阅读说明：本技术 一种均一粒径磁性微球的制备方法 (Preparation method of magnetic microspheres with uniform particle size ) 是由 仲玉 任连兵 于 2020-12-15 设计创作，主要内容包括：本发明涉及高分子材料技术领域,提供一种均一粒径磁性微球的制备方法,包括以下步骤：(1)磁流体制备；(2)烯烃化磁流体后修饰；(3)溶胀；(4)水相的制备；(5)磁性微球的制备。其解决了现有技术磁流体磁性易流失,粒径分布宽的问题。(The invention relates to the technical field of high polymer materials, and provides a preparation method of magnetic microspheres with uniform particle size, which comprises the following steps: (1) preparing magnetic fluid; (2) performing magnetic fluid chemical modification by olefin; (3) swelling; (4) preparing an aqueous phase; (5) and (4) preparing magnetic microspheres. The problems that the magnetism of the magnetic fluid is easy to lose and the particle size distribution is wide in the prior art are solved.)

1. A preparation method of magnetic microspheres with uniform particle size is characterized by comprising the following steps: the method comprises the following steps:

(1) preparing magnetic fluid:

adding soluble ferric ion salt into ethylene glycol to prepare a solution of 0.01-0.5 mol/L; then adding inorganic salt, stirring and mixing uniformly, transferring the mixture into a hydrothermal reaction kettle, and reacting for 8-24 hours at the temperature of 200-300 ℃; after the reaction is finished, cooling to room temperature, performing centrifugal separation, washing and drying to obtain ferroferric oxide magnetic fluid with hydroxyl on the surface;

(2) olefin magnetic fluid post-modification:

adding the ferroferric oxide magnetic fluid obtained in the step (1) into a mixed solvent composed of dimethyl sulfoxide and deionized water, stirring until the ferroferric oxide magnetic fluid is uniformly dispersed, adding a vinyl epoxy compound, adjusting the pH value of the system to 8-12 by using an acidity regulator, and reacting for 2-24 hours at 50-80 ℃, wherein the mass ratio of the ferroferric oxide magnetic fluid to the vinyl epoxy compound is 0.02-1: 1; after the reaction is finished, centrifugally separating, washing and drying to obtain the alkene-alkylated modified ferroferric oxide magnetic fluid;

(3) swelling:

mixing the olefine hydrocarbon modified ferroferric oxide magnetic fluid obtained in the step (2) with a polymerizable monomer, a cross-linking agent, an emulsifier and deionized water, and homogenizing and emulsifying for 2-15 min to obtain an emulsion I; mixing an initiator, an emulsifier and deionized water, and homogenizing and emulsifying for 2-15 min to obtain emulsion II;

adding the emulsion I into the seed solution, controlling the system temperature at 10-70 ℃, and stirring for swelling for 30-200 min; then adding the emulsion II, and continuing swelling for 20-80 min to obtain an oil phase swelling matter; the mass ratio of the emulsion I to the emulsion II to the seed solution is 10-64: 1: 1-3;

(4) preparation of the aqueous phase: adding a stabilizer into deionized water, heating to 50-80 ℃, and obtaining a water phase with the concentration of 1-3 g/L after the stabilizer is completely dissolved;

(5) preparing magnetic microspheres:

adding the water phase obtained in the step (4) into the seed solution obtained in the step (3), wherein the mass ratio of the water phase to the oil phase swelling matter is 5-10: 1, heating to 60-90 ℃, and stirring for reaction for 6-24 hours; after the reaction is finished, cooling to room temperature, carrying out suction filtration, washing and drying to obtain the magnetic microspheres with uniform particle size.

2. The method for preparing magnetic microspheres with uniform particle size according to claim 1, wherein the method comprises the following steps: the vinyl epoxy compound is M1 or M2, and the structure of M1 is as follows:wherein n is 2 ~ 6, and M2 structure is:

3. the method for preparing magnetic microspheres with uniform particle size according to claim 1, wherein the method comprises the following steps: the ferric ion salt is any one of ferric chloride, ferric nitrate and ferric acetate, and the inorganic salt is any one of ferrous chloride, ferrous nitrate, zinc chloride, magnesium chloride and copper chloride.

4. The method for preparing magnetic microspheres with uniform particle size according to claim 1, wherein the method comprises the following steps: the molar ratio of the ferric ion salt to the inorganic salt is 0.01-1: 2.

