Micro-suspension polymerization preparation method of polydisperse crosslinked polystyrene porous microspheres

Abstract

The invention provides a micro-suspension polymerization preparation method of polydisperse crosslinked polystyrene porous microspheres, and particularly relates to the technical field of organic synthesis. The preparation method of the crosslinked polystyrene porous microspheres comprises the following steps: uniformly mixing a styrene monomer, a crosslinking agent, an initiator, a pore-foaming agent, an emulsifier and deionized water, emulsifying into small liquid drops, adding a stabilizer, and polymerizing under the protection of nitrogen to obtain the polystyrene porous microspheres. According to the preparation method, the emulsifier is added in the preparation process to disperse the monomer into micro-droplets with smaller particle size, so that the particle size distribution range of the polystyrene porous microspheres is remarkably reduced, the particle size of the polystyrene porous microspheres is far smaller than that of the microspheres prepared by a traditional suspension polymerization method, and the preparation of the submicron porous microspheres is realized. Meanwhile, the pore diameter structure and the particle size distribution of the porous microspheres are regulated and controlled by optimizing factors such as the dosage of a mixed monomer or a pore-foaming agent, the stirring speed, the type and the ratio of an emulsifier and the like, so that the pore structure is more uniform and dense, the specific surface area is large, and the requirement of stage treatment is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of organic synthesis, and particularly relates to a method for preparing polydisperse crosslinked polystyrene porous microspheres by micro-suspension polymerization. Background Art

[0002] Porous materials are widely used in industrial separation and purification processes. Currently, there are various types of porous materials, such as silica gel, zeolite, activated carbon, porous metals, porous polymer materials, etc., which are widely used in the fields of purification and separation of liquids and gases, ion exchange resins, catalyst carriers, and aerospace materials. Among them, porous polymer materials have attracted much attention due to their low density, high porosity, and easy functionalization. In particular, polystyrene-based porous microspheres have received extensive attention because of their simple preparation method, high mechanical strength, good chemical stability, and compatibility with polar and non-polar organic solvents.

[0003] The preparation methods of polystyrene-based porous microspheres mainly include dispersion polymerization, seed swelling polymerization, precipitation polymerization, and suspension polymerization, etc. Suspension polymerization is a traditional method for preparing porous polymer microspheres. Through strong mechanical stirring, monomers or monomer mixtures insoluble in water are dispersed in a suspension medium for polymerization reaction. The particle size of the obtained microspheres depends on the size of the monomer droplets, and the droplet size is affected by the stirring speed, the amount of dispersant, and the external environment. Suspension polymerization can generate microspheres with a particle size range of 50 μm to 1 mm, but the size distribution is relatively wide, and usually requires classification treatment before use.

[0004] Although suspension polymerization is a traditional method for preparing porous polymer microspheres, it still faces some technical problems in practical applications. First, due to the uncertainty in controlling the size of monomer droplets, even if the stirring form and speed are strictly controlled, the particle size and pore size distribution of the obtained microspheres are still relatively wide, making it difficult to meet the requirements of high-precision applications. Second, it is difficult to prepare porous microspheres with smaller particle size and uniform distribution by suspension polymerization, which limits its application in some high-precision fields. That is to say, suspension polymerization still faces technical challenges in aspects such as particle size distribution control, process complexity, and embedding of functional substances.

[0005] In view of this, the present invention is specifically proposed. Summary of the Invention

[0006] One of the purposes of the present invention is to provide a method for preparing crosslinked polystyrene porous microspheres, aiming to solve at least one of the above technical problems in the prior art.

[0007] Another purpose of the present invention is to provide a crosslinked polystyrene porous microsphere.

[0008] In order to achieve the above purposes of the present invention, the following technical solutions are specifically adopted:

[0009] The first aspect of the present invention provides a method for preparing polystyrene porous microspheres. Styrene monomer, crosslinking agent, initiator, porogen, emulsifier and reaction solvent are mixed uniformly and emulsified into small droplets, and then added to a stabilizer solution. Under nitrogen protection, stirring and reflux reaction is carried out to obtain polystyrene porous microspheres.

[0010] Further, the reaction solvent includes deionized water.

[0011] Preferably, the volume of the styrene monomer is 0.5 to 4% of the volume of the reaction solvent.

[0012] Further, the crosslinking agent includes divinylbenzene (DVB), ethylene glycol dimethacrylate (EGDMA), and ethylene glycol dimethacrylate (DEGDMA).

