A porous polymer microsphere, its preparation method and application

Abstract

This invention belongs to the field of polymer microsphere technology and discloses a method for preparing porous polymer microspheres and their applications. The main steps include: adding a dispersant, stabilizer, and emulsifier to deionized water and stirring to form a homogeneous aqueous mixed solution; mixing a crosslinking agent, monomer, pore-forming agent, and initiator at room temperature to obtain a homogeneous oil mixed solution; adding the oil mixed solution to the aqueous mixed solution, stirring to disperse, and then heating to carry out a polymerization reaction; filtering the product, washing with tetrahydrofuran and methanol, drying by spray drying, and then sieving to obtain microspheres of the target particle size. The preparation process of this invention is simple and suitable for large-scale production. The obtained microspheres have high specific surface area, narrow pore size distribution, and excellent thermal stability, and can be directly used as gas chromatography packing material to achieve efficient separation of some hydrocarbon gases (such as methane, ethane-ethylene, acetylene, and propane), with high separation degree and good repeatability, meeting commercialization requirements.

Description

Technical Field

[0001] This invention belongs to the field of polymer microsphere technology, specifically relating to a porous polymer microsphere, its preparation method, and its application. Background Technology

[0002] The performance of packing material directly affects the separation efficiency and detection sensitivity of the column. Currently, the main methods for preparing microspheres for packing include suspension polymerization, seed swelling polymerization, membrane emulsification, and microfluidic methods. Compared to traditional agarose-based packing materials, which suffer from poor chemical stability and low mechanical strength, polymer microsphere packing materials (such as styrene-divinylbenzene copolymer) have become a research hotspot due to their tunable pore structure, chemical corrosion resistance, and high mechanical strength.

[0003] In the preparation of porous microspheres by suspension polymerization, a mixed oil phase is dispersed and suspended in an aqueous solvent under mechanical action, and polymerization is initiated by an initiator. However, polymer microspheres prepared by existing suspension polymerization methods generally suffer from the following defects: 1) Uneven particle size distribution: Improper selection of dispersant leads to microsphere adhesion, affecting the uniformity of column packing; 2) Insufficient pore size control: Unreasonable pore-forming agent ratio leads to wide pore size distribution or low specific surface area; 3) Poor thermal stability: Improper polymerization temperature or initiator dosage causes microsphere structural defects.

[0004] In the early 1980s, Ugelstad et al. proposed seed swelling polymerization, which uses uniformly sized microspheres obtained through dispersion polymerization as polymerization centers. After one or more steps of swelling with monomers and porogens, further polymerization yields microspheres with larger particle sizes. Patent CN118373932B describes a two-step seed swelling method using dispersion polymerization to prepare monodisperse styrene seed microspheres, followed by emulsification swelling to prepare styrene-divinylbenzene porous microspheres. This method has a complex production process, produces microspheres with small particle sizes, requires stringent reaction conditions, has an excessively long preparation cycle, and the multiple steps of polymerization, swelling, and cleaning lead to excessive reagent consumption, significant waste and pollution, and ultimately, high product costs.

[0005] Membrane emulsification is a highly efficient emulsification method that uses an inorganic membrane micropore to force a dispersed phase into a continuous phase under external pressure to form an emulsion. Then, suspension polymerization yields porous microspheres with uniform particle size. Patent CN101229509A describes the use of membrane emulsification to prepare highly cross-linked styrene-divinylbenzene porous microspheres at 60-80°C using suspension polymerization. However, this process is cumbersome and its production efficiency is unsuitable for industrial-scale production.

[0006] As can be seen from the above, the current preparation process of the microspheres containing the aforementioned fillers has technical difficulties such as long reaction time, cumbersome preparation steps, and difficulty in large-scale production. Moreover, the currently disclosed synthesis processes at home and abroad all have inconsistent particle size dispersion, small specific surface area, and complicated operations, making them unsuitable for direct application in large-scale industrial production. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention optimizes the composition of the aqueous mixed solution, the oil phase, and the polymerization process to obtain a porous polymer microsphere, solving the problems of uneven particle size, wide pore size distribution, and poor stability in the prior art, and producing a high-performance packing material suitable for separation.

