Preparation method of anti-electromagnetic interference material, anti-electromagnetic interference material and application of anti-electromagnetic interference material

Abstract

The embodiment of the invention relates to the technical field of anti-electromagnetic interference materials, in particular to a preparation method of an anti-electromagnetic interference material and the anti-electromagnetic interference material. According to the embodiment of the invention, the anti-electromagnetic interference material with the gallium-based liquid metal content gradually changing in one direction can be prepared. In the process that electromagnetic waves reach the end, with the high gallium-based liquid metal content, of the anti-electromagnetic interference material from the end, with the low gallium-based liquid metal content, of the anti-electromagnetic interference material, the electromagnetic waves are lost through MXene, and when the electromagnetic waves reach the end, with the high gallium-based liquid metal content, of the anti-electromagnetic interference material, the electromagnetic waves are lost through MXene. The gallium-based liquid metal gathered at one end with higher content of the gallium-based liquid metal particles of the aerogel anti-electromagnetic interference material is reflected back to the anti-electromagnetic interference material, and then the MXene loses the electromagnetic wave, so that the purpose of absorbing, reflecting and reabsorbing the electromagnetic wave is achieved; the anti-electromagnetic interference material has good electromagnetic shielding performance and wave absorbing performance at the same time.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of anti-electromagnetic interference materials, and in particular, to a method for preparing an anti-electromagnetic interference material, an anti-electromagnetic interference material and applications thereof. Background Art

[0002] With the rapid development of electronic information technology, electromagnetic waves have been widely used in various fields, but they have also produced many negative effects. Electromagnetic waves in the environment can cause electromagnetic pollution and interfere with the normal operation of the electromagnetic system of the equipment. The electromagnetic wave radiation of the digital transmission system can cause information leakage. At the same time, electromagnetic radiation may also have direct or indirect adverse effects on human health.

[0003] Anti-electromagnetic interference materials are often used in electromagnetic protection. Anti-electromagnetic interference materials can absorb or reflect electromagnetic waves, so that the energy of electromagnetic waves is attenuated or the propagation path is blocked. Existing anti-electromagnetic interference materials are usually difficult to have good electromagnetic shielding performance and wave absorbing performance at the same time. Summary of the invention

[0004] The embodiments of the present application provide a method for preparing an anti-electromagnetic interference material, an anti-electromagnetic interference material and applications thereof, which can enable the anti-electromagnetic interference material to have both good electromagnetic shielding performance and wave absorbing performance.

[0005] In order to solve the above technical problems, the embodiments of the present application provide the following technical solutions:

[0006] In a first aspect of the present application, a method for preparing an anti-electromagnetic interference material is provided, the method comprising: placing a first dispersion in a mold, the first dispersion comprising biomass collagen fibers, polyvinyl alcohol, MXene, gallium-based liquid metal particles and water; allowing the first dispersion to stand in the mold for a preset time; and freeze-drying the first dispersion in the mold to obtain an aerogel anti-electromagnetic interference material.

[0007] In an embodiment of the present application, during the process of allowing the first dispersion to stand, the gallium-based liquid metal particles in the first dispersion gradually sink under the action of gravity, so that the concentration of the gallium-based liquid metal particles in the first dispersion gradually increases along the direction of gravity, showing a gradual change. After freeze-drying the first dispersion, the polyvinyl alcohol and biomass collagen fibers in the first dispersion undergo a cross-linking reaction to form an aerogel anti-electromagnetic interference material, and in the aerogel anti-electromagnetic interference material, the content of gallium-based liquid metal particles per unit volume remains gradually increasing along the direction of gravity. The porous structure of the aerogel anti-electromagnetic interference material can effectively reduce its impedance mismatch and reduce the reflection of electromagnetic waves. In the process of the electromagnetic wave reaching the end of the anti-electromagnetic interference material with a lower content of gallium-based liquid metal particles from the end of the anti-electromagnetic interference material with a higher content of gallium-based liquid metal particles, the electromagnetic wave is first lost by MXene. When the electromagnetic wave reaches the end of the aerogel anti-electromagnetic interference material with a higher content of gallium-based liquid metal particles, the gallium-based liquid metal gathered at the end of the aerogel anti-electromagnetic interference material with a higher content of gallium-based liquid metal particles is reflected back into the anti-electromagnetic interference material, and the electromagnetic wave is lost by MXene again, thereby achieving the purpose of "absorption → reflection → re-absorption" of the electromagnetic wave, so that the anti-electromagnetic interference material has both good electromagnetic shielding performance and wave absorbing performance.

