Cationic polymeric microspheres and methods for their preparation

Abstract

The present disclosure provides a kind of cationic polymer microspheres and its preparation method. Among them, the preparation method of cationic polymer microspheres includes: chain transfer agent, aromatic monomer, initiator are mixed in water and organic solvent, obtain mixed solution, wherein the chain transfer agent is the cationic macromolecular chain transfer agent with molecular weight greater than 8000, and the aromatic monomer includes at least two benzene ring structures;The mixed solution is vacuum sealed and heated to initiate polymerization and self-assembly process, to form cationic polymer microspheres.

Description

Technical Field

[0001] This disclosure relates to the field of polymer nanomaterials technology, and in particular to a cationic polymer microsphere and its preparation method. Background Technology

[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 narrow size distribution are crucial.

[0003] Common methods for preparing polymer microspheres include suspension polymerization, precipitation polymerization, emulsion polymerization, dispersion polymerization, and seed polymerization. Different polymerization methods can produce 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, there is an urgent need to develop new methods for preparing cationic polymer microspheres to meet the needs of high-performance applications. Summary of the Invention

[0004] In view of this, the main objective of this disclosure is to provide a cationic polymer microsphere and a method for preparing the same, in order to at least partially solve at least one of the aforementioned technical problems.

[0005] To achieve the above objectives, the technical solution disclosed herein is as follows:

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

[0007] A chain transfer agent, an aromatic monomer, and an initiator are mixed in water and an organic solvent to obtain a mixture, 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 mixture is vacuum-sealed and heated to initiate polymerization and self-assembly processes, forming cationic polymer microspheres.

[0009] As a second aspect of this disclosure, a cationic polymer microsphere prepared by the above-described method is provided, the cationic polymer microsphere comprising a core formed by the polymerization of aromatic monomers and a cationic polymer layer covering the core.

[0010] According to embodiments of this disclosure, a method for preparing cationic polymer microspheres is provided, which utilizes a cationic macromolecular chain transfer agent and an aromatic monomer containing at least two benzene ring structures to prepare monodisperse cationic polymer microspheres. During the polymerization reaction, the solubilizing cationic macromolecular chain transfer agent regulates the polymerization reaction of the solubilizing aromatic monomer, gradually forming an amphiphilic block polymer. As the polymerization reaction proceeds, the length ratio of the solubilizing chain segment to the solubilizing chain segment continuously increases, driving the amphiphilic block polymer to undergo a self-assembly process in a selective solvent, forming cationic polymer microspheres.

[0011] According to embodiments of this disclosure, the cationic polymer microspheres prepared by the method proposed in this disclosure have adjustable particle size and good monodispersity. Furthermore, the microspheres have a positively charged surface, exhibiting good stability. Attached Figure Description

[0012] Figure 1 These are scanning electron microscope images of the cationic polymer microspheres prepared in Examples 1-3 of this disclosure;

[0013] Figure 2 These are scanning electron microscope images of the cationic polymer microspheres prepared in Examples 4-6 of this disclosure;

[0014] Figure 3 These are scanning electron microscope images of the cationic polymer microspheres prepared in Examples 7-9 of this disclosure. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided 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 such ranges or values ​​should be understood to include values ​​close to such ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in this disclosure.

[0017] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit this disclosure. The terms “comprising,” “including,” etc., as used herein indicate the presence of the stated features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0018] Currently, common methods for preparing polymer microspheres include suspension polymerization, precipitation polymerization, emulsion polymerization, dispersion polymerization, and seed polymerization. Among these, dispersion polymerization is an excellent method for preparing monodisperse microspheres due to its ease of operation. However, the preparation of surface-functionalized polymer microspheres using dispersion polymerization often faces challenges. One method of dispersion polymerization involves the dispersion copolymerization of functional monomers, but this method results in most functional groups being embedded within the particles, making full utilization impossible. Another method uses stabilizers containing functional groups, but this often only yields polydisperse polymer microspheres. Furthermore, other preparation methods also suffer from insufficient particle stability, poor monodispersity, low surface charge density, or cumbersome operation. Therefore, the preparation of uniformly sized monodisperse polymer microspheres using functionalized stabilizers remains technically challenging.

