Chiral electromagnetic shielding fabric and preparation method thereof

Abstract

The invention belongs to the field of electromagnetic shielding, and discloses a chiral electromagnetic shielding fabric and a preparation method thereof. The chiral electromagnetic shielding fabric comprises a fiber substrate and a shielding film layer, the shielding film layer is loaded on the fiber substrate, and the shielding film layer is made of a polymer film with a spiral structure on the surface. The invention provides a chiral electromagnetic shielding fabric which is characterized in that a shielding film layer is arranged on a fiber substrate, the shielding film layer is obtained by growing on the fiber surface through an in-situ growth method, a precursor is adsorbed on the surface of a chiral template through homopolymerization or copolymerization, and a polymer film with a spiral structure on the surface is prepared. The thin film with the single-hand spiral nanometer spiral structure on the surface is directly obtained on the fiber surface through an in-situ growth method, the structure is simple, fiber treatment is easy, preparation is convenient, and the electromagnetic shielding effect is good.

Description

Technical Field

[0001] This invention relates to the field of electromagnetic shielding technology, and in particular to a chiral electromagnetic shielding fabric and its preparation method. Background Technology

[0002] With the development of modern technology, various electromagnetic environments have become more complex. Electromagnetic interference (EMI) not only seriously threatens the stable operation of precision electronic equipment, but may also pose potential risks to information security and human health. Therefore, fabrics that can achieve electromagnetic shielding have also attracted people's attention.

[0003] In existing technologies, fabrics with electromagnetic shielding effects are often produced by weaving conductive fibers into the fabric or by depositing conductive particles on the surface of the fibers to improve the conductivity of the fabric, thereby achieving electromagnetic shielding. However, the preparation process of existing technologies is complex, the shielding effect is generally poor, and the fabric is difficult to meet processing requirements after treatment. In summary, existing technologies are not suitable for producing electromagnetic shielding fabrics. Summary of the Invention

[0004] The main objective of this invention is to provide a chiral electromagnetic shielding fabric and its preparation method, aiming to solve the problem that it is difficult to prepare electromagnetic shielding fabrics in the prior art.

[0005] To achieve the above objectives, the present invention provides a chiral electromagnetic shielding fabric, comprising: Fiber substrate; and, A shielding film layer is loaded on the fiber substrate, and the shielding film layer is made of a polymer film with a helical structure on its surface.

[0006] In one embodiment, the material of the fiber substrate includes one or more of cellulose fibers, protein fibers, polyester fibers, polyamide fibers, carbon cloth, and basalt.

[0007] This invention also provides a method for preparing a chiral electromagnetic shielding fabric, comprising the following steps: A chiral molecular template is dissolved in an organic solvent to obtain a transparent solution; The fiber substrate is immersed in the transparent solvent to allow the chiral molecules in the chiral molecular template to be uniformly adsorbed on the surface of the fiber. A polymer precursor is added to the transparent solution impregnated with the fiber substrate, causing the precursor to adsorb onto the surface of the chiral molecules, thereby preparing a polymer film with a helical structure on its surface.

[0008] In one embodiment, prior to the step of impregnating the fiber substrate in the transparent solvent to allow the chiral molecules in the chiral molecular template to be uniformly adsorbed on the surface of the fiber, the method further includes: The fiber substrate is subjected to surface modification treatment.

[0009] In one embodiment, the step of performing a surface modification treatment on the fiber substrate includes: The initial fibers are immersed in acid or alkali solutions; The initial fibers are heated and stirred in an acidic or alkaline solution to obtain the treated fibers. The treated fibers are then immersed in a neutralization process to obtain neutralized fibers. The neutralized fibers are rinsed with deionized water to obtain the fiber substrate.

[0010] In one embodiment, the step of performing a surface modification treatment on the fiber substrate includes: The original fibers are directly reacted without any treatment to obtain the fiber substrate.

[0011] In one embodiment, the chiral molecular template includes any one or more of the following: chiral cationic template, anionic template, electrically neutral chiral template, chiral surfactant, chiral organic ammonium, chiral metal ion center, and chiral ionic liquid cation.

[0012] In one embodiment, the polymer precursor includes any one or more of chiral polysilanes, chiral polymers, chiral MOFs, and chiral COFs.

[0013] In one embodiment, the organic solvent includes any one or more of methanol, ethanol, n-propanol, isopropanol, tetrahydrofuran, diethyl ether, ethyl acetate, acetonitrile, N-dimethylformamide, 1,4-dioxane, dimethyl sulfoxide, acetone, glycerol, ethylene glycol, pyridine, formic acid, and acetic acid.