[0008] In some embodiments, in the first dispersion, the mass ratio of the MXene to the gallium-based liquid metal particles ranges from (0.1:10) to (0.1:5).

[0009] In some embodiments, the mass ratio of the polyvinyl alcohol to the biomass collagen fibers ranges from (4:1) to (3:2).

[0010] In some embodiments, the preset time is 20 minutes to 40 minutes.

[0011] In some embodiments, the gallium-based liquid metal particles include gallium-based liquid metal particles with a particle size of micrometer scale and / or gallium-based liquid metal particles with a particle size of nanometer scale.

[0012] In some embodiments, before placing the first dispersion in the mold, the method further includes: preparing the first dispersion; preparing the first dispersion includes: dissolving polyvinyl alcohol and biomass collagen fibers in water to obtain a first mixed liquid; mixing MXene and gallium-based liquid metal with the first mixed liquid to obtain a second mixed liquid; and ultrasonically treating and mechanically stirring the second mixed liquid to obtain the first dispersion.

[0013] In some embodiments, the ultrasonic treatment is intermittent ultrasonic treatment.

[0014] In some embodiments, the freeze-drying temperature is -53°C to -43°C, and the freeze-drying time is 30h to 40h.

[0015] In the second aspect of the present application, an anti-electromagnetic interference material is also provided. The anti-electromagnetic interference material is prepared according to the method described in the first aspect.

[0016] In the third aspect of the present application, there is also provided an application of an anti-electromagnetic interference material prepared by the method described in the first aspect in the field of anti-electromagnetic interference.

[0017] It should be understood that the contents described in the summary of the invention are not intended to limit the key or important features of the present disclosure, nor are they intended to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments of the present invention. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0019] Figure 1 The present invention provides a flowchart of a method for preparing an anti-electromagnetic interference material according to an embodiment of the present invention. DETAILED DESCRIPTION

[0020] The principles and spirit of the present disclosure will be described below with reference to several exemplary embodiments shown in the accompanying drawings. It should be understood that the description of these specific embodiments is only to enable those skilled in the art to better understand and implement the present disclosure, and does not limit the scope of the present disclosure in any way. In the following description and claims, unless otherwise defined, all technical and scientific terms used herein have the meanings commonly understood by those of ordinary skill in the art.

[0021] As used herein, the term "including" and similar terms should be understood as open inclusion, i.e., "including but not limited to". The term "based on" should be understood as "based at least in part on". The term "one embodiment" or "the embodiment" should be understood as "at least one embodiment". The terms "first", "second", etc. may refer to different or the same objects, and are only used to distinguish the objects referred to, without implying a specific spatial order, temporal order, order of importance, etc. of the objects referred to.

[0022] For example, Figure 1 The present invention provides a process flow diagram of a method for preparing an anti-electromagnetic interference material. Figure 1 , the method comprises the following steps:

[0023] Step 11: placing a first dispersion in a mold, wherein the first dispersion includes biomass collagen fibers, polyvinyl alcohol, MXene, gallium-based liquid metal particles and water.

[0024] Step 12: leaving the first dispersion liquid in the mold for a preset time.

[0025] Step 13: freeze-dry the first dispersion in the mold to obtain an aerogel anti-electromagnetic interference material.

