CN117550650A - SiO (silicon dioxide) 2 Wrapping magnetic Fe 3 O 4 Method for preparing nano particles - Google Patents

SiO (silicon dioxide) 2 Wrapping magnetic Fe 3 O 4 Method for preparing nano particles Download PDF

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CN117550650A
CN117550650A CN202311553293.1A CN202311553293A CN117550650A CN 117550650 A CN117550650 A CN 117550650A CN 202311553293 A CN202311553293 A CN 202311553293A CN 117550650 A CN117550650 A CN 117550650A
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sio
nano particles
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particle size
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戴良
赵媛
汪书韵
曹振奇
马伟
彭芳
毛剑锋
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Wuxi Guosheng Bioengineering Co ltd
Jiangnan University
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Jiangnan University
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F41/00—Apparatus or processes specially adapted for manufacturing or assembling magnets, inductances or transformers; Apparatus or processes specially adapted for manufacturing materials characterised by their magnetic properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y25/00—Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
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    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C01B33/18—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof
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    • C01—INORGANIC CHEMISTRY
    • C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
    • C01G49/00—Compounds of iron
    • C01G49/02—Oxides; Hydroxides
    • C01G49/08—Ferroso-ferric oxide (Fe3O4)
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    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/01—Particle morphology depicted by an image
    • C01P2004/03—Particle morphology depicted by an image obtained by SEM
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    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/30—Particle morphology extending in three dimensions
    • C01P2004/32—Spheres
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/51—Particles with a specific particle size distribution
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
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    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/80—Particles consisting of a mixture of two or more inorganic phases
    • C01P2004/82—Particles consisting of a mixture of two or more inorganic phases two phases having the same anion, e.g. both oxidic phases
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/42—Magnetic properties

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Abstract

The invention provides a SiO 2 Wrapping magnetic Fe 3 O 4 The preparation method of the nano particles utilizes an improved solvothermal method to prepare the magnetic Fe with large particle size and narrow particle size distribution 3 O 4 Nano particles are hydrolyzed by silicate ester and SiO is uniformly coated on the surface of the nano particles 2 Finally, the SiO with controllable morphology and particle size and good dispersity is obtained 2 Wrapping magnetic Fe 3 O 4 NanoparticlesAnd (5) a seed. The method has the advantages of low-cost and easily-obtained raw materials, simple operation, no need of complex large-scale equipment, environment-friendly reagents, short reaction time and industrial production.

Description

SiO (silicon dioxide) 2 Wrapping magnetic Fe 3 O 4 Method for preparing nano particles
Technical Field
The invention belongs to the technical field of magnetic nano materials, in particular to a SiO (silicon oxide) 2 Wrapping magnetic Fe 3 O 4 A method for preparing nano particles.
Background
The magnetic beads generally refer to magnetic particles with superparamagnetism, which can be rapidly aggregated in a magnetic field and can be uniformly dispersed again after no magnetic field exists. The silica magnetic beads are convenient to carry out diversified modification due to the hydroxyl groups on the surfaces of the silica magnetic beads, the coated nano particles have good monodispersity, uniform particle size distribution and stronger chemical stability to the external environment, and the silica magnetic beads can be combined with medicines, proteins, antibodies or nucleic acids, so that the silica magnetic beads have wide application prospects. The unique physical and chemical properties of the magnetic micro-nano material draw great attention, and the characteristics of low toxicity, easily available raw materials, simple preparation, excellent performance and the like become research hot spots in recent years.
Currently, fe 3 O 4 The preparation method of the magnetic nano particles mainly comprises a coprecipitation method, a high-temperature decomposition method, a microemulsion method, a sol-gel method, an ultrasonic chemical method and the like. The nanometer particles obtained by the traditional technology have regular morphology, but have wider particle size distribution and general surface property and morphology controllability.