[0013] Preferably, the volume ratio of the crosslinking agent to the styrene monomer is 0.15 to 5:1.

[0014] Further, the initiator includes benzoyl peroxide (BPO), azobisisobutyronitrile (AIBN).

[0015] Preferably, the mass of the initiator is 3 to 14% of the total volume of the crosslinking agent and the styrene monomer.

[0016] Further, the porogen includes dibutyl phthalate (DBP), toluene, n-hexane or n-heptane.

[0017] Preferably, the dosage of the porogen is 0.5 to 2 wt% of the mass of the reaction solvent.

[0018] Further, the emulsifier includes at least one of sodium dodecyl sulfate (SDS), sodium dodecylbenzenesulfonate (LAS), Tween 20, Span 80, polyethylene glycol (PEG), and polyvinylpyrrolidone (PVP).

[0019] Preferably, the dosage of the emulsifier is 0.1 to 0.6 wt% of the mass of the reaction solvent.

[0020] Further, the stabilizer in the stabilizer solution includes polyvinyl alcohol (PVA), hydroxyethyl cellulose (HEC), and gelatin-arabic gum.

[0021] Preferably, the dosage of the stabilizer is 0.1 to 1 wt% of the mass of the reaction solvent.

[0022] Preferably, the mass concentration of the stabilizer solution is 3 to 8 wt%.

[0023] Further, the temperature of the reaction is 65 to 90 °C.

[0024] Preferably, the reaction time is 8 to 16 h.

[0025] Preferably, the stirring speed is 100 to 300 rpm.

[0026] Furthermore, the emulsification time is 15 to 40 min.

[0027] The second aspect of the present invention provides a crosslinked polystyrene porous microsphere, which is prepared by the preparation method described in the first aspect.

[0028] Furthermore, the particle size is 500 nm to 1.6 μm.

[0029] Compared with the prior art, the present invention has at least the following beneficial effects:

[0030] The preparation method provided by the present invention disperses the monomer into smaller micro-droplets by adding an emulsifier during the preparation process, significantly narrowing the particle size distribution range of the polystyrene porous microspheres, which is much smaller than the particle size of the microspheres prepared by the traditional suspension polymerization method, realizing the preparation of sub-micron porous microspheres. At the same time, the dosage and proportion of other raw materials regulate the pore structure and distribution of the porous microspheres, making the pore structure more uniform and dense, with a large specific surface area, reducing the need for classification treatment.

[0031] The crosslinked polystyrene porous microspheres provided by the present invention have a smaller particle size distribution range, a uniform and dense pore structure, and a large specific surface area, improving the adsorption and separation performance of the polystyrene porous microspheres, expanding the application fields of the polystyrene porous microspheres, reducing the application cost, and promoting the development of downstream industries. Description of the Drawings

[0032] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. Obviously, the following drawings are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0033] Figure 1 SEM photographs obtained for the characterization examples. Detailed Embodiments

[0034] To make the objectives, technical solutions, and advantages of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some, rather than all, embodiments of the present invention.

[0035] In the following, the terms "comprising", "having" and their cognates that can be used in various embodiments of the present invention are only intended to denote specific features, numbers, steps, operations, elements, components or combinations of the foregoing items, and should not be construed as precluding the existence of one or more other features, numbers, steps, operations, elements, components or combinations of the foregoing items or as precluding the possibility of adding one or more features, numbers, steps, operations, elements, components or combinations of the foregoing items.

[0036] The first aspect of the present invention provides a method for preparing cross-linked polystyrene porous microspheres. A styrene monomer, a cross-linking agent, an initiator, a pore-forming agent, an emulsifier and a reaction solvent are mixed uniformly and emulsified into small droplets, and then a stabilizer solution is added. The mixture is stirred and refluxed under nitrogen protection to obtain polystyrene porous microspheres.

[0037] In the preparation method provided by the present invention, by adding an emulsifier during the preparation process, the monomer is dispersed into smaller micro-droplets, significantly narrowing the particle size distribution range of the cross-linked polystyrene porous microspheres, which is much smaller than the particle size of the microspheres prepared by the traditional suspension polymerization method, and realizing the preparation of sub-micron porous microspheres. At the same time, the dosage and proportion of other raw materials regulate the pore size structure and distribution of the porous microspheres, making the pore structure more uniform and dense, with a large specific surface area and reducing the need for classification treatment.

