CN110292895B

CN110292895B - A kind of super-hybrid aerogel electromagnetic interference material and preparation method thereof

Info

Publication number: CN110292895B
Application number: CN201910598470.5A
Authority: CN
Inventors: 张恩爽; 雷朝帅; 李文静; 刘圆圆; 郭慧; 杨洁颖; 张昊
Original assignee: Aerospace Research Institute of Materials and Processing Technology
Current assignee: Aerospace Research Institute of Materials and Processing Technology
Priority date: 2019-07-04
Filing date: 2019-07-04
Publication date: 2021-10-29
Anticipated expiration: 2039-07-04
Also published as: CN110292895A

Abstract

The invention relates to a super-hybrid aerogel electromagnetic interference material and a preparation method thereof. The method is as follows: preparing a phenolic sol containing graphene oxide; gelling and aging the phenolic sol containing graphene oxide to obtain a wet gel, and then immersing the wet gel in a magnetic salt solution to obtain a magnetic salt-wet gel, and then the magnetic-containing salt-wet gel is sequentially subjected to solvent replacement, drying and cracking to obtain a super-hybrid carbon aerogel; the polyimide foam after heat treatment at 100-300 ° C for 1-12 hours is subjected to high temperature cracking to obtain cracked polyimide foam; and mixing and pulverizing the cracked polyimide foam and super-hybrid carbon aerogel with a mass ratio of 1:(0.1-10) to obtain a super-hybrid aerogel glue EMI material. The super-hybrid aerogel electromagnetic interference material prepared by the invention has low density and hierarchical structure, and can simultaneously produce long-term effective interference effects on electromagnetic signals of various frequency bands.

Description

Super-hybrid aerogel electromagnetic interference material and preparation method thereof

Technical Field

The invention belongs to the technical field of aerogel preparation, and particularly relates to a super-mixed aerogel electromagnetic interference material and a preparation method thereof.

Background

The smoke screen is an economic, efficient and simple passive photoelectric countermeasure means, and can perform interference action on photoelectric systems such as reconnaissance alarm, search tracking and the like. In recent years, aerosol smoke screen technology in China is rapidly developed, but the aerosol smoke screen technology still has the limitations of single function, backward variety, over-narrow shielding interference wave band and the like, wherein the multiband (or full-waveband) interference technology is limited by the problems of single material variety, poor action effect and the like for a long time, and the development of a novel multiband and high-efficiency electromagnetic interference material is an important way for solving the limitation of the existing material. Due to the sensitivity of the research field, related research reports at home and abroad are limited, and most of the related research reports are concentrated on an infrared smoke screen with active interference and a passive single-waveband smoke screen. Regarding the multiband interference material, Russian patent (RU:2371665C2) reports a broadband smoke shell with shielding effect on visible light, infrared and radar bands, but the interference effect is limited, and the effective action time is not more than 5 min. Norwegian Vorma.Kjell et al developed a smoke screen bomb composed of an inner cavity and an outer cavity with a full-wave-band shielding effect, and the aim of interfering visible light, infrared and millimeter wave bands can be achieved by mixing two shielding agents, but the operation is relatively complex and the shielding time is less than 5min (see: Zhang Dongmei, Zhao Sheng hong, Qiao Yanhua, et al. military smoke screen hiding agent for foreign countries and the current situation and development of [ J ] infrared technology, 2008,30(7):000376 + 378.). The millimeter wave/infrared composite interference material prepared by carbon fiber, copper-plated carbon fiber, conductive carbon powder and other multi-components has 12.7-16.4dB and 21.2-33.3dB of attenuation on 3mm and 8mm waves respectively, and has 85% -90% of absorption on infrared light, but only realizes effective shielding of two wave bands (see: Tesshui. infrared/millimeter wave composite interference material research [ D ]. Nanjing university of physical Engineers, 2009.). From the current reports, military passive smoke screen interference materials which have long-term effective shielding effect on visible light, infrared light and millimeter wave multiband have not been reported.

The comprehensive shielding performance research is carried out aiming at two wave bands, namely visible light and infrared light, and the interference performance of the material is related to the conductivity and magnetism of the material, and more importantly, the micro structure of the material is matched with the wavelength of the interference wave band, so that the multi-level structure is a breakthrough point for researching the multi-band interference material. The aerogel is a three-dimensional network nano porous material, has the characteristics of high porosity, high specific surface area, low density and the like, and has potential application values in the fields of mechanics, acoustics, electricity, heat, optics and the like. In the existing aerogel systems, carbon aerogel attracts much attention because of its excellent properties such as adjustable size and easy doping, but its properties such as conductivity and lightweight are still to be improved. Graphene has excellent abilities of attenuating and absorbing electromagnetic waves due to characteristics of high conductivity, high dielectric constant, surface residual defects and functional groups, and the like, and is an ideal material for electromagnetic interference, but has limitations of low attenuation rate, single action waveband, high cost and the like when being applied alone.

Therefore, in order to utilize the advantages of the carbon material and the graphene material, solve the advantages and limitations existing when the graphene-carbon composite aerogel is independently used as an electromagnetic interference material, combine the structural characteristics of the graphene, the carbon aerogel and the magnetic nano powder, and the prepared magnetic graphene-carbon composite aerogel is expected to expand the structural advantages of the material and develop a novel smoke screen interference material.

Chinese patent application CN201910209695.7 discloses a preparation method of a carbon aerogel based electromagnetic shielding material, although the total shielding effect of the carbon aerogel based electromagnetic shielding material obtained by the preparation method is 7.5-10.5 dB at 8.2-12.4 GHz and the wave-absorbing reflection loss at 8.2-12.4 GHz can reach-35 dB at most, the carbon aerogel sheet prepared by the method is subjected to electromagnetic shielding performance test in a form of the carbon aerogel sheet, the action target is to electromagnetic pollution instead of military countermeasure (the patent), the implementation mode is the aerogel sheet instead of a smoke-spreading curtain, the action waveband range is narrow, and the application effect of the carbon aerogel based electromagnetic shielding material is different from that of the material disclosed by the invention.

CN201810050424.7 discloses a preparation method of graphene-doped carbon aerogel powder for electromagnetic interference materials, wherein the material prepared by the method has excellent electromagnetic shielding performance; secondly, magnetic components are introduced to increase magnetic loss; the combined action of the structure and the components improves the overall interference performance of the material on infrared light and visible light.

CN106243379A proposes a graphene-polymer composite foam material prepared by a freeze drying method, the material has an electromagnetic shielding performance of shielding rate not less than 40dB within the range of 8-12Hz, the material belongs to a block shielding material, is a material designed aiming at electromagnetic pollution, is a smoke screen material required by non-military countermeasure, and has a narrower electromagnetic shielding wave band, which is different from the material of the invention in application effect.

Disclosure of Invention

The invention provides a super-hybrid aerogel electromagnetic interference material and a preparation method thereof, aiming at solving the problems of high density of an electromagnetic shielding material, single electromagnetic shielding wave band and short effective shielding action time in the prior art.

