Preparation method and application of polystyrene-divinyl benzene composite microspheres

Abstract

The invention relates to the technical field of high polymer materials, and discloses a preparation method and application of polystyrene-divinyl benzene composite microspheres, and an environment-friendly solvent system, such as a water-based or non-toxic organic solvent, is adopted to replace a traditional organic solvent. The solvent pollution risk can be reduced by using water-phase emulsion polymerization, meanwhile, the recovery and treatment of the solvent are simplified, the surfactant is optimized, the low-toxicity and environment-friendly surfactant is selected for emulsion stabilization, and chemical substances harmful to the environment and the human body are prevented from being used. By optimizing a polymerization process, accurately controlling the crosslinking degree and introducing a green solvent and an environment-friendly surface modification method, the improved polystyrene-divinyl benzene composite microsphere overcomes some defects (such as high cost, non-uniform particle size, difficulty in controlling the crosslinking degree and the like) in the prior art; in addition, the method has wider application potential in a plurality of fields (such as coatings, medicines and catalysis), and has better environmental protection property, health safety and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and specifically to a preparation method and application of polystyrene-divinylbenzene composite microspheres. Background Art

[0002] Polystyrene-divinylbenzene composite microspheres are a kind of particulate materials with special structures and properties, usually prepared by suspension polymerization or emulsion polymerization methods. During the preparation process, polystyrene (PS) and divinylbenzene (DVB) are used together as monomers for polymerization reactions, and composite microspheres with relatively high mechanical strength and chemical stability are formed through cross-linking effects. The surfaces of these microspheres can be functionalized by changing the polymerization conditions, endowing them with different surface properties, such as hydrophobicity, hydrophilicity, or catalytic activity. They have a wide range of applications, especially important applications can be found in coatings, inks, adhesives, pharmaceutical delivery systems, environmental catalysis, adsorbents, and high-performance composite materials. Due to their excellent stability, adjustable pore structures, and functionalization characteristics, polystyrene-divinylbenzene composite microspheres show great potential in various industrial and scientific fields.

[0003] Although the preparation methods and applications of polystyrene-divinylbenzene composite microspheres have shown extensive potential in many fields, there are still some drawbacks and challenges in the existing technologies, mainly including the following aspects: The preparation process is complex and costly: The currently commonly used suspension polymerization or emulsion polymerization methods require precise control of reaction conditions (such as temperature, solvent, catalyst, etc.), and often require a long reaction time, which makes the production process relatively complex and the production cost relatively high; The particle size distribution is uneven: Although the particle size of polystyrene-divinylbenzene composite microspheres can be controlled by adjusting the polymerization conditions, in actual production, the particle size distribution may be uneven, affecting the application performance of the microspheres. For example, in some application scenarios, the consistency of particle size has high requirements for the performance of the final product, and uneven particle size distribution may reduce the overall effect of the material; Difficult to control the crosslinking degree: As a crosslinking agent, excessive or insufficient use of divinylbenzene may lead to unstable performance of polystyrene microspheres. When the crosslinking degree is too high, the plasticity of the microspheres is poor and they are prone to becoming brittle; When the crosslinking degree is too low, the mechanical properties and chemical stability of the microspheres are insufficient. Therefore, precisely controlling the crosslinking degree is a technical problem; Difficult to functionalize: During the functionalization (such as hydrophilicity, hydrophobicity, etc.) of the surface of the composite microspheres, problems such as unsatisfactory surface modification effects are often faced, especially in terms of the uniformity and stability of the surface coating of the microspheres. The instability during the functionalization process may affect its performance in specific applications; Environmental and health risks: Some chemical substances such as organic solvents and catalysts used in the preparation process have certain environmental pollution and health risks. Especially in large-scale production, the management and treatment of these chemicals are problems that must be solved; Application limitations: Although polystyrene-divinylbenzene composite microspheres have application potential in many fields, their performance in some specific scenarios is still limited. For example, in high-temperature or strong acid-base environments, the stability of the composite microspheres may be affected, restricting their application scope in some industrial applications.

