Nanometer hollow silica microspheres, and preparation method and application thereof

Abstract

The application discloses a kind of nano hollow silica microspheres and its preparation method and application, belong to nanometer material preparation technical field, the preparation method by introducing multiple silicon sources in stages, the copolymerization effect of multiple silicon sources quickly forms the dense rigid shell layer of high crosslinking density on microsphere surface, solve the poor sphericity caused by the shell layer strength deficiency in traditional method, easy to collapse problem, ensure the integrity of hollow structure, specific steps are as follows: preparation of amphiphilic polysiloxane by introducing silicon source in stages;Subsequently, the water emulsion is formed by dispersing the amphiphilic polysiloxane, and the nano hollow silica microspheres are obtained by alkaline hydrolysis-crosslinking reaction and post, the shell thickness of the obtained microspheres is 7-10nm, the particle size distribution satisfies D50<60nm, D90<90nm, the specific surface area is <200m 2 / g, and the structure stability is excellent.

Description

Technical Field

[0001] This invention relates to the field of nanomaterial preparation technology, and in particular to a nano-hollow silica microsphere, its preparation method, and its application. Background Technology

[0002] Hollow silica microspheres can be used as an anti-reflective coating material for solar cells. Due to their suitable density and excellent dispersibility, they can form a uniform, ultra-thin coating on the cell surface, effectively reducing solar light reflection loss, improving light absorption efficiency, and thus enhancing the photoelectric conversion efficiency of solar cells. Experimental data shows that using hollow silica microspheres as an anti-reflective coating material can increase the photoelectric conversion efficiency of solar cells by approximately 10%, which is of significant value in improving the overall power generation efficiency of photovoltaic power generation systems.

[0003] The design of antireflective coatings must meet specific optical conditions, requiring the coating material to have a refractive index of approximately 1.22. However, silicon dioxide has an intrinsic refractive index of 1.46. Therefore, a high-porosity structure must be constructed to adjust the coating's refractive index to the range of 1.2–1.3 to meet the antireflective performance requirements. Considering both optical performance and structural requirements, the average particle size of the microspheres should not exceed 60 nm.

[0004] Researchers both domestically and internationally have conducted extensive research and developed various preparation methods for the controllable synthesis of hollow silica microspheres. The template method is an early and relatively mature technique; however, when using this method to prepare hollow silica microspheres with a particle size less than 100 nm, particle agglomeration is highly likely, making it difficult to meet the performance requirements of photovoltaic anti-reflection coatings. Therefore, researchers both domestically and internationally have gradually shifted to the sol-gel method. This method involves forming a sol through the hydrolysis and condensation reaction of a silicon source in solution, followed by a gelation process to directly prepare hollow silica microspheres. This method requires no template, has mild reaction conditions, and can be directly synthesized in solution, making it more suitable for large-scale industrial production.

[0005] Domestic patent CN202010492656.5 discloses a method for preparing small-sized monodisperse hollow silica microspheres. This process is simple, controllable, and has great industrialization potential, and its application in the field of display screen antireflection has achieved good results. However, when extending it to the field of photovoltaic antireflection coating, it faces significant technical bottlenecks. The hollow silica microspheres prepared by this method at room temperature have a shell rich in silanol groups (-Si-OH) and mesoporous channels of 1~10nm on the surface. During the high-temperature tempering process of the glass substrate at 500~600℃, the silanol groups undergo cross-linking condensation reaction, causing the shell to shrink and collapse, resulting in a significant decrease in the hollowness of the microspheres, which cannot meet the requirements for photovoltaic antireflection coatings.

[0006] Meanwhile, the existing literature "Silica Hollow Spheres: Precise Synthesis, Structural Regulation and Innovative Applications in the Energy Field" clearly mentions that hollow silica microspheres at the tens of nanometer scale prepared by template method or sol-gel method have shells rich in silanol groups and have mesoporous structures at room temperature. During calcination at 500~900℃ (or high-temperature treatment of the substrate), the cross-linking reaction of silanol groups will cause the shell to shrink and collapse, which will not only reduce the hollowness, but also be accompanied by a significant decrease in pore volume and specific surface area. This phenomenon is particularly prominent in scenarios such as photovoltaic anti-reflection coatings, which is highly consistent with the pain points of the high-temperature tempering process of photovoltaic glass targeted by this invention.

