Mesoporous silica microsphere with adjustable pore structure and particle size as well as preparation method and application of mesoporous silica microsphere

Abstract

The invention discloses mesoporous silica microspheres with adjustable pore structures and particle sizes and a preparation method and application of the mesoporous silica microspheres, and belongs to the technical field of nano materials. Adding a metered surfactant, a metered polymer emulsion and a metered settling agent into water, and uniformly mixing to obtain a pre-solution; adding metered tetraethyl orthosilicate into the preposed solution, and continuously stirring to fully react; and after the reaction is finished, centrifuging, washing and post-treating to obtain a product, namely the mesoporous silica. The mesoporous silica microspheres prepared by the method can be used in the fields of new energy batteries, cosmetics, skin care products, daily chemical products and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of nanomaterials, and particularly relates to a mesoporous silica microsphere with a controllable pore structure and particle size, and a preparation method and application thereof. Background Art

[0002] Mesoporous silica has shown various uses in daily chemical products due to its controllable pore structure, high specific surface area, and high oil absorption value. It can achieve the targeted release or slow release of active ingredients such as drugs, active components, and fragrances by surface modification and pore size regulation, extending the effect and lifespan of the product. Its high specific surface area and oil absorption value enable it to effectively adsorb oils and other small molecules, enhancing the oil control effect, and it can also be used as a carrier for ultraviolet absorbers in sunscreen products to improve the sunscreen performance.

[0003] In the field of lithium batteries, traditional anode materials such as lithium-based materials and graphene have their respective limitations, such as the dendritic tendency of lithium metal and the low theoretical specific capacity of graphene. Mesoporous silica, with its hierarchical pore structure, not only helps the penetration of the electrolyte and the transport of lithium ions, but also effectively prevents the formation of lithium dendrites, significantly improving the safety and performance of the battery. Therefore, mesoporous silica shows great potential to become a high-performance anode material for lithium batteries.

[0004] In materials science, the specific surface area is an important parameter for measuring the surface area possessed by a unit mass of material, and it has a crucial impact on the performance and application fields of the material. Especially for mesoporous silica with a hierarchical pore structure, the size of the specific surface area directly determines its functional characteristics and application effects.

[0005] In adsorption and separation technologies, a higher specific surface area provides more active sites, significantly increasing the contact area with adsorbed molecules, thus significantly enhancing the adsorption efficiency of the material for target substances. In environmental governance, this high adsorption capacity is particularly important and can be used to capture and remove pollutants in water or gas. In addition, in the field of catalysis, the increase in specific surface area provides more sufficient contact and reaction space for reactant molecules, enabling the catalyst to fully play its role, accelerating the chemical reaction rate, and improving the catalytic efficiency. At the same time, the high specific surface area can also provide more sites for various functionalization modifications, thereby enhancing the selectivity and reaction stability of the material.

[0006] Therefore, for mesoporous silica materials, a high specific surface area is not only the basis of their excellent performance but also the key to their wide application in fields such as adsorption, separation, and catalysis. This characteristic makes it show great application potential in industries such as energy, environment, and chemical engineering.

[0007] The mesoporous silica produced currently faces the following problems in practical applications: Its preparation process usually requires strict control of conditions (such as temperature, pH value, and type of template agent), resulting in a complex process and high cost. In addition, the specific surface area and pore size distribution stability of some materials are insufficient, restricting their performance in the fields of adsorption, separation, and catalysis.

[0008] The common template methods for preparing mesoporous silica can be divided into hard template method and soft template method. The hard template method uses solid substances as rigid templates, deposits the target material through physical coating, and finally removes the template to form a fixed morphology. The hard template method can precisely replicate the shape and size of the hard template, is suitable for preparing single and uniform nano / microstructures, and the rigid template supports the structure during the synthesis process, being suitable for preparing easily deformable materials. However, the removal of the hard template requires the use of strong acids, high-temperature calcination, or corrosive solvents to remove the template, which may damage the structure of the final product or introduce impurities. It is usually difficult to achieve complex hierarchical pores or multi-scale composite structures.

