Infrared stealth composite film material capable of being dynamically adjusted at multiple temperatures and preparation method of infrared stealth composite film material

Abstract

The invention belongs to the technical field of infrared stealth protection materials, and provides an infrared stealth composite thin film material capable of being dynamically adjusted at multiple temperatures and a preparation method of the infrared stealth composite thin film material. The preparation method comprises the following steps: firstly, modifying boron nitride by using an MOF material, and compounding the modified boron nitride and microencapsulated blue-phase liquid crystal into VO2 (M) aerogel to prepare composite aerogel; preparing a doped bismuth antimonide film through a co-sputtering method; and finally, coating the bismuth antimonide doped film with the composite aerogel, and drying and curing to obtain the bismuth antimonide doped film. The infrared emissivity of the infrared stealth composite film material is 43% at a low temperature, 40%-58% at a normal temperature and 51% at a high temperature, the temperature response time is 1-3 seconds, and the working temperature range is-30-150 DEG C; the infrared emissivity and the reflectivity are dynamically adjusted at different temperatures, and the coating has certain durability and can be applied to infrared stealth protection of carrying tools.

Description

Technical Field

[0001] This invention relates to the field of infrared stealth protective materials technology, and in particular to an infrared stealth composite thin film material with multi-temperature dynamic adjustment and its preparation method. Background Technology

[0002] In recent years, with the continuous advancement of infrared detection technology and the expansion of its application fields, the research and application of infrared stealth protection technology for vehicles has received increasing attention. The main purpose of this technology is to reduce or alter the thermal radiation characteristics of vehicles on infrared detectors. In military applications, this can reduce the likelihood of being detected and tracked by enemy infrared reconnaissance equipment. For civilian vehicles, it can also be applied in certain situations to protect the privacy of vehicle owners, prevent criminals from using thermal imaging equipment to spy on the interior of the vehicle, and serve as a security measure to make the vehicle less susceptible to detection by infrared detection equipment at night or in concealed environments, increasing the difficulty of illegal intrusion. Therefore, infrared stealth protection technology for vehicles is an important research direction in the military and security fields. This technology is of great significance for improving the survivability of military vehicles and the stealth of civilian vehicles in specific environments. Therefore, a multi-temperature dynamically adjustable infrared stealth composite film material is crucial for the overall infrared stealth protection of the vehicle body.

[0003] Boron nitride has low thermal conductivity, which helps reduce heat transfer and thus reduces infrared radiation caused by thermal conduction. It also has a certain degree of thermal stability. However, it is difficult to disperse uniformly in composite materials, and its interfacial compatibility with the matrix is ​​poor. Thermosensitive nanocapsule composites utilize the thermosensitive properties of blue phase liquid crystals, adjusting their optical properties through temperature response to achieve tunable infrared emissivity. However, its phase transition process is relatively complex. VO2(M) undergoes a metal-insulator transition at around 68℃, and its optical properties also change abruptly under infrared light. The resulting porous aerogel exhibits excellent thermal insulation properties and good chemical stability. Bismuth antimonide also has the characteristics of low infrared emissivity and high infrared reflectivity. Therefore, there is an urgent need to provide a composite thin film material that simultaneously considers the infrared emission and reflection characteristics of materials at different temperatures, while also possessing a certain degree of durability and stability, in order to comprehensively improve infrared stealth effects. Summary of the Invention

[0004] The purpose of this invention is to provide an infrared stealth composite thin film material with dynamic temperature adjustment and its preparation method, so that the infrared stealth thin film material has the infrared emission and reflection characteristics of the material at different temperatures.

[0005] A method for preparing an infrared stealth composite thin film material with multi-temperature dynamic adjustment, characterized by comprising the following steps:

[0006] (1) The modified boron nitride is prepared by mixing boron nitride nanosheets and MOF materials in deionized water at a mass ratio of 3 to 5:1, ultrasonically treating for 1 hour, and drying at 40 to 60°C to obtain modified boron nitride.

[0007] (2) Preparation of temperature-sensitive nanocapsules: Blue phase liquid crystal was prepared into microcapsules using ionic liquid templates and electrochemical polymerization, and then nano-sized. The specific steps are as follows.

[0008] 1-Butyl-3-methylimidazolium hexafluorophosphate (C 11 H 18 N2P˙F6) is heated to 60-80℃, and blue phase liquid crystal powder is slowly added while stirring. The mixture is then ultrasonically treated for 20-30 minutes to obtain a uniformly dispersed ionic liquid complex.

[0009] A three-electrode system was constructed using a platinum sheet as the working electrode, Ag / AgCl as the reference electrode, and a stainless steel sheet as the counter electrode. The ionic liquid complex was mixed with acrylic acid and sodium perchlorate and then injected into an electrochemical cell for electropolymerization. After the reaction was completed, the encapsulated product on the electrode surface was rinsed with ethanol and then dispersed in an ethanol solution and vacuum dried to obtain temperature-sensitive nanocapsules.

[0010] (3) Preparation of VO2(M) aerogels doped with modified boron nitride and thermosensitive nanocapsules:

[0011] Vanadium dioxide of type M was mixed evenly with acetic acid, and the pH value was adjusted to 8-10. Then, the prepared modified boron nitride and powdered temperature-sensitive nanocapsules were added. The mass ratio of VO2(M), modified boron nitride and powdered temperature-sensitive nanocapsules was 4-8:3-5:1. The mixture was magnetically stirred at 50-60℃. After gelation, it was dried in a vacuum drying oven for 4-6 hours. Finally, the gel was dried at 40-60℃ for about one week to obtain the composite aerogel.

[0012] (4) Preparation of bismuth antimonide thin film: BiSb alloy as main target material and In and W as doping target material, bismuth antimonide thin film was prepared by co-sputtering method;

[0013] (5) Preparation of infrared stealth composite film: At 20-25℃, a composite aerogel is coated on the bismuth antimonide film, and the thickness ratio of the composite aerogel layer to the bismuth antimonide film layer is 2-3:1; after standing, drying and curing, the infrared stealth composite film is obtained.

[0014] Further, the MOF material in step (1) is made by mixing UiO-66 and MIL-53 in a mass ratio of 3:1 to 5:1, adding the surfactant polyvinylpyrrolidone, stirring and heating to 100℃ to 120℃, reacting by surface-induced epitaxial growth for 12 to 20 hours, and finally centrifuging to obtain the MIL-53 / UiO-66 composite material.

[0015] Further, in step (2), 1-butyl-3-methylimidazolium hexafluorophosphate (C 11 H 18 The ratio of N2P˙F6 to blue phase liquid crystal is 5:1 to 2; the mass ratio of the ionic liquid composite to acrylic acid and sodium perchlorate is 10:3 to 6:0.3 to 0.5; the parameters of the electropolymerization reaction are: polymerization at 1.0 to 2.0 V for 30 to 90 min; vacuum drying is carried out at a temperature of 40 to 60 °C for 3 to 6 h.

[0016] Furthermore, the preparation method of the blue phase liquid crystal is as follows: chiral agent R10 and nematic liquid crystal E7 are mixed at a mass ratio of 1:5 to 10, melted at 80 to 100°C, and then ultrasonically treated to make them uniformly mixed. After cooling to room temperature, a blue phase crystal mother liquor is obtained. Under the conditions of 365nm light irradiation and 60°C, blue phase liquid crystal is obtained by photo-induced polymerization.

