CN110508222B - Monodisperse core-shell microsphere with mesoporous silica shell and preparation method thereof - Google Patents
Monodisperse core-shell microsphere with mesoporous silica shell and preparation method thereof Download PDFInfo
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Abstract
The invention belongs to the technical field of liquid chromatogram stationary phase filler, and particularly relates to a monodisperse core-shell microsphere with a mesoporous silica shell and a preparation method thereof. The method comprises the following steps: preparing micron-sized silane microspheres with uniform size efficiently by a one-pot method; then preparing a controllable mesoporous silicon dioxide shell layer by taking the nonporous silane microspheres as cores to obtain core-shell microspheres; and then removing the template agent in the pore channel to obtain the monodisperse core-shell microsphere with the mesoporous silica shell layer. The particle size of the mesoporous core-shell microsphere prepared by the method is 0.22-10.6 um, the mesoporous aperture of the mesoporous silica core-shell microsphere is 2-40 nm, the thickness of the mesoporous shell layer is 20-600 nm, the specific surface area of the microsphere can be effectively increased through an open pore channel perpendicular to the surface of the core, and the mesoporous silica core-shell microsphere has an excellent application prospect in the fields of chromatographic packing, molecular adsorption and reaction catalysis.
Description
Technical Field
The invention belongs to the technical field of liquid chromatogram stationary phase filler, and particularly relates to a microsphere with a mesoporous silica shell and a preparation method thereof.
Background
Silane and silicon dioxide microspheres are nontoxic, high in mechanical strength, good in thermal stability, solvent-resistant and easy to modify, and since the last century, the preparation technology of the silane and silicon dioxide microspheres is concerned and researched by people greatly, and gradually becomes a key requirement in the fields of mixture separation, medicine and catalyst carriers, photoelectric display, environmental detection, measurement standards and the like, so that the silane and silicon dioxide microspheres are a microsphere material which is rapid in development and has a considerable prospect.
The technological and social progress puts higher and higher requirements on the high-efficiency and rapid analysis of complex mixtures, and the liquid chromatography packing is used as the core part of a liquid chromatography column and plays a decisive role in improving the application range and the separation precision of the chromatography column. Silica microspheres are used as an important chromatographic column stationary phase, and various ultrahigh pressure liquid chromatography technologies based on microsphere packing of about 2 um have been developed in recent years, so that the progress of the chromatography technology is greatly promoted. Although the particle size is reduced, the action area of the filler and the substance to be separated can be increased, and the separation efficiency of the chromatogram can be improved. However, the column pressure is easily and rapidly increased by simply reducing the particle size, and a large amount of heat generated by the mobile phase also widens the spectrum peak, thereby increasing the energy and equipment cost and influencing the analysis speed and quality. The silica microspheres with the core-shell structure can reduce back pressure through the size control of the core; the effective specific surface area of interaction is increased through the porous shell layer, and the column efficiency is improved; compared with the full-porous microsphere filler, the porous microsphere filler reduces the diffusion path of an analyte, and is beneficial to narrowing a chromatographic peak; it also has more stable mechanical strength and durability compared to fully porous microspheres or hollow microspheres. Therefore, the development of porous silica microsphere fillers is a reasonable approach to address the above problems.
In the preparation of the core-shell microspheres, a baby has earlier proposed in 1968 that silica microspheres are prepared by hydrolytic polycondensation of tetraethyl orthosilicate in an alkaline environment. The method has the advantages of mild conditions, simple and convenient operation equipment, low cost and the like, and gradually becomes a mature route for preparing the silicon dioxide microspheres after certain optimization and improvement. However, the size of the silica microspheres prepared by the baby process is generally in the submicron level, the controllable range is relatively narrow, the silica microspheres are greatly influenced by the polymerization environment, and the repeatability is unstable. The solid silicon spheres with larger sizes reported in the literature can only be obtained by repeated multi-step seed growth, or slow dripping of monomer raw materials, or by introducing strong electrolyte in a reaction system for assistance. The method has the inevitable defects of poor monodispersity of the microspheres, low utilization efficiency after screening, complex and time-consuming steps, difficulty in mass preparation and the like. Therefore, the research on a general method for efficiently and simply preparing the monodisperse silicon-based microspheres is of great significance.
