Hollow silicon dioxide microsphere based on silicon-based amphiphilic random copolymer and preparation method of hollow silicon dioxide microsphere

Abstract

The invention relates to the technical field of preparation of silicon dioxide microspheres, and discloses hollow silicon dioxide microspheres based on a silicon-based amphiphilic random copolymer and a preparation method of the hollow silicon dioxide microspheres. The preparation method comprises the following steps: carrying out hydrolytic condensation on tetraalkoxy silane, a hydrophobic silane compound and a hydrophilic silane compound in an organic solvent under the catalysis of inorganic acid, and removing the solvent to obtain a silicon-based amphiphilic random copolymer; carrying out self-assembly on the silicon-based amphiphilic random copolymer in water to form a vesicle structure; and carrying out a curing reaction on the vesicle structure through base catalysis, and then washing and drying to obtain the hollow silicon dioxide microspheres. A silicon-based amphiphilic random copolymer obtained by hydrolytic condensation of a silane compound catalyzed by inorganic acid is self-assembled in water to form a vesicle structure, then alkoxy silane in a vesicle hydrophobic region is subjected to hydrolytic condensation to form a silicon dioxide shell layer, and the hollow silicon dioxide microspheres are obtained; the preparation method is simple in process, good in reproducibility, low in equipment requirement and suitable for large-scale mass production.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of silica microsphere preparation, and particularly relates to a hollow silica microsphere based on a silicon-based amphiphilic random copolymer and a preparation method thereof. BACKGROUND

[0002] Hollow silica nanoparticles have attracted much attention due to their higher specific surface area, higher insulation performance, lower thermal conductivity, excellent light scattering-transmission performance and material loading-release performance. Based on these characteristics, hollow silica nanoparticles have been widely concerned in the fields of chips, sensors, drug delivery systems, energy storage, catalysts and optics.

[0003] At present, the preparation methods of hollow silica mainly include a hard template method and a soft template method. The hard template method is the most typical and widely used method, which usually uses polystyrene microspheres as templates, and the silica shell structure can be controlled by the morphology and size of the polystyrene microspheres, catalysts, reaction solvents and reaction time. However, the polystyrene microsphere template needs to be surface modified, and the template needs to be removed through heat treatment or chemical treatment, so the process is complicated, the cost is high, and it is difficult to synthesize on a large scale. Moreover, the hollow structure of silica is prone to deformation and collapse during the removal of the template, which destroys the structural integrity.

[0004] In comparison, the soft template method forms a silica shell on the surface of a soft template such as an emulsion droplet or a polymer micelle particle through hydrolysis and condensation of a silicon source, and then removes the soft template to obtain a hollow silica microsphere, which has the advantages of simple synthesis process and good scalability. For example, the patent with the publication number CN115385345A discloses a preparation method of hollow silica microspheres. The method forms an emulsion with a water-oil-water structure through a water-in-oil and oil-in-water two-step method, and makes the silicon source compound hydrolyze and condense on the oil-water interface through aging to form silica. Then, the hollow silica microspheres are obtained through washing, drying and sintering. However, the silica microspheres prepared by the method have a wide size distribution, which limits their application. SUMMARY

[0005] The application provides a hollow silica microsphere based on a silicon-based amphiphilic random copolymer and a preparation method thereof, and aims to solve the technical problems of complex preparation process, poor reproducibility and uneven particle size distribution of silica microspheres in the prior art.

[0006] In order to achieve the above-mentioned purpose, the following technical solutions are adopted in the application.

[0007] In a first aspect, the application provides a preparation method of a hollow silica microsphere based on a silicon-based amphiphilic random copolymer, which comprises the following steps:

[0008] S1, hydrolytic condensation of tetraalkoxysilane, hydrophobic silane compound and hydrophilic silane compound in organic solvent by inorganic acid catalysis, removal of solvent to obtain silicon-based amphiphilic random copolymer;

[0009] S2, self-assembly of silicon-based amphiphilic random copolymer in water to form vesicular structure;

[0010] S3, curing reaction of the vesicular structure by base catalysis; collection of solid phase, washing, drying to obtain hollow silica microspheres.

