A method for preparing magnetic microspheres with controllable magnetic particle size

Abstract

The application discloses a kind of magnetic microsphere preparation methods of controllable magnetic particle size, comprising the following steps: first roughening, high molecular microsphere and ultrapure water are added to three-necked flask, roughing agent is then added and stirred, while 40 DEG C water bath heating, roughing is completed after separation solid-liquid and wash multiple times, drying storage is ready for use;Then nitrification, the roughing high molecular microsphere obtained in step one is placed in beaker, ultrapure water is added and stirred, and nitrification agent is added twice and stirred for 48h, and solid-liquid is separated and washed three times;The nitrification high molecular microsphere prepared in step two is dispersed in ultrapure water, and metal precursor solution is added dropwise, stirred and heated to 40-90 DEG C.The application design is novel, can be in relatively simple operation environment the production of magnetic microsphere, and can stably controllable the production of different particle size, different magnetic particle size magnetic microsphere, effectively guarantee the performance and quality of magnetic microsphere, simplify preparation process, reduce production cost.

Description

Technical Field

[0001] This invention relates to the field of nanosphere technology, and more particularly to a method for preparing magnetic microspheres with controllable magnetic particle size. Background Technology

[0002] Magnetic microspheres are polymeric microspheres containing magnetic nanoparticles that exhibit strong magnetic responsiveness. Their preparation process includes: preparation and modification of nanomagnets, dispersion, and microsphericization. Magnetic microspheres can be widely used in magnetic displays, biomedicine, nanomaterials for stealth, and non-destructive testing.

[0003] As a novel material, nanomagnetic materials exhibit unique physical and chemical properties, such as quantum size effects, small size effects, interface effects, and macroscopic quantum tunneling effects, which distinguish them from conventional magnetic materials.

[0004] Nanoscale iron oxide particles have high saturation magnetization and good biocompatibility, and are free of toxic side effects. They can be used in many biomedical fields, such as cell labeling and separation, nuclear magnetic resonance contrast agents, targeted drug carriers, and tumor magnetic hyperthermia therapy.

[0005] Currently, the preparation methods for magnetic microspheres make it difficult to control the particle size of the magnetic core material, which easily leads to agglomeration. The size of the magnetic particles on the surface of the magnetic microspheres is difficult to control and their distribution is relatively uneven, which limits their applicability. In addition, most of them require high temperature and high pressure synthesis conditions, making the preparation operation relatively complex. Summary of the Invention

[0006] The purpose of this invention is to address the shortcomings of existing technologies, such as the difficulty in controlling the size and uneven distribution of magnetic particles on the surface of magnetic microspheres, which limits their applicability, and the fact that most require high-temperature and high-pressure synthesis conditions, making the preparation process relatively complex. The invention proposes a method for preparing magnetic microspheres with controllable magnetic particle size.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for preparing magnetic microspheres with controllable magnetic particle size includes the following steps:

[0009] Step 1: Roughening. Add polymer microspheres and ultrapure water to a three-necked flask, then add a roughening agent and stir. At the same time, heat in a 40°C water bath. After roughening is completed, separate the solid and liquid and wash several times. Dry and store for later use.

[0010] Step 2, nitration: Take the coarsened polymer microspheres obtained in Step 1 and put them into a beaker. Add ultrapure water and stir. Add the nitrifying agent in two batches and stir for 48 hours. Separate the solid and liquid and wash three times.

[0011] Step 3: Disperse the nitrated polymer microspheres obtained in Step 2 in ultrapure water, add the metal precursor solution dropwise, stir and heat to 40-90℃.

[0012] Step 4: Evacuate the reactor and introduce nitrogen gas. Add the anionic reaction solution in batches, adjust the pH value to 5-10, adjust the temperature to 40-100℃, and add the metal precursor solution again to control the anion content. React for 120 minutes, separate the solid and liquid, and wash several times to complete the preparation.

[0013] Preferably, the polymer microspheres are one or more of the following: polystyrene microspheres, silica microspheres, titanium dioxide microspheres, polymethyl methacrylate microspheres, melamine resin microspheres, polystyrene, polymethyl methacrylate, polyethyl methacrylate, and styrene-acrylate copolymers.

[0014] Preferably, the roughening agent is one or a mixture of several of concentrated sulfuric acid, potassium dichromate, manganese sulfate, phosphoric acid, and methanesulfonic acid.

