Gradient design and preparation method based on graphene aerogel fibers

Abstract

The invention relates to a gradient design based on graphene aerogel fibers and a preparation method of the graphene aerogel fibers, and belongs to the technical field of preparation of wave-absorbing materials. The graphene-based aerogel fiber gradient design and preparation method comprises the following steps that firstly, graphene and TPU are mixed, then carbon nanotubes, MXene, silicon dioxide fibers and the like are mixed according to a certain mass ratio, and a spinning precursor is obtained; and then injecting the slurry into a water tank by adopting wet spinning, and freeze-drying to obtain the aerogel fiber. And by adopting an impedance gradient structure design, the dried aerogel fibers are laid to obtain the composite material. According to the graphene aerogel fiber gradient design and the preparation method thereof, on the basis of a special core-shell structure, the outer layer is compounded with TPU, so that the mechanical property of the aerogel is enhanced while the internal structure of the aerogel is reserved. Due to the design of the multi-layer gradient structure, each layer has different impedance matching characteristics, the impedance matching performance and the high-loss performance are both considered, and the broadband wave absorbing performance is achieved.

Description

Technical Field

[0001] The present invention relates to a gradient design of graphene aerogel fibers and a preparation method thereof, belonging to the technical field of preparation of microwave absorption materials. Background Art

[0002] Graphene is a two-dimensional layered material. Due to its light weight and high conductivity, and with a large number of functional groups and intrinsic defects on its surface, it can increase dipole polarization, making graphene an excellent electromagnetic wave absorption material. Aerogel fibers have become the focus of wide application due to their high specific surface area, high porosity, low density, and low thermal conductivity. However, currently, for the application of aerogel fibers, it is mostly in the field of thermal insulation. Functionalization of aerogels is a major method to expand their application fields. Moreover, traditional aerogel fibers have poor mechanical properties and cannot meet the requirements of various special-shaped devices for microwave absorption materials. By wrapping a layer of polymer flexible material outside the aerogel fiber, its mechanical properties can be effectively improved. The aerogel structure inside the fiber can not only improve the impedance matching characteristics but also provide space for the functionalization of aerogel fibers to accommodate other components, and can undertake rich functions of interacting with ions or molecules.

[0003] Therefore, inspired by animal fur, the present invention uses graphene as the main body of aerogel fibers, wraps a layer of TPU on the outer layer to form a special core-shell structure, realizes both mechanical properties and multifunctionality, and through the design of a gradient structure, realizes relatively broadband microwave absorption performance. Summary of the Invention

[0004] The purpose of the present invention is to provide a gradient design of graphene aerogel fibers and a preparation method thereof, and the prepared impedance-graded graphene aerogel fiber microwave absorption material has good flexibility and electromagnetic wave absorption performance.

[0005] The present invention also provides an impedance-graded graphene aerogel fiber microwave absorption material prepared by the above preparation method.

[0006] In order to achieve the above purposes, the technical solution adopted by the impedance-graded graphene aerogel fiber microwave absorption material of the present invention is as follows:

[0007] A gradient design of graphene aerogel fibers and a preparation method thereof, including the following steps: First, mix graphene with TPU. Secondly, mix carbon nanotubes, MXene, silica fibers, etc. according to a certain mass ratio to obtain a spinning precursor. Subsequently, adopt wet spinning, inject the slurry into a water tank and then freeze-dry to obtain aerogel fibers. Adopt an impedance gradient structure design, and lay the dried aerogel fibers to obtain the product.

[0008] The gradient design and preparation method of the graphene aerogel fiber of the present invention, based on a special core-shell structure, enhances its mechanical properties while retaining the internal structure of the aerogel by compounding with TPU on the outer layer. The design of the multi-layer gradient structure enables each layer to have different impedance matching characteristics, taking into account both impedance matching and high-loss performance, so that it has a relatively broadband wave-absorbing performance.

[0009] Preferably, the concentration of the graphene oxide slurry is 1-18 mg / g, preferably 4-10 mg / g.

[0010] Preferably, the mass ratio of the graphene oxide, carbon nanotubes, MXene, and silica fiber is 1:1-1:5, preferably 1:1-1:4.

[0011] Preferably, the number of layers of the multi-layer structure is 2-5 layers, preferably 3-5 layers.

[0012] Preferably, the preparation of the spinning precursor includes the following steps: First, replace the solvent of the graphene oxide slurry with DMF, dissolve TPU in DMF, mix the graphene and TPU according to a certain mass ratio, stir evenly under magnetic stirring, and then add carbon nanotubes, MXene, and silica fiber to the above mixed solution according to a certain mass ratio respectively, and stir evenly to obtain the spinning precursor solution.

[0013] Preferably, the wet spinning includes the following steps: First, transfer the above spinning precursor to a syringe, inject the spinning solution into the coagulation bath by an injection pump, and the coagulation bath uses deionized water. Then, collect the fiber in the coagulation bath and perform freeze-drying. The freezing time is 1-3 h, preferably 2 h.

