A kind of cerium dioxide hollow sphere and its preparation method and application

Abstract

The invention belongs to the field of inorganic nanomaterial technology, and in particular to a kind of cerium dioxide hollow sphere and preparation method and application thereof, the surface of silica colloidal sphere is modified by the amido organosilicon quaternary ammonium salt prepared, and modified silica colloidal sphere is obtained; Polystyrene microspheres and modified silica colloidal sphere are weighed and dispersed in aqueous ethanol, ceric ammonium nitrate solution is added and 3~5mL, 0.01mol / L sodium citrate solution are added simultaneously as morphology directing agent to obtain core-shell structure microsphere; Core-shell structure microsphere is etched with alkali liquor, and then gradient calcination obtains cerium oxide hollow sphere. The present invention carries out modification modification on the surface of silica colloidal sphere by amido organosilicon quaternary ammonium salt, increases the amount of functional group, improves the surface charge density of silica colloidal sphere, makes precursor form dense shell layer on the surface of silica colloidal sphere, prevents collapse.

Description

Technical Field

[0001] The 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] Cerium oxide, as an n-type semiconductor and 4f electron energy level structure, has a band gap of 2.94eV and a light absorption threshold of about 420nm. Theoretically, as long as the wavelength of light is less than 420nm, it can be absorbed by cerium oxide, and cerium oxide has a low refractive index for light, so cerium oxide is an important UV shielding material.

[0003] Cerium oxide hollow spheres are added to high-end cosmetics, especially sunscreen cosmetics, which can not only play a role in sun protection, but also achieve antioxidant effects by loading antioxidants.

[0004] The preparation methods of cerium oxide hollow spheres include solvent thermal 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 the more commonly used method in the prior art. The main steps of the hard template method are to first prepare monodisperse hard template microspheres. Common hard templates include silica colloidal spheres, polystyrene spheres, carbon spheres prepared by hydrothermal polysaccharide and various organic polymer microspheres. Then, through physical, chemical adsorption or precipitation, sol-gel and other means, the template surface is coated with a certain thickness of precursor to form a core-shell complex. Then, the template is removed by physical or chemical methods to prepare the target product with a hollow structure.

[0005] However, during the preparation of hollow ceria spheres, the amount of functional groups on the surface of the colloidal spheres is limited, resulting in a thin shell. The spheres often collapse after the template is removed. Furthermore, insufficient morphology control during the preparation process results in an irregular surface. This can create a gritty feel when applied to sunscreen cosmetics, affecting the skin feel. 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, so as to solve the problems raised in the above background technology.

[0007] In order to achieve the above technical objectives, the technical solution of the present invention is:

[0008] A method for preparing hollow cerium dioxide spheres comprises the following steps:

[0009] S1, using chloroacetyl and N,N-dimethyl-1,3-propylenediamine as reactants, dichloromethane as solvent, and adding an acid binding agent and a water scavenger to prepare N-(3-(dimethylamino)propyl)acetamide;

[0010] Then, N-(3-(dimethylamino)propyl)acetamide and (3-chloropropyl)trimethoxysilane are used as reactants, potassium iodide is used as a catalyst, and isopropyl alcohol is used as a solvent. The reaction is carried out under nitrogen protection, and then purified to obtain an amido organosilicon quaternary ammonium salt.

[0011] S2. Ultrasonic dispersion of silica colloidal spheres in ethanol solution to prepare a 0.5 g / mL silica dispersion, adding amido organosilicon quaternary ammonium salt thereto, heating to 70° C. and stirring continuously for 8 h, filtering, washing, and vacuum drying to obtain modified silica colloidal spheres;

[0012] S3, weighing ammonium cerium nitrate and dissolving it in distilled water to obtain an ammonium cerium nitrate solution, weighing polystyrene microspheres and modified silica colloidal spheres and dispersing them 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, filtering, washing, and drying to obtain core-shell structured microspheres;

[0013] S4. The core-shell structured microspheres are etched with an alkaline solution, and then gradient calcined to obtain hollow cerium oxide spheres.

[0014] As a further improvement, in step S2, the mass ratio of the amido organosilicon quaternary ammonium salt to the silica colloidal spheres is 30:1-1.5.