[0038] Further, the reaction solvent includes deionized water.

[0039] Preferably, the volume of the styrene monomer is 0.5-4% of the volume of the reaction solvent.

[0040] Typically but not restrictively, the volume of the styrene monomer can be, for example, 0.5%, 1%, 2%, 3% or 4% of the volume of the reaction solvent, or any value within the range of 0.5-4%.

[0041] Further, the cross-linking agent includes divinylbenzene (DVB), ethylene glycol dimethacrylate (EGDMA), ethylene glycol dimethacrylate (DEGDMA).

[0042] Preferably, the volume ratio of the cross-linking agent to the styrene monomer is 0.15-5:1. The cross-linking agent within this dosage range ensures that the polystyrene has a suitable cross-linking degree and mechanical strength, enhances the rigidity of the pore wall structure, makes the pore distribution more uniform, and at the same time helps to improve the sphericity of the microspheres and avoid microsphere collapse.

[0043] Typically but not restrictively, the volume ratio of the crosslinking agent to the styrene monomer can be, for example, 0.15:1, 0.25:1, 0.35:1, 0.45:1, 0.55:1, 0.65:1, 0.75:1, 0.85:1, 1:1, 1.5:1, 2:1, 3:1, 4:1 or 5:1, or can also be any value within the range of 0.15 to 5:1.

[0044] Furthermore, the initiator includes benzoyl peroxide (BPO) and azobisisobutyronitrile (AIBN). Conducting Reaction One under nitrogen protection serves two purposes: one is to prevent the initiator from being quenched by oxygen, and the other is to avoid side reactions between active free radicals and oxygen; ensuring the efficient progress of the polymerization reaction and improving the monomer conversion rate and the integrity of the microsphere structure.

[0045] Preferably, the mass of the initiator is 3 to 14% of the total volume of the crosslinking agent and the styrene monomer.

[0046] Typically but not restrictively, the mass of the initiator can be, for example, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13% or 14% of the total volume of the crosslinking agent and the styrene monomer, or can also be any value within the range of 3% to 14% of the total volume of the crosslinking agent and the styrene monomer.

[0047] Furthermore, the pore-forming agent includes dibutyl phthalate (DBP), toluene, n-hexane or n-heptane. The pore-forming agent forms phase separation during the polymerization process and is removed by volatilization or extraction after polymerization is completed, leaving uniform and dense voids.

[0048] Preferably, the dosage of the pore-forming agent is 0.5 to 2 wt% of the mass of the reaction solvent. Typically but not restrictively, the dosage of the pore-forming agent can be, for example, 0.5 wt%, 0.8 wt%, 1.0 wt%, 1.2 wt%, 1.5 wt%, 1.8 wt% or 2.0 wt% of the mass of the reaction solvent, or can also be any value within the range of 0.5 to 2 wt%.

[0049] Furthermore, the emulsifier includes at least one of sodium dodecyl sulfate (SDS), sodium dodecylbenzenesulfonate (LAS), Tween 20, Span 80, polyethylene glycol (PEG) and polyvinylpyrrolidone (PVP).

[0050] Preferably, the dosage of the emulsifier is 0.1 - 0.6 wt% of the mass of the reaction solvent. Typically but not restrictively, the dosage of the emulsifier can be, for example, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt% or 0.6 wt% of the mass of the reaction solvent, or any value within the range of 0.1 - 0.6 wt%.

[0051] Furthermore, the stabilizers in the stabilizer solution include polyvinyl alcohol (PVA), hydroxyethyl cellulose (HEC), and gelatin - arabic gum. The stabilizers coat the surface of the droplets, preventing the droplets from colliding and merging during the polymerization process and maintaining the uniformity of the droplet size after emulsification.

[0052] Preferably, the dosage of the stabilizer is 0.1 - 1 wt% of the mass of the reaction solvent. Typically but not restrictively, the dosage of the stabilizer can be, for example, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt% or 1 wt% of the mass of the reaction solvent, or any value within the range of 0.1 wt% - 1 wt% of the mass of the styrene monomer.

[0053] Preferably, the mass concentration of the stabilizer solution is 3 - 8 wt%. Typically but not restrictively, the mass concentration of the stabilizer solution can be, for example, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt% or 8 wt%, or any value within the range of 3 - 8 wt%.

