Process for the preparation of monodisperse silica with adjustable particle size

Abstract

The application relates to the technical field of silicon dioxide, and discloses a preparation process of monodisperse silicon dioxide with adjustable particle size; ethanol, water, a polyethylene glycol cationic surfactant, an alkylamine, tetraethyl orthosilicate are added into a reaction container, ammonia water is added dropwise after stirring, and then the mixture is aged, washed and calcined after stirring to obtain monodisperse silicon dioxide with adjustable particle size. The polyethylene glycol cationic surfactant contains a polyethylene glycol molecular chain segment and can be used as a structure directing agent; meanwhile, the polyethylene glycol cationic surfactant contains a quaternary ammonium salt group and can be used as a cationic surfactant; in an aqueous solution, the polyethylene glycol cationic surfactant self-assembles to form nanoscale micelles, forms a micellar template, induces the deposition of silicon dioxide, adsorbs and directionally deposits silicon dioxide precursors on the micellar template, and finally is calcined at high temperature to obtain silicon dioxide particles with different particle sizes, high specific surface areas and high dispersity, which have good practical application in chromatographic column fillers and the like.

Description

Technical Field

[0001] This invention relates to the field of silica technology, specifically to a process for preparing monodisperse silica with adjustable particle size. Background Technology

[0002] Silica has advantages such as chemical stability, easy surface modification, and stable separation performance. It can also be used to develop various types of packing materials, such as reversed-phase, normal-phase, and ion-exchange packing materials, which can be adapted to different sample separation scenarios and have wide applications in chromatographic column separation. By adjusting the particle size of silica and changing the resistance of the mobile phase, the chromatographic peak shape and separation speed can be optimized.

[0003] Traditional methods for preparing silica primarily involve the sol-gel method, using raw materials such as tetraethyl orthosilicate and sodium silicate, and adding additives such as hexadecyltrimethylammonium bromide, sodium dodecylbenzenesulfonate, polyethylene glycol, and polyvinylpyrrolidone to obtain silica particles with different morphologies and tunable pore sizes. Patent CN106190106B discloses near-infrared mesoporous silica nanoprobes targeting tumors and their preparation method. Using raw materials such as hexadecyltrimethylammonium bromide, tetraethyl orthosilicate, indocyanine green, and polyethylene glycol, the prepared mesoporous silica has advantages such as large specific surface area and small particle size. However, this patent struggles to achieve tunable silica particle size, which hinders its practical application in chromatographic column packing and other applications. Summary of the Invention

[0004] (a) Technical problems to be solved: In view of the shortcomings of the existing technology, the present invention solves the problems of large particle size and poor dispersibility of silica.

[0005] (II) To solve the above-mentioned technical problems, the technical solution of the present invention is: a preparation process for monodisperse silica with adjustable particle size: (1) Add N,N-dimethylformamide, 1 mol: (1-1.2) mol: (1-1.1) mol: (0.24-0.36) mol of polyethylene glycol, N-methyliminodiacetic acid, N,N-dicyclohexylcarbodiimide, and 4-dimethylaminopyridine to the reaction vessel, and carry out the reaction. Distill the solution under reduced pressure, wash the product with petroleum ether, and dry to obtain the polyethylene glycol precursor.

[0006] (2) Add N,N-dimethylformamide, 100g:(7-16)g of polyethylene glycol precursor and chloroalkanes to the reaction vessel, carry out the reaction, distill the solution under reduced pressure, wash the product with petroleum ether, and dry to obtain polyethylene glycol cationic surfactant.

[0007] (3) Add ethanol and water to the reaction vessel in a ratio of (3-7) g: (16-25) g: 100 g: (18-26) mL, along with polyethylene glycol cationic surfactant, alkylamine, tetraethyl orthosilicate, and ammonia. After stirring, allow the mixture to stand and age. After filtration, wash the product with ethanol and water, dry it, and then calcine it in a muffle furnace. After cooling, obtain monodisperse silica with adjustable particle size.

[0008] Furthermore, in (1), the molecular weight of polyethylene glycol is 400-1000.

[0009] Furthermore, in (1), the reaction temperature is 20-35℃ and the reaction time is 12-18h.

[0010] Furthermore, the structural formula of the chloroalkane in (2) is Cl-C n H 2n+1 n is 2-6.

[0011] Furthermore, in (2), the reaction temperature is 90-120℃ and the reaction time is 18-36h.

[0012] Furthermore, the mass concentration of ammonia in (3) is 22-28%.

[0013] Furthermore, the structural formula of the alkylamine in (3) is NH2-C a H2 a +1, a is 12-16.

