Monomesoporous silica nanobowl and preparation method thereof

Abstract

The application belongs to the technical field of nanometer materials, and particularly discloses a single mesoporous silica nanobowl and a preparation method thereof. 2 The single mesoporous silica nanobowl has a hollow structure, a particle size of 20-40 nm, a specific surface area of 500-800 m / g, and an opening size of 10-25 nm on the surface of the single mesoporous silica nanobowl. The preparation method comprises the following steps: (1) preparing a single micelle aqueous solution; (2) preparing a TMB@PEO-PPO-PEO single micelle composite solution; (3) preparing a TMB@PEO-PPO-PEO@SiO2 composite nanometer material solution; (4) preparing a composite material solution; and (5) preparing a single mesoporous silica nanobowl. The prepared single mesoporous silica nanobowl has an ultrasmall and uniform size, unique open pores and a large number of surface micropores, so that the specific surface area of the material is greatly improved, the active sites of a chemical reaction are increased, and the material has good hydrophobicity due to the rich methyl groups on the surface.

Description

Technical Field

[0001] This invention relates to the field of nanomaterials technology, and more specifically, to a single-mesoporous silica nanobowl and its preparation method. Background Technology

[0002] Bowl-shaped materials, due to their many excellent properties such as high-activity interfaces, large pore volume, unique pore structure, and unobstructed mass transport channels, are widely used in research fields such as energy storage, adsorption, catalysis, energy, and biomedicine. However, the morphology and structure of bowl-shaped materials synthesized using traditional template-free methods, hard template methods, and nanoemulsion methods are often uncontrollable. This uncontrollability leads to extreme inhomogeneity in their quantity, size, pore size, and thickness, and can even cause irregular aggregation and severe deformation of nanoparticles. Furthermore, most of these materials have few mesoporous structures and are excessively large, typically at the micrometer level, which limits their practical applications to some extent. For example, patent number CN202110263736.8 discloses a method for preparing silica nanobowls, with the prepared silica nanobowls having a size of approximately 300 nm. To date, no work has been reported on the synthesis of ultra-small single-mesoporous bowl-shaped nanoparticles. Summary of the Invention

[0003] To address the shortcomings of existing technologies, the present invention aims to provide a single-mesoporous silica nanobowl and its preparation method. The single-mesoporous silica nanobowl and its preparation method provided by the present invention utilize a stable single-micelle-assisted interface assembly method to synthesize ultra-small single-mesoporous silica nanobowls, solving the synthesis problem of ultra-small asymmetric hollow mesoporous structure materials. The prepared single-mesoporous silica nanobowls possess ultra-small and uniform dimensions. Unique open channels and numerous surface micropores significantly increase the specific surface area of ​​the material, increasing the active sites for chemical reactions. Furthermore, the surface contains abundant methyl groups, giving the material superhydrophobicity and corrosion resistance.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a single-mesoporous silica nanobowl, wherein the single-mesoporous silica nanobowl has a hollow structure, the particle size of the single-mesoporous silica nanobowl is 20-40 nm, and the specific surface area is 500-800 m². 2 / g, the size of the recessed pores on the surface of the monoporous silica nanobowl is 10-25 nm.

[0005] Another aspect of the present invention provides the following technical solution: a method for preparing a single-mesoporous silica nanobowl, comprising the following steps:

[0006] (1) Block copolymer F127 (PEO-PPO-PEO) and hydrochloric acid aqueous solution with a concentration of 1-5 mol / L are mixed evenly at a mass ratio of 1:30-100. The hydrophobic PPO end automatically aggregates in the interior because it is insoluble in hydrochloric acid aqueous solution, while the hydrophilic PEO end is distributed in the outer layer because it has good compatibility with hydrochloric acid aqueous solution, forming a spherical single micelle aqueous solution with a double-layer structure.

[0007] (2) Mix 1,3,5-trimethylbenzene (TMB) with the aqueous solution of single micelles prepared in step (1) and stir for 14-36 h at a stirring speed of 800-1500 r / min. Due to the principle of like dissolves like, the TMB in the oil phase will enter the hydrophobic PPO region inside the aqueous solution of single micelles, thereby swelling the polymer single micelles to obtain TMB@PEO-PPO-PEO single micelle composite solution.

