Silica hollow microsphere and preparation method thereof
The preparation of silica hollow microspheres by self-templating method solves the problems of complex operation and high-temperature calcination in the existing technology, and realizes silica hollow microspheres with uniform particle size and excellent performance, thus expanding its application scenarios.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-24
- Publication Date
- 2026-04-14
AI Technical Summary
Existing methods for preparing hollow silica microspheres suffer from problems such as complex operation, the need for high-temperature calcination or the use of chemical reagents, and difficulty in controlling the diameter of the microspheres.
A self-templating method was adopted, in which a first silicon source was mixed with a solution for hydrolysis and condensation reaction, and a second silicon source was added to form multilayer microspheres. Subsequently, the microspheres were washed with alcohol at room temperature to prepare organic-inorganic hybrid silica hollow microspheres. This method avoids high-temperature calcination and the use of chemical reagents, and achieves control over hollowness and particle size.
The production process has been simplified, energy consumption has been reduced, and hollow silica microspheres with uniform particle size have been obtained. These microspheres possess excellent mechanical strength and thermal stability, expanding their application scenarios such as lithium-ion battery electrolyte additives, polymer composite fillers, and catalyst supports.
Smart Images
Figure CN121849982A_ABST
Abstract
Description
Technical Field
[0001] This application belongs to the field of silica material technology, specifically relating to a silica hollow microsphere and its preparation method. Background Technology
[0002] Hollow silica microspheres possess characteristics such as low density, high specific surface area, load-bearing cavities, and chemical stability. In biomedicine, they can encapsulate poorly soluble drugs to improve bioavailability. In engineering, they can serve as lightweight heat-insulating fillers. In catalysis, they can protect active components and enhance mass transfer efficiency. In environmental treatment, they can adsorb harmful substances in water. In the communications field, they can be used as electronic packaging materials. Their important applications extend beyond these, making the preparation of hollow silica microspheres crucial.
[0003] Currently, the two main methods for preparing hollow silica microspheres are spray drying and template drying. Spray drying involves atomizing liquid raw materials such as solutions, emulsions, and suspensions into extremely fine droplets using an atomizer. Upon contact with hot air, these droplets rapidly solidify and are then dried to obtain the desired product. While this method is simple, it is difficult to control the microsphere diameter, requiring subsequent grading and screening to obtain products within the target size range. Template drying uses a material with a specific shape and structure as a template, which is then filled or coated to obtain microspheres of the desired shape. This method includes hard template drying and soft template drying. Microspheres obtained through template drying require removal of the template using chemical reagents in subsequent processes. Challenges include selecting the removal agent, microsphere breakage, removal agent residue, and high processing costs. Furthermore, methods for removing the template agent are difficult to implement, requiring high temperatures and making condition control challenging.
[0004] Therefore, there is an urgent need to develop a simple method for preparing silica hollow microspheres that does not require chemical reagents or high temperatures. Summary of the Invention
[0005] This application aims to at least partially address one of the technical problems existing in the prior art. To this end, one objective of this application is to provide a method for preparing hollow silica microspheres that is simple to operate, requires no calcination throughout the process, and can obtain organic-inorganic hybrid hollow silica microspheres with adjustable hollowness.
[0006] In a first aspect, this application proposes a method for preparing hollow silica microspheres. According to an embodiment of this application, the method includes: mixing a first silicon source with a first solution, adjusting the pH to allow the first silicon source to undergo a hydrolysis reaction; adding an alkali to the solution after the hydrolysis reaction to conduct a condensation reaction, obtaining a microsphere dispersion; adding a second silicon source to the microsphere dispersion to obtain a multilayer microsphere dispersion; sequentially centrifuging and filtering the multilayer microsphere dispersion to obtain a solid; and washing the solid with alcohol to obtain the hollow silica microspheres. Therefore, compared to traditional hard template methods requiring high-temperature calcination to remove the template, soft template methods requiring large amounts of surfactants, and spray drying methods where particle size is difficult to control, this application can complete "self-templating" molding in one step in a room-temperature, weakly alkaline solution: the first silicon source condenses to form polysilsesquioxane microspheres with soluble oligomers inside, without the need for an external hard template or surfactant; subsequent low-temperature alcohol washing removes the internal oligomers, eliminating the need for high-temperature calcination. By adjusting the hydrolysis time and coating amount, the cavity volume and hollowness can be controlled stepwise while retaining organic functional groups, resulting in hybrid hollow microspheres with uniform particle size. This process eliminates complex equipment such as high-temperature furnaces, simplifies the production process, and reduces energy consumption, offering advantages such as being green, low-consumption, and highly repeatable.
[0007] According to an embodiment of this application, the first silicon source is a monosubstituted silane coupling agent.
[0008] According to embodiments of this application, the second silicon source is an orthosilicate or a monosubstituted silane coupling agent.