[0019] In realizing the concept of this disclosure, it was discovered that reversible addition-fragmentation chain transfer (RAFT) polymerization can obtain nanoparticles with different morphologies, including spherical micelles, worm-like micelles, and vesicles, through a polymerization-induced self-assembly (PISA) mechanism. Based on this, this disclosure proposes a method for preparing cationic polymer microspheres, utilizing a cationic macromolecular RAFT reagent and an aromatic monomer to undergo polymerization and self-assembly under the action of an initiator. The electrostatic repulsion between the cationic macromolecular RAFT reagent segments ensures the spherical morphology of the polymer microspheres, while the π-π stacking interactions in the polymer segments formed by the aromatic monomer promote the rapid nucleation of block polymers, accelerating the formation of cationic polymer microspheres. This disclosure employs a one-pot synthesis method, which is simple and easy to control. The prepared polymer microspheres exhibit good monodispersity and adjustable particle size, overcoming the limitations of existing technologies and providing a universal and efficient new route for preparing monodisperse polymer microspheres.

[0020] According to one aspect of this disclosure, a method for preparing cationic polymer microspheres is provided, comprising:

[0021] A chain transfer agent, an aromatic monomer, and an initiator are mixed in water and an organic solvent to obtain a mixture, 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 mixture is vacuum-sealed and heated to initiate polymerization and self-assembly processes, forming cationic polymer microspheres.

[0023] According to embodiments of this disclosure, the method for preparing cationic polymer microspheres achieves efficient preparation of cationic polymer microspheres by combining a cationic macromolecular RAFT reagent with an aromatic monomer containing at least two benzene ring structures. During the polymerization reaction, the solubilizing cationic macromolecular RAFT reagent regulates the polymerization reaction of the solubilizing aromatic monomer, gradually polymerizing to form an amphiphilic block polymer. As the polymerization reaction proceeds, the length ratio of the solubilizing chain segment to the solubilizing chain segment continuously increases, and the amphiphilic block polymer undergoes self-assembly in a selective solvent to form cationic polymer microspheres. The strong electrostatic repulsion between the cationic macromolecular RAFT reagent chains effectively restricts the fusion transformation of the block polymer microsphere morphology, thereby ensuring that the polymer exhibits only a spherical morphology. Meanwhile, the strong π-π stacking interaction between the benzene ring structures in the aromatic polymer blocks not only promotes the rapid nucleation of the polymer, but also allows the polymerization reaction to take place within the nucleus, significantly accelerating the synthesis rate of polymer microspheres and completing the preparation of microspheres in a short time. This avoids the occurrence of secondary nucleation, resulting in the formation of cationic polymer microspheres exhibiting excellent monodispersity.

[0024] According to embodiments of this disclosure, the preparation method of cationic polymer microspheres involves quenching, centrifugation, precipitation, and drying after the polymerization reaction and self-assembly process are completed. In practical applications, cationic polymer microspheres can also be obtained by quenching, dialysis, and drying. Exemplarily, cooling quenching can be used to rapidly terminate the polymerization reaction, preventing over-polymerization or side reactions, thereby ensuring that the structure and properties of the polymer microspheres meet the intended design. The obtained cationic polymer microspheres can be diluted with a mixed solution of ethanol and water, then centrifuged, washed, and circulated three times to remove unreacted monomers and initiators, ensuring the purity and stability of the microspheres. Drying methods can include, for example, freeze-drying, which removes moisture through low-temperature freezing and vacuum sublimation, avoiding microsphere structural damage or agglomeration caused by direct heating, thus maintaining the morphology and dispersibility of the microspheres while ensuring product stability.