[0009] The core characteristics of the soft template method are the self-repair and dynamic adjustment capabilities of the template. Using dynamic templates such as surfactant micelles, polymer self-assemblies, or liquid crystals, the directional growth of materials is guided through non-covalent bonds to form ordered mesopores or hierarchical structures. Complex mesopores, layered, or three-dimensional interconnected structures can be formed through the soft template method to meet diverse requirements such as catalysis and drug carriers. At the same time, the template synthesis step is omitted, and the self-assembly process can be achieved through the solution. However, the dynamic template is easily interfered by factors such as temperature, pH, and concentration, resulting in structural deformation or disorder. To achieve the target structure, it is often necessary to finely regulate the solution parameters, and it is difficult to completely remove some soft templates. Summary of the Invention

[0010] The objective of the present invention is to solve the deficiencies of the prior art, and provide a mesoporous silica microsphere with a controllable pore structure and particle size, its preparation method and application. A polymer emulsion containing polymer nanoparticles with a size of 10 - 20 nm and a surfactant are used to jointly manufacture the mesoporous silica microsphere, and at the same time, the structural properties of the material are optimized, including enhancing the specific surface area, uniformly controlling the pore size distribution, and enhancing its stability in complex environments to better meet the requirements of industrial applications.

[0011] To solve the above technical problems, the present invention adopts the following technical solution: A preparation method of a mesoporous silica microsphere with a controllable pore structure and particle size, comprising the following steps:

[0012] (1) Add a surfactant, a polymer emulsion, and a precipitant into water, and mix them evenly to obtain a pre-solution;

[0013] (2) Add tetraethyl orthosilicate into the pre-solution to obtain a mixed solution, and continue to stir and react at a temperature of 10 - 70 °C for 2 - 48 h;

[0014] (3) After the reaction is completed, through separation, washing, and post-treatment, a powdery sample is obtained, which is the target product.

[0015] Furthermore, the surfactant described in step (1) is at least one of cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, tetradecyltrimethylammonium bromide, tetradecyltrimethylammonium chloride, and tetradecyldimethylbenzylammonium chloride, and the concentration of the surfactant in the pre-solution is 0.01% - 10%.

[0016] Furthermore, the polymer emulsion described in step (1) is one or a mixture of styrene-acrylic emulsion and styrene-butadiene rubber emulsion, and the concentration in the pre-solution is 1% - 10%.

[0017] Furthermore, the precipitant described in step (1) is triethanolamine, and the concentration in the pre-solution is 1% - 10%.

[0018] Furthermore, the concentration of tetraethyl orthosilicate described in step (2) in the mixed solution is 1% - 20%.

[0019] Furthermore, the post-treatment described in step (3) is calcination at a temperature of 400 - 900 °C for 4 - 24 h.

[0020] The present invention utilizes a polymer emulsion containing polymer nanoparticles with a size of 10 - 20 nm and a surfactant to synergistically fabricate mesoporous silica microspheres. When the polymer emulsion is added to the reaction system, the nanoparticles are embedded in the material to form pores, and after high-temperature calcination, a mesoporous material with a hollow structure is formed. Compared with the method using small molecule templates, the polymer emulsion template can not only prepare mesoporous silica microspheres with larger pore diameters, but also synthesize mesoporous silica microspheres with controllable pore diameters and particle sizes by adjusting the types and ratios of the surfactant and the polymer emulsion.

[0021] The present invention also provides mesoporous silica microspheres with a controllable pore structure and particle size prepared by the above preparation method. By adjusting the ratio and type of the surfactant and the polymer emulsion, mesoporous silica microspheres with a uniform pore or hierarchical pore structure and controllable size can be prepared, with an oil absorption value of 200 - 620 mL / 100 g and a specific surface area of 1000 - 1500 m 2 / g.

[0022] The third aspect of the present invention is to provide the application of the above mesoporous silica microspheres in the fields of new energy batteries, cosmetics, skin care products, and daily chemical products.

[0023] The synthesis of mesoporous silica is affected by various factors, including surfactant type, emulsion type, solution pH value, reaction temperature, and reaction time, etc. These parameters will have a significant impact on the interaction between the template and silicon species, the condensation rate of silica, and the growth process. Therefore, by adjusting reaction conditions, such as temperature or surfactant selection, the size and pore diameter of silica microspheres can be effectively controlled to meet the requirements of different applications.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] The technical method of the present invention is applicable to a wide temperature range, enabling the synthesis of mesoporous silica microspheres with ultra-high oil absorption values and specific surface areas under different temperature conditions. By adjusting the reaction temperature and surfactant type, the product performance can be further optimized to prepare mesoporous silica microspheres with smaller particle sizes, higher oil absorption values, and larger specific surface areas. In addition, this method is simple to operate, has mild reaction conditions, high safety, and low operation risks. Description of the Drawings

[0026] Figure 1 It is a sample diagram of the mesoporous silica microspheres prepared in Example 1.

