An MXene-based fiber, electromagnetic shielding fabric, its preparation method and application

Abstract

This invention discloses an MXene-based fiber, an electromagnetic shielding fabric, and their preparation method and applications. The preparation method includes the following steps: polyvinyl alcohol and an MXene solution are mixed uniformly in a certain proportion to obtain a spinning solution; the spinning solution is injected into a calcium ion coagulation bath for curing; the cured fiber is washed with water and dried to obtain dried fiber; polymerizable isocyanate (PMDI), acetonitrile, and methyl hexanoate are mixed in a certain proportion to obtain a crosslinking agent; the obtained dried fiber is immersed in the crosslinking agent and reacted at 60-80℃ for a set time, followed by washing and drying to obtain the MXene-based fiber. This fiber / fabric possesses good flexibility, mechanical properties, and multimodal response (orientation / humidity / temperature / light) electromagnetic shielding effectiveness. The multimodal response behavior enables the textile to automatically adjust its shielding performance over a wide range when receiving external stimuli.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic interference shielding materials technology, specifically relating to an MXene-based fiber, an electromagnetic shielding fabric, its preparation method and application, and its application in the field of electromagnetic shielding. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] The rapid development of electronic products generates electromagnetic interference (EMI) or radiation, which not only affects the normal operation of surrounding equipment but also negatively impacts human health. Therefore, there is an urgent need to develop high-performance EMI shielding materials. In recent years, stretchable conductive fibers have attracted considerable attention because their textiles are becoming ideal platforms for wearable electronic products, such as electronic skin, health monitors, wearable EMI shielding materials, and supercapacitors. These textiles can adapt to various deformations, such as twisting, bending, and stretching, while maintaining the performance and reliability of the devices. Furthermore, conductive fibers can be woven into various patterns with adjustable properties or combined with other textiles to achieve multifunctionality. Wet spinning utilizes the double diffusion and phase change process of a high-concentration solution in a coagulation bath, ultimately solidifying and forming the fiber. It features simple operation, low cost, and the ability to produce fibers in large quantities. Fibers prepared by wet spinning have better mechanical properties.

[0004] Many current research efforts focus on developing stretchable fibers incorporating various conductive materials. MXene, as a novel two-dimensional nanomaterial, possesses excellent conductivity, abundant functional groups, and good hydrophilicity, and has been extensively studied for its potential in wearable electronic devices. While its high conductivity and good hydrophilicity make MXene sheets promising for electromagnetic interference (EMI) shielding and functional textiles, the poor spinnability of MXene dispersions and the weak interfacial interactions between MXene sheets result in poor tensile strength and ductility of its fibers. Furthermore, the easy oxidation of MXene in H2O / O2 environments severely limits its applications.

[0005] Furthermore, the complex and ever-changing environment and the rapid development of the Internet of Things pose new challenges to smart electronic fabrics. Achieving adjustable EMI shielding performance in textiles is challenging due to their fixed composition and structural design. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide an MXene-based fiber, an electromagnetic shielding fabric, its preparation method, and its applications. This fiber / fabric possesses excellent flexibility, mechanical properties, and multimodal response (orientation / humidity / electricity / light) electromagnetic shielding effectiveness. This multimodal response behavior enables the textile to automatically adjust its shielding performance over a wide range when receiving external stimuli.

[0007] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing MXene-based fibers, comprising the following steps:

[0009] Polyvinyl alcohol and MXene solution are mixed evenly in a certain proportion to obtain a spinning solution. The spinning solution is injected into a calcium ion coagulation bath for solidification. The solidified fiber is washed with water and dried to obtain dry fiber.

[0010] A crosslinking agent is obtained by mixing polymerizable isocyanate (PMDI), acetonitrile and methyl hexanoate in a certain proportion.

[0011] The obtained dried fibers are immersed in a crosslinking agent and reacted at 60-80℃ for a set time. After washing and drying, MXene-based fibers are obtained.

[0012] Methyl hexanoate, as an organic solvent, has moderate polarity and can dissolve many organic substances, thus it can be used as a medium for isocyanate reactions.

[0013] In some embodiments, the spinning solution contains 10-13 wt% polyvinyl alcohol and 30-35 mg / mL MXene.

[0014] Preferably, the MXene wafer has an average size of about 3μm and a thickness of about 1.5nm.

[0015] In some embodiments, the concentration of calcium ions in the calcium ion coagulation bath is 5-8 wt%.

[0016] In some embodiments, the volume percentage of PMDI in the crosslinking agent is 5%-15%.

[0017] Preferably, in the crosslinking agent, the volume ratio of acetonitrile to methyl hexanoate is 3-5:1.

