Mesoporous silica microspheres, preparation method and application thereof

Abstract

The present invention belongs to the field of chromatography filling technology, and specifically relates to a kind of mesoporous silica microspheres, preparation method and application. The present invention utilizes tetraethylenepentamine functionalized modified template microspheres to generate electrostatic anchoring with oligosiloxane anions generated by hydrolysis of silicon source, thereby inhibiting silicon source nucleation; by covering the surface of the template microspheres in a lying configuration, the steric hindrance is reduced, the diffusion of silicon precursors in the silicon source solution is promoted, and the yield of mesoporous silica microspheres is increased; by grafting octadecyltrichlorosilane silanol groups to modify the surface of the mesoporous silica, a highly cross-linked Si-O-Si skeleton is formed, thereby improving the mechanical strength of the microspheres, reducing column efficiency loss, and improving the comprehensive yield and performance of high performance liquid chromatography.

Description

Technical Field

[0001] The invention belongs to the technical field of chromatographic filling, and particularly relates to mesoporous silica microspheres, a preparation method and applications thereof. Background Art

[0002] High-performance liquid chromatography (HPLC) is widely used in biology, chemical engineering, pharmaceuticals, food analysis, environmental protection, and other fields, serving as a crucial tool for separating and analyzing complex samples. Chromatographic fillers, at the core of HPLC, are a crucial component of chromatographic research. Currently, mesoporous silica microspheres are the most widely used chromatographic fillers, offering advantages such as large specific surface area, low dielectric constant, low expansion coefficient, strong adsorption, chemical stability, excellent thermal and shock resistance, and easy dispersion.

[0003] Currently, the main preparation methods for mesoporous silica microspheres include the sol-gel method, the microemulsion method, the spray-drying method, and the polymerization-induced colloidal aggregation method. The sol-gel method is to add a surfactant to the solution and then remove the template by calcination or solution extraction to obtain porous silica microspheres; the silica microspheres obtained by the microemulsion method have a wide particle size distribution and must undergo strict particle size screening; the polymerization-induced colloidal aggregation method cannot be maturely applied on a large scale due to the limitations of conditions such as silica sol; the silica particles produced by the spray-drying method have poor sphericity, a wide particle size distribution, and poor mechanical strength, which basically cannot meet the requirements of high-performance liquid chromatography fillers. The existing technology is very difficult to prepare mesoporous silica spheres with uniform particle size and good dispersibility, which usually results in high cost and low column efficiency. Summary of the Invention

[0004] The purpose of the present invention is to provide a mesoporous silica microsphere, a preparation method and application thereof, so as to solve the above technical problems.

[0005] In order to achieve the above technical objectives, the technical solution of the present invention is:

[0006] A method for preparing mesoporous silica microspheres comprises the following steps:

[0007] S1, the silica sol aqueous phase W1 and the oil phase O were mixed at a mass ratio of 1:1 and homogenized at high speed to form a W1 / O primary emulsion; then, the W1 / O primary emulsion was injected into the external aqueous phase W2 at a mass ratio of (W1 / O):W2 = 1:5, and homogenized at 200 rpm and 20°C for 3 h to form a W1 / O / W2 double emulsion;

[0008] S2. Pulse-add 0.05-0.1 wt% tetraethoxysilane solution and 0.02-0.08 wt% hexadecyltrimethylammonium bromide solution to the W1 / O / W2 double emulsion in a mass ratio of 1:1-2, ultrasonically disperse at 300 W for 20 min, and react at 40° C. for 6 h to obtain a silicon source solution;

[0009] S3. Under a nitrogen atmosphere, add a silicon source solution dropwise to the modified poly(glycidyl methacrylate-co-ethylene glycol dimethylate) microsphere solution at a dropwise rate of 0.2 mL / min, adjust the pH to 5.5-6.5, react with stirring at 30°C for 2-4 hours, and vacuum infiltrate for 30-60 minutes; the obtained microspheres are calcined and dried in sections to obtain initial mesoporous silica microspheres; wherein the mass ratio of the modified poly(glycidyl methacrylate-co-ethylene glycol dimethylate) microsphere solution to the silicon source solution is 2:1-3;

[0010] S4. Initial mesoporous silica microspheres were immersed in a 30 wt% hydrochloric acid solution at 120°C at a mass ratio of 1:25 for 6 h. After washing and drying, the microspheres were dispersed in toluene. Octadecyltrichlorosilane was added and the solution was refluxed at 125°C for 24 h. The resulting product was washed with toluene and ethanol in turn and dried to obtain mesoporous silica microspheres. The mass ratio of octadecyltrichlorosilane to initial mesoporous silica microspheres was 1:1.

[0011] As a further improvement, in step S1, the silica sol aqueous phase W1 is prepared by dissolving a silane coupling agent and sodium carboxymethyl cellulose in deionized water and ultrasonically dispersing the mixture at 600 W for 30 minutes; wherein the mass fractions of the silane coupling agent and sodium carboxymethyl cellulose after being dissolved in deionized water are 1.5-2.0 wt% and 0.1-0.5 wt%, respectively, and the viscosity of the silica sol aqueous phase is 500-800 mPa·s at room temperature.

[0012] As a further improvement, in step S1, the preparation method of the oil phase O is: dissolving polyglycerol ricinoleate in cyclohexane / liquid paraffin at a solid-liquid ratio of 1:30, and the volume ratio of cyclohexane to liquid paraffin is 3:1; the preparation method of the external aqueous phase W2 is: mixing 2wt% polyvinyl alcohol solution and 0.4wt% sodium lauryl sulfate solution at a volume ratio of 1:1, and stirring at 300rpm for 12min.

[0013] As a further improvement, in step S2, the tetraethoxysilane solution and the hexadecyltrimethylammonium bromide solution are added dropwise in a pulsed manner: the tetraethoxysilane solution and the hexadecyltrimethylammonium bromide solution are added alternately every 10 minutes, and the total number of additions is 6 to 10 times.