[0017] Further, the preparation method of the M-type vanadium dioxide is as follows: vanadium pentoxide is heated to a molten state and then uniformly mixed with deionized water at a mass ratio of 1:5 to 10. The mixture is filtered to obtain vanadium pentoxide gel. The vanadium pentoxide gel is freeze-dried at -50 to -80°C to obtain vanadium pentoxide powder. The vanadium pentoxide powder is uniformly mixed with carbon powder and carbon nanotubes at a mass ratio of 10:1 to 3:0.5 to 1. The mixture is then subjected to a carbothermic reduction reaction at 700 to 900°C for 2 to 4 hours to obtain M-phase vanadium dioxide powder.

[0018] Furthermore, in step (4), the main target material BiSb alloy is a BiSb alloy thin film prepared by co-sputtering Bi target and Sb target with single crystal silicon (001) as substrate.

[0019] Furthermore, the molar ratio of each substance in the bismuth antimonide thin film doped with In and W is Bi:Sb:In:W = 3~10:3~10:1~2:1.

[0020] Furthermore, during the co-sputtering of In and W-doped bismuth antimonide films, the power applied to the In and W targets was 15–50 W, the sputtering time was 40–70 min, the power applied to the main target was 150 W, the sputtering time was 20–30 min, the flow rates of the input working gases nitrogen and argon were maintained at 2.8 sccm and 80 sccm, respectively, the substrate temperature was 180–200 °C, and the distance between the target and the substrate was fixed at 50–70 mm. After sputtering, the substrate temperature was maintained for a period of time to solidify the film. After the substrate temperature dropped to room temperature, the vacuum was released and the sample was taken out.

[0021] Furthermore, in step (5), an air compressor is used to spray the composite aerogel onto the bismuth antimonide film; after spraying, it is left to stand for 1 to 2 hours and then placed in a drying oven at 100 to 150°C for 5 to 24 hours to cure.

[0022] The infrared stealth composite thin film material with multi-temperature dynamic adjustment prepared by the aforementioned preparation method is characterized in that it is composed of a stacked composite aerogel layer and a bismuth antimonide thin film layer doped with indium and tungsten, wherein the thickness ratio of the composite aerogel layer to the bismuth antimonide thin film layer is 2-3:1; the composite aerogel layer is formed by drying and curing doped modified boron nitride, temperature-sensitive nanocapsules, and VO2(M) aerogel, wherein the mass ratio of the doped modified boron nitride, temperature-sensitive nanocapsules, and VO2(M) is 4-6:1-2:1.

[0023] VO2(M) aerogel undergoes a metal-insulator transition at around 68℃, and its optical properties in the infrared field also change abruptly. At 68℃, VO2 is in a monoclinic phase (insulating state) with a certain band gap in its electronic structure. When the temperature is above 68℃, the structure transforms into a tetragonal rutile phase (metallic state), and the band gap closes. Therefore, it has a high infrared emissivity of 80-90% in the insulating state, while it has a low infrared emissivity of 30-40% in the metallic state, and reflects most of the infrared radiation. Boron nitride nanosheets possess low thermal conductivity, which reduces heat transfer and effectively decreases infrared radiation propagation. This invention modifies boron nitride nanosheets using MOF materials of UiO-66 and / or MIL-53. UiO-66 exhibits high chemical and thermal stability, while MIL-53 offers adjustable pore size and porosity. By adjusting the ratio of these two materials, more adsorption sites are provided for the boron nitride nanosheets, resulting in more uniform dispersion in the composite gel. This improves the compatibility of boron nitride with the matrix, helps maintain the microstructure of the composite material, and prevents agglomeration. Furthermore, it enhances the thermal stability of the boron nitride nanosheets at high temperatures, thereby reducing infrared emissivity. Combining the modified boron nitride nanosheets with VO2(M) gel enables the composite gel to maintain stability at high temperatures, broadening the applicable temperature range of the VO2(M) gel.

[0024] Furthermore, this invention utilizes the infrared optical properties of VO2(M) aerogel at higher operating temperatures to composite it with a temperature-sensitive blue phase liquid crystal. By leveraging the synergistic regulatory characteristics of the composite material, the scattering and absorption of infrared light by the material in different temperature zones are further optimized, thereby improving the infrared stealth characteristics of the material in different temperature zones.

[0025] By modifying the temperature-sensitive blue phase liquid crystal with nano-microencapsulation to achieve uniform distribution and by utilizing its temperature response to change its optical properties, the blue phase liquid crystal has a three-dimensional chiral cubic structure. Its molecules are twisted and arranged along a biaxial direction under strong chirality to form a periodic photonic crystal structure. In a fully polymerized system (such as 30wt% RM105 / DCM), the blue phase temperature range can be extended to -180 to 240℃. When the temperature is below -20℃, molecular thermal motion weakens, chiral helical twisting force increases, lattice shrinks, the band gap blue shifts, and infrared emissivity increases from 40% to about 60%. When the temperature is between -20℃ and 0℃, lattice shrinkage stops, the band gap stabilizes, and infrared emissivity remains at about 60%. When the temperature is between 0℃ and 80℃, the lattice constant remains stable, and the photonic band gap matches the infrared detection band, with infrared emissivity remaining between 25% and 45%. When the temperature is between 80℃ and 240℃, the lattice expands, the band gap redshifts, and infrared emissivity gradually increases to 60%. When the temperature reaches the phase transition critical temperature of 240℃, the lattice decomposes, the photonic band gap disappears, infrared emissivity exceeds 80%, and infrared stealth performance fails. Utilizing this characteristic of blue phase liquid crystals, the composite gel exhibits adaptive dynamic control of infrared radiation under different operating temperature conditions.

[0026] The phase transition of VO2(M) gel works in synergy with the thermosensitive properties of blue phase liquid crystal. When the operating temperature is low, the low infrared emissivity of blue phase liquid crystal plays a dominant role, neutralizing the infrared stealth optical properties of composite aerogel at low temperatures. When the operating temperature is in the critical temperature range of about 68-80℃, the increase in infrared emissivity of blue phase liquid crystal and the decrease in infrared emissivity of VO2 cancel each other out, so that the overall infrared emissivity is maintained in a stable range of 50-60%. When the operating temperature is high, the situation is the opposite of the low temperature, and VO2 takes the lead, forming a dual temperature response mechanism. The aerogel composited with modified boron nitride and thermosensitive nanocapsules exhibits lower infrared emissivity compared to ordinary aerogels that rely solely on the phase transition of VO2. The composite aerogel not only effectively suppresses infrared radiation through interfacial coupling with MOFs but also achieves superior infrared emissivity by working synergistically with blue phase liquid crystals at different temperatures, further broadening its operating temperature range. Compared to ordinary aerogels that may deactivate at 100℃, VO2 protected by the highly thermally stable MOF material and the highly antioxidant boron nitride nanosheets is more stable at high temperatures. Furthermore, the modified boron nitride makes the phase transition of VO2 more uniform, reducing leakage caused by abrupt changes in infrared emissivity in ordinary aerogels.

[0027] Finally, bismuth antimonide films doped with indium and tungsten achieve a relatively high and consistent reflectivity in the infrared band, while exhibiting good corrosion resistance and high-temperature stability. Indium exhibits high infrared reflectivity (70-90%) in the mid-wave infrared range at room temperature to approximately 200°C, and tungsten exhibits high infrared reflectivity (70-90%) in the long-wave infrared range at 500-2000°C. By doping BiSb films with indium and tungsten, leveraging the inherent low infrared emissivity and high infrared reflectivity of ternary alloy topological insulator films, and combining the infrared response characteristics of both at different wavelengths and temperatures, the infrared operating band of BiSb films is broadened, as is the operating temperature range for high infrared reflectivity, which also covers certain extreme conditions, thus enhancing their infrared stealth effect under various conditions.

