Absorbing loss type electromagnetic shielding material based on conductive nanofiber and preparation method thereof

Abstract

The application discloses an absorption loss type electromagnetic shielding material based on conductive nanofibers and a preparation method thereof, and adopts an in-situ polymerization method to prepare a polyaniline / MXene composite material with good conductivity, then introduces the composite material into an aqueous solution of polyethylene glycol and polyvinyl alcohol to obtain a conductive mixed solution, then prepares conductive nanofibers through electrospinning, and finally obtains the absorption loss type electromagnetic shielding composite material based on the conductive nanofibers through crosslinking of the obtained conductive nanofibers. The material obtained by the application not only has very good structural stability, but also has good electromagnetic shielding performance, and the average shielding efficiency in the X wave band is 28 dB, wherein the absorption loss is 24 dB, and excellent electromagnetic shielding and absorption performance is exhibited. The good conductivity of the obtained nanofibers promotes dielectric loss of electromagnetic waves, and the large specific surface area and rich pore structure of the nanofibers provide a favorable place for multiple reflection loss and absorption loss of electromagnetic waves in the material, so that the conductive nanofibers obtained by the application exhibit good electromagnetic shielding performance, and have a good application prospect in the electromagnetic protection field.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electromagnetic shielding composite materials, and relates to an absorption loss type electromagnetic shielding material based on conductive fibers and a preparation method thereof. BACKGROUND

[0002] Electrospinning is a technology for preparing polymer fibers and composite fibers, has the characteristics of strong operability and simple flexibility, and has a good application prospect in the field of electromagnetic shielding. Electrospinning can directly prepare continuous fibers in the form of non-woven fabric from polymers or composite materials through a solution spinning method, which plays an important role in the absorption and attenuation of electromagnetic waves. Polyvinyl alcohol is a white solid powder polymer material with a large number of hydroxyl groups in the molecular chain, has good water solubility, and has good spinnability and film-forming property, and has great potential in the electrospinning process.

[0003] Generally speaking, electromagnetic shielding materials need to have good electrical conductivity, and most polymer materials have poor electrical conductivity, which is not conducive to electromagnetic shielding. At present, filling conductive materials in polymer materials is an effective method for preparing conductive composite materials. MXene is a layered metal carbide and metal nitride material, which has good electrical conductivity. Polyaniline is a conductive polymer material that has the conductivity of metal and the processability of plastic, and also has the chemical and electrochemical properties that metal and plastic lack, and has good application value in the field of electromagnetic shielding. Combining MXene with polyaniline to obtain a composite material with good electrical conductivity, and then introducing it into polyvinyl alcohol to prepare conductive nanofibers for electromagnetic shielding by electrospinning has not been reported. SUMMARY

[0004] The application relates to an absorption loss type electromagnetic shielding material based on conductive nanofibers and a preparation method thereof, and first obtains a MXene / polyaniline composite material with good electrical conductivity, then introduces the composite material into an aqueous solution of polyvinyl alcohol and polyethylene glycol to prepare a conductive mixed solution, then electrospins the mixed solution to prepare continuous conductive nanofibers, and finally fixes the nanofibers through a cross-linking reaction to obtain an absorption loss type shielding material with good electromagnetic shielding performance.

[0005] The application is implemented by the following technical scheme.

[0006] The application provides an absorption loss type electromagnetic shielding material based on conductive nanofibers and a preparation method thereof, which comprises the following processes: surface modification of polyaniline on MXene, introduction of a polyaniline / MXene composite into an aqueous solution of polyvinyl alcohol to prepare conductive nanofibers by electrospinning, and cross-linking of the obtained nanofibers by using glutaraldehyde to obtain an absorption loss type electromagnetic shielding material.

