Hydrophilic monodisperse silicon microsphere and preparation method thereof

Abstract

The invention relates to a hydrophilic monodisperse silicon microsphere and a preparation method thereof, and belongs to the technical field of silicon dioxide microsphere preparation. According to the method, a Stber method based on sol-gel is utilized, ethanol is taken as a solvent, hydrolytic condensation is performed in ammonia water, and the silicon microspheres with target particle sizes are directly generated by regulating and controlling all reaction conditions. The silicon microspheres are subjected to high-temperature roasting, so that residual moisture and organic impurities are removed, the purity is improved, further growth and maturation of crystals are promoted, and the crystallinity and stability of the crystals are improved. And forming a self-assembled single layer on the surface of the silicon microsphere by using a thiol analogue, thereby further improving the hydrophilicity of the silicon microsphere.

Description

Technical Field

[0001] The invention belongs to the technical field of silicon dioxide microsphere preparation, and relates to hydrophilic monodisperse silicon microspheres and a preparation method thereof. Background Art

[0002] Spherical silica ( ) is a widely used material. Due to its excellent chemical stability, high surface area, good mechanical properties and thermal stability, it is widely used in catalyst supports, adsorbents, electronic devices, medical imaging and other fields. The micron or nanometer particle size of spherical silica gives it special surface properties, which can provide greater reactivity and better dispersibility. In materials science, especially in the field of nanotechnology, the preparation and application of spherical silica have attracted much attention. By adjusting its particle size and surface properties, its performance in different applications can be significantly changed, such as improving catalytic activity, improving water solubility or enhancing biocompatibility. Therefore, the preparation of monodisperse silica microspheres with controllable particle size and surface properties has become a research focus.

[0003] Common processes for synthesizing spherical silica include the microemulsion method, the vapor-phase chemical method, and the Stöber method. The microemulsion method utilizes surfactants to form a microemulsion between an aqueous and oily phase. This method, by controlling the reaction environment, can produce silica particles with uniform particle size and good dispersion. The vapor-phase chemical method converts a gaseous silicon source into solid silicon via chemical vapor deposition (CVD) under high-temperature conditions to produce silica particles. This method generally produces high-purity, impurity-free silica, but the process is complex and costly. The Stöber method synthesizes silica particles in solution via hydrolysis and condensation reactions. In this method, a silane compound (such as tetraethoxysilane) is hydrolyzed in a water-alcohol mixed solvent using an acid- or base-catalyzed reaction. A further condensation reaction then polymerizes to form silicon-oxygen bonds, ultimately yielding silica particles. The Stöber method offers advantages such as precise particle size control, simplicity, and low cost, making it one of the most widely used preparation methods.

[0004] While existing synthesis methods each offer their own advantages, they still have certain shortcomings. First, the microemulsion method requires the use of large amounts of surfactants, which can result in the presence of organic impurities in the product, affecting the purity and subsequent applications of the material. While the vapor-phase chemical method can produce high-purity silica, its high cost and complex experimental equipment limit its application in large-scale production. While the Stöber method offers lower costs and greater controllability, the silica particles produced are typically smooth and lack hydrophilicity, limiting their dispersibility and stability in aqueous media. Furthermore, while existing preparation methods can achieve a certain degree of precision in particle size control, there are still gaps in particle size distribution uniformity and particle monodispersity, placing higher demands on certain high-precision applications such as biomedicine and nanosensors. Therefore, improving the hydrophilicity, surface uniformity, and stability of silica particles while maintaining low cost remains a difficult and challenging task in current research. Summary of the Invention

[0005] The present invention relates to a method for preparing silicon microspheres, in particular to a method for preparing hydrophilic monodisperse silicon microspheres.

[0006] The purpose of the present invention can be achieved through the following technical solutions: The invention discloses hydrophilic monodisperse silicon microspheres, comprising the following raw materials in parts by weight: 5-7 parts by weight of a hydrolyzate, 7-9 parts by weight of a silicon source solution, and 0.01-0.1 parts by weight of a thiol analogue.

[0007] As a preferred technical solution of the present invention, the hydrolysis solution is ammonia water, deionized water and anhydrous ethanol, and the mass ratio of ammonia water, deionized water and anhydrous ethanol is 0.8-2.4:0.3-2.2:4.5-7.7.

