阅读说明：本技术 一种表面开孔的空心交联聚合物微球的制备方法 (Preparation method of hollow cross-linked polymer microspheres with open pores on surfaces ) 是由 姜勇 徐倩睿 王志飞 焦真 于 2021-07-30 设计创作，主要内容包括：本发明公开了一种表面开孔的空心交联聚合物微球的制备方法,包括如下步骤：制备交联聚合物微球；将制得的交联聚合物微球分散于不良溶剂中,得到交联聚合物微球分散液；交联聚合物微球分散液的固含量为0.01g/mL；将交联聚合物微球分散液与良溶剂混合,得到交联聚合物微球混合液；将交联聚合物微球混合液置于含有超临界二氧化碳的反应釜中,调节反应釜的温度和压力,使交联聚合物微球吸附超临界二氧化碳达到吸附饱和,在对应的压力和温度下反应不低于7小时后,快速卸压获得表面开孔的空心交联聚合物微球。(The invention discloses a preparation method of hollow cross-linked polymer microspheres with open pores on the surfaces, which comprises the following steps: preparing crosslinked polymer microspheres; dispersing the prepared crosslinked polymer microspheres in a poor solvent to obtain a crosslinked polymer microsphere dispersion liquid; the solid content of the crosslinked polymer microsphere dispersion is 0.01 g/mL; mixing the crosslinked polymer microsphere dispersion liquid with a good solvent to obtain a crosslinked polymer microsphere mixed liquid; and (2) placing the crosslinked polymer microsphere mixed solution into a reaction kettle containing supercritical carbon dioxide, adjusting the temperature and the pressure of the reaction kettle to ensure that the crosslinked polymer microsphere adsorbs the supercritical carbon dioxide to reach adsorption saturation, and quickly releasing pressure to obtain the hollow crosslinked polymer microsphere with open pores on the surface after the reaction is carried out for not less than 7 hours at the corresponding pressure and temperature.)

1. A preparation method of hollow cross-linked polymer microspheres with open pores on the surfaces is characterized by comprising the following steps:

(1) preparing crosslinked polymer microspheres;

(2) dispersing the crosslinked polymer microspheres prepared in the step (1) in a poor solvent to obtain a crosslinked polymer microsphere dispersion liquid;

(3) mixing the crosslinked polymer microsphere dispersion liquid with a good solvent to obtain a crosslinked polymer microsphere mixed liquid;

(4) and (2) placing the crosslinked polymer microsphere mixed solution into a reaction kettle containing supercritical carbon dioxide, adjusting the temperature and the pressure of the reaction kettle to ensure that the crosslinked polymer microsphere adsorbs the supercritical carbon dioxide to reach adsorption saturation, and quickly releasing pressure to obtain the hollow crosslinked polymer microsphere with open pores on the surface after the reaction is carried out for not less than 7 hours at the corresponding pressure and temperature.

2. The method for preparing hollow crosslinked polymer microspheres with open pores on the surface according to claim 1, wherein: in the step (1), the preparation of the crosslinked polymer microspheres specifically comprises the following steps: uniformly dispersing a monomer in a reaction medium to obtain a reaction solution, and introducing nitrogen into a reaction container filled with the reaction solution to carry out bubbling to remove oxygen in the reaction container; and adding an initiator into the reaction liquid to initiate polymerization reaction, adding a cross-linking agent after the polymerization reaction to perform cross-linking reaction, placing the reaction liquid in an ice-water bath to terminate the reaction after the reaction, and performing centrifugal operation after the ice bath to obtain the cross-linked polymer microspheres.

3. The method for preparing hollow crosslinked polymer microspheres with open pores on the surface according to claim 2, wherein: the monomer is one or more of styrene, maleic anhydride, methyl methacrylate, methacrylic acid, hydroxyethyl methacrylate, N-vinyl pyrrolidone, vinyl acetate, ether imide, lactic acid, propylene, ethylene terephthalate, dimethyl siloxane, dianhydride, diamine, ethylene, divinylbenzene, N-methylene bisacrylamide or ethylene glycol dimethacrylate.

4. The method for preparing hollow crosslinked polymer microspheres with open pores on the surface according to claim 1, wherein: in the step (2), the poor solvent is one or a mixture of ethanol, isobutanol, butanol, isopropanol, water, acetonitrile or ethylene glycol according to any proportion.

5. The method for preparing hollow crosslinked polymer microspheres with open pores on the surface according to claim 1, wherein: in the step (2), the solid content of the crosslinked polymer microsphere dispersion is 0.01 g/mL.

6. The method for preparing hollow crosslinked polymer microspheres with open pores on the surface according to claim 1, wherein: in the step (3), the good solvent is one or a mixture of several of dichloromethane, dibutyl phthalate, toluene, tetrahydrofuran, methyl propyl ketone and acetone according to any proportion.

7. The method for preparing hollow crosslinked polymer microspheres with open pores on the surface according to claim 1, wherein: and (4) taking out the crosslinked polymer microspheres subjected to pressure shock reduction in the reaction kettle, and placing the crosslinked polymer microspheres in an ice-water mixture for cooling and shaping.

