A method for precise preparation and control of nano-SiO2 particle size

Abstract

This invention discloses a method for precisely controlling the particle size of nano-SiO2 particles. The method involves uniformly mixing distilled water and an alkane solution, adding basic amino acids, stirring until homogeneous, adding tetraethyl orthosilicate at 20–80°C, and refluxing to obtain a seed dispersion. The seed dispersion is then rotary evaporated to obtain a seed dispersion body. This seed dispersion body is dissolved in a mixture of anhydrous ethanol and water containing basic amino acids, and the mixture is heated to 40–100°C before adding tetraethyl orthosilicate and refluxing to obtain nano-SiO2 particles with a size of 10–165 nm. This invention utilizes basic amino acids as a basic catalyst, controls the reaction temperature to prepare nano-SiO2 particles as "seeds," and then uses a seed regeneration principle to perform "seed regrowth" to prepare 10–165 nm nano-silica particles with high monodispersity.

Description

Technical Field

[0001] This invention belongs to the field of nano-SiO2 particle preparation technology, specifically relating to a method for precisely controlling the particle size of nano-SiO2 particles. Background Technology

[0002] Nanoscale SiO2 particles are an important inorganic non-metallic material and an ideal building block for assembling functional nanostructures, playing a crucial role in fields such as rubber, photonic crystals, biomedicine, and cosmetics. SiO2 exhibits quantum size effects, small size effects, macroscopic quantum tunneling effects, and surface effects, resulting in unique mechanical, electrical, magnetic, optical, and thermal properties, offering broad application prospects in many fields, such as polymer materials, nanoglasses, photonic crystals, and drug carriers. The properties of SiO2 materials are closely related to their particle size and distribution; many optical, electrical, and magnetic properties can only be macroscopically manifested when the SiO2 particle size is suitable and the particle size distribution is relatively uniform. In foams, the particle size of silica particles also significantly affects foam stability.

[0003] Currently, the main methods for preparing nano-silica particles are: The three methods—method, microemulsion method, and precipitation method—each have their own advantages and disadvantages.

[0004] Microemulsion methods can produce nano-SiO2 particles with a particle size range of 20–100 nm, but there are many types of surfactants, and the selection of surfactants and co-surfactants largely depends on experience.

[0005] The precipitation method for preparing nano-SiO2 particles can control the particle size and produce nano-SiO2 particles with a minimum particle size of about 2 nm. It has the advantages of simple process and low cost, but its particle size distribution is relatively wide and it is easy to agglomerate.

[0006] The main limitation of this method lies in preparing particles with small diameters, with the smallest particle size reaching 15–20 nm, but exhibiting high polydispersity (greater than 20%). Therefore, achieving monodispersity better than 4%–5% for preparing nano-SiO2 particles with a diameter less than 100 nm using one-step synthesis or small seed regrowth is a significant challenge.

[0007] Despite numerous research reports on the preparation of nano-silica particles, the industrialization and commercialization of small-sized nano-silica particles are mainly limited by two bottlenecks: firstly, the lack of efficient and feasible industrial-scale preparation methods; and secondly, the stability of the nanoparticle-based foam dispersion system. The large specific surface area of ​​the foam system makes this dispersion system extremely unstable, prone to breakage and delamination, hindering its application in industries such as food and pharmaceuticals, and limiting its development to basic laboratory research. Therefore, there is an urgent need to develop a technology for precise control of the particle size of nano-SiO2 particles to meet the needs of these applications. Summary of the Invention

[0008] To overcome the problems in the prior art, the purpose of this invention is to provide a method for precisely controlling the particle size of nano-SiO2 particles. This method uses a regeneration method and alkaline amino acids as an alkaline catalyst to prepare highly monodisperse silica particles of 10-165 nm in an aqueous medium.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] A method for precisely controlling the particle size of nano-SiO2 particles includes the following steps:

[0011] 1) Mix distilled water and alkane solution evenly, then add basic amino acids and stir evenly. Add tetraethyl orthosilicate at 20-80℃ and reflux for 12-24 hours to obtain seed dispersion. Rotary evaporate the seed dispersion to obtain seed dispersion.