[0008] (3) Tetraethyl orthosilicate (TEOS) was added to the TMB@PEO-PPO-PEO single micelle composite solution prepared in step (2), and stirred at 800-1500 r / min for 5-24 h. After the addition of tetraethyl orthosilicate, the silica precursor can interact with the hydrophilic polyoxyethylene (PEO) fragment of amphiphilic F127; through the interaction of van der Waals forces and intermolecular hydrogen bonds, a core-shell structure TMB@PEO-PPO-PEO@SiO2 composite nanomaterial solution with hydroxyl groups on the surface was obtained.

[0009] The chemical formula for the reaction in specific step (3) is as follows:

[0010]

[0011] (4) Dimethyl dimethoxysilane (DMDMS) was added as a capping agent to the TMB@PEO-PPO-PEO@SiO2 composite nanomaterial solution prepared in step (3), and stirred at 800-1500 r / min for 12-36 h to obtain a TMB@PEO-PPO-PEO@SiO2 organic-inorganic hybrid composite material solution with abundant methyl groups on the surface.

[0012] The chemical formula for the reaction in specific step (4) is as follows:

[0013]

[0014] As can be seen from the above reaction chemical formula, most of the hydroxyl groups on the surface of the composite nanomaterial are changed to methyl groups. The methyl end becomes hydrophobic, while the hydroxyl end becomes hydrophilic, thus the composite nanomaterial exhibits a greater degree of hydrophobicity.

[0015] (5) The composite material solution in step (4) is allowed to stand and evaporate to remove 1,3,5-trimethylbenzene from the composite material solution, followed by centrifugation and washing; then the obtained sample is refluxed in anhydrous ethanol to remove the block copolymer, and finally dried to obtain a monoporous silica nanobowl.

[0016] During the settling process, hydrophobic particles spontaneously migrate towards the biphase interface, minimizing the interfacial energy of the system. Furthermore, the presence of surface methyl groups increases the steric hindrance between particles, preventing aggregation and maintaining a monolayer array at the interface. This array is a key prerequisite for achieving directional concavity during evaporation. Subsequently, during evaporation, TMB molecules in the upper oil phase preferentially evaporate. As evaporation proceeds, the liquid level drops to a critical level, and TMB within the micelle core begins to diffuse outward. At this stage, the volume of TMB molecules within the silica shell gradually decreases, driving the silica particles to rise towards the oil phase. Simultaneously, the reduction of TMB causes contraction of the internal F127 micelles (elastic compression of PPO fragments). Simultaneously, as the organic phase of TMB decreases, the hydrophobic oligomers at the bottom of the silica shell migrate upward, thinning the silica shell in the aqueous phase. Therefore, due to the compression of the hydrophobic shell by water and the contractile tension of the micelles, the soft silica shell concaves upward in the aqueous phase, ultimately forming concave bowl-shaped monoporous nanoparticles. For a detailed mechanism, see [link to mechanism description]. Figure 9 .

[0017] Furthermore, the mass ratio of the 1,3,5-trimethylbenzene in step (2) to the block copolymer F127 in step (1) is 1:0.33-10.

[0018] Furthermore, the mass ratio of the tetraethyl orthosilicate in step (3) to the block copolymer F127 in step (1) is 1:0.33-10.

[0019] Furthermore, the mass ratio of the dimethyldimethoxysilane in step (4) to the block copolymer F127 in step (1) is 1:0.17-5.

[0020] Furthermore, in step (5), the mixture is allowed to stand at 23-60 °C for 12-48 h to evaporate.

[0021] Furthermore, in step (5), the centrifugation speed is 30,000-80,000 r / min and the centrifugation time is 10-30 min.

[0022] Furthermore, the washing conditions in step (5) are as follows: first, use distilled water and wash 3 times, then use a 95% ethanol solution and wash 3 times.

[0023] Furthermore, the reflux temperature in step (5) is 50-90 ℃ and the reflux time is 0.5-5 h.

[0024] The advantages of this invention are:

[0025] 1. This invention discloses a single-mesoporous silica nanobowl and its preparation method. The ultra-small single-mesoporous silica nanobowl is synthesized by a stable single-micelle assisted interface assembly method, which solves the problem of synthesizing ultra-small asymmetric hollow mesoporous structure materials. The prepared single-mesoporous silica nanobowl has an ultra-small and uniform size. The unique open channels and a large number of surface micropores greatly improve the specific surface area of ​​the material and increase the active sites for chemical reactions.

