Preparation method and application of magnetic mesoporous super-high nitrogen content core-shell structure composite microspheres

Abstract

The application discloses a preparation method and application of magnetic mesoporous super-high nitrogen content core-shell structure composite microspheres, and comprises the following steps: taking magnetic nanoparticles as seeds, depositing a dense silica protective layer on the surface of the magnetic nanoparticles through a sol-gel method to obtain magnetic composite microspheres; dispersing deionized water, an organic solvent and the magnetic composite microspheres in an oil-water mixed solvent to obtain a dispersion liquid A; dispersing melamine and formaldehyde in deionized water, and forming a solution B under the action of an alkaline catalyst; adding the dispersion liquid A into the solution B, adding an acidic catalyst dropwise, continuing to stir at 100 DEG C, and then carrying out post-treatment to obtain the magnetic mesoporous super-high nitrogen content core-shell structure composite microspheres; the magnetic mesoporous super-high nitrogen content core-shell structure composite microspheres have the characteristics of strong superparamagnetic response, large mesoporous channels, a regular and ordered core-shell structure, super-high nitrogen content, a polymer / carbon-based structure of functional groups, controllable hydrophilicity and hydrophobicity and easy material transmission and diffusion, and can be applied as a carrier in the fields of adsorption separation, catalysis, drug release and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of magnetic materials, in particular to a preparation method and application of magnetic mesoporous super-high nitrogen content core-shell structure composite microspheres. BACKGROUND

[0002] Due to the poor assembly ability of nitrogen-containing carbon source precursors, taking melamine formaldehyde resin as an example, it is a carbon source material with super-high nitrogen content, but its polymerization reaction is carried out at high temperature, which is not conducive to the progress of the liquid phase assembly reaction, and the nitrogen-containing magnetic porous material obtained has problems such as poor magnetic response, small pore size, disordered pore distribution, and poor dispersibility.

[0003] In the prior art, patent application CN201910391025.1 discloses a kind of magnetic ordered mesoporous carbon-based or high polymer-based core-shell structure composite microspheres, which uses magnetic nanoparticles as seeds, and a dense silica protective layer is coated on the surface of the magnetic nanoparticles by sol-gel method;Using interfacial co-assembly technology, using a high molecular weight block copolymer as a template agent, a macromolecular surfactant / polymer layer composite material with ordered mesostructure is deposited on the surface of the silica;Finally, by calcining carbonization in nitrogen, a magnetic mesoporous carbon-based composite microsphere with strong hydrophobic surface is obtained, or by solvent extraction method, a surface functionalized magnetic mesoporous polymer-based composite microsphere is obtained. Patent document CN111250067A discloses a kind of magnetic mesoporous composite material and its preparation method and application, the magnetic mesoporous composite material particle includes at least 1 non-porous or microporous magnetic particle and a mesoporous polymer skeleton penetrating through the composite material particle, the polymer skeleton is a mesoporous polymer layer with at least two characteristic microstructure domains, which combines the advantages of multi-microstructure extraction material and magnetic material, and can achieve better selective separation of target molecules by using molecular exclusion, van der Waals force, dipole interaction, ion exchange and other multiple actions.

[0004] However, the polymer skeleton of the above-mentioned magnetic ordered mesoporous material has low nitrogen content, few functional groups and low reactivity, which is difficult to meet the application requirements of high nitrogen content, and it is necessary to obtain microspheres with strong superparamagnetic response, larger mesoporous channels, regular and ordered core-shell structure, super-high nitrogen content and functional groups of polymer / carbon-based structure, controllable hydrophilicity and hydrophobicity, and easy material transmission and diffusion. SUMMARY

[0005] In view of the deficiencies in the prior art, the first object of the present application is to provide a preparation method of magnetic mesoporous super-high nitrogen content core-shell structure composite microspheres.

[0006] The second object of the present application is to provide the application of the above-mentioned magnetic mesoporous super-high nitrogen content core-shell structure composite microspheres.

[0007] To achieve the above-mentioned purposes, the technical scheme adopted by the present application is:

[0008] The present application provides a preparation method of magnetic mesoporous super-high nitrogen content core-shell structure composite microspheres, comprising the following steps:

[0009] (1) taking magnetic nanoparticles as seeds, depositing a dense silica protective layer on the surface of the magnetic nanoparticles through a sol-gel method to obtain magnetic composite microspheres;

[0010] (2) mixing deionized water and an organic solvent to obtain an oil-water mixed solvent, dispersing the magnetic composite microspheres in the oil-water mixed solvent, and then dispersing a macromolecular block copolymer in the oil-water mixed solvent, and performing ultrasonic dispersion to obtain dispersion liquid A; wherein the macromolecular block copolymer forms micelles in the oil-water mixed solvent as a surfactant, the micelles are uniformly dispersed, and part of the micelles are adsorbed on the surface of the magnetic composite microspheres through intermolecular forces;