[0012] 2) Dissolve the seed dispersion in a mixture of anhydrous ethanol and water containing alkaline amino acids, then heat to 40-100℃ and add tetraethyl orthosilicate, reflux for 12-24 hours to obtain nano-SiO2 particles of 10-165nm.

[0013] Furthermore, the volume ratio of distilled water to alkane solution is 100–150:5–20.

[0014] Furthermore, the ratio of distilled water to alkaline amino acids is 100–150 mL: 0.1–0.6 g.

[0015] Furthermore, in step 1), the ratio of basic amino acids to tetraethyl orthosilicate is 0.1–0.6 g: 5–15 mL.

[0016] Furthermore, the basic amino acid is L-arginine.

[0017] Furthermore, the alkane solution is one of cyclohexane, pentane, and rapeseed oil.

[0018] Furthermore, the mass ratio of the basic amino acid in step 1) to the basic amino acid in step 2) is 0.1-0.6:0.2-1.5.

[0019] Furthermore, the volume ratio of tetraethyl orthosilicate in step 1) to tetraethyl orthosilicate in step 2) is 5-12:10-20.

[0020] Furthermore, the molar ratio of anhydrous ethanol to water is 1.2:1.

[0021] Furthermore, the concentration of seed dispersion in the mixture is 0.1–0.8 g / mL.

[0022] Compared with existing technologies, this invention uses a regrowth method and arginine as an alkaline catalyst to prepare highly monodisperse silica particles in an aqueous medium, which has the following advantages:

[0023] This invention utilizes the electrostatic interaction between basic amino acids and tetraethyl orthosilicate to prepare SiO2 particles of different sizes. The method is similar, but alkaline amino acids are used instead of ammonia as a catalyst. The advantages are that the prepared nano-silica particles are highly dispersed and small in size. Furthermore, the use of alkaline amino acids to assist in the preparation of nano-silica particles has been proven to be effective against [various challenges]. The process is compatible, allowing the particles to regenerate into larger particles while perfectly maintaining monodispersity. This invention first utilizes basic amino acids as a basic catalyst, controlling the reaction temperature to prepare nano-SiO2 particles as "seeds," and then leverages the seed regeneration principle to... This invention employs a "seed regrowth" method, controlling reaction parameters during the seed regeneration stage to prepare nano-silica particles of varying sizes. The nano-silica particles prepared in this invention have a particle size as low as 10 nm and exhibit high monodispersity, making them ideal for the formation of colloidal arrays and application as colloidal templates. Furthermore, the excellent monodispersity is maintained without the need for modification treatment with ammonia, surfactants, or silane coupling agents during the preparation process, thus reducing production costs. The catalyst used in the preparation process is a natural amino acid, free of any hazardous chemicals. Functional additives, such as fluorescent dyes, can also be introduced during the seed regrowth process, enabling its wide application in fields such as bioimaging and photonic crystals. Detailed Implementation

[0024] To facilitate understanding of the present invention, a more comprehensive description will be given below with reference to relevant examples. Preferred embodiments of the invention are shown in the examples. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention.

[0025] The present invention provides a method for precisely controlling the particle size of nano-SiO2 particles, comprising the following steps:

[0026] 1) Preparation process of nanoparticle seeds:

[0027] Step 1: Mix 100-150 mL of distilled water and 5-20 mL of alkane solution thoroughly. Add 0.1-0.6 g of basic amino acids at room temperature (25°C) and transfer the mixture to a 250 mL two-necked flask equipped with a mechanical stirrer and reflux condenser. Stir the mixture at 200-800 r / min until homogeneous. Then, add 5-15 mL of tetraethyl orthosilicate (TEOS) to the seed dispersion at 20-80°C and reflux for 12-24 h to obtain a light blue microemulsion, i.e., the seed dispersion. Set the temperature of the rotary evaporator to 60-100°C and the vacuum degree to 95 kPa, and rotary evaporate the seed dispersion for 1-6 h to obtain a white powder solid, i.e., 10 nm SiO2 particles, i.e., the seed dispersion.