[0014] This invention provides a chiral electromagnetic shielding fabric with a shielding film layer disposed on a fiber substrate. The shielding film layer is grown on the fiber surface by an in-situ growth method. The precursor is homopolymerized or copolymerized and adsorbed onto the surface of a chiral template to prepare a polymer film with a helical structure on the surface, resulting in a fabric with a chiral structure on the surface. When electrons pass through the chiral nanostructure, i.e., the helical molecules, the spin-orbit coupling and the chiral breaking of the structure work synergistically, leading to an asymmetric electron transport probability for different spin directions, achieving spin polarization. This film has a high electromagnetic shielding effect across the entire electromagnetic shielding band. The film with a single-handed helical nanostructure on the surface is obtained directly on the fiber surface by an in-situ growth method. The structure is simple, the fiber processing is simple, it is easy to prepare, and the electromagnetic shielding effect is good. Attached Figure Description

[0015] Figure 1 This is a microscopic image (scale bar is 100nm) of the spiral structure on the shielding film layer in this invention.

[0016] Figure 2 These are images of cotton fabric loaded with chiral material (black) and the original cotton fabric (white) from Embodiment 1 of the present invention.

[0017] Figure 3 This is an electromagnetic shielding test diagram of Embodiment 1 of the present invention in the 5.38-8.17 GHz band.

[0018] Figure 4 This is an electromagnetic shielding test diagram of Embodiment 1 of the present invention in the 8.2-12.4GHz band.

[0019] Figure 5 These are images of basalt loaded with chiral material (black) and the original image of basalt (brown) from Embodiment 2 of the present invention.

[0020] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indicators will also change accordingly.

[0023] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0024] The present invention provides a chiral electromagnetic shielding fabric, comprising a fiber substrate and a shielding film layer; the shielding film layer is loaded on the fiber substrate, and the material of the shielding film layer is a polymer film with a helical structure on its surface.

[0025] This invention provides a chiral electromagnetic shielding fabric with a shielding film layer disposed on a fiber substrate. The shielding film layer is grown on the fiber surface by an in-situ growth method. The precursor is homopolymerized or copolymerized and adsorbed onto the surface of a chiral template to prepare a polymer film with a helical structure on the surface, resulting in a fabric with a chiral structure on the surface. When electrons pass through the chiral nanostructure, i.e., the helical molecules, the spin-orbit coupling and the chiral breaking of the structure work synergistically, leading to an asymmetric electron transport probability for different spin directions, achieving spin polarization. This film has a high electromagnetic shielding effect across the entire electromagnetic shielding band. The film with a single-handed helical nanostructure on the surface is obtained directly on the fiber surface by an in-situ growth method. The structure is simple, the fiber processing is simple, it is easy to prepare, and the electromagnetic shielding effect is good.

[0026] Please see Figure 1 The chiral structure forms a three-dimensional conductive network, offering higher shielding effectiveness and a wider frequency band. Its strong flexibility and adaptability to deformation make it suitable for complex applications. The helical structure itself possesses natural elasticity and stretchability. When the fabric is subjected to stretching, bending, or torsion, the helical fibers can buffer stress through their own tightening / loosening, preventing the conductive layer from breaking or detaching. The helical fiber arrangement contains numerous micropores and gaps, resulting in lower fabric areal density and better breathability while maintaining the continuity of the conductive network. When the fabric is subjected to friction or repeated bending, the external force is dispersed across multiple helical fibers rather than concentrated in one area, reducing wear and detachment of the conductive layer.

[0027] Specifically, in this embodiment, the material of the fiber substrate includes one or more of cellulose fiber, protein fiber, polyester fiber, polyamide fiber, carbon cloth, and basalt.

[0028] On the other hand, in this embodiment, the thickness of the shielding film layer is 0.0001-5mm.

[0029] Based on the chiral electromagnetic shielding fabric described above, the present invention also provides a method for preparing the chiral electromagnetic shielding fabric, which is used to prepare the chiral electromagnetic shielding fabric described above, and therefore has all the technical features of the chiral electromagnetic shielding fabric described above.

[0030] The method for preparing the chiral electromagnetic shielding fabric includes the following steps: S10. Dissolve the chiral molecular template in an organic solvent to obtain a transparent solution; S20. The fiber substrate is added to the transparent solvent for impregnation, so that the chiral molecules in the chiral molecular template are uniformly adsorbed on the surface of the fiber. S30. Add a polymer precursor to the transparent solution impregnated with the fiber substrate, so that the precursor is adsorbed on the surface of the chiral molecules to prepare a polymer film with a helical structure on the surface.