[0011] (3) dispersing melamine and formaldehyde in deionized water to form solution B of high-nitrogen prepolymers under the action of an alkaline catalyst;

[0012] (4) adding the dispersion liquid A into the solution B, wherein the micelles and the high-nitrogen prepolymers form composite micelles through hydrogen bond interaction, and further deposit on the surface of the magnetic composite microspheres to obtain a mixed liquid;

[0013] (5) adding an acidic catalyst dropwise into the mixed liquid, and continuing to stir at 100℃ for 6-10h after the addition is completed, so that the prepolymers are further polymerized and the surfactant is loaded in the polymer, to obtain a core-shell structure composite microsphere blank; wherein the structure of the core-shell structure composite microsphere blank from inside to outside is as follows: magnetic nanoparticles / dense silica / surfactant with mesostructure and high-molecular layer with super-high nitrogen content;

[0014] (6) performing post-treatment on the core-shell structure composite microsphere blank to obtain magnetic mesoporous super-high nitrogen content core-shell structure composite microspheres; wherein the post-treatment is selected from one of the following two ways:

[0015] ① calcining and carbonizing the core-shell structure composite microsphere blank in nitrogen, the calcination temperature is 350-800℃, and the calcination time is 2-6h, to obtain magnetic mesoporous super-high nitrogen content carbon-based core-shell structure composite microspheres with strong hydrophobic surface;

[0016] ② removing the macromolecular surface template agent from the core-shell structure composite microsphere blank by a solvent extraction method to obtain magnetic mesoporous super-high nitrogen content polymer-based core-shell structure composite microspheres with strong hydrophilic surface.

[0017] As a preferred, the macromolecular block copolymer is amphiphilic macromolecular block copolymer F127.

[0018] Preferably, the magnetic nanoparticles are magnetic ferroferric oxide particles with a particle size of 50-100 nm.

[0019] Preferably, in step (2), the mass / volume ratio of the magnetic composite microspheres, the organic solvent and the deionized water in the dispersion A is 0.4-0.8 g: 0.5-1.0 mL: 10 mL.

[0020] Preferably, in step (2), the organic solvent is 1,3,5-trimethylbenzene.

[0021] Preferably, in step (3), the basic catalyst is a 0.01 mol / L sodium hydroxide solution.

[0022] Preferably, in step (5), the acidic catalyst is a 1 mol / L hydrochloric acid solution.

[0023] Preferably, in steps (1) and (5), the post-processing steps of separating the magnetic composite microspheres by a magnet and washing the microspheres with a mixed solution of ethanol and water and drying at room temperature are further included.

[0024] The application also provides a use of the magnetic mesoporous super-high nitrogen content core-shell structure composite microspheres as a carrier in adsorption separation, catalysis and drug release, wherein the magnetic mesoporous super-high nitrogen content core-shell structure composite microspheres are obtained by the above method for preparing the magnetic mesoporous super-high nitrogen content core-shell structure composite microspheres.

[0025] Compared with the prior art, the application has the following beneficial effects:

[0026] The application adopts a nano-emulsion assisted interfacial co-assembly method, uses macromolecular block copolymers to form stable micelles in an oil-water system as a soft template, with one end of the micelles infiltrating in an organic phase and the other end exposed outside, and the micelles have sufficient thermodynamic stability due to the low critical micelle concentration, so that the micelles can be stably assembled in melamine formaldehyde resin, and then a stable composite micelle is formed by hydrogen bonding between the hydrophilic end of the micelles and the super-high nitrogen content melamine formaldehyde prepolymer, a surfactant with a mesostructure and a high-molecular layer with super-high nitrogen content are deposited on the surface of pre-prepared dense silica, and after treatment, the magnetic mesoporous super-high nitrogen content core-shell structure composite microspheres are obtained, the self-assembly ability of the nitrogen-containing carbon source precursor is improved by the formed composite micelles, the nitrogen content of the microspheres is improved by selecting a high-nitrogen prepolymer as a precursor, and the prepared magnetic mesoporous super-high nitrogen content core-shell structure composite microspheres have the characteristics of strong superparamagnetic response, large mesoporous channels, regular and ordered core-shell structure, super-high nitrogen content, high-molecular / carbon-based structure of functional groups, controllable hydrophilicity and hydrophobicity, and easy material transmission and diffusion, and can be used as a carrier in the fields of adsorption separation, catalysis, drug release and the like. Attached Figure Description

[0027] Figure 1 This is a TEM image of a magnetic mesoporous core-shell composite microsphere with ultra-high nitrogen content in one embodiment.