[0007] The paper "High-Temperature Resistance, Lightweight, and Thermally Insulating Silica Aerogel via Doping Hollow Silica Nanoparticles" further corroborates the above mechanism by comparing the high-temperature sintering behavior of small-sized solid silica nanoparticles (2-15 nm) and large-sized hollow silica nanoparticles (100-250 nm, with shell thickness as low as tens of nanometers). In-situ transmission electron microscopy heating experiments show that at 1000℃, hollow microspheres with a diameter <120 nm and a shell thickness <22 nm undergo significant structural collapse and sintering fusion due to the extensive cross-linking and condensation of silanol groups, resulting in a sharp decrease in pore volume; while microspheres with a diameter >120 nm and a shell thickness >22 nm retain structural integrity. This study clarifies the high-temperature stability threshold of nanoscale (tens of nanometer shells) hollow microspheres, providing a visual experimental basis for technical issues.

[0008] To address the aforementioned issues, a conventional solution is hydrothermal treatment. This process promotes the further condensation of silanol groups on the surface of the spherical shell to form a dense shell layer, thereby suppressing structural collapse at high temperatures and improving the stability of the hollowness. However, the hydrothermal process increases manufacturing costs and process complexity, and also generates additional waste liquid, which is not conducive to efficient industrial production. Summary of the Invention

[0009] In view of this, the present invention proposes a nano-hollow silica microsphere, its preparation method and application, which solves the technical problem of insufficient shell density and easy collapse of existing small-sized hollow silica microspheres used for photovoltaic enhancement.

[0010] The technical solution of this invention is implemented as follows: In a first aspect, the present invention provides a method for preparing nano-hollow silica microspheres, comprising the following steps: S1, Preparation of amphiphilic polysiloxane: The first silicon source, alcohol solvent, water, surfactant and catalyst are mixed and heated for 2-3 hours. Then the second silicon source is added and the reaction is continued for 2-3 hours. Finally, the amphiphilic polysiloxane is obtained by vacuum distillation. S2, Preparation of nano-hollow silica microspheres: The amphiphilic polysiloxane obtained in step S1 is added to water and stirred to form an amphiphilic polysiloxane aqueous emulsion; an alkaline medium is added to the emulsion, and the amphiphilic polysiloxane aqueous emulsion droplets are converted in situ to prepare nano-hollow silica microspheres.

[0011] Based on this technical solution, and more preferably, the amphiphilic polysiloxane aqueous emulsion is formed by stirring amphiphilic polysiloxane in water for 0.1-0.2 hours to form an emulsion with a mass concentration of 5-30%.

[0012] Based on this technical solution, and further preferably, the first silicon source is methyl orthosilicate, ethyl orthosilicate or propyl orthosilicate, and the second silicon source is methyltriethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylchlorosilane, trimethylmethoxysilane, trimethylethoxysilane or hexamethyldisiloxane.

[0013] Based on this technical solution, and further preferably, the surfactant is at least one of polyethylene glycol, polyoxyethylene polyoxypropylene monobutyl ether, or carboxylic acid-functionalized polyethylene glycol derivative, wherein the carboxylic acid-functionalized polyethylene glycol derivative is at least one of methoxy polyethylene glycol acetic acid, methoxy polyethylene glycol succinic acid, methoxy polyethylene glycol glutaric acid, methoxy polyethylene glycol succinic acid, or methoxy polyethylene glycol glutaric acid.

[0014] Based on this technical solution, and more preferably, the alcohol solvent is at least one of ethanol, methanol, propanol, isopropanol or n-butanol.

[0015] Based on this technical solution, more preferably, the mass ratio of the first silicon source to the second silicon source is 1:(0.1-0.5), the mass ratio of the surfactant to the first silicon source is (0.2-0.3):1, the mass ratio of the alcohol solvent to the first silicon source is 1:(5-15), and the mass ratio of water to the first silicon source is 1:(90-110). The alkaline medium added is at least one of sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate, or sodium bicarbonate, and the amount of the alkaline medium added is 4-10% of the mass of the amphiphilic polysiloxane.

[0016] Based on this technical solution, a further preferred embodiment is that the heating reaction temperature is 70-100℃ and the time is 2-3h, and the vacuum distillation temperature is 120-150℃ and the reaction time is 1-6h.

