A method for preparing morphology-tunable hollow SiO2 nanoparticles and SiO2 thin films
Hollow SiO2 nanoparticles with tunable morphology were successfully prepared by using the sol-gel method and modified polydimethylsiloxane, which solved the problems of complex preparation methods and high equipment costs in the existing technology and achieved the effect of high transmittance of SiO2 thin film.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2025-01-15
- Publication Date
- 2026-04-03
AI Technical Summary
Existing technologies struggle to prepare porous SiO2 nanoparticles with tunable morphology under mild conditions, resulting in uncontrollable refractive index. Furthermore, traditional methods suffer from high equipment costs, complex operations, or damage to the substrate.
Hollow SiO2 nanoparticles with controllable morphology were synthesized by sol-gel method using polyacrylic acid as a template agent. The morphology of the nanoparticles was controlled by the volume ratio of polydimethylsiloxane and tetraethyl orthosilicate, and the transmittance of the SiO2 film was improved by using modified polydimethylsiloxane.
The study achieved the preparation of hollow SiO2 nanoparticles with tunable morphology under mild conditions, which significantly improved the transmittance of SiO2 films to specific wavelengths of light, especially the transmittance in the wavelength range of 800-900 nm, which reached 98.3%-98.6%.
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Figure CN119898772B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of optical thin films and nanomaterials technology. More specifically, this invention relates to a method for preparing hollow SiO2 nanoparticles with adjustable morphology and SiO2 thin films. Background Technology
[0002] Porous optical thin films have broad application prospects in sensors and microelectronics due to their advantages of high specific surface area, low dielectric constant, and tunable refractive index. SiO2, with its low refractive index, low dielectric constant, chemical inertness, and thermal stability, has attracted widespread attention for its applications in optics and electronics. Although SiO2 (refractive index n = 1.46) is already considered a low-refractive-index dense material, practical applications of optical devices often require even lower refractive indices, thus prompting research into porous SiO2 thin films with ultra-low refractive indices and different morphologies. Introducing pores into the film reduces the refractive index of SiO2, but it still falls far short of the refractive index of air (1.0). Therefore, it is necessary to study different methods for preparing low-refractive-index SiO2 materials. Chemical etching and high-temperature calcination of template agents are effective methods for obtaining porous SiO2 materials; however, the toxicity and harmfulness of etching agents hinder large-scale production and application, while high-temperature calcination can damage precision optical substrates. Furthermore, while tilted-angle deposition can produce SiO2 nanorod array films, this method is costly, complex, and difficult to control in terms of refractive index and film thickness, and it is not suitable for large-area fabrication. Therefore, there is a need to develop a method for preparing porous SiO2 nanoparticles with different morphologies under mild conditions, which can then be used to prepare porous SiO2 films with tunable refractive index. Summary of the Invention
[0003] One object of the present invention is to solve at least the above-mentioned problems and / or defects, and to provide at least the advantages described below.
[0004] To achieve these objectives and other advantages according to the present invention, a method for preparing morphology-tunable hollow SiO2 nanoparticles is provided, comprising: using polyacrylic acid as a template agent and polydimethylsiloxane and tetraethyl orthosilicate as raw materials, preparing hollow SiO2 nanoparticle sol by sol-gel method, and synthesizing morphology-controllable hollow SiO2 nanoparticles by changing the volume ratio of polydimethylsiloxane and tetraethyl orthosilicate.
[0005] Preferably, the process specifically includes the following steps:
[0006] Step 1: Dissolve a certain amount of polyacrylic acid in ammonia water at room temperature, then add anhydrous ethanol and mix and stir to obtain solution A;
[0007] Step 2: Under certain temperature conditions, add a certain amount of polydimethylsiloxane to solution A from step 1 to obtain a mixture;
[0008] Step 3: Divide a certain amount of tetraethyl orthosilicate into 5 equal parts and gradually add them to the mixture obtained in Step 2 at certain time intervals to obtain solution B;
[0009] Step 4: Stir the solution B from Step 3 thoroughly at a certain temperature until a sol is formed, and then age it.
[0010] Step 5: Filter the aged sol to obtain hollow SiO2 nanoparticles.
[0011] Preferably, in step one, the mass-to-volume ratio of polyacrylic acid, ammonia, and anhydrous ethanol is 0.10–20 g: 5–15 mL: 150–200 mL.
[0012] Preferably, in step two, the temperature of solution A is 30°C when polydimethylsiloxane is added, and the volume ratio of polydimethylsiloxane to ammonia is 0-1:5-15.