[0025] According to embodiments of this disclosure, vacuum sealing and heating of the mixture includes: adding the mixture to a sealing tube, and performing three cycles of freezing-vacuuming-thawing to ensure that the gas inside the sealing tube is fully discharged, avoiding interference from impurities such as oxygen on the polymerization reaction. After completing the cycle, the sealing tube is vacuum sealed and heated to 70-80 °C, for example, 70 °C, 73 °C, 75 °C, 77 °C, 80 °C, etc. The reaction is maintained at this temperature for 10-20 h, for example, 10 h, 13 h, 15 h, 17 h, 20 h, etc. Suitable 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 extent 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, ensuring the performance and stability of the polymer microspheres.

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

[0027] Formula (I),

[0028] Equation (II), where, include:

[0029] The chain transfer agent is selected from either polymethacryloyloxyethyltrimethylammonium chloride or polyacryloyloxyethyltrimethylammonium chloride. A cationic macromolecular chain transfer agent with a positive charge is chosen, capable of forming a uniformly distributed positively charged layer on the surface of the polymer microspheres. This positively charged layer not only helps improve the monodispersity of the microspheres but also prevents microsphere aggregation through electrostatic repulsion, thereby ensuring good monodispersity and stability of the microspheres. Where 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, thereby adjusting the particle size and surface charge density of the cationic polymer microspheres.

[0030] Exemplarily, the chain transfer agent used in this disclosure is polymethacryloyloxyethyltrimethylammonium chloride (PMATAC). 55 -PETTC) can be synthesized through 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 chalcant. After three freeze-vacuum-thaw cycles, the tube was vacuum-sealed. The tube was then placed in an oil bath at 45°C and stirred for polymerization for 7 hours, followed by quenching the polymerization reaction by cooling. Next, the reaction mixture was dialyzed against methanol to remove unreacted raw materials, then dialyzed against water to replace the methanol, and finally freeze-dried to obtain the product PMATAC. 55 -PETTC.

[0032] According to embodiments of this disclosure, the aromatic monomer includes any one of: methacryloyloxyethyl anthracene ester, methacryloyloxyethyl naphthate ester, diphenyl methyl methacrylate, and phenoxyphenyl methacrylate. The aromatic monomer contains at least two benzene ring structures, preferably two to three benzene ring structures. Aromatic monomers with only one benzene ring structure have a smaller number of benzene rings, resulting in weaker π-π stacking interactions, leading to a slower nucleation rate of polymer microspheres and difficulty in rapidly forming uniform microsphere structures. Furthermore, an excessive number of benzene rings reduces the solubility of the aromatic monomer, making it difficult for the polymerization reaction to proceed uniformly, thus affecting the uniformity and dispersibility of the microspheres. Therefore, selecting aromatic monomers containing two to three benzene rings can ensure rapid nucleation of polymer microspheres while maintaining good solubility, thereby achieving the preparation of uniform, monodisperse polymer microspheres.

[0033] By way of example, the aromatic monomer methacryloyloxyethyl anthracene ester (MAEAC) used in this disclosure can be synthesized by the following steps:

[0034] 10.00 g (44.99 mmol) of 9-anthracarboxylic acid and 100 mL of thionyl chloride were added to a 250 mL round-bottom flask. A reflux condenser and tail gas absorption apparatus was set up, and the reaction was stirred at 75 °C for 10 h to complete the formation of acyl chloride. The residual thionyl chloride was removed by rotary evaporation under reduced pressure (evaporation to dryness). The product after evaporation 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 the reaction was allowed to proceed for 12 h at room temperature. After the reaction was complete, the generated salt was removed by filtration, and the product was evaporated to dryness under reduced pressure to obtain crude MAEAC, which was further purified by column chromatography to obtain MAEAC.

