Biparental silica microspheres and a method for preparing the same

Abstract

The application belongs to the technical field of powder material preparation, and particularly discloses amphiphilic silica microspheres and a preparation method thereof. The preparation method of the amphiphilic silica microspheres comprises the following steps: preparing a water solution of polystyrene sulfonic acid or perfluorohexyl sulfonic acid, adding silane (one or more of aminosilane, hydroxysilane and mercaptosilane) dropwise for reaction, and obtaining the amphiphilic silica microspheres through centrifugation and drying treatment after the reaction. The preparation method adopts high-molecular organic acid with amphiphilicity to react with silane, and hydrolysis reaction occurs in the self-assembly process to form silica. The preparation method has mild reaction conditions, is simple, efficient, low in cost, and the amphiphilic silica microspheres have excellent dispersibility in water phase or oil phase solvent, are uniform in particle size, controllable in size, and good in dispersibility, and are a high-quality microsphere filler.

Description

Technical Field

[0001] This invention relates to the field of powder material preparation technology, and in particular to an amphiphilic silica microsphere and its preparation method. Background Technology

[0002] Silica possesses excellent dielectric properties and a low coefficient of thermal expansion, making it a high-performance inorganic filler widely used in adhesives, coatings, and other fields. High silica filler content can reduce costs, increase strength, and lower the coefficient of thermal expansion. However, as the filler content increases, the system viscosity rises sharply, leading to difficulties in silica dispersion in the resin and a tendency for agglomeration. Compared to ordinary silica, spherical silica offers advantages such as a smooth surface, uniform dispersion, and good flowability, typically allowing for higher filler ratios in resins. In the copper-clad laminate industry, the silica filler content is generally less than 40% of the total volume, but using spherical silica can achieve a filler content of up to 60%, reducing costs while significantly improving the material's mechanical properties.

[0003] In 1968, Stober et al. used ethanol as a solvent and tetraethyl orthosilicate as a raw material to prepare monodisperse spherical silica via hydrolysis and condensation reactions using the sol-gel method. However, silica microspheres prepared by this method are often difficult to disperse in some solvents or resins, often requiring further modification to make them hydrophilic or lipophilic, thereby increasing the compatibility of silica with solvents or resins, which complicates the use of silica. Furthermore, because hydrolysis and condensation occur simultaneously in this method, the reaction rates change continuously with varying reaction conditions, requiring very strict control of the reaction conditions. This further complicates the control of the morphology and uniformity of the silica.

[0004] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of this invention is to provide an amphiphilic silica microsphere and its preparation method, which aims to solve the problem that existing methods for preparing silica microspheres are difficult to control the morphology, uniformity and dispersibility of silica at the same time.

[0006] The technical solution of the present invention is as follows:

[0007] A first aspect of the present invention provides a method for preparing amphiphilic silica microspheres, comprising the steps of:

[0008] Prepare an aqueous solution of a high molecular weight organic acid, wherein the high molecular weight organic acid is polystyrene sulfonic acid or perfluorohexyl sulfonic acid;

[0009] Silane was added to the aqueous solution of the high molecular weight organic acid to carry out the reaction, and then centrifuged to obtain the amphiphilic silica microspheres.

[0010] The silane is one or more of aminosilane, hydroxysilane, and mercaptosilane.

[0011] Optionally, in the aqueous solution of the high molecular weight organic acid, the mass ratio of the high molecular weight organic acid to water is (10-20):100.

[0012] Optionally, the mass ratio of the high molecular weight organic acid to the silane is 10:(1-20).

[0013] Optionally, the addition of silane specifically involves adding silane dropwise at a rate of 0.05-0.2 g / min.

[0014] Optionally, in the step of preparing the aqueous solution of the high molecular weight organic acid, the high molecular weight organic acid is added to water and stirred at 0-60°C to obtain the aqueous solution of the high molecular weight organic acid.

[0015] Optionally, the reaction time is 2-24 hours.

[0016] Optionally, the aminosilane is aminopropyltrimethoxysilane or aminopropyltriethoxysilane.

