Preparation method of super-hydrophobic SiO2 aerogel microspheres and product

Abstract

The invention discloses a preparation method of super-hydrophobic SiO2 aerogel microspheres, which comprises the following steps: adding double silicon source precursors methyltrimethoxysilane and dimethyldiethoxysilane into an aqueous solution of hexadecyl trimethyl ammonium bromide to form an oil-in-water emulsion; adding acetic acid and ammonia water to obtain an aqueous dispersion; quickly adding the aqueous dispersion into a normal hexane solution of Span-80, and stirring to obtain wet gel; the obtained wet gel is soaked in absolute ethyl alcohol to be aged, washed, subjected to suction filtration and dried, and the super-hydrophobic SiO2 aerogel microspheres are obtained. According to the preparation method, the content of hydrophobic methyl in the obtained aerogel microspheres can be effectively increased, and the SiO2 aerogel microspheres with regular morphology, uniform particle size, less adhesion, excellent hydrophobic performance and excellent heat insulation performance are prepared; reaction raw materials are low in price, reaction conditions are mild, and the method is suitable for industrial production.

Description

Technical Field

[0001] The present invention belongs to the technical field of synthesis of textile functional finishing materials, and particularly relates to a preparation method and product of SiO 2 aerogel microspheres. Background Art

[0002] The heat insulation materials suitable for fabric coating finishing can effectively block heat and play an important role in dealing with extreme weather. SiO 2 aerogel has low thermal conductivity, high porosity and high stability, and is an ideal fabric heat insulation coating material.

[0003] However, the bulk SiO 2 aerogel prepared by conventional methods cannot be directly applied to fabric coating finishing, and its mechanical strength is relatively low. Crushing and using it may damage the three-dimensional network structure of the aerogel and affect the heat insulation effect. In addition, the hydrophobicity of SiO 2 aerogel is relatively poor. The capillary force will damage the pore structure of the microspheres during the drying process, and the finishing liquid is likely to penetrate into the interior of the aerogel during the application process, affecting the heat insulation effect. Using hydrophobic methyltrimethoxysilane as the silicon source precursor, hydrolyzing and condensing in an emulsion system can obtain SiO 2 aerogel microspheres with certain hydrophobic properties. However, the number of hydrophobic methyl groups that the precursor methyltrimethoxysilane can provide is limited, and the hydrophobicity of SiO 2 aerogel microspheres still needs to be further improved to meet the application requirements in fabric coating finishing. Summary of the Invention

[0004] To solve the problems existing in the above-mentioned prior art, the present invention provides a preparation method of superhydrophobic SiO 2 aerogel microspheres. The method has simple steps, and the obtained product has excellent hydrophobic properties and outstanding heat insulation properties.

[0005] A preparation method of superhydrophobic SiO 2 aerogel microspheres, comprising: adding the double silicon source precursors methyltrimethoxysilane and dimethyldiethoxysilane to an aqueous solution of cetyltrimethylammonium bromide to obtain an oil-in-water emulsion; adding acetic acid and ammonia water to obtain an aqueous dispersion; quickly adding the aqueous dispersion to a n-hexane solution of Span-80, and stirring to obtain a wet gel; immersing and aging the obtained wet gel in absolute ethanol, washing, filtering by suction, and drying to obtain superhydrophobic SiO 2 aerogel microspheres.

[0006] A superhydrophobic SiO 2Preparation method of aerogel microspheres, comprising: at room temperature, adding cationic surfactant cetyltrimethylammonium bromide into deionized water, stirring to dissolve, adding double silicon source precursors methyltrimethoxysilane and dimethyldiethoxysilane, and stirring evenly to form an oil-in-water emulsion. Subsequently, adding acetic acid to catalyze the hydrolysis of the silicon source precursor into silanol, and adding ammonia water to catalyze the condensation of silanol to obtain an aqueous dispersion. Then, quickly transferring the aqueous dispersion into a n-hexane solution of Span-80 and stirring evenly to form a water-in-oil emulsion, enabling the silanol to continue to condense in the emulsion to obtain a wet gel. Soaking and aging the wet gel in absolute ethanol, and after washing, suction filtration, and drying treatments, obtaining the superhydrophobic SiO 2 aerogel microspheres.