The invention provides a preparation method of an ultra-hybrid aerogel electromagnetic interference material in a first aspect, which comprises the following steps:

(1) preparing a precursor solution from a phenolic substance and a weakly basic catalyst by using water, dispersing the graphene oxide solution in the precursor solution to obtain a precursor mixed solution containing the graphene oxide, adding an aldehyde substance into the precursor mixed solution containing the graphene oxide, and uniformly mixing to obtain a phenolic sol containing the graphene oxide;

(2) gelling and aging the phenolic sol containing graphene oxide prepared in the step (1) to obtain wet gel, then putting the wet gel into a magnetic salt solution for soaking to obtain magnetic salt-containing wet gel, and then sequentially carrying out a solvent replacement step and a drying step on the magnetic salt-containing wet gel to obtain the super-hybrid phenolic aerogel;

(3) carrying out pyrolysis on the super-hybrid phenolic aerogel prepared in the step (2) to prepare super-hybrid carbon aerogel;

(4) carrying out pyrolysis on the polyimide foam subjected to heat treatment for 1-12h at 100-300 ℃ to obtain a pyrolyzed polyimide foam; and

(5) and (3) mixing the cracked polyimide foam obtained in the step (4) with the super hybrid carbon aerogel obtained in the step (3) according to the mass ratio of 1: (0.1-10) mixing and crushing to obtain the super-mixed aerogel electromagnetic interference material.

Preferably, the magnetic salt solution is an iron salt solution and/or a cobalt salt solution; and/or in the step (4), the density of the mixture after heat treatment for 1-12 hours at 100-300 ℃ is 0.01-0.5g/cm³The polyimide foam is subjected to high-temperature cracking to obtain the cracked polyimide foam.

Preferably, the ferric salt solution is a ferric trichloride solution and/or a ferric nitrate solution; and/or the cobalt salt solution is a cobalt dichloride solution and/or a cobalt nitrate solution.

Preferably, the concentration of the magnetic salt solution is 0.1-10 g/L; and/or in the step (2), the dipping time is 1-10 days.

Preferably, in the step (3), the pyrolysis temperature is 500-1500 ℃, and the pyrolysis time is 1-10 h; and/or in the step (4), the pyrolysis temperature is 800-1500 ℃, and the pyrolysis time is 1-10 h.

Preferably, the concentration of the weak alkaline catalyst is 0.1-5 wt%; the concentration of the graphene oxide solution is 1-100 g/L; the mass ratio of the phenolic substance, the weak alkaline catalyst with the concentration of 0.1-5 wt%, water, the graphene oxide solution with the concentration of 1-100g/L and the aldehyde substance is (1-500): (1-100): (1-200): (0.001-10): (1-100); and/or the graphene accounts for 1-8% of the super-hybrid aerogel electromagnetic interference material by mass percent.

Preferably, the phenolic material is selected from the group consisting of phenol, resorcinol, phloroglucinol, cresol, xylenol, mixed cresols and nonylphenol; the aldehyde substance is selected from the group consisting of formaldehyde, paraformaldehyde, furfural and acetaldehyde; and/or the weakly basic catalyst is a sodium carbonate solution.

Preferably, in the step (2), the gelling and aging temperature is 20-90 ℃, and the gelling and aging time is 1-8 days; and/or in the step (2), the solvent replacement is carried out in an alcohol solvent or a ketone solvent, the solvent replacement time is 1-8 days, and the solvent replacement is repeated for 1-5 times; the alcohol solvent is selected from the group consisting of methanol, ethanol, propanol and isopropanol; the ketone solvent is selected from the group consisting of butanone and acetone; and/or in the step (2), the drying is supercritical drying which takes absolute ethyl alcohol as a drying medium; the supercritical drying with absolute ethyl alcohol as a drying medium comprises the following steps: and (2) carrying out a solvent replacement step on the wet gel containing the magnetic salt, then, loading the wet gel into supercritical drying equipment, placing the supercritical drying equipment into an autoclave, adding absolute ethyl alcohol into the autoclave, sealing the autoclave to ensure that the pressure in the autoclave is 5-30MPa and the temperature is 0-40 ℃, keeping the pressure and the temperature for 1-48h, and then discharging the absolute ethyl alcohol and fluid generated in the drying process to obtain the super-hybrid phenolic aerogel.

Preferably, in the step (5), the cracked polyimide foam and the super-hybrid carbon aerogel are placed in a high-rotation-speed pulverizer to be subjected to mixed pulverization, in the process of mixed pulverization, the rotation speed of the high-rotation-speed pulverizer is 10000-100000r/min, and the time of mixed pulverization is 1-30 min.

The invention provides in a second aspect the super-hybrid aerogel electromagnetic interference material prepared by the preparation method of the first aspect of the invention.

Compared with the prior art, the invention at least has the following beneficial effects:

(1) the magnetic graphene carbon aerogel material is prepared by adopting graphene-doped carbon aerogel as a carrier, and the graphene carbon aerogel is of a hierarchical micro-nano structure which is beneficial to ferroferric oxide (Fe)₃O₄) Magnetic nano particles such as cobalt oxide (CoO) and the like are uniformly loaded, and compared with a carbon aerogel based electromagnetic shielding material taking pure carbon aerogel as a carrier, the magnetic graphene carbon aerogel material (super-hybrid carbon aerogel) prepared by the invention can obviously contribute to improving the overall electromagnetic long-term interference performance of the material; in the dipping process in the present invention, the magnetic ion (e.g., Fe) contained in the magnetic salt solution³⁺Or Co²⁺) Coupling reaction with wet gel to make magnetic ion (such as Fe)³⁺Or Co²⁺) The nano particles are embedded in the wet gel material and cannot be removed in the subsequent solvent replacement process, and compared with a doping method for directly adding magnetic salt ions into a sol-gel process, the nano particles prepared by the modification method are better in dispersion, and the method cannot influence the phenolic gel process.

(2) The composite aerogel is prepared by using a graphene doping technology, and the micron-sized PI foam, the submicron-sized graphene sheet layer and the graded size effect of carbon aerogel nanoparticles are used, so that long-term effective interference effect can be generated on electromagnetic signals of various wave bands (including visible light, a middle infrared wave band (3-5 mu m) and a far infrared wave band (8-12 mu m)) at the same time, and the defects of single interference wave band and short effective shielding time of the traditional material are overcome; the inventor finds that the formula of the material, namely the proportion of each scale, can be adjusted according to different interference wave bands, so as to realize better interference effect; more importantly, the inventor finds that in the super hybrid aerogel electromagnetic interference material, the mass ratio of the polyimide foam after cracking to the super hybrid carbon aerogel needs to be controlled to be 1: (0.1 to 10), and more preferably controlled in a range of 1: (2-4), so can guarantee that the electromagnetic interference material of super-mixed aerogel produces long-term effectual interference effect to the electromagnetic signal of multiple wave bands simultaneously better.

(3) The invention is different from the prior art that a foam layer is introduced into an electromagnetic shielding material, the invention adopts the steps of carrying out heat treatment for 1-12h at 100-300 ℃, mixing and crushing PI foam subjected to high-temperature cracking and the super hybrid carbon aerogel for carrying out pulverization treatment to prepare the super hybrid aerogel electromagnetic interference material, the inventor finds that the PI foam subjected to special heat treatment can be better fused with other powder, the PI foam subjected to high-temperature cracking can reduce the density and improve the conductivity, the electromagnetic interference performance of the super hybrid aerogel electromagnetic interference material on various wave bands can be obviously improved, and the effective electromagnetic shielding action time of the material can be prolonged.