[0013] Preferably, in step three, the time interval is 1 hour.
[0014] Preferably, in step three, the volume ratio of polydimethylsiloxane to tetraethyl orthosilicate is 1:0 to 3.
[0015] Preferably, in step four, the stirring temperature of solution B is 40–60°C, and the stirring time is 36–72 h.
[0016] Preferably, in step five, the filter paper used for filtration is PVDF filter paper with a pore size of 0.22 μm.
[0017] An SO2 thin film is prepared from hollow SiO2 nanoparticles with tunable morphology as described above.
[0018] A method for preparing an SO2 thin film includes: cleaning the substrate with a plasma cleaner, and immersing the substrate in a hollow SiO2 nanoparticle sol at a speed of 200-600 mm / min for 20-40 s using a dip-coating machine to deposit a SiO2 thin film.
[0019] To improve the transmittance of SO2 films for light with wavelengths of 800–900 nm, an equal amount of modified polydimethylsiloxane was used to replace the polydimethylsiloxane in step one. The method for preparing the modified polydimethylsiloxane includes:
[0020] Polydimethylsiloxane, diphenylsilanediol, and tridecafluorooctyltriethoxysilane were added to a reaction vessel, along with a 0.05 mol / L potassium hydroxide solution. After stirring and mixing thoroughly, the mixture was heated to 100–120 °C and stirred for 12–18 h at a stirring speed of 300–500 rpm. After the reaction was completed, the potassium hydroxide solution was removed by washing with water to obtain modified polydimethylsiloxane. The volume ratio of polydimethylsiloxane, diphenylsilanediol, tridecafluorooctyltriethoxysilane to potassium hydroxide solution was 4:1–2:1:2–4.
[0021] This invention offers at least the following advantages: Using polyacrylic acid (PAA) as a template agent, hollow SiO2 nanoparticles (HSNs) sol are prepared via a sol-gel method. By changing the volume ratio of polydimethylsiloxane (PDMS) and tetraethyl orthosilicate (TEOS), hollow SiO2 nanoparticles with controllable morphology can be synthesized. The hollow nanoparticles exhibit spherical and tadpole-like morphologies. This invention adjusts the refractive index by modifying the nanoparticle morphology, thus providing a new approach for preparing ultra-low refractive index materials.
[0022] The SiO2 film prepared using the hollow SiO2 nanoparticles of this invention has high transmittance for light in the range of 300–900 nm, but the peak transmittance is concentrated in the range of 350–400 nm. After preparing hollow SiO2 nanoparticles using polydimethylsiloxane modified with diphenylsilanediol and tridecafluorooctyltriethoxysilane, the transmittance of the SiO2 film for light in the range of 800–900 nm is significantly improved.
[0023] Other advantages, objectives and features of the present invention will become apparent in part from the following description, and in part from those skilled in the art through study and practice of the invention. Attached Figure Description
[0024] Figure 1 TEM image of the SiO2 thin film prepared in Example 1;
[0025] Figure 2 TEM image of the SiO2 thin film prepared in Example 2;
[0026] Figure 3 TEM image of the SiO2 thin film prepared in Comparative Example 1;
[0027] Figure 4 The transmittance curves of SiO2 thin films prepared for different wavelengths of light are shown for blank substrates, Example 1, Example 2 and Comparative Example 1. Detailed Implementation
[0028] The present invention will now be described in further detail with reference to the accompanying drawings, so that those skilled in the art can implement it based on the description.
[0029] It should be understood that terms such as “having,” “comprising,” and “including” as used herein do not exclude the presence or addition of one or more other elements or combinations thereof.
[0030] Example 1
[0031] This embodiment provides a method for preparing hollow SiO2 nanoparticles with tunable morphology, including the following steps:
[0032] Step 1: Dissolve 0.15g of polyacrylic acid (PAA) in 7mL of ammonia water at 25℃, then add 180mL of anhydrous ethanol and mix and stir to obtain solution A;
[0033] Step 2: Add 0.5 mL of polydimethylsiloxane to solution A at 30°C to obtain a mixture;
[0034] Step 3: Divide 1 mL of tetraethyl orthosilicate into 5 equal portions, and gradually add them to the mixture in 5 portions at 1-hour intervals to obtain solution B;
[0035] Step 4: Stir solution B from step 3 at 50°C for 48 hours until a sol is formed and then age it.
[0036] Step 5: Filter the aged sol using PVDF filter paper with a pore size of 0.22μm to finally obtain hollow SiO2 nanoparticles with adjustable morphology.