[0028] Among them, the basic amino acid is L-arginine.

[0029] The alkane solution is one of cyclohexane, pentane, and rapeseed oil.

[0030] 2) Seed regrowth process:

[0031] Step 1: Transfer the seed dispersion to a 250 mL three-necked flask equipped with a mechanical stirrer and reflux condenser. Control the stirring speed at 300–1000 rpm, heat to 40–100 °C, and then add 210 mL of a mixed solution of anhydrous ethanol and water containing 0.2–1.5 g of basic amino acids, so that the concentration of the seed dispersion is 0.1–0.8 g / mL. Then transfer it to a 250 mL three-necked flask equipped with a mechanical stirrer and reflux condenser, and control the stirring speed at 300–1000 rpm.

[0032] In this invention, the particle size of nano-SiO2 particles is controlled by the content of the seed dispersion.

[0033] Step 2: Heat the solution to 40–100°C and add 10–20 mL of TEOS. Reflux the solution at this temperature for 12–24 h to obtain a blue-white microemulsion. Then, centrifuge the microemulsion three times with anhydrous ethanol at a speed of 5000–12000 r / min. Finally, dry the microemulsion in a constant temperature drying oven at 40–100°C for 6–18 h to obtain nano-SiO2 particles.

[0034] The molar ratio of anhydrous ethanol to water is 1.2:1.

[0035] Example 1

[0036] A method for precisely controlling the particle size of nano-SiO2 particles mainly includes the following steps:

[0037] 1) Preparation process of nanoparticle seeds:

[0038] Step 1: Mix 122 mL of distilled water and 9 mL of alkane solution evenly, add 0.182 g of basic amino acids at room temperature, transfer it to a 250 mL two-necked flask equipped with a mechanical stirrer and reflux condenser, and control the stirring speed at 300 r / min.

[0039] The alkane is cyclohexane.

[0040] Step 2: After controlling the temperature to 60℃, add 11mL of tetraethyl orthosilicate (TEOS), reflux for 20h to obtain a light blue microemulsion, i.e., seed dispersion. Set the temperature of the rotary evaporator to 80℃ and the vacuum degree to 95kPa, and rotary evaporate for 1h to obtain a white powder solid, i.e., seed dispersion, with a particle size of 10nm.

[0041] 2) Seed regrowth process:

[0042] Step 1: Dissolve the seed dispersion obtained in step 1) in 210 mL of a mixed solution of anhydrous ethanol and water containing 0.8 g of basic amino acids, so that the concentration of the seed dispersion is 0.8 g / mL. Then transfer it to a 250 mL three-necked flask equipped with a mechanical stirrer and a reflux condenser, and control the stirring speed at 300 r / min.

[0043] Step 2: Heat the solution to 60℃ and add 12mL of TEOS. Reflux the solution at this temperature for 20h to obtain a blue-white microemulsion. Then, centrifuge the microemulsion three times with anhydrous ethanol at a speed of 10000r / min. Finally, dry the microemulsion in a constant temperature drying oven at 65℃ for 12h to obtain nano-silica particles with increased particle size.

[0044] Example 2

[0045] A method for precisely controlling the particle size of nano-SiO2 particles mainly includes the following steps:

[0046] 1) Preparation process of nanoparticle seeds:

[0047] Step 1: Mix 122 mL of distilled water and 9 mL of alkane solution evenly, add 0.182 g of basic amino acids at room temperature, transfer it to a 250 mL two-necked flask equipped with a mechanical stirrer and reflux condenser, and control the stirring speed at 300 r / min.