[0007] The application relates to an absorbing loss type electromagnetic shielding material based on conductive nanofibers and a preparation method thereof, and specifically comprises the following steps:

[0008] (1) 10-15 g of LiF is added into 50 mL of HCl solution with a concentration of 1 mol / L, mechanical stirring is carried out for 5-15 min, then a MAX phase is slowly added, reaction is carried out at 30-40 DEG C for 24 h, and then MXene powder is obtained through centrifugation, washing and drying;

[0009] (2) 20 mL of aniline monomer and 5-10 g of MXene solid powder obtained in the step (1) are dispersed in 50-100 mL of protonic acid with a concentration of 1 mol / L to prepare a MXene solution, then 20-50 g of ammonium persulfate is added into the mixed solution, magnetic stirring is carried out under the condition of 0 DEG C ice bath for 4-6 h, then the obtained product is filtered, washed and dried to obtain a polyaniline / MXene composite;

[0010] (3) The polyaniline / MXene composite, polyvinyl alcohol and polyethylene glycol obtained in the step (2) are dispersed in deionized water, mixing is carried out at a stirring speed of 200 r / min under the condition of 70-90 DEG C until the polyaniline / MXene composite is uniformly dispersed and the polyvinyl alcohol and the polyethylene glycol are completely dissolved to obtain a mixed solution, and the solid content of the polyaniline / MXene composite in the polyvinyl alcohol solution is 10%-15%;

[0011] (4) The mixed solution obtained in the step (3) is injected into a syringe with a volume of 10 mL and a needle diameter of 0.8 mm, and air bubbles are discharged, the syringe is fixed on a micro-injection pump, the needle is used as a positive electrode, and an aluminum foil is used as a negative electrode, the solution is pushed into the needle through the metering pump, nanofibers are prepared at a spinning voltage of 10-20 kV, and the nanofibers are collected on a roller fixed at a distance of 10-15 cm from the needle through the aluminum foil;

[0012] (5) The nanofibers obtained in the step (4) are dried, and then are placed in 50% glutaraldehyde solution steam with trifluoroacetic acid as a catalyst to carry out a crosslinking reaction, and are dried at 60 DEG C for 10-12 h to obtain the absorbing loss type electromagnetic shielding material based on the conductive nanofibers.

[0013] Preferably, the MAX phase is one or more of Ti3AlC2, Ti2AlC or Ti3AlCN, and the particle size is less than or equal to 200 mesh.

[0014] Preferably, the protonic acid is hydrochloric acid, sulfuric acid, dodecylbenzenesulfonic acid and camphorsulfonic acid.

[0015] The conductive nanofiber obtained by the application has good electromagnetic shielding performance, and the average shielding efficiency in the X wave band is 28 dB, of which the absorption loss is 24 dB, showing absorption loss-based electromagnetic shielding performance, and having good application prospect in the field of electromagnetic protection.

[0016] The application has the following beneficial effects:

[0017] (1) The conductive nanofiber obtained by the application shows loss-based electromagnetic shielding, that is, most of the electromagnetic waves are absorbed inside the material when the electromagnetic waves pass through the composite material, greatly reducing the secondary electromagnetic pollution caused by the reflection of electromagnetic waves, and is an ideal electromagnetic shielding material. The polyaniline / MXene composite material is prepared by in-situ polymerization in the application, and polyaniline and MXene both have good conductivity to promote dielectric loss of electromagnetic waves. The layered loose structure of MXene is conducive to multiple reflection and absorption of electromagnetic waves inside the material. The large porosity and large specific surface area of the conductive nanofiber further promote the absorption and attenuation of electromagnetic waves, so that the conductive fiber obtained by the application exhibits absorption loss-based electromagnetic shielding.

[0018] (2) The conductive nanofiber obtained by the application has good structural stability and mechanical properties. After obtaining the conductive nanofiber, the obtained nanofiber is crosslinked by glutaraldehyde vapor in the application, so as to prevent aggregation and sliding between the fibers and obtain a composite material with stable structure. The application uses polyvinyl alcohol and polyethylene glycol with good flexibility and mechanical strength as the matrix to prepare the conductive nanofiber, and the obtained composite material has good flexibility and mechanical properties. Tests show that the obtained material does not deform after being bent for many times and maintains good mechanical and electromagnetic shielding properties. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is the SEM picture of the conductive composite nanofiber prepared based on example 1. DETAILED DESCRIPTION

[0020] In order to have a clearer understanding of the technical features of the application, the technical solutions of the application will be described in detail below, but it cannot be understood as limiting the scope of implementation of the application.

