CNF / MXene@Ga electromagnetic shielding composite film and preparation method thereof

Abstract

The invention discloses a CNF / MXene@Ga electromagnetic shielding composite film and a preparation method thereof, comprising dispersing MXene in water, adding metal Ga, first ultrasonicating at room temperature, and then ultrasonicating under ice bath conditions to obtain a uniform MXene@Ga aqueous dispersion; adding cellulose nanofiber CNF to the dispersion and mixing evenly, performing vacuum-assisted filtration, and then adding a water-soluble organic solvent with a boiling point lower than that of water to continue vacuum filtration, performing solvent exchange, repeating multiple times, and after the organic solvent is drained, removing the film and drying it to obtain a CNF / MXene@Ga electromagnetic shielding composite film. The electromagnetic shielding composite film has a multilayer structure stacked layer by layer, and also has good flexibility and tensile strength, and at the same time has the functions of electromagnetic shielding, Joule heating, photothermal conversion, etc.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanomaterials, and specifically relates to a CNF / MXene@Ga electromagnetic shielding composite film and a preparation method thereof. Background Art

[0002] With the advent of the 5G era and the rapid development of communication technology, the impact of electromagnetic interference on the normal operation of equipment and human health cannot be ignored. In particular, the development trend of lightweight and portable electronic equipment has put forward new requirements for electromagnetic shielding materials. MXene (two-dimensional transition metal carbide, nitride or carbonitride), as a highly conductive two-dimensional material, has received widespread attention in the field of electromagnetic shielding, and Ti3C2 MXene has the best performance. Gallium (Ga), as a liquid metal (melting point 29.8℃), has extremely low vapor pressure and non-toxicity, and is promising in flexible electronics, drug transportation, robotics and other fields. Solid gallium is easily dispersed into micrometers or nanoparticles under the action of ultrasound, and has application potential in the field of nanomaterials due to its phase change, high thermal conductivity and high electrical conductivity. As an interface material for electronic equipment, it is not enough to only realize the function of electromagnetic shielding. For example, the temperature of the equipment needs to be controlled in a low temperature environment to ensure normal operation. Therefore, it is urgent to develop new materials to give electromagnetic shielding materials Joule heating, photothermal conversion and other capabilities based on the basic functions of existing electromagnetic shielding materials, so that they can achieve temperature control of equipment under low voltage or light conditions. Summary of the invention

[0003] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a CNF / MXene@Ga electromagnetic shielding composite film and a preparation method thereof that can improve the mechanical strength of MXene-based materials and realize thermal management functions such as electromagnetic shielding, electrothermal, and photothermal conversion.

[0004] In order to solve the above technical problems, the present invention adopts the following technical solutions.

[0005] A method for preparing a CNF / MXene@Ga electromagnetic shielding composite film comprises the following steps:

[0006] (1) Dispersing MXene in water, adding metallic Ga, and ultrasonicating at room temperature first, and then ultrasonicating in an ice bath to obtain a uniform MXene@Ga aqueous dispersion;

[0007] (2) Add cellulose nanofibers CNF to the aqueous dispersion of MXene@Ga and mix them evenly, perform vacuum-assisted filtration, and then add a water-soluble organic solvent with a boiling point lower than that of water to continue vacuum filtration to perform solvent exchange. Repeat this process several times. After the organic solvent is dried, remove the membrane and dry it to obtain a CNF / MXene@Ga electromagnetic shielding composite membrane.

[0008] In the above-mentioned method for preparing the CNF / MXene@Ga electromagnetic shielding composite film, preferably, in step (1), the mass ratio of the MXene to the metal Ga is 2 to 10:1, and the concentration of the MXene dispersed in water is 1 mg / mL to 3 mg / mL.

[0009] In the above-mentioned method for preparing the CNF / MXene@Ga electromagnetic shielding composite film, preferably, in step (1), the time of the room temperature ultrasound is 3 min to 5 min, the total time of the room temperature ultrasound and the ultrasound under ice bath conditions is 10 min to 20 min, and the ultrasound is repeated for 3s to 5s and then stopped for 1s to 3s.