[0015] Preferably, the nitrifying agent is one or a mixture of several of the following: nitric acid, fuming nitric acid, sulfuric acid, glacial acetic acid, acetic anhydride, phosphoric acid, perchloric acid, acetic anhydride, trifluoroacetic anhydride, trifluoroacetic acid, methanesulfonic acid, and trifluoromethanesulfonic acid.

[0016] Preferably, the metal precursor solution is one or more of ferric chloride, ferric sulfate, ferric nitrate, polyaluminum ferric chloride, ferric tribromide, ferric perchlorate, ferric dihydrogen phosphate, potassium ferricyanide, ferrous sulfate, ferrous chloride, and ferrous carbonate, wherein the ferrous salt content is 0.1 to 20 wt%.

[0017] Preferably, the anionic reaction solution is prepared by mixing a reducing agent, a buffer, a complexing agent, and a surfactant.

[0018] More preferably, the reducing agent includes one or a mixture of several of sodium nitrate, potassium nitrate, ammonium nitrate, calcium nitrate, lead nitrate, cerium nitrate, sodium citrate, sodium hypophosphite, sodium borohydride, sodium chloride, sodium carbonate, sodium sulfate, and sodium bicarbonate.

[0019] More preferably, the buffer is one or a mixture of several of the following: ethanol, hydrochloric acid, acetic acid, ammonia, sodium hydroxide solution, potassium hydroxide solution, sodium hydroxide solution, and sodium bicarbonate solution.

[0020] More preferably, the complexing agent includes one or a mixture of several of sodium citrate, sodium sulfite, sodium thiosulfate, polyvinylpyrrolidone, ethylenediamine, and organic polyphosphonic acids.

[0021] More preferably, the surfactant comprises one or a mixture of several of sodium dodecylbenzenesulfonate, polyvinyl alcohol, polyethylene glycol, sodium dodecyl sulfate, sodium hexadecyl sulfate, sodium octadecyl sulfate, and sodium dihexyl succinate.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] 1. In this invention, the content of magnetic particles is adjusted by regulating the concentration of ferric salt and ferrous salt in the metal precursor solution, and the size of magnetic particles is controlled by controlling the concentration of anions and pH value during the reaction. This effectively ensures the controllability of the size of magnetic particles, so as to meet the different needs of magnetic microspheres in different application scenarios.

[0024] 2. In this invention, the magnetic particles on the surface of microspheres of different sizes can be uniformly distributed, and the magnetic particles will not fall off. This ensures that the magnetic microspheres have good monodispersity, high sphericity, good magnetic response, and consistent magnetic content, thus ensuring the quality of the magnetic microspheres.

[0025] 3. The preparation environment of this invention is relatively simple, requiring no high temperature and high pressure reaction atmosphere, and the operation is relatively simple, making it easy to promote and produce.

[0026] This invention features a novel design that enables the production of magnetic microspheres in a relatively simple operating environment. It allows for the stable and controllable production of magnetic microspheres with different particle sizes and magnetic particle dimensions, effectively ensuring the performance and quality of the magnetic microspheres, simplifying the preparation process, and reducing production costs. Attached Figure Description

[0027] Figure 1 This is a SEM image of the product from Embodiment 1 of the present invention.

[0028] Figure 2 This is a SEM image of the product from Embodiment 2 of the present invention.

[0029] Figure 3 This is a SEM image of the product from Embodiment 3 of the present invention.

[0030] Figure 4 This is a SEM image of the product from Embodiment 4 of the present invention.

[0031] Figure 5 This is a magnified SEM image of the product from Embodiment 4 of the present invention.

[0032] Figure 6 The thermogravimetric analysis test weight percentage change curves are shown for various embodiments of the present invention. Detailed Implementation

[0033] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0034] Example 1

[0035] The anionic reaction solution is pre-prepared and consists of a complexing agent, a surfactant, a reducing agent, and a buffer.

[0036] Complexing agent: prepared by compounding 0.01wt% polyvinylpyrrolidone and 5mL ethylenediamine.

[0037] Surfactant: prepared by compounding 0.1 wt% sodium dodecylbenzenesulfonate, 0.01 wt% polyvinyl alcohol, and 5 mL polyethylene glycol.

[0038] Reducing agent: prepared by mixing 10wt% sodium nitrate, 5wt% sodium citrate, 5wt% sodium hypophosphite and ultrapure water.

[0039] Buffer: prepared by mixing 20wt% ethanol, 5% hydrochloric acid, 15% ammonia and ultrapure water.

