Method for preparing monodisperse silicon dioxide microspheres with controllable particle size based on seed growth method
By combining the Stöber method and the sodium silicate method, the generation rate of sodium silicate in the aqueous phase was controlled, and low-cost silica microspheres with controllable particle size were prepared. This solved the problems of high cost and difficulty in controlling nucleation and growth kinetics in the existing technology, and realized the large-scale production of monodisperse silica microspheres with controllable particle size.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XIAN LANQIAO NEW ENERGY TECH CO LTD
- Filing Date
- 2026-02-11
- Publication Date
- 2026-05-08
AI Technical Summary
Existing technologies struggle to achieve monodispersity and controllable particle size of silica microspheres at low cost, especially in large-scale production, where traditional methods are costly and difficult to control nucleation and growth kinetics.
Highly monodisperse silica seeds were prepared using the Stöber method, and controlled growth of sodium silicate in aqueous phase was achieved by controlling the formation rate of sodium silicate and combining it with low-cost sodium silicate, resulting in silica microspheres with excellent monodispersity and controllable particle size.
This method enables low-cost, large-scale production of silica microspheres with excellent monodispersity and controllable particle size, solving the problems of high cost and cumbersome steps in traditional methods, and ensuring the monodispersity and particle size uniformity of the product.
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Figure CN121990579A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of silica preparation technology, specifically relating to a method for preparing monodisperse silica microspheres with controllable particle size based on seed growth. Background Technology
[0002] Silica microspheres have wide applications in chromatographic packing materials, drug carriers, coating additives, photonic crystals, and standard metrology due to their excellent chemical stability, biocompatibility, ease of functionalization, and unique optical properties. Monodispersity (uniform size distribution) and precise controllable particle size are crucial to their performance. Currently, the commonly used classical Stöber method (using tetraethyl orthosilicate (TEOS) as the silicon source) can prepare highly monodisperse silica microspheres in an alcohol-water-ammonia system. However, preparing large-sized (>2 μm) particles requires large amounts of expensive TEOS and organic solvents, resulting in high costs and cumbersome multiple growth steps, hindering large-scale production. Furthermore, while the industrially widely used sodium silicate (water glass) method is inexpensive and readily available, the traditional acidification precipitation process makes it difficult to control nucleation and growth kinetics, resulting in products that are mostly aggregates or amorphous powders, unable to directly obtain monodisperse spherical particles, and unable to achieve precise particle size control. Therefore, there is an urgent need in this field for a silica microsphere preparation technology that can balance "monodispersibility of the product" with "process economy and scalability." If high-quality monodisperse small-particle silica obtained by the Stöber method can be used as "seeds," and then controlled growth of inexpensive sodium silicate can be achieved on their surface, it will have enormous industrial application potential. However, achieving a stable transfer of the seed from the alcohol phase system to the aqueous growth system, and effectively suppressing homogeneous nucleation of sodium silicate in the aqueous phase, are key challenges in realizing this technological path. Summary of the Invention
[0003] The purpose of this invention is to provide a method for preparing silica microspheres that combines monodispersity with low cost and large-scale production.
[0004] To achieve the above objectives, the present invention provides a method for preparing silica microspheres comprising the following steps:
[0005] Step 1: After uniformly mixing the nonpolar solvent with deionized water, add the organosilane and stir until homogeneous, then add the organic base and stir until homogeneous to obtain a transparent precursor solution; the nonpolar solvent is selected from any two of ethanol, methanol, and isopropanol; the organosilane is selected from any three of tetraethyl orthosilicate, tetramethyl orthosilicate, methyltrimethoxysilane, and methylsilane; the organic base is selected from any two of ammonia, triethanolamine, and N-methylpyrrolidone.
[0006] Step 2: Hydrolyze the transparent precursor solution from Step 1 at 60–80°C for 3–5 h to obtain a silica seed dispersion.
