Mono-mesoporous silica nano bowl and preparation method thereof

Abstract

The invention is applicable to the technical field of nano materials, and particularly discloses a single-mesoporous silica nano bowl and a preparation method thereof.The single-mesoporous silica nano bowl is of a hollow structure, the particle size of the single-mesoporous silica nano bowl is 20-40 nm, the specific surface area of the single-mesoporous silica nano bowl is 500-800 m < 2 > / g, and the size of an opening in the surface of the single-mesoporous silica nano bowl is 10-25 nm; the preparation method comprises the following steps: (1) preparing a single micelle aqueous solution; (2) preparing a TMB-coated PEO (Polyethylene Oxide)-PPO (Polyphenylene Oxide)-PEO (Polyethylene Oxide) single micelle composite solution; (3) preparing a TMB (at) PEO (Polyethylene Oxide)-PPO (Polyphenylene Oxide)-PEO (at) SiO2 composite nano material solution; (4) preparing a composite material solution; and (5) preparing the single mesoporous silicon dioxide nano bowl. The preparation method has the beneficial effects that the prepared single-mesoporous silicon dioxide nano bowl has ultra-small and uniform size, unique open pore channels and a large number of surface micropores, so that the specific surface area of the material is greatly increased, active sites of chemical reaction are increased, and the surface of the single-mesoporous silicon dioxide nano bowl contains rich methyl groups, so that the material has good hydrophobic performance.

Description

Technical Field

[0001] The present invention relates to the technical field of nanomaterials, and more specifically, it relates to a single mesoporous silica nanobowl and a preparation method thereof. Background Art

[0002] Bowl-shaped materials are often widely used in research fields such as energy storage, adsorption, catalysis, energy, and biomedicine due to their many excellent properties, such as high active surface interfaces, large pore volumes, unique pore structures, unobstructed mass transfer channels, etc. The morphological structures obtained by synthesizing bowl-shaped materials using traditional strategies such as template-free methods, hard template methods, and nanoemulsion methods are often uncontrollable. This uncontrollability makes their quantity, size, pore diameter, and thickness extremely non-uniform, and even causes irregular aggregation and severe deformation of nanoparticles. Moreover, most of them have few mesoporous structures and are too large in size, usually at the micron level, which to a certain extent limits their practical applications. For example, the patent number CN202110263736.8 discloses a preparation method of silica nanobowls, and the size of the prepared silica nanobowls is about 300 nm. So far, the work of synthesizing ultra-small single mesoporous bowl-shaped nanoparticles has not been reported. Summary of the Invention

[0003] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a single mesoporous silica nanobowl and a preparation method thereof. The single mesoporous silica nanobowl and the preparation method thereof provided by the present invention use a stable single micelle-assisted interfacial 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 have ultra-small and uniform sizes, unique open pore channels, and a large number of surface micropores, which greatly improve the specific surface area of the material, increase the active sites of chemical reactions, and the surface thereof contains rich methyl groups, making the material have superhydrophobicity and corrosion resistance.

[0004] To achieve the above purpose, the present invention provides the following technical solutions in one aspect: A single mesoporous silica nanobowl, the single mesoporous silica nanobowl has a hollow structure, the particle size of the single mesoporous silica nanobowl is 20 - 40 nm, the specific surface area is 500 - 800 m 2 / g, and the size of the concave pores on the surface of the single mesoporous silica nanobowl is 10 - 25 nm.

[0005] The present invention provides the following technical solutions in another aspect: A preparation method of a single mesoporous silica nanobowl, which includes the following steps: (1) Mix the block copolymer F127 (PEO-PPO-PEO) with an aqueous hydrochloric acid solution with a concentration of 1-5 mol / L in a mass ratio of 1:30-100 and mix evenly. The hydrophobic PPO end automatically aggregates inside because it is insoluble in the aqueous hydrochloric acid solution, and the hydrophilic PEO end is distributed on the outer layer because of its good compatibility with the aqueous hydrochloric acid solution, forming an aqueous solution of spherical single micelles with a bilayer structure; (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 oil-phase TMB will enter the hydrophobic PPO region inside the aqueous solution of single micelles, thus swelling the polymer single micelles to obtain a TMB@PEO-PPO-PEO single micelle composite solution; (3) Add tetraethyl orthosilicate (TEOS) to the TMB@PEO-PPO-PEO single micelle composite solution prepared in step (2) and stir at a speed of 800-1500 r / min for 5-24 h. After adding tetraethyl orthosilicate, the silica precursor can interact with the hydrophilic polyethylene oxide (PEO) segment of the 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 a hydroxyl group on the surface is obtained; The reaction chemical formula of step (3) is as follows:

