Heavy metal boron-based carbon nanofiber flexible thin film as well as preparation method and application thereof

Abstract

The invention provides a heavy metal boron-based carbon nanofiber flexible thin film as well as a preparation method and application thereof, and relates to the technical field of protective materials. The preparation method of the heavy metal boron-based carbon nanofiber flexible film comprises the following steps: mixing a polymer, a boron-containing compound, a heavy metal salt and a solvent to obtain a polymer precursor solution; performing electrostatic spinning on the polymer precursor solution to obtain a heavy metal boron-based polymer nanofiber membrane; sequentially carrying out drying and first calcination on the heavy metal boron-based polymer nanofiber membrane to obtain a pre-stabilized heavy metal boron-based polymer nanofiber membrane; the pre-stabilized heavy metal boron-based polymer nanofiber membrane is subjected to second calcination, and the heavy metal boron-based carbon nanofiber flexible membrane is obtained. The heavy metal boron-based carbon nanofiber flexible thin film prepared by the invention has breathable and tensile properties, and can effectively protect nucleation.

Description

Technical Field

[0001] The present invention relates to the technical field of protective materials, and particularly relates to a heavy metal boron-based carbon nanofiber flexible film, a preparation method thereof, and an application thereof. Background Art

[0002] Nuclear radiation, biological and chemical protection are issues that must be taken seriously in modern society. With the development of technology and the advancement of industrialization, the risk of people being exposed to radiation and chemical substances is also increasing. Currently, the use of radiation facilities is constantly increasing, especially in the medical field, where it is inevitable to use radiation for diagnosis and treatment. In positron emission tomography (PET), the positrons emitted annihilate with electrons and generate gamma-ray photons; fast neutron therapy involves the use of fast neutrons in cancer treatment; proton beam therapy involves the use of protons; and hadron beam therapy involves protons and heavy charged ions. There are many applications of radiation, but excessive radiation doses can have very serious long-term effects on human health. At the same time, society is also facing many biological and chemical threats, such as some pathogens, bacteria, viruses, chemical agents, etc. Therefore, nuclear, biological, and chemical protection technology is one of the important challenges faced by today's society and has become the most important research field.

[0003] In nuclear, biological, and chemical protection, protective clothing is one of the important measures to protect workers from nuclear radiation, bacteria, toxic chemicals, etc. The irreplaceability of protective clothing lies in its ability to effectively prevent the spread and intrusion of nuclear radiation, microorganisms, and chemical agents, thus ensuring the safety of workers. Currently, the application of protective clothing in nuclear, biological, and chemical protection has been widely recognized and widely used in various fields, such as medical and health, environmental protection, etc. However, the current protective clothing technology needs to be innovated because, with the development of technology and social progress, people's requirements for protective clothing are also getting higher and higher. Traditional protective clothing fabrics are limited to single biochemical protection functions and single nuclear radiation protection functions, and can no longer meet the modern epidemic prevention and nuclear protection needs. More efficient, safe, and environmentally friendly protective clothing technology is needed to ensure people's health and safety. Therefore, future research should focus on the research of nuclear, biological, and chemical multifunctional protective clothing fabrics.

[0004] Lead is the most commonly used radiation protection material at present. It has a high density and a hard texture, and can block most radiation. It can shield gamma rays, but is ineffective against neutrons. Lead and its compounds are toxic to a certain extent, and long-term exposure will cause harm to multiple systems of the human body, such as the nervous system, hematopoiesis, digestion, kidneys, cardiovascular system, and endocrine system. Summary of the Invention

[0005] The purpose of the present invention is to provide a heavy metal boron-based carbon nanofiber flexible film, a preparation method thereof, and an application thereof. The heavy metal boron-based carbon nanofiber flexible film prepared by the present invention has air permeability and tensile resistance, and can effectively protect against nuclear, biological, and chemical agents.

[0006] To achieve the above-mentioned invention object, the present invention provides the following technical solutions:

[0007] The present invention provides a preparation method of a heavy metal boron-based carbon nanofiber flexible film, comprising the following steps:

[0008] Mix a polymer, a boron-containing compound, a heavy metal salt, and a solvent to obtain a polymer precursor solution;

[0009] Electrospin the polymer precursor solution to obtain a heavy metal boron-based polymer nanofiber membrane;

[0010] Dry and first calcine the heavy metal boron-based polymer nanofiber membrane in sequence to obtain a pre-stabilized heavy metal boron-based polymer nanofiber membrane; the temperature of the first calcination is 200-400°C; the time of the first calcination is 0.5-1.5 h;

[0011] Second-calcine the pre-stabilized heavy metal boron-based polymer nanofiber membrane to obtain a heavy metal boron-based carbon nanofiber flexible film; the temperature of the second calcination is 400-1500°C; the time of the second calcination is 0.5-2.5 h.