[0021] Example 1

[0022] (1) 10 g of LiF was added to 50 mL of HCl solution with a concentration of 1 mol / L, mechanically stirred for 10 min, then 8 g of Ti3AlC2 was slowly added, reacted at 35℃ for 24 h, and then centrifuged, washed and dried to obtain MXene powder;

[0023] (2) 20 mL of aniline monomer and 5 g of MXene solid powder obtained in step (1) were dispersed in 50 mL of hydrochloric acid with a concentration of 1 mol / L to prepare a MXene solution, and then 20 g of ammonium persulfate was added to the mixed solution. After magnetic stirring at 0°C ice bath for 4 h, the product was filtered, washed and dried to obtain a polyaniline / MXene composite;

[0024] (3) 5 g of polyaniline / MXene composite obtained in step (2), 10 g of polyvinyl alcohol and 5 g of polyethylene glycol were dispersed in 150 mL of deionized water, and mixed at a stirring speed of 200 r / min at 85°C until the polyaniline / MXene composite was uniformly dispersed and the polyvinyl alcohol and polyethylene glycol were completely dissolved to obtain a mixed solution;

[0025] (4) The mixed solution obtained in step (3) was injected into a syringe with a volume of 10 mL and a needle diameter of 0.8 mm to remove air bubbles, and was fixed on a micro-injection pump. The needle was used as the positive electrode and aluminum foil as the negative electrode. The solution was pushed into the needle by the metering pump, and nanofibers were prepared at a spinning voltage of 15 kV, and the aluminum foil was fixed on the roller at a distance of 15 cm from the needle to collect the nanofibers;

[0026] (5) The nanofibers obtained in step (4) were dried and placed in a 50% glutaraldehyde solution vapor with trifluoroacetic acid as a catalyst to undergo crosslinking reaction and dried at 60°C for 10 h to obtain an absorption loss type electromagnetic shielding material based on conductive nanofibers.

[0027] As Figure 1 The SEM picture of the prepared absorption loss type electromagnetic shielding material based on conductive nanofibers, the obtained nanofibers are uniform in thickness, the conductive filler is well dispersed and has very large porosity, which is beneficial to the absorption and attenuation of electromagnetic waves.

[0028] Example 2

[0029] (1) 10 g of LiF was added to 50 mL of HCl solution with a concentration of 1 mol / L, and mechanically stirred for 10 min, then 8 g of Ti3AlC2 was slowly added, and reacted at 35°C for 24 h, then centrifuged, washed and dried to obtain MXene powder;

[0030] (2) 20 mL of aniline monomer and 5 g of MXene solid powder obtained in step (1) were dispersed in 50 mL of sulfuric acid with a concentration of 1 mol / L to prepare a MXene solution, and then 20 g of ammonium persulfate was added to the mixed solution. After magnetic stirring at 0°C ice bath for 4 h, the product was filtered, washed and dried to obtain a polyaniline / MXene composite;

[0031] (3) 5 g of the polyaniline / MXene composite obtained in step (2), 10 g of polyvinyl alcohol, and 5 g of polyethylene glycol were dispersed in 150 mL of deionized water, and mixed at 85°C at a stirring speed of 200 r / min until the polyaniline / MXene composite was uniformly dispersed and the polyvinyl alcohol and polyethylene glycol were completely dissolved to obtain a mixed solution;

[0032] (4) The mixed solution obtained in step (3) was injected into a syringe with a volume of 10 mL and a needle diameter of 0.8 mm, and air bubbles were discharged, and it was fixed on a microsyringe pump, with the needle as the positive electrode and aluminum foil as the negative electrode, the solution was pushed into the needle by the metering pump, and nanofibers were prepared at a spinning voltage of 15 kV, and an aluminum foil was used to fix a roller at a distance of 15 cm from the needle to collect the nanofibers;

[0033] (5) The nanofibers obtained in step (4) were dried and placed in a 50% glutaraldehyde solution vapor with trifluoroacetic acid as a catalyst to undergo cross-linking reaction and dried at 60°C for 10 h to obtain an absorption loss type electromagnetic shielding material based on conductive nanofibers.

