CN117986678A - Intelligent adjustable electromagnetic wave absorption composite aerogel based on temperature driving and preparation method thereof - Google Patents
Intelligent adjustable electromagnetic wave absorption composite aerogel based on temperature driving and preparation method thereof Download PDFInfo
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- 239000004964 aerogel Substances 0.000 title claims abstract description 53
- 238000010521 absorption reaction Methods 0.000 title claims abstract description 22
- 238000002360 preparation method Methods 0.000 title claims abstract description 21
- 239000002131 composite material Substances 0.000 title claims abstract description 16
- 229910021542 Vanadium(IV) oxide Inorganic materials 0.000 claims abstract description 50
- GRUMUEUJTSXQOI-UHFFFAOYSA-N vanadium dioxide Chemical compound O=[V]=O GRUMUEUJTSXQOI-UHFFFAOYSA-N 0.000 claims abstract description 50
- 239000004760 aramid Substances 0.000 claims abstract description 46
- 229920003235 aromatic polyamide Polymers 0.000 claims abstract description 43
- 239000002121 nanofiber Substances 0.000 claims abstract description 43
- 239000002041 carbon nanotube Substances 0.000 claims abstract description 39
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 27
- 229910021393 carbon nanotube Inorganic materials 0.000 claims abstract description 27
- 239000000843 powder Substances 0.000 claims abstract description 26
- 239000006185 dispersion Substances 0.000 claims abstract description 18
- 125000000524 functional group Chemical group 0.000 claims abstract description 18
- 125000002924 primary amino group Chemical group [H]N([H])* 0.000 claims abstract description 18
- 239000007788 liquid Substances 0.000 claims abstract description 16
- 239000000945 filler Substances 0.000 claims abstract description 13
- 238000004108 freeze drying Methods 0.000 claims abstract description 8
- 230000004048 modification Effects 0.000 claims abstract description 8
- 238000012986 modification Methods 0.000 claims abstract description 8
- 238000002156 mixing Methods 0.000 claims abstract description 7
- 238000013329 compounding Methods 0.000 claims abstract description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 30
- 238000000034 method Methods 0.000 claims description 20
- 238000003756 stirring Methods 0.000 claims description 17
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 11
- 238000001035 drying Methods 0.000 claims description 11
- 238000004140 cleaning Methods 0.000 claims description 9
- WYTZZXDRDKSJID-UHFFFAOYSA-N (3-aminopropyl)triethoxysilane Chemical compound CCO[Si](OCC)(OCC)CCCN WYTZZXDRDKSJID-UHFFFAOYSA-N 0.000 claims description 6
- 238000009210 therapy by ultrasound Methods 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims 1
- 230000033228 biological regulation Effects 0.000 abstract description 4
- 239000006096 absorbing agent Substances 0.000 abstract description 2
- 239000000243 solution Substances 0.000 description 27
- 239000008367 deionised water Substances 0.000 description 22
- 229910021641 deionized water Inorganic materials 0.000 description 22
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 description 21
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 21
- 239000011358 absorbing material Substances 0.000 description 11
- GNTDGMZSJNCJKK-UHFFFAOYSA-N divanadium pentaoxide Chemical compound O=[V](=O)O[V](=O)=O GNTDGMZSJNCJKK-UHFFFAOYSA-N 0.000 description 10
- 238000000227 grinding Methods 0.000 description 10
- 238000006243 chemical reaction Methods 0.000 description 9
- 230000000052 comparative effect Effects 0.000 description 7
- 229920006231 aramid fiber Polymers 0.000 description 6
- 230000008859 change Effects 0.000 description 6
- 238000001291 vacuum drying Methods 0.000 description 6
- YASYEJJMZJALEJ-UHFFFAOYSA-N Citric acid monohydrate Chemical compound O.OC(=O)CC(O)(C(O)=O)CC(O)=O YASYEJJMZJALEJ-UHFFFAOYSA-N 0.000 description 5
- 229960002303 citric acid monohydrate Drugs 0.000 description 5
- 238000003760 magnetic stirring Methods 0.000 description 4
- 239000011259 mixed solution Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- 238000005406 washing Methods 0.000 description 4
- 230000027311 M phase Effects 0.000 description 3
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 3
- 238000007605 air drying Methods 0.000 description 3
- 238000000137 annealing Methods 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 238000001027 hydrothermal synthesis Methods 0.000 description 3
- 238000010907 mechanical stirring Methods 0.000 description 3
- 239000004570 mortar (masonry) Substances 0.000 description 3
- 239000012299 nitrogen atmosphere Substances 0.000 description 3
- -1 polytetrafluoroethylene Polymers 0.000 description 3
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 3
- 239000004810 polytetrafluoroethylene Substances 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 238000000967 suction filtration Methods 0.000 description 3
- 239000006228 supernatant Substances 0.000 description 3
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- 238000011161 development Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 230000010287 polarization Effects 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