[0006] (4) Add dimethyldimethoxysilane (DMDMS) as a capping agent to the TMB@PEO-PPO-PEO@SiO2 composite nanomaterial solution prepared in step (3) and stir at a speed of 800-1500 r / min for 12-36 h to obtain a TMB@PEO-PPO-PEO@SiO2 organic-inorganic hybrid composite material solution with a rich methyl group on the surface; The reaction chemical formula of step (4) is as follows:

[0007] It can be seen from the above reaction chemical formula that most of the hydroxyl groups on the surface of the composite nanomaterial are changed to methyl groups. The methyl end shows hydrophobicity and the hydroxyl end shows hydrophilicity. Furthermore, the composite nanomaterial shows a greater degree of hydrophobicity.

[0008] (5) Let the composite material solution in step (4) stand and volatilize to remove 1,3,5-trimethylbenzene in the composite material solution, then centrifuge and wash; then reflux the obtained sample in absolute ethanol to remove the block copolymer, and finally dry to obtain single mesoporous silica nanobowls.

[0009] During the static process, the hydrophobic particles spontaneously migrate towards the biphasic interface, minimizing the interfacial energy of the system. In addition, the presence of surface methyl groups increases the steric hindrance between the particles, preventing aggregation and maintaining a monolayer array at the interface. This array is a key prerequisite for achieving directional depression during the evaporation process. Subsequently, during the evaporation process, the TMB molecules in the upper oil phase preferentially evaporate. As evaporation progresses, the liquid level drops to the critical level, and the TMB within the micelle core begins to diffuse outwards. At this stage, the volume of the TMB molecules within the silica shell gradually decreases, driving the silica particles to rise towards the oil phase. At the same time, the reduction of TMB causes the contraction of the internal F127 micelles (elastic extrusion of the PPO segments). Meanwhile, as the organic phase of TMB decreases, the hydrophobic oligomers at the bottom of the silica shell migrate upwards, thinning the silica shell in the aqueous phase. Therefore, due to the compression of water on the hydrophobic shell and the contraction tension of the micelles, the soft silica shell concaves upwards in the aqueous phase, ultimately forming a single mesoporous nanoparticle in the shape of a concave bowl. The specific mechanism process is shown in Figure 9 .

[0010] 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.

[0011] Furthermore, the mass ratio of the tetraethyl orthosilicate in step (3) to the block copolymer F127 in step (1) is 1:0.33 - 10.

[0012] Furthermore, the mass ratio of the dimethyldimethoxysilane in step (4) to the block copolymer F127 in step (1) is 1:0.17 - 5.

[0013] Furthermore, in step (5), it is left to stand and evaporate at 23 - 60 °C for 12 - 48 h.

[0014] Furthermore, the centrifugation speed in step (5) is 30000 - 80000 r / min, and the centrifugation time is 10 - 30 min.

[0015] Furthermore, the washing conditions in step (5) are to first use distilled water for 3 washing times, and then use an ethanol solution with a concentration of 95% for 3 washing times.

[0016] Furthermore, the reflux temperature in step (5) is 50 - 90 °C, and the reflux time is 0.5 - 5 h.

[0017] The advantages of the present invention are: 1. The present invention discloses a single mesoporous silica nanobowl and a preparation method thereof. By using a method of stable single micelle-assisted interfacial assembly, ultrasmall single mesoporous silica nanobowls are synthesized, solving the problem of synthesizing ultrasmall asymmetric hollow mesoporous structure materials. The prepared single mesoporous silica nanobowls have ultrasmall and uniform sizes, unique open pore channels, and a large number of surface micropores, greatly increasing the specific surface area of the material and the active sites for chemical reactions.