[0007] Step 3: Under stirring conditions, add sodium silicate aqueous solution with a concentration of 1-3 mol / L dropwise to the silica seed dispersion from Step 2, and add deionized water to control the pH of the reaction solution to 9-11. Continue stirring for 5-8 hours to obtain the grown silica dispersion.
[0008] Step 4: After preliminary separation of the silica dispersion grown in Step 3 by gravity sedimentation, the silica dispersion is washed by centrifugation with distilled water and anhydrous ethanol. The resulting precipitate is freeze-dried at a temperature gradient of -5 to -20℃ for 12 to 24 h to obtain monodisperse silica microsphere powder.
[0009] In step 1 above, the preferred volume ratio of the nonpolar solvent, deionized water, organosilane, and organic base is 100:25-40:2-5:6-10.
[0010] Furthermore, in step 1 above, the nonpolar solvent is preferably selected from any two of ethanol, methanol, and isopropanol in a volume ratio of 1:1 to 2.
[0011] Furthermore, in step 1 above, the organosilane is preferably selected from a mixture of any three of tetraethyl orthosilicate, tetramethyl orthosilicate, methyltrimethoxysilane, and methylsilane in a volume ratio of 1:0.5 to 2:0.3 to 3.
[0012] Furthermore, in step 1 above, the organic base is preferably selected from any two of ammonia, triethanolamine, and N-methylpyrrolidone in a volume ratio of 1:1 to 2.
[0013] In step 2 above, the concentration of silica seeds in the silica seed dispersion is preferably 0.1 to 0.5 mol / L.
[0014] In step 3 above, the preferred volume ratio of the silica seed dispersion to the sodium silicate aqueous solution is 1:0.8-4.
[0015] In step 3 above, the stirring speed is preferably 600-1000 r / min.
[0016] In step 4 above, the centrifugal washing is performed by centrifuging at a speed of 5000-8000 r / min for 6-10 min, and the washing process is repeated until the precipitate is clean.
[0017] In step 4 above, it is preferable to freeze-dry the obtained precipitate at -5 to -10°C for 10 to 12 hours, thaw it, and then freeze-dry it at -15 to -20°C for 4 to 8 hours.
[0018] The beneficial effects of this invention are as follows:
[0019] 1. This invention combines the advantages of the Stöber method (using TEOS as the silicon source to prepare the "core") with the sodium silicate precipitation method (used to construct the "shell"). The Stöber method ensures the perfect monodispersity of the initial seed, laying the foundation for the excellent morphology of the product; then, the widely available and low-cost sodium silicate is used to achieve subsequent low-cost, large-scale growth, effectively solving the problems of high cost and complicated steps in the scale-up production of the traditional Stöber method.
[0020] 2. This invention effectively overcomes the problem of explosive homogeneous nucleation caused by drastic pH changes in the traditional sodium silicate method by precisely controlling reaction kinetics. By ensuring that the generation rate of silicate ions is always lower than their heterogeneous deposition rate on the seed surface, secondary nucleation is completely suppressed, achieving pure heterogeneous growth of silicon species entirely on the seed surface. This not only ensures that the final product inherits the monodispersity of the seed but also enables precise and controllable scaling up of the microsphere size, ultimately obtaining silica microspheres with excellent monodispersity and controllable particle size. Attached Figure Description
[0021] Figure 1 This is a scanning electron microscope image of the SiO2 powder prepared in Comparative Example 1.
[0022] Figure 2 This is the X-ray powder diffraction pattern of the SiO2 powder prepared in Comparative Example 1.
[0023] Figure 3 This is a scanning electron microscope image of the SiO2 powder prepared in Comparative Example 2.
[0024] Figure 4 This is a scanning electron microscope image of the SiO2 powder prepared in Comparative Example 3.
[0025] Figure 5 This is a scanning electron microscope image of the SiO2 powder prepared in Example 1. Detailed Implementation
[0026] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments, but the scope of protection of the present invention is not limited to these embodiments.
