A kind of magnetic Janus microsphere and preparation method thereof

Abstract

The present invention relates to a magnetic Janus microsphere and a preparation method thereof, belonging to the field of microsphere technology. The present invention uses a θ glass capillary as a generating device, and specifically comprises the following steps: (1) dissolving a water-soluble monomer, polyethylene glycol, an initiator, and a cross-linking agent in water to obtain a dispersed phase I; (2) dissolving pyrrole in a magnetic ionic liquid to obtain a dispersed phase II; (3) mixing soybean oil and paraffin to obtain a continuous phase; (4) connecting one hole of the θ glass capillary to the dispersed phase and the other hole to the continuous phase, mixing the dispersed phase and the continuous phase at a flow rate ratio of 1:10-40 to obtain magnetic Janus droplets; (5) subjecting the magnetic Janus droplets to a polymerization reaction to obtain the magnetic Janus microsphere. The magnetic Janus microspheres of the present invention are introduced into a uniform and stable magnetic ionic liquid, and monodisperse MIL-water Janus droplets are prepared in a one-step method by means of the θ glass capillary in the absence of a surfactant, and the droplets and microspheres can be precisely magnetically manipulated.

Description

Technical Field

[0001] The invention belongs to the technical field of microspheres, and in particular relates to magnetic Janus microspheres and a preparation method thereof. Background Art

[0002] The magnetic manipulation of droplets and their microspheres has attracted widespread attention due to its convenience. It has been used in separation, extraction, nucleic acid detection and purification of special cell types. Magnetic Janus droplets and their microspheres have attracted particular attention from researchers because of their dual nature and ability to be magnetically manipulated. Traditional methods for preparing Janus droplets often require multi-step emulsification with complex surfactants. Existing methods for preparing magnetic droplets or microspheres are to introduce magnetic particles into the droplets and disperse the magnetic particles in the aqueous or oily phase, which will cause many problems, such as particle sedimentation and flocculation. Additional surfactants are required to stabilize them and disperse the magnetic particles to prevent contamination of neighboring droplets. The second method is to first prepare porous microspheres and then embed the magnetic particles. This will also have certain problems, such as magnetic shedding and limited pore structure, which result in the magnetic particles not being evenly distributed throughout the microsphere.

[0003] Therefore, it is necessary to use true magnetic liquids in these droplets, rather than magnetic particles dispersed in a liquid. For example, magnetic ionic liquids (MILs) are salts composed of organic cations and inorganic anions that are liquid at or near room temperature. A common example is 1-methyl-3-butylimidazolium tetrachloride ferric salt [Bmim]FeCl4. Recently developed magnetic ionic liquids can adsorb on magnets, respond macroscopically to external magnetic fields, and exhibit a certain magnetization strength under the influence of an applied magnetic field. Although there are reports on the preparation of magnetic ionic liquids, the one-step preparation of MIL-water Janus droplets using microfluidic technology in the absence of surfactants, the manipulation of the droplets using magnetic fields, and the preparation of magnetic Janus microspheres by introducing monomers into magnetic Janus droplets remain unreported. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the problems in the prior art that the preparation process of magnetic Janus microspheres easily leads to sedimentation and flocculation of particles and requires additional surfactants to stabilize the magnetic particles.

[0005] To solve the above technical problems, the present invention provides a magnetic Janus microspheres and a preparation method thereof. A uniform magnetic ionic liquid is introduced, and MIL-water Janus droplets are prepared in a one-step process by microfluidic technology in the absence of a surfactant. The Janus droplets are then used as templates to prepare magnetic Janus microspheres.

[0006] The first object of the present invention is to provide a method for preparing magnetic Janus microspheres, using a θ glass capillary as a generating device, wherein the interior of the θ glass capillary is partitioned and the cross-section has a θ structure, the θ glass capillary is provided with two holes, the inner diameter of one end of the θ glass capillary is 40 μm-80 μm, and the inner diameter of the end forming the magnetic Janus droplet is 5 μm-10 μm. The preparation method comprises the following steps:

[0007] (1) Dissolving a water-soluble monomer, polyethylene glycol, an initiator, and a cross-linking agent in water to obtain a dispersed phase I;

[0008] (2) dissolving pyrrole in magnetic ionic liquid to obtain dispersed phase II;

[0009] (3) Mixing soybean oil and paraffin to obtain a continuous phase;

[0010] (4) connecting one hole of the θ glass capillary to the dispersed phases described in steps (1) and (2), and connecting the other hole to the continuous phase described in step (3), mixing the dispersed phase and the continuous phase at a flow rate ratio of 1:10-40 to obtain magnetic Janus droplets;

[0011] (5) The magnetic Janus droplets described in step (4) are polymerized to obtain the magnetic Janus microspheres.

