MXene / bacterial cellulose electromagnetic shielding porous membrane and preparation method and application thereof

Abstract

The application discloses MXene / bacterial cellulose electromagnetic shielding porous membranes and a preparation method and application thereof, and comprises the following steps: mixing Ti3C2T x Mxene and a bacterial cellulose dispersion solution to obtain a MXene / BC mixed solution; performing suction filtration on the MXene / BC mixed solution to obtain a MXene / BC gel block; and performing freezing and freeze-drying treatment on the MXene / BC gel block to obtain the MXene / bacterial cellulose electromagnetic shielding porous membrane; the MXene / bacterial cellulose electromagnetic shielding porous membrane prepared by the application has the characteristics of light weight, thinness, high conductivity and high electromagnetic wave absorption capacity compared with traditional electromagnetic shielding films and aerogels.

Description

Technical Field

[0001] This invention belongs to the field of electromagnetic shielding materials technology, and specifically relates to an MXene / bacterial cellulose electromagnetic shielding porous membrane, its preparation method, and its application. Background Technology

[0002] Electromagnetic shielding materials play a crucial role in modern electronic devices and communication systems. With the development of miniaturization, lightweighting, digitalization, and high-density integration of electronic components, requirements for electromagnetic shielding materials such as lightweight and flexibility have been put forward. In recent years, some new materials such as metal matrix composites, nanomaterials, graphene, electromagnetic shielding films, and electromagnetic shielding aerogels have also been used to prepare electromagnetic shielding materials to improve the shielding effect. The above materials have good shielding effect, transparency, and corrosion resistance, and therefore are increasingly widely used in electronic devices, communication equipment, and other fields.

[0003] Currently, most existing electromagnetic shielding films are composed of highly conductive materials. There is an impedance mismatch between their free space and the shielding body, which causes most electromagnetic waves to be reflected, easily causing secondary pollution. Secondly, electromagnetic shielding aerogels mainly rely on their long propagation path to absorb electromagnetic waves, so they have a large footprint and are relatively thick, which limits their application scenarios. Summary of the Invention

[0004] To address the technical problems existing in the prior art, this invention provides an MXene / bacterial cellulose electromagnetic shielding porous membrane, its preparation method, and its application. This solves the technical problems of impedance mismatch between the free space and the shielding body of existing electromagnetic shielding films, which leads to the reflection of most electromagnetic waves and easy secondary pollution, as well as the large footprint and thickness of electromagnetic shielding aerogels, which limit their application scenarios.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] This invention provides a method for preparing an MXene / bacterial cellulose electromagnetic shielding porous membrane, comprising:

[0007] Ti3C2T x Mxene was mixed with bacterial cellulose dispersion to obtain MXene / BC mixed solution;

[0008] The MXene / BC mixed solution was filtered to obtain MXene / BC gel blocks;

[0009] The MXene / BC gel block was subjected to freeze-drying treatment to obtain the MXene / bacterial cellulose electromagnetic shielding porous membrane.

[0010] Furthermore, the Ti3C2Tx The preparation process of Mxene is as follows:

[0011] Ti3C2 was obtained by etching Ti3AlC2 with hydrofluoric acid. x Mxene.

[0012] Furthermore, the preparation process of the bacterial cellulose dispersion is as follows:

[0013] The bacterial cellulose gel block was subjected to high-temperature impurity removal and shearing treatment to obtain a bacterial cellulose dispersion.

[0014] Furthermore, the Ti3C2T x The process of mixing Mxene with bacterial cellulose dispersion to obtain an MXene / BC mixed solution is as follows:

[0015] Ti3C2T x Mxene and bacterial cellulose dispersion were mixed in a mass ratio of (40-80):(20-60), and deionized water was added and stirred to obtain an MXene / BC mixed solution.

[0016] Further, the process of filtering the MXene / BC mixed solution to obtain MXene / BC gel blocks is as follows:

[0017] The MXene / BC mixed solution was filtered using a vacuum-assisted filtration method to obtain MXene / BC gel blocks.

