A method for preparing a single-aperture hollow silicon sphere

Abstract

This invention discloses a method for preparing single-pore hollow silicon spheres. Using positively charged polystyrene spheres as templates, the method employs electrostatic spray granulation to coat the polystyrene surface with a layer of silica sol. The core is then removed by calcination, resulting in hollow silicon spheres. Because the polystyrene spheres are positively charged, during electrostatic spray granulation, the silicon shell is repelled to one side by a positive electric field of the same charge. Finally, calcination yields single-pore hollow silicon spheres. These spheres can effectively carry functional substances such as fragrances, drugs, and catalysts into their internal space for sustained release, while maintaining good structural strength, thus showing promising practical applications. Furthermore, the preparation method of this invention is simple, allows for mass production, and is beneficial for industrial production and application.

Description

Technical Field

[0001] This invention relates to the field of nanomaterial synthesis, and specifically to a method for preparing a single-pore hollow silicon sphere. Background Technology

[0002] Compared to solid silicon sphere nanomaterials, hollow silicon spheres with nanoshell structures possess superior properties. Their hollow structure serves as an internal space, offering greater possibilities for the integration of material release, magnetic, optical, mechanical, thermal, electrical, and catalytic functions, as well as storage and transportation. Therefore, hollow silicon spheres have a wider range of applications.

[0003] However, how to store functional materials within the internal space and effectively utilize that space has always been a key scientific problem. Currently, the hard template removal method is one of the simplest and most effective methods for preparing hollow silicon spheres. It is widely used due to its simplicity, high reproducibility, good predictability, and the uniformity and stability of the product morphology. This method generally uses carbon spheres or polystyrene (PS) spheres as templates, first coating them with a shell structure, and then removing the core through certain means to obtain a hollow structure.

[0004] However, the hollow structure obtained by the above method has the following problems: if the shell structure is too dense, it is very unfavorable for the internal space loading of functional materials. Most materials cannot be effectively loaded because they cannot enter or the entry channels are too small; if the shell structure is too loose, the shell structure will collapse due to insufficient structural strength, thus losing the internal space structure. Summary of the Invention

[0005] In view of the technical problems existing in the background art, the purpose of the present invention is to provide a method for preparing a single-aperture hollow silicon sphere. The single-aperture hollow silicon sphere prepared by this method can not only smoothly load functional materials into its internal space, but also maintain good structural strength.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] The first aspect of the present invention provides a method for preparing a single-aperture hollow silicon sphere, comprising the following steps:

[0008] S1. Preparation of surface-positively charged modified polystyrene (PS) spheres:

[0009] Positively charged polystyrene spheres were added to an aqueous solution of a Gemini quaternary ammonium salt cationic surfactant, stirred and reacted at a certain temperature, and purified to obtain positively charged polystyrene spheres.

[0010] S2. Preparation of silica sol solution: Add ammonia to a mixture of anhydrous ethanol and water, stir until homogeneous to obtain solution A; then add tetraethyl orthosilicate to solution A, stir and react for 18-24 hours to obtain (classical) silica sol solution.

[0011] S3. Preparation of single-aperture hollow silicon spheres:

[0012] S31. The obtained surface positive charge modified polystyrene spheres are added to a silica sol solution and ultrasonically treated.

[0013] S32. The ultrasonically treated solution is subjected to electrostatic spray granulation and high-temperature calcination to obtain single-pore hollow silicon spheres.

[0014] Preferably, in step S1, the mass ratio of the polystyrene spheres to the gemini quaternary ammonium cationic surfactant is 5-12:0.0005-0.006.

[0015] Preferably, in step S1, the stirring reaction temperature is 40-60℃ and the stirring reaction time is 18-24h.

[0016] Preferably, in step S2, the volume ratio of ammonia to tetraethyl orthosilicate is 0.6-1:12.5.

[0017] Preferably, in step S2, the tetraethyl orthosilicate is added by dropping, with a dropping rate of 0.01-0.05 mL / min.