[0009] According to embodiments of this application, the first silicon source includes phenyltrimethoxysilane, and optionally one or more of methyltrimethoxysilane, propyltrimethoxysilane, vinyltrimethoxysilane, aminopropyltrimethoxysilane, and octyltrimethoxysilane.
[0010] According to embodiments of this application, the second silicon source includes one or more of methyltrimethoxysilane, propyltrimethoxysilane, vinyltrimethoxysilane, aminopropyltrimethoxysilane, methyl orthosilicate, and tetraethyl orthosilicate.
[0011] According to an embodiment of this application, the volume ratio of the first silicon source to the second silicon source is 1:(1-4).
[0012] According to embodiments of this application, the alcohol washing is performed using anhydrous methanol, anhydrous ethanol, propanol, and isopropanol.
[0013] According to an embodiment of this application, the alcohol washing time is 2-10 hours.
[0014] According to an embodiment of this application, the volume ratio of the first silicon source to the alcohol-water solution is 1:(20-100).
[0015] According to embodiments of this application, the first solution is selected from aqueous solutions or aqueous alcohol solutions.
[0016] According to an embodiment of this application, the volume ratio of alcohol to water in the alcohol-water solution is 1:99-1:1.
[0017] According to an embodiment of this application, after pH adjustment, the pH value of the solution is 2.0-7.0.
[0018] According to an embodiment of this application, the temperature of the hydrolysis reaction is 30-80°C.
[0019] According to an embodiment of this application, the hydrolysis reaction takes 1-60 minutes.
[0020] According to embodiments of this application, the alkali is selected from at least one of ammonia, sodium carbonate, sodium hydroxide, and potassium hydroxide.
[0021] According to an embodiment of this application, after adding alkali to the solution following the hydrolysis reaction, the pH value of the solution is 9.0-11.0.
[0022] According to an embodiment of this application, the condensation reaction takes 1-5 hours.
[0023] According to an embodiment of this application, the temperature of the condensation reaction is 30-80°C.
[0024] In a second aspect of this application, a hollow silica microsphere is proposed. According to embodiments of this application, the hollow silica microsphere is prepared using the method described in the first aspect. Thus, the hollow silica microsphere prepared by the method of this application possesses an organic-inorganic hybrid structure: the inorganic siloxane framework (-Si-O-Si-) endows the microsphere with excellent mechanical strength and thermal stability; the functional groups introduced by the organic phenyl groups and coupling agents enhance the compatibility of the microsphere with the organic matrix, while providing active sites for subsequent functional modifications (such as grafting catalysts, adsorbents, and conductive groups). Compared to purely inorganic or purely organic microspheres, this hybrid structure achieves a synergistic effect of "structural stability" and "functional tunability," expanding the application scenarios of the product (such as lithium-ion battery electrolyte additives, polymer composite fillers, catalyst supports, electronic packaging materials, etc.).
[0025] According to embodiments of this application, the hollow silica microspheres contain organic groups.
[0026] According to embodiments of this application, the particle size of the silica hollow microspheres is 200-2000 nm.
[0027] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description
[0028] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which: Figure 1 This is a flowchart of a method for preparing hollow silica microspheres according to an embodiment of this application; Figure 2 This is a TEM image of the silica hollow microspheres according to Example 1 of this application; Figure 3 This is a TEM image of the silica hollow microspheres according to Example 2 of this application; Figure 4 This is a TEM image of the silica hollow microspheres according to Example 3 of this application; Figure 5 This is a TEM image of the silica hollow microspheres according to Example 4 of this application; Figure 6 This is a TEM image of the silica hollow microspheres according to Example 5 of this application; Figure 7 This is a TEM image of the silica hollow microspheres according to Comparative Example 1 of this application. Detailed Implementation
[0029] The embodiments of the silica hollow microspheres and their preparation method described herein are disclosed in detail below with appropriate reference to the accompanying drawings. However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of practically identical structures may be omitted. This is to avoid unnecessarily lengthy descriptions and to facilitate understanding by those skilled in the art. Furthermore, the accompanying drawings and the following description are provided for the purpose of enabling those skilled in the art to fully understand this application and are not intended to limit the subject matter of the claims.
[0030] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a specific parameter, it is also expected that ranges of 60-110 and 80-120 are also included. Furthermore, if minimum range values of 1 and 2 are listed, and if maximum range values of 3, 4, and 5 are listed, then the following ranges are all expected: 1-3, 1-4, 1-5, 2-3, 2-4, and 2-5. In this application, unless otherwise stated, the numerical range "ab" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0-5" indicates that all real numbers between "0-5" have been listed in this article; "0-5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.
[0031] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions.
[0032] Unless otherwise specified, all technical features and optional technical features of this application may be combined to form new technical solutions.