[0008] In a first aspect, the present invention provides a method for preparing porous polymer microspheres, comprising the following steps: Step S1, Preparation of aqueous mixed solution: Add water to a three-necked flask, stir at 300 rpm, slowly add dispersant, stabilizer and emulsifier, continue to disperse for 30 minutes to form a homogeneous solution, and obtain aqueous mixed solution; Step S2, Preparation of oil phase mixed solution: Mix the monomer, crosslinking agent, pore-forming agent and initiator and add them to another container beaker, and sonicate to dissolve until homogeneous to obtain oil phase mixed solution; Step S3, suspension polymerization reaction: The oil phase mixture is added to the aqueous phase mixture, and the mixture is pre-dispersed by stirring at 300 rpm for 30 minutes. Then the temperature is raised to 65℃~75℃ for complete reaction to obtain the reaction solution. Step S4, post-processing: After filtering the reaction solution, wash it sequentially with tetrahydrofuran and methanol, then dry it, and use an ultrasonic vibrating sieve to obtain porous polymer microspheres of the target particle size.

[0009] Preferably, in step S1, the water is deionized water.

[0010] Preferably, the dispersant in step S1 is any one or a mixture of several of the following: hydroxypropyl methylcellulose (HPMC), carboxymethyl cellulose (CMC), hydroxyethyl cellulose, polyvinyl alcohol (PVA), and polyvinylpyrrolidone (PVP), and the amount used is 1.0 wt% to 2.0 wt% of the mass of deionized water. More preferably, the dispersant is selected from hydroxypropyl methylcellulose (HPMC) and polyvinylpyrrolidone (PVP), and the mass ratio of the two is 1:2 or 1.5:2.

[0011] Preferably, the stabilizer in step S1 is any one or a mixture of sodium sulfate and sodium chloride, and the amount used is 2.0 wt% to 4.5 wt% of the mass of deionized water. More preferably, sodium chloride is selected as the stabilizer, and when the mass of deionized water is 180 g, the mass of sodium chloride is 6 g.

[0012] Preferably, the emulsifier in step S1 is any one or a mixture of several of the following: sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and sodium bis(dodecylphenyl) ether disulfonate, and the amount used is 0.05 wt% to 0.15 wt% of the mass of deionized water. More preferably, sodium dodecyl sulfate is selected as the emulsifier.

[0013] Preferably, in step S2, the monomer is ethylene glycol dimethacrylate, the crosslinking agent is divinylbenzene, and the mass ratio is 1:(2~4). More preferably, the mass of deionized water is 180g, the mass of the monomer ethylene glycol dimethacrylate is 10g, and the mass of the crosslinking agent divinylbenzene is 32g.

[0014] Preferably, the porogen in step S2 is any one or two of toluene, cyclohexanol, dodecane, n-heptane, liquid paraffin, and 2-ethylhexanoic acid, and the amount used is 60 wt% to 150 wt% of the total mass of monomer and crosslinking agent; more preferably, the porogen is liquid paraffin and 2-ethylhexanoic acid in a mass ratio of 1:10; or dodecane and 2-ethylhexanoic acid in a mass ratio of 1:5.

[0015] Preferably, in step S2, the initiator is any one of azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, and dimethyl azobisisobutyrate, and the amount used is 2 wt% to 5 wt% of the total mass of the monomer and the crosslinking agent. More preferably, dimethyl azobisisobutyrate is selected as the initiator.

[0016] Preferably, the cleaning solvent in step S4 is tetrahydrofuran and methanol, wherein the mass of tetrahydrofuran used is 5 to 10 times the total weight of the monomer and crosslinking agent, and the amount of methanol used is 5 to 10 times the total weight of the monomer and crosslinking agent.

[0017] Preferably, in step S4, after washing, the microspheres are dried by spray drying and then sieved using an ultrasonic vibrating sieve to obtain porous polymer microspheres of the target particle size.

