Cationic polymer microsphere and preparation method thereof

Abstract

The invention provides a cationic polymer microsphere and a preparation method thereof. The preparation method of the cationic polymer microspheres comprises the steps that a chain transfer agent, an aromatic monomer and an initiator are mixed in water and an organic solvent to obtain a mixed solution, the chain transfer agent is a cationic macromolecular chain transfer agent with the molecular weight larger than 8000, and the aromatic monomer comprises at least two benzene ring structures; and carrying out vacuum sealing and heating on the mixed solution to initiate a polymerization reaction and a self-assembly process so as to form the cationic polymer microspheres.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer nanomaterials, and in particular to a cationic polymer microsphere and a preparation method thereof. Background Art

[0002] Polymer microspheres are polymer particles with a spherical shape and a particle size ranging from tens of nanometers to hundreds of micrometers. They are widely used in catalysis, adsorption separation, molecular imprinting, soft templates for material synthesis, and biomedical analysis. For most applications, a well-defined particle size and a narrow size distribution are essential.

[0003] Common methods for preparing polymer microspheres include suspension polymerization, precipitation polymerization, emulsion polymerization, dispersion polymerization and seed polymerization. Different polymerization methods can prepare microspheres of different sizes and uniformities. However, these methods still have some problems in preparing cationic polymer microspheres, such as insufficient particle stability, poor monodispersity, low surface charge density and cumbersome operation. Therefore, it is urgent to develop new methods to prepare cationic polymer microspheres to meet the needs of high-performance applications. Summary of the invention

[0004] In view of this, the main purpose of the present disclosure is to provide a cationic polymer microsphere and a preparation method thereof, in order to at least partially solve at least one of the above-mentioned technical problems.

[0005] To achieve the above purpose, the technical solution of the present invention is as follows:

[0006] In one aspect of the present disclosure, a method for preparing cationic polymer microspheres is provided, comprising:

[0007] Mixing a chain transfer agent, an aromatic monomer, and an initiator in water and an organic solvent to obtain a mixed solution, wherein the chain transfer agent is a cationic macromolecular chain transfer agent with a molecular weight greater than 8000, and the aromatic monomer contains at least two benzene ring structures;

[0008] The mixed solution is vacuum sealed and heated to initiate polymerization and self-assembly processes to form cationic polymer microspheres.

[0009] As a second aspect of the present disclosure, a cationic polymer microsphere prepared by the above preparation method is provided. The cationic polymer microsphere comprises a core formed by polymerization of an aromatic monomer and a cationic polymer layer coated outside the core.

[0010] According to an embodiment of the present disclosure, a method for preparing cationic polymer microspheres is provided, wherein a cationic macromolecular chain transfer agent and an aromatic monomer containing at least two benzene ring structures are used to prepare monodisperse cationic polymer microspheres. During the polymerization reaction, the solvophilic cationic macromolecular chain transfer agent regulates the polymerization reaction of the solvophobic aromatic monomer, gradually forming an amphiphilic block polymer. As the polymerization reaction proceeds, the length ratio of the solvophobic segment to the solvophilic segment continues to increase, driving the amphiphilic block polymer to undergo a self-assembly process in a selective solvent to form cationic polymer microspheres.

[0011] According to the embodiments of the present disclosure, the cationic polymer microspheres prepared by the preparation method of the cationic polymer microspheres proposed in the present disclosure have adjustable particle sizes and good monodispersity. In addition, the microspheres have positive charges on their surfaces and good stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a scanning electron microscope image of the cationic polymer microspheres prepared in Examples 1 to 3 of the present disclosure;

[0013] Figure 2 is a scanning electron microscope image of the cationic polymer microspheres prepared in Examples 4 to 6 of the present disclosure;

[0014] Figure 3 This is a scanning electron microscope image of the cationic polymer microspheres prepared in Examples 7 to 9 of the present disclosure. DETAILED DESCRIPTION

[0015] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in conjunction with specific embodiments.

[0016] The endpoints and any values ​​of the ranges disclosed in this disclosure are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this disclosure.