[0018] 2. The present invention discloses a single mesoporous silica nanobowl with a surface opening size of about 17 nm, a particle size of about 32 nm, and a specific surface area as high as 519 m 2 / g, having excellent dispersibility and uniformity, and its surface contains abundant methyl groups, making the material have good hydrophobic properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a scanning electron microscope image of the single mesoporous silica nanobowl prepared in Example 1 of the present invention.

[0020] Figure 2 It is a transmission electron microscope image of the single mesoporous silica nanobowl prepared in Example 1 of the present invention.

[0021] Figure 3 It is an infrared test spectrum of the single mesoporous silica nanobowl prepared in Example 1 of the present invention.

[0022] Figure 4 It is a scanning electron microscope image of the single mesoporous silica nanobowl prepared in Example 2 of the present invention.

[0023] Figure 5 It is a scanning electron microscope image of the single mesoporous silica nanobowl prepared in Example 3 of the present invention.

[0024] Figure 6 It is a scanning electron microscope image of the single mesoporous silica nanobowl prepared in Example 4 of the present invention.

[0025] Figure 7 It is a scanning electron microscope image of the single mesoporous silica nanobowl prepared in Example 5 of the present invention.

[0026] Figure 8 It is a hydrophobic angle diagram of the single mesoporous silica nanobowl prepared in Example 1 of the present invention coated with a bare zinc sheet and a bare zinc sheet.

[0027] Figure 9 It is a mechanism process diagram for preparing the single mesoporous silica nanobowl of the present invention.

[0028] Figure 10This is the scanning electron microscope image of the single mesoporous silica nanobowl prepared in Example 6 of the present invention. Detailed implementation manners

[0029] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments may be combined with each other. The present invention will be described in detail below with reference to the drawings and in combination with the embodiments.

[0030] It should be pointed out that unless otherwise specified, all technical and scientific terms used in the present application have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present application belongs.

[0031] In the present invention, without contrary description, the orientations such as "upper, lower" are generally in the directions shown in the drawings, or in the vertical, perpendicular or gravitational directions; similarly, for the convenience of understanding and description, "left, right" are generally in the left and right shown in the drawings; "inside, outside" refer to the inside and outside relative to the contours of the respective components, but the above orientation terms do not limit the present invention.

[0032] Example 1: A preparation method of a single mesoporous silica nanobowl, which comprises the following steps: (1) Mix 0.3 g of block copolymer F127 (PEO-PPO-PEO) uniformly with 15 mL of hydrochloric acid aqueous solution with a concentration of 2 mol / L to form a spherical single micelle aqueous solution with a bilayer structure; (2) Add 0.3 g of 1,3,5-trimethylbenzene (TMB) to the single micelle aqueous solution prepared in step (1), mix and stir for 14 h, and the stirring speed is 1400 r / min to obtain a TMB@PEO-PPO-PEO single micelle composite solution; (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 a speed of 1400 r / min for 8 h to obtain a core-shell structure TMB@PEO-PPO-PEO@SiO2 composite nanomaterial solution with a hydroxyl group on the surface; (4) Add 0.1 g of dimethyldimethoxysilane (DMDMS) as a capping agent to the TMB@PEO-PPO-PEO@SiO2 composite nanomaterial solution prepared in step (3), and stir at a speed of 1400 r / min for 24 h to obtain a TMB@PEO-PPO-PEO@SiO2 organic-inorganic hybrid composite material solution with rich methyl groups on the surface; (5) The composite material solution in step (4) is left to stand and volatilize at room temperature for 24 h to remove 1,3,5-trimethylbenzene in the composite material solution. Subsequently, the composite material solution is centrifuged at a speed of 80000 r / min for 15 min, then washed with water 3 times and washed with 95% ethanol 3 times; finally, the obtained sample is refluxed in absolute ethanol at 80 °C for 1 h to remove the block copolymer, and finally a single mesoporous silica nanobowl is obtained after drying.