[0012] Preferably, the polymer includes one or more of polyvinylpyrrolidone, polyacrylonitrile, and polyvinyl alcohol;

[0013] The heavy metal salt includes one or more of bismuth-containing compounds and tungsten-based compounds;

[0014] The solvent includes one or more of ethanol, glacial acetic acid, acetone, and N,N-dimethylformamide.

[0015] Preferably, the mass of the polymer is 5-50% of the total mass of the polymer and the solvent; the mass ratio of boron element in the boron-containing compound, heavy metal element in the heavy metal salt, and the polymer is 1-10:5-30:75.

[0016] Preferably, the conditions of the electrospinning include: the ejection speed is 0.1-10 mL / h; the voltage is 12-22 kV; the distance between the nozzle tip and the receiving plate is 10-20 cm; the roller rotation speed is 100-300 r / min; the relative humidity is 30% ± 5%; the temperature is 23 ± 2°C.

[0017] Preferably, the temperature of the drying is 50-100°C; the time of the drying is 4-12 h.

[0018] Preferably, the first calcination is carried out in an air atmosphere.

[0019] Preferably, the second calcination is carried out in a nitrogen atmosphere.

[0020] The present invention provides a heavy metal boron-based carbon nanofiber flexible film prepared by the preparation method described in the above technical solution, which includes heavy metal elements, boron elements and carbon fibers.

[0021] The present invention provides an application of the heavy metal boron-based carbon nanofiber flexible film described in the above technical solution in fabrics.

[0022] Preferably, the fabric includes a nuclear, biological and chemical protective clothing fabric.

[0023] The present invention provides a preparation method of a heavy metal boron-based carbon nanofiber flexible film. The present invention uses electrospinning to prepare a heavy metal boron-based carbon nanofiber flexible film with a nanoscale fiber morphology. The heavy metal boron-based carbon nanofiber flexible film prepared by the present invention has a nuclear radiation protection function due to the presence of B elements and other heavy metals (such as W, Bi, etc.); the carbon nanofibers prepared by electrospinning have small pore sizes and large surface areas, showing a high adsorption capacity for organic substances; the carbon nanofiber flexible film has characteristics such as high aerosol filtration efficiency, low surface density, and small pressure drop, and can also block large-sized bacteria, viruses and other microorganisms, ensuring that small molecules such as water vapor can pass through quickly to achieve high air permeability; in addition, the heavy metal oxides on the flexible film have the ability to degrade chemical agents. The heavy metal boron-based carbon nanofiber flexible film prepared by the present invention has multiple functions such as nuclear radiation protection, chemical protection and large-sized biological bacteria protection, and has good application prospects; moreover, the preparation method described in the present invention does not require special equipment and harsh conditions, has a simple process, strong controllability, and is easy to realize large-scale production, and has practicability.

[0024] The present invention provides a preparation method of a heavy metal boron-based carbon nanofiber flexible film that is simple, fast and highly controllable. The heavy metal boron-based carbon nanofiber flexible film obtained by the method of the present invention can be used for the fabric of nuclear, biological and chemical protective clothing. Description of the Drawings

[0025] Figure 1 Photograph of the electrospun heavy metal (Bi / W) boron-based polymer nanofiber film obtained in Comparative Example 1;

[0026] Figure 2 Photograph of the pre-stabilized electrospun heavy metal (Bi / W) boron-based polymer nanofiber film obtained in Comparative Example 1;

[0027] Figure 3 Photograph of the heavy metal (Bi / W) boron-based carbon nanofiber brittle film obtained in Comparative Example 1;

[0028] Figure 4 Photograph of the heavy metal (Bi / W) boron-based carbon nanofiber flexible film obtained in Example 1;

[0029] Figure 5 Folded photo of the heavy metal (Bi / W) boron-based carbon nanofiber flexible film obtained in Example 1;

[0030] Figure 6 Photo of the heavy metal (Bi / W) carbon nanofiber brittle film obtained in Comparative Example 2;

[0031] Figure 7 Photo of the heavy metal (Bi) boron-based carbon nanofiber flexible film obtained in Example 2. Detailed implementation manners

