BaTiO3 / graphene composite flexible wave-absorbing plate and preparation method thereof

Abstract

The invention relates to a preparation method of a flexible BaTiO3 / graphene / PDMS composite material, and belongs to the technical field of preparation of wave-absorbing materials. The preparation method provided by the invention comprises the following steps: firstly, preparing graphene oxide slurry, and adding barium titanate nanoparticles and performing ultrasonic dispersion to obtain barium titanate / graphene oxide composite slurry; freeze-drying the composite slurry to obtain barium titanate / graphene oxide aerogel; then, the aerogel is subjected to hydrazine hydrate reduction treatment; and finally, mixing the reduced aerogel with hydroxyl silicone oil, a curing agent and normal hexane, and preparing the flexible composite material through a PDMS pouring process. The composite material disclosed by the invention not only has dielectric constant adjusting capability, but also has excellent microwave absorption performance, and is suitable for the application fields of flexible electronic devices and microwave absorption.

Description

Technical Field

[0001] The invention relates to a flexible BaTiO3 / graphene / PDMS composite material and a preparation method thereof, belonging to the technical field of wave absorbing material preparation. Background Art

[0002] Graphene is a two-dimensional layered material. It has the characteristics of light weight and high conductivity. At the same time, it also has a large number of functional groups and intrinsic defects on the surface, which can increase dipole polarization, making graphene an excellent new electromagnetic wave absorbing material and has attracted widespread attention. In 2011, Han et al. found that the absorption intensity of reduced graphene oxide was -6.9dB at 7GHz. (Reference [1]: Chao Wang, Xijiang Han, Ping Xu, et al. The electromagnetic property of chemically reduced graphene oxide and its application as microwave absorbing material [J]. Applied Physics Letters, 2011, 98 (7): 072906.) However, the absorption band of single graphene is narrow, and the mechanical properties of graphene are poor. At present, most of the absorbing plates studied at home and abroad are rigid materials with poor flexibility. There is an urgent need for the integration of stealth and load-bearing materials, that is, the new material should not only have good absorbing performance, but also have good mechanical properties, especially flexibility. When graphene alone is used as an absorbing material, it is difficult to meet the current demand for broadband and flexibility of absorbing materials. Summary of the invention

[0003] The purpose of the present invention is to provide a method for preparing a flexible BaTiO3 / graphene / PDMS composite material. The prepared composite flexible absorbing plate has good flexibility and good electromagnetic wave absorption performance after simulation fitting.

[0004] The present invention also provides a flexible BaTiO3 / graphene / PDMS composite material prepared by the above preparation method.

[0005] To achieve the above objectives, the technical solution adopted by the flexible BaTiO3 / graphene / PDMS composite material of the present invention is:

[0006] A method for preparing a flexible BaTiO3 / graphene / PDMS composite material comprises the following steps: compounding graphene oxide slurry diluted with deionized water and tert-butyl alcohol with barium titanate nanoparticles, laying the composite slurry in a mold with good thermal conductivity, and then pre-freezing and molding with liquid nitrogen. The molded block is freeze-dried, and then the dried block is reduced to obtain a result.

[0007] The preparation method of the flexible BaTiO3 / graphene / PDMS composite material of the present invention utilizes the dielectric material barium titanate to improve the impedance matching of graphene, and utilizes PDMS to improve the flexibility of the composite material. A composite material with both flexibility and wave absorption performance is obtained. The process is simple and stable, and not only can the flexibility of the composite material be improved, but also the electromagnetic parameters of the composite material can be adjusted by compounding with the dielectric material, thereby regulating its impedance matching characteristics, making it easier for electromagnetic waves to enter the interior of the material, and dissipating the electromagnetic waves through multiple loss mechanisms, thereby achieving better wave absorption performance.

[0008] Preferably, the concentration of the graphene oxide slurry is 1-18 mg / g, preferably 4-10 mg / g.

[0009] Preferably, the mass ratio of graphene oxide to barium titanate is 1:1-1:5, preferably 1:1-1:2.

[0010] Preferably, the method of composite graphene oxide with barium titanate comprises the following steps: The method of composite graphene oxide with barium titanate comprises the following steps: first, the graphene oxide slurry is diluted to a concentration of 4-10 mg / mL using deionized water and tert-butanol, and then barium titanate nanoparticles are added to the dispersion in a mass ratio of 1:1-1:2 and stirred thoroughly for 4 hours.

[0011] Preferably, the reduction method is hydrazine hydrate vapor reduction, and the mass ratio of graphene oxide to hydrazine hydrate is 1:1-1:3.5, preferably 1:3.5.

[0012] Preferably, the ratio of the flexible polymer in the reduction method is PDMS: curing agent: n-hexane is 10:1:1.

[0013] Preferably, the vacuum infusion of a flexible polymer into a BaTiO3 / graphene aerogel comprises the following steps: preparing a mixed solution of PDMS, a curing agent, and n-hexane, stirring at 1000 r / min for 2 min to mix evenly, and the preparation ratio is 10:1:1. -0.1 MPa vacuum defoaming for 5 min. The BaTiO3 / graphene aerogel is pressed into an uncured polymer, and the vacuum infusion process is repeated 5 times at intervals of 20 minutes to achieve the highest infusion rate. Finally, the flexible BaTiO3 / graphene / PDMS composite material is obtained by curing at 65°C for 4 hours.