[0017] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0018] At present, common methods for preparing polymer microspheres include suspension polymerization, precipitation polymerization, emulsion polymerization, dispersion polymerization and seed polymerization. Among them, dispersion polymerization has become an excellent method for preparing monodisperse microspheres due to its simple operation. However, the preparation of surface functionalized polymer microspheres using dispersion polymerization usually faces challenges. One method of dispersion polymerization is through dispersed copolymerization of functional monomers, but this method causes most functional groups to be embedded in the interior of the particles and cannot be fully utilized; another method is to use stabilizers containing functional groups, but often only polydisperse polymer microspheres can be obtained. In addition, other preparation methods also have problems such as insufficient particle stability, poor monodispersity, low surface charge density or cumbersome operation. Therefore, the preparation of monodisperse polymer microspheres with uniform size using functional stabilizers still has high technical difficulty.

[0019] In the process of realizing the concept of the present disclosure, it was found that reversible addition fragmentation chain transfer (RAFT) polymerization can obtain nanoparticles of different morphologies through the polymerization induced self-assembly (PISA) mechanism, including spherical micelles, worm-like micelles and vesicles. Based on this, the present disclosure proposes a method for preparing cationic polymer microspheres, using cationic macromolecular RAFT agents and aromatic monomers to carry out polymerization reaction and self-assembly process under the action of an initiator. The electrostatic repulsion between the cationic macromolecular RAFT agent segments ensures the spherical morphology of the polymer microspheres, while the π-π stacking interaction in the polymer segments formed by the aromatic monomers promotes the rapid nucleation of the block polymer and accelerates the formation of cationic polymer microspheres. The present disclosure adopts a one-pot synthesis method, which is simple and easy to control. The prepared polymer microspheres have good monodispersity and adjustable particle size, which overcomes the limitations of the prior art and provides a general and efficient new way to prepare monodisperse polymer microspheres.

[0020] According to an embodiment of one aspect of the present disclosure, there is provided a method for preparing cationic polymer microspheres, comprising:

[0021] Mixing a chain transfer agent, an aromatic monomer, and an initiator in water and an organic solvent to obtain a mixed solution, wherein the chain transfer agent is a cationic macromolecular chain transfer agent with a molecular weight greater than 8000, and the aromatic monomer contains at least two benzene ring structures;

[0022] The mixed solution is vacuum sealed and heated to initiate polymerization and self-assembly processes to form cationic polymer microspheres.

[0023] According to the embodiments of the present disclosure, the preparation method of cationic polymer microspheres of the present disclosure realizes the efficient preparation of cationic polymer microspheres by combining a cationic macromolecular RAFT agent and an aromatic monomer containing at least two benzene ring structures. During the polymerization reaction, the solvophilic cationic macromolecular RAFT agent regulates the polymerization reaction of the solvophobic aromatic monomer, and gradually polymerizes to form an amphiphilic block polymer. As the polymerization reaction proceeds, the length ratio of the solvophobic segment to the solvophilic segment continues to increase, and the amphiphilic block polymer self-assembles in a selective solvent to form cationic polymer microspheres. Among them, there is a strong electrostatic repulsion between the cationic macromolecular RAFT agent chains, and the electrostatic repulsion is used to effectively limit the fusion transformation of the block polymer microsphere morphology, thereby ensuring that the polymer only presents a spherical morphology. At the same time, the benzene ring structures in the aromatic polymer blocks have strong π-π stacking interactions, which not only promotes the rapid nucleation of the polymer, but also enables the polymerization reaction to proceed inside the nucleus, significantly accelerating the synthesis rate of polymer microspheres and completing the preparation of microspheres in a shorter time, avoiding the occurrence of secondary nucleation, so that the formed cationic polymer microspheres exhibit excellent monodispersity.

[0024] According to the embodiments of the present disclosure, the preparation method of cationic polymer microspheres, after the polymerization reaction and the self-assembly process are completed, the cationic polymer microspheres are obtained after quenching, centrifugation, precipitation, and drying. In practical applications, cationic polymer microspheres can also be obtained after quenching, dialysis, and drying. Exemplarily, the polymerization reaction can be quenched by cooling to quickly terminate the polymerization reaction and prevent the occurrence of excessive polymerization or side reactions, thereby ensuring that the structure and performance of the polymer microspheres meet the expected design. The obtained cationic polymer microspheres can be diluted with a mixed solution of ethanol and water, and then centrifuged, washed, and circulated three times to remove impurities such as unreacted monomers and initiators to ensure the purity and stability of the microspheres. For example, the drying method can be freeze-drying, which removes moisture by low-temperature freezing and vacuum sublimation to avoid the destruction or agglomeration of the microsphere structure caused by direct heating and drying, thereby maintaining the morphology and dispersibility of the microspheres and ensuring the stability of the product.