[0014] Preferably, the treatment time of the freeze-drying gradually increases with the increase of the thickness of the composite material, and the freeze-drying time is 3-6 days, preferably 6 days.

[0015] Preferably, the reduction method is hydrazine hydrate vapor reduction, and the mass ratio of the graphene oxide and hydrazine hydrate is 1:1-1:3.5, preferably 1:3.5.

[0016] Preferably, the design of the multi-layer impedance gradient structure includes the following steps: First, perform the multi-layer structure design by the simulation software in the way that the impedance gradient increases from top to bottom in turn, and obtain a relatively broadband wave-absorbing performance by adjusting the electromagnetic parameters and thickness of each layer, so as to determine the electromagnetic parameter distribution and the corresponding thickness of each layer in the multi-layer structure. Then, lay the prepared aerogel fiber according to the designed structure to obtain it.

[0017] The technical solution adopted by the present invention based on the gradient design and preparation method of the graphene aerogel fiber is as follows:

[0018] An impedance-gradient graphene aerogel fiber microwave absorbing material prepared by using the above-mentioned graphene aerogel fiber gradient design and its preparation method.

[0019] The graphene aerogel fiber gradient design and its preparation method of the present invention are based on a special core-shell structure. By compounding with TPU on the outer layer, while retaining the internal structure of the aerogel, its mechanical properties are enhanced. The design of the multi-layer gradient structure enables each layer to have different impedance matching characteristics, taking into account both impedance matching and high-loss performance, so that it has relatively broadband microwave absorbing performance. Description of the Drawings

[0020] Figure 1 SEM image of the graphene / silica aerogel fiber prepared in Example 1 of the present invention;

[0021] Figure 2 SEM image of the graphene / carbon nanotube aerogel fiber prepared in Example 2 of the present invention;

[0022] Figure 3 SEM image of the graphene / MXene aerogel fiber prepared in Example 3 of the present invention. Detailed Description of the Invention

[0023] The technical solution of the present invention will be further described below in conjunction with specific embodiments.

[0024] Example 1

[0025] The graphene aerogel fiber gradient design and its preparation method of this example include the following steps:

[0026] 1) Change the solvent of the graphene oxide slurry from water to DMF to prepare graphene slurries with different concentrations.

[0027] 2) Prepare a TPU solution, mix the graphene slurry and the TPU solution according to a mass ratio of 10:1. After stirring evenly, add silica fibers to the above mixed solution according to a certain mass ratio, and stir evenly by magnetic stirring. Then the spinning precursor solution can be obtained.

[0028] 3) Transfer the prepared spinning precursor solution to a syringe, and use an injection pump with an injection rate controlled at 1 mL / min. Inject the solution into the coagulation bath, collect the fibers in the coagulation bath, and then perform freeze-drying treatment on the fibers to obtain aerogel fibers.

[0029] 4) Reduce the obtained aerogel fibers by hydrazine hydrate, and then test their electromagnetic parameters.

[0030] 5) Calculate the electromagnetic parameters obtained in step 4) through simulation software and conduct gradient structure design. For different layers, adopt different electromagnetic parameters and different thicknesses to design and obtain a relatively broadband wave-absorbing performance.

[0031] 6) Based on the design result of step 5), invert the required electromagnetic parameters and thickness, and lay the prepared graphene-based aerogel fibers to obtain the product.

[0032] Example 2

[0033] The gradient design of graphene aerogel fiber and its preparation method in this example include the following steps:

[0034] 1) Change the solvent of the graphene oxide slurry from water to DMF to prepare graphene slurries with different concentrations.

[0035] 2) Prepare a TPU solution, mix the graphene slurry and the TPU solution according to a mass ratio of 10:1. After stirring evenly, add carbon nanotubes to the above mixed solution according to a certain mass ratio and stir evenly with a magnetic stirrer to obtain a spinning precursor solution.

[0036] 3) Transfer the prepared spinning precursor solution to a syringe, use an injection pump, and control the injection rate at 1 mL / min. Inject the solution into the coagulation bath, collect the fibers in the coagulation bath, and conduct freeze-drying treatment on the fibers to obtain aerogel fibers.

[0037] 4) Reduce the obtained aerogel fibers with hydrazine hydrate, and then test their electromagnetic parameters.

[0038] 5) Calculate the electromagnetic parameters obtained in step 4) through simulation software and conduct gradient structure design. For different layers, adopt different electromagnetic parameters and different thicknesses to design and obtain a relatively broadband wave-absorbing performance.

[0039] 6) Based on the design result of step 5), invert the required electromagnetic parameters and thickness, and lay the prepared graphene-based aerogel fibers to obtain the product.

[0040] Example 3

[0041] The gradient design of graphene aerogel fiber and its preparation method in this example include the following steps:

[0042] 1) Change the solvent of the graphene oxide slurry from water to DMF to prepare graphene slurries with different concentrations.

[0043] 2) Prepare the TPU solution, mix the graphene slurry and the TPU solution at a mass ratio of 10:1. After stirring evenly, add MXene to the above mixed solution at a certain mass ratio and stir evenly with a magnetic stirrer. Then the spinning precursor solution can be obtained.