[0040] Step 1: Add 1g of polystyrene microspheres and 25mL of ultrapure water to a three-necked flask. Add 15wt% concentrated sulfuric acid in batches and stir for 120min at a stirring speed of 350r / min. After roughening, separate the solid and liquid. Wash once with ethanol and then three times with ultrapure water using ultrasonic power of 3000W. After washing, dry and store.

[0041] Step 2: Take 0.5g of the roughened polystyrene microspheres obtained in Step 1 and put them into a beaker. Add 50mL of ultrapure water and stir for 30min at a stirring speed of 350r / min. First, add 25%wt concentrated nitric acid and stir for 10min. Then, add 10%wt concentrated sulfuric acid and stir for 48h at a stirring speed of 350r / min. Separate the solid and liquid and wash three times with ultrapure water.

[0042] Step 3: Disperse the nitrated polystyrene microspheres obtained in Step 2 in ultrapure water, stir and heat to 60°C, stirring at a speed of 400 r / min, and slowly add 50 mL of a metal precursor solution composed of ferrous sulfate and ferric sulfate using a peristaltic pump. The metal precursor solution contains 5 wt% ferrous salt and the addition speed is 8 mL / min.

[0043] Step 4: Evacuate the reactor and purge with nitrogen for 60 minutes. Add 1 wt% complexing agent and 0.1 wt% surfactant, slowly heat to 60°C, add buffer to adjust the pH to 5-9, then cool to 40°C, add 10 wt% reducing agent and react for 10 minutes. Heat to 60°C again and adjust the pH to 5-9, then cool to 40°C, add 10 wt% reducing agent and react for 30 minutes. Add another 10 wt% reducing agent, and simultaneously add a metal precursor solution containing 1 wt% iron salt dropwise using a peristaltic pump for 30 minutes at a dropping rate of 10 mL / min. Finally, control the pH at 7-10 by continuously adding buffer until the reaction is complete. Add a total of 50 mL of anionic reaction solution, separate the solid and liquid, and wash three times with ultrapure water.

[0044] Ferric and ferrous salts are provided by a metal precursor solution. The ferrous salt acts as an initiator, while the ferrous salt is used for redox reactions. An anionic reaction solution provides the reaction environment for a gel-like state. The reducing agent performs the redox reaction. A buffer is used to ensure the stability of the experimental solution in a gel-like state. A complexing agent is used to control the growth rate and size of the particles, ensuring control over the size of the magnetic particles. A surfactant is used to maintain the surface tension between particles and also to control the particle size, preventing uncontrolled growth of magnetic particles and ensuring that the magnetic particles are of suitable and uniform size.

[0045] The product prepared in this embodiment was scanned using a scanning electron microscope, and the electron microscope images are recorded in the appendix. Figure 1 The thermogravimetric analysis data are recorded in Table 2, and the weight curves are attached. Figure 6 Curve a in the diagram.

[0046] Thermogravimetric analysis (TG test): The sample is subjected to a specific temperature program (heating / cooling / isothermal control), and the change in sample mass with temperature or time is observed. In this invention, TG testing is performed under nitrogen protection. The core polymer microspheres exhibit weight loss in the range of 400–450°C, with the maximum weight loss rate around 430°C. At 700°C, the remaining weight represents a percentage of the weight of iron(III) oxide. As the magnetic particles on the microsphere surface thicken, the specific gravity of the remaining weight increases.

[0047] Example 2

[0048] The synthesis was performed according to the method described in Example 1, with the reaction temperature in steps three and four adjusted to 65°C, the total amount of anion added adjusted to 75 mL, and electron micrographs recorded in Appendix 1. Figure 2 The thermogravimetric analysis results are recorded in Table 2, and the weight curves are shown in the appendix. Figure 6 Curve b in the diagram.

[0049] Example 3

[0050] The synthesis was carried out according to the method described in Example 1, with the reaction temperature in steps three and four adjusted to 80°C, the total amount of anion added adjusted to 80 mL, and the electron micrographs recorded in Appendix 1. Figure 2 The thermogravimetric analysis results are recorded in Table 2, and the weight curves are shown in the appendix. Figure 6 Curve c in the diagram.

[0051] Example 4

[0052] The synthesis was carried out according to the method described in Example 1, with the reaction temperature in steps three and four adjusted to 90°C, the total amount of anion added adjusted to 100 mL, and the electron micrographs recorded in Appendix 1. Figure 2 The thermogravimetric analysis results are recorded in Table 2, and the weight curves are shown in the appendix. Figure 6 Curve d in the figure.

