A method for preparing a nanosilica dispersion

Abstract

The application relates to the field of nanometer silicon dioxide, and particularly relates to a preparation method of a nanometer silicon dioxide dispersion liquid, the preparation steps being as follows: modified polyethylene glycol methacrylate is added into a mixed solvent of ethanol and deionized water, the temperature is increased to 30-50 DEG C, stirring is carried out for 15-25 min, tetraethyl orthosilicate is added, and stirring is carried out for 8-12 min; in the application, a dispersion liquid with a specific block structure is synchronously introduced in a process of forming a silicon dioxide sol, and a reaction gradient is accurately controlled, one-step cooperation of particle growth and surface modification is realized, compared with the prior art, the dispersion liquid obtained by the method has the characteristics of low viscosity under super-high solid content, permanent stability of spontaneous redispersion after drying, and pH response intelligent release function, meanwhile, a closed-loop solvent system is adopted in a process, energy consumption is reduced, and the method has wide application prospects in the fields of diaphragm coating and optical antireflection thin film.

Description

Technical Field

[0001] This invention relates to the field of nano-silica, and more particularly to a method for preparing a nano-silica dispersion. Background Technology

[0002] Nano silica dispersion is a semi-transparent liquid material with nano-sized silica particles as its core component. It is a functional additive that imparts anti-agglomeration ability to nano silica particles through chemical modification or physical coating. It is mainly used in coatings, refractory materials, textile industry and other fields.

[0003] In existing technologies, the small particle size and high surface hydroxyl density of nano-silica dispersions make it easy for hydrogen bonds to form between particles, leading to agglomeration. Furthermore, traditional processes require drying into powder, and during dehydration, the silanol groups of adjacent particles undergo irreversible condensation reactions, forming strong Si-O-Si covalent bonds, resulting in hard agglomerates. These hard agglomerates are difficult to redisperse using conventional mechanical forces. Simultaneously, as the solid content increases, the distance between particles decreases, significantly enhancing van der Waals attraction and hydrogen bonding, causing a sharp increase in the viscosity of the dispersion system. This severely affects its processing performance and leads to irreversible hardening during drying. Moreover, the viscosity increases dramatically at high solid content, limiting its application range. In addition, conventional dispersions primarily address dispersion stability issues and lack intelligent response capabilities to environmental stimuli, restricting their application in high-end fields such as controlled drug release.

[0004] Therefore, based on the relevant technologies mentioned above, there is an urgent need to develop a method for preparing nano-silica dispersions. Summary of the Invention

[0005] In view of this, the purpose of this invention is to provide a method for preparing nano-silica dispersions to solve the problems of agglomeration, high viscosity due to high solid content, and limited functionality in the prior art.

[0006] To achieve the above objectives, the present invention provides a method for preparing a nano-silica dispersion.

[0007] A method for preparing a nano-silica dispersion, comprising the following steps:

[0008] Step S1: Add modified polyethylene glycol methacrylate to a mixed solvent of ethanol and deionized water, heat to 30-50℃, stir for 15-25 min, add tetraethyl orthosilicate, stir for 8-12 min, add 0.1 mol / L HCl solution, adjust pH to 1.8-2.2, react for 1-3 h, the reaction is complete, and a mixed solution is obtained;

[0009] Step S2: Add the mixed solution to the flask, add 0.1 mol / L ammonia water, adjust the pH to 8.8-9.2, heat to 55-65℃, add the mixed solution of tetraethyl orthosilicate and modified polyethylene glycol methacrylate and ethanol, stir the reaction for 5-7 hours at a speed of 350-450 rpm, and the reaction is complete to obtain a sol.

[0010] Step S3: Add the sol to the flask, heat to 50-70℃, react for 10-14 hours. Once the reaction is complete, replace the solvent with deionized water using an ultrafiltration device, concentrate under reduced pressure, and obtain a nano-silica dispersion.

[0011] Tetraethyl orthosilicate is fully hydrolyzed into active silanol groups using HCl solution. Then, in an alkaline environment created by ammonia, tetraethyl orthosilicate and modified polyethylene glycol methacrylate are added dropwise simultaneously. By precisely controlling the reaction conditions, the active groups in the dispersion molecules undergo a condensation reaction with the Si-OH groups on the surface of the newly generated silica particles to form covalent bonds Si-O-Si. This achieves in-situ synchronization of particle growth and surface modification. At the same time, the alkaline environment and suitable temperature are conducive to the formation of a sol with uniform particle size.

