Preparation method of double-hollow multi-shell H-SiO2-coated SnO2-coated H-SiO2-coated SnO2 core-shell microspheres
The preparation of double hollow multi-shell H-SiO2@SnO2@H-SiO2@SnO2 core-shell microspheres by hard template method combined with chemical coating method, solving the problems of complex preparation process and low yield in the prior art, achieving high efficiency, Controllable microsphere preparation and high emissivity have expanded its prospects for applications in multiple fields.
Patent Information
- Application Number
- CN202411443251.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-16
- Publication Date
- 2024-12-31
AI Technical Summary
In the prior art, the preparation method of hollow multi-shell core-shell microspheres has problems such as difficult to control particle size and dispersion, high equipment cost, low yield and cumbersome operation, especially the preparation of double hollow multi-shell structures is relatively small. Limits its application in high-performance chip packaging and thermally radiant materials.
Using the hard template method combined with chemical coating method, PS microspheres are used as templates, SiO2 and SnO2 are alternately coated under low temperature water bath conditions, and a double hollow multi-shelled layer H-SiO2@SnO2@H-SiO2@ SnO2 core-shell microspheres.
It has achieved good monodispersity, uniform particle size and controllable shell thickness of microspheres, improved emissivity, simplified the preparation process, reduced costs, and was suitable for large-scale production, expanding its thermal radiation, drug sustained release, and catalysis. Applications in other fields.
Smart Images
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Abstract
Description
Technical Field
[0001] The invention relates to a method for preparing a hollow multi-shell structure material microsphere, in particular to a method for preparing a double hollow multi-shell H-SiO2@SnO2@H-SiO2@SnO2 core-shell microsphere. Background Art
[0002] In order to meet the needs of high-performance chips in electronic packaging and thermal radiation, it is of great practical significance to develop new materials with both low dielectric constant and high infrared emissivity. As a chip packaging material with a low dielectric constant, hollow SiO2 microspheres (H-SiO2) have limited emissivity, which limits the cooling of the chip through radiation heat dissipation. Metal oxides such as SnO2 have high infrared emissivity and have become one of the research hotspots of radiative cooling.
[0003] Hollow multi-shell structure materials, due to the shell interface effect of different materials and the hollow structure, can destroy the continuity of the heat transfer path, effectively reduce the thermal conductivity of the material, and improve its emissivity, which can be widely used in thermal radiation materials. In addition, the hollow multi-shell structure has the advantages of large specific surface area, low density and short material transmission path, and has broad application prospects in the fields of drug sustained release, catalysis, sensors, nanoreactors, etc. Therefore, SiO2 and SnO2 are compounded and designed into hollow multi-shell core-shell microspheres, which have a higher emissivity.
[0004] At present, the preparation of hollow microspheres is mainly based on the hard template method and the soft template method. The soft template method has certain advantages in terms of preparation cost, synthesis steps and expansion of hollowness, but the soft template method is not easy to control the morphology of hollow microspheres, and its dispersibility and particle size distribution are poor. The hard template method has received widespread attention due to its controllable morphology, uniform product particle size, and good dispersibility.
[0005] The preparation of hollow multi-shell core-shell microspheres is generally prepared by a hard template method combined with a hydrothermal synthesis method. Due to the general dispersibility of the hydrothermal synthesis product, the particle size and shell thickness of the core-shell microspheres are difficult to control, and the high equipment cost and low product yield have limited large-scale use. The preparation of double hollow multi-shell core-shell microspheres is rare, and based on the hard template method, the removal of the structural core requires at least two steps, which is cumbersome and time-consuming. Summary of the invention
[0006] The purpose of the present invention is to provide a method for preparing double hollow multi-shell H-SiO2@SnO2@H-SiO2@SnO2 core-shell microspheres. The method is based on a hard template method, takes PS microspheres as templates, and adopts a chemical coating method. In a low-temperature water bath, SiO2 and SnO2 are alternately coated. After a one-step heat treatment, double hollow multi-shell H-SiO2@SnO2@H-SiO2@SnO2 core-shell microspheres are prepared, and their emissivity is relatively improved.