[0018] Preferably, in step S4, the temperature is raised to 70°C and the reaction is carried out for 16 hours.

[0019] Secondly, the present invention provides porous polymer microspheres prepared by the above-described preparation method.

[0020] Preferably, the porous polymer microspheres have a specific surface area ≥350 m² / g; an average pore size of 5 nm to 12 nm; and an average particle size of 100 μm to 200 μm.

[0021] Thirdly, the present invention provides the application of the above-mentioned porous polymer microspheres in gas chromatography separation.

[0022] This invention provides an efficient and stable method for preparing porous polymer microspheres by optimizing the suspension polymerization process. The steps include preparing an aqueous phase mixture, preparing an oil phase mixture, performing a suspension polymerization reaction, and post-treatment. This method uses different porogens and their proportions to alter the internal pore structure of the microspheres, thereby changing their porosity, pore size, and specific surface area. The particle size is adjusted using a dispersant and stirring speed. By adjusting the proportions of the dispersant and porogen and the reaction parameters, microspheres with uniform particle size and controllable pore size are obtained. These microspheres can be directly used as gas chromatography packing material to achieve efficient separation of certain hydrocarbon gases (such as methane, ethane-ethylene, acetylene, and propane), exhibiting high resolution and good repeatability, meeting commercialization requirements.

[0023] Compared with the prior art, the present invention has the following advantages: (1) The microspheres prepared by this invention have a particle size of 50 μm to 200 μm and a narrow particle size distribution; they have a high specific surface area of ​​≥350 m² / g (BET method), and the pore size, particle size and specific surface area are easy to control. (2) It has excellent separation effect on methane, ethane-ethylene, acetylene and propane mixtures and good repeatability.

[0024] The preparation process of this invention is simple, with good process stability and reproducibility, making it very suitable for industrial production. The resulting microspheres have high specific surface area, narrow pore size distribution, and excellent thermal stability. They can also be directly used as gas chromatography packing materials to achieve efficient separation of some hydrocarbon gases (such as methane, ethane-ethylene, acetylene, and propane), with high separation degree and good repeatability, and their performance meets the requirements for commercialization. Attached Figure Description

[0025] Figure 1 Scanning electron microscope image of the microspheres prepared in Example 1; Figure 2 The particle size distribution of the microspheres prepared in Example 1 is shown in the diagram. Figure 3 The image shows the BET pore size distribution of the microspheres prepared in Example 1. Figure 4 The image shows the effect of a gas chromatography column with microspheres as the stationary phase prepared in Example 1 separating methane, ethane-ethylene, acetylene, and propane mixtures under certain chromatographic conditions. Figure 5 The image shows the effect of the gas chromatography column with microspheres as the stationary phase prepared in Example 5 on the separation of methane, ethane-ethylene, acetylene, and propane mixtures under certain chromatographic conditions. Figure 6 The image shows the effect of separating methane, ethane-ethylene, acetylene, and propane mixtures using a gas chromatography column with microspheres as the stationary phase prepared in Example 5 under certain chromatographic conditions. Detailed Implementation

[0026] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention is determined by the claims.

[0027] Unless otherwise specified, all raw materials and components used in the embodiments of this invention were purchased through general commercial channels. The ultrasonic vibrating screen was purchased from Henan Xinxiang Gaofu Machinery Co., Ltd., model S49-AC-300; the spray dryer was manufactured by Shanghai Jipu Electronic Technology Co., Ltd., product model GIPP-2000.

[0028] <Example 1> Step S1, Preparation of aqueous mixed solution: Take a 500 mL three-necked flask and add 180 mL (180 g) of deionized water. Turn on the stirrer and adjust the speed to 300 rpm. While stirring, slowly add 1.00 g of hydroxypropyl methylcellulose, 2.0 g of PVP, 0.2 g of sodium dodecyl sulfate, and 6 g of NaCl in batches. Stir and disperse for 30 minutes until completely dissolved to obtain an aqueous mixed solution.

