Intelligent electromagnetic shielding material with tunable electromagnetic shielding range and preparation method thereof

Abstract

The invention discloses an intelligent electromagnetic shielding material with a tunable electromagnetic shielding range and a preparation method thereof.The intelligent electromagnetic shielding material is prepared from N-isopropylacrylamide, MXene, a mixed solution of PEDOT: PSS, a cross-linking agent and an initiator, and the specific preparation method comprises the following steps that firstly, the mixed solution of MXene and the mixed solution of PEDOT: PSS are mixed, and a conductive filler mixed solution is obtained; 2, mixing the conductive filler mixed solution obtained in the step 1 with N-isopropylacrylamide, adding a cross-linking agent and an initiator, and pouring the mixture into a polytetrafluoroethylene mold; 3, polymerizing the mixed solution obtained in the step 2 by utilizing a directional freezing method to obtain composite conductive hydrogel with a directional pore channel structure; and 4, soaking the hydrogel obtained in the step 3 in deionized water, and removing redundant solvents and impurities. The intelligent electromagnetic shielding material disclosed by the invention can be used for rapidly regulating and controlling the electromagnetic shielding performance under illumination and thermal stimulation.

Description

Technical Field

[0001] The present invention belongs to the field of materials science, and relates to a preparation method of an electromagnetic shielding material, in particular to an intelligent electromagnetic shielding material capable of tuning the electromagnetic shielding range by means of photothermal and other means and a preparation method thereof. Background Art

[0002] In the face of a complex electromagnetic environment, high-performance EMI shielding structure materials with high EMI shielding effectiveness (SE), easy manufacturability, good mechanical strength and flexibility, flexibility and intelligence are required to meet the current needs. Compared with traditional electromagnetic shielding materials with fixed shielding performance, the new generation of intelligent electromagnetic shielding materials can sense and dynamically adjust their SE according to specific application requirements and environmental changes (pressure, pH value, temperature, etc.). However, the existing intelligent EMI shielding materials regulate the electromagnetic shielding performance of the materials through in-situ control. Therefore, developing intelligent electromagnetic shielding materials that can be remotely controlled and controllably adjusted is an important challenge that urgently needs to be solved, which is of great significance for broadening the application of intelligent EMI shielding materials in complex electromagnetic protection systems and future intelligent life. Summary of the Invention

[0003] In order to solve the above problems existing in the existing electromagnetic shielding materials, the present invention provides an intelligent electromagnetic shielding material with a tunable electromagnetic shielding range and a preparation method thereof. The intelligent electromagnetic shielding material can rapidly regulate the electromagnetic shielding performance under light and heat stimuli. Its system is mainly composed of PNIPAM (poly-N-isopropylacrylamide) and MXene / PEDOT (poly(ethylenedioxythiophene):PSS (polystyrenesulfonic acid)). Among them, a temperature-sensitive PNIPAM hydrogel is used as a matrix to form an intelligent hydrogel, and a photothermal conversion material MXene and a conductive polymer PEDOT:PSS are introduced into the PNIPAM hydrogel, so that the conductive fillers form a conductive network in the matrix, ensuring that the obtained material has excellent conductivity and photothermal conversion efficiency while having a temperature-responsive intelligent function. The introduction of the directional channels endows the composite hydrogel with excellent electromagnetic shielding performance and mechanical properties. In addition, it has a rapid reaction rate under light stimulation, improving the response rate of the intelligent electromagnetic shielding material, and laying an important foundation for the preparation of an intelligent adjustable electromagnetic shielding material that responds to multiple stimuli.

[0004] The object of the present invention is achieved by the following technical solutions:

[0005] An intelligent electromagnetic shielding material with a tunable electromagnetic shielding range, which is made from a mixed solution of N-isopropylacrylamide, MXene, PEDOT:PSS, a crosslinking agent and an initiator. Among them: the mass ratio of the mixed solution of MXene and PEDOT:PSS is 1-5:1, and the mass ratio of MXene and N-isopropylacrylamide is 1-5:100; the crosslinking agent is N,N'-methylenebisacrylamide and N,N,N',N'-tetramethylethylenediamine, and the initiator is ammonium persulfate; the mass ratio of N,N'-methylenebisacrylamide, N,N,N',N'-tetramethylethylenediamine, ammonium persulfate to N-isopropylacrylamide is 0.5-5:0.70-0.80:1.8-1.9:100; in the mixed solution of PEDOT:PSS, the mass ratio of PEDOT and PSS is 1:2.5-3.