In the preparation of the porous shell layer of the microsphere, the current technology is mainly based on various template methods. In the preparation method disclosed in 5.2011 of chinese patent application 201010567428.6, a porous polymer is used as a template, and the polymer needs to be functionalized with amino modification and then coated with a silica shell layer, although the yield can be significantly improved, the number of steps is large, the control process is not simple, and a hollow region is formed after a polymer core is removed by high-temperature burning, which may cause the reduction of the mechanical strength and durability of the microsphere and the non-uniformity of the pore size distribution.
In the preparation method disclosed in 2017, 1 month, chinese patent application 201610655630.1 discloses that a core-shell microsphere with a radioactive mesoporous structure can be obtained by using two quaternary ammonium salt surfactants with different carbon chain lengths as template agents, and has a good separation capability for small molecules, but the method has a narrow adjustable range of pore diameter, cannot effectively separate substances with high molecular weight and large hydrodynamic volume, and simultaneously the thickness of a mesoporous shell layer and the corresponding specific surface area thereof are not easy to control, and the collapse of pore channels and the damage of morphology can be caused by high-temperature burning, which greatly limits the application range thereof.
Aiming at the defects, the invention develops a general method for preparing monodisperse silane microspheres, in particular micron-sized monodisperse solid silane microspheres, by a one-pot method, which is efficient, simple and convenient and has good repeatability, by adopting an organosilane monomer without template molecules or seed microspheres; furthermore, the prepared silane microspheres are used as cores, and based on a surfactant template method, wide-range adjustment of the pore diameter and the shell thickness of open mesoporous pore channels is realized by selectively adding an organic solvent and gradually growing, so that the purpose of effectively controlling the surface morphology and the specific surface area is achieved, and a good material basis is provided for the application of the silane microspheres in the directions of high performance liquid chromatography column packing and adsorption carriers.
Disclosure of Invention
The invention aims to provide a monodisperse core-shell mesoporous microsphere which is efficient, simple and convenient, uniform in product particle size and controllable in morphology and a preparation method thereof.
The invention prepares the non-porous silane microspheres by using organosilane as a precursor through a sol-gel method; then preparing a controllable mesoporous silicon dioxide shell layer by taking the nonporous silane microspheres as cores to obtain core-shell microspheres; and then removing the template agent in the pore channel to obtain the monodisperse core-shell microsphere with the mesoporous silica shell layer.
The invention solves the problems of low efficiency, undersize product grain diameter or uneven size of the preparation method of the silicon dioxide solid microsphere core in the prior art, and further overcomes the defect of the shape regulation range of the mesoporous shell layer of the core-shell silicon dioxide microsphere. The invention can effectively control the structure of the vertical mesoporous pore canal of the shell layer of the microsphere, including the pore diameter, the pore thickness and the corresponding specific surface area, while ensuring the good size monodispersity and good sphericity of the silane microspheres.
The invention provides a preparation method of monodisperse core-shell microspheres with mesoporous silica shells, which comprises the following steps:
(1) preparing micron-sized silane microspheres with uniform size by a one-pot method: preparing nonporous silane microspheres with determined composition and particle size by using water as a solvent and organosilane as a precursor through a sol-gel method under an alkaline condition;
(2) taking nonporous silane microspheres as a core, dispersing the nonporous silane microspheres in an alkaline aqueous solution containing a cationic surfactant, and then adding an organic oil phase and a silicon dioxide precursor to prepare a controllable mesoporous silicon dioxide shell layer to obtain core-shell microspheres;
(3) and removing the template agent in the pore channel by post-treatment modes such as heating and calcining, solvent reflux or ion exchange and the like to obtain the monodisperse core-shell microsphere with the mesoporous silica shell layer.