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- 238000007796 conventional method Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000005670 electromagnetic radiation Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 238000007710 freezing Methods 0.000 description 1
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- 239000007789 gas Substances 0.000 description 1
- 230000036541 health Effects 0.000 description 1
- 239000000017 hydrogel Substances 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000002715 modification method Methods 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000012782 phase change material Substances 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/28—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by elimination of a liquid phase from a macromolecular composition or article, e.g. drying of coagulum
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/009—Use of pretreated compounding ingredients
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- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
- H05K9/00—Screening of apparatus or components against electric or magnetic fields
- H05K9/0073—Shielding materials
- H05K9/0081—Electromagnetic shielding materials, e.g. EMI, RFI shielding
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2377/00—Characterised by the use of polyamides obtained by reactions forming a carboxylic amide link in the main chain; Derivatives of such polymers
- C08J2377/10—Polyamides derived from aromatically bound amino and carboxyl groups of amino carboxylic acids or of polyamines and polycarboxylic acids
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Abstract
The invention discloses an intelligent adjustable electromagnetic wave absorption composite aerogel based on temperature driving and a preparation method thereof, comprising the following steps: carrying out surface modification on vanadium dioxide powder to obtain vanadium dioxide with amino functional groups on the surface; compounding vanadium dioxide with amino functional groups on the surface with carboxylated carbon nano tubes to obtain wave-absorbing fillers; uniformly mixing the wave-absorbing filler and the aramid nanofiber dispersion liquid, and then freeze-drying to obtain the CNTs/VO 2/ANF mixed aerogel. The aerogel prepared by the invention has different dielectric properties at different temperatures, and opens up a road for intelligent regulation and control application of the electromagnetic absorber under temperature driving.
Description
Technical Field
The invention belongs to the technical field of wave absorbing materials, and particularly relates to intelligent adjustable electromagnetic wave absorbing composite aerogel based on temperature driving and a preparation method thereof.
Background
The rapid development of the information age has led to the widespread use of electromagnetic wave technology in the fields of communication technology, electronic equipment, military, etc. However, the aggravated electromagnetic pollution and radiation also pose a threat to human health and information security. The urgent need to efficiently treat electromagnetic pollution and absorb electromagnetic radiation has attracted great attention to the development of efficient electromagnetic wave absorbing materials. At present, the wave absorbing properties of most wave absorbing materials are fixed after the preparation is finished, and dynamic regulation and control cannot be realized. In the face of complex practical application environments and fields, the single electromagnetic wave absorption performance cannot meet the requirements. Therefore, new requirements for intelligent controllability are put on the current electromagnetic wave absorbing materials.
The aerogel has the physical characteristics of ultralow density, high porosity, large specific surface area and low dielectric constant, and has great potential for adjusting and controlling electromagnetic wave absorption. Vanadium dioxide (VO 2) is a phase change material, and a phenomenon in which a temperature-driven metal-insulator phase transition (MIT) occurs at a temperature around 68 ℃. Meanwhile, the conductivity of the VO 2 can be greatly changed in the phase change process, so that the VO 2 has potential application in the wave-absorbing field. Therefore, the invention provides the intelligent adjustable electromagnetic wave absorption composite aerogel based on temperature driving and the preparation method thereof, so as to realize the intelligent real-time adjustable function of electromagnetic absorption.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides the intelligent adjustable electromagnetic wave absorption composite aerogel based on temperature driving and the preparation method thereof, which solve the problem that the traditional wave absorbing material is difficult to implement and regulate the wave absorbing performance. The aerogel prepared by the method can realize the adjustable wave absorption frequency and the switchable wave absorption function based on temperature driving.