[0032] The present invention provides a method for preparing a heavy metal boron-based carbon nanofiber flexible film, comprising the following steps:

[0033] Mix a polymer, a boron-containing compound, a heavy metal salt and a solvent to obtain a polymer precursor solution;

[0034] Perform electrospinning on the polymer precursor solution to obtain a heavy metal boron-based polymer nanofiber membrane;

[0035] Dry and perform a first calcination on the heavy metal boron-based polymer nanofiber membrane in sequence to obtain a pre-stabilized heavy metal boron-based polymer nanofiber membrane; the temperature of the first calcination is 200-400°C; the time of the first calcination is 0.5-1.5 h;

[0036] Perform a second calcination on the pre-stabilized heavy metal boron-based polymer nanofiber membrane to obtain a heavy metal boron-based carbon nanofiber flexible film; the temperature of the second calcination is 400-1500°C; the time of the second calcination is 0.5-2.5 h.

[0037] In the present invention, a polymer, a boron-containing compound, a heavy metal salt and a solvent are mixed to obtain a polymer precursor solution. In the present invention, the polymer preferably includes one or more of polyvinylpyrrolidone (PVP), polyacrylonitrile (PAN) and polyvinyl alcohol (PVA). In a specific embodiment of the present invention, the molecular weight Mw of the PVP is 1300000; the molecular weight Mw of the PAN is 150000; the molecular weight Mw of the PVA is 67000.

[0038] In the present invention, the boron-containing compound preferably includes one or more of boric acid, boron-10 acid and soluble boron-containing drugs. In the present invention, the soluble boron-containing drugs preferably include one or more of bortezomib, ixazomib, tavaborole and crisaborole.

[0039] In the present invention, the heavy metal salt preferably includes one or several of bismuth-containing compounds and tungsten compounds; the bismuth-containing compounds preferably include one or several of bismuth citrate, bismuth chloride, bismuth nitrate, bismuth acetylacetonate, and potassium bismuth citrate; the tungsten compounds preferably include one or more of sodium tungstate, tungsten chloride, and phosphotungstic acid. In the present invention, bismuth and tungsten provide good gamma-ray shielding ability due to their high atomic numbers, and boron has good neutron shielding ability because of the high neutron absorption cross-section of boron-10 element and does not emit gamma rays. All three are non-toxic alternatives to lead.

[0040] In the present invention, the solvent preferably includes one or several of ethanol, glacial acetic acid, acetone, and N,N-dimethylformamide.

[0041] In the present invention, the mass of the polymer is preferably 5-50% of the total mass of the polymer and the solvent, more preferably 10-30%; the mass ratio of boron element in the boron-containing compound, heavy metal element in the heavy metal salt, and the polymer is preferably 1-10:5-30:75, more preferably 5:10-20:75; when the heavy metal salt includes bismuth-containing compounds and tungsten compounds, the mass ratio of bismuth and tungsten is preferably 1:1.

[0042] In the present invention, the mixing of the polymer, boron-containing compound, heavy metal salt, and solvent preferably includes: dissolving the polymer in the solvent, adding the boron-containing compound and the heavy metal salt, and stirring. In the present invention, the temperature of the stirring is preferably 30-60°C; the time of the stirring is preferably 4-12 h.

[0043] After obtaining the polymer precursor solution, the present invention electrospins the polymer precursor solution to obtain a heavy metal boron-based polymer nanofiber membrane. The present invention preferably fills the polymer precursor solution into a syringe, sets the conditions of electrospinning and applies high voltage to perform electrospinning.

[0044] In the present invention, the conditions of electrospinning preferably include: the ejection speed is 0.1-10 mL / h; the voltage is 12-22 kV; the distance between the nozzle tip and the receiving plate is 10-20 cm; the roller rotation speed is 100-300 r / min; the relative humidity is 30% ± 5%; the temperature is 23 ± 2°C. In the present invention, the conditions of electrospinning are more preferably: the ejection speed is 1.5-8 mL / h; the voltage is 15-18 kV; the distance between the nozzle tip and the receiving plate is 15-18 cm; the roller rotation speed is 150-200 r / min; the relative humidity is 35%; the temperature is 25°C.

[0045] In the present invention, the supporting carrier used for electrospinning is preferably non-woven fabric.