CN110767437a discloses a preparation method of magnetic nano particles with a silica coated ferroferric oxide core-shell structure, which comprises the steps of dissolving a surfactant of a separator in n-hexane to form uniform water-in-oil emulsion, then dropwise adding an iron source precursor solution into the water-in-oil emulsion, slowly adding an alkaline reagent to obtain uniformly dispersed Fe 3 O 4 A nanoparticle microemulsion; then adding silicate and alkaline reagent dropwise to hydrolyze the silicon source to formSiO 2 Coating Fe 3 O 4 And (3) nano particles to finally obtain the magnetic microbeads. The method uses the obtained Fe 3 O 4 In the nanoparticle microemulsion, fe 3 O 4 The nano particles are positioned in the hydrophilic part of the microemulsion, and the hydrophobic part of the microemulsion is positioned in Fe 3 O 4 The surface of the nano particles, when a silicon source is added, can be formed on Fe 3 O 4 And the hydrophobic part on the surface of the nano particle is stably hydrolyzed, and finally the magnetic microbead with uniformly dispersed particle size is obtained. However, in the water-in-oil emulsion system constructed by the method, the size of the microemulsion directly limits the size of the magnetic microbeads, so that the method is only suitable for preparing the magnetic microbeads with small particle size, and the magnetic microbeads with large particle size and narrow particle size part cannot be successfully obtained.
There are reports in the prior art (sun S, JACS, 2004,126 (1), 273-279; jana NR, chemistry of materials,2004, 16 (20): 3931-3935) that organic iron is used as a precursor, a high boiling point organic solvent (hexadecane, octadecane, 1-octadecene, etc.) is used, and the precursor is cleaved at high temperature in an activator (alcohol or primary amine) in a non-aqueous solvent to obtain magnetic Fe 3 O 4 The nanoparticles are monodisperse. However, these methods have severe requirements for reaction conditions, complicated operation, poor repeatability, and high organic solvent cost, and are not suitable for industrial mass production.
Preparation of magnetic Fe by hydrothermal method 3 O 4 The nanoparticles are typically FeSO 4 ·7H 2 O and NaOH are used as raw materials, sodium thiosulfate is used as an oxidant, and Fe (OH) is prepared by a hydrothermal oxidation method firstly 2 Colloid, oxidized to Fe 3 O 4 . The solvothermal method is a preparation method based on a hydrothermal method, and can enable crystal grains to grow by prolonging the reaction time due to simple operation, so that the grain size can be conveniently regulated and controlled. In the prior art, sodium acetate is used as a classical stabilizer and a precipitator to prepare large-size Fe in literature 3 O 4 Report of nanoparticles. But the particle size distribution is still broad and the production cycle is long. Therefore, a preparation process which is simple to operate, low in cost and easy to obtain raw materials, and large in particle size and narrow in particle size dispersion of the prepared magnetic microbeads is needed.
Disclosure of Invention
To solve the problems in the prior art for preparing SiO 2 Wrapping magnetic Fe 3 O 4 The invention provides an improved SiO which is difficult to obtain the defects of large particle size, narrow particle size distribution, complex reaction condition and long reaction period of nano particles 2 Wrapping magnetic Fe 3 O 4 The preparation method of the nano particles can rapidly prepare the magnetic composite particles with uniform coating, narrow particle size distribution, controllable particle size and strong magnetic response at room temperature. The particle size can be adjusted by controlling the proportion of the ferric chloride hexahydrate and the compound sodium salt, and meanwhile, the particle size distribution is narrow and the magnetic response is strong; the invention has short reaction time and simple method, and is suitable for industrial production.
The invention solves the technical problems by the following technical proposal:
SiO (silicon dioxide) 2 Wrapping magnetic Fe 3 O 4 A method of preparing nanoparticles comprising the steps of:
(1) After ultrasonic dispersion of an iron source and ethanol, adding polyethylene glycol, and performing ultrasonic dispersion again to obtain a dispersion liquid A; anhydrous sodium acetate, sodium polyacrylate and ethylene glycol are subjected to ultrasonic dispersion at constant temperature to obtain a dispersion liquid B; maintaining constant temperature, slowly adding dispersion A into dispersion B, stirring for 30-60min, transferring to reaction kettle, incubating at 180-240 deg.C, cooling to room temperature, magnetically separating, washing, and drying to obtain magnetic Fe 3 O 4 A nanoparticle;
(2) The magnetic Fe obtained in the step (1) is treated 3 O 4 Dispersing nano particles in ethanol water solution by ultrasonic, adding ammonia water, stirring for 30-60min, dripping alkyl orthosilicate, reacting for 8-15h, magnetically separating, and washing to obtain seed SiO 2 Wrapping magnetic Fe 3 O 4 And (3) nanoparticles.