[0031] This invention provides a method for preparing chiral electromagnetic shielding fabric. Using chiral molecules as templates, a polymer precursor is added to copolymerize on the fabric surface. The fabric is then adsorbed onto the fiber surface and grown in situ to prepare a thin film with a single-handed helical nanostructure on the surface. The preparation steps are simple and the application range is wide.

[0032] The electromagnetic shielding frequency range of this thin film is 100MHz-40GHz.

[0033] Furthermore, prior to step S20, the following steps are also included: S01. Surface modification treatment is performed on the fiber substrate.

[0034] In this embodiment, the surface of the fiber substrate is modified to facilitate the uniform adsorption of chiral molecules onto the surface of the fabric.

[0035] Furthermore, step S01 includes: S011. Immerse the initial fibers in an acidic or alkaline solution; S012. The initial fiber is heated and stirred in an acidic or alkaline solution to obtain the treated fiber. S013. The treated fibers are immersed in a neutralization treatment to obtain neutralized fibers; S014. Rinse the neutralized fibers with deionized water to obtain the fiber substrate.

[0036] It should be noted that the acid solution includes any one of sulfuric acid, hydrochloric acid, nitric acid, phosphoric acid, hydrofluoric acid, citric acid, acetic acid, lactic acid, malic acid, phosphoric acid, carbonic acid, boric acid, Lewis acid, p-toluenesulfonic acid, and salicylic acid.

[0037] The alkaline solution includes any one of sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, ammonia, hydrazine hydrate, sodium carbonate, sodium bicarbonate, and magnesium hydroxide.

[0038] In the process of immersing the initial fibers in the acid solution, the present invention provides the following specific embodiments: Completely immerse the dried fibers in a three-necked flask or polytetrafluoroethylene reactor containing acid. Place the apparatus in an oil bath or heating mantle and continuously stir and react for 1 second to 72 hours at a set temperature (e.g., 80°C, 100°C, 120°C). Immerse the fibers in a dilute aqueous solution of sodium bicarbonate or sodium hydroxide for a short time to neutralize the acid adsorbed in the fiber micropores. Thoroughly clean: Rinse and soak the fibers repeatedly with plenty of deionized water until the pH of the outflowing water is neutral.

[0039] It should be noted that the acid solution is any one of concentrated HNO3, H2SO4, or H2SO4 / K2Cr2O7 (chromic acid).

[0040] The present invention provides the following specific embodiments in which the initial fibers are immersed in an alkaline solution: The fibers are immersed in an alkaline solution. This is typically done in a water bath at a specific temperature (room temperature to boiling point, such as 60°C or 80°C) for a certain time (1 second to 72 hours). Then, they are neutralized by immersion in a dilute acetic acid or hydrochloric acid solution. Finally, they are rinsed thoroughly with plenty of deionized water until neutral (pH=7).

[0041] It should be noted that the alkaline solution is either NaOH or KOH solution.

[0042] In another embodiment, step S01 includes: In this embodiment, the chiral molecular template includes any one or more of the following: chiral cationic template, anionic template, electrically neutral chiral template, chiral surfactant, chiral organic ammonium, chiral metal ion center, and chiral ionic liquid cation.

[0043] Similarly, in this embodiment, the polymer precursor includes any one or more of chiral polysilanes, chiral polymers, chiral MOFs, and chiral COFs.

[0044] The chiral polysilanes include tetramethoxysilane, tetraethoxysilane, aminopropyltriethoxysilane, glycidyl etheroxypropyltrimethoxysilane, mercaptopropyltrimethoxysilane, silanylphenyltrimethoxysilane, and dimethyldimethoxysilane, with the general chemical formula (RSiO). 1.5 ) n R can be an inert group (such as isobutyl or cyclohexyl) or a reactive group (such as vinyl, epoxy, or amino), such as 1,2-bis(trimethoxysilyl)ethane.

[0045] The chiral polymers include chiral polypyrrole, chiral polyaniline, chiral polym-phenylenediamine, chiral polyo-phenylenediamine, chiral polyo-phenylenediamine, chiral aminophenol, chiral carbon materials, and chiral B compounds; amino or amine-containing monomers such as pyrrole, aniline, and m-phenylenediamine, compounds containing amine or amino groups, and various amine or amino compounds containing element B.