[0011] Preferably, the tetraalkoxysilane includes at least one of methoxy, ethoxy or isopropoxy;

[0012] The hydrophobic silane compound includes at least one of alkylsilane, vinylsilane, phenylsilane or acryloxy silane;

[0013] The hydrophilic silane compound includes at least one of aminosilane, sulfonic silane, epoxy silane, diethylene glycol monomethyl ether silane, triethylene glycol monomethyl ether silane or polyethylene glycol monomethyl ether silane;

[0014] The organic solvent includes at least one of methanol, ethanol, isopropanol or butanol.

[0015] Further preferably, the tetraalkoxysilane includes tetraethyl orthosilicate;

[0016] The hydrophobic silane compound includes at least one of phenyltriethoxysilane, n-propyltriethoxysilane, n-octyltriethoxysilane or methacryloxypropyltriethoxysilane;

[0017] The hydrophilic silane compound includes at least one of γ-glycidoxypropyltriethoxysilane, 3-aminopropyltriethoxysilane or polyethylene glycol 500 monomethyl ether triethoxysilane.

[0018] Preferably, the mass ratio of the hydrophobic silane compound to tetraalkoxysilane is 0-0.5:1;

[0019] The mass ratio of the hydrophilic silane compound to tetraalkoxysilane is 0.2-0.6:1.

[0020] Preferably, the inorganic acid includes any one of hydrochloric acid, nitric acid or sulfuric acid;

[0021] The mass ratio of inorganic acid to tetraalkoxysilane is 0.05-0.2:1.

[0022] Preferably, the reaction temperature of the hydrolytic condensation in S1 is 60-160℃, and the reaction time is 4-12h;

[0023] The solvent is removed by atmospheric high-temperature distillation, vacuum distillation or thin film evaporation.

[0024] Preferably, the silicon-based amphiphilic random copolymer in step S2 is added to water, and self-assembly is carried out under stirring at room temperature.

[0025] Preferably, the mass ratio of water to the silicon-based amphiphilic random copolymer is 5-20:1.

[0026] Preferably, the vesicular structure is subjected to a curing reaction under the catalysis of a base.

[0027] The base catalyst is added to the vesicular structure, the pH is adjusted to 10-11, and stirring is carried out until uniform; then the temperature is raised to 80-90°C to carry out the curing reaction.

[0028] Further preferably, the base catalyst includes aqueous ammonia, aqueous sodium hydroxide or aqueous potassium hydroxide.

[0029] The stirring time is 2-3h.

[0030] The curing reaction time is 24-36h.

[0031] In a second aspect, the present application provides the hollow silica microspheres prepared by the above preparation method.

[0032] Compared with the prior art, the present application has the following advantages:

[0033] The present application forms a vesicular structure by self-assembly of a silicon-based amphiphilic random copolymer obtained by inorganic acid catalysis of hydrolysis and condensation of silane compounds in water, and then hydrolysis and condensation of the alkoxysilane in the hydrophobic region of the vesicle to form a silica shell layer, thereby obtaining hollow silica microspheres; the preparation method is simple, reproducible, and has low requirements for equipment, and is suitable for large-scale production.

[0034] The hollow silica microspheres prepared by the present application have the advantages of good uniformity, controllable particle size, high porosity, etc., and can be applied to catalysis, biological medicine, optics, heat insulation, high-frequency and high-speed communication, etc. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed in the embodiment description. Obviously, the drawings in the following description are only some embodiments described in the present application, and for those skilled in the art, other drawings can also be obtained without creative labor on the basis of these drawings.

