Cerium dioxide hollow sphere as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of inorganic nano materials, and particularly relates to a cerium dioxide hollow sphere and a preparation method and application thereof.The surface of a silicon dioxide colloidal sphere is modified through prepared acylamino organosilicon quaternary ammonium salt, and a modified silicon dioxide colloidal sphere is obtained; weighing polystyrene microspheres and the modified silicon dioxide colloidal spheres, dispersing the polystyrene microspheres and the modified silicon dioxide colloidal spheres in an ethanol aqueous solution, adding a ceric ammonium nitrate solution, and simultaneously adding 3-5mL of a 0.01 mol / L sodium citrate solution as a morphology guiding agent to obtain core-shell structure microspheres; and etching the core-shell structure microspheres with alkali liquor, and then carrying out gradient calcination to obtain the cerium oxide hollow spheres. The surface of the silicon dioxide colloidal sphere is modified through the acylamino organosilicon quaternary ammonium salt, the quantity of functional groups is increased, the surface charge density of the silicon dioxide colloidal sphere is improved, the precursor forms a compact shell layer on the surface of the silicon dioxide colloidal sphere, and collapse is prevented.

Description

Technical Field

[0001] The present invention belongs to the technical field of inorganic nanomaterials, and particularly relates to a cerium dioxide hollow sphere and a preparation method and application thereof. Background Art

[0002] As an n-type semiconductor and 4f electron energy level structure, cerium oxide has a band gap of 2.94 eV, and its light absorption threshold is about 420 nm. Theoretically, as long as the light with a wavelength less than 420 nm can be absorbed by cerium oxide, and cerium oxide has a low refractive index for light. Therefore, cerium oxide is an important ultraviolet shielding material.

[0003] Adding cerium dioxide hollow spheres to high-end cosmetics, especially sunscreen cosmetics, can not only play a sunscreen role, but also achieve an antioxidant effect by loading antioxidant substances.

[0004] The preparation methods of cerium dioxide hollow spheres include solvothermal method and template method. The template method is further divided into hard template method and soft template method. Among them, the hard template method is a relatively commonly used method in the prior art. The main steps of the hard template method are to prepare monodisperse hard template microspheres. Common hard templates include silica colloidal spheres, polystyrene spheres, carbon spheres prepared by polysaccharide hydrothermal method, and various organic polymer microspheres. Then, through physical, chemical adsorption or precipitation, sol-gel and other means, a certain thickness of precursor is coated on the surface of the template to form a core-shell composite, and then the template is removed by physical or chemical methods to prepare the target product with a hollow structure.

[0005] However, in the process of preparing cerium dioxide hollow spheres, the amount of surface functional groups on the silica colloidal spheres is limited, so the obtained shell layer is relatively thin, and the hollow spheres often collapse after removing the template. And there is insufficient morphology control in the preparation process, and the surface of the obtained cerium dioxide hollow spheres is irregular, resulting in a "sand feeling" during the application process when added to sunscreen cosmetics, affecting the skin feeling experience. Summary of the Invention

[0006] The purpose of the present invention is to provide a cerium dioxide hollow sphere and a preparation method and application thereof to solve the problems raised in the above background art.

[0007] To achieve the above technical purpose, the technical solution of the present invention is as follows: A preparation method of a cerium dioxide hollow sphere, comprising the following steps: S1. Using chloroacetyl and N,N-dimethyl-1,3-propanediamine as reactants, dichloromethane as a solvent, and adding an acid-binding agent and a water-removing agent at the same time to prepare N-(3-(dimethylamino)propyl)acetamide; Then, using N-(3-(dimethylamino)propyl)acetamide and (3-chloropropyl)trimethoxysilane as reactants, potassium iodide as a catalyst, and isopropanol as a solvent, the reaction is carried out under nitrogen protection, and then the amidyl organosilicon quaternary ammonium salt is obtained through purification; S2. Ultrasonically disperse silica colloidal spheres in an ethanol solution to prepare a silica dispersion of 0.5 g / mL. Add the amidyl organosilicon quaternary ammonium salt thereto, heat to 70 °C and continuously stir for 8 h, then perform suction filtration, washing, and vacuum drying to obtain modified silica colloidal spheres; S3. Weigh ammonium cerium nitrate and dissolve it in distilled water to obtain an ammonium cerium nitrate solution. Weigh polystyrene microspheres and modified silica colloidal spheres and disperse them in an ethanol aqueous solution. Add the ammonium cerium nitrate solution and simultaneously add 3 - 5 mL of a 0.01 mol / L sodium citrate solution as a morphology guiding agent, and stir magnetically at 45 °C for 6 hours. After natural cooling, perform suction filtration, washing, and drying to obtain core-shell structured microspheres; S4. Etch the core-shell structured microspheres with an alkaline solution, and then perform gradient calcination to obtain cerium oxide hollow spheres.