[0033] Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used in this application is for the purpose of describing particular embodiments only and is not intended to limit this application; unless otherwise stated, the values of the parameters mentioned in this application can be measured using various measurement methods commonly used in the art (e.g., they can be tested according to the methods given in the embodiments of this application).
[0034] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. "First feature" and "second feature" may include one or more of the indicated feature.
[0035] In the description of this application, "A and / or B" can include any of the cases of A alone, B alone, or A and B, where A and B are merely examples and can be any technical feature connected by "and / or" in this application.
[0036] In one aspect of this application, a method for preparing hollow silica microspheres is provided. According to an embodiment of this application, the method for preparing the hollow silica microspheres includes: S100: Mix the first silicon source with the first solution, adjust the pH, and allow the first silicon source to undergo a hydrolysis reaction.
[0037] According to some embodiments of this application, the first silicon source is a monosubstituted silane coupling agent. According to some embodiments of this application, the first silicon source includes phenyltrimethoxysilane, and optionally one or more of methyltrimethoxysilane, propyltrimethoxysilane, aminopropyltrimethoxysilane, vinyltrimethoxysilane, and octyltrimethoxysilane. Thus, by selecting "phenyltrimethoxysilane" as the core silane, its hydrolysis can self-condense to synthesize polysilsesquioxane microspheres containing soluble oligomers, naturally acting as a "self-template" core, and exhibiting strong hydrophobicity, facilitating subsequent coating layer deposition. Furthermore, methyl / propyl / vinyl / octyltrimethoxysilane can be combined, whose hydrolytic activity is faster or close to that of phenyltrimethoxysilane, enabling the formation of microspheres containing phenyltrimethoxysilane oligomers, avoiding the formation of solid microspheres due to excessively rapid reaction, while simultaneously improving shell density and mechanical strength, introducing organic groups to provide reaction sites, and subsequently grafting drugs, catalysts, or polymers via thiol-ene, free radical, or hydrosilaneylation.
[0038] It should be noted that when the first silicon source is selected from two or more sources, the volume ratio between the two or more first silicon sources is 1:1-100:1 (phenyltrimethoxysilane: other coupling agents). This ensures the formation of a hollow structure, avoiding localized excessive condensation caused by an excessive proportion of other coupling agents (leading to microsphere aggregation, wide particle size distribution, and low hollowness). Furthermore, it optimizes the hybrid structure of the microspheres through component synergy—for example, a balanced combination of rigid and flexible groups can improve the mechanical strength and flexibility of the microspheres, and an appropriate ratio of hydrophobic and active groups can balance organic compatibility and subsequent modification capabilities. Ultimately, this results in a well-structured and balanced core microsphere, laying a stable foundation for subsequent multilayer coating and hollow structure construction.
[0039] According to some embodiments of this application, the first solution is selected from aqueous solutions or aqueous alcohol solutions.
[0040] According to some embodiments of this application, the volume ratio of alcohol to water in the alcohol-water solution is 1:99 to 1:1. For example, it can be 1:99, 1:90, 1:70, 1:50, 1:10, 1:5, 1:2, 1:1, etc., or it can be any range of the above values.
[0041] It should be noted that the "alcohol-water solution" mentioned in this application refers to a binary mixture system composed of an alcohol compound and water. This application does not specifically limit the types of alcohol compounds mentioned, and those skilled in the art can choose them reasonably according to actual experimental needs. For example, the alcohol compound can be selected from commonly used low molecular weight alcohols such as methanol, ethanol, propanol, and isopropanol.
[0042] According to some embodiments of this application, the volume ratio of the first silicon source to the first solution is 1:(20-100). For example, it can be 1:20, 1:25, 1:30, 1:36, 1:40, 1:45, 1:50, 1:55, 1:60, 1:65, 1:70, 1:75, 1:80, 1:88, 1:90, 1:95, 1:100, etc., or any range of the above values. Therefore, by controlling the volume ratio of the first silicon source to the first solution within the above specific range, the dispersion state of the coupling agent can be controlled. On the one hand, this reduces morphological defects such as microsphere aggregation and wide particle size distribution; on the other hand, it prevents the formation of colloids due to excessively high coupling agent concentration.
[0043] According to some embodiments of this application, after pH adjustment, the pH value of the solution is 2.0-7.0. For example, it can be 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, etc., or any range of the above values. It should be noted that this application does not specifically limit the reagent used for pH adjustment, as long as it can adjust the pH value to the range of 2.0-7.0. For example, the acid used for pH adjustment can be formic acid, acetic acid, hydrochloric acid, nitric acid, etc. Monosubstituted silane coupling agents (such as phenyltrimethoxysilane) are mostly hydrophobic organosilicon compounds, which have poor compatibility with pure water and easily form oil droplet-like aggregates, resulting in a wide microsphere particle size distribution. By controlling the pH value within the above range, protons (H... + The protonation of oxygen atoms (-Si-OR) in silane molecules to form organosilicon alcohols can reduce the surface tension at the interface between the coupling agent and water, improve the dispersion stability of silane coupling agents in the aqueous phase, and prevent oil droplet aggregation. At the same time, the silanols (-Si-OH) generated by hydrolysis are beneficial to the rapid formation of microsphere shells.