5. The method for preparing magnetic microspheres with uniform particle size according to claim 1, wherein the method comprises the following steps: the stabilizer is one or more of polyvinyl alcohol, polyethylene glycol, polyvinylpyrrolidone, hydroxymethyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, beta-cyclodextrin, beta-methyl cyclodextrin and hydroxyapatite.

6. The method for preparing magnetic microspheres with uniform particle size according to claim 1, wherein the method comprises the following steps: the polymerizable monomer is any one or a mixture of more than two of styrene, methyl styrene, ethyl styrene, chloromethyl styrene, methyl acrylate, propyl acrylate, butyl acrylate, methyl methacrylate, pentaerythritol methacrylate, glycidyl acrylate, butyl methacrylate, acrylamide, hydroxyethyl methacrylate, hydroxyethyl acrylate and methacrylamide.

7. The method for preparing magnetic microspheres with uniform particle size according to claim 1, wherein the method comprises the following steps: the cross-linking agent is any one or a mixture of more than two of divinylbenzene, ethylene glycol dimethacrylate, triethylene glycol, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, 1, 3-butanediol dimethacrylate, 1, 4-butanediol dimethacrylate, hexamethylene bismethacrylamide, divinylphenylmethane, glyceryl trimethacrylate and methylene acrylamide.

8. The method for preparing magnetic microspheres with uniform particle size according to claim 1, wherein the method comprises the following steps: the emulsifier is one or a mixture of ionic emulsifier and non-ionic emulsifier in any ratio.

9. The method for preparing magnetic microspheres with uniform particle size according to claim 1, wherein the method comprises the following steps: the initiator is any one or a mixture of more than two of benzoyl peroxide, azobisisobutyronitrile, dimethyl azobisisobutyrate and azobisisobutylamidine.

10. The method for preparing magnetic microspheres with uniform particle size according to claim 1, wherein the method comprises the following steps: the mass ratio of the ferroferric oxide magnetic fluid, the polymerizable monomer, the cross-linking agent, the emulsifier and the deionized water in the emulsion I is 0.5-4: 2-4: 0.2-4: 0.05-0.5: 10-20; the mass ratio of the initiator to the emulsifier to the deionized water in the emulsion II is 0.5-2: 0.05-0.5: 5-10.

Technical Field

The invention relates to the technical field of high polymer materials, in particular to a preparation method of magnetic microspheres with uniform particle size.

Background

As a novel functional material, magnetic microspheres have been widely used in the fields of bioseparation, gene detection, magnetic hyperthermia, in vitro diagnosis, in vivo imaging, and the like, due to their properties of operability (superparamagnetic property), modifiability (surface facilitates functional modification), convenient labeling, and non-toxicity. With the further development of the magnetic microspheres in the application field, higher and higher requirements are put forward on the structure, performance and functionalization of the magnetic microspheres.

At present, the preparation methods of the magnetic microspheres mainly comprise a monomer polymerization method, an in-situ synthesis method, an embedding method and the like. The monomer polymerization method is to add the magnetic fluid into a high molecular monomer and initiate copolymerization or polycondensation reaction by an initiator so as to form a layer of polymer on the surface of the magnetic fluid. It is reported in the literature (Xu ZZ, Xia A, Wang C, et al. Synthesis of raspberry-like magnetic polystyrene microspheres [ J ]. Materials Chemistry and Physics,2007,107(2):494 and 499.) that magnetofluid ferroferric oxide subjected to oleophilic treatment, oleophilic monomer and initiator form an oil phase dispersed in an aqueous phase and polymerized to obtain magnetic microspheres.

Norwegian scientists (F.K. Hansen, J.Ugelstad.particle size in polymerization. IV.particle size in monomer dispersions. journal of Polymer science Part A: Polymer Chemistry,1979,17:3069-₂，-COOH，-SO₃H, and the like, then penetrating iron ions with a certain concentration to the surface of the microsphere, and raising the pH value of the system to enable the iron ions to form ferroferric oxide magnetic nanoparticles on the surface of the microsphere, thereby preparing the monodisperse magnetic microsphere.

In addition, chinese patent (CN201610329610.5) discloses a method for preparing magnetic polymer microspheres with a single particle size by coating magnetic ferroferric oxide magnetic fluid and oily polymerizable monomers with seed-swollen oleic acid and polymerizing.