[0008] As a further improvement, in step S2, the mass ratio of the amidyl organosilicon quaternary ammonium salt to the silica colloidal spheres is 30:1 - 1.5.

[0009] As a further improvement, in step S3, the mass ratio of the polystyrene microspheres, the modified silica colloidal spheres, and the ammonium cerium nitrate is 1:0.5:10 - 11.

[0010] As a further improvement, in step S4, the specific steps of alkaline solution etching are as follows: Disperse the core-shell structured microspheres in a 3 mol / L sodium hydroxide solution, heat at 80 °C for 2 h, cool and then perform suction filtration to obtain a solid substance, wash it three times with deionized water and anhydrous ethanol respectively, and repeat 2 - 3 times, where 0.5 g of the core-shell structured microspheres is added to every 100 mL of the sodium hydroxide solution.

[0011] As a further improvement, in step S4, the specific steps of gradient calcination are as follows: First, calcine the solid substance obtained by alkaline solution etching at 200 °C for 1 h, then at 350 °C for 2 h, and finally at 500 °C for 0.5 h and then cool down. The heating rate of gradient calcination is 10 °C / min, and the cooling rate of gradient calcination is to first cool down at a speed of 25 °C / min to 95 °C and then cool naturally to room temperature.

[0012] As a further improvement, in step S1, the acid-binding agent is sodium bicarbonate, the molar ratio of N,N-dimethyl-1,3-propanediamine, chloroacetyl, and sodium bicarbonate is 1.3:1:1.1, the water-removing agent is anhydrous magnesium sulfate, and the reaction condition is to stir at room temperature for 6 h.

[0013] As a further improvement, in step S1, the molar ratio of N-(3-(dimethylamino)propyl)acetamide, (3-chloropropyl)trimethoxysilane and potassium iodide is 1:1.2:0.24, and the reaction conditions of N-(3-(dimethylamino)propyl)acetamide and (3-chloropropyl)trimethoxysilane are reacting at 80 °C for 48 h.

[0014] The present invention also provides a cerium dioxide hollow sphere.

[0015] The present invention also provides an application of the cerium dioxide hollow sphere in a light protection product.

[0016] Due to the above technical solution, the beneficial effects of the present invention are as follows: For the cerium dioxide hollow sphere, its preparation method and application provided by the present invention, the surface of the silica colloidal sphere is modified by an amide group-containing organosilicon quaternary ammonium salt, the amount of functional groups is increased, the surface charge density of the silica colloidal sphere is increased, so that a dense shell layer is formed on the surface of the silica colloidal sphere to prevent collapse, and a double-template system is adopted to prepare the cerium dioxide hollow sphere, and the addition amount of the modifier and the usage amount of the precursor are adjusted to control the thickness of the shell layer, and the shell layer thickness of 20-22 nm is achieved.

[0017] In the present invention, an amide group is introduced into the surface modifier. During the alkali etching process of the silica colloidal sphere, the amide group on the surface of the silica colloidal sphere is rapidly hydrolyzed by the alkali solution, so that a space is formed inside the shell, which can accelerate the etching speed of the silica colloidal sphere. After the formation of a dense shell layer, the alkali solution cannot enter the inside of the shell layer, resulting in a slow etching speed of the silica colloidal sphere. The introduction of the amide group can accelerate the etching speed and etching effect of the template.