[0046] The chiral COFs include various substituted aminophenols and aminophenols formed from aldehydes, self-condensation of boric acid or condensation with ortho-diols, hexahydroxytriphenylene: a classic C3 node. Tetrahydroxytetrastyrene reacting with boric acid: an extended C4 node. Terephthaloboric acid: a classic linear linking unit. Imine chemistry (the most widely used and diverse) reactions: condensation of aldehydes with amines, forming C=N bonds. Representative units: aldehyde units: such as the C3 aldehyde node mentioned above, and linear dialdehydes (such as terephthalaldehyde, biphenyl dialdehyde). Amino units: linear diamines: such as p-phenylenediamine, biphenylenediamine, tetrathiofulvalene diamine. Planar trigonal triamines: such as 1,3,5-tris(4-aminophenyl)benzene. Acylhydrazone chemistry reactions: condensation of aldehydes with acylhydrazides, forming C=NN bonds. Representative units: various diacylhydrazide linking units. Alkene chemical reactions: Knoevenagel condensation of aldehydes with methyl ketones or self-condensation of aldehydes, forming C=C bonds. Representative units: 1,3,5-triacetylbenzene (C3 node), terephthalonitrile, etc.

[0047] There are various implementations of chiral MOF structures. Among them, the chiral ligand-constructed type uses chiral amino acids, bipyridines, Schiff bases, etc., to coordinate with metals, resulting in controllable chirality and structural stability; examples include MOF-520 and Zn-amino acid MOFs. The chiral template-induced type uses achiral ligands and metals, with chiral channels formed by a chiral template agent (such as L-tartaric acid). Chirality is retained after template removal; examples include chiral MIL-53 and chiral ZIF-8. The spontaneous resolution type lacks a chiral source; chirality is spontaneously formed during the self-assembly of achiral ligands and metals, requiring resolution to obtain a single configuration; an example is [Co(4,4'-bipy)2(H2O)2]・(NO3)2. The post-modified type grafts chiral groups (such as L-proline) into the channels of achiral MOFs, retaining the original porosity; examples include chiral UiO-66 and chiral MIL-101.

[0048] In addition, in this embodiment, the organic solvent includes any one or more of methanol, ethanol, n-propanol, isopropanol, tetrahydrofuran, diethyl ether, ethyl acetate, acetonitrile, N-dimethylformamide, 1,4-dioxane, dimethyl sulfoxide, acetone, glycerol, ethylene glycol, pyridine, formic acid, and acetic acid.

[0049] Based on the above-described method for preparing chiral electromagnetic shielding fabric, the present invention provides the following specific embodiments: Example 1

[0050] Please see Figure 2 0.05 mmol of L-ValC, a chiral derivative of valine acid with a hexadecyl carbon chain, was added. 16 0.60 mmol of pyrazole-4-boronic acid pinacol ester and 5.99 mmol of p-toluenesulfonic acid were dissolved in 6 mL of ethanol, and then 2.88 mmol of pyrrole, 27 mL of water, and 4.32 mmol of oxidant FeCl3·6H2O were added. The acid-treated cotton fabric was placed in the reactor and reacted for 2 h by in-situ growth on the cotton fabric substrate to obtain cotton fabric with a chiral polymer structure.

[0051] Please see Figures 3 to 4 In the 5.38-8.17 GHz band, EMI SE T It can reach 62dB in the 8.2-12.4GHz band, EMI SE T It can achieve 63dB, which provides a high level of electromagnetic shielding.

[0052] Example 2

[0053] Please see Figure 5 0.05 mmol of the octadecyl chain phenylglycine chiral derivative L-PhgC 18 0.60 mmol of quinoline 8-boronic acid was dissolved in 6 mL of ethanol, 2.88 mmol of pyrrole and 27 mL of water, and finally 4.32 mmol of FeCl3·6H2O was added. The basalt fiber was placed in the reactor and reacted for 2 hours on an acid-treated cotton substrate to obtain basalt with a chiral polymer structure.

[0054] In the 5.38-8.17 GHz band, EMI SE T It can reach 60dB in the 8.2-12.4GHz band, EMI SE T It can achieve 61dB, which provides a high level of electromagnetic shielding.

[0055] Example 3

[0056] 0.05 mmol of an octadecyl chain alanine chiral derivative and 5.99 mmol of p-toluenesulfonic acid were dissolved in 6 mL of ethanol. Then, 2.88 mmol of pyrrole, 27 mL of water, and 4.32 mmol of FeCl3·6H2O were added. The cotton cloth was placed in the reactor, and the reaction was carried out in situ on an alkali-treated sponge substrate for 2 h to obtain a sponge with a chiral polymer structure.