[0012] In one embodiment of the present invention, in step (1), the water-soluble monomer is one or more of acrylamide, allyl dextran and acrylic acid.

[0013] In one embodiment of the present invention, in step (1), the molecular weight of the polyethylene glycol is 2000-10000.

[0014] In one embodiment of the present invention, in step (1), the initiator is one or more of ammonium persulfate, potassium persulfate and azobisisobutylamidine hydrochloride; and the cross-linking agent is N,N-methylenebisacrylamide.

[0015] In one embodiment of the present invention, in step (1), the mass ratio of the water-soluble monomer, polyethylene glycol, initiator and cross-linking agent is 4-15:5-30:0.1-1:0.3-1.2.

[0016] In one embodiment of the present invention, in step (2), the mass fraction of pyrrole is 15-40%.

[0017] In one embodiment of the present invention, in step (3), the volume ratio of soybean oil to paraffin is 1-6:1.

[0018] In one embodiment of the present invention, in step (4), the flow rate ratio of dispersed phase I to dispersed phase II is 1:4-5:1.

[0019] In one embodiment of the present invention, in step (5), the polymerization reaction temperature is 70-95°C.

[0020] In one embodiment of the present invention, in step (5), the inner diameter of the polytetrafluoroethylene extension tube used in the polymerization reaction is 40 μm-100 μm, and the effective heating tube length is 100 cm-200 cm.

[0021] The second object of the present invention is to provide magnetic Janus microspheres prepared by the preparation method.

[0022] The technical solution of the present invention has the following advantages over the prior art:

[0023] The magnetic Janus microspheres described in this invention systematically and comprehensively study the interfacial tension between three liquids: a magnetic ionic liquid, water, and a continuous phase, and delve into the mechanism by which Janus droplets form between magnetic ionic liquids and water. Binary Janus droplets are formed from two immiscible liquids. The formation of Janus droplets depends on the interfacial tension coefficients of the two liquids (A and B) and the continuous phase (C) in which the droplets reside. Therefore, the interfacial tension between the three liquids, magnetic ionic liquid (MIL), water, and soybean oil / liquid wax, as well as the spreading coefficient S of the magnetic ionic liquid, were first studied in principle. m Based on the analysis of the interfacial tension between the three, the formation mechanism of magnetic ionic liquid-water Janus droplets is explained by geometric structure. Figure 1 and equation γ 2 AB =γ 2 B +γ 2 A -2γ B γ A cos(π-α) and S B =γ A -(γ AB +γ B ). When the volume of MIL exceeds 20%, MIL is immiscible with water. The interfacial tension (γ mw ) is 15.51 mNm -1 , the interfacial tension between the continuous phase liquid paraffin / soybean oil and the aqueous phase (γ w ) is 29.01 mNm -1 , and the interfacial tension value (γ m ) is 17.02 mNm -1, and thus the spreading coefficient of the magnetic ionic liquid (S m ), calculated by the above equation (2), we can get S m =-3.52 mNm -1 , if S m <0, magnetic ionic liquid-water Janus droplets can be obtained, and the water phase is partially coated by the magnetic ionic liquid.

[0024] The magnetic Janus microspheres described in the present invention introduce a uniform and stable magnetic ionic liquid. In the absence of a surfactant, monodisperse MIL-water Janus droplets are prepared in a one-step method using a θ glass capillary tube. The droplets and microspheres can also be precisely magnetically manipulated. In addition, magnetic Janus porous microspheres can also be prepared by adding monomers to MIL and water using the Janus droplets as templates. Compared with the traditional multi-step emulsification and complex addition of surfactants for preparing multi-component emulsions, the present invention is simple to operate, highly reproducible, and has a controllable process. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0026] Figure 1 This is a geometric model diagram of the formation of MIL-water magnetic Janus droplets in the present invention.

[0027] Figure 2 The figure is a flow chart for the preparation of magnetic Janus microspheres of the present invention.

[0028] Figure 3 This is a microscope image of the preparation process of the magnetic Janus droplets of the present invention.