[0048] The alkane is cyclohexane.

[0049] Step 2: After controlling the temperature to 60℃, add 11mL of tetraethyl orthosilicate (TEOS), reflux for 20h to obtain a light blue microemulsion, i.e., seed dispersion. Set the temperature of the rotary evaporator to 80℃ and the vacuum degree to 95kPa, and rotary evaporate for 1h to obtain a white powder solid, i.e., seed dispersion, with a particle size of 10nm.

[0050] 2) Seed regrowth process:

[0051] Step 1: Dissolve the seed dispersion obtained in step 1) in 210 mL of a mixed solution of anhydrous ethanol and water containing 0.8 g of basic amino acids, so that the concentration of the seed dispersion is 0.6 g / mL. Then transfer it to a 250 mL three-necked flask equipped with a mechanical stirrer and a reflux condenser, and control the stirring speed at 300 r / min.

[0052] Step 2: Heat the solution to 60℃ and add 12mL of TEOS. Reflux the solution at this temperature for 20h to obtain a blue-white microemulsion. Then, centrifuge the microemulsion three times with anhydrous ethanol at a speed of 10000r / min. Finally, dry the microemulsion in a constant temperature drying oven at 65℃ for 12h to obtain nano-silica particles with increased particle size.

[0053] Example 3

[0054] A method for precisely controlling the particle size of nano-SiO2 particles mainly includes the following steps:

[0055] 1) Preparation process of nanoparticle seeds:

[0056] Step 1: Mix 122 mL of distilled water and 9 mL of alkane solution evenly, add 0.182 g of basic amino acids at room temperature, transfer it to a 250 mL two-necked flask equipped with a mechanical stirrer and reflux condenser, and control the stirring speed at 300 r / min.

[0057] The alkane is cyclohexane.

[0058] Step 2: After controlling the temperature to 60℃, add 11 mL of tetraethyl orthosilicate (TEOS), reflux for 20 h to obtain a light blue microemulsion, i.e., seed dispersion. Set the rotary evaporator temperature to 80℃ and the vacuum degree to 95 kPa, and rotary evaporate for 1 h to obtain a white powder solid, i.e., seed dispersion, with a particle size of 10 nm.

[0059] 2) Seed regrowth process:

[0060] Step 1: Dissolve the seed dispersion obtained in step 1) in 210 mL of a mixed solution of anhydrous ethanol and water containing 0.8 g of basic amino acids to make the concentration of the seed dispersion 0.4 g / mL. Then transfer it to a 250 mL three-necked flask equipped with a mechanical stirrer and reflux condenser, and control the stirring speed at 300 r / min.

[0061] Step 2: Heat the solution to 60℃ and add 12mL of TEOS. Reflux the solution at this temperature for 20h to obtain a blue-white microemulsion. Then, centrifuge the microemulsion three times with anhydrous ethanol at a speed of 10000r / min. Finally, dry the microemulsion in a constant temperature drying oven at 65℃ for 12h to obtain nano-silica particles with increased particle size.

[0062] Example 4

[0063] A method for precisely controlling the particle size of nano-SiO2 particles mainly includes the following steps:

[0064] 1) Preparation process of nanoparticle seeds:

[0065] Step 1: Mix 122 mL of distilled water and 9 mL of alkane solution evenly, add 0.182 g of basic amino acids at room temperature, transfer it to a 250 mL two-necked flask equipped with a mechanical stirrer and reflux condenser, and control the stirring speed at 300 r / min.

[0066] The alkane is cyclohexane.

[0067] Step 2: After controlling the temperature to 60℃, add 11 mL of tetraethyl orthosilicate (TEOS), reflux for 20 h to obtain a light blue microemulsion, i.e., seed dispersion. Set the rotary evaporator temperature to 80℃ and the vacuum degree to 95 kPa, and rotary evaporate for 1 h to obtain a white powder solid, i.e., seed dispersion, with a particle size of 10 nm.