[0006] A preparation method of an intelligent electromagnetic shielding material with a tunable electromagnetic shielding range, comprising the following steps:

[0007] Step 1: Mix the mixed solution of MXene and PEDOT:PSS to obtain a conductive filler mixed solution;

[0008] Step 2: Mix the conductive filler mixed solution obtained in Step 1 with N-isopropylacrylamide, add a crosslinking agent and an initiator, and pour it into a polytetrafluoroethylene mold;

[0009] Step 3: Using the method of directional freezing, polymerize the mixed solution obtained in Step 2 to obtain a composite conductive hydrogel with a directional pore structure. The specific method is: soak the mold filled with the mixed solution in liquid nitrogen for 10-40 min under the protection of inert gas, then keep it at -12 °C for 6-20 h, and finally polymerize it at room temperature for 5-24 h;

[0010] Step 4: Soak the hydrogel obtained in Step 3 in deionized water to remove excess solvents and impurities, and control the deionized water soaking time to be 12-24 h.

[0011] Compared with the prior art, the present invention has the following advantages:

[0012] 1. The present invention introduces two-dimensional nanosheet MXene into the composite hydrogel. The introduction of MXene can not only improve the electromagnetic shielding performance of the hydrogel, but also has excellent photothermal conversion efficiency.

[0013] 2. The present invention introduces a directional structure inside the hydrogel, which greatly improves the strength of the hydrogel. The strength of the hydrogel is increased by 6 times compared with that of the isotropic hydrogel, and at the same time, the hydrogel can quickly adjust the electromagnetic shielding parameters under photothermal stimulation.

[0014] 3. During the regulation process of the intelligent electromagnetic shielding material of the present invention, there is a wide adjustable range of electromagnetic shielding performance, realizing its reversible regulation between 15.5 and 59.3 dB.

[0015] 4. The preparation method of the present invention is simple and has a wide application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is the cross-sectional SEM image of the composite hydrogel obtained in Step 3 of Example 1;

[0017] Figure 2 is the adjustable range of the electromagnetic shielding parameters tested for the composite hydrogel obtained in Step 3 of Example 1. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings, but are not limited thereto. Any modification or equivalent replacement of the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention shall be covered by the protection scope of the present invention.

[0019] Example 1:

[0020] This example provides a preparation method of an intelligent electromagnetic shielding material with a tunable electromagnetic shielding range. The method includes the following steps:

[0021] Step 1. Mix the mixed solution of MXene and PEDOT:PSS to obtain a conductive filler mixed solution, wherein the mass ratio of the mixed solution of MXene and PEDOT:PSS is 2:1, and the mass ratio of PEDOT and PSS is 1:2.5.

[0022] Step 2. Mix the conductive filler mixed solution obtained in Step 1 with N-isopropylacrylamide, add a cross-linking agent (N,N'-methylenebisacrylamide and N,N,N',N'-tetramethylethylenediamine) and an initiator (ammonium persulfate), and then pour it into a polytetrafluoroethylene mold. Among them, the mass ratio of MXene to N-isopropylacrylamide is 5:100, and the mass ratio of N,N'-methylenebisacrylamide, N,N,N',N'-tetramethylethylenediamine, ammonium persulfate to N-isopropylacrylamide is 2:0.72:1.85:100.

[0023] Step 3. Keep the mold filled with the solution in an argon atmosphere, soak it in liquid nitrogen for 40 min, then keep it at -12 °C for 14 h, and finally polymerize it at room temperature for 18 h to obtain a composite conductive hydrogel with an oriented pore structure.

[0024] Step 4. Soak the hydrogel obtained in Step 3 in deionized water for 12 h to remove excess solvents and impurities, and test its electromagnetic shielding performance.

[0025] Figure 1 is the cross-sectional scanning electron microscope image of the hydrogel actuator obtained in the second step of this embodiment. It can be seen from Figure 1 that the hydrogel actuator has an obvious directional structure; Figure 2 is the data graph of the adjustable range of the electromagnetic shielding parameters of the composite hydrogel tested in the third step of this embodiment. It can be found from Figure 2 that the composite hydrogel can be reversibly regulated between 15.5 and 59.3 dB.

[0026] Example 2:

[0027] This embodiment provides a preparation method of an intelligent electromagnetic shielding material with a tunable electromagnetic shielding range. The method includes the following steps:

[0028] Step 1: Mix the mixed solution of MXene and PEDOT:PSS to obtain a conductive filler mixed solution. Among them, the mass ratio of the mixed solution of MXene and PEDOT:PSS is 3:1, and the mass ratio of PEDOT and PSS is 1:3.