[0014] As a further improvement, in step S3, the preparation method of the modified poly(glycidyl methacrylate)-co-ethylene glycol dimethacrylate) microsphere solution is as follows: dispersing poly(glycidyl methacrylate)-co-ethylene glycol dimethacrylate) microspheres in deionized water, adding tetraethylene pentamine after ultrasonic treatment, reacting at 80° C. for 12 hours, washing and drying after the reaction; mixing the microspheres obtained after drying with isopropanol and deionized water, and ultrasonically treating at 600W for 15 minutes to obtain a modified poly(glycidyl methacrylate)-co-ethylene glycol dimethacrylate) microsphere solution; wherein the mass ratio of poly(glycidyl methacrylate)-co-ethylene glycol dimethacrylate microspheres to tetraethylene pentamine is 1:2~4; and the mass ratio of the microspheres obtained after drying to isopropanol and deionized water is 1:20:4.

[0015] As a further improvement, the preparation method of the polymethacrylate co-ethylene glycol dimethacrylate microspheres is as follows: dissolving glycidyl methacrylate, ethylene dimethacrylate, and cyclohexanol in deionized water, mixing uniformly and emulsifying for 30 minutes to obtain an emulsified mixture; adding the emulsified mixture to a styrene seed suspension, reacting in a 70°C water bath for 24 hours, washing the obtained microspheres with water, removing cyclohexanol through toluene extraction, and drying at 50°C for 6 hours to obtain polymethacrylate co-ethylene glycol dimethacrylate microspheres; wherein the mass ratio of glycidyl methacrylate, ethylene dimethacrylate, and cyclohexanol is 1:1~3:2.

[0016] As a further improvement, the preparation method of the styrene seed suspension is as follows: under a nitrogen atmosphere, polymerized styrene is dispersed in an anhydrous ethanol medium, dicyclohexylcarbodiimide and polyvinyl pyrrolidone are added, the mixture is evenly mixed and then ultrasonically treated, and then stirred at 70°C and 120r / min for 24 hours, centrifuged and washed, and dried to obtain styrene seeds; the styrene seeds are dispersed in deionized water, benzoyl peroxide and polyvinyl alcohol are added, ultrasonically dispersed, and stirred in a water bath at 30°C for 30 minutes to obtain a styrene seed suspension; wherein the added amounts of dicyclohexylcarbodiimide and polyvinyl pyrrolidone are 5wt% and 1wt% of the polymerized styrene, respectively; and the mass ratio of styrene seeds, benzoyl peroxide and polyvinyl alcohol is 1:0.2~0.5:3.

[0017] The present invention also provides mesoporous silica microspheres.

[0018] The present invention also provides an application of mesoporous silica microspheres in high performance liquid chromatography. The mesoporous silica microspheres are dispersed in a toluene solution at a solid-liquid ratio of 1:20, and loaded into a stainless steel column in the form of a suspension at 40 MPa for high performance liquid chromatography.

[0019] Due to the adoption of the above technical solution, the present invention has the following beneficial effects:

[0020] 1. After functional modification with tetraethylenepentamine, protonated amino groups are formed on the surface of poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) microspheres, which react with oligosiloxane anions ([Si(OH)3] - ) Through strong electrostatic interaction, the self-nucleation of silicon sources is suppressed, and the directional enrichment of silicon sources on the surface of template microspheres is achieved, which increases the density of nucleation sites, reduces the self-nucleation rate, and improves the yield and dispersibility of mesoporous silica microspheres.

[0021] 2. Tetraethylenepentamine molecules are anchored at multiple points and combined with the epoxy groups on the surface of poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) microspheres to form a lying grafting configuration, which enables the silicon precursor to be evenly embedded in the pores of the polymer template to form a three-dimensional interpenetrating network structure; reducing steric hindrance, promoting the diffusion of silicon precursors in the silicon source solution, increasing the diffusion flux of silicon precursors, and improving the generation rate of mesoporous silica.

[0022] 3. Octadecyltrichlorosilane modifies the Si-OH groups on the surface of mesoporous silica microspheres through silanol grafting to form a highly cross-linked Si-O-Si skeleton, thereby improving the mechanical strength of the mesoporous silica microspheres and reducing column efficiency loss; effectively reducing the exposure of silanol groups, reducing nonspecific adsorption with the separated and purified samples, reducing the hydrogen bonding and ion exchange between the sample and silanol groups, reducing the tailing factor, and improving the HPCL separation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Graphs showing the particle size distribution of mesoporous silica microspheres obtained in different examples; wherein curves a, b, c, d, and e are the particle size distribution curves of mesoporous silica microspheres obtained in Comparative Example 1, Comparative Example 2, Example 1, Example 2, and Example 3, respectively;

[0024] Figure 2 Figure 2 is a scanning electron microscope image of mesoporous silica microspheres; Figure a is a scanning electron microscope image of the mesoporous silica microspheres obtained in Comparative Example 1; Figure b is a scanning electron microscope image of the mesoporous silica microspheres obtained in Comparative Example 2; and Figure c is a scanning electron microscope image of the mesoporous silica microspheres obtained in Example 1. DETAILED DESCRIPTION

[0025] The technical scheme of the present invention will be clearly and completely described below in conjunction with specific embodiments, but it will be understood by those skilled in the art that the following described embodiments are part of embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work premise belong to the scope of protection of the present invention. Those who do not specify specific conditions in the embodiments are carried out according to normal conditions or the conditions recommended by the manufacturer. Those whose reagents or instruments are not specified by the manufacturer are conventional products that can be purchased commercially.

[0026] Example 1: Preparation and application of mesoporous silica microspheres, comprising the following steps:

[0027] 1. A silane coupling agent and sodium carboxymethyl cellulose were dissolved in deionized water and ultrasonically dispersed at 600W for 30 minutes to obtain a silica sol aqueous phase W1. The mass fractions of the silane coupling agent and sodium carboxymethyl cellulose after being dissolved in deionized water were 1.5wt% and 0.1wt%, respectively. The viscosity of the silica sol aqueous phase at room temperature was 500mPa·s.

[0028] 2. Dissolve polyglycerol ricinoleate in cyclohexane / liquid paraffin at a solid-liquid ratio of 1:30 and a volume ratio of cyclohexane to liquid paraffin of 3:1 to obtain oil phase O; mix the silica sol aqueous phase W1 with the oil phase O at a mass ratio of 1:1 and homogenize at 12,000 rpm for 20 minutes to form a W1 / O primary emulsion.