8. The method for preparing hollow crosslinked polymer microspheres with open pores on the surface according to claim 1, wherein: in the step (4), the reaction temperature of the reaction kettle is 40-50 ℃, and the pressure is 20-25 MPa.

9. The method for preparing hollow crosslinked polymer microspheres with open pores on the surface according to claim 1, wherein: in the step (4), the pressure relief speed is more than 8 Mpa/s.

10. The method for preparing hollow crosslinked polymer microspheres with open pores on the surface according to claim 1, wherein: in the step (4), the size of the hollow cross-linked polymer microsphere with the open pores on the surface is 100 nm-10 mu m, and the pore volume rate is 1-70% (V/V).

Technical Field

The invention relates to a preparation method of hollow cross-linked polymer microspheres with open pores on the surfaces.

Background

With the continuous development and progress of science and technology in recent years, nano materials have been applied to aspects of our lives. Hollow nanostructures are a special class of nanomaterials, and any structure with empty spaces inside can be classified as a "hollow structure" by definition. The hollow structure has unique characteristics and applications in different fields, including micro-nano containers and reactors, optical characteristics and applications, magnetism, energy storage, catalysis, biomedical applications, environmental remediation and sensors. The hollow micro/nano-structure substance with the surface open pores has better future development prospect.

The preparation method has high uniformity and good consistent appearance for preparing the hollow and porous structure nano microspheres. There are generally three main methods for synthesizing hollow structures: (1) a hard template method; (2) a soft template method; (3) a self-templated method. The template method is to prepare a template, cover the outer surface of the template with a layer of shell material, and selectively remove the template to obtain a hollow structure. Although in most manufacturing processes the templates are completely removed without any effect on the composition of the final product, there is still the problem that some templates cannot be completely removed. At the same time, pore size, pore structure and pore morphology are largely dependent on the template used (e.g. silica), while the cumbersome procedure and use of toxic etchants or solvents (e.g. hydrofluoric acid) severely limit their widespread use.

Disclosure of Invention

The purpose of the invention is as follows: the invention provides a preparation method of hollow cross-linked polymer microspheres with open pores on the surface, aiming at the problems of the prior art in preparing hollow and porous structures.

The technical scheme is as follows: the preparation method of the hollow cross-linked polymer microsphere with the open pores on the surface comprises the following steps:

(1) preparing crosslinked polymer microspheres;

(2) dispersing the crosslinked polymer microspheres prepared in the step (1) in a poor solvent to obtain a crosslinked polymer microsphere dispersion liquid; the solid content of the crosslinked polymer microsphere dispersion is 0.01 g/mL;

(3) mixing the crosslinked polymer microsphere dispersion liquid with a good solvent to obtain a crosslinked polymer microsphere mixed liquid;

(4) and (2) placing the crosslinked polymer microsphere mixed solution into a reaction kettle containing supercritical carbon dioxide, adjusting the temperature and the pressure of the reaction kettle to ensure that the crosslinked polymer microsphere adsorbs the supercritical carbon dioxide to reach adsorption saturation, and quickly releasing pressure to obtain the hollow crosslinked polymer microsphere with open pores on the surface after the reaction is carried out for not less than 7 hours at the corresponding pressure and temperature.

Wherein, in the step (1), the preparation of the crosslinked polymer microspheres specifically comprises the following steps: uniformly dispersing a monomer in a reaction medium to obtain a reaction solution, and introducing nitrogen into a reaction container filled with the reaction solution to carry out bubbling to remove oxygen in the reaction container so as to prevent oxygen from quenching free radicals; and adding an initiator into the reaction liquid to initiate polymerization reaction, adding a cross-linking agent after the polymerization reaction to perform cross-linking reaction, placing the reaction liquid in an ice-water bath to terminate the reaction after the reaction, and performing centrifugal operation after the ice bath to obtain the cross-linked polymer microspheres. The cross-linked polymer microsphere comprises a polymer microsphere and a cross-linking agent layer wrapped outside the polymer microsphere, wherein the cross-linking agent and the polymer on the outer surface of the polymer microsphere are subjected to copolymerization reaction, and the cross-linking agent can prevent the polymer on the outer surface of the polymer microsphere from reacting with a good solvent.

The monomer is one or more of styrene, maleic anhydride, methyl methacrylate, methacrylic acid, hydroxyethyl methacrylate, N-vinyl pyrrolidone, vinyl acetate, ether imide, lactic acid, propylene, ethylene terephthalate, dimethyl siloxane, dianhydride, diamine, ethylene, divinylbenzene, N-methylene bisacrylamide or ethylene glycol dimethacrylate.

Wherein, in the step (2), the poor solvent is one or a mixture of ethanol, isobutanol, butanol, isopropanol, water, acetonitrile or ethylene glycol according to any proportion; in the step (3), the good solvent is one or a mixture of several of dichloromethane, dibutyl phthalate, toluene, tetrahydrofuran, methyl propyl ketone and acetone according to any proportion.