[0044] According to some embodiments of this application, the temperature of the hydrolysis reaction is 30-80°C. For example, it can be 30°C, 32°C, 35°C, 38°C, 40°C, 42°C, 45°C, 48°C, 50°C, 52°C, 55°C, 58°C, 60°C, 62°C, 65°C, 68°C, 70°C, 72°C, 75°C, 78°C, 80°C, etc., or any range of the above values. Therefore, by keeping the temperature within the above range, the molecular diffusion rate can be increased, the contact probability between silane and water molecules can be enhanced, and the hydrolysis reaction can be accelerated.
[0045] According to some embodiments of this application, the hydrolysis reaction time is 1-60 min. For example, it can be 1 min, 5 min, 10 min, 12 min, 15 min, 18 min, 20 min, 22 min, 25 min, 28 min, 30 min, 32 min, 35 min, 38 min, 40 min, 42 min, 45 min, 48 min, 50 min, 52 min, 55 min, 58 min, 60 min, etc., or a range of any of the above values. Therefore, the degree of hydrolysis of the first silicon source can be controlled, and the particle size of the microspheres can be adjusted.
[0046] S200: Add alkali to the solution after the hydrolysis reaction to carry out a condensation reaction and obtain a microsphere dispersion.
[0047] According to some embodiments of this application, the alkali is selected from at least one of ammonia, sodium carbonate, sodium hydroxide, and potassium hydroxide. Therefore, by using an alkali selected from the above types, an alkaline environment can be created in the solution, ensuring the silanol condensation reaction proceeds.
[0048] According to some embodiments of this application, after adding alkali to the solution following the hydrolysis reaction, the pH value of the solution is 9.0-11.0. For example, it can be 9.0, 9.2, 9.4, 9.6, 9.8, 10.0, 10.2, 10.4, 10.6, 10.8, 11.0, etc., or it can be a range of any of the above values.
[0049] According to some embodiments of this application, the condensation reaction time is 1-5 hours, for example, it can be 1 hour, 1.2 hours, 1.5 hours, 1.8 hours, 2 hours, 2.2 hours, 2.5 hours, 2.8 hours, 3 hours, 3.2 hours, 3.5 hours, 3.8 hours, 4 hours, 4.2 hours, 4.5 hours, 4.8 hours, 5 hours, etc., or it can be any range of the above values. Therefore, by controlling the condensation reaction time within the above specific range, the wall thickness of the polysilsesquioxane microspheres can be controlled.
[0050] According to some embodiments of this application, the temperature of the condensation reaction is 30-80°C. For example, it can be 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, etc., or it can be any range of the above values.
[0051] S300: Add a second silicon source to the microsphere dispersion to obtain a multilayer microsphere dispersion.
[0052] According to some embodiments of this application, the second silicon source is an orthosilicate or a monosubstituted silane coupling agent. According to some embodiments of this application, the second silicon source includes one or more of methyltrimethoxysilane, propyltrimethoxysilane, vinyltrimethoxysilane, aminopropyltrimethoxysilane, methyl orthosilicate, and tetraethyl orthosilicate. Selecting an unsubstituted silicon source (such as methyl orthosilicate or tetraethyl orthosilicate) can improve the shell density and mechanical strength, effectively resisting external impacts during subsequent centrifugation, washing, and application, and preventing the collapse of the hollow structure. Selecting a monosubstituted silane coupling agent (methyl / propyl / vinyl / aminopropyltrimethoxysilane) as the coating silane can adjust the shell flexibility and provide the microspheres with modifiability.
[0053] According to some embodiments of this application, the volume ratio of the first silicon source to the second silicon source is 1:(1-4). For example, it can be 1:1.0, 1:1.5, 1:2.0, 1:2.5, 1:3.0, 1:3.5, 1:4.0, or any range of the above values. The amount of the first silicon source determines the particle size and hybrid structure stability of the microsphere substrate, while the amount of the second silicon source determines the thickness, density, and functional density of the multilayer shells, ensuring coating uniformity and interlayer bonding. By controlling the volume ratio of the two sources within the above range, the cavity volume of the organic-inorganic hybrid silica hollow microspheres can be controlled, while ensuring the stability of the hollow structure and the uniformity of the shells.
[0054] S400: The multilayer microsphere dispersion is centrifuged and filtered sequentially to obtain a solid.
