CoFe2O4 / polymer magnetic composite microsphere and preparation method thereof

Abstract

The invention discloses a preparation method of CoFe2O4 / polymer magnetic composite microspheres, which comprises the following steps: dissolving octadecyltrichlorosilane in isopropanol at room temperature, dispersing CoFe2O4 powder in the solution, stirring and reacting for a certain time, centrifuging and precipitating, and drying to obtain hydrophobic CoFe2O4 powder; adding the hydrophobic CoFe2O4 powder, potassium persulfate, polyethylene glycol-400 and deionized water into normal octane at room temperature, mixing and stirring, and stirring and emulsifying at a high speed to obtain a water-in-oil Pickering emulsion; and finally, filling the water-in-oil emulsion into a closed container to carry out thermal polymerization reaction, and centrifuging, washing and drying after the reaction to obtain the magnetic composite microspheres. The preparation method disclosed by the invention is convenient to operate, high in balling rate, energy-saving and environment-friendly, and the prepared CoFe2O4 / polymer magnetic composite microspheres have the advantages of strong magnetism, large specific surface area, adjustable microsphere size and the like, and have wide application prospects in the fields of biology, medicine, environment, stealth and the like as magnetic carriers for preparing functional materials.

Description

Technical Field

[0001] The invention belongs to the technical field of magnetic composite materials, and particularly relates to CoFe2O4 / polymer magnetic composite microspheres and a preparation method thereof. Background Art

[0002] Magnetic polymer microspheres are a kind of functional composite materials that combine magnetic materials and polymer materials. They can be widely used in biomedicine, catalysis, sewage treatment and other fields. At present, there are many methods for preparing magnetic polymer composite microspheres, mainly embedding method, in-situ method, monomer polymerization method, interface deposition method and self-assembly method. However, most of the prepared microspheres are solid microspheres with high density and small specific surface area, resulting in poor performance and high cost, which seriously hinders their industrial application. The preparation of microspheres with porous structures can effectively increase their specific surface area, reduce density, increase surface permeability and other characteristics, thereby effectively improving the industrial application prospects of magnetic polymer composite microspheres.

[0003] Pickering emulsion uses small inorganic solid particles as emulsifiers to stabilize the emulsion. Compared with traditional emulsions, it has the advantages of lower toxicity, less harm to human health, easier handling, and less susceptible to external environmental factors such as temperature, pH value, electrolytes, etc., and has attracted widespread attention. Pickering emulsion polymerization is also widely used in the preparation of polymer composite microspheres. Since magnetic powders, such as Fe3O4 and CoFe2O4, have a much higher density than traditional SiO2, it is difficult to form a stable Pickering emulsion, and there are few literature reports on the preparation of porous magnetic polymer composite microspheres by the Pickering emulsion method. Summary of the invention

[0004] In view of the problems existing in the prior art, the present invention provides a method for preparing CoFe2O4 / polymer magnetic composite microspheres. The present invention uses alkylsilane-modified hydrophobic CoFe2O4 powder as a solid emulsifier, and prepares CoFe2O4 / polymer magnetic composite microspheres conveniently and quickly by in-situ polymerization of an oil-in-water Pickering emulsion.

[0005] The present invention is achieved through the following technical solutions: A method for preparing CoFe2O4 / polymer magnetic composite microspheres comprises the following steps: S1: Dissolve octadecyltrichlorosilane in isopropanol at room temperature, then disperse CoFe2O4 powder in the above solution by magnetic stirring, react for a certain period of time under stirring, centrifuge and precipitate, and vacuum dry to obtain hydrophobic CoFe2O4 powder; S2: adding the hydrophobic CoFe2O4 powder, potassium persulfate, polyethylene glycol-400 and deionized water into n-octane at room temperature, mixing and stirring, and emulsifying with high-speed stirring to obtain a water-in-oil Pickering emulsion; S3: The water-in-oil emulsion is placed in a sealed container and then placed in an oven to perform a thermal polymerization reaction. After the reaction is completed, the reaction solution is centrifuged and washed, and the obtained solid is dried under ventilation at room temperature to obtain magnetic composite microspheres.

[0006] A further improvement of the present invention is: In S1, the usage ratio of trichlorooctadecylsilane, CoFe2O4 powder and isopropanol is 0.3-0.6 g: 1 g: 30 mL.

[0007] Furthermore, in S1, the speed of the magnetic stirring is 400-600 rpm, and the time is 3-5 h; the speed of the centrifugal sedimentation is 7000-9000 rpm, and the time is 3-5 h; the temperature of the vacuum drying is 120-160° C., and the time is 3-5 h.

