electromagnetic shielding film with conductive gradient structure and preparation method of MXene / graphite-phase carbon nitride / aramid nanofiber electromagnetic shielding film
By introducing aramid nanofibers and graphite phase carbon nitride into the MXene-based electromagnetic shielding material, an electromagnetic shielding film with a conductive gradient structure is solved, and the balance problem between the mechanical properties of MXene-based materials is achieved, and the combination of efficient electromagnetic wave shielding and mechanical strength is achieved.
Patent Information
- Application Number
- CN202510414149.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-04-03
- Publication Date
- 2025-07-04
AI Technical Summary
The existing MXene-based electromagnetic shielding materials are difficult to balance between mechanical properties and electromagnetic shielding properties, and the intrinsic conductivity is high, which limits its practical application.
By introducing high mechanical strength aramid nanofibers and dielectric matching material graphite phase carbon nitride, it forms hydrogen bonds with MXene, and uses vacuum-assisted suction filtration to prepare electromagnetic shielding films with conductive gradient structures to optimize impedance matching performance.
It achieves a balance between high mechanical strength and excellent electromagnetic shielding performance, reduces reflection loss, improves the shielding and attenuation effect of electromagnetic waves, and maintains good machiningability.
Smart Images
Figure CN120264723A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of electromagnetic shielding materials, and particularly to an MXene / graphite phase carbon nitride / aramid nanofiber (MXene / g-C3N4 / ANF) electromagnetic shielding film with a conductive gradient structure and a preparation method thereof. Background Art
[0002] With the rapid development of modern electronic devices and the application of 5G technology, ubiquitous electromagnetic waves have brought a serious crisis to the safe operation of electronic devices and even directly threatened human health. Electromagnetic shielding materials precisely utilize the inherent conductive, magnetic, and other properties of the shielding body to block the propagation path of electromagnetic waves, causing the electromagnetic waves to be reflected or confined within the shielding body, and fundamentally regulating electromagnetic interference. MXene-based electromagnetic shielding materials have excellent electromagnetic shielding performance, and at the same time, they also possess characteristics such as high conductivity, high absorption loss, large absorption bandwidth, and light weight and easy processing. However, due to the poor mechanical properties and high intrinsic conductivity of MXene itself, its practical applications are limited. Therefore, how to make good composites of MXene with other materials to ensure the balance of the composite materials in terms of electromagnetic shielding performance, processability, and mechanical strength is a technical problem that needs to be solved currently. In view of the above background and current situation, on the one hand, semiconductor graphite phase carbon nitride is introduced as an impedance matching material to regulate the electrical properties of MXene. On the other hand, one-dimensional rigid aramid nanofibers can form hydrogen bond interactions with the MXene conductive layer to obtain a composite material with good mechanical properties. Through a vacuum-assisted filtration process, the three are well combined to prepare an electromagnetic shielding composite film with both excellent mechanical properties and electromagnetic functions. Summary of the Invention
[0003] Aiming at the deficiencies of the prior art, the present invention proposes an MXene / g-C3N4 / ANF electromagnetic shielding film with a conductive gradient structure.
[0004] The object of the present invention can be achieved through the following technical solutions:
[0005] An MXene / g-C3N4 / ANF electromagnetic shielding film with a conductive gradient structure, comprising the following raw materials:
[0006] MXene,
[0007] g-C3N4,
[0008] ANF.
[0009] Optionally, the electromagnetic shielding material is a conductive gradient composite film, including a top layer, a middle layer, and a bottom layer. The content of MXene in the top layer, middle layer, and bottom layer increases in sequence, and the content of g-C3N4 in the top layer, middle layer, and bottom layer decreases in sequence.
[0010] Optionally, the total mass ratio of the MXene, g-C3N4, and ANF in the composite film is 45:45:60 or 63:27:60.
[0011] Optionally, in the top layer, middle layer, and bottom layer, the mass ratios of MXene, g-C3N4, and ANF are 9:21:20, 15:15:20, and 21:9:20, or 15:15:20, 21:9:20, and 27:3:20, respectively. The former composite film is denoted as MCNA37-55-73, where M represents MXene, CN represents g-C3N4, A represents ANF, and the numbers represent the mass ratios of MXene and g-C3N4 in each layer of the film; the latter composite film is denoted as MCNA55-73-91.