In order to achieve the technical purpose, the invention adopts the following technical scheme:
The intelligent adjustable electromagnetic wave absorption composite aerogel based on temperature driving and the preparation method thereof comprise the following steps: carrying out surface modification on vanadium dioxide powder to obtain vanadium dioxide with amino functional groups on the surface; compounding vanadium dioxide with amino functional groups on the surface with carboxylated carbon nano tubes to obtain wave-absorbing fillers; uniformly mixing the wave-absorbing filler and the aramid nanofiber dispersion liquid, and then freeze-drying to obtain the CNTs/VO 2/ANF mixed aerogel.
Further, the preparation method of the vanadium dioxide powder comprises the following steps: adding vanadium pentoxide and citric acid monohydrate into deionized water, magnetically stirring to orange, performing hydrothermal reaction, centrifugally drying, performing high-temperature annealing treatment, and grinding the treated solid to obtain VO 2 powder.
Further, the mass ratio of citric acid monohydrate to vanadium pentoxide is 1.775:1; the hydrothermal reaction temperature is 180 ℃; the high-temperature annealing treatment procedure lasts for 3-5 hours at 450 ℃, and the heating rate is not higher than 3 ℃/min; the protective gas for high-temperature annealing is argon or nitrogen.
Further, the surface modification method for the vanadium dioxide powder comprises the following steps: mixing vanadium dioxide with absolute ethyl alcohol, performing ultrasonic treatment, adding APTES, magnetically stirring, and centrifuging to obtain vanadium dioxide with amino functional groups on the surface.
Further, the ratio of vanadium dioxide powder to APTES was 0.473g: 25. Mu.L.
Further, the method for compounding vanadium dioxide with amino functional groups on the surface and carboxylated carbon nano tubes comprises the following steps: mixing vanadium dioxide with amino functional groups on the surface with carboxylated carbon nano tubes in water, magnetically stirring under the water bath condition, and then cleaning and drying to obtain the wave-absorbing filler.
Further, the water bath temperature is 90 ℃, and the magnetic stirring time is 1h.
Further, the preparation method of the aramid nanofiber dispersion liquid comprises the following steps: adding aramid fiber into dimethyl sulfoxide solution containing potassium hydroxide, stirring to crack the aramid fiber into aramid nanofiber, and washing with deionized water to replace the dimethyl sulfoxide solution to obtain aramid nanofiber dispersion.
Further, in the dimethyl sulfoxide solution containing potassium hydroxide, the mass concentration of the potassium hydroxide is 2-3 mg/ml; the stirring time is 5-7 days.
Further, the freeze-drying temperature is-50 to-30 ℃.
Further, the ratio of the carboxylated carbon nanotubes to the dispersion liquid of vanadium dioxide and aramid nanofibers with amino functional groups on the surface is (0.024-0.040) g: (0.072 to 0.120 g): 16g; in the aramid nanofiber dispersion liquid, the mass concentration of the aramid nanofibers is 9-11 mg/g.
Further, the ratio of the carboxylated carbon nanotubes to the dispersion liquid of vanadium dioxide and aramid nanofibers with amino functional groups on the surface is (0.024-0.040) g: (0.120-0.200 g): 16g; in the aramid nanofiber dispersion liquid, the mass concentration of the aramid nanofibers is 9-11 mg/g.
Further, the ratio of the carboxylated carbon nanotubes to the dispersion liquid of vanadium dioxide and aramid nanofibers with amino functional groups on the surface is (0.072-0.088) g: (0.360-0.440) g:16g; in the aramid nanofiber dispersion liquid, the mass concentration of the aramid nanofibers is 9-11 mg/g.
The invention also provides aerogel with adjustable wave absorption frequency, which is prepared by the method.
The invention also provides aerogel with the wave absorbing function from closed to open, which is prepared by the method.
The invention also provides aerogel with the wave absorbing function from on to off, which is prepared by the method.
The beneficial effects are that:
The aerogel structure with a porous structure and adjustable wave absorbing performance is prepared by a hydrothermal method and a freeze drying method, wherein vanadium dioxide is used as an adjusting and controlling filler, and carboxylated carbon nanotubes are used as the wave absorbing filler and the vanadium dioxide are uniformly distributed on aramid nanofibers serving as an aerogel framework. The phase change behavior of vanadium dioxide is benefited, and the vanadium dioxide has different dielectric properties at different temperatures, so that the application of the wave absorbing property in the aspect of intelligent regulation is facilitated. The aerogel of the aramid nanofiber skeleton has a porous structure, and helps electromagnetic waves enter the material. Through the addition of the wave-absorbing filler, the aerogel with different VO 2 filling amounts causes multiple polarization effects with different degrees, so that the frequency tunable electromagnetic wave absorption performance and the switching function switchable function can be realized under the driving of temperature.