[0033] The microstructure of the single mesoporous silica nanobowl prepared in Example 1 was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results are as Figure 1 and Figure 2 shown. The size, thickness and pore diameter of the single mesoporous silica nanobowl prepared in this example are uniform; it can be seen from Figure 1 that the particle size of the prepared ultra-small bowl-shaped particles is all in the range of 20 - 40 nm, the specific surface area is 519 m 2 / g, and it shows good dispersibility. A concave mesopore can be found at the center of each particle. In addition, a considerable number of nanoparticles were successfully observed with the bowl mouth facing away from the observation field of view, mainly showing the back (convex part) of the bowl. It can be seen from Figure 2 that the overall morphology of the particles is a hollow bowl-shaped structure. After measurement, the thickness of the hollow shell layer is about 7 nm, and the pore diameter of the concave mesopore is about 17 nm.

[0034] The single mesoporous silica nanobowl prepared in Example 1 was used to prepare a sample by the pressing method for infrared spectroscopy test. The results are as Figure 3 shown. It can be seen from Figure 3 the FT-IR spectrum that an absorption band appears at 2960 cm −1 which can be attributed to the vibration of the C−H bond in the -CH3 group, indicating the presence of a methane-bridged framework.

[0035] Example 2: The overall method is the same as that of Example 1, except that the addition amount of 1,3,5-trimethylbenzene (TMB) in step (2) is 0.5 g.

[0036] The microstructure of the single mesoporous silica nanobowl prepared in Example 2 was observed by scanning electron microscopy (SEM). The results are as Figure 4 shown. It can be seen from Figure 4 that the particle size of the prepared ultra-small bowl-shaped particles is all in the range of 20 - 40 nm, the specific surface area is 612 m 2 / g. The pore diameter of the concave mesopores is about 22 - 25 nm, which is larger than that in Example 1. This is because when the amount of TMB increases, more TMB molecules will occupy the space inside the mesopores, thus expanding the size of the mesopores.

[0037] Example 3: The overall method is the same as that in Example 1, except that the addition amount of tetraethyl orthosilicate (TEOS) in step (3) is 0.5 g.

[0038] The microstructure of the single mesoporous silica nanobowls prepared in Example 3 was observed by scanning electron microscopy (SEM), and the results are as Figure 5 shown. It can be seen from Figure 5 that the prepared ultra-small bowl-shaped particles have particle sizes all within 20 - 40 nm, the specific surface area is 510 m 2 / g, and the pore diameter of the concave mesopores is 12 - 17 nm. The pore diameter of the concave mesopores is smaller than that in Example 1, and obvious agglomeration phenomenon is shown as a whole, indicating that the precursors are over-aggregated and react in local areas, and then agglomerated silica is formed. More silica accumulates around the template, which will fill the space that could originally form larger mesopores.

[0039] Example 4: A method for preparing single mesoporous silica nanobowls, which includes the following steps: (1) Mix 0.3 g of block copolymer F127 (PEO-PPO-PEO) with 9 mL of 1 mol / L hydrochloric acid aqueous solution evenly to form a spherical single micelle aqueous solution with a bilayer structure; (2) Add 0.1 g of 1,3,5-trimethylbenzene (TMB) to the single micelle aqueous solution prepared in step (1), mix and stir for 25 h at a stirring speed of 800 r / min to obtain a TMB@PEO-PPO-PEO single micelle composite solution; (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 a speed of 800 r / min for 5 h to obtain a core-shell structure TMB@PEO-PPO-PEO@SiO2 composite nanomaterial solution with a hydroxyl group on the surface; (4) Add 0.05 g of dimethyldimethoxysilane (DMDMS) as a capping agent to the TMB@PEO-PPO-PEO@SiO2 composite nanomaterial solution prepared in step (3), and stir at a speed of 800 r / min for 12 h to obtain a TMB@PEO-PPO-PEO@SiO2 organic-inorganic hybrid composite material solution with rich methyl groups on the surface; (5) The composite material solution in step (4) is left to stand and volatilize at room temperature for 12 h to remove 1,3,5-trimethylbenzene in the composite material solution. Subsequently, the composite material solution is centrifuged at a speed of 30,000 r / min for 30 min (if the rotation speed is low, the required time will be longer). Then, it is washed with water three times and washed with 95% ethanol three times. Finally, the obtained sample is refluxed in absolute ethanol at 50 °C for 5 h (if the temperature is low, the required time will be longer) to remove the block copolymer. Finally, the single mesoporous silica nanobowls are obtained after drying.