[0008] Furthermore, in S2, the feed ratio of the hydrophobic CoFe2O4 powder, potassium persulfate, polyethylene glycol-400, deionized water and n-octane is 0.1-0.25 g: 0.1 g: 0.6 g: 0.4 mL: 4 mL.

[0009] Furthermore, in S3, the temperature of the thermal polymerization reaction is 60° C.-90° C., and the time is 0.5-4 h.

[0010] Preferably, in S3, the temperature of the thermal polymerization reaction is 70° C. and the time is 6 hours.

[0011] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention uses octadecyltrichlorosilane to conveniently and quickly modify CoFe2O4 nanomagnetic powder to obtain a hydrophobic CoFe2O4 magnetic solid emulsifier, and simply mixes a vinyl-terminated polyethylene glycol-400 water-soluble monomer, a water-soluble initiator, deionized water and n-octane to obtain an oil-in-water type Pickering emulsion. After in-situ polymerization, CoFe2O4 / polymer magnetic composite microspheres can be conveniently and quickly prepared. The method has simple process, convenient operation, low equipment requirements, and is suitable for industrial production.

[0012] 2. The CoFe2O4 / polymer magnetic composite microspheres prepared by the present invention have CoFe2O4 magnetic nanopowder wrapped on the surface of the microspheres, which makes the microspheres have strong magnetism; further, by simply adjusting the amount of octadecyltrichlorosilane modifier, the particle size of the microspheres can be effectively adjusted to meet the requirements of microsphere particle size in different application fields; a small amount of water is used as a porogen (the porogen is green and environmentally friendly), so that the prepared microspheres have a large specific surface area, which has great advantages as a magnetic carrier for preparing functional materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a microscope photo of the spherical powder finally obtained in Examples 1 to 4; Among them, a is embodiment 1, b is embodiment 2, c is embodiment 3, and d is embodiment 4. DETAILED DESCRIPTION

[0014] The present invention is described in detail below in conjunction with specific embodiments. Example 1

[0015] Dissolve 0.3 g of octadecyltrichlorosilane and 1 g of CoFe2O4 powder in 30 mL of isopropanol, stir magnetically at 400-600 rpm for 3-5 h at room temperature, centrifuge at 7000-9000 rpm for 3-5 h after the reaction, and then vacuum dry at 120-160 ° C for 3-5 h to obtain hydrophobic CoFe2O4 powder; 0.2 g of the hydrophobic CoFe2O4 powder, 0.1 g of potassium persulfate, 0.6 g of polyethylene glycol-400 and 0.4 mL of deionized water were added to 4 mL of n-octane, mixed evenly, stirred and emulsified to obtain a water-in-oil Pickering emulsion; The water-in-oil emulsion is placed in a sealed container and placed in an oven for thermal polymerization at 70°C for 6 hours. After the reaction is completed, the reaction solution is centrifuged and washed, and the solid is dried under ventilation at room temperature to obtain a powder to obtain magnetic composite microspheres.

[0016] Example 2 Dissolve 0.4 g of octadecyltrichlorosilane and 1 g of CoFe2O4 powder in 30 mL of isopropanol, stir magnetically at 400-600 rpm for 3-5 h at room temperature, centrifuge at 7000-9000 rpm for 3-5 h after the reaction, and then vacuum dry at 120-160 ° C for 3-5 h to obtain hydrophobic CoFe2O4 powder; 0.2 g of the hydrophobic CoFe2O4 powder, 0.1 g of potassium persulfate, 0.6 g of polyethylene glycol-400 and 0.4 mL of deionized water were added to 4 mL of n-octane, mixed evenly, stirred and emulsified to obtain a water-in-oil Pickering emulsion; The water-in-oil emulsion is placed in a sealed container and placed in an oven for thermal polymerization at 70°C for 6 hours. After the reaction is completed, the reaction solution is centrifuged and washed, and the solid is dried under ventilation at room temperature to obtain a powder to obtain magnetic composite microspheres. Example 3

[0017] Dissolve 0.5 g of octadecyltrichlorosilane and 1 g of CoFe2O4 powder in 30 mL of isopropanol, stir magnetically at 400-600 rpm for 3-5 h at room temperature, centrifuge at 7000-9000 rpm for 3-5 h after the reaction, and then vacuum dry at 120-160 ° C for 3-5 h to obtain hydrophobic CoFe2O4 powder; 0.2 g of the hydrophobic CoFe2O4 powder, 0.1 g of potassium persulfate, 0.6 g of polyethylene glycol-400 and 0.4 mL of deionized water were added to 4 mL of n-octane, mixed evenly, stirred and emulsified to obtain a water-in-oil Pickering emulsion; The water-in-oil emulsion is placed in a sealed container and placed in an oven for thermal polymerization at 70°C for 6 hours. After the reaction is completed, the reaction solution is centrifuged and washed, and the solid is dried under ventilation at room temperature to obtain a powder to obtain magnetic composite microspheres.