[0029] Step S2, preparation of oil phase mixed solution: Weigh 2.50 g liquid paraffin, 32.0 g divinylbenzene, 10 g ethylene glycol dimethacrylate, 1.00 g dimethyl azobisisobutyrate, and 25.00 g 2-ethylhexanoic acid in sequence and add them to a 250 mL beaker. Sonicate until completely dissolved to obtain oil phase mixed solution.

[0030] Step S3, suspension polymerization reaction: The oil phase mixture is added to the aqueous phase mixture and pre-dispersed by stirring at 300 rpm for 30 minutes. Then, the oil bath temperature is set to 70℃ and the reaction is carried out for 16 hours.

[0031] Step S4, post-processing: After the reaction is complete, the product is filtered and washed three times each with tetrahydrofuran and methanol, with each washing solvent being 100 mL. The washed product is then dried by spray drying and sieved using an ultrasonic vibrating sieve to complete the packing preparation.

[0032] <Example 2> Step S1, Preparation of aqueous mixed solution: Take a 500 mL three-necked flask and add 180 mL of deionized water. Turn on the stirrer and adjust the speed to 300 rpm. While stirring, slowly add 1.00 g hydroxypropyl methylcellulose, 2.0 g PVP, 0.2 g sodium dodecyl sulfate, and 6 g NaCl in batches and stir for 30 minutes until completely dissolved.

[0033] Step S2, preparation of oil phase mixed solution: Weigh 2.50 g liquid paraffin, 32.0 g divinylbenzene, 10 g ethylene glycol dimethacrylate, 1.00 g dimethyl azobisisobutyrate, and 40.00 g 2-ethylhexanoic acid in sequence and add them to a 250 mL beaker and sonicate until completely dissolved.

[0034] Step S3, suspension polymerization reaction: The oil phase mixture is added to the aqueous phase mixture and pre-dispersed by stirring at 300 rpm for 30 minutes. Then, the oil bath temperature is set to 70℃ and the reaction is carried out for 16 hours.

[0035] Step S4, post-processing: After the reaction is complete, the product is filtered and washed three times each with tetrahydrofuran and methanol, with each washing solvent being 100 mL. The washed product is then dried by spray drying and sieved using an ultrasonic vibrating sieve to complete the packing preparation.

[0036] <Example 3> Step S1, Preparation of aqueous mixed solution: Take a 500 mL three-necked flask and add 180 mL of deionized water. Turn on the stirrer and adjust the speed to 300 rpm. While stirring, slowly add 1.00 g hydroxypropyl methylcellulose, 2.0 g PVP, 0.2 g sodium dodecyl sulfate, and 6 g NaCl in batches and stir for 30 minutes until completely dissolved.

[0037] Step S2, preparation of oil phase mixed solution: Weigh 5 g dodecane, 32.0 g divinylbenzene, 10 g ethylene glycol dimethacrylate, 1.0 g dimethyl azobisisobutyrate, and 25.00 g 2-ethylhexanoic acid in sequence and add them to a 250 mL beaker and sonicate until completely dissolved.

[0038] Step S3, suspension polymerization reaction: The oil phase mixture is added to the aqueous phase mixture and pre-dispersed by stirring at 300 rpm for 30 minutes. Then, the oil bath temperature is set to 70℃ and the reaction is carried out for 16 hours.

[0039] Step S4, post-processing: After the reaction is complete, the product is filtered and washed three times each with tetrahydrofuran and methanol, with each washing solvent being 100 mL. The washed product is then dried by spray drying and sieved using an ultrasonic vibrating sieve to complete the packing preparation.

[0040] <Example 4> Step S1, Preparation of aqueous mixed solution: Take a 500 mL three-necked flask and add 180 mL of deionized water. Turn on the stirrer and adjust the speed to 300 rpm. While stirring, slowly add 1.50 g of hydroxypropyl methylcellulose, 2.0 g of PVP, 0.2 g of sodium dodecyl sulfate and 6 g of NaCl in batches and stir for 30 minutes until completely dissolved.