[0018] Furthermore, the filtration of the MXene / BC mixed solution using vacuum-assisted filtration is stopped when there is no free water on the surface and a gel state is formed.

[0019] Furthermore, during the freezing process, the freezing temperature is -10 to 0°C, and the freezing time is 6 to 7 hours.

[0020] Furthermore, during the freeze-drying process, the freeze-drying temperature is -60 to -55°C, and the freeze-drying time is 10 to 12 hours.

[0021] The present invention also provides an MXene / bacterial cellulose electromagnetic shielding porous membrane, which is prepared using the aforementioned method for preparing an MXene / bacterial cellulose electromagnetic shielding porous membrane;

[0022] The conductivity of the MXene / bacterial cellulose electromagnetic shielding porous membrane is 1405–8834 mS·cm. -1 The density of the MXene / bacterial cellulose electromagnetic shielding porous membrane is 0.004–0.01528 mg·cm³.-1 At 8.2-12.4 GHz, the electromagnetic shielding effectiveness of the MXene / bacterial cellulose electromagnetic shielding porous membrane is 49.6-77.3 dB, and the electromagnetic shielding effectiveness per unit density (SEE / t) is 12287-19157 dB·cm. 2 ·g -1 .

[0023] The present invention also provides an application of the MXene / bacterial cellulose electromagnetic shielding porous membrane, characterized in that the MXene / bacterial cellulose electromagnetic shielding porous membrane is used as an electromagnetic shielding material.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] This invention provides an MXene / bacterial cellulose electromagnetic shielding porous membrane, its preparation method, and its application, using Ti3C2T x MXene and bacterial cellulose are mixed and filtered, then frozen and freeze-dried to obtain an MXene / bacterial cellulose electromagnetic shielding porous membrane. Compared with traditional electromagnetic shielding films and aerogels, it is lightweight, thin, highly conductive, and has a high ability to absorb electromagnetic waves. Specifically, MXene, with its two-dimensional structure, is used as the conductive substrate. MXene's high conductivity allows it to reflect most electromagnetic waves and provide a conductive path. Bacterial cellulose is used as the composite substrate to provide impedance matching, allowing the remaining electromagnetic waves to enter the interior of the porous membrane. Its three-dimensional network structure easily forms a gel during manufacturing, retaining some moisture, and forms pores after freeze-drying. Secondly, the conductivity of MXene and the pores formed by bacterial cellulose work synergistically to allow electromagnetic waves to undergo multiple reflections and scatterings within the material. After vacuum treatment... The vacuum-filtered and cold-dried porous membrane retains the thinness of traditional thin films while incorporating the porous structure of aerogels, combining the structural advantages of both. The prepared MXene / BC porous membrane has a highly porous structure, which increases the contact area between the material and electromagnetic waves, providing more opportunities for absorption and scattering, thereby achieving better electromagnetic shielding. Secondly, MXene, a two-dimensional material, has good electrical conductivity, better than traditional metal shielding materials, and features low density and easy processing. Bacterial cellulose has the advantages of flexibility and high strength, giving the MXene / BC porous membrane good plasticity and bendability, allowing for shape and size adjustments as needed, making it more convenient to apply the MXene / bacterial cellulose electromagnetic shielding porous membrane to electronic devices with different shapes and curved surfaces. Attached Figure Description

[0026] Figure 1This is a cross-sectional SEM image of the MXene / bacterial cellulose electromagnetic shielding porous membrane prepared in Example 3;

[0027] Figure 2 The electromagnetic shielding effectiveness of the MXene / bacterial cellulose electromagnetic shielding porous membrane prepared in Example 1 is shown in the frequency range of 8.2–12.4 GHz.

[0028] Figure 3 The electromagnetic shielding effectiveness of the MXene / bacterial cellulose electromagnetic shielding porous membrane prepared in Example 2 is shown in the frequency range of 8.2–12.4 GHz.