And (4) taking out the crosslinked polymeric microspheres subjected to pressure shock reduction in the reaction kettle, and placing the crosslinked polymeric microspheres in an ice-water mixture for cooling and shaping.

Wherein, in the step (4), the reaction temperature of the reaction kettle is 40-110 ℃, and the pressure is 15-25 MPa.

Wherein, in the step (4), the pressure relief speed is more than 8 Mpa/s.

Wherein, in the step (4), the size of the hollow cross-linked polymer microsphere with open pores on the surface is 100 nm-10 μm, and the pore volume rate is 1-70% (V/V).

The preparation mechanism of the crosslinked polymer microsphere of the invention is as follows: along with the reaction, different molecular chains are continuously crosslinked with each other to gradually form a three-dimensional network structure, so that the addition reaction is continuously carried out, microspheres (the microspheres are similar to a wool ball structure) are formed by stirring, and the specific reaction formula is as follows:

(ii) a And adding a cross-linking agent after the polymer microspheres are formed, and carrying out copolymerization reaction on the cross-linking agent and the polymer on the outer surfaces of the polymer microspheres to form the cross-linked polymer microspheres wrapped with the cross-linking agent layer.

The preparation mechanism of the hollow cross-linked polymer microsphere with the open pores on the surface is as follows: placing the crosslinked polymer microsphere mixed solution into a reaction kettle containing supercritical carbon dioxide, adjusting the density (concentration) of the supercritical carbon dioxide by adjusting the temperature and pressure of the reaction kettle, wherein the temperature and pressure of the reaction kettle are different, the adsorption capacity of the crosslinked polymer microsphere to the supercritical carbon dioxide when the supercritical carbon dioxide is saturated is different, in the high-pressure carbon dioxide reaction kettle, the supercritical carbon dioxide is dispersed in the crosslinked polymer microsphere through long-time adsorption and stabilization (the cosolvent acetone enables the supercritical carbon dioxide to enter the crosslinked polymer microsphere), a polymer/gas saturated system with uniform concentration is formed, and the gas concentration in the polymer/gas system can reach 5-20 wt% by controlling certain gas pressure and temperature; through pressure shock drop and/or temperature shock rise, a polymer/gas saturated system rapidly enters a thermodynamically unstable state to form a supersaturated system, gas in the system needs to reach a stable state with low free energy at the moment, a large number of gas nuclei are formed almost simultaneously through homogeneous nucleation and heterogeneous nucleation, supersaturated gas in the system diffuses into the gas nuclei to increase bubbles, the free energy of the system is continuously reduced, a shape-specific cavity is formed in a crosslinked polymer microsphere to convert carbon dioxide from liquid to gas, the gas rushes out from the crosslinked polymer microsphere and takes away good solvent in the polymer microsphere, and pores of a microsphere shell are formed through gas rushing out. The cavity in the center of the polymer microsphere is formed by dissolving the polymer in the center area in a good solvent, the good solvent is taken away by bubbles, and the polymer on the outer surface of the polymer microsphere does not react with the good solvent under the action of a crosslinking agent.

Has the advantages that: compared with a template method, the method does not need to remove a corresponding template at the later stage, so that the production steps and processes are greatly reduced.

Drawings

FIG. 1 is a transmission electron micrograph of hollow crosslinked carboxylated polystyrene microspheres with open pores on the surface, obtained in example 1 under a reaction pressure of 20 MPa;

FIG. 2 is a TEM image of the hollow crosslinked carboxylated polystyrene microspheres with open pores on the surface obtained in example 1 at a reaction pressure of 25 MPa;

FIG. 3 is a TEM image of the cross-linked carboxylated polystyrene microspheres with porous surfaces obtained in example 2 at a stabilization time of 3 hours;

FIG. 4 is a TEM image of open-surface-cell bottleneck-type hollow crosslinked carboxylated polystyrene microspheres obtained in example 2 at a low crosslinking degree;

FIG. 5 is a transmission electron micrograph of hollow crosslinked carboxylated polystyrene microspheres obtained in example 2 in the presence of dichloromethane as a good solvent.

Detailed Description

The technical scheme of the invention is further explained by combining the attached drawings.

Example 1

The invention relates to a preparation method of hollow cross-linked carboxylated polystyrene microspheres with open pores on the surface, which is prepared from the following raw materials in parts by weight: styrene: 20 parts of (1); ammonium persulfate: 0.25 part; divinylbenzene: 1.5 parts; methacrylic acid: 1.5 parts; the method specifically comprises the following steps:

(1) mixing ethanol, water and styrene according to a mass ratio of 9: 5: 0.5, placing the mixture in a reaction vessel, stirring and mixing the mixture evenly by a high-speed stirrer, introducing nitrogen to carry out bubbling to remove oxygen in the reaction vessel, heating the mixture to 75 ℃, adding 0.25 part of ammonium persulfate, initiating polymerization reaction for 2.5 hours, adding 1.5 parts of divinylbenzene and 1.5 parts of methacrylic acid, placing the mixture in an ice-water bath to terminate the reaction after 4 hours of reaction, centrifuging the mixture for 10 minutes at the rotating speed of 10000r/min after the reaction is finished, and cleaning the separated polystyrene microspheres by water and ethanol for at least 3 times;