[0007] The objective of the present invention is achieved through the following technical solutions:
[0008] A method for preparing double hollow multi-shell H-SiO2@SnO2@H-SiO2@SnO2 core-shell microspheres, the method comprising the following preparation steps:
[0009] (1) First, PS microspheres prepared by soap-free emulsion polymerization are modified with PVP, and then dispersed into an ethanol solution to form a uniform PS microsphere ethanol dispersion, and then the ethanol dispersion is transferred to a three-necked flask, mechanically stirred, and then ammonia water is added, and the three-necked flask is heated to 50-80°C, TEOS is diluted with ethanol solution, and then the dilution is added to the three-necked flask using a constant pressure dropping funnel. After the dropping is completed, the reaction is continued for 5h-12h. After the reaction is completed, the product is centrifuged, and the precipitate is ultrasonically washed three times with water and ethanol, and finally the product is dried at 50°C-80°C. Dry in an oven at 0°C for 8h to 24h to obtain PS@SiO2 microsphere powder; the concentration of the PS microsphere ethanol dispersion in the above step (1) is 1.00mg / mL to 800mg / mL (PS microspheres are modified with PVP according to the PVP modification method in step (3)), the amount of ethanol added is 20mL to 2000mL, and the concentration of ammonia water is 0.02mol / L to 1.2mol / L; the concentration of TEOS after dilution with ethanol solution is 0.1mol / L to 2mol / L, and the amount of ethanol used is 10mL to 500mL;
[0010] (2) The PS@SiO2 core-shell microsphere powder obtained in step (1) is ultrasonically dispersed in 15 mL to 2500 mL of deionized water to form a uniform PS@SiO2 core-shell microsphere dispersion, and the dispersion is transferred to a three-necked flask and stirred at a constant speed, and Na2SnO3·4H2O is dissolved in a mixture of water and ethanol in a volume ratio of 1:1 to form a Na2SnO3·4H2O mixed solution, and the Na2SnO3 mixed solution is added to the three-necked flask through a constant pressure dropping funnel, and the reaction is carried out at 30°C to 90°C for 2h to 7h. After the reaction is completed, The product was centrifuged, and the obtained precipitate was ultrasonically cleaned three times with water and ethanol respectively. Finally, the obtained product was dried in an oven at 50°C to 80°C for 8h to 24h to obtain PS@SiO2@SnO2 core-shell microsphere powder; the concentration of the PS@SiO2 core-shell microsphere dispersion in the above step (2) was 1.00mg / mL to 800mg / mL; the mass ratio of Na2SnO3·4H2O to PS@SiO2 core-shell microspheres was 0.2:1 to 8:1, and the amount of deionized water in the Na2SnO3 mixed solution was 10mL to 1000mL;
[0011] (3) The PS@SiO2@SnO2 core-shell microsphere powder obtained in step (2) is first modified with PVP, and ultrasonically dispersed in 15 mL to 2500 mL of deionized water to form a PS@SiO2@SnO2 core-shell microsphere dispersion, and then the dispersion is transferred to a three-necked flask and stirred, and PVP is added. The reaction is carried out at 25°C to 35°C for 12 h to 24 h. After the reaction is completed, the product is centrifuged, and the obtained precipitate is ultrasonically cleaned three times with water and ethanol, respectively. That is, the PVP modification is completed, and the obtained product is ultrasonically dispersed with 15 mL to 2500 mL of ethanol solution to form a uniform PS@SiO2@SnO2 core-shell microsphere ethanol dispersion, and then the ethanol dispersion is transferred to a reaction vessel and stirred, and ammonia water is added. TEOS is diluted with ethanol solution, and the TEOS ethanol dilution is dripped into the reactor at 25 to 35°C, and stirring is continued after dripping. The reaction was continued for 4 to 24 hours. After the reaction was completed, the product was centrifuged. The precipitate was ultrasonically cleaned three times with water and ethanol respectively. The product was dried in an oven at 50°C to 80°C for 8 to 24 hours to obtain PS@SiO2@SnO2@SiO2 core-shell microsphere powder. The concentration of the PS@SiO2@SnO2 core-shell microsphere dispersion in the above step (3) was 1.00 mg / mL to 500 mg / mL, the concentration of the PS@SiO2@SnO2 core-shell microsphere ethanol dispersion was 1.00 mg / mL to 800 mg / mL, the mass ratio of PVP to PS@SiO2@SnO2 core-shell microsphere was 0.5:1 to 30:1, the concentration of the TEOS ethanol dilution was 0.1 mol / L to 2.0 mol / mL, the amount of ethanol used was 10 mL to 500 mL, and the concentration of ammonia water was 0.1 mol / L to 2.5 mol / L.