[0010] In the above-mentioned method for preparing the CNF / MXene@Ga electromagnetic shielding composite film, preferably, in step (1), the MXene is Ti3C2.

[0011] In the method for preparing the above-mentioned CNF / MXene@Ga electromagnetic shielding composite film, preferably, the mass ratio of the MXene to the cellulose nanofiber CNF is 1 to 9:1.

[0012] In the above-mentioned method for preparing the CNF / MXene@Ga electromagnetic shielding composite film, preferably, in step (2), the mixing is uniformly carried out by vortex oscillation, and the oscillation time is 10 min to 20 min.

[0013] In the above-mentioned method for preparing the CNF / MXene@Ga electromagnetic shielding composite film, preferably, in step (2), the water-soluble organic solvent having a boiling point lower than that of water is one of ethanol and acetone.

[0014] In the above-mentioned method for preparing the CNF / MXene@Ga electromagnetic shielding composite film, preferably, in step (2), the repetition is more than 3 times, the drying is vacuum drying, the vacuum drying temperature is 40°C, and the vacuum drying time is 1h to 24h.

[0015] As a general technical concept, the present invention also provides a CNF / MXene@Ga electromagnetic shielding composite film prepared by the above-mentioned preparation method.

[0016] The above-mentioned CNF / MXene@Ga electromagnetic shielding composite film preferably has a multilayer structure stacked layer by layer, with a maximum shielding effectiveness of more than 47dB, a tensile strength of more than 35MPa, and a maximum temperature of more than 139°C at a voltage of 4V.

[0017] Compared with the prior art, the advantages of the present invention are:

[0018] The method of the present invention uses simple ultrasound, vacuum filtration and other methods to prepare CNF / MXene@Ga electromagnetic shielding composite film, and the prepared electromagnetic shielding composite film has good flexibility, tensile strength, electromagnetic shielding, Joule heating and photothermal conversion capabilities. The composite film integrates the advantages of multiple materials and realizes functions that cannot be achieved by a single material, and can solve the problem of thermal management of electronic equipment itself in cold environments. The CNF used is a natural green polymer, and the low vapor pressure of liquid metal Ga ensures its safety. It has the potential to be applied to electronic equipment as an interface material with electromagnetic interference shielding as the main function and multi-function as the auxiliary function to ensure the normal operation of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the process flow of the method for preparing the CNF / MXene@Ga electromagnetic shielding composite film in an embodiment of the present invention.

[0020] Figure 2 This is a diagram showing the flexibility of the CNF / MXene@Ga electromagnetic shielding composite film CMG-1 of Example 1 of the present invention.

[0021] Figure 3 This is a cross-sectional scanning electron microscope photograph of the CNF / MXene@Ga electromagnetic shielding composite film CMG-3 of Example 3 of the present invention.

[0022] Figure 4 Graphs showing the tensile strength and elongation at break of the CNF / MXene@Ga electromagnetic shielding composite films CMG-1, CMG-2, CMG-3, and CMG-4 of Examples 1-4 of the present invention.

[0023] Figure 5 This is a diagram of the shielding effectiveness of the CNF / MXene@Ga electromagnetic shielding composite films CMG-1, CMG-2, CMG-3, and CMG-4 of Examples 1-4 of the present invention in the X-band.

[0024] Figure 6 This is a Joule heating temperature change diagram of the CNF / MXene@Ga electromagnetic shielding composite film CMG-4 of Example 4 of the present invention at a voltage of 2-4V.

[0025] Figure 7 Temperature variation diagram of CNF / MXene@Ga electromagnetic shielding composite films CMG-1, CMG-2, CMG-3, and CMG-4 of Examples 1-4 of the present invention under a xenon lamp light source. DETAILED DESCRIPTION

[0026] The present invention is further described below in conjunction with the accompanying drawings and specific preferred embodiments, but the scope of protection of the present invention is not limited thereby. The materials and instruments used in the following examples are all commercially available. Cellulose nanofiber CNF is usually prepared by mechanical preparation or chemical oxidation, and can be directly purchased commercially. The CNF in the following examples comes from Shansi Technology Co., Ltd.