[0015] As a further improvement, in step S3, the mass ratio of the polystyrene microspheres, the modified silica colloidal spheres, and the ceric ammonium nitrate is 1:0.5:10-11.

[0016] As a further improvement, in step S4, the specific steps of alkaline solution etching are as follows: the shell-core structured microspheres are dispersed in a 3 mol / L sodium hydroxide solution, heated at 80°C for 2 h, cooled and filtered to obtain a solid substance, and washed three times with deionized water and anhydrous ethanol respectively, and repeated 2 to 3 times, wherein 0.5 g of shell-core structured microspheres are added to every 100 mL of sodium hydroxide solution.

[0017] As a further improvement, in step S4, the specific steps of gradient calcination are: the solid material obtained by alkali solution etching is first calcined at 200°C for 1h, then calcined at 350°C for 2h, and finally calcined at 500°C for 0.5h and then cooled. The heating rate of the gradient calcination is 10°C / min, and the cooling rate of the gradient calcination is first cooled to 95°C at a rate of 25°C / min and then naturally cooled to room temperature.

[0018] As a further improvement, in step S1, the acid binding agent is sodium bicarbonate, the molar ratio of N,N-dimethyl-1,3-propylenediamine, chloroacetyl and sodium bicarbonate is 1.3:1:1.1, the dehydrating agent is anhydrous magnesium sulfate, and the reaction conditions are stirring at room temperature for 6 hours.

[0019] 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 80°C for 48 hours.

[0020] The invention also provides a hollow cerium dioxide sphere.

[0021] The present invention also provides an application of the cerium dioxide hollow spheres in light protection products.

[0022] Due to the adoption of the above technical solution, the present invention has the following beneficial effects:

[0023] The present invention provides hollow cerium dioxide spheres, a preparation method thereof, and an application thereof. The surfaces of the cerium dioxide colloid spheres are modified by using an amido organic silicon quaternary ammonium salt to increase the amount of functional groups and improve the surface charge density of the cerium dioxide colloid spheres. A precursor forms a dense shell on the surface of the cerium dioxide colloid spheres to prevent collapse. The hollow cerium dioxide spheres are prepared using a dual-template system, and the amount of a modifier added and the amount of a precursor used are adjusted to control the thickness of the shell, thereby achieving a shell thickness of 20 to 22 nm.

[0024] The present invention introduces amide groups into a surface modifier. During the alkali etching of the silica colloidal spheres, the amide groups on the surface of the silica colloidal spheres are rapidly hydrolyzed by the alkali solution, thereby forming a space inside the shell. This can accelerate the etching speed of the silica colloidal spheres and prevent the alkali solution from being unable to enter the shell layer after a dense shell layer is formed, resulting in a slow etching speed of the silica colloidal spheres. The introduction of the amide groups can accelerate the etching speed and etching effect of the template.

[0025] During the preparation of core-shell structured microspheres, the present invention adds a sodium citrate solution as a morphology directing agent to induce crystal face epitaxial growth, regulate the morphology of the cerium oxide hollow microspheres, increase the sphericity, and improve the skin feel of sunscreen and other skin care products. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 are transmission electron microscope images of the hollow cerium oxide 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;

[0027] Figure 2 The infrared analysis spectra of the hollow cerium oxide spheres prepared in Example 1, Comparative Example 3, and Comparative Example 4 are shown, 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;

[0028] Figure 3 is a SEM photograph of the cerium dioxide hollow spheres prepared in Example 1. DETAILED DESCRIPTION

[0029] The technical scheme of the present invention will be clearly and completely described below in conjunction with specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work premise belong to the scope of protection of the present invention. Those who do not specify specific conditions in the embodiments are carried out according to normal conditions or the conditions recommended by the manufacturer. Those whose reagents or instruments are not specified by the manufacturer are conventional products that can be purchased commercially.

[0030] In the present invention, the preparation methods of silica colloidal spheres and polystyrene microspheres are both prior art, and the specific preparation methods are as follows:

[0031] Silica colloidal spheres were prepared using the Stober method;

[0032] Anhydrous ethanol, ammonia water, and deionized water were mixed and magnetically stirred for 30 minutes to obtain a homogeneous solution in a volume ratio of 60:9:25. Then, ethyl orthosilicate was added thereto in a volume ratio of ethyl orthosilicate to anhydrous ethanol of 1:15. After stirring for 1 hour, the mixture was centrifuged, and the precipitate was separated and washed to obtain silica colloidal spheres.