[0029] 3. Mix 2 wt% polyvinyl alcohol solution and 0.4 wt% sodium lauryl sulfate solution in a volume ratio of 1:1, and stir at 300 rpm for 12 min to obtain the external aqueous phase W2; inject the W1 / O primary emulsion into the external aqueous phase W2 in a mass ratio of (W1 / O):W2=1:5, and react at 200 rpm and 20°C for 3 h to form a W1 / O / W2 double emulsion.

[0030] 4. Add 0.05 wt% tetraethoxysilane solution and 0.02 wt% hexadecyltrimethylammonium bromide solution to the W1 / O / W2 double emulsion in a pulsed manner every 10 min at a mass ratio of 1:1. The total number of additions is 6 times. Ultrasonic dispersion is performed at 300 W for 20 min. The mixture is reacted at 40°C for 6 h to obtain a silicon source solution.

[0031] 5. Under a nitrogen atmosphere, disperse polymerized styrene in anhydrous ethanol medium, add dicyclohexylcarbodiimide and polyvinylpyrrolidone, stir and mix at 600 r / min for 20 min, ultrasonically disperse at 300 W for 5 min, then stir and react at 70°C and 120 r / min for 24 h. After centrifugation, wash with anhydrous ethanol and distilled water, and dry at 60°C for 2 h to obtain styrene seeds; wherein the mass ratio of polymerized styrene to anhydrous ethanol is 1:60; the added amounts of dicyclohexylcarbodiimide and polyvinylpyrrolidone are 5wt% and 1wt% of the polymerized styrene, respectively.

[0032] 6. Disperse styrene seeds in deionized water at a solid-liquid ratio of 1:60, add benzoyl peroxide and polyvinyl alcohol, and ultrasonically disperse at 300W for 5 minutes. Stir in a 30°C water bath for 30 minutes to obtain a styrene seed suspension; wherein the mass ratio of styrene seeds, benzoyl peroxide, and polyvinyl alcohol is 1:0.2:3.

[0033] 7. Dissolve glycidyl methacrylate, ethylene dimethacrylate, and cyclohexanol in deionized water, mix well, and emulsify for 30 minutes to obtain an emulsified mixture; add the emulsified mixture to a styrene seed suspension at a volume ratio of 1:2, and react in a water bath at 70°C for 24 hours. Wash the obtained microspheres with water, extract to remove cyclohexanol through toluene, and dry at 50°C for 6 hours to obtain poly glycidyl methacrylate-co-ethylene glycol dimethacrylate microspheres; wherein the mass ratio of glycidyl methacrylate, ethylene dimethacrylate, and cyclohexanol is 1:1:2.

[0034] 8. Disperse poly(glycidyl methacrylate)-co-ethylene glycol dimethacrylate) microspheres in deionized water at a mass ratio of 1:40, perform ultrasonic treatment at 600 W for 5 min, add tetraethylene pentamine, react at 80 ° C for 12 h, wash after the reaction, and dry at 60 ° C for 3 h. Mix the dried microspheres with isopropanol and deionized water, and perform ultrasonic treatment at 600 W for 15 min to obtain a modified poly(glycidyl methacrylate)-co-ethylene glycol dimethacrylate) microsphere solution; wherein the mass ratio of poly(glycidyl methacrylate)-co-ethylene glycol dimethacrylate microspheres to tetraethylene pentamine is 1:2; the mass ratio of the dried microspheres to isopropanol and deionized water is 1:20:4.

[0035] 9. Under nitrogen atmosphere, add silicon source solution to modified poly(glycidyl methacrylate-co-ethylene glycol dimethylate) microsphere solution at a drop rate of 0.2 mL / min, add 0.1 M ammonia water to adjust the pH to 5.5, stir the reaction at 30°C for 2 h, and vacuum infiltrate for 30 min; the obtained microspheres are washed with deionized water and calcined in stages: first increase the temperature to 280°C at 2°C / min, keep warm for 1 h, then increase the temperature to 500°C at 5°C / min and cure for 2 h. After calcination, the obtained microspheres are subjected to CO2 supercritical drying and dried at 10 MPa and 45°C for 3 h to obtain initial mesoporous silica microspheres; wherein, the mass ratio of modified poly(glycidyl methacrylate-co-ethylene glycol dimethylate) microsphere solution to silicon source solution is 2:1.

[0036] 10. At a mass ratio of 1:25, the initial mesoporous silica microspheres were immersed in a 30wt% hydrochloric acid solution at 120°C for 6 hours, then washed with deionized water until neutral, and then dried at 120°C for 8 hours. The obtained product was dispersed in toluene, octadecyltrichlorosilane was added, and refluxed at 125°C for 24 hours. The final product was washed with toluene and ethanol in turn, and dried at 60°C for 12 hours to obtain mesoporous silica microspheres; at a solid-liquid ratio of 1:20, the mesoporous silica microspheres were dispersed in a toluene solution, and loaded into a stainless steel column as a suspension at 40 MPa for high performance liquid chromatography; wherein the mass ratio of octadecyltrichlorosilane to the initial mesoporous silica microspheres was 1:1.

[0037] Example 2: Preparation and application of mesoporous silica microspheres, comprising the following steps:

[0038] 1. A silane coupling agent and sodium carboxymethyl cellulose were dissolved in deionized water and ultrasonically dispersed at 600W for 30 minutes to obtain a silica sol aqueous phase W1. The mass fractions of the silane coupling agent and sodium carboxymethyl cellulose after dissolving in deionized water were 1.8wt% and 0.3wt%, respectively. The viscosity of the silica sol aqueous phase at room temperature was 700mPa·s.

[0039] 2. Dissolve polyglycerol ricinoleate in cyclohexane / liquid paraffin at a solid-liquid ratio of 1:30 and a volume ratio of cyclohexane to liquid paraffin of 3:1 to obtain oil phase O; mix the silica sol aqueous phase W1 with the oil phase O at a mass ratio of 1:1 and homogenize at 12,000 rpm for 20 minutes to form a W1 / O primary emulsion.

[0040] 3. Mix 2 wt% polyvinyl alcohol solution and 0.4 wt% sodium lauryl sulfate solution in a volume ratio of 1:1, and stir at 300 rpm for 12 min to obtain the external aqueous phase W2; inject the W1 / O primary emulsion into the external aqueous phase W2 in a mass ratio of (W1 / O):W2=1:5, and react at 200 rpm and 20°C for 3 h to form a W1 / O / W2 double emulsion.