[0027] In the following examples, the concentration of the aqueous dispersion of MXene is 2 mg / mL, the ultrasonic time of the cell crusher is 15 minutes, 3 seconds on and 1 second off, the cellulose nanofiber CNF used is commercially available (mechanically produced), the vortex oscillation time is 10 minutes, and the water-soluble organic solvent with a boiling point lower than that of water is ethanol.

[0028] Example 1

[0029] A method for preparing a CNF / MXene@Ga electromagnetic shielding composite film of the present invention, such as Figure 1 As shown, the following steps are included:

[0030] (1) Weigh 60 mg of MXene and 6 mg of metallic Ga blocks, so that the mass ratio of MXene:Ga is 10:1, and MXene is specifically Ti3C2. Disperse MXene in 30 mL of deionized water to make the MXene concentration 2 mg / mL. Add Ga blocks and sonicate with a cell crusher for 15 minutes, with the first 3 minutes at room temperature and then in an ice bath to obtain a uniform MXene@Ga aqueous dispersion.

[0031] (2) Weigh 20 mg of cellulose nanofiber CNF and add it to the aqueous dispersion of MXene@Ga to make the mass ratio of MXene:CNF = 3:1. Subsequently, the obtained mixed solution was oscillated on a vortex oscillator for 10 minutes, and the evenly mixed dispersion was poured into a filtration bottle. Vacuum filtration was performed by adding ethanol to continue vacuum filtration, and solvent exchange was repeated 3 times. After all the ethanol was drained, the membrane was removed and vacuum dried at 40°C for 1 hour to obtain a CNF / MXene@Ga electromagnetic shielding composite membrane. The obtained CNF / MXene@Ga electromagnetic shielding composite membrane was named CMG-1. The composite membrane has a multilayer structure (multilayer superposition), such as Figure 2 As shown, the composite film has good flexibility and excellent tensile strength. While achieving electromagnetic shielding, it can also achieve functions such as photothermal conversion and Joule heating.

[0032] Example 2

[0033] A method for preparing a CNF / MXene@Ga electromagnetic shielding composite film of the present invention, such as Figure 1 As shown, the following steps are included:

[0034] (1) Weigh 60 mg of MXene and 10 mg of metallic Ga block so that the mass ratio of MXene:Ga is 6:1, and MXene is specifically Ti3C2. Disperse MXene in 30 mL of deionized water so that the MXene concentration is 2 mg / mL. Add Ga block and sonicate with a cell crusher for 15 minutes, with the first 3 minutes at room temperature and then in an ice bath to obtain a uniform MXene@Ga aqueous dispersion.

[0035] (2) Weigh 20 mg of CNF and add it to the aqueous dispersion of MXene@Ga to make the mass ratio of MXene:CNF = 3:1. Subsequently, the obtained mixed solution was oscillated on a vortex oscillator for 10 minutes, the uniformly mixed dispersion was filtered by vacuum assisted filtration, ethanol was added to continue vacuum filtration, and solvent exchange was repeated 3 times. After all the ethanol was drained, the membrane was removed and vacuum dried at 40°C for 1 hour to obtain a CNF / MXene@Ga electromagnetic shielding composite membrane, named CMG-2. The composite membrane has a multilayer structure with good flexibility and tensile strength. While achieving electromagnetic shielding, it can also realize functions such as photothermal conversion and Joule heating.

[0036] Example 3

[0037] A method for preparing a CNF / MXene@Ga electromagnetic shielding composite film of the present invention, such as Figure 1 As shown, the following steps are included:

[0038] (1) Weigh 60 mg of MXene and 15 mg of metallic Ga blocks, so that the mass ratio of MXene:Ga is 4:1, and the MXene is specifically Ti3C2. Disperse MXene in 30 mL of deionized water so that the MXene concentration is 2 mg / mL. Add Ga blocks and sonicate with a cell crusher for 15 minutes, with the first 3 minutes at room temperature and then in an ice bath to obtain a uniform MXene@Ga aqueous dispersion.