[0004] Therefore, we propose a preparation method and application of polystyrene-divinylbenzene composite microspheres. Summary of the Invention

[0005] To achieve the above object, the present invention provides the following technical solutions: A preparation method and application of polystyrene-divinylbenzene composite microspheres, including the following steps:

[0006] S1 Polymerization reaction

[0007] S1.1: Selection of green solvents: Use environmentally friendly solvent systems, such as water-based or non-toxic organic solvents (e.g., ethanol), to replace traditional organic solvents. Using aqueous emulsion polymerization can reduce the risk of solvent pollution and simplify the recovery and treatment of solvents. Optimization of surfactants: Select low-toxicity, environmentally friendly surfactants (such as surfactants of natural origin) for emulsion stabilization, and avoid using chemicals harmful to the environment and human body;

[0008] S1.2: Temperature and pressure control: Optimize the polymerization reaction rate by precisely controlling the reaction temperature and pressure. More efficient reactor designs, such as microchannel reactors, can be used to improve the reaction efficiency and reduce the generation of by-products. Optimization of monomer ratio: By optimizing the ratio of polystyrene (PS) and divinylbenzene (DVB) monomers, precisely control the crosslinking degree of the microspheres to obtain composite microspheres with good mechanical properties and not easily embrittled;

[0009] S1.3: Introduction of crosslinking agent regulators: Introduce crosslinking regulators (such as a small amount of crosslinking regulators or modifiers) during the polymerization process to achieve precise control of the crosslinking degree. This can improve its stability and heat resistance without sacrificing the flexibility of the microspheres. Step-by-step crosslinking process: Through a staged polymerization process, gradually add divinylbenzene to achieve gradient control of the crosslinking degree, thereby avoiding excessive crosslinking.

[0010] S2 Functional surface modification

[0011] S2.1: Modify the surface of the microspheres by adding functional monomers during the polymerization process or by post-surface grafting methods. For example, select hydrophilic or hydrophobic functional monomers (such as vinyl ether compounds, amino or carboxyl compounds) to make the surface of the microspheres have good water dispersibility or enhance compatibility with other materials. Solvent-free modification method: Adopt solvent-free modification methods such as gas-phase graft polymerization, which avoids environmental pollution problems caused by the use of traditional solvents and can achieve a more uniform and stable functional coating;

[0012] S2.2: Multistage surface modification: Achieve a multifunctional surface of the microspheres by adopting a multi-step surface modification method. For example, graft hydrophilic monomers in the first step and specific catalytic or adsorption functional monomers in the second step, enabling them to provide different functions in different application scenarios.

[0013] S3 Drying and recovery of microspheres

[0014] S3.1: Dry the microspheres using low-temperature vacuum drying technology. This method can not only reduce thermal damage but also prevent the microspheres from breaking;

[0015] S3.2: After drying, use mechanical screening or centrifugal separation technology to classify the microspheres, thereby obtaining a relatively uniform particle size distribution.

[0016] Application Performance Optimization of S4 Microspheres

[0017] S4.1: In coatings and adhesives, the modified polystyrene-divinylbenzene composite microspheres can be used as synergistic fillers to improve the mechanical strength, weather resistance, and UV resistance of coatings. Due to their excellent surface functionalization characteristics, these composite microspheres can enhance the adhesion and water resistance of coatings and are suitable for high-demand architectural coatings and exterior wall thermal insulation coatings;

[0018] S4.2: Through surface modification, the composite microspheres have better biocompatibility and targeting in the medical field. Drugs can be encapsulated inside the microspheres, and the controlled release of drugs can be achieved by adjusting their crosslinking degree. The microspheres can also be used in sustained release systems to avoid the rapid release of drugs in the body, extend the efficacy time, and reduce side effects;

[0019] S4.3: In the field of environmental protection, the modified composite microspheres can be used as adsorbents for water treatment to remove heavy metal ions, organic pollutants, etc. in water. The surface functionalization of the microspheres enhances their adsorption capacity and selectivity, and due to their high stability, they can be used for a long time in relatively harsh environments. In the field of catalysis, the microspheres can be used as catalytic carriers for gas or liquid catalytic reactions by loading catalysts, with good regenerability and catalytic efficiency.

[0020] S5 Environmental Protection and Health Safety

[0021] S5.1: Its preparation method uses environmentally friendly solvents and catalysts, reducing the harm to the environment and human body. At the same time, solvent-free modification technology and water-based emulsion polymerization methods are adopted to effectively reduce the emissions of harmful gases and solvents. During the production process, high-temperature and high-pressure operations are minimized to reduce safety hazards and ensure the safety of the production environment.