[0025] According to an embodiment of the present disclosure, vacuum sealing and heating the mixed solution includes: adding the mixed solution to the sealed tube, and performing three freeze-vacuum-thaw cycles on the sealed tube to ensure that the gas in the sealed tube is fully discharged to avoid interference of impurities such as oxygen on the polymerization reaction. After the cycle operation is completed, the sealed tube is vacuum sealed and heated to 70-80 ° C, for example, 70 ° C, 73 ° C, 75 ° C, 77 ° C, 80 ° C, etc. The insulation reaction is 10-20 h, for example, 10 h, 13 h, 15 h, 17 h, 20 h, etc. Appropriate reaction temperature and reaction time are key factors to ensure efficient polymerization and uniform formation of polymer microspheres. By precisely controlling the temperature and time, the rate and degree of the polymerization reaction can be optimized, thereby obtaining cationic polymer microspheres with uniform particle size and good monodispersity. At the same time, suitable reaction conditions can also effectively avoid the occurrence of side reactions and ensure the performance and stability of polymer microspheres.

[0026] According to an embodiment of the present disclosure, the chain transfer agent has a structure as shown in formula (I) or formula (II):

[0027] Formula (I),

[0028] Formula (II), wherein include:

[0029] Any one of polymethacryloyloxyethyl trimethyl ammonium chloride and polyacryloyloxyethyl trimethyl ammonium chloride. The chain transfer agent is a cationic macromolecular chain transfer agent, which has a positive charge and can form a uniformly distributed positive charge layer on the surface of the polymer microsphere. This positive charge layer not only helps to improve the monodispersity of the microspheres, but also prevents the microspheres from aggregating through electrostatic repulsion, thereby ensuring that the microspheres have good monodispersity and stability. Wherein 40≤n≤110, for example, n can be 40, 60, 80, 90, 110, etc. Chain transfer agents with different degrees of polymerization (n) can be selected according to the needs of different applications to adjust the particle size and surface charge density of the cationic polymer microspheres.

[0030] For example, the chain transfer agent used in the present disclosure is polymethacryloyloxyethyl trimethyl ammonium chloride (PMATAC 55 -PETTC) can be synthesized by the following steps:

[0031] 4-Cyano-4-(2-phenylethylthiothiocarbonyl)thiopentanoic acid (PETTC) (700.80 mg, 2.07 mmol), methacryloyloxyethyltrimethylammonium chloride (MATAC) (17.17 g, 0.08 mol), initiator VA-044 (133.20 mg, 0.41 mmol) and methanol (42.00 g) were added to a sealed tube equipped with a magnetic bar. After three freeze-vacuum-thaw cycles, the sealed tube was vacuum sealed. The sealed tube was placed in an oil bath at 45°C and stirred for polymerization for 7 hours, and the polymerization reaction was quenched by cooling. Then, the reaction mixture was dialyzed with methanol to remove unreacted raw materials, and then the methanol was replaced by dialyzation with water, and finally the product PMATAC was obtained by freeze drying. 55 -PETTC.

[0032] According to an embodiment of the present disclosure, the aromatic monomer includes any one of methacryloyloxyethyl anthracene carboxylate, methacryloyloxyethyl naphthoate, diphenylmethyl methacrylate, and phenoxyphenyl methacrylate. The aromatic monomer contains at least two benzene ring structures, preferably 2 to 3 benzene ring structures. The aromatic monomer with one benzene ring structure has a weak π-π stacking effect due to the small number of benzene rings, resulting in a slow nucleation rate of the polymer microspheres and difficulty in quickly forming a uniform microsphere structure. In addition, too many benzene rings will lead to a decrease in the solubility of the aromatic monomer, making it difficult for the polymerization reaction to proceed uniformly, thereby affecting the uniformity and dispersibility of the microspheres. Therefore, the selection of an aromatic monomer containing 2 to 3 benzene rings can maintain good solubility while ensuring rapid nucleation of the polymer microspheres, thereby achieving the preparation of uniform and monodisperse polymer microspheres.