[0026] 2. This invention discloses a single-mesoporous silica nanobowl with a surface opening size of approximately 17 nm, a particle size of approximately 32 nm, and a specific surface area as high as 519 m². 2 / g, exhibits excellent dispersibility and uniformity, and its surface contains abundant methyl groups, giving the material good hydrophobic properties. Attached Figure Description

[0027] Figure 1 This is a scanning electron microscope image of the single-mesoporous silica nanobowl prepared in Example 1 of the present invention.

[0028] Figure 2 This is a transmission electron microscope (TEM) image of the single-mesoporous silica nanobowl prepared in Example 1 of the present invention.

[0029] Figure 3 The infrared spectrum of the single-mesoporous silica nanobowl prepared in Example 1 of this invention.

[0030] Figure 4 This is a scanning electron microscope image of the single-mesoporous silica nanobowl prepared in Example 2 of the present invention.

[0031] Figure 5 This is a scanning electron microscope image of the single-mesoporous silica nanobowl prepared in Example 3 of the present invention.

[0032] Figure 6 This is a scanning electron microscope image of the single-mesoporous silica nanobowl prepared in Example 4 of the present invention.

[0033] Figure 7 This is a scanning electron microscope image of the single-mesoporous silica nanobowl prepared in Example 5 of the present invention.

[0034] Figure 8 The image shows the hydrophobic angle diagrams of the bare zinc sheet coated with the single-mesoporous silica nanobowl prepared in Example 1 of this invention and the bare zinc sheet.

[0035] Figure 9 This diagram illustrates the mechanism by which the present invention prepares single-mesoporous silica nanobowls.

[0036] Figure 10 This is a scanning electron microscope image of the single-mesoporous silica nanobowl prepared in Example 6 of the present invention. Detailed Implementation

[0037] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0038] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0039] In this invention, unless otherwise stated, the directional terms such as "up" and "down" generally refer to the directions shown in the accompanying drawings, or to the vertical, perpendicular, or gravitational direction; similarly, for ease of understanding and description, "left" and "right" generally refer to the left and right shown in the accompanying drawings; "inner" and "outer" refer to the inner and outer contours of each component itself, but the above directional terms are not intended to limit this invention.

[0040] Example 1: A method for preparing a single-mesoporous silica nanobowl, comprising the following steps:

[0041] (1) Mix 0.3 g of block copolymer F127 (PEO-PPO-PEO) with 15 mL of 2 mol / L hydrochloric acid aqueous solution to form a bilayer structure of spherical single micelle aqueous solution;

[0042] (2) Add 0.3 g of 1,3,5-trimethylbenzene (TMB) to the aqueous solution of single micelles prepared in step (1), mix and stir for 14 h at a stirring speed of 1400 r / min to obtain TMB@PEO-PPO-PEO single micelle composite solution.

[0043] (3) Add 0.3 g of tetraethyl orthosilicate (TEOS) to the TMB@PEO-PPO-PEO single micelle composite solution prepared in step (2) and stir at 1400 r / min for 8 h to obtain a core-shell structure TMB@PEO-PPO-PEO@SiO2 composite nanomaterial solution with hydroxyl groups on the surface.

[0044] (4) 0.1 g of dimethyldimethoxysilane (DMDMS) was added as a capping agent to the TMB@PEO-PPO-PEO@SiO2 composite nanomaterial solution prepared in step (3), and stirred at 1400 r / min for 24 h to obtain a TMB@PEO-PPO-PEO@SiO2 organic-inorganic hybrid composite material solution with abundant methyl groups on the surface.

[0045] (5) The composite material solution in step (4) was allowed to stand and evaporate at room temperature for 24 h to remove 1,3,5-trimethylbenzene from the composite material solution. Then the composite material solution was centrifuged at 80,000 r / min for 15 min, followed by washing with water 3 times and washing with 95% ethanol 3 times. Finally, the obtained sample was refluxed in anhydrous ethanol at 80 °C for 1 h to remove the block copolymer. Finally, it was dried to obtain a monoporous silica nanobowl.