[0033] Polystyrene microspheres were prepared by soap-free emulsion polymerization;

[0034] Styrene monomer was added to distilled water with a mass ratio of styrene monomer to distilled water of 1:10, and then the temperature was raised to 70°C under a nitrogen atmosphere. 10 mL of a 10 mg / mL potassium persulfate solution was then added. The mixture was stirred for 10 h and then cooled. The precipitate was separated by centrifugation and dried to obtain polystyrene microspheres.

[0035] Example 1 A method for preparing hollow cerium dioxide spheres comprises the following steps:

[0036] S1. Preparation of surface modifier;

[0037] Take 135.45 g (1.3 mol) of N,N-dimethyl-1,3-propylenediamine, then add 50 mL of dichloromethane to dilute it to obtain a diluted N,N-dimethyl-1,3-propylenediamine solution; take 71.1 mL (1 mol) of chloroacetyl, add 20 mL of dichloromethane to dilute it to obtain a diluted chloroacetyl solution;

[0038] To the N,N-dimethyl-1,3-propylenediamine dilution, 92.41 g of an acid-binding agent, sodium bicarbonate, and 2 g of anhydrous magnesium sulfate, a water removal agent, were added, and stirred in an ice-water bath at 3 ° C for 0.5 h. Then, the chloroacetyl dilution was slowly added dropwise thereto. After the addition was completed, the temperature was raised to room temperature, 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 and separated, and the washing was continued 3 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 at 20 KPa and 30 ° C.

[0039] 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. under a nitrogen atmosphere and stirred and refluxed for 48 hours. After the reaction was completed, the mixture was filtered and the filtrate was collected. The mixture was subjected to reduced pressure distillation at 10 KPa and 55° C., cooled, and washed with petroleum ether to precipitate a colloid. The obtained colloid was subjected to reduced pressure distillation at 20 KPa and 50° C. to obtain an amido organosilicon quaternary ammonium salt.

[0040] S2, surface modification of silica colloidal spheres;

[0041] 1 g of silica colloidal spheres were ultrasonically dispersed in an ethanol solution to prepare a 0.5 g / mL silica dispersion. 30 g of amido organosilicon quaternary ammonium salt was then added to the dispersion. The mixture was heated to 70°C and stirred continuously for 8 h. The solid matter was filtered and washed three times with anhydrous ethanol and distilled water, respectively, and then dried in a vacuum at 120°C for 1 h to obtain modified silica colloidal spheres.

[0042] S3, dissolving 1 g of cerium ammonium nitrate in distilled water to obtain a 0.1 mol / L cerium ammonium nitrate solution;

[0043] 0.1 g of polystyrene microspheres and 0.05 g of modified silica colloidal spheres were dispersed in 50 mL of a mixed solution of ethanol and water, with a volume ratio of ethanol to water of 4:1. The above-prepared ammonium cerium nitrate solution was added thereto, and 3 mL of 0.01 mol / L sodium citrate was added as a morphology directing agent. The mixture was magnetically stirred at 45 ° C for 6 h, and then naturally cooled and filtered to obtain a solid material. The solid material was 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.

[0044] S4, template alkaline solution etching and template gradient calcination;

[0045] 0.5 g of core-shell microspheres were dispersed in 100 mL of 3 mol / L sodium hydroxide solution and heated at 80 °C for 2 h. After cooling, the solid was filtered and washed three times with deionized water and anhydrous ethanol respectively. Then, the template was etched with alkaline solution in sodium hydroxide solution, and the template alkali solution etching was repeated three times.

[0046] The solid material obtained after three alkaline solution etching was first calcined at 200°C for 1h, then calcined at 350°C for 2h, and finally calcined at 500°C for 0.5h before cooling. The calcination heating rate was 10°C / min. After calcination, it was 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.