[0018] Preferably, in step S2, the volume ratio of anhydrous ethanol to water in the anhydrous ethanol and water mixed solvent is 70-100:6-8.

[0019] Preferably, in step S2, the stirring reaction time is 10-20 min.

[0020] Preferably, in step S3, the experimental parameters for electrostatic spray granulation are: positive voltage 20-25kV, spinning distance 25-30cm, injection rate 0.3-0.5mL / h, temperature 30℃, and humidity 30%.

[0021] Preferably, in step S3, the high-temperature calcination temperature is 500-800℃ and the calcination time is 1-3h.

[0022] Preferably, the purification process includes: centrifugation and drying of the reaction product.

[0023] A second aspect of the present invention is to provide a single-aperture hollow silicon sphere obtained by the above-described preparation method.

[0024] The present invention has the following beneficial effects:

[0025] (1) This invention first prepares positively charged polystyrene spheres. Then, using the positively charged polystyrene spheres as templates, electrostatic spray granulation is employed to coat the surface of the polystyrene spheres with a layer of silica sol. The template is then removed by calcination, resulting in hollow silica spheres. The positively charged polystyrene spheres are obtained by surface modification of commercially available positively charged polystyrene spheres using a gemini quaternary ammonium salt cationic surfactant. This is because the gemini quaternary ammonium salt cationic surfactant possesses special double N... + The head group, when used to modify positively charged polystyrene spheres, further increases the electropositivity of the polystyrene sphere surface. This results in a silicon shell that is repelled to one side by a similarly positive electric field during the subsequent electrostatic spray granulation of the positively charged polystyrene spheres. After calcination to remove the core, a single-pore hollow silicon sphere is obtained. This single-pore hollow silicon sphere can effectively load functional substances such as fragrances, pharmaceuticals, and catalysts into its internal space for sustained release, while maintaining good structural strength.

[0026] (2) The preparation method of the present invention is simple and can be mass-produced, which is conducive to industrial production and application. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0028] Figure 1 SEM image of the single-aperture hollow silicon sphere prepared in Example 1 Figure 1 ;

[0029] Figure 2 SEM image of the single-aperture hollow silicon sphere prepared in Example 1 Figure 2 ;

[0030] Figure 3 The image shows the SEM image of the silica spheres finally prepared in Comparative Example 1 when "negatively charged polystyrene spheres" were used instead of "positively charged polystyrene spheres".

[0031] Figure 4 SEM image of the silica spheres prepared in Comparative Example 2;

[0032] Figure 5 The image shows the SEM image of the silica spheres prepared in Comparative Example 3. Detailed Implementation

[0033] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention may be implemented in other embodiments without these specific details.

[0034] Example 1

[0035] A method for preparing a single-aperture hollow silicon sphere, comprising the following steps:

[0036] S1. Preparation of polystyrene spheres modified with positive surface charge:

[0037] 0.5g of positively charged polystyrene spheres were added to an aqueous solution of a 3‰ mass fraction of Gemini quaternary ammonium salt cationic surfactant, and stirred at 60℃ for 24h. Then, the mixture was centrifuged and dried at 80℃ to obtain positively charged polystyrene spheres.

[0038] S2. Preparation of silica sol solution: Add 0.8 mL of ammonia to a mixed solvent consisting of 80 mL of anhydrous ethanol and 7.5 mL of water, and stir for 20 min under sealed conditions to obtain solution A; then add 12.5 mL of tetraethyl orthosilicate to solution A at a dropping rate of 0.02 mL / min. After the addition is complete, stir vigorously for 24 h to obtain (classical) silica sol solution.

[0039] S3. Preparation of single-pore hollow silica spheres: Add 0.10g of surface positively charged polystyrene spheres to 8mL of silica sol solution and sonicate for 10min. Then, electrostatic spray granulation is performed on the ultrasonically treated solution. The specific parameters are set as follows: voltage: positive voltage 20-25kV, spinning distance 25-30cm, injection rate 0.3-0.5mL / h, temperature 30℃, humidity 30%. Finally, the powder obtained after granulation is calcined at 500℃ for 1h to obtain single-pore hollow silica spheres.