[0014] The technical solution adopted by the graphene composite flexible wave absorbing plate of the present invention is:

[0015] A flexible BaTiO3 / graphene / PDMS composite material prepared by adopting the preparation method of the flexible BaTiO3 / graphene / PDMS composite material.

[0016] The flexible BaTiO3 / graphene / PDMS composite material of the present invention uses flexible polymer vacuum infusion to give aerogel flexibility. The electromagnetic parameters of the composite material are adjusted by using barium titanate, thereby regulating its impedance matching characteristics, making it easier for electromagnetic waves to enter the material, and dissipating the electromagnetic waves through multiple loss mechanisms, thereby achieving better wave absorption performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a SEM image of the BaTiO3 / graphene aerogel prepared in Example 1 of the present invention;

[0018] Figure 2 This is a SEM image of the flexible BaTiO3 / graphene / PDMS composite material obtained in Example 2 of the present invention;

[0019] Figure 3 This is a reflection loss diagram of the flexible BaTiO3 / graphene / PDMS composite material prepared in Example 2 of the present invention. DETAILED DESCRIPTION

[0020] The technical solution of the present invention is further described below in conjunction with specific implementation methods.

[0021] Example 1

[0022] The preparation method of the BaTiO3 / graphene aerogel of this embodiment comprises the following steps:

[0023] 1) Mixing graphene oxide slurry with water and tert-butyl alcohol and stirring evenly to prepare graphene oxide slurry with a concentration of 10 mg / g. Adding barium titanate nanoparticles to the 10 mg / g graphene oxide slurry at a mass ratio of 1:1, and stirring and mixing evenly.

[0024] 2) Pour the composite slurry into a mold with good thermal conductivity and scrape it flat.

[0025] 3) The layered slurry and the mold are frozen with liquid nitrogen. The freezing time is controlled by a temperature control valve. The pre-freezing temperature is -50°C and the pre-freezing time is 1 hour.

[0026] 4) Demolding the frozen block, and then drying it using a freeze-drying process.

[0027] 5) The plate dried in step 4) is placed in a blast drying oven, and then reduced with hydrazine hydrate. The mass ratio of graphene oxide to hydrazine hydrate is 1:3.5, the reduction temperature is 90° C., and the reduction time is 24 hours.

[0028] Example 2

[0029] The preparation method of the flexible BaTiO3 / graphene / PDMS composite material of this embodiment comprises the following steps:

[0030] 1) Mix the graphene oxide slurry with water and tert-butyl alcohol and stir to prepare a graphene oxide slurry with a concentration of 4 mg / g. Add barium titanate nanoparticles to the 10 mg / g graphene oxide slurry at a mass ratio of 1:2 and stir to mix thoroughly.

[0031] 2) Pour the composite slurry into a mold with good thermal conductivity and scrape it flat.

[0032] 3) The layered slurry and the mold are frozen with liquid nitrogen. The freezing time is controlled by a temperature control valve. The pre-freezing temperature is -50°C and the pre-freezing time is 1 hour.

[0033] 4) Demolding the frozen block, and then drying it using a freeze-drying process.

[0034] 5) The plate dried in step 4) is placed in a blast drying oven, and then reduced with hydrazine hydrate. The mass ratio of graphene oxide to hydrazine hydrate is 1:3.5, the reduction temperature is 90° C., and the reduction time is 24 hours.

[0035] 6) The ratio of the flexible polymer was 10:1:1 for PDMS: curing agent: n-hexane, stirred at 1000 r / min for 2 min, and defoamed at -0.1 MPa vacuum for 5 min.

[0036] 7) The BaTiO3 / graphene aerogel obtained in step 5) is placed into the cured resin obtained in step 6), and the vacuum infusion process is repeated 5 times at intervals of 20 minutes.

[0037] 8) Take out the composite in step 7) and cure it at 65° C. for 4 h.

[0038] Example 3

[0039] The preparation method of the flexible BaTiO3 / graphene / PDMS composite material of this embodiment comprises the following steps:

[0040] 1) Mix the graphene oxide slurry with water and tert-butyl alcohol and stir to prepare a graphene oxide slurry with a concentration of 8 mg / g. Add barium titanate nanoparticles to the 10 mg / g graphene oxide slurry at a mass ratio of 1:1 and stir to mix thoroughly.

[0041] 2) Pour the composite slurry into a mold with good thermal conductivity and scrape it flat.

[0042] 3) The layered slurry and the mold are frozen with liquid nitrogen. The freezing time is controlled by a temperature control valve. The pre-freezing temperature is -50°C and the pre-freezing time is 1 hour.

[0043] 4) Demolding the frozen block, and then drying it using a freeze-drying process.

[0044] 5) The plate dried in step 4) is placed in a blast drying oven, and then subjected to reduction treatment with hydrazine hydrate. The mass ratio of graphene oxide to hydrazine hydrate is 1:1, the reduction temperature is 90° C., and the reduction time is 24 hours.