Further, the SiO 2 Wrapping magnetic Fe 3 O 4 The nano particles have a core-shell structure, and the core is magnetic Fe 3 O 4 Nanoparticles with a particle size of 200-1000nm, preferably 380-560nm; the shell is SiO 2 ，SiO 2 Wrapping magnetic Fe 3 O 4 Nanoparticle to magnetic Fe 3 O 4 The nanoparticles are 20-300nm in size, preferably 40-120nm in size, such as 50nm, 80nm, 90nm, 100nm, 110nm.
Further, the SiO 2 Wrapping magnetic Fe 3 O 4 The polydispersion coefficient of the nano particles is 1 to or less than D 50 /D 20 Less than or equal to 1.5, preferably 1.22, less than or equal to D 50 /D 20 Less than or equal to 1.36. The particle size distribution can be D 50 /D 20 The closer the value is to 1, the narrower the particle size distribution of the particles. The preparation method improves the solvothermal method and the Stober method, particularly adopts the sodium salt of the compounding of sodium acetate and sodium polyacrylate in the solvothermal method, and the compounded sodium salt simultaneously plays roles of a stabilizer, a precipitator and an antistatic agent, so that the reaction time can be prolonged to obtain the magnetic Fe with large particle size 3 O 4 Nanoparticles, then according to classical Stober in the resulting magnetic Fe 3 O 4 Growth of SiO on nanoparticle surface 2 Finally, the SiO with controllable grain diameter and narrow grain diameter distribution is obtained 2 Wrapping magnetic Fe 3 O 4 And (3) nanoparticles. According to the improved preparation method provided by the invention, the magnetic composite particles can be prepared to have good dispersibility in larger size (more than 300 nm), uniform and stable size and good repeatability in application, and the requirements of large particle size and narrow particle size distribution in the application fields of biological medicines, catalysts, photonic crystals and the like can be met without poor result repeatability caused by size difference.
Further, in the step (1), the iron source is ferric trichloride hexahydrate, and the polyethylene glycol has a number average molecular weight of 1500-3000 g/mol; slowly adding the dispersion liquid A into the dispersion liquid B within 1-2 h; the incubation time is 3 to 10 hours, preferably 4 to 6 hours.
Further, in the step (1), the molecular weight of the sodium polyacrylate is 400-1500g/mol; preferably 600-1000g/mol. Sodium polyacrylate mainly acts as stabilizer and antistatic agent, and has multiple carboxyl groups on its polymer chain, and is adsorbed on Fe 3 O 4 Nanoparticle surface and carboxylate radical to make Fe 3 O 4 The nano particles have better dispersibility in organic solvents; in addition, the addition of sodium polyacrylate causes Fe 3 O 4 NanoparticlesElectronegativity, after subsequent addition of ammonia water, tends to adsorb NH in the system 4 + Is beneficial to the reaction of the orthosilicate in Fe 3 O 4 Hydrolysis of nanoparticle surfaces to form SiO 2 The coating layer finally obtains SiO with large grain diameter and evenly dispersed grain diameter 2 Wrapping magnetic Fe 3 O 4 And (3) nanoparticles.
Further, in the step (1), when preparing the dispersion liquid A, the dosage ratio of the iron source, the ethanol and the polyethylene glycol is 1 to 4.5g:20-30mL:1.2-1.4g; when preparing the dispersion liquid B, the dosage ratio of anhydrous sodium acetate, sodium polyacrylate and ethanol is 1g:0.2-0.3g:20-30mL; and the volume ratio of the dispersion liquid A to the dispersion liquid B is 1-1.3:1, preferably 1-1.22:1. according to the dosage ratio of the materials, the magnetic Fe with narrow particle size distribution can be obtained 3 O 4 The nano particles are coated with SiO uniformly for obtaining good surface appearance subsequently 2 Lay a foundation for the composite magnetic particles.
The inventors have also found that substitution of sodium polyacrylate with organic sodium salts of other structures, such as sodium dodecylbenzenesulfonate, sodium citrate, etc., does not achieve the effect of narrow particle size distribution, for reasons that are not clear. The inventors speculate that anhydrous sodium acetate and sodium polyacrylate have synergistic effect and can lead to Fe 3 O 4 The aggregation crystallization process is stably and synchronously carried out, and Fe with uniform particle size is finally obtained 3 O 4 A nanoparticle; in addition, compared with small molecular organic sodium salt, the sodium polyacrylate is a high molecular sodium salt, has adjustable molecular weight, higher carboxyl density and more effective reduction of Fe 3 O 4 The surface energy of the nano particles and the adsorption effect of the polymer can also more effectively prevent Fe 3 O 4 Agglomeration of nanoparticles.