[0017] Secondly, the present invention provides a type of hollow silica nanosphere with a controllable and dense shell, prepared by the method of the first aspect. The nano-hollow silica microspheres have a particle size of D50 < 100 nm, D90 < 120 nm, a shell wall thickness of 7-10 nm, and a specific surface area of ​​< 200 m². 2 / g.

[0018] Thirdly, the present invention provides the application of nano-hollow silica microspheres with controllable and dense shells in antireflective materials, carriers for encapsulating and slow-releasing active substances, and adsorbent materials.

[0019] The nano-hollow silica microspheres, their preparation method, and their applications described in this invention have the following advantages over existing technologies: 1. This invention employs a phased introduction of silicon sources. By precisely controlling the amount of water in the first silicon source reaction system, the full hydrolysis and polymerization of the first silicon source are ensured, significantly improving the degree of polymerization and structural robustness of the polysiloxane basic framework. Subsequently, by flexibly adjusting the type and amount of the second silicon source, the branching degree and HLB value of the polysiloxane oligomer can be directionally controlled, thereby achieving control over the particle size (D50 < 100 nm, D90 < 120 nm) and shell density (shell wall thickness 7-10 nm, specific surface area < 200 m²) of nano-hollow silica microspheres. 2 The precise matching of / g) makes the entire preparation process clear, easy to operate, and requires no complex special equipment, making it easy to scale up for industrial production.

[0020] 2. It possesses both amphiphilic dispersion properties, eliminating the need for secondary modification processes. The directional introduction of a second silicon source creates a moderately hydrophobic structure on the surface of the nano-hollow silica microspheres, endowing the product with unique amphiphilic dispersion properties. It can maintain stable dispersion in aqueous systems without significant agglomeration, and it is also highly compatible with organic solvents. No additional hydrophobic or hydrophilic modification treatment is required, allowing it to be directly adapted to different types of coating systems such as water-based and oil-based systems. This significantly simplifies the production process, shortens the processing cycle, and significantly reduces production costs and environmental risks during the modification process.

[0021] 3. By avoiding hydrothermal processes and balancing efficiency, cost, and environmental protection, this invention employs a staged silicon source copolymerization reaction system design to directly prepare hollow silica microspheres with dense shells and stable structures. This effectively solves the technical problem of insufficient shell cross-linking in traditional room-temperature preparation processes, which leads to the shrinkage and collapse of microspheres during high-temperature applications or subsequent processing. Furthermore, it eliminates the need for additional high-pressure hydrothermal processes, reducing the investment cost of high-pressure reaction equipment and energy consumption during production, while also lowering the discharge of high-salt wastewater from hydrothermal processes. This achieves synergistic optimization of production efficiency, economic cost, and environmental performance, aligning with the development trend of green production. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a TEM image of the nano-hollow silica microspheres obtained in Example 1 of the present invention; Figure 2 This is a TEM image of the hollow silica nanospheres prepared in Example 2 of the present invention; Figure 3 This is a TEM image of the hollow silica nanospheres prepared in Example 3 of the present invention; Figure 4 This is a TEM image of the hollow silica nanospheres prepared in Example 4 of the present invention; Figure 5 This is a TEM image of the hollow silica nanospheres prepared in Example 5 of the present invention; Figure 6 This is a TEM image of the hollow silica nanospheres prepared in Example 6 of the present invention; Figure 7 The volume distribution diagram of the BJH (desorption) pores of the nano-hollow silica microspheres prepared in Example 6 of this invention; Figure 8 This is a TEM image of the nano-hollow silica microspheres prepared in Comparative Example 1 of this invention. Figure 9 This is a TEM image of the hollow silica nanospheres prepared in Example 7 of the present invention; Figure 10 This is a TEM image of the photovoltaic glass antireflection coating prepared in Example 8 of the present invention; Figure 11 This is a TEM image of the photovoltaic glass antireflection coating prepared in Example 9 of the present invention; Figure 12 The BJH pore volume distribution diagram of the nano-hollow silica microspheres prepared in Example 9 of the present invention; Figure 13 This is a TEM image of the hollow silica nanospheres prepared in Example 10 of the present invention; Figure 14 This is a reflectance curve of the anti-reflective coating on the PET surface obtained in Application Example 2 of the present invention; Figure 15 Here is a SEM image of the antireflection coating prepared in Application Example 3 of this invention; Figure 16 Here is a SEM image of the hollow silica nanospheres prepared in Example 3 of this invention. Figure 17 Here is a SEM image of the antireflection coating prepared in Application Example 4 of this invention; Figure 18 The image shows a cross-sectional SEM image of the nano-hollow silica antireflective coating prepared in Application Example 4 of this invention. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] This invention, through in-depth research on the structure and performance correlation of nano-hollow silica microspheres, found that when the microsphere particle size D50 > 40 nm, its sphericity deteriorates significantly under transmission electron microscopy (TEM) observation, exhibiting defects such as irregular deformation, surface protrusions or depressions. Furthermore, after high-temperature tempering treatment at 500-600℃, these microspheres are prone to shrinkage and collapse due to insufficient structural stability, failing to meet the long-term anti-reflection requirements of photovoltaic anti-reflection glass.