[0036] By way of example, the aromatic monomer methacryloyloxyethyl naphthate (MAENC) used in this 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). 1-Naphthoyl chloride (25.00 g, 131.14 mmol) was slowly added at 0 °C, and the reaction was continued at room temperature for 12 h. After removing solid byproducts by filtration, the filtrate was concentrated and purified by column chromatography to obtain MAENC.

[0038] According to embodiments of this 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, aromatic monomer, and initiator is 1:(100~200):0.20, for example, 1:100:0.2, 1:120:0.2, 1:150:0.2, 1:170:0.2, or 1:200:0.2. By precisely controlling the ratio of the chain transfer agent, aromatic monomer, and initiator, a balance between rapid nucleation and uniform growth can be achieved during polymerization, avoiding secondary nucleation and ensuring that the microspheres have good monodispersity and morphological stability.

[0039] According to embodiments of this disclosure, the organic solvent includes any one of alcohol solvents, sulfoxide solvents, alkane solvents, and ether solvents, wherein the mass ratio of organic solvent to water is (6~4):(4~6), for example, 6:4, 5:5, 4:6, etc. The ratio of organic solvent to water affects the polymerization process. When the amount of organic solvent is too high and the amount of water is too low, the nucleation time will be significantly prolonged, leading to uneven particle size distribution of microspheres and even potential agglomeration, affecting the quality and performance of the microspheres. When the water content is too high and the organic solvent is too low, the solubility of the system will decrease, affecting the dissolution of aromatic monomers and chain transfer agents, thereby reducing the efficiency of the polymerization reaction. Insufficient solubility may also lead to uneven surface of the polymer microspheres, affecting the morphology and performance of the cationic polymer microspheres.

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

[0041] According to another aspect of this disclosure, a cationic polymer microsphere prepared by the above preparation method is provided, the cationic polymer microsphere comprising a core formed by the polymerization of aromatic monomers and a cationic polymer layer covering the core.

[0042] According to embodiments of this disclosure, the zeta potential 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 microsphere surface carries abundant positive charges, which not only enhances the stability of the microspheres in solution but also makes them exhibit stronger interaction capabilities in adsorption and separation applications. The particle size of the polymer microspheres is 100~500 nm, for example, 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, etc. By controlling the particle size, the cationic polymer microspheres can meet the needs of various application scenarios, such as biomedical detection, drug delivery, and nanomaterial preparation. The polydispersity index of the polymer microspheres is less than 0.1, and the polydispersity index can be, for example, 0.09, 0.07, 0.05, 0.03, etc. The low polydispersity index indicates that the cationic polymer microspheres have a highly consistent particle size distribution, which not only ensures the performance uniformity of the microspheres in practical applications, but also significantly improves their applicability in high-precision fields.

[0043] According to embodiments of this disclosure, the cationic polymer microspheres prepared herein can be used in fields such as drug carriers, adsorption separation, and antibacterial applications. For example, by introducing positively charged groups through a quaternization reaction, treated polystyrene microspheres can be used for the adsorption of anionic pollutants in water. Quaternized cationic copolymer microspheres exhibit excellent antibacterial activity; when added to coatings, the antibacterial rate can still exceed 95%, providing a pathway for the development of antibacterial coatings. Furthermore, cationic microspheres are more effective than anionic and nonionic microspheres as flocculants in papermaking and wastewater treatment, and are also frequently used in cosmetics and personal care products.

[0044] To make the objectives, technical solutions, and advantages of this disclosure clearer, the following detailed description is provided in conjunction with specific embodiments. Unless otherwise specified, all methods described in the embodiments are conventional and can be performed according to the techniques or conditions described in the literature or the product manual.

[0045] Example 1:

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

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

[0048] The mixture was added to a sealed tube containing a magnetic magnet. After three cycles of freezing-vacuuming-thawing, the tube was vacuum-sealed and the reaction was carried out in a 70 °C oil bath for 20 h. The reaction formula is shown below:

[0049]

[0050] After the reaction is complete, the polymerization reaction is quenched by cooling to obtain the target degree of polymerization (DP). PMAEAC 1-1. Cationic polymer microspheres with a value of 100.