[0041] Step S2, preparation of oil phase mixed solution: Weigh 2.50 g liquid paraffin, 32.0 g divinylbenzene, 10 g ethylene glycol dimethacrylate, 1.00 g dimethyl azobisisobutyrate, and 25.00 g 2-ethylhexanoic acid in sequence and add them to a 250 mL beaker and sonicate until completely dissolved.

[0042] Step S3, suspension polymerization reaction: The oil phase mixture is added to the aqueous phase mixture and pre-dispersed by stirring at 300 rpm for 30 minutes. Then, the oil bath temperature is set to 70℃ and the reaction is carried out for 16 hours.

[0043] Step S4, post-processing: After the reaction is complete, the product is filtered and washed three times each with tetrahydrofuran and methanol, with each washing solvent being 100 mL. The washed product is then dried by spray drying and sieved using an ultrasonic vibrating sieve to complete the packing preparation.

[0044] <Example 5> Step S1, Preparation of aqueous mixed solution: Take a 500 mL three-necked flask and add 180 mL of deionized water. Turn on the stirrer and adjust the speed to 300 rpm. While stirring, slowly add 1.00 g hydroxypropyl methylcellulose, 2.0 g PVP, 0.2 g sodium dodecyl sulfate, and 6 g NaCl in batches and stir for 30 minutes until completely dissolved.

[0045] Step S2, preparation of oil phase mixed solution: Weigh 2.50 g liquid paraffin, 32.0 g divinylbenzene, 10 g ethylene glycol dimethacrylate, 1.00 g dimethyl azobisisobutyrate, and 25.00 g 2-ethylhexanoic acid in sequence and add them to a 250 mL beaker and sonicate until completely dissolved.

[0046] Step S3, suspension polymerization reaction: The oil phase mixture is added to the aqueous phase mixture and pre-dispersed by stirring at 400 rpm for 30 minutes. Then, the oil bath temperature is set to 70℃ and the reaction is carried out for 16 hours.

[0047] Step S4, post-processing: After the reaction is complete, the product is filtered and washed three times each with tetrahydrofuran and methanol, with each washing solvent being 100 mL. The washed product is then dried by spray drying and sieved using an ultrasonic vibrating sieve to complete the packing preparation.

[0048] <Comparative Example 1> Step S1, Preparation of aqueous mixed solution: Take a 500 mL three-necked flask and add 180 mL of deionized water. Turn on the stirrer and adjust the speed to 300 rpm. While stirring, slowly add 1.00 g hydroxypropyl methylcellulose, 2.0 g PVP, 0.5 g sodium dodecyl sulfate, and 6 g NaCl in batches and stir for 30 minutes until completely dissolved.

[0049] Step S2, preparation of oil phase mixed solution: Weigh 2.50 g liquid paraffin, 32.0 g divinylbenzene, 10 g ethylene glycol dimethacrylate, 1.00 g dimethyl azobisisobutyrate, and 25.00 g 2-ethylhexanoic acid in sequence and add them to a 250 mL beaker and sonicate until completely dissolved.

[0050] Step S3, suspension polymerization reaction: The oil phase mixture is added to the aqueous phase mixture and pre-dispersed by stirring at 300 rpm for 30 minutes. Then, the oil bath temperature is set to 70℃ and the reaction is carried out for 16 hours.

[0051] Step S4, post-processing: After the reaction is complete, the product is filtered and washed three times each with tetrahydrofuran and methanol, with each washing solvent being 100 mL. The washed product is then dried by spray drying and sieved using an ultrasonic vibrating sieve to complete the packing preparation.

[0052] <Comparative Example 2> Step S1, Preparation of aqueous mixed solution: Take a 500 mL three-necked flask and add 180 mL of deionized water. Turn on the stirrer and adjust the speed to 300 rpm. While stirring, slowly add 1.00 g hydroxypropyl methylcellulose, 2.0 g PVP, 0.2 g sodium dodecyl sulfate, and 6 g NaCl in batches and stir for 30 minutes until completely dissolved.