[0028] The synergistic effect between the bismuth antimonide-doped thin film and the composite gel achieves full-temperature, full-wavelength optimization of the material's infrared stealth performance. The low infrared emissivity of the composite aerogel combined with the high infrared reflectivity of the bismuth antimonide-doped thin film, with the film's mid-to-long infrared band covering the gel's long-wavelength band, further optimizes the material's infrared stealth performance. The composite process further broadens the operating temperature range, extending it from room temperature to certain extreme temperature zones. The application of the high-reflectivity substrate film and the porous structure of the composite gel provide excellent thermal insulation properties, blocking heat dissipation from high-temperature areas and thus reducing the infrared radiation intensity of vehicles and other components, achieving infrared stealth.

[0029] The results of the embodiments show that the infrared emissivity of the infrared stealth composite thin film material with multi-temperature dynamic adjustment provided by the present invention is 43% at low temperature, 40% to 58% at room temperature, and 51% at high temperature, with a temperature response time of 1 to 3 seconds and an operating temperature range of -30 to 150°C.

[0030] This invention involves coating a composite aerogel of VO2(M) doped with modified boron nitride and temperature-sensitive nanocapsules onto a bismuth antimonide thin film, followed by curing, to obtain a VO2(M) aerogel composite material of modified boron nitride and temperature-sensitive nanocapsules, which is then combined with a bismuth antimonide-doped thin film. The method for preparing the multi-temperature dynamically adjustable infrared stealth composite thin film material provided by this invention is simple to operate and ensures the performance of the composite thin film.

[0031] The multi-temperature dynamically adjustable infrared stealth composite film material of this invention can be applied to infrared stealth protection of vehicles. For example, covering the body of a car with the composite film material can reduce the infrared radiation performance of the car itself under dynamic temperature changes. Detailed Implementation

[0032] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0033] This invention provides a thin film material composed of a composite aerogel of VO2(M) doped with modified boron nitride and thermosensitive nanocapsules and a bismuth antimonide film, wherein the bismuth antimonide film is a bismuth antimonide film doped with indium and tungsten, and the mass ratio of the composite aerogel of VO2(M) doped with modified boron nitride and thermosensitive nanocapsules to the bismuth antimonide film is 2 to 3:1.

[0034] Its preparation process is as follows:

[0035] S1. Preparation of composite MOF materials:

[0036] ZrCl, terephthalic acid (H2BDC), and 4-4'-azophthalic acid were dissolved in a supercritical CO2 / DMF mixed solvent. The DNA origami framework was immersed in phosphate buffer containing the thermosensitive polymer poly(N-isopropylacrylamide) (PNIPAM) and treated at 60°C for 30 min to form a hybrid template. The above solution was mixed with the template and then a photoresponsive azophenyl group was incorporated. The reaction temperature was lowered to 60°C and the reaction time was shortened to 4 h using a vapor phase-assisted method. Finally, the thermosensitive template was used to achieve self-expansion and detachment at 25°C to obtain UiO-66.

[0037] aluminum hydroxide, H vBDC, photothermal gold nanorods, and PNIPAM@SiO2 temperature-sensitive template were added to ultrapure water and ultrasonically dispersed for 10 min. They were then irradiated with 808 nm near-infrared light for 1 h to form MIL-53 crystal nuclei. The crystals were then crystallized with steam assistance and reacted at a constant temperature for 7 h. Finally, the temperature was lowered to 25 °C, and the MIL-53 was obtained by self-expansion and detachment from the template.

[0038] Finally, MIL-53 was added to the UiO-66 mother liquor, with a mass ratio of UiO-66 to MIL-53 of 3:1 to 5:1. The surfactant polyvinylpyrrolidone (PVP) was added, and the mixture was stirred and heated to 100℃ to 120℃. The reaction was carried out by surface-induced epitaxial growth for 12 to 20 hours. Finally, the MIL-53 / UiO-66 composite material was obtained by centrifugation.

[0039] S2. Preparation of modified boron nitride: Boron nitride nanosheets and composite MOF materials were mixed in deionized water at a mass ratio of 3 to 5:1, ultrasonically treated for 1 hour, and dried at 40 to 60°C to obtain modified boron nitride;

[0040] Preparation of blue phase liquid crystal: Chiral agent R10 and nematic liquid crystal E7 are mixed at a mass ratio of 1:5 to 10, melted at 80 to 100°C, and then ultrasonically treated to make them uniformly mixed. After cooling to room temperature, blue phase crystal mother liquor is obtained. Under 365nm light and 60°C, blue phase liquid crystal is obtained by photo-induced polymerization.

[0041] Preparation of thermosensitive nanocapsules: Blue phase liquid crystal was fabricated into microcapsules using an ionic liquid template and electrochemical polymerization method, and then nano-sized. C0.05 11 H 18 N2P˙F6 was heated to 60–80°C, and blue phase liquid crystal powder was slowly added while stirring. The mixture was ultrasonically treated for 20–30 min to obtain a uniformly dispersed ionic liquid composite. A three-electrode system was constructed using a platinum sheet as the working electrode, Ag / AgCl as the reference electrode, and a stainless steel sheet as the counter electrode. The composite was then mixed uniformly with acrylic acid and sodium perchlorate and injected into an electrochemical cell. Polymerization was carried out at 1.0–2.0 V for 30–90 min. After the reaction, the encapsulated product on the electrode surface was rinsed with ethanol 5–8 times, and then dispersed in an ethanol solution. The product was then vacuum dried at 40–60°C for 3–6 h to obtain a thermosensitive nanocapsule composite material.

[0042] Preparation of VO2(M): Vanadium pentoxide was heated to a molten state and then mixed uniformly with deionized water at a mass ratio of 1:5 to 10. The mixture was filtered to obtain vanadium pentoxide gel. The gel was freeze-dried at -50 to -80°C to obtain vanadium pentoxide powder. The vanadium pentoxide powder was mixed uniformly with carbon powder and carbon nanotubes at a mass ratio of 10:1 to 3:0.5 to 1. The mixture was subjected to a carbothermic reduction reaction at 700 to 900°C for 2 to 4 hours to obtain M-phase vanadium dioxide powder.

[0043] Preparation of VO2(M) aerogel doped with modified boron nitride and thermosensitive nanocapsules: The prepared VO2(M) was mixed with acetic acid to form a uniform mixed sol. After adjusting the pH value to 8-10, the prepared modified boron nitride and powdered thermosensitive nanocapsule composite material was added. The mass ratio of VO2(M), modified boron nitride and powdered thermosensitive nanocapsules was 4-8:3-5:1. The mixture was magnetically stirred at 50-60℃. After gelation, it was dried in a vacuum drying oven for 4-6 hours. Finally, the gel was dried at 40-60℃ for about one week to obtain the composite aerogel.