[0051] Example 2

[0052] Example 2 of this disclosure provides a method for preparing cationic polymer microspheres, which differs from Example 1 in that the method yields microspheres with a target degree of polymerization (DP). PMAEAC The cationic polymer microspheres 1-2 have a particle size of 150. The other preparation processes for the cationic polymer microspheres in Example 2 are the same as in Example 1.

[0053] Example 3

[0054] Example 3 provides a method for preparing cationic polymer microspheres, which differs from Example 1 in that the method yields microspheres with a target degree of polymerization (DP). PMAEACThe cationic polymer microspheres 1-3 have a particle size of 200. The other preparation processes for the cationic polymer microspheres in Example 3 are the same as in Example 1.

[0055] The obtained cationic polymer microspheres 1-1, 1-2, and 1-3 were diluted to 0.50 mg / g in an ethanol-water solution and then characterized by scanning electron microscopy (SEM). Figure 1 These are scanning electron microscope images of the cationic polymer microspheres prepared in Examples 1-3 of this disclosure.

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

[0057] Example 4:

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

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

[0060] The mixture was added to a sealed tube containing a magnetic magnet. After three cycles of freezing-vacuuming-thawing, the tube was vacuum-sealed and the reaction was carried out in a 70 °C oil bath for 20 h. The reaction formula is shown below:

[0061]

[0062] After the reaction is complete, the polymerization reaction is quenched by cooling to obtain the target degree of polymerization (DP). PMAENC 2-1. Cationic polymer microspheres with a value of 100.

[0063] Example 5

[0064] Example 5 of this disclosure provides a method for preparing cationic polymer microspheres, which differs from Example 4 in that the method yields microspheres with a target degree of polymerization (DP).PMAENC The cationic polymer microspheres in Example 5 have a particle size of 150. All other preparation processes for the cationic polymer microspheres in Example 5 are the same as in Example 4.

[0065] Example 6

[0066] Example 6 of this disclosure provides a method for preparing cationic polymer microspheres, which differs from Example 4 in that the method yields microspheres with a target degree of polymerization (DP). PMAENC The cationic polymer microspheres in Example 6 have a particle size of 200. All other preparation processes for the cationic polymer microspheres in Example 6 are the same as in Example 4.

[0067] The obtained cationic polymer microspheres 2-1, 2-2, and 2-3 were diluted to 0.50 mg / g in an ethanol-water solution and then characterized by scanning electron microscopy (SEM). Figure 2 These are scanning electron microscope images of the cationic polymer microspheres prepared in Examples 4-6 of this disclosure.

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

[0069] Example 7:

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

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

[0072] The mixture was added to a sealed tube containing a magnetic magnet. After three cycles of freezing-vacuuming-thawing, the tube was vacuum-sealed and the reaction was carried out in an 80 °C oil bath for 20 h. The reaction formula is shown below:

[0073]

[0074] After the reaction is complete, the polymerization reaction is quenched by cooling to obtain the target degree of polymerization (DP). PMAEAC 3-1. Cationic polymer microspheres with a value of 100.

[0075] Example 8

[0076] Example 8 of this disclosure provides a method for preparing cationic polymer microspheres. The difference from Example 7 is that the mass ratio of ethanol to water is 5:5 (EtOH / H2O = 5 / 5 (w / w)), and the resulting microspheres have the target degree of polymerization (DP). PMAEAC 3-2 cationic polymer microspheres with a value of 100. The other preparation processes for the cationic polymer microspheres in Example 8 are the same as in Example 7.

[0077] Example 9

[0078] Example 9 of this 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 resulting microspheres have the target degree of polymerization (DP). PMAEAC The cationic polymer microspheres in Example 9 have a value of 100. All other preparation processes for the cationic polymer microspheres in Example 9 are the same as in Example 7.