[0012] The dispersion is permanently anchored on the surface of silica particles through covalent Si-O-Si bonds. During the drying process, the steric hindrance layer formed by the long polyethylene glycol chains in its molecules can effectively physically isolate adjacent particles, thereby preventing condensation reactions between silanol groups on the particle surface and avoiding hard agglomeration. Therefore, when the dried powder comes into contact with water, the polyethylene glycol chains can quickly hydrate and expand, allowing the particles to redisperse and achieve permanent stability.

[0013] Meanwhile, the long ethylene glycol chains anchored on the particle surface fully extend in water, forming a thick hydration layer and steric hindrance, which can significantly weaken the van der Waals attraction between particles. Therefore, even with high particle concentrations, the system can maintain low viscosity and significantly improve processing performance.

[0014] Preferably, the volume ratio of ethanol to deionized water in step S1 is 4:1.

[0015] Preferably, the mass ratio of modified polyethylene glycol methacrylate to tetraethyl orthosilicate in step S1 is 1:4.6-4.7.

[0016] Preferably, the mass ratio of the mixed solution, tetraethyl orthosilicate and modified polyethylene glycol methacrylate in step S2 is 1:0.32-0.33:0.008-0.01.

[0017] Preferably, the mass ratio of modified polyethylene glycol methacrylate to ethanol in step S2 is 1:17-19.

[0018] Preferably, the preparation steps of the modified polyethylene glycol methacrylate are as follows:

[0019] Under a nitrogen atmosphere, dimethylaminoethyl methacrylate, sodium styrene sulfonate, and polyethylene glycol methacrylate were added to anhydrous ethanol solvent, stirred and mixed, and the initiator azobisisobutyronitrile was added. The mixture was heated to 65-75℃ and reacted for 22-26 hours. The temperature was then lowered to 5-10℃, hydroquinone was added, and the mixture was allowed to stand to precipitate. The precipitate was filtered, washed, and dried to obtain modified polyethylene glycol methacrylate.

[0020] The modified polyethylene glycol methacrylate contains a zwitterionic block copolymer of dimethylaminoethyl methacrylate and sodium styrene sulfonate. In a neutral environment, the tertiary amine group is partially protonated, forming an inner salt structure with the sulfonate group, which can provide charge stability. At the same time, this structure can effectively load a truly charged drug through electrostatic interaction. In a slightly acidic environment, the degree of protonation of the tertiary amine group increases, resulting in an increase in the net positive charge density on the particle surface, thereby generating electrostatic repulsion. It then binds to the positively charged drug, initiating molecular isomerization. In addition, the charge balance with the sulfonate group is also broken. Through the synergistic effect of the two, the drug can be rapidly desorbed and released, thereby achieving intelligent response.

[0021] Preferably, the mass ratio of dimethylaminoethyl methacrylate, sodium styrene sulfonate, polyethylene glycol methacrylate, initiator azobisisobutyronitrile, and hydroquinone is 1:1.25-1.35:4.9-5.1:0.008-0.012:0.0008-0.0012.

[0022] Preferably, the hydroquinone is a polymerization inhibitor, and the molecular weight of polyethylene glycol methacrylate is 500.

[0023] The beneficial effects of this invention are:

[0024] This invention provides a method for preparing a nano-silica dispersion. By simultaneously introducing a dispersion with a specific block structure during the formation of silica sol and precisely controlling the reaction gradient, a one-step synergistic process of particle growth and surface modification is achieved. Compared with the prior art, the dispersion obtained by this method has the characteristics of low viscosity under ultra-high solid content, permanent stability that can spontaneously redisperse after drying, and intelligent release function in response to pH. At the same time, the process adopts a closed-loop solvent system to reduce energy consumption. It has broad application prospects in the fields of membrane coating and optical antireflection film. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments.

[0026] Example 1: The preparation steps of a modified polyethylene glycol methacrylate are as follows:

[0027] Under a nitrogen atmosphere, 100g of dimethylaminoethyl methacrylate, 125g of sodium styrene sulfonate, and 490g of polyethylene glycol methacrylate were added to 1000mL of anhydrous ethanol solvent and stirred. 0.8g of azobisisobutyronitrile (AIBN) initiator was added, the mixture was heated to 65℃ and reacted for 26h. The temperature was then lowered to 5℃, and 0.08g of hydroquinone was added. The mixture was allowed to stand to precipitate, filtered, washed, and dried to obtain modified polyethylene glycol methacrylate.