[0041] 4. Add 0.08 wt% tetraethoxysilane solution and 0.05 wt% hexadecyltrimethylammonium bromide solution to the W1 / O / W2 double emulsion in a pulsed manner every 10 min at a mass ratio of 1:1.5. The total number of additions is 8 times. Ultrasonic dispersion is performed at 300 W for 20 min. The mixture is reacted at 40°C for 6 h to obtain a silicon source solution.

[0042] 5. Under a nitrogen atmosphere, disperse polymerized styrene in anhydrous ethanol medium, add dicyclohexylcarbodiimide and polyvinylpyrrolidone, stir and mix at 600 r / min for 20 min, ultrasonically disperse at 300 W for 5 min, then stir and react at 70°C and 120 r / min for 24 h. After centrifugation, wash with anhydrous ethanol and distilled water, and dry at 60°C for 2 h to obtain styrene seeds; wherein the mass ratio of polymerized styrene to anhydrous ethanol is 1:60; the added amounts of dicyclohexylcarbodiimide and polyvinylpyrrolidone are 5wt% and 1wt% of the polymerized styrene, respectively.

[0043] 6. Disperse styrene seeds in deionized water at a solid-liquid ratio of 1:60, add benzoyl peroxide and polyvinyl alcohol, and ultrasonically disperse at 300W for 5 minutes. Stir in a 30°C water bath for 30 minutes to obtain a styrene seed suspension; wherein the mass ratio of styrene seeds, benzoyl peroxide, and polyvinyl alcohol is 1:0.2:3.

[0044] 7. Dissolve glycidyl methacrylate, ethylene dimethacrylate, and cyclohexanol in deionized water, mix well, and emulsify for 30 minutes to obtain an emulsified mixture; add the emulsified mixture to a styrene seed suspension at a volume ratio of 1:2, and react in a water bath at 70°C for 24 hours. Wash the obtained microspheres with water, extract to remove cyclohexanol through toluene, and dry at 50°C for 6 hours to obtain poly glycidyl methacrylate-co-ethylene glycol dimethacrylate microspheres; wherein the mass ratio of glycidyl methacrylate, ethylene dimethacrylate, and cyclohexanol is 1:2:2.

[0045] 8. Disperse poly(glycidyl methacrylate)-co-ethylene glycol dimethacrylate) microspheres in deionized water at a mass ratio of 1:40, perform ultrasonic treatment at 600 W for 5 min, add tetraethylene pentamine, react at 80 ° C for 12 h, wash after the reaction, and dry at 60 ° C for 3 h. Mix the dried microspheres with isopropanol and deionized water, and perform ultrasonic treatment at 600 W for 15 min to obtain a modified poly(glycidyl methacrylate)-co-ethylene glycol dimethacrylate) microsphere solution; wherein the mass ratio of poly(glycidyl methacrylate)-co-ethylene glycol dimethacrylate microspheres to tetraethylene pentamine is 1:3; the mass ratio of the dried microspheres to isopropanol and deionized water is 1:20:4.

[0046] 9. Under nitrogen atmosphere, add silicon source solution to modified poly(glycidyl methacrylate-co-ethylene glycol dimethylate) microsphere solution at a drop rate of 0.2 mL / min, add 0.1 M ammonia water to adjust the pH to 6.0, stir the reaction at 30°C for 3 h, and vacuum infiltrate for 50 min; the obtained microspheres are washed with deionized water and calcined in stages: first increase the temperature to 280°C at 2°C / min, keep warm for 1 h, then increase the temperature to 500°C at 5°C / min and cure for 2 h. After calcination, the obtained microspheres are subjected to CO2 supercritical drying and dried at 10 MPa and 45°C for 4 h to obtain initial mesoporous silica microspheres; wherein, the mass ratio of modified poly(glycidyl methacrylate-co-ethylene glycol dimethylate) microsphere solution to silicon source solution is 2:2.

[0047] 10. At a mass ratio of 1:25, the initial mesoporous silica microspheres were immersed in a 30wt% hydrochloric acid solution at 120°C for 6 hours, then washed with deionized water until neutral, and then dried at 120°C for 8 hours. The obtained product was dispersed in toluene, octadecyltrichlorosilane was added, and refluxed at 125°C for 24 hours. The final product was washed with toluene and ethanol in turn, and dried at 60°C for 12 hours to obtain mesoporous silica microspheres; at a solid-liquid ratio of 1:20, the mesoporous silica microspheres were dispersed in a toluene solution, and loaded into a stainless steel column as a suspension at 40 MPa for high performance liquid chromatography; wherein the mass ratio of octadecyltrichlorosilane to the initial mesoporous silica microspheres was 2:1.

[0048] Example 3: Preparation and application of mesoporous silica microspheres, comprising the following steps:

[0049] 1. Dissolve the silane coupling agent and sodium carboxymethyl cellulose in deionized water and perform ultrasonic dispersion at 600W for 30 minutes to obtain a silica sol aqueous phase W1. The mass fractions of the silane coupling agent and sodium carboxymethyl cellulose after dissolving in deionized water are 2.0wt% and 0.5wt%, respectively. The viscosity of the silica sol aqueous phase at room temperature is 800mPa·s.

[0050] 2. Dissolve polyglycerol ricinoleate in cyclohexane / liquid paraffin at a solid-liquid ratio of 1:30 and a volume ratio of cyclohexane to liquid paraffin of 3:1 to obtain oil phase O; mix the silica sol aqueous phase W1 with the oil phase O at a mass ratio of 1:1 and homogenize at 12,000 rpm for 20 minutes to form a W1 / O primary emulsion.

[0051] 3. Mix 2 wt% polyvinyl alcohol solution and 0.4 wt% sodium lauryl sulfate solution in a volume ratio of 1:1, and stir at 300 rpm for 12 min to obtain the external aqueous phase W2; inject the W1 / O primary emulsion into the external aqueous phase W2 in a mass ratio of (W1 / O):W2=1:5, and react at 200 rpm and 20°C for 3 h to form a W1 / O / W2 double emulsion.