[0012] A method for preparing an MXene / g-C3N4 / ANF electromagnetic shielding film with a conductive gradient structure includes the following steps:
[0013] Prepare an MXene aqueous dispersion, a g-C3N4 aqueous dispersion, and an ANF aqueous dispersion;
[0014] Ultrasonically mix the prepared MXene aqueous dispersion, g-C3N4 aqueous dispersion, and ANF aqueous dispersion to obtain a mixed solution;
[0015] Load the mixed solution onto a substrate film.
[0016] Optionally, the substrate film is a polyethylene terephthalate nuclear pore filter membrane.
[0017] The concentrations of the MXene aqueous dispersion, g-C3N4 aqueous dispersion, and ANF aqueous dispersion are 0.5 mg / g, 1 mg / g, and 1 mg / g, respectively.
[0018] Optionally, the loading method is: stacking on the substrate film through a vacuum-assisted filtration process.
[0019] Optionally, in the electromagnetic shielding material, the total mass ratio of the MXene, g-C3N4, and ANF in the composite film is 45:45:60 or 63:27:60.
[0020] Optionally, the method for preparing the MXene includes the following steps:
[0021] Add hydrochloric acid into the polytetrafluoroethylene liner, then add lithium fluoride, and stir until lithium fluoride is completely dissolved. Under the ice bath condition, add Ti3AlC2 and stir magnetically for reaction. Then transfer the mixed solution in the polytetrafluoroethylene liner to a centrifuge tube, and centrifuge and wash repeatedly for several times until the pH of the upper layer solution reaches 7. Subsequently, break it with a cell disruptor under the protection of inert gas. Freeze-dry the obtained solution under vacuum.
[0022] The preparation method of the g-C3N4 includes the following steps:
[0023] Mix melamine, phosphorous acid, and deionized water and stir in an oil bath. Transfer it into a reaction kettle and carry out hydrothermal reaction. Wash with water, centrifuge, and dry to obtain a precursor. Take the precursor and reflux it with glycerol and ethanol under the condition of an oil bath. After the reflux ends, wash, centrifuge, and dry in sequence. Finally, pyrolyze the obtained material in a muffle furnace.
[0024] The preparation method of the ANF includes the following steps:
[0025] Ultrasonically treat with acetone to remove the impurities contained in Kevlar 49, and place it in an oven to dry. Add Kevlar 49 and potassium hydroxide into the dimethyl sulfoxide solvent in sequence, heat in an oil bath, and stir to obtain an ANF / dimethyl sulfoxide dispersion. Then protonate it. Take the ANF / dimethyl sulfoxide dispersion, add deionized water, and stir to obtain an ANF dispersion.
[0026] Application of the above-mentioned MXene / g-C3N4 / ANF electromagnetic shielding film with a conductive gradient structure, or the electromagnetic shielding material prepared by the preparation method of the above-mentioned MXene / g-C3N4 / ANF electromagnetic shielding film with a conductive gradient structure, in the preparation of electromagnetic shielding devices.
[0027] Advantages of the present invention:
[0028] 1. Introduce strong hydrogen bond interactions between ANF with excellent mechanical properties and MXene, enhancing the mechanical properties of the MXene-based shielding material.
[0029] 2. Introduce a dielectric matching material g-C3N4, which generates dielectric loss while reducing the intrinsic conductivity of MXene to enhance the electromagnetic shielding performance. In addition, g-C3N4 can also generate hydrogen bond interactions with aramid nanofibers and MXene respectively, endowing the shielding material with synergistic mechanical strength.
[0030] 3. Reasonably design the conductive gradient structure of the composite material, so that the conductive fillers form a conductive gradient in the direction from the top layer to the bottom layer, improving the impedance matching performance, thereby enhancing the effective shielding and attenuation of the shielding material for incident electromagnetic waves, reducing the reflection loss, and avoiding secondary pollution. Description of the drawings
[0031] The present invention will be further described below in conjunction with the accompanying drawings.