[0039] (2) Weigh 20 mg of CNF and add it to the aqueous dispersion of MXene@Ga to make the mass ratio of MXene:CNF = 3:1. Then, oscillate the resulting mixture on a vortex oscillator for 10 minutes, filter the uniformly mixed dispersion using vacuum assisted filtration, add ethanol and continue vacuum filtration, perform solvent exchange, and repeat 3 times. After all the ethanol is drained, remove the membrane and dry it in vacuum at 40°C for 1 hour to obtain a CNF / MXene@Ga electromagnetic shielding composite membrane, named CMG-3. Figure 3 As shown, the composite film has a multilayer structure with layers stacked one on top of the other. The composite film also has good flexibility and tensile strength, and can achieve functions such as photothermal conversion and Joule heating while achieving electromagnetic shielding.

[0040] Example 4

[0041] A method for preparing a CNF / MXene@Ga electromagnetic shielding composite film of the present invention, such as Figure 1 As shown, the following steps are included:

[0042] (1) Weigh 60 mg of MXene and 20 mg of metallic Ga blocks, so that the mass ratio of MXene:Ga is 3:1, and MXene is specifically Ti3C2. Disperse MXene in 30 mL of deionized water to make the MXene concentration 2 mg / mL. Add Ga blocks and use a cell crusher to sonicate for 15 minutes, with the first 3 minutes at room temperature and then in an ice bath to obtain a uniform MXene@Ga dispersion.

[0043] (2) Weigh 20 mg of CNF and add it to the aqueous dispersion of MXene@Ga to make the mass ratio of MXene:CNF = 3:1. Subsequently, the obtained mixed solution was oscillated on a vortex oscillator for 10 minutes, the uniformly mixed dispersion was filtered by vacuum assisted filtration, ethanol was added to continue vacuum filtration, and solvent exchange was repeated 3 times. After all the ethanol was drained, the membrane was removed and vacuum dried at 40°C for 1 hour to obtain a CNF / MXene@Ga electromagnetic shielding composite membrane, named CMG-4. The composite membrane has a multilayer structure with good flexibility and tensile strength. While achieving electromagnetic shielding, it can also realize functions such as photothermal conversion and Joule heating.

[0044] like Figure 4 As shown in Figure 2, the tensile strength of the composite films CMG-1 to CMG-4 decreases slightly with the increase of Ga content, and generally reaches about 30 MPa. Figure 5 As shown in the figure, the shielding effectiveness of the composite films CMG-1 to CMG-4 decreases with the increase of the electromagnetic wave frequency, and generally remains above 41dB. Figure 6 As shown in the figure, the temperature of the CMG-4 composite film increases significantly with the increase of DC voltage. Even at a voltage of 2V, the temperature can reach above 40°C, which can act as a good heat source. Figure 7 As shown, under the irradiation of simulated light source, the composite films of CMG-1 to CMG-4 reached temperature equilibrium in only 60s, and the maximum temperature could reach above 60℃.

[0045] Example 5

[0046] A method for preparing a CNF / MXene@Ga electromagnetic shielding composite film of the present invention, such as Figure 1 As shown, the following steps are included:

[0047] (1) Weigh 60 mg of MXene and 15 mg of metallic Ga block so that the mass ratio of MXene:Ga is 4:1, and MXene is specifically Ti3C2. Disperse MXene in 30 mL of deionized water so that the MXene concentration is 2 mg / mL. Add Ga block and sonicate with a cell crusher for 15 minutes, with the first 3 minutes at room temperature and then in an ice bath to obtain a uniform MXene@Ga aqueous dispersion.

[0048] (2) Weigh 60 mg of CNF and add it to the aqueous dispersion of MXene@Ga to make the mass ratio of MXene:CNF = 1:1. Subsequently, the resulting mixture was oscillated on a vortex oscillator for 10 minutes, the uniformly mixed dispersion was filtered by vacuum assisted filtration, ethanol was added to continue vacuum filtration, and solvent exchange was repeated 3 times. After all the ethanol was drained, the membrane was removed and vacuum dried at 40°C for 1 hour to obtain a CNF / MXene@Ga electromagnetic shielding composite membrane, named CMG-5. The composite membrane has a multilayer structure with good flexibility and tensile strength. While achieving electromagnetic shielding, it can also realize functions such as photothermal conversion and Joule heating.