[0055] According to some embodiments of this application, when centrifuging the obtained multilayer microsphere dispersion, the centrifugation speed and time do not need to be strictly limited. The core criterion is that effective separation of the multilayer microspheres (solid phase) and the dispersion (liquid phase) can be achieved, and the separated solid product has no obvious agglomeration and its structure is intact. For example, the centrifugation speed can be selected from 2000-4000 r / min, and the centrifugation time can be selected from 5-20 min. Those skilled in the art can make adaptive adjustments to the speed and time according to the actual dispersion volume, microsphere particle size and concentration, provided that the above separation effect is met, all of which fall within the protection scope of this application.
[0056] S500: The solid is washed with alcohol to obtain the hollow silica microspheres.
[0057] According to some embodiments of this application, the alcohol washing is performed using anhydrous methanol, anhydrous ethanol, propanol, or isopropanol. Thus, alcohol washing can easily and readily remove phenyltrimethoxysilane oligomers from the interior of the microspheres.
[0058] According to some embodiments of this application, the alcohol washing time is 2-10 hours. For example, it can be 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours, 8 hours, 8.5 hours, 9 hours, 9.5 hours, 10 hours, or any range of the above values.
[0059] In a second aspect of this application, a hollow silica microsphere is proposed. According to embodiments of this application, the hollow silica microsphere is prepared using the method described in the first aspect. Thus, the hollow silica microsphere prepared by the method of this application possesses an organic-inorganic hybrid structure: the inorganic siloxane framework (-Si-O-Si-) endows the microsphere with excellent mechanical strength and thermal stability; the functional groups introduced by the organic phenyl groups and coupling agents enhance the compatibility of the microsphere with the organic matrix, while providing active sites for subsequent functional modifications (such as grafting catalysts, adsorbents, and conductive groups). Compared to purely inorganic or purely organic microspheres, this hybrid structure achieves a synergistic effect of "structural stability" and "functional tunability," expanding the application scenarios of the product (such as lithium-ion battery electrolyte additives, polymer composite fillers, catalyst supports, electronic packaging materials, etc.).
[0060] According to some embodiments of this application, the hollow silica microspheres contain organic groups.
[0061] It should be noted that the types of organic groups in the organic-inorganic hybrid silica hollow microspheres are jointly determined by the types of the first and second silicon sources. Specifically, the organic groups inside the microspheres are entirely determined by the type of the first silicon source. For example, when the first silicon source is only phenyltrimethoxysilane, the basic organic group in the core microsphere is phenyl; when the first silicon source is a complex system of phenyltrimethoxysilane and methyltrimethoxysilane, the basic organic group in the core microsphere is a combination of phenyl and methyl. The organic groups in the shell are determined by the type of the second silicon source: when the second silicon source is vinyltrimethoxysilane, vinyl groups are introduced into the shell; when the second silicon source is only tetraethyl orthosilicate (an unsubstituted silane without organic substituents), its hydrolysis and condensation only form a pure inorganic siloxane skeleton, and the shell does not contain any organic groups.
[0062] According to some embodiments of this application, the particle size of the silica hollow microspheres is 200-2000 nm. For example, it can be 200 nm, 500 nm, 1000 nm, 1500 nm, 2000 nm, etc., or it can be any range of the above values.
[0063] The embodiments of this application are described in detail below. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed in accordance with the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.
[0064] Example 1 1. Stir 1 ml of phenyltrimethoxysilane with 100 ml of water at 30 °C until the pH is about 7.0. Hydrolyze for 2 min, then adjust the pH to about 10.5 with 5% ammonia and react for 2 h to obtain a microsphere dispersion. 2. Adjust the pH of the microsphere dispersion from step 1 to 10.0, and then slowly add 1 ml of methyl orthosilicate to the dispersion to obtain a multilayer silica microsphere dispersion.
[0065] 3. Centrifuge and filter the dispersion from step 2 to obtain a solid. Soak and wash the solid in anhydrous ethanol solution for 5 hours to obtain organic-inorganic hybrid silica hollow microspheres.
[0066] Example 2 1. Stir 1 ml of phenyltrimethoxysilane with 100 ml of water at 30 °C until the pH is about 7.0. Hydrolyze for 10 min, then adjust the pH to about 10.5 with 5% ammonia and react for 2 h to obtain a microsphere dispersion. 2. Adjust the pH of the microsphere dispersion from step 1 to 10.0, then slowly add 1 ml of methyltrimethoxysilane to the dispersion, followed by 1 ml of methyl orthosilicate, to obtain a multilayer silica microsphere dispersion.
[0067] 3. Centrifuge and filter the dispersion from step 2 to obtain a solid. Soak and wash the solid in anhydrous ethanol solution for 5 hours to obtain organic-inorganic hybrid silica hollow microspheres.