[0034] Example 3

[0035] (1) 10 g of LiF was added to 50 mL of HCl solution with a concentration of 1 mol / L, mechanically stirred for 10 min, and then 8 g of Ti2AlC was slowly added, reacted at 35°C for 24 h, and then centrifuged, washed and dried to obtain MXene powder;

[0036] (2) 20 mL of aniline monomer and 5 g of MXene solid powder obtained in step (1) were dispersed in 50 mL of sulfuric acid with a concentration of 1 mol / L to prepare a MXene solution, then 20 g of ammonium persulfate was added to the mixed solution, and the reaction was carried out under the condition of 0°C ice bath and magnetic stirring for 4 h, then the product was filtered, washed and dried to obtain a polyaniline / MXene composite;

[0037] (3) 5 g of the polyaniline / MXene composite obtained in step (2), 10 g of polyvinyl alcohol, and 5 g of polyethylene glycol were dispersed in 150 mL of deionized water, and mixed at 85°C at a stirring speed of 200 r / min until the polyaniline / MXene composite was uniformly dispersed and the polyvinyl alcohol and polyethylene glycol were completely dissolved to obtain a mixed solution;

[0038] (4) The mixed solution obtained in step (3) was injected into a syringe with a volume of 10 mL and a needle diameter of 0.8 mm, and air bubbles were discharged, and it was fixed on a microsyringe pump, with the needle as the positive electrode and aluminum foil as the negative electrode, the solution was pushed into the needle by the metering pump, and nanofibers were prepared at a spinning voltage of 15 kV, and an aluminum foil was used to fix a roller at a distance of 15 cm from the needle to collect the nanofibers;

[0039] (5) The nanofiber obtained in step (4) is dried and placed in a crosslinking reaction with 50% glutaraldehyde solution vapor with trifluoroacetic acid as a catalyst and dried at 60°C for 10h to obtain an absorption loss type electromagnetic shielding material based on conductive nanofiber.

[0040] Example 4

[0041] (1) 10g of LiF was added to 50mL of HCl solution with a concentration of 1mol / L, mechanically stirred for 10min, then 8g of Ti3AlC2 was slowly added, reacted at 35°C for 24h, then centrifuged, washed and dried to obtain MXene powder;

[0042] (2) 20mL of aniline monomer was dispersed with 5g of MXene solid powder obtained in step (1) in 50mL of sulfuric acid with a concentration of 1mol / L to prepare a MXene solution, then 20g of ammonium persulfate was added to the mixed solution, and the reaction was carried out under magnetic stirring at 0°C ice bath for 4h, then the product was filtered, washed and dried to obtain a polyaniline / MXene composite;

[0043] (3) 8g of polyaniline / MXene composite obtained in step (2), 10g of polyvinyl alcohol and 5g of polyethylene glycol were dispersed in 150mL of deionized water, and mixed at a stirring speed of 200r / min at 85°C until the polyaniline / MXene composite was uniformly dispersed and the polyvinyl alcohol and polyethylene glycol were completely dissolved to obtain a mixed solution;

[0044] (4) The mixed solution obtained in step (3) was injected into a syringe with a volume of 10mL and a needle diameter of 0.8mm, and the bubbles were discharged, then it was fixed on a micro syringe pump, with the needle as the positive electrode and aluminum foil as the negative electrode, the solution was pushed into the needle by the metering pump, and nanofiber was prepared at a spinning voltage of 15kV, and the aluminum foil was fixed on the roller at a distance of 15cm from the needle to collect the nanofiber;

[0045] (5) The nanofiber obtained in step (4) was dried and placed in a crosslinking reaction with 50% glutaraldehyde solution vapor with trifluoroacetic acid as a catalyst and dried at 60°C for 10h to obtain an absorption loss type electromagnetic shielding material based on conductive nanofiber.