[0017] Optionally, the hydroxysilane is hydroxypropyltrimethoxysilane or hydroxypropyltriethoxysilane.

[0018] Optionally, the mercaptosilane is mercaptopropyltrimethoxysilane or mercaptopropyltriethoxysilane.

[0019] In a second aspect, the present invention provides amphiphilic silica microspheres prepared by any of the preparation methods described above.

[0020] Optionally, the particle size range of the amphiphilic silica microspheres is 0.16-0.35 μm.

[0021] Optionally, the sphericity of the amphiphilic silica microspheres is 97%-98%.

[0022] This invention prepares amphiphilic silica microspheres by reacting an aqueous solution of polystyrene sulfonic acid (PSS) or perfluorohexyl sulfonic acid (Nafion) with a specific silane (aminosilane, hydroxysilane, or mercaptosilane). The preparation method has the following beneficial effects:

[0023] (1) No additional alcohol solvent is required, and PSS / Nafion itself is acidic, thus avoiding the use of inorganic acids and bases, making the preparation method simpler and more efficient. The preparation method greatly simplifies the preparation process and has the advantages of mild experimental conditions, simple processing, and low cost.

[0024] (2) The repeating units in the PSS / Nafion high molecular organic acid have sulfonic acid groups, which can self-assemble with specific silanes containing amino, hydroxy or mercapto groups, effectively avoiding the aggregation phenomenon in the preparation of silica. The resulting amphiphilic silica microspheres have good uniformity.

[0025] (3) PSS / Nafion is a stable high molecular weight organic acid. Compared with the inorganic acid usually used, it can control the hydrolysis of silicon dioxide more gently. In this invention, PSS / Nafion organic acid is used instead of ordinary inorganic acid to control the reaction conditions for preparing silicon dioxide, so that the reaction is more gentle and the particle size of silicon dioxide can be controlled more effectively.

[0026] (4) The silica microspheres prepared by this invention have amphiphilic properties, which makes the silica microspheres have excellent dispersibility in aqueous or oil solvents, greatly facilitating subsequent applications. Moreover, the amphiphilic silica microspheres have uniform particle size, controllable size, and good dispersibility, making them a high-quality microsphere filler. Attached Figure Description

[0027] Figure 1 This is a scanning electron microscope (SEM) image of the amphiphilic silica microspheres provided in Example 1 of the present invention.

[0028] Figure 2 This is a SEM image of the amphiphilic silica microspheres provided in Example 2 of the present invention.

[0029] Figure 3 This is a SEM image of the amphiphilic silica microspheres provided in Example 3 of the present invention.

[0030] Figure 4 This is a SEM image of the amphiphilic silica microspheres provided in Example 4 of the present invention.

[0031] Figure 5 This is a SEM image of the silica microspheres provided in Example 6 of the present invention.

[0032] Figure 6 This is a SEM image of the silica microspheres provided in Example 7 of the present invention.

[0033] Figure 7 This is a SEM image of the silica microspheres provided in Example 8 of the present invention.

[0034] Figure 8A macroscopic image of the amphiphilic silica microspheres dispersed in ethyl acetate as provided in Example 1 of this invention.

[0035] Figure 9 Here is a macroscopic diagram of the amphiphilic silica microspheres dispersed in petroleum ether provided in Example 2 of this invention.

[0036] Figure 10 The macroscopic diagram of the amphiphilic silica microspheres dispersed in water provided in Embodiment 3 of the present invention.

[0037] Figure 11 The macroscopic diagram of silica microspheres dispersed in ethyl acetate as provided in Example 7 of this invention.

[0038] Figure 12 The macroscopic diagram of silica microspheres dispersed in water provided in Embodiment 8 of the present invention. Detailed Implementation

[0039] This invention provides amphiphilic silica microspheres and a method for preparing the same. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the invention is further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention.