[0014] Furthermore, in (3), the aging temperature is 20-30℃ and the aging time is 24-36h.

[0015] Furthermore, in (3), the heating rate during calcination is 5-10℃ / min, the temperature is raised to 550-650℃, and the calcination is maintained for 4-6 hours.

[0016] (III) Beneficial Technical Effects: This invention uses tetraethyl orthosilicate as the silicon source and adds polyethylene glycol cationic surfactant, which contains polyethylene glycol molecular chain segments and can act as a structure directing agent. It also contains quaternary ammonium salt groups and acts as a cationic surfactant. In aqueous solution, it self-assembles to form nanoscale micelles, forming a micelle template, which induces the deposition of silica. The silica precursor is adsorbed and directionally deposited on the micelle template. Finally, after high-temperature calcination, silica particles with high specific surface area and high dispersibility are obtained. By controlling the molecular weight of polyethylene glycol and the chain length of the polyethylene glycol cationic surfactant, silica particles with different particle sizes can be obtained. It has good practical applications in chromatographic column packing and other fields. Attached Figure Description

[0017] Figure 1 This is a scanning electron microscope image of the monodisperse silica prepared in Example 1.

[0018] Figure 2 This is a scanning electron microscope image of the monodisperse silica prepared in Example 2.

[0019] Figure 3 This is a scanning electron microscope image of the monodisperse silica prepared in Example 3. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below. However, it should be understood that the description herein is merely illustrative and not intended to limit the scope of the invention.

[0021] Example 1: (1) Add 80 mL of N,N-dimethylformamide, 10 mmol of polyethylene glycol 400 (about 4.0 g), 11 mmol of N-methyliminodiacetic acid, 10 mmol of N,N-dicyclohexylcarbodiimide, and 2.8 mmol of 4-dimethylaminopyridine to the reaction vessel, stir and react at 25 °C for 12 h, distill the solution under reduced pressure, wash the product with petroleum ether, and dry to obtain the polyethylene glycol precursor.

[0022] (2) Add 60 mL of N,N-dimethylformamide, 5 g of polyethylene glycol precursor and 0.35 g of 1-chloropropane to a reaction vessel equipped with a reflux condenser, heat to 110 °C, stir and react for 18 h, distill the solution under reduced pressure, wash the product with petroleum ether, and dry to obtain polyethylene glycol cationic surfactant.

[0023] (3) Add 3.5L of ethanol, 5L of water, 5.7g of polyethylene glycol cationic surfactant, 16g of dodecylamine, and 100g of tetraethyl orthosilicate to the reaction vessel. After stirring, add 20mL of ammonia water with a mass concentration of 28%. After stirring, let it stand at 30℃ for 24h. After filtration, wash the product with ethanol and water, dry it, place it in a muffle furnace, heat it to 550℃ at a heating rate of 5℃ / min, keep it at the temperature for 6h, and cool it to obtain monodisperse silica. Figures 1-3 The scanning electron microscope images show that the prepared silica has a uniform particle size, good dispersibility, and is not prone to agglomeration.

[0024] Example 2: (1) Add 90 mL of N,N-dimethylformamide, 10 mmol of polyethylene glycol 600 (about 6.0 g), 10 mmol of N-methyliminodiacetic acid, 10 mmol of N,N-dicyclohexylcarbodiimide, and 3.6 mmol of 4-dimethylaminopyridine to the reaction vessel, stir and react at 20 °C for 18 h, distill the solution under reduced pressure, wash the product with petroleum ether, and dry to obtain the polyethylene glycol precursor.

[0025] (2) Add 70 mL of N,N-dimethylformamide, 5 g of polyethylene glycol precursor and 0.51 g of 1-chlorohexane to a reaction vessel equipped with a reflux condenser, heat to 90 °C, stir and react for 36 h, distill the solution under reduced pressure, wash the product with petroleum ether, and dry to obtain polyethylene glycol cationic surfactant.

[0026] (3) Add 4L of ethanol, 5L of water, 7g of polyethylene glycol cationic surfactant, 22g of dodecylamine and 100g of tetraethyl orthosilicate to the reaction vessel. After stirring, add 26mL of ammonia water with a mass concentration of 22%. After stirring, let it stand at 20℃ for 36h. After filtration, wash the product with ethanol and water, dry it and place it in a muffle furnace. Heat it to 650℃ at a heating rate of 10℃ / min and keep it at the temperature for 4h. After cooling, monodisperse silica is obtained.