[0007] Furthermore, a preparation method of superhydrophobic SiO 2 aerogel microspheres, comprising: at room temperature, adding cetyltrimethylammonium bromide into deionized water, stirring to dissolve, adding double silicon source precursors methyltrimethoxysilane and dimethyldiethoxysilane to form an oil-in-water emulsion. Subsequently, adding acetic acid with a concentration of 5%, stirring for 15 min, then adding ammonia water with a concentration of 0.50 mol / L to obtain an aqueous dispersion. Quickly adding the above aqueous dispersion into a n-hexane solution of Span-80, continuing to stir for 30 min, then soaking and aging the obtained wet gel in absolute ethanol for 3 h, washing, suction filtering, and drying to obtain superhydrophobic SiO 2 aerogel microspheres.

[0008] The present invention uses hydrophobic methyltrimethoxysilane and dimethyldiethoxysilane as double silicon source precursors, hydrolyzing and condensing in an emulsion system emulsified by cetyltrimethylammonium bromide and Span-80 to prepare SiO 2 aerogel microspheres, which can increase the hydrophobic methyl content in the obtained aerogel microspheres, effectively improve the hydrophobicity of the microspheres, and meet the application requirements in fabric finishing.

[0009] Preferably, calculated based on the amount of deionized water used being 15.0 mL, the total amount of methyltrimethoxysilane and dimethyldiethoxysilane is 5.0 mL, and the volume ratio is 2:1 to 7:1; more preferably 4:1 to 7:1; even more preferably 6:1.

[0010] Preferably, calculated based on the amount of deionized water used being 15.0 mL, the amount of cetyltrimethylammonium bromide is 0.05 g to 0.25 g; more preferably 0.075 g to 0.20 g; even more preferably 0.10 g.

[0011] Preferably, based on the amount of deionized water being 15.0 mL, the amount of acetic acid with a concentration of 5% is 0.05 mL to 0.30 mL; more preferably 0.10 mL to 0.20 mL; even more preferably 0.15 mL.

[0012] Preferably, based on the amount of deionized water being 15.0 mL, the amount of ammonia water with a concentration of 0.50 mol / L is 0.80 mL to 1.3 mL; more preferably 0.80 mL to 1.0 mL; even more preferably 0.90 mL.

[0013] Preferably, based on the amount of deionized water being 15.0 mL, the amount of Span-80 is 0.20 g to 0.70 g; more preferably 0.30 g to 0.50 g; even more preferably 0.40 g.

[0014] Preferably, in the reaction system, based on the amount of deionized water being 15.0 mL, the amount of n-hexane is 60 mL.

[0015] As a specific preference, a method for preparing superhydrophobic SiO 2 aerogel microspheres includes: At room temperature, cetyltrimethylammonium bromide (with an amount of 0.05 g to 0.25 g) is added to 15 mL of deionized water and stirred until dissolved, and methyltrimethoxysilane and dimethyldiethoxysilane (with a total amount of 5.0 mL and a volume ratio of 2:1 to 7:1) are added to form an oil-in-water emulsion. Subsequently, acetic acid with a concentration of 5% (with an amount of 0.05 mL to 0.30 mL) is added, and after stirring for 15 min, ammonia water with a concentration of 0.50 mol / L (with an amount of 0.80 mL to 1.30 mL) is added to obtain an aqueous dispersion. The above aqueous dispersion is quickly added to a n-hexane solution of 60 mL Span-80 (with an amount of 0.20 g to 0.70 g), and after continuing to stir for 30 min, the obtained wet gel is soaked and aged in absolute ethanol for 3 h, washed, filtered by suction, and dried to obtain superhydrophobic SiO 2 aerogel microspheres.

[0016] Specifically, a method for preparing superhydrophobic SiO 2 aerogel microspheres includes the following steps: (1) At room temperature, 0.05 g to 0.25 g of cetyltrimethylammonium bromide is added to 15 mL of deionized water and stirred until dissolved. Subsequently, 5.0 mL of a mixture of methyltrimethoxysilane and dimethyldiethoxysilane with a volume ratio of 2:1 to 7:1 is added and stirred evenly.

[0017] (2) Add 0.05 mL to 0.30 mL of 5% acetic acid to the above solution, stir for 15 min, then add 0.80 mL to 1.3 mL of 0.50 mol / L ammonia water to obtain an aqueous dispersion. Subsequently, quickly add the above aqueous dispersion to 60 mL of n-hexane solution with 0.20 g to 0.70 g of Span-80, and continue to stir for 30 min to obtain a wet gel.

[0018] (3) Immerse the obtained wet gel in absolute ethanol for 3 h, wash, filter by suction, and dry to obtain superhydrophobic SiO 2 aerogel microspheres.