[0041] This invention provides a method for preparing amphiphilic silica microspheres, comprising the following steps:

[0042] Prepare an aqueous solution of a high molecular weight organic acid, wherein the high molecular weight organic acid is polystyrene sulfonic acid or perfluorohexyl sulfonic acid;

[0043] Silane was added to the aqueous solution of the high molecular weight organic acid to carry out the reaction. After the reaction, the mixture was centrifuged and dried to obtain the amphiphilic silica microspheres.

[0044] The silane is one or more of aminosilane, hydroxysilane, and mercaptosilane.

[0045] The preparation method provided by this invention greatly simplifies the preparation process and has the advantages of mild experimental conditions, simple processing, and low cost. The specific silanes used in this invention are aminosilanes (aminopropyltrimethyl / ethoxysilane), hydroxysilanes (hydroxypropyltrimethyl / ethoxysilane), mercaptosilanes (mercaptopropyltrimethyl / ethoxysilane), etc., which contain amino, hydroxyl, mercapto groups, etc. PSS (whose structural formula is...) is added... ) or Nafion (its structural formula is After being dissolved in an aqueous solution of a high-molecular-weight organic acid, both PSS and Nafion contain sulfonic acid groups in their repeating units. These sulfonic acid groups can interact with hydroxyl, amino, and thiol groups, undergoing self-assembly to form a relatively regular arrangement. Hydrolysis also occurs on these chain segments. Since PSS or Nafion is a mild organic acid, it can initiate the slow hydrolysis of silanes on the PSS or Nafion chain segments to generate silica. This effectively controls the reaction, increases its uniformity, and prevents the aggregation of silica produced by hydrolysis. This allows for more stable and effective control of particle size, ensuring the sphericity and uniformity of the silica microspheres. Furthermore, the amphiphilic nature of the high-molecular-weight segments and the hydrophilic nature of the sulfonic acid groups in PSS or Nafion allows the self-assembled silica microspheres to be well dispersed in aqueous or oil-based solvents, greatly facilitating subsequent applications. Furthermore, this preparation method only requires the addition of PSS or Nafion and silane, avoiding the use of other organic solvents and inorganic acids and bases, reducing the introduction of other impurities, and simplifying post-processing, making the preparation more convenient and efficient. It should be noted that amphiphilic silica and the above-mentioned effects can be prepared using high-molecular-weight organic acids whose segmental repeating units contain sulfonic acid, phosphoric acid, or other groups; therefore, the high-molecular-weight organic acids used in the preparation method are not limited to PSS and Nafion.

[0046] In some embodiments, the mass ratio of the polymeric organic acid to water in the aqueous solution of the polymeric organic acid is (10-20):100.

[0047] This invention uses PSS or Nafion organic acids to react with silanes. Compared with inorganic acids, PSS and Nafion have the following advantages: (1) Buffering capacity: Organic acids absorb or release protons (H+ ions) to resist drastic changes in pH. Even at the same pH, pH changes in PSS and Nafion organic acid solutions tend to be more gradual and controllable, thus making the reaction conditions more mild. (2) Molecular structure: The molecular structure of organic acids includes hydrophobic and hydrophilic regions, and these structural features can affect their interaction with the silica surface. PSS and Nafion organic acids have more specific functional groups and side chains, in which sulfonic acid groups can selectively interact with specific functional groups on the silica surface to form self-assembled structures. This selectivity can reduce side reactions and minimize damage to the silica structure. In contrast, other acids may react with multiple sites on the silica surface, leading to more violent reactions and potential structural damage. (3) Reaction rate: The limited water solubility of PSS and Nafion restricts the rate and extent of their reaction with silica, helping to create milder reaction conditions and slowing down the hydrolysis rate of silica. The slower reaction rate can provide milder conditions to control the reaction. In contrast, inorganic acids may have higher reactivity, leading to faster and more violent reactions. (4) Byproducts: The reaction of PSS and Nafion with silanes produces fewer, less toxic, and easier-to-handle byproducts. In contrast, the reaction of inorganic acids may produce harmful or difficult-to-handle byproducts.