[0026] To address the aforementioned problems, this invention innovatively employs a core technical solution of introducing multiple silicon sources in stages: by precisely increasing the water content in the first silicon source reaction system, the degree of hydrolysis and polymerization of the first silicon source is controlled, significantly improving the degree of polymerization and structural regularity of the polysiloxane basic framework; then, by optimizing the type and amount of the second silicon source, the branching degree of the polysiloxane oligomer is directionally adjusted, promoting synergistic optimization of the internal structure of the silica network, specifically manifested in a significant reduction in the number of micropores and a BET specific surface area (<200m²). 2 / g) effectively reduces and significantly increases the content of Q4 silicon atoms, which represents a fully cross-linked structure, while extending the spin-lattice relaxation time, ultimately greatly improving the sphericity of the microspheres and forming a regular and uniform spherical structure.

[0027] Example 1: A dense and controllable shell of hollow silica nanospheres and its preparation method, comprising the following steps: 300g of tetraethyl orthosilicate, 28g of deionized water, 70g of ethanol, 50g of polyethylene glycol 500 and 5g of hydrochloric acid were mixed evenly and polymerized at 80°C for 2 hours. After heating to 135°C and reacting under vacuum for 2 hours, 220g of amphiphilic polysiloxane with a viscosity of 50cp was obtained. Under stirring conditions of 200 r / min, 20 g of amphiphilic polysiloxane was added to 100 g of deionized water to obtain a transparent bluish mixture. Under stirring conditions of 200 r / min, 6 g of 20% sodium hydroxide was added to the above mixture, and the reaction was continued at room temperature for 6 h to obtain a dispersion of nano-hollow silica microspheres. The transparent bluish dispersion was washed with a ceramic membrane until neutral to obtain silica hollow microspheres dispersed in an aqueous solution.

[0028] Testing revealed that the scanning electron microscope (SEM) results of the nano-hollow silica microspheres obtained in this embodiment were as follows: Figure 1 As shown, the D50 is 28.1 nm, the coefficient of variation (cv) is 0.17, the shell thickness is approximately 5.3 nm, the hollowness is approximately 24.2%, and the specific surface area is 464 m². 2 / g, pore volume is 0.76cm 3 / g.

[0029] Example 2: The difference between Example 2 and Example 1 is that, except for replacing 500 g of polyethylene glycol monomethyl ether 500 with 80 g of 1000 polyethylene glycol monomethyl ether 1000, the other steps are the same as in Example 1.

[0030] Testing revealed that the scanning electron microscope (SEM) results of the nano-hollow silica microspheres obtained in this embodiment were as follows: Figure 2 As shown, the D50 is 27.3 nm, the coefficient of variation (cv) is 0.18, the shell thickness is approximately 5.7 nm, the hollowness is approximately 19.8%, and the specific surface area is 432 m². 2 / g, pore volume 0.69cm 3 / g.

[0031] Example 3: The difference between Example 3 and Example 1 is that polyethylene glycol 350 is used, with a mass of 40g. The other methods and steps are the same as in Example 1.