[0027] Figure 2 It is a scanning electron microscope image of the mesoporous silica microspheres prepared in Example 1.

[0028] Figure 3 . It is a high-magnification scanning electron microscope image of the mesoporous silica microspheres prepared in Example 1.

[0029] Figure 4 . It is the nitrogen adsorption-desorption isotherm curve of the mesoporous silica microspheres in Example 1.

[0030] Figure 5 It is the pore size distribution diagram of the mesoporous silica microspheres in Example 1.

[0031] Figure 6 It is a scanning electron microscope image of the mesoporous silica microspheres prepared in Example 2.

[0032] Figure 7 It is a high-magnification scanning electron microscope image of the mesoporous silica microspheres prepared in Example 2.

[0033] Figure 8 It is a scanning electron microscope image of the mesoporous silica microspheres prepared in Example 3.

[0034] Figure 9 It is a high-magnification scanning electron microscope image of the mesoporous silica microspheres prepared in Example 3.

[0035] Figure 10It is the nitrogen adsorption - desorption curve of the mesoporous silica microspheres prepared in Example 3.

[0036] Figure 11 It is the pore size distribution diagram of the mesoporous silica microspheres prepared in Example 3.

[0037] Figure 12 It is the scanning electron microscope image of the mesoporous silica microspheres prepared in Example 4.

[0038] Figure 13 It is the scanning electron microscope image of the mesoporous silica microspheres prepared in Example 5. Detailed implementation manners

[0039] Combined with the embodiments below, the technical solutions of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without making creative efforts belong to the scope of protection of the present invention.

[0040] Example 1

[0041] This example provides a preparation method of mesoporous silica microspheres with adjustable pore structure and particle size, including the following steps:

[0042] (1) Dissolve tetradecyldimethylbenzylammonium chloride in water to obtain a 4% (mass fraction) aqueous solution of tetradecyldimethylbenzylammonium chloride. Add styrene - acrylic emulsion to the aqueous solution of tetradecyldimethylbenzylammonium chloride. After stirring for 1 h, add triethanolamine solution and stir for another 1 h to obtain a pre - solution, where the mass fraction of the styrene - acrylic emulsion is 1.6% and the mass fraction of triethanolamine is 3.5%;

[0043] (2) Add tetraethyl orthosilicate to the pre - solution to obtain a mixture with a 9% (mass fraction) of tetraethyl orthosilicate. Stir and react at a reaction temperature of 25 °C for 24 h to obtain a reaction solution (when calculating the mass fractions of the above raw materials, the reactions between substances are not considered);

[0044] (3) Use deionized water and alcohol to wash the reaction solution alternately for multiple times and centrifuge to obtain a precipitate product. Place the precipitate in an oven and dry it at 60 °C, then calcine it at a calcination temperature of 550 °C for 5 h to obtain a white powder of mesoporous silica microspheres with ultra - high oil absorption value and ultra - high specific surface area, and there is no caking phenomenon, as Figure 1 shown.

[0045] Performance test:

[0046] According to the scanning electron microscope image, it can be observed that the mesoporous silica prepared in this example is spherical particles with uniform size, as Figure 2As shown; it can be seen from the high-magnification electron microscope scanning image that the surface of the mesoporous silica microspheres is smooth, and the particles stack to form regular pores, as Figure 3 shown. According to the nitrogen adsorption-desorption isotherm curve ( Figure 4 shown), it can be seen that it belongs to type IV isotherm. The BET (Brunauer-Emmett-Teller) specific surface area is calculated to be about 1528.478 m 2 / g, and the pore volume is 0.307 cm 3 / g.

[0047] According to the pore size distribution diagram ( Figure 5 shown), it can be found that the pore size of the mesoporous silica microspheres prepared in this example is distributed in the range of 2 - 5 nm, with uniform pore channels.

[0048] Using dibutyl phthalate (DBP) as the test oil, the oil absorption value of the mesoporous silica microspheres prepared in this example is measured to be about 308 mL / 100 g.