[0046] The microstructure of the monoporous silica nanobowls prepared in Example 1 was observed using scanning electron microscopy (SEM) and transmission electron microscopy (TEM), and the results are as follows: Figure 1 and Figure 2 As shown, the single-mesoporous silica nanobowls prepared in this embodiment are uniform in size, thickness, and pore size; from Figure 1 It can be seen that the prepared ultra-small bowl-shaped particles have a particle size of 20-40 nm and a specific surface area of ​​519 m². 2 / g, and exhibited good dispersibility. A mesopore was found at the center of each particle. Furthermore, a considerable number of nanoparticles were successfully observed to have the bowl-shaped opening facing away from the field of view, primarily showing the back of the bowl (the convex portion). From Figure 2 The particle's overall morphology can be seen to be a hollow bowl-shaped structure. Measurements show that the thickness of the hollow shell is about 7 nm, and the pore size of the recessed mesopores is about 17 nm.

[0047] The monoporous silica nanobowls prepared in Example 1 were used to prepare samples via a pellet pressing method, and infrared spectroscopy was performed. The results are as follows: Figure 3 As shown, from Figure 3 The FT-IR spectrum shows that at 2960 cm⁻¹ −1 The absorption band shown can be attributed to the vibration of the C−H bond in the -CH3 group, indicating the presence of a methane-bridging framework.

[0048] Example 2: The overall method is the same as that in Example 1, except that the amount of 1,3,5-trimethylbenzene (TMB) added in step (2) is 0.5 g.

[0049] The microstructure of the monoporous silica nanobowls prepared in Example 2 was observed using a scanning electron microscope (SEM), and the results are as follows: Figure 4 As shown, from Figure 4 It can be seen that the prepared ultra-small bowl-shaped particles have a particle size of 20-40 nm and a specific surface area of ​​612 m². 2 / g, the pore size of the recessed mesopores is about 22-25nm. The pore size of the recessed mesopores is larger than that of Example 1. This is because when the amount of TMB increases, more TMB molecules will occupy the space inside the mesopores, thereby increasing the size of the mesopores.

[0050] Example 3: The overall method is the same as that in Example 1, except that the amount of tetraethyl orthosilicate (TEOS) added in step (3) is 0.5 g.

[0051] The microstructure of the monoporous silica nanobowls prepared in Example 3 was observed using a scanning electron microscope (SEM), and the results are as follows: Figure 5 As shown, from Figure 5 It can be seen that the prepared ultra-small bowl-shaped particles have a particle size of 20-40 nm and a specific surface area of ​​510 m². 2 / g, the pore size of the recessed mesopores is 12-17nm, which is smaller than that of Example 1. The overall phenomenon of obvious aggregation is observed, indicating that the precursor is excessively aggregated and reacted in a local area, thereby forming aggregated silicon dioxide. More silicon dioxide accumulates around the template, which will fill the space that could have formed larger mesopores.

[0052] Example 4: A method for preparing a single-mesoporous silica nanobowl, comprising the following steps:

[0053] (1) Mix 0.3 g of block copolymer F127 (PEO-PPO-PEO) with 9 mL of 1 mol / L hydrochloric acid aqueous solution to form a bilayer structure of spherical single micelle aqueous solution;

[0054] (2) Add 0.1 g of 1,3,5-trimethylbenzene (TMB) to the aqueous solution of single micelles prepared in step (1), mix and stir for 25 h at a stirring speed of 800 r / min to obtain TMB@PEO-PPO-PEO single micelle composite solution;

[0055] (3) Add 0.1 g of tetraethyl orthosilicate (TEOS) to the TMB@PEO-PPO-PEO single micelle composite solution prepared in step (2) and stir at 800 r / min for 5 h to obtain a core-shell structure TMB@PEO-PPO-PEO@SiO2 composite nanomaterial solution with hydroxyl groups on the surface.

[0056] (4) 0.05 g of dimethyldimethoxysilane (DMDMS) was added as a capping agent to the TMB@PEO-PPO-PEO@SiO2 composite nanomaterial solution prepared in step (3), and stirred at 800 r / min for 12 h to obtain a TMB@PEO-PPO-PEO@SiO2 organic-inorganic hybrid composite material solution with abundant methyl groups on the surface.