[0022] Preferably, in step S1, a suitable environmentally friendly solvent is selected, such as ethanol, water, or non-toxic solvents, etc. For emulsion polymerization, water can be used as the solvent to avoid using toxic organic solvents. By adjusting the solvent ratio, the stability of the reaction system is optimized. Selection of surfactants: Select non-toxic and low-irritating natural surfactants, such as chitosan or polyvinyl alcohol (PVA), to stabilize the emulsion. Using these natural components can effectively reduce environmental pollution and avoid the impact of traditional surfactants on human health. In the experiment, a constant-temperature reactor, such as a water bath or a thermal circulation reactor, is used to ensure that the reaction temperature is maintained within an ideal range (generally 60 - 80 °C), avoiding side reactions caused by too high a temperature or too slow a polymerization rate due to too low a temperature. Pressure control: The reaction kettle is equipped with an automatic pressure regulation function to ensure that the pressure is within the range of 10 - 20 MPa, thereby avoiding solvent volatilization or incomplete reaction. Optimization of monomer ratio: Adjust the ratio of polystyrene to divinylbenzene according to different target properties. The best ratio can be selected through small-scale experiments before the reaction, such as PS / DVB = 90:10 or 80:20, to avoid excessive cross-linking caused by excessive divinylbenzene. Addition of cross-linking regulator: During the polymerization process, an appropriate amount of cross-linking regulator is added, such as a small amount of trivinyltrisilane or other cross-linking regulating molecules. By adjusting the timing of its addition (such as adding gradually instead of all at once), the cross-linking reaction is controlled. The divinylbenzene is added in stages by gradually adding it (such as adding 10% first, and then adding the remaining part when the reaction proceeds to a certain extent), and the cross-linking degree is optimized in this way.

[0023] Preferably, in step S2, suitable functional monomers are selected, such as acrylic acid, vinylbenzene, amino compounds, etc. These monomers can undergo chemical reactions with the surface of the microspheres to form a functionalized coating. For example, acrylic acid can be added to obtain hydrophilicity, or the surface compatibility with other materials can be enhanced by introducing amino or methyl functional groups. Implementation of the functionalization process: The radical polymerization method is used. After the polymerization is completed, a functional monomer, such as acrylic acid or epoxide, is added to the reaction system, and then surface grafting or post-polymerization reaction is carried out. This process can be carried out under low-temperature conditions through a simple reflux reaction to avoid side reactions caused by high temperature. On the surface of the microspheres, first, a hydrophilic monomer is used for a primary functionalization modification, and then different subsequent reactions are used to further introduce hydrophobicity or other special functions (such as metal catalysis, adsorption function). The specific method is to perform surface cleaning after the first modification to remove unreacted monomers, and then introduce the second modification reaction. This process can be completed by the solvation method or the gas-phase grafting method.

[0024] Preferably, in step S3, a low-temperature vacuum drying device (such as a vacuum drying oven or a spray dryer) is used, and the temperature is controlled below 50°C while maintaining a low-pressure environment (such as 10 - 20 kPa) to avoid damaging the microsphere structure due to excessive temperature. Through the vacuum state, moisture and solvents will evaporate rapidly, and the drying process is milder, which can maintain the shape and structure stability of the microspheres. After drying, the microspheres are classified according to the particle size distribution by mechanical screening or vibrating screening technology. The aperture of the sieve is adjusted according to the required particle size range (such as gradually screening through sieve meshes with apertures of 300 μm, 500 μm, etc.). Centrifugal separation: For microspheres with uneven particle size distribution, a centrifuge can be used to further classify the microspheres by differential centrifugal separation to ensure a more uniform particle size distribution.

[0025] Preferably, in step S4, the prepared composite microspheres are added to the coating, and the microspheres can enhance the hardness, ultraviolet resistance, and corrosion resistance of the coating. In adhesives, the microspheres can improve the adhesion force, especially the adhesion performance at high temperatures. At this time, an appropriate amount of surface modifier (such as polyvinyl alcohol) needs to be added to the microspheres to increase the dispersibility and stability of the microspheres in the coating or adhesive. The drug (such as an antibiotic or an anticancer drug) is dissolved in the reaction solution, and as the polymerization reaction proceeds, the drug is embedded inside the polystyrene-divinylbenzene composite microspheres. By adjusting the crosslinking degree, the slow release of the drug can be achieved. An in vitro drug release experiment (such as the dialysis method) is used to evaluate the release performance of the microspheres to ensure that the drug can be gradually released within a specific time range. When the microspheres are used for water treatment, their adsorption capacity for heavy metal ions (such as lead and mercury) or organic pollutants (such as benzene compounds) is improved through surface functionalization. The microspheres remove harmful substances in water through adsorption, and their adsorption capacity can be restored by washing or using a chemical regenerant after use. Catalyst carrier application: In catalytic applications, the microspheres can be used as catalyst carriers, and catalysts such as metal nanoparticles are loaded on the surface of the microspheres for catalytic reactions. During the reaction process, the functional groups on the surface of the microspheres can improve the dispersibility and activity of the catalyst, thereby enhancing the catalytic effect.