[0012] (4) The PS@SiO2@SnO2@SiO2 core-shell microsphere powder obtained in step (3) is ultrasonically dispersed in 15 mL to 2500 mL of deionized water to obtain a PS@SiO2@SnO2@SiO2 core-shell microsphere dispersion, which is transferred to a three-necked flask and stirred. Na2SnO3·4H2O is dissolved in a mixture of deionized water and ethanol in a volume ratio of 1:1 to form a Na2SnO3 mixed solution, which is added to the three-necked flask using a constant pressure dropping funnel, and reacted at 30°C to 90°C for 2h to 7h. After the reaction is completed, the product is centrifuged and the resulting precipitate is washed with deionized water and 4H2O. and ethanol ultrasonic cleaning three times, and finally the product is dried in an oven at 50°C to 80°C for 8h to 24h to obtain PS@SiO2@SnO2@H-SiO2@SnO2 core-shell microsphere powder; the concentration of the PS@SiO2@SnO2@SiO2 core-shell microsphere dispersion in the above step (4) is 1.00mg / mL to 800mg / mL, the mass ratio of Na2SnO3·4H2O to PS@SiO2@SnO2@SiO2 core-shell microsphere is 0.5:1 to 2:1, and the amount of deionized water in the Na2SnO3 mixed solution is 10mL to 1000mL;
[0013] (5) The microsphere powders obtained in the above steps (1), (2), (3) and (4) are placed in magnetic boats respectively, and transferred to a muffle furnace. In an air atmosphere, they are heat treated at 200°C for 0.5h to 1h, and then heated to 400°C to 600°C for 1h to 6h to obtain H-SiO2 microspheres, H-SiO2@SnO2 core-shell microspheres, H-SiO2@SnO2@SiO2 core-shell microspheres, H-SiO2@SnO2@SiO2 core-shell microspheres, and H-SiO2@SnO2@H-SiO2@SnO2 core-shell microspheres. The heating rate of the muffle furnace in the above step (5) is 0.5°C / min to 10°C / min.
[0014] The method for preparing a double hollow multi-shell H-SiO2@SnO2@H-SiO2@SnO2 core-shell microsphere comprises the following steps: in the step (1), firstly dispersing the PVP-modified PS emulsion prepared by soap-free emulsion polymerization into an ethanol solution to form a uniform PS microsphere ethanol dispersion, then transferring the ethanol dispersion into a three-necked flask, mechanically stirring, adding ammonia water, heating the three-necked flask to 55-75° C., diluting TEOS with an ethanol solution, and then adding the dilution into the three-necked flask with a constant pressure dropping funnel. After the dropping is completed, the reaction is continued for 5.5 h to 11.5 h. After the reaction is completed, the product is centrifuged to obtain a precipitate, ultrasonically treating with water and ethanol, respectively. The product was washed three times and dried in an oven at 55°C to 75°C for 8.5h to 23.5h to obtain PS@SiO2 core-shell microsphere powder; the concentration of the PS microsphere ethanol dispersion in the above step (1) was 1.50mg / mL to 799.5mg / mL (PS microspheres were modified with PVP according to the PVP modification method in step (3)), the amount of ethanol added was 25mL to 1995mL, and the concentration of ammonia water was 0.025mol / L to 1.195mol / L; the concentration of TEOS after dilution with ethanol solution was 0.15mol / L to 1.95mol / L, and the amount of ethanol used was 15 to 495mL.
[0015] The preparation method of the double hollow multi-shell H-SiO2@SnO2@H-SiO2@SnO2 core-shell microspheres is as follows: in the above step (2), the PS@SiO2 core-shell microsphere powder obtained in step (1) is ultrasonically dispersed in 20mL to 2495mL of deionized water to form a uniform PS@SiO2 core-shell microsphere dispersion, and the dispersion is transferred to a three-necked flask and stirred at a constant speed, Na2SnO3·4H2O is dissolved in a mixed solution of water and ethanol in a volume ratio of 1:1 to form a Na2SnO3·4H2O mixed solution, and the Na2SnO3 mixed solution is added to the three-necked flask through a constant pressure dropping funnel, and the mixture is stirred at 3°C. The reaction was carried out at 5°C to 85°C for 2.5h to 6.5h. After the reaction, the product was centrifuged, and the precipitate was ultrasonically cleaned three times with water and ethanol respectively. Finally, the product was dried in an oven at 55°C to 75°C for 8.5h to 23.5h to obtain PS@SiO2@SnO2 core-shell microsphere powder. The concentration of the PS@SiO2 core-shell microsphere dispersion in the above step (2) was 1.50mg / mL to 799.5mg / mL. The mass ratio of Na2SnO3·4H2O to PS@SiO2 core-shell microspheres was 0.3:1 to 7.9:1, and the amount of deionized water in the Na2SnO3 mixed solution was 15mL to 995mL.