Further, in the ultrasonic dispersion of the present invention, the ultrasonic frequency is not particularly limited, and the material can be sufficiently dispersed, for example, in one embodiment of the present invention, the ultrasonic frequency is 60 kHz to 100kHz; washing and drying are not particularly limited, and generally, washing with deionized water is performed first, washing with absolute ethyl alcohol is performed later, and drying is oven drying, vacuum drying or the like.
In step (1), it is possible to addThe dosage of the iron source reaches the increase of magnetic Fe 3 O 4 The size of the nano particles is further controlled, so that the purpose of controllable particle size is achieved; and magnetic Fe in the presence of two sodium salts of the compound anhydrous sodium acetate and sodium polyacrylate 3 O 4 The particle size of the nano particles steadily and synchronously increases, so that the particle size distribution is narrow when large-particle-size magnetic particles are obtained. In a preferred technical scheme of the invention, the dosage ratio of the iron source, the ethanol and the polyethylene glycol is 1-3.5g:20-30mL:1.2-1.4g, corresponding to the obtained magnetic Fe 3 O 4 The size of the nano particles is 380-560nm; in a more preferable technical scheme of the invention, the dosage ratio of the iron source, the ethanol and the polyethylene glycol is 1-2.5g:20-30mL:1.25-1.3g, corresponding to the obtained magnetic Fe 3 O 4 The nanoparticle size is 380-440nm. In the prior art, the increase of magnetic Fe is generally achieved by prolonging the reaction time of solvothermal reaction 3 O 4 The purpose of the nanoparticle size. However, on the one hand, to obtain large-sized magnetic Fe 3 O 4 The nanoparticle needs to prolong the reaction time to more than 48 hours, so that the long reaction time is not desirable for industrial production; in addition, by extending the reaction time, although large-size magnetic Fe can be obtained 3 O 4 Nanoparticles, however, also broaden the particle size distribution. The invention can complete the reaction in a short time to obtain large-size magnetic Fe with required size and narrow particle size distribution by compounding anhydrous sodium acetate and sodium polyacrylate 3 O 4 The nano particles have the advantage of obvious industrial production.
Further, in the step (2), magnetic Fe 3 O 4 The nano particles are dispersed in ethanol water solution in an ultrasonic way, and the volume concentration of ethanol in the ethanol water solution is 80-90%; the alkyl orthosilicate is at least one selected from ethyl orthosilicate and methyl orthosilicate; the mass concentration of the ammonia water is 30-40wt%.
Further, in the step (2), magnetic Fe 3 O 4 The dosage ratio of the nano particles to the ethanol water solution to the ammonia water to the alkyl orthosilicate is 1mg:10-15mL:0.15-0.2mL:0.15-0.2mL; in one embodiment of the invention, the magnetic Fe 3 O 4 The dosage ratio of the nano particles to the ethanol water solution to the ammonia water to the alkyl orthosilicate is 1mg:12.8mL:0.16mL:0.16mL.
Compared with the prior art, the technical scheme of the invention has the following advantages:
in the preparation method, the magnetic Fe with controllable particle size and narrow particle size distribution can be obtained 3 O 4 The nanometer particles have strong magnetic response and uniform particle size, and the particle size of the nanometer particles is 300-950 nm. The preparation method has the advantages of simple process, mild reaction conditions and short reaction time, and can realize large-scale production. In the subsequent silicon dioxide coating layer, the silicon source is hydrolyzed under the room temperature condition, the reaction condition is mild, the obtained silicon dioxide coating layer is uniformly dispersed, the magnetic response is strong, the silicon dioxide coating layer is uniformly covered, the particle size is uniform, and the surface of the adjustable silicon dioxide magnetic microsphere can be continuously modified with the ligand, so that the silicon dioxide magnetic microsphere has wide application prospect in the fields of biomedicine, catalysts, photonic crystals and the like.
Drawings
FIG. 1 shows magnetic Fe having a median particle diameter of 382nm obtained in step (1) of example 1 3 O 4 SEM photograph of the nanoparticle.
FIG. 2 is SiO with a median particle diameter of 478nm obtained in step (2) of example 1 2 Wrapping bare magnetic Fe 3 O 4 SEM photograph of the nanoparticle.