[0047] Example 2 A method for preparing hollow cerium dioxide spheres comprises the following steps:

[0048] S1. Preparation of surface modifier;

[0049] Take 135.45 g (1.3 mol) of N,N-dimethyl-1,3-propylenediamine, then add 50 mL of dichloromethane to dilute it to obtain a diluted N,N-dimethyl-1,3-propylenediamine solution; take 71.1 mL (1 mol) of chloroacetyl, add 20 mL of dichloromethane to dilute it to obtain a diluted chloroacetyl solution;

[0050] To the N,N-dimethyl-1,3-propylenediamine dilution, 92.41 g of sodium bicarbonate and 2 g of anhydrous magnesium sulfate were added, and the mixture was stirred in an ice-water bath at 3°C for 0.5 h. Then, the chloroacetyl dilution was slowly added dropwise thereto. After the addition was completed, the mixture was heated to room temperature, stirred and refluxed for 6 h, and then filtered. The filtrate was washed with 100 mL of a 5% by mass sodium bicarbonate solution, allowed to stand and separated, and the mixture was washed three 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 reduced pressure distillation to obtain N-(3-(dimethylamino)propyl)acetamide. The reduced pressure distillation was specifically carried out at 20 KPa and 30°C.

[0051] 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. under a nitrogen atmosphere and stirred and refluxed for 48 hours. After the reaction was completed, the mixture was filtered and the filtrate was collected. The mixture was subjected to reduced pressure distillation at 10 KPa and 55° C., cooled, and washed with petroleum ether to precipitate a colloid. The obtained colloid was subjected to reduced pressure distillation at 20 KPa and 50° C. to obtain an amido organosilicon quaternary ammonium salt.

[0052] S2, surface modification of silica colloidal spheres;

[0053] 1.5 g of silica colloidal spheres were ultrasonically dispersed in an ethanol solution to prepare a 0.5 g / mL silica dispersion. 30 g of amido organosilicon quaternary ammonium salt was then added to the dispersion. The mixture was heated to 70°C and stirred continuously for 8 h. The solid matter was filtered and washed three times with anhydrous ethanol and distilled water, respectively, and then dried in a vacuum at 120°C for 1 h to obtain modified silica colloidal spheres.

[0054] S3, dissolving 1.05 g of ceric ammonium nitrate in distilled water to obtain a 0.1 mol / L ceric ammonium nitrate solution;

[0055] 0.1 g of polystyrene microspheres and 0.05 g of modified silica colloidal spheres were dispersed in 50 mL of a mixed solution of ethanol and water, with a volume ratio of ethanol to water of 4:1. The above-prepared ammonium cerium nitrate solution was added thereto, and 5 mL of 0.01 mol / L sodium citrate was added as a morphology directing agent. The mixture was magnetically stirred at 45 ° C for 6 h, and then naturally cooled and filtered to obtain a solid material. The solid material was 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.

[0056] S4, template alkaline solution etching and template gradient calcination;

[0057] 0.5 g of core-shell microspheres were dispersed in 100 mL of 3 mol / L sodium hydroxide solution and heated at 80°C for 2 h. After cooling, the solid was filtered and washed three times with deionized water and anhydrous ethanol, respectively. The template was then repeatedly etched with alkaline solution.

[0058] The solid material obtained after two alkaline solution etchings was first calcined at 200°C for 1h, then calcined at 350°C for 2h, and finally calcined at 500°C for 0.5h before cooling. The calcination heating rate was 10°C / min. After calcination, the temperature was 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.

[0059] Example 3 A method for preparing hollow cerium dioxide spheres comprises the following steps:

[0060] S1. Preparation of surface modifier;

[0061] Take 135.45 g (1.3 mol) of N,N-dimethyl-1,3-propylenediamine, then add 50 mL of dichloromethane to dilute it to obtain a diluted N,N-dimethyl-1,3-propylenediamine solution; take 71.1 mL (1 mol) of chloroacetyl, add 20 mL of dichloromethane to dilute it to obtain a diluted chloroacetyl solution;

[0062] To the N,N-dimethyl-1,3-propylenediamine dilution, 92.41 g of sodium bicarbonate and 2 g of anhydrous magnesium sulfate were added, and the mixture was stirred in an ice-water bath at 3°C for 0.5 h. Then, the chloroacetyl dilution was slowly added dropwise thereto. After the addition was completed, the mixture was heated to room temperature, stirred and refluxed for 6 h, and then filtered. The filtrate was washed with 100 mL of a 5% by mass sodium bicarbonate solution, allowed to stand and separated, and the mixture was washed three 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 reduced pressure distillation to obtain N-(3-(dimethylamino)propyl)acetamide. The reduced pressure distillation was specifically carried out at 20 KPa and 30°C.