The magnetic microspheres prepared by the above method have many disadvantages: for example, the magnetic microspheres prepared by the monomer polymerization method have wide particle size distribution and large magnetic phase difference among different magnetic microspheres. In-situ synthesis and Chinese patent (CN201610329610.5) disclose a method for preparing single-particle-size magnetic polymer microspheres, but swollen magnetic fluid is easy to lose, and the performance of the magnetic microspheres is affected. Therefore, the search for a magnetic microsphere with a single particle size, which is not easy to lose the magnetism of the magnetic fluid, is a key problem to be solved urgently.

Disclosure of Invention

Therefore, aiming at the content, the invention provides a preparation method of magnetic microspheres with uniform particle size, which solves the problems of easy loss of magnetism and wide particle size distribution of magnetic fluid in the prior art.

In order to achieve the purpose, the invention is realized by the following technical scheme:

a preparation method of magnetic microspheres with uniform particle size comprises the following steps:

(1) preparing magnetic fluid:

adding soluble ferric ion salt into ethylene glycol to prepare a solution of 0.01-0.5 mol/L; then adding inorganic salt, stirring and mixing uniformly, transferring the mixture into a hydrothermal reaction kettle, and reacting for 8-24 hours at the temperature of 200-300 ℃; after the reaction is finished, cooling to room temperature, performing centrifugal separation, washing and drying to obtain ferroferric oxide magnetic fluid with hydroxyl on the surface;

(2) olefin magnetic fluid post-modification:

adding the ferroferric oxide magnetic fluid obtained in the step (1) into a mixed solvent composed of dimethyl sulfoxide and deionized water, stirring until the ferroferric oxide magnetic fluid is uniformly dispersed, adding a vinyl epoxy compound, adjusting the pH value of the system to 8-12 by using an acidity regulator, and reacting for 2-24 hours at 50-80 ℃, wherein the mass ratio of the ferroferric oxide magnetic fluid to the vinyl epoxy compound is 0.02-1: 1; after the reaction is finished, centrifugally separating, washing and drying to obtain the alkene-alkylated modified ferroferric oxide magnetic fluid;

(3) swelling:

mixing the olefine hydrocarbon modified ferroferric oxide magnetic fluid obtained in the step (2) with a polymerizable monomer, a cross-linking agent, an emulsifier and deionized water, and homogenizing and emulsifying for 2-15 min to obtain an emulsion I; mixing an initiator, an emulsifier and deionized water, and homogenizing and emulsifying for 2-15 min to obtain emulsion II;

adding the emulsion I into the seed solution, controlling the system temperature at 10-70 ℃, and stirring for swelling for 30-200 min; then adding an emulsion II, and continuing swelling for 20-80 min to obtain an oil phase swelling substance, wherein the mass ratio of the emulsion I to the emulsion II to the seed solution is 10-64: 1: 1-3;

(4) preparation of the aqueous phase: adding a stabilizer into deionized water, heating to 50-80 ℃, and obtaining a water phase with the concentration of 1-3 g/L after the stabilizer is completely dissolved;

(5) preparing magnetic microspheres:

adding the water phase obtained in the step (4) into the oil phase swelling matter obtained in the step (3), wherein the mass ratio of the water phase to the oil phase swelling matter is 5-10: 1, heating to 60-90 ℃, and stirring for reaction for 6-24 hours; after the reaction is finished, cooling to room temperature, carrying out suction filtration, washing and drying to obtain the magnetic microspheres with uniform particle size.

The further improvement is that: the vinyl epoxy compound is M1 or M2, and the structure of M1 is as follows:wherein n is 2 ~ 6, and M2 structure is:

the further improvement is that: the ferric ion salt is any one of ferric chloride, ferric nitrate and ferric acetate, and the inorganic salt is any one of ferrous chloride, ferrous nitrate, zinc chloride, magnesium chloride and copper chloride.

The further improvement is that: the molar ratio of the ferric ion salt to the inorganic salt is 0.01-1: 2.

The further improvement is that: the stabilizer is one or more of polyvinyl alcohol, polyethylene glycol, polyvinylpyrrolidone, hydroxymethyl cellulose, hydroxypropyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, beta-cyclodextrin, beta-methyl cyclodextrin and hydroxyapatite.