[0026] In an embodiment of the present application, a first dispersion is placed in a mold, the first dispersion is allowed to stand in the mold for a preset time, and then the first dispersion in the mold is freeze-dried to obtain an aerogel anti-electromagnetic interference material. The first dispersion specifically includes biomass collagen fibers, polyvinyl alcohol, Ti 3 C 2 T x , gallium-based liquid metal particles and water; wherein biomass collagen fibers and polyvinyl alcohol are dissolved in water, Ti 3 C 2 T x The gallium-based liquid metal particles are dispersed in water. The water in the first dispersion can be deionized water.

[0027] In the embodiments of the present application, MXene is a type of metal carbon / nitride with a two-dimensional layered structure, and its chemical formula is M n+1 X n T x , where (n = 1-3), M represents an early transition metal, such as Ti, Zr, V, Mo, etc.; X represents C or N elements, T x It is a surface group, usually -OH, -O, -F or -Cl. It is named MXene because it has a lamellar structure similar to graphene.

[0028] In some embodiments, MXene can be Ti 3 C 2 T x .Ti 3 C 2 T x It has high electrical conductivity, special morphological structure and adjustable surface functional groups, which can attenuate electromagnetic waves through conductive loss, multiple reflections, polarization loss and other methods. 3 C 2 T x Take this as an example to illustrate.

[0029] Gallium-based liquid metal is a type of liquid metal that combines the properties of metal and fluid. In some embodiments, the particle size of the gallium-based liquid metal particles can be micrometer-level or nanometer-level. When the particle size of the gallium-based liquid metal particles is nanometer-level, the aerogel anti-electromagnetic interference material has better wave absorption performance.

[0030] In some embodiments, the gallium-based liquid metal may include a gallium-indium-tin alloy. For example, in some embodiments of the present application, the mass fractions of gallium, indium, and tin in the gallium-indium-tin alloy are 62.5%, 25%, and 12.5%, respectively. In other embodiments, the gallium-based liquid metal may also include a gallium-indium eutectic. For example, the mass fractions of gallium and indium in the gallium-indium eutectic are 75% and 25%, respectively.

[0031] In some embodiments, during the process of allowing the first dispersion to stand, the gallium-based liquid metal particles in the first dispersion gradually sink under the action of gravity, so that the concentration of the gallium-based liquid metal particles in the first dispersion gradually increases along the direction of gravity, showing a gradual change. After the first dispersion is freeze-dried, the polyvinyl alcohol and biomass collagen fibers in the first dispersion undergo a cross-linking reaction to form an aerogel anti-electromagnetic interference material, and in the aerogel anti-electromagnetic interference material, the content of gallium-based liquid metal particles per unit volume is maintained to gradually increase along the direction of gravity. The porous structure of the aerogel anti-electromagnetic interference material is conducive to reducing its impedance mismatch and reducing the reflection of electromagnetic waves. In the process of the electromagnetic wave reaching the end of the anti-electromagnetic interference material with a lower content of gallium-based liquid metal particles from the end with a lower content of gallium-based liquid metal particles, Ti is first 3 C 2 T x The electromagnetic wave is lost. When the electromagnetic wave reaches the end of the aerogel anti-electromagnetic interference material with a higher content of gallium-based liquid metal particles, the gallium-based liquid metal particles gathered at the end of the aerogel anti-electromagnetic interference material with a higher content of gallium-based liquid metal particles are reflected into the anti-electromagnetic interference material and then transmitted by Ti again. 3 C 2 T x The electromagnetic wave is lost, thereby achieving the purpose of "absorbing → reflecting → reabsorbing" the electromagnetic wave.

[0032] In some embodiments, in order to make the anti-electromagnetic shielding material have good wave absorbing performance and electromagnetic shielding performance, in the first dispersion, Ti 3 C 2 T x The mass ratio of the gallium-based liquid metal particles ranges from (0.1:10) to (0.1:5).