[0036] Figure 1 The transmission electron microscope image of the hollow silica microspheres prepared in Example 1;

[0037] Figure 2 Dynamic light scattering data plot of the hollow silica microspheres prepared for Example 1 ;

[0038] Figure 3 Transmission electron micrograph of the hollow silica microspheres prepared for Example 2;

[0039] Figure 4 Dynamic light scattering data plot of the hollow silica microspheres prepared for Example 2;

[0040] Figure 5 Transmission electron micrograph of the hollow silica microspheres prepared for Example 3;

[0041] Figure 6 Dynamic light scattering data plot of the hollow silica microspheres prepared for Example 3. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0043] In the following description of the present embodiments, the terms "comprise", "contain", "have" and "include" and the like are open terms, i.e., meaning including but not limited to.

[0044] In the following description of the present embodiments, the term "and / or" is used to describe the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B, which can represent the following three cases: A exists alone, B exists alone and A and B exist simultaneously. Wherein A and B can be singular or plural. The character " / " generally represents that the front and rear associated objects are in an "or" relationship.

[0045] In the following description of the present embodiments, the term "at least one" means one or more, and "multiple" means two or more. "At least one of the following" or the like means any combination of these items, including any combination of single item or multiple items. For example, "at least one of a, b or c", or "at least one of a, b and c", can represent a, b, c, a-b (i.e., a and b), a-c, b-c, or a-b-c, wherein a, b and c can be single or multiple.

[0046] The terminology used in the embodiments of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. As used in the description of the embodiments of the present application and the appended claims, the singular forms "a," "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0047] Those skilled in the art should understand that, in the following description of the embodiments of the present application, the order of the serial numbers does not mean the order of execution, and part or all of the steps can be executed in parallel or in sequence, and the execution order of each process should be determined according to its function and inherent logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0048] Those skilled in the art should understand that the numerical ranges in the embodiments of the present application should be understood as each intermediate value between the upper limit and the lower limit of the range. Each smaller range between any stated value or stated range and any other stated value or intermediate value within the stated range is also included in the present application. The upper limit and the lower limit of these smaller ranges can be independently included or excluded from the range.

[0049] Unless otherwise defined, technical / scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials related to the documents. In the event of a conflict between any incorporated document and the content of this specification, the content of this specification controls.

[0050] In a first aspect, the present application provides a preparation method of hollow silica microspheres based on silicon-based amphiphilic random copolymer, comprising:

[0051] S1, tetraalkoxysilane, hydrophobic silane compound and hydrophilic silane compound are hydrolyzed and condensed in an organic solvent by inorganic acid catalysis, and after removing the solvent, a silicon-based amphiphilic random copolymer is obtained;

[0052] In the present application, the alkoxyl group of the tetraalkoxysilane includes at least one of methoxyl, ethoxyl or isopropoxyl; the tetraalkoxysilane is preferably tetraethyl orthosilicate.

[0053] The hydrophobic silane compound contains a hydrophobic group; the hydrophobic silane compound includes at least one of alkylsilane, vinylsilane, phenylsilane or acryloyloxy silane, and in the present application, any one or a mixture of two or more of phenyltriethoxysilane, n-propyltriethoxysilane, n-octyltriethoxysilane or methacryloyloxypropyltriethoxysilane can be used.

[0054] The hydrophilic silane compound contains a hydrophilic group; the hydrophilic silane compound includes at least one of an amino silane, a sulfonic acid group silane, an epoxy group silane, a diethylene glycol monomethyl ether silane, a triethylene glycol monomethyl ether silane, or a polyethylene glycol monomethyl ether silane. Among them, the polyethylene glycol methyl ether group silane preferably has a molecular weight of 350-2000, such as a molecular weight of 350, 500, 800, 1000, or 2000.

[0055] In the present application, the hydrophilic silane compound can be selected from any one or a mixture of two or more of γ-glycidyl ether oxypropyl triethoxysilane, 3-aminopropyl triethoxysilane, or polyethylene glycol 500 monomethyl ether triethoxysilane.

[0056] The organic solvent includes at least one of methanol, ethanol, isopropanol, or butanol.

[0057] In the present application, the mass ratio of the hydrophobic silane compound to the tetraalkoxysilane is preferably 0-0.5:1, and the mass ratio of the hydrophilic silane compound to the tetraalkoxysilane is 0.2-0.6:1.