[0033] For example, the aromatic monomer methacryloyloxyethyl anthracene carboxylate (MAEAC) used in the present disclosure can be synthesized by the following steps:

[0034] 9-Anthracenecarboxylic acid (10.00 g, 44.99 mmol) and 100 mL of thionyl chloride were added to a 250 mL round-bottom flask. A condensation reflux and tail gas absorption device was set up, and the reaction was stirred at 75 °C for 10 h to complete the reaction of generating acyl chloride. The residual thionyl chloride was removed by reduced pressure rotary evaporation (spin-drying), and the spin-dried product was dissolved in 50 mL of tetrahydrofuran (THF) to obtain a product solution.

[0035] Hydroxyethyl methacrylate (7.03 g, 53.79 mmol), triethylamine (9.11 g, 88.94 mmol) and 100 mL of THF were added to a 250 mL round-bottom flask. The product solution obtained in the previous step was slowly added dropwise to the system using a constant pressure dropping funnel at 0 °C, and then reacted at room temperature for 12 h. After the reaction was completed, the generated salt was removed by suction filtration, and the crude MAEAC product was obtained by decompression and spin drying, and further purified by column chromatography to obtain MAEAC.

[0036] For example, the aromatic monomer methacryloyloxyethyl naphthoate (MAENC) used in the present disclosure can be synthesized by the following steps:

[0037] Hydroxyethyl methacrylate (20.48 g, 157.37 mmol) and triethylamine (26.54 g, 262.29 mmol) were dissolved in 200 mL of dichloromethane (CH2Cl2), and 1-naphthoyl chloride (25.00 g, 131.14 mmol) was slowly added at 0 °C, followed by reaction at room temperature for 12 h. After filtering to remove the solid byproduct, the filtrate was concentrated and purified by column chromatography to obtain MAENC.

[0038] According to an embodiment of the present disclosure, the initiator includes any one of a thermal initiator, a photoinitiator, and a redox initiator, preferably azobisisobutyronitrile (AIBN). The molar ratio of the chain transfer agent, the aromatic monomer, and the initiator is 1: (100-200): 0.20, for example, it can be 1: 100: 0.2, 1: 120: 0.2, 1: 150: 0.2, 1: 170: 0.2, 1: 200: 0.2. By precisely controlling the ratio of the chain transfer agent, the aromatic monomer, and the initiator, a balance between rapid nucleation and uniform growth can be achieved during the polymerization process, avoiding the occurrence of secondary nucleation, thereby ensuring that the microspheres have good monodispersity and morphological stability.

[0039] According to an embodiment of the present disclosure, the organic solvent includes any one of an alcohol solvent, a sulfoxide solvent, an alkane solvent, and an ether solvent, wherein the mass ratio of the organic solvent to water is (6~4):(4~6), for example, it can be 6:4, 5:5, 4:6, etc. The ratio of the organic solvent to water will affect the process of the polymerization reaction. When the amount of organic solvent is too high and the amount of water is too little, the nucleation time will be significantly prolonged, resulting in uneven particle size distribution of the microspheres, and even agglomeration may occur, affecting the quality and performance of the microspheres. When the water content is too high and the organic solvent is too little, the solubility of the system will be reduced, affecting the dissolution of aromatic monomers and chain transfer agents, thereby reducing the efficiency of the polymerization reaction. Insufficient solubility may also cause an uneven surface of the polymer microspheres, affecting the morphology and performance of the cationic polymer microspheres.

[0040] According to the embodiments of the present disclosure, the solid content of the cationic polymer microspheres is 14% to 28%, for example, 14%, 18%, 20%, 25%, 28%, etc. The preparation method of the cationic polymer microspheres in the present disclosure can prepare cationic polymer microspheres with a higher solid content, that is, the cationic polymer microspheres have a higher concentration in the solution, can be prepared in large quantities, and provide an effective method for subsequent industrial applications.

[0041] According to another embodiment of the present disclosure, a cationic polymer microsphere prepared by the above preparation method is provided, wherein the cationic polymer microsphere comprises a core formed by polymerization of an aromatic monomer and a cationic polymer layer coated outside the core.