[0048] In summary, due to the unique molecular characteristics, reaction selectivity, buffering capacity, and interaction modes with silica of PSS and Nafion organic acids, the reaction conditions can be controlled more effectively, allowing the silica hydrolysis reaction to proceed more gently and ensuring the preparation of high-quality silica.

[0049] In some embodiments, the mass ratio of the polymeric organic acid to the silane is 10:(1-20).

[0050] In some embodiments, the addition of silane specifically refers to adding silane dropwise at a rate of 0.05-0.2 g / min.

[0051] In some embodiments, in the step of preparing the aqueous solution of the high molecular weight organic acid, the high molecular weight organic acid is added to water and stirred at 0-60°C to obtain the aqueous solution of the high molecular weight organic acid.

[0052] In some implementations, the reaction time is 2-24 hours.

[0053] In some embodiments, the aminosilane is aminopropyltrimethoxysilane or aminopropyltriethoxysilane.

[0054] In some embodiments, the hydroxysilane is hydroxypropyltrimethoxysilane or hydroxypropyltriethoxysilane.

[0055] In some embodiments, the mercaptosilane is mercaptopropyltrimethoxysilane or mercaptopropyltriethoxysilane.

[0056] The silane used in this invention contains amino, hydroxyl, and mercapto groups, which can interact with the sulfonic acid groups in the repeating units of PSS and Nafion chains to self-assemble into a relatively regular arrangement. The silane slowly hydrolyzes on the organic acid PSS or Nafion chains to generate silica, effectively controlling the reaction, increasing reaction uniformity, and effectively preventing the aggregation of silica produced by hydrolysis. This allows for more stable and effective control of particle size, ensuring the sphericity and uniformity of the silica microspheres.

[0057] This invention also provides amphiphilic silica microspheres, prepared by any of the methods described above. The amphiphilic silica microspheres prepared by the above methods have uniform particle size, controllable size, and good dispersibility, making them a high-quality microsphere filler.

[0058] In some embodiments, the particle size of the amphiphilic silica microspheres ranges from 0.16 to 0.35 μm.

[0059] In some embodiments, the sphericity of the amphiphilic silica microspheres is 97%-98%.

[0060] The following detailed description uses specific examples.

[0061] Example 1

[0062] 10 g of PSS and 100 g of water were added to a round-bottom flask to prepare a solution, which was stirred thoroughly at 40 °C. Then, 10 g of hydroxypropyltriethoxysilane solution was slowly added dropwise over 60 minutes, during which the solution gradually changed from clear to off-white. After the addition was complete, the reaction was continued for 12 hours. After centrifugation, the solution was dried at 60 °C for 12 hours to obtain amphiphilic silica microspheres.

[0063] Example 2

[0064] 15g of Nafion and 100g of water were added to a round-bottom flask to prepare a solution, which was stirred thoroughly at 30°C. Then, 12g of aminopropyltriethoxysilane solution was slowly added dropwise over 120 minutes, during which the solution gradually changed from clear to off-white. After the addition was complete, the reaction was continued for 15 hours. After centrifugation, the solution was dried at 80°C for 12 hours to obtain amphiphilic silica microspheres.

[0065] Example 3

[0066] 18 g of PSS and 100 g of water were added to a round-bottom flask to prepare a solution, which was stirred thoroughly at 35 °C. Then, 12 g of aminopropyltrimethoxysilane silane solution was slowly added dropwise over 150 min, during which the solution gradually changed from clear to off-white. After the addition was complete, the reaction was continued for 10 h, centrifuged, and dried at 70 °C for 14 h to obtain amphiphilic silica microspheres.

[0067] Example 4

[0068] 8 g of Nafion and 100 g of water were added to a round-bottom flask to prepare a solution, which was stirred thoroughly at 20 °C. Then, 5 g of hydroxypropyltriethoxysilane solution was slowly added dropwise over 100 min, during which the solution gradually changed from clear to off-white. After the addition was complete, the reaction was continued for 15 h, centrifuged, and dried at 60 °C for 18 h to obtain amphiphilic silica microspheres.