[0026] Preferably, in step S5, harmful solvents, catalysts, or toxic additives are avoided. In the process implementation, non-toxic solvents and pollution-free reaction materials are used as much as possible, and it is ensured that all waste can be effectively treated. The improved polymerization process uses low-temperature and low-pressure reactions to reduce energy consumption and environmental impact. The equipment also selects an automated and precision control system to further reduce human errors and ensure the safety and controllability of the reaction process.

[0027] Compared with the prior art, the present invention provides a method for preparing polystyrene-divinylbenzene composite microspheres and its applications, having the following beneficial effects:

[0028] The preparation method and application of the polystyrene-divinylbenzene composite microspheres, by optimizing the polymerization process, precisely controlling the crosslinking degree, introducing green solvents and environmentally friendly surface modification methods, the improved polystyrene-divinylbenzene composite microspheres not only solve some disadvantages in the prior art (such as high cost, uneven particle size, difficult crosslinking degree control, etc.), but also have broader application potential in multiple fields (such as coatings, medicine, environmental protection, catalysis, etc.), and have good environmental protection and health safety. Detailed implementation manners

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0030] Embodiment

[0031] An embodiment of the preparation method and application of the polystyrene-divinylbenzene composite microspheres

[0032] A preparation method and application of the polystyrene-divinylbenzene composite microspheres, comprising the following steps:

[0033] S1 Polymerization reaction

[0034] S1.1: Selection of green solvents: An environmentally friendly solvent system is adopted, such as an aqueous-based or non-toxic organic solvent (such as ethanol), to replace the traditional organic solvent. Using aqueous emulsion polymerization can reduce the risk of solvent pollution and simplify the recovery and treatment of solvents. Optimization of surfactants: Surfactants with low toxicity and environmental friendliness (such as surfactants of natural origin) are selected for emulsion stabilization, and chemicals harmful to the environment and human body are avoided;

[0035] S1.2: Temperature and pressure control: By precisely regulating the reaction temperature and pressure, the polymerization reaction rate is optimized. A more efficient reactor design can be adopted, such as a microchannel reactor, to improve the reaction efficiency and reduce the generation of by-products. Optimization of monomer ratio: By optimizing the ratio of polystyrene (PS) and divinylbenzene (DVB) monomers, the crosslinking degree of the microspheres is precisely controlled to obtain composite microspheres with both good mechanical properties and not easily brittle;

[0036] S1.3: Introduce crosslinking agent regulator: During the polymerization process, introduce a crosslinking regulator (such as a small amount of crosslinking regulator or modifier) to achieve precise control of the crosslinking degree. This can enhance its stability and heat resistance without sacrificing the flexibility of the microspheres. Step-by-step crosslinking process: Through a staged polymerization process, add divinylbenzene step by step to achieve gradient regulation of the crosslinking degree, thus avoiding excessive crosslinking.

[0037] S2 Functional surface modification

[0038] S2.1: Modify the surface of the microspheres by adding functional monomers during the polymerization process or by post-surface grafting methods. For example, select hydrophilic or hydrophobic functional monomers (such as vinyl ether compounds, amino or carboxyl compounds) to make the surface of the microspheres have good water dispersibility or enhance compatibility with other materials. Solvent-free modification method: Adopt solvent-free modification methods such as gas-phase graft polymerization, which avoids environmental pollution problems caused by the use of traditional solvents and can achieve a more uniform and stable functional coating.

[0039] S2.2: Multistage surface modification: Achieve a multifunctional surface of the microspheres by adopting a multi-step surface modification method. For example, graft hydrophilic monomers in the first step and specific catalytic or adsorption functional monomers in the second step, enabling them to provide different functions in different application scenarios.

[0040] S3 Drying and recovery of microspheres

[0041] S3.1: Dry the microspheres using low-temperature vacuum drying technology. This method can not only reduce thermal damage but also prevent the microspheres from breaking.

[0042] S3.2: After drying, use mechanical sieving or centrifugal separation technology to classify the microspheres, thereby obtaining a relatively uniform particle size distribution.