[0079] The obtained cationic polymer microspheres 3-1, 3-2, and 3-3 were diluted to 0.50 mg / g in an ethanol-water solution and then characterized by scanning electron microscopy (SEM). Figure 3 These are scanning electron microscope images of the cationic polymer microspheres prepared in Examples 7-9 of this disclosure.

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

[0081] The cationic polymer microspheres prepared in Examples 1-9 were subjected to dynamic light scattering (DLS) particle size and zeta potential tests. Table 1 shows the DLS particle size and zeta potential test data of the cationic polymer microspheres prepared in Examples 1-9.

[0082] Table 1

[0083]

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

[0085] This disclosure introduces cationic macromolecular chain transfer agents and aromatic monomers into a polymerization system, successfully preparing monodisperse cationic polymer microspheres through electrostatic repulsion and π-π interactions. The cationic macromolecular chain transfer agent imparts a positive charge to the surface of the microspheres, generating electrostatic repulsion to prevent aggregation, thus ensuring the monodispersity of the microspheres. The π-π interactions of the aromatic monomers accelerate polymer nucleation and uniform growth, further improving polymerization efficiency and microsphere uniformity. Furthermore, polymerization parameters, such as reaction temperature, time, reagent type and dosage, can be flexibly controlled within existing polymerization systems, thereby optimizing the particle size, surface charge density, and dispersibility of the cationic polymer microspheres. The preparation method disclosed herein is applicable not only to various aromatic monomers and cationic macromolecular chain transfer agents but also to efficient polymerization reactions in different solvent systems, demonstrating broad applicability and scalability. It provides a new technical route for the preparation of high-performance cationic polymer microspheres, possessing significant scientific and application value.

[0086] The specific embodiments described above further illustrate the purpose, technical solutions, and beneficial effects of this disclosure. It should be understood that the above descriptions are merely specific embodiments of this disclosure and are not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A process for the preparation of cationic polymeric 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 comprises at least two benzene ring structures; vacuum sealing and heating the mixed solution to initiate a polymerization reaction and a self-assembly process, thereby forming cationic polymer microspheres, wherein the chain transfer agent has a structure as shown in formula (I) or formula (II): formula (I), Formula (II), wherein, comprises: any one of polymethacryloyloxyethyl trimethyl ammonium chloride or polyacryloyloxyethyl trimethyl ammonium chloride, 40≤n≤110, the aromatic monomer comprises any one of methacryloyloxyethyl anthracene formate, methacryloyloxyethyl naphthalene formate, diphenyl methyl methacrylate or phenoxy benzyl methacrylate.

2. The preparation method according to claim 1, wherein the initiator comprises any one of a thermal initiator, a photoinitiator or a redox initiator; a molar ratio of the chain transfer agent, the aromatic monomer and the initiator is 1: (100-200): 0.

20.

3. The preparation method according to claim 1, wherein the organic solvent comprises any one of an alcohol solvent, a sulfoxide solvent or an ether solvent, wherein a mass ratio of the organic solvent to water is (6-4):(4-6).

4. The preparation method according to claim 1, wherein the vacuum sealing and heating of the mixed solution comprises: after vacuum sealing the mixed solution, heating to 70-80 ℃ and maintaining the temperature for 10-20 h.

5. The preparation method according to claim 1, wherein a solid content of the cationic polymer microspheres is 14%-28%.

6. The method of claim 1, wherein, 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.

7. Cationic polymeric microspheres prepared by the process according to any one of claims 1 to 6, characterized in that The cationic polymer microspheres comprise a core formed by polymerization of the aromatic monomer and a cationic polymer layer covering the core.

8. The cationic polymer microspheres according to claim 7, wherein a Zeta potential value of the polymer microspheres is greater than 25 mv; a particle size of the polymer microspheres is 100-500 nm; a particle size polydispersity coefficient of the polymer microspheres is less than 0.1.

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