[0068] Example 3 1. Stir 1 ml of phenyltrimethoxysilane with 100 ml of water at 30 °C until the pH is about 7.0. Hydrolyze for 2 min, then adjust the pH to about 10.5 with 5% ammonia and react for 2 h to obtain a microsphere dispersion. 2. Adjust the pH of the microsphere dispersion from step 1 to 10.0, then slowly add 1 ml of vinyltrimethoxysilane to the dispersion, followed by 1 ml of tetraethyl orthosilicate, to obtain a multilayer silica microsphere dispersion.
[0069] 3. Centrifuge and filter the dispersion from step 2 to obtain a solid. Soak and wash the solid in anhydrous ethanol solution for 5 hours to obtain organic-inorganic hybrid silica hollow microspheres.
[0070] Example 4 1. Stir 1 ml of phenyltrimethoxysilane with 100 ml of water at 30 °C until the pH is about 7.0. Hydrolyze for 2 min, then adjust the pH to about 10.5 with 5% ammonia and react for 2 h to obtain a microsphere dispersion. 2. Adjust the pH of the microsphere dispersion from step 1 to 10.0, and then slowly add 2 ml of a mixture of vinyltrimethoxysilane and tetraethyl orthosilicate (volume ratio 1:1) to the dispersion to obtain a multilayer silica microsphere dispersion.
[0071] 3. Centrifuge and filter the dispersion from step 2 to obtain a solid. Soak and wash the solid in anhydrous ethanol solution for 5 hours to obtain organic-inorganic hybrid silica hollow microspheres.
[0072] Example 5 1. Stir 0.8 ml phenyltrimethoxysilane, 0.2 ml methyltrimethoxysilane and 100 ml water at 30 °C until the pH is about 7.0. Hydrolyze for 2 min, then adjust the pH to about 10.5 with 5% ammonia water and react for 2 h to obtain microsphere dispersion. 2. Adjust the pH of the microsphere dispersion from step 1 to 10.0, then slowly add 1 ml of vinyltrimethoxysilane to the dispersion, followed by 1 ml of tetraethyl orthosilicate, to obtain a multilayer silica microsphere dispersion.
[0073] 3. Centrifuge and filter the dispersion from step 2 to obtain a solid. Soak and wash the solid in anhydrous ethanol solution for 10 hours to obtain organic-inorganic hybrid silica hollow microspheres.
[0074] Example 6 1. Stir 1 ml of phenyltrimethoxysilane with 100 ml of water at 30 °C until the pH is approximately 2.0. Hydrolyze for 2 min, then adjust the pH to approximately 10.5 with 5% ammonia and react for 2 h to obtain a microsphere dispersion. 2. Adjust the pH of the microsphere dispersion from step 1 to 10.0, and then slowly add 1 ml of methyl orthosilicate to the dispersion to obtain a multilayer silica microsphere dispersion.
[0075] 3. Centrifuge and filter the dispersion from step 2 to obtain a solid. Soak and wash the solid in anhydrous ethanol solution for 10 hours to obtain organic-inorganic hybrid silica hollow microspheres.
[0076] Example 7 1. Stir 1 ml of phenyltrimethoxysilane with 100 ml of water at 30 °C until the pH is about 7.0. Hydrolyze for 2 min, then adjust the pH to about 10.5 with 5% ammonia and react for 2 h to obtain a microsphere dispersion. 2. Adjust the pH of the microsphere dispersion from step 1 to 10.0, and then slowly add 1 ml of methyl orthosilicate to the dispersion to obtain a multilayer silica microsphere dispersion.
[0077] 3. Centrifuge and filter the dispersion from step 2 to obtain a solid. Soak and wash the solid in anhydrous ethanol solution for 10 hours to obtain organic-inorganic hybrid silica hollow microspheres.
[0078] Example 8 1. Stir 2 ml of phenyltrimethoxysilane with 100 ml of water at 30 °C until the pH is about 7.0. Hydrolyze for 2 min, then adjust the pH to about 10.5 with 5% ammonia and react for 2 h to obtain a microsphere dispersion. 2. Adjust the pH of the microsphere dispersion from step 1 to 10.0, and then slowly add 5 ml of methyl orthosilicate to the dispersion to obtain a multilayer silica microsphere dispersion.
[0079] 3. Centrifuge and filter the dispersion from step 2 to obtain a solid. Soak and wash the solid in anhydrous ethanol solution for 10 hours to obtain organic-inorganic hybrid silica hollow microspheres.
[0080] Example 9 1. Stir 5 ml of phenyltrimethoxysilane with 100 ml of water at 30 °C until the pH is about 7.0. Hydrolyze for 2 min, then adjust the pH to about 10.5 with 5% ammonia and react for 2 h to obtain a microsphere dispersion. 2. Adjust the pH of the microsphere dispersion from step 1 to 10.0, and then slowly add 5 ml of methyl orthosilicate to the dispersion to obtain a multilayer silica microsphere dispersion.