(2) dispersing the crosslinked carboxylated polystyrene microspheres obtained in the step (1) in poor solvent ethanol to obtain crosslinked carboxylated polystyrene microsphere dispersion liquid; in the crosslinked carboxylated polystyrene microsphere dispersion liquid, the solid content of the carboxylated polystyrene microspheres is 0.01 g/mL; taking 2 parts of cross-linked carboxylated polystyrene microsphere dispersion liquid and 3.5 parts of good solvent acetone, uniformly mixing, placing in a carbon dioxide reaction kettle, adjusting the temperature in the reaction kettle to be 40 ℃ and the pressure to be 20MPa and 25MPa respectively, placing the carbon dioxide reaction kettle under the reaction conditions, stabilizing for 7 hours, and quickly releasing pressure after the reaction is finished to obtain the hollow cross-linked carboxylated polystyrene microsphere with open pores on the surface. The transmission electron microscope photos of the crosslinked carboxylated polystyrene microspheres obtained under different reaction pressures are shown in figures 1-2, and as can be seen from figures 1-2, the crosslinked polystyrene microspheres are hollow inside and have a plurality of through hole structures on the shell. The size of the obtained crosslinked polystyrene microsphere is about 300nm under the pressure of the reaction kettle of 20MPa, the hollow size is about 162nm, and the porosity is 15%; the size of the obtained crosslinked polystyrene microsphere is about 300nm under the pressure of a reaction kettle of 25MPa, the hollow size is about 185nm, and the porosity is 23.8%.

The pressure in the reaction kettle is different, the adsorption capacity of the crosslinked polymer microspheres to supercritical carbon dioxide when the supercritical carbon dioxide is saturated is different, the higher the pressure is, the higher the concentration of carbon dioxide gas in the crosslinked polymer microspheres is, and the pore diameter of the corresponding hollow cavity of the polymer microspheres after pressure relief is larger.

Example 2

The preparation method of the cross-linked carboxylated polystyrene microsphere with porous surface is prepared from the following raw materials in parts by weight: styrene: 20 parts of (1); ammonium persulfate: 0.25 part; divinylbenzene: 1.5 parts; methacrylic acid: 1.5 parts; the method specifically comprises the following steps:

(1) mixing ethanol, water and styrene according to a mass ratio of 9: 5: 0.5, placing the polystyrene microspheres in a reaction container, stirring and mixing the polystyrene microspheres uniformly by a high-speed stirrer, introducing nitrogen to remove oxygen in the reaction container by bubbling, heating the reaction container to 75 ℃, adding 0.25 part of ammonium persulfate, initiating a polymerization reaction for 2.5 hours, adding 1 part of divinylbenzene and 1.5 parts of methacrylic acid, placing the mixture in an ice-water bath to terminate the reaction after reacting for 4 hours, centrifuging the mixture for 10 minutes at the rotating speed of 10000r/min after the reaction is finished, and cleaning the separated polystyrene microspheres for at least 3 times by using water and ethanol; (2) dispersing the crosslinked polystyrene microspheres obtained in the step (1) in a poor solvent ethanol to obtain a crosslinked polystyrene microsphere dispersion liquid; in the crosslinked polystyrene microsphere dispersion, the solid content of the polystyrene microspheres is 0.01 g/mL; taking 2 parts of crosslinked polystyrene microsphere dispersion liquid and 3.5 parts of good solvent acetone, uniformly mixing, placing in a carbon dioxide reaction kettle, adjusting the temperature in the reaction kettle to be 40 ℃ and the pressure to be 20MPa, placing the carbon dioxide reaction kettle under the reaction condition, stabilizing for 3 hours, quickly releasing pressure after the reaction is finished, and placing in an ice water bath for cooling and shaping to obtain the crosslinked polystyrene microsphere with open pores on the surface. The transmission electron micrograph of the obtained crosslinked polystyrene microsphere is shown in fig. 3, and it can be seen from fig. 3 that the crosslinked polystyrene microsphere shell has a porous structure. The size of the crosslinked polystyrene microsphere is about 300nm, the hollow size is about 20nm, and the porosity is 2%.

As can be seen from the comparison between fig. 1 and fig. 3, by adjusting the saturation adsorption time, the longer the saturation adsorption time is, the supercritical carbon dioxide adsorbed in the crosslinked polystyrene microsphere will be gathered at the center of the polymer microsphere to form a sphere, so that a hollow structure will be formed at the center of the polymer microsphere after pressure relief; if the saturated adsorption time is not long enough, the supercritical carbon dioxide adsorbed in the crosslinked polystyrene microspheres is only single small liquid drops, and a large liquid ball is not formed, so that the liquid drops are adsorbed on the inner surface of the polymer microspheres, and the polymer microspheres with porous surfaces are obtained after pressure relief.