[0069] Example 5

[0070] 17 g of Nafion and 100 g of water were added to a round-bottom flask to prepare a solution, which was stirred thoroughly at 35 °C. Then, 12 g of hydroxypropyltrimethoxysilane solution was slowly added dropwise over 180 min, during which the solution gradually changed from clear to off-white. After the addition was complete, the reaction was continued for 16 h, centrifuged, and dried at 70 °C for 10 h to obtain amphiphilic silica microspheres.

[0071] The silica microspheres prepared in Examples 1-5 are easily dispersed in water and organic solvents (such as ethyl acetate, epoxy resin, acrylic acid and other polymer solvents), and exhibit good dispersibility.

[0072] Mesoporous silica microspheres were obtained by calcining amphiphilic silica microspheres at 800℃ for 5 hours in a muffle furnace. The specific surface area of ​​these mesoporous silica microspheres was measured to be approximately 600 m². 2 / g.

[0073] By further calcining the prepared silica microspheres to remove the PSS / Nafion material on the surface, the amphiphilic properties are lost, but mesoporous silica material is obtained. This mesoporous silica has a high specific surface area and can be used to adsorb or load other materials.

[0074] Example 6

[0075] In a round-bottom flask, 30 ml of ethanol, 2 ml of distilled water, and 4 ml of trifluorobenzenesulfonic acid were added as the starting solution, and the mixture was stirred thoroughly at 30°C. Then, 6 g of hydroxypropyltriethoxysilane was quickly added to the flask, and the solution changed from clear to opaque. After continuing the reaction for 10 hours, silica microspheres were obtained.

[0076] Example 7

[0077] In a round-bottom flask, 40 ml of ethanol, 3 ml of distilled water, and 3 ml of acetic acid were added as the starting solution, and the mixture was stirred thoroughly at 35°C. Then, 10 g of aminopropyltriethoxysilane was quickly added to the flask, and the solution changed from clear to opaque. After continuing the reaction for 12 hours, silica microspheres were obtained.

[0078] Example 8

[0079] Add 35 ml of ethanol, 3 ml of distilled water, and 5 ml of hydrochloric acid to a round-bottom flask as the starting solution, and stir until homogeneous at 25°C. Then, quickly add 15 g of mercaptopropyltriethoxysilane to the flask; the solution changes from clear to opaque. Continue the reaction for 15 h to obtain silica microspheres.

[0080] The silica microspheres prepared in Examples 6-8 were poorly dispersed in solvents such as water and ethyl acetate.

[0081] The particle size of the silica microspheres prepared in Examples 1-8 was tested, and the results are shown in Table 1.

[0082] Table 1

[0083] Average particle size / nm 182 201 196 298 Sphericity / % 97.2 97.4 97.6 97.5 Serial Number / Particle Size Example 5 Example 6 Example 7 Example 8 Average particle size / nm 216 245 198 505 Sphericity / % 97.1 85.2 76.7 36.5

[0084] The test results show that the silica microspheres prepared using organic acids PSS or Nafion in Examples 1-4 have good sphericity and relatively uniform particle size. Their morphology results are as follows: Figure 1-4 As shown.

[0085] In Example 1, silica microspheres were prepared using PSS, achieving a sphericity of 97.2%. In Example 2, silica was prepared using Nafion, achieving a sphericity of 97.4%, both showing good sphericity. In Example 3, increasing the reaction temperature resulted in a slight increase in the average particle size of the silica microspheres compared to Example 1. In Example 4, increasing the amounts of Nafion and silane also led to a certain increase in the particle size of the silica microspheres.

[0086] Example 6 uses the small molecule organic acid trifluorobenzenesulfonic acid to prepare silica. Although the hydrolysis rate is slower than that of inorganic acids, there is no polymer chain self-assembly process, such as... Figure 5 As shown, the prepared silica microspheres exhibit poor sphericity, lack amphiphilic properties, and have poor dispersibility in water and organic solvents.