[0054] Furthermore, the temperature of the reaction is 65 - 90 °C. Typically but not restrictively, the temperature of the reaction can be, for example, 65 °C, 70 °C, 75 °C, 80 °C, 85 °C or 90 °C, or any value within the range of 65 °C - 90 °C.

[0055] Preferably, the time of the reaction is 8 - 16 h. Typically but not restrictively, the time of the reaction can be, for example, 8 h, 9 h, 10 h, 11 h, 12 h, 13 h, 14 h, 15 h or 16 h, or any value within the range of 8 h - 16 h.

[0056] Preferably, the rotation speed of the stirring is 100 - 300 rpm. Typically but not restrictively, the rotation speed of the stirring can be, for example, 100 rpm, 150 rpm, 200 rpm, 250 rpm or 300 rpm, or any value within the range of 100 rpm - 300 rpm.

[0057] Further, the emulsification time is 15 to 40 min. Typically but not restrictively, the emulsification time can be, for example, 15 min, 20 min, 25 min, 30 min, 35 min, or 40 min, or any value within the range of 15 min to 40 min.

[0058] Further, a cell disruptor is used for the emulsification. When the cell disruptor is performing emulsification, the monomer is dispersed into smaller micro-droplets by means of ultrasound.

[0059] The second aspect of the present invention provides a cross-linked polystyrene porous microsphere, which is prepared by using the preparation method described in the first aspect.

[0060] The polystyrene porous microspheres provided by the present invention have a smaller particle size distribution range, a uniform and dense pore structure, a large specific surface area, improve the adsorption and separation performance of the polystyrene porous microspheres, expand the application fields of the polystyrene porous microspheres, reduce the application cost, and promote the development of downstream industries.

[0061] Further, the particle size is 500 nm to 1.6 μm.

[0062] The cross-linked polystyrene porous microspheres provided by the present invention have a large specific surface area and can meet the applications in different scenarios, including industrial separation and purification treatment, being used as a template for functional modification for biological separation and immunoassay.

[0063] The present invention will be further described below through specific examples and comparative examples. However, it should be understood that these examples are only used for more detailed description and should not be construed as limiting the present invention in any form. For the raw materials used in the examples and comparative examples of the present invention, without specifying specific conditions, they are carried out according to conventional conditions or the conditions recommended by the manufacturer. For the reagents or instruments without specifying the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0064] Example 1

[0065] This example provides a polystyrene porous microsphere, and the preparation method is as follows:

[0066] 1. Weigh 3 mL of monomer St, 3 mL of cross-linking agent DVB, 0.8 g of initiator BPO, and 3 g of porogen DBP and add them to a beaker. Finally, add 0.5 g of emulsifier LAS and 190 g of deionized water.

[0067] 2. After mixing the above solution evenly, emulsify it with a cell disruptor for 20 min, then transfer the above emulsion into a three-necked flask, and then add 20 g of an appropriate amount of 5% PVA solution. Under nitrogen protection, stir and reflux at 70 °C and 200 rpm for 12 h to obtain a white emulsion product, that is, polystyrene porous microspheres.

[0068] Example 2

[0069] This example provides a polystyrene porous microsphere, and the preparation method is as follows:

[0070] 1. Weigh 2 mL of monomer St, 4 mL of crosslinking agent DVB, 0.4 g of initiator BPO, and 2 g of porogen DBP and add them to a beaker. Finally, add 0.27 g of emulsifier SDS and 190 g of deionized water.

[0071] 2. After mixing the above solution evenly, emulsify it with a cell disruptor for 25 minutes. Then transfer the above emulsion into a three-necked flask, and add 20 g of an appropriate amount of 5% PVA solution. Under nitrogen protection, stir and reflux at 70 °C and 200 rpm for 12 h to obtain a white emulsion product, that is, polystyrene porous microspheres.

[0072] Example 3

[0073] This example provides a polystyrene porous microsphere, and the preparation method is as follows:

[0074] 1. Weigh 3 mL of monomer St, 3 mL of crosslinking agent DVB, 0.5 g of initiator BPO, and 1.36 g of porogen toluene and add them to a beaker. Finally, add 0.45 g of emulsifier Tween 20 and deionized water.