[0040] Example 2

[0041] A method for preparing a single-aperture hollow silicon sphere, comprising the following steps:

[0042] S1. Preparation of polystyrene spheres modified with positive surface charge:

[0043] 0.8 g of positively charged polystyrene spheres were added to an aqueous solution of a 1‰ mass fraction of Gemini quaternary ammonium salt cationic surfactant, and stirred at 40 °C for 24 h. The mixture was then centrifuged and dried at 80 °C to obtain positively charged polystyrene spheres.

[0044] S2. Preparation of silica sol solution: Add 0.8 mL of ammonia to a mixed solvent consisting of 80 mL of anhydrous ethanol and 7.5 mL of water, and stir for 20 min under sealed conditions to obtain solution A; then add 12.5 mL of tetraethyl orthosilicate to solution A at a dropping rate of 0.05 mL / min. After the addition is complete, stir vigorously for 18 h to obtain (classical) silica sol solution.

[0045] S3. Preparation of single-pore hollow silica spheres: Add 0.12g of surface positively charged polystyrene spheres to 8mL of silica sol solution and sonicate for 10min. Then, electrostatic spray granulation is performed on the ultrasonically treated solution. The specific parameters are set as follows: voltage: positive voltage 20-25kV, spinning distance 25-30cm, injection rate 0.3-0.5mL / h, temperature 30℃, humidity 30%. Finally, the powder obtained after granulation is calcined at 500℃ for 1h to obtain single-pore hollow silica spheres.

[0046] Example 3

[0047] A method for preparing a single-aperture hollow silicon sphere, comprising the following steps:

[0048] S1. Preparation of polystyrene spheres modified with positive surface charge:

[0049] 1.2g of positively charged polystyrene spheres were added to an aqueous solution of a 5‰ mass fraction of Gemini quaternary ammonium salt cationic surfactant, stirred at 50℃ for 20h, then centrifuged and dried at 80℃ to obtain positively charged polystyrene spheres.

[0050] S2. Preparation of silica sol solution: Add 1 mL of ammonia to a mixed solvent consisting of 80 mL of anhydrous ethanol and 7.5 mL of water, and stir for 20 min under sealed conditions to obtain solution A; then add 12.5 mL of tetraethyl orthosilicate to solution A at a dropping rate of 0.02 mL / min. After the addition is complete, stir vigorously for 24 h to obtain (classical) silica sol solution.

[0051] S3. Preparation of single-pore hollow silica spheres: Add 0.06g of surface positively charged modified polystyrene spheres to 8mL of silica sol solution and sonicate for 10min. Then, perform electrostatic spray granulation on the solution obtained after ultrasonic treatment. The specific parameters are set as follows: voltage: positive voltage 20-25kV, spinning distance 25-30cm, injection rate 0.3-0.5mL / h, temperature 30℃, humidity 30%. Finally, the powder obtained after granulation is calcined at 500℃ for 1h to obtain single-pore hollow silica spheres.

[0052] Example 4

[0053] A method for preparing a single-aperture hollow silicon sphere, comprising the following steps:

[0054] S1. Preparation of surface positive charge modified polystyrene spheres: The steps are the same as in Example 1, to obtain surface positive charge modified polystyrene spheres;

[0055] S2. Preparation of silica sol solution: Add 0.6 mL of ammonia to a mixed solvent consisting of 100 mL of anhydrous ethanol and 8.5 mL of water, and stir for 10 min under sealed conditions to obtain solution A; then add 12.5 mL of tetraethyl orthosilicate to solution A at a dropping rate of 0.01 mL / min. After the addition is complete, stir vigorously for 18 h to obtain (classical) silica sol solution.

[0056] S3. Preparation of single-pore hollow silica spheres: Add 0.1g of surface positively charged polystyrene spheres to 8mL of silica sol solution and sonicate for 10min. Then, electrostatic spray granulation is performed on the ultrasonically treated solution. The specific parameters are set as follows: voltage: positive voltage 20-25kV, spinning distance 25-30cm, injection rate 0.3-0.5mL / h, temperature 30℃, humidity 30%. Finally, the powder obtained after granulation is calcined at 600℃ for 2h to obtain single-pore hollow silica spheres.