Furthermore, the invention can modify specific functional groups on the surface of the prepared core-shell microsphere to obtain the core-shell functional microsphere with the mesoporous silica shell layer for specific application.
Preferably, in step (1), the organosilane used is selected from tetraalkoxysilanes ((R)1O)4Si), trialkoxysilane ((R)1O)3-Si-R2) Wherein R is1Selected from methyl, ethyl, propyl or isopropyl, R2Is selected from vinyl, gamma-aminopropyl, N- (beta-aminoethyl) -gamma-aminopropyl, gamma-glycidoxypropyl, gamma-methacryloxypropyl, gamma-mercaptopropyl, vinyl and phenyl.
Preferably, in the step (1), the particle size of the non-porous silane microsphere core is in the range of 0.2 um to 10 um.
Preferably, in step (2), the non-porous silane microspheres are prepared according to the method in step (1). It may also be any silica microsphere prepared commercially or by other means.
Preferably, in step (2), the cationic surfactant used is cetyltrimethylammonium bromide.
Preferably, in steps (1) and (2), ammonia, urea or triethanolamine is used to adjust the desired alkalinity.
Preferably, in the step (2), the organic oil phase used is one or more of propanol or its isomer, butanol or its isomer, n-hexane, cyclohexane, benzene, toluene or mesitylene.
Preferably, in the step (2), the silica precursor used is tetraalkoxysilane (R)1O)4Si, wherein R1Is methyl, ethyl, propyl or isopropyl. Tetraethoxysilane is more preferred.
Preferably, in the step (3), the mesoporous aperture of the mesoporous silica shell is within the range of 2 nm to 40 nm, and the thickness of the mesoporous shell is within the range of 20 nm to 600 nm.
Preferably, in the step (3), the heating and calcining temperature is 500-600 ℃; refluxing the solvent by selecting acidic ethanol or acetone as the solvent; the ion exchange adopts a certain concentration of ammonium chloride ethanol solution.
The particle size of the monodisperse core-shell microsphere prepared by the invention is within the range of 0.22 um to 10.6 um; the aperture of the mesoporous silica shell is within 2 nm-40 nm, and the thickness of the mesoporous shell is within 20 nm-600 nm. The open pore canal vertical to the surface of the core can effectively increase the specific surface area of the microsphere, and has excellent application prospect in the fields of chromatographic packing, molecular adsorption and reaction catalysis.
The invention has the beneficial effects that:
1. the invention provides a method for preparing monodisperse non-porous silane microspheres, in particular to micron-sized monodisperse solid silane microspheres, which can be used for preparing the monodisperse non-porous silane microspheres efficiently, simply and conveniently and has good repeatability by designing and adopting different silane monomers and mixtures thereof. The method is based on a sol-gel method, silane can be automatically hydrolyzed and dissolved in water at the initial stage, the system is simple, ethanol or other organic solvents are not needed, and the method is environment-friendly; the polycondensation reaction of silanol is initiated by a proper amount of alkali, the single nucleation process is ensured, the size of the final sphere is uniform, the final sphere is positively correlated with the initial silane monomer content and inversely correlated with the initiating alkali concentration or pH, the control means is simple and clear, and the universality is strong; the matched tetraalkoxysilane can be copolymerized and inserted into the framework or covered on the surface of the initial spherical core, and plays the roles of reducing the surface energy, providing necessary hydrophilicity and facilitating the silicon hydroxyl of subsequent reaction, thereby obviously preventing the agglomeration of the microspheres; the method does not need any template molecules or seed microspheres, has high preparation efficiency and high utilization rate of raw materials, is easy to amplify and control, and can collect and use products without screening or surface functionalization treatment. The particle size of the non-porous silane microsphere synthesized by the method is within the range of 0.2-10 um, and the non-porous silane microsphere can be used in a plurality of fields such as stationary phase fillers, medicaments, catalyst carriers, measurement standards and the like;
