阅读说明：本技术 一种自愈合石墨烯隐身薄膜及其制备方法 (self-healing graphene stealth film and preparation method thereof ) 是由 谭琳 冯辉霞 张根旺 康虎 李潇阳 陈娜丽 赵丹 徐阳 于 2019-08-26 设计创作，主要内容包括：本发明涉及一种自愈合石墨烯隐身薄膜的制备方法,包括如下步骤：⑴将含硫还原剂加入氧化石墨溶液,加热反应后得到胶状液体；⑵胶状液体经冷却、洗涤过滤、冷冻干燥得硫掺杂石墨烯粉末；⑶硫掺杂石墨烯粉末中加入去离子水,离心分离后得上清液；⑷在聚乙烯醇中依次加入上清液、去离子水,搅拌溶解后形成混合液,加入增塑剂制成聚乙烯醇铸膜液；⑸聚乙烯醇/硫掺杂石墨烯铸膜液经加热制成铸膜液,倒在器皿上自然干燥,得自愈合石墨烯隐身薄膜。本发明所制备的硫掺杂石墨烯基隐身材料与其他杂原子掺杂石墨烯材料相比,具有更强的隐身特性且波段可调；且本发明制备过程简单易行、反应条件温和,有利于隐身材料连续化和规模化生产的实现。(the invention relates to a preparation method of a self-healing graphene stealth film, which comprises the following steps: the preparation method comprises the steps of adding a sulfur-containing reducing agent into a graphite oxide solution, and heating for reaction to obtain colloidal liquid; cooling, washing, filtering and freeze-drying the colloidal liquid to obtain sulfur-doped graphene powder; adding deionized water into the sulfur-doped graphene powder, and performing centrifugal separation to obtain a supernatant; sequentially adding supernatant and deionized water into polyvinyl alcohol, stirring and dissolving to form a mixed solution, and adding a plasticizer to prepare a polyvinyl alcohol casting solution; and heating the polyvinyl alcohol/sulfur doped graphene casting solution to prepare a casting solution, pouring the casting solution on a utensil, and naturally drying to obtain the healed graphene stealth film. Compared with other heteroatom-doped graphene materials, the sulfur-doped graphene-based stealth material prepared by the invention has stronger stealth characteristic and adjustable wave band; the preparation process is simple and easy to implement, the reaction conditions are mild, and the method is favorable for realizing the continuous and large-scale production of the stealth material.)

1. a preparation method of a self-healing graphene stealth film is characterized by comprising the following steps: the method comprises the following steps:

the preparation method comprises the steps of adding a sulfur ~ containing reducing agent into a graphite oxide solution, heating to 80 ~ 100 ℃, and carrying out continuous constant thermal reaction for 1 ~ 3 hours to obtain black colloidal liquid after the reaction is finished;

Cooling the black colloidal liquid to room temperature, washing and filtering the black colloidal liquid for multiple times by deionized water, and freeze-drying the black colloidal liquid to obtain black sulfur-doped graphene powder;

adding deionized water into the sulfur ~ doped graphene powder to obtain a dispersion liquid with the concentration of 2 ~ 5mg/mL, and performing centrifugal separation on the dispersion liquid to obtain a supernatant;

Sequentially adding the supernatant and deionized water into polyvinyl alcohol, stirring and dissolving at normal temperature to form a mixed solution, adding a plasticizer into the mixed solution, and uniformly stirring to prepare a polyvinyl alcohol casting solution;

and fifthly, heating the polyvinyl alcohol/sulfur ~ doped graphene casting solution in a water bath at 80 ~ 100 ℃ for 10 ~ 30min to prepare a casting solution with uniformly mixed polyvinyl alcohol completely dissolved, quickly taking out the casting solution, quickly pouring the casting solution onto a steel sheet or a culture dish, and naturally drying to obtain the self ~ healing graphene stealth film.

2. the method for preparing a self-healing graphene stealth film according to claim 1, characterized in that: the sulfur-containing reducing agent in the step is one of sodium bisulfate, thioglycolic acid, 3-mercaptopropionic acid and sodium sulfide.

3. the method for preparing the self ~ healing graphene stealth film according to claim 1, characterized in that the ratio of the sulfur ~ containing reducing agent to the graphite oxide solution in the step of making is (1.6 ~ 4.0) g (50 ~ 200) mL.

4. the preparation method of the self ~ healing graphene stealth film according to claim 1, characterized in that the number of washing times with deionized water in the second step is 6 ~ 10.

5. The method for preparing a self-healing graphene stealth film according to claim 1, characterized in that: the step of freeze-drying in the second step is carried out at the temperature of minus 50 ℃ and the pressure of 0.1 atm.

6. The method for preparing a self-healing graphene stealth film according to claim 1, characterized in that: and the step three of centrifugal separation refers to that the rotating speed is 4000 revolutions per minute, the centrifugation is carried out for five minutes, and the supernatant is taken.