[0008] As a preferred technical solution of the present invention, the silicon source liquid comprises tetraethoxysilane, a dispersant and anhydrous ethanol, and the mass ratio of the tetraethoxysilane, the dispersant and the anhydrous ethanol is 1:0.01-0.03:4.5-9.

[0009] As a preferred technical solution of the present invention, the thiol analogue is at least one of 3-mercaptopropionic acid and undecanethiol.

[0010] Furthermore, the method for preparing the hydrophilic monodisperse silica microspheres comprises the following steps: (1) Stir the hydrolyzate at 240-300 rpm for 30-60 min and keep it at 35-45°C; (2) In another stirring container, stir the silicon source solution at 240-300 rpm for 10-20 minutes and keep the temperature at 35-45°C; (3) Pour the silicon source solution into the hydrolyzed solution while stirring, and stir for 5-7 hours to form a reaction solution with silicon microspheres with a particle size of 200-600 nm; (4) The reaction solution was centrifuged, and the retained solid was dried and then calcined at 600-800 °C for 6-8 h and then pulverized to obtain monodispersed 200-600 nm silicon microspheres; (5) treating the silicon microspheres with acid or alkali to increase the surface hydroxyl groups, and then drying to obtain pretreated silicon microspheres; (6) The pretreated silica microspheres are immersed in a thiol analogue ethanol solution for 10-20 hours and ultrasonically treated for 30-60 minutes. Hydrophilic monodisperse silica microspheres are obtained by washing and vacuum drying.

[0011] As a preferred technical solution of the present invention, the acid treatment step is to place the silicon microspheres in a 0.1-1M hydrochloric acid solution or a 0.1-0.5M nitric acid solution at 20-50°C and stir for 0.5-2h; the alkali treatment step is to place the silicon microspheres in a 0.1-0.5M sodium hydroxide solution at 20-60°C and stir for 0.5-1h.

[0012] As a preferred technical solution of the present invention, the concentration of the thiol analogue ethanol solution is 0.1-10 mM.

[0013] Beneficial effects of the present invention: (1) The present invention uses the Stöber method to prepare nano-silica particles with controllable particle size. Silane compounds undergo hydrolysis in a water-alcohol mixed solvent under the action of an acid or base catalyst to generate silanols ( ) intermediates, which then undergo a condensation reaction to form silicon-oxygen bonds and gradually aggregate into silica particles. As the reaction proceeds, the particles gradually increase in size. Therefore, by adjusting synthesis parameters such as stirring speed, amount of silicon source, and amount of ammonia, the particle size of nano-silica can be precisely controlled.

[0014] (2) The cost of preparing nano-silica by the Stöber method is relatively low. The raw materials used are relatively cheap and are common chemical reagents that are easily available. At the same time, the experimental process is simple to operate, the preparation efficiency is high, and it is easy to control and scale up production.

[0015] (3) High-temperature calcination can effectively remove organic residues and other impurities, improving the purity of nano-silica. The calcination process can promote the structural rearrangement of nano-silica, improving the crystallinity and structural stability of the material. Higher crystallinity is usually accompanied by better mechanical properties and thermal stability, which is particularly important for certain applications (such as catalyst supports or high-temperature resistant materials).

[0016] (4) The present application forms a self-assembled monolayer on the surface of the silicon microspheres by using the thiol analogues, and further improves the hydrophilicity of the silicon microspheres. The thiol analogues generally have a terminal sulfhydryl group (-SH) with high chemical activity, and can form strong bonding with many surfaces; the thiol molecules spontaneously arrange on the surface of the silicon microspheres to form a tightly ordered monolayer, the formation of the self-assembled monolayer changes the chemical composition and physical properties of the surface of the silicon microspheres, reduces the surface energy, so that water molecules are more easily spread on the surface, and the improved hydrophilicity can improve the dispersibility and stability of the silicon microspheres in the aqueous medium, and enhance the performance of the silicon microspheres in the fields of biomedicine, catalysis and sensors. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to facilitate the understanding of those skilled in the art, the present application will be further described below in conjunction with the drawings.