[0028] Example 2: The preparation steps of a modified polyethylene glycol methacrylate are as follows:

[0029] Under a nitrogen atmosphere, 100g of dimethylaminoethyl methacrylate, 130g of sodium styrene sulfonate, and 500g of polyethylene glycol methacrylate were added to 1000mL of anhydrous ethanol solvent and stirred. 1g of the initiator azobisisobutyronitrile was added, the temperature was raised to 70℃, and the reaction was carried out for 24h. The temperature was lowered to 8℃, 0.1g of hydroquinone was added, and the mixture was allowed to stand to precipitate. The mixture was filtered, washed, and dried to obtain modified polyethylene glycol methacrylate.

[0030] Example 3: The preparation steps of a modified polyethylene glycol methacrylate are as follows:

[0031] Under a nitrogen atmosphere, 100g of dimethylaminoethyl methacrylate, 135g of sodium styrene sulfonate, and 510g of polyethylene glycol methacrylate were added to 1000mL of anhydrous ethanol solvent and stirred. 1.2g of azobisisobutyronitrile (AIBN) initiator was added, the mixture was heated to 75℃, and reacted for 22h. The temperature was then lowered to 10℃, and 0.12g of hydroquinone was added. The mixture was allowed to stand to precipitate, filtered, washed, and dried to obtain modified polyethylene glycol methacrylate.

[0032] Example 4: A method for preparing a nano-silica dispersion:

[0033] S1: Add 100g of modified polyethylene glycol methacrylate to a mixed solvent of 400mL ethanol and 100mL deionized water, heat to 30℃, stir for 25min, add 460g of tetraethyl orthosilicate, stir for 8min, add 0.1mol / L HCl solution, adjust the pH to 1.8-2.2, react for 3h, the reaction is complete, and a mixed solution is obtained;

[0034] S2: Add 100g of the mixed solution to a flask, add 0.1mol / L ammonia water, adjust the pH to 8.8-9.2, heat to 55℃, add 32g of tetraethyl orthosilicate and 0.8g of modified polyethylene glycol methacrylate and 13.6g of ethanol mixed solution, stir the reaction for 7h at 350rpm, the reaction is complete, and a sol is obtained;

[0035] S3: Add 100g of sol to a flask, heat to 50℃, react for 14h, and when the reaction is complete, replace the solvent with deionized water using an ultrafiltration device, concentrate under reduced pressure, and obtain a nano-silica dispersion.

[0036] Example 5: A method for preparing a nano-silica dispersion:

[0037] S1: Add 100g of modified polyethylene glycol methacrylate to a mixed solvent of 400mL ethanol and 100mL deionized water, heat to 40℃, stir for 20min, add 465g of tetraethyl orthosilicate, stir for 10min, add 0.1mol / L HCl solution, adjust pH to 1.8-2.2, react for 2h, the reaction is complete, and a mixed solution is obtained;

[0038] S2: Add 100g of the mixed solution to a flask, add 0.1mol / L ammonia water, adjust the pH to 8.8-9.2, heat to 60℃, add 32.5g of tetraethyl orthosilicate and 0.9g of modified polyethylene glycol methacrylate and 16.2g of ethanol mixed solution, stir the reaction for 6h at 400rpm, and the reaction is complete to obtain sol;

[0039] S3: Add 100g of sol to a flask, heat to 60℃, react for 12h, and when the reaction is complete, replace the solvent with deionized water using an ultrafiltration device, concentrate under reduced pressure, and obtain a nano silica dispersion.

[0040] Example 6: A method for preparing a nano-silica dispersion:

[0041] S1: Add 100g of modified polyethylene glycol methacrylate to a mixed solvent of 400mL ethanol and 100mL deionized water, heat to 50℃, stir for 15min, add 33g of tetraethyl orthosilicate, stir for 8min, add 0.1mol / L HCl solution, adjust the pH to 1.8-2.2, react for 3h, the reaction is complete, and a mixed solution is obtained;

[0042] S2: Add 100g of the mixed solution to a flask, add 0.1mol / L ammonia water, adjust the pH to 8.8-9.2, heat to 65℃, add 33g of tetraethyl orthosilicate and 1g of modified polyethylene glycol methacrylate and 19g of ethanol mixed solution, stir the reaction for 5h at 450rpm, the reaction is complete, and a sol is obtained;

[0043] S3: Add 100g of sol to a flask, heat to 70℃, react for 10h, and when the reaction is complete, replace the solvent with deionized water using an ultrafiltration device, concentrate under reduced pressure, and obtain a nano silica dispersion.