Example 3

The invention relates to a preparation method of hollow cross-linked carboxylated polystyrene microspheres with open pores on the surface, which is prepared from the following raw materials in parts by weight: styrene: 20 parts of (1); ammonium persulfate: 0.25 part; divinylbenzene: 1 part; methacrylic acid: 1.5 parts; the method specifically comprises the following steps:

(1) mixing ethanol, water and styrene according to a mass ratio of 9: 5: 0.5, placing the mixture in a reaction vessel, stirring and mixing the mixture evenly by a high-speed stirrer, introducing nitrogen to carry out bubbling to remove oxygen in the reaction vessel, heating the mixture to 75 ℃, adding 0.25 part of ammonium persulfate, initiating polymerization reaction for 2.5 hours, adding 1 part of divinylbenzene and 1.5 parts of methacrylic acid, placing the mixture in an ice-water bath to terminate the reaction after reacting for 4 hours, centrifuging the mixture for 10 minutes at the rotating speed of 10000r/min after the reaction is finished, and cleaning the separated polystyrene microspheres for at least 3 times by water and ethanol;

(2) dispersing the crosslinked polystyrene microspheres obtained in the step (1) in a poor solvent ethanol to obtain a crosslinked polystyrene microsphere dispersion liquid; in the crosslinked polystyrene microsphere dispersion, the solid content of the polystyrene microspheres is 0.01 g/mL; taking 2 parts of crosslinked polystyrene microsphere dispersion liquid and 3.5 parts of good solvent acetone, uniformly mixing, placing in a carbon dioxide reaction kettle, adjusting the temperature in the reaction kettle to be 40 ℃ and the pressure to be 20MPa, placing the carbon dioxide reaction kettle under the reaction condition, stabilizing for 7 hours, quickly releasing pressure after the reaction is finished, and placing in an ice water bath to obtain the hollow crosslinked polystyrene microsphere with open pores on the surface. The transmission electron micrograph of the obtained crosslinked polystyrene microsphere is shown in fig. 4, and as can be seen from fig. 4, the crosslinked polystyrene microsphere is hollow inside and has a through hole structure on the shell. The size of the crosslinked polystyrene microsphere is about 230nm, the hollow size is about 105nm, and the porosity is 10.9%.

As can be seen from a comparison between fig. 1 and fig. 4, in example 1, the degree of crosslinking of the polymer microspheres is 7.5%, in example 3, the degree of crosslinking of the polymer microspheres is 5%, and the polymer microspheres with different degrees of crosslinking can form porous microspheres with different morphology structures through a reaction kettle. The smaller the density of the crosslinked layer is, the better the flexibility of the polymer microsphere is, and the hollow crosslinked polystyrene microsphere with the bottleneck-shaped surface opening can be prepared in the process of releasing pressure by carbon dioxide gas. The rigidity of the crosslinked layer on the outer surface of the polymer microsphere can be changed by adjusting the content of the crosslinking agent.

Example 4

The invention relates to a preparation method of hollow cross-linked carboxylated polystyrene microspheres with open pores on the surface, which is prepared from the following raw materials in parts by weight: styrene: 20 parts of (1); ammonium persulfate: 0.25 part; divinylbenzene: 1.5 parts; methacrylic acid: 1.5 parts; the method specifically comprises the following steps:

(1) mixing ethanol, water and styrene according to a mass ratio of 9: 5: 0.5, placing the mixture in a reaction vessel, stirring and mixing the mixture evenly by a high-speed stirrer, introducing nitrogen to carry out bubbling to remove oxygen in the reaction vessel, heating the mixture to 75 ℃, adding 0.25 part of ammonium persulfate, initiating polymerization reaction for 2.5 hours, adding 1.5 parts of divinylbenzene and 1.5 parts of methacrylic acid, placing the mixture in an ice-water bath to terminate the reaction after 4 hours of reaction, centrifuging the mixture for 10 minutes at the rotating speed of 10000r/min after the reaction is finished, and cleaning the separated polystyrene microspheres by water and ethanol for at least 3 times;

(2) dispersing the crosslinked polystyrene microspheres obtained in the step (1) in a poor solvent ethanol to obtain a crosslinked polystyrene microsphere dispersion liquid; in the crosslinked polystyrene microsphere dispersion, the solid content of the polystyrene microspheres is 0.01 g/mL; taking 2 parts of crosslinked polystyrene microsphere dispersion liquid and 3.5 parts of good solvent dichloromethane, uniformly mixing, placing in a carbon dioxide reaction kettle, adjusting the temperature in the reaction kettle to be 40 ℃ and the pressure to be 20MPa, placing the carbon dioxide reaction kettle under the reaction condition, stabilizing for 7 hours, quickly releasing pressure after the reaction is finished, and placing in an ice water bath to obtain the hollow crosslinked polystyrene microsphere with open pores on the surface. The transmission electron micrograph of the obtained crosslinked polystyrene microsphere is shown in FIG. 5, and it can be seen from FIG. 5 that the crosslinked polystyrene microsphere is hollow inside. The size of the crosslinked polystyrene microsphere is about 330nm, the hollow size is about 190nm, and the porosity is 19%.