[0040] The microstructure of the single mesoporous silica nanobowls prepared in Example 4 was observed by scanning electron microscopy (SEM). The results are as Figure 6 shown. It can be seen from Figure 6 that the prepared ultra-small bowl-shaped particles have a particle size of 20 - 40 nm, a specific surface area of 452 m 2 / g, and the pore diameter of the concave mesopores is 10 - 15 nm. The pore diameter of the concave mesopores is smaller than that in Example 1, which in turn leads to a smaller specific surface area compared to Example 1.

[0041] Example 5: A method for preparing single mesoporous silica nanobowls, which includes the following steps: (1) 0.3 g of block copolymer F127 (PEO-PPO-PEO) is mixed evenly with 30 mL of 5 mol / L hydrochloric acid aqueous solution to form a spherical single micelle aqueous solution with a bilayer structure; (2) 3 g of 1,3,5-trimethylbenzene (TMB) is added to the single micelle aqueous solution prepared in step (1), and the mixture is stirred for 36 h at a stirring speed of 1500 r / min to obtain a TMB@PEO-PPO-PEO single micelle composite solution; (3) 3 g of tetraethyl orthosilicate (TEOS) is added to the TMB@PEO-PPO-PEO single micelle composite solution prepared in step (2), and the mixture is stirred at a speed of 1500 r / min for 24 h to obtain a core-shell structure TMB@PEO-PPO-PEO@SiO2 composite nanomaterial solution with a hydroxyl group on the surface; (4) 1.5 g of dimethyldimethoxysilane (DMDMS) is added as a capping agent to the TMB@PEO-PPO-PEO@SiO2 composite nanomaterial solution prepared in step (3), and the mixture is stirred at a speed of 1500 r / min for 36 h to obtain a TMB@PEO-PPO-PEO@SiO2 organic-inorganic hybrid composite material solution with a rich methyl group on the surface; (5) The composite material solution in step (4) is left to stand and volatilize at room temperature for 48 h to remove 1,3,5-trimethylbenzene in the composite material solution. Subsequently, the composite material solution is centrifuged at a speed of 80000 r / min for 10 min, then washed with water 3 times and washed with ethanol with a concentration of 95% 3 times. Finally, the obtained sample is refluxed in absolute ethanol at 90 °C for 0.5 h to remove the block copolymer, and finally, single mesoporous silica nanobowls are obtained after drying.

[0042] The microstructure of the single mesoporous silica nanobowls prepared in Example 5 was observed by scanning electron microscopy (SEM). The results are as Figure 7 shown. It can be seen from Figure 7 that the prepared ultra-small bowl-shaped particles have particle sizes all within 20 - 40 nm, the specific surface area is 715 m 2 / g, and the pore diameter of the concave mesopores is within 25 - 30 nm. Among them, the pore diameter of the concave mesopores is larger than that in Example 1, and the specific surface area is larger than that in Example 1.

[0043] Example 6: The overall method is the same as that in Example 1, except that in step (5), the composite material solution in step (4) is left to stand and volatilize at 60 °C for 24 h.

[0044] The microstructure of the single mesoporous silica nanobowls prepared in Example 5 was observed by scanning electron microscopy (SEM). The results are as Figure 10 shown. It can be seen from Figure 10 that the prepared bowl-shaped particles have particle sizes all within 90 - 110 nm, the specific surface area is 215 m 2 / g, and the pore diameter of the concave mesopores is within 45 - 55 nm. Among them, the pore diameter of the concave mesopores is larger than that in Example 1, and the specific surface area is smaller than that in Example 1, indicating that the increase in temperature accelerates the diffusion of TMB molecules and increases the shrinkage stress. As the temperature increases, the thermal motion energy of molecules increases, which makes it easier for molecules to overcome limiting factors such as intermolecular forces. In addition, the methyl groups introduced by DMDMS show enhanced reactivity at high temperatures, enhancing their hydrophobic interaction with the aqueous phase and promoting the more complete migration of the organic oligomers at the bottom of the shell to the oil phase. This directional migration causes the shell on the aqueous phase side to become thinner and the shell on the oil phase side to become thicker, resulting in the center of gravity of the particles moving towards the oil direction. To maintain the interface balance, the edge of the shell on the aqueous phase side is forced to expand outwards, resulting in an increase in the overall particle size and a further expansion of the concave structure. Therefore, the increase in the volatilization temperature will change the size of the bowl-shaped particles and the size of the concave mesopores.