[0037] The method for preparing SiO2 thin films using hollow SiO2 nanoparticles in this embodiment is as follows: the substrate is cleaned with a plasma cleaner, and the substrate is immersed in hollow SiO2 nanoparticle sol at a speed of 500 mm / min for 30 s using a dip-coating machine to deposit a SiO2 thin film with a refractive index of 1.11.
[0038] Example 2
[0039] This embodiment provides a method for preparing hollow SiO2 nanoparticles with tunable morphology, including the following steps:
[0040] Step 1: Dissolve 0.15g PAA in 7mL ammonia water at 25℃, then add 180mL anhydrous ethanol and mix and stir to obtain solution A;
[0041] Step 2: Add 1 mL of polydimethylsiloxane to solution A from Step 1 at 30°C to obtain a mixture;
[0042] Step 3: Divide 1 mL of tetraethyl orthosilicate into 5 equal portions, and gradually add them to the mixture from Step 2 in 5 portions at 1-hour intervals to obtain solution B;
[0043] Step 4: Stir solution B from step 3 at 50°C for 48 hours until a sol is formed and then age it.
[0044] Step 5: Filter the aged sol using PVDF filter paper with a pore size of 0.22μm to finally obtain hollow SiO2 nanoparticles with adjustable morphology.
[0045] The method for preparing SiO2 thin films using hollow SiO2 nanoparticles in this embodiment is as follows: the substrate is cleaned with a plasma cleaner, and the substrate is immersed in hollow SiO2 nanoparticle sol at a speed of 500 mm / min for 30 seconds using a dip-coating machine to deposit a SiO2 thin film with a refractive index of 1.08.
[0046] Example 3
[0047] This embodiment provides a method for preparing hollow SiO2 nanoparticles with tunable morphology. The difference from Example 1 is that 0.5 mL of modified polydimethylsiloxane is used instead of the polydimethylsiloxane in Example 1. The remaining steps and parameters are the same as in Example 1. The modification method for the modified polydimethylsiloxane includes:
[0048] 8 mL of polydimethylsiloxane, 2 mL of diphenylsilanediol, and 2 mL of tridecafluorooctyltriethoxysilane were added to a reaction vessel, along with 5 mL of 0.05 mol / L potassium hydroxide solution. After stirring and mixing thoroughly, the mixture was heated to 120 °C and stirred for 12 h at a stirring speed of 400 rpm. After the reaction was completed, the potassium hydroxide solution was removed by washing with water to obtain modified polydimethylsiloxane.
[0049] The method for preparing SiO2 thin films using hollow SiO2 nanoparticles in this embodiment is as follows: the substrate is cleaned with a plasma cleaner, and the substrate is immersed in hollow SiO2 nanoparticle sol at a speed of 500 mm / min for 30 seconds using a dip-coating machine to deposit a SiO2 thin film with a refractive index of 1.07.
[0050] Example 4
[0051] This embodiment provides a method for preparing hollow SiO2 nanoparticles with tunable morphology. The difference from Example 2 is that 0.5 mL of modified polydimethylsiloxane is used instead of the polydimethylsiloxane in Example 2. The remaining steps and parameters are the same as in Example 2. Specifically, the modification...
[0052] 8 mL of polydimethylsiloxane, 3 mL of diphenylsilanediol, and 2 mL of tridecafluorooctyltriethoxysilane were added to a reaction vessel, along with 6 mL of 0.05 mol / L potassium hydroxide solution. After stirring and mixing thoroughly, the mixture was heated to 120 °C and stirred for 16 h at a stirring speed of 500 rpm. After the reaction was completed, the potassium hydroxide solution was removed by washing with water to obtain modified polydimethylsiloxane.
[0053] The method for preparing SiO2 thin films using hollow SiO2 nanoparticles in this embodiment is as follows: the substrate is cleaned with a plasma cleaner, and the substrate is immersed in hollow SiO2 nanoparticle sol at a speed of 500 mm / min for 30 seconds using a dip-coating machine to deposit a SiO2 thin film with a refractive index of 1.05.
[0054] Comparative Example 1
[0055] This comparative example provides a method for preparing hollow SiO2 nanoparticles, including the following steps:
[0056] Step 1: Dissolve 0.15g of polyacrylic acid (PAA) in 7mL of ammonia water at 25℃, then add 180mL of anhydrous ethanol and mix and stir to obtain a solution;
[0057] Step 2: Divide 1 mL of tetraethyl orthosilicate (TEOS) into 5 equal portions and add them gradually to the solution in 5 portions at 1-hour intervals.
