A method for preparing monodisperse silica core-shell microspheres using a dual template method

Abstract

The invention discloses a method for preparing monodisperse silica core-shell microspheres by adopting a double template method, and relates to the technical field of chromatographic separation materials. The invention utilizes micron-level polymer microspheres and nanometer-level pore templates, and by adding silicon sources and catalysts at different time periods, the pore templates are coated on solid silica microspheres to form composite silica core-shell microspheres, and the microsphere templates and the pore templates are removed by dissolution extraction and high-temperature calcination to obtain silica core-shell microspheres with porous surfaces. The invention completes the control of the particle size of the microspheres, the thickness of the core-shell layer and the size of the pore structure in the same reaction system, and solves the problems of the traditional long time consumption and the occurrence of agglomeration. The silica core-shell microspheres prepared by the technology have good morphology and monodispersity, and the core-shell layer thickness and pore structure control method are simple, and are suitable for use in chromatographic separation.

Description

Technical Field

[0001] The invention relates to the technical field of chromatographic separation materials, and in particular to a method for preparing monodisperse silicon dioxide core-shell microspheres by adopting a double template method. Background Art

[0002] Due to the inherent defects of porous fillers and the requirements of scientific development for rapid and efficient separation, silica core-shell microspheres are widely used in high performance liquid chromatography due to their special structure and superior separation performance. Compared with non-porous silica spheres of the same particle size, porous silica core-shell microspheres have a large sample loading capacity and a special non-porous core and mesoporous shell structure, which not only ensures their high mechanical strength, but also greatly shortens the diffusion distance of the solute, which can significantly shorten the time required for the separation process. Traditional preparation of silica core-shell microspheres uses layer-by-layer self-assembly method, polymerization-induced deposition method, etc., but they all present different problems, such as long time consumption, small pore size of silica spheres, agglomeration and secondary nucleation. Based on the above problems, we have developed a dual-template method for the preparation of monodisperse silica core-shell microspheres. Summary of the invention

[0003] The main purpose of the present invention is to provide a method for preparing monodisperse silica core-shell microspheres by using a dual template method, using a micron-sized polymer microsphere template and a pore template, using a one-step method to add a silicon source at different time periods to form composite silica core-shell microspheres, and then removing the template to obtain silica core-shell microspheres with good monodispersity, adjustable core-shell thickness and pore structure, thereby solving the problems of long time consumption and agglomeration in the traditional method.

[0004] To achieve the above object, the technical solution adopted by the present invention is:

[0005] The present invention provides a method for preparing monodisperse silica core-shell microspheres by using a dual template method, comprising the following steps:

[0006] Step S1, obtaining solid silica microspheres: dispersing a micron-sized polymer microsphere template in a solvent to form a micron-sized polymer microsphere template suspension, and adding a catalyst and a silicon source to the micron-sized polymer microsphere template suspension to form solid silica microspheres;

[0007] Step S2, obtaining composite silica core-shell microspheres: adding a silicon source, a catalyst and a pore template into solid silica microspheres, and doping the nano-sized micelles in the pore template into the shell layer of the silica microspheres to form composite silica core-shell microspheres;

[0008] Step S3, preparing silica core-shell microspheres: performing dissolution extraction or high-temperature calcination treatment on the composite silica core-shell microspheres to remove the micron-sized polymer microsphere template and the pore template to obtain silica core-shell microspheres.

[0009] As a further optimization scheme of the present invention, the micron-sized polymer microsphere template in step S1 is a polymer microsphere with a group modified on the surface, wherein the surface modified group is any one of an amino group, a carboxyl group, and a sulfonic acid group.

[0010] As a further optimization scheme of the present invention, the micron-sized polymer microsphere template is a polymer microsphere with amino groups modified on the surface.

[0011] As a further optimization scheme of the present invention, the solvent in step S1 is a mixed solution of lower alcohol and water, wherein the lower alcohol and water are ethanol / water 1:10 to 10:1 V / V or methanol / water 1:10 to 10:1 V / V.

[0012] As a further optimization scheme of the present invention, the catalyst is a weak alkaline substance soluble in a solvent, and the weak alkaline substance includes an organic base and an inorganic base.

[0013] As a further optimization scheme of the present invention, the catalyst in step S1 and step S2 is triethylamine, ethylenediamine, trimethylammonium hydroxide or diethanolamine, and the catalyst concentration is 0.05-1 mol / L.

[0014] As a further optimization scheme of the present invention, the pore template in step S2 is a composite template, wherein the composite template is dodecylamine and dodecylamine polyoxyethylene ether or polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer and polyethylene glycol dodecyl ether, and the mass ratio of the composite template is 1:1.

[0015] As a further optimization scheme of the present invention, the silicon source in step S1 and step S2 is an inorganic silicon source tetraethyl orthosilicate, and the concentration of the silicon source is 0.01-1 mol / L.

[0016] As a further optimization scheme of the present invention, the pore size of the core-shell layer of the silica core-shell microspheres in step 3 is 1 to 500 nm.

[0017] As a further optimization scheme of the present invention, the high temperature calcination curing temperature in step 3 is 600° C. to 800° C., and the calcination time is 6 to 10 hours.

[0018] By using micron-scale polymer microspheres and nano-scale pore templates, silicon sources and catalysts are added at different time periods to coat the pore templates on solid silica microspheres to form composite silica core-shell microspheres. The microsphere templates and pore templates are removed by dissolution extraction and high-temperature calcination to obtain silica core-shell microspheres with porous surfaces. The silica core-shell microspheres prepared by this technology are highly uniform, with controllable core-shell layer thickness and pore structure.