(4) According to the invention, the high-conductivity graphene and the magnetic nanoparticles are combined to endow the material with high electronic conduction and magnetism, so that when electromagnetic waves are incident on the surface of the material, dielectric loss and magnetic loss are generated simultaneously, and the electromagnetic interference performance of the material is improved.

(5) The application of the super-mixed aerogel electromagnetic interference material prepared by the invention in the field of electromagnetic interference can be effectively realized by combining a scattering technology.

(6) The super-hybrid gel electromagnetic interference material prepared by the invention is microcosmically of a porous structure, the average pore diameter is 15-300 nm, the doping amount of graphene is 1-10%, preferably 1-8%, and the density is 0.01-0.5g/cm³The electromagnetic interference performance for visible light is 90% or more, and the electromagnetic interference performance for infrared light is 70% or more, more preferablyThe electromagnetic interference performance to visible light is more than 95%, and the electromagnetic interference performance to infrared light is more than 75%.

Drawings

FIG. 1 is a flow chart of the preparation of the super-hybrid aerogel electromagnetic interference material of the present invention.

Fig. 2 is an SEM image of the super-hybrid aerogel emi material prepared in example 1 of the present invention.

FIG. 3 is an EDS energy spectrum (Fe) of the super-hybrid aerogel EMI material prepared in example 1 of the present invention.

FIG. 4 is an EDS energy spectrum (Co) of the super-hybrid aerogel EMI material prepared in example 3 of the present invention.

FIG. 5 is a macroscopic picture of the polyimide foam of example 1 of the present invention before and after cracking. In the figure, (a) shows a polyimide foam before cracking, and (b) shows a polyimide foam after cracking.

FIG. 6 is an SEM photograph of cracked polyimide foam of example 1 of the present invention after pulverization.

FIG. 7 shows the transmittance of the super-hybrid aerogel EMI material prepared in example 1 of the present invention to infrared light of 3-5 μm.

FIG. 8 shows the transmittance of the super-hybrid aerogel EMI material prepared in example 1 of the present invention to infrared light of 8-12 μm.

Fig. 9 shows the transmittance of visible light for the super-hybrid aerogel electromagnetic interference material prepared in example 1 of the present invention. In fig. 7 to 9, the unit of abscissa time is second(s).

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the embodiments described are only a few embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

(2) gelling and aging the phenolic sol containing graphene oxide prepared in the step (1) to obtain wet gel, then putting the wet gel into a magnetic salt solution (containing a magnetic element solution, such as an iron salt solution or a cobalt salt solution) for dipping to obtain magnetic salt-containing wet gel, and then sequentially carrying out a solvent replacement step and a drying step on the magnetic salt-containing wet gel to obtain the super-hybrid phenolic aerogel; in the present invention, super-hybrid phenolic aerogel is also referred to as magnetic/graphene oxide/phenolic super-hybrid aerogel or graphene oxide/M (OH)_xComposite phenolic aerogel, wherein M is a magnetic element, such as iron or cobalt;

(3) carrying out pyrolysis on the super-hybrid phenolic aerogel prepared in the step (2) to prepare super-hybrid carbon aerogel; in the present invention, the super hybrid carbon aerogel is also referred to as magnetic/graphene/carbon super hybrid aerogel;

(4) pyrolyzing (e.g., pyrolyzing in a pyrolysis furnace) a polyimide foam (PI foam) after heat treatment for 1 to 12 hours (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, or 12 hours) at 100 to 300 ℃ (e.g., 100 ℃, 120 ℃, 150 ℃, 180 ℃,200 ℃, 220 ℃, 250 ℃, 280 ℃, or 300 ℃) to obtain a pyrolyzed polyimide foam; preferably, the polyimide foam after heat treatment for 3 to 6 hours (e.g., 3, 3.5, 4, 4.5, 5, 5.5, or 6 hours) at 150 to 300 ℃ (e.g., 150 ℃, 160 ℃, 170 ℃, 180 ℃, 190 ℃,200 ℃, 210 ℃, 220 ℃, 230 ℃, 240 ℃, 250 ℃, 260 ℃, 270 ℃, 280 ℃, 290 ℃, or 300 ℃) is subjected to pyrolysis to obtain a cracked polyimide foam;

(5) and (3) mixing the cracked polyimide foam obtained in the step (4) with the super hybrid carbon aerogel obtained in the step (3) according to the mass ratio of 1: (0.1-10) (e.g., 1:0.1, 1:0.5, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, or 1:10) by mixing and pulverizing to obtain a super-hybrid aerogel electromagnetic interference material; namely, in the super-hybrid aerogel electromagnetic interference material, the mass ratio of the cracked polyimide foam to the super-hybrid carbon aerogel is 1: (0.1 to 10), preferably 1: (2 to 4) (examples: 1:2, 1:2.5, 1:3, 1:3.5 or 1: 4).

Particularly, the electromagnetic interference material prepared by the invention is a powder material, and in the implementation process, the powder needs to be scattered into a smoke screen by compressed gas, so that the effective shielding of light with different wave bands is realized; the electromagnetic interference material prepared by the invention is a smoke screen material suitable for military countermeasures.

The magnetic graphene carbon aerogel material is prepared by adopting graphene-doped carbon aerogel as a carrier, and the graphene carbon aerogel is of a hierarchical micro-nano structure which is beneficial to ferroferric oxide (Fe)₃O₄) Magnetic nano particles such as cobalt oxide (CoO) and the like are uniformly loaded, and compared with a carbon aerogel based electromagnetic shielding material taking pure carbon aerogel as a carrier, the magnetic graphene carbon aerogel material (super-hybrid carbon aerogel) prepared by the invention can obviously contribute to improving the overall electromagnetic long-term interference performance of the material; in the dipping process in the present invention, the magnetic ion (e.g., Fe) contained in the magnetic salt solution³⁺Or Co²⁺) Coupling reaction with wet gel to make magnetic ion (such as Fe)³⁺Or Co²⁺) Compared with a doping method in which magnetic salt ions are directly added into a sol-gel process, the nano particles prepared by the modification method are better dispersed, and the method cannot influence the phenolic gel process, because the magnetic modification of the wet gel is performed after gelation and aging, magnetic ions such as Fe are avoided³⁺Or Co²⁺The reaction with weak alkaline catalyst such as sodium carbonate, prevent the gelation process of the solution, and can not realize the preparation of the super-mixed aerogel. The invention utilizes the graphene doping technologyThe composite aerogel is prepared by the method, and by utilizing the micron-scale of PI foam, the submicron-scale of graphene sheet layers and the grading size effect of carbon aerogel nanoparticles, long-term effective interference action can be simultaneously generated on electromagnetic signals of various wave bands (comprising visible light, a middle infrared wave band (3-5 mu m) and a far infrared wave band (8-12 mu m)), so that the defects of single interference wave band and short effective shielding action time of the traditional material are overcome.