[0057] (5) The composite material solution in step (4) was allowed to stand and evaporate at room temperature for 12 h to remove 1,3,5-trimethylbenzene from the composite material solution. Then the composite material solution was centrifuged at 30,000 r / min for 30 min (the lower the speed, the longer the time required). Then it was washed with water 3 times and washed with 95% ethanol 3 times. Finally, the obtained sample was refluxed in anhydrous ethanol at 50 °C for 5 h (the lower the temperature, the longer the time required) to remove the block copolymer. Finally, it was dried to obtain a monoporous silica nanobowl.

[0058] The microstructure of the monoporous silica nanobowls prepared in Example 4 was observed using a scanning electron microscope (SEM), and the results are as follows: Figure 6 As shown, from Figure 6 It can be seen that the prepared ultra-small bowl-shaped particles have a particle size of 20-40 nm and a specific surface area of ​​452 m². 2 / g, the pore size of the recessed mesopores is 10-15nm, wherein the pore size of the recessed mesopores is smaller than that of Example 1, which in turn leads to a smaller specific surface area compared to Example 1.

[0059] Example 5: A method for preparing a single-mesoporous silica nanobowl, comprising the following steps:

[0060] (1) Mix 0.3 g of block copolymer F127 (PEO-PPO-PEO) with 30 mL of 5 mol / L hydrochloric acid aqueous solution to form a bilayer structure of spherical single micelle aqueous solution;

[0061] (2) Add 3 g of 1,3,5-trimethylbenzene (TMB) to the aqueous solution of single micelles prepared in step (1), mix and stir for 36 h at a stirring speed of 1500 r / min to obtain TMB@PEO-PPO-PEO single micelle composite solution.

[0062] (3) Add 3 g of tetraethyl orthosilicate (TEOS) to the TMB@PEO-PPO-PEO single micelle composite solution prepared in step (2) and stir at 1500 r / min for 24 h to obtain a core-shell structure TMB@PEO-PPO-PEO@SiO2 composite nanomaterial solution with hydroxyl groups on the surface.

[0063] (4) 1.5 g of dimethyldimethoxysilane (DMDMS) was added as a capping agent to the TMB@PEO-PPO-PEO@SiO2 composite nanomaterial solution prepared in step (3), and stirred at 1500 r / min for 36 h to obtain a TMB@PEO-PPO-PEO@SiO2 organic-inorganic hybrid composite material solution with abundant methyl groups on the surface.

[0064] (5) The composite material solution in step (4) was allowed to stand and evaporate at room temperature for 48 h to remove 1,3,5-trimethylbenzene from the composite material solution. Then the composite material solution was centrifuged at 80,000 r / min for 10 min, followed by washing with water 3 times and washing with 95% ethanol 3 times. Finally, the obtained sample was refluxed in anhydrous ethanol at 90 °C for 0.5 h to remove the block copolymer. Finally, it was dried to obtain a monoporous silica nanobowl.

[0065] The microstructure of the monoporous silica nanobowls prepared in Example 5 was observed using a scanning electron microscope (SEM), and the results are as follows: Figure 7 As shown, from Figure 7 It can be seen that the prepared ultra-small bowl-shaped particles have a particle size of 20-40 nm and a specific surface area of ​​715 m². 2 / g, the pore size of the recessed mesopores is 25-30 nm, wherein the pore size of the recessed mesopores is larger than that of Example 1, and the specific surface area is larger than that of Example 1.

[0066] Example 6: The overall method is the same as that of Example 1, except that in step (5), the composite material solution of step (4) is allowed to stand at 60 °C for 24 h to evaporate.

[0067] The microstructure of the monoporous silica nanobowls prepared in Example 5 was observed using a scanning electron microscope (SEM), and the results are as follows: Figure 10 As shown, from Figure 10 It can be seen that the prepared bowl-shaped particles have a particle size of 90-110 nm and a specific surface area of ​​215 m². 2 / g, the pore size of the recessed mesopores is 45-55 nm. The pore size of the recessed mesopores is larger than that of Example 1, while the specific surface area is smaller, indicating that increased temperature accelerates the diffusion of TMB molecules and increases shrinkage stress. With increasing temperature, the thermal kinetic energy of the molecules increases, making it easier for the molecules to overcome limiting factors such as intermolecular forces. Furthermore, the methyl groups introduced by DMDMS exhibit enhanced reactivity at high temperatures, strengthening their hydrophobic interactions with the aqueous phase and promoting more complete migration of the organic oligomers at the bottom of the shell to the oil phase. This directional migration leads to a thinner shell on the aqueous side and a thicker shell on the oil side, causing the center of gravity of the particles to shift towards the oil. To maintain interfacial balance, the edges of the aqueous shell are forced to expand outwards, resulting in an overall increase in particle size and further expansion of the recessed structure. Therefore, increasing the volatilization temperature changes the size of the bowl-shaped particles and the size of the recessed mesopores.