[0018] In the process of preparing the core-shell structure microspheres of the present invention, a sodium citrate solution is added as a morphology guiding agent to induce epitaxial growth of crystal planes, regulate the morphology of the cerium oxide hollow microspheres, improve the sphericity, and improve the skin feel of skin care products such as sunscreen. Description of the Drawings

[0019] Figure 1 are transmission electron microscope images of the cerium dioxide hollow spheres prepared in Comparative Example 1, Comparative Example 2 and Example 1, wherein a is the transmission electron microscope image of Example 1, b is the transmission electron microscope image of Comparative Example 2, and c is the transmission electron microscope image of Comparative Example 1; Figure 2 are infrared analysis spectra of the cerium dioxide hollow spheres prepared in Example 1, Comparative Example 3 and Comparative Example 4, wherein a is the infrared spectrum of Example 1, b is the infrared spectrum of Comparative Example 3, and c is the infrared spectrum of Comparative Example 4; Figure 3 is the SEM photograph of the cerium dioxide hollow sphere prepared in Example 1. Detailed implementation manners

[0020] The technical solutions of the present invention will be clearly and completely described below in conjunction with the specific implementation manners. However, those skilled in the art will understand that the following described embodiments are part of the embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. For those conditions not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. Those reagents or instruments not specified by the manufacturer can be obtained as conventional products through commercial purchase.

[0021] In the present invention, the preparation methods of silica colloidal spheres and polystyrene microspheres are both prior arts, and the specific preparation methods are as follows: The silica colloidal spheres are prepared by the Stober method; Mix absolute ethanol, ammonia water and deionized water and stir magnetically for 30 min to obtain a homogeneous solution. The volume ratio of the three is 60:9:25. Then add tetraethyl orthosilicate thereto, and the volume ratio of tetraethyl orthosilicate to absolute ethanol is 1:15. After stirring for 1 h, centrifuge, separate the precipitate, wash it, and obtain silica colloidal spheres; The polystyrene microspheres are prepared by the soap-free emulsion polymerization method; Add styrene monomer to distilled water, and the mass ratio of styrene monomer to distilled water is 1:10. Then heat to 70 °C under a nitrogen atmosphere, then add 10 mL of a 10 mg / mL potassium persulfate solution, stir and react for 10 h, then cool, centrifuge to separate the precipitate, and dry to obtain polystyrene microspheres.

[0022] Example 1 A preparation method of cerium dioxide hollow spheres, comprising the following steps: S1. Preparation of the surface modifier; Take 135.45 g (1.3 mol) of N,N-dimethyl-1,3-propanediamine, and then add 50 mL of dichloromethane thereto for dilution to obtain an N,N-dimethyl-1,3-propanediamine dilution solution. Take 71.1 mL (1 mol) of chloroacetyl, and add 20 mL of dichloromethane thereto for dilution to obtain a chloroacetyl dilution solution; 92.41 g of the acid-binding agent sodium bicarbonate and 2 g of the water-removing agent anhydrous magnesium sulfate were added to the N,N-dimethyl-1,3-propanediamine dilution solution, and the mixture was stirred in an ice bath at 3 °C for 0.5 h. Then, the chloroacetyl dilution solution was slowly added dropwise thereto. After the addition was completed, the temperature was raised to room temperature, and the mixture was stirred and refluxed for 6 h and then filtered. The filtrate was washed with 100 mL of a 5% sodium bicarbonate solution by mass, allowed to stand for liquid separation after stratification, and washed 3 more times. The lower oil phase was collected, dehydrated with anhydrous magnesium sulfate, and then filtered to obtain an anhydrous oil phase. The solvent was removed by vacuum distillation to obtain N-(3-(dimethylamino)propyl)acetamide. The vacuum distillation was specifically carried out under the conditions of 20 KPa and 30 °C; 146.23 g (1 mol) of N-(3-(dimethylamino)propyl)acetamide and 238.46 g (1.2 mol) of (3-chloropropyl)trimethoxysilane were weighed and mixed, and then 100 mL of isopropanol and 39.84 g (0.24 mol) of potassium iodide were added thereto. The mixture was heated to 80 °C and stirred and refluxed for 48 h under a nitrogen atmosphere. After the reaction was completed, the mixture was filtered, and the filtrate was collected. Vacuum distillation was carried out under the conditions of 10 KPa and 55 °C. After cooling, it was washed with petroleum ether, and a colloidal substance was precipitated. The obtained colloidal substance was vacuum distilled under the conditions of 20 KPa and 50 °C to obtain an amide group organosilicon quaternary ammonium salt; S2. Surface modification of silica colloidal spheres; 1 g of silica colloidal spheres was ultrasonically dispersed in an ethanol solution to prepare a silica dispersion of 0.5 g / mL. Then, 30 g of the amide group organosilicon quaternary ammonium salt was added thereto, and the temperature was raised to 70 °C and continuously stirred for 8 h. The solid substance obtained by suction filtration was washed three times with anhydrous ethanol and distilled water respectively, and then vacuum dried at 120 °C for 1 h to obtain modified silica colloidal spheres; S3. 1 g of ammonium cerium nitrate was dissolved in distilled water to obtain a 0.1 mol / L ammonium cerium nitrate solution; 0.1 g of polystyrene microspheres and 0.05 g of modified silica colloidal spheres were dispersed in 50 mL of an ethanol-water mixed solution with a volume ratio of ethanol to water of 4:1. The above-prepared ammonium cerium nitrate solution was added thereto, and at the same time, 3 mL of 0.01 mol / L sodium citrate was added as a morphology guiding agent. The mixture was magnetically stirred at 45 °C for 6 h, and after natural cooling, the solid substance was obtained by suction filtration, washed three times with deionized water and anhydrous ethanol respectively, and finally dried at 70 °C for 1 h to obtain core-shell structured microspheres; S4. Template alkali etching and template gradient calcination; 0.5 g of core-shell structured microspheres was dispersed in 100 mL of a 3 mol / L sodium hydroxide solution, heated at 80 °C for 2 h, and after cooling, the solid substance was obtained by suction filtration, washed three times with deionized water and anhydrous ethanol respectively, and then continued to be added to the sodium hydroxide solution for template alkali etching. Template alkali etching was repeated three times; The solid substance obtained after three - time alkaline etching is first calcined at 200 °C for 1 h, then at 350 °C for 2 h, and finally at 500 °C for 0.5 h and then cooled. The heating rate of calcination is 10 °C / min. After calcination, it is first cooled to 95 °C at a rate of 25 °C / min, and then naturally cooled to room temperature to obtain cerium dioxide hollow spheres.