[0019] Experiments have proved that the superhydrophobic SiO 2 aerogel microspheres prepared by the present invention have regular morphology, uniform particle size, and less adhesion to each other. After testing, the thermal conductivity of the microspheres is 0.0454 W / m·k, and the water contact angle is as high as 160.0°, showing excellent hydrophobic performance and outstanding heat insulation performance.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) In the preparation method of the present invention, hydrophobic methyltrimethoxysilane and dimethyldiethoxysilane are used as double silicon source precursors, which are hydrolyzed and condensed in an emulsion system to obtain superhydrophobic SiO 2 aerogel microspheres with regular morphology, less adhesion, and excellent hydrophobic performance.

[0021] (2) In the preparation method of the present invention, the raw materials are inexpensive and the reaction conditions are mild, which is suitable for industrial production. Description of the Drawings

[0022] Figure 1 are the thermal conductivities of superhydrophobic SiO 2 aerogel microspheres prepared under different volume ratios of methyltrimethoxysilane (MTMS) and dimethyldiethoxysilane (DMDES).

[0023] Figure 2 are the thermal conductivities of superhydrophobic SiO 2 aerogel microspheres prepared under different dosages of cetyltrimethylammonium bromide (CTAB).

[0024] Figure 3 are the thermal conductivities of superhydrophobic SiO 2 aerogel microspheres prepared under different dosages of acetic acid.

[0025] Figure 4 are the thermal conductivities of superhydrophobic SiO 2 aerogel microspheres prepared under different dosages of ammonia water.

[0026] Figure 5 are the thermal conductivity coefficients of SiO 2 aerogel microspheres prepared with different amounts of Span-80.

[0027] Figure 6 is the infrared spectrum of the superhydrophobic SiO 2 aerogel microspheres prepared in Example 1.

[0028] Figure 7 is the scanning electron microscope image of the superhydrophobic SiO 2 aerogel microspheres prepared in Example 1.

[0029] Figure 8 is the water contact angle image of the superhydrophobic SiO 2 aerogel microspheres prepared in Example 1. Detailed implementation manners

[0030] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. After reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0031] Example 1

[0032] At room temperature, 0.10 g of cetyltrimethylammonium bromide was added to 15 mL of deionized water and stirred until dissolved, and 4.285 mL of methyltrimethoxysilane and 0.715 mL of dimethyldiethoxysilane were added to form an oil-in-water emulsion. Subsequently, 0.15 mL of 5% acetic acid was added, and after stirring for 15 min, 0.90 mL of 0.50 mol / L ammonia water was added to obtain an aqueous dispersion. The above aqueous dispersion was quickly added to 60 mL of a n-hexane solution with 0.40 g of Span-80, and after continuing to stir for 30 min, the obtained wet gel was soaked and aged in absolute ethanol for 3 h, washed, filtered by suction, and dried to obtain superhydrophobic SiO 2 aerogel microspheres.

[0033] A small amount of the prepared superhydrophobic SiO 2 aerogel microspheres was mixed and ground with chromatographically pure potassium bromide particles and then pressed into a tablet, and its infrared spectrum was tested by Fourier transform infrared spectroscopy, as Figure 6 shown. It can be clearly observed from Figure 6 the Si-O-Si vibration peak at 1030 cm -1 , the Si-C vibration peaks at 1270 cm -1 and 780 cm -1 , proving SiO2 Successful preparation of aerogel microspheres.

[0034] Example 2: Optimization of the volume ratio of methyltrimethoxysilane and dimethyldiethoxysilane At room temperature, 0.10 g of cetyltrimethylammonium bromide was added to 15 mL of deionized water and stirred until dissolved. Then, methyltrimethoxysilane and dimethyldiethoxysilane with a total volume of 5 mL and volume ratios of 2:1, 3:1, 4:1, 5:1, 6:1, 7:1 were added to form an oil-in-water emulsion. Subsequently, 0.10 mL of 5% acetic acid was added, and after stirring for 15 min, 1.0 mL of 0.50 mol / L ammonia water was added to obtain an aqueous dispersion. The above aqueous dispersion was quickly added to 60 mL of a hexane solution containing 0.40 g of Span-80. After continuing to stir for 30 min, the obtained wet gel was soaked and aged in absolute ethanol for 3 h, washed, filtered by suction, and dried to obtain superhydrophobic SiO 2 aerogel microspheres. The thermal conductivity of the SiO 2 aerogel microspheres was tested, and the results are as Figure 1 shown. It can be Figure 1 seen that when the volume ratio of methyltrimethoxysilane and dimethyldiethoxysilane is 6:1, the thermal conductivity of the microspheres is the lowest.