[0032] Figure 1 It is the experimental data graph of this application;
[0033] Figure 2 It is the physical diagram of the MCNA55-73-91 conductive gradient composite film of this application. Specific embodiments
[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.
[0035] In some embodiments of the present invention, a preparation method of an MXene / g-C3N4 / ANF electromagnetic shielding film with a conductive gradient structure is disclosed, which may include the following steps:
[0036] First, the required raw materials are synthesized separately: MXene is synthesized by in-situ etching method, g-C3N4 is synthesized by hydrothermal method, and ANF is synthesized by deprotonation method. Secondly, the three are stacked and filtered on a polyethylene terephthalate nuclear pore filter membrane by vacuum-assisted filtration.
[0037] Specifically, the MXene aqueous dispersion (1 mg / g), g-C3N4 aqueous dispersion (0.5 mg / g), and ANF aqueous dispersion (1 mg / g) are ultrasonically treated for about 3 h respectively to obtain uniform solutions. The total load of each membrane is 150 mg. MXene, g-C3N4, and ANF are added to the system in a certain mass percentage (for specific examples of the ratio, see the MCNA37-55-73 and MCNA55-73-91 conductive gradient composite films). The obtained mixed solution is first ultrasonically treated for 1 h and finally homogenized for 10 min, and the finally obtained solution is stacked on a polyethylene terephthalate nuclear pore filter membrane (diameter 50 mm, pore diameter 0.22 μm) by vacuum-assisted filtration process. The finally obtained composite film is fixed with a 200-mesh standard copper mesh and dried at room temperature. In this embodiment, the following three composite films are prepared by the above method:
[0038] MCNA 37-55-73 Conductive Gradient Composite Film: The total load is 150 mg (45 mg of MXene, 45 mg of g-C3N4, and 60 mg of ANF), divided into three layers, with a load of 50 mg per layer. The top layer ratio is: 9 mg of MXene, 21 mg of g-C3N4, and 20 mg of ANF; the middle layer ratio is: 15 mg of MXene, 15 mg of g-C3N4, and 20 mg of ANF; the bottom layer ratio is: 21 mg of MXene, 9 mg of g-C3N4, and 20 mg of ANF;
[0039] MCNA 55-73-91 Conductive Gradient Composite Film: The total load is 150 mg (63 mg of MXene, 27 mg of g-C3N4, and 60 mg of ANF), divided into three layers, with a load of 50 mg per layer. The top layer ratio is: 15 mg of MXene, 15 mg of g-C3N4, and 20 mg of ANF; the middle layer ratio is: 21 mg of MXene, 9 mg of g-C3N4, and 20 mg of ANF; the bottom layer ratio is: 27 mg of MXene, 3 mg of g-C3N4, and 20 mg of ANF.
[0040] The MXene, g-C3N4, and ANF used in the above experiments were all prepared by ourselves. Now, the raw materials and detailed preparation steps for each material are listed as follows:
[0041] 1. Raw materials: Ti3AlC2 MAX powder (purity ≥ 98 wt%) was purchased from Jilin Yiyi Technology Co., Ltd. Kevlar 49 was purchased from Shanghai DuPont Company. Lithium fluoride, melamine, solid phosphorous acid, glycerol, absolute ethanol, potassium hydroxide, and dimethyl sulfoxide were all purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. Hydrochloric acid was purchased from Sinopharm Chemical Reagent Co., Ltd. All chemicals were of analytical grade and were not further purified. Deionized water was used in this experiment.
[0042] 2. Preparation of MXene
[0043] Accurately weigh 1 g of Ti3AlC2 raw material and 1.6 g of lithium fluoride for standby. Add 20 mL of 9 M hydrochloric acid to the polytetrafluoroethylene inner lining, then directly add 1.6 g of lithium fluoride, stir for 3 - 5 minutes until the lithium fluoride is completely dissolved, and then slowly add 1 g of Ti3AlC2 to the solution under ice bath conditions within 3 - 5 min. After adding, carry out a constant temperature magnetic stirring reaction at 35 °C for 36 h. Then transfer the mixed solution in the polytetrafluoroethylene inner lining to a centrifuge tube, and centrifuge and wash repeatedly several times until the pH of the upper layer solution reaches 7. Subsequently, break it with a cell disruptor for 30 min under an argon atmosphere. Finally, vacuum freeze-dry the obtained solution to obtain nanosheet materials.