The further improvement is that: the polymerizable monomer is any one or a mixture of more than two of styrene, methyl styrene, ethyl styrene, chloromethyl styrene, methyl acrylate, propyl acrylate, butyl acrylate, methyl methacrylate, pentaerythritol methacrylate, glycidyl acrylate, butyl methacrylate, acrylamide, hydroxyethyl methacrylate, hydroxyethyl acrylate and methacrylamide.

The further improvement is that: the cross-linking agent is any one or a mixture of more than two of divinylbenzene, ethylene glycol dimethacrylate, triethylene glycol, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, 1, 3-butanediol dimethacrylate, 1, 4-butanediol dimethacrylate, hexamethylene bismethacrylamide, divinylphenylmethane, glyceryl trimethacrylate and methylene acrylamide.

The further improvement is that: the emulsifier is one or a mixture of ionic emulsifier and non-ionic emulsifier in any ratio. The ionic emulsifier is alkylbenzene sulfonate, alkyl succinate sulfonate or alkyl diphenyl ether sulfonate. The non-ionic emulsifier is alkylphenol polyoxyethylene, benzyl phenol polyoxyethylene, phenethyl phenol polyoxyethylene, fatty alcohol polyoxyethylene or fatty amine polyoxyethylene.

The further improvement is that: the initiator is any one or a mixture of more than two of benzoyl peroxide, azobisisobutyronitrile, dimethyl azobisisobutyrate and azobisisobutylamidine.

The further improvement is that: the mass ratio of the ferroferric oxide magnetic fluid, the polymerizable monomer, the cross-linking agent, the emulsifier and the deionized water in the emulsion I is 0.5-4: 2-4: 0.2-4: 0.05-0.5: 10-20; the mass ratio of the initiator to the emulsifier to the deionized water in the emulsion II is 0.5-2: 0.05-0.5: 5-10.

By adopting the technical scheme, the invention has the beneficial effects that:

the invention prepares a magnetic microsphere with uniform particle size, firstly synthesizing magnetic fluid with a large amount of hydroxyl on the surface, secondly introducing hydrophobic oleophilic polymerizable olefin into the surface of the magnetic fluid by a post-modification method, increasing the intermiscibility of the magnetic fluid and polymerizable monomers, and initiating the polymerization of the olefin on the surface of the magnetic fluid and the polymerizable monomers by an initiator to ensure that the magnetic fluid is bonded on the internal skeleton of the microsphere through a chemical bond, thereby ensuring that the magnetic fluid in the magnetic microsphere is not leaked and the magnetism is not easy to lose. In addition, the magnetic microsphere synthesized by the method also has the advantages of controllable particle size, stable chemical property and the like, and has potential application value in the aspects of biological medicine and in-vitro diagnosis.

Drawings

FIG. 1 is a schematic diagram of the principle of post-modification of an olefin magnetic fluid in an embodiment of the present invention.

Detailed Description

The following detailed description will be provided for the embodiments of the present invention with reference to specific embodiments, so that how to apply the technical means to solve the technical problems and achieve the technical effects can be fully understood and implemented.

Unless otherwise indicated, the techniques employed in the examples are conventional and well known to those skilled in the art, and the reagents and products employed are also commercially available.

The seed solution is polystyrene seed solution and is prepared by the following steps:

160mL of ethanol and 20mL of ultrapure water are weighed and added into a 500mL round-bottom flask, a reflux condenser tube, mechanical stirring, a nitrogen ventilating duct and a thermometer are arranged on a reaction bottle, 1.5g of dispersant PVP is added, stirring and mixing are carried out uniformly, nitrogen is introduced into the flask, and the system is heated to 60 ℃; weighing 1.0g of dodecanethiol and 0.14g of azobisisobutyronitrile, dissolving in 20g of styrene, adding into the reaction flask, keeping the temperature for reaction for 20 hours to obtain a low-molecular-weight polystyrene seed solution, cleaning, and testing the molecular weight Mn of the seed to be 3284 and the particle size to be 0.8 mu m.

Weighing 2.5g of the prepared low-molecular-weight polystyrene seed solution into a 250mL round-bottom flask; weighing 0.11g of azobisisobutyronitrile, 30g of styrene, 0.4g of dodecanethiol, 0.1g of SDS and 20mL of ultrapure water into a 100mL beaker, emulsifying to obtain an emulsion with the particle size of about 10 microns, adding the emulsion into the flask, heating to 60 ℃, keeping the temperature for reaction for 3 hours, adding 0.5g of PEG4000/40g of ultrapure water solution, reacting for 20 hours at 80 ℃ to obtain a homogeneous polystyrene seed solution, and washing to be clean, testing the molecular weight Mn of the seed to be 10448 and the particle size to be 1.5 microns.