[0087] Example 7 uses acetic acid to prepare silica, which does not involve a self-assembly process. Furthermore, the addition of other substances makes the reaction conditions more difficult to control. Figure 6 As shown, the prepared silica contains many impurities and has an uneven particle size. Furthermore, the silica microspheres are difficult to disperse in water and organic solvents.

[0088] like Figure 7 As shown, in Example 8, hydrochloric acid was used to prepare silica. The prepared silica had poor morphology, with unsatisfactory homogeneity and sphericity. The reason for this is that the hydrochloric acid used in the preparation was highly acidic, resulting in a faster hydrolysis rate of silica and making the reaction conditions more difficult to control, thus leading to poor sphericity in the prepared silica.

[0089] like Figure 8-10 As shown, the amphiphilic silica microspheres prepared in Examples 1-3 of this invention can be well dispersed in ethyl acetate, petroleum ether and water without aggregation or precipitation.

[0090] like Figure 11 As shown, the ordinary silica microspheres prepared in Example 7, compared with the amphiphilic silica microspheres prepared in this invention, exhibited agglomeration in ethyl acetate and poor dispersibility.

[0091] like Figure 12 As shown, the ordinary silica microspheres prepared in Example 8 precipitated in water and were difficult to disperse.

[0092] In summary, the amphiphilic silica microspheres prepared by this invention using amphiphilic polymeric organic acids exhibit excellent dispersibility and compatibility in both aqueous and oil-phase solvents. Compared to conventionally prepared silica microspheres, the amphiphilic silica microspheres provided by this invention have advantages such as uniform particle size, controllable size, and good dispersibility, making them a high-quality microsphere filler.

[0093] It should be understood that the application of the present invention is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for preparing amphiphilic silica microspheres, characterized in that, Including the following steps: Prepare an aqueous solution of a high molecular weight organic acid, wherein the high molecular weight organic acid is polystyrene sulfonic acid or perfluorohexyl sulfonic acid; Silane was added to the aqueous solution of the high molecular weight organic acid to carry out the reaction, and then centrifuged to obtain the amphiphilic silica microspheres. The silane is one or more of aminosilane, hydroxysilane, and mercaptosilane.

2. The method for preparing amphiphilic silica microspheres according to claim 1, characterized in that, In the aqueous solution of the high molecular weight organic acid, the mass ratio of the high molecular weight organic acid to water is (10-20):

100.

3. The method for preparing amphiphilic silica microspheres according to claim 1, characterized in that, The mass ratio of the high molecular weight organic acid to the silane is 10:(1-20).

4. The method for preparing amphiphilic silica microspheres according to claim 1, characterized in that, The addition of silane specifically involves adding silane dropwise at a rate of 0.05-0.2 g / min.

5. The method for preparing amphiphilic silica microspheres according to claim 1, characterized in that, The specific steps for preparing the aqueous solution of the high molecular weight organic acid are as follows: adding the high molecular weight organic acid to water and stirring at 0-60°C to obtain the aqueous solution of the high molecular weight organic acid.

6. The method for preparing amphiphilic silica microspheres according to claim 1, characterized in that, The reaction time is 2-24 hours.

7. The method for preparing amphiphilic silica microspheres according to claim 1, characterized in that, The aminosilane is aminopropyltrimethoxysilane or aminopropyltriethoxysilane; and / or, the hydroxysilane is hydroxypropyltrimethoxysilane or hydroxypropyltriethoxysilane; and / or, the mercaptosilane is mercaptopropyltrimethoxysilane or mercaptopropyltriethoxysilane.

8. An amphiphilic silica microsphere, characterized in that, The amphiphilic silica microspheres were prepared by the method described in any one of claims 1-7.

9. The amphiphilic silica microspheres according to claim 8, characterized in that, The amphiphilic silica microspheres have a particle size range of 0.16-0.35 μm.

10. The amphiphilic silica microspheres according to claim 8, characterized in that, The sphericity of the amphiphilic silica microspheres is 97%-98%.

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