A method for preparing a silica aerogel composite material with LSPR effect

Abstract

The application belongs to the technical field of silica aerogel modification, and discloses a preparation method of a silica aerogel composite material with LSPR effect. Method one: (1) preparing an amine group modified silica aerogel composite material; (2) after the amine group modified silica aerogel composite material is fully immersed in a molybdenum oxide quantum dot solution, separation is performed, the precipitate is taken, and drying is performed, and the target product is obtained. Method two: (1) stirring and mixing a silicon source and a molybdenum oxide quantum dot solution, uniformly stirring an amine group modifier, and standing at room temperature until a wet gel is formed; (2) performing solvent replacement on the wet gel obtained in step (1) in anhydrous ethanol; (3) performing aging treatment on the wet gel obtained in step (2); (4) drying the wet gel obtained in step (3) to obtain the target product. The composite material prepared by the application not only has good heat insulation performance, but also has the functions of infrared shielding and invisibility.

Description

Technical Field

[0001] This invention belongs to the field of silica aerogel modification technology, specifically relating to a method for preparing a silica aerogel composite material with LSPR effect. Background Technology

[0002] Silica aerogel is a novel porous functional material with both solid phase particles and pores at the nanoscale, and it is lightweight (0.003~0.35 g / cm³). 3 ), translucent (light transmittance > 60%), high specific surface area (600~1500m²) 2 With its superior properties such as high porosity (88~99.8%), low sound propagation velocity (~100m / s), low dielectric constant (1.01~1.1), and extremely low thermal conductivity (12~20mW / (m·K)), silica aerogel has broad application prospects in chemistry, thermal, acoustics, optics, and electrical fields, especially in high-efficiency thermal insulation materials, adsorbent materials, chemical catalysts, and their supports. Existing unmodified pure silica aerogels lack effective infrared shielding and stealth capabilities, a key drawback for high-temperature or military applications, and one of the core requirements driving its functional modification.

[0003] 2D amorphous molybdenum oxide quantum dots, as an amorphous material with LSPR effect (Weiqian Kong, WeiLiu, Xiaoli Zheng, Qun Xu Adv. Optical Mater., 2023), exhibit extremely strong plasmon resonance effect in the visible and near-infrared regions, and have a strong absorption effect on visible and near-infrared photons, thus possessing a certain infrared shielding stealth function.

[0004] Therefore, if molybdenum oxide quantum dots with LSPR effect and silica aerogel can be combined, a new type of infrared shielding stealth material can be obtained. Summary of the Invention

[0005] To address the problem that existing unmodified pure silica aerogels lack effective infrared shielding and stealth capabilities, the present invention aims to provide a method for preparing silica aerogel composite materials with LSPR effect. The silica aerogel composite materials prepared by the present invention possess certain infrared shielding and stealth capabilities.

[0006] To achieve the above objectives, the present invention provides two technical solutions, as follows: The first approach: A method for preparing a silica aerogel composite material with LSPR effect, comprising the following steps: (1) Preparation of amine-modified silica aerogel composite material; (2) After the amine-modified silica aerogel composite material is fully impregnated in the molybdenum oxide quantum dot solution, it is separated, the precipitate is taken and dried to obtain the target product; wherein the molybdenum oxide quantum dots are molybdenum oxide quantum dots with LSPR effect, and the solvent of the molybdenum oxide quantum dot solution is an aqueous solvent.

[0007] Preferably, in step (2), the ratio of raw material usage is amine-modified silica aerogel composite material : molybdenum oxide quantum dot solution = (200~500) mg : (10~30) mL.

[0008] Preferably, in step (2): the soaking time is 24~48h; the separation method is centrifugation, the centrifugation speed is 8000~12000r / min and the time is 5~10min; the drying is freeze drying, the freeze drying temperature is -40~-60℃ and the time is 24~48h.