[0068] 2) Seed regrowth process:

[0069] Step 1: Dissolve the white powder solid obtained in step 1) in 210 mL of a mixed solution of anhydrous ethanol and water containing 0.8 g of basic amino acids to make the concentration of the seed dispersion 0.2 g / mL. Then transfer it to a 250 mL three-necked flask equipped with a mechanical stirrer and reflux condenser, and control the stirring speed at 300 r / min.

[0070] Step 2: Heat the solution to 60℃ and add 12mL of TEOS. Reflux the solution at this temperature for 20h to obtain a blue-white microemulsion. Then, centrifuge the microemulsion three times with anhydrous ethanol at a speed of 10000r / min. Finally, dry the microemulsion in a constant temperature drying oven at 65℃ for 12h to obtain nano-silica particles with increased particle size.

[0071] Example 5

[0072] A method for precisely controlling the particle size of nano-SiO2 particles mainly includes the following steps:

[0073] 1) Preparation process of nanoparticle seeds:

[0074] Step 1: Mix 122 mL of distilled water and 9 mL of alkane solution evenly, add 0.182 g of basic amino acids at room temperature, transfer it to a 250 mL two-necked flask equipped with a mechanical stirrer and reflux condenser, and control the stirring speed at 300 r / min.

[0075] The alkane is cyclohexane.

[0076] Step 2: After controlling the temperature to 60℃, add 11 mL of tetraethyl orthosilicate (TEOS), reflux for 20 h to obtain a light blue microemulsion, i.e., seed dispersion. Set the rotary evaporator temperature to 80℃ and the vacuum degree to 95 kPa, and rotary evaporate for 1 h to obtain a white powder solid, i.e., seed dispersion, with a particle size of 10 nm.

[0077] 2) Seed regrowth process:

[0078] Step 1: Dissolve the white powder solid obtained in step 1) in 210 mL of a mixed solution of anhydrous ethanol and water containing 0.8 g of basic amino acids to make the concentration of the seed dispersion 0.1 g / mL. Then transfer it to a 250 mL three-necked flask equipped with a mechanical stirrer and reflux condenser, and control the stirring speed at 300 r / min.

[0079] Step 2: Heat the solution to 60℃ and add 12mL of TEOS. Reflux the solution at this temperature for 20h to obtain a blue-white microemulsion. Then, centrifuge the microemulsion three times with anhydrous ethanol at a speed of 10000r / min. Finally, dry the microemulsion in a constant temperature drying oven at 65℃ for 12h to obtain nano-silica particles with increased particle size.

[0080] Transmission electron microscopy (TEM) tests were performed on Examples 1-5.

[0081] The sample was diluted with ethanol solution to a certain factor (100-120 times) and sonicated for 10 min. Finally, the solution was transferred to a copper grid with a pipette and the particle size of nano-SiO2 was observed using transmission electron microscopy.

[0082] Table 1 shows the particle size results of nano-silica synthesized from seed dispersions of different concentrations prepared in Examples 1-5.

[0083] Table 1. Particle size of nano-silica synthesized from seed dispersions of different concentrations. As shown in Table 1, the particle size of nano-silica particles increases with the decrease of seed dispersion content. The nano-silica particles prepared from seed dispersions of 0.8 g / mL, 0.6 g / mL, 0.4 g / mL, 0.2 g / mL, and 0.1 g / mL have particle sizes of approximately 25 nm, 45 nm, 80 nm, 120 nm, and 165 nm, respectively, and exhibit good monodispersity.

[0084] Example 6

[0085] A method for precisely controlling the particle size of nano-SiO2 particles mainly includes the following steps:

[0086] 1) Preparation process of nanoparticle seeds:

[0087] Step 1: Mix 100 mL of distilled water and 5 mL of alkane solution evenly, add 0.1 g of basic amino acids at room temperature, transfer the mixture to a 250 mL two-necked flask equipped with a mechanical stirrer and reflux condenser, and control the stirring speed at 200 r / min.