[0018] Figure 1 The sample prepared for Example 1 is shown in the electron microscope magnification graph; Figure 2 The sample prepared for Example 1 is shown in the water contact angle graph; Figure 3 The sample prepared for Example 2 is shown in the electron microscope magnification graph; Figure 4 The sample prepared for Example 2 is shown in the water contact angle graph; Figure 5 The sample prepared for the comparative example is shown in the electron microscope magnification graph; Figure 6 The sample prepared for the comparative example is shown in the water contact angle graph. DETAILED DESCRIPTION

[0019] In order to further illustrate the technical means and effects adopted by the present application to achieve the predetermined application purposes, the specific embodiments, structures, features and effects according to the present application are described in detail below in conjunction with the drawings and preferred embodiments.

[0020] Example 1 A hydrophilic monodisperse silicon microsphere comprises the following raw materials by weight: 6 parts by weight of a hydrolysis solution, 8 parts by weight of a silicon source solution, and 0.05 parts by weight of a thiol analogue.

[0021] The hydrolysis solution is ammonia, deionized water and anhydrous ethanol, and the mass ratio of the ammonia, deionized water and anhydrous ethanol is 1.6:1.3:6.

[0022] The silicon source solution is tetraethoxysilane, a dispersing agent and anhydrous ethanol, and the mass ratio of the tetraethoxysilane, the dispersing agent and the anhydrous ethanol is 1:0.02:7.

[0023] The thiol analogue is 3-mercaptopropionic acid.

[0024] The preparation method of the hydrophilic monodisperse silicon microspheres comprises the following steps: (1) stir the hydrolysis liquid at 260 rpm for 45 min and keep the temperature at 40℃; (2) stir the silicon source liquid in another stirring container at 260 rpm for 15 min and keep the temperature at 40℃; (3) pour the silicon source liquid into the hydrolysis liquid under stirring, stir for 6 h, and form a silicon microsphere reaction liquid; (4) centrifuge the reaction liquid, dry the solid, and then crush the solid after high-temperature calcination at 700℃ for 7 h to obtain silicon microspheres with a particle size of about 500-550 nm; (5) treat the silicon microspheres with acid or alkali to increase the surface hydroxyl groups, and then dry to obtain pretreated silicon microspheres; (6) immerse the pretreated silicon microspheres in a thiol analogue ethanol solution, soak for 15 h, and ultrasonically treat for 45 min, and then obtain the hydrophilic monodisperse silicon microspheres through washing and vacuum drying.

[0025] As a preferred technical solution of the present application, the acid treatment in step (5) is stirring the silicon microspheres in a 0.5M hydrochloric acid solution at 30℃ for 1 h; and the alkali treatment is stirring the silicon microspheres in a 0.3M sodium hydroxide solution at 40℃ for 45 min.

[0026] The concentration of the thiol analogue ethanol solution is 5 mM.

[0027] Example 2 A hydrophilic monodisperse silicon microsphere comprises the following raw materials by weight: 6 parts by weight of a hydrolysis liquid, 9 parts by weight of a silicon source liquid, and 0.03 parts by weight of a thiol analogue.

[0028] The hydrolysis liquid is ammonia water, deionized water, and anhydrous ethanol, and the mass ratio of the ammonia water, deionized water, and anhydrous ethanol is 1.6:1.3:6.

[0029] The silicon source liquid is tetraethoxysilane, a dispersing agent, and anhydrous ethanol, and the mass ratio of the tetraethoxysilane, the dispersing agent, and the anhydrous ethanol is 1:0.02:7.

[0030] The thiol analogue is 3-mercaptopropionic acid.

[0031] The preparation method of the hydrophilic monodisperse silicon microspheres comprises the following steps: (1) stir the hydrolysis liquid at 260 rpm for 45 min and keep the temperature at 40℃; (2) stir the silicon source liquid in another stirring container at 260 rpm for 15 min and keep the temperature at 40℃; (3) pour the silicon source liquid into the hydrolysis liquid under stirring, stir for 7 h, and form a silicon microsphere reaction liquid; (4) centrifuging the reaction solution, drying the solid, and then crushing the solid after calcination at 700 DEG C for 7 hours to obtain monodisperse 560-600 nm silica microspheres; (5) treating the silica microspheres with acid or alkali to increase the surface hydroxyl groups, and drying to obtain pretreated silica microspheres; (6) immersing the pretreated silica microspheres in a thiol analogue ethanol solution, soaking for 15 hours, and ultrasonic treatment for 45 minutes, and then obtaining hydrophilic monodisperse silica microspheres by washing and vacuum drying.