Drawings
FIG. 1 is a flow chart of the process of the present invention;
FIGS. 2 to 3 are photographs of aerogels prepared in example 1;
FIG. 4 is a photograph of an aerogel prepared in comparative example 1;
FIG. 5 is an SEM image and EDS image of the wave-absorbing filler prepared in example 2;
FIG. 6 is an electromagnetic parameter chart of example 1;
FIG. 7 is an electromagnetic parameter chart of example 2;
FIG. 8 is an electromagnetic parameter chart of example 3;
FIG. 9 is a graph of electromagnetic parameters of comparative example 1;
fig. 10 is a graph of the wave absorbing performance of examples 1 to 3 and comparative example 1.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. It will be apparent that the described embodiments are some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The experimental methods used in the examples below, unless otherwise indicated, are conventional methods, and the reagents, methods and apparatus used, unless otherwise indicated, are conventional in the art.
Example 1
The embodiment provides an aerogel with a frequency tunable function, and the preparation method comprises the following steps:
(1) Preparing vanadium dioxide powder:
56ml deionized water, 1.065g citric acid monohydrate, and 0.6g vanadium pentoxide were added in a 100ml beaker. The solution was changed from cloudy to orange by magnetic stirring for 15min, then transferred to a 100ml polytetrafluoroethylene reaction kettle, sealed and placed in a forced air drying oven at 180 ℃ for reaction for 6h. And after the reaction is finished, naturally cooling to room temperature, pouring out dark blue transparent supernatant, and alternately cleaning the black product at the bottom with deionized water and absolute ethyl alcohol for three times respectively. After drying in a vacuum oven at 60℃for 6 hours, phase B VO 2 powder (VO 2 (B)) was obtained by grinding with an agate mortar. Subsequently, it was annealed at 450 ℃ for 5 hours in an N 2 atmosphere, and ground to obtain M-phase VO 2 powder (VO 2 (M)).
(2) Surface modification of vanadium dioxide:
In a 250ml beaker, 0.473g of VO 2 (M), 100ml of absolute ethanol and 1ml of deionized water were added and dispersed ultrasonically for 1h. Then 25 mu L of APTES is added, magnetically stirred for 5 hours and centrifuged; washing with absolute ethanol for 3 times, drying in a vacuum drying oven at 40deg.C for 8 hr, and grinding to obtain VO 2 @APTES powder (VA).
(3) Preparing a wave absorbing material:
Adding carboxylated carbon nanotubes (COOH-CNTS) and VA into a beaker containing a proper amount of deionized water according to the mass ratio of 1:3, magnetically stirring for 1h at the water bath of 90 ℃, then drying for 4h at the temperature of 80 ℃ in a vacuum drying oven, and grinding to obtain carboxylated carbon nanotubes and vanadium dioxide modified powder with the mass ratio of 1:3.
(4) Preparing an aramid nanofiber solution:
1.5L of dimethyl sulfoxide solution, 3g of aramid nanofibers and 4.5g of potassium hydroxide are respectively added into a three-necked flask, and the aramid fibers are cracked by mechanical stirring for 5 days by using a stirring paddle; and repeatedly cleaning the solution in a suction filtration bottle by using deionized water, replacing dimethyl sulfoxide in the mixed solution, adding a proper amount of deionized water, and adjusting the concentration of the obtained Aramid Nanofiber (ANF) solution to 10mg/g.
(5) Preparing CNTs/VO 2/ANF mixed aerogel:
16g of ANF solution is placed in a self-made 4 x 2cm mould, and 0.128g of the wave-absorbing material prepared in the step (3) (modified powder with the mass ratio of carboxylated carbon nano tubes to vanadium dioxide being 1:3) is added. After stirring uniformly, freezing the sample at-40 ℃, and then freeze-drying for 120 hours to obtain CNTs/VO 2/ANF aerogel with frequency tunable function. Referring to FIGS. 2 to 3, it can be seen from FIG. 3 that the CNTs/VO 2/ANF aerogel prepared in this example is light.