[0088] The alkane is cyclohexane.

[0089] Step 2: After controlling the temperature to 40℃, add 13mL of tetraethyl orthosilicate (TEOS), reflux for 24h to obtain a light blue microemulsion, i.e., seed dispersion. Set the temperature of the rotary evaporator to 60℃ and the vacuum degree to 95kPa, and rotary evaporate for 1h to obtain a white powder solid, i.e., seed dispersion.

[0090] 2) Seed regrowth process:

[0091] Step 1: Dissolve the seed dispersion obtained in step 1) in a mixed solution of anhydrous ethanol and water containing 0.2g of basic amino acids (molar ratio of anhydrous ethanol to water is 1.2:1) to make the concentration of the seed dispersion 0.4g / mL. Then transfer it to a 250mL three-necked flask equipped with a mechanical stirrer and reflux condenser, and control the stirring speed at 400r / min.

[0092] Step 2: Heat the solution to 50℃ and add 12mL of TEOS. Reflux the solution at this temperature for 18h to obtain a blue-white microemulsion. Then, centrifuge the microemulsion three times with anhydrous ethanol at a speed of 9000r / min. Finally, dry the microemulsion in a constant temperature drying oven at 40℃ for 12h to obtain nano-silica particles with a particle size of 35nm.

[0093] Example 7

[0094] A method for precisely controlling the particle size of nano-SiO2 particles mainly includes the following steps:

[0095] 1) Preparation process of nanoparticle seeds:

[0096] Step 1: Mix 150 mL of distilled water and 10 mL of alkane solution evenly, add 0.15 g of basic amino acids at room temperature, transfer it to a 250 mL two-necked flask equipped with a mechanical stirrer and reflux condenser, and control the stirring speed at 400 r / min.

[0097] The alkane is cyclohexane.

[0098] Step 2: After controlling the temperature to 50℃, add 10mL of tetraethyl orthosilicate (TEOS), reflux for 22h to obtain a light blue microemulsion, i.e., seed dispersion. Set the temperature of the rotary evaporator to 100℃ and the vacuum degree to 95kPa, and rotary evaporate for 1h to obtain a white powder solid, i.e., seed dispersion.

[0099] 2) Seed regrowth process:

[0100] Step 1: Dissolve the white powder solid obtained in step 1) in a mixed solution of anhydrous ethanol and water containing 0.4 g of basic amino acids (molar ratio of anhydrous ethanol to water is 1.2:1) to make the concentration of the seed dispersion 0.4 g / mL. Then transfer it to a 250 mL three-necked flask equipped with a mechanical stirrer and reflux condenser, and control the stirring speed at 500 r / min.

[0101] Step 2: Heat the solution to 60℃ and add 12mL of TEOS. Reflux the solution at this temperature for 20h to obtain a blue-white microemulsion. Then, centrifuge the microemulsion three times with anhydrous ethanol at a speed of 11000r / min. Finally, dry the microemulsion in a constant temperature drying oven at 50℃ for 12h to obtain nano-silica particles with a particle size of 56nm.

[0102] Example 8

[0103] A method for precisely controlling the particle size of nano-SiO2 particles mainly includes the following steps:

[0104] 1) Preparation process of nanoparticle seeds:

[0105] Step 1: Mix 130 mL of distilled water and 8 mL of alkane solution evenly, add 0.15 g of basic amino acids at room temperature, transfer the mixture to a 250 mL two-necked flask equipped with a mechanical stirrer and reflux condenser, and control the stirring speed at 500 r / min.

[0106] The alkane is cyclohexane.