[0027] Example 3: (1) Add 90 mL of N,N-dimethylformamide, 10 mmol of polyethylene glycol 800 (about 8.0 g), 12 mmol of N-methyliminodiacetic acid, 11 mmol of N,N-dicyclohexylcarbodiimide, and 2.4 mmol of 4-dimethylaminopyridine to the reaction vessel, stir and react at 25 °C for 18 h, distill the solution under reduced pressure, wash the product with petroleum ether, and dry to obtain the polyethylene glycol precursor.

[0028] (2) Add 80 mL of N,N-dimethylformamide, 5 g of polyethylene glycol precursor and 0.67 g of 1-chloroethane to a reaction vessel equipped with a reflux condenser. Heat to 120 °C and stir for 18 h. Distill the solution under reduced pressure, wash the product with petroleum ether and dry to obtain a polyethylene glycol cationic surfactant.

[0029] (3) Add 2.5L of ethanol, 3L of water, 3g of polyethylene glycol cationic surfactant, 25g of hexadecylamine, and 100g of tetraethyl orthosilicate to the reaction vessel. After stirring, add 18mL of ammonia water with a mass concentration of 28%. After stirring, let it stand at 25℃ for 36h. After filtration, wash the product with ethanol and water, dry it, and place it in a muffle furnace. Heat it to 600℃ at a heating rate of 10℃ / min, keep it at the temperature for 4h, and cool it to obtain monodisperse silica.

[0030] Example 4: (1) Add 80 mL of N,N-dimethylformamide, 10 mmol of polyethylene glycol 1000 (about 10.0 g), 11 mmol of N-methyliminodiacetic acid, 11 mmol of N,N-dicyclohexylcarbodiimide, and 3 mmol of 4-dimethylaminopyridine to the reaction vessel, stir and react at 35 °C for 12 h, distill the solution under reduced pressure, wash the product with petroleum ether, and dry to obtain the polyethylene glycol precursor.

[0031] (2) Add 80 mL of N,N-dimethylformamide, 5 g of polyethylene glycol precursor and 0.8 g of 1-chlorobutane to a reaction vessel equipped with a reflux condenser. Heat to 90 °C and stir for 36 h. Distill the solution under reduced pressure, wash the product with petroleum ether and dry to obtain a polyethylene glycol cationic surfactant.

[0032] (3) Add 3L of ethanol, 4L of water, 4.2g of polyethylene glycol cationic surfactant, 17g of dodecylamine, and 100g of tetraethyl orthosilicate to the reaction vessel. After stirring, add 18mL of ammonia water with a mass concentration of 28%. After stirring, let it stand at 25℃ for 24h. After filtration, wash the product with ethanol and water, dry it, and place it in a muffle furnace. Heat it to 550℃ at a heating rate of 5℃ / min, keep it at the temperature for 6h, and cool it to obtain monodisperse silica.

[0033] Comparative Example 1 differs from Example 1 in that it does not contain a polyethylene glycol cationic surfactant.

[0034] (1) Add 3.5L of ethanol, 5L of water, 16g of dodecylamine and 100g of tetraethyl orthosilicate to the reaction vessel. After stirring, add 20mL of ammonia water with a mass concentration of 28%. After stirring, let it stand at 30℃ for 24h. After filtration, wash the product with ethanol and water, dry it and place it in a muffle furnace. Heat it to 550℃ at a heating rate of 5℃ / min and keep it at that temperature for 6h. After cooling, silicon dioxide is obtained.

[0035] Comparative Example 2 differs from Example 1 in that a polyethylene glycol precursor is used instead of a polyethylene glycol cationic surfactant.

[0036] (1) Add 3.5L ethanol, 5L water, 5.7g polyethylene glycol precursor, 16g dodecylamine and 100g tetraethyl orthosilicate to the reaction vessel. After stirring, add 20mL of ammonia water with a mass concentration of 28%. After stirring, let stand at 30℃ for 24h. After filtration, wash the product with ethanol and water, dry it and place it in a muffle furnace. Heat it to 550℃ at a heating rate of 5℃ / min and keep it at the temperature for 6h. After cooling, obtain monodisperse silica with adjustable particle size.

[0037] Comparative Example 3 differs from Example 1 in that hexadecyltrimethylammonium bromide is used instead of polyethylene glycol cationic surfactant.

[0038] (1) Add 3.5L ethanol, 5L water, 5.7g cetyltrimethylammonium bromide, 16g dodecylamine, and 100g tetraethyl orthosilicate to the reaction vessel. After stirring, add 20mL of ammonia water with a mass concentration of 28%. After stirring, let it stand at 30℃ for 24h. After filtration, wash the product with ethanol and water, dry it, and place it in a muffle furnace. Heat it to 550℃ at a heating rate of 5℃ / min and keep it at that temperature for 6h. After cooling, silicon dioxide is obtained.