[0044] Preparation of Bismuth Antimonide Thin Films: A co-sputtering method was used with single-crystal silicon (001) as the substrate. First, Bi and Sb targets were sputtered to obtain BiSb alloy thin films. These films were then used as the main target, with In and W as the doping targets. Acetone, alcohol, and deionized water were used as cleaning solutions, and the substrate was ultrasonically cleaned for 20–30 minutes to remove impurities from the substrate surface. The cleaned substrate was dried and placed in the sputtering chamber, ensuring the working pressure inside the chamber was approximately 1.0 Pa. The target surfaces were cleaned using a pulsed laser, bombarding them with 200–400 mJ energy for 5–10 minutes. The cleaned main and doped targets were then installed in the sputtering chamber, and power was applied to the In and W targets. The sputtering rate was 15–50 W, the sputtering time was 40–70 min, the power applied to the main target was kept constant at 150 W, the sputtering time was 20–30 min, the flow rates of the input working gases nitrogen (99.999%) and argon (99.999%) were kept at 2.8 sccm and 80 sccm respectively, the substrate temperature was set at 180–200 °C, and the distance between the target and the substrate was fixed at 50–70 mm. After sputtering, the substrate temperature was maintained for a period of time to solidify the film. After the substrate temperature dropped to room temperature, the vacuum was released and the sample was taken out. The molar ratio of each substance in the obtained film, Bi:Sb:In:W, was 3–10:3–10:1–2:1.

[0045] Preparation of infrared stealth composite film: At room temperature (20-25℃), a layer of composite aerogel of VO2(M) doped with modified boron nitride and thermosensitive nanocapsules is coated on a bismuth antimonide film. The coating is sprayed using an air compressor, left to stand for 1-2 hours, and then placed in a drying oven at 100-150℃ for 5-24 hours to cure, thus obtaining the composite film material.

[0046] Example 1

[0047] The thickness ratio of the composite aerogel of VO2(M) doped with modified boron nitride and thermosensitive nanocapsules to the bismuth antimonide film is 2.5:1.

[0048] Preparation of composite MOF materials: First, 5 parts by weight of ZrCl and 5 parts by weight of H...v BDC was dissolved in 3 parts by weight of 4-4'-azophthalic acid in 10 parts by weight of supercritical CO2 / DMF mixed solvent. 5 parts by weight of DNA origami frameworks were immersed in 10 parts by weight of phosphate buffer containing the thermosensitive polymer PNIPAM and treated at 60°C for 30 min to form a hybrid template. The above solution was mixed with the template and 2 parts by weight of photoresponsive azophenyl groups were incorporated. The reaction temperature was lowered to 60°C and the reaction time was shortened to 4 h using a vapor-assisted method. Finally, the template was detached from the template at 25°C through self-expansion to obtain UiO-66. Then, 1 part by weight of aluminum hydroxide, 5 parts by weight of H2BDC, 2 parts by weight of photothermal gold nanorods, and 5 parts by weight of PNIPAM@SiO2 thermosensitive template were added to ultrapure water and ultrasonically dispersed for 10 min. The mixture was irradiated with 808 nm near-infrared light for 1 h to form MIL-53 crystal nuclei. Then, vapor-assisted crystallization was performed at a constant temperature for 7 h. Finally, the temperature was lowered to 25°C, and the template was detached from the template through self-expansion to obtain MIL-53. Finally, according to the mass ratio of UiO-66 to MIL-53 of 5:1, MIL-53 was added to the UiO-66 mother liquor, 0.3 parts by weight of surfactant PVP was added, the mixture was stirred and heated to 100℃, and after reacting for 20 hours, the MIL-53 / UiO-66 composite MOF material was obtained by centrifugation.

[0049] Preparation of modified boron nitride: 30 parts by weight of BN nanosheets and 6 parts by weight of composite MOF material were mixed in deionized water at a mass ratio of 5:1, ultrasonically treated for 1 hour, and dried at 50°C to obtain modified boron nitride.

[0050] Preparation of temperature-sensitive nanocapsule composite material: First, blue phase liquid crystal was prepared by mixing chiral agent R10 and nematic liquid crystal E7 at a mass ratio of 1:9, melting at 90°C, and then ultrasonically treating to make it uniformly mixed. After cooling to room temperature, blue phase crystal mother liquor was obtained. Under 365nm light and 60°C, blue phase liquid crystal was obtained by photo-induced polymerization.

[0051] Next, blue phase liquid crystal was prepared into microcapsules using an ionic liquid template and electrochemical polymerization method, and then nano-sized. First, C... 11 H 18 N2P˙F6 was heated to 60℃, and blue phase liquid crystal powder was slowly added while stirring. The mixture was then ultrasonically treated for 30 minutes to obtain a uniformly dispersed ionic liquid composite, in which C... 11 H 18The ratio of N2P˙F6 to blue phase liquid crystal was 5:1. A three-electrode system was constructed using a platinum sheet as the working electrode, Ag / AgCl as the reference electrode, and a stainless steel sheet as the counter electrode. The ionic liquid complex was mixed with acrylic acid and sodium perchlorate and then injected into the electrochemical cell. The mass ratio of the ionic liquid complex to acrylic acid and sodium perchlorate was 10:3:0.5. Polymerization was carried out at 2.0 V for 90 min. After the reaction, the encapsulated product on the electrode surface was washed five times with ethanol, then dispersed in an ethanol solution and vacuum dried at 60 °C for 6 h to obtain temperature-sensitive nanocapsules.

[0052] Preparation of VO2(M): 5 parts by weight of vanadium pentoxide were heated to a molten state and then uniformly mixed with deionized water at a mass ratio of 1:10. The mixture was filtered to obtain vanadium pentoxide gel. The vanadium pentoxide gel was freeze-dried at -80℃ to obtain vanadium pentoxide powder. The vanadium pentoxide powder was uniformly mixed with carbon powder and carbon nanotubes at a mass ratio of 10:3:0.5 and subjected to a carbothermic reduction reaction at 800℃ to obtain M-phase vanadium dioxide powder.

[0053] Preparation of composite aerogel of VO2(M) doped with modified boron nitride and thermosensitive nanocapsules: VO2(M) was mixed evenly with acetic acid, and the pH was adjusted to 8. Then, the prepared modified boron nitride and powdered thermosensitive nanocapsules were added. The mass ratio of VO2(M), modified boron nitride and powdered thermosensitive nanocapsules was 5:5:1. The mixture was magnetically stirred at 60℃. After gelation, the mixture was dried in a vacuum drying oven for 6 hours. Finally, the gel was dried at 50℃ for about one week to obtain the composite aerogel of VO2(M) doped with modified boron nitride and thermosensitive nanocapsules.

[0054] Preparation of bismuth antimonide thin films: Bismuth antimonide thin films were prepared by co-sputtering: using single-crystal silicon (001) as a substrate, Bi and Sb targets were sputtered first to obtain BiSb alloy thin films; then, using the BiSb alloy thin film as the main target material and In and W targets as doping targets, bismuth antimonide thin films doped with In and W were co-sputtered to prepare In and W doped bismuth antimonide thin films. The molar ratio of each substance in the obtained thin film Bi:Sb:In:W was 3:3:1:1.

[0055] Before co-sputtering, the substrate needs to be cleaned with acetone, alcohol, and deionized water in an ultrasonic bath for 30 minutes to remove impurities from the substrate surface. After cleaning, the substrate is dried and placed in the sputtering chamber. Before sputtering, the target material is cleaned by bombarding with a pulsed laser at 400 mJ energy for 5 minutes.

[0056] During the co-sputtering process of In and W-doped bismuth antimonide films, the substrate temperature was 190℃, the distance between the target and the substrate was fixed at 60mm, the power applied to the main target was 150W, and the sputtering time was 20min. The power applied to the In and W targets was 20W, and the sputtering time was 60min. The flow rates of the input working gases, nitrogen and argon, were maintained at 2.8sccm and 80sccm, respectively. After sputtering, the substrate temperature was maintained for a period of time to solidify the film. When the substrate temperature dropped to approximately room temperature, the vacuum was released and the sample was removed, yielding In and W-doped bismuth antimonide films.