[0046] After obtaining the heavy metal boride-based polymer nanofiber membrane, the present invention sequentially dries and first calcines the heavy metal boride-based polymer nanofiber membrane to obtain a pre-stabilized heavy metal boride-based polymer nanofiber membrane. In the present invention, the temperature of the drying is preferably 50-100°C, more preferably 60-80°C; the time of the drying is preferably 4-12 h, more preferably 6-10 h. In the present invention, the temperature of the first calcination is 200-400°C, preferably 250-300°C; the time of the first calcination is 0.5-1.5 h, preferably 0.5-1 h; the first calcination is preferably carried out in an air atmosphere. In the present invention, the first calcination is preferably carried out in a muffle furnace. In the present invention, the function of the first calcination is to pre-stabilize the obtained heavy metal boride-based polymer nanofiber membrane so as to form a flexible film by subsequent second calcination.

[0047] After obtaining the pre-stabilized heavy metal boride-based polymer nanofiber membrane, the present invention second calcines the pre-stabilized heavy metal boride-based polymer nanofiber membrane to obtain a flexible heavy metal boride-based carbon nanofiber film. In the present invention, the temperature of the second calcination is 400-1500°C, more preferably 650-1000°C; the time of the second calcination is 0.5-2.5 h, more preferably 0.5-2 h; the second calcination is preferably carried out in a nitrogen atmosphere. In the present invention, the second calcination is preferably carried out in a tube furnace. In the present invention, the function of the second calcination is to calcine the obtained pre-stabilized heavy metal boride-based polymer nanofiber membrane to form a flexible heavy metal boride-based carbon nanofiber film.

[0048] The present invention provides a flexible heavy metal boride-based carbon nanofiber film prepared by the preparation method described in the above technical solution, which includes a heavy metal element, a boron element and a carbon fiber. In the present invention, the heavy metal element preferably includes one or more of bismuth and tungsten.

[0049] The present invention provides an application of the flexible heavy metal boride-based carbon nanofiber film described in the above technical solution in a fabric. In the present invention, the fabric preferably includes a nuclear, biological and chemical protective clothing fabric. In a specific embodiment of the present invention, the flexible heavy metal boride-based carbon nanofiber film is preferably used as an interlayer fabric of a nuclear, biological and chemical protective clothing.

[0050] In the present invention, carbon fiber, as a new type of fibrous material, has excellent properties such as light weight, high strength, high modulus, and corrosion resistance, providing new possibilities for technological innovation in the field of biochemical protection. It is lighter and stronger than traditional protective materials, which helps improve the comfort and flexibility of protective equipment and reduces the burden on users; it has excellent corrosion resistance and can maintain stability in harsh environments, extending the service life of biochemical protective equipment; in addition, the conductivity of carbon fiber enables it to integrate intelligent sensing technology, enhancing the intelligent level of biochemical protective equipment and providing real-time monitoring and feedback functions. With the continuous development of carbon fiber technology, its application potential in the field of biochemical protection will be further expanded. In the future, it may be possible to achieve the multifunctionalization of biochemical protective equipment and expand its scope of application through functional improvement of carbon fiber.

[0051] Based on the fact that the flexible film of heavy metal boron-based carbon nanofibers in the present invention is lightweight, it can be used as the sandwich fabric of nuclear, biological, and chemical protective clothing, which opens up new possibilities for the development of advanced systems capable of guarding against nuclear radiation, chemical, and biological threats. Therefore, the preparation of the novel fabric of the flexible film of heavy metal boron-based carbon nanofibers in the present invention not only has high scientific value but also has practical significance for nuclear, biological, and chemical protection.

[0052] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without making creative efforts shall fall within the scope of protection of the present invention.

[0053] Comparative Example 1

[0054] (1) Dissolve 1 g of polymer PVP (Mw = 1300000) in 10 mL of solvent ethanol, and add boric acid, bismuth citrate, and tungsten chloride in a certain mass fraction ratio (B:Bi:W:PVP = 5%:10%:10%:75%) during this period. After stirring at room temperature for 12 h, a homogeneous and transparent polymer precursor solution is formed;

[0055] (2) Load the above 10 mL of polymer precursor solution into a 10 mL syringe, place it in an electrospinning machine, with the positive voltage for electrospinning being 18 kV applied to the tip of the nozzle, the distance between the tip of the nozzle and the receiving plate being 15 cm, the spraying speed being 1.5 mL / h, the roller rotation speed being 150 r / min, the temperature being 25 °C, and the relative humidity being 35%; using non-woven fabric as the supporting carrier, electrospinning is carried out to prepare a heavy metal (Bi / W) boron-based polymer nanofiber membrane, as Figure 1 shown;

[0056] (3) Dry the heavy metal (Bi / W) borate-based polymer nanofiber membrane at 60 °C for 6 h, and calcine it at 250 °C for 2 h in a muffle furnace to obtain a pre-stabilized heavy metal (Bi / W) borate-based polymer nanofiber membrane, as Figure 2 shown;

[0057] (4) Calcinate the pre-stabilized heavy metal (Bi / W) borate-based polymer nanofiber membrane at 650 °C for 3 h in a nitrogen atmosphere in a tube furnace to obtain a brittle thin film of heavy metal (Bi / W) borate-based carbon nanofibers, as Figure 3 shown.