[0032] Testing revealed that the scanning electron microscope (SEM) results of the nano-hollow silica microspheres obtained in this embodiment were as follows: Figure 3 As shown, the D50 is 31.2 nm, the coefficient of variation (cv) is 0.17, the shell thickness is approximately 6.7 nm, the hollowness is approximately 18.6%, and the specific surface area is 424 m². 2 / g, pore volume 0.72cm 3 / g.

[0033] Example 4: The difference from Example 1 is that the mass of polyethylene glycol 500 used is 75g, but the other steps are the same as in Example 1.

[0034] Testing revealed that the scanning electron microscope (SEM) results of the nano-hollow silica microspheres obtained in this embodiment were as follows: Figure 4As shown, D50 is 18 nm, coefficient of variation (cv) is 0.17, shell thickness is approximately 4.6 nm, hollowness is approximately 11.6%, and specific surface area is 402 m². 2 / g, pore volume 0.53cm 3 / g.

[0035] Example 5: The difference from Example 1 is that the amount of polyethylene glycol monomethyl ether added is 40g, while the other methods and steps are the same as in Example 1.

[0036] Testing revealed that the scanning electron microscope (SEM) results of the nano-hollow silica microspheres obtained in this embodiment were as follows: Figure 5 As shown in the figure, the BJH pore volume distribution of the nano-hollow silica microspheres is as follows. Figure 6 As shown, the sphericity is poor, D50 is 52.8 nm, coefficient of variation (cv) is 0.20, shell thickness is approximately 7.8 nm, hollowness is approximately 35.0%, and specific surface area is 455.95 m². 2 / g, pore volume 0.9cm 3 / g.

[0037] Example 6: 300g of tetraethyl orthosilicate, 36g of deionized water, 70g of ethanol, 50g of polyethylene glycol 500 and 5g of hydrochloric acid were mixed evenly, and then heated to 80℃ for 1.5h to polymerize. After heating to 135℃ and reacting under vacuum for 2h, 220g of amphiphilic polysiloxane with a viscosity of 46cp was obtained. Testing revealed that the scanning electron microscope (SEM) results of the nano-hollow silica microspheres obtained in this embodiment were as follows: Figure 8 As shown, the D50 is 43 nm, the coefficient of variation (cv) is 0.23, the shell thickness is approximately 8 nm, the hollowness is approximately 24.8%, and the specific surface area is 281 m². 2 / g, pore volume is 0.76cm 3 / g.

[0038] Comparative Example 1: The dispersion of hollow silica microspheres from Example 6 was separated to obtain hollow silica microspheres, which were then placed in an oven at 80°C and heated for 48 hours. The scanning electron microscope (SEM) image of the hollow silica microspheres obtained in this comparative example is shown below. Figure 7 As shown, the sphericity of the nano-hollow silica microspheres did not improve.

[0039] Example 7: 300g of methyl orthosilicate, 41g of deionized water, 70g of methanol, 60g of polyethylene glycol 500 and 0.4g of hydrochloric acid were mixed evenly and heated at 80°C for 1 hour. Then 95g of methyltriethoxysilane was added and heated at 80°C for 1.5 hours. The temperature was then raised to 135°C and the reaction was carried out under vacuum for 2 hours to obtain 220g of amphiphilic polysiloxane with a viscosity of 52cp. Testing revealed that the scanning electron microscope (SEM) results of the nano-hollow silica microspheres obtained in this embodiment were as follows: Figure 9 As shown, the D50 is 57 nm, the coefficient of variation (cv) is 0.27, the shell thickness is approximately 8.1 nm, the hollowness is approximately 34.8%, and the specific surface area is 161 m². 2 / g, pore volume 0.92cm 3 / g.

[0040] Example 8: The difference from Example 1 is that the amount of deionized water is increased to 8g and methyltriethoxysilane is increased to 100g, while the other methods and steps are the same as in Example 1.

[0041] Testing revealed that the scanning electron microscope (SEM) results of the nano-hollow silica microspheres obtained in this embodiment were as follows: Figure 10 As shown, the D50 is 54.8 nm, the coefficient of variation (cv) is 0.28, the shell thickness is approximately 8.4 nm, the hollowness is approximately 33.3%, and the specific surface area is 179 m². 2 / g, pore volume 0.90cm 3 / g.

[0042] Example 9: The difference from Example 1 is that the amount of deionized water is increased to 10g, and methyltriethoxysilane is replaced with 95g of dimethyldimethoxysilane. The other steps are the same as in Example 7.