[0029] Figure 4 The electromagnetic shielding effectiveness of the MXene / bacterial cellulose electromagnetic shielding porous membrane prepared in Example 3 is shown in the frequency range of 8.2–12.4 GHz.

[0030] Figure 5 The electromagnetic shielding effectiveness of the MXene / bacterial cellulose electromagnetic shielding porous membrane prepared in Example 4 is shown in the frequency range of 8.2–12.4 GHz.

[0031] Figure 6 The electromagnetic shielding effectiveness of the MXene / bacterial cellulose electromagnetic shielding porous membrane prepared in Example 5 is shown in the frequency range of 8.2–12.4 GHz. Detailed Implementation

[0032] To make the technical problems solved by the present invention, the technical solutions, and the beneficial effects clearer, the following specific embodiments provide a further detailed description of the present invention. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of the invention.

[0033] This invention provides a method for preparing an MXene / bacterial cellulose electromagnetic shielding porous membrane, comprising the following steps:

[0034] Step 1: Etch Ti3AlC2 with hydrofluoric acid to obtain Ti3C2T x Mxene; high-temperature impurity removal and shearing treatment of bacterial cellulose (BC) gel blocks to obtain bacterial cellulose dispersion.

[0035] Specifically, the Ti3C2T x The preparation process of Mxene is as follows:

[0036] LiF was dissolved in hydrochloric acid solution, then Ti3AlC2 was added, stirred, and centrifuged, washed, and shaken until the solution turned dark green. The supernatant was collected and sonicated to obtain Ti3C2T. x Mxene.

[0037] Specifically, the preparation process of the bacterial cellulose dispersion is as follows:

[0038] The bacterial cellulose gel block was placed in deionized water and heated and stirred to remove impurities at high temperature, thus obtaining the removed bacterial cellulose gel block.

[0039] The purified bacterial cellulose was placed in deionized water and then sheared to obtain a bacterial cellulose dispersion.

[0040] Step 2, place Ti3C2T x Mxene and bacterial cellulose dispersion were mixed at a mass ratio of (40-80):(20-60), and deionized water was added and stirred to obtain an MXene / BC mixed solution.

[0041] Step 3: Use vacuum-assisted filtration to filter the MXene / BC mixed solution to obtain MXene / BC gel blocks; wherein, the filtration of the MXene / BC mixed solution using vacuum-assisted filtration is stopped when there is no free water on the surface and a gel state is formed.

[0042] Step 4: Place the MXene / BC gel block in a refrigerator for freezing treatment, and then place it in a freeze dryer for freeze drying to obtain the MXene / bacterial cellulose electromagnetic shielding porous membrane; wherein, when freezing the MXene / BC gel block, the freezing temperature is -10 to 0℃ and the freezing time is 6 to 7 hours; when freeze drying, the freeze drying temperature is -60 to -55℃ and the freeze drying time is 10 to 12 hours.

[0043] Preparation principle:

[0044] The method for preparing the MXene / bacterial cellulose electromagnetic shielding porous membrane of the present invention involves the formation of hydrogen bonds between MXene nanosheets and BC during the filtration process, allowing the mechanically weak MXene to be supported by BC. The ultra-fine three-dimensional network structure of BC endows the MXene / BC composite material with a gel-like state, retaining some moisture in the composite material. After cold drying, the moisture is removed, forming a porous structure inside the material, thus obtaining the MXene / BC porous membrane.

[0045] MXene, a new member of the 2D materials family, possesses a highly conductive layered structure that provides excellent electron conduction channels for effectively absorbing and scattering electromagnetic waves. These advantages make MXene an excellent electromagnetic shielding material. Bacterial cellulose itself possesses advantages such as high crystallinity, biocompatibility, high water retention, biodegradability, and non-toxicity. Its excellent three-dimensional network structure endows it with very good mechanical properties, and its abundant functional groups and unique structure make it easy to modify and surface-modify, making it suitable as a matrix for composite materials.

