Nanofilm for electromagnetic shielding and preparation method and application thereof

Abstract

This invention discloses a nanofilm for electromagnetic shielding, its preparation method, and its applications. The invention first prepares an MXene suspension; then mixes the MXene suspension with anhydrous ethanol to obtain an electrospraying solution; next, it mixes polyacrylonitrile with enzymatically hydrolyzed lignin to prepare a spinning solution; using the electrospraying solution and the spinning solution, it assembles an upper lignin / PAN nanofiber membrane, a middle MXene@lignin / PAN composite membrane, and a lower lignin / PAN nanofiber membrane into a sandwich-layer structure, forming a "spinning + spraying" nanofilm. The "spinning + spraying" nanofilm prepared by this invention has the advantages of low-conductivity filler and high electromagnetic shielding performance, and can be used in aerospace, defense, and next-generation wearable flexible electronics, showing broad market application prospects.

Description

Technical Field

[0001] This invention relates to a nanofilm for electromagnetic shielding, its preparation method and application, belonging to the field of electromagnetic shielding materials technology. Background Technology

[0002] With the rapid development of electronic devices and wireless communication technologies, electromagnetic pollution has become increasingly serious, making the development of high-performance electromagnetic shielding materials a research hotspot. While traditional metal-based electromagnetic shielding materials (such as copper and aluminum) possess excellent shielding effectiveness, their high density, susceptibility to corrosion, and poor processing flexibility make them unsuitable for meeting the demands of modern electronic devices for flexible and lightweight electromagnetic shielding materials. Therefore, developing novel, high-performance, lightweight, and flexible electromagnetic shielding materials is of significant practical importance.

[0003] Electrospinning is an effective method for preparing nanofibers, which possess large specific surface area and high aspect ratio, and are widely used in electromagnetic shielding, optics, and thermal management. Lignin, as an abundant and renewable natural polymer material, has advantages such as low cost, biodegradability, and rich aromatic ring structure; however, its utilization rate is low, leading to resource waste. It is worth noting that lignin can be electrospun into nanofiber membranes using spinning aids. These membranes are lightweight, flexible, and porous, providing an effective way to utilize lignin resources.

[0004] MXene, as a novel two-dimensional material, possesses high conductivity, large specific surface area, and good surface activity, and has attracted much attention in the field of electromagnetic shielding in recent years. However, pure MXene films are costly and have poor mechanical properties, making it difficult to meet the needs of practical applications. Furthermore, MXene sheets are prone to stacking, hindering the full utilization of their surface and interface effects. Therefore, addressing these issues through material composites and structural design has become crucial for the research of MXene-based electromagnetic shielding materials.

[0005] The literature (Zhou B, Zhang Z, Li Y, et al. Flexible, robust, and multifunctional electromagnetic interference shielding film with alternating cellulose nanofiber and MXene layers[J].ACS applied materials & interfaces, 2020, 12(4): 4895-4905.) discloses the preparation of multilayer films containing alternating cellulose nanofiber (CNF) layers and MXene layers by alternating vacuum filtration method. However, due to the severe stacking phenomenon of MXene, the electromagnetic shielding performance is only 39.6 dB with MXene addition of 44%. Summary of the Invention

[0006] To address the aforementioned issues, this invention first mixes lithium fluoride (LiF) and hydrochloric acid (HCl), adds titanium aluminum carbide (Ti3AlC2), and reacts with stirring for 48 hours. After centrifugation, washing, and ultrasonic exfoliation, an MXene dispersion is obtained. The MXene suspension is then mixed with anhydrous ethanol to obtain an electrospraying solution. Next, polyacrylonitrile (PAN) and N,N-dimethylformamide (DMF) are mixed, and enzymatically hydrolyzed lignin is added. After stirring for 24 hours, a spinning solution is obtained. Finally, the electrospraying solution and the spinning solution are placed separately in syringes, and the electrospinning and electrospraying parameters are adjusted to prepare a sandwich-layered "spinning + spraying" nanofilm consisting of an upper lignin / PAN nanofiber membrane, a middle MXene@lignin / PAN composite membrane, and a lower lignin / PAN nanofiber membrane. The "spinning + spraying" nanofilm for electromagnetic shielding prepared by this invention is lightweight, flexible, and possesses excellent electromagnetic shielding performance, making it suitable for a wide range of market applications in aerospace, defense, and next-generation flexible wearable electronic devices.