[0028] Figure 2 The image shows the TEM morphology of the magnetic mesoporous ultra-high nitrogen content polymer-based core-shell composite microspheres prepared using F127 as a template agent in Example 1.

[0029] Figure 3 The image shows the TEM morphology of the magnetic mesoporous ultra-high nitrogen content carbon-based core-shell composite microspheres prepared using F127 as a template agent in Example 2. Detailed Implementation

[0030] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the description of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0031] Example 1

[0032] This embodiment prepares a magnetic mesoporous core-shell structured composite microsphere with ultra-high nitrogen content, and the steps are as follows:

[0033] (1) 100 mg of magnetic iron oxide particles with a particle size of about 80 nm were uniformly dispersed in 80 mL of ethanol, 40 mL of deionized water and 1 mL of concentrated ammonia (28 wt%), and 0.3 g of tetraethyl orthosilicate (TEOS) was added. The mixture was magnetically stirred at room temperature for 8 h to obtain magnetic composite microspheres with a layer of silica deposited on the surface. The product was separated by a magnet and washed with a mixed solution of ethanol and water. After washing, the product was dried at room temperature for later use.

[0034] (2) Mix 10 mL of deionized water, 0.6 g of F127 and 0.8 mL of 1,3,5-trimethylbenzene (TMB) to obtain an oil-water mixed solvent. Then, ultrasonically disperse the magnetic iron oxide composite microspheres with a dense silica layer deposited on the surface in the oil-water mixed solvent and ultrasonically disperse them to obtain dispersion A.

[0035] (3) Add 0.378g of melamine, 187μL of formaldehyde and 50μL of 0.01mol / L sodium hydroxide solution to 40mL of deionized water, stir and dissolve at 100℃ to obtain solution B;

[0036] (4) Add dispersion A to solution B and stir for 60 minutes to make the solution uniform;

[0037] (5) After the addition of 0.8 mL of 1 mol / L hydrochloric acid is completed, continue to stir rapidly at 100°C for 8 h to obtain composite microspheres with the structure of magnetic magnetite / compact silica / high polymer skeleton containing macromolecular surfactants, collect the product by magnetic separation, and wash with a mixed solution of ethanol and water;

[0038] (6) Extract the obtained composite microsphere blank in 80 mL of ethanol at 80°C for 48 h three times to remove the macromolecular surfactants, wash with deionized water, and dry to obtain magnetic mesoporous super-high-nitrogen-content polymer-based core-shell structure composite microspheres with strong hydrophilic surfaces.

[0039] Example 2

[0040] This example prepares a magnetic mesoporous super-high-nitrogen-content core-shell structure composite microsphere, and the steps are as follows:

[0041] (1) Disperse 100 mg of magnetic magnetite particles with a particle size of about 80 nm uniformly in 80 mL of ethanol, 40 mL of deionized water, and 1 mL of concentrated ammonia water (28 wt.%), add 0.3 g of tetraethyl orthosilicate, and stir magnetically at room temperature for 8 h to obtain magnetic composite microspheres with a layer of silica deposited on the surface. Separate the product by a magnet and wash it with a mixed solution of ethanol and water. After washing, dry the product at room temperature and wait for use;

[0042] (2) Mix 10 mL of deionized water, 0.6 g of F127, and 0.8 mL of 1,3,5-trimethylbenzene to obtain an oil-water mixed solvent. Ultrasonically disperse the magnetic magnetite composite microspheres with a layer of compact silica deposited on the surface in the oil-water mixed solvent to obtain dispersion liquid A;

[0043] (3) Add 0.378 g of melamine, 187 μL of formaldehyde, and 50 μL of 0.01 mol / L sodium hydroxide solution to 40 mL of deionized water, and stir to dissolve at 100°C to obtain solution B;

[0044] (4) Add dispersion liquid A to solution B and stir for 60 min to make the solution uniform;

[0045] (5) Add 0.8 mL of 1 mol / L hydrochloric acid to the mixed solution, and after the addition is complete, continue to stir rapidly at 100°C for 8 h to obtain composite microspheres with the structure of magnetic magnetite / compact silica / high polymer skeleton containing macromolecular surfactants. Collect the product by magnetic separation and wash it with a mixed solution of ethanol and water;

[0046] (6) Calcine and carbonize the obtained composite microsphere blank in nitrogen, with a calcination temperature of 500°C and a calcination time of 6 h, to obtain magnetic mesoporous super-high-nitrogen-content carbon-based core-shell structure composite microspheres with strong hydrophobic surfaces.