2. the invention further improves the prior surfactant template method, realizes the wide-range adjustment of the aperture and the shell thickness of the open mesoporous, and thus achieves the purpose of effectively controlling the surface appearance and the specific surface area of the microsphere. In the existing scheme, a cationic surfactant can form micelles in a solution, the micelles can perform electrostatic interaction with surfaces of silica precursor oligomers with negative charges and silane microsphere cores in the solution, and the silica oligomers tend to deposit and polymerize on the surfaces of the microsphere cores under the drive of energy reduced by free energy to form open mesoporous channels vertical to the surfaces of the microsphere cores. According to the scheme, based on the characteristic that the pore diameter of the mesopores is determined by the size of the oil-in-water micelle, organic solvents with different properties are selectively and cooperatively added to change the structure of the micelle, so that the pore diameter can be adjusted and controlled between 2 nm and 40 nm, and the requirements of chromatographic separation analysis on molecules with various sizes are met. Because the compound formed by the micelle template agent and the silicon dioxide precursor oligomer is gradually coated and grown on the spherical core, the shell layer can be subjected to multiple rounds of growth and assembly by an intermittent feeding mode, and the thickness of the mesoporous shell layer is adjusted within the range of 20 nm-600 nm, namely the corresponding specific surface area of the material is adjusted;
3. the invention also provides a multiple optional post-processing template removal mode. The traditional heating and calcining method is short in time consumption and thorough in impurity removal, but can cause channel collapse to a certain degree, reduce the specific surface area and lose silicon hydroxyl which can be modified on the surface; the solvent reflux and ion exchange method is mild and stable, can well maintain the shape of the mesoporous silica microspheres, but has long time consumption and needs repeated operation. The operator can select a suitable method according to the requirement.
Drawings
FIG. 1 is a scanning electron microscope image of monodisperse silane solid microspheres prepared by the invention.
FIG. 2 is a scanning electron microscope image of the micron-sized microsphere with a mesoporous silica shell layer prepared by the present invention.
FIG. 3 is a transmission electron microscope image of the micron-sized microsphere with a mesoporous silica shell layer prepared by the present invention.
FIG. 4 is a nitrogen adsorption and desorption isotherm of the micron-sized microsphere with a mesoporous silica shell prepared by the present invention.
FIG. 5 shows the BJH adsorption pore size distribution of the micron-sized microsphere with a mesoporous silica shell layer prepared by the invention.
Detailed Description
The above-described scheme is further illustrated below with reference to specific examples. It should be understood that these examples are for illustrative purposes and are not intended to limit the scope of the present invention. The experimental conditions used in the examples can be further adjusted according to actual conditions, and the conditions in the conventional experiments (deionized water, room temperature, etc.) are not generally indicated. Specific implementation processes of the present invention are described below through various embodiments, wherein embodiments 1 to 4 are preparation processes of monodisperse silica solid microspheres, and embodiments 5 to 8 are synthesis processes of mesoporous silica shells.
EXAMPLE 1 Synthesis of monodisperse solid silane microspheres
50 ml of water and 8 ml of Vinyltriethoxysilane (VTES) are added into a 150 ml three-neck flask, and the stirring speed is controlled to be 200-300 rpm, so that a homogeneous prehydrolysis liquid is formed. Preparing 5 ml of fresh dilute ammonia water with the mass fraction of 5-6%, adding 50 ul of the dilute ammonia water into the solution, reacting for 9 min, adding 1.5 ml of Tetraethoxysilane (TEOS) into the system, simultaneously replenishing the residual dilute ammonia water into the reaction system at the speed of 0.1 ml/min, and continuing to react for 2-12 h after the dropwise addition is finished. After the reaction is finished, the mixture is separated by centrifugation at 3000 rpm for 3 min, repeatedly washed to be neutral by distilled water and then washed by absolute ethyl alcohol for 3 times. Drying for 6 h at 40 ℃ in a vacuum drying oven to obtain the monodisperse solid silane microsphere powder with the particle size of 3 um under an electron microscope.