[0007] The first objective of this invention is to provide a method for preparing a nanofilm for electromagnetic shielding, comprising the following steps:

[0008] (1) Mix lithium fluoride and hydrochloric acid, add titanium aluminum carbide to react, and then ultrasonically peel off the reaction to obtain MXene suspension;

[0009] (2) Mix the MXene suspension with a volatile organic solvent to obtain an electro-spraying liquid;

[0010] (3) Add polyacrylonitrile to an organic solvent and mix, add enzymatically hydrolyzed lignin, and stir thoroughly to obtain a spinning solution;

[0011] (4) The upper lignin / polyacrylonitrile nanofiber membrane is prepared by electrospinning using the spinning solution of step (3). The middle MXene@lignin / polyacrylonitrile composite membrane is prepared by electrospinning using the electrospraying solution of step (2) and the spinning solution of step (3). The lower lignin / polyacrylonitrile nanofiber membrane is prepared by electrospinning using the spinning solution of step (3). The three membranes are assembled in sequence to form the nanofilm used for electromagnetic shielding.

[0012] In one embodiment of the present invention, the concentration of the MXene suspension in step (1) is 10 mg / mL to 25 mg / mL.

[0013] In one embodiment of the present invention, the mass ratio of lithium fluoride to titanium aluminum carbide in step (1) is 1:0.5 to 2.

[0014] In one embodiment of the present invention, the reaction temperature in step (1) is 35°C to 40°C and the reaction time is 40 to 60 hours.

[0015] In one embodiment of the present invention, the concentration of hydrochloric acid in step (1) is 6-10 M.

[0016] In one embodiment of the present invention, the ultrasonic time in step (1) is 0.5-3h and the ultrasonic power is 300-500W.

[0017] In one embodiment of the present invention, step (1) further includes a washing step after the reaction, wherein the washing is performed by centrifugation at 3000-7000 rpm for 1-5 min.

[0018] In one embodiment of the present invention, in step (2), the volatile organic solvent is anhydrous ethanol, and the volume ratio of MXene suspension to anhydrous ethanol is 1-2:2-1.

[0019] In one embodiment of the present invention, the mass ratio of polyacrylonitrile and enzymatically hydrolyzed lignin in step (3) is 6-8:3.

[0020] In one embodiment of the present invention, the organic solvent in step (3) is one of N,N-dimethylformamide, dimethyl sulfoxide, a mixed solvent of acetone and N,N-dimethylformamide, or a mixed solvent of tetrahydrofuran and N,N-dimethylformamide.

[0021] In one embodiment of the present invention, the solid content of the spinning solution in step (3) is 10wt% to 20wt%.

[0022] In one embodiment of the present invention, the voltage for electrospinning the upper and lower layers in step (4) is 12-20 kV, the injection speed is 0.5-1 mL / h, and the spinning time is 1-5 h.

[0023] In one embodiment of the present invention, the preparation of the intermediate layer in step (4) involves simultaneous electrospinning and electrostatic spraying. The electrostatic spraying injection speed is 0.5–7 mL / h, the voltage is 12–20 kV, and the time is 6–11 h.

[0024] In one embodiment of the present invention, the loading of MXene in the nanofilm in step (4) is 2.5%-15%.

[0025] The second objective of this invention is to prepare a nanofilm for electromagnetic shielding using the method described in this invention.

[0026] A third objective of this invention is the application of the nanofilms for electromagnetic shielding described herein in the fields of aerospace, defense, or next-generation flexible wearable electronic devices.

[0027] The fourth objective of this invention is to provide an electromagnetic shielding material that employs the nanofilm for electromagnetic shielding described in this invention.

[0028] The beneficial effects of this invention are:

[0029] (1) By combining electrospinning and electrostatic spraying technologies, this invention successfully prepared an electromagnetic shielding composite film with a sandwich layer structure. This method is simple and easy to control, and can uniformly load MXene onto the surface of nanofibers, reducing the stacking phenomenon of MXene. It can not only improve the utilization rate of MXene and improve surface conductivity, but also create a heterogeneous interface and improve electromagnetic wave loss.