[0046] The MXene / bacterial cellulose electromagnetic shielding porous membrane of the present invention is lightweight, thin, highly conductive, and has a high electromagnetic wave absorption capability; specifically, the conductivity of the MXene / bacterial cellulose electromagnetic shielding porous membrane is 1405–8834 mS·cm. -1 The density of the MXene / bacterial cellulose electromagnetic shielding porous membrane is 0.004–0.01528 mg·cm³. -1 At 8.2-12.4 GHz, the electromagnetic shielding effectiveness of the MXene / bacterial cellulose electromagnetic shielding porous membrane is 49.6-77.3 dB, and the electromagnetic shielding effectiveness per unit density (SEE / t) is 12287-19157 dB·cm. 2 ·g -1 .

[0047] Example 1

[0048] This embodiment 1 provides a method for preparing an MXene / bacterial cellulose electromagnetic shielding porous membrane, including the following steps:

[0049] Step 1: Etch Ti3AlC2 with hydrofluoric acid (HF) to obtain Ti3C2T x MXene was used to remove impurities from bacterial cellulose (BC) gel blocks at high temperature and shearing to obtain a BC dispersion.

[0050] Specifically, the Ti3C2T x The preparation process of Mxene is as follows:

[0051] 1.6 g of LiF was dissolved in 20 ml of 9 mol / L hydrochloric acid solution, followed by the addition of 1 g of Ti3AlC2. The mixture was stirred continuously at 35 °C for 24 h. After centrifugation, washing, and shaking until the solution turned dark green, the supernatant was collected and sonicated for 30 min to obtain the Ti3C2T. x Mxene.

[0052] Specifically, the preparation process of the BC dispersion is as follows:

[0053] Weigh 1g of BC gel block with an oven-dry weight and place it in 500ml of deionized water. Stir at 100℃ for 1h to obtain a BC gel block after impurity removal. Then, the BC gel block after impurity removal is subjected to high-speed shearing to obtain a BC dispersion. The rotation speed during high-speed shearing is 1000r / min and the shearing time is 5-10min.

[0054] Step 2, the Ti3C2T prepared in Step 1 x Mxene and bacterial cellulose dispersion were mixed at a mass ratio of 40:60, deionized water was added, and the mixture was stirred to obtain a 150 mL MXene / BC mixed solution.

[0055] Step 3: The MXene / BC mixed solution prepared in Step 2 is filtered using a vacuum-assisted filtration method. When there is no free water on the surface and a gel is formed, the filtration is stopped to obtain the MXene / BC gel block.

[0056] Step 4: Place the MXene / BC gel block prepared in Step 3 into a refrigerator and freeze it at -10 to 0°C for 6 to 7 hours. Then, place it in a freeze dryer and treat it at -60 to -55°C for 10 to 12 hours to obtain the MXene / bacterial cellulose electromagnetic shielding porous membrane.

[0057] Example 2

[0058] The method for preparing an MXene / bacterial cellulose electromagnetic shielding porous membrane provided in Example 2 is basically the same as the method for preparing an MXene / bacterial cellulose electromagnetic shielding porous membrane described in Example 1 above, except that:

[0059] In step 2, Ti3C2T x Mxene and bacterial cellulose dispersion are mixed at a mass ratio of 50:50; the remaining steps are basically the same and will not be described in detail here.

[0060] Example 3

[0061] The method for preparing an MXene / bacterial cellulose electromagnetic shielding porous membrane provided in Example 3 is basically the same as the method for preparing an MXene / bacterial cellulose electromagnetic shielding porous membrane described in Example 1 above, except that:

[0062] In step 2, Ti3C2T x Mxene and bacterial cellulose dispersion are mixed at a mass ratio of 60:40; the remaining steps are basically the same and will not be described in detail here.