[0068] Experiment: The monoporous silica nanobowl material prepared in Example 1 was coated onto a zinc sheet. Then, one drop of water was dropped onto both the zinc sheet coated with the material from Example 1 and the bare zinc sheet without coating. The hydrophobic angle was then measured using a contact angle meter. The results are shown in [Figure 1]. Figure 8 ,from Figure 8 As can be seen from (a), the hydrophobic angle of the zinc sheet coated with the material of Example 1 is 131.57°; from Figure 8 As can be seen in (b), the hydrophobic angle of the bare zinc sheet without coating is 79.35°; clearly, the single-mesoporous silica nanobowl material prepared by the present invention has good hydrophobic properties.

[0069] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0070] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a single-mesoporous silica nanobowl, characterized in that: It includes the following steps: (1) Preparation of single micelle aqueous solution: The block copolymer F127 and the hydrochloric acid aqueous solution with a concentration of 1-5 mol / L are mixed evenly at a mass ratio of 1:30-100 to form a single micelle aqueous solution; (2) Preparation of TMB@PEO-PPO-PEO single micelle composite solution: 1,3,5-trimethylbenzene is mixed with the single micelle aqueous solution prepared in step (1) and stirred for 14-36 h at a stirring speed of 800-1500 r / min to obtain TMB@PEO-PPO-PEO single micelle composite solution. (3) Preparation of TMB@PEO-PPO-PEO@SiO2 composite nanomaterial solution: Add tetraethyl orthosilicate to the TMB@PEO-PPO-PEO single micelle composite solution prepared in step (2), and stir at 800-1500 r / min for 5-24 h to obtain TMB@PEO-PPO-PEO@SiO2 composite nanomaterial solution; (4) Preparation of composite material solution: Dimethyldimethoxysilane is added to the TMB@PEO-PPO-PEO@SiO2 composite nanomaterial solution prepared in step (3), and stirred at 800-1500 r / min for 12-36 h to obtain the composite material solution; (5) Preparation of monoporous silica nanobowls: The composite material solution in step (4) is allowed to stand and evaporate to remove 1,3,5-trimethylbenzene from the composite material solution, followed by centrifugation and washing; then the obtained sample is refluxed in anhydrous ethanol to remove the block copolymer, and finally dried to obtain monoporous silica nanobowls. The mesoporous silica nanobowls have a hollow structure, with a particle size of 20-40 nm and a specific surface area of ​​500-800 m². 2 / g, the pore size of the recessed pores on the surface of the monoporous silica nanobowl is 10-25 nm.

2. The method for preparing a single-mesoporous silica nanobowl according to claim 1, characterized in that, The mass ratio of 1,3,5-trimethylbenzene in step (2) to block copolymer F127 in step (1) is 1:0.33-10.

3. The method for preparing a single-mesoporous silica nanobowl according to claim 1, characterized in that, The mass ratio of the tetraethyl orthosilicate in step (3) to the block copolymer F127 in step (1) is 1:0.33-10.

4. The method for preparing a single-mesoporous silica nanobowl according to claim 1, characterized in that, The mass ratio of the dimethyldimethoxysilane in step (4) to the block copolymer F127 in step (1) is 1:0.17-5.

5. The method for preparing a single-mesoporous silica nanobowl according to claim 1, characterized in that, In step (5), allow the mixture to stand at 23-60℃ for 12-48 hours to evaporate.

6. The method for preparing a single-mesoporous silica nanobowl according to claim 1, characterized in that, In step (5), the centrifugation speed is 30,000-80,000 r / min and the centrifugation time is 10-30 min.

7. The method for preparing a single-mesoporous silica nanobowl according to claim 1, characterized in that, The washing conditions in step (5) are: first, use distilled water and wash 3 times, then use a 95% ethanol solution and wash 3 times.

8. A method for preparing a single-mesoporous silica nanobowl according to claim 1, characterized in that, The reflux temperature in step (5) is 50-90 ℃ and the reflux time is 0.5-5 h.

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