[0044] Comparative Example 1:

[0045] Compared with Example 4, this comparative example omits the S2 preparation step in the preparation method of a nano-silica dispersion, and directly performs physical mixing. The remaining steps and parameters are the same, and will not be repeated in this comparative example. The final result is a nano-silica dispersion.

[0046] Comparative Example 2:

[0047] Compared with Example 4, this comparative example only replaces "modified polyethylene glycol methacrylate" with "a mixture of dimethylaminoethyl methacrylate, sodium styrene sulfonate and polyethylene glycol methacrylate". All other steps and parameters are the same, and will not be repeated in this comparative example. The final product is a nano silica dispersion.

[0048] Comparative Example 3:

[0049] Compared with Example 4, this comparative example only replaces "modified polyethylene glycol methacrylate" with "polyethylene glycol methacrylate". All other steps and parameters are the same, and will not be repeated in this comparative example. The final product is a nano silica dispersion.

[0050] Comparative Example 4:

[0051] Compared with Example 4, this comparative example only replaces the reaction temperature "55℃" in S2 with "70℃". All other steps and parameters are the same, and will not be repeated here. The final result is a nano-silica dispersion.

[0052] Comparative Example 5:

[0053] Compared with Example 4, this comparative example only replaces "Mn=500" of polyethylene glycol methacrylate with "Mn=350". All other steps and parameters are the same, and will not be repeated here. The final result is a nano silica dispersion.

[0054] Performance testing:

[0055] Particle size and distribution

[0056] The Malvern nanoparticle size analyzer was used in accordance with the ISO 22412-2017 testing standard.

[0057] 1. Take the nano-silica dispersions of Examples 4-6 and Comparative Examples 1-5 respectively, dilute them to 0.1wt%, heat them to 25℃, and equilibrate for 10min;

[0058] 2. The particle size was measured using a Malvern nanoparticle size analyzer at a detection angle of 173°. The test was run three times and the average value was taken. The particle size and polydispersity index (PDI) value were recorded.

[0059] Storage stability:

[0060] The Malvern nanoparticle size analyzer was used in accordance with the GB / T 6753.3-1986 testing standard.

[0061] 1. Take 50 mL of each of the nano silica dispersions from Examples 4-6 and Comparative Examples 1-5, heat to 25°C, equilibrate for 10 min, seal in a transparent glass bottle, and let stand in the dark for 6 months.

[0062] 2. Take 1.0 mL of sample, centrifuge for 10 min at 10000 rpm, and calculate the sedimentation rate. ;

[0063] 3. Following the same testing steps as described above for "Particle Size and Distribution", after 6 months of testing, measure the particle size (6) and polydispersity index (PDI) (6) value.

[0064] Table 1

[0065]

[0066] Dry redispersibility

[0067] 1. Take the nano-silica dispersions from Examples 4-6 and Comparative Examples 1-5, freeze-dry them, take 10.0 g of each dispersion, add 10 mL of deionized water, heat to 25°C, rotate at 500 rpm, and record the time T required for the solution to become uniformly translucent. 自 (s);

[0068] 2. If spontaneous dispersion is not complete within 300 seconds, use ultrasonic treatment at 200W, sampling and measuring particle size every 30 seconds. Stop ultrasonication when the particle size recovers to ±5% of the initial value, and record the ultrasonic time T. 超 (min);

[0069] 3. Energy consumption calculation: Cumulative energy consumption value = ultrasonic power (W) × ultrasonic time (min).

[0070] Table 2

[0071]

[0072] pH-responsive release:

[0073] The RC806D intelligent dissolution apparatus was used in accordance with the test standards for dissolution and release determination in Part IV of the Chinese Pharmacopoeia.