[0049] Example 6

[0050] A method for preparing a CNF / MXene@Ga electromagnetic shielding composite film of the present invention, such as Figure 1 As shown, the following steps are included:

[0051] (1) Weigh 60 mg of MXene and 15 mg of metallic Ga blocks, so that the mass ratio of MXene:Ga is 4:1, and the MXene is specifically Ti3C2. Disperse MXene in 30 mL of deionized water so that the MXene concentration is 2 mg / mL. Add Ga blocks and sonicate with a cell crusher for 15 minutes, with the first 3 minutes at room temperature and then in an ice bath to obtain a uniform MXene@Ga aqueous dispersion.

[0052] (2) Weigh 30 mg of CNF and add it to the aqueous dispersion of MXene@Ga to make the mass ratio of MXene:CNF = 2:1. Subsequently, the resulting mixture was oscillated on a vortex oscillator for 10 minutes, the uniformly mixed dispersion was filtered by vacuum assisted filtration, ethanol was added to continue vacuum filtration, and solvent exchange was repeated 3 times. After all the ethanol was drained, the membrane was removed and vacuum dried at 40°C for 1 hour to obtain a CNF / MXene@Ga electromagnetic shielding composite membrane, named CMG-6. The composite membrane has a multilayer structure with good flexibility and tensile strength. While achieving electromagnetic shielding, it can also realize functions such as photothermal conversion and Joule heating.

[0053] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as above in the preferred embodiment, it is not used to limit the present invention. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention, still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for preparing a CNF / MXene@Ga electromagnetic shielding composite film, characterized in that: The following steps are involved: (1) Disperse MXene in water, add metallic Ga, and perform ultrasonic treatment at room temperature first, and then in an ice bath to obtain a uniform MXene@Ga aqueous dispersion; (2) Add cellulose nanofibers CNF to the aqueous dispersion of MXene@Ga and mix them evenly, perform vacuum-assisted filtration, and then add a water-soluble organic solvent with a boiling point lower than that of water to continue vacuum filtration to exchange the solvent. Repeat this process several times. After the organic solvent is drained, remove the membrane and dry it to obtain a CNF / MXene@Ga electromagnetic shielding composite membrane. In step (1), the mass ratio of the MXene to the metal Ga is 2 to 10:1, and the MXene is Ti3C2; The mass ratio of the MXene to the cellulose nanofiber CNF is 1 to 9:1; The CNF / MXene@Ga electromagnetic shielding composite film has a multilayer structure stacked layer by layer.

2. The method for preparing the CNF / MXene@Ga electromagnetic shielding composite film according to claim 1, characterized in that: In step (1), the concentration of MXene dispersed in water is 1 mg / mL to 3 mg / mL.

3. The method for preparing the CNF / MXene@Ga electromagnetic shielding composite film according to claim 1, characterized in that: In step (1), the time of the room temperature ultrasound is 3 min to 5 min, and the total time of the room temperature ultrasound and the ultrasound in an ice bath is 10 min to 20 min, with each ultrasound being performed for 3s to 5s and then stopped for 1s to 3s.

4. The method for preparing a CNF / MXene@Ga electromagnetic shielding composite film according to any one of claims 1 to 3, characterized in that: In step (2), the mixing is carried out uniformly by vortex oscillation, and the oscillation time is 10 min to 20 min.

5. The method for preparing a CNF / MXene@Ga electromagnetic shielding composite film according to any one of claims 1 to 3, characterized in that: In step (2), the water-soluble organic solvent having a boiling point lower than that of water is one of ethanol and acetone.

6. The method for preparing a CNF / MXene@Ga electromagnetic shielding composite film according to any one of claims 1 to 3, characterized in that: In step (2), the repetition is repeated more than 3 times, the drying is vacuum drying, the vacuum drying temperature is 40° C., and the vacuum drying time is 1 h to 24 h.

7. A CNF / MXene@Ga electromagnetic shielding composite film prepared by the preparation method according to any one of claims 1 to 6.

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