[0033] In some embodiments, in order to further improve the wave absorption performance and electromagnetic shielding performance of the electromagnetic shielding material, the mass ratio of polyvinyl alcohol to biomass collagen fibers in the first dispersion is in the range of (4:1) to (3:2).

[0034] In some embodiments, the preset time may be any appropriate time. In some embodiments of the present application, in order to make the anti-electromagnetic shielding material have good wave absorbing performance and electromagnetic shielding performance at the same time, the preset time is 20 minutes to 40 minutes.

[0035] In some embodiments, before step 11, the method further includes: preparing a first dispersion liquid, and the method of preparing the first dispersion liquid specifically includes: dissolving polyvinyl alcohol and biomass collagen fibers in water to obtain a first mixed liquid; mixing MXene and gallium-based liquid metal with the first mixed liquid to obtain a second mixed liquid; and ultrasonically treating and mechanically stirring the second mixed liquid to obtain a first dispersion liquid.

[0036] Specifically, in some embodiments, polyvinyl alcohol and biomass collagen fibers are dissolved in water to obtain a first mixed solution, including: crushing the polyvinyl alcohol block with a grinder, screening out polyvinyl alcohol particles within 30 meshes with a mesh sieve, washing the polyvinyl alcohol particles with ultrapure water for 10h to 14h, and drying the polyvinyl alcohol particles at 40°C to 50°C to obtain polyvinyl alcohol powder. After mixing the polyvinyl alcohol powder, biomass collagen fiber dry powder and water, the mixture of polyvinyl alcohol powder, biomass collagen fiber dry powder and water is placed at 85°C to 95°C and stirred for 1.5h to 2.5h to obtain the first mixed solution.

[0037] Specifically, in some embodiments, the second mixed liquid is subjected to ultrasonic treatment and mechanical stirring, including: firstly subjecting the second mixed liquid to intermittent ultrasonic treatment, and then subjecting the second mixed liquid to mechanical stirring; the mechanical stirring time may be 25min to 35min. In some embodiments, the ultrasonic treatment is intermittent ultrasonic treatment, specifically, ultrasonic treatment may be performed for 2s to 4s at intervals of 0.5s to 1.5s. The power of the ultrasonic treatment is 350w to 450w, and the time of the ultrasonic treatment is 10min to 15min.

[0038] In the embodiment of the present application, the gallium-based liquid metal has high surface tension and density, and is easy to self-aggregate and quickly deposit. By subjecting the second mixture to ultrasonic treatment, the bulk gallium-based liquid metal in the second mixture can be made into micrometer and / or nanometer-scale particles, so as to reduce the deposition rate of the gallium-based liquid metal particles in the second mixture, and at the same time enhance the dispersibility of the gallium-based liquid metal particles in the second mixture.

[0039] In some embodiments, step 13 specifically includes: after the first dispersion is allowed to stand in a mold (such as a polytetrafluoroethylene mold) for a preset time, the mold is placed in liquid nitrogen to freeze-dry the first dispersion in the mold to obtain an aerogel anti-electromagnetic interference material, that is, an aerogel material with anti-electromagnetic interference function. Specifically, in some embodiments, the freeze-drying temperature is -53°C to -43°C, and the freeze-drying time is 30h to 40h. During the freeze-drying process, due to the temperature gradient in the first dispersion, ice crystals grow laterally, compressing the biomass collagen fibers, polyvinyl alcohol, and Ti 3 C 2 T x And gallium-based liquid metal particles form an aerogel anti-electromagnetic interference material with a horizontal asymmetric gradient structure.

[0040] The embodiments of the present application also provide an anti-electromagnetic interference material, which is prepared according to the method provided in the above embodiments.

[0041] The embodiments of the present application also provide an application of an anti-electromagnetic interference material prepared by the method provided in the above embodiments in the field of anti-electromagnetic interference.

[0042] Several embodiments of the present application are provided below.