[0058] In the present application, the inorganic acid includes any one of hydrochloric acid, nitric acid, or sulfuric acid; the mass ratio of the inorganic acid to the tetraalkoxysilane is preferably 0.05-0.2:1. The reaction temperature of the hydrolysis condensation is 60-160°C, and the reaction time is 4-12h.

[0059] After the hydrolysis condensation reaction, the solvent is preferably removed by normal pressure high temperature distillation, reduced pressure distillation, or thin film evaporation to obtain the silicon-based amphiphilic random copolymer.

[0060] S2, the silicon-based amphiphilic random copolymer is self-assembled in water to form a vesicular structure;

[0061] Specifically, the silicon-based amphiphilic random copolymer is added to water and stirred at a speed of 200-5000r / min at room temperature for self-assembly; wherein the mass ratio of water to the silicon-based amphiphilic random copolymer is 5-20:1.

[0062] S3, the vesicular structure is subjected to a curing reaction under the catalysis of a base; the solid phase is collected, washed, and dried to obtain the hollow silica microspheres.

[0063] Specifically, a base catalyst is added to the vesicular structure, the pH is adjusted to 10-11, and stirring is performed for 2-4h; then the temperature is raised to 80-90°C for a curing reaction, and the curing reaction time is preferably 24-36h; wherein the base catalyst can be selected from aqueous ammonia, an aqueous sodium hydroxide solution, or an aqueous potassium hydroxide solution. The product after the curing reaction is centrifuged to collect the solid phase, which is sequentially washed with deionized water and ethanol, and then dried to a constant weight to obtain the hollow silica microspheres.

[0064] The present application obtains the hollow silica microspheres by self-assembling the silicon-based amphiphilic random copolymer obtained by hydrolysis and condensation of silane compound in water to form a vesicle structure, and then hydrolyzing and condensing the alkoxysilane in the hydrophobic region of the vesicle to form a silica shell. The preparation method is simple in process, good in reproducibility, low in requirement for equipment, and suitable for large-scale production.

[0065] The hollow silica microspheres prepared by the present application have the advantages of good uniformity, controllable particle size, high porosity, etc. The size distribution is uniform, and the hollow silica microspheres can be applied to catalysis, biological medicine, optics, heat insulation, high-frequency and high-speed communication, etc.

[0066] The present application is further described below by examples.

[0067] Example 1

[0068] The present embodiment provides a preparation method of nano hollow silica microspheres, comprising:

[0069] S1, 208 g of tetraethyl orthosilicate, 100 g of γ-glycidoxypropyl triethoxysilane and 50 g of ethanol are uniformly mixed, and after stirring for 5 min, 10 g of hydrochloric acid (mass fraction of 37%) and 5 g of deionized water are uniformly mixed, and then the temperature is raised to 80℃ and reacted for 12 h. After the reaction is completed, the solvent and low molecular weight compounds in the system are quickly removed by vacuum distillation to obtain a silicon-based amphiphilic random copolymer with certain viscosity and flowability;

[0070] S2, 40 g of the silicon-based amphiphilic random copolymer is quickly added to 400 mL of deionized water, and stirred at a speed of 600 rpm at room temperature for 5 min to obtain a transparent slightly white solution;

[0071] S3, 20 mL of 28% ammonia water is added to the solution of S2, and after stirring at room temperature for 2 h, the temperature is raised to 80℃ and continues to stir for 24 h to obtain a transparent slightly opalescent solution;

[0072] The solution is centrifuged at a speed of 12000 rpm for 30 min, and the nanoparticles are collected; the nanoparticles are washed twice with deionized water and once with ethanol, and dried in a 60℃ oven to constant weight to obtain a white powder, i.e. hollow silica microspheres.

[0073] The transmission electron microscope (SEM) of the hollow silica microspheres prepared in Example 1 is shown in Figure 1 The particles are hollow structures, the size is 20-50 nm, the wall thickness is about 8 nm, and the particle size distribution is uniform.