The inventor finds that the formula of the material, namely the proportion of each scale, can be adjusted according to different interference wave bands, so as to realize better interference effect; more importantly, the inventor finds that in the super hybrid aerogel electromagnetic interference material, the mass ratio of the polyimide foam after cracking to the super hybrid carbon aerogel needs to be controlled to be 1: (0.1 to 10), and more preferably controlled in a range of 1: (2-4), so that the electromagnetic interference material of the super-hybrid aerogel can be better ensured to generate long-term effective interference effect on electromagnetic signals of various wave bands; in the invention, the quality ratio of polyimide foam and super-hybrid carbon aerogel has a great influence on performance, too much polyimide foam can cause that the magnetic graphene carbon material with a micro-nano structure can not fully exert interference on short-wave-band light, wave transmission can occur, too little foam can not better realize the internal multi-level reflection of the material, and the interference performance is influenced; in addition, the invention is different from the prior art that a foam layer is introduced into the electromagnetic shielding material, the invention overcomes the technical bias that polyimide foam (PI foam) can not be heated and can possibly cause performance reduction after being heated, the invention introduces the polyimide foam which is subjected to special heat treatment and high-temperature cracking, the polyimide foam with a special structure has certain conductivity and light weight, and can effectively improve the electromagnetic interference performance of the material, the invention adopts the technical scheme that the PI foam is subjected to heat treatment for 1-12h at 100-300 ℃, more preferably for 3-6 h at 150-300 ℃, the PI foam after high-temperature cracking is mixed and crushed with the super-hybrid carbon aerogel for powdering treatment to prepare the super-hybrid aerogel electromagnetic interference material, and the inventor finds that the PI foam after special heat treatment can be better fused with other powder, PI foam after pyrolysis can reduce density and improve electric conductivity, can obviously improve super mixed aerogel electromagnetic interference material is simultaneously to the electromagnetic interference performance of multiple wave bands and the effective electromagnetic shield effect time of extension material can show the long-term anti-interference ability that improves material mid infrared band (3 ~ 5 mu m) and far infrared band (8 ~ 12 mu m) very much.

The super-hybrid aerogel electromagnetic material prepared by the invention can obviously improve the shielding performance of infrared light and visible light, and particularly introduces a foam structure with a special structure, so that the multiple internal reflection is improved; and secondly, a magnetic component is introduced to increase magnetic loss, and the overall interference performance of the material on infrared light and visible light is improved under the combined action of the structure and the component.

According to some preferred embodiments, the magnetic salt solution is a ferric salt solution and/or a cobalt salt solution. In the present invention, the iron salt solution and/or the cobalt salt solution are/is an aqueous solution using water as a solvent.

According to some preferred embodiments, in the step (4), the density of the mixture after heat treatment at 100-300 ℃ for 1-12h is 0.01-0.5g/cm³(e.g., 0.01, 0.05, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, or 0.5g/cm³) Performing pyrolysis on the polyimide foam to obtain the polyimide foam after pyrolysis; preferably, in the step (4), the polyimide foam before pyrolysis has a density of 0.15-0.4 g/cm after heat treatment at 100-300 ℃ for 1-12h³The polyimide foam of (a); more preferably, in the step (4), the density of the polyimide foam before pyrolysis after heat treatment at 300 ℃ for 3-6 h is 0.15-0.4 g/cm³The polyimide foam of (1). The density of the polyimide foam before pyrolysis has important influence on the long-term anti-interference performance of the super-mixed aerogel electromagnetic interference material, and the density after heat treatment is preferably 0.01-0.5g/cm³More preferably, the density is 0.15 to 0.4g/cm³The polyimide foam is subjected to pyrolysis, so that the preparation of the super-hybrid aerogel electromagnetic interference material with long effective shielding action time is ensured(ii) a Moreover, the inventor finds that when the temperature of the heat treatment is 150-300 ℃ and the time of the heat treatment is 3-6 hours, the preparation density is more favorably ensured to be 0.15-0.4 g/cm³The polyimide foam of (1).

According to some preferred embodiments, the iron salt solution is a solution of ferric chloride (FeCl)₃Solution) and/or ferric nitrate solution; and/or the cobalt salt solution is a cobalt dichloride solution (CoCl)₂Solution) and/or cobalt nitrate solution.

According to some preferred embodiments, the concentration of the magnetic salt solution is 0.1 to 10g/L (e.g., 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10g/L), preferably 0.1 to 3 g/L; and/or in step (2), the soaking time is 1-10 days (for example, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 days).

According to some preferred embodiments, in step (3), the pyrolysis temperature is 500 to 1500 ℃ (e.g., 500 ℃, 600 ℃, 700 ℃, 800 ℃, 900 ℃, 1000 ℃, 1100 ℃, 1200 ℃, 1300 ℃, 1400 ℃ or 1500 ℃), and the pyrolysis time is 1 to 10h (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10 h); and/or in step (4), the pyrolysis temperature is 800-1500 ℃ (such as 800 ℃, 900 ℃, 1000 ℃, 1100 ℃, 1200 ℃, 1300 ℃, 1400 ℃ or 1500 ℃) and is preferably 1000-1200 ℃, and the pyrolysis time is 1-10h (such as 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10h) and is preferably 1-4 h; in particular, the pyrolysis in step (3) and/or the pyrolysis in step (4) is carried out under protection of an inert atmosphere (e.g. a nitrogen atmosphere or an argon atmosphere); the invention discovers that the pyrolysis temperature of the polyimide foam has important influence on the prepared super-hybrid aerogel electromagnetic interference material, and the pyrolysis temperature out of the range, particularly the pyrolysis temperature under the conditions that the pyrolysis temperature is 1000-1200 ℃ and the pyrolysis time is not 1-4 h, is not beneficial to preparing the super-hybrid aerogel electromagnetic interference material with excellent electromagnetic interference performance.

According to some preferred embodiments, the concentration of the weakly basic catalyst is 0.1 to 5 wt% (e.g., 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 1 wt%, 2 wt%, 3 wt%, 4 wt%, or 5 wt%); the concentration of the graphene oxide solution is 1-100g/L, preferably 2-50 g/L (for example, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38, 40, 42, 44, 46, 48 or 50 g/L); the mass ratio of the phenolic substance, the weak alkaline catalyst with the concentration of 0.1-5 wt%, water, the graphene oxide solution with the concentration of 1-100g/L and the aldehyde substance is (1-500): (1-100): (1-200): (0.001-10): (1-100) preferably (1-100): (1-50): (20-200): (0.001-5): (2-20); and/or the graphene accounts for 1-10% by mass, preferably 1-8% (e.g., 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 6.5%, 7%, 7.5% or 8%) of the super-hybrid aerogel electromagnetic interference material. The graphene accounts for 1-10% of the super-hybrid aerogel electromagnetic interference material in percentage by mass, and more preferably 1-8%, within the range of 1-8%, with the increase of the graphene in the super-hybrid aerogel electromagnetic interference material in percentage by mass, the change of the average particle size and the average pore size of the carbon aerogel is avoided, the density of the super-hybrid aerogel electromagnetic interference material is reduced, and the electromagnetic shielding performance of the super-hybrid aerogel electromagnetic interference material is improved; however, when the content of graphene is too high, that is, the amount of graphene oxide is too large, the graphene oxide dispersion effect is not good, which in turn leads to an increase in density of the super-hybrid aerogel electromagnetic interference material and a decrease in electromagnetic shielding performance.