[0023] Example 2 A preparation method of cerium dioxide hollow spheres, comprising the following steps: S1. Preparation of surface modifier; Take 135.45 g (1.3 mol) of N,N - dimethyl - 1,3 - propanediamine, and then add 50 mL of dichloromethane to it for dilution to obtain a diluted solution of N,N - dimethyl - 1,3 - propanediamine. Take 71.1 mL (1 mol) of chloroacetyl, and add 20 mL of dichloromethane to it for dilution to obtain a diluted solution of chloroacetyl. Add 92.41 g of sodium bicarbonate and 2 g of anhydrous magnesium sulfate to the diluted solution of N,N - dimethyl - 1,3 - propanediamine, stir in an ice - water bath at 3 °C for 0.5 h, and then slowly dropwise add the diluted solution of chloroacetyl. After the addition is complete, raise the temperature to room temperature, stir and reflux for 6 h, then filter. The filtrate is washed with 100 mL of a 5% sodium bicarbonate solution by mass fraction, allowed to stand for liquid - liquid separation after layering, and washed 3 more times. The lower oil phase is collected, dehydrated with anhydrous magnesium sulfate and then filtered to obtain an anhydrous oil phase. The solvent is removed by vacuum distillation to obtain N - (3 - (dimethylamino)propyl)acetamide. The vacuum distillation is specifically carried out under the conditions of 20 KPa and 30 °C. Weigh 146.23 g (1 mol) of N - (3 - (dimethylamino)propyl)acetamide and 238.46 g (1.2 mol) of (3 - chloropropyl)trimethoxysilane and mix them. Then add 100 mL of isopropanol and 39.84 g (0.24 mol) of potassium iodide to it. Heat to 80 °C and stir and reflux for 48 h under a nitrogen atmosphere. After the reaction is completed, filter and collect the filtrate. Carry out vacuum distillation under the conditions of 10 KPa and 55 °C. After cooling, wash with petroleum ether to precipitate a gel - like substance. The obtained gel - like substance is vacuum distilled under the conditions of 20 KPa and 50 °C to obtain an amide - group organosilicon quaternary ammonium salt. S2. Surface modification of silica colloidal spheres; Ultrasonically disperse 1.5 g of silica colloidal spheres in an ethanol solution to prepare a silica dispersion with a concentration of 0.5 g / mL. Then add 30 g of amide - group organosilicon quaternary ammonium salt to it, raise the temperature to 70 °C and continuously stir for 8 h. The solid substance obtained by suction filtration is washed three times with anhydrous ethanol and distilled water respectively, and then vacuum - dried at 120 °C for 1 h to obtain modified silica colloidal spheres. S3. Dissolve 1.05 g of ammonium cerium nitrate in distilled water to obtain a 0.1 mol / L ammonium cerium nitrate solution; Disperse 0.1 g of polystyrene microspheres and 0.05 g of modified silica colloidal spheres in 50 mL of an ethanol-water mixed solution with a volume ratio of ethanol to water of 4:1. Add the ammonium cerium nitrate solution prepared above thereto, and at the same time add 5 mL of 0.01 mol / L sodium citrate as a morphology guiding agent. Stir magnetically at 45 °C for 6 h, and after natural cooling, filter to obtain a solid substance. Wash it three times with deionized water and anhydrous ethanol respectively, and finally dry it at 70 °C for 1 h to obtain core-shell structured microspheres; S4. Template alkali etching and template gradient calcination; Take 0.5 g of core-shell structured microspheres and disperse them in 100 mL of 3 mol / L sodium hydroxide solution. Heat at 80 °C for 2 h, and after cooling, filter to obtain a solid substance. Wash it three times with deionized water and anhydrous ethanol respectively, and then repeat the template alkali etching; The solid substance obtained after two alkali etching processes is first calcined at 200 °C for 1 h, then at 350 °C for 2 h, and finally at 500 °C for 0.5 h and then cooled. The heating rate during calcination is 10 °C / min. After calcination, cool it to 95 °C at a rate of 25 °C / min first, and then cool it naturally to room temperature to obtain cerium dioxide hollow spheres.