[0027] Comparative Example 1
[0028] Step 1: Mix 100 mL of a 1:1 mixture of ethanol and methanol and 30 mL of deionized water evenly. Then add 3 mL of a 1:1:1 mixture of tetraethyl orthosilicate, tetramethyl orthosilicate, and methyltrimethoxysilane and stir continuously until homogeneous. Finally, slowly add 8 mL of a 1:1 mixture of ammonia and triethanolamine and stir until homogeneous to obtain a transparent precursor solution.
[0029] Step 2: Hydrolyze the transparent precursor solution from Step 1 at 60°C for 4 hours to obtain a silica seed dispersion.
[0030] Step 3: The silica seed dispersion from Step 2 is first centrifuged with distilled water at 5000 rpm for 10 min, then centrifuged with distilled water at 6000 rpm for 15 min. The resulting precipitate is freeze-dried at -10℃ for 10 h, thawed, and then freeze-dried at -20℃ for 5 h. After thawing, SiO2 powder is obtained. Figure 1 As shown, the prepared SiO2 is spherical with a size of about 150 nm. These microspheres are very uniform in size, have smooth surfaces, and have no obvious defects or agglomeration, which are typical characteristics of monodisperse microspheres. Figure 2 A broad and diffuse diffraction peak appears in the range of 2θ ≈ 15 to 30°, without sharp crystalline diffraction peaks, which is a typical characteristic of amorphous (non-crystalline) silicon dioxide.
[0031] Comparative Example 2
[0032] Step 1: Add 16 mL of 1 mol / L hydrochloric acid solution to 50 mL of 2.5 mol / L sodium silicate aqueous solution, stir the reaction system continuously for 20 min, and then let it stand for 30 min.
[0033] Step 2: Centrifuge the aged reaction mixture from Step 1 at 10000 r / min for 10 min. Discard the supernatant, and wash the precipitate alternately with deionized water and anhydrous ethanol, repeating this centrifugation and washing process a total of 8 times. Finally, dry the washed solid product at -10℃ for 12 h to obtain SiO2 powder. Figure 3 As shown, most of the prepared SiO2 particles are irregular spherical or near-spherical in shape, with relatively uniform size (about 30 nm), and no obvious large particles or sharp crystal edges.
[0034] Comparative Example 3
[0035] Step 1: Mix 100 mL of a 1:1 mixture of ethanol and methanol and 30 mL of deionized water evenly. Then add 3 mL of a 1:1:1 mixture of tetraethyl orthosilicate, tetramethyl orthosilicate, and methyltrimethoxysilane and stir continuously until homogeneous. Finally, slowly add 8 mL of a 1:1 mixture of ammonia and triethanolamine and stir until homogeneous to obtain a transparent precursor solution.
[0036] Step 2: The transparent precursor solution from Step 1 was hydrolyzed at 60°C for 4 hours under stirring at 600 r / min to obtain a 0.3 mol / L silica seed dispersion.
[0037] Step 3: Under stirring conditions of 800 r / min, add 50 mL of 0.3 mol / L sodium silicate aqueous solution to 40 mL of 0.3 mol / L silica seed dispersion, followed by adding 16 mL of 1 mol / L hydrochloric acid solution. Continue stirring at 800 r / min for 5 h to obtain the grown silica dispersion.
[0038] Step 4: The grown silica dispersion is first centrifuged with distilled water at 5000 rpm for 10 min, then centrifuged with distilled water at 6000 rpm for 15 min. The resulting precipitate is freeze-dried at -10℃ for 10 h, thawed, and then freeze-dried at -20℃ for 5 h. After thawing, SiO2 powder is obtained. Figure 4 As shown, the obtained SiO2 is spherical with a size of 100-300 nm and contains some unformed sol.
[0039] Example 1
[0040] Step 1: Mix 100 mL of a 1:1 mixture of ethanol and methanol and 30 mL of deionized water evenly. Then add 3 mL of a 1:1:1 mixture of tetraethyl orthosilicate, tetramethyl orthosilicate, and methyltrimethoxysilane and stir continuously until homogeneous. Finally, slowly add 8 mL of a 1:1 mixture of ammonia and triethanolamine and stir until homogeneous to obtain a transparent precursor solution.