FIG. 3 shows magnetic Fe of 438nm median particle diameter obtained in step (1) of example 2 3 O 4 SEM photograph of the nanoparticle.
FIG. 4 is SiO with a median particle diameter of 518nm obtained in step (2) of example 2 2 Wrapping bare magnetic Fe 3 O 4 SEM photograph of the nanoparticle.
FIG. 5 shows that step (1) of example 3 gives 557nm bare magnetic Fe 3 O 4 SEM photographs of NPs.
FIG. 6 is a silicon dioxide coated bare magnetic Fe of 654nm obtained in step (2) of example 3 3 O 4 SEM photographs of NPs.
FIG. 7 is a bare magnetic Fe of 936nm obtained in the step (1) of example 4 3 O 4 SEM photographs of NPs.
Detailed Description
The present invention will be further described with reference to the accompanying drawings and specific examples, which are not intended to be limiting, so that those skilled in the art will better understand the invention and practice it.
Sodium polyacrylate is purchased from Hangzhou Yuhao chemical engineering Co., ltd, and has molecular weights of 400, 600, 1000 and 1500 respectively.
Example 1
(1) Weighing 4.8g of ferric chloride hexahydrate, adding 120mL of glycol for ultrasonic dissolution (ultrasonic frequency is 100 kHz), adding 6g of polyethylene glycol, and then carrying out ultrasonic dissolution to obtain a tan solution A; 4.38g of anhydrous sodium acetate, 0.88g of sodium polyacrylate with molecular weight of 600 g/mol are weighed, 120mL of ethylene glycol is added, and the mixture is magnetically stirred and dissolved in a water bath at 40 ℃ to obtain colorless transparent solution B. Keeping water bath and stirring, slowly introducing solution A into solution B, after the addition is completed within 1h, keeping the volume ratio of solution A to solution B at 1:1, continuously preserving heat and stirring for 30min, transferring to a reaction kettle, incubating for 4h at 200 ℃, changing the solution from pale yellow to black, washing 3 times with absolute ethyl alcohol after magnetic separation, and re-dispersing in 100mL of deionized water to obtain magnetic Fe with median particle diameter of 382nm 3 O 4 And (3) nanoparticles.
(2) Taking 0.1g of the magnetic Fe obtained in S1 3 O 4 Adding 1.12L anhydrous ethanol and 0.16L deionized water into the nano particles, carrying out ultrasonic mixing for 1h at room temperature, adding 16mL of 30wt% ammonia water after a mechanical stirring device is built, carrying out mechanical stirring for 30min, slowly dropwise adding 16mL of tetraethyl orthosilicate, and reacting for 12h, wherein the solution becomes milky. After magnetic separation, washing with absolute ethanol and water for 3 times respectively, and redispersing in 100mL deionized water to obtain SiO with median particle diameter of 478nm 2 Wrapping bare magnetic Fe 3 O 4 And (3) nanoparticles.
FIG. 1 shows magnetic Fe having a median particle diameter of 382nm obtained in step (1) of example 1 3 O 4 SEM photograph of nanoparticles, D 50 /D 20 1.17. FIG. 2 is SiO with a median particle diameter of 478nm obtained in step (2) of example 1 2 Wrapping bare magnetic Fe 3 O 4 SEM photograph of nanoparticles, D 50 /D 20 1.22. It can be seen that the light source is,magnetic Fe obtained in step (1) 3 O 4 Nanoparticles, and SiO obtained in step (2) 2 Wrapping magnetic Fe 3 O 4 The nano particles have good dispersibility and narrow particle size distribution.
Example 2
The other conditions were the same as in example 1 except that in step (1), the amount of ferric chloride hexahydrate was changed to 10.8g, the amount of sodium acetate anhydrous was changed to 9.86g, and the amount of sodium polyacrylate was changed to 1.97g; step (1) obtaining 438nm bare magnetic Fe 3 O 4 NPs; step (2) obtaining 518nm silicon dioxide coated bare magnetic Fe 3 O 4 NPs。
FIG. 3 shows magnetic Fe of 438nm median particle diameter obtained in step (1) of example 2 3 O 4 SEM photograph of nanoparticles, D 50 /D 20 1.23. FIG. 4 is SiO with a median particle diameter of 518nm obtained in step (2) of example 2 2 Wrapping bare magnetic Fe 3 O 4 SEM photograph of nanoparticles, D 50 /D 20 1.30.