[0009] The second approach: A method for preparing a silica aerogel composite material with LSPR effect, the steps of which are as follows: (1) Stir and mix the silicon source and molybdenum oxide quantum dot solution, add an amine modifier and stir evenly, and let stand at room temperature until a wet gel is formed; wherein, the molybdenum oxide quantum dots are molybdenum oxide quantum dots with LSPR effect, and the solvent of the molybdenum oxide quantum dot solution is an aqueous solvent. (2) The wet gel obtained in step (1) is placed in anhydrous ethanol for solvent exchange; (3) The wet gel obtained in step (2) is subjected to aging treatment; (4) Dry the wet gel obtained in step (3) to obtain the target product.

[0010] Preferably, the silicon source is tetraethyl orthosilicate, and the amine modifier is 3-aminopropyltriethoxysilane.

[0011] Preferably, in step (1), the ratio of raw material usage is silicon source: molybdenum oxide quantum dot solution: amine modifier = 2 mL: (1~5) mL: (1~3) mL.

[0012] In the two technical solutions mentioned above, the molybdenum oxide quantum dot solution is prepared according to the following preparation process: molybdenum disulfide is added to a mixed solvent composed of anhydrous ethanol and water and ultrasonically dispersed; then hydrogen peroxide solution is added to the dispersion, followed by supercritical CO2 treatment; the solution after supercritical CO2 treatment is irradiated with light, centrifuged, and the supernatant is taken, which is the molybdenum oxide quantum dot solution.

[0013] Preferably, the molybdenum disulfide: mixed solvent: hydrogen peroxide solution = (100~500) mg: (5~10) mL: (1~5) mL, and the concentration of hydrogen peroxide solution is 25~35 wt%; in the mixed solvent, the volume ratio of anhydrous ethanol: water is (3~5): (5~10); the conditions for supercritical CO2 treatment are: temperature 40~60℃, pressure 10~17 MPa, time 3~8 h; and light exposure time 3~5 h.

[0014] The core technology of this invention lies in the use of amine-modified silica aerogel. Because the nitrogen atom in the amine group has lone pair electrons, it can form coordinate bonds with metal ions, thereby realizing the composite of silica aerogel and molybdenum oxide quantum dots. This results in the final composite material having the LSPR effect of molybdenum oxide quantum dots and the high temperature resistance of silica aerogel.

[0015] The silica aerogel composite material with LSPR effect prepared by this invention can be used as an infrared shielding stealth material in the military field. It can shield infrared signals while insulating heat, thus avoiding detection.

[0016] In this invention, the preparation of the amine-modified silica aerogel composite material and the molybdenum oxide (LSPR) quantum dot solution are both existing technologies. The preparation of the amine-modified silica aerogel composite material can refer to, but is not limited to, the literature: CHOI H, HAN HH, PARALE VG, et al. Rigid amine-incorporatedsilica aerogel for highly efficient CO2 capture and heavy metal removal[J / OL]. Chemical Engineering Journal, 2024, 483: 149357. DOI:10.1016 / j.cej.2024.149357; the preparation of the molybdenum oxide (LSPR) quantum dot solution can refer to, but is not limited to, the literature: LIU W, XU Q. CO2‐Assisted Conversion of Crystal Two‐Dimensional MolybdenumOxide to Amorphism with Plasmon Resonances[J / OL]. Chemistry – A European Journal, 2018, 24(52): 13693-13700. DOI:10.1002 / chem.201801055.