[0041] Step 2: The transparent precursor solution from Step 1 was hydrolyzed at 60°C for 4 hours under stirring at 600 r / min to obtain a 0.3 mol / L silica seed dispersion.
[0042] Step 3: Under stirring conditions of 800 r / min, add 50 mL of 1 mol / L sodium silicate aqueous solution to 40 mL of 0.3 mol / L silica seed dispersion, and add deionized water to control the pH of the reaction solution to 10. Continue stirring for 5 h to obtain the grown silica dispersion.
[0043] Step 4: The grown silica dispersion is first centrifuged with distilled water at 5000 rpm for 10 min, then centrifuged with distilled water at 6000 rpm for 15 min. The resulting precipitate is freeze-dried at -10℃ for 10 h, thawed, and then freeze-dried at -20℃ for 5 h. After thawing, SiO2 powder is obtained. Figure 5 As shown, the prepared SiO2 is spherical with a size of about 400 nm, and is uniformly dispersed and of uniform size.
[0044] Comparing the results of Example 1 and Comparative Example 3, it can be seen that simply combining the Stöber method with the sodium silicate precipitation method cannot obtain monodisperse SiO2 microspheres with uniform cut size. In this invention, after generating monodisperse SiO2 seeds using the Stöber method, the concentration of sodium silicate and the pH value of the system are controlled to ensure that the generation rate of silicate ions is always lower than their heterogeneous deposition rate on the seed surface. This achieves precise and controllable scaling up of the microsphere particle size, and finally obtains silica microspheres with excellent monodispersity and controllable particle size.
[0045] Example 2
[0046] Step 1: Mix 100 mL of ethanol and isopropanol in a volume ratio of 1:2 with 40 mL of deionized water. Then add 5 mL of tetraethyl orthosilicate, tetramethyl orthosilicate, and methyltrimethoxysilane in a volume ratio of 1:1:1 and stir continuously until homogeneous. Then slowly add 10 mL of ammonia and N-methylpyrrolidone in a volume ratio of 1:1 and stir until homogeneous to obtain a transparent precursor solution.
[0047] Step 2: The transparent precursor solution from Step 1 was hydrolyzed at 70°C for 4 hours under stirring at 600 r / min to obtain a 0.2 mol / L silica seed dispersion.
[0048] Step 3: Under stirring conditions of 800 r / min, add 70 mL of 2 mol / L sodium silicate aqueous solution to 50 mL of 0.2 mol / L silica seed dispersion, and add deionized water to control the pH of the reaction solution to 10.5. Continue stirring for 5 h to obtain the grown silica dispersion.
[0049] Step 4: Centrifuge the grown silica dispersion at 5000 r / min for 10 min with distilled water, then centrifuge at 6000 r / min for 15 min with distilled water. Freeze-dry the resulting precipitate at -10℃ for 10 h, thaw it, and then freeze-dry it at -20℃ for 5 h. After thawing, SiO2 powder is obtained.
[0050] Example 3
[0051] Step 1: Mix 100 mL of a 1:1 mixture of ethanol and methanol and 30 mL of deionized water evenly. Then add 3 mL of a 1:2:0.5 mixture of tetraethyl orthosilicate, tetramethyl orthosilicate, and methylsilane and stir continuously until homogeneous. Finally, slowly add 8 mL of a 2:1 mixture of ammonia and triethanolamine and stir until homogeneous to obtain a transparent precursor solution.
[0052] Step 2: The transparent precursor solution from Step 1 was hydrolyzed at 60°C for 4 hours under stirring at 600 r / min to obtain a 0.3 mol / L silica seed dispersion.
[0053] Step 3: Under stirring conditions of 800 r / min, add 80 mL of 1 mol / L sodium silicate aqueous solution to 60 mL of 0.3 mol / L silica seed dispersion, and add deionized water to control the pH of the reaction solution to 11. Continue stirring for 5 h to obtain the grown silica dispersion.