[0057] Preparation of composite thin film material: At room temperature (25℃), a layer of composite aerogel of VO2(M) doped with modified boron nitride and temperature-sensitive nanocapsules was sprayed onto a bismuth antimonide thin film doped with In and W using an air compressor. After standing for 2 hours, the film was placed in a drying oven at 100℃ for 24 hours to cure, thus obtaining an infrared stealth composite thin film material that can be dynamically adjusted at multiple temperatures.

[0058] In accordance with the provisions of GJB10055-2021, GJB8700-2015 and GB / T43249-2023, infrared performance tests were conducted under stable environmental conditions, and the test results are shown in Table 1.

[0059] Example 2

[0060] The thickness ratio of the composite aerogel of VO2(M) doped with modified boron nitride and thermosensitive nanocapsules to the bismuth antimonide film is 2:1.

[0061] Preparation of composite MOF material: First, 8 parts by weight of ZrCl, 5 parts by weight of H2BDC and 3 parts by weight of 4-4'-azophthalic acid were dissolved in 10 parts by weight of supercritical CO2 / DMF mixed solvent. 5 parts by weight of DNA origami frames were immersed in 10 parts by weight of phosphate buffer containing thermosensitive polymer PNIPAM and treated at 60°C for 30 min to form a hybrid template. After mixing the above solution with the template, 2 parts by weight of photoresponsive azophenyl groups were incorporated. The reaction temperature was reduced to 60°C and the reaction time was shortened to 4 h using a vapor phase-assisted method. Finally, the thermosensitive template was used to achieve self-expansion and detachment at 25°C to obtain UiO-66. Two parts by weight of aluminum hydroxide, five parts by weight of H2BDC, two parts by weight of photothermal gold nanorods, and five parts by weight of PNIPAM@SiO2 thermosensitive template were added to ultrapure water and ultrasonically dispersed for 10 min. The mixture was then irradiated with 808 nm near-infrared light for 1 h to form MIL-53 crystal nuclei. Steam-assisted crystallization was then performed at a constant temperature for 7 h. Finally, the temperature was lowered to 25 °C, and the mixture detached from the template through self-expansion to obtain MIL-53. MIL-53 was then added to the UiO-66 mother liquor at a mass ratio of 4:1. 0.3 parts by weight of surfactant PVP was added, and the mixture was stirred and heated to 100 °C for 20 h. Finally, centrifugation was performed to obtain the MIL-53 / UiO-66 composite material.

[0062] Preparation of modified boron nitride: 30 parts by weight of BN nanosheets and 10 parts by weight of composite MOF material were mixed in deionized water at a mass ratio of 3:1, ultrasonically treated for 1 hour, and dried at 50°C to obtain modified boron nitride.

[0063] Preparation of temperature-sensitive nanocapsule composite material: First, prepare blue phase liquid crystal: Chiral agent R10 and nematic liquid crystal E7 are mixed at a mass ratio of 1:9, melted at 90℃ and ultrasonically treated to make them uniformly mixed. After cooling to room temperature, a blue phase crystal mother liquor is obtained. Under 365nm light and 60℃ conditions, blue phase liquid crystal is obtained by photo-induced polymerization.

[0064] Next, blue phase liquid crystal was prepared into microcapsules using an ionic liquid template and electrochemical polymerization method, and then nano-sized. First, C... 11 H 18 N2P˙F6 was heated to 60℃, and blue phase liquid crystal powder was slowly added while stirring. The mixture was then ultrasonically treated for 30 minutes to obtain a uniformly dispersed ionic liquid composite, in which C... 11 H 18The ratio of N2P˙F6 to blue phase liquid crystal was 5:1. A three-electrode system was constructed using a platinum sheet as the working electrode, Ag / AgCl as the reference electrode, and a stainless steel sheet as the counter electrode. The ionic liquid complex was mixed with acrylic acid and sodium perchlorate and then injected into an electrochemical cell. The mass ratio of the ionic liquid complex to acrylic acid and sodium perchlorate was 10:5:0.3. Polymerization was carried out at 2.0 V for 90 min. After the reaction, the encapsulated product on the electrode surface was washed five times with ethanol, and then dispersed in an ethanol solution and vacuum dried at 60 °C for 6 h to obtain temperature-sensitive nanocapsules.

[0065] Preparation of VO2(M): 5 parts by weight of vanadium pentoxide were heated to a molten state and then uniformly mixed with deionized water at a mass ratio of 1:10. The mixture was filtered to obtain vanadium pentoxide gel. The gel was freeze-dried at -80℃ to obtain vanadium pentoxide powder. The powder was uniformly mixed with carbon powder and carbon nanotubes at a mass ratio of 10:1:0.5 and subjected to a carbothermic reduction reaction at 800℃ to obtain M-phase vanadium dioxide powder.

[0066] Preparation of composite aerogel of VO2(M) doped with modified boron nitride and thermosensitive nanocapsules: VO2(M) was mixed evenly with acetic acid, and the pH was adjusted to 8. Then, the prepared modified boron nitride and powdered thermosensitive nanocapsules were added. The mass ratio of VO2(M), modified boron nitride and powdered thermosensitive nanocapsules was 5:6:1. The mixture was magnetically stirred at 60℃. After gelation, the mixture was dried in a vacuum drying oven for 6 hours. Finally, the gel was dried at 50℃ for about one week to obtain the composite aerogel of VO2(M) doped with modified boron nitride and thermosensitive nanocapsules.

[0067] Preparation of bismuth antimonide thin films: Using single-crystal silicon (001) as a substrate, Bi and Sb targets were sputtered first to obtain BiSb alloy thin films. Then, using the BiSb alloy thin film as the main target material and In and W targets as doping targets, In and W doped bismuth antimonide thin films were co-sputtered to prepare In and W doped bismuth antimonide thin films. The molar ratio of each substance in the obtained film Bi:Sb:In:W was 5:3:1:1.

[0068] Before co-sputtering, the substrate needs to be cleaned with acetone, alcohol, and deionized water as a cleaning solution in an ultrasonic bath for 30 minutes to remove impurities from the substrate surface. After cleaning, the substrate is dried and placed in the sputtering chamber. Before sputtering, the target material is cleaned by bombarding with a pulsed laser at an energy of 400 mJ for 5 minutes.

[0069] During the co-sputtering process of In and W-doped bismuth antimonide films, the substrate temperature was 200℃, the distance between the target and the substrate was fixed at 60mm, the power applied to the main target was 150W, and the sputtering time was 20min. The power applied to the In and W targets was 40W, and the sputtering time was 50min. The flow rates of the input working gases, nitrogen and argon, were maintained at 2.8sccm and 80sccm, respectively. After sputtering, the substrate temperature was maintained for a period of time to solidify the film. When the substrate temperature dropped to approximately room temperature, the vacuum was released and the sample was removed, yielding In and W-doped bismuth antimonide films.

[0070] Preparation of composite thin film material: At room temperature (25℃), a layer of composite aerogel of VO2(M) doped with modified boron nitride and temperature-sensitive nanocapsules was sprayed onto a bismuth antimonide thin film doped with In and W using an air compressor. After standing for 2 hours, it was placed in a drying oven at 125℃ for 24 hours to cure, thus obtaining an infrared stealth composite thin film material that can be dynamically adjusted at multiple temperatures.

[0071] In accordance with the provisions of GJB10055-2021, GJB8700-2015 and GB / T43249-2023, infrared performance tests were conducted under stable environmental conditions, and the test results are shown in Table 1.