[0043] Example 1

[0044] The preparation method of the anti-electromagnetic interference material comprises the following steps:

[0045] After the polyvinyl alcohol block was crushed with a grinder, polyvinyl alcohol particles within 30 mesh were screened out with a mesh sieve. The polyvinyl alcohol particles were washed with ultrapure water for 12 hours, and then dried at 45°C to obtain polyvinyl alcohol powder. 0.4g polyvinyl alcohol powder and 0.1g biomass collagen fiber powder were added to 10mL deionized water, and the mixture of polyvinyl alcohol powder, biomass collagen fiber powder and deionized water was stirred at 90°C for 2.5 hours to obtain a light yellow first mixed solution. Ti was added at a mass ratio of 0.1:5 3 C 2 T x and gallium-based liquid metal are added to the first mixed solution, and the first mixed solution is subjected to ultrasonic treatment, the power of the ultrasonic treatment is 400W, the time of the ultrasonic treatment is 12 minutes, and the ultrasonic treatment is paused for 1 second every 3 seconds. Then, the first mixed solution is mechanically stirred for 30 minutes to obtain a first dispersion;

[0046] The first dispersion was transferred to a customized polytetrafluoroethylene mold. After the first dispersion was allowed to stand in the polytetrafluoroethylene mold for 30 minutes, the polytetrafluoroethylene mold containing the first dispersion was placed in a freeze dryer and freeze-dried at -48°C and 10Pa for 36 hours to obtain an aerogel anti-electromagnetic interference material.

[0047] Example 2

[0048] The difference between Example 2 and Example 1 is that in the process of preparing the anti-electromagnetic interference material, the masses of the polyvinyl alcohol powder and the biomass collagen fiber dry powder are 0.3g and 0.2g respectively; 3 C 2 T x The mass ratio of gallium-based liquid metal is 0.1:10.

[0049] Comparative Example 1

[0050] The difference between the comparative example 1 and the embodiment 1 is that in the process of preparing the anti-electromagnetic interference material, only Ti is added to the first mixed solution. 3 C 2 T x , but no gallium-based liquid metal is added, that is, the first dispersion liquid of Comparative Example 1 does not include gallium-based liquid metal particles.

[0051] The anti-electromagnetic interference performance of the anti-electromagnetic interference materials provided in Example 1, Example 2 and Comparative Example 1 was tested respectively, and the test results are shown in Table 1:

[0052] Table 1

[0053] Electromagnetic shielding effectiveness (dB) Reflection coefficient Example 1 85.3 0.08 Example 2 71.5 0.09 Comparative Example 1 55.4 0.62

[0054] It can be seen from Table 1 that the electromagnetic shielding effectiveness of the anti-electromagnetic interference material provided in Example 1 reaches 85.3dB, and the reflection coefficient is only 0.08; the electromagnetic shielding effectiveness of the anti-electromagnetic interference material provided in Example 2 reaches 70.8dB, and the reflection coefficient is only 0.09. The electromagnetic shielding effectiveness of the anti-electromagnetic interference material provided in Comparative Example 1 can reach 55.4, but the reflection coefficient is 0.62; since the reflection coefficient of the anti-electromagnetic interference material provided in Comparative Example 1 is relatively large, it is easy to cause secondary electromagnetic radiation pollution. Compared with Comparative Example 1, the anti-electromagnetic interference materials of Examples 1 and 2 have higher electromagnetic shielding effectiveness and lower reflection coefficient, that is, the anti-electromagnetic interference materials of Examples 1 and 2 have more excellent electromagnetic shielding performance and more excellent wave absorbing performance.

[0055] The difference between Example 1 and Comparative Example 1 is that, in the process of preparing the anti-electromagnetic interference material, gallium-based liquid metal is added to the first dispersion of Example 1, while gallium-based liquid metal is not added to the first dispersion of Comparative Example 1. Example 1 and Example 2 can effectively improve the electromagnetic shielding effectiveness of the anti-electromagnetic interference material and reduce the reflection coefficient of the electromagnetic interference material by using gallium-based liquid metal.

