Monodisperse polymethyl methacrylate surface-modified microspheres and method for preparing the same

Abstract

The application provides monodisperse polymethyl methacrylate surface modified microspheres and a preparation method thereof, and belongs to the technical field of microsphere modification. The preparation method comprises the following steps: ultrasonic dispersion is performed on monodisperse polymethyl methacrylate microspheres and an organic solvent to obtain pretreated polymethyl methacrylate microsphere suspension; the pretreated polymethyl methacrylate microsphere suspension, a modifier and a catalyst are reacted to obtain monodisperse polymethyl methacrylate surface modified microspheres. The method can effectively maintain the uniform particle size advantage of the monodisperse PMMA microspheres; the modification uniformity is good, the functional group is controllable; the performance of the microsphere body is not damaged; the surface activity of the modified monodisperse PMMA microspheres is significantly improved, and the dispersibility and compatibility are greatly improved.

Description

Technical Field

[0001] This invention relates to the field of microsphere modification technology, and in particular to a monodisperse polymethyl methacrylate surface-modified microsphere and its preparation method. Background Technology

[0002] Polymethyl methacrylate (PMMA) monodisperse microspheres, due to their outstanding advantages such as uniform particle size, high transparency, excellent biocompatibility, and ease of synthesis, have been widely used in various fields, including chromatographic packing materials, bioseparation, optical materials, battery separators, and antibacterial materials, playing an important role in high-end manufacturing and biopharmaceutical industries. However, the surface of PMMA monodisperse microspheres contains only ester and methyl groups, exhibiting strong chemical inertness and low surface energy, which limits their application in a wider range of scenarios. Therefore, surface modification treatment has become an essential requirement.

[0003] Currently, extensive research has been conducted on surface modification methods for PMMA monodisperse microspheres. Physical modification, mainly including plasma treatment and irradiation modification, has advantages such as being pollution-free, having a fast processing speed, and high grafting efficiency, but it also suffers from problems such as easy attenuation of modification effects, expensive equipment, and difficulty in large-scale production. Adding functional monomers during MMA polymerization for copolymerization can introduce functional groups onto the surface of PMMA microspheres. However, this method has low functionalization efficiency, and the addition of monomers has a significant impact on the particle size of the microspheres. Patent CN 120944025A reports the mixing of microspheres with double-bonded olefins on their surface with alkenyl functional group molecules and azo initiators, followed by an addition reaction to obtain microspheres with surface functionalizations such as carboxyl, amino, and sulfonic acid groups; however, it does not mention the uniformity of microsphere particle size.

[0004] Therefore, there is an urgent need to develop a mild, efficient, and controllable method for surface modification of PMMA monodisperse microspheres. This method should accurately introduce target functional groups while effectively maintaining the monodispersity of the microspheres, significantly improving the overall performance of the microspheres, overcoming the aforementioned shortcomings of existing technologies, and expanding their application scope in high-end fields. Summary of the Invention

[0005] The purpose of this invention is to provide a monodisperse polymethyl methacrylate (PMMA) surface-modified microsphere and its preparation method, aiming to maintain the monodispersity and particle size of the microspheres while controllably grafting hydroxyl, amino, or carboxyl functional groups onto their surface to achieve functionalization of the PMMA microsphere surface.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a method for preparing monodisperse polymethyl methacrylate surface-modified microspheres, comprising the following steps: 1) Monodisperse polymethyl methacrylate microspheres and organic solvents were ultrasonically dispersed to obtain a pretreated polymethyl methacrylate microsphere suspension; 2) The pretreated polymethyl methacrylate microsphere suspension, modifier and catalyst were reacted to obtain monodisperse polymethyl methacrylate surface modified microspheres; The modifier is a hydroxyl-containing compound, an amino-containing compound, or a compound containing both carboxyl and hydroxyl groups.

[0007] Preferably, the monodisperse polymethyl methacrylate microspheres in step 1) have a particle size of 10 nm to 100 μm and a coefficient of variation of ≤10%; the organic solvent includes one or more of toluene, xylene and isopropanol.

[0008] Preferably, the mass ratio of the monodisperse polymethyl methacrylate microspheres to the organic solvent in step 1) is 1~10:100.

[0009] Preferably, the modifier in step 2) comprises one or more of ethylene glycol, polyethylene glycol, polyethylene glycol monomethyl ether, ethanolamine, N-thioethylenediamine, N-thiodiaminopropane, glycerol, tetraethylenepentamine, glycolic acid, 3-hydroxypropionic acid, and lactic acid; and the catalyst is one or more of sodium methoxide, sodium hydroxide, potassium hydroxide, sodium carbonate, and zinc acetate.

[0010] Preferably, the mass ratio of the modifier in step 2) to the monodisperse polymethyl methacrylate microspheres in step 1) is 0.2~20:1; the mass of the catalyst is 0.5~5% of the mass of the monodisperse polymethyl methacrylate microspheres.

[0011] Preferably, the reaction temperature in step 2) is 60~100℃ and the reaction time is 2~10h.

[0012] Preferably, the products after the reaction in step 2) are cooled and centrifuged sequentially to obtain solid products. The solid products are then washed and dried sequentially to obtain monodisperse polymethyl methacrylate surface-modified microspheres.

[0013] Preferably, the centrifugation speed is 2000~8000 r / min, and the centrifugation time is 3~15 min; the washing reagents are organic solvent and water, and the number of washings with organic solvent and water is 3~5 times independently; the drying temperature is 60~80℃, and the drying time is 4~6 h.

[0014] The present invention also provides monodisperse polymethyl methacrylate surface-modified microspheres prepared by the preparation method described above, wherein the surface of the monodisperse polymethyl methacrylate surface-modified microspheres is grafted with one or more of hydroxyl, amino and carboxyl groups, and the particle size of the monodisperse polymethyl methacrylate surface-modified microspheres is 10 nm to 100 μm.

[0015] The beneficial effects of this invention are: 1) Effectively maintains the uniformity of monodisperse PMMA microspheres: This invention uses a mild transesterification reaction with controllable reaction conditions, avoiding damage to the microsphere structure. The coefficient of variation of the modified microspheres is ≤5%, preserving their monodispersity and solving the defects of existing technologies that easily lead to microsphere aggregation, swelling, and uneven particle size.

[0016] 2) Good uniformity of modification and controllable functional groups: By precisely controlling the amount of modifier and catalyst, reaction temperature and time, the directional substitution of ester groups on the surface of microspheres can be achieved, and the thickness of the modified layer is uniform; different functional modifiers can be selected according to the target application requirements, and the surface properties of microspheres can be flexibly adjusted.

[0017] 3) The microsphere bulk properties are not damaged: The transesterification reaction of the present invention only occurs on the surface of monodisperse PMMA microspheres and does not involve the polymerization or degradation of the microsphere bulk. This solves the defect of excessive modification leading to a decrease in the bulk properties of microspheres in the prior art, and takes into account both surface functional modification and bulk property stability.

[0018] 4) The surface activity of the modified monodisperse PMMA microspheres is significantly improved, and the dispersibility and compatibility are greatly enhanced. They can effectively bond with inorganic particles, biomolecules and other polymers, avoiding aggregation in polar or aqueous systems.

[0019] 5) Simple process, low cost, and scalable production: The modification process of this invention does not require complex equipment, the steps are simple, the pretreatment, transesterification reaction and post-treatment processes are easy to operate, and the organic solvents, modifiers and catalysts used are all conventional chemical raw materials, which are easy to obtain and have low cost; the reaction conditions are mild, no high temperature and high pressure are required, energy consumption is low, the post-treatment is simple, and industrial-scale production can be realized. Attached Figure Description

[0020] Figure 1 Scanning electron microscope image of the monodisperse PMMA surface carboxyl-modified microspheres prepared in Example 5; Figure 2 Fourier transform infrared spectra of the original monodisperse PMMA microspheres of Example 3, the monodisperse PMMA surface hydroxyl-modified microspheres, and the monodisperse PMMA surface carboxyl-modified microspheres of Example 5. Detailed Implementation

[0021] This invention provides a method for preparing monodisperse polymethyl methacrylate surface-modified microspheres, comprising the following steps: 1) Monodisperse polymethyl methacrylate microspheres (monodisperse PMMA microspheres) and organic solvents are ultrasonically dispersed to obtain a pretreated polymethyl methacrylate microsphere suspension; 2) The pretreated polymethyl methacrylate microsphere suspension, modifier and catalyst were reacted to obtain monodisperse polymethyl methacrylate surface modified microspheres; The modifier is a hydroxyl-containing compound, an amino-containing compound, or a compound containing both carboxyl and hydroxyl groups.

[0022] In this invention, the particle size of the monodisperse polymethyl methacrylate microspheres in step 1) is preferably 10 nm to 100 μm, more preferably 100 nm to 10 μm, and even more preferably 500 nm to 1 μm; the coefficient of variation of the monodisperse polymethyl methacrylate microspheres (… C V d The organic solvent preferably contains ≤10%, more preferably ≤5%, and even more preferably ≤3%; the organic solvent preferably contains one or more of toluene, xylene and isopropanol.

[0023] The monodisperse polymethyl methacrylate microspheres of the present invention are prepared by dispersion polymerization or emulsion polymerization, and the coefficient of variation ensures the monodispersity advantage of the microspheres; the organic solvent is an organic solvent that has been dried by anhydrous calcium chloride and 3A molecular sieve.

[0024] In this invention, the mass ratio of the monodisperse polymethyl methacrylate microspheres and the organic solvent in step 1) is preferably 1~10:100, more preferably 3~8:100, and even more preferably 4~6:100.

[0025] The mass ratio of monodisperse polymethyl methacrylate microspheres to organic solvent in this invention can ensure good dispersion of PMMA microspheres, improve the solubility of modifiers and catalysts, and accelerate the reaction.

[0026] In this invention, the modifier in step 2) preferably comprises one or more of ethylene glycol, polyethylene glycol, polyethylene glycol monomethyl ether, ethanolamine, N-thioethylenediamine, N-thiodiaminopropane, glycerol, tetraethylenepentamine, glycolic acid, 3-hydroxypropionic acid, and lactic acid; the catalyst is preferably one or more of sodium methoxide, sodium hydroxide, potassium hydroxide, sodium carbonate, and zinc acetate.

[0027] In this invention, the mass ratio of the modifier in step 2) to the monodisperse polymethyl methacrylate microspheres in step 1) is preferably 0.2~20:1, more preferably 2~15:1, and even more preferably 5~10:1; the mass of the catalyst is preferably 0.5~5% of the mass of the monodisperse polymethyl methacrylate microspheres, more preferably 1~4%, and even more preferably 2~3%.

[0028] In this invention, the reaction temperature in step 2) is preferably 60~100℃, more preferably 70~90℃, and even more preferably 80℃, and the reaction time is preferably 2~10h, more preferably 4~8h, and even more preferably 5~6h.

[0029] In this invention, the reaction in step 2) is carried out under stirring conditions. The stirring rate is preferably 100~500 r / min, more preferably 200~400 r / min, and even more preferably 300 r / min. Under the reaction temperature, time and stirring rate of this invention, the reaction can be fully carried out, while avoiding excessive temperature that could cause the microspheres to swell, agglomerate or degrade.

[0030] In this invention, the ester groups (-COOCH3) on the surface of monodisperse PMMA microspheres undergo a nucleophilic substitution reaction with the modifier under the action of a catalyst, thereby achieving the directional substitution of the ester groups on the PMMA microsphere surface, i.e., transesterification reaction, which grafts target functional groups (such as hydroxyl, amino, carboxyl, etc.) onto the surface of the microspheres. The entire reaction does not involve the breaking and polymerization of the molecular chain backbone, thus effectively preserving the monodispersity and bulk properties of the microspheres. Moreover, the reaction conditions are mild and controllable, and the byproducts are simple and easy to remove, ensuring the stability and consistency of the modification effect.

[0031] In this invention, the products after the reaction in step 2) are sequentially cooled and centrifuged to obtain solid products. The solid products are then sequentially washed and dried to obtain monodisperse polymethyl methacrylate