[0018] Preferably, the obtained dried fibers are immersed in a crosslinking agent and crosslinked at 60-80°C for 50-100 min.

[0019] More preferably, after the crosslinking reaction is complete, acetone is used to clean the residue on the fiber surface.

[0020] Secondly, the present invention provides an MXene-based fiber prepared by the aforementioned preparation method.

[0021] Thirdly, the present invention provides the application of the MXene-based fibers in the preparation of electronic skin, health monitors, wearable electromagnetic interference shielding fabrics, wearable thermotherapy fabrics, or supercapacitors.

[0022] Fourthly, the present invention provides an electromagnetic shielding fabric woven from the MXene-based fibers.

[0023] The beneficial effects achieved by one or more embodiments of the present invention described above are as follows:

[0024] (1) In this invention, the MXene-based fibers prepared by wet spinning have a simple preparation process, do not require complex equipment, are environmentally friendly, have low production costs, and high yields. The fiber diameter can be controlled by adjusting the injection speed of the injection pump and the needle diameter, thereby adjusting the mechanical properties and electromagnetic shielding properties of the MXene-based textiles.

[0025] (2) The MXene-based fibers and electromagnetic shielding fabrics prepared by this invention, by introducing the hydrophobic backbone of PMDI, ensure the reliability and durability of electronic fabrics in extreme environments such as high temperature and high humidity. The fabrics exhibit excellent antioxidant properties in high temperature and high humidity environments, solving the problem of MXene instability in extreme environments.

[0026] (3) The MXene-based fibers prepared by this invention have good mechanical and electromagnetic shielding properties and can be used to prepare wearable electromagnetic shielding textiles. These electronic textiles can be applied in fields such as health monitors, flexible wearable devices, and wearable electromagnetic shielding materials. The textiles maintain the performance and reliability of the devices under various deformations.

[0027] (4) The electromagnetic shielding fabric prepared by the MXene-based fiber of the present invention can dynamically adjust the shielding effect by adjusting the weaving method and changing the rotation angle, which proves its great application potential as an intelligent shielding switch.

[0028] (5) The excellent moisture absorption of PVA combined with the efficient photo / electrothermal conversion of MXene enables the electromagnetic shielding fabric to achieve wet / photo / electro-modal response behavior, thereby achieving adjustable EMI shielding performance. Attached Figure Description

[0029] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0030] Figure 1 The XRD diffraction pattern of the MXene-based fiber prepared in Example 1.

[0031] Figure 2 The image shows a scanning electron microscope (SEM) image of the MXene-based fibers prepared in Example 2.

[0032] Figure 3 The energy spectrum of the MXene-based fiber prepared in Example 2 is shown.

[0033] Figure 4 This is a physical image of the electromagnetic shielding fabric prepared in Example 2.

[0034] Figure 5 The image shows the X-ray photoelectron spectroscopy (XPS) spectrum of the MXene-based fiber prepared in Example 2.

[0035] Figure 6 The stress-strain curve of the MXene-based fiber prepared in Example 2 is shown.

[0036] Figure 7 The image shows the bending stability test results of the electromagnetic shielding fabric prepared in Example 2.

[0037] Figure 8 The electromagnetic shielding performance diagrams are for the electromagnetic shielding fabrics prepared in Example 2 and the comparative example.

[0038] Figure 9 Graphs showing the changes in EMI SE and resistance of the electromagnetic shielding fabrics prepared for Examples 1 and 2 at 95% RH and 65°C.

[0039] Figure 10 The electromagnetic shielding performance of the MXene-based fiber prepared in Example 2 at different rotation angles is shown in the figure.

[0040] Figure 11 The electromagnetic shielding performance of the MXene-based fiber prepared in Example 2 under light / humidity cycling is shown in the figure.

[0041] Figure 12 The image shows an infrared image of the MXene-based fiber prepared in Example 2 under xenon lamp irradiation. Detailed Implementation

[0042] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0043] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0044] Example 1

[0045] A method for preparing MXene-based fibers includes the following steps:

[0046] (1) Preparation of polyvinyl alcohol (PVA124, viscosity 54-66 mPa·s) solution: Dissolve 10 g of polyvinyl alcohol (PVA) in 90 mL of deionized water, let stand at room temperature for 30 min, and then stir continuously in an oil bath at 95 °C for 10 h until a clear and transparent homogeneous solution is obtained.