According to some preferred embodiments, the phenolic material is selected from the group consisting of phenol, resorcinol, phloroglucinol, cresol, xylenol, mixed cresols and nonylphenol; the aldehyde substance is selected from the group consisting of formaldehyde, paraformaldehyde, furfural and acetaldehyde; and/or the weakly basic catalyst is a sodium carbonate solution.

According to some preferred embodiments, in the step (2), the temperature of the gelling and aging is 20-90 ℃, and the time of the gelling and aging is 1-8 days; and/or in the step (2), the solvent replacement is carried out in an alcohol solvent or a ketone solvent, the solvent replacement time is 1-8 days, and the solvent replacement is repeated for 1-5 times; the alcohol solvent is selected from the group consisting of methanol, ethanol, propanol and isopropanol; the ketone solvent is selected from the group consisting of butanone and acetone; and/or in the step (2), the drying is supercritical drying which takes absolute ethyl alcohol as a drying medium; the supercritical drying with absolute ethyl alcohol as a drying medium comprises the following steps: and (2) carrying out a solvent replacement step on the wet gel containing the magnetic salt, then, loading the wet gel into supercritical drying equipment, placing the supercritical drying equipment into an autoclave, adding absolute ethyl alcohol into the autoclave, sealing the autoclave to ensure that the pressure and the temperature of the liquid in the autoclave are 5-30MPa and 0-40 ℃, keeping the pressure and the temperature for 1-48h, and then discharging the absolute ethyl alcohol and the fluid generated in the drying process to obtain the super-hybrid phenolic aerogel.

According to some preferred embodiments, in the step (5), the cracked polyimide foam and the ultra-hybrid carbon aerogel are placed in a high-speed pulverizer to perform the mixed pulverization, wherein the rotation speed of the high-speed pulverizer is 10000-100000r/min (such as 10000, 20000, 30000, 40000, 50000, 60000, 70000, 80000, 90000 or 100000r/min), and the mixed pulverization time is 1-30min (such as 1, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28 or 30min), preferably 10-30 min (10, 15, 20, 25 or 30 min). When the crushing time is more than 5min, the crusher works for 5min, and starts to work next time after the interval of 10min, so that the instrument is prevented from heating seriously.

According to some specific embodiments, in the present invention, the process for preparing the super hybrid aerogel electromagnetic interference material comprises:

s1 preparation of phenolic sol containing graphene oxide

Weighing 1-500g of resorcinol in a beaker, adding 1-100g of sodium carbonate solution with the mass fraction of 0.1-5% into the beaker, then weighing 1-200g of deionized water in the beaker, and carrying out magnetic stirring until the resorcinol is completely dissolved to obtain a precursor solution; then weighing 1-100mL of graphene oxide solution of 1-100g/L, adding the graphene oxide solution into the precursor solution, stirring for 1-30min, and performing ultrasonic treatment for 1-60min to obtain a precursor mixed solution containing graphene oxide; and weighing 1-100g of formaldehyde, adding the formaldehyde into the precursor mixed solution containing the graphene oxide, and magnetically stirring for 1-60min to obtain the phenolic sol containing the graphene oxide.

S2 preparation of magnetic/graphene oxide/phenolic aldehyde super-hybrid aerogel

Placing the system in an oven at 20-90 ℃ for gelling and aging for 1-8 days to obtain wet gel; subsequently, the gelled and aged wet gel was carefully separated from the container, and the wet gel was divided into 0.1-2cm³In small pieces and is juxtaposed with 0.1-10g/L FeCl₃Or CoCl₂Soaking in the magnetic element solution for 1-10 days to obtain wet gel containing magnetic salt. Then, taking the wet gel containing the magnetic salt out of the magnetic salt solution, then placing the wet gel containing the magnetic salt in a container containing ethanol, wherein the volume of the ethanol is 5-50 times that of the wet gel containing the magnetic salt, carrying out solvent replacement for 1-8 days, and repeating the step for 1-5 times to finish the solvent replacement process; and finally, placing the container filled with the magnetic salt wet gel after solvent replacement in an autoclave, adding absolute ethyl alcohol into the autoclave, sealing to ensure that the liquid pressure reaches 5-30MPa and the temperature reaches 0-40 ℃, maintaining the pressure and the temperature for 1-48h, and then slowly discharging fluid at constant temperature to finally obtain a magnetic/graphene oxide/phenolic aldehyde super-hybrid aerogel (super-hybrid phenolic aerogel) product.

S3 preparation of magnetic/graphene/carbon super-hybrid aerogel

And (3) carrying out a cracking process on the magnetic/graphene oxide/phenolic aldehyde super-hybrid aerogel prepared by supercritical drying under the protection of nitrogen, wherein the cracking temperature is 500-1500 ℃, and the time is 1-10h, so as to obtain the magnetic/graphene/carbon super-hybrid aerogel (super-hybrid carbon aerogel).

S4 preparation of cracked PI foam

The density of the mixture is 0.01-0.5g/cm after heat treatment at 100-300 ℃ for 1-12h in advance³The PI foam is placed in a high-temperature cracking furnace to be cracked for 1-10h at the temperature of 800-1500 ℃ to obtain the cracked PI foam.

S5 preparation of super-mixed aerogel electromagnetic interference material

Crushing the cracked PI foam and the magnetic/graphene/carbon super-hybrid aerogel in a high-rotation-speed crusher, wherein the mass ratio of the cracked PI foam to the magnetic/graphene/carbon super-hybrid aerogel is 1 (0.1-10), the rotation speed in the crushing process is 10000-100000r/min, the crushing time is 1-30min, the interval is 10min every 5min, and collecting the obtained powder, namely the super-hybrid aerogel electromagnetic interference material.

The super-mixed aerogel electromagnetic interference material prepared by the invention has the advantages of low density and multiple electromagnetic interference wave bands (including visible light wave bands, 3-5 mu m mid-infrared wave bands and 8-12 mu m far-infrared wave bands); in the super-hybrid aerogel electromagnetic interference material prepared by the invention, the preferable doping amount of graphene is 1-8%, the macroscopic maximum size (powder particle size) of the super-hybrid aerogel electromagnetic interference material is 100-300 mu m, the microscopic minimum size (gel nanoparticle size) is 10-25nm, the microscopic structure of the super-hybrid aerogel electromagnetic interference material is a porous structure, the average pore diameter is 15-300 nm, and the density is 0.01-0.5g/cm³The average electromagnetic interference performance for visible light is more than 90%, and the average electromagnetic interference performance for infrared light is more than 75%. In the invention, the maximum size refers to the particle size of powder, the minimum size refers to the size of nano particles in the particles, and the average pore size refers to the average pore size of a microstructure in the whole material.

The application of the super-mixed aerogel electromagnetic material prepared by the invention in the field of electromagnetic interference can be effectively realized by combining a scattering technology; specifically, a blower is used to drive the target area to 1-10m²Blowing and scattering the electromagnetic interference material powder at a wind speed of/min, wherein the scattering density is 0.1-10g/m³。

The invention will be further illustrated by way of example, but the scope of protection is not limited to these examples.