As can be seen from FIGS. 1 and 5, hollow crosslinked polystyrene microspheres with open surfaces can be prepared by using different good solvents. In example 1, the good solvent is acetone, and in example 4, the good solvent is dichloromethane, and hollow crosslinked polystyrene microspheres can be formed by passing through a reaction kettle.

Example 5

The invention relates to a preparation method of hollow cross-linked polystyrene maleic anhydride microspheres with open pores on the surface, which is prepared from the following raw materials in parts by weight: styrene: 20 parts of (1); maleic anhydride: 20 parts of (1); ammonium persulfate: 0.5 part; divinylbenzene: 2 parts of (1); the method specifically comprises the following steps:

(1) mixing ethanol, water, styrene and maleic anhydride according to a mass ratio of 9: 5: 0.5: 0.5, placing the mixture in a reaction vessel, stirring and mixing the mixture uniformly by a high-speed stirrer, introducing nitrogen to carry out bubbling to remove oxygen in the reaction vessel, heating the mixture to 75 ℃, adding 0.5 part of ammonium persulfate, initiating polymerization reaction for 2.5 hours, adding 2 parts of divinylbenzene, placing the mixture in an ice water bath to terminate the reaction after the reaction is carried out for 4 hours, centrifuging the mixture for 10 minutes at the rotating speed of 10000r/min after the reaction is finished, and cleaning the separated polystyrene maleic anhydride microspheres for at least 3 times by using water and ethanol;

(2) dispersing the crosslinked polystyrene maleic anhydride microspheres obtained in the step (1) in poor solvent ethanol to obtain crosslinked polystyrene maleic anhydride microsphere dispersion liquid; in the crosslinked polystyrene maleic anhydride microsphere dispersion liquid, the solid content of the polystyrene maleic anhydride microspheres is 0.01 g/mL; taking 2.5 parts of crosslinked polystyrene maleic anhydride microsphere dispersion liquid and 4 parts of good solvent dichloromethane, uniformly mixing, placing in a carbon dioxide reaction kettle, adjusting the temperature in the reaction kettle to be 40 ℃ and the pressure to be 20MPa, placing the carbon dioxide reaction kettle under the reaction condition, stabilizing for 7 hours, and quickly releasing pressure after the reaction is finished to obtain the hollow crosslinked polystyrene maleic anhydride microspheres with open pores on the surfaces.

Example 6

The invention relates to a preparation method of hollow cross-linked polymethyl methacrylate microspheres with open pores on the surface, which is prepared from the following raw materials in parts by weight: methyl methacrylate: 5 parts of a mixture; polyvinylpyrrolidone: 1.5 parts; azobisisobutyronitrile: 0.05 part; ethylene glycol dimethacrylate: 0.5 part; the method specifically comprises the following steps:

(1) mixing ethanol, water and methyl methacrylate according to a mass ratio of 1: 1: 0.2, placing the mixture in a reaction vessel, adding 1.5 parts of polyvinylpyrrolidone into the reaction vessel, stirring and mixing the mixture uniformly by a high-speed stirrer, introducing nitrogen to remove oxygen in the reaction vessel by bubbling, heating the mixture to 75 ℃, adding 0.05 part of azodiisobutyronitrile, initiating a polymerization reaction for 2.5 hours, adding 0.5 part of ethylene glycol dimethacrylate, placing the mixture in an ice-water bath to terminate the reaction after the reaction is carried out for 4 hours, centrifuging the mixture for 10 minutes at a rotating speed of 10000r/min after the reaction is finished, and cleaning the separated polymethyl methacrylate microspheres by water and ethanol for at least 3 times;

(2) dispersing the crosslinked polymethyl methacrylate microspheres obtained in the step (1) in poor solvent ethanol to obtain crosslinked polymethyl methacrylate microsphere dispersion liquid; in the crosslinked polymethyl methacrylate microsphere dispersion liquid, the solid content of the polymethyl methacrylate microspheres is 0.01 g/mL; uniformly mixing 1 part of crosslinked polymethyl methacrylate microsphere dispersion liquid and 2 parts of good solvent acetone, placing the mixture into a carbon dioxide reaction kettle, adjusting the temperature in the reaction kettle to be 40 ℃ and the pressure to be 20MPa, placing the carbon dioxide reaction kettle under the reaction conditions, stabilizing for 7 hours, and quickly releasing pressure after the reaction is finished to obtain the hollow crosslinked polymethyl methacrylate microsphere with open pores on the surface.