EXAMPLE 2 Synthesis of monodisperse solid silane microspheres
200 ml of water and 28 ml of Vinyltriethoxysilane (VTES) are added into a 500 ml three-neck flask, and the stirring speed is controlled to be 200-300 rpm, so that a homogeneous prehydrolysis liquid is formed. Preparing 5 ml of fresh 5-6 mass percent dilute ammonia water, adding 260 ul of the dilute ammonia water into the solution, reacting for 8 min, adding 6 ml of Tetraethoxysilane (TEOS) into the system, simultaneously replenishing the residual dilute ammonia water into the reaction system at the speed of 0.2 ml/min, and continuing to react for 2-12 h after the dropwise addition is finished. After the reaction is finished, the mixture is separated by centrifugation at 3000 rpm for 3 min, repeatedly washed to be neutral by distilled water and then washed by absolute ethyl alcohol for 3 times. Drying for 6 h at 40 ℃ in a vacuum drying oven to obtain the monodisperse solid silane microsphere powder with the particle size of 2 um under an electron microscope.
EXAMPLE 3 Synthesis of monodisperse solid silane microspheres
50 ml of water and 10 ml of Vinyltriethoxysilane (VTES) are added into a 150 ml three-neck flask, and the stirring speed is controlled to be 200-300 rpm, so that a homogeneous prehydrolysis liquid is formed. Preparing 5 ml of fresh dilute ammonia water with the mass fraction of 5-6%, adding 30 ul of the dilute ammonia water into the solution, reacting for 7 min, adding 1.3 ml of Tetraethoxysilane (TEOS) into the system, simultaneously supplementing the remaining dilute ammonia water into the reaction system at the speed of 0.1 ml/min, and continuing to react for 2-12 h after the dropwise addition is finished. After the reaction is finished, the mixture is separated by centrifugation at 3000 rpm for 3 min, repeatedly washed to be neutral by distilled water and then washed by absolute ethyl alcohol for 3 times. Drying for 6 h at 40 ℃ in a vacuum drying oven to obtain the monodisperse solid silane microsphere powder with the particle size of 5 um under an electron microscope.
EXAMPLE 4 Synthesis of monodisperse solid silane microspheres
50 ml of water and 1 ml of Vinyltriethoxysilane (VTES) are added into a 150 ml three-neck flask, and the stirring speed is controlled to be 200-300 rpm, so that a homogeneous prehydrolysis liquid is formed. Adding 1 ml of freshly prepared dilute ammonia water with the mass fraction of 5-6% into the solution, reacting for 7 min, adding 0.5 ml of Tetraethoxysilane (TEOS) into the system, simultaneously adding the remaining dilute ammonia water into the reaction system at the speed of 0.1 ml/min, and continuing to react for 2-12 h after the dropwise addition is finished. After the reaction is finished, the mixture is separated by centrifuging at 9000 rpm for 3 min, repeatedly washed to neutrality by distilled water and then washed by absolute ethyl alcohol for 3 times. Drying for 6 h at 40 ℃ in a vacuum drying oven to obtain the monodisperse solid silane microsphere powder with the particle size of 0.2 um under an electron microscope.