Example 3
The other conditions were the same as in example 1 except that in step (1), the amount of ferric chloride hexahydrate was changed to 16.8g, the amount of sodium acetate anhydrous was changed to 15.33g, and the amount of sodium polyacrylate was changed to 3.07g; step (1) obtaining 560nm bare magnetic Fe 3 O 4 NPs; step (2) obtaining 557nm silicon dioxide coated bare magnetic Fe 3 O 4 NPs。
FIG. 5 shows that step (1) of example 3 gives 557nm bare magnetic Fe 3 O 4 SEM photograph of NPs, D thereof 50 /D 20 1.27; FIG. 6 is a silicon dioxide coated bare magnetic Fe of 654nm obtained in step (2) of example 3 3 O 4 SEM photograph of NPs, D thereof 50 /D 20 1.36.
Example 4
The other conditions were the same as in example 1 except that in step (1), the amount of ferric chloride hexahydrate was changed to 21.6g, the amount of sodium acetate anhydrous was changed to 19.71g, and the amount of sodium polyacrylate was changed to 3.94g; step (1) to obtain 936nm bare magnetic Fe 3 O 4 NPs。
FIG. 7 is a real worldEXAMPLE 4 step (1) bare magnetic Fe at 936nm 3 O 4 SEM photograph of NPs, D thereof 50 /D 20 1.33.
Example 5
Other conditions were the same as in example 1, except that the volume ratio of solution a to solution B was 1.22:1.
example 6
Other conditions were the same as in example 1, except that the volume ratio of solution A and solution B was 1.3:1.
example 7
The other conditions were the same as in example 1 except that the amount of sodium polyacrylate was changed from 0.88g to 1.32g.
Example 8
The other conditions were the same as in example 1 except that the molecular weight of sodium polyacrylate was 1000g/mol.
Example 9
The other conditions were the same as in example 1 except that the molecular weight of sodium polyacrylate was 400 g/mol.
Example 10
The other conditions were the same as in example 1 except that the molecular weight of sodium polyacrylate was 1500g/mol.
Comparative example 1
The other conditions were the same as in example 1 except that sodium polyacrylate was not added and the amount of anhydrous sodium acetate was changed to 5.26g.
Comparative example 2
Other conditions were the same as in example 1 except that sodium polyacrylate was replaced with equal mass of sodium citrate.
Comparative example 3
The other conditions were the same as in example 1 except that sodium polyacrylate was replaced with equal mass of sodium dodecylbenzenesulfonate.
Wherein, in comparative example 1, only anhydrous sodium acetate and magnetic Fe are added 3 O 4 The nanoparticle size distribution is broadened. Comparative example 2 and comparative example 3 used sodium citrate and sodium dodecylbenzenesulfonate in place of sodium polyacrylate, respectively. Although the particle size distribution was better than comparative example 1, it was still worse than example 1. In particular, comparative example 2 and comparative example 3 2 Wrapped magnetic materialFe 3 O 4 Nanoparticles, broad particle size distribution: comparative example 2 SiO 2 Wrapping magnetic Fe 3 O 4 The median diameter of the nano particles is 478nm, D 50 /D 20 1.35; comparative example 3 SiO 2 Wrapping magnetic Fe 3 O 4 The median particle diameter of the nano particles is 463nm, D 50 /D 20 1.31. It can be seen that sodium polyacrylate is advantageous for obtaining Fe with a narrow particle size distribution except in step (1) 3 O 4 Nanoparticles, also facilitate the formation of uniform SiO during subsequent hydrolysis of the orthosilicate 2 The coating layer is the final composite magnetic particle with narrow particle size distribution.
The median particle diameters and particle diameter distributions of the above examples and comparative examples are shown in the following table 1:
TABLE 1 particle size and particle size distribution
It can be seen that the method of the invention can efficiently and rapidly prepare magnetic Fe with larger particle size 3 O 4 Nano particles, narrow particle size distribution and large-size magnetic Fe 3 O 4 The nano particles have stronger magnetism and are more convenient for magnetic separation, and the SiO with narrow particle size distribution is prepared subsequently 2 Wrapping magnetic Fe 3 O 4 The nano particles lay a good foundation. The method can effectively prepare the magnetic particles with controllable particle size and narrow particle size distribution, and SiO is arranged on the surface 2 The modified groups can be conveniently used for various occasions, such as medical contrast agents, biological markers, active organism separation (active organisms comprise proteins, amino acids, peptides, nucleic acids, enzymes and the like), catalysts, photonic crystals, microwave absorbing materials, thermomagnetic therapy, biological sensors, drug transportation and the like.