[0044] 3. Preparation of g-C3N4
[0045] Accurately weigh 1 g of melamine, 1.2 g of phosphorous acid, and 100 ml of deionized water. After mixing the three, stir vigorously in an 80 °C oil bath for 1 h. After the stirring ends, transfer it into a reaction kettle and carry out a hydrothermal reaction at 180 °C for 10 h. Subsequently, wash it three times with water, and centrifuge it, and then dry it at 60 °C to obtain a precursor. Weigh 0.6 g of the precursor, 5 ml of glycerol, and 15 ml of ethanol, and reflux them in a 90 °C oil bath for 3 h. After the reflux ends, wash it three times with ethanol, and centrifuge it, and then dry it at 60 °C. Finally, pyrolyze the obtained material in a muffle furnace at a heating rate of 2 °C / min at 500 °C for 2 h to obtain the final required nanosheets.
[0046] 4. Preparation of ANF
[0047] First, ultrasonically treat it with acetone for 4 h to remove the impurities contained in Kevlar 49, and place it in a 60 °C oven for drying. Accurately weigh 2 g of Kevlar 49 and 1.5 g of potassium hydroxide, and add them successively to 500 ml of dimethyl sulfoxide solvent. Heat it in a 35 °C oil bath and stir it at 800 rpm for 7 days to obtain an ANF / dimethyl sulfoxide dispersion. Then protonate it. Take 100 ml of the ANF / dimethyl sulfoxide dispersion, add 500 ml of deionized water, and stir it at 500 rpm at room temperature for 6 h to obtain an ANF / H2O dispersion.
[0048] Due to the poor mechanical properties and high intrinsic conductivity of MXene, aramid nanofibers with high mechanical strength and the dielectric matching material graphitic carbon nitride are respectively introduced into the components to form a dense stacked internal layered structure, achieving a balance between high mechanical strength and electromagnetic shielding performance. Further, through the design of a conductive gradient structure, a transition layer (top layer and middle layer) and a reflection layer (bottom layer) are divided, optimizing the impedance matching of the composite material. Research shows that through scanning electron microscopy, a dense layered stacked structure is observed in the cross-section of the composite film, and the distribution of Ti elements shows that the composite film has an obvious conductive gradient ( Figure 1 a in it is the cross-sectional scanning morphology and Ti element energy spectrum diagram of the MCNA55-73-91 conductive gradient composite film). The composite film has excellent electromagnetic shielding performance. Compared with MCNA37-55-73 (11.3 dB), the EMI SE value of the MCNA55-73-91 conductive gradient composite film is as high as 35.2 dB (8.2 - 12.4 GHz) ( Figure 1 b in it), and the absorption coefficients A are 0.18 and 0.17 respectively ( Figure 1 c in it). In addition, the composite film has strong mechanical properties. The tensile strengths of the MCNA37-55-73 and MCNA55-73-91 conductive gradient composite films are 146.3 MPa and 166.7 MPa respectively, and the toughnesses are 14.6 MJ m -3and 21.7 MJ m -3 ( Figure 1 d) in. In addition, the MCNA55-73-91 guiding elevator gradient composite film also exhibits long-term stable Joule heating performance of 3500 s( Figure 1 e) in.
[0049] In the description of this specification, the descriptions referring to terms such as "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.
[0050] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments, and the above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.
Claims
1. An MXene / g-C3N4 / ANF electromagnetic shielding film with a guiding gradient structure, characterized in that, It includes the following raw materials: MXene, g-C3N4, and ANF.