[0043] S4 Optimize the application performance of microspheres

[0044] S4.1: In coatings and adhesives, the modified polystyrene-divinylbenzene composite microspheres can be used as synergistic fillers to enhance the mechanical strength, weather resistance, and UV resistance of the coating. Due to their excellent surface functionalization characteristics, these composite microspheres can enhance the adhesion and water resistance of the coating and are suitable for high-demand architectural coatings and exterior wall thermal insulation coatings.

[0045] S4.2: Through surface modification, the composite microspheres have better biocompatibility and targeting in the medical field. Drugs can be encapsulated inside the microspheres, and the controlled release of drugs can be achieved by using the adjusted crosslinking degree. The microspheres can also be used in sustained-release systems to avoid the rapid release of drugs in the body, extend the therapeutic effect time, and reduce side effects.

[0046] S4.3: In the field of environmental protection, the improved composite microspheres can be used as adsorbents for water treatment to remove heavy metal ions, organic pollutants, etc. in water. The surface functionalization of the microspheres enhances their adsorption capacity and selectivity, and due to their high stability, they can be used for a long time in relatively harsh environments. In the field of catalysis, the microspheres can be used as catalytic carriers for gas or liquid catalytic reactions by loading catalysts, and have good regenerability and catalytic efficiency.

[0047] S5 Environmental Protection and Health and Safety

[0048] S5.1: Its preparation method uses environmentally friendly solvents and catalysts, reducing the harm to the environment and human body. At the same time, solvent-free modification technology and water-based emulsion polymerization methods are adopted to effectively reduce the emissions of harmful gases and solvents. During the production process, high-temperature and high-pressure operations are minimized to reduce safety hazards and ensure the safety of the production environment.

[0049] Specifically, in step S1, suitable environmentally friendly solvents are selected, such as ethanol, water, or non-toxic solvents, etc. For emulsion polymerization, water can be used as the solvent to avoid using toxic organic solvents. By adjusting the solvent ratio, the stability of the reaction system is optimized. Selection of surfactants: Select non-toxic and low-irritating natural surfactants, such as chitosan or polyvinyl alcohol (PVA), to stabilize the emulsion. Using these natural components can effectively reduce environmental pollution and avoid the impact of traditional surfactants on human health. In the experiment, a constant-temperature reactor, such as a water bath or a thermal circulation reactor, is used to ensure that the reaction temperature is maintained within the ideal range (generally 60 - 80 °C), avoiding side reactions caused by too high a temperature or too slow a polymerization rate caused by too low a temperature. Pressure control: The reaction kettle is equipped with an automatic pressure regulation function to ensure that the pressure is within the range of 10 - 20 MPa, thereby avoiding solvent volatilization or incomplete reaction. Optimization of monomer ratio: Adjust the ratio of polystyrene to divinylbenzene according to different target properties. The optimal ratio can be selected through small-scale experiments before the reaction, such as PS / DVB = 90:10 or 80:20, to avoid excessive cross-linking caused by excessive divinylbenzene. Addition of cross-linking regulators: During the polymerization process, an appropriate amount of cross-linking regulators, such as a small amount of trivinyltrisilane or other cross-linking regulating molecules, is added. By adjusting the timing of their addition (such as gradually adding instead of adding all at once), the cross-linking reaction is controlled. The divinylbenzene is added in stages by gradually adding the cross-linking agent (such as first adding 10% and then adding the remaining part when the reaction proceeds to a certain extent), and the cross-linking degree is optimized in this way.

[0050] Specifically, suitable functional monomers are selected in step S2, such as acrylic acid, vinylbenzene, amino compounds, etc. These monomers can undergo chemical reactions with the surface of the microspheres to form a functionalized coating. For example, acrylic acid can be added to obtain hydrophilicity, or the surface compatibility with other materials can be enhanced by introducing amino or methyl functional groups. Implementation of the functionalization process: Using the free radical polymerization method, after the polymerization is completed, functional monomers such as acrylic acid or epoxides are added to the reaction system, and then surface grafting or post-polymerization reactions are carried out. This process can be carried out under low-temperature conditions through a simple reflux reaction to avoid side reactions caused by high temperatures. On the surface of the microspheres, first, a hydrophilic monomer is used for primary functionalization modification, and then hydrophobicity or other special functions (such as metal catalysis, adsorption function) are further introduced through different subsequent reactions. The specific method is to perform surface cleaning after the first modification to remove unreacted monomers, and then introduce the second modification reaction. This process can be completed by the solvation method or the gas-phase grafting method.