[0043] Testing revealed that the scanning electron microscope (SEM) results of the nano-hollow silica microspheres obtained in this embodiment were as follows: Figure 11 As shown in the figure, the BJH pore volume distribution of the nano-hollow silica microspheres is as follows. Figure 12 As shown, the D50 is 54 nm, the coefficient of variation (cv) is 0.32, the shell thickness is approximately 8 nm, the hollowness is approximately 34.8%, and the specific surface area is 143 m². 2 / g, pore volume is 0.89cm 3 / g.

[0044] Example 10: The difference from Example 7 is that methyltriethoxysilane is replaced with 20g of trimethylchlorosilane, while the other steps are the same as in Example 7.

[0045] Testing revealed that the scanning electron microscope (SEM) results of the nano-hollow silica microspheres obtained in this embodiment were as follows: Figure 13 As shown, the D50 is 52.8 nm, the coefficient of variation (cv) is 0.31, the shell thickness is approximately 8 nm, the hollowness is approximately 33.9%, and the specific surface area is 113 m². 2 / g, pore volume 0.82cm 3 / g.

[0046] Application Example 1: The application of the silica hollow microspheres prepared in Examples 1 and 8 as antireflective films on cellulose triacetate (TAC) is as follows: According to the weight parts, 18 parts of hollow silica microspheres prepared in Example 5, Comparative Example 2, and Comparative Example 5, 250 parts of ethyl acetate, 100 parts of fluorinated methyl methacrylate, and 11 parts of photoinitiator Darocure 1173 were mixed to obtain an anti-reflective coating. The anti-reflective coating was applied to the TAC substrate using a coating machine die head, maintaining a uniform flow rate of 1.0 cc / min to achieve a wet coating thickness of 3 μm. The coating was then dried at 80°C under nitrogen protection for 3 minutes to achieve a dry film thickness of 100 nm, thus obtaining the anti-reflective coating on the TAC surface. Double-sided coating was then applied. Transmittance (TT) and haze were measured using a haze meter. The antireflective film prepared using microspheres from Example 1 had a transmittance of 94.86% and a haze of 0.28%. The antireflective film prepared using microspheres from Example 5 had a transmittance of 95.1% and a haze of 0.31%.

[0047] Application Example 2: The hollow silica microspheres prepared in Examples 1 and 8 are used as antireflective films on polyethylene terephthalate (PET), specifically as follows: According to the weight parts, 78.5 parts of hollow silica microspheres, 258 parts of propylene glycol monomethyl ether, 100 parts of fluorinated methyl methacrylate, and 1 part of photoinitiator Darocure1173 are mixed to obtain an anti-reflective coating. The anti-reflective coating is applied to the PET substrate using a coating machine die head. The slurry is maintained at a uniform flow rate of 1.0 cc / min through the die head, resulting in a wet coating thickness of 2 μm. The coating is then dried at 80°C under nitrogen protection for 3 minutes, resulting in a dry film coating thickness of 100 nm. This yields the anti-reflective coating on the PET surface. Performance parameters are as follows: Figure 14 As shown.

[0048] Application Example 3: The application of the hollow silica microspheres prepared in Example 9 for anti-reflection in photovoltaic glass is as follows: According to the specified weight parts, 1 part of the hollow silica microspheres prepared in Comparative Example 5, 0.6 parts of adhesion promoter Z-6040, 0.2 parts of wetting agent BYK-3455, 0.8 parts of dispersant Disperbyk-180, and 97.4 parts of water are mixed to obtain the nano-hollow microsphere antireflection coating solution. The nano-hollow microsphere antireflection coating solution is uniformly coated onto the glass surface by roller coating, with a film thickness of 150 nm. Then, it is baked at 300℃ for 5 min, and then tempered in a tempering furnace at 650℃ to obtain photovoltaic antireflection glass.

[0049] SEM image of the antireflection coating in Application Example 3 is shown below. Figure 15 As shown, the cross-sectional view of the antireflective coating is as follows. Figure 16 As shown, the transmittance of the obtained antireflective film is 1.2% higher than that of the uncoated glass.

[0050] Application Example 4: Application Example 4 uses hollow silica microspheres prepared in Example 8, and the other methods and steps are the same as in Application Example 3.