[0042] According to an embodiment of the present disclosure, the Zeta potential value of the polymer microspheres is greater than 25 mv, and the Zeta potential value can be, for example, 30 mv, 35 mv, 40 mv, 50 mv, 60 mv, etc. A higher Zeta potential value indicates that the surface of the microspheres is rich in positive charges, which not only enhances the stability of the microspheres in solution, but also makes them show stronger interaction ability in adsorption and separation applications. The particle size of the polymer microspheres is 100~500 nm, for example, it can be 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, etc. By regulating the particle size, cationic polymer microspheres can meet the needs of various application scenarios, such as biomedical testing, drug delivery, preparation of nanomaterials, etc. The particle size polydispersity coefficient of the polymer microspheres is less than 0.1, and the dispersion coefficient can be, for example, 0.09, 0.07, 0.05, 0.03, etc. The lower polydispersity coefficient indicates that the cationic polymer microspheres have a highly consistent particle size distribution, which not only ensures the uniformity of the performance of the microspheres in practical applications, but also significantly improves their applicability in high-precision fields.

[0043] According to the embodiments of the present disclosure, the cationic polymer microspheres prepared by the present disclosure can be used in the fields of drug carriers, adsorption separation, antibacterial, etc. For example, by introducing positively charged groups through quaternization reaction, the treated polystyrene microspheres can be used for the adsorption of anionic pollutants in water. The quaternized cationic copolymer microspheres show excellent antibacterial activity. When added to the coating, the antibacterial rate can still exceed 95%, providing a way for the development of antibacterial coatings. In addition, cationic microspheres are more effective than anionic microspheres and non-ionic microspheres as flocculants for papermaking and wastewater treatment, and are also often used in cosmetics and personal care products.

[0044] In order to make the purpose, technical scheme and advantages of the present disclosure more clear, the present disclosure is further described in detail below in conjunction with specific embodiments. Specific techniques or conditions not specified in the embodiments are conventional methods and can be carried out according to the techniques or conditions described in the literature in the art or according to the product instructions.

[0045] Embodiment 1:

[0046] Embodiment 1 of the present disclosure provides a method for preparing cationic polymer microspheres, comprising the following steps:

[0047] Polymethacryloyloxyethyltrimethylammonium chloride (PMATAC 55 -PETTC) as chain transfer agent (42.35 mg, 3.60×10 -3 mmol), methacryloyloxyethyl anthracene carboxylate (MAEAC) as an aromatic monomer (120.37 mg, 3.60×10 -1 mmol), azobisisobutyronitrile (AIBN) as initiator (0.12 mg, 0.72×10 -3 mmol), added together with 1000 mg of ethanol aqueous solution and mixed to obtain a mixed solution. The mass ratio of ethanol to water is 6:4 (EtOH / H2O = 6 / 4 (w / w)).

[0048] The mixed solution was added to a sealed tube equipped with a magnetic rod. After three freeze-vacuum-thaw cycles, the sealed tube was vacuum-sealed and kept in a 70 ℃ oil bath for 20 h. The reaction formula is as follows:

[0049]

[0050] After the reaction is completed, the polymerization reaction is quenched by cooling to prepare the target degree of polymerization (DP PMAEAC ) is 100 cationic polymer microspheres 1-1.

[0051] Example 2

[0052] Example 2 of the present disclosure provides a method for preparing cationic polymer microspheres, which is different from Example 1 in that the target degree of polymerization (DP PMAEAC ) is 150. The other preparation processes of the cationic polymer microspheres in Example 2 are the same as those in Example 1.

[0053] Example 3

[0054] This embodiment 3 provides a method for preparing cationic polymer microspheres, which is different from embodiment 1 in that the target degree of polymerization (DP PMAEAC) is 200. The other preparation processes of the cationic polymer microspheres in Example 3 are the same as those in Example 1.

[0055] The obtained cationic polymer microspheres 1-1, 1-2, and 1-3 were diluted to 0.50 mg / g in ethanol aqueous solution and characterized by scanning electron microscope (SEM). Figure 1 This is a scanning electron microscope image of the cationic polymer microspheres prepared in Examples 1 to 3 of the present disclosure.

[0056] like Figure 1 As shown, the prepared cationic polymer microspheres have uniform sizes, and the average particle size increases with the increase of polymerization degree.

[0057] Embodiment 4:

[0058] Embodiment 4 of the present disclosure provides a method for preparing cationic polymer microspheres, comprising the following steps:

[0059] Polymethacryloyloxyethyltrimethylammonium chloride (PMATAC 55 -PETTC) as chain transfer agent (42.35 mg, 3.60×10 -3 mmol), methacryloyloxyethyl naphthoate (MAENC) as an aromatic monomer (102.35 mg, 3.60×10 -1 mmol), azobisisobutyronitrile (AIBN) as initiator (0.12 mg, 0.72×10 -3 mmol), added together with 1000 mg of ethanol aqueous solution and mixed to obtain a mixed solution, wherein the mass ratio of ethanol to water is 4:6 (EtOH / H2O = 4 / 6 (w / w)).