Example 7

The invention relates to a preparation method of a hollow cross-linked polymethyl methacrylate/methacrylic acid microsphere with an open pore on the surface, which is prepared from the following raw materials in parts by weight: methyl methacrylate: 5 parts of a mixture; polyvinyl alcohol: 0.5 part; azobisisobutyronitrile: 0.05 part; ethylene glycol dimethacrylate: 0.5 part; methacrylic acid: 0.5 part; the method specifically comprises the following steps:

(1) mixing ethanol, water and methyl methacrylate according to a mass ratio of 1: 1: 0.2, placing the mixture in a reaction vessel, adding 0.5 part of polyvinyl alcohol into the reaction vessel, stirring and mixing the mixture uniformly by a high-speed stirrer, introducing nitrogen to remove oxygen in the reaction vessel by bubbling, heating the mixture to 75 ℃, adding 0.05 part of azobisisobutyronitrile, initiating a polymerization reaction for 2.5 hours, adding 0.5 part of ethylene glycol dimethacrylate and 0.5 part of methacrylic acid, placing the mixture in an ice-water bath to stop the reaction after the reaction is carried out for 4 hours, centrifuging the mixture for 10 minutes at a rotating speed of 10000r/min after the reaction is finished, and cleaning the separated polymethyl methacrylate/methacrylic acid microspheres by water and ethanol for at least 3 times;

(2) dispersing the crosslinked polymethyl methacrylate/methacrylic acid microspheres obtained in the step (1) in poor solvent ethanol to obtain crosslinked polymethyl methacrylate/methacrylic acid microsphere dispersion liquid; in the crosslinked polymethyl methacrylate/methacrylic acid microsphere dispersion liquid, the solid content of the polymethyl methacrylate/methacrylic acid microspheres is 0.01 g/mL; uniformly mixing 1 part of crosslinked polymethyl methacrylate/methacrylic acid microsphere dispersion and 2 parts of good solvent acetone, placing the mixture into a carbon dioxide reaction kettle, adjusting the temperature in the reaction kettle to be 40 ℃ and the pressure to be 20MPa, placing the carbon dioxide reaction kettle under the reaction conditions, stabilizing for 7 hours, and quickly releasing pressure after the reaction is finished to obtain the hollow crosslinked polymethyl methacrylate/methacrylic acid microsphere with open pores on the surface.

Example 8

The invention relates to a preparation method of hollow cross-linked poly (hydroxyethyl methacrylate)/N-vinyl pyrrolidone microspheres with open pores on the surface, which is prepared from the following raw materials in parts by weight: hydroxyethyl methacrylate: 2 parts of (1); n-vinylpyrrolidone: 2 parts of (1); span 60: 5 parts of a mixture; ammonium persulfate: 0.05 part; n, N-methylenebisacrylamide: 0.5 part; methacrylic acid: 0.5 part; the method specifically comprises the following steps:

(1) mixing ethanol, hydroxyethyl methacrylate and N-vinyl pyrrolidone according to a mass ratio of 2.5: 2: 2, placing the mixture in a reaction vessel, adding 605 parts of Span into the reaction vessel, stirring and mixing the mixture uniformly by a high-speed stirrer, introducing nitrogen to remove oxygen in the reaction vessel by bubbling, heating the mixture to 70 ℃, adding 0.05 part of ammonium persulfate, initiating a polymerization reaction for 2.5 hours, adding 0.5 part of N, N-methylene bisacrylamide and 0.5 part of methacrylic acid, placing the mixture in an ice water bath to terminate the reaction after the reaction is carried out for 4 hours, centrifuging the mixture for 10 minutes at a rotating speed of 10000r/min after the reaction is finished, and cleaning the separated polyhydroxyethyl methacrylate/N-vinyl pyrrolidone microspheres by water and ethanol for at least 3 times;

(2) dispersing the crosslinked poly (hydroxyethyl methacrylate)/N-vinyl pyrrolidone microspheres obtained in the step (1) in poor solvent ethanol to obtain a crosslinked poly (hydroxyethyl methacrylate)/N-vinyl pyrrolidone microsphere dispersion liquid; in the crosslinked poly (hydroxyethyl methacrylate)/N-vinyl pyrrolidone microsphere dispersion, the solid content of the poly (hydroxyethyl methacrylate)/N-vinyl pyrrolidone microspheres is 0.01 g/mL; uniformly mixing 1 part of crosslinked polyhydroxyethyl methacrylate/N-vinyl pyrrolidone microsphere dispersion liquid and 2 parts of good solvent toluene, placing the mixture into a carbon dioxide reaction kettle, adjusting the temperature in the reaction kettle to be 40 ℃ and the pressure to be 20MPa, placing the carbon dioxide reaction kettle under the reaction conditions, stabilizing for 7 hours, and quickly releasing pressure after the reaction is finished to obtain the hollow crosslinked polyhydroxyethyl methacrylate/N-vinyl pyrrolidone microspheres with open pores on the surfaces.