[0081] 3. Centrifuge and filter the dispersion from step 2 to obtain a solid. Soak and wash the solid in anhydrous ethanol solution for 10 hours to obtain organic-inorganic hybrid silica hollow microspheres.
[0082] Example 10 1. Stir 1 ml of phenyltrimethoxysilane with 100 ml of water at 30 °C until the pH is approximately 2.0. Hydrolyze for 1 min, then adjust the pH to approximately 10.5 with 5% ammonia and react for 2 h to obtain a microsphere dispersion. 2. Adjust the pH of the microsphere dispersion from step 1 to 10.0, and then slowly add 1 ml of methyl orthosilicate to the dispersion to obtain a multilayer silica microsphere dispersion.
[0083] 3. Centrifuge and filter the dispersion from step 2 to obtain a solid. Soak and wash the solid in anhydrous ethanol solution for 10 hours to obtain organic-inorganic hybrid silica hollow microspheres.
[0084] Example 11 1. Stir 1 ml of phenyltrimethoxysilane with 100 ml of water at 30 °C until the pH is approximately 2.0. Hydrolyze for 20 min, then adjust the pH to approximately 10.5 with 5% ammonia and react for 2 h to obtain a microsphere dispersion. 2. Adjust the pH of the microsphere dispersion from step 1 to 10.0, and then slowly add 1 ml of methyl orthosilicate to the dispersion to obtain a multilayer silica microsphere dispersion.
[0085] 3. Centrifuge and filter the dispersion from step 2 to obtain a solid. Soak and wash the solid in anhydrous ethanol solution for 10 hours to obtain organic-inorganic hybrid silica hollow microspheres.
[0086] Example 12 1. Stir 1 ml of phenyltrimethoxysilane with 100 ml of water at 30 °C until the pH is approximately 2.0. Hydrolyze for 60 min, then adjust the pH to approximately 10.5 with 5% ammonia and react for 2 h to obtain a microsphere dispersion. 2. Adjust the pH of the microsphere dispersion from step 1 to 10.0, and then slowly add 1 ml of methyl orthosilicate to the dispersion to obtain a multilayer silica microsphere dispersion.
[0087] 3. Centrifuge and filter the dispersion from step 2 to obtain a solid. Soak and wash the solid in anhydrous ethanol solution for 10 hours to obtain organic-inorganic hybrid silica hollow microspheres.
[0088] Example 13 1. Stir 1 ml of phenyltrimethoxysilane with 100 ml of water at 30 °C until the pH is about 7.0. Hydrolyze for 2 min, then adjust the pH to about 10.5 with 5% ammonia and react for 2 h to obtain a microsphere dispersion. 2. Adjust the pH of the microsphere dispersion from step 1 to 10.0, and then slowly add 1 ml of methyl orthosilicate to the dispersion to obtain a multilayer silica microsphere dispersion.
[0089] 3. Centrifuge and filter the dispersion from step 2 to obtain a solid. Soak and wash the solid in anhydrous ethanol solution for 10 minutes to obtain organic-inorganic hybrid silica hollow microspheres.
[0090] Example 14 1. Stir 1 ml of phenyltrimethoxysilane with 100 ml of water at 30 °C until the pH is about 7.0. Hydrolyze for 2 min, then adjust the pH to about 10.5 with 5% ammonia and react for 2 h to obtain a microsphere dispersion. 2. Adjust the pH of the microsphere dispersion from step 1 to 10.0, and then slowly add 1 ml of methyl orthosilicate to the dispersion to obtain a multilayer silica microsphere dispersion.
[0091] 3. Centrifuge and filter the dispersion from step 2 to obtain a solid. Soak and wash the solid in anhydrous ethanol solution for 2 hours to obtain organic-inorganic hybrid silica hollow microspheres.
[0092] Example 15 1. Stir 1 ml of phenyltrimethoxysilane with 100 ml of water at 30 °C until the pH is about 7.0. Hydrolyze for 2 min, then adjust the pH to about 10.5 with 5% ammonia and react for 2 h to obtain a microsphere dispersion. 2. Adjust the pH of the microsphere dispersion from step 1 to 10.0, and then slowly add 1 ml of methyl orthosilicate to the dispersion to obtain a multilayer silica microsphere dispersion.
[0093] 3. Centrifuge and filter the dispersion from step 2 to obtain a solid. Soak and wash the solid in anhydrous methanol solution for 10 hours to obtain organic-inorganic hybrid silica hollow microspheres.