[0045] Experiment: Coat the single mesoporous silica nanobowl material prepared in Example 1 onto a zinc sheet. Then, drop 1 drop of water onto the zinc sheet coated with the material of Example 1 and the bare zinc sheet without coating respectively. Next, use a contact angle tester to detect the hydrophobic angle. The results are shown in Figure 8 , and it can be seen from Figure 8 (a) that the hydrophobic angle of the zinc sheet coated with the material of Example 1 is 131.57°; it can be seen from Figure 8 (b) that the hydrophobic angle of the bare zinc sheet without coating is 79.35°; obviously, the single mesoporous silica nanobowl material prepared by the present invention has good hydrophobic performance.

[0046] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, various modifications and changes can be made to the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

[0047] The above is only the preferred implementation mode of the present invention. The protection scope of the present invention is not limited to the above embodiments. All technical solutions falling within the idea of the present invention belong to the protection scope of the present invention. It should be pointed out that for those of ordinary skill in the art, several improvements and refinements made without departing from the principle of the present invention should also be regarded as within the protection scope of the present invention.

Claims

1. A single mesoporous silica nanobowl, characterized in that: The single mesoporous silica nanobowl has a hollow structure, the particle size of the single mesoporous silica nanobowl is 20-40 nm, the specific surface area is 500-800 m 2 / g, and the pore diameter of the concave pores on the surface of the single mesoporous silica nanobowl is 10-25 nm.

2. The preparation method of a single mesoporous silica nanobowl according to claim 1, characterized in that: It includes the following steps: (1) Prepare an aqueous solution of single micelles: Mix the block copolymer F127 and an aqueous hydrochloric acid solution with a concentration of 1 - 5 mol / L evenly at a mass ratio of 1:30 - 100 to form an aqueous solution of single micelles; (2) Prepare a TMB@PEO-PPO-PEO single micelle composite solution: Mix 1,3,5-trimethylbenzene 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 to obtain a TMB@PEO-PPO-PEO single micelle composite solution; (3) Prepare a 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 a speed of 800 - 1500 r / min for 5 - 24 h to obtain a TMB@PEO-PPO-PEO@SiO2 composite nanomaterial solution; (4) Prepare a composite material solution: Add dimethyldimethoxysilane to the TMB@PEO-PPO-PEO@SiO2 composite nanomaterial solution prepared in step (3) and stir at a speed of 800 - 1500 r / min for 12 - 36 h to obtain a composite material solution; (5) Prepare single mesoporous silica nanobowls: Let the composite material solution in step (4) stand and volatilize to remove 1,3,5-trimethylbenzene in the composite material solution, then centrifuge and wash; then reflux the obtained sample in absolute ethanol to remove the block copolymer, and finally dry to obtain single mesoporous silica nanobowls.

3. The preparation method of a single mesoporous silica nanobowl according to claim 2, wherein, 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.

4. The preparation method of a single mesoporous silica nanobowl according to claim 2, 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.

5. The preparation method of a single mesoporous silica nanobowl according to claim 2, 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.

6. The preparation method of a single mesoporous silica nanobowl according to claim 2, characterized in that, In step (5), let it stand and volatilize at 23 - 60 °C for 12 - 48 h.

7. The preparation method of a single mesoporous silica nanobowl according to claim 2, characterized in that, The centrifugation speed in step (5) is 30000 - 80000 r / min, and the centrifugation time is 10 - 30 min.

8. The preparation method of a single mesoporous silica nanobowl according to claim 2, characterized in that, The washing conditions in step (5) are to first use distilled water for 3 times of washing, and then use an ethanol solution with a concentration of 95% for 3 times of washing.

9. The preparation method of a single mesoporous silica nanobowl according to claim 2, characterized in that, The reflux temperature in step (5) is 50 - 90 °C, and the reflux time is 0.5 - 5 h.

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