[0049] Example 2

[0050] This example provides a preparation method of mesoporous silica microspheres with a controllable pore structure and particle size, including the following steps:

[0051] (1) Dissolve tetradecyldimethylbenzylammonium chloride in water to obtain a 4% tetradecyldimethylbenzylammonium chloride aqueous solution. Add styrene-acrylic emulsion to the tetradecyldimethylbenzylammonium chloride aqueous solution, stir for 1 h, then add triethanolamine solution and stir for another 1 h to obtain a pre-solution, where the mass fraction of the styrene-acrylic emulsion is 0.8% and the mass fraction of triethanolamine is 3.5%;

[0052] (2) Add tetraethyl orthosilicate to the pre-solution to obtain a mixture with a mass fraction of 9% tetraethyl orthosilicate, and stir and react at a reaction temperature of 25 °C for 24 h to obtain a reaction solution (when calculating the mass fractions of the above raw materials, the reactions between substances are not considered);

[0053] (3) Use deionized water and alcohol to wash the reaction solution alternately for multiple times and centrifuge to obtain a precipitate product. Place the precipitate in an oven and dry it at 60 °C, then calcine it at a calcination temperature of 550 °C for 5 h to obtain mesoporous silica microspheres with an ultra-high oil absorption value and an ultra-high specific surface area.

[0054] Performance test:

[0055] Figure 6 is the electron microscope scanning image of the mesoporous silica microspheres prepared according to this example, Figure 7It is a scanning electron micrograph at high magnification, from which it can be observed that the size distribution of most silica microspheres is uniform. Its specific surface area is 1038.474 m 2 / g, and the oil absorption value is 260 mL / 100 g.

[0056] Example 3

[0057] This example provides a method for preparing mesoporous silica microspheres with a controllable pore structure and particle size, including the following steps:

[0058] (1) Dissolve tetradecyldimethylbenzylammonium chloride in water to obtain an aqueous solution of tetradecyldimethylbenzylammonium chloride with a mass fraction of 4%. Add styrene-butadiene rubber latex to the aqueous solution of tetradecyldimethylbenzylammonium chloride, stir for 1 h, then add triethanolamine solution and stir again for 1 h to obtain a pre-solution, where the mass fraction of the styrene-acrylic latex is 0.8% and the mass fraction of triethanolamine is 3.5%;

[0059] (2) Add tetraethyl orthosilicate to the pre-solution to obtain a mixture with a mass fraction of tetraethyl orthosilicate of 9%. Stir and react at a reaction temperature of 25 °C for 24 h to obtain a reaction solution (when calculating the mass fractions of the above raw materials, the reactions between various substances are not considered);

[0060] (3) Use deionized water and alcohol to wash the reaction solution alternately for multiple times and centrifuge to obtain a precipitate product. Place the precipitate in an oven and dry it at 60 °C, then calcine it at a calcination temperature of 550 °C for 5 h to obtain mesoporous silica microspheres with an ultra-high oil absorption value and an ultra-high specific surface area.

[0061] Performance test:

[0062] Figure 8 It is a scanning electron micrograph of the mesoporous silica microspheres prepared according to this example, Figure 9 which is a high-magnification scanning electron micrograph. It can be observed that the silica microspheres have a pore structure and the particle sizes are uniform.

[0063] Figure 10 It is the nitrogen adsorption-desorption isotherm of the mesoporous silica microspheres prepared according to this example. It can be calculated that the specific surface area is 861.586 m 2 / g and the pore volume is 0.885 cm3 / g.

[0064] Figure 11 It is the pore size distribution diagram of the mesoporous silica microspheres prepared in this example. It can be seen that the pore size distribution is between 25 and 125 nm, belonging to a hierarchical pore structure.

[0065] Its measured oil absorption value is 617 mL / 100 g.

[0066] Example 4

[0067] This embodiment provides a method for preparing mesoporous silica microspheres with controllable pore structure and particle size, comprising the following steps:

[0068] (1) Tetradecyldimethylbenzyl ammonium chloride was dissolved in water to obtain a 4% aqueous solution of tetradecyldimethylbenzyl ammonium chloride, styrene-butadiene rubber emulsion was added to the aqueous solution of tetradecyldimethylbenzyl ammonium chloride, and the mixture was stirred for 1 hour. Then, triethanolamine solution was added and stirred again for 1 hour to obtain a pre-solution in which the mass fraction of styrene-acrylic emulsion was 1.6% and the mass fraction of triethanolamine was 3.5%;

[0069] (2) adding tetraethyl orthosilicate to the pre-solution to obtain a mixed solution having a mass fraction of 9% tetraethyl orthosilicate, stirring and reacting at a reaction temperature of 25° C. for 24 hours to obtain a reaction solution (the mass fractions of the above raw materials are calculated without considering the reaction between the substances);

[0070] (3) The reaction solution was washed alternately with deionized water and alcohol several times and centrifuged to obtain a precipitated product. The precipitate was dried in an oven at 60°C and then calcined at 550°C for 5 h to obtain mesoporous silica microspheres with ultra-high oil absorption value and ultra-high specific surface area.