[0051] Specifically, a low-temperature vacuum drying device (such as a vacuum drying oven or a spray dryer) is used in step S3, the temperature is controlled below 50°C, and at the same time, a low-pressure environment (such as 10 - 20 kPa) is maintained to avoid damaging the microsphere structure due to excessive temperature. Through the vacuum state, water and solvents will evaporate rapidly, and the drying process is more gentle, capable of maintaining the shape and structure stability of the microspheres. After drying, the microspheres are classified according to the particle size distribution by mechanical screening or vibration screening techniques. The pore size of the sieve is adjusted according to the required particle size range (such as gradually screening through sieve meshes with pore sizes of 300 μm, 500 μm, etc.). Centrifugal separation: For microspheres with uneven particle size distribution, a centrifuge can be used to further classify the microspheres by differential centrifugal separation to ensure a more uniform particle size distribution.

[0052] Specifically, in step S4, the prepared composite microspheres are added to the coating. The microspheres can enhance the hardness, UV resistance, and corrosion resistance of the coating. In adhesives, the microspheres can improve the adhesion, especially the adhesion performance at high temperatures. At this time, an appropriate amount of surface modifier (such as polyvinyl alcohol) needs to be added to the microspheres to increase the dispersibility and stability of the microspheres in the coating or adhesive. The drug (such as an antibiotic or an anticancer drug) is dissolved in the reaction solution. As the polymerization reaction proceeds, the drug is embedded inside the polystyrene-divinylbenzene composite microspheres. By adjusting the crosslinking degree, the slow release of the drug can be achieved. An in vitro drug release experiment (such as the dialysis method) is used to evaluate the release performance of the microspheres to ensure that the drug can be gradually released within a specific time range. When the microspheres are used for water treatment, their adsorption capacity for heavy metal ions (such as lead and mercury) or organic pollutants (such as benzene compounds) is improved through surface functionalization. The microspheres remove harmful substances in water through adsorption and can restore their adsorption capacity through washing or using a chemical regenerant after use. Catalytic carrier application: In catalytic applications, the microspheres can be used as catalyst carriers. Catalysts such as metal nanoparticles are loaded on the surface of the microspheres for catalytic reactions. During the reaction process, the functional groups on the surface of the microspheres can improve the dispersibility and activity of the catalyst, thereby enhancing the catalytic effect.

[0053] Specifically, in step S5, harmful solvents, catalysts, or toxic additives are avoided. During the implementation of the process, non-toxic solvents and pollution-free reaction materials are used as much as possible, and it is ensured that all waste can be effectively treated. The improved polymerization process uses low-temperature and low-pressure reactions to reduce energy consumption and environmental impact. The equipment also selects an automated and precise control system to further reduce human errors and ensure the safety and controllability of the reaction process.

[0054] Through the above technical solutions, in the present invention, by optimizing the polymerization process, precisely controlling the crosslinking degree, introducing green solvents and environmentally friendly surface modification methods, the improved polystyrene-divinylbenzene composite microspheres not only solve some drawbacks in the prior art (such as high cost, uneven particle size, difficulty in controlling the crosslinking degree, etc.), but also have broader application potential in multiple fields (such as coatings, medicine, environmental protection, catalysis, etc.), and have good environmental protection and health safety.