Example 1

S1 preparation of phenolic sol containing graphene oxide

Weighing 5.5g of resorcinol in a beaker, adding 10g of sodium carbonate solution with the mass fraction of 1% into the beaker, then weighing 59g of deionized water in the beaker, and carrying out magnetic stirring until the resorcinol is completely dissolved to obtain a precursor solution; then weighing 15mL of 26g/L graphene oxide solution, adding the solution into the precursor solution, stirring for 5min, and performing ultrasonic treatment for 30min to obtain a precursor mixed solution containing graphene oxide; and weighing 9g of formaldehyde, adding the formaldehyde into the precursor mixed solution containing the graphene oxide, and magnetically stirring for 30min to obtain the phenolic sol containing the graphene oxide.

Placing the system in an oven at 80 ℃ for gelation and aging for 3 days to obtain wet gel; subsequently, the gelled and aged wet gel was carefully separated from the container, and the wet gel was divided into 1cm³In a small block of FeCl at a concentration of 1g/L₃Soaking in the solution for 3 days to obtain wet gel containing magnetic salt. Then, taking the wet gel containing the magnetic salt out of the magnetic salt solution, then placing the wet gel containing the magnetic salt in a container containing ethanol, wherein the volume of the ethanol is 10 times that of the gel, carrying out solvent replacement for 3 days, repeating the step for 3 times, and finishing the solvent replacement process; and finally, placing the container filled with the wet gel containing the magnetic salt after solvent replacement in an autoclave, adding absolute ethyl alcohol into the autoclave, sealing to ensure that the liquid pressure reaches 25MPa and the temperature reaches 25 ℃, maintaining the pressure and the temperature for 24 hours, and then slowly discharging fluid at constant temperature to finally obtain a magnetic/graphene oxide/phenolic aldehyde super-hybrid aerogel (super-hybrid phenolic aerogel) product.

S3 preparation of magnetic/graphene/carbon super-hybrid aerogel

And (3) cracking the magnetic/graphene oxide/phenolic aldehyde super-hybrid aerogel prepared by supercritical drying under the protection of nitrogen, wherein the cracking temperature is 1000 ℃, and the time is 6 hours, so as to obtain the magnetic/graphene/carbon super-hybrid aerogel (super-hybrid carbon aerogel).

S4 preparation of cracked PI foam

The density of the mixture is 0.2g/cm after heat treatment at 280 ℃ for 5 hours in advance³And (3) putting the PI foam into a high-temperature cracking furnace to crack for 2 hours at 1000 ℃.

S5 preparation of super-mixed aerogel electromagnetic interference material

Crushing the cracked PI foam and the super-mixed carbon aerogel in a high-speed crusher, wherein the mass ratio of the cracked PI foam to the super-mixed carbon aerogel is 1:3, the rotation speed in the crushing process is 40000r/min, the crushing time is 10min, the time is 10min after each 5min of operation, and the obtained powder is collected, namely the super-mixed aerogel electromagnetic interference material.

S6 method for scattering super-mixed aerogel electromagnetic interference material

5m in the target area by using a blower²Blowing and scattering the super-mixed aerogel electromagnetic interference material powder at a wind speed of/min, wherein the scattering density is 1g/m³。

In the super-hybrid aerogel electromagnetic interference material prepared by the embodiment, the powder particle size of the super-hybrid aerogel electromagnetic interference material is 300 μm, the gel nanoparticle size is 15nm, and the powder density of the super-hybrid aerogel electromagnetic interference material is 0.075g/cm³Within the shielding time of 0-30 min, the average electromagnetic interference performance of the material on visible light is more than 99% (as shown in figure 9), the effective shielding action time on visible light is 50min, within the shielding time of 0-10 min, the average electromagnetic interference performance on infrared light with the wavelength of 3-5 mu m is more than 99% (as shown in figure 7), within the shielding time of 0-5 min, the average electromagnetic interference performance on infrared light with the wavelength of 8-12 mu m is more than 98% (as shown in figure 8), and the effective shielding action time of the material on infrared light is 46 min. In the invention, the interference performance of a test material is shown as a time-dependent change curve, the shielding rate is more than 65% and is regarded as effective shielding, and the corresponding time is effective acting time, wherein the shielding rate is 100% -transmittance.

Example 2

Example 2 is essentially the same as example 1, except that: in step S1, 10mL of 26g/L graphene oxide solution is weighed and added to the precursor solution.

Example 3

Example 3 is essentially the same as example 1, except that: in step S2, CoCl is used at the same concentration₂As a modifying solution.

Example 4

Example 4 is essentially the same as example 1, except that: in step S2, the magnetic modification process is in the sol-gel stage, i.e. FeCl with a concentration of 1g/L is directly added₃The modification solution is added to the graphene oxide-containing phenolic sol, resulting in no gelation.

Example 5

Example 5 is essentially the same as example 1, except that: in step S3, the cracking temperature of the magnetic/graphene oxide/phenolic aldehyde super hybrid aerogel is 1500 ℃.

Example 6

Example 6 is essentially the same as example 1, except that: in step S3, the cracking time of the magnetic/graphene oxide/phenolic aldehyde super-hybrid aerogel is 10 h.

Example 7

Example 7 is essentially the same as example 1, except that: in step S4, the polyimide foam was cracked at 1200 ℃ for 2 hours.

Example 8

Example 8 is essentially the same as example 1, except that: in step S4, the polyimide foam was cracked at 800 ℃ for 6 hours.

Example 9

Example 9 is essentially the same as example 1, except that: in step S4, the polyimide foam was cracked at 1500 ℃ for 2 hours.

Example 10

Example 10 is essentially the same as example 1, except that: in step S5, the mass ratio of the cracked PI foam to the super hybrid carbon aerogel is 1:2.

Example 11

Example 11 is essentially the same as example 1, except that: in step S5, the mass ratio of the cracked PI foam to the super hybrid carbon aerogel is 1: 4.

Example 12

Example 12 is essentially the same as example 1, except that: in step S5, the mass ratio of the cracked PI foam to the super hybrid carbon aerogel is 1: 0.5.

Example 13

Example 13 is essentially the same as example 1, except that: in step S5, the mass ratio of the cracked PI foam to the super hybrid carbon aerogel is 1: 8.

Comparative example 1

Comparative example 1 is substantially the same as example 1 except that: not including step S4, in step S5, no PI foam was added during the pulverization in the high rotation speed pulverizer.

Comparative example 2

Comparative example 2 is substantially the same as example 1 except that: not including the step S4, directly crushing PI foam and super-mixed carbon aerogel which are not subjected to heat treatment and high-temperature cracking in a high-speed crusher in the step S5, wherein the mass ratio of the PI foam and the super-mixed carbon aerogel which are not subjected to special treatment is 1:1, the rotation speed in the crushing process is 40000r/min, the crushing time is 10min, the interval is 10min every 5min of operation, and the obtained powder is collected to obtain the electromagnetic interference material.