[0030] (2) This invention utilizes continuous electrostatic spraying and electrospinning operations to achieve self-assembly under strong van der Waals forces, forming a three-dimensional nanofiber network layered structure. This structure consists of a conductive layer formed by the self-deposited MXene layer and a void layer formed by a few nanofibers, creating a continuous alternation between conductive and insulating layers. This facilitates the loss of electromagnetic wave energy. The electromagnetic shielding nanofilm prepared by this invention has the advantage of high electromagnetic shielding performance with low conductive filler content. When the MXene content is 15%, the electromagnetic shielding effectiveness (EMI SE) of the film reaches 44.1 dB.

[0031] (3) The electromagnetic shielding nanofilm prepared by the present invention slows down the oxidation of MXene and improves its durability due to its reasonable sandwich structure design. 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 some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0033] Figure 1 This is a schematic diagram illustrating the preparation mechanism of the "spinning + spraying" nanofilm used for electromagnetic shielding in this invention.

[0034] Figure 2 The images show actual photos of the "spinning + spraying" nanofilm used for electromagnetic shielding in Example 1 folded into different shapes.

[0035] Figure 3 The images shown are scanning electron microscope (SEM) images of the "spinning + spraying" nanofilm used for electromagnetic shielding in Example 1, where (a) is a planar SEM image of the intermediate layer with a diameter of 4 μm; and (b) is a cross-sectional SEM image of the intermediate layer with a diameter of 20 μm.

[0036] Figure 4 The electromagnetic shielding performance diagrams are for the "spinning + spraying" nanofilms used for electromagnetic shielding in Examples 1-4.

[0037] Figure 5 The results are the durability test results of the "spinning + spraying" nanofilm used for electromagnetic shielding in Example 4. Detailed Implementation

[0038] The preferred embodiments of the present invention are described below. It should be understood that the embodiments are for better explanation of the present invention and are not intended to limit the present invention.

[0039] Test method:

[0040] 1. Microscopic morphology test:

[0041] The tests were conducted using a cold field emission scanning electron microscope, model Regulus 8100.

[0042] 2. Electromagnetic shielding effect test:

[0043] The network vector analyzer, model DR-S, was used for testing in the X-band (8.2-12.4 GHz).

[0044] Raw materials used in the examples:

[0045] Titanium aluminum carbide (Ti3AlC2): 400 mesh, purchased from Eleven Technology Co., Ltd.

[0046] Lithium fluoride (LiF): analytical grade, purchased from Shanghai Aladdin Chemical Reagent Co., Ltd.

[0047] Hydrochloric acid (HCl): analytical grade, purchased from Sinopharm Reagent Co., Ltd.

[0048] N,N-Dimethylformamide (DMF): Analytical grade, purchased from Sinopharm Reagent Co., Ltd.

[0049] Polyacrylonitrile (PAN), Mw = 150,000, purchased from Suzhou Great Medical Technology Co., Ltd.

[0050] Anhydrous ethanol: analytical grade, purchased from Sinopharm Chemical Reagent Co., Ltd.

[0051] Enzymatic hydrolysis of lignin was prepared as follows: Straw was crushed to 1-5 mm particles using a hammer mill, treated with 1.5 MPa saturated steam for 5-10 minutes, and then washed with 60°C hot water. After solid-liquid separation, a pretreated raw material was obtained. This pretreated raw material was then adjusted to a 15 wt% lignocellulose slurry using pH 4.8 phosphate buffer. Laccase and ABTS were covalently immobilized on porous resin (enzyme loading = 120 U / g carrier) to obtain a laccase-mediate composite carrier. This composite carrier was filled into a fixed-bed continuous flow reactor. The lignocellulose slurry flowed through the reactor at a rate of 0.5 BV / h, the reaction temperature was 50°C, and the oxygenation rate was 0.1 vvm. The effluent was subjected to ceramic membrane ultrafiltration (50 kDa) to remove undegraded components. The permeate contained soluble lignin fragments. The permeate was adjusted to pH... 2.0 After lignin precipitation, it was separated by a disc centrifuge (3000 rpm, 10 min) and spray-dried (inlet air temperature 180℃, outlet air temperature 80℃) to obtain powdered enzymatically hydrolyzed lignin.

[0052] Unless otherwise specified, the percentages (%) used in the examples refer to mass percentages.