[0017] Beneficial effects: (1) The silica aerogel composite material with LSPR effect prepared by the present invention has the unique structure, low density and high porosity of aerogel, as well as the LSPR effect of molybdenum oxide quantum dots, which has a strong absorption effect on infrared and near-infrared, so that the composite material not only has good heat insulation performance but also infrared shielding stealth function. (2) This invention realizes molybdenum oxide quantum dot composite silica aerogel, which represents a next-generation infrared stealth material technology path from "passive shielding" to "active control". It is not just a simple "1+1" composite, but a smart thermal management platform created through nanoscale fine design. Although it is currently mainly in the laboratory concept verification stage, it shows great potential in high-end defense equipment and spacecraft thermal control. (3) The preparation process of the present invention is simple and easy to control. It does not require long-term post-gelation modification during the preparation process, and no large amount of waste liquid is generated, which significantly shortens the preparation cycle and simplifies the synthesis process. Attached Figure Description

[0018] Figure 1 TEM images of the target product (a) obtained in Example 1, control product 1 (b) obtained in Comparative Example 1, and control sample 2 (c) obtained in Comparative Example 2.

[0019] Figure 2 FTIR images of the target product obtained in Example 1, control product 1 obtained in Comparative Example 1, and control sample 2 obtained in Comparative Example 2.

[0020] Figure 3 UV-VIS images of the target product obtained in Example 1, control product 1 obtained in Comparative Example 1, and control sample 2 obtained in Comparative Example 2. Detailed Implementation

[0021] To enable those skilled in the art to better understand the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the described embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the present invention.

[0022] Example 1 A method for preparing a silica aerogel composite material with LSPR effect, comprising the following steps: (1) Preparation of amine-modified silica aerogel composite material: 2 mL of tetraethyl orthosilicate, 1 mL of deionized water and 2 mL of anhydrous ethanol solution were stirred and mixed. 3 mL of 3-aminopropyltriethoxysilane was added and stirred for 1 min. The mixture was poured into a mold and kept at room temperature for 4 min to form a wet gel. The wet gel was placed in anhydrous ethanol for replacement 3 times (6 h each time) and aged at 60 °C for 24 h. After aging, the wet gel was dried in supercritical CO2 at 60 °C and 8 MPa for 24 h. The dried sample was ground into powder to obtain amine-modified silica aerogel composite material. (2) Preparation of molybdenum oxide quantum dot solution: Weigh 500 mg of molybdenum disulfide, add 3 mL of anhydrous ethanol and 7 mL of deionized water, stir and mix, and sonicate for 2 h to obtain a dispersion; then add 5 mL of 30 wt% hydrogen peroxide solution to the dispersion, and treat with supercritical CO2 at 40 °C and 17 MPa for 3 h; irradiate the supercritical CO2 treated solution under natural sunlight for 5 h, centrifuge at 3000 r / min for 20 min, and take the supernatant, which is the molybdenum oxide quantum dot solution; (3) Take 200mg of the amine-modified silica aerogel composite material powder obtained in step (1) and immerse it in 10mL of the molybdenum oxide quantum dot solution obtained in step (2) for 24h, centrifuge at 10000r / min for 5min, and freeze dry at -40℃ for 24h to obtain the target product.

[0023] Example 2 A method for preparing a silica aerogel composite material with LSPR effect, comprising the following steps: (1) Preparation of molybdenum oxide quantum dot solution: Same as step (2) in Example 1; (2) Mix 2 mL of tetraethyl orthosilicate and 3 mL of molybdenum oxide quantum dot solution, add 3 mL of 3-aminopropyltriethoxysilane and stir for 1 min, pour into a mold, and let stand at room temperature for 4 min to form a wet gel; place the wet gel in anhydrous ethanol for replacement 3 times (6 h each time), age at 60 °C for 24 h, and after aging, dry the wet gel in supercritical CO2 at 60 °C and 8 MPa for 24 h to obtain the target product.