[0058] It is known through detection and analysis that what is obtained in Comparative Example 1 is a brittle thin film of heavy metal (Bi / W) borate-based carbon nanofibers. The PVP nanofiber membrane forms carbon nanofibers after calcination in an N2 atmosphere. Among them, Bi, W, and B elements are firmly coated in the carbon fibers, having a good protection effect against nuclear, biological, and chemical agents. The membrane is brittle and has poor tensile resistance.

[0059] Example 1

[0060] The difference between this example and Comparative Example 1 is only that: dry the heavy metal (Bi / W) borate-based polymer nanofiber membrane prepared in step (2) at 60 °C for 6 h, and calcine it at 250 °C for 1 h in a muffle furnace to obtain a pre-stabilized heavy metal (Bi / W) borate-based polymer nanofiber membrane; calcinate the pre-stabilized heavy metal (Bi / W) borate-based polymer nanofiber membrane at 650 °C for 2 h in a nitrogen atmosphere in a tube furnace to obtain a flexible thin film of heavy metal (Bi / W) borate-based carbon nanofibers, as Figure 4 and Figure 5 shown; where the mass fraction ratio of each substance is B:Bi:W:PVP = 5%:10%:10%:75%;

[0061] The rest of the content is exactly the same as that described in Comparative Example 1.

[0062] It is known through detection and analysis that what is obtained in Example 1 is a flexible thin film of heavy metal (Bi / W) borate-based carbon nanofibers. Compared with the membrane obtained in Comparative Example 1, it is more flexible and has a certain tensile resistance. Among them, Bi, W, and B elements are firmly coated in the carbon fibers, having a better protection effect against nuclear, biological, and chemical agents.

[0063] Comparative Example 2

[0064] The difference between this example and Comparative Example 1 is only that: boric acid is not added in step (1); the heavy metal (Bi / W) polymer nanofiber membrane prepared in step (2) is dried at 60 °C for 6 h and calcined at 250 °C for 1 h in a muffle furnace to obtain a pre-stabilized heavy metal (Bi / W) polymer nanofiber membrane; the pre-stabilized heavy metal (Bi / W) polymer nanofiber membrane is calcined at 650 °C for 2 h in a nitrogen atmosphere in a tube furnace to obtain a brittle heavy metal (Bi / W) carbon nanofiber thin film, as Figure 6 shown; where the mass fraction ratio of each substance is Bi: W: PVP = 10%: 10%: 80%;

[0065] The rest of the content is exactly the same as that described in Comparative Example 1.

[0066] It is known through detection and analysis that: what is obtained in Comparative Example 2 is a brittle heavy metal (Bi / W) carbon nanofiber thin film. Due to the non-addition of boric acid, compared with the thin film obtained in Example 1, the film is brittle and has poor tensile resistance. Among them, Bi and W elements are firmly coated in the carbon fiber, having a good protection effect against nuclear, biological and chemical agents.

[0067] Example 2

[0068] The difference between this example and Comparative Example 1 is only that: tungsten chloride is not added in step (1), and the amount of bismuth citrate added is doubled; the heavy metal (Bi) boron-based polymer nanofiber membrane prepared in step (2) is dried at 60 °C for 6 h and calcined at 250 °C for 1 h in a muffle furnace to obtain a pre-stabilized heavy metal (Bi) boron-based polymer nanofiber membrane; the pre-stabilized heavy metal (Bi) boron-based polymer nanofiber membrane is calcined at 650 °C for 2 h in a nitrogen atmosphere in a tube furnace to obtain a flexible heavy metal (Bi) boron-based carbon nanofiber thin film; as Figure 7 shown; where the mass fraction ratio of each substance is B: Bi: PVP = 5%: 20%: 75%;

[0069] The rest of the content is exactly the same as that described in Comparative Example 1.