[0053] The technical solution of the present invention will be described in detail below with reference to specific embodiments. In the following embodiments, unless otherwise specified, the reagents, materials and equipment used can be purchased commercially, prepared by conventional methods, or commonly used in the industry.

[0054] Example 1

[0055] A method for preparing a spinning-spray nanofilm for electromagnetic shielding includes the following steps:

[0056] (1) Mix 2g lithium fluoride (LiF) and 40mL 9M hydrochloric acid (HCl) evenly, then add 2g titanium aluminum carbide (Ti3AlC2) and stir at 35℃ for 48 hours. Centrifuge and wash, sonicate for 1 hour, and centrifuge to collect the supernatant, which is the MXenen dispersion.

[0057] (2) Mix 20 mg / mL MXene dispersion with an equal volume of anhydrous ethanol to obtain an electrospraying solution;

[0058] (3) Add 1.33g of polyacrylonitrile (PAN) to 10g of N,N-dimethylformamide (DMF) and stir until uniform. Then add 0.57g of enzymatically hydrolyzed lignin and stir for 24 hours to obtain a uniform spinning solution with a solid content of 16wt%. The mass ratio of polyacrylonitrile (PAN) to enzymatically hydrolyzed lignin is 7:3.

[0059] (4) Place 4.9 mL of electrospraying solution and 12 mL of spinning solution into syringes respectively. Adjust the electrospinning injection speed to 0.8 mL / h, the electrospraying speed to 0.5 mL / h, the applied voltage to 17 kV, the roller speed to 100 rpm, and the receiving distance to 15 cm. First, prepare the lower lignin / PAN nanofiber membrane, with an electrospinning time of 3 h; then prepare the middle MXene@lignin / PAN composite membrane, with a spinning + spraying time of 9 h; finally, prepare the upper lignin / PAN nanofiber membrane, with a spinning time of 3 h, and finally assemble a sandwich-layer structure of "spinning + spraying" nanomembrane, in which the MXene loading is 2.5%.

[0060] Figure 2 Images showing the "spinning + spraying" nanofilm with its sandwich-like layered structure folded into different shapes. Figure 3 This is a scanning electron microscope image of the "spinning + spraying" nanofilm with a sandwich-like layered structure.

[0061] Comparative Example 1:

[0062] This application also optimized the mass ratio of polyacrylonitrile to enzymatically hydrolyzed lignin as follows:

[0063] The other steps are the same as in Example 1, and the solid content of step (3) is fixed at 16wt%. The only difference is that the ratio of polyacrylonitrile and lignin is adjusted to 5:5. Electrospinning is performed, and the resulting spun film is brittle and the fibers have some beading and lack a certain degree of flexibility.

[0064] The other steps are the same as in Example 1, and the solid content of step (3) is fixed at 16wt%. The ratio of polyacrylonitrile and lignin is adjusted to 6:4. Electrospinning is performed, and the resulting spun film has relative flexibility, but is still not flexible enough.

[0065] In Example 1, when the ratio of polyacrylonitrile to lignin was 7:3, electrospinning was performed, and the resulting spun film had good flexibility, and the fibers were free of beads and uniform in size.

[0066] Example 2

[0067] In step (4) of Example 1, the volume of the electrospraying liquid was adjusted to 10 mL, and the electrostatic spraying speed was adjusted to 1.1 mL / h. Everything else remained the same as in Example 1, resulting in a "spinning + spraying" nanofilm; wherein the MXene loading was 5%.

[0068] Example 3

[0069] In step (4) of Example 1, the volume of the electrospraying liquid was adjusted to 21 mL, and the electrostatic spraying speed was adjusted to 2.3 mL / h. Everything else remained the same as in Example 1, resulting in a "spinning + spraying" nanofilm; wherein the MXene loading was 10%.

[0070] Example 4

[0071] In step (4) of Example 1, the volume of the electrospraying liquid was adjusted to 33.5 mL, and the electrostatic spraying speed was adjusted to 3.7 mL / h. Everything else remained the same as in Example 1, resulting in a "spinning + spraying" nanofilm; wherein the MXene loading was 15%.