[0024] Comparative Example 1 The difference from Example 1 is that no amine modification was performed on the silica aerogel, that is, in step (1), the amount of 3-aminopropyltriethoxysilane added was 0. The specific preparation steps of this comparative example are as follows: (1) Preparation of silica aerogel: (1.1) Mix 2 mL of tetraethyl orthosilicate with 1 mL of deionized water and 2 mL of anhydrous ethanol solution, add 20 μL of 36 wt% hydrochloric acid and stir for 1 h to fully hydrolyze the tetraethyl orthosilicate; (1.2) Dilute 30 μL of 28 wt% ammonia with 4 mL of deionized water. Slowly add the diluted ammonia to the hydrolysate obtained in step (1.1). After the addition is complete, stir for 1 min, pour into a mold, and let stand at room temperature for 4 min to form a wet gel. Place the wet gel in anhydrous ethanol for replacement 3 times (6 h each time), age at 60 °C for 24 h, and then dry the wet gel with supercritical CO2 at 60 °C and 8 MPa for 24 h. Grind the dried sample into powder to obtain silica aerogel. (2) Preparation of molybdenum oxide quantum dot solution: Same as step (2) in Example 1; (3) Take 200 mg of silica aerogel powder obtained in step (1) and soak it in 10 mL of molybdenum oxide quantum dot solution obtained in step (2) for 24 h, centrifuge at 10000 r / min for 5 min, freeze dry at -40℃ for 24 h to obtain control sample 1.

[0025] Comparative Example 2 The difference from Example 1 is that no molybdenum oxide quantum dot solution was added. The specific steps of this comparative example are as follows: 2 mL of tetraethyl orthosilicate was mixed with 1 mL of deionized water and 2 mL of anhydrous ethanol solution. 3 mL of 3-aminopropyltriethoxysilane was added and stirred for 1 min. The mixture was poured into a mold and allowed to stand at room temperature for 4 min to form a wet gel. The wet gel was placed in anhydrous ethanol for displacement three times (6 h each time) and aged at 60 °C for 24 h. After aging, the wet gel was dried in supercritical CO2 at 60 °C and 8 MPa for 24 h. The dried sample was ground into powder to obtain anamine-modified silica aerogel composite material, which served as control sample 2.

[0026] Characterization results Figure 1 These are TEM images of the target product (a) obtained in Example 1, control product 1 (b) obtained in Comparative Example 1, and control sample 2 (c) obtained in Comparative Example 2. Figure 1 It can be seen that: the particles in Example 1 are in an agglomerated state, but the particle size is relatively uniform, and there are moderately loose porous areas inside the aggregates. The overall structure is loose and the distribution is relatively uniform. The particles in Comparative Example 1 are fine but have a higher degree of agglomeration, showing a densely packed state. The pore structure is not obvious, and the boundaries between particles are relatively blurred. Although the particles in Comparative Example 2 are in an agglomerated state, the particle size is less uniform, and the structure of the aggregates is not uniform.