[0072] Example 3

[0073] The thickness ratio of the composite aerogel of VO2(M) doped with modified boron nitride and thermosensitive nanocapsules to the bismuth antimonide film is 2.85:1.

[0074] Preparation of composite MOF materials: First, 5 parts by weight of ZrCl, 5 parts by weight of H2BDC, and 3 parts by weight of 4-4'-azophthalic acid were dissolved in 10 parts by weight of supercritical CO2 / DMF mixed solvent. 5 parts by weight of DNA origami frames were immersed in 10 parts by weight of phosphate buffer containing the thermosensitive polymer PNIPAM and treated at 60°C for 30 min to form a hybrid template. The above solution was mixed with the template, and 2 parts by weight of photoresponsive azophenyl groups were incorporated. The reaction temperature was lowered to 60°C and the reaction time shortened to 4 h using a vapor-phase assisted method. Finally, self-expansion and detachment at 25°C were achieved through the thermosensitive template to obtain UiO-66. Then, 1 part by weight of aluminum hydroxide, 5 parts by weight of H2BDC, and 3 parts by weight of H2BDC were dissolved in 10 parts by weight of supercritical CO2 / DMF mixed solvent. Two parts by weight of BDC, two parts by weight of photothermal gold nanorods, and five parts by weight of PNIPAM@SiO2 thermosensitive template were added to ultrapure water and ultrasonically dispersed for 10 min. The mixture was then irradiated with 808 nm near-infrared light for 1 h to form MIL-53 crystal nuclei. The crystals were then crystallized with steam assistance and reacted at a constant temperature for 7 h. Finally, the temperature was lowered to 25 °C, and the template was detached through self-expansion to obtain MIL-53. MIL-53 was then added to UiO-66 mother liquor at a mass ratio of 5:1. 0.3 parts by weight of surfactant PVP was added, and the mixture was stirred and heated to 100 °C for 20 h. Finally, the mixture was centrifuged to obtain the MIL-53 / UiO-66 composite MOF material.

[0075] Preparation of modified boron nitride: 30 parts by weight of BN nanosheets and 6 parts by weight of composite MOF material were mixed in deionized water at a mass ratio of 5:1, ultrasonically treated for 1 h, and dried at 50 °C to obtain modified boron nitride.

[0076] Preparation of temperature-sensitive nanocapsule composite material: First, blue phase liquid crystal was prepared by mixing chiral agent R10 and nematic liquid crystal E7 at a mass ratio of 1:9, melting at 90°C, and then ultrasonically treating to make it uniformly mixed. After cooling to room temperature, blue phase crystal mother liquor was obtained. Under 365nm light and 60°C, blue phase liquid crystal was obtained by photo-induced polymerization.

[0077] Next, blue phase liquid crystal was prepared into microcapsules using an ionic liquid template and electrochemical polymerization method, and then nano-sized. First, C... 11 H 18 N2P˙F6 was heated to 60℃, and blue phase liquid crystal powder was slowly added while stirring. The mixture was then ultrasonically treated for 30 minutes to obtain a uniformly dispersed ionic liquid composite, in which C... 11 H 18The ratio of N2P˙F6 to blue phase liquid crystal was 5:1. A three-electrode system was constructed using a platinum sheet as the working electrode, Ag / AgCl as the reference electrode, and a stainless steel sheet as the counter electrode. The ionic liquid composite was mixed with acrylic acid and sodium perchlorate and then injected into an electrochemical cell, with a mass ratio of ionic liquid composite to acrylic acid and sodium perchlorate of 10:5:0.3. Polymerization was carried out at 2.0 V for 90 min. After the reaction, the encapsulated product on the electrode surface was washed five times with ethanol, then dispersed in an ethanol solution and vacuum dried at 60 °C for 6 h to obtain the temperature-sensitive nanocapsule composite material.

[0078] Preparation of VO2(M): 5 parts by weight of vanadium pentoxide were heated to a molten state and then uniformly mixed with deionized water at a mass ratio of 1:10. The mixture was filtered to obtain vanadium pentoxide gel. The gel was freeze-dried at -80℃ to obtain vanadium pentoxide powder. The powder was uniformly mixed with carbon powder and carbon nanotubes at a mass ratio of 10:2:1 and subjected to a carbothermic reduction reaction at 850℃ to obtain M-phase vanadium dioxide powder.

[0079] Preparation of composite aerogel of VO2(M) doped with modified boron nitride and thermosensitive nanocapsules: VO2(M) was mixed evenly with acetic acid, and the pH was adjusted to 8. Then, the prepared modified boron nitride and powdered thermosensitive nanocapsules were added. The mass ratio of VO2(M), modified boron nitride and powdered thermosensitive nanocapsules was 5:5:1. The mixture was magnetically stirred at 60℃. After gelation, the mixture was dried in a vacuum drying oven for 6 hours. Finally, the gel was dried at 50℃ for about one week to obtain the composite aerogel of VO2(M) doped with modified boron nitride and thermosensitive nanocapsules.

[0080] Preparation of bismuth antimonide thin films:

[0081] Using single-crystal silicon (001) as a substrate, Bi and Sb targets were sputtered first to obtain BiSb alloy thin films. Then, using the BiSb alloy thin film as the main target material and In and W targets as doping targets, bismuth antimonide thin films doped with In and W were co-sputtered to prepare In and W doped bismuth antimonide thin films. The molar ratio of each substance in the obtained thin film Bi:Sb:In:W was 3:3:1:1.

[0082] Before co-sputtering, the substrate needs to be cleaned with acetone, alcohol, and deionized water as a cleaning solution in an ultrasonic bath for 30 minutes to remove impurities from the substrate surface. After cleaning, the substrate is dried and placed in the sputtering chamber. Before sputtering, the target material is cleaned by bombarding with a pulsed laser at an energy of 400 mJ for 5 minutes.

[0083] During the co-sputtering process of In and W-doped bismuth antimonide films, the substrate temperature was 190℃, the distance between the target and the substrate was fixed at 60mm, the power applied to the main target was 150W, and the sputtering time was 20min. The power applied to the In and W targets was 20W, and the sputtering time was 60min. The flow rates of the input working gases, nitrogen and argon, were maintained at 2.8sccm and 80sccm, respectively. After sputtering, the substrate temperature was maintained for a period of time to solidify the film. When the substrate temperature dropped to approximately room temperature, the vacuum was released and the sample was removed, yielding In and W-doped bismuth antimonide films.

[0084] Preparation of composite thin film material: At room temperature (25℃), a layer of composite aerogel of VO2(M) doped with modified boron nitride and temperature-sensitive nanocapsules was sprayed onto an In and W-doped bismuth antimonide thin film using an air compressor. After standing for 2 hours, the film was placed in a 150℃ drying oven for 24 hours to cure, thus obtaining an infrared stealth composite thin film material that can be dynamically adjusted at multiple temperatures.

[0085] In accordance with the provisions of GJB10055-2021, GJB8700-2015 and GB / T43249-2023, infrared performance tests were conducted under stable environmental conditions, and the test results are shown in Table 1.

[0086] Example 4

[0087] The thickness ratio of the composite aerogel of VO2(M) doped with modified boron nitride and thermosensitive nanocapsules to the bismuth antimonide film is 2.85:1.