[0072] The obtained "spinning + spraying" nanofilm was subjected to performance testing, and the test results are as follows:

[0073] Figure 4 The figures show the electromagnetic shielding performance of the "spinning + spraying" nanofilms used for electromagnetic shielding in Examples 1-4. Figure 4 It can be seen that: when the solid content of MXene in the nanofilm is 2.5% (Example 1), the electromagnetic shielding performance can reach 19dB; when the solid content of MXene in the nanofilm is 5% (Example 2), the electromagnetic shielding performance can reach 23.3dB; when the solid content of MXene in the nanofilm is 10% (Example 3), the electromagnetic shielding performance can reach 33.1dB; and when the solid content of MXene in the nanofilm is 15% (Example 4), the electromagnetic shielding performance can reach 44.1dB.

[0074] The "spinning + spraying" nanofilm prepared in Example 4 was subjected to durability testing, and the unassembled intermediate layer MXene@lignin / PAN composite film from Example 4 was used as a control for durability testing. The sandwich structure showed an electromagnetic shielding performance decrease of only 4.1 dB after 4 months of storage, while the single intermediate layer showed a decrease of 9 dB after four months. The comparison is as follows. Figure 5 As shown.

[0075] Example 5

[0076] In step (4) of Example 4, the electrospinning time of the upper and lower layers was adjusted to 1 h, the "spinning + spraying" time of the middle layer was 13 h, and the electrostatic spraying injection speed was 2.58 mL / h; the rest remained the same as in Example 1, and a "spinning + spraying" nanofilm was obtained.

[0077] Example 6

[0078] In step (4) of Example 4, the electrospinning time of the upper and lower layers was adjusted to 2h, the "spinning + spraying" time of the middle layer was 11h, and the electrostatic spraying injection speed was 3.05mL / h; the rest remained the same as in Example 1, and a "spinning + spraying" nanofilm was obtained.

[0079] Example 7

[0080] In step (4) of Example 4, the electrospinning time for the upper and lower layers was adjusted to 4 hours, and the "spinning + spraying" time for the middle layer was adjusted to 7 hours. The electrostatic spraying injection speed was adjusted to 4.79 mL / h.

[0081] Everything else remained the same as in Example 1, resulting in a "spinning + spraying" nanofilm.

[0082] Example 8

[0083] In step (4) of Example 4, the electrospinning time for the upper and lower layers was adjusted to 5 hours, and the "spinning + spraying" time for the middle layer was adjusted to 5 hours. The electrostatic spraying injection speed was adjusted to 6.7 mL / h.

[0084] Everything else remained the same as in Example 1, resulting in a "spinning + spraying" nanofilm.

[0085] In this application, by controlling the speed of electrostatic spraying, the solid content of MXene in the nanofilms prepared in Examples 5 to 8 is 15%.

[0086] Comparative Example 2: Nanofilms with the same MXene loading were prepared using a blending method.

[0087] Adjust steps (2), (3), and (4) of Example 4 as follows:

[0088] The MXene dispersion was pre-frozen in a -20°C refrigerator for 12 hours and then freeze-dried in a freeze dryer to obtain MXene powder. 335 mg of the powder was dissolved in 11.6 g of N,N-dimethylformamide (DMF) and stirred evenly. 1.33 g of polyacrylonitrile (PAN) and 0.57 g of enzymatically hydrolyzed lignin were added and stirred evenly to obtain a spinning solution with a solid content of 16 wt%, wherein the MXene loading was 15%. Spinning was carried out according to the spinning conditions in step (4) of Example 4.

[0089] Everything else remained the same as in Example 1, resulting in a blended nanofilm.

[0090] Comparative Example 3: Preparation of nanofilms using a spinning-then-spraying method

[0091] Adjust step (4) of Example 4 as follows:

[0092] First, electrospinning is carried out for 15 hours, followed by electrostatic spraying for 9 hours.

[0093] Everything else remained the same as in Example 1, resulting in a nanofilm with MXene sprayed on one side.

[0094] Comparative Example 4: Preparation of an intermediate layer of electrospun nanofibers and two sides of electrospun MXene nanosheets.

[0095] Adjust step (4) of Example 4 as follows:

[0096] First, electrospinning is performed for 15 hours, followed by electrostatic spraying for 4.5 hours. Then, the nanofilm is peeled off from the tin foil and electrostatic spraying is performed on the reverse side for 4.5 hours.

[0097] Everything else remained the same as in Example 1, resulting in a nanofilm coated with MXene on both sides.