Example 2
The embodiment provides an aerogel with a wave absorbing function from off to on, and the preparation method comprises the following steps:
(1) Preparing vanadium dioxide powder:
56ml deionized water, 1.065g citric acid monohydrate, and 0.6g vanadium pentoxide were added in a 100ml beaker. The solution was changed from cloudy to orange by magnetic stirring for 15min, then transferred to a 100ml polytetrafluoroethylene reaction kettle, sealed and placed in a forced air drying oven at 180 ℃ for reaction for 6h. And after the reaction is finished, naturally cooling to room temperature, pouring out dark blue transparent supernatant, and alternately cleaning the black product at the bottom with deionized water and absolute ethyl alcohol for three times respectively. After drying in a vacuum oven at 60℃for 6 hours, phase B VO 2 powder (VO 2 (B)) was obtained by grinding with an agate mortar. Subsequently, it was annealed at 450 ℃ for 5 hours in an N 2 atmosphere, and ground to obtain M-phase VO 2 powder (VO 2 (M)).
(2) Surface modification of vanadium dioxide:
In a 250ml beaker, 0.473g of VO 2 (M), 100ml of absolute ethanol and 1ml of deionized water were added and dispersed ultrasonically for 1h. Then 25 mu L of APTES is added, magnetically stirred for 5 hours and centrifuged; washing with absolute ethanol for 3 times, drying in a vacuum drying oven at 40deg.C for 8 hr, and grinding to obtain VO 2 @APTES powder (VA).
(3) Preparing a wave absorbing material:
Carboxylated carbon nanotubes (COOH-CNTS) and VA are added into a beaker containing proper amount of deionized water according to the mass ratio of 1:5, magnetically stirred for 1h at the water bath of 90 ℃, then dried for 4h at the temperature of 80 ℃ in a vacuum drying oven, and the carboxylated carbon nanotubes and vanadium dioxide modified powder with the mass ratio of 1:5 is obtained after grinding (figure 5).
(4) Preparing an aramid nanofiber solution:
1.5L of dimethyl sulfoxide solution, 3g of aramid nanofibers and 4.5g of potassium hydroxide are respectively added into a three-necked flask, and the aramid fibers are cracked by mechanical stirring for 5 days by using a stirring paddle; and repeatedly cleaning the solution in a suction filtration bottle by using deionized water, replacing dimethyl sulfoxide in the mixed solution, adding a proper amount of deionized water, and adjusting the concentration of the obtained aramid nanofiber solution to 10mg/g.
(5) Preparing CNTs/VO 2/ANF mixed aerogel:
16g of ANF solution is placed in a self-made 4 x 2cm mould, and 0.192g of the wave-absorbing material prepared in the step (3) (modified powder with the mass ratio of carboxylated carbon nano tubes to vanadium dioxide being 1:5) is added. After stirring uniformly, the sample was frozen at-40 ℃ and then freeze-dried for 120 hours to obtain CNTs/VO 2/ANF aerogel with wave-absorbing function from off to on.
Example 3
The embodiment provides aerogel with a wave absorbing function from on to off, and the preparation method comprises the following steps:
(1) Preparing vanadium dioxide powder:
56ml deionized water, 1.065g citric acid monohydrate, and 0.6g vanadium pentoxide were added in a 100ml beaker. The solution was changed from cloudy to orange by magnetic stirring for 15min, then transferred to a 100ml polytetrafluoroethylene reaction kettle, sealed and placed in a forced air drying oven at 180 ℃ for reaction for 6h. And after the reaction is finished, naturally cooling to room temperature, pouring out dark blue transparent supernatant, and alternately cleaning the black product at the bottom with deionized water and absolute ethyl alcohol for three times respectively. After drying in a vacuum oven at 60℃for 6 hours, phase B VO 2 powder (VO 2 (B)) was obtained by grinding with an agate mortar. Subsequently, it was annealed at 450 ℃ for 5 hours in an N 2 atmosphere, and ground to obtain M-phase VO 2 powder (VO 2 (M)).
(2) Surface modification of vanadium dioxide:
In a 250ml beaker, 0.473g of VO 2 (M), 100ml of absolute ethanol and 1ml of deionized water were added and dispersed ultrasonically for 1h. Then 25 mu L of APTES is added, magnetically stirred for 5 hours and centrifuged; washing with absolute ethanol for 3 times, drying in a vacuum drying oven at 40deg.C for 8 hr, and grinding to obtain VO 2 @APTES powder (VA).