[0055] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A preparation method and application of polystyrene-divinylbenzene composite microspheres, characterized in that: It includes the following steps: S1 Polymerization reaction S1.1: Selection of green solvents: Use environmentally friendly solvent systems, such as water-based or non-toxic organic solvents (such as ethanol), to replace traditional organic solvents. Using aqueous emulsion polymerization can reduce the risk of solvent pollution and simplify the recovery and treatment of solvents. Optimization of surfactants: Select low-toxicity, environmentally friendly surfactants (such as surfactants of natural origin) for emulsion stabilization, and avoid using chemicals harmful to the environment and human body; S1.2: Temperature and pressure control: Optimize the polymerization reaction rate by precisely controlling the reaction temperature and pressure. More efficient reactor designs, such as microchannel reactors, can be used to improve the reaction efficiency and reduce the generation of by-products. Optimization of monomer ratio: By optimizing the ratio of polystyrene (PS) and divinylbenzene (DVB) monomers, precisely control the crosslinking degree of the microspheres to obtain composite microspheres with good mechanical properties and not easily embrittled; S1.3: Introduction of crosslinking agent regulators: Introduce crosslinking regulators (such as a small amount of crosslinking regulators or modifiers) during the polymerization process to achieve precise control of the crosslinking degree. This can improve its stability and heat resistance without sacrificing the flexibility of the microspheres. Step-by-step crosslinking process: Gradually add divinylbenzene through a staged polymerization process to achieve gradient control of the crosslinking degree, thus avoiding excessive crosslinking. S2 Functional surface modification S2.1: Modify the surface of the microspheres by adding functional monomers during the polymerization process or by post-surface grafting methods. For example, select hydrophilic or hydrophobic functional monomers (such as vinyl ether compounds, amino or carboxyl compounds) to make the surface of the microspheres have good water dispersibility or enhance compatibility with other materials. Solvent-free modification method: Adopt solvent-free modification methods such as gas-phase graft polymerization, which avoids environmental pollution problems caused by the use of traditional solvents and can achieve a more uniform and stable functional coating; S2.2: Multistage surface modification: Achieve a multifunctional surface of the microspheres by adopting a multi-step surface modification method. For example, graft hydrophilic monomers in the first step and graft specific catalytic or adsorption functional monomers in the second step, so that it can provide different functions in different application scenarios. S3 Drying and recovery of microspheres S3.1: Dry the microspheres using low-temperature vacuum drying technology, which can not only reduce thermal damage but also prevent the microspheres from breaking; S3.2: After drying, use mechanical screening or centrifugal separation technology to classify the microspheres to obtain a relatively uniform particle size distribution. S4 Optimize the application performance of microspheres S4.1: In coatings and adhesives, the modified polystyrene-divinylbenzene composite microspheres can be used as synergistic fillers to improve the mechanical strength, weather resistance, and ultraviolet resistance of the coatings. Due to their excellent surface functionalization characteristics, these composite microspheres can enhance the adhesion and water resistance of the coatings and are suitable for high-demand architectural coatings and exterior wall thermal insulation coatings; S4.2: Through surface modification, the composite microspheres have better biocompatibility and targeting in the pharmaceutical field. Drugs can be encapsulated inside the microspheres, and the controlled release of drugs can be achieved by adjusting their crosslinking degree. The microspheres can also be used in sustained-release systems to avoid the rapid release of drugs in the body, extend the efficacy time, and reduce side effects. S4.3: In the field of environmental protection, the modified composite microspheres can be used as adsorbents for water treatment to remove heavy metal ions, organic pollutants, etc. in water. The surface functionalization of the microspheres enhances their adsorption capacity and selectivity, and due to their high stability, they can be used for a long time in relatively harsh environments. In the field of catalysis, the microspheres can be used as catalytic carriers for gas or liquid catalytic reactions by loading catalysts, and have good regenerability and catalytic efficiency. S5 Environmental protection and health safety S5.1: Its preparation method uses environmentally friendly solvents and catalysts, reducing the harm to the environment and human body. At the same time, solvent-free modification technology and water-based emulsion polymerization methods are adopted to effectively reduce the emission of harmful gases and solvents. During the production process, high-temperature and high-pressure operations are minimized as much as possible, reducing safety hazards and ensuring the safety of the production environment.

2. A method for preparing a polystyrene-divinylbenzene composite microsphere and its application according to claim 1, characterized in that: In step S1, suitable environmentally friendly solvents are selected, such as ethanol, water, or non-toxic solvents, etc. For emulsion polymerization, water can be used as a solvent to avoid using toxic organic solvents. By adjusting the solvent ratio, the stability of the reaction system is optimized. Selection of surfactants: Non-toxic and low-irritating natural surfactants, such as chitosan or polyvinyl alcohol (PVA), are selected to stabilize the emulsion. Using these natural ingredients can effectively reduce environmental pollution and avoid the impact of traditional surfactants on human health. In the experiment, a constant-temperature reactor, such as a water bath or a thermal circulation reactor, is used to ensure that the reaction temperature is maintained within the ideal range (generally 60 - 80 °C), avoiding side reactions caused by too high temperature or too slow polymerization rate caused by too low temperature. Pressure control: The reaction kettle is equipped with an automatic pressure regulation function to ensure that the pressure is within the range of 10 - 20 MPa, thereby avoiding solvent volatilization or incomplete reaction. Optimization of monomer ratio: The ratio of polystyrene to divinylbenzene is adjusted according to different target properties. The optimal ratio can be selected through small-scale experiments before the reaction, such as PS / DVB = 90:10 or 80:20, to avoid excessive crosslinking caused by excessive divinylbenzene. Addition of crosslinking regulator: During the polymerization process, an appropriate amount of crosslinking regulator, such as a small amount of trivinyltrisilane or other crosslinking regulating molecules, is added. By adjusting the timing of its addition (such as adding gradually instead of all at once), the crosslinking reaction is controlled. The divinylbenzene is added in stages by gradually adding the crosslinking agent (such as adding 10% first, and then adding the remaining part when the reaction proceeds to a certain extent), and the crosslinking degree is optimized in this way.