[0088] Preparation of MOF material UiO-66: 5 parts by weight of ZrCl, 5 parts by weight of H2BDC, and 3 parts by weight of 4-4'-azophthalic acid were dissolved in 10 parts by weight of supercritical CO2 / DMF mixed solvent. 5 parts by weight of DNA origami frames were immersed in 10 parts by weight of phosphate buffer containing the thermosensitive polymer PNIPAM and treated at 60°C for 30 min to form a hybrid template. The above solution was mixed with the template, and 2 parts by weight of photoresponsive azophenyl groups were incorporated. The reaction temperature was lowered to 60°C and the reaction time was shortened to 4 h using a vapor-phase assisted method. Finally, the thermosensitive template was used to achieve self-expansion and detachment at 25°C to obtain UiO-66. Finally, the UiO-66 material was obtained by centrifugation.

[0089] Preparation of modified boron nitride: 30 parts by weight of BN nanosheets and 5 parts by weight of UiO-66 material were mixed in deionized water at a mass ratio of 5:1, ultrasonically treated for 1 hour, and dried at 50°C to obtain modified boron nitride.

[0090] Preparation of temperature-sensitive nanocapsule composite materials:

[0091] First, blue phase liquid crystal is prepared by mixing chiral agent R10 and nematic liquid crystal E7 at a mass ratio of 1:9, melting at 90°C, and then ultrasonically mixing to ensure uniform mixing. After cooling to room temperature, a blue phase crystal mother liquor is obtained. Under 365nm light and 60°C conditions, blue phase liquid crystal is obtained through photoinduced polymerization.

[0092] Next, blue phase liquid crystal was prepared into microcapsules using an ionic liquid template and electrochemical polymerization method, and then nano-sized. First, C... 11 H 18 N2P˙F6 was heated to 60℃, and blue phase liquid crystal powder was slowly added while stirring. The mixture was then ultrasonically treated for 30 minutes to obtain a uniformly dispersed ionic liquid composite, in which C... 11 H 18 The ratio of N2P˙F6 to blue phase liquid crystal was 5:1. A three-electrode system was constructed using a platinum sheet as the working electrode, Ag / AgCl as the reference electrode, and a stainless steel sheet as the counter electrode. The ionic liquid composite was mixed with acrylic acid and sodium perchlorate and then injected into an electrochemical cell, with a mass ratio of ionic liquid composite to acrylic acid and sodium perchlorate of 10:5:0.3. Polymerization was carried out at 2.0 V for 90 min. After the reaction, the encapsulated product on the electrode surface was washed five times with ethanol, then dispersed in an ethanol solution and vacuum dried at 60 °C for 6 h to obtain the temperature-sensitive nanocapsule composite material.

[0093] Preparation of VO2(M): 5 parts by weight of vanadium pentoxide were heated to a molten state and then uniformly mixed with deionized water at a mass ratio of 1:10. The mixture was filtered to obtain vanadium pentoxide gel. The gel was freeze-dried at -80℃ to obtain vanadium pentoxide powder. The powder was uniformly mixed with carbon powder and carbon nanotubes at a mass ratio of 10:2:1 and subjected to a carbothermic reduction reaction at 850℃ to obtain M-phase vanadium dioxide powder.

[0094] Preparation of composite aerogel of VO2(M) doped with modified boron nitride and thermosensitive nanocapsules: VO2(M) was mixed evenly with acetic acid, and the pH was adjusted to 8. Then, the prepared modified boron nitride and powdered thermosensitive nanocapsules were added. The mass ratio of VO2(M), modified boron nitride and powdered thermosensitive nanocapsules was 5:5:1. The mixture was magnetically stirred at 60℃. After gelation, the mixture was dried in a vacuum drying oven for 6 hours. Finally, the gel was dried at 50℃ for about one week to obtain the composite aerogel of VO2(M) doped with modified boron nitride and thermosensitive nanocapsules.

[0095] Preparation of bismuth antimonide thin films:

[0096] Using single-crystal silicon (001) as a substrate, Bi and Sb targets were sputtered first to obtain BiSb alloy thin films. Then, using the BiSb alloy thin film as the main target material and In and W targets as doping targets, bismuth antimonide thin films doped with In and W were co-sputtered to prepare In and W doped bismuth antimonide thin films. The molar ratio of each substance in the obtained thin film Bi:Sb:In:W was 3:3:1:1.

[0097] Before co-sputtering, the substrate needs to be cleaned with acetone, alcohol, and deionized water as a cleaning solution in an ultrasonic bath for 30 minutes to remove impurities from the substrate surface. After cleaning, the substrate is dried and placed in the sputtering chamber. Before sputtering, the target material is cleaned by bombarding with a pulsed laser at an energy of 400 mJ for 5 minutes.

[0098] During the co-sputtering process of In and W-doped bismuth antimonide films, the substrate temperature was 190℃, the distance between the target and the substrate was fixed at 60mm, the power applied to the main target was 150W, and the sputtering time was 20min. The power applied to the In and W targets was 20W, and the sputtering time was 60min. The flow rates of the input working gases, nitrogen and argon, were maintained at 2.8sccm and 80sccm, respectively. After sputtering, the substrate temperature was maintained for a period of time to solidify the film. When the substrate temperature dropped to approximately room temperature, the vacuum was released and the sample was removed, yielding In and W-doped bismuth antimonide films.

[0099] Preparation of composite thin film material: At room temperature (25℃), a layer of composite aerogel of VO2(M) doped with modified boron nitride and temperature-sensitive nanocapsules was sprayed onto an In and W-doped bismuth antimonide thin film using an air compressor. After standing for 2 hours, the film was placed in a 150℃ drying oven for 24 hours to cure, thus obtaining an infrared stealth composite thin film material that can be dynamically adjusted at multiple temperatures.

[0100] In accordance with the provisions of GJB10055-2021, GJB8700-2015 and GB / T43249-2023, infrared performance tests were conducted under stable environmental conditions, and the test results are shown in Table 1.

[0101] Example 5

[0102] Preparation of ordinary VO2(M) aerogel:

[0103] Five parts by weight of vanadium pentoxide were heated to a molten state and then uniformly mixed with deionized water at a mass ratio of 1:10. The mixture was filtered to obtain vanadium pentoxide gel. The gel was freeze-dried at -80℃ to obtain vanadium pentoxide powder. The powder was uniformly mixed with carbon powder and carbon nanotubes at a mass ratio of 10:2:1 and subjected to a carbothermic reduction reaction at 850℃ to obtain M-phase vanadium dioxide powder. VO2(M) was dissolved in an ethanol / water mixture (volume ratio 1:1), a small amount of dispersant was added, and the mixture was ultrasonically treated for 60 min to form a stable sol. After adjusting the pH to 8, the mixture was allowed to stand at 60℃ for 24 h to form a gel structure. The gel structure was then dried in a freeze-drying oven for 12 h to obtain VO2(M) aerogel.

[0104] In accordance with the provisions of GJB10055-2021, GJB8700-2015 and GB / T43249-2023, infrared performance tests were conducted under stable environmental conditions, and the test results are shown in Table 1.

[0105] Example 6

[0106] Preparation of bismuth antimonide thin films:

[0107] Using single-crystal silicon (001) as a substrate, Bi and Sb targets were first sputtered to obtain BiSb alloy thin films.

[0108] Before co-sputtering, the substrate needs to be cleaned with acetone, alcohol, and deionized water as a cleaning solution in an ultrasonic bath for 30 minutes to remove impurities from the substrate surface. After cleaning, the substrate is dried and placed in the sputtering chamber. Before sputtering, the target material is cleaned by bombarding with a pulsed laser at an energy of 400 mJ for 5 minutes.