Example one

A preparation method of magnetic microspheres with uniform particle size comprises the following steps:

(1) preparing magnetic fluid:

adding ferric chloride into ethylene glycol to prepare a solution with the concentration of 0.01 mol/L; then adding ferrous chloride, wherein the molar ratio of the ferric chloride to the ferrous chloride is 0.1:2, stirring and mixing uniformly, transferring to a hydrothermal reaction kettle, and reacting for 8 hours at the temperature of 200 ℃; after the reaction is finished, cooling to room temperature, performing centrifugal separation, washing and drying to obtain ferroferric oxide magnetic fluid with hydroxyl on the surface;

(2) olefin magnetic fluid post-modification:

adding the ferroferric oxide magnetic fluid obtained in the step (1) into a mixed solvent composed of dimethyl sulfoxide and deionized water, stirring until the ferroferric oxide magnetic fluid is uniformly dispersed, adding allyl glycidyl ether, adjusting the pH value of the system to 8 by using sodium hydroxide, and reacting for 24 hours at 50 ℃, wherein the mass ratio of the ferroferric oxide magnetic fluid to the allyl glycidyl ether is 0.1: 1; after the reaction is finished, centrifugally separating, washing and drying to obtain the alkene-alkylated modified ferroferric oxide magnetic fluid;

(3) swelling:

mixing the olefine hydrocarbon modified ferroferric oxide magnetic fluid obtained in the step (2) with styrene, divinylbenzene, SDS and deionized water according to the mass ratio of 0.5:2:0.2:0.05:10, and homogenizing and emulsifying for 2min to obtain emulsion I; mixing azodiisobutyronitrile, SDS and deionized water according to the mass ratio of 10:1:100, and homogenizing and emulsifying for 2min to obtain emulsion II;

adding the emulsion I into the seed solution (particle size: 1.5 μm), controlling the temperature of the system at 60 deg.C, stirring and swelling for 100 min; then adding an emulsion II, and continuing swelling for 20min to obtain an oil phase swelling substance, wherein the mass ratio of the emulsion I to the emulsion II to the seed solution is 11:1: 1;

(4) preparation of the aqueous phase: adding polyvinyl alcohol into deionized water, heating to 50 ℃, and obtaining a water phase with the concentration of 2g/L after the stabilizer is completely dissolved;

(5) preparing magnetic microspheres:

adding the water phase obtained in the step (4) into the oil phase swelling matter obtained in the step (3), wherein the mass ratio of the water phase to the oil phase swelling matter is 5:1, heating to 80 ℃, and stirring for reacting for 18 hours; after the reaction is finished, the reaction solution is cooled to room temperature, and then is filtered, washed and dried, so that the magnetic microspheres with the particle size of 3.1 mu m are obtained, wherein C.V is 2.1%.

Example two

A preparation method of magnetic microspheres with uniform particle size comprises the following steps:

(1) preparing magnetic fluid:

adding ferric nitrate into ethylene glycol to prepare a solution of 0.25 mol/L; then adding ferrous nitrate, wherein the molar ratio of the ferric nitrate to the ferrous nitrate is 0.5:2, stirring and mixing uniformly, transferring to a hydrothermal reaction kettle, and reacting for 24 hours at the temperature of 250 ℃; after the reaction is finished, cooling to room temperature, performing centrifugal separation, washing and drying to obtain ferroferric oxide magnetic fluid with hydroxyl on the surface;

(2) olefin magnetic fluid post-modification:

adding the ferroferric oxide magnetic fluid obtained in the step (1) into a mixed solvent composed of dimethyl sulfoxide and deionized water, stirring until the ferroferric oxide magnetic fluid is uniformly dispersed, adding 1, 2-epoxy-5-hexene, wherein the mass ratio of the ferroferric oxide magnetic fluid to the 1, 2-epoxy-5-hexene is 0.5:1, adjusting the pH value of the system to 10 by using sodium hydroxide, and reacting for 12 hours at 60 ℃; after the reaction is finished, centrifugally separating, washing and drying to obtain the alkene-alkylated modified ferroferric oxide magnetic fluid;