[0035] Example 3: Optimization of the amount of cetyltrimethylammonium bromide At room temperature, 0.05 g, 0.075 g, 0.10 g, 0.15 g, 0.20 g, 0.25 g of cetyltrimethylammonium bromide were respectively added to 15 mL of deionized water and stirred until dissolved. Then, 4.285 mL of methyltrimethoxysilane and 0.715 mL of dimethyldiethoxysilane were added to form an oil-in-water emulsion. Subsequently, 0.10 mL of 5% acetic acid was added, and after stirring for 15 min, 1.0 mL of 0.50 mol / L ammonia water was added to obtain an aqueous dispersion. The above aqueous dispersion was quickly added to 60 mL of a hexane solution containing 0.40 g of Span-80. After continuing to stir for 30 min, the obtained wet gel was soaked and aged in absolute ethanol for 3 h, washed, filtered by suction, and dried to obtain superhydrophobic SiO 2 aerogel microspheres. The thermal conductivity of the SiO 2 aerogel microspheres was tested, and the results are as Figure 2 shown. It can be Figure 2 seen that when the amount of cetyltrimethylammonium bromide is 0.10 g, the thermal conductivity of the microspheres is the lowest.

[0036] Example 4: Optimization of the amount of acetic acid At room temperature, 0.10 g of cetyltrimethylammonium bromide was added to 15 mL of deionized water and stirred until dissolved. Then, 4.285 mL of methyltrimethoxysilane and 0.715 mL of dimethyldiethoxysilane were added to form an oil-in-water emulsion. Subsequently, 0.05 mL, 0.10 mL, 0.15 mL, 0.20 mL, 0.25 mL, and 0.30 mL of 5% acetic acid were added respectively. After stirring for 15 min, 1.0 mL of 0.50 mol / L ammonia water was added to obtain an aqueous dispersion. The above aqueous dispersion was quickly added to 60 mL of a hexane solution containing 0.40 g of Span-80. After continuing to stir for 30 min, the obtained wet gel was soaked and aged in absolute ethanol for 3 h, washed, filtered by suction, and dried to obtain superhydrophobic SiO 2 aerogel microspheres. The thermal conductivity of the SiO 2 aerogel microspheres was tested, and the results are as Figure 3 shown. It can be seen from Figure 3 that when the amount of acetic acid used is 0.15 mL, the thermal conductivity of the microspheres is the lowest.

[0037] Example 5: Optimization of the amount of ammonia water At room temperature, 0.10 g of cetyltrimethylammonium bromide was added to 15 mL of deionized water and stirred until dissolved. Then, 4.285 mL of methyltrimethoxysilane and 0.715 mL of dimethyldiethoxysilane were added to form an oil-in-water emulsion. Subsequently, 0.15 mL of 5% acetic acid was added. After stirring for 15 min, 0.80 mL, 0.90 mL, 1.0 mL, 1.1 mL, 1.2 mL, and 1.3 mL of 0.50 mol / L ammonia water were added respectively to obtain an aqueous dispersion. The above aqueous dispersion was quickly added to 60 mL of a hexane solution containing 0.40 g of Span-80. After continuing to stir for 30 min, the obtained wet gel was soaked and aged in absolute ethanol for 3 h, washed, filtered by suction, and dried to obtain superhydrophobic SiO 2 aerogel microspheres. The thermal conductivity of the SiO 2 aerogel microspheres was tested, and the results are as Figure 4 shown. It can be seen from Figure 4 that when the amount of ammonia water used is 0.90 mL, the thermal conductivity of the microspheres is the lowest.

[0038] Example 6: Optimization of the amount of Span80 At room temperature, 0.10 g of cetyltrimethylammonium bromide was added to 15 mL of deionized water and stirred until dissolved. Then, 4.285 mL of methyltrimethoxysilane and 0.715 mL of dimethyldiethoxysilane were added to form an oil-in-water emulsion. Subsequently, 0.15 mL of 5% acetic acid was added, and after stirring for 15 min, 0.90 mL of 0.50 mol / L ammonia water was added to obtain an aqueous dispersion. The above aqueous dispersion was quickly added to 60 mL of n-hexane solutions containing 0.20 g, 0.30 g, 0.40 g, 0.50 g, 0.60 g, and 0.70 g of Span-80 respectively. After continuing to stir for 30 min, the obtained wet gel was soaked and aged in absolute ethanol for 3 h, washed, filtered by suction, and dried to obtain superhydrophobic SiO 2 aerogel microspheres. The thermal conductivity of the SiO 2 aerogel microspheres was measured, and the results are as Figure 5 shown. It can be seen from Figure 5 that when the amount of Span80 is 0.40 g, the thermal conductivity of the microspheres is the lowest.