[0058] Step 3: Stir the solution from Step 2 thoroughly at 50°C for 48 hours until a sol is formed and then allow it to age.
[0059] Step 4: Filter the sol obtained in Step 3 using PVDF filter paper with a pore size of 0.22 μm to finally obtain hollow SiO2 nanoparticles with adjustable morphology.
[0060] The method for preparing SiO2 thin films using hollow SiO2 nanoparticles in this comparative example is as follows: the substrate is cleaned with a plasma cleaner, and the substrate is immersed in hollow SiO2 nanoparticle sol at a speed of 500 mm / min for 30 s using a dip-coating machine to deposit a SiO2 thin film with a refractive index of 1.15.
[0061] like Figures 1-3 As shown, Examples 1, 2, and Comparative Example 1 obtained three types of SiO2 nanoparticles with drastically different morphologies by changing the PDMS / TEOS value, including nanotadpoles and hollow nanospheres with varying degrees of hollowness. In Comparative Example 1, when PDMS / TEOS = 0, only hollow SiO2 nanospheres were obtained, such as... Figure 3As shown, when the PDMS / TEOS value increases, the resulting hollow silica nanoparticles (HSNs) consist of hollow nanospheres and hollow nanotadpoles, as shown in the figure. Figure 1 As shown, over 60% of the nanoparticles exhibit a tadpole-like morphology. The hollow nanotadpoles have a relatively rounded shape at one end, forming the tadpole's head, while this hollow structure gradually tapers at the other end, forming the tadpole's tail. The SiO2 shell at the head and tail of the nanotadpoles has a relatively uniform thickness, approximately a few nanometers. Figure 2 As shown, with further increases in the PDMS / TEOS value, a rather peculiar phenomenon emerged: the hollow SiO2 nanoparticles were coated with a layer of dark gray substance, which is a hybrid of PDMS and SiO2. The different morphologies of the nanoparticles may be related to the deformation of PAA clusters in ethanol solution. Based on the above results, the PDMS concentration directly affects the final morphology of the SiO2 nanoparticles.
[0062] Comparative Example 2
[0063] This comparative example provides a method for preparing hollow SiO2 nanoparticles, including the following steps:
[0064] Step 1: At room temperature, dissolve 0.04g of PAA in 7mL of ammonia water to obtain an ammonia solution of PAA; then mix 180mL of ethanol with the ammonia solution of PAA in a 250mL conical flask to obtain the reaction solution;
[0065] Step 2: Then divide 1 mL of TEOS into five equal parts and add them to the vigorously stirred reaction solution in five separate additions, with an interval of one hour between additions.
[0066] Step 3: Hollow SiO2 nanoparticle sol is prepared after the reaction has proceeded for 48 hours.
[0067] The method for preparing SiO2 thin films using hollow SiO2 nanoparticles in this comparative example is as follows:
[0068] First, the substrate was immersed in Piranha solution for 1 hour, and then placed in a saturated HDMS atmosphere for 24 hours. Finally, the thin film was prepared by dip coating at a dip speed of 1000 mm / min.
[0069] This comparative example successfully synthesized hollow SiO2 nanoparticles (hollow SiO2 nanospheres and worm-like hollow SiO2 nanotubes), and the refractive index of the SiO2 film was found to be 1.28.
[0070] Comparative Example 3
[0071] This comparative example provides a method for preparing hollow SiO2 nanoparticles. The difference between this comparative example and Comparative Example 2 is that the amount of PAA used in step one of this comparative example is 0.08 g. The methods and parameters of the remaining steps of this comparative example are the same as those of Comparative Example 2.
[0072] The hollow SiO2 nanoparticles prepared in this comparative example were used to prepare a SiO2 thin film using the same method as in Comparative Example 1. The refractive index of the prepared SiO2 thin film was measured to be 1.19.
[0073] Comparative Example 4
[0074] This comparative example provides a method for preparing hollow SiO2 nanoparticles. The difference between this comparative example and Comparative Example 2 is that the amount of PAA used in step one of this comparative example is 0.15g. The methods and parameters of the remaining steps of this comparative example are the same as those of Comparative Example 2.
[0075] The hollow SiO2 nanoparticles prepared in this comparative example were used to prepare a SiO2 thin film using the same method as in Comparative Example 2. The refractive index of the prepared SiO2 thin film was measured to be 1.12.