[0044] 3) Transfer the prepared spinning precursor solution to a syringe, use an injection pump, and control the injection rate at 1 mL / min. Inject the solution into the coagulation bath, collect the fibers in the coagulation bath, and then perform freeze-drying treatment on the fibers to obtain aerogel fibers.

[0045] 4) Reduce the obtained aerogel fibers with hydrazine hydrate, and then test their electromagnetic parameters.

[0046] 5) Calculate the electromagnetic parameters obtained in step 4) through simulation software and conduct gradient structure design. For different layers, use different electromagnetic parameters and different thicknesses to design and obtain broadband microwave absorption properties.

[0047] 6) Based on the design results in step 5), invert the required electromagnetic parameters and thickness, and lay the prepared graphene-based aerogel fibers to obtain the product.

[0048] Perform SEM tests on the graphene / silica aerogel fibers prepared in step 4) of Example 1. The obtained SEM images are shown in Figure 1 , as can be seen from Figure 1 that the aerogel structure is relatively well preserved; perform SEM tests on the graphene / carbon nanotube aerogel fibers prepared in step 4) of Example 2. The obtained SEM images are shown in Figure 2 , and perform SEM tests on the graphene / MXene aerogel fibers prepared in step 4) of Example 3. The obtained SEM images are as shown in Figure 3 .

[0049] Experimental Example

[0050] Test the electromagnetic parameters of the graphene-based aerogel fibers prepared in Examples 1, 2, and 3, and the microwave absorption properties of the prepared impedance-gradient graphene aerogel fiber absorbing materials.

[0051] The test method is to use an Agilent N5244A vector network analyzer for testing. The electromagnetic parameters of the graphene-based aerogel fibers are obtained through the coaxial method test, and the microwave absorption properties of the impedance-gradient graphene aerogel fiber absorbing materials are tested through the bow-tie method. The electromagnetic wave band is 2 - 18 GHz.

[0052] As can be seen from the above embodiments, the present invention provides a graphene aerogel fiber gradient design and its preparation method. Based on a special core-shell structure, by compounding with TPU on the outer layer, while retaining the internal structure of the aerogel, its mechanical properties are enhanced. The design of the multi-layer gradient structure enables each layer to have different impedance matching characteristics, taking into account both impedance matching and high-loss performance, so that it has a relatively broadband wave-absorbing performance.

[0053] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for gradient design and preparation of graphene-based aerogel fibers, characterized in that: It includes the following steps: First, mix graphene with TPU. Secondly, mix carbon nanotubes, MXene, silica fibers, etc. respectively according to a certain mass ratio to obtain a spinning precursor. Subsequently, wet spinning is adopted. After injecting the slurry into a water tank, freeze-drying is carried out to obtain aerogel fibers. The impedance gradient structure design is adopted, and the dried aerogel fibers are laid to obtain the product.

2. The method for gradient design and preparation of graphene-based aerogel fibers according to claim 1, wherein: The concentration of the graphene oxide slurry is 4 - 12 mg / mL.

3. The method for gradient design and preparation of graphene-based aerogel fibers according to claim 1, characterized in that: The concentration of the TPU solution is 0.5 - 1 g / mL.

4. The gradient design and preparation method of the graphene-based aerogel fiber according to claim 1, characterized in that: The mass ratio of graphene to carbon nanotubes, MXene, and silica fibers is 1:1 - 1:

4.

5. The gradient design and preparation method of the graphene-based aerogel fiber according to claim 1, characterized in that: The impedance gradient structure design is 2 - 5 layers.

6. The gradient design and preparation method of the graphene-based aerogel fiber according to any one of claims 1-5, characterized in that: The method for compounding graphene oxide with carbon nanotubes, MXene, and silica fibers includes the following steps: First, mix graphene with the TPU solution. Subsequently, carbon nanotubes, MXene, and silica fibers are respectively compounded with the graphene and TPU mixed solution according to a certain mass ratio.

7. The method for gradient design and preparation of graphene-based aerogel fibers according to claim 1, characterized in that: The wet spinning includes the following steps: First, transfer the mixed solution to a syringe, and use an injection pump to inject the spinning solution into the coagulation bath at an injection rate of 1 mL / min. Collect the fibers in the coagulation bath and then carry out freeze-drying, and then reduction can obtain graphene-based aerogel fibers.

8. The preparation method for the gradient design of the graphene-based aerogel fiber according to claim 1, wherein: The design of the impedance gradient structure includes the following steps: First, carry out a multi-layer structure design through simulation software in the way that the impedance gradient increases from top to bottom. Based on the designed gradient structure, select the graphene-based aerogel fibers that meet the electromagnetic parameters of each layer of the gradient structure, and lay them according to the designed order and thickness to obtain the product.

9. An impedance-gradient graphene aerogel fiber absorbing material prepared by a preparation method adopting the gradient design of the graphene-based aerogel fiber as described in any one of claims 1 - 8.

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