[0052] 4. Add 0.05 wt% tetraethoxysilane solution and 0.02 wt% hexadecyltrimethylammonium bromide solution to the W1 / O / W2 double emulsion in a pulsed manner every 10 min at a mass ratio of 1:2. Add 10 times in total. Ultrasonic dispersion at 300 W for 20 min. React at 40 ° C for 6 h to obtain a silicon source solution.

[0053] 5. Under a nitrogen atmosphere, disperse polymerized styrene in anhydrous ethanol medium, add dicyclohexylcarbodiimide and polyvinylpyrrolidone, stir and mix at 600 r / min for 20 min, ultrasonically disperse at 300 W for 5 min, then stir and react at 70°C and 120 r / min for 24 h. After centrifugation, wash with anhydrous ethanol and distilled water, and dry at 60°C for 2 h to obtain styrene seeds; wherein the mass ratio of polymerized styrene to anhydrous ethanol is 1:60; the added amounts of dicyclohexylcarbodiimide and polyvinylpyrrolidone are 5wt% and 1wt% of the polymerized styrene, respectively.

[0054] 6. Disperse styrene seeds in deionized water at a solid-liquid ratio of 1:60, add benzoyl peroxide and polyvinyl alcohol, and disperse under 300W ultrasonic dispersion for 5 minutes. Stir in a 30°C water bath for 30 minutes to obtain a styrene seed suspension; wherein the mass ratio of styrene seeds, benzoyl peroxide, and polyvinyl alcohol is 1:0.5:3.

[0055] 7. Dissolve glycidyl methacrylate, ethylene dimethacrylate, and cyclohexanol in deionized water, mix well, and emulsify for 30 minutes to obtain an emulsified mixture; add the emulsified mixture to a styrene seed suspension at a volume ratio of 1:2, and react in a water bath at 70°C for 24 hours. Wash the obtained microspheres with water, extract to remove cyclohexanol through toluene, and dry at 50°C for 6 hours to obtain poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) microspheres; wherein the mass ratio of glycidyl methacrylate, ethylene dimethacrylate, and cyclohexanol is 1:3:2.

[0056] 8. Disperse poly(glycidyl methacrylate)-co-ethylene glycol dimethacrylate) microspheres in deionized water at a mass ratio of 1:40, perform ultrasonic treatment at 600 W for 5 min, add tetraethylene pentamine, react at 80 ° C for 12 h, wash after the reaction, and dry at 60 ° C for 3 h. Mix the dried microspheres with isopropanol and deionized water, and perform ultrasonic treatment at 600 W for 15 min to obtain a modified poly(glycidyl methacrylate)-co-ethylene glycol dimethacrylate) microsphere solution; wherein the mass ratio of poly(glycidyl methacrylate)-co-ethylene glycol dimethacrylate microspheres to tetraethylene pentamine is 1:4; the mass ratio of the dried microspheres to isopropanol and deionized water is 1:20:4.

[0057] 9. Under nitrogen atmosphere, add silicon source solution to modified poly(glycidyl methacrylate-co-ethylene glycol dimethylate) microsphere solution at a drop rate of 0.2 mL / min, add 0.1 M ammonia water to adjust the pH to 6.5, stir the reaction at 30°C for 4 h, and vacuum infiltrate for 60 min; the obtained microspheres are washed with deionized water and calcined in stages: first increase the temperature to 280°C at 2°C / min, keep warm for 1 h, then increase the temperature to 500°C at 5°C / min and cure for 2 h. After calcination, the obtained microspheres are subjected to CO2 supercritical drying and dried at 10 MPa and 45°C for 3 h to obtain initial mesoporous silica microspheres; wherein, the mass ratio of modified poly(glycidyl methacrylate-co-ethylene glycol dimethylate) microsphere solution to silicon source solution is 2:3.

[0058] 10. At a mass ratio of 1:25, the initial mesoporous silica microspheres were immersed in a 30wt% hydrochloric acid solution at 120°C for 6 hours, then washed with deionized water until neutral, and then dried at 120°C for 8 hours. The obtained product was dispersed in toluene, octadecyltrichlorosilane was added, and refluxed at 125°C for 24 hours. The final product was washed with toluene and ethanol in turn, and dried at 60°C for 12 hours to obtain mesoporous silica microspheres; at a solid-liquid ratio of 1:20, the mesoporous silica microspheres were dispersed in a toluene solution, and loaded into a stainless steel column as a suspension at 40 MPa for high performance liquid chromatography; wherein the mass ratio of octadecyltrichlorosilane to the initial mesoporous silica microspheres was 3:1.

[0059] Comparative Example 1 differs from Example 1 in that the poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) microspheres are not modified, and specifically comprises the following steps:

[0060] 1. A silane coupling agent and sodium carboxymethyl cellulose were dissolved in deionized water and ultrasonically dispersed at 600W for 30 minutes to obtain a silica sol aqueous phase W1. The mass fractions of the silane coupling agent and sodium carboxymethyl cellulose after being dissolved in deionized water were 1.5wt% and 0.1wt%, respectively. The viscosity of the silica sol aqueous phase at room temperature was 500mPa·s.

[0061] 2. Dissolve polyglycerol ricinoleate in cyclohexane / liquid paraffin at a solid-liquid ratio of 1:30 and a volume ratio of cyclohexane to liquid paraffin of 3:1 to obtain oil phase O; mix the silica sol aqueous phase W1 with the oil phase O at a mass ratio of 1:1 and homogenize at 12,000 rpm for 20 minutes to form a W1 / O primary emulsion.

[0062] 3. Mix 2 wt% polyvinyl alcohol solution and 0.4 wt% sodium lauryl sulfate solution in a volume ratio of 1:1, and stir at 300 rpm for 12 min to obtain the external aqueous phase W2; inject the W1 / O primary emulsion into the external aqueous phase W2 in a mass ratio of (W1 / O):W2=1:5, and react at 200 rpm and 20°C for 3 h to form a W1 / O / W2 double emulsion.

[0063] 4. Add 0.05 wt% tetraethoxysilane solution and 0.02 wt% hexadecyltrimethylammonium bromide solution to the W1 / O / W2 double emulsion in a pulsed manner every 10 min at a mass ratio of 1:1. The total number of additions is 6 times. Ultrasonic dispersion is performed at 300 W for 20 min. The mixture is reacted at 40°C for 6 h to obtain a silicon source solution.