[0027] Figure 2 The images show the FTIR spectra of the target product obtained in Example 1, control product 1 obtained in Comparative Example 1, and control sample 2 obtained in Comparative Example 2. It is well known to those skilled in the art that in the infrared spectrum of conventional silica aerogels, 465 cm⁻¹... -1 The characteristic peak at 697 cm⁻¹ is attributed to the bending vibration of the Si-O-Si bond.-1 The characteristic peak at 1000~1200 cm⁻¹ is attributed to the symmetric stretching of Si-O-Si. -1 The characteristic peaks at this location belong to Si-O-Si antisymmetric stretching; these three elements together constitute the three major characteristic peaks of SiO2, and their combination clearly demonstrates the formation of the silicon-oxygen framework. Figure 2 It can be seen that: the sample of Comparative Example 1 only shows the antisymmetric stretching characteristic absorption peak of Si-O-Si (1000~1200cm). -1 Characteristic peaks of Si-OH (783.5 cm⁻¹) -1 ), without -NH2 (~1500cm) -1 Nearby), Mo-O (614cm) -1 The relevant absorption peaks indicate that it is a silicon-based material containing silanol groups. This is because: the silicon dioxide framework was destroyed after Comparative Example 1 was impregnated with molybdenum oxide quantum dot solution, hence the peak at 465 cm⁻¹. -1 697cm -1 The characteristic peaks related to silica disappeared. In Comparative Example 1, due to the collapse of the framework, a dense agglomerate was formed, resulting in a significant decrease in the transmittance of infrared light. Infrared light could not effectively penetrate and could not excite the vibration of internal Mo-O bonds. Only the surface Si-O-Si signal could be detected. Even if a small number of Mo-O bonds existed, the bonding environment was disordered due to the framework breakage, and the bond energy and vibration frequency were disordered, making it impossible to form a concentrated characteristic absorption peak, which was eventually masked by the infrared background. The sample in Comparative Example 2 showed -NH2 (~1500 cm⁻¹) -1 The characteristic absorption peaks near the Si-O-Si region and the three characteristic peaks at 465 cm⁻¹ -1 697cm -1 1000~1200cm -1 ), but without Mo-O (614cm) -1 Absorption peak (577 cm⁻¹ to its right) -1 The characteristic peak at the location is attributed to -Si-CH3), and the absorption of the Si-related functional group (Si-O-Si) is weak, indicating that it is an amino-containing material; the sample in Example 1 also shows -NH2 (~1500 cm⁻¹). -1 Nearby), Si-O-Si (465cm) -1 697cm -1 1000~1200cm -1 ), Mo-O (614cm) -1The characteristic absorption peak of Si-OH was observed, and compared with Comparative Example 2, the absorption of Si-OH was significantly weakened. At the same time, it integrated amino (-NH2), silicon-oxygen bond (Si-O-Si), and molybdenum-oxygen bond (Mo-O) functional groups, taking into account the structural characteristics of Comparative Example 1 and Comparative Example 2. It also added Mo-O functional group. The Si-OH content was much lower than that of Comparative Example 2, indicating that there were fewer hydroxyl residues on its silicon-based surface, and the material had better stability and binding with other substances.

[0028] Figure 3 These are the UV-VIS images of the target product obtained in Example 1, control product 1 obtained in Comparative Example 1, and control sample 2 obtained in Comparative Example 2. Figure 3 It can be seen that: Comparative Example 2 exhibits extremely low absorption intensity across the entire wavelength range of 200–1600 nm, with no obvious characteristic absorption peaks, especially in the near-infrared region (800–1600 nm), where absorption is almost nonexistent, indicating that it does not possess the LSPR (Local Surface Plasmon Resonance) effect; Comparative Example 1 only has absorption peaks in the short wavelength (200 nm) and the long wavelength (1400 nm) of the near-infrared region, but its absorption intensity in the core LSPR characteristic region of 800–1200 nm is very weak, and the LSPR effect is not significant; Example 1 exhibits a strong and broad characteristic absorption peak (typical LSPR feature) in the 800–1200 nm range, with an absorption intensity higher than Comparative Example 1 and Comparative Example 2, and also has effective absorption in the short wavelength range, with light absorption covering a broad band of "ultraviolet → visible → near-infrared," demonstrating a significant LSPR effect. Figure 1 The TEM results showed that the particles in Example 1 were uniform in size, with a loose aggregate structure and moderate porosity. This structure is conducive to the dispersion of nanoparticles and the excitation of the LSPR effect. In contrast, Comparative Example 2 did not have this structure (no LSPR), while Comparative Example 1 was excessively aggregated (LSPR effect was suppressed). The structure of Example 1 had a higher degree of matching with LSPR performance.

Claims

1. A method for preparing a silica aerogel composite material with LSPR effect, characterized in that, The steps are as follows: (1) Preparation of amine-modified silica aerogel composite material; (2) After the amine-modified silica aerogel composite material is fully impregnated in the molybdenum oxide quantum dot solution, it is separated, the precipitate is taken and dried to obtain the target product; wherein the molybdenum oxide quantum dots are molybdenum oxide quantum dots with LSPR effect, and the solvent of the molybdenum oxide quantum dot solution is an aqueous solvent.