(3) swelling:

mixing the olefine hydrocarbon modified ferroferric oxide magnetic fluid obtained in the step (2) with methyl methacrylate, pentaerythritol triacrylate, Tween-80 and deionized water according to the mass ratio of 2:3:2:0.25:15, and homogenizing and emulsifying for 8min to obtain emulsion I; mixing benzoyl peroxide, Tween-80 and deionized water according to the mass ratio of 1.2:0.25:8, and homogenizing and emulsifying for 8min to obtain emulsion II;

adding the emulsion I into the seed solution (particle diameter: 0.8 μm), controlling the system temperature at 20 deg.C, stirring and swelling for 200 min; then adding an emulsion II, and continuing swelling for 50min to obtain an oil phase swelling substance, wherein the mass ratio of the emulsion I to the emulsion II to the seed solution is 40:1: 2;

(4) preparation of the aqueous phase: adding polyvinylpyrrolidone into deionized water, heating to 60 ℃, and obtaining a water phase with the concentration of 1g/L after the stabilizer is completely dissolved;

(5) preparing magnetic microspheres:

adding the water phase obtained in the step (4) into the oil phase swelling matter obtained in the step (3), wherein the mass ratio of the water phase to the oil phase swelling matter is 8:1, heating to 60 ℃, and stirring for reaction for 24 hours; after the reaction is finished, cooling to room temperature, carrying out suction filtration, washing and drying to obtain the magnetic microspheres with the particle size of 2.4 mu m, wherein C.V is 2.7%.

EXAMPLE III

A preparation method of magnetic microspheres with uniform particle size comprises the following steps:

(1) preparing magnetic fluid:

adding ferric acetate into ethylene glycol to prepare a solution with the concentration of 0.5 mol/L; then adding zinc chloride, wherein the molar ratio of the ferric acetate to the zinc chloride is 1:2, stirring and mixing uniformly, transferring to a hydrothermal reaction kettle, and reacting for 16h at the temperature of 300 ℃; after the reaction is finished, cooling to room temperature, performing centrifugal separation, washing and drying to obtain ferroferric oxide magnetic fluid with hydroxyl on the surface;

(2) olefin magnetic fluid post-modification:

adding the ferroferric oxide magnetic fluid obtained in the step (1) into a mixed solvent composed of dimethyl sulfoxide and deionized water, stirring until the ferroferric oxide magnetic fluid is uniformly dispersed, adding 1, 2-epoxy-9-decene, wherein the mass ratio of the ferroferric oxide magnetic fluid to the 1, 2-epoxy-9-decene is 1:1, adjusting the pH value of the system to 12 by using sodium hydroxide, and reacting for 2 hours at 80 ℃; after the reaction is finished, centrifugally separating, washing and drying to obtain the alkene-alkylated modified ferroferric oxide magnetic fluid;

(3) swelling:

mixing the olefine hydrocarbon modified ferroferric oxide magnetic fluid obtained in the step (2) with glycidyl methacrylate, triethylene glycol dimethacrylate, SDS and deionized water according to the mass ratio of 8:8:8:1:40, and homogenizing and emulsifying for 15min to obtain emulsion I; mixing azodiisobutyl amidine, SDS and deionized water according to the mass ratio of 2:0.5:10, and homogenizing and emulsifying for 15min to obtain emulsion II;

adding the emulsion I into the seed solution (particle size: 0.8 μm), controlling the system temperature at 70 deg.C, stirring and swelling for 40 min; then adding an emulsion II, and continuing swelling for 80min to obtain an oil phase swelling substance, wherein the mass ratio of the emulsion I to the emulsion II to the seed solution is 64:1: 3;

(4) preparation of the aqueous phase: adding a stabilizer into deionized water, heating to 80 ℃, and obtaining a water phase with the concentration of 3g/L after the stabilizer is completely dissolved;

(5) preparing magnetic microspheres:

adding the water phase obtained in the step (4) into the oil phase swelling matter obtained in the step (3), wherein the mass ratio of the water phase to the oil phase swelling matter is 10:1, heating to 90 ℃, and stirring for reacting for 6 hours; after the reaction is finished, the reaction solution is cooled to room temperature, and then is filtered, washed and dried, so that the magnetic microspheres with the particle size of 1.6 mu m are obtained, wherein C.V is 2.7%.

The above description is only an embodiment utilizing the technical content of the present disclosure, and any modification and variation made by those skilled in the art can be covered by the claims of the present disclosure, and not limited to the embodiments disclosed.