[0070] It is known through detection and analysis that: what is obtained in Example 2 is a flexible heavy metal (Bi) boron-based carbon nanofiber thin film. Due to the addition of boric acid, compared with the thin film obtained in Comparative Example 2, the film is more flexible and has a certain tensile resistance. Among them, Bi element is firmly coated in the carbon fiber, having a better protection effect against nuclear, biological and chemical agents.

[0071] Comparative Example 3

[0072] According to the method in "A Medical Radiation Shielding Ray Protective Clothing (CN 104021832 A)", using TPO (thermoplastic polyolefin elastomer) as the base, a certain proportion of shielding substances is added for batching. Among them, the weight percentages of TPO: boron element in boron nitride: lead: tungsten are 70%: 10%: 10%: 10%. Through mixing, crushing granulation, and extrusion processes, a (Pb WB) / TPO elastomer flexible composite radiation shielding material is made for the fabric of medical radiation protective clothing.

[0073] Compared with the extrusion molding synthesis method used in Comparative Example 3, the method of the present invention uses electrospinning technology to synthesize a flexible film, and the distribution of composite shielding metal Bi, W, and non-metal B elements is more uniform. In Examples 1-2, the nuclear radiation shielding performances of the two heavy metal boron-based carbon nanofiber flexible films obtained by the present invention are both higher than those of the lead tungsten boron-based composite material obtained in Comparative Example 3. The specific performances are shown in Table 3.

[0074] Table 1: Nuclear Radiation Dose Rate Shielding Performances of Carbon Nanofiber Films Prepared in Examples 1-2 and Comparative Examples 1-2

[0075]

[0076] Table 2: Chemical Anti-Permeation Time (BT) of Carbon Nanofiber Films Prepared in Examples 1-2 and Comparative Examples 1-2

[0077]

[0078]

[0079] Table 3: Comparison of Nuclear Radiation Shielding Performances in Examples 1-2 and Comparative Example 3

[0080]

[0081] 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 be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for preparing a heavy metal boron-based carbon nanofiber flexible film, comprising the following steps: Mix a polymer, a boron-containing compound, a heavy metal salt, and a solvent to obtain a polymer precursor solution; Perform electrospinning on the polymer precursor solution to obtain a heavy metal boron-based polymer nanofiber membrane; Successively dry and first calcine the heavy metal boron-based polymer nanofiber membrane to obtain a pre-stabilized heavy metal boron-based polymer nanofiber membrane; the temperature of the first calcination is 200-400 °C; the time of the first calcination is 0.5-1.5 h; Perform second calcination on the pre-stabilized heavy metal boron-based polymer nanofiber membrane to obtain a heavy metal boron-based carbon nanofiber flexible film; the temperature of the second calcination is 400-1500 °C; the time of the second calcination is 0.5-2.5 h.

2. The preparation method according to claim 1, characterized in that, The polymer includes one or more of polyvinylpyrrolidone, polyacrylonitrile, and polyvinyl alcohol; The heavy metal salt includes one or more of bismuth-containing compounds and tungsten-based compounds; The solvent includes one or more of ethanol, glacial acetic acid, acetone, and N,N-dimethylformamide.

3. The preparation method according to claim 1 or 2, characterized in that, The mass of the polymer is 5-50% of the total mass of the polymer and the solvent; the mass ratio of boron element in the boron-containing compound, heavy metal element in the heavy metal salt, and the polymer is 1-10:5-30:

75.

4. The preparation method according to claim 1, characterized in that, The conditions for the electrospinning include: the ejection speed is 0.1-10 mL / h; the voltage is 12-22 kV; the distance between the nozzle tip and the receiving plate is 10-20 cm; the roller rotation speed is 100-300 r / min; the relative humidity is 30% ± 5%; the temperature is 23 ± 2 °C.

5. The preparation method according to claim 1, characterized in that, The temperature of the drying is 50-100 °C; the time of the drying is 4-12 h.

6. The preparation method according to claim 1, wherein, The first calcination is carried out in an air atmosphere.

7. The preparation method according to claim 1, wherein, The second calcination is carried out in a nitrogen atmosphere.

8. The heavy metal boron-based carbon nanofiber flexible film prepared by the preparation method according to any one of claims 1-7, comprising a heavy metal element, a boron element, and carbon fibers.

9. The application of the heavy metal boron-based carbon nanofiber flexible film according to claim 8 in a fabric.

10. The application according to claim 9, wherein, The fabric includes a nuclear, biological, and chemical protective clothing fabric.

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