[0046] Table 1 is the average electromagnetic shielding energy (SE) and absorption loss shielding efficiency (SE A ) parameters of the absorption loss type electromagnetic shielding material based on conductive nanofiber prepared based on Examples 1-4 in the X band. The SE of the composite material obtained in Examples 1-4 is between 27dB and 30dB, showing good electromagnetic shielding performance; the SE ABetween 23 dB and 25 dB, indicating that most of the electromagnetic waves are absorbed by the inside of the conductive nanofiber, which is an ideal shielding material and has good application prospects in the field of electromagnetic shielding.

[0047] Table 1. Electromagnetic shielding performance parameters of the conductive nanofiber obtained in the example

[0048] Group Example 1 Example 2 Example 3 Example 4 SE (dB) 28 29 27 30 SE A (dB)]]> 24 25 23 25

Claims

1. A method for preparing an electrically conductive nanofiber-based absorption loss type electromagnetic shielding material, characterized by, The process comprises the following steps: surface modification of polyaniline on MXene, introduction of polyaniline / MXene composite into polyvinyl alcohol and polyethylene glycol aqueous solution to prepare conductive nanofibers by electrospinning, and cross-linking of the obtained nanofibers by glutaraldehyde to obtain an absorption loss type electromagnetic shielding material.

2. The method for preparing an electrically conductive nanofiber-based absorption loss type electromagnetic shielding material according to claim 1, characterized by, Specifically comprising the following steps: (1) 10-15 g of LiF is added to 50 mL of HCl solution with a concentration of 1 mol / L, and mechanical stirring is performed for 5-15 min, then MAX phase is slowly added, and reaction is performed at 30-40℃ for 24 h, followed by centrifugation, washing and drying to obtain MXene powder; (2) 20 mL of aniline monomer and 5-10 g of MXene solid powder obtained in step (1) are dispersed in 50-100 mL of protonic acid with a concentration of 1 mol / L to prepare a MXene solution, then 20-50 g of ammonium persulfate is added to the mixed solution, and magnetic stirring is performed at 0℃ under ice bath condition for 4-6 h, then the obtained product is filtered, washed and dried to obtain a polyaniline / MXene composite; (3) The polyaniline / MXene composite, polyvinyl alcohol and polyethylene glycol obtained in step (2) are dispersed in deionized water, and mixing is performed at a stirring speed of 200 r / min at 70-90℃ until the polyaniline / MXene composite is uniformly dispersed and the polyvinyl alcohol and polyethylene glycol are completely dissolved to obtain a mixed solution, and the solid content of the polyaniline / MXene composite in the polyvinyl alcohol solution is 10%-15%; (4) The mixed solution obtained in step (3) is injected into a syringe with a volume of 10 mL and a needle diameter of 0.8 mm, and bubbles are discharged, then the syringe is fixed on a micro-injection pump, the needle is used as the positive electrode, and aluminum foil is used as the negative electrode, the solution is pushed into the needle by the metering pump, and nanofibers are prepared at a spinning voltage of 10-20 kV, and the aluminum foil is fixed on a roller at a distance of 10-15 cm from the needle to collect the nanofibers; (5) The nanofibers obtained in step (4) are dried, then placed in a 50% glutaraldehyde solution vapor with trifluoroacetic acid as a catalyst to perform cross-linking reaction, and dried at 60℃ for 10-12 h to obtain an absorption loss type electromagnetic shielding material based on conductive nanofibers.

3. The method for preparing the absorption-loss type electromagnetic shielding material based on conductive nanofibers according to claim 2, characterized in that, The MAX phase in step (1) is one or more of Ti3AlC2, Ti2AlC or Ti3AlCN, and the particle size is ≤200 mesh.

4. The method for preparing the absorption-loss type electromagnetic shielding material based on conductive nanofibers according to claim 2, characterized in that, The protonic acid in step (2) is hydrochloric acid, sulfuric acid, dodecylbenzenesulfonic acid and camphor sulfonic acid.

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