[0016] The preparation method of the double hollow multi-shell H-SiO2@SnO2@H-SiO2@SnO2 core-shell microspheres is as follows: in the above step (3), the PS@SiO2@SnO2 core-shell microsphere powder obtained in step (2) is firstly subjected to PVP modification, and then ultrasonically dispersed in 20mL to 2495mL deionized water to form a PS@SiO2@SnO2 core-shell microsphere dispersion, and then the dispersion is transferred to a three-necked flask and stirred, and PVP is added, and the reaction is carried out at 26°C to 34°C for 12.5h to 23.5h. After the reaction is completed, the product is centrifuged, and the obtained precipitate is ultrasonically cleaned three times with water and ethanol respectively, that is, the PVP modification is completed, and the obtained product is ultrasonically dispersed with 20mL to 2495mL ethanol solution to form a uniform PS@SiO2@SnO2 core-shell microsphere ethanol dispersion, and then the ethanol dispersion is transferred to a reaction container and stirred, and ammonia water is added, TEOS is diluted with ethanol solution, and the reactor is dripped at 26 to 34°C. After the addition of TEOS ethanol dilution, continue to stir and react for 4.5h to 23.5h. After the reaction is completed, the product is centrifuged, and the obtained precipitate is ultrasonically cleaned three times with water and ethanol respectively. Finally, the obtained product is dried in an oven at 55°C to 75°C for 8.5h to 23.5h to obtain PS@SiO2@SnO2@SiO2 core-shell microsphere powder; the concentration of the PS@SiO2@SnO2 core-shell microsphere dispersion described in the above step (3) is 1.50mg / mL to 495m g / mL, the concentration of PS@SiO2@SnO2 core-shell microsphere ethanol dispersion is 1.50mg / mL~799.5mg / mL, the mass ratio of PVP to PS@SiO2@SnO2 core-shell microspheres is 0.6:1~29.9:1, the concentration of TEOS ethanol dilution is 0.15mol / L~1.95mol / mL, the ethanol usage is 15mL~495mL, and the ammonia concentration is 0.15mol / L~2.45mol / L.
[0017] The preparation method of the double hollow multi-shell H-SiO2@SnO2@H-SiO2@SnO2 core-shell microspheres is as follows: in the above step (4), the PS@SiO2@SnO2@SiO2 core-shell microsphere powder obtained in step (3) is ultrasonically dispersed in 20mL to 2495mL of deionized water to obtain a PS@SiO2@SnO2@SiO2 core-shell microsphere dispersion, the dispersion is transferred to a three-necked flask and stirred, Na2SnO3·4H2O is dissolved in a mixture of deionized water and ethanol in a volume ratio of 1:1 to form a Na2SnO3 mixed solution, which is added to the three-necked flask using a constant pressure dropping funnel and reacted at 35°C to 85°C for 2.5h to 6. 5h, after the reaction is completed, the product is centrifuged, and the obtained precipitate is ultrasonically cleaned three times with deionized water and ethanol respectively, and finally the obtained product is dried in an oven at 55℃~75℃ for 8.5h~23.5h to obtain PS@SiO2@SnO2@H-SiO2@SnO2 core-shell microsphere powder; the concentration of the PS@SiO2@SnO2@SiO2 core-shell microsphere dispersion in the above step (4) is 1.00mg / mL~800mg / mL, the mass ratio of Na2SnO3·4H2O to PS@SiO2@SnO2@SiO2 core-shell microspheres is 0.6:1~1.9:1, and the amount of deionized water in the Na2SnO3 mixed solution is 15mL~995mL.
[0018] The method for preparing double hollow multi-shell H-SiO2@SnO2@H-SiO2@SnO2 core-shell microspheres is as follows: in the above step (5), the microsphere powders obtained in steps (1), (2), (3) and (4) are respectively placed in a magnetic boat and transferred to a muffle furnace, and heat treated at 200°C for 0.6h to 0.9h in an air atmosphere, and then heated to 405°C to 595°C for 1.5h to 5.5h to obtain H-SiO2 microspheres, H-SiO2@SnO2 core-shell microspheres, H-SiO2@SnO2@SiO2 core-shell microspheres, H-SiO2@SnO2@SiO2 core-shell microspheres, and H-SiO2@SnO2@H-SiO2@SnO2 core-shell microspheres; the muffle furnace heating rate in the above step (5) is 1°C / min to 9.5°C / min.
[0019] Advantages and effects of the present invention:
[0020] 1. The present invention uses PS microspheres as templates and adopts a low-temperature chemical coating method to alternately coat SiO2 and SnO2, and then undergoes a step of heat treatment to prepare double hollow multi-shell H-SiO2@SnO2@H-SiO2@SnO2 core-shell microspheres. The synthesis method is simple and economical, the reaction process is mild and controllable, the yield is high, and large-scale production can be carried out.
[0021] 2. The double hollow multi-shell core-shell microspheres prepared by the present invention have good monodispersity, uniform particle size, and controllable shell thickness. Compared with conventional SiO2 microspheres, the double hollow, symmetrical multilayer structure and rough surface characteristics make them have higher emissivity. Its double hollow, symmetrical multilayer structure and rough surface characteristics have broad application prospects in the fields of thermal radiation, drug sustained release, catalysis, sensors, nanoreactors, etc. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 This is a scanning electron microscope image of PS@SiO2 core-shell microspheres prepared in Example 1 of the present invention;
[0023] Figure 2 This is a transmission electron microscope image of PS@SiO2 core-shell microspheres prepared in Example 1 of the present invention;
[0024] Figure 3 This is a scanning electron microscope image of PS@SiO2@SnO2 core-shell microspheres prepared in Example 1 of the present invention;
[0025] Figure 4 This is a transmission electron microscope image of H-SiO2@SnO2 core-shell microspheres prepared in Example 1 of the present invention;
[0026] Figure 5 This is a transmission electron microscope image of H-SiO2@SnO2@SiO2 core-shell microspheres prepared in Example 1 of the present invention;
[0027] Figure 6 This is a transmission electron microscope image of H-SiO2@SnO2@H-SiO2@SnO2 core-shell microspheres prepared in Example 1 of the present invention;
[0028] Figure 7 This is a spectral emissivity diagram of the H-SiO2@SnO2@H-SiO2@SnO2 core-shell microspheres prepared in Example 1 of the present invention. DETAILED DESCRIPTION
[0029] The present invention will be further described below in conjunction with the embodiments shown in the accompanying drawings.