[0064] 5. Under a nitrogen atmosphere, disperse polymerized styrene in anhydrous ethanol medium, add dicyclohexylcarbodiimide and polyvinylpyrrolidone, stir and mix at 600 r / min for 20 min, ultrasonically disperse at 300 W for 5 min, then stir and react at 70°C and 120 r / min for 24 h. After centrifugation, wash with anhydrous ethanol and distilled water, and dry at 60°C for 2 h to obtain styrene seeds; wherein the mass ratio of polymerized styrene to anhydrous ethanol is 1:60; the added amounts of dicyclohexylcarbodiimide and polyvinylpyrrolidone are 5wt% and 1wt% of the polymerized styrene, respectively.

[0065] 6. Disperse styrene seeds in deionized water at a solid-liquid ratio of 1:60, add benzoyl peroxide and polyvinyl alcohol, and ultrasonically disperse at 300W for 5 minutes. Stir in a 30°C water bath for 30 minutes to obtain a styrene seed suspension; wherein the mass ratio of styrene seeds, benzoyl peroxide, and polyvinyl alcohol is 1:0.2:3.

[0066] 7. Dissolve glycidyl methacrylate, ethylene dimethacrylate, and cyclohexanol in deionized water, mix well, and emulsify for 30 minutes to obtain an emulsified mixture; add the emulsified mixture to a styrene seed suspension at a volume ratio of 1:2, and react in a water bath at 70°C for 24 hours. Wash the obtained microspheres with water, extract to remove cyclohexanol through toluene, and dry at 50°C for 6 hours to obtain poly glycidyl methacrylate-co-ethylene glycol dimethacrylate microspheres; wherein the mass ratio of glycidyl methacrylate, ethylene dimethacrylate, and cyclohexanol is 1:1:2.

[0067] 8. The obtained poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) microspheres were mixed with isopropyl alcohol and deionized water in a mass ratio of 1:20:4, and ultrasonicated at 600 W for 15 min to obtain a poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) microsphere solution.

[0068] 9. Under a nitrogen atmosphere, a silicon source solution was added dropwise to a poly(glycidyl methacrylate-co-ethylene glycol dimethyl) ester microsphere solution at a drop rate of 0.2 mL / min, and 0.1 M ammonia water was added dropwise to adjust the pH to 5.5. The mixture was stirred at 30°C for 2 h and vacuum infiltrated for 30 min. The obtained microspheres were washed with deionized water and calcined in stages: first, the temperature was raised to 280°C at 2°C / min, kept warm for 1 h, and then raised to 500°C at 5°C / min for curing for 2 h. After calcination, the obtained microspheres were subjected to supercritical CO2 drying at 10 MPa and 45°C for 3 h to obtain initial mesoporous silica microspheres. The mass ratio of the poly(glycidyl methacrylate-co-ethylene glycol dimethyl) ester microsphere solution to the silicon source solution was 2:1.

[0069] 10. At a mass ratio of 1:25, the initial mesoporous silica microspheres were immersed in a 30wt% hydrochloric acid solution at 120°C for 6 hours, then washed with deionized water until neutral, and then dried at 120°C for 8 hours. The obtained product was dispersed in toluene, octadecyltrichlorosilane was added, and refluxed at 125°C for 24 hours. The final product was washed with toluene and ethanol in turn, and dried at 60°C for 12 hours to obtain mesoporous silica microspheres; at a solid-liquid ratio of 1:20, the mesoporous silica microspheres were dispersed in a toluene solution, and loaded into a stainless steel column as a suspension at 40 MPa for high performance liquid chromatography; wherein the mass ratio of octadecyltrichlorosilane to the initial mesoporous silica microspheres was 1:1.

[0070] Comparative Example 2 differs from Example 1 in that the mesoporous silica microspheres are not modified with octadecyltrichlorosilane, and specifically comprises the following steps:

[0071] 1. A silane coupling agent and sodium carboxymethyl cellulose were dissolved in deionized water and ultrasonically dispersed at 600W for 30 minutes to obtain a silica sol aqueous phase W1. The mass fractions of the silane coupling agent and sodium carboxymethyl cellulose after being dissolved in deionized water were 1.5wt% and 0.1wt%, respectively. The viscosity of the silica sol aqueous phase at room temperature was 500mPa·s.

[0072] 2. Dissolve polyglycerol ricinoleate in cyclohexane / liquid paraffin at a solid-liquid ratio of 1:30 and a volume ratio of cyclohexane to liquid paraffin of 3:1 to obtain oil phase O; mix the silica sol aqueous phase W1 with the oil phase O at a mass ratio of 1:1 and homogenize at 12,000 rpm for 20 minutes to form a W1 / O primary emulsion.

[0073] 3. Mix 2 wt% polyvinyl alcohol solution and 0.4 wt% sodium lauryl sulfate solution in a volume ratio of 1:1, and stir at 300 rpm for 12 min to obtain the external aqueous phase W2; add the external aqueous phase W2 to the W1 / O primary emulsion in a mass ratio of (W1 / O):W2=1:5, and react at 200 rpm and 20°C for 3 h to form a W1 / O / W2 double emulsion.

[0074] 4. Add 0.05 wt% tetraethoxysilane solution and 0.02 wt% hexadecyltrimethylammonium bromide solution to the W1 / O / W2 double emulsion in a pulsed manner every 10 min at a mass ratio of 1:1. The total number of additions is 6 times. Ultrasonic dispersion is performed at 300 W for 20 min. The mixture is reacted at 40°C for 6 h to obtain a silicon source solution.

[0075] 5. Under a nitrogen atmosphere, disperse polymerized styrene in anhydrous ethanol medium, add dicyclohexylcarbodiimide and polyvinylpyrrolidone, stir and mix at 600 r / min for 20 min, ultrasonically disperse at 300 W for 5 min, then stir and react at 70°C and 120 r / min for 24 h. After centrifugation, wash with anhydrous ethanol and distilled water, and dry at 60°C for 2 h to obtain styrene seeds; wherein the mass ratio of polymerized styrene to anhydrous ethanol is 1:60; the added amounts of dicyclohexylcarbodiimide and polyvinylpyrrolidone are 5wt% and 1wt% of the polymerized styrene, respectively.