[0024] Example 3 A method for preparing cerium dioxide hollow spheres, comprising the following steps: S1. Preparation of a surface modifier; Take 135.45 g (1.3 mol) of N,N-dimethyl-1,3-propanediamine, and then add 50 mL of dichloromethane thereto for dilution to obtain an N,N-dimethyl-1,3-propanediamine dilution solution. Take 71.1 mL (1 mol) of chloroacetyl, and add 20 mL of dichloromethane thereto for dilution to obtain a chloroacetyl dilution solution; Add 92.41 g of sodium bicarbonate and 2 g of anhydrous magnesium sulfate to the N,N-dimethyl-1,3-propanediamine dilution solution, stir in an ice bath at 3 °C for 0.5 h, and then slowly dropwise add the chloroacetyl dilution solution thereto. After the addition is completed, raise the temperature to room temperature, stir and reflux for 6 h and then filter. Wash the filtrate with 100 mL of a 5% by mass sodium bicarbonate solution, let it stand for liquid separation after layering, continue to wash 3 times, collect the lower oil phase, remove water with anhydrous magnesium sulfate and then filter to obtain an anhydrous oil phase, and remove the solvent by vacuum distillation to obtain N-(3-(dimethylamino)propyl)acetamide. The vacuum distillation is specifically carried out under the conditions of 20 KPa and 30 °C; Weigh 146.23 g (1 mol) of N-(3-(dimethylamino)propyl)acetamide and 238.46 g (1.2 mol) of (3-chloropropyl)trimethoxysilane and mix them. Then add 100 mL of isopropanol and 39.84 g (0.24 mol) of potassium iodide to the mixture. Heat it to 80 °C under a nitrogen atmosphere and stir and reflux for 48 h. After the reaction is completed, filter it, collect the filtrate, perform vacuum distillation at 10 KPa and 55 °C, wash it with petroleum ether after cooling, and a gelatinous substance will precipitate. The obtained gelatinous substance is subjected to vacuum distillation at 20 KPa and 50 °C to obtain an amido organosilicon quaternary ammonium salt; S2. Surface modification of silica colloidal spheres; Ultrasonically disperse 1.3 g of silica colloidal spheres in an ethanol solution to prepare a silica dispersion of 0.5 g / mL. Then add 30 g of amido organosilicon quaternary ammonium salt to it, heat it to 70 °C and continuously stir for 8 h. Filter to obtain a solid substance, wash it three times with anhydrous ethanol and distilled water respectively, and then vacuum dry it at 120 °C for 1 h to obtain modified silica colloidal spheres; S3. Dissolve 1.1 g of ammonium cerium nitrate in distilled water to obtain a 0.1 mol / L ammonium cerium nitrate solution; Disperse 0.1 g of polystyrene microspheres and 0.05 g of modified silica colloidal spheres in 50 mL of an ethanol-water mixed solution with a volume ratio of ethanol to water of 4:1. Add the above-prepared ammonium cerium nitrate solution to it, and at the same time add 4 mL of 0.01 mol / L sodium citrate as a morphology guiding agent. Stir magnetically at 45 °C for 6 h. After natural cooling, filter to obtain a solid substance, wash it three times with deionized water and anhydrous ethanol respectively, and finally dry it at 70 °C for 1 h to obtain core-shell structured microspheres; S4. Template lye etching and template gradient calcination; Take 0.5 g of core-shell structured microspheres and disperse them in 100 mL of 3 mol / L sodium hydroxide solution. Heat it at 80 °C for 2 h. After cooling, filter to obtain a solid substance, wash it three times with deionized water and anhydrous ethanol respectively, and then repeat the template lye etching; The solid substance obtained after two lye etchings is first calcined at 200 °C for 1 h, then at 350 °C for 2 h, and finally at 500 °C for 0.5 h and then cooled. The heating rate of calcination is 10 °C / min. After calcination, it is first cooled to 95 °C at a rate of 25 °C / min, and then naturally cooled to room temperature to obtain cerium dioxide hollow spheres.