[0107] Step 2: After controlling the temperature to 55℃, add 15mL of tetraethyl orthosilicate (TEOS), reflux for 23h to obtain a light blue microemulsion, i.e., seed dispersion. Set the temperature of the rotary evaporator to 70℃ and the vacuum degree to 95kPa, and rotary evaporate for 1h to obtain a white powder solid, i.e., seed dispersion.

[0108] 2) Seed regrowth process:

[0109] Step 1: Dissolve the seed dispersion obtained in step 1) in a mixed solution of anhydrous ethanol and water containing 0.4 g of basic amino acids (molar ratio of anhydrous ethanol to water is 1.2:1) to make the concentration of the seed dispersion 0.4 g / mL. Then transfer it to a 250 mL three-necked flask equipped with a mechanical stirrer and reflux condenser, and control the stirring speed at 300 r / min.

[0110] Step 2: Heat the solution to 60℃ and add 12mL of TEOS. Reflux the solution at this temperature for 24h to obtain a blue-white microemulsion. Then, centrifuge the microemulsion three times with anhydrous ethanol at a speed of 8000r / min. Finally, dry the microemulsion in a constant temperature drying oven at 70℃ for 12h to obtain nano-silica particles with a particle size of 70nm.

[0111] Example 9

[0112] A method for precisely controlling the particle size of nano-SiO2 particles mainly includes the following steps:

[0113] 1) Preparation process of nanoparticle seeds:

[0114] Step 1: Mix 150 mL of distilled water and 20 mL of alkane solution evenly, add 0.6 g of basic amino acids at room temperature, transfer the mixture to a 250 mL two-necked flask equipped with a mechanical stirrer and reflux condenser, and control the stirring speed at 800 r / min.

[0115] The alkane is cyclohexane.

[0116] Step 2: After controlling the temperature to 20℃, add 15mL of tetraethyl orthosilicate (TEOS), reflux for 12h to obtain a light blue microemulsion, i.e., seed dispersion. Set the temperature of the rotary evaporator to 100℃ and the vacuum degree to 95kPa, and rotary evaporate for 1h to obtain a white powder solid, i.e., seed dispersion.

[0117] 2) Seed regrowth process:

[0118] Step 1: Dissolve the seed dispersion obtained in step 1) in a mixed solution of anhydrous ethanol and water containing 0.2g of basic amino acids (molar ratio of anhydrous ethanol to water is 1.2:1) to make the concentration of the seed dispersion 0.1g / mL. Then transfer it to a 250mL three-necked flask equipped with a mechanical stirrer and reflux condenser, and control the stirring speed at 1000r / min.

[0119] Step 2: Heat to 100℃ and add 10mL of TEOS to the solution. Reflux at this temperature for 24h to obtain a blue-white microemulsion. Then, centrifuge and wash three times with anhydrous ethanol at a speed of 5000r / min. Finally, dry in a constant temperature drying oven at 100℃ for 6h to obtain nano-silica particles with increased particle size.

[0120] Example 10

[0121] A method for precisely controlling the particle size of nano-SiO2 particles mainly includes the following steps:

[0122] 1) Preparation process of nanoparticle seeds:

[0123] Step 1: Mix 120 mL of distilled water and 15 mL of alkane solution evenly, add 0.4 g of basic amino acids at room temperature, transfer the mixture to a 250 mL two-necked flask equipped with a mechanical stirrer and reflux condenser, and control the stirring speed at 600 r / min.

[0124] The alkane is cyclohexane.

[0125] Step 2: After controlling the temperature to 80℃, add 5mL of tetraethyl orthosilicate (TEOS), reflux for 24h to obtain a light blue microemulsion, i.e., seed dispersion. Set the temperature of the rotary evaporator to 60℃ and the vacuum degree to 95kPa, and rotary evaporate for 6h to obtain a white powder solid, i.e., seed dispersion.