[0060] The mixed solution was added to a sealed tube equipped with a magnetic rod. After three freeze-vacuum-thaw cycles, the sealed tube was vacuum-sealed and kept in a 70 ℃ oil bath for 20 h. The reaction formula is as follows:

[0061]

[0062] After the reaction is completed, the polymerization reaction is quenched by cooling to prepare the target degree of polymerization (DP PMAENC ) is 100 cationic polymer microspheres 2-1.

[0063] Example 5

[0064] Example 5 of the present disclosure provides a method for preparing cationic polymer microspheres, which is different from Example 4 in that the target degree of polymerization (DPPMAENC ) is 150 cationic polymer microspheres 2-2. The other preparation processes of the cationic polymer microspheres in Example 5 are the same as those in Example 4.

[0065] Example 6

[0066] Example 6 of the present disclosure provides a method for preparing cationic polymer microspheres, which is different from Example 4 in that the target degree of polymerization (DP PMAENC ) is 200 cationic polymer microspheres 2-3. The other preparation processes of the cationic polymer microspheres in Example 6 are the same as those in Example 4.

[0067] The obtained cationic polymer microspheres 2-1, 2-2, and 2-3 were diluted to 0.50 mg / g in ethanol aqueous solution and characterized by scanning electron microscope (SEM). Figure 2 This is a scanning electron microscope image of the cationic polymer microspheres prepared in Examples 4 to 6 of the present disclosure.

[0068] like Figure 2 As shown, the prepared cationic polymer microspheres have uniform sizes, and the average particle size increases with the increase of polymerization degree.

[0069] Embodiment 7:

[0070] Embodiment 7 of the present disclosure provides a method for preparing cationic polymer microspheres, comprising the following steps:

[0071] Polymethacryloyloxyethyltrimethylammonium chloride (PMATAC 55 -PETTC) as chain transfer agent (42.35 mg, 3.60×10 -3 mmol), methacryloyloxyethyl anthracene carboxylate (MAEAC) as an aromatic monomer (120.37 mg, 3.60×10 -1 mmol), azobisisobutyronitrile (AIBN) as initiator (0.12 mg, 0.72×10 -3 mmol), added together with 1000 mg of ethanol aqueous solution and mixed to obtain a mixed solution. The mass ratio of ethanol to water is 6:4 (EtOH / H2O = 6 / 4 (w / w)).

[0072] The mixed solution was added to a sealed tube equipped with a magnetic bar. After three freeze-vacuum-thaw cycles, the sealed tube was vacuum-sealed and kept in an 80 ℃ oil bath for 20 h. The reaction formula is as follows:

[0073]

[0074] After the reaction is completed, the polymerization reaction is quenched by cooling to prepare the target degree of polymerization (DP PMAEAC ) is 100 cationic polymer microspheres 3-1.

[0075] Example 8

[0076] Example 8 of the present disclosure provides a method for preparing cationic polymer microspheres, which is different from Example 7 in that the mass ratio of ethanol to water is 5:5 (EtOH / H2O = 5 / 5 (w / w)), and the target degree of polymerization (DP PMAEAC ) is 100. The other preparation processes of the cationic polymer microspheres in Example 8 are the same as those in Example 7.

[0077] Example 9

[0078] Example 9 of the present disclosure provides a method for preparing cationic polymer microspheres. The difference from Example 7 is that the mass ratio of ethanol to water is 4:6 (EtOH / H2O = 4 / 6 (w / w)), and the target degree of polymerization (DP PMAEAC ) is 100. The other preparation processes of the cationic polymer microspheres in Example 9 are the same as those in Example 7.

[0079] The obtained cationic polymer microspheres 3-1, 3-2, and 3-3 were diluted to 0.50 mg / g in ethanol aqueous solution and characterized by scanning electron microscope (SEM). Figure 3 This is a scanning electron microscope image of the cationic polymer microspheres prepared in Examples 7 to 9 of the present disclosure.

[0080] like Figure 3 As shown, the prepared cationic polymer microspheres are uniform in size, and the average particle size decreases with the increase of water content in the mixed solvent.