[0076] 6. Disperse styrene seeds in deionized water at a solid-liquid ratio of 1:60, add benzoyl peroxide and polyvinyl alcohol, and ultrasonically disperse at 300W for 5 minutes. Stir in a 30°C water bath for 30 minutes to obtain a styrene seed suspension; wherein the mass ratio of styrene seeds, benzoyl peroxide, and polyvinyl alcohol is 1:0.2:3.

[0077] 7. Dissolve glycidyl methacrylate, ethylene dimethacrylate, and cyclohexanol in deionized water, mix well, and emulsify for 30 minutes to obtain an emulsified mixture; add the emulsified mixture to a styrene seed suspension at a volume ratio of 1:2, and react in a water bath at 70°C for 24 hours. Wash the obtained microspheres with water, extract to remove cyclohexanol through toluene, and dry at 50°C for 6 hours to obtain poly glycidyl methacrylate-co-ethylene glycol dimethacrylate microspheres; wherein the mass ratio of glycidyl methacrylate, ethylene dimethacrylate, and cyclohexanol is 1:1:2.

[0078] 8. Disperse poly(glycidyl methacrylate)-co-ethylene glycol dimethacrylate) microspheres in deionized water at a mass ratio of 1:40, perform ultrasonic treatment at 600 W for 5 min, add tetraethylene pentamine, react at 80 ° C for 12 h, wash after the reaction, and dry at 60 ° C for 3 h. Mix the dried microspheres with isopropanol and deionized water, and perform ultrasonic treatment at 600 W for 15 min to obtain a modified poly(glycidyl methacrylate)-co-ethylene glycol dimethacrylate) microsphere solution; wherein the mass ratio of poly(glycidyl methacrylate)-co-ethylene glycol dimethacrylate microspheres to tetraethylene pentamine is 1:2; the mass ratio of the dried microspheres to isopropanol and deionized water is 1:20:4.

[0079] 9. Under a nitrogen atmosphere, a silicon source solution was added dropwise to a modified poly(glycidyl methacrylate-co-ethylene glycol dimethyl) ester microsphere solution at a dropwise rate of 0.2 mL / min, and 0.1 M ammonia water was added dropwise to adjust the pH to 5.5. The mixture was stirred at 30°C for 2 h and vacuum infiltrated for 30 min. The obtained microspheres were washed with deionized water and calcined in stages: first, the temperature was raised to 280°C at 2°C / min, kept warm for 1 h, and then raised to 500°C at 5°C / min for curing for 2 h. After calcination, the obtained microspheres were subjected to supercritical CO2 drying at 10 MPa and 45°C for 3 h to obtain mesoporous silica microspheres. The mass ratio of the modified poly(glycidyl methacrylate-co-ethylene glycol dimethyl) ester microsphere solution to the silicon source solution was 2:1.

[0080] 10. Mesoporous silica microspheres were dispersed in toluene solution at a solid-liquid ratio of 1:20 and loaded into a stainless steel column as a suspension at 40 MPa for high performance liquid chromatography.

[0081] Figure 1 The particle size distribution diagrams of mesoporous silica microspheres obtained in different examples are shown in FIG. 1 , wherein curves a, b, c, d, and e are the particle size distribution curves of mesoporous silica microspheres obtained in Comparative Example 1, Comparative Example 2, Example 1, Example 2, and Example 3, respectively. Figure 1 It can be seen that compared with Comparative Example 1-2, the particle size distribution curve of Example 1-3 has a concentrated peak, a highly uniform particle size, and good dispersibility; while although the particle size distribution of the comparative example is also single-peaked, the particle size curve is dispersed, the span is large, the particle size difference is large, and the dispersibility is poor.

[0082] Figure 2 The following are scanning electron micrographs of mesoporous silica microspheres obtained in different examples, wherein Figure a is a scanning electron micrograph of the mesoporous silica microspheres obtained in Comparative Example 1; Figure b is a scanning electron micrograph of the mesoporous silica microspheres obtained in Comparative Example 2; and Figure c is a scanning electron micrograph of the mesoporous silica microspheres obtained in Example 1. The overall particle size of the mesoporous silica microspheres obtained in Comparative Examples 1-2 is relatively large and unevenly distributed, and a small portion of the silica microspheres exhibit adhesion. The mesoporous silica microspheres obtained in Example 1 are more evenly distributed and have essentially no adhesion, significantly improving their dispersibility.

[0083] The yield of mesoporous silica microspheres in different examples was determined by TG / DSC and calculated according to the mass of the calcined product / theoretical maximum mass. The calculation results are shown in Table 1:

[0084] Table 1 Mesoporous silica production rate

[0085]

[0086] The four amino side chains of tetraethylenepentamine connect to the epoxy groups on the surface of poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) microspheres through multi-point anchoring, forming a "lying" grafting structure. This increases the pore openness of the template microsphere surface, improves the diffusion flux of the silicon source, and improves the yield of mesoporous silica microspheres. In contrast, Comparative Example 1 lacks tetraethylenepentamine modification, and the yield of mesoporous silica is significantly reduced.

[0087] An HPLC accelerated aging test was performed using a 15 cm × 4.6 mm column filled with the mesoporous silica microspheres obtained in different examples. The mobile phase was acetonitrile / water = 50:50, the flow rate was 1 mL / min, and the number of injections was 200. The test results are shown in Table 2.

[0088] Table 2 HPLC accelerated aging test results

[0089]

[0090] Functionalizing the mesoporous silica microspheres with octadecyltrichlorosilane can effectively reduce the exposure of silanol groups and reduce nonspecific adsorption to the separated and purified samples. Therefore, the column efficiency loss in Examples 1-3 is significantly reduced, while the column efficiency loss in Comparative Example 2 is significantly increased due to the lack of octadecyltrichlorosilane modification.

[0091] The specific embodiments of the present invention described above do not limit the scope of protection of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the scope of protection of the claims of the present invention.