Example 5 mesoporous silica Shell coating
100 mg of silane microsphere powder with the particle size of 3 um (example 1) is dispersed in 30 ml of 5-50 g/L Cetyl Trimethyl Ammonium Bromide (CTAB) solution, 360 ul of 25% Triethanolamine (TEA) aqueous solution is added in, and after uniform dispersion is carried out through ultrasound, 16 ml of cyclohexane is added. The flask was transferred to an oil bath at 60 ℃, the appropriate stirring speed was adjusted, after 1 h of stable temperature, 0.3 ml of TEOS was slowly added dropwise and the reaction was continued for 12 h. After the reaction is finished, the obtained product is repeatedly washed by deionized water and ethanol, dried for 6 hours at the temperature of 60 ℃, and transferred into a muffle furnace to be burnt for 4 hours at the temperature of 550 ℃ under the air atmosphere. The average pore diameter of the obtained mesoporous microsphere is 5.5 nm, the thickness of a mesoporous shell layer is about 100 nm, and the BET specific surface area is 121.3 m2/g。
Example 6 mesoporous silica Shell coating
6 g of silane microsphere powder with the particle size of 2 um (example 2) is taken and dispersed in 200 ml of Cetyl Trimethyl Ammonium Bromide (CTAB) solution with the concentration of 25-50 g/L, 12 ml of Triethanolamine (TEA) aqueous solution with the mass fraction of 50% is added, and after the triethanolamine aqueous solution is uniformly dispersed by ultrasound, 120 ml of toluene is added. The flask was transferred to an oil bath at 60 ℃, the appropriate stirring speed was adjusted, after 1 h of stable temperature, 8 ml of TEOS was slowly added dropwise, and the reaction was continued for 72 h. After the reaction is finished, the obtained product is repeatedly washed by deionized water and ethanol, and the washing temperature is 60 DEGDrying at the temperature of 6 ℃ for 6 h, transferring into a muffle furnace, and burning at 550 ℃ for 4 h in an air atmosphere. The average pore diameter of the obtained mesoporous microsphere is 6.0 nm, the thickness of a mesoporous shell layer is about 110 nm, and the BET specific surface area is 142.8 m2/g。
Example 7 mesoporous silica Shell coating
3 g of silane microsphere powder with the particle size of 2 um (example 2) is taken and dispersed in 200 ml of Cetyl Trimethyl Ammonium Bromide (CTAB) solution with the concentration of 25-50 g/L, 12 ml of Triethanolamine (TEA) aqueous solution with the mass fraction of 50% is added, and after the triethanolamine aqueous solution is uniformly dispersed by ultrasound, 120 ml of toluene is added. Transferring the flask to an oil bath at 60 ℃, adjusting a proper stirring speed, stabilizing the temperature for 1 h, slowly dropwise adding 1.3 ml of TEOS, supplementing 3 ml of TEOS after reacting for 12 h, supplementing 3 ml of TEOS after continuing to react for 12 h, and repeating the supplementing process for 6 times. After the reaction is finished, the obtained product is repeatedly washed by deionized water and ethanol, dried at 60 ℃ for 6 hours, and refluxed in acidic ethanol (hydrochloric acid: ethanol =1: 1) or 0.6% by mass of ammonium chloride ethanol solution for 2-3 times to remove the template. The average pore diameter of the obtained mesoporous microsphere is 10.0 nm, the thickness of a mesoporous shell layer is about 380 nm, and the BET specific surface area is 636.9 m2/g。
EXAMPLE 8 mesoporous silica Shell coating
3 g of silane microsphere powder with the particle size of 2 um (example 2) is taken and dispersed in 200 ml of Cetyl Trimethyl Ammonium Bromide (CTAB) solution with the concentration of 25-50 g/L, 12 ml of Triethanolamine (TEA) aqueous solution with the mass fraction of 50% is added, and after the triethanolamine aqueous solution is uniformly dispersed by ultrasound, 12 ml of isopropanol is added. After the flask was transferred to a 60 ℃ oil bath, 120 ml of toluene was added, an appropriate stirring speed was adjusted, and after the temperature was stabilized for 1 hour, 5 ml of TEOS was slowly dropped, and the reaction was continued for 72 hours. After the reaction is finished, the obtained product is repeatedly cleaned by deionized water and ethanol, dried for 6 h at 60 ℃, transferred into a muffle furnace for firing for 4 h at 550 ℃, the average pore diameter of the mesoporous microsphere is 22.3 nm, the thickness of the mesoporous shell layer is about 105 nm, and the BET specific surface area is 83.9 m2/g。
Example 9 surface alkylation modification of mesoporous silica Shell
Refluxing 3 g of functional microspheres with mesoporous silica shells for 3 h by using acidic ethanol, recovering surface silicon hydroxyl, repeatedly washing, centrifuging and drying. 3 g of the silica microspheres are uniformly dispersed in 40 ml of toluene, added into 60 ml of toluene in which 6 ml of octadecyltrichlorosilane is dissolved, introduced with nitrogen for 30 min, and stirred and refluxed for 12 h at 110 ℃. After the reaction is finished, products are collected by suction filtration and washed by anhydrous toluene, acetone and methanol in sequence, and then dried in an oven at 60 ℃ to obtain the functional microspheres modified by C18.