(3) Preparing a wave absorbing material:
Adding carboxylated carbon nanotubes (COOH-CNTS) and VA into a beaker containing a proper amount of deionized water according to the mass ratio of 1:5, magnetically stirring for 1h at the water bath of 90 ℃, then drying for 4h at the temperature of 80 ℃ in a vacuum drying oven, and grinding to obtain carboxylated carbon nanotubes and vanadium dioxide modified powder with the mass ratio of 1:5.
(4) Preparing an aramid nanofiber solution:
1.5L of dimethyl sulfoxide solution, 3g of aramid nanofibers and 4.5g of potassium hydroxide are respectively added into a three-necked flask, and the aramid fibers are cracked by mechanical stirring for 5 days by using a stirring paddle; and repeatedly cleaning the solution in a suction filtration bottle by using deionized water, replacing dimethyl sulfoxide in the mixed solution, adding a proper amount of deionized water, and adjusting the concentration of the obtained aramid nanofiber solution to 10mg/g.
(5) Preparing CNTs/VO 2/ANF mixed aerogel:
16g of ANF solution is placed in a self-made 4 x 2cm mould, and 0.48g of the wave-absorbing material prepared in the step (3) (modified powder with the mass ratio of carboxylated carbon nano tubes to vanadium dioxide being 1:5) is added. After stirring uniformly, the sample was frozen at-40 ℃ and then freeze-dried for 120 hours to obtain CNTs/VO 2/ANF aerogel with wave-absorbing function from on to off.
Comparative example 1
This comparative example provides for the preparation of carbon nanotube/aramid nanofiber aerogel comprising the steps of:
(1) Preparation of an aramid nanofiber dispersion:
1.5L of dimethyl sulfoxide solution, 3g of aramid nanofiber and 4.5g of potassium hydroxide are respectively added into a three-necked flask, the aramid nanofiber is mechanically stirred for 5 days by using a stirring paddle, the aramid fiber is cracked, then deionized water is used for repeatedly cleaning in a suction filter flask, dimethyl sulfoxide in the mixed solution is replaced, and a proper amount of deionized water is added, so that the concentration of the obtained aramid nanofiber solution is regulated to 10mg/g.
(2) Preparation of carbon nanotube/aramid nanofiber aerogel:
16g of ANF solution was placed in a homemade 4 x 2cm mold, while 0.032g of carbon nanotubes were added. After stirring well, the samples were frozen at-40 ℃ and subsequently freeze-dried for 120h to give CNTs/ANF aerogel (figure 4).
Effect test
The samples of examples 1, 2, 3 and comparative example 1 were cut into rectangular blocks of 22.84mm by 10.13mm in size, and the temperature-varying electromagnetic parameters of the different aerogels at the X-band (8.2-12.4 GHz) were tested by waveguide method in a high Wen Bodao test fixture Ceyear vector network analyzer with an in-situ heating platform.
Test results:
As can be seen from 6 to 9, in the X-band, the dielectric real part and the imaginary part of the samples in examples 1 to 3 of the present invention are significantly changed as compared with comparative example 1, and increase with increasing temperature.
In fig. 10, it was found from the calculated wave absorbing performance that example 1 had a function of tuning the frequency in real time as the temperature increased. Embodiment 2 has a switchable function of absorbing waves from off to on. Embodiment 3 has a switchable function of absorbing the waves from on to off. The frequency tunable and wave absorbing switchable functions of embodiments 1-3 are mainly attributed to the fact that the phase change behavior generated by vanadium dioxide with different contents brings about interface polarization effects with other interfaces to different degrees, and the functions are realized by adjusting impedance matching and attenuation constants in cooperation with various loss mechanisms.