[0074] 1. Take the nano-silica dispersions of Examples 4-6 and Comparative Examples 1-5, freeze-dry them, take 100.0 mg of each dispersion, add 10 mL of phosphate buffer (pH=7.4), vortex to mix, add 10 mg of doxorubicin, heat to 37°C, shake for 24 h, filter, centrifuge, wash, and determine the drug loading rate (DL%): ;

[0075] 2. Place the drug-loaded dispersion in the dialysis bag at the bottom of the dissolution vessel, rotate at 50 rpm, and maintain a temperature of 37℃±0.5℃. Take 1 mL samples at regular intervals: 0.5, 1, 2, 3, 4, and 6 hours.

[0076] 3. Cumulative release rate;

[0077]

[0078] Table 3

[0079]

[0080] Data Analysis:

[0081] As can be seen from Tables 1-3, the nano-silica dispersion prepared by the present invention has better stability, redispersibility and intelligent responsiveness.

[0082] In contrast, Comparative Example 1, due to direct physical mixing, resulted in a high precipitation rate of 52.3%, required strong ultrasound for redispersibility, and had a drug loading rate of only 9.5%. This was because it lacked crucial simultaneous in-situ modification, and the dispersion failed to form an effective anchoring effect through covalent bonds. The physically adsorbed dispersion detached from the SiO2 surface during the drying and concentration process, causing the exposed silanol groups to undergo a condensation reaction during dehydration, generating covalently linked hard aggregates. At the same time, the covalent bond network formed a mechanical lock, which could only be broken by ultrasonic shearing force. In addition, Example 4 simultaneously completed copolymer grafting during particle growth, allowing the dispersion to be permanently anchored to the surface through covalent bonds. This physically isolated the particles through the steric hindrance layer (polyethylene glycol chain), preventing the condensation reaction. Simultaneously, it spontaneously redispersed upon the addition of water, without the need for external force.

[0083] Comparative Example 2, by replacing modified polyethylene glycol methacrylate with a mixture of dimethylaminoethyl methacrylate, sodium styrene sulfonate, and polyethylene glycol methacrylate, resulted in increased particle size, redispersion energy consumption of 1600 W·min, and a pH response release rate of only 45.2% after 6 months of storage. This was because the mixture could not be oriented on the particle surface, and dimethylaminoethyl methacrylate and sodium styrene sulfonate were randomly adsorbed, forming local charge cancellation regions. Furthermore, the long chains of polyethylene glycol methacrylate, lacking the anchoring support of block structures, exhibited a coiled conformation on the particle surface, and the steric hindrance layer thickness was reduced, with the interparticle spacing smaller than the Debye length of the steric hindrance layer. Van der Waals forces dominated aggregation, thus requiring high energy consumption for redispersion. In addition, dimethylaminoethyl methacrylate and sodium styrene sulfonate were not chemically bonded, and the charge reversal of "increased cation density and retained anion" could not be achieved simultaneously when the pH decreased.

[0084] Comparative Example 3, due to the replacement of modified polyethylene glycol methacrylate with polyethylene glycol methacrylate, experienced decreased stability and loss of pH response function. This is because polyethylene glycol methacrylate relies solely on sterically hindered ethylene oxide but lacks the electrostatic repulsion provided by anionic groups. When the ionic strength of the system increases, the counterion compresses and diffuses the double layer, and van der Waals forces between particles become dominant. At this point, the single sterically hindered layer is compressed and thinned, and cannot resist particle collisions and aggregation, leading to irreversible sedimentation and drug encapsulation rupture. Simultaneously, the tertiary amine group (-N(CH3)2) in the zwitterionic structure is a key switch for pH response. Under acidic conditions, it protonates into a cation (-N... + (CH3)2H), triggering surface charge reversal and drug-load bond disruption: cationization repels positively charged drug molecules, while pure polyethylene glycol methacrylate does not have this group, and the drug can only be loaded through physical adsorption, which cannot achieve targeted release in the tumor microacid environment.

[0085] In Comparative Example 4, the reaction temperature in S2 exceeded the normal temperature, resulting in abnormal particle size growth, loss of redispersibility, and failure of pH response function. The reason is that the pure polyethylene glycol methacrylate chain contains a large number of ether bonds, which trigger a β-elimination reaction at a high temperature of 70°C, causing polyethylene glycol chain breakage. At the same time, after chain breakage, the number of ethylene oxide units is reduced from 11 to 4-5, the solvation layer thickness collapses, and the van der Waals forces and distances, as well as the thinning of the steric hindrance layer, increase the interparticle attraction by 8 times, leading to uncontrolled polycondensation during the ripening stage.