[0071] Performance testing:

[0072] Figure 12 The electron microscope scanning image of the mesoporous silica microspheres prepared in this example shows that they are uniform in size and have a smooth surface. The specific surface area is 912.821m 2 / g, and the oil absorption value is 479mL / 100g.

[0073] Example 5

[0074] This embodiment provides a method for preparing mesoporous silica microspheres with controllable pore structure and particle size, comprising the following steps:

[0075] (1) Tetradecyldimethylbenzyl ammonium chloride was dissolved in water to obtain a 4% aqueous solution of tetradecyldimethylbenzyl ammonium chloride, a mixed emulsion of styrene-butadiene rubber latex and styrene-acrylic latex (1:1) was added to the aqueous solution of tetradecyldimethylbenzyl ammonium chloride, and the mixture was stirred for 1 hour, and then triethanolamine solution was added, and the mixture was stirred for another 1 hour to obtain a pre-solution, wherein the mass fraction of styrene-acrylic latex was 1.6% and the mass fraction of triethanolamine was 3.5%;

[0076] (2) adding tetraethyl orthosilicate to the pre-solution to obtain a mixed solution having a mass fraction of 9% tetraethyl orthosilicate, stirring and reacting at a reaction temperature of 25° C. for 24 hours to obtain a reaction solution (the mass fractions of the above raw materials are calculated without considering the reaction between the substances);

[0077] (3) The reaction solution was washed alternately with deionized water and alcohol for several times and centrifuged to obtain a precipitate product. After drying the precipitate in an oven at 60 °C, it was calcined at a calcination temperature of 550 °C for 5 h to obtain mesoporous silica microspheres with ultra-high oil absorption value and ultra-high specific surface area.

[0078] Performance test:

[0079] Figure 13 This is the SEM image of the mesoporous silica microspheres prepared in this example, with a specific surface area of 1042.854 m 2 / g and an oil absorption value of 362 mL / g.

[0080] According to Figure 3 , Figure 7 , Figure 9 , Figure 12 and Figure 13 It can be seen that by adjusting the ratio and types of surfactant and polymer emulsion, silica microspheres with particle size distribution ranging from 100 to 400 nm can be synthesized according to the present invention. According to Figure 5 and Figure 11 It can be proved that the present invention can not only prepare silica microspheres with a uniform pore structure, but also prepare silica microspheres with a hierarchical pore structure.

[0081] The above is only the best implementation mode of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several modifications or equivalent replacements can be made to the technical solution of the present invention, and the same technical effects can also be achieved, which should also be regarded as belonging to the protection scope of the present invention.

Claims

1. A preparation method of mesoporous silica microspheres with a regulable pore structure and particle size, characterized in that, It includes the following steps: (1) Add surfactant, polymer emulsion and precipitant into water, and mix them evenly as the pre-solution; (2) Add tetraethyl orthosilicate into the pre-solution to obtain a mixed solution, and continue stirring and reacting at a temperature of 10-70 °C for 2-48 h; (3) After the reaction is completed, through separation, washing and post-treatment, a powdery sample is obtained, which is the target product.

2. The preparation method according to claim 1, characterized in that: The surfactant described in step (1) is at least one of cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, tetradecyltrimethylammonium bromide, tetradecyltrimethylammonium chloride, and tetradecyldimethylbenzylammonium chloride, and the concentration of the surfactant in the pre-solution is 0.01%-10%.

3. The preparation method according to claim 2, wherein: The polymer emulsion described in step (1) is one or a mixture of styrene-acrylic emulsion and styrene-butadiene rubber emulsion, and the concentration in the pre-solution is 1%-10%.

4. The preparation method according to claim 3, characterized in that: The precipitant described in step (1) is triethanolamine, and the concentration in the pre-solution is 1%-10%.

5. The preparation method according to claim 4, characterized in that: The concentration of tetraethyl orthosilicate described in step (2) in the mixed solution is 1%-20%.

6. The preparation method according to claim 5, characterized in that: The post-treatment described in step (3) is calcination at a temperature of 400-900 °C for 4-24 h.

7. Mesoporous silica microspheres with a tunable pore structure and particle size prepared by the preparation method according to any one of claims 1 to 6, characterized in that: The specific surface area of the mesoporous silica microspheres is 1000-1500 m 2 / g.

9. Application of the mesoporous silica microspheres with hierarchical pores described in claim 7 as an adsorbent in the fields of lithium batteries, cosmetics, skin care products, and daily chemical products.

Images