[0029] Figure 4 These are microscope images of magnetic manipulation of the magnetic Janus droplets of the present invention; wherein: ac is a microscope image of the magnetic Janus droplets changing their positions due to magnetic field manipulation; de is a microscope image of the magnetic Janus droplets forming necklaces due to magnetic field manipulation.

[0030] Figure 5 Characterization diagrams of the MIL-water magnetic Janus droplets and magnetic Janus microspheres of Example 1 of the present invention; wherein, a is a microscope image of the MIL-water magnetic Janus droplets; b is an electron microscope image of the magnetic Janus microspheres.

[0031] Figure 6Characterization diagrams of the MIL-water magnetic Janus droplets and magnetic Janus microspheres of Example 2 of the present invention; wherein, a is a microscope image of the MIL-water magnetic Janus droplets; b is an electron microscope image of the magnetic Janus microspheres.

[0032] Figure 7 Characterization diagrams of the MIL-water magnetic Janus droplets and magnetic Janus microspheres of Example 3 of the present invention; wherein, a is a microscope image of the MIL-water magnetic Janus droplets; b is an electron microscope image of the magnetic Janus microspheres.

[0033] Figure 8 Characterization diagrams of the MIL-water magnetic Janus droplets and magnetic Janus microspheres of Example 4 of the present invention; wherein, a is a microscope image of the MIL-water magnetic Janus droplets; b is an electron microscope image of the magnetic Janus microspheres.

[0034] Figure 9 Characterization diagrams of the MIL-water magnetic Janus droplets and magnetic Janus microspheres of Comparative Example 1 of the present invention; wherein, a is a microscope image of the MIL-water magnetic Janus droplets; b is an electron microscope image of the magnetic Janus microspheres.

[0035] Figure 10 Characterization diagrams of the MIL-water magnetic Janus droplets and magnetic Janus microspheres of Comparative Example 2 of the present invention; wherein, a is a microscope image of the MIL-water magnetic Janus droplets; b is an electron microscope image of the magnetic Janus microspheres.

[0036] Figure 11 This is a curve showing the change in concentration of magnetic Janus microspheres over time in Test Example 1 of the present invention.

[0037] Figure 12 This is a graph showing the regeneration performance test of the magnetic Janus microspheres adsorbed with MB in Test Example 1 of the present invention; a is the desorption curve of the microspheres adsorbed with MB under different pH conditions, and b is the FT-IR spectrum of the magnetic PAM microspheres after desorption. DETAILED DESCRIPTION

[0038] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0039] In this invention, unless otherwise specified, a theta glass capillary tube is used as the primary generating device. The theta glass capillary tube is internally partitioned, with a theta cross-section. It has two orifices, one with an inner diameter of 60 μm and the other with an inner diameter of 8 μm, where the magnetic Janus droplets are formed. The theta glass capillary tube is placed within a coaxial flow device fitted with a polytetrafluoroethylene (PTFE) hose. This device is connected to the coaxial flow device via three syringe pumps: two connected to one orifice of the theta glass tube to inject the dispersed phase, and one connected to the other orifice to inject the continuous phase. The continuous and dispersed phases are injected into the device at a specific flow rate ratio, forming magnetic Janus droplets.

[0040] In this invention, unless otherwise specified, the preparation method for a magnetic ionic liquid is as follows: 1-butyl-3-methylimidazolium chloride and an equimolar volume of anhydrous ferric chloride are slowly added to a three-necked flask in an N2-protected glove box. The complexation reaction occurs for approximately 24 hours, yielding a dark brown liquid. Deionized water is then added for extraction and separation to completely remove any unreacted reactants. The resulting brownish-yellow clear liquid is vacuum-dried at 80°C for 48 hours to yield 1-methyl-3-butylimidazolium ferric chloride magnetic ionic liquid, abbreviated as [Bmim]FeCl4. Example 1

[0041] Reference Figure 2 As shown, a magnetic Janus microsphere and a preparation method thereof specifically include the following steps:

[0042] Prepare 10 g of monomer synthesis solution of dispersed phase I as dispersed phase, in which the mass concentration of acrylamide (AM) is 8%, the mass concentration of polyethylene glycol (PEG-4000, Mw=4000) is 15%, the mass concentration of initiator ammonium persulfate (APS) is 0.5%, the mass concentration of cross-linking agent N,N-methylenebisacrylamide (MBAM) is 0.6%, the pyrrole content of dispersed phase II magnetic ionic liquid is 25%, and the volume ratio of soybean oil to liquid paraffin is 3:1 as the continuous phase. Figure 2 Connect the microfluidic device as shown. The flow rates of dispersed phase I, dispersed phase II, and continuous phase were adjusted to 0.5 mL / h, 0.5 mL / h, and 15 mL / h, respectively. Under shear force, the dispersed phase liquid was sheared into uniformly dispersed droplets. These droplets then flowed through a 100 cm long, 50 μm inner diameter polytetrafluoroethylene (PTFE) extension tube in a water bath (86°C) to initiate polymerization. A 75% DMF solution was used to collect the sample.

[0043] Figure 3 This is a microscope image of the preparation process of magnetic Janus droplets. It can be seen from the figure that after the magnetic ionic liquid and the water phase come into contact through one end of the θ glass capillary, magnetic ionic liquid-water Janus droplets are formed under the shear of the continuous phase.

[0044] Figure 4 Microscope image of magnetic manipulation of magnetic Janus droplets.

[0045] Figure 5 This is an electron microscope image of the MIL-water magnetic Janus droplet microscope and its microspheres. Example 2

[0046] A magnetic Janus microsphere and a preparation method thereof, specifically comprising the following steps:

[0047] Prepare 10 g of the monomer synthesis solution of dispersed phase I as the dispersed phase, in which the mass concentration of acrylamide (AM) is 4%, the mass concentration of polyethylene glycol (PEG-4000, Mw=4000) is 5%, the mass concentration of initiator ammonium persulfate (APS) is 0.1%, and the mass concentration of cross-linking agent N,N-methylenebisacrylamide (MBAM) is 0.3%. The pyrrole content in dispersed phase II magnetic ionic liquid is 15%, and the volume ratio of soybean oil to liquid paraffin is 1:1 as the continuous phase. According to Figure 1 Connect the microfluidic device as shown. The flow rates of dispersed phase I, dispersed phase II, and continuous phase were adjusted to 0.1 mL / h, 0.5 mL / h, and 5 mL / h, respectively. Under shear force, the dispersed phase liquid was sheared into uniformly dispersed droplets. These droplets then flowed through a 50 μm inner diameter, 130 cm long, polytetrafluoroethylene extension tube through a water bath (91°C) to initiate polymerization. A 70% DMF solution was used to collect the sample.

[0048] Figure 6 This is an electron microscope image of the MIL-water magnetic Janus droplet microscope and its microspheres. Example 3

[0049] A magnetic Janus microsphere and a preparation method thereof, specifically comprising the following steps:

[0050] Prepare 10 g of monomer synthesis solution of dispersed phase I as the dispersed phase, in which the mass concentration of acrylamide (AM) is 15%, the mass concentration of polyethylene glycol (PEG-4000, Mw=4000) is 30%, the mass concentration of initiator potassium persulfate is 0.8%, and the mass concentration of crosslinker N,N-methylenebisacrylamide (MBAM) is 0.4%. Dispersed phase II contains 25% pyrrole in the magnetic ionic liquid and a volume ratio of soybean oil to liquid paraffin of 6:1 as the continuous phase. Figure 1Connect the microfluidic device as shown. The flow rates of dispersed phase I, dispersed phase II, and continuous phase were adjusted to 0.8 mL / h, 0.2 mL / h, and 32 mL / h, respectively. Under shear force, the dispersed phase liquid was sheared into uniformly dispersed droplets. These droplets then flowed through a 150 cm long, 50 μm inner diameter polytetrafluoroethylene extension tube into a water bath (75°C) to initiate polymerization. An 85% DMF solution was used to collect the sample.

[0051] Figure 7 This is an electron microscope image of the MIL-water magnetic Janus droplet microscope and its microspheres. Example 4

[0052] A magnetic Janus microsphere and a preparation method thereof, specifically comprising the following steps:

[0053] Prepare 10 g of the monomer synthesis solution of dispersed phase I as the dispersed phase, wherein the mass concentration of allyl dextran is 12%, the mass concentration of polyethylene glycol (PEG-4000, Mw=4000) is 20%, the mass concentration of initiator potassium persulfate is 0.6%, the mass concentration of cross-linking agent N,N-methylenebisacrylamide (MBAM) is 1.0%, the pyrrole content of dispersed phase II magnetic ionic liquid is 25%, and the volume ratio of soybean oil to liquid paraffin is 6:1 as the continuous phase. Figure 1 Connect the microfluidic device as shown. The flow rates of dispersed phase I, dispersed phase II, and continuous phase were adjusted to 0.2 mL / h, 0.8 mL / h, and 32 mL / h, respectively. Under shear force, the dispersed phase liquid was sheared into uniformly dispersed droplets. These droplets then flowed through a 150 cm long, 50 μm inner diameter polytetrafluoroethylene (PTFE) extension tube into a water bath (75°C) to initiate polymerization. An 85% DMF solution was used to collect the sample.