The invention provides an intelligent adjustable electromagnetic wave absorption composite aerogel based on temperature driving and a preparation method thereof, wherein vanadium dioxide serving as a filler with adjustable dielectric property is prepared, is respectively modified with carbon nanotubes and then synthesized according to a certain proportion, and is added into hydrogel taking aramid nanofibers as a framework for freeze drying to obtain the intelligent dynamic adjustable CNTs/VO 2/ANF composite aerogel. According to the aerogel with the frequency adjustable and wave absorbing switchable functions prepared by the preparation method, compared with the aerogel without vanadium dioxide, the aerogel with the dielectric constant real part and the dielectric constant imaginary part which are far smaller than those of the aerogel with the vanadium dioxide, and the temperature change is not obvious, the introduction of the vanadium dioxide is shown to increase the dielectric constant and the degree of the vanadium dioxide along with the temperature change through the temperature change test of the vector network analyzer by the waveguide method. In addition, the aerogel with the aramid nanofiber as a framework has a porous structure, so that electromagnetic waves can enter the inside of the material more easily for attenuation. The invention provides insight for the intelligent electromagnetic wave absorption performance and opens up a road for the intelligent regulation and control application of the electromagnetic wave absorber under the drive of temperature.
The above is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above examples, and all technical solutions belonging to the concept of the present invention belong to the protection scope of the present invention. It should be noted that modifications and adaptations to the invention without departing from the principles thereof are intended to be within the scope of the invention as set forth in the following claims.
Claims (10)
1. The preparation method of the intelligent adjustable electromagnetic wave absorption composite aerogel based on temperature driving is characterized by comprising the following steps of:
Carrying out surface modification on vanadium dioxide powder to obtain vanadium dioxide with amino functional groups on the surface;
compounding vanadium dioxide with amino functional groups on the surface with carboxylated carbon nano tubes to obtain wave-absorbing fillers;
Uniformly mixing the wave-absorbing filler and the aramid nanofiber dispersion liquid, and then freeze-drying to obtain the CNTs/VO 2/ANF mixed aerogel.
2. The method for preparing the intelligent adjustable electromagnetic wave absorption composite aerogel based on temperature driving according to claim 1, wherein,
The method for carrying out surface modification on the vanadium dioxide powder comprises the following steps:
Mixing vanadium dioxide with absolute ethyl alcohol, performing ultrasonic treatment, adding APTES, magnetically stirring, and centrifuging to obtain vanadium dioxide with amino functional groups on the surface.
3. The method for preparing the intelligent adjustable electromagnetic wave absorption composite aerogel based on temperature driving according to claim 1, wherein,
The method for compounding vanadium dioxide with amino functional groups on the surface and carboxylated carbon nano tubes comprises the following steps:
Mixing vanadium dioxide with amino functional groups on the surface with carboxylated carbon nano tubes in water, magnetically stirring under the water bath condition, and then cleaning and drying to obtain the wave-absorbing filler.
4. The method for preparing the intelligent adjustable electromagnetic wave absorption composite aerogel based on temperature driving according to claim 1, wherein,
The freeze-drying temperature is-50 to-30 ℃.
5. The method for preparing the intelligent adjustable electromagnetic wave absorption composite aerogel based on temperature driving according to claim 1, wherein,
The proportion of the dispersion liquid of the carboxylated carbon nano tube, the vanadium dioxide with the amino functional group on the surface and the aramid nanofiber is (0.024-0.040) g: (0.072 to 0.120 g): 16g;
in the aramid nanofiber dispersion liquid, the mass concentration of the aramid nanofibers is 9-11 mg/g.
6. The method for preparing the intelligent adjustable electromagnetic wave absorption composite aerogel based on temperature driving according to claim 1, wherein,
The proportion of the dispersion liquid of the carboxylated carbon nano tube, the vanadium dioxide with the amino functional group on the surface and the aramid nanofiber is (0.024-0.040) g: (0.120-0.200 g): 16g;
in the aramid nanofiber dispersion liquid, the mass concentration of the aramid nanofibers is 9-11 mg/g.
7. The method for preparing the intelligent adjustable electromagnetic wave absorption composite aerogel based on temperature driving according to claim 1, wherein,
The proportion of the dispersion liquid of the carboxylated carbon nano tube, the vanadium dioxide with the amino functional group on the surface and the aramid nanofiber is (0.072-0.088) g: (0.360-0.440) g:16g;
in the aramid nanofiber dispersion liquid, the mass concentration of the aramid nanofibers is 9-11 mg/g.
8. An aerogel having an adjustable wave-absorbing frequency produced by the production method according to any one of claims 1 to 5.
9. The aerogel with switchable wave absorbing function prepared by the preparation method according to any one of claims 1 to 4 and 6.
10. The aerogel with switchable wave absorbing function prepared by the preparation method according to any one of claims 1 to 4 and 7.
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