2. The MXene / g-C3N4 / ANF electromagnetic shielding film with a guiding gradient structure according to claim 1, characterized in that, The electromagnetic shielding film is a gradient composite film, including a top layer, a middle layer and a bottom layer. The content of MXene in the top layer, middle layer and bottom layer increases in turn, and the content of g-C3N4 in the top layer, middle layer and bottom layer decreases in turn.
3. The MXene / g-C3N4 / ANF electromagnetic shielding film with a guiding gradient structure according to claim 1, wherein The total mass ratio of MXene, g-C3N4 and ANF in the composite film is 45:45:60 or 63:27:
60.
4. The MXene / g-C3N4 / ANF electromagnetic shielding film with a guiding gradient structure according to claim 2, characterized in that, In the top layer, middle layer and bottom layer, the mass ratios of MXene, g-C3N4 and ANF are 9:21:20, 15:15:20 and 21:9:20 respectively, or 15:15:20, 21:9:20, 27:3:
20.
5. A preparation method of an MXene / g-C3N4 / ANF electromagnetic shielding film with a guiding gradient structure, characterized in that, It includes the following steps: Prepare MXene aqueous dispersion, g-C3N4 aqueous dispersion and ANF aqueous dispersion; Ultrasonically mix the prepared MXene aqueous dispersion, g-C3N4 aqueous dispersion and ANF aqueous dispersion to obtain a mixed solution; Load the mixed solution onto a base film.
6. The preparation method of the MXene / g-C3N4 / ANF electromagnetic shielding film with a guiding gradient structure according to claim 5, characterized in that, The base film is a polyethylene terephthalate nuclear pore filter membrane. The concentrations of the MXene aqueous dispersion, g-C3N4 aqueous dispersion and ANF aqueous dispersion are 0.5 mg / g, 1 mg / g and 1 mg / g respectively.
7. The preparation method of the MXene / g-C3N4 / ANF electromagnetic shielding film with a guiding gradient structure according to claim 5, characterized in that, The loading method is: stacking on the base film through a vacuum-assisted suction filtration process.
8. The preparation method of the MXene / g-C3N4 / ANF electromagnetic shielding film with a guiding gradient structure according to claim 5, characterized in that, The total mass ratio of MXene, g-C3N4 and ANF in the composite film is 45:45:60 or 63:27:
60.
9. The preparation method of the MXene / g-C3N4 / ANF electromagnetic shielding film with a conductive gradient structure according to claim 5, characterized in that The preparation method of the MXene includes the following steps: Add hydrochloric acid into a polytetrafluoroethylene inner liner, then add lithium fluoride, stir until completely dissolved, and then add Ti3AlC2 under an ice bath condition, and carry out magnetic stirring reaction; then transfer the mixed solution in the polytetrafluoroethylene inner liner to a centrifuge tube, and centrifuge and wash repeatedly for several times until the pH of the upper layer solution reaches 7; then break it with a cell disruptor under the protection of inert gas; freeze-dry the obtained solution under vacuum; The preparation method of the g-C3N4 includes the following steps: Mix melamine, phosphorous acid and deionized water and stir in an oil bath; transfer it into a reaction kettle and carry out hydrothermal reaction; wash with water and centrifuge, and dry to obtain a precursor; take the precursor and reflux it with glycerol and ethanol under the condition of an oil bath; after the reflux ends, carry out cleaning, centrifugation and drying in turn, and finally pyrolyze the obtained material in a muffle furnace; The preparation method of the ANF includes the following steps: Ultrasonically treat with acetone to remove impurities contained in Kevlar 49, and place it in an oven for drying; add Kevlar 49 and potassium hydroxide into dimethyl sulfoxide solvent in sequence, heat in an oil bath and stir to obtain an ANF / dimethyl sulfoxide dispersion; then protonate it, take the ANF / dimethyl sulfoxide dispersion, add deionized water and stir to obtain an ANF dispersion.
10. Use of the MXene / g-C3N4 / ANF electromagnetic shielding film having a conductive gradient structure according to any one of claims 1 to 4, or the electromagnetic shielding material prepared by the method for preparing the MXene / g-C3N4 / ANF electromagnetic shielding film having a conductive gradient structure according to any one of claims 5 to 9, in the preparation of electromagnetic shielding devices.