[0076] Comparative Example 5
[0077] This comparative example provides a method for preparing hollow SiO2 nanoparticles with tunable morphology, which mainly includes the synthesis of solid SiO2 nanoparticles and their conversion into hollow SiO2 nanoparticles, specifically including the following steps:
[0078] Step 1: Mix 10 mL of TEOS, 80 g of anhydrous ethanol and 6 g of ammonia water and stir at 22 °C for 8 h to obtain a solution;
[0079] Step 2: Static age the solution in a sealed glass container at 22°C for 3 days until a white sol containing solid SiO2 nanoparticles is obtained.
[0080] Step 3: Take 5g of the white sol containing solid SiO2 nanoparticles obtained in Step 2, add it to a solution of 100g water and ethanol in a 1:1 mass ratio, and store for 7 days. Collect the hollow SiO2 nanoparticles obtained by triple centrifugation, and then redisperse them in ethanol to obtain hollow SiO2 nanoparticle sol.
[0081] The method for preparing SiO2 thin films using hollow SiO2 nanoparticles in this comparative example is as follows:
[0082] Immerse the substrate in a 0.1 wt% HF solution for 5 minutes, then rinse with deionized water. Using a dip coating machine, vertically immerse the substrate in the solution for 5 minutes, then lift it out of the solution at a given speed. Air dry for 20 minutes.
[0083] This comparative example successfully synthesized hollow SiO2 nanoparticles with different morphologies, and the refractive index of the SiO2 thin film was found to be 1.27.
[0084] Comparative Example 6
[0085] This comparative example provides a method for preparing hollow SiO2 nanoparticles with adjustable morphology. The difference between this comparative example and Comparative Example 4 is that the white sol containing solid SiO2 nanoparticles in step three is stored in a mixed solution of water and ethanol for 14 days. The methods and parameters of the remaining steps in this comparative example are the same as those in Comparative Example 5.
[0086] The SiO2 thin film prepared in this comparative example has a refractive index of 1.16.
[0087] Comparative Example 7
[0088] This comparative example provides a method for preparing hollow SiO2 nanoparticles with tunable morphology. PVP-functionalized monodisperse PS microspheres are prepared via PVP-mediated surfactant-free emulsion polymerization. Specific steps include:
[0089] Step 1: Put 10g of styrene, 3.5g of polyvinylpyrrolidone (PVP), 0.41g of α-azobisisobutylaminopyridine dihydrochloride and 100ml of deionized water into a 250ml round-bottom flask equipped with a nitrogen inlet, condenser and mechanical stirrer.
[0090] Step 2: Degas the reaction solution with nitrogen for 60 minutes, then immerse it in a 70°C water bath and stir at 300 rpm for 24 hours.
[0091] Step 3: Centrifuge to collect the prepared PS microspheres, wash them three times with ethanol, and finally disperse them in ethanol for future use.
[0092] Step 4: Dissolve 1.31g of cetyltrimethylammonium bromide (CTAB) in 40mL of anhydrous ethanol, then add TEOS (0.8mL to 4.8mL) and disperse the mixture by ultrasonic oscillation for 30 minutes.
[0093] Step 5: Take 5g of the PS microsphere ethanol dispersion from Step 3 and add it to the mixture from Step 4, then stir for 10 minutes.
[0094] Step Six: Finally, add 1 ml of ammonia to the reaction mixture and stir vigorously at 300 rpm for 3 hours at 50°C. Collect the PS / SiO2 microspheres by centrifugation and wash them three times with water and ethanol to remove residual TEOS and ammonia, obtaining hollow SiO2 nanoparticle sol.
[0095] This comparative method for preparing SiO2 thin films using hollow SiO2 nanoparticles:
[0096] The substrate was immersed in a 0.1% hydrofluoric acid solution for 5 minutes. The substrate was then lifted from the sol using a dip-coating machine at a speed of 200 mm / min. The substrate was then calcined in air at 550°C for 6 hours to remove the PS template of the PS / SiO2 microspheres, resulting in a hollow SiO2 film.
[0097] This comparative study successfully synthesized hollow SiO2 nanoparticles with different morphologies by changing the content of TEOS (0.8 mL to 4.8 mL), and found that the refractive index of the SiO2 film varied from 1.17 to 1.29.