[0063] 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. under a nitrogen atmosphere and stirred and refluxed for 48 hours. After the reaction was completed, the mixture was filtered and the filtrate was collected. The mixture was subjected to reduced pressure distillation at 10 KPa and 55° C., cooled, and washed with petroleum ether to precipitate a colloid. The obtained colloid was subjected to reduced pressure distillation at 20 KPa and 50° C. to obtain an amido organosilicon quaternary ammonium salt.

[0064] S2, surface modification of silica colloidal spheres;

[0065] 1.3 g of silica colloidal spheres were ultrasonically dispersed in an ethanol solution to prepare a 0.5 g / mL silica dispersion. 30 g of amido organosilicon quaternary ammonium salt was then added to the dispersion. The mixture was heated to 70°C and stirred continuously for 8 h. The solid was filtered and washed three times with anhydrous ethanol and distilled water, respectively, and then dried under vacuum at 120°C for 1 h to obtain modified silica colloidal spheres.

[0066] S3, dissolving 1.1 g of ceric ammonium nitrate in distilled water to obtain a 0.1 mol / L ceric ammonium nitrate solution;

[0067] 0.1 g of polystyrene microspheres and 0.05 g of modified silica colloidal spheres were dispersed in 50 mL of a mixed solution of ethanol and water, with a volume ratio of ethanol to water of 4:1. The above-prepared ammonium cerium nitrate solution was added thereto, and 4 mL of 0.01 mol / L sodium citrate was added as a morphology directing agent. The mixture was magnetically stirred at 45 ° C for 6 h, and then naturally cooled and filtered to obtain a solid material. The solid material was 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.

[0068] S4, template alkaline solution etching and template gradient calcination;

[0069] 0.5 g of core-shell microspheres were dispersed in 100 mL of 3 mol / L sodium hydroxide solution and heated at 80°C for 2 h. After cooling, the solid was filtered and washed three times with deionized water and anhydrous ethanol, respectively. The template was then repeatedly etched with alkaline solution.

[0070] The solid material obtained after two alkaline solution etchings was first calcined at 200°C for 1h, then calcined at 350°C for 2h, and finally calcined at 500°C for 0.5h before cooling. The calcination heating rate was 10°C / min. After calcination, the temperature was 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.

[0071] Comparative Example 1 This comparative example provides a method for preparing hollow cerium dioxide spheres. The specific steps are the same as those in Example 1, except that, in this comparative example, the surface modification of the cerium dioxide colloidal spheres is not performed.

[0072] Comparative Example 2 This comparative example provides a method for preparing hollow cerium dioxide 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.

[0073] Comparative Example 3 This comparative example provides a method for preparing hollow cerium dioxide spheres. The specific steps are the same as those in Example 1, except that in this comparative example, in step S4, the template alkaline solution etching process is performed only once.

[0074] Comparative Example 4 This comparative example provides a method for preparing hollow cerium dioxide 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 the silica colloidal spheres to prepare hollow cerium dioxide spheres. The specific method is: 1.3 g of silica colloidal spheres are ultrasonically dispersed in an ethanol solution to prepare a 0.5 g / mL silica dispersion, and then 40 g of γ-chloropropyltrimethoxysilane is added thereto. The temperature is raised to 90°C and stirred continuously for 8 hours. The solid substance is filtered out and washed three times with anhydrous ethanol and distilled water respectively, and then vacuum dried at 120°C for 1 hour to obtain modified silica colloidal spheres.

[0075] like Figure 1 As 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, 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 1 It can be seen that compared with Comparative Example 1, the surface modification of the cerium dioxide colloidal spheres in Example 1 can improve the density of the shell layer, and by comparing Comparative Example 2 with Example 1, the amount of cerium salt added is greater, and the shell layer of the cerium dioxide hollow spheres obtained in Comparative Example 2 becomes thicker.