[0018] Example 4 Dissolve 0.6 g of octadecyltrichlorosilane and 1 g of CoFe2O4 powder in 30 mL of isopropanol, stir magnetically at 400-600 rpm for 3-5 h at room temperature, centrifuge at 7000-9000 rpm for 3-5 h after the reaction, and then vacuum dry at 120-160 ° C for 3-5 h to obtain hydrophobic CoFe2O4 powder; 0.2 g of the hydrophobic CoFe2O4 powder, 0.1 g of potassium persulfate, 0.6 g of polyethylene glycol-400 and 0.4 mL of deionized water were added to 4 mL of n-octane, mixed evenly, stirred and emulsified to obtain a water-in-oil Pickering emulsion; The water-in-oil emulsion is placed in a sealed container and placed in an oven for thermal polymerization at 70°C for 6 hours. After the reaction is completed, the reaction solution is centrifuged and washed, and the solid is dried under ventilation at room temperature to obtain a powder to obtain magnetic composite microspheres.

[0019] The water contact angle, magnetic separation time and particle size distribution of the CoFe2O4 / polymer magnetic composite microspheres prepared in Examples 1 to 4 were tested respectively. The test results are shown in the following table:

[0020] As can be seen from the above table, the present invention can effectively adjust the particle size of the microspheres by simply adjusting the amount of the octadecyltrichlorosilane modifier to meet the requirements of different application fields for the particle size of the microspheres; the microspheres prepared by the method of the present invention have a short magnetic separation time and excellent hydrophobic properties, and have great advantages as a magnetic carrier for preparing functional materials.

[0021] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing CoFe2O4 / polymer magnetic composite microspheres, characterized in that: The following steps are involved: S1: Dissolve octadecyltrichlorosilane in isopropanol at room temperature, then disperse CoFe2O4 powder in the above solution by magnetic stirring, react for a certain period of time under stirring, centrifuge and precipitate, and vacuum dry to obtain hydrophobic CoFe2O4 powder; S2: adding the hydrophobic CoFe2O4 powder, potassium persulfate, polyethylene glycol-400 and deionized water into n-octane at room temperature, mixing evenly, stirring and emulsifying to obtain a water-in-oil Pickering emulsion; S3: The water-in-oil emulsion is placed in a sealed container and placed in an oven to perform a thermal polymerization reaction. After the reaction is completed, the reaction solution is centrifuged and washed, and the obtained solid is dried under ventilation at room temperature to obtain magnetic composite microspheres.

2. The method for preparing CoFe2O4 / polymer magnetic composite microspheres according to claim 1, characterized in that: In S1, the usage ratio of trichlorooctadecylsilane, CoFe2O4 powder and isopropanol is 0.3-0.6 g: 1 g: 30 mL.

3. The method for preparing CoFe2O4 / polymer magnetic composite microspheres according to claim 1, characterized in that: In S1, the speed of the magnetic stirring is 400-600 rpm, and the time is 3-5 h; the speed of the centrifugal precipitation is 7000-9000 rpm, and the time is 3-5 h; the temperature of the vacuum drying is 120-160° C., and the time is 3-5 h.

4. The method for preparing CoFe2O4 / polymer magnetic composite microspheres according to claim 1, characterized in that: In S2, the feed ratio of the hydrophobic CoFe2O4 powder, potassium persulfate, polyethylene glycol-400, deionized water and n-octane is 0.1-0.25 g: 0.1 g: 0.6 g: 0.4 mL: 4 mL.

5. The method for preparing CoFe2O4 / polymer magnetic composite microspheres according to claim 1, characterized in that: In S3, the temperature of the thermal polymerization reaction is 60°C-90°C, and the time is 0.5-4h.

6. The method for preparing CoFe2O4 / polymer magnetic composite microspheres according to claim 5, characterized in that: The temperature of the thermal polymerization reaction is 70° C. and the time is 6 hours.

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