Comparative example 3

S1, dissolving 5.82g of resorcinol in 60mL of deionized water, fully stirring, adding 7.84mL of formaldehyde solution when the resorcinol is completely dissolved, stirring for 20min, then adding 0.11g of anhydrous sodium carbonate, stirring for 20min, adding deionized water to 90mL when the resorcinol is completely dissolved, and stirring for 5min to obtain a reaction solution; adding 1g of electromagnetic shielding reinforcing agent into the reaction solution, and stirring for 10 min;

s2, placing the reaction solution at 80 ℃ for full gelation and aging to obtain wet gel; placing the wet gel in 15% ferric nitrate solution (the mass of ferric nitrate is 0.7134g), and fully soaking for 3 days;

s3, putting the fully-soaked wet gel containing the iron salt into a container filled with fresh acetone for solvent exchange, and replacing the acetone every day for 5 days; placing the wet gel after solvent exchange in supercritical carbon dioxide extraction apparatus, and subjecting to CO treatment at 45 deg.C and 200bar₂Supercritical drying to obtain aerogel;

s4, carbonizing the obtained aerogel in a tube furnace under the protection of flowing argon, slowly raising the temperature from room temperature to 150 ℃, vacuumizing, and keeping for 2 hours; then introducing argon at the air flow rate of 50mL/min, slowly heating from 150 ℃ to 1050 ℃ at the heating rate of 0.6 ℃/min, preserving heat, carbonizing and reducing for 3 hours, and naturally cooling to room temperature to obtain the carbon aerogel based electromagnetic shielding material;

the preparation method of the electromagnetic shielding reinforcing agent comprises the following steps: adding 15g of modified graphene oxide, 3g of modified diatomite, 1g of aluminate coupling agent and 100g of deionized water into a supercritical reaction device, sealing the system, introducing carbon dioxide to 35MPa, stirring for 120min at 65 ℃, relieving pressure, filtering and drying to obtain an electromagnetic shielding reinforcing agent;

the preparation method of the modified graphene oxide comprises the following steps: placing the graphene oxide in a low-temperature plasma treatment instrument for treatment for 15min to obtain pretreated graphene oxide; preparing a dopamine acid solution, adjusting the pH value to 10, then adding pretreated graphene oxide into the dopamine acid solution for soaking, oscillating for 36 hours in a dark place, then separating the pretreated graphene oxide, drying at 35 ℃, taking 15g of dried material, 3g of hexadecyl trimethyl ammonium bromide and 100g of deionized water, stirring and mixing, then carrying out ultrasonic treatment for 60min, and obtaining modified graphene oxide; in the ultrasonic process, introducing nano bubbles into the mixed feed liquid;

the atmosphere of the low-temperature plasma treatment instrument is oxygen; the frequency of the low-temperature plasma processor is 45KHz, the power is 40W, and the pressure of oxygen is 25 Pa; the nano bubbles are oxygen; the ultrasonic treatment frequency is 45KHz, the ultrasonic power density is 1200W/L, the ultrasonic adopts intermittent irradiation, and the irradiation time/irradiation stopping time of the intermittent irradiation is 20s/10 s; the concentration of the dopamine acid solution is 10 mg/mL; the mass ratio of the pretreated graphene oxide to the dopamine hydrochloric acid solution is 1: 10;

the preparation method of the modified diatomite comprises the following steps: calcining kieselguhr for 2 hours at 400 ℃, adding 15g of calcined kieselguhr, 2g of sodium lignosulfonate and 100g of 1% copper nitrate solution by mass into a sealed container, introducing nitrogen into the sealed container to saturate the nitrogen, sealing, then placing the sealed container in an electron accelerator of 2.5MeV and 40mA for irradiation stirring treatment, and after the treatment is finished, carrying out reduced pressure concentration, filtration and drying to obtain modified kieselguhr; the irradiation dose rate adopted by irradiation is 100kGy/h, and the irradiation dose is 400 kGy.

Crushing the carbon aerogel based electromagnetic shielding material prepared by the comparative example to obtain carbon aerogel based electromagnetic shielding material powder, and blowing 5m of the carbon aerogel based electromagnetic shielding material powder in a target area by using a blower²Blowing powder at a wind speed of 1g/m³The average electromagnetic interference performance of the carbon aerogel based electromagnetic shielding material prepared by the comparative example on visible light and infrared light and the effective shielding time are tested, and the results are shown in table 1.

Comparative example 4

S1 preparation of sol

Weighing 5.5g of resorcinol in a beaker, adding 10g of sodium carbonate solution with the mass fraction of 1% into the beaker, then weighing 59g of deionized water in the beaker, and carrying out magnetic stirring until the resorcinol is completely dissolved to obtain a precursor solution; then weighing 20mL of 26g/L graphene oxide solution, adding the solution into the precursor solution, stirring for 5min, and performing ultrasonic treatment for 20min to obtain a precursor mixed solution containing graphene oxide; and weighing 9g of formaldehyde, adding the formaldehyde into the precursor mixed solution containing the graphene oxide, and magnetically stirring for 5min to obtain the phenolic sol containing the graphene oxide.

S2 and preparation of graphene oxide composite phenolic aerogel

Subpackaging the prepared phenolic sol containing graphene oxide, sealing, and placing in an oven at 80 ℃ for gelling and aging for 3 days; carefully separating the gelled and aged gel from the container, placing the gel in a container containing ethanol, wherein the volume of the ethanol is 10 times that of the gel, performing solvent replacement for 3 days, and repeating the step for 3 times to finish the solvent replacement process; and finally, placing the stainless steel cylinder filled with the wet gel in an autoclave, adding absolute ethyl alcohol into the autoclave, sealing to ensure that the liquid pressure reaches 15.0MPa and the temperature reaches 25 ℃, maintaining the pressure and the temperature for 24 hours, and then slowly discharging fluid at constant temperature to finally obtain the graphene oxide composite phenolic aerogel product.

S3, preparation of graphene composite carbon aerogel

And (3) carrying out a cracking process on the graphene oxide composite phenolic aerogel prepared by supercritical drying under the protection of nitrogen, wherein the cracking temperature is 1000 ℃, and the time is 6 hours, so as to obtain the graphene composite carbon aerogel.

S4 preparation of electromagnetic shielding material

And (2) crushing the graphene composite carbon aerogel in a high-speed crusher at the rotation speed of 34000r/min for 15min, wherein the interval of 10min is 5min every time, and collecting the obtained powder, namely the electromagnetic shielding material.

S5, spreading electromagnetic shielding material

Using a blower at 2.5m in the target area²Blowing and scattering the powder of the electromagnetic shielding material at a wind speed of/min, wherein the scattering density is 1g/m³。

The size of the gel nano-particles of the graphene composite carbon aerogel prepared by the comparative example is 15 nm; the density of the electromagnetic shielding material prepared in this comparative example was 0.18g/cm³Within 0-5 min, the electromagnetic interference performance (electromagnetic shielding performance) on visible light is more than 90%, and the electromagnetic interference performance on infrared light is more than 75%.