Claims (10)

1. SiO (silicon dioxide) 2 Wrapping magnetic Fe 3 O 4 The preparation method of the nano particles is characterized by comprising the following steps:
(1) After ultrasonic dispersion of iron source and ethanolAdding polyethylene glycol, and performing ultrasonic dispersion again to obtain a dispersion liquid A; anhydrous sodium acetate, sodium polyacrylate and ethylene glycol are subjected to ultrasonic dispersion at constant temperature to obtain a dispersion liquid B; maintaining constant temperature, slowly adding dispersion A into dispersion B, stirring for 30-60min, transferring to reaction kettle, incubating at 180-240 deg.C, cooling to room temperature, magnetically separating, washing, and drying to obtain magnetic Fe 3 O 4 A nanoparticle;
(2) The magnetic Fe obtained in the step (1) is treated 3 O 4 Dispersing nano particles in ethanol water solution by ultrasonic, adding ammonia water, stirring for 30-60min, dripping alkyl orthosilicate, reacting for 8-15h, magnetically separating, and washing to obtain seed SiO 2 Wrapping magnetic Fe 3 O 4 And (3) nanoparticles.
2. The method of claim 1, wherein the SiO is 2 Wrapping magnetic Fe 3 O 4 The nano particles have a core-shell structure, and the core is magnetic Fe 3 O 4 Nanoparticles with a particle size of 200-1000nm, preferably 380-560nm; the shell is SiO 2 ，SiO 2 Wrapping magnetic Fe 3 O 4 Nanoparticle to magnetic Fe 3 O 4 The nanoparticles are 20-300nm in size, preferably 40-120nm in size.
3. The method of claim 1, wherein the SiO is 2 Wrapping magnetic Fe 3 O 4 The polydispersion coefficient of the nano particles is 1 to or less than D 50 /D 20 Less than or equal to 1.5, preferably 1.22, less than or equal to D 50 /D 20 ≤1.36。
4. The method according to claim 1, wherein in the step (1), the iron source is ferric trichloride hexahydrate, and the polyethylene glycol has a number average molecular weight of 1500 to 3000 g/mol; slowly adding the dispersion liquid A into the dispersion liquid B within 1-2 h; the incubation time is 3 to 10 hours, preferably 4 to 6 hours.
5. The process according to claim 1, wherein in step (1), the molecular weight of the sodium polyacrylate is 400 to 1500g/mol.
6. The process according to claim 5, wherein the molecular weight of the sodium polyacrylate is 600 to 1000g/mol.
7. The method according to claim 1, wherein in the step (1), the dispersion A is prepared by mixing the iron source, ethanol and polyethylene glycol in an amount of 1 to 4.5g:20-30mL:1.2-1.4g; when preparing the dispersion liquid B, the dosage ratio of anhydrous sodium acetate, sodium polyacrylate and ethanol is 1g:0.2-0.3g:20-30mL; and the volume ratio of the dispersion liquid A to the dispersion liquid B is 1-1.3:1, preferably 1-1.22:1.
8. the preparation method according to claim 1, wherein in the step (1), the ratio of the iron source, ethanol and polyethylene glycol is 1-3.5g:20-30mL:1.2-1.4g; preferably, the dosage ratio of the iron source, the ethanol and the polyethylene glycol is 1-2.5g:20-30mL:1.25-1.4g.
9. The method according to claim 1, wherein in the step (2), magnetic Fe 3 O 4 The nano particles are dispersed in ethanol water solution in an ultrasonic way, and the volume concentration of ethanol in the ethanol water solution is 80-90%; the alkyl orthosilicate is at least one selected from ethyl orthosilicate and methyl orthosilicate; the mass concentration of the ammonia water is 30-40wt%.
10. The method according to claim 1, wherein in the step (2), magnetic Fe 3 O 4 The dosage ratio of the nano particles to the ethanol water solution to the ammonia water to the alkyl orthosilicate is 1mg:10-15mL:0.15-0.2mL:0.15-0.2mL.
CN202311553293.1A 2023-11-21 2023-11-21 SiO (silicon dioxide) 2 Wrapping magnetic Fe 3 O 4 Method for preparing nano particles Pending CN117550650A (en)

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