[0025] Comparative Example 1 This comparative example provides a method for preparing cerium dioxide hollow spheres. The specific steps are the same as those in Example 1, except that in this comparative example, the surface modification of silica colloidal spheres is not carried out.

[0026] Comparative Example 2 This comparative example provides a method for preparing cerium dioxide hollow spheres. The specific steps are the same as those in Example 1, except that in this comparative example, in step S3, the mass of ammonium cerium nitrate is 1.8 g.

[0027] Comparative Example 3 This comparative example provides a method for preparing cerium dioxide hollow spheres. The specific steps are the same as those in Example 1, except that in this comparative example, in step S4, the template alkali solution etching process is only carried out once.

[0028] Comparative Example 4 This comparative example provides a method for preparing cerium dioxide hollow spheres. The specific steps are the same as those in Example 1, except that in this comparative example, γ-chloropropyltrimethoxysilane is used to modify the surface of silica colloidal spheres to prepare cerium dioxide hollow spheres. The specific method is as follows: 1.3 g of silica colloidal spheres are ultrasonically dispersed in an ethanol solution to prepare a silica dispersion with a concentration of 0.5 g / mL, and then 40 g of γ-chloropropyltrimethoxysilane is added thereto. The temperature is raised to 90 °C and continuously stirred for 8 h. The solid matter obtained by suction filtration is washed three times with absolute ethanol and distilled water respectively, and then vacuum dried at 120 °C for 1 h to obtain modified silica colloidal spheres.

[0029] As Figure 1 shown, the transmission electron microscope images of the cerium dioxide hollow spheres prepared in Comparative Example 1, Comparative Example 2, and Example 1 are shown. Among them, a is the transmission electron microscope image of Example 1, b is the transmission electron microscope image of Comparative Example 2, and c is the transmission electron microscope image of Comparative Example 1. It can be seen from Figure 1 this that compared with Comparative Example 1, in Example 1, by surface modification of the silica colloidal spheres, the density of the shell layer can be improved, and by comparing Comparative Example 2 and Example 1, the addition amount of cerium salt is more, and the shell layer of the cerium dioxide hollow spheres obtained in Comparative Example 2 becomes thicker.

[0030] As Figure 2 shown, the infrared analysis spectra of the cerium dioxide hollow spheres prepared in Example 1, Comparative Example 3, and Comparative Example 4 are shown. Among them, a is the infrared spectrum of Example 1, b is the infrared spectrum of Comparative Example 3, and c is the infrared spectrum of Comparative Example 4. It can be seen from Figure 2 this that there are no obvious characteristic peaks in the cerium dioxide hollow spheres prepared in Example 1, indicating that during the alkali solution etching process, the silica template is completely etched. In Comparative Example 3, only one alkali solution etching is carried out, and obvious characteristic peaks still exist, indicating that the silica template is not completely etched. In Comparative Example 4, only the surface of the silica colloidal spheres is modified with quaternary ammonium salt silane and three alkali solution etching processes are carried out. Although the density of the shell layer of the cerium dioxide hollow spheres can be improved, the silica template is still not completely removed after three alkali solution etching processes, indicating that introducing an amide group into the quaternary ammonium salt silane in the present invention can accelerate the etching effect and etching rate of the silica template.

[0031] As Figure 3 shown, the SEM photograph of the cerium dioxide hollow spheres prepared in Example 1 shows that the cerium dioxide hollow spheres prepared by the present invention have good sphericity and uniform structure.