[0053] Step S2, preparation of oil phase mixed solution: Weigh 2.50 g liquid paraffin, 20.0 g divinylbenzene, 20.0 g ethylene glycol dimethacrylate, 1.00 g dimethyl azobisisobutyrate, and 25.00 g 2-ethylhexanoic acid in sequence and add them to a 250 mL beaker and sonicate until completely dissolved.

[0054] Step S3, suspension polymerization reaction: The oil phase mixture is added to the aqueous phase mixture and pre-dispersed by stirring at 300 rpm for 30 minutes. Then, the oil bath temperature is set to 70℃ and the reaction is carried out for 16 hours.

[0055] Step S4, post-processing: After the reaction is complete, the product is filtered and washed three times each with tetrahydrofuran and methanol, with each washing solvent being 100 mL. The washed product is then dried by spray drying and sieved using an ultrasonic vibrating sieve to complete the packing preparation.

[0056] <Test Example 1> The microspheres prepared in Example 1 were scanned using a Hitachi Regulus 8100 scanning electron microscope. The results are shown in the figure. Figure 1 .Depend on Figure 1 It can be seen that the microspheres prepared in Example 1 have good spherical shape and smooth surface, indicating that the pore size of the microsphere surface is small.

[0057] The microspheres prepared in the examples and comparative examples were tested using a Bettersize 2600 laser particle size analyzer and a Micromeritics ASAP 2460 BET (specific surface area and porosity analysis) testing device. The particle size and BET data are shown in Table 1 below; and the particle size distribution diagram of the microspheres prepared in Example 1 is also shown. Figure 2 ) and BET aperture distribution map ( Figure 3 (represented by )

[0058] Table 1. Particle size and BET test data of the fillers prepared in the examples and comparative examples

[0059] As shown in Table 1, by comparing Examples 1, 2, and 3, we can conclude that changing the type or proportion of the pore-forming agent can adjust the average pore size and specific surface area of ​​the prepared microspheres. Comparing Examples 1, 4, and 5, it can be concluded that changing the amount of dispersant and the stirring speed can adjust the particle size of the prepared microspheres. Comparative Example 1 shows that when the emulsifier dosage exceeds 0.05wt%~0.15wt% of the water mass, the microsphere particle size is too small. In Comparative Example 2, when the monomer to crosslinking agent ratio exceeds 1:(2~4), the pore size is too large and the specific surface area is too small. The above examples and comparative examples demonstrate that the particle size, pore size, and specific surface area of ​​microspheres can be adjusted within a certain range.

[0060] <Application Example 1> The prepared microspheres were packed into a 1m × 3.2mm packed column, and the separation effect of methane, ethane-ethylene, acetylene, and propane mixtures was tested using a GC9790 Plus gas chromatograph. The results are shown in the figure. Figures 4-6 The chromatographic parameters are as follows: high-purity N2 is used as the carrier gas, the carrier gas flow rate is 20 mL / min, the split ratio is 50:1, the temperature program is: 40℃, hold for 2 minutes, increase to 70℃ at 5℃ / min, hold for 5 minutes, and the injection port and detector temperatures are 120℃ and 150℃, respectively.