[0039] The microscopic morphology of the superhydrophobic SiO 2 aerogel microspheres prepared in Example 1 is as Figure 7 shown. It can be seen from the figure that the average particle size of the microspheres is about 500 nm, and the particle size distribution is uniform, the morphology is regular, and the adhesion is less, which can meet the application requirements in the fields of coating, filling, etc. After testing, the thermal conductivity of the superhydrophobic SiO 2 aerogel microspheres prepared in Example 1 is 0.0454 W / m·k, and the water contact angle is as high as 160.0° (as Figure 8 shown), indicating that the microspheres have excellent hydrophobic properties and excellent heat insulation properties. The main reasons are as follows: During the preparation of the SiO 2 aerogel microspheres, two hydrophobic silicon source precursors, methyltrimethoxysilane and dimethyldiethoxysilane, were used. A large number of hydrophobic methyl groups in the precursors were retained in the structure of the SiO 2 aerogel microspheres after hydrolysis and condensation, endowing the microspheres with excellent hydrophobicity, preventing the capillary force from destroying the pore structure of the microspheres during the drying process, and ensuring the heat insulation performance of the microspheres; In addition, the hydrolysis and condensation processes of the silicon source precursors were carried out in the emulsion system, which could effectively prevent the adhesion of the microspheres and also ensured the heat insulation performance of the microspheres.

Claims

1. A method for preparing super-hydrophobic SiO2 aerogel microspheres, characterized in that: include: Adding methyltrimethoxysilane and dimethyldiethoxysilane, two silicon source precursors, into an aqueous solution of hexadecyltrimethylammonium bromide to obtain an oil-in-water emulsion; adding acetic acid and aqueous ammonia to obtain an aqueous dispersion; The aqueous dispersion was quickly added to the n-hexane solution of Span-80 and stirred to obtain a wet gel; The obtained wet gel is immersed in anhydrous ethanol for aging, washed, filtered and dried to obtain super-hydrophobic SiO2 aerogel microspheres.

2. The method for preparing super-hydrophobic SiO2 aerogel microspheres according to claim 1, characterized in that: At room temperature, hexadecyl trimethyl ammonium bromide was added to deionized water and stirred to dissolve, and methyl trimethoxysilane and dimethyl diethoxysilane, two silicon source precursors, were added to form an oil-in-water emulsion. Subsequently, acetic acid with a concentration of 5% was added, and after stirring for 15 min, ammonia water with a concentration of 0.50 mol / L was added to obtain an aqueous dispersion. The above aqueous dispersion was quickly added to the n-hexane solution of Span-80, and after continuing to stir for 30 min, the obtained wet gel was immersed in anhydrous ethanol for aging for 3 h, washed, filtered, and dried to obtain superhydrophobic SiO2 aerogel microspheres.

3. The method for preparing super-hydrophobic SiO2 aerogel microspheres according to claim 1, characterized in that: Calculated based on the usage of 15.0 mL of deionized water, the total usage of the methyltrimethoxysilane and dimethyldiethoxysilane is 5.0 mL, and the volume ratio is 2:1 to 7:

1.

4. The method for preparing super-hydrophobic SiO2 aerogel microspheres according to claim 1, characterized in that: Based on the usage of 15.0 mL of deionized water, the usage of hexadecyltrimethylammonium bromide is 0.05 g to 0.25 g.

5. The method for preparing super-hydrophobic SiO2 aerogel microspheres according to claim 1, characterized in that: Based on the usage of 15.0 mL of deionized water, the acetic acid is a 5% aqueous acetic acid solution with a usage of 0.05 mL to 0.30 mL.

6. The method for preparing super-hydrophobic SiO2 aerogel microspheres according to claim 1, characterized in that: Calculated based on the usage of 15.0 mL of deionized water, the concentration of the ammonia water is 0.50 mol / L, and the usage is 0.80 mL to 1.30 mL.

7. The method for preparing super-hydrophobic SiO2 aerogel microspheres according to claim 1, characterized in that: Based on the usage of 15.0 mL of deionized water, the usage of n-hexane is 60.0 mL.

8. The method for preparing super-hydrophobic SiO2 aerogel microspheres according to claim 1, characterized in that: Based on the usage of 15.0 mL of deionized water, the usage of Span-80 is 0.20 g to 0.70 g.

9. A super hydrophobic SiO2 aerogel microsphere, characterized in that: The method is prepared according to any one of claims 1 to 8.

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