[0086] In Comparative Example 5, the molecular weight of the polyethylene glycol methacrylate chain was replaced from 500 to 350g because the steric hindrance layer provided by polyethylene glycol methacrylate was thinner, but insufficient to overcome the van der Waals forces between particles. During storage, the particles gradually approached each other, and irreversible aggregation occurred after crossing the energy barrier. Redispersion still required energy and also had a certain impact on release performance.

[0087] In summary, this invention, through the design of a specific zwitterionic block copolymer dispersion and its innovative simultaneous introduction and in-situ covalent anchoring during the critical stage of silica sol particle growth, coupled with precise process control, successfully achieves "one-step synergistic development of particle growth and surface modification." Simultaneously, this solution effectively solves the long-standing problems of dry hard agglomeration, high viscosity due to high solids content, and lack of intelligent functions in nano-silica dispersions. It endows the product with superior properties such as ultra-high solids content, low viscosity, permanent dry stability with spontaneous redispersibility, and pH-responsive intelligent release, all while being a green and environmentally friendly process. Furthermore, the effectiveness of the technical solution and the necessity of various elements, such as covalent anchoring, zwitterionic structure, and appropriate PEG chain length, are fully verified through the data from the examples and comparisons with comparative examples.

[0088] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

[0089] This invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for preparing a nano-silica dispersion, characterized in that, The preparation steps are as follows: Step S1: Add modified polyethylene glycol methacrylate to a mixed solvent of ethanol and deionized water, heat to 30-50℃, stir for 15-25 min, add tetraethyl orthosilicate, stir for 8-12 min, add 0.1 mol / L HCl solution, adjust pH to 1.8-2.2, react for 1-3 h, the reaction is complete, and a mixed solution is obtained; Step S2: Add the mixed solution to the flask, add 0.1 mol / L ammonia water, adjust the pH to 8.8-9.2, heat to 55-65℃, add the mixed solution of tetraethyl orthosilicate and modified polyethylene glycol methacrylate and ethanol, stir the reaction for 5-7 hours at a speed of 350-450 rpm, and the reaction is complete to obtain a sol. Step S3: Add the sol to the flask, heat to 50-70℃, react for 10-14 hours. Once the reaction is complete, replace the solvent with deionized water using an ultrafiltration device, concentrate under reduced pressure, and obtain a nano-silica dispersion. The preparation steps of the modified polyethylene glycol methacrylate are as follows: Under a nitrogen atmosphere, dimethylaminoethyl methacrylate, sodium styrene sulfonate, and polyethylene glycol methacrylate were added to anhydrous ethanol solvent, stirred and mixed, and the initiator azobisisobutyronitrile was added. The mixture was heated to 65-75℃ and reacted for 22-26 hours. The temperature was then lowered to 5-10℃, hydroquinone was added, and the mixture was allowed to stand to precipitate. The precipitate was filtered, washed, and dried to obtain modified polyethylene glycol methacrylate. The molecular weight of polyethylene glycol methacrylate is 500.

2. The method for preparing a nano-silica dispersion according to claim 1, characterized in that, The volume ratio of ethanol to deionized water in step S1 is 4:

1.

3. The method for preparing a nano-silica dispersion according to claim 1, characterized in that, The mass ratio of modified polyethylene glycol methacrylate to tetraethyl orthosilicate in step S1 is 1:4.6-4.

7.

4. The method for preparing a nano-silica dispersion according to claim 1, characterized in that, The mass ratio of the mixed solution, tetraethyl orthosilicate and modified polyethylene glycol methacrylate in step S2 is 1:0.32-0.33:0.008-0.

01.

5. The method for preparing a nano-silica dispersion according to claim 1, characterized in that, The mass ratio of modified polyethylene glycol methacrylate to ethanol in step S2 is 1:17-19.

6. The method for preparing a nano-silica dispersion according to claim 1, characterized in that, The mass ratio of dimethylaminoethyl methacrylate, sodium styrene sulfonate, polyethylene glycol methacrylate, initiator azobisisobutyronitrile, and hydroquinone is 1:1.25-1.35:4.9-5.1:0.008-0.012:0.0008-0.0012.

7. The method for preparing a nano-silica dispersion according to claim 1, characterized in that, Hydroquinone is a polymerization inhibitor.

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