[0029] Step 2: Mix the conductive filler mixed solution obtained in Step 1 with N-isopropylacrylamide. After adding a cross-linking agent (N,N'-methylenebisacrylamide and N,N,N',N'-tetramethylethylenediamine) and an initiator (ammonium persulfate), pour it into a polytetrafluoroethylene mold. Among them, the mass ratio of MXene and N-isopropylacrylamide is 4:100, and the mass ratio of N,N'-methylenebisacrylamide, N,N,N',N'-tetramethylethylenediamine, ammonium persulfate to N-isopropylacrylamide is 3:0.75:1.83:100.

[0030] Step 3: Keep the mold filled with the solution in an argon atmosphere, soak it in liquid nitrogen for 40 min, then keep it at -12 °C for 16 h, and finally polymerize it at room temperature for 13 h to obtain a composite conductive hydrogel with a directional pore structure.

[0031] Step 4: Soak the hydrogel obtained in Step 3 in deionized water for 15 h to remove excess solvents and impurities.

[0032] Example 3:

[0033] This embodiment provides a preparation method of an intelligent electromagnetic shielding material with a tunable electromagnetic shielding range. The method includes the following steps:

[0034] Step 1: Mix the mixed solution of MXene and PEDOT:PSS to obtain a conductive filler mixed solution, where the mass ratio of the MXene and PEDOT:PSS mixed solution is 2:1, and the mass ratio of PEDOT and PSS is 1:2.5.

[0035] Step 2: Mix the conductive filler mixed solution obtained in Step 1 with N-isopropylacrylamide, add cross-linking agents (N,N'-methylenebisacrylamide and N,N,N',N'-tetramethylethylenediamine) and initiator (ammonium persulfate), and then pour it into a polytetrafluoroethylene mold. Among them, the mass ratio of MXene and N-isopropylacrylamide is 3:100, and the mass ratio of N,N'-methylenebisacrylamide, N,N,N',N'-tetramethylethylenediamine, ammonium persulfate to N-isopropylacrylamide is 3:0.76:1.85:100.

[0036] Step 3: Keep the mold containing the solution in an argon atmosphere, soak it in liquid nitrogen for 40 min, then keep it at -12 °C for 20 h, and polymerize it at room temperature for 15 h to obtain a composite conductive hydrogel with a directional pore structure.

[0037] Step 4: Soak the hydrogel obtained in Step 3 in deionized water for 18 h to remove excess solvents and impurities.

Claims

1. An intelligent electromagnetic shielding material with a tunable electromagnetic shielding range, characterized in that The intelligent electromagnetic shielding material is made of N-isopropylacrylamide, MXene, a mixed solution of PEDOT:PSS, a crosslinker and an initiator, wherein the mass ratio of the mixed solution of MXene and PEDOT:PSS is 1 to 5:1, and the mass ratio of MXene and N-isopropylacrylamide is 1 to 5:

100.

2. The intelligent electromagnetic shielding material with tunable electromagnetic shielding range according to claim 1, characterized in that The crosslinking agents are N,N'-methylenebisacrylamide and N,N,N',N'-tetramethylethylenediamine, and the initiator is ammonium persulfate.

3. The intelligent electromagnetic shielding material with tunable electromagnetic shielding range according to claim 2, characterized in that The mass ratio of the N,N'-methylenebisacrylamide, N,N,N',N'-tetramethylethylenediamine, ammonium persulfate and N-isopropylacrylamide is 0.5-5:0.70-0.80:1.8-1.9:

100.

4. The intelligent electromagnetic shielding material with tunable electromagnetic shielding range according to claim 1, characterized in that In the mixed solution of PEDOT:PSS, the mass ratio of PEDOT to PSS is 1:2.5-3.

5. A method for preparing the intelligent electromagnetic shielding material with a tunable electromagnetic shielding range according to any one of claims 1 to 4, characterized in that The method comprises the following steps: Step 1, mixing a mixed solution of MXene and PEDOT:PSS to obtain a conductive filler mixed solution; Step 2: Mix the conductive filler mixed solution obtained in step 1 with N-isopropylacrylamide, add a crosslinking agent and an initiator, and pour into a mold; Step 3: polymerizing the mixed solution obtained in step 2 by a directional freezing method to obtain a composite conductive hydrogel having a directional pore structure; Step 4: Soak the hydrogel obtained in step 3 in deionized water to remove excess solvent and impurities.

6. The method for preparing the intelligent electromagnetic shielding material with tunable electromagnetic shielding range according to claim 5, characterized in that The specific method of step three is: immerse the mold containing the mixed solution in liquid nitrogen for 10 to 40 minutes under the protection of inert gas, then keep it at -12°C for 6 to 20 hours, and finally polymerize it at room temperature for 5 to 24 hours.

7. The method for preparing the intelligent electromagnetic shielding material with tunable electromagnetic shielding range according to claim 5, characterized in that The deionization soaking time is 12 to 24 hours.

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