[0074] The dynamic light scattering (DLS) data of the hollow silica microspheres prepared in Example 1 is shown in Figure 2 Figure 2 ​It can be seen that the Z-average size of the hollow silica microsphere particles is 37.93 nm, and the PDI is 0.185, indicating that the size distribution of the hollow nanoparticles is uniform.

[0075] Example 2

[0076] The present embodiment provides a preparation method of nano hollow silica microspheres, comprising:

[0077] S1, 312 g of tetraethyl orthosilicate, 100 g of γ-glycidyl ether propyl triethoxysilane and 100 g of ethanol are uniformly mixed, and after stirring for 5 min, 15 g of hydrochloric acid (mass fraction of 37%) and 10 g of deionized water are added and uniformly mixed, and then the temperature is raised to 80°C and reacted for 12 h. After the reaction is completed, the solvent and low molecular weight compounds in the system are quickly removed by vacuum distillation to obtain a silicon-based amphiphilic random copolymer with certain viscosity and flowability;

[0078] S2, 40 g of the silicon-based amphiphilic random copolymer is quickly added to 400 mL of deionized water, and stirred at a speed of 600 rpm for 5 min at room temperature to obtain a transparent slightly white solution;

[0079] S3, 20 mL of 28% ammonia water is added to the solution of S2, and after stirring at room temperature for 2 h, the temperature is raised to 80°C and continues to stir for 24 h to obtain a transparent slightly milky solution;

[0080] The solution is centrifuged at a speed of 12000 rpm for 30 min, and the nanoparticles are collected; the nanoparticles are washed twice with deionized water and once with ethanol, and dried in a 60°C oven to constant weight to obtain a white powder, i.e. hollow silica microspheres.

[0081] The transmission electron microscopy (TEM) image of the hollow silica microspheres prepared in Example 2 is shown in Figure 3 The hollow silica microsphere particles are hollow structures, with a size of 40-80 nm and a wall thickness of about 8 nm, and the particle size distribution is relatively uniform.

[0082] The DLS data of the hollow silica microspheres prepared in Example 2 is shown in Figure 4 The Z-average size of the hollow silica microsphere particles is 64.04 nm, and the PDI is 0.121.

[0083] Example 3

[0084] The present embodiment provides a preparation method of nano hollow silica microspheres, comprising:

[0085] S1, 312 g of tetraethyl orthosilicate, 100 g of polyethylene glycol 500 monomethyl ether triethoxysilane propyl ether, 30 g of phenyl triethoxysilane and 100 g of ethanol were uniformly mixed, after stirring for 5 min, 15 g of hydrochloric acid (mass fraction of 37%) and 10 g of deionized water were added respectively and uniformly mixed, and the temperature was raised to 80°C and reacted for 12 h. After the reaction was completed, the solvent and low molecular weight compounds in the system were quickly removed by distillation under reduced pressure to obtain a silicon-based amphiphilic random copolymer with certain viscosity and flowability;

[0086] S2, 40 g of the silicon-based amphiphilic random copolymer was quickly added to 400 mL of deionized water, and stirred at a speed of 600 rpm for 5 min at room temperature to obtain a transparent slightly white solution;

[0087] S3, 20 mL of 28% ammonia water was added to the solution of S2, and stirred at room temperature for 2 h, and then the temperature was raised to 80°C and stirred for 24 h to obtain a transparent slightly milky solution;

[0088] The solution was centrifuged at a speed of 12000 rpm for 30 min, and the nanoparticles were collected; the nanoparticles were washed twice with deionized water and once with ethanol, and dried in a 60°C oven to constant weight to obtain a white powder, i.e. hollow silica microspheres.

[0089] The transmission electron microscope image of the hollow silica microspheres prepared in Example 3 is shown in Figure 5 The hollow silica microsphere particles are hollow structures, the size is 50-150 nm, the wall thickness is about 10 nm, and the particle size distribution is relatively uniform.

[0090] The DLS data of the hollow silica microspheres prepared in Example 3 is shown in Figure 6 The hollow silica microsphere particle size is unimodal distribution, the Z average size is 137.5 nm, and the PDI is 0.120, indicating that the particle size distribution is uniform.