[0109] During the co-sputtering process of bismuth antimonide thin films, the substrate temperature was 190℃, the distance between the target and the substrate was fixed at 60mm, the power applied to the target was 150W, the sputtering time was 20min, and the flow rates of the input working gases nitrogen and argon were maintained at 2.8sccm and 80sccm, respectively. After sputtering, the substrate temperature was maintained for a period of time to solidify the film. When the substrate temperature dropped to around room temperature, the vacuum was released and the sample was removed, yielding the bismuth antimonide thin film.

[0110] In accordance with the provisions of GJB10055-2021, GJB8700-2015 and GB / T43249-2023, infrared performance tests were conducted under stable environmental conditions, and the test results are shown in Table 1.

[0111] Table 1. Performance test results of the composite thin film materials prepared in Examples 1-6

[0112]

[0113] As can be seen from the above embodiments, the infrared stealth composite film material with multi-temperature dynamic adjustment provided by the present invention has low infrared emissivity, high infrared reflectivity and good heat insulation performance. Its infrared emissivity is 43% at low temperature, 40% to 58% at room temperature, and 51% at high temperature. The temperature response time is 1 to 3 seconds, and the working temperature range is -30 to 150°C.

[0114] The embodiments described above are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for preparing a multi-temperature dynamically adjustable infrared stealth composite film material, characterized in that, Comprise the following steps: (1) the preparation method of the modified boron nitride is: mixing boron nitride nanosheet and MOF material in deionized water at a mass ratio of 3-5:1, ultrasonic treatment for 1h, drying at 40-60℃ to obtain modified boron nitride; (2) preparation of temperature-sensitive nanocapsule: using ionic liquid template and electrochemical polymerization method, the blue phase liquid crystal is made into microcapsule, and nanocrystallization is carried out, the specific steps are as follows, 1-butyl-3-methylimidazolium hexafluorophosphate (C 11 H 18 N2P˙F6) was heated to 60-80℃, and blue phase liquid crystal powder was slowly added while stirring, and ultrasonic treatment was performed for 20-30 min to obtain a uniformly dispersed ionic liquid composite; A three electrode system is constructed with platinum sheet as working electrode, Ag / AgCl as reference electrode and stainless steel sheet as counter electrode, the ionic liquid compound is mixed with acrylic acid and sodium perchlorate, then injected into the electrochemical cell, and the electrochemical polymerization reaction is carried out, after the reaction, the capsule product on the electrode surface is washed with ethanol, then dispersed in ethanol solution, vacuum dried to obtain temperature-sensitive nanocapsule; (3) preparation of VO2(M) aerogel doped with modified boron nitride and temperature-sensitive nanocapsule: M-type vanadium dioxide is mixed with acetic acid, after adjusting the pH value to 8-10, the prepared modified boron nitride and powder temperature-sensitive nanocapsule are added, the mass ratio of VO2(M), modified boron nitride and powder temperature-sensitive nanocapsule is 4-8:3-5:1, magnetic stirring is carried out at 50-60℃, after the gel appears, drying in vacuum drying oven for 4-6h, finally the gel is dried at 40-60℃ for about one week to obtain composite aerogel; (4) preparation of bismuth antimony doped film: using BiSb alloy as main target material and In and W as doping target material, bismuth antimony doped film is prepared by co-sputtering method; (5) preparation of infrared stealth composite film: a layer of composite aerogel is coated on the bismuth antimony doped film at 20-25℃, the thickness ratio of the composite aerogel layer to the bismuth antimony doped film layer is 2-3:1; after standing, drying and curing, the infrared stealth composite film is obtained.

2. The production method according to claim 1, characterized by, The MOF material in step (1) is prepared by mixing UiO-66 and MIL-53 at a mass ratio of 3:1-5:1, adding surfactant polyvinylpyrrolidone, stirring and heating to 100-120℃, reacting for 12-20h by surface-induced epitaxial growth method, and finally centrifuging to obtain MIL-53 / UiO-66 composite material.

3. The method of claim 1, wherein: In the step (2), 1-butyl-3-methylimidazolium hexafluorophosphate (C 11 H 18 N2P˙F6) and the blue phase liquid crystal are used in a ratio of 5:1 to 2; the ion liquid compound, acrylic acid, and sodium perchlorate are used in a mass ratio of 10:3 to 6:0.3 to 0.5; the parameters of the electropolymerization reaction are as follows: polymerization for 30 to 90 min at 1.0 to 2.0 V; and the vacuum drying is performed at a temperature of 40 to 60 °C for 3 to 6 h.

4. The method of claim 1, wherein: The preparation method of the blue phase liquid crystal is: mixing chiral agent R10 and nematic phase liquid crystal E7 at a mass ratio of 1:5-10, melting at 80-100℃, ultrasonic treatment to mix uniformly, cooling to room temperature to obtain blue phase crystal mother liquor, under the conditions of 365nm light and 60℃, blue phase liquid crystal is obtained by light-induced polymerization.

5. The method of claim 1, wherein: The preparation method of M-type vanadium dioxide is: heating vanadium pentoxide to molten state, uniformly mixing with deionized water at a mass ratio of 1:5-10, filtering to obtain vanadium pentoxide gel, freeze-drying the vanadium pentoxide gel at-50--80℃ to obtain vanadium pentoxide powder, uniformly mixing the vanadium pentoxide powder with carbon powder and carbon nanotube at a mass ratio of 10:1-3:0.5-1, carrying out carbonthermal reduction reaction at 700-900℃ for 2-4h to obtain M-phase vanadium dioxide powder.

6. The method of claim 1, wherein: In step (4), the main target BiSb alloy is a BiSb alloy thin film prepared by co-sputtering of Bi and Sb targets on a single crystal silicon (001) substrate.

7. The method of claim 1, wherein: In the BiSb thin film doped with In and W, the mass ratio of the substances is Bi:Sb:In:W=3-10:3-10:1-2:

1.

8. The method of claim 7, wherein: In the co-sputtering process of the BiSb thin film doped with In and W, the power applied to the In and W targets is 15-50 W, the sputtering time is 40-70 min, the power applied to the main target is 150 W, the sputtering time is 20-30 min, the flow rates of the input working gases nitrogen and argon are maintained at 2.8 sccm and 80 sccm respectively, the substrate temperature is 180-200°C, the distance between the target and the substrate is fixed at 50-70 mm, after sputtering, the substrate temperature is maintained for a period of time to solidify the thin film, and after the substrate temperature drops to room temperature, the vacuum is released and the sample is taken out.

9. The method of claim 1, wherein: In step (5), an air compressor is used to spray the composite aerogel on the doped BiSb thin film; after spraying, it is left to stand for 1-2 h, and then placed in a drying oven at 100-150°C for solidification for 5-24 h.

10. The multi-temperature dynamically adjustable infrared stealth composite thin film material prepared by the preparation method of any one of claims 1-9, characterized in that, composed of a laminated composite aerogel layer and a doped BiSb thin film layer doped with indium and tungsten, the thickness ratio of the composite aerogel layer to the doped BiSb thin film layer is 2-3:1; the composite aerogel layer is prepared by drying and solidifying doped modified boron nitride, temperature-sensitive nano microcapsules and VO2(M) aerogel, and the mass ratio of the doped modified boron nitride, temperature-sensitive nano microcapsules and VO2(M) is 4-6:1-2:

1. the composite aerogel layer is prepared by drying and solidifying doped modified boron nitride, temperature-sensitive nano microcapsules and VO2(M) aerogel, and the mass ratio of the doped modified boron nitride, temperature-sensitive nano microcapsules and VO2(M) is 4-6:1-2:1.

Images