[0047] (2) Preparation of MXene aqueous dispersion: The Ti3AlC2 (MAX phase) precursor was etched using a lithium fluoride / hydrochloric acid (LiF / HCl) mixed solution, and then the MXene aqueous dispersion was obtained by layering. First, 6.4 g of lithium fluoride powder was added to 80 ml of hydrochloric acid (6M) solution and stirred at room temperature until dissolved. Then, 4 g of MAX was added to the solution and stirred in a 35°C water bath for 24 hours to completely etch the aluminum layer of MAX. Finally, the suspension was centrifuged several times and washed with deionized water until the pH value was ≈6. After shaking the suspension several times and centrifuging, the supernatant obtained was the MXene aqueous dispersion.

[0048] (3) Preparation of spinning solution: Mix MXene dispersion and polyvinyl alcohol solution in a ratio of 1:1 (solid content) and stir at room temperature for 1-2 hours until the solution is uniform to obtain PVA / MXene composite spinning solution.

[0049] (4) Preparation of PVA / MXene composite fibers: Pour the above PVA / MXene spinning solution into an injection pump, set the wet spinning parameters, and inject it into the coagulation bath by the injection pump. The spun fibers are formed through the solidification process and the drawing process. At the same time, the fibers are collected by the collection device of the wet spinning equipment and dried at room temperature. The wet spinning conditions are: the injection speed of the syringe is 100ml / h, and the needle type is 19G (inner diameter 0.72mm).

[0050] (5) Preparation of PVA / MXene smart electronic fabric: The obtained fibers were woven to the required size using a hand weaving tool. Specifically, the fabric was woven using a parallel weaving method. The fabric used to test the shielding performance was 30mm × 30mm in size, 400-600μm in thickness, and 400g / cm³ in density. 3 Left and right. The textile worn on the wooden figure measures 60mm x 60mm.

[0051] Figure 1 The XRD diffraction patterns of MXene-based fibers prepared in different proportions according to Examples 1, 2, and 4 of this invention are shown. The XRD peaks confirm that the composite fibers are composed of MXene (around 3°) and PVA (around 20°). Furthermore, as the MXene content increases (Example 1), the MXene peak shifts to the right.

[0052] Example 2

[0053] Compared to Example 1, steps (1)-(4) remain unchanged, and the fibers obtained after drying in step (4) are subjected to chemical crosslinking treatment. The chemically crosslinked fibers are prepared by polymethylene polyphenyl polyisocyanate (PMDI) assisted chemical crosslinking.

[0054] (5) Preparation of crosslinking agent: Acetonitrile and methyl hexanoate are mixed in a ratio of 4:1 (V / V) to obtain solution 1; PMDI is dissolved in solution 1 (1:9, V / V) and stirred evenly to obtain crosslinking agent.

[0055] (7) The fiber was immersed in the crosslinking agent and reacted in an oven at 70°C for 90 min. Then, the residue on the sample surface was cleaned with acetone. After drying, chemically crosslinked PVA / MXene fibers were finally obtained.

[0056] (8) Preparation of chemically cross-linked PVA / MXene smart electronic fabric: The obtained fibers are woven on a hand weaving tool. The fabric size can be adjusted for shielding performance testing.

[0057] The SEM and EDS results of the MXene-based fibers prepared in Example 2 are as follows: Figure 2 and Figure 3 As shown, the diameter of the MXene-based fiber is about 300 μm, and the MXene nanosheets are uniformly distributed inside the fiber.

[0058] Optical images of the electromagnetic shielding fabric prepared in Example 2 are shown below. Figure 4 As shown, this demonstrates its potential as a wearable electronic device.

[0059] SEM and XPS images of the MXene-based fibers prepared in Example 2 are shown below. Figure 3 and Figure 5 As shown, the results indicate that the presence of nitrogen indicates successful chemical cross-linking and confirms the effective interaction between the fiber and PMDI.

[0060] The mechanical properties of the MXene-based fibers prepared in Example 2 were tested, and the stress-strain curves were obtained as follows: Figure 6 Through the synergistic effect of hydrogen bonds, ionic bonds, and covalent bonds, chemically cross-linked MXene-based fibers exhibit remarkable mechanical properties. A breaking strength of 220 MPa demonstrates the fiber's excellent mechanical properties, meeting the requirements for knitting and wearing.

[0061] Figure 7 This is a test graph showing the bending stability of the fabric prepared in Example 2. The sample was attached to a finger, and after 1200 bending cycles, the fabric's resistance remained stable.

[0062] Comparative Example 1

[0063] The difference from Example 2 lies in the preparation of the spinning solution in step (3): MXene dispersion and polyvinyl alcohol solution are mixed at a ratio of 1:9 (solid content), and stirred at room temperature for 2 hours until the solution is homogeneous to obtain PVA / MXene composite spinning solution. The solid content of MXene is 10%.