[0054] Figure 8 This is the electron micrograph of the MIL-water magnetic Janus droplet microscope and its microspheres. After changing the water-soluble monomer to allyl dextran, the interfacial tension between the magnetic ionic liquid and the water phase did not change significantly, and the MIL-water magnetic Janus microspheres can still be prepared. Comparative Example 1

[0055] Prepare 10 g of the monomer synthesis solution of dispersed phase I as the dispersed phase, wherein the mass concentration of acrylamide (AM) is 8%, the mass concentration of polyethylene glycol (PEG-4000, Mw=4000) is 2%, the content of initiator ammonium persulfate (APS) is 0.5%, the mass concentration of cross-linking agent N,N-methylenebisacrylamide (MBAM) is 0.6%, the pyrrole content of dispersed phase II magnetic ionic liquid is 25%, and the volume ratio of soybean oil to liquid paraffin is 1:1 as the continuous phase. Figure 1Connect the microfluidic device as shown. The flow rates of dispersed phase I, dispersed phase II, and continuous phase were adjusted to 0.5 mL / h, 0.5 mL / h, and 9 mL / h, respectively. Under shear force, the dispersed phase liquid was sheared into uniformly dispersed droplets. These droplets then flowed through a 100 cm long, 50 μm inner diameter polytetrafluoroethylene extension tube through a water bath (86°C) to initiate polymerization. A 75% DMF solution was used to collect the sample.

[0056] Due to the low PEG content in the aqueous phase, the interfacial tension between the magnetic ionic liquid phase and the aqueous phase (γ mw ) is reduced, so that the spreading coefficient of the magnetic ionic liquid (S m )>0, thus forming droplets with a core-shell structure of magnetic ionic liquid and water, with the water phase completely encapsulated by the magnetic ionic liquid phase. Ultimately, after polymerization, microspheres with a core-shell structure were not formed, rather than Janus structures.

[0057] Figure 9 Microscope and electron microscope images of magnetic ionic liquid / water core-shell structure droplets formed by reducing the PEG content in the aqueous phase. The interfacial tension between the magnetic ionic liquid and the aqueous phase is reduced, resulting in the formation of core-shell structure droplets instead of Janus structure. Comparative Example 2

[0058] Prepare 10 g of the monomer synthesis solution of dispersed phase I as the dispersed phase, wherein the mass concentration of acrylamide (AM) and polyethylene glycol (PEG-4000, Mw=4000) is 7%, the content of initiator ammonium persulfate (APS) is 0.5%, the mass concentration of cross-linking agent N, N-methylenebisacrylamide (MBAM) is 0.6%, the pyrrole content of dispersed phase II magnetic ionic liquid is 13%, and the volume ratio of soybean oil to liquid paraffin is 1:1 as the continuous phase. Figure 1 Connect the microfluidic device as shown. The flow rates of dispersed phase I, dispersed phase II, and continuous phase were adjusted to 0.5 mL / h, 0.5 mL / hN, and 9 mL / h, respectively. Under shear force, the dispersed phase liquid was sheared into uniformly dispersed droplets. These droplets then flowed through a 100 cm long, 50 μm inner diameter polytetrafluoroethylene extension tube through a water bath (86°C) to initiate polymerization. A 75% DMF solution was used to collect the sample.

[0059] When the pyrrole content in the magnetic ionic liquid is lower than 15%, solidification is difficult to occur due to the low pyrrole content. After the microspheres are washed with DMF solvent, only half of the sphere remains and they are not magnetic.

[0060] like Figure 10 As shown in the figure, when the pyrrole content in the magnetic ionic liquid is low, the magnetic ionic liquid phase cannot aggregate and can only form a hemispherical electron microscope image. Because the pyrrole content is low, self-aggregation cannot occur in the magnetic ionic liquid phase.