It should be noted that the above-mentioned examples are only for illustrating the technical concepts and features of the present invention, and the purpose of the present invention is to enable those skilled in the art to understand the content of the present invention and to implement the present invention, and not to limit the protection scope of the present invention. All equivalent changes or modifications made according to the spirit of the present invention should be covered within the protection scope of the present invention.
Claims (4)
1. A preparation method of monodisperse core-shell microspheres with mesoporous silica shells is characterized by comprising the following specific steps:
(1) preparing micron-sized silane microspheres with uniform size by a one-pot method: preparing nonporous silane microspheres with determined composition and particle size by using water as a solvent and organosilane as a precursor through a sol-gel method under an alkaline condition; the process is as follows: first, trialkoxysilane (R)1O)3-Si-R2Dissolving in water, stirring to form homogeneous prehydrolysis liquid; preparing dilute ammonia water with the mass fraction of 5-6%, adding the dilute ammonia water into the solution, and reacting; then adding tetraalkoxysilane (R) to the above system1O)4Si, simultaneously dripping diluted ammonia water with the same mass fraction into the reaction system, and continuing the reaction; after the reaction is finished, performing centrifugal separation, repeatedly washing the mixture to be neutral by using distilled water, and drying the mixture in a vacuum drying oven to obtain monodisperse solid silane microsphere powder;
(2) taking nonporous silane microspheres as a core, dispersing the nonporous silane microspheres in an alkaline aqueous solution containing a cationic surfactant, and then adding an organic oil phase and a silicon dioxide precursor to prepare a controllable mesoporous silicon dioxide shell layer to obtain core-shell microspheres;
(3) removing the template agent in the pore channel by post-treatment modes such as heating and calcining, solvent refluxing or ion exchange and the like to obtain the monodisperse core-shell microsphere with the mesoporous silica shell layer;
modifying a specific functional group on the surface of the monodisperse core-shell microsphere with the mesoporous silica shell layer to obtain the monodisperse core-shell functional microsphere with the mesoporous silica shell layer;
tetraalkoxysilane (R) used in step (1)1O)4Si, trialkoxysilane (R)1O)3-Si-R2Wherein R is1Selected from methyl, ethyl, propyl or isopropyl, R2Is selected from vinyl, gamma-aminopropyl, N- (beta-aminoethyl) -gamma-aminopropyl, gamma-glycidoxypropyl, gamma-methacryloxypropyl, gamma-mercaptopropyl, vinyl, phenyl;
the particle size of the non-porous silane microspheres in the step (1) is within the range of 0.2 um-10 um;
the silicon dioxide precursor used in the step (2) is tetraalkoxysilane (R)1O)4Si, wherein R1Is methyl, ethyl, propyl or isopropyl;
the mesoporous aperture of the mesoporous silica shell layer in the step (3) is 2 nm-40 nm; the thickness of the mesoporous shell of the mesoporous silica shell is 20 nm-600 nm.
2. The method according to claim 1, wherein the cationic surfactant used in step (2) is cetyltrimethylammonium bromide or cetyltrimethylammonium chloride.
3. The preparation method according to claim 2, wherein the organic oil phase added in step (2) is one or more of methanol, ethanol, propanol, butanol, pentanol, n-hexane, cyclohexane, benzene, toluene and mesitylene.
4. A monodisperse core-shell microsphere having a mesoporous silica shell layer obtained by the preparation method according to any one of claims 1 to 3, wherein the particle size of the non-porous silane microsphere as a core is 0.2 to 10 um; the thickness of the mesoporous silica shell is 20 nm-600 nm, and the aperture of the mesoporous silica shell is 2 nm-40 nm.
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