[0051] SEM image of the antireflection coating in Application Example 4 is shown below. Figure 17 As shown, the cross-sectional view of the antireflective coating is as follows. Figure 18 As shown, the transmittance of the obtained antireflective film is 2.9% higher than that of the uncoated glass.

[0052] In summary, the nano-hollow silica microspheres prepared by this technical solution can maintain excellent structural stability even when the particle size D50 is controlled within the target range of less than 40nm. After being treated with a high-temperature tempering process of 500-600℃ for photovoltaic anti-reflective glass, they can effectively resist structural deformation and collapse under high-temperature conditions, continuously maintain good anti-reflective performance, fully meet the actual application requirements of photovoltaic anti-reflective glass, and significantly improve the reliability and service life of the product.

[0053] 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, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing nano-hollow silica microspheres, characterized in that, Includes the following steps: S1, Preparation of amphiphilic polysiloxane: The first silicon source, alcohol solvent, water, surfactant and catalyst are mixed and heated for 2-3 hours. Then the second silicon source is added and the reaction is continued for 2-3 hours. Finally, the amphiphilic polysiloxane is obtained by vacuum distillation. S2, Preparation of nano-hollow silica microspheres: The amphiphilic polysiloxane obtained in step S1 is added to water and stirred to form an amphiphilic polysiloxane aqueous emulsion. An alkaline medium is added to the emulsion, and the amphiphilic polysiloxane aqueous emulsion droplets are converted in situ to prepare nano-hollow silica microspheres.

2. The method for preparing nano-hollow silica microspheres according to claim 1, characterized in that, The first silicon source is methyl orthosilicate, ethyl orthosilicate, or propyl orthosilicate, and the second silicon source is methyltriethoxysilane, methyltrimethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylchlorosilane, trimethylmethoxysilane, trimethylethoxysilane, or hexamethyldisiloxane.

3. The method for preparing nano-hollow silica microspheres according to claim 2, characterized in that, The amphiphilic polysiloxane aqueous emulsion is formed by stirring amphiphilic polysiloxane in water for 0.1-0.2 hours to form an emulsion with a mass concentration of 5-30%.

4. The method for preparing nano-hollow silica microspheres according to claim 1, characterized in that, The surfactant is at least one of polyethylene glycol, polyoxyethylene polyoxypropylene monobutyl ether, or a carboxylic acid-functionalized polyethylene glycol derivative, wherein the carboxylic acid-functionalized polyethylene glycol derivative is at least one of methoxy polyethylene glycol acetic acid, methoxy polyethylene glycol succinic acid, methoxy polyethylene glycol glutaric acid, methoxy polyethylene glycol succinic acid, or methoxy polyethylene glycol glutamate.

5. The method for preparing nano-hollow silica microspheres according to claim 1, characterized in that, The alcohol solvent is at least one of ethanol, methanol, propanol, isopropanol, or n-butanol.

6. The method for preparing nano-hollow silica microspheres according to claim 1, characterized in that, The mass ratio of the first silicon source to the second silicon source is 1:(0.1-0.5), the mass ratio of the surfactant to the first silicon source is (0.2-0.3):1, the mass ratio of the alcohol solvent to the first silicon source is 1:(5-15), and the mass ratio of water to the first silicon source is 1:(90-110). The alkaline medium added is at least one of sodium hydroxide, potassium hydroxide, ammonia, sodium carbonate, or sodium bicarbonate, and the amount of the alkaline medium added is 4-10% of the mass of the amphiphilic polysiloxane.

7. The method for preparing nano-hollow silica microspheres according to claim 1, characterized in that, The heating reaction temperature is 70-100℃ and the time is 2-3h; the vacuum distillation temperature is 120-150℃ and the reaction time is 1-6h.

8. A type of hollow silica nanosphere, prepared by the method for preparing hollow silica nanospheres according to any one of claims 1-8, characterized in that, The nano-hollow silica microspheres have a particle size of D50 < 100 nm, D90 < 120 nm, a shell wall thickness of 7-10 nm, and a specific surface area of ​​< 200 m². 2 / g.

9. The application of the nano-hollow silica microspheres according to claim 8 in antireflective materials, carriers for encapsulating and sustaining the release of active substances, and adsorbent materials.

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