[0076] like Figure 2 As shown, the infrared analysis spectra of the hollow cerium oxide spheres prepared in Example 1, Comparative Example 3 and Comparative Example 4 are shown, 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 2 It can be seen that the hollow cerium dioxide spheres prepared in Example 1 do not have obvious characteristic peaks, indicating that the silica template is completely etched during the alkali solution etching process. In Comparative Example 3, only one alkali solution etching is performed, and there are still obvious characteristic peaks, indicating that the silica template is not completely etched. In Comparative Example 4, only quaternary ammonium salt silane is used to modify the surface of the silica colloidal spheres, and alkali solution etching is performed three times. Although the shell density of the hollow cerium dioxide spheres can be improved, the three alkali solution etchings still do not completely remove the silica template, indicating that the introduction of amide groups in the quaternary ammonium salt silane in the present invention can accelerate the etching effect and etching rate of the silica template.

[0077] like Figure 3 , which is a SEM photograph of the hollow cerium oxide spheres prepared in Example 1, indicating that the hollow cerium oxide spheres prepared in the present invention have good sphericity and uniform structure.

[0078] The specific embodiments of the present invention described above do not limit the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A method for preparing hollow cerium dioxide spheres, characterized in that: The following steps are involved: S1, using chloroacetyl and N,N-dimethyl-1,3-propylenediamine as reactants, dichloromethane as solvent, and adding an acid binding agent and a water scavenger to prepare N-(3-(dimethylamino)propyl)acetamide; Then, N-(3-(dimethylamino)propyl)acetamide and (3-chloropropyl)trimethoxysilane are used as reactants, potassium iodide is used as a catalyst, and isopropyl alcohol is used as a solvent. The reaction is carried out under nitrogen protection, and then purified to obtain an amido organosilicon quaternary ammonium salt. S2. Ultrasonic dispersion of silica colloidal spheres in ethanol solution to prepare a 0.5 g / mL silica dispersion, adding amido organosilicon quaternary ammonium salt thereto, heating to 70° C. and stirring continuously for 8 h, filtering, washing, and vacuum drying to obtain modified silica colloidal spheres; S3, weighing ammonium cerium nitrate and dissolving it in distilled water to obtain an ammonium cerium nitrate solution, weighing polystyrene microspheres and modified silica colloidal spheres and dispersing them 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, filtering, washing, and drying to obtain core-shell structured microspheres; S4, etching the core-shell structure microspheres with an alkali solution, and then gradient calcining to obtain hollow cerium dioxide spheres; In step S3, the mass ratio of polystyrene microspheres, modified silica colloidal spheres and ceric ammonium nitrate is 1:0.5:10-11; In step S4, the specific steps of alkaline solution etching are as follows: the shell-core structured microspheres are dispersed in a 3 mol / L sodium hydroxide solution, heated at 80°C for 2 h, cooled and filtered to obtain a solid material, and washed three times with deionized water and anhydrous ethanol, respectively, and repeated 2-3 times, wherein 0.5 g of the shell-core structured microspheres are added to every 100 mL of sodium hydroxide solution; In step S4, the specific steps of gradient calcination are: the solid material obtained by alkali solution etching is first calcined at 200°C for 1h, then calcined at 350°C for 2h, and finally calcined at 500°C for 0.5h and then cooled. The heating rate of the gradient calcination is 10°C / min, and the cooling rate of the gradient calcination is first cooled to 95°C at a rate of 25°C / min and then naturally cooled to room temperature.

2. The method for preparing hollow cerium dioxide spheres according to claim 1, wherein 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 method for preparing hollow cerium dioxide 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-propylenediamine, chloroacetyl and sodium bicarbonate is 1.3:1:1.1, the water scavenger is anhydrous magnesium sulfate, and the reaction conditions are stirring at room temperature for 6 hours.

4. The method for preparing hollow cerium dioxide 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 80° C. and 48 hours.

5. The hollow cerium oxide spheres prepared by the method for preparing hollow cerium oxide spheres according to claim 1.

6. Use of the hollow cerium oxide spheres prepared by the method for preparing hollow cerium oxide spheres according to claim 1 in light protection products.

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