[0053] Table 1. Reaction temperature and amount of anion exchange solution added in each example

[0054]

[0055] Table 2. Results of thermogravimetric analysis

[0056] Example Weight percent (%) Example One 37.78802 Example Two 41.49327 Example Three 44.40498 Example Four 50.29167

[0057] Combine Table 2 and Appendix Figure 6 The weight percentage curves and electron microscope images of each embodiment clearly show that:

[0058] Appendix Figure 1 The surface particles of the medium magnetic microspheres are uniform and dense. Although there are a few gaps between the particles, the overall encapsulation is intact.

[0059] Appendix Figure 2 The surface particles of the medium magnetic microspheres are small, uniform, flat, and dense.

[0060] Appendix Figure 3 The surface particles of the medium magnetic microspheres are coarse, but they still remain uniform, flat and dense.

[0061] Appendix Figure 4 The magnetic particles on the surface of the medium magnetic microspheres have undergone a second layer of coating growth.

[0062] This invention regulates the content of magnetic particles by controlling the concentration of ferrous salt in the metal precursor solution added at different stages, and adjusts the anion concentration and pH value of the solution by adjusting the amount of anion reaction solution added. This effectively controls the size of magnetic particles on the surface of magnetic microspheres and ensures that the magnetic particles are evenly distributed on the surface of the magnetic microspheres. It can meet the needs of customized and mass production of magnetic microspheres with different particle sizes.

[0063] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing magnetic microspheres with controllable magnetic particle size, characterized in that, Includes the following steps: Step 1: Roughening. Add polymer microspheres and ultrapure water to a three-necked flask, then add a roughening agent and stir. At the same time, heat in a 40°C water bath. After roughening is completed, separate the solid and liquid and wash several times. Dry and store for later use. Step 2, nitration: Take the roughened polymer microspheres obtained in Step 1 and put them into a beaker. Add ultrapure water and stir. First, add 25%wt concentrated nitric acid and stir for 10 min. Then add 10%wt concentrated sulfuric acid and stir for 48 h. Separate the solid and liquid and wash three times. Step 3: Disperse the nitrated polymer microspheres obtained in Step 2 in ultrapure water, add dropwise a metal precursor solution composed of ferrous sulfate and ferric sulfate, the metal precursor solution containing 5 wt% ferrous salt, stir and heat to 40-90℃. Step 4: Evacuate the reactor and introduce nitrogen gas. Add 1 wt% complexing agent and 0.1 wt% surfactant, slowly heat to 60°C, add buffer to adjust the pH to 5-9, then cool to 40°C, add 10 wt% reducing agent and react for 10 min. Heat to 60°C again and adjust the pH to 5-9, then cool to 40°C, add 10 wt% reducing agent and react for 30 min. Add another 10 wt% reducing agent. The total amount of complexing agent, surfactant, reducing agent, and buffer added is 50 mL, 75 mL, 80 mL, or 100 mL, respectively. At the same time, add a metal precursor solution containing 1 wt% iron salt dropwise again and react for 30 min at a dropping rate of 10 mL / min. Finally, control the pH at 7-10 by continuously adding buffer until the reaction is complete. Separate the solid and liquid and wash several times to complete the preparation.

2. The method for preparing magnetic microspheres with controllable magnetic particle size according to claim 1, characterized in that, The polymer microspheres are polystyrene microspheres or polymethyl methacrylate microspheres.

3. The method for preparing magnetic microspheres with controllable magnetic particle size according to claim 1, characterized in that, The roughening agent is one or a mixture of several of the following: concentrated sulfuric acid, potassium dichromate, phosphoric acid, and methanesulfonic acid.

4. The method for preparing magnetic microspheres with controllable magnetic particle size according to claim 1, characterized in that, The reducing agent is prepared by compounding 10wt% sodium nitrate, 5wt% sodium citrate, 5wt% sodium hypophosphite and ultrapure water.

5. The method for preparing magnetic microspheres with controllable magnetic particle size according to claim 1, characterized in that, The buffer is prepared by compounding 20wt% ethanol, 5% hydrochloric acid, 15% ammonia and ultrapure water.

6. The method for preparing magnetic microspheres with controllable magnetic particle size according to claim 1, characterized in that, The complexing agent was prepared by compounding 0.01 wt% polyvinylpyrrolidone and 5 mL ethylenediamine.

7. The method for preparing magnetic microspheres with controllable magnetic particle size according to claim 1, characterized in that, The surfactant was prepared by compounding 0.1 wt% sodium dodecylbenzenesulfonate, 0.01 wt% polyvinyl alcohol, and 5 mL polyethylene glycol.

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