[0098] Comparative Example 5:

[0099] The electrostatic spraying operations in steps (1), (2) and (4) of Example 4 are omitted, and the rest is consistent with Example 4 to obtain a lignin / PAN nanofilm.

[0100] The nanofilms prepared in Examples 4-8 and Comparative Examples 2-5 were subjected to performance tests, and the test results are as follows:

[0101] Table 1

[0102] Example 4 44.1 Example 5 42.3 Example 6 43.0 Example 7 38.4 Example 8 35.7 Comparative Example 2 1.9 Comparative Example 3 33.5 Comparative Example 4 37.1 Comparative Example 5 0.23

[0103] As shown in Table 1, the electromagnetic shielding effects of Examples 4-6 are not significantly different, while the electromagnetic shielding effects of Examples 7 and 8 are relatively low. This is because the intermediate layer in Examples 4-6 is thicker, and the resulting layer structure can effectively dissipate electromagnetic waves multiple times. In contrast, in Examples 7 and 8, the intermediate layer is thinner, leading to MXene accumulation. Therefore, the same amount of MXene results in a lower electromagnetic shielding effect. In Comparative Example 2, the nanofilms prepared using a blending method with the same MXene loading showed severe MXene accumulation and a very poor electromagnetic shielding effect. The nanofilms prepared by single-sided and double-sided spraying methods in Comparative Examples 3 and 4 also failed to solve the problem of MXene stacking, and their electromagnetic shielding effects were also weak.

[0104] The embodiments provided above are not intended to limit the scope of the invention, nor are the described steps intended to limit the order of execution. Any obvious modifications made to the invention by those skilled in the art based on existing common knowledge also fall within the scope of protection defined by the claims.

Claims

1. A method for preparing a nanofilm for electromagnetic shielding, characterized in that, Includes the following steps: (1) Mix lithium fluoride and hydrochloric acid, add titanium aluminum carbide to react, and then ultrasonically peel off the reaction to obtain MXene suspension; (2) The MXene suspension was mixed with a volatile organic solvent to obtain an electro-spraying liquid; (3) Add polyacrylonitrile to an organic solvent and mix, add enzymatically hydrolyzed lignin, and stir thoroughly to obtain a spinning solution; (4) The upper lignin / polyacrylonitrile nanofiber membrane is prepared by electrospinning using the spinning solution of step (3). The middle MXene@lignin / polyacrylonitrile composite membrane is prepared by electrospinning using the electrospraying solution of step (2) and the spinning solution of step (3). The lower lignin / polyacrylonitrile nanofiber membrane is prepared by electrospinning using the spinning solution of step (3). The three membranes are assembled in sequence to form the nanofilm used for electromagnetic shielding.

2. The preparation method according to claim 1, characterized in that, The concentration of the MXene suspension in step (1) is 10 mg / mL to 25 mg / mL.

3. The preparation method according to claim 1, characterized in that, In step (1), the mass ratio of lithium fluoride to titanium aluminum carbide is 1:0.5-2; the reaction temperature is 35℃-40℃ and the reaction time is 40-60h.

4. The preparation method according to claim 1, characterized in that, In step (3), the mass ratio of polyacrylonitrile to enzymatically hydrolyzed lignin is 6–8:

3.

5. The preparation method according to claim 1, characterized in that, The solid content of the spinning solution in step (3) is 10wt% to 20wt%.

6. The preparation method according to claim 1, characterized in that, In step (4), the voltage for electrospinning the upper and lower layers is 12-20 kV, the injection speed is 0.5-1 mL / h, and the spinning time is 1-5 h.

7. The preparation method according to claim 1, characterized in that, In step (4), the intermediate layer is prepared by simultaneously performing electrospinning and electrostatic spraying. The electrostatic spraying injection speed is 0.5-7 mL / h, the voltage is 12-20 kV, and the time is 6-11 h.

8. A nanofilm for electromagnetic shielding prepared by the preparation method according to any one of claims 1 to 7.

9. The application of the nanofilm for electromagnetic shielding as described in claim 8 in the fields of aerospace, defense, or next-generation flexible wearable electronic devices.

10. An electromagnetic shielding material, characterized in that, It employs the nanofilm for electromagnetic shielding as described in claim 8.

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