[0081] The cationic polymer microspheres prepared in Examples 1 to 9 were subjected to dynamic light scattering (DLS) particle size test and Zeta potential test. Table 1 is a table of DLS particle size test and Zeta potential test data of the cationic polymer microspheres prepared in Examples 1 to 9.

[0082] Table 1

[0083]

[0084] As shown in Table 1, the Zeta potential of the cationic polymer microspheres prepared in Examples 1 to 9 of the present disclosure is all above 25 mV, indicating strong system stability, and the particle size polydispersity index (PDI) is less than 0.1, indicating that the prepared cationic polymer microspheres have good monodispersity.

[0085] The present invention introduces cationic macromolecular chain transfer agents and aromatic monomers into the polymerization system, and successfully prepares monodisperse cationic polymer microspheres through electrostatic repulsion and π-π interaction. The cationic macromolecular chain transfer agent imparts positive charge to the surface of the microspheres, generating electrostatic repulsion to prevent aggregation, thereby ensuring the monodispersity of the microspheres; the π-π interaction of the aromatic monomers accelerates the nucleation and uniform growth of the polymer, further improving the polymerization efficiency and the uniformity of the microspheres. In addition, the parameters in the polymerization process, such as reaction temperature, time, reagent type and dosage, can be flexibly controlled in the existing polymerization system, thereby optimizing the particle size, surface charge density and dispersity of the cationic polymer microspheres. The preparation method disclosed in the present invention is not only applicable to a variety of aromatic monomers and cationic macromolecular chain transfer agents, but also can achieve efficient polymerization reactions in different solvent systems, showing wide applicability and scalability, and providing a new technical path for the preparation of high-performance cationic polymer microspheres, which has important scientific significance and application value.

[0086] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above description is only a specific embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A method for preparing cationic polymer microspheres, characterized in that: The preparation method comprises: Mixing a chain transfer agent, an aromatic monomer, and an initiator in water and an organic solvent to obtain a mixed solution, wherein the chain transfer agent is a cationic macromolecular chain transfer agent with a molecular weight greater than 8000, and the aromatic monomer contains at least two benzene ring structures; The mixed solution is vacuum sealed and heated to initiate polymerization and self-assembly processes to form cationic polymer microspheres.

2. The preparation method according to claim 1, characterized in that: The chain transfer agent has a structure as shown in formula (I) or formula (II): Formula (I), Formula (II), wherein include: Any one of polymethacryloyloxyethyl trimethyl ammonium chloride and polyacryloyloxyethyl trimethyl ammonium chloride, 40≤n≤110.

3. The preparation method according to claim 1, characterized in that: The aromatic monomer includes any one of methacryloyloxyethyl anthracene carboxylate, methacryloyloxyethyl naphthoate, diphenylmethyl methacrylate, and phenoxyphenyl methacrylate.

4. The preparation method according to claim 1, characterized in that: The initiator includes any one of a thermal initiator, a photoinitiator, and a redox initiator; The molar ratio of the chain transfer agent, the aromatic monomer and the initiator is 1:(100-200):0.

20.

5. The preparation method according to claim 1, characterized in that: The organic solvent includes any one of an alcohol solvent, a sulfoxide solvent, and an ether solvent. Wherein, the mass ratio of the organic solvent to water is (6~4):(4~6).

6. The preparation method according to claim 1, characterized in that: The vacuum sealing and heating of the mixed liquid comprises: The mixed solution is vacuum sealed and heated to 70-80°C for 10-20 hours.

7. The preparation method according to claim 1, characterized in that: The solid content of the cationic polymer microspheres is 14% to 28%.

8. The preparation method according to claim 1, characterized in that: The preparation method further comprises: After the polymerization reaction and the self-assembly process are completed, the cationic polymer microspheres are obtained after quenching, centrifugation, precipitation and drying.

9. A cationic polymer microsphere obtained by the preparation method according to any one of claims 1 to 8, characterized in that: The cationic polymer microspheres include a core formed by polymerization of aromatic monomers and a cationic polymer layer covering the core.

10. The cationic polymer microspheres according to claim 9, characterized in that The zeta potential value of the polymer microspheres is greater than 25 mv; The particle size of the polymer microspheres is 100-500 nm; The particle size polydispersity coefficient of the polymer microspheres is less than 0.1.

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