[0061] Appendix Figure 4 Appendix Figure 5 Appendix Figure 6 The chromatographic column microspheres packed were prepared in Examples 1, 5, and Comparative Example 1, respectively. As shown in the accompanying figures, the microspheres prepared in Examples 1 and 5, after being packed into the chromatographic column, can effectively separate methane, ethane-ethylene, acetylene, and propane mixtures, with excellent separation results. However, the microspheres prepared in Comparative Example 1, after being packed into the chromatographic column, show poor separation results for methane, ethane-ethylene, acetylene, and propane mixtures. This comparison demonstrates that the microspheres prepared in Examples 1 and 5 enable the effective separation of low-carbon hydrocarbon gases on the chromatographic stationary phase. The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing porous polymer microspheres, characterized in that, Includes the following steps: Step S1, Preparation of aqueous mixed solution: Add water to a container, and slowly add dispersant, stabilizer and emulsifier while stirring, and continue to disperse to form a uniform solution to obtain aqueous mixed solution; Step S2, Preparation of oil phase mixed solution: Mix the monomer, crosslinking agent, pore-forming agent and initiator and add them to another container, and sonicate to dissolve until homogeneous to obtain oil phase mixed solution; Step S3, suspension polymerization reaction: The oil phase mixed solution is added to the aqueous phase mixed solution, pre-dispersed, and then heated to 65℃~75℃ for complete reaction to obtain the reaction solution; Step S4, Post-processing: The reaction solution is filtered, washed, dried, and sieved to obtain porous polymer microspheres of the target particle size; wherein, In step S1, the dispersant is any one or more of hydroxypropyl methylcellulose, carboxymethyl cellulose, hydroxyethyl cellulose, polyvinyl alcohol, or polyvinylpyrrolidone, and the amount used is 1.0 wt% to 2.0 wt% of the mass of the water. In step S1, the stabilizer is any one or more of sodium sulfate and sodium chloride, and the dosage is 2.0 wt% to 4.5 wt% of the water mass. In step S1, the emulsifier is any one or more of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, or sodium bis(dodecylphenyl) ether disulfonate, and the amount used is 0.05 wt% to 0.15 wt% of the water mass. In step S2, the monomer is ethylene glycol dimethacrylate, and the crosslinking agent is divinylbenzene, with a mass ratio of 1:(2~4). In step S2, the pore-forming agent is any one or two of toluene, cyclohexanol, dodecane, n-heptane, liquid paraffin, or 2-ethylhexanoic acid, and the amount used is 60wt%~150wt% of the total mass of the monomer and crosslinking agent. In step S2, the initiator is any one of azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide or dimethyl azobisisobutyrate, and the amount used is 2wt% to 5wt% of the total mass of monomer and crosslinking agent.

2. The method for preparing porous polymer microspheres as described in claim 1, characterized in that, In step S1, the water is deionized water.

3. The method for preparing porous polymer microspheres as described in claim 1, characterized in that, In step S1, the dispersant is hydroxypropyl methylcellulose and polyvinylpyrrolidone in a mass ratio of 1:2 or 1.5:

2.

4. The method for preparing porous polymer microspheres as described in claim 1, characterized in that, The stabilizer is sodium chloride, the mass of the water is 180g, and the mass of the sodium chloride is 6g; the emulsifier is sodium dodecyl sulfate, and the initiator is azobisisobutyronitrile.

5. The method for preparing porous polymer microspheres as described in claim 1, characterized in that, The water has a mass of 180g, the monomer ethylene glycol dimethacrylate has a mass of 10g, and the crosslinking agent divinylbenzene has a mass of 32g.

6. The method for preparing porous polymer microspheres as described in claim 5, characterized in that, The pore-forming agent is liquid paraffin and 2-ethylhexanoic acid in a mass ratio of 1:10; or dodecane and 2-ethylhexanoic acid in a mass ratio of 1:

5.

7. The method for preparing porous polymer microspheres as described in claim 1, characterized in that, In step S3, the mixture is pre-dispersed at 300 rpm for 30 minutes, and then heated to 65°C to 75°C for 12 to 20 hours. In step S4, the reaction solution is filtered, washed with tetrahydrofuran and methanol in sequence, dried by spray drying, and then sieved with an ultrasonic vibrating sieve to obtain porous polymer microspheres of the target particle size.

8. A porous polymer microsphere, characterized in that, The porous polymer microspheres are prepared by the method described in any one of claims 1 to 7.

9. The porous polymer microspheres as described in claim 8, characterized in that, The porous polymer microspheres have a specific surface area ≥350 m² / g; an average pore size of 5 nm to 12 nm; and an average particle size of 100 μm to 200 μm.

10. The application of the porous polymer microspheres as described in claim 8 in gas chromatography separation.

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