[0056] In an embodiment of the present application, during the standing of the first dispersion, the gallium-based liquid metal particles in the first dispersion gradually sink under the action of gravity, so that the concentration of the gallium-based liquid metal particles in the first dispersion gradually increases along the direction of gravity, showing a gradual change. After the first dispersion is freeze-dried, the polyvinyl alcohol and biomass collagen fibers in the first dispersion undergo a cross-linking reaction to form an aerogel anti-electromagnetic interference material, and in the aerogel anti-electromagnetic interference material, the content of gallium-based liquid metal particles per unit volume is maintained to gradually increase along the direction of gravity. In the process of electromagnetic waves reaching the end of the anti-electromagnetic interference material where the gallium-based liquid metal particle content is lower, Ti is firstly 3 C 2 T x The electromagnetic wave is lost. When the electromagnetic wave reaches the end of the aerogel anti-electromagnetic interference material with a higher content of gallium-based liquid metal particles, the gallium-based liquid metal gathered at the end of the aerogel anti-electromagnetic interference material with a higher content of gallium-based liquid metal particles is reflected back to the anti-electromagnetic interference material and is again transmitted by Ti 3 C 2 T x The electromagnetic wave is lost, thereby achieving the purpose of "absorbing → reflecting → reabsorbing" the electromagnetic wave. Therefore, the preparation method of the anti-electromagnetic interference material provided in the embodiment of the present application can effectively improve the electromagnetic shielding effectiveness of the anti-electromagnetic interference material, reduce the reflection coefficient of the electromagnetic interference material, and make the anti-electromagnetic interference material have good electromagnetic shielding performance and wave absorbing performance at the same time.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may also be combined, the steps may be implemented in any order, and there are many other changes in different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they may still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an anti-electromagnetic interference material, characterized in that: The method comprises: placing a first dispersion in a mold, wherein the first dispersion includes biomass collagen fibers, polyvinyl alcohol, MXene, gallium-based liquid metal particles, and water; Allowing the first dispersion to stand in the mold for a preset time; The first dispersion in the mold is freeze-dried to obtain an aerogel anti-electromagnetic interference material.

2. The method according to claim 1, characterized in that In the first dispersion, the mass ratio of the MXene to the gallium-based liquid metal particles is in the range of (0.1:10) to (0.1:5).

3. The method according to claim 1, characterized in that The mass ratio of the polyvinyl alcohol to the biomass collagen fibers ranges from (4:1) to (3:2).

4. The method according to claim 1, characterized in that: The preset time is 20 minutes to 40 minutes.

5. The method according to claim 1, characterized in that The gallium-based liquid metal particles include gallium-based liquid metal particles with a particle size of micrometer scale and / or gallium-based liquid metal particles with a particle size of nanometer scale.

6. The method according to any one of claims 1 to 5, characterized in that: Before placing the first dispersion in the mold, the method further comprises: preparing the first dispersion; The preparation of the first dispersion comprises: Dissolving polyvinyl alcohol and biomass collagen fibers in water to obtain a first mixed solution; Mixing MXene, gallium-based liquid metal and the first mixed solution to obtain a second mixed solution; The second mixed liquid is subjected to ultrasonic treatment and mechanical stirring to obtain a first dispersed liquid.

7. The method according to claim 6, characterized in that The ultrasonic treatment is intermittent ultrasonic treatment.

8. The method according to claim 6, characterized in that: The freeze-drying temperature is -53°C to -43°C, and the freeze-drying time is 30h to 40h.

9. An anti-electromagnetic interference material, characterized in that: The anti-electromagnetic interference material is prepared according to the method according to any one of claims 1-8.

10. Use of an anti-electromagnetic interference material prepared by the method according to any one of claims 1 to 8 in the field of anti-electromagnetic interference.

Images