[0039] The particle size of silica was measured using a laser particle size analyzer. The specific surface area of ​​silica was measured using a specific surface area and pore size analyzer via the N2 adsorption-desorption curve method.

[0040] Table 1. Particle size and specific surface area tests

[0041] Through testing, Examples 1-4 used a polyethylene glycol cationic surfactant, which contains polyethylene glycol molecular chain segments and can act as a structure directing agent, and also contains quaternary ammonium salt groups, as a cationic surfactant. In aqueous solution, it self-assembles to form nanoscale micelles, forming a micelle template, which induces the deposition of silica. The silica precursor is adsorbed and directionally deposited on the micelle template. Finally, after high-temperature calcination, silica particles with high specific surface area and high dispersibility are obtained. By controlling the molecular weight of polyethylene glycol and the chain length of the polyethylene glycol cationic surfactant, silica particles with different particle sizes are obtained.

[0042] Comparative Example 1 did not include a polyethylene glycol cationic surfactant, while Comparative Example 2 used a polyethylene glycol precursor that did not contain quaternary ammonium salt cations. Both examples produced silica particles with larger sizes and smaller specific surface areas. Comparative Example 3 used hexadecyltrimethylammonium bromide as a cationic surfactant. The silica produced in Comparative Example 3 also had significantly larger particle sizes and smaller specific surface areas than that in Example 1.

[0043] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for preparing monodisperse silica with adjustable particle size, characterized in that, The preparation process includes: (1) Add N,N-dimethylformamide, polyethylene glycol, N-methyliminodiacetic acid, N,N-dicyclohexylcarbodiimide and 4-dimethylaminopyridine to the reaction vessel, carry out the reaction, distill the solution under reduced pressure, wash the product, dry it, and obtain the polyethylene glycol precursor. (2) Add N,N-dimethylformamide, polyethylene glycol precursor and chloroalkanes to the reaction vessel, carry out the reaction, distill the solution under reduced pressure, wash the product, dry it, and obtain polyethylene glycol cationic surfactant. (3) Add ethanol, water, polyethylene glycol cationic surfactant, alkylamine and tetraethyl orthosilicate to the reaction vessel, stir and add ammonia dropwise, stir and let stand to age, filter and wash the product, dry and place it in a muffle furnace for calcination, cool and obtain monodisperse silica with adjustable particle size. The ratio of the polyethylene glycol cationic surfactant, alkylamine, tetraethyl orthosilicate, and ammonia is (3-7) g: (16-25) g: 100 g: (18-26) mL.

2. The preparation process of monodisperse silica with adjustable particle size according to claim 1, characterized in that, In (1), the ratio of polyethylene glycol, N-methyliminodiacetic acid, N,N-dicyclohexylcarbodiimide, and 4-dimethylaminopyridine is 1 mol: (1-1.2) mol: (1-1.1) mol: (0.24-0.36) mol, and the molecular weight of polyethylene glycol is 400-1000.

3. The preparation process of monodisperse silica with adjustable particle size according to claim 1, characterized in that, The reaction in (1) is carried out at 20-35℃ for 12-18h.

4. The preparation process of monodisperse silica with adjustable particle size according to claim 1, characterized in that, The ratio of polyethylene glycol precursor to chloroalkane in (2) is 100g: (7-16)g.

5. The preparation process of monodisperse silica with adjustable particle size according to claim 4, characterized in that, The chloroalkane has the structural formula Cl-C n H 2n+1 n is any integer from 2 to 6.

6. The preparation process of monodisperse silica with adjustable particle size according to claim 1, characterized in that, The reaction in (2) is carried out at 90-120℃ for 18-36 hours.

7. The preparation process of monodisperse silica with adjustable particle size according to claim 1, characterized in that, The mass concentration of ammonia in (3) is 22-28%.

8. The preparation process of monodisperse silica with adjustable particle size according to claim 7, characterized in that, The alkylamine has the structural formula NH2-C. a H2 a +1, where a is any integer from 12 to 16.

9. The preparation process of monodisperse silica with adjustable particle size according to claim 1, characterized in that, The aging process in (3) is carried out at 20-30℃ for 24-36 hours.

10. The preparation process of monodisperse silica with adjustable particle size according to claim 1, characterized in that, In step (3), the calcination is carried out at a heating rate of 5-10℃ / min, heating to 550-650℃ and holding for 4-6 hours.

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