Claims

1. A method for preparing mesoporous silica microspheres, comprising the following steps: S1, the silica sol aqueous phase W1 and the oil phase O were mixed at a mass ratio of 1:1 and homogenized at high speed to form a W1 / O primary emulsion; then, the W1 / O primary emulsion was injected into the external aqueous phase W2 at a mass ratio of (W1 / O):W2 = 1:5, and homogenized at 200 rpm and 20°C for 3 h to form a W1 / O / W2 double emulsion; S2. Pulse-add 0.05-0.1 wt% tetraethoxysilane solution and 0.02-0.08 wt% hexadecyltrimethylammonium bromide solution to the W1 / O / W2 double emulsion in a mass ratio of 1:1-2, ultrasonically disperse at 300 W for 20 min, and react at 40° C. for 6 h to obtain a silicon source solution; S3. Under a nitrogen atmosphere, add a silicon source solution dropwise to the modified poly(glycidyl methacrylate-co-ethylene glycol dimethylate) microsphere solution at a dropwise acceleration rate of 0.2 mL / min, adjust the pH to 5.5-6.5, react with stirring at 30°C for 2-4 hours, and vacuum infiltrate for 30-60 minutes. The obtained microspheres are calcined and dried in sections to obtain initial mesoporous silica microspheres; wherein the mass ratio of the modified poly(glycidyl methacrylate-co-ethylene glycol dimethylate) microsphere solution to the silicon source solution is 2:1-3; S4, soaking the initial mesoporous silica microspheres in a 30 wt % hydrochloric acid solution at 120° C. at a mass ratio of 1:25 for 6 h, washing and drying, dispersing the microspheres in toluene, adding octadecyltrichlorosilane, and refluxing at 125° C. for 24 h. The resulting product is washed with toluene and ethanol in sequence, and dried to obtain mesoporous silica microspheres; wherein the mass ratio of octadecyltrichlorosilane to the initial mesoporous silica microspheres is 1:1; In step S3, the preparation method of the modified poly(glycidyl methacrylate)-co-ethylene glycol dimethacrylate) microsphere solution is as follows: dispersing poly(glycidyl methacrylate)-co-ethylene glycol dimethacrylate) microspheres in deionized water, adding tetraethylene pentamine after ultrasonic treatment, reacting at 80° C. for 12 hours, washing and drying after the reaction; mixing the microspheres obtained after drying with isopropanol and deionized water, and ultrasonically treating at 600W for 15 minutes to obtain a modified poly(glycidyl methacrylate)-co-ethylene glycol dimethacrylate) microsphere solution; wherein the mass ratio of poly(glycidyl methacrylate)-co-ethylene glycol dimethacrylate microspheres to tetraethylene pentamine is 1:2~4; and the mass ratio of the microspheres obtained after drying to isopropanol and deionized water is 1:20:

4.

2. The method for preparing mesoporous silica microspheres according to claim 1, wherein: In step S1, the silica sol aqueous phase W1 is prepared by dissolving a silane coupling agent and sodium carboxymethyl cellulose in deionized water, and ultrasonically dispersing the mixture at 600W for 30 minutes. The mass fractions of the silane coupling agent and sodium carboxymethyl cellulose dissolved in deionized water are 1.5-2.0wt% and 0.1-0.5wt%, respectively. The viscosity of the silica sol aqueous phase is 500-800mPa·s at room temperature.

3. The method for preparing mesoporous silica microspheres according to claim 1, wherein: In step S1, the oil phase O is prepared by dissolving polyglycerol ricinoleate in cyclohexane / liquid paraffin at a solid-liquid ratio of 1:30, with the volume ratio of cyclohexane to liquid paraffin being 3:1; the external aqueous phase W2 is prepared by mixing 2 wt% polyvinyl alcohol solution and 0.4 wt% sodium lauryl sulfate solution at a volume ratio of 1:1, and stirring at 300 rpm for 12 minutes.

4. The method for preparing mesoporous silica microspheres according to claim 1, wherein: In step S2, the tetraethoxysilane solution and the hexadecyltrimethylammonium bromide solution are added dropwise in a pulsed manner: the tetraethoxysilane solution and the hexadecyltrimethylammonium bromide solution are added alternately every 10 minutes, and the total number of additions is 6 to 10 times.

5. The method for preparing mesoporous silica microspheres according to claim 1, wherein: The preparation method of the polymethacrylate-co-ethylene glycol dimethacrylate microspheres comprises the following steps: dissolving glycidyl methacrylate, ethylene dimethacrylate, and cyclohexanol in deionized water, mixing uniformly, and emulsifying for 30 minutes to obtain an emulsified mixture; adding the emulsified mixture to a styrene seed suspension, reacting in a water bath at 70° C. for 24 hours, washing the obtained microspheres with water, extracting with toluene to remove cyclohexanol, and drying at 50° C. for 6 hours to obtain the polymethacrylate-co-ethylene glycol dimethacrylate microspheres; wherein the mass ratio of glycidyl methacrylate, ethylene dimethacrylate, and cyclohexanol is 1:1 to 3:

2.

6. The method for preparing mesoporous silica microspheres according to claim 5, wherein: The preparation method of the styrene seed suspension comprises: dispersing polymerized styrene in an anhydrous ethanol medium under a nitrogen atmosphere, adding dicyclohexylcarbodiimide and polyvinylpyrrolidone, mixing uniformly, performing ultrasonic treatment, stirring at 70° C. and 120 rpm for 24 hours, centrifuging, washing, and drying to obtain styrene seeds; Styrene seeds were dispersed in deionized water, and benzoyl peroxide and polyvinyl alcohol were added. After ultrasonic dispersion, the suspension was stirred in a 30°C water bath for 30 minutes to obtain a styrene seed suspension. The added amounts of dicyclohexylcarbodiimide and polyvinyl pyrrolidone were 5wt% and 1wt% of the polymerized styrene, respectively. The mass ratio of styrene seeds, benzoyl peroxide, and polyvinyl alcohol was 1:0.2 to 0.5:

3.

7. The mesoporous silica microspheres prepared by the method for preparing mesoporous silica microspheres according to claim 1.

8. Use of the mesoporous silica microspheres prepared by the method for preparing mesoporous silica microspheres according to claim 1 in high performance liquid chromatography, characterized in that: Mesoporous silica microspheres were dispersed in toluene solution at a solid-liquid ratio of 1:20 and loaded into a stainless steel column as a suspension at 40 MPa for high performance liquid chromatography.

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