[0019] Compared with the prior art, the present invention has the following beneficial effects: the present invention completes the control of the particle size of the microspheres, the thickness of the core-shell layer and the size of the pore structure in the same reaction system, thus solving the problems of the traditional long time consumption and agglomeration. Therefore, for the preparation of other silica core-shell microspheres with uniform particle sizes and target pore structures, the method is more scalable and reproducible. The silica core-shell microspheres prepared by the method have good morphology and monodispersity, and the method for regulating the thickness of the core-shell layer and the pore structure is simple, which is suitable for use in chromatographic separation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic flow chart of a method for preparing monodisperse silica core-shell microspheres using a dual template method according to the present invention;

[0021] Figure 2 This is a scanning electron microscope image of silica microspheres;

[0022] Figure 3 This is a scanning electron micrograph of monodisperse silica core-shell microspheres. DETAILED DESCRIPTION

[0023] The present application is further described in detail below in conjunction with the accompanying drawings. It is necessary to point out here that the following specific implementation methods are only used to further illustrate the present application and cannot be understood as limiting the scope of protection of the present application. Technical personnel in this field can make some non-essential improvements and adjustments to the present application based on the above application content.

[0024] Example

[0025] like Figure 1 As shown, the embodiment of the present invention includes the following steps:

[0026] Step S1, obtain solid silica microspheres: take 20g of commercially available 7μm PGMA / EGDMA porous cross-linked microspheres, ultrasonically disperse them in 240mL of anhydrous ethanol and 60mL of water, add 9mL of triethylamine, and mechanically stir at 150rpm. Prepare a mixed solution of 90g TEOS and 60mL of anhydrous ethanol, add it dropwise into the reaction emulsion at a rate of 0.5mL / min, react for 24h after the addition is complete, mechanically stir the reaction at 60℃ for 24h (150rpm), wash with water until neutral, wash with alcohol, and dry at 80℃ to obtain silica microspheres. Figure 2 It can be seen that the pore size of this silica microsphere is very small and can be regarded as a solid silica microsphere;

[0027] Step S2, obtaining composite silica core-shell microspheres: adding a template mixture solution (13 g of dodecylamine and 13 g of dodecylamine polyoxyethylene ether, dissolved in 1200 mL of methanol and 500 mL of water), adding 25 mL of TEOS, stirring for 1 min to mix, adding 2 mL of ammonia water (28%), stirring for 10 s, stopping stirring, standing at 25 ° C for 24 h, filtering, washing with water and ethanol three times in sequence, to form composite silica core-shell microspheres;

[0028] Step S3, preparing silica core-shell microspheres: drying the composite silica core-shell microspheres in an oven at 80°C for 12 h, raising the temperature of the dried microspheres to 600°C over a 180 min program, and calcining at 600°C for 7 h to remove the organic template therein, thereby obtaining silica core-shell microspheres, such as Figure 3 shown.

[0029] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing monodisperse silica core-shell microspheres using a dual template method, characterized in that: The steps include: Step S1, obtaining solid silica microspheres: dispersing a micron-sized polymer microsphere template in a solvent to form a micron-sized polymer microsphere template suspension, adding a catalyst and a silicon source to the micron-sized polymer microsphere template suspension to form solid silica microspheres, wherein the micron-sized polymer microsphere template is a polymer microsphere with amino groups modified on the surface; Step S2, obtaining composite silica core-shell microspheres: adding a silicon source, a catalyst and a pore template into solid silica microspheres, and doping the nano-sized micelles in the pore template into the shell layer of the silica microspheres to form composite silica core-shell microspheres, wherein the pore template is a composite template agent, wherein the composite template agent is dodecylamine and dodecylamine polyoxyethylene ether or a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer and polyethylene glycol dodecyl ether, and the mass ratio of the composite template agent is 1:1; Step S3, preparing silica core-shell microspheres: dissolving and extracting or high-temperature calcining the composite silica core-shell microspheres to remove the micron-sized polymer microsphere template and the pore template to obtain silica core-shell microspheres, wherein the pore size of the core-shell layer of the silica core-shell microspheres is 1-500 nm.

2. The method for preparing monodisperse silica core-shell microspheres by using a dual template method according to claim 1, characterized in that: In the step S1, the solvent is a mixed solution of lower alcohol and water, wherein the lower alcohol and water are ethanol / water 1:10-10:1 V / V or methanol / water 1:10-10:1 V / V.

3. The method for preparing monodisperse silica core-shell microspheres by using a dual template method according to claim 1, characterized in that: The catalyst is a weakly alkaline substance soluble in a solvent, and the weakly alkaline substance includes an organic base and an inorganic base.

4. The method for preparing monodisperse silica core-shell microspheres by using a dual template method according to claim 1, characterized in that: The catalyst in step S1 and step S2 is triethylamine, ethylenediamine, trimethylammonium hydroxide or diethanolamine, and the catalyst concentration is 0.05-1 mol / L.

5. The method for preparing monodisperse silica core-shell microspheres by using a dual template method according to claim 1, characterized in that: The silicon source in step S1 and step S2 is tetraethyl orthosilicate, and the concentration of the silicon source is 0.01-1 mol / L.

6. The method for preparing monodisperse silica core-shell microspheres by using a dual template method according to claim 1, characterized in that: In step S3, the high temperature calcination curing temperature is 600° C. to 800° C., and the calcination time is 6 to 10 hours.

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