[0032] The specific embodiments of the present invention described above do not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and deformations made according to the technical concept of the present invention shall be included in the protection scope of the claims of the present invention.

Claims

1. A preparation method of cerium dioxide hollow spheres, characterized in that, It includes the following steps: S1. Using chloroacetyl and N,N-dimethyl-1,3-propanediamine as reactants, dichloromethane as a solvent, and adding an acid-binding agent and a water-removing agent simultaneously to prepare N-(3-(dimethylamino)propyl)acetamide; Then, using N-(3-(dimethylamino)propyl)acetamide and (3-chloropropyl)trimethoxysilane as reactants, potassium iodide as a catalyst, and isopropanol as a solvent, reacting under nitrogen protection, and then purifying to obtain an amido organosilicon quaternary ammonium salt; S2. Ultrasonically dispersing silica colloidal spheres in an ethanol solution to prepare a silica dispersion of 0.5 g / mL, adding the amido organosilicon quaternary ammonium salt thereto, heating to 70 °C and continuously stirring for 8 h, filtering, washing, and drying in vacuo to obtain modified silica colloidal spheres; S3. Weighing ammonium cerium nitrate and dissolving it in distilled water to obtain an ammonium cerium nitrate solution, dispersing polystyrene microspheres and modified silica colloidal spheres in an ethanol aqueous solution, adding the ammonium cerium nitrate solution and simultaneously adding 3 - 5 mL of a 0.01 mol / L sodium citrate solution as a morphology-directing agent, magnetically stirring at 45 °C for 6 hours, naturally cooling, then filtering, washing, and drying to obtain core-shell structured microspheres; S4. Etching the core-shell structured microspheres with an alkaline solution, and then performing gradient calcination to obtain cerium dioxide hollow spheres.

2. The preparation method of cerium dioxide hollow spheres according to claim 1, characterized in that, In step S2, the mass ratio of the amido organosilicon quaternary ammonium salt to the silica colloidal spheres is 30:1 - 1.

5.

3. The preparation method of cerium dioxide hollow spheres according to claim 2, wherein, In step S3, the mass ratio of polystyrene microspheres, modified silica colloidal spheres, and ammonium cerium nitrate is 1:0.5:10 - 11.

4. The preparation method of the cerium dioxide hollow spheres according to claim 1, characterized in that, In step S4, the specific steps of alkaline solution etching are: dispersing the core-shell structured microspheres in a 3 mol / L sodium hydroxide solution, heating at 80 °C for 2 h, cooling, then filtering to obtain a solid substance, washing three times with deionized water and anhydrous ethanol respectively, repeating 2 - 3 times, where 0.5 g of the core-shell structured microspheres is added to every 100 mL of the sodium hydroxide solution.

5. The preparation method of the cerium dioxide hollow spheres according to claim 4, characterized in that, In step S4, the specific steps of gradient calcination are: first calcining the solid substance obtained by alkaline solution etching at 200 °C for 1 h, then at 350 °C for 2 h, and finally at 500 °C for 0.5 h and then cooling down. The heating rate of gradient calcination is 10 °C / min, and the cooling rate of gradient calcination is to first cool down at a speed of 25 °C / min to 95 °C and then naturally cool to room temperature.

6. The preparation method of the cerium dioxide hollow spheres according to claim 1, wherein, In step S1, the acid-binding agent is sodium bicarbonate, the molar ratio of N,N-dimethyl-1,3-propanediamine, chloroacetyl, and sodium bicarbonate is 1.3:1:1.1, the water-removing agent is anhydrous magnesium sulfate, and the reaction condition is stirring at room temperature for 6 h.

7. The preparation method of the cerium dioxide hollow spheres according to claim 1, wherein, In step S1, the molar ratio of N-(3-(dimethylamino)propyl)acetamide, (3-chloropropyl)trimethoxysilane, and potassium iodide is 1:1.2:0.24, and the reaction conditions of N-(3-(dimethylamino)propyl)acetamide and (3-chloropropyl)trimethoxysilane are reacting at 80 °C for 48 h.

8. Cerium dioxide hollow spheres prepared by the method for preparing cerium dioxide hollow spheres according to claim 1.

9. Application of the cerium dioxide hollow spheres prepared by the method for preparing cerium dioxide hollow spheres according to claim 1 in light protection products.

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