[0091] The preparation method of the present application is simple, reproducible, low in equipment requirements and suitable for large-scale production; from the test results, it can be seen that the hollow silica microspheres prepared by the present application are uniform, the particle size is controllable and the porosity is high.

[0092] Although the present application has been described in detail in the specification and specific embodiments, some modifications or improvements can be made on the basis of the present application, which is obvious to those skilled in the art. Therefore, these modifications or improvements made on the basis of not deviating from the spirit of the present application, all belong to the scope of protection claimed by the present application.

Claims

1. A method for preparing hollow silica microspheres based on silicon-based amphiphilic random copolymers, characterized in that, include: S1, tetraalkoxysilane, hydrophobic silane compound and hydrophilic silane compound are hydrolyzed and condensed in an organic solvent by inorganic acid catalysis, and after removing the solvent, a silicon-based amphiphilic random copolymer is obtained. S2, a silicon-based amphiphilic random copolymer is self-assembled in water to form a vesicle structure; S3, the vesicle structure is solidified by alkaline catalysis; The solid phase was collected, washed, and dried to obtain hollow silica microspheres.

2. The preparation method according to claim 1, characterized in that, In the tetraalkoxysilane, the alkoxy group includes at least one of methoxy, ethoxy, or isopropoxy. The hydrophobic silane compound includes at least one of alkylsilane, vinylsilane, phenylsilane, or acryloyloxysilane; The hydrophilic silane compound includes at least one of aminosilane, sulfonic acid silane, epoxy silane, diethylene glycol monomethyl ether silane, triethylene glycol monomethyl ether silane or polyethylene glycol monomethyl ether silane; The organic solvent includes at least one of methanol, ethanol, isopropanol, and butanol.

3. The preparation method according to claim 2, characterized in that, The tetraalkoxysilane includes tetraethyl orthosilicate; The hydrophobic silane compound includes at least one of phenyltriethoxysilane, n-propyltriethoxysilane, n-octyltriethoxysilane, or methacryloxypropyltriethoxysilane; The hydrophilic silane compound includes at least one of γ-glycidoxypropyltriethoxysilane, 3-aminopropyltriethoxysilane, or polyethylene glycol 500 monomethyl ether triethoxysilylpropyl ether.

4. The preparation method according to claim 1, characterized in that, The mass ratio of the hydrophobic silane compound to the tetraalkoxysilane is 0~0.5:1; The mass ratio of the hydrophilic silane compound to the tetraalkoxysilane is 0.2~0.6:

1.

5. The preparation method according to claim 1, characterized in that, The inorganic acid includes any one of hydrochloric acid, nitric acid, or sulfuric acid; The mass ratio of inorganic acid to tetraalkoxysilane is 0.05~0.2:

1.

6. The preparation method according to claim 1, characterized in that, The hydrolysis-condensation reaction temperature described in S1 is 60~160℃, and the reaction time is 4~12h; Solvents are removed by atmospheric pressure high-temperature distillation, vacuum distillation, or thin-film evaporation.

7. The preparation method according to claim 1, characterized in that, In step S2, the silicon-based amphiphilic random copolymer is added to water and stirred at room temperature to carry out self-assembly; The mass ratio of water to the silicon-based amphiphilic random copolymer is 5~20:

1.

8. The preparation method according to claim 1, characterized in that, The process of solidifying the vesicle structure using an alkaline catalysis method specifically involves: An alkaline catalyst was added to the vesicle structure, the pH was adjusted to 10-11, and the mixture was stirred until homogeneous. Then the temperature was raised to 80-90℃ to carry out the curing reaction.

9. The preparation method according to claim 8, characterized in that, The alkaline catalyst includes ammonia, sodium hydroxide aqueous solution, or potassium hydroxide aqueous solution; The stirring time is 2-3 hours; The curing reaction takes 24 to 36 hours.

10. Hollow silica microspheres prepared by the preparation method according to any one of claims 1-9.

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