[0057] In the 5.38-8.17 GHz band, EMI SE TIt can reach 70dB in the 8.2-12.4GHz band, EMI SE T It can achieve 70dB, providing a high level of electromagnetic shielding.

[0058] Example 4

[0059] 0.09 mmol of an octadecyl chain valine chiral derivative and 5.99 mmol of salicylic acid were dissolved in 6 mL of ethanol. Then, 2.88 mmol of aniline, 27 mL of water, and 4.32 mmol of FeCl3·6H2O were added. The polyamide fiber was placed in the reactor and reacted for 2 h by in-situ growth on a cotton substrate to obtain polyamide fiber with a chiral polymer structure.

[0060] In the 5.38-8.17 GHz band, EMI SE T It can reach 65dB in the 8.2-12.4GHz band, EMI SE T It can achieve 64dB, providing a high level of electromagnetic shielding.

[0061] Example 5

[0062] 0.09 mmol (L)-PhgC 16 1.83 mmol of 3-aminophenol and 0.09 mmol of manganese acetate tetrahydrate were dissolved in methanol (8 mL). The acid-treated carbon cloth was immersed in the solution, and then stirred at 60°C while adding 62 mL of deionized water. After stirring for 20 minutes, 2.70 mmol of formaldehyde was added dropwise, and the reaction was carried out for 2 hours. The mixture was then carbonized at 1000°C (under high-purity nitrogen protection) to obtain chiral carbon nanotube-supported carbon cloth.

[0063] In the 5.38-8.17 GHz band, EMI SE T It can reach 73dB in the 8.2-12.4GHz band, EMI SE T It can achieve 75dB, providing a high level of electromagnetic shielding.

[0064] The above are merely preferred embodiments of the present invention and do not limit the scope of the patent. Any equivalent structural or procedural transformations made based on the description and drawings of the present invention, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of the present invention.

Claims

1. A chiral electromagnetic shielding fabric, characterized in that, include: Fiber substrate; as well as, A shielding film layer is loaded on the fiber substrate, and the shielding film layer is made of a polymer film with a helical structure on its surface.

2. The chiral electromagnetic shielding fabric according to claim 1, characterized in that, The fiber substrate is made of one or more of the following materials: cellulose fiber, protein fiber, polyester fiber, polyamide fiber, carbon cloth, and basalt.

3. A method for preparing a chiral electromagnetic shielding fabric, used to prepare the chiral electromagnetic shielding fabric according to any one of claims 1 to 2, characterized in that, Includes the following steps: A chiral molecular template is dissolved in an organic solvent to obtain a transparent solution; The fiber substrate is immersed in the transparent solvent to allow the chiral molecules in the chiral molecular template to be uniformly adsorbed on the surface of the fiber. A polymer precursor is added to the transparent solution impregnated with the fiber substrate, causing the precursor to adsorb onto the surface of the chiral molecules, thereby preparing a polymer film with a helical structure on its surface.

4. The method for preparing chiral electromagnetic shielding fabric according to claim 3, characterized in that, Prior to the step of impregnating the fiber substrate in the transparent solvent to allow the chiral molecules in the chiral molecular template to be uniformly adsorbed on the surface of the fiber, the method further includes: The fiber substrate is subjected to surface modification treatment.

5. The method for preparing chiral electromagnetic shielding fabric according to claim 4, characterized in that, The steps for surface modification of the fiber substrate include: The initial fibers are immersed in acid or alkali solutions; The initial fibers are heated and stirred in an acidic or alkaline solution to obtain the treated fibers. The treated fibers are then immersed in a neutralization process to obtain neutralized fibers. The neutralized fibers are rinsed with deionized water to obtain the fiber substrate.

6. The method for preparing chiral electromagnetic shielding fabric according to claim 3, characterized in that, The chiral molecular template includes any one or more of the following: chiral cationic template, anionic template, electrically neutral chiral template, chiral surfactant, chiral organic ammonium, chiral metal ion center, and chiral ionic liquid cation.

7. The method for preparing chiral electromagnetic shielding fabric according to claim 3, characterized in that, The polymer precursor includes any one or more of chiral polysilanes, chiral polymers, chiral MOFs, and chiral COFs.

8. The method for preparing chiral electromagnetic shielding fabric according to claim 3, characterized in that, The organic solvent includes any one or more of methanol, ethanol, n-propanol, isopropanol, tetrahydrofuran, diethyl ether, ethyl acetate, acetonitrile, N-dimethylformamide, 1,4-dioxane, dimethyl sulfoxide, acetone, glycerol, ethylene glycol, pyridine, formic acid, and acetic acid.

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