[0047] The magnetic mesoporous super-high nitrogen content core-shell structure composite microspheres prepared in Embodiments 1 and 2 can be applied as carriers in the fields of adsorption separation, catalysis, drug release and the like.

[0048] The above only describes the preferred embodiments of the present application, and it should be noted that, for those skilled in the art, several improvements and supplements can be made without departing from the method of the present application, and these improvements and supplements should also be considered as the protection scope of the present application.

Claims

1. A method for preparing magnetic mesoporous super-high nitrogen content core-shell structure composite microspheres, characterized in that, The method comprises the following steps: (1) taking magnetic nanoparticles as seeds, depositing a dense silica protective layer on the surface of the magnetic nanoparticles by a sol-gel method to obtain magnetic composite microspheres; (2) mixing deionized water and an organic solvent to obtain an oil-water mixed solvent, dispersing the magnetic composite microspheres in the oil-water mixed solvent first, then dispersing a macromolecular block copolymer in the oil-water mixed solvent, and fully ultrasonic dispersing to obtain dispersion liquid A; wherein the macromolecular block copolymer serves as a surfactant and a soft template, the lipophilic end is immersed in the organic phase, the hydrophilic end is exposed outside, micelles are formed in the oil-water mixed solvent, the micelles are uniformly dispersed, and part of the micelles are adsorbed on the surface of the magnetic composite microspheres through intermolecular forces; the organic solvent is 1,3,5-trimethylbenzene; (3) dispersing melamine and formaldehyde in deionized water to form solution B of high-nitrogen prepolymers under the action of an alkaline catalyst; (4) adding the dispersion liquid A into the solution B, wherein the micelles and the high-nitrogen prepolymers form composite micelles through hydrogen bond interaction, and are further deposited on the surface of the magnetic composite microspheres to obtain a mixed liquid; (5) adding an acidic catalyst into the mixed liquid dropwise, continuing to stir at 100 ℃ for 6-10 h after the addition is completed, and further polymerizing the prepolymers to load the surfactants in the polymers to obtain a core-shell structure composite microsphere blank; wherein the structure of the core-shell structure composite microsphere blank is, from inside to outside, magnetic nanoparticles / dense silica / surface active agent with mesostructure and high-molecular layer with ultra-high nitrogen content; (6) post-treating the core-shell structure composite microsphere blank to obtain a magnetic mesoporous ultra-high nitrogen content core-shell structure composite microsphere; wherein the post-treatment is selected from one of the following two ways: ① calcining and carbonizing the core-shell structure composite microsphere blank in nitrogen, the calcination temperature is 350-800 ℃, and the calcination time is 2-6 h to obtain a magnetic mesoporous ultra-high nitrogen content carbon-based core-shell structure composite microsphere with strong hydrophobic surface; ② removing the macromolecular surface template by a solvent extraction method to obtain a magnetic mesoporous ultra-high nitrogen content high-molecular-based core-shell structure composite microsphere with strong hydrophilic surface; The macromolecular block copolymer is amphiphilic macromolecular block copolymer F127. In step (2), the mass-volume ratio of the amphiphilic macromolecular block copolymer F127, the magnetic composite microspheres, the organic solvent and the deionized water in the dispersion liquid A is 0.6 g: 0.4-0.8 g: 0.5-1.0 mL: 10 mL.

2. The method for preparing magnetic mesoporous core-shell composite microspheres with ultra-high nitrogen content according to claim 1, characterized in that, The magnetic nanoparticles are magnetic magnetite particles with a particle size of 50-100 nm.

3. The method for preparing magnetic mesoporous ultra-high nitrogen content core-shell structured composite microspheres according to claim 1, characterized in that, In step (3), the alkaline catalyst is a 0.01 mol / L sodium hydroxide solution.

4. The method for preparing magnetic mesoporous ultra-high nitrogen content core-shell structured composite microspheres according to claim 1, characterized in that, In step (5), the acidic catalyst is a 1 mol / L hydrochloric acid solution.

5. The method for preparing magnetic mesoporous ultra-high nitrogen content core-shell structured composite microspheres according to claim 1, characterized in that, In step (1), the magnetic composite microspheres are further treated by separation through a magnet, washing with a mixed solution of ethanol and water, and drying at room temperature.

6. Use of the magnetic mesoporous super-high nitrogen content core-shell structure composite microspheres as a carrier in adsorption separation, catalysis, drug release, wherein the magnetic mesoporous super-high nitrogen content core-shell structure composite microspheres are obtained by the preparation method of the magnetic mesoporous super-high nitrogen content core-shell structure composite microspheres according to any one of claims 1 to 5.

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