Comparative example 5

S1, dissolving 5.82g of resorcinol in 60mL of deionized water, fully stirring, adding 7.84mL of formaldehyde solution when the resorcinol is completely dissolved, stirring for 20min, then adding 0.11g of anhydrous sodium carbonate, stirring for 20min, adding deionized water to 90mL when the resorcinol is completely dissolved, and stirring for 5min to obtain a reaction solution;

s4, carbonizing the obtained aerogel in a tube furnace under the protection of flowing argon, slowly raising the temperature from room temperature to 150 ℃, vacuumizing, and keeping for 2 hours; then introducing argon gas at the gas flow rate of 50mL/min, slowly heating from 150 ℃ to 1050 ℃ at the heating rate of 0.6 ℃/min, preserving heat, carbonizing and reducing for 3h, and naturally cooling to room temperature to obtain the carbon aerogel based electromagnetic shielding material.

S5, carrying out freeze drying on the neutral graphene oxide aqueous dispersion to obtain graphene oxide powder, adding 100mg of graphene oxide powder into 3.2g of deionized water, and placing the mixture in a cell crusher to be treated for 20min under the power of 60W to obtain the graphene oxide aqueous dispersion with the mass fraction of 3%; cutting open-cell polyimide foam into cubic blocks of 0.9g, soaking the cubic blocks in the graphene oxide aqueous dispersion, repeatedly extruding the polyimide foam to enable the graphene oxide aqueous dispersion to be uniformly adsorbed in pores of the polyimide foam, wherein the mass ratio of the polyimide foam to the graphene oxide is 9:1, and performing vacuum drying to obtain a graphene oxide-based foam composite material; and (3) placing the foam composite material based on the graphene oxide into a hydriodic acid solution with the mass fraction of 0.5%, refluxing for 3h at 90 ℃, washing with water, and drying to obtain the foam composite material based on the reduced graphene oxide.

S6, crushing the reduced graphene oxide-based foam composite material and the carbon aerogel-based electromagnetic shielding material in a high-speed crusher, wherein the mass ratio of the reduced graphene oxide-based foam composite material to the carbon aerogel-based electromagnetic shielding material is 1:1, the rotation speed in the crushing process is 40000r/min, the crushing time is 10min, the interval is 10min every 5min, and the mixed electromagnetic shielding material powder is obtained by collecting.

S7, adopting a blower to move 5m in the target area²Blowing the mixed electromagnetic shielding material powder at a wind speed of/min, wherein the distribution density is 1g/m³。

In particular, the notation-indicates that the index was not tested.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. a preparation method of super-hybrid aerogel electromagnetic interference material, is characterized in that, described method comprises the steps:

(1) phenolic substance and weak basic catalyst are prepared into precursor solution with water, then graphene oxide solution is dispersed in the precursor solution, obtains the precursor mixed solution comprising graphene oxide, and then goes to the described precursor solution containing graphene oxide. Adding aldehydes to the precursor mixture solution of graphene oxide and mixing uniformly to prepare a novolak sol containing graphene oxide;

(2) gelling and aging the phenolic sol containing graphene oxide obtained in step (1) to obtain a wet gel, and then placing the wet gel in a magnetic salt solution and dipping to obtain a magnetic salt-containing wet gel Then, the magnetic salt-containing wet gel is sequentially subjected to a solvent replacement step and a drying step to obtain a super-hybrid phenolic aerogel;

(3) pyrolyzing the super-hybrid phenolic aerogel obtained in step (2) to obtain a super-hybrid carbon aerogel;

(4) pyrolyzing the polyimide foam after heat treatment at 100-300° C. for 1-12 hours, to obtain a cracked polyimide foam; in step (4), the temperature of the pyrolysis is 1000 ℃ ~1200℃, the high temperature cracking time is 1 ~ 4h;

(5) mixing and pulverizing the cracked polyimide foam obtained in step (4) and the super-hybrid carbon aerogel obtained in step (3) according to a mass ratio of 1:(2-4) to obtain a super-hybrid Aerogel electromagnetic interference material.

2. preparation method according to claim 1, is characterized in that:

The magnetic salt solution is an iron salt solution and/or a cobalt salt solution; and/or

In step (4), the polyimide foam having a density of 0.01-0.5 g/cm ³ after heat treatment at 100-300° C. for 1-12 hours is pyrolyzed to obtain the cracked polyimide foam .

3. preparation method according to claim 2, is characterized in that:

The ferric salt solution is a ferric chloride solution and/or a ferric nitrate solution; and/or

The cobalt salt solution is a cobalt dichloride solution and/or a cobalt nitrate solution.

4. preparation method according to claim 1, is characterized in that:

The concentration of the magnetic salt solution is 0.1-10 g/L; and/or

In step (2), the dipping time is 1-10 days.

5. preparation method according to claim 1, is characterized in that:

In step (3), the temperature of the high-temperature cracking is 500-1500° C., and the time of the high-temperature cracking is 1-10 h.

6. according to the preparation method described in any one of claim 1 to 5, it is characterized in that:

The concentration of the weakly basic catalyst is 0.1-5wt%;

The concentration of the graphene oxide solution is 1～100g/L;

The mass ratio of the phenolic substance, the weakly basic catalyst with a concentration of 0.1 to 5wt%, water, the graphene oxide solution with a concentration of 1 to 100 g/L and the amount of aldehydes is (1 to 500): (1 to 100): (1 to 200): (0.001 to 10): (1 to 100); and/or

The mass percentage content of graphene in the super-hybrid aerogel electromagnetic interference material is 1% to 8%.

7. The preparation method according to any one of claims 1 to 5, wherein:

The phenolic substance is selected from the group consisting of phenol, resorcinol, phloroglucinol, cresol, xylenol, mixed cresol and nonylphenol;

The aldehydes are selected from the group consisting of formaldehyde, paraformaldehyde, furfural and acetaldehyde; and/or

The weakly basic catalyst is sodium carbonate solution.

8. preparation method according to any one of claim 1 to 5, is characterized in that:

In step (2), the temperature for gelation and aging is 20-90° C., and the time for gelation and aging is 1-8 days; and/or

In step (2), the solvent replacement is performed in an alcohol solvent or a ketone solvent, the solvent replacement time is 1 to 8 days, and the solvent replacement is repeated for 1 to 5 times;

The alcohol solvent is selected from the group consisting of methanol, ethanol, propanol and isopropanol;

The ketone solvent is selected from the group consisting of butanone and acetone; and/or

In step (2), the drying is supercritical drying, and the supercritical drying uses dehydrated alcohol as a drying medium;

The supercritical drying using absolute ethanol as the drying medium includes: after performing the solvent replacement step on the wet gel containing the magnetic salt, placing it in a supercritical drying equipment and placing the supercritical drying equipment in an autoclave, and placing the supercritical drying equipment in an autoclave. Add absolute ethanol and seal it, so that the pressure in the autoclave is 5-30 MPa, the temperature is 0-40 °C, the pressure and temperature are maintained for 1-48 hours, and then the absolute ethanol and the fluid produced in the drying process are discharged to obtain Super-hybrid phenolic aerogel.

9. preparation method according to any one of claim 1 to 5, is characterized in that:

In step (5), the cracked polyimide foam and the super-hybrid carbon aerogel are placed in a high-speed pulverizer for the mixed pulverization. During the mixed pulverization process, the The rotating speed of the high-speed pulverizer is 10,000-100,000 r/min, and the mixing and pulverizing time is 1-30 min.

10. The super-hybrid aerogel electromagnetic interference material prepared by the preparation method of any one of claims 1 to 9.