[0057] Example 5

[0058] A method for preparing a single-aperture hollow silicon sphere, comprising the following steps:

[0059] S1. Preparation of surface positive charge modified polystyrene spheres: The steps are the same as in Example 1, to obtain surface positive charge modified polystyrene spheres;

[0060] S2. Preparation of silica sol solution: Add 0.8 mL of ammonia to a mixed solvent consisting of 70 mL of anhydrous ethanol and 6.2 mL of water, and stir for 15 min under sealed conditions to obtain solution A; then add 12.5 mL of tetraethyl orthosilicate to solution A at a dropping rate of 0.05 mL / min. After the addition is complete, stir vigorously for 20 h to obtain (classical) silica sol solution.

[0061] S3. Preparation of single-pore hollow silica spheres: Add 0.10g of surface positively charged polystyrene spheres to 8mL of silica sol solution and sonicate for 10min. Then, electrostatic spray granulation is performed on the ultrasonically treated solution. The specific parameters are set as follows: voltage: positive voltage 20-25kV, spinning distance 25-30cm, injection rate 0.3-0.5mL / h, temperature 30℃, humidity 30%. Finally, the powder obtained after granulation is calcined at 800℃ for 3h to obtain single-pore hollow silica spheres.

[0062] Comparative Example 1

[0063] The steps are basically the same as in Example 1, except that the "positively charged polystyrene spheres" in step S1 are replaced with "negatively charged polystyrene spheres" (see Example 1). Figure 3 Additionally, the method involved replacing the polystyrene spheres with "uncharged polystyrene spheres" and directly replacing the "positively charged polystyrene spheres" in step S3 with "positively charged polystyrene spheres". The final result was a hollow silicon sphere without openings.

[0064] Comparative Example 2

[0065] The steps are basically the same as in Example 1, except that the "gemini quaternary ammonium salt cationic surfactant" in step S1 is replaced with "octadecyltrimethylammonium chloride", and the resulting silicon spheres break open (see Example 1). Figure 4 ).

[0066] Comparative Example 3

[0067] The steps are basically the same as in Example 1, except that the "gemini quaternary ammonium salt cationic surfactant" in step S1 is replaced with "hexadecyl dimethyl benzyl ammonium chloride", and finally hollow silicon spheres that cannot be opened are obtained (see below). Figure 5 ).

[0068] The single-aperture hollow silicon spheres prepared in Example 1 and the silicon spheres prepared in Comparative Examples 1-3 were characterized, and the obtained SEM images are shown below. Figure 1-5 As shown.

[0069] Depend on Figure 1-2 The results show that the hollow silicon spheres prepared in Example 1 of this invention have a single-hole plum-like morphology.

[0070] Depend on Figure 3 The results show that in Comparative Example 1, replacing "positively charged polystyrene spheres" with "negatively charged polystyrene spheres" resulted in the final silica spheres being conventional, non-porous hollow silica spheres.

[0071] Depend on Figure 4 The results show that the silica spheres prepared in Comparative Example 2 broke open and did not form a single-opening structure.

[0072] Depend on Figure 5 The results show that Comparative Example 3 produced hollow silica spheres that did not form a single-opening structure.

[0073] In this invention, the surface electrical modification of polystyrene spheres is the core key to preparing single-pore hollow silica spheres. Experimental results demonstrate that when using "uncharged polystyrene spheres," "negatively charged polystyrene spheres," or "unmodified positively charged polystyrene spheres," and when using conventional cationic surfactants such as octadecyltrimethylammonium chloride or hexadecyldimethylbenzylammonium chloride instead of "gemini quaternary ammonium salt cationic surfactants" to modify polystyrene spheres as hard templates, non-pore-forming hollow silica spheres or broken-shell hollow silica spheres are ultimately obtained. In other words, the positive charge on the surface-charged polystyrene spheres needs to be further increased. Because the electropositivity of commercially available positively charged polystyrene spheres is insufficient, a single-pore structure cannot be formed. Furthermore, using ordinary cationic surfactants to modify polystyrene spheres still results in insufficient electropositivity, preventing the formation of a single-pore structure and potentially leading to system instability.