7. the preparation method of the self ~ healing graphene stealth film according to claim 1, characterized in that in the step four, the ratio of polyvinyl alcohol to the supernatant is (5.0 ~ 25.0) g (2 ~ 5) mL, and the ratio of polyvinyl alcohol to the deionized water is (5.0 ~ 25.0) g (20 ~ 100) mL.

8. The method for preparing a self-healing graphene stealth film according to claim 1, characterized in that: the plasticizer in the step four is one of polyvinylpyrrolidone, boric acid, metanilic acid, glycerol and ethylene glycol.

9. the preparation method of the self% ~ healing graphene stealth film according to claim 7, wherein the addition amount of the plasticizer in the step four is 5% ~ 50% of the mass of the mixed solution.

10. the self-healing graphene stealth film prepared by the preparation method according ~ any one of claims 1 ~ 9 is characterized in that the mass of the sulfur-doped graphene cast film material in the self-healing graphene stealth film accounts for 30-70% of the sum of the mass of the sulfur-doped graphene cast film material and the mass of the polyvinyl alcohol composite.

Technical Field

The invention relates to the technical field of electromagnetic wave absorption materials, in particular to a preparation method of a self-healing graphene stealth film.

Background

At present, radar stealth materials capable of efficiently absorbing electromagnetic waves become the most valuable tactical defense means in modern wars.

The existing invisible machine is commonly used with a hydroxy ferrite wave-absorbing coating, and the weight of the coating is 8-16kg/m²In order to ensure the effect, the body is coated with several layers, which brings about an additional weight to the fighter. In addition, the coating is easy to peel off by air current scouring in the flying process, and the coating needs to be sprayed again for a plurality of flights.

Graphene is a two-dimensional material with a thickness of only one carbon atom, which is discovered so far, and is also a nanometer two-dimensional material with the thinnest thickness and the largest strength, and is widely applied to various fields due to excellent mechanical property, electrical conductivity, thermal conductivity, flexibility, stability, elasticity and strong acid and alkali resistance. However, the conventional graphene film preparation process is complicated, the requirement on reaction conditions is high, high-temperature annealing is mostly adopted in the preparation intermediate process, the energy consumption is high, the stealth and self-healing functions are avoided, and the graphene film preparation method cannot be used in fields with strong concealment such as military affairs.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a preparation method of a self-healing graphene stealth film, which is low in cost, simple, convenient and fast, and low in energy consumption.

The technical scheme for realizing the purpose of the invention is as follows: a preparation method of a self-healing graphene stealth film is characterized by comprising the following steps: the method comprises the following steps:

the preparation method comprises the steps of adding a sulfur ~ containing reducing agent into a graphite oxide solution, heating to 80 ~ 100 ℃, and carrying out continuous constant thermal reaction for 1 ~ 3 hours to obtain black colloidal liquid after the reaction is finished;

Cooling the black colloidal liquid to room temperature, washing and filtering the black colloidal liquid for multiple times by deionized water, and freeze-drying the black colloidal liquid to obtain black sulfur-doped graphene powder;

adding deionized water into the sulfur ~ doped graphene powder to obtain a dispersion liquid with the concentration of 2 ~ 5mg/mL, and performing centrifugal separation on the dispersion liquid to obtain a supernatant;

Sequentially adding the supernatant and deionized water into polyvinyl alcohol, stirring and dissolving at normal temperature to form a mixed solution, adding a plasticizer into the mixed solution, and uniformly stirring to prepare a polyvinyl alcohol casting solution;

and fifthly, heating the polyvinyl alcohol/sulfur ~ doped graphene casting solution in a water bath at 80 ~ 100 ℃ for 10 ~ 30min to prepare a casting solution with uniformly mixed polyvinyl alcohol completely dissolved, quickly taking out the casting solution, quickly pouring the casting solution onto a steel sheet or a culture dish, and naturally drying to obtain the self ~ healing graphene stealth film.

In the technical scheme, the sulfur-containing reducing agent in the step is one of sodium bisulfate, thioglycolic acid, 3-mercaptopropionic acid and sodium sulfide.

in the technical scheme, the ratio of the sulfur ~ containing reducing agent to the graphite oxide solution in the step is (1.6 ~ 4.0) g, (50 ~ 200) mL.

above-mentioned technical scheme, the step adopts the deionized water washing number of times to be 6 ~ 10 times in the second.

In the technical scheme, the freeze drying is carried out at the temperature of minus 50 ℃ and the pressure of 0.1 atm.