[0030] Embodiment 1:
[0031] A method for preparing double hollow multi-shell H-SiO2@SnO2@H-SiO2@SnO2 core-shell microspheres is specifically completed according to the following steps:
[0032] (1) First, ultrasonically disperse 10g of PVP-modified PS microsphere emulsion (PS emulsion concentration is about 0.1mg / mL) in 250mL of anhydrous ethanol, then transfer it to a 500mL three-necked flask, add 3mL of ammonia water, and stir to mix evenly. Heat to 70℃, dilute 20mL of TEOS with 50mL of ethanol, and use a constant pressure dropping funnel to drop the TEOS dilution into the reaction bottle. After the drop is complete, continue the reaction for 6h. Centrifuge the product, and the resulting precipitate is ultrasonically cleaned three times with water and ethanol, respectively, and dried at 80℃ for 12h to obtain PS@SiO2 core-shell microsphere powder.
[0033] Figure 1 This is a scanning electron microscope picture of PS@SiO2 core-shell microspheres. It can be seen that they have good monodispersity and uniform particle size. The shell layer is formed by SiO2 particles deposited on the surface of PS microspheres, and its surface is rough. Figure 2 This is a transmission electron microscope image of PS@SiO2 core-shell microspheres.
[0034] (2) 0.80 g of PS@SiO2 core-shell microspheres were uniformly dispersed in 70 mL of deionized water by ultrasonic dispersion and transferred to a 500 mL reaction bottle. 0.62 g of Na2SnO3·4H2O was dissolved in a mixture of 150 mL of deionized water and anhydrous ethanol (volume ratio of deionized water to anhydrous ethanol was 1:1), and the mixture was added to the reaction bottle using a constant pressure dropping funnel. The reaction was completed at 70°C for 4 h, and the product was centrifuged. The resulting precipitate was ultrasonically washed three times with water and ethanol, respectively, and dried at 80°C for 12 h to obtain PS@SiO2@SnO2 core-shell microsphere powder.
[0035] Figure 3 This is a scanning electron microscope image of PS@SiO2@SnO2 core-shell microspheres. It can be seen that its morphology is similar to that of PS@SiO2 core-shell microspheres. It also has a relatively rough surface, good monodispersity, and uniform particle size distribution.
[0036] (3) Weigh 0.2g of PS@SiO2@SnO2 core-shell microspheres, ultrasonically disperse them in a reaction bottle with 80mL of deionized water, add 3g of PVP, stir at 25°C for 20h, centrifuge the product after the reaction, and ultrasonically clean the precipitate with water and ethanol three times. The precipitate after the last ultrasonic cleaning was ultrasonically dispersed with 150mL of ethanol, transferred to a 250mL reaction bottle, added 10mL of ammonia water, diluted 1mL of TEOS with 30mL of anhydrous ethanol, and added the TEOS dilution to the reaction bottle with a constant pressure dropping funnel. React at 25°C for 12h. After the reaction, centrifuge the product, ultrasonically clean the precipitate with water and ethanol three times, and dry at 80°C for 12h to obtain PS@SiO2@SnO2@SiO2 core-shell microsphere powder.
[0037] (4) The synthesis method for coating a layer of SnO2 on the surface of PS@SiO2@SnO2@SiO2 core-shell microspheres is the same as step (2), except that the amount of Na2SnO3·4H2O is increased to 1.24 g, and the amount of other sample reagents added remains unchanged. The final product after the reaction is dried at 80°C for 12 h to obtain PS@SiO2@SnO2@H-SiO2@SnO2 core-shell microsphere powder.
[0038] (5) The microsphere powders obtained in steps (1), (2), (3) and (4) are placed in magnetic boats respectively, and transferred to a muffle furnace under air atmosphere, and heat treated at 200°C for 0.5 h, and then heated to 400°C for 3 h to obtain H-SiO2 microspheres, H-SiO2@SnO2 core-shell microspheres, H-SiO2@SnO2@SiO2 core-shell microspheres, and H-SiO2@SnO2@H-SiO2@SnO2 core-shell microspheres. The heating rate of the muffle furnace is 5°C / min.
[0039] Figure 4 This is a transmission electron microscope image of H-SiO2@SnO2 core-shell microspheres, which shows that their morphology is hollow core-shell microspheres.