[0074] Fragrance sustained release experiment

[0075] A fragrance sustained-release experiment was conducted using the single-aperture hollow silicon sphere prepared in Example 1, the non-aperture hollow silicon sphere prepared in Comparative Example 1, and the broken-shell silicon sphere prepared in Comparative Example 2.

[0076] Specific steps: (1) Select 100ml of commercially available 10% rose essence, add 5g of the above-mentioned single-hole hollow silica balls, non-hole hollow silica balls, and broken-shell silica balls, stir for 3h, centrifuge, and dry; (2) Weigh 1g of single-hole hollow silica balls, non-hole hollow silica balls, and broken-shell silica balls and add them to 10ml of deionized water, stir thoroughly, then pour them onto 20g of pure cotton socks and dry at 80℃ for 3h; (3) Refer to GBT14765-93 (Air Quality, Three-Point Comparison Odor Bag Method) to conduct human olfactory organ testing. The fragrance settings are divided into five levels from high to low: strong, strong, normal, weak, and very weak. The results are shown in Table 1 below.

[0077] Table 1

[0078]

[0079] The results in Table 1 show that the single-pore hollow silicon spheres prepared by the present invention have good functional material loading and sustained release effects, and can smoothly load fragrances into the internal space for sustained release. Similarly, they can also be used in functional materials such as drugs and catalysts.

[0080] This invention is not limited to the specific embodiments described above. Any modifications made by those skilled in the art based on the above concept without creative effort are within the scope of protection of this invention.

Claims

1. A method for preparing a single-aperture hollow silicon sphere, characterized in that, Includes the following steps: S1. Preparation of surface-positively charged modified polystyrene spheres: Positively charged polystyrene spheres were added to an aqueous solution of a Gemini quaternary ammonium salt cationic surfactant, stirred and reacted at a certain temperature, and purified to obtain positively charged polystyrene spheres. The mass ratio of the positively charged polystyrene spheres to the Gemini quaternary ammonium cationic surfactant is 5-12:0.0005-0.006; The temperature of the stirring reaction is 40-60℃, and the stirring reaction time is 18-24h; S2. Preparation of silica sol solution: Add ammonia to a mixture of anhydrous ethanol and water, stir until homogeneous to obtain solution A; then add tetraethyl orthosilicate to solution A, stir to react, and obtain silica sol solution; S3. Preparation of single-aperture hollow silicon spheres: S31. The obtained surface positive charge modified polystyrene spheres are added to a silica sol solution and ultrasonically treated. S32. The ultrasonically treated solution is subjected to electrostatic spray granulation and high-temperature calcination to obtain single-pore hollow silicon spheres. The experimental parameters for electrostatic spray granulation are: positive voltage 20-25kV, spinning distance 25-30cm, injection rate 0.3-0.5mL / h, temperature 30℃, and humidity 30%.

2. The method for preparing a single-aperture hollow silicon sphere according to claim 1, characterized in that, In step S2, the volume ratio of ammonia to tetraethyl orthosilicate is 0.6-1:12.

5.

3. The method for preparing a single-aperture hollow silicon sphere according to claim 1, characterized in that, In step S2, the tetraethyl orthosilicate is added by dropping, with a dropping rate of 0.01-0.05 mL / min; the stirring reaction time is 10-20 min.

4. The method for preparing a single-aperture hollow silicon sphere according to claim 1, characterized in that, In step S2, the volume ratio of anhydrous ethanol to water in the anhydrous ethanol and water mixed solvent is 70-100:6-8.

5. The method for preparing a single-aperture hollow silicon sphere according to claim 1, characterized in that, In step S3, the high-temperature calcination temperature is 500-800℃, and the calcination time is 1-3h.

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