[0063] As attached Figure 1 As shown, attached Figure 1 The attached image shows a cross-sectional SEM image of the MXene / bacterial cellulose electromagnetic shielding porous membrane prepared in Example 3; from the attached image... Figure 1 As can be seen, the cross-section of the MXene / BC porous membrane contains many pores. These pores allow most electromagnetic waves to be reflected and absorbed multiple times inside, thus avoiding secondary pollution of electromagnetic waves.

[0064] Example 4

[0065] The method for preparing an MXene / bacterial cellulose electromagnetic shielding porous membrane provided in Example 4 is basically the same as the method for preparing an MXene / bacterial cellulose electromagnetic shielding porous membrane described in Example 1 above, except that:

[0066] In step 2, Ti3C2T x Mxene and bacterial cellulose dispersion are mixed at a mass ratio of 70:30; the remaining steps are basically the same and will not be described in detail here.

[0067] Example 5

[0068] The method for preparing an MXene / bacterial cellulose electromagnetic shielding porous membrane provided in Example 5 is basically the same as the method for preparing an MXene / bacterial cellulose electromagnetic shielding porous membrane described in Example 1 above, except that:

[0069] In step 2, Ti3C2T x Mxene and bacterial cellulose dispersion are mixed at a mass ratio of 80:20; the remaining steps are basically the same and will not be described in detail here.

[0070] As attached Figure 2-6 As shown, attached Figure 2 The figure shows the electromagnetic shielding effectiveness of the MXene / bacterial cellulose electromagnetic shielding porous membrane prepared in Example 1 at frequencies of 8.2–12.4 GHz. Figure 2 The total electromagnetic shielding effectiveness can be obtained as 49.6dB, which meets the commercial requirement of more than 30dB; among which, the average absorption loss is 38.4dB and the average reflection loss is 11.2dB.

[0071] Appendix Figure 3 The figure shows the electromagnetic shielding effectiveness of the MXene / bacterial cellulose electromagnetic shielding porous membrane prepared in Example 2 at frequencies of 8.2–12.4 GHz. Figure 3The total electromagnetic shielding effectiveness can be obtained as 58.1dB, which meets the commercial requirement of more than 30dB; among which, the average absorption loss is 45.2dB and the average reflection loss is 12.9dB.

[0072] Appendix Figure 4 The figure shows the electromagnetic shielding effectiveness of the MXene / bacterial cellulose electromagnetic shielding porous membrane prepared in Example 3 at frequencies of 8.2–12.4 GHz. Figure 4 The total electromagnetic shielding effectiveness can be obtained as 64.2dB, which meets the commercial requirement of more than 30dB; among which, the average absorption loss is 52.2dB and the average reflection loss is 12.0dB.

[0073] Appendix Figure 5 The figure shows the electromagnetic shielding effectiveness of the MXene / bacterial cellulose electromagnetic shielding porous membrane prepared in Example 4 at frequencies of 8.2–12.4 GHz. Figure 5 The total electromagnetic shielding effectiveness can be obtained as 70.1dB, which meets the commercial requirement of more than 30dB; among which, the average absorption loss is 59.0dB and the average reflection loss is 11.1dB.

[0074] Appendix Figure 6 The figure shows the electromagnetic shielding effectiveness of the MXene / bacterial cellulose electromagnetic shielding porous membrane prepared in Example 5 at frequencies of 8.2–12.4 GHz. Figure 6 The total electromagnetic shielding effectiveness can be obtained as 77.3dB, which meets the commercial requirement of more than 30dB; among which, the average absorption loss is 65.2dB and the average reflection loss is 12.1dB.

[0075] From the appendix Figure 2-6 As can be seen, with the increase of MXene content, the electromagnetic shielding effectiveness of the porous membrane is significantly improved, and its reflection effectiveness is maintained at around 10dB, which shows that the MXene / bacterial cellulose electromagnetic shielding porous membrane plays a certain role in the absorption of electromagnetic waves.