[0064] Comparative Example 2

[0065] The difference from Example 2 lies in the preparation of the spinning solution in step (3): MXene dispersion and polyvinyl alcohol solution are mixed in a ratio of 2:8 (solid content), and stirred at room temperature for 1-2 hours until the solution is homogeneous to obtain PVA / MXene composite spinning solution. The solid content of MXene is 20%.

[0066] Comparative Example 3

[0067] The difference from Example 2 lies in the preparation of the spinning solution in step (3): MXene dispersion and polyvinyl alcohol solution are mixed in a ratio of 3:7 (solid content), and stirred at room temperature for 2 hours until the solution is homogeneous to obtain PVA / MXene composite spinning solution. The solid content of MXene is 30%.

[0068] Comparative Example 4

[0069] The difference from Example 2 lies in the preparation of the spinning solution in step (3): MXene dispersion and polyvinyl alcohol solution are mixed in a ratio of 4:6 (solid content), and stirred at room temperature for 2 hours until the solution is homogeneous to obtain PVA / MXene composite spinning solution. The solid content of MXene is 40%.

[0070] The electromagnetic shielding effectiveness of the X-band textiles prepared in Example 1, Comparative Example 1, and Comparative Example 4 was measured using an Agilent Technologies E8363A electromagnetic vector network analyzer, as shown below. Figure 8 As shown, the results indicate that the electromagnetic shielding effectiveness of the electromagnetic shielding fabric with a 50 wt.% MXene content can reach 60 dB, demonstrating good electromagnetic wave shielding performance.

[0071] Figure 9 The electromagnetic shielding performance and resistance changes of the PVA / MXene smart electronic fabrics prepared in Examples 1 and 2 of this invention are shown in the graphs at 95% RH and 65°C. The results indicate that chemical crosslinking improves the antioxidant properties of the electromagnetic shielding fabric.

[0072] The shielding performance of the electromagnetic shielding fabric prepared in Example 2 was tested at different angles, as follows: Figure 10The results showed that the shielding performance could be tuned within the range of 8-58 dB by changing the rotation angle of the textile, demonstrating its potential as a shielding switch.

[0073] The shielding performance of the electromagnetic shielding fabric prepared in Example 2 under wet / light cycling was tested, such as... Figure 11 As shown in the figure. The results indicate that through repeated water absorption and desorption, the electromagnetic shielding fabric exhibits intelligent EMI shielding behavior in an "on / off" state.

[0074] The above demonstrates the multimodal driving behavior of electromagnetic shielding fabrics.

[0075] Infrared imaging of the electromagnetic shielding fabric prepared in Example 2 adhered to human skin under illumination (simulated by a xenon lamp) was tested. Figure 12 As shown, the results indicate that textiles can reach controllable thermotherapy temperatures under light irradiation and can be used for wearable thermotherapy.

[0076] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method of preparing a MXene-based fiber, characterized by: The method comprises the following steps: polyvinyl alcohol and MXene solution are mixed in proportion to obtain a spinning solution, the spinning solution is injected into a calcium ion coagulation bath for solidification, and the obtained fiber is washed with water and dried to obtain a dry fiber; The mass percentage of polyvinyl alcohol is 10-13 wt%; the mass concentration of MXene is 30-35 mg / mL; In the spinning solution, the mass ratio of polyvinyl alcohol to MXene is 1:1; The injection condition is that the injection speed of the syringe is 100 mL / h, the needle type is 19G, and the inner diameter is 0.72 mm; in the calcium ion coagulation bath, the concentration of calcium ions is 5-8 wt%; The polymerizable isocyanate, acetonitrile and methyl caproate are mixed in proportion to obtain a crosslinking agent; The obtained dry fiber is immersed in the crosslinking agent, and a crosslinking reaction is carried out at 60-80℃ for 50-90 min, then the fiber is washed and dried to obtain a MXene-based fiber; The fabric knitted by the MXene-based fiber prepared by the method can realize shielding performance in the range of 8-58 dB by changing the rotation angle of the textile.

2. The method of claim 1, wherein: In the crosslinking agent, the volume percentage of PMDI is 5%-15%.

3. The method of claim 2, wherein: In the crosslinking agent, the volume ratio of acetonitrile to methyl caproate is 3-5:

1.

4. The method of claim 3, wherein: After the crosslinking reaction is completed, the fiber surface is cleaned with acetone.

5. A MXene-based fiber, characterized by: Prepared by the preparation method of any one of claims 1-4.

6. Use of the MXene-based fiber of claim 5 in the preparation of electronic skin, health monitors, wearable electromagnetic interference shielding fabrics, wearable thermal therapy fabrics or supercapacitors.

7. An electromagnetic shielding fabric, characterized by: Knitted from the MXene-based fiber of claim 5.

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