[0054] Step 4: Centrifuge the grown silica dispersion at 5000 r / min for 10 min with distilled water, then centrifuge at 6000 r / min for 15 min with distilled water. Freeze-dry the resulting precipitate at -10℃ for 10 h, thaw it, and then freeze-dry it at -20℃ for 5 h. After thawing, SiO2 powder is obtained.
Claims
1. A method for preparing monodisperse silica microspheres with controllable particle size based on seed growth, characterized in that: The method includes the following steps: Step 1: After uniformly mixing a nonpolar solvent with deionized water, add an organosilane and stir until homogeneous, then add an organic base and stir until homogeneous to obtain a transparent precursor solution; the nonpolar solvent is selected from any two of ethanol, methanol, and isopropanol; the organosilane is selected from any three of tetraethyl orthosilicate, tetramethyl orthosilicate, methyltrimethoxysilane, and methylsilane; the organic base is selected from any two of ammonia, triethanolamine, and N-methylpyrrolidone. Step 2: Hydrolyze the transparent precursor solution from Step 1 at 60–80 °C for 3–5 h to obtain a silica seed dispersion; Step 3: Under stirring conditions, add sodium silicate aqueous solution with a concentration of 1-3 mol / L dropwise to the silica seed dispersion from Step 2, and add deionized water to control the pH of the reaction solution to 9-11. Continue stirring for 5-8 hours to obtain the grown silica dispersion. Step 4: After preliminary separation of the silica dispersion grown in Step 3 by gravity sedimentation, the silica dispersion is washed by centrifugation with distilled water and anhydrous ethanol. The resulting precipitate is freeze-dried at a temperature gradient of -5 to -20℃ for 12 to 24 h to obtain monodisperse silica microsphere powder.
2. The method for preparing monodisperse silica microspheres with controllable particle size based on seed growth method according to claim 1, characterized in that: In step 1, the volume ratio of the nonpolar solvent, deionized water, organosilane, and organic base is 100:25-40:2-5:6-10.
3. The method for preparing monodisperse silica microspheres with controllable particle size based on seed growth method according to claim 1 or 2, characterized in that: The nonpolar solvent is selected from any two of ethanol, methanol, and isopropanol in a volume ratio of 1:1 to 2.
4. The method for preparing monodisperse silica microspheres with controllable particle size based on seed growth method according to claim 1 or 2, characterized in that: The organosilane is selected from a mixture of any three of tetraethyl orthosilicate, tetramethyl orthosilicate, methyltrimethoxysilane, and methylsilane in a volume ratio of 1:0.5 to 2:0.3 to 3.
5. The method for preparing monodisperse silica microspheres with controllable particle size based on seed growth method according to claim 1 or 2, characterized in that: The organic base is selected from any two of ammonia, triethanolamine, and N-methylpyrrolidone in a volume ratio of 1:1 to 2.
6. The method for preparing monodisperse silica microspheres with controllable particle size based on seed growth method according to claim 1, characterized in that: In step 2, the concentration of silica seeds in the silica seed dispersion is 0.1–0.5 mol / L.
7. The method for preparing monodisperse silica microspheres with controllable particle size based on seed growth method according to claim 1 or 6, characterized in that: In step 3, the volume ratio of the silica seed dispersion to the sodium silicate aqueous solution is 1:0.8-4.
8. The method for preparing monodisperse silica microspheres with controllable particle size based on seed growth method according to claim 1, characterized in that: In step 3, the stirring speed is 600-1000 r / min.
9. The method for preparing monodisperse silica microspheres with controllable particle size based on seed growth method according to claim 1, characterized in that: In step 4, the centrifugal washing is performed by centrifuging at a speed of 5000-8000 r / min for 6-10 min, and the washing process is repeated until the precipitate is clean.
10. The method for preparing monodisperse silica microspheres with controllable particle size based on seed growth method according to claim 1, characterized in that: In step 4, the obtained precipitate is freeze-dried at -5 to -10°C for 10 to 12 hours, thawed, and then freeze-dried at -15 to -20°C for 4 to 8 hours.