[0061] Test Example 1

[0062] The adsorption performance of the magnetic Janus microspheres of Example 2 was tested. 50 mL of 10 mg / L and 60 mg / L methylene blue MB solutions were prepared, and 5 mg of magnetic Janus microspheres were added to each solution. The MB concentration curve over time was plotted as follows: Figure 11 As shown. Figure 11 It can be seen that the MB concentration decreased rapidly over time from 0 to 75 minutes, but after 75 minutes, the decrease in MB concentration slowed significantly. After 250 minutes, no MB could be detected in the solution using a UV-Vis spectrophotometer. To further verify the effectiveness of magnetic PAM microspheres in adsorbing MB, a colorimeter was used to measure the residual color of the MB solution after adsorption. The results showed that the residual color of the MB solution was 9° (meeting the color requirement of the domestic drinking water quality standard, GB T5750-2006, ≤15°).

[0063] The regeneration performance of the magnetic Janus microspheres adsorbed with MB was tested. Solvent desorption was used to desorb and regenerate the magnetic Janus microspheres adsorbed with MB. 5 mg of magnetic Janus microspheres saturated with MB were placed in 10 mL of 50% methanol solution with pH values ​​of 2, 6, and 10 for desorption. Figure 12 As shown in a, in a methanol solution with a pH of 2, 90% of MB was desorbed at t = 5 min. When t = 30 min, the desorption equilibrium was basically reached, and the desorption rate was basically 100%. To verify this, FT-IR experiments were performed on the desorbed microspheres, as shown in Figure 12 As shown in Figure b, 1 is MB and 2 is the desorbed magnetic PAM microspheres. No characteristic absorption peaks of MB were detected in the desorbed magnetic PAM microspheres. This indicates that 100% desorption of the magnetic microspheres was achieved in methanol solutions at a pH of 2. However, in methanol solutions at pH 6 and 10, 20% and 40% of MB remained after 24 h of desorption, respectively.

[0064] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for preparing magnetic Janus microspheres, characterized in that: A θ glass capillary is used as a generating device. The interior of the θ glass capillary is separated and the cross section is a θ structure. The θ glass capillary is provided with two holes. The inner diameter of one end of the θ glass capillary is 40 μm-80 μm, and the inner diameter of the end forming the magnetic Janus droplet is 5 μm-10 μm. The preparation method includes the following steps: (1) dissolving a water-soluble monomer, polyethylene glycol, an initiator, and a cross-linking agent in water to obtain a dispersed phase I; the water-soluble monomer is one or more of acrylamide, allyl dextran, and acrylic acid; the mass ratio of the water-soluble monomer, polyethylene glycol, initiator, and cross-linking agent is 4-15:5-30:0.1-1:0.3-1.2; (2) dissolving pyrrole in a magnetic ionic liquid to obtain a dispersed phase II; the mass fraction of the pyrrole is 15-40%; (3) mixing soybean oil and paraffin to obtain a continuous phase; (4) One of the holes of the θ glass capillary is connected to the dispersed phases described in steps (1) and (2), and the other hole is connected to the continuous phase described in step (3), and the dispersed phase and the continuous phase are mixed at a flow rate ratio of 1:10-40 to obtain magnetic Janus droplets; (5) The magnetic Janus droplets described in step (4) are polymerized to obtain the magnetic Janus microspheres.

2. The method for preparing magnetic Janus microspheres according to claim 1, wherein In step (1), the molecular weight of the polyethylene glycol is 2000-10000.

3. The method for preparing magnetic Janus microspheres according to claim 1, wherein In step (1), the initiator is one or more of ammonium persulfate, potassium persulfate and azobisisobutylamidine hydrochloride; and the cross-linking agent is N,N-methylenebisacrylamide.

4. The method for preparing magnetic Janus microspheres according to claim 1, wherein In step (3), the volume ratio of the soybean oil to the paraffin is 1-6:

1.

5. The method for preparing magnetic Janus microspheres according to claim 1, wherein In step (4), the flow rate ratio of dispersed phase I to dispersed phase II is 1:4-5:

1.

6. The method for preparing magnetic Janus microspheres according to claim 1, characterized in that: In step (5), the polymerization reaction temperature is 70-95°C.

7. Magnetic Janus microspheres prepared by the preparation method according to any one of claims 1 to 6.

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