[0076] It should be noted that, after measuring the conductivity and density of the MXene / bacterial cellulose electromagnetic shielding porous membranes prepared in Examples 1-5 above, it was found that the conductivity of the MXene / bacterial cellulose electromagnetic shielding porous membranes was 1405–8834 mS·cm. -1 The density of the MXene / bacterial cellulose electromagnetic shielding porous membrane is 0.004–0.01528 mg·cm³. -1 Therefore, the MXene / bacterial cellulose electromagnetic shielding porous membrane of the present invention has the characteristics of being lightweight, thin, and highly conductive compared with traditional electromagnetic shielding films and aerogels.

[0077] The above embodiments are merely one of the implementation methods for achieving the technical solution of the present invention. The scope of protection claimed by the present invention is not limited to this embodiment, but also includes any variations, substitutions and other implementation methods that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention.

Claims

1. A method for preparing an MXene / bacterial cellulose electromagnetic shielding porous membrane, characterized in that, The method comprises the steps of: Ti3C2T x The Mxene is mixed with the bacterial cellulose dispersion solution to obtain a MXene / BC mixed solution. The MXene / BC mixed solution is subjected to suction filtration to obtain a MXene / BC gel block; specifically, the MXene / BC mixed solution is subjected to suction filtration by using a vacuum-assisted filtration method, and the MXene / BC gel block is obtained; the end criterion for the suction filtration of the MXene / BC mixed solution by using the vacuum-assisted filtration method is that the suction filtration is stopped when there is no free water on the surface and a gel state is formed; The MXene / BC gel block is subjected to freezing and freeze-drying treatment to obtain the MXene / bacterial cellulose electromagnetic shielding porous membrane; wherein, during the freezing treatment, the freezing temperature is-10-0 ℃, and the freezing time is 6-7 h; during the freeze-drying treatment, the freeze-drying temperature is-60--55 ℃, and the freeze-drying time is 10-12 h.

2. The method of claim 1, wherein the MXene / bacterial cellulose electromagnetic shielding porous membrane is prepared by the steps of: The Ti3C2T x The preparation process of Mxene is as follows: Ti3C2T is obtained by etching Ti3AlC2 with hydrofluoric acid x Mxene.

3. The method of claim 1, wherein the MXene / bacterial cellulose electromagnetic shielding porous membrane is prepared by the steps of: The preparation process of the bacterial cellulose dispersion liquid is specifically as follows: The bacterial cellulose gel block is subjected to high-temperature impurity removal and shearing treatment to obtain the bacterial cellulose dispersion liquid.

4. The method of claim 1, wherein the MXene / bacterial cellulose electromagnetic shielding porous membrane is prepared by the steps of: Ti3C2T x The process of mixing the Mxene with the bacterial cellulose dispersion solution to obtain the MXene / BC mixed solution is as follows: Ti3C2T x The Mxene and the bacterial cellulose dispersion solution were mixed in a mass ratio of (40-80):(20-60), and deionized water was added and stirred to obtain a MXene / BC mixed solution.

5. An MXene / bacterial cellulose electromagnetic shielding porous membrane, characterized in that, The MXene / bacterial cellulose electromagnetic shielding porous membrane is prepared by using the preparation method of the MXene / bacterial cellulose electromagnetic shielding porous membrane according to any one of claims 1-4. The MXene / bacterial cellulose electromagnetic shielding porous membrane has an electrical conductivity of 1405-8834 mS·cm -1 ; a density of 0.004-0.01528 mg·cm -1 ; an electromagnetic shielding effectiveness of 49.6-77.3 dB under 8.2-12.4 GHz, and an electromagnetic shielding effectiveness per unit density (SEE / t) of 12287-19157 dB·cm 2 ·g -1 .

6. Use of a MXene / bacterial cellulose electromagnetic shielding porous membrane according to claim 5, characterized in that, The MXene / bacterial cellulose electromagnetic shielding porous membrane is applied as an electromagnetic shielding material.

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