2. The method for preparing the silica aerogel composite material with LSPR effect as described in claim 1, characterized in that, The molybdenum oxide quantum dot solution was prepared according to the following process: molybdenum disulfide was added to a mixed solvent consisting of anhydrous ethanol and water and ultrasonically dispersed; then hydrogen peroxide solution was added to the dispersion, followed by supercritical CO2 treatment; the supercritical CO2-treated solution was then irradiated with light, centrifuged, and the supernatant was collected, which is the molybdenum oxide quantum dot solution.

3. The method for preparing the silica aerogel composite material with LSPR effect as described in claim 2, characterized in that, Molybdenum disulfide: mixed solvent: hydrogen peroxide solution = (100~500) mg: (5~10) mL: (1~5) mL, the concentration of hydrogen peroxide solution is 25~35 wt%; in the mixed solvent, the volume ratio of anhydrous ethanol: water is (3~5): (5~10); the conditions for supercritical CO2 treatment are: temperature 40~60℃, pressure 10~17 MPa, time 3~8 h; the illumination time is 3~5 h.

4. The method for preparing the silica aerogel composite material with LSPR effect as described in any one of claims 1 to 3, characterized in that: In step (2), the ratio of raw materials used is amine-modified silica aerogel composite material : molybdenum oxide quantum dot solution = (200~500) mg : (10~30) mL.

5. The method for preparing the silica aerogel composite material with LSPR effect as described in any one of claims 1 to 3, characterized in that, In step (2): the soaking time is 24~48h; the separation method is centrifugation, the centrifugation speed is 8000~12000r / min and the time is 5~10min; the drying is freeze drying, the freeze drying temperature is -40~-60℃ and the time is 24~48h.

6. A method for preparing a silica aerogel composite material with LSPR effect, characterized in that, The steps are as follows: (1) Stir and mix the silicon source and molybdenum oxide quantum dot solution, add an amine modifier and stir evenly, and let stand at room temperature until a wet gel is formed; wherein, the molybdenum oxide quantum dots are molybdenum oxide quantum dots with LSPR effect, and the solvent of the molybdenum oxide quantum dot solution is an aqueous solvent. (2) The wet gel obtained in step (1) is placed in anhydrous ethanol for solvent exchange; (3) The wet gel obtained in step (2) is subjected to aging treatment; (4) Dry the wet gel obtained in step (3) to obtain the target product.

7. The method for preparing the silica aerogel composite material with LSPR effect as described in claim 6, characterized in that, The molybdenum oxide quantum dot solution was prepared according to the following process: molybdenum disulfide was added to a mixed solvent consisting of anhydrous ethanol and water and ultrasonically dispersed; then hydrogen peroxide solution was added to the dispersion, followed by supercritical CO2 treatment; the supercritical CO2-treated solution was then irradiated with light, centrifuged, and the supernatant was collected, which is the molybdenum oxide quantum dot solution.

8. The method for preparing the silica aerogel composite material with LSPR effect as described in claim 7, characterized in that, Molybdenum disulfide: mixed solvent: hydrogen peroxide solution = (100~500) mg: (5~10) mL: (1~5) mL, the concentration of hydrogen peroxide solution is 25~35 wt%; in the mixed solvent, the volume ratio of anhydrous ethanol: water is (3~5): (5~10); the conditions for supercritical CO2 treatment are: temperature 40~60℃, pressure 10~17 MPa, time 3~8 h; the illumination time is 3~5 h.

9. The method for preparing the silica aerogel composite material with LSPR effect as described in any one of claims 6 to 8, characterized in that: The silicon source is tetraethyl orthosilicate, and the amine modifier is 3-aminopropyltriethoxysilane.

10. The method for preparing the silica aerogel composite material with LSPR effect as described in any one of claims 6 to 8, characterized in that: In step (1), the ratio of raw materials used is silicon source: molybdenum oxide quantum dot solution: amine modifier = 2 mL: (1~5) mL: (1~3) mL.

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