[0040] Figure 5 This is a transmission electron microscope image of H-SiO2@SnO2@SiO2 core-shell microspheres. It can be seen that the outermost layer is the SiO2 shell layer, and its morphology is a hollow multi-shell core-shell microsphere.
[0041] Figure 6 This is a transmission electron microscope image of H-SiO2@SnO2@H-SiO2@SnO2 core-shell microspheres, which can be seen as obvious double hollow multi-shell core-shell microspheres.
[0042] Figure 7 It is the spectral emissivity graph of double hollow multi-shell H-SiO2@SnO2@H-SiO2@SnO2 core-shell microspheres, and its emissivity is 0.89~0.99.
Claims
1. A method for preparing double hollow multi-shell H-SiO2@SnO2@H-SiO2@SnO2 core-shell microspheres, characterized in that: The method comprises the following preparation steps: (1) First, PS microspheres prepared by soap-free emulsion polymerization are modified with PVP, and then dispersed into an ethanol solution to form a uniform PS microsphere ethanol dispersion, and then the ethanol dispersion is transferred to a three-necked flask, mechanically stirred, and then ammonia water is added, and the three-necked flask is heated to 50-80°C, TEOS is diluted with ethanol solution, and then the dilution is added to the three-necked flask using a constant pressure dropping funnel. After the dropping is completed, the reaction is continued for 5h-12h. After the reaction is completed, the product is centrifuged, and the precipitate is ultrasonically washed three times with water and ethanol, and finally the product is dried at 50°C-80°C. Dry in an oven at 0°C for 8h to 24h to obtain PS@SiO2 microsphere powder; the concentration of the PS microsphere ethanol dispersion in the above step (1) is 1.00mg / mL to 800mg / mL (PS microspheres are modified with PVP according to the PVP modification method in step (3)), the amount of ethanol added is 20mL to 2000mL, and the concentration of ammonia water is 0.02mol / L to 1.2mol / L; the concentration of TEOS after dilution with ethanol solution is 0.1mol / L to 2mol / L, and the amount of ethanol used is 10mL to 500mL; (2) The PS@SiO2 core-shell microsphere powder obtained in step (1) is ultrasonically dispersed in 15 mL to 2500 mL of deionized water to form a uniform PS@SiO2 core-shell microsphere dispersion, and the dispersion is transferred to a three-necked flask and stirred at a constant speed, and Na2SnO3·4H2O is dissolved in a mixture of water and ethanol in a volume ratio of 1:1 to form a Na2SnO3·4H2O mixed solution, and the Na2SnO3 mixed solution is added to the three-necked flask through a constant pressure dropping funnel, and the reaction is carried out at 30°C to 90°C for 2h to 7h. After the reaction is completed, The product was centrifuged, and the obtained precipitate was ultrasonically cleaned three times with water and ethanol respectively. Finally, the obtained product was dried in an oven at 50°C to 80°C for 8h to 24h to obtain PS@SiO2@SnO2 core-shell microsphere powder; the concentration of the PS@SiO2 core-shell microsphere dispersion in the above step (2) was 1.00mg / mL to 800mg / mL; the mass ratio of Na2SnO3·4H2O to PS@SiO2 core-shell microspheres was 0.2:1 to 8:1, and the amount of deionized water in the Na2SnO3 mixed solution was 10mL to 1000mL; (3) The PS@SiO2@SnO2 core-shell microsphere powder obtained in step (2) is first modified with PVP, and ultrasonically dispersed in 15 mL to 2500 mL of deionized water to form a PS@SiO2@SnO2 core-shell microsphere dispersion, and then the dispersion is transferred to a three-necked flask and stirred, and PVP is added. The reaction is carried out at 25°C to 35°C for 12 h to 24 h. After the reaction is completed, the product is centrifuged, and the obtained precipitate is ultrasonically cleaned three times with water and ethanol, respectively. That is, the PVP modification is completed, and the obtained product is ultrasonically dispersed with 15 mL to 2500 mL of ethanol solution to form a uniform PS@SiO2@SnO2 core-shell microsphere ethanol dispersion, and then the ethanol dispersion is transferred to a reaction vessel and stirred, and ammonia water is added. TEOS is diluted with ethanol solution, and the TEOS ethanol dilution is dripped into the reactor at 25 to 35°C, and stirring is continued after dripping. The reaction was continued for 4 to 24 hours. After the reaction was completed, the product was centrifuged. The precipitate was ultrasonically cleaned three times with water and ethanol respectively. The product was dried in an oven at 50°C to 80°C for 8 to 24 hours to obtain PS@SiO2@SnO2@SiO2 core-shell microsphere powder. The concentration of the PS@SiO2@SnO2 core-shell microsphere dispersion in the above step (3) was 1.00 mg / mL to 500 mg / mL, the concentration of the PS@SiO2@SnO2 core-shell microsphere ethanol dispersion was 1.00 mg / mL to 800 mg / mL, the mass ratio of PVP to PS@SiO2@SnO2 core-shell microsphere was 0.5:1 to 30:1, the concentration of the TEOS ethanol dilution was 0.1 mol / L to 2.0 mol / mL, the amount of ethanol used was 10 mL to 500 mL, and the concentration of ammonia water was 0.1 mol / L to 2.5 mol / L. (4) The PS@SiO2@SnO2@SiO2 core-shell microsphere powder obtained in step (3) is ultrasonically dispersed in 15 mL to 2500 mL of deionized water to obtain a PS@SiO2@SnO2@SiO2 core-shell microsphere dispersion, which is transferred to a three-necked flask and stirred. Na2SnO3·4H2O is dissolved in a mixture of deionized water and ethanol in a volume ratio of 1:1 to form a Na2SnO3 mixed solution, which is added to the three-necked flask using a constant pressure dropping funnel, and reacted at 30°C to 90°C for 2h to 7h. After the reaction is completed, the product is centrifuged and the resulting precipitate is washed with deionized water and 4H2O. and ethanol ultrasonic cleaning three times, and finally the product is dried in an oven at 50°C to 80°C for 8h to 24h to obtain PS@SiO2@SnO2@H-SiO2@SnO2 core-shell microsphere powder; the concentration of the PS@SiO2@SnO2@SiO2 core-shell microsphere dispersion in the above step (4) is 1.00mg / mL to 800mg / mL, the mass ratio of Na2SnO3·4H2O to PS@SiO2@SnO2@SiO2 core-shell microsphere is 0.5:1 to 2:1, and the amount of deionized water in the Na2SnO3 mixed solution is 10mL to 1000mL; (5) The microsphere powders obtained in the above steps (1), (2), (3) and (4) are placed in magnetic boats respectively, and transferred to a muffle furnace. In an air atmosphere, they are heat treated at 200°C for 0.5h to 1h, and then heated to 400°C to 600°C for 1h to 6h to obtain H-SiO2 microspheres, H-SiO2@SnO2 core-shell microspheres, H-SiO2@SnO2@SiO2 core-shell microspheres, H-SiO2@SnO2@SiO2 core-shell microspheres, and H-SiO2@SnO2@H-SiO2@SnO2 core-shell microspheres. The heating rate of the muffle furnace in the above step (5) is 0.5°C / min to 10°C / min.
2. The method for preparing double hollow multi-shell H-SiO2@SnO2@H-SiO2@SnO2 core-shell microspheres according to claim 1, characterized in that: In the step (1), the PVP-modified PS emulsion prepared by the soap-free emulsion polymerization method is first dispersed in an ethanol solution to form a uniform PS microsphere ethanol dispersion, and then the ethanol dispersion is transferred to a three-necked flask, mechanically stirred, and then ammonia water is added, and the three-necked flask is heated to 55-75° C. TEOS is diluted with an ethanol solution, and then the dilution is added to the three-necked flask using a constant pressure dropping funnel. After the dropping is completed, the reaction is continued for 5.5 h to 11.5 h. After the reaction is completed, the product is centrifuged, and the precipitate is ultrasonically cleaned three times with water and ethanol respectively, and finally the product is dried in an oven at 55° C. to 75° C. Dry for 8.5h to 23.5h to obtain PS@SiO2 core-shell microsphere powder; the concentration of the PS microsphere ethanol dispersion in the above step (1) is 1.50mg / mL to 799.5mg / mL (PS microspheres are modified with PVP according to the PVP modification method in step (3)), the amount of ethanol added is 25mL to 1995mL, and the concentration of ammonia water is 0.025mol / L to 1.195mol / L; the concentration of TEOS after dilution with ethanol solution is 0.15mol / L to 1.95mol / L, and the amount of ethanol used is 15 to 495mL.
3. The method for preparing double hollow multi-shell H-SiO2@SnO2@H-SiO2@SnO2 core-shell microspheres according to claim 2, characterized in that: In the above step (2), the PS@SiO2 core-shell microsphere powder obtained in step (1) is ultrasonically dispersed in 20 mL to 2495 mL of deionized water to form a uniform PS@SiO2 core-shell microsphere dispersion, and the dispersion is then transferred to a three-necked flask and stirred at a constant speed, and Na2SnO3·4H2O is dissolved in a mixture of water and ethanol in a volume ratio of 1:1 to form a Na2SnO3·4H2O mixed solution, and the Na2SnO3 mixed solution is added to the three-necked flask through a constant pressure dropping funnel, and the reaction is carried out at 35°C to 85°C for 2.5h to 6.5h, and the reaction is terminated. The product was then centrifuged, and the resulting precipitate was ultrasonically cleaned three times with water and ethanol respectively. Finally, the product was dried in an oven at 55°C to 75°C for 8.5h to 23.5h to obtain PS@SiO2@SnO2 core-shell microsphere powder. The concentration of the PS@SiO2 core-shell microsphere dispersion in the above step (2) was 1.50mg / mL to 799.5mg / mL. The mass ratio of Na2SnO3·4H2O to PS@SiO2 core-shell microspheres was 0.3:1 to 7.9:1, and the amount of deionized water in the Na2SnO3 mixed solution was 15mL to 995mL.