[0094] Comparative Example 1 1. Stir 1 ml of phenyltrimethoxysilane with 100 ml of water at 30 °C until the pH is about 7.0. Hydrolyze for 2 min, then adjust the pH to about 10.5 with 5% ammonia and react for 24 h to obtain a microsphere dispersion. 2. Centrifuge and filter the dispersion from step 1 to obtain a solid. Soak and wash the solid in anhydrous methanol solution for 10 hours to obtain organic-inorganic hybrid silica hollow microspheres.
[0095] SEM and TEM tests were performed on the silica hollow microspheres prepared in Examples 1-15, and the particle size and hollowness of the microspheres were statistically analyzed. The experimental results are shown in Table 1. As can be seen from the experimental results of Examples 1 and 10-12, the hollow volume of the prepared silica hollow microspheres gradually decreases with increasing hydrolysis time. Examples 6-7 show that the particle size of the silica hollow microspheres is related to the pH during hydrolysis; as the pH approaches neutral, the particle size of the silica hollow microspheres gradually increases. Furthermore, analysis of the data from Examples 1, 7, and 13-14 reveals that insufficient alcohol washing time also leads to a gradual reduction in the hollow volume of the silica hollow microspheres. In summary, by synergistically controlling the two key process parameters—hydrolysis pH and hydrolysis time, and alcohol washing time—precise and controllable control of the hollow volume of silica hollow microspheres can be achieved. Furthermore, as shown in Examples 7-9, the particle size of the silica hollow microspheres is related to the amount of silicon source used. With a fixed amount of water, the microsphere particle size gradually increases with the increase of silicon source. Therefore, the particle size of the silica hollow microspheres can be controlled by adjusting the amount of silicon source used.
[0096] Scanning electron microscopy images of the silica hollow microspheres prepared in Examples 1-5 and Comparative Example 1 are shown below. Figure 2-7 As shown, the microspheres in Comparative Example 1 exhibit significant deformation, while the silica hollow microspheres prepared by the method of this application not only have a larger hollow structure inside, but also have better sphericity.
[0097] Table 1
[0098] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.
[0099] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.
Claims
1. A method for preparing hollow silica microspheres, characterized in that, include: The first silicon source is mixed with the first solution, and the pH is adjusted to allow the first silicon source to undergo a hydrolysis reaction. An alkali was added to the solution after the hydrolysis reaction to carry out a condensation reaction and obtain a microsphere dispersion. A second silicon source is added to the microsphere dispersion to obtain a multilayer microsphere dispersion; The multilayer microsphere dispersion was sequentially centrifuged and filtered to obtain a solid. The solid was washed with alcohol to obtain the hollow silica microspheres.
2. The preparation method according to claim 1, characterized in that, The first silicon source is a monosubstituted silane coupling agent; the second silicon source is an orthosilicate or a monosubstituted silane coupling agent.
3. The preparation method according to claim 2, characterized in that, The first silicon source includes phenyltrimethoxysilane, and optionally one or more of methyltrimethoxysilane, propyltrimethoxysilane, aminopropyltrimethoxysilane, vinyltrimethoxysilane, and octyltrimethoxysilane; The second silicon source includes one or more of methyltrimethoxysilane, propyltrimethoxysilane, vinyltrimethoxysilane, aminopropyltrimethoxysilane, methyl orthosilicate, and tetraethyl orthosilicate.
4. The preparation method according to claim 3, characterized in that, The volume ratio of the first silicon source to the second silicon source is 1:(1-4).
5. The preparation method according to claim 1, characterized in that, The alcohol washing was performed using anhydrous methanol, anhydrous ethanol, propanol, and isopropanol. And / or, the alcohol washing time is 2-10 hours.
6. The preparation method according to claim 1, characterized in that, The volume ratio of the first silicon source to the first solution is 1:(20-100); And / or, the first solution is selected from an aqueous solution or an alcohol-water solution, wherein the alcohol-water volume ratio is 1:99-1:1; And / or, after pH adjustment, the pH value of the solution is 2.0-7.
0.
7. The preparation method according to claim 1, characterized in that, The hydrolysis reaction is carried out at a temperature of 30-80℃. And / or, the hydrolysis reaction takes 1-60 min.
8. The preparation method according to claim 1, characterized in that, The alkali is selected from at least one of ammonia, sodium carbonate, sodium hydroxide, and potassium hydroxide; And / or, after adding alkali to the solution following the hydrolysis reaction, the pH value of the solution is 9.0-11.0; And / or, the condensation reaction takes 1-5 hours; And / or, the temperature of the condensation reaction is 30-80°C.
9. A type of hollow silica microsphere, characterized in that, The hollow silica microspheres are prepared by the method described in any one of claims 1-8.
10. The hollow silica microspheres according to claim 9, characterized in that, The hollow silica microspheres contain organic groups; Optionally, the particle size of the hollow silica microspheres is 200-2000 nm.