According to the technical scheme, the step three of centrifugal separation means that the rotating speed is 4000 revolutions per minute, the centrifugal separation is carried out for five minutes, and the supernatant is obtained.

according to the technical scheme, the ratio of the polyvinyl alcohol to the supernatant in the step four is (5.0 ~ 25.0) g (2 ~ 5) mL, and the ratio of the polyvinyl alcohol to the deionized water is (5.0 ~ 25.0) g (20 ~ 100) mL.

in the above technical solution, the plasticizer in the step four is one of polyvinylpyrrolidone, boric acid, metanilic acid, glycerol, and ethylene glycol.

according to the technical scheme, the adding amount of the plasticizer in the step four is 5% ~ 50% of the mass of the mixed liquid.

the self ~ healing graphene stealth film comprises 30% ~ 70% of sulfur ~ doped graphene cast film materials and polyvinyl alcohol composite materials, wherein the mass of the sulfur ~ doped graphene cast film materials accounts for the sum of the mass of the sulfur ~ doped graphene cast film materials and the mass of the polyvinyl alcohol composite materials.

After the technical scheme is adopted, the invention has the following positive effects:

(1) compared with other heteroatom-doped graphene materials and most of graphene-based composite materials, the sulfur-doped graphene-based stealth material prepared by the invention has stronger stealth characteristics and adjustable wave band; the preparation process is simple and easy to implement, the reaction conditions are mild, and the method is favorable for realizing the continuous and large-scale production of the stealth material;

(2) according to the preparation method, the sulfur ~ doped graphene stealth material is prepared by a chemical wet method, the reaction condition is changed from high ~ temperature annealing to low ~ temperature reaction, and the reaction can be carried out by heating in a water bath at the temperature of 80 ~ 100 ℃ for 10 ~ 30min, so that the reaction time is greatly shortened, the reaction temperature is reduced, the energy consumption is reduced, the reaction condition is mild, the preparation of the liquid ~ phase easily ~ processed film ~ forming material is realized while the energy consumption is greatly reduced, and the industrial large ~ scale production is facilitated.

(3) according to the preparation method, semiconductor type hybrid graphene is prepared through sulfur doping treatment on graphene, and fine adjustment of the dielectric property of the material is realized through regulating and controlling the concentration of a reducing agent, so that the aim of preparing the sulfur-doped graphene-based stealth material with adjustable stealth frequency band and stealth strength is fulfilled (see figure 2), and the problem that the preparation of a 'body tailoring' type stealth material cannot be realized according to the actual stealth requirement is solved.

(4) The trace sulfur doping is adopted, and the trace doping is beneficial to improving the wave absorbing performance of the graphene (the larger the sulfur doping amount is, the better the sulfur doping amount is); the prepared sulfur-doped graphene has excellent wave-absorbing performance of an adjustable frequency band as a single material, the reflection loss of a final product can even reach-51.8 dB, and the wave-absorbing strength even exceeds that of most graphene-based composite materials, so that the single material is compounded with other substances to obtain more excellent wave-absorbing characteristics;

(5) The sulfur-doped graphene film prepared by the invention has self-healing performance, and the sulfur-doped graphene film still has conductivity after self-healing, namely after mechanical abrasion, only water needs to be added, slightly pressed, applied with force and dried, the stealth film can be repaired and repeatedly applied, and meanwhile, the electrical and mechanical properties of the film are recovered;

(6) the invention can provide data storage and factual support for the conductive stealth material stealth mechanism research by establishing a database of quantitative relations among functional group types, structures, conductivity, dielectric constant and stealth characteristics; greatly broadens the selectable range of graphene-based components in the construction of the stealth composite material, and provides a new preparation idea for obtaining a composite structure with wider stealth frequency range and stronger absorption strength.

drawings

In order that the present disclosure may be more readily and clearly understood, reference is now made to the following detailed description of the present disclosure taken in conjunction with the accompanying drawings, in which

Fig. 1 shows the reflection loss of the sulfur-doped graphene/polyvinyl alcohol composite in example 1 of the present invention;

Fig. 2 shows the reflection loss of the sulfur-doped graphene/polyvinyl alcohol composite in example 2 of the present invention;

fig. 3 shows the reflection loss of the sulfur-doped graphene/polyvinyl alcohol composite in example 3 of the present invention;

Fig. 4 shows the reflection loss of the sulfur-doped graphene/polyvinyl alcohol composite in example 4 of the present invention;

fig. 5 shows the reflection loss of the sulfur-doped graphene/polyvinyl alcohol composite in example 5 of the present invention;

Fig. 6 shows the reflection loss of the sulfur-doped graphene/polyvinyl alcohol composite in example 6 of the present invention;

FIG. 7 shows the reflection loss of the sulfur-doped graphene/polyvinyl alcohol composite in the comparative example;

fig. 8 is a self-healing characteristic display diagram of the sulfur-doped graphene stealth film according to the present invention;

Fig. 9 is a schematic diagram of a mechanical tensile test result before a self-healing test of the sulfur-doped graphene stealth film according to the present invention;

Fig. 10 is a schematic diagram of a mechanical tensile test result of the sulfur-doped graphene stealth film material after shearing and self-healing;

Fig. 11 is a process diagram of a self-healing electrical recovery test result of the sulfur-doped graphene stealth film according to the present invention.

Detailed Description