[0098] The transmittance data of SiO2 thin films prepared by blank substrate (glass slide), Example 1, Example 2, and Comparative Example 1 for different wavelengths of light were measured respectively. Figure 4 ,from Figure 4 It can be seen that, within the wavelength range of 300–900 nm, the SiO2 films prepared in Examples 1, 2, and Comparative Example 1 exhibit significantly higher transmittance for light in this range than the blank substrate. Specifically, the SiO2 films prepared in Examples 1 and 2 show significantly higher transmittance for light in the 300–900 nm wavelength range than Comparative Example 1, and all three SiO2 films exhibit the highest transmittance for light in the 350–400 nm wavelength range. The SiO2 film prepared in Example 1 achieves a peak transmittance of 98%, while the SiO2 film prepared in Example 2 exhibits the highest transmittance. The peak transmittance of the film was 97.2%, both higher than the 96.4% of the comparative example. However, the transmittance for light in the 800-900 nm range was less than ideal. For light in the 800-900 nm range, the SiO2 film prepared in Example 1 had the lowest transmittance at 93.3%, Example 2 at 94%, and Comparative Example 1 at 93.2%. The SiO2 films prepared using modified polydimethylsiloxane in Examples 3 and 4 had the lowest transmittance for light in the 800-900 nm range at 98.3% and 98.6%, respectively, which were significantly better than those in Examples 1 and 2.
[0099] The number of devices and processing scale described herein are for the purpose of simplifying the description of the invention. Applications, modifications, and variations of the invention will be readily apparent to those skilled in the art.
[0100] Although embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details and illustrations shown and described herein.
Claims
1. A method for preparing hollow SiO2 nanoparticles with tunable morphology, characterized in that, Specifically, the following steps are included: Step 1: Dissolve a certain amount of polyacrylic acid in ammonia water at room temperature, then add anhydrous ethanol and mix and stir to obtain solution A; Step 2: Under certain temperature conditions, add a certain amount of modified polydimethylsiloxane to solution A from Step 1 to obtain a mixed solution; Step 3: Divide a certain amount of tetraethyl orthosilicate into 5 equal parts and gradually add them to the mixture obtained in Step 2 at certain time intervals to obtain solution B; Step 4: Stir the solution B from Step 3 thoroughly at a certain temperature until a sol is formed, and then age it. Step 5: Filter the aged sol to obtain hollow SiO2 nanoparticles; The preparation methods of modified polydimethylsiloxane include: Polydimethylsiloxane, diphenylsilanediol, and tridecafluorooctyltriethoxysilane were added to a reaction vessel, along with a 0.05 mol / L potassium hydroxide solution. After stirring and mixing thoroughly, the mixture was heated to 100-120°C and stirred for 12-18 hours at a stirring speed of 300-500 rpm. After the reaction was completed, the potassium hydroxide solution was removed by washing with water to obtain modified polydimethylsiloxane. The volume ratio of polydimethylsiloxane, diphenylsilanediol, tridecafluorooctyltriethoxysilane to potassium hydroxide solution was 4:1-2:1:2-4.
2. The method for preparing morphology-tunable hollow SiO2 nanoparticles as described in claim 1, characterized in that, In step one, the mass-to-volume ratio of polyacrylic acid, ammonia, and anhydrous ethanol is 0.10~20g:5~15mL:150~200mL.
3. The method for preparing morphology-tunable hollow SiO2 nanoparticles as described in claim 1, characterized in that, In step two, the temperature of solution A is 30°C when the modified polydimethylsiloxane is added, and the volume ratio of modified polydimethylsiloxane to ammonia is 1:5~15.
4. The method for preparing morphology-tunable hollow SiO2 nanoparticles as described in claim 1, characterized in that, In step three, the time interval is 1 hour.
5. The method for preparing morphology-tunable hollow SiO2 nanoparticles as described in claim 1, characterized in that, In step three, the volume ratio of modified polydimethylsiloxane to tetraethyl orthosilicate is 1:1~3.
6. The method for preparing morphology-tunable hollow SiO2 nanoparticles as described in claim 1, characterized in that, In step four, the stirring temperature of solution B is 40~60℃, and the stirring time is 36~72h.
7. The method for preparing morphology-tunable hollow SiO2 nanoparticles as described in claim 1, characterized in that, In step five, the filter paper used for filtration is PVDF filter paper with a pore size of 0.22μm.
8. A SiO2 thin film, characterized in that, The SiO2 thin film is prepared by the method for preparing morphology-tunable hollow SiO2 nanoparticles as described in any one of claims 1-7.
9. A method for preparing a SiO2 thin film as described in claim 8, characterized in that, include: The substrate is cleaned using a plasma cleaner, and then immersed in hollow SiO2 nanoparticle sol at a speed of 200-600 mm / min using a dip-coating machine for 20-40 seconds to deposit a SiO2 thin film.