Example 9

The invention relates to a preparation method of a hollow cross-linked polymethyl methacrylate/polymethyl methacrylate-2-hydroxyethyl composite microsphere with open pores on the surface, which is prepared from the following raw materials in parts by weight: 2-hydroxyethyl methacrylate: 5 parts of a mixture; methyl methacrylate: 0.5 part; potassium persulfate: 0.05 part; ethylene glycol dimethacrylate: 0.5 part; sodium lauryl sulfate: 0.07 part; benzoyl peroxide: 0.06 part; the method specifically comprises the following steps:

(1) mixing water and 2-hydroxyethyl methacrylate according to the weight ratio of 1: 0.2, adding 0.07 part of sodium dodecyl sulfate and 0.25 part of ethylene glycol dimethacrylate, putting the mixture into an ultrasonic emulsification reactor, and emulsifying for later use; water and methyl methacrylate were additionally mixed as 5: 1, adding 0.06 part of benzoyl peroxide and 0.25 part of ethylene glycol dimethacrylate, placing the mixture in a reactor, uniformly stirring and mixing the mixture by a high-speed stirrer, introducing nitrogen to perform bubbling to remove oxygen in a reaction container, heating to 80 ℃, adding 0.05 part of potassium persulfate, initiating polymerization reaction for 1 hour, adding emulsified 2-hydroxyethyl methacrylate, placing the mixture in an ice water bath to terminate the reaction after reacting for 4 hours, centrifuging the mixture for 10 minutes at the rotating speed of 10000r/min after the reaction is finished, and cleaning the separated polymethyl methacrylate/2-hydroxyethyl methacrylate composite microspheres for at least 3 times by using water and ethanol;

(2) dispersing the crosslinked polymethyl methacrylate/polymethyl methacrylate-2-hydroxyethyl methacrylate composite microspheres obtained in the step (1) in poor solvent ethanol to obtain crosslinked polymethyl methacrylate/polymethyl methacrylate-2-hydroxyethyl methacrylate composite microsphere dispersion liquid; in the crosslinked polymethyl methacrylate/polymethyl methacrylate-2-hydroxyethyl ester composite microsphere dispersion, the solid content of the polymethyl methacrylate/polymethyl methacrylate-2-hydroxyethyl ester composite microsphere is 0.01 g/mL; uniformly mixing 1 part of crosslinked polymethyl methacrylate/polymethyl methacrylate-2-hydroxyethyl composite microsphere dispersion liquid and 2 parts of good solvent acetone, placing the mixture in a carbon dioxide reaction kettle, adjusting the temperature in the reaction kettle to be 40 ℃ and the pressure to be 20MPa, placing the carbon dioxide reaction kettle under the reaction conditions, stabilizing for 7 hours, and quickly releasing pressure after the reaction is finished to obtain the hollow crosslinked polymethyl methacrylate/polymethyl methacrylate-2-hydroxyethyl composite microsphere with open pores on the surface.

Example 10

The invention relates to a preparation method of hollow cross-linked polyvinyl acetate microspheres with open pores on the surface, which is prepared from the following raw materials in parts by weight: vinyl acetate: 5 parts of a mixture; polyvinyl alcohol: 0.15 part; azobisisobutyronitrile: 0.05 part; divinylbenzene: 0.5 part; the method specifically comprises the following steps:

(1) mixing water, vinyl acetate and divinylbenzene according to a mass ratio of 1: 0.2: 0.01, adding 0.15 part of polyvinyl alcohol, placing the mixture into a reaction container, stirring and mixing the mixture uniformly by a high-speed stirrer, introducing nitrogen to remove oxygen in the reaction container by bubbling, heating to 65 ℃, adding 0.05 part of azobisisobutyronitrile, initiating polymerization for 4 hours, placing the mixture into an ice water bath to terminate the reaction, centrifuging the mixture for 10 minutes at a rotation speed of 10000r/min after the reaction is finished, and cleaning the separated polyvinyl acetate microspheres by water and ethanol for at least 3 times;

(2) dispersing the crosslinked polyvinyl acetate microspheres obtained in the step (1) in a poor solvent ethanol to obtain a crosslinked polyvinyl acetate microsphere dispersion liquid; in the crosslinked polyvinyl acetate microsphere dispersion liquid, the solid content of the polyvinyl acetate microspheres is 0.01 g/mL; uniformly mixing 1 part of crosslinked polyvinyl acetate microsphere dispersion and 2 parts of good solvent acetone, placing the mixture into a carbon dioxide reaction kettle, adjusting the temperature in the reaction kettle to be 40 ℃ and the pressure to be 20MPa, placing the carbon dioxide reaction kettle under the reaction conditions, stabilizing for 7 hours, and quickly releasing pressure after the reaction is finished to obtain the hollow crosslinked polyvinyl acetate microsphere with open pores on the surface.

According to the invention, the adsorption quantity of the crosslinked polymer microspheres to the supercritical carbon dioxide when the crosslinked polymer microspheres reach adsorption saturation is changed by adjusting the pressure and the temperature in the supercritical carbon dioxide reaction kettle, so that the concentration of the supercritical carbon dioxide is changed, the gas concentration of the supercritical carbon dioxide in the crosslinked polystyrene microspheres is different during saturation adsorption, and the pore diameters and the sizes of cavities in the corresponding crosslinked polymer microspheres after pressure relief are different, so that the sizes and the distribution of the micro-nano structure are adjusted.