[0126] 2) Seed regrowth process:

[0127] Step 1: Dissolve the seed dispersion obtained in step 1) in a mixed solution of anhydrous ethanol and water containing 1.5g of basic amino acids (molar ratio of anhydrous ethanol to water is 1.2:1) to make the concentration of the seed dispersion 0.8g / mL. Then transfer it to a 250mL three-necked flask equipped with a mechanical stirrer and reflux condenser, and control the stirring speed at 700r / min.

[0128] Step 2: Heat the solution to 40℃ and add 20mL of TEOS. Reflux the solution at this temperature for 12 hours to obtain a blue-white microemulsion. Then, centrifuge the microemulsion three times with anhydrous ethanol at a speed of 12000r / min. Finally, dry the microemulsion in a constant temperature drying oven at 40℃ for 18 hours to obtain nano-silica particles with increased particle size.

[0129] This invention first utilizes basic amino acids as a basic catalyst to prepare nano-SiO2 particles as "seeds" by controlling the reaction temperature, and then uses the seed regeneration principle to... This invention employs a "seed regrowth" method, controlling reaction parameters during the seed regeneration stage, such as reaction time, seed dispersion content, catalyst content, and the molar ratio of anhydrous ethanol / water, to prepare nano-silica particles of varying sizes. The nano-silica particles prepared by this invention have a particle size as low as 10 nm and exhibit excellent monodispersity, making them highly suitable for the formation of colloidal arrays and application as colloidal templates. Furthermore, the excellent monodispersity is maintained without the need for modification treatment with ammonia, surfactants, or silane coupling agents during the preparation process, thus reducing production costs. The catalyst used in the preparation process is a natural amino acid, free of any hazardous chemicals. Functional additives, such as fluorescent dyes, can also be introduced during the seed regeneration process, enabling its wide application in fields such as bioimaging and photonic crystals.

[0130] The above description is only of the preferred embodiment of the present invention and should not be construed as limiting the scope of the claims. The present invention is not limited to the above embodiments, and variations in its specific structure are permitted. All variations made within the scope of the independent claims of the present invention are also within the scope of protection of the present invention.

[0131] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

Claims

1. A method for precisely controlling the particle size of nano-SiO2 particles, characterized in that, The method comprises the following steps: 1) mixing distilled water and an alkane solution uniformly, then adding a basic amino acid, stirring uniformly, adding tetraethyl orthosilicate at 20-80 ℃, and condensing and refluxing for 12-24 h to obtain a seed dispersion liquid, and rotary evaporating the seed dispersion liquid to obtain a seed dispersion body; wherein the volume ratio of the distilled water to the alkane solution is 100-150:5-20, the ratio of the amount of the distilled water to the amount of the basic amino acid is 100-150 mL:0.1-0.6 g, and the ratio of the amount of the basic amino acid to the amount of the tetraethyl orthosilicate is 0.1-0.6 g:5-15 mL; 2) dissolving the seed dispersion body in a mixture of anhydrous ethanol and water containing a basic amino acid, the concentration of the seed dispersion body in the mixture being 0.1-0.8 g / mL, then heating to 40-100 ℃, adding tetraethyl orthosilicate, and condensing and refluxing for 12-24 h to obtain nano-SiO2 particles of 10-165 nm.

2. The method for precisely controlling the particle size of nano-SiO2 particles according to claim 1, wherein, The basic amino acid is L-arginine. 3.The method of claim 1, wherein the method is characterized by, The alkane solution is cyclohexane or pentane. 4.The method of claim 1, wherein the method is characterized by, The mass ratio of the basic amino acid in step 1) to the basic amino acid in step 2) is 0.1-0.6:0.2-1.

5. 5.The method of claim 1, wherein the method is characterized by, The volume ratio of the tetraethyl orthosilicate in step 1) to the tetraethyl orthosilicate in step 2) is 5-12:10-20. 6.The method for realizing precise control of the particle size of nano-SiO 2 particles according to claim 1, characterized in that, The molar ratio of the anhydrous ethanol to the water is 1.2:1.

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