[0032] As a preferred technical solution of the present application, the acid treatment is stirring the silica microspheres in a 0.5 M hydrochloric acid solution at 30 DEG C for 1 hour; and the alkali treatment is stirring the silica microspheres in a 0.3 M sodium hydroxide solution at 40 DEG C for 45 minutes.

[0033] The concentration of the thiol analogue ethanol solution is 5 mM.

[0034] Comparative Example Based on Example 2, steps (5) and (6) are not performed, and the rest is consistent with Example 1.

[0035] Performance Test The particle size of the sample is measured by a scanning electron microscope (SEM) image; The static contact angle of a water droplet on the surface of the sample is measured by a contact angle measuring instrument.

[0036] As can be seen from the test results and the accompanying drawings, the present application can prepare silica microspheres with a target particle size by controlling the components and the reaction, and the particle size is uniform, and the self-assembled monolayer of the thiol analogue on the surface of the silica microspheres significantly improves the hydrophilicity of the silica microspheres.

[0037] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Although the present application has been disclosed as above with a preferred embodiment, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content without departing from the scope of the technical solution of the present application, and any brief introduction, modification, equivalent change and modification of the above embodiments based on the technical essence of the present application are still within the scope of the technical solution of the present application.

Claims

1. A method for preparing hydrophilic monodisperse silicon microspheres, characterized by: The following steps are involved: (1) Providing a hydrolysis solution comprising ammonia water, deionized water and anhydrous ethanol; (2) providing a silicon source solution comprising tetraethoxysilane, a dispersant and anhydrous ethanol; (3) adding the silicon source solution prepared in step (2) to the hydrolyzed solution in step (1) while stirring, and fully dispersing the solution to form a silicon microsphere reaction solution; (4) centrifuging the reaction solution of step (3), retaining the solid, calcining it, and then crushing it to obtain silicon microspheres; (5) treating the silicon microspheres with acid or alkali, and drying them to obtain pretreated silicon microspheres; (6) The pretreated silica microspheres were immersed in an ethanol solution of a thiol analogue and ultrasonically treated, and hydrophilic monodispersed silica microspheres were obtained by washing and vacuum drying.

2. The hydrophilic monodisperse silica microspheres according to claim 1, characterized in that: The mass ratio of the hydrolyzate, the silicon source solution, and the thiol analogue is 5-7:7-9:0.01-0.

1.

3. The hydrophilic monodisperse silica microspheres according to claim 1, characterized in that: The hydrolysis solution in step (1) has a mass ratio of 0.8-2.4:0.3-2.2:4.5-7.7 among the ammonia water, deionized water and anhydrous ethanol.

4. The hydrophilic monodisperse silicon microspheres according to claim 1, characterized in that: The silicon source liquid in step (2) is tetraethoxysilane, a dispersant and anhydrous ethanol, and the mass ratio of the tetraethoxysilane, the dispersant and the anhydrous ethanol is 1:0.01-0.03:4.5-9.

5. The hydrophilic monodisperse silica microspheres according to claim 1, characterized in that: The high-temperature calcination temperature in step (4) is 600-800°C, and the calcination time is 6-8h; the particle size of the silicon microspheres is 200-600 nm.

6. The hydrophilic monodisperse silica microspheres according to claim 1, characterized in that: The thiol analogue in step (6) is at least one of 3-mercaptopropionic acid and undecanethiol.

7. The method for preparing hydrophilic monodisperse silicon microspheres according to claim 1, wherein: The acid treatment step is: immersing the silicon microspheres in a 0.1-1M hydrochloric acid solution or a 0.1-0.5M nitric acid solution at 20-50°C for 0.5-2h; the alkali treatment step is: immersing the silicon microspheres in a 0.1-0.5M sodium hydroxide solution at 20-60°C for 0.5-1h.

8. The method for preparing hydrophilic monodisperse silicon microspheres according to claim 1, wherein: The concentration of the thiol analogue ethanol solution is 0.1-10 mM.

9. A silicon microsphere, characterized in that: Obtained by the preparation method of the hydrophilic monodisperse silicon microspheres according to claim 1.

10. A use of the silicon microspheres according to claim 1, characterized in that: Used in biomedical materials, catalysts and sensor materials.

Images