3. A method for preparing a polystyrene-divinylbenzene composite microsphere and its application according to claim 1, characterized in that: In step S2, suitable functional monomers are selected, such as acrylic acid, vinylbenzene, amino compounds, etc. These monomers can undergo chemical reactions with the surface of the microspheres to form a functionalized coating. For example, acrylic acid can be added to obtain hydrophilicity, or the surface compatibility with other materials can be enhanced by introducing amino or methyl functional groups. The implementation of the functionalization process: Using the free radical polymerization method, after the polymerization is completed, functional monomers such as acrylic acid or epoxides are added to the reaction system, and then surface grafting or post-polymerization reactions are carried out. This process can be carried out under low-temperature conditions through a simple reflux reaction to avoid side reactions caused by high temperatures. On the surface of the microspheres, first, a hydrophilic monomer is used for a primary functionalization modification, and then hydrophobicity or other special functions (such as metal catalysis, adsorption function) are further introduced through different subsequent reactions. The specific method is to perform surface cleaning after the first modification to remove unreacted monomers, and then introduce the second modification reaction. This process can be completed by the solvation method or the gas-phase grafting method.

4. A method for preparing a polystyrene-divinylbenzene composite microsphere and its application according to claim 1, characterized in that: In step S3, a low-temperature vacuum drying device (such as a vacuum drying oven or a spray dryer) is used, the temperature is controlled below 50°C, and at the same time, a low-pressure environment (such as 10 - 20 kPa) is maintained to avoid damaging the microsphere structure due to excessive temperature. Through the vacuum state, moisture and solvents will evaporate rapidly, and the drying process is more gentle, capable of maintaining the shape and structure of the microspheres stable. After drying, the microspheres are classified according to the particle size distribution by mechanical screening or vibrating screening techniques. The pore size of the sieve is adjusted according to the required particle size range (such as gradually screening through sieve meshes with multiple pore sizes such as 300 μm and 500 μm). Centrifugal separation: For microspheres with an uneven particle size distribution, a centrifuge can be used to further classify the microspheres by differential centrifugal separation to ensure a more uniform particle size distribution.

5. A preparation method and application of a polystyrene-divinylbenzene composite microsphere according to claim 1, characterized in that: In step S4, the prepared composite microspheres are added to the coating. The microspheres can enhance the hardness, ultraviolet resistance and corrosion resistance of the coating. In adhesives, the microspheres can improve the adhesion, especially the adhesion performance at high temperatures. At this time, an appropriate amount of surface modifier (such as polyvinyl alcohol) needs to be added to the microspheres to increase the dispersibility and stability of the microspheres in the coating or adhesive. The drug (such as an antibiotic or an anticancer drug) is dissolved in the reaction solution. As the polymerization reaction proceeds, the drug is embedded inside the polystyrene-divinylbenzene composite microspheres. By adjusting the crosslinking degree, slow release of the drug can be achieved. An in vitro drug release experiment (such as dialysis method) is used to evaluate the release performance of the microspheres to ensure that the drug can be gradually released within a specific time range. When the microspheres are used for water treatment, their adsorption capacity for heavy metal ions (such as lead and mercury) or organic pollutants (such as benzene compounds) is improved through surface functionalization. The microspheres remove harmful substances in water through adsorption and can restore their adsorption capacity by washing or using a chemical regenerant after use. Catalyst support application: In catalytic applications, the microspheres can be used as catalyst supports. Catalysts such as metal nanoparticles are loaded on the surface of the microspheres for catalytic reactions. During the reaction process, the functional groups on the surface of the microspheres can improve the dispersibility and activity of the catalyst, thereby enhancing the catalytic effect.

6. The preparation method and application of a polystyrene-divinylbenzene composite microsphere according to claim 1, characterized in that: In step S5, harmful solvents, catalysts or toxic additives are avoided. In the process implementation, non-toxic solvents and pollution-free reaction materials are used as much as possible, and it is ensured that all waste can be effectively treated. The improved polymerization process uses low-temperature and low-pressure reactions to reduce energy consumption and environmental impact. The equipment also selects an automated and precision control system to further reduce human errors and ensure the safety and controllability of the reaction process.