[0045] 6) The ratio of the flexible polymer was 10:1:1 for PDMS: curing agent: n-hexane, stirred at 1000 r / min for 2 min, and defoamed at -0.1 MPa vacuum for 5 min.

[0046] 7) The BaTiO3 / graphene aerogel obtained in step 5) is placed into the cured resin obtained in step 6), and the vacuum infusion process is repeated 5 times at intervals of 20 minutes.

[0047] 8) Take out the composite in step 7) and cure it at 65° C. for 4 h.

[0048] Experimental example

[0049] The electromagnetic wave absorption performance of the flexible BaTiO3 / graphene / PDMS composite material prepared in Example 2 was tested.

[0050] The test method is to use Agilent N5244A vector network analyzer to test the absorbing performance of the graphene composite flexible absorbing plate obtained by the bow frame test method. The electromagnetic wave band is 1-18GHz. The test results are shown in Figure 3 ,Depend on Figure 3 It can be seen that the flexible BaTiO3 / graphene / PDMS composite material prepared by the present invention can improve the electromagnetic wave absorption performance of the material.

[0051] From the above examples, it can be seen that the present invention provides a flexible BaTiO3 / graphene / PDMS composite material, which uses flexible polymer vacuum infusion to give aerogel flexibility. The electromagnetic parameters of the composite material are adjusted by using barium titanate, and then its impedance matching characteristics are regulated, so that electromagnetic waves can enter the material more easily, and the electromagnetic waves are dissipated through multiple loss mechanisms to achieve better wave absorption performance.

[0052] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a flexible BaTiO3 / graphene / PDMS composite material, characterized in that: The following steps are involved: The high mass fraction graphene oxide slurry is diluted and dispersed, and appropriate amounts of deionized water and tert-butyl alcohol are added thereto, and the mixture is dispersed by ultrasonication and stirring at room temperature; barium titanate nanoparticles are added to the diluted graphene oxide slurry, and ultrasonic stirring is continued until uniform to obtain barium titanate / graphene oxide composite slurry; the composite slurry is poured into a mold with good thermal conductivity, pre-frozen and freeze-dried to obtain barium titanate / graphene oxide aerogel; the aerogel is reduced with hydrazine hydrate and dried in a vacuum drying oven to remove moisture and residual reducing agent to obtain BaTiO3 / graphene aerogel. Subsequently, the BaTiO3 / graphene aerogel is vacuum-infused with a flexible polymer to obtain a flexible BaTiO3 / graphene / PDMS composite material.

2. The method for preparing the flexible BaTiO3 / graphene / PDMS composite material according to claim 1, characterized in that: The concentration of the graphene oxide slurry is 1-18 mg / g.

3. The method for preparing the flexible BaTiO3 / graphene / PDMS composite material according to claim 1, characterized in that: The mass ratio of the graphene oxide to the barium titanate nanoparticles is 1:1-1:

5.

4. The method for preparing the flexible BaTiO3 / graphene / PDMS composite material according to any one of claims 1 to 3, characterized in that: The method for composite graphene oxide with barium titanate comprises the following steps: firstly, the graphene oxide slurry is diluted to a concentration of 1-10 mg / mL using deionized water and tert-butyl alcohol, and then barium titanate nanoparticles are added to the dispersion in a mass ratio of 1:1-1:5 and stirred thoroughly for 4-8 hours.

5. The method for preparing the flexible BaTiO3 / graphene / PDMS composite material according to claim 1, characterized in that: The pre-freezing molding is to introduce liquid nitrogen into the mold, control the temperature through a temperature control valve, use a metal mold with good thermal conductivity to hold the slurry, the pre-freezing time is 1 hour, and the pre-freezing temperature is -50°C.

6. The method for preparing the flexible BaTiO3 / graphene / PDMS composite material according to claim 1, characterized in that: The freeze-drying treatment time is 5 days.

7. The method for preparing the flexible BaTiO3 / graphene / PDMS composite material according to claim 1, characterized in that: The reduction adopts a hydrazine hydrate steam reduction method, and the mass ratio of graphene oxide to hydrazine hydrate is 1:1-1:3.

5.

8. The method for preparing the flexible BaTiO3 / graphene / PDMS composite material according to claim 1, characterized in that: The ratio of the flexible polymer is PDMS: curing agent: n-hexane is 10:1:1-10:1:

5.

9. The method for preparing the flexible BaTiO3 / graphene / PDMS composite material according to any one of claims 1 to 5, characterized in that: The method of vacuum infusing a flexible polymer into a BaTiO3 / graphene aerogel comprises the following steps: preparing a uniformly mixed solution of PDMS, a curing agent, and n-hexane and vacuum defoaming the mixture. The BaTiO3 / graphene aerogel is pressed into an uncured polymer and vacuum infused to a maximum filling amount. The flexible BaTiO3 / graphene / PDMS composite material is then cured at 55-70°C.

10. A flexible BaTiO3 / graphene / PDMS composite material prepared by the preparation method of the flexible BaTiO3 / graphene / PDMS composite material as claimed in any one of claims 1 to 9.

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