4. The method for preparing double hollow multi-shell H-SiO2@SnO2@H-SiO2@SnO2 core-shell microspheres according to claim 3, characterized in that: In the above step (3), the PS@SiO2@SnO2 core-shell microsphere powder obtained in step (2) is first modified with PVP, and ultrasonically dispersed in 20mL~2495mL deionized water to form a PS@SiO2@SnO2 core-shell microsphere dispersion, and then the dispersion is transferred to a three-necked flask and stirred, and PVP is added, and the reaction is carried out at 26°C~34°C for 12.5h~23.5h. After the reaction is completed, the product is centrifuged, and the obtained precipitate is ultrasonically washed three times with water and ethanol, respectively, that is, the PVP modification is completed, and the obtained product is ultrasonically dispersed with 20mL~2495mL ethanol solution to form a uniform PS@SiO2@SnO2 core-shell microsphere ethanol dispersion, and then the ethanol dispersion is transferred to a reaction container and stirred, ammonia water is added, TEOS is diluted with ethanol solution, and the TEOS ethanol dilution is added dropwise to the reactor at 26~34°C. After the addition is completed, the reaction is continued by stirring for 4.5 h~23.5h, after the reaction is completed, the product is centrifuged, the obtained precipitate is ultrasonically cleaned three times with water and ethanol respectively, and finally the obtained product is dried in an oven at 55℃~75℃ for 8.5h~23.5h to obtain PS@SiO2@SnO2@SiO2 core-shell microsphere powder; the concentration of the PS@SiO2@SnO2 core-shell microsphere dispersion described in the above step (3) is 1.50mg / mL~495mg / mL, the concentration of the PS@SiO2@SnO2 core-shell microsphere ethanol dispersion is 1.50mg / mL~799.5mg / mL, the mass ratio of PVP to PS@SiO2@SnO2 core-shell microsphere is 0.6:1~29.9:1, the concentration of TEOS ethanol dilution is 0.15mol / L~1.95mol / mL, the amount of ethanol used is 15mL~495mL, and the concentration of ammonia water is 0.15mol / L~2.45mol / L.
5. The method for preparing double hollow multi-shell H-SiO2@SnO2@H-SiO2@SnO2 core-shell microspheres according to claim 4, characterized in that: In the above step (4), the PS@SiO2@SnO2@SiO2 core-shell microsphere powder obtained in step (3) is ultrasonically dispersed in 20mL~2495mL deionized water to obtain a PS@SiO2@SnO2@SiO2 core-shell microsphere dispersion, and the dispersion is transferred to a three-necked flask and stirred. Na2SnO3·4H2O is dissolved in a mixture of deionized water and ethanol in a volume ratio of 1:1 to form a Na2SnO3 mixed solution, which is added to the three-necked flask using a constant pressure dropping funnel, and reacted at 35°C~85°C for 2.5h~6.5h. After the reaction is completed, the product is centrifuged and the resulting precipitates are respectively used for deionization. The obtained product is dried in an oven at 55°C to 75°C for 8.5h to 23.5h to obtain PS@SiO2@SnO2@H-SiO2@SnO2 core-shell microsphere powder; the concentration of the PS@SiO2@SnO2@SiO2 core-shell microsphere dispersion in the above step (4) is 1.00mg / mL to 800mg / mL, the mass ratio of Na2SnO3·4H2O to PS@SiO2@SnO2@SiO2 core-shell microsphere is 0.6:1 to 1.9:1, and the amount of deionized water in the Na2SnO3 mixed solution is 15mL to 995mL.
6. The method for preparing double hollow multi-shell H-SiO2@SnO2@H-SiO2@SnO2 core-shell microspheres according to claim 5, characterized in that: In the above step (5), the microsphere powders obtained in steps (1), (2), (3) and (4) are respectively placed in a magnetic boat and transferred to a muffle furnace. In an air atmosphere, they are heat treated at 200°C for 0.6h to 0.9h, and then heated to 405°C to 595°C for 1.5h to 5.5h to obtain H-SiO2 microspheres, H-SiO2@SnO2 core-shell microspheres, H-SiO2@SnO2@SiO2 core-shell microspheres, H-SiO2@SnO2@SiO2 core-shell microspheres, and H-SiO2@SnO2@H-SiO2@SnO2 core-shell microspheres. The heating rate of the muffle furnace in the above step (5) is 1°C / min to 9.5°C / min.