[0075] 2. After mixing the above solution evenly, emulsify it with a cell disruptor for 30 minutes. Then transfer the above emulsion into a three-necked flask, and add 15 g of an appropriate amount of 5% hydroxyethyl cellulose solution. Under nitrogen protection, stir and reflux at 80 °C and 250 rpm for 10 h to obtain a white emulsion product, that is, polystyrene porous microspheres.

[0076] Example 4

[0077] This example provides a polystyrene porous microsphere, and the preparation method is as follows:

[0078] 1. Weigh 2 mL of monomer St, 4 mL of crosslinking agent DVB, 0.6 g of initiator BPO, and 2.2 g of porogen n-heptane and add them to a beaker. Finally, add 1.0 g of emulsifier LAS and 190 g of deionized water.

[0079] 2. After mixing the above solution evenly, emulsify it with a cell disruptor for 40 minutes. Then transfer the above emulsion into a three-necked flask, and add 15 g of an appropriate amount of 3% PVA solution. Under nitrogen protection, stir and reflux at 65 °C and 100 rpm for 16 h to obtain a white emulsion product, that is, polystyrene porous microspheres.

[0080] Example 5

[0081] This embodiment provides a polystyrene porous microsphere, and the preparation method is as follows:

[0082] 1. Weigh 3 mL of monomer St, 3 mL of crosslinking agent DVB, 0.48 g of initiator BPO, and 1.81 g of porogen DBP and add them to a beaker. Finally, add 0.54 g of emulsifier Span 80 and 190 g of deionized water.

[0083] 2. After mixing the above solution evenly, emulsify it with a cell disruptor for 15 min. Then transfer the above emulsion into a three-necked flask, and add 25 g of an appropriate amount of 5% PVA solution. Under nitrogen protection, stir and reflux at 90 °C and 300 rpm for 8 h to obtain a white emulsion product, that is, polystyrene porous microspheres.

[0084] Example 6

[0085] This embodiment provides a polystyrene porous microsphere. Different from Example 1, the amount of the crosslinking agent used is 2 mL, and the amounts of the remaining raw materials are the same as those in Example 1, which will not be elaborated here.

[0086] Example 7

[0087] This embodiment provides a polystyrene porous microsphere. Different from Example 1, the amount of the crosslinking agent used is 6 mL, and the amounts of the remaining raw materials are the same as those in Example 1, which will not be elaborated here.

[0088] Example 8

[0089] This embodiment provides a polystyrene porous microsphere. Different from Example 1, the amount of porogen DBP used is 1.2 g, and the remaining raw materials and preparation method are the same as those in Example 1, which will not be elaborated here.

[0090] Example 9

[0091] This embodiment provides a polystyrene porous microsphere. Different from Example 1, the amount of porogen DBP used is 4.0 g, and the remaining raw materials and preparation method are the same as those in Example 1, which will not be elaborated here.

[0092] Example 10

[0093] This embodiment provides a polystyrene porous microsphere. Different from Example 1, the amount of emulsifier PVP used is 0.64 g, and the remaining raw materials and preparation method are the same as those in Example 1, which will not be elaborated here.

[0094] Example 11

[0095] This embodiment provides a polystyrene porous microsphere. Different from Example 1, the amount of emulsifier PEG used is 0.9 g, and the remaining raw materials and preparation method are the same as those in Example 1, which will not be elaborated here.

[0096] Comparative Example 1

[0097] This example provides a polystyrene porous microsphere. Different from Example 1, emulsifier LAS is not added, and the remaining raw materials and preparation methods are the same as those in Example 1, which will not be elaborated here.

[0098] Comparative Example 2

[0099] This example provides a polystyrene porous microsphere. Different from Example 1, crosslinking agent DVB is not added, and the remaining raw materials and preparation methods are the same as those in Example 1, which will not be elaborated here.

[0100] Comparative Example 3

[0101] This example provides a polystyrene porous microsphere. Different from Example 1, PVA solution is not added, and the remaining raw materials and preparation methods are the same as those in Example 1, which will not be elaborated here.

[0102] Characterization Example

[0103] The polystyrene porous microspheres of Example 1 were subjected to scanning electron microscopy, and the obtained pictures are as Figure 1 shown.

[0104] From Figure 1 the scanning electron microscope (SEM) images, it can be seen that the particle size distribution of the polystyrene porous microspheres is in the range of 500 nm - 1.6 μm. The particle size distribution is significantly smaller and narrower than that of traditional suspension polymerization (50 μm - 1 mm). The sphericity of the particle size distribution microspheres is good, the surface pore diameter of the porous microspheres is dense, and the surface is relatively rough, indicating that the specific surface area of the porous microspheres is large, which is beneficial to subsequent practical applications.

[0105] Testing Example

[0106] The polystyrene porous microspheres obtained in the examples and comparative examples were characterized by microscopy and SEM to observe their particle size distribution and morphology.

[0107] The obtained data are shown in Table 1 below.

[0108] Table 1

[0109]

[0110] As can be seen from Table 1, when preparing polydisperse porous microspheres by micro-suspension polymerization, without adding an emulsifier, PVA cannot emulsify the oil phase and water phase into uniform micron-sized small droplets, resulting in a wider particle size distribution and larger particle size. Adding an appropriate amount of emulsifier can make the particle size distribution narrower, but excessive emulsifier may produce extra micelles, leading to instability at the oil-water interface of the emulsion and causing aggregation. Moreover, there are significant differences in the emulsifying ability of different types of emulsifiers for the water phase and oil phase, and they have an obvious impact on the size and stability of the small oil droplets in the water phase. The role of the stabilizer is to stabilize the small oil droplets in the continuous phase, enabling them to better disperse in the water phase and avoid self-aggregation. Without adding a stabilizer, the stability of the microspheres during the polymerization process will be imbalanced, resulting in the coalescence of some microspheres. In addition, without a cross-linking agent, the rigidity of the microspheres is insufficient and prone to causing the collapse of the spherical structure. Therefore, factors such as the amount of porogen, the amount of mixed monomers, the stirring speed, the type and ratio of emulsifiers can be optimized to control the particle size distribution and pore structure of the porous microspheres.

[0111] Finally, it should be noted that the above-described embodiments are only specific embodiments of the present invention, used to illustrate the technical solutions of the present invention, rather than limiting it. The protection scope of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: any person skilled in the art within the technical scope disclosed by the present invention can still modify the technical solutions recorded in the foregoing embodiments or easily conceive of changes, or make equivalent replacements for some of the technical features; and these modifications, changes or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A method for preparing cross-linked polystyrene porous microspheres, characterized in that: The styrene monomer, crosslinking agent, initiator, porogen, emulsifier and reaction solvent are uniformly mixed and emulsified into small droplets, and then a stabilizer solution is added, and the mixture is stirred and refluxed under nitrogen protection to obtain polystyrene porous microspheres.

2. The preparation method according to claim 1, characterized in that: The reaction solvent includes deionized water; Preferably, the volume of the styrene monomer is 0.5 to 4% of the volume of the reaction solvent; Preferably, the cross-linking agent includes divinylbenzene, ethylene glycol dimethacrylate, ethylene glycol dimethacrylate; Preferably, the volume ratio of the cross-linking agent to the styrene monomer is 0.15 to 5:

1.

3. The preparation method according to claim 1, characterized in that: The initiator includes benzoyl peroxide and azobisisobutyronitrile; Preferably, the mass of the initiator is 3-14% of the total volume of the cross-linking agent and the styrene monomer.

4. The preparation method according to claim 1, characterized in that: The porogen includes dibutyl phthalate, toluene, n-hexane or n-heptane; Preferably, the amount of the porogen used is 0.5-2 wt % of the mass of the reaction solvent.

5. The preparation method according to claim 1, characterized in that: The emulsifier includes at least one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, Tween 20, Span 80, polyethylene glycol and polyvinyl pyrrolidone; preferably, the amount of the emulsifier is 0.1-0.6wt% of the mass of the reaction solvent.

6. The preparation method according to claim 1, characterized in that: The stabilizer in the stabilizer solution includes polyvinyl alcohol, hydroxyethyl cellulose, and gelatin-arabic gum; Preferably, the amount of the stabilizer used is 0.1-1 wt % of the mass of the reaction solvent.

7. The preparation method according to any one of claims 1 to 6, characterized in that: The reaction temperature is 65-90°C; Preferably, the reaction time is 8 to 16 hours; Preferably, the stirring speed is 100-300 rpm.

8. The preparation method according to any one of claims 1 to 6, characterized in that: The emulsification time is 15 to 40 minutes.

9. A cross-linked polystyrene porous microsphere, characterized in that: The preparation method is described in any one of claims 1 to 8.

10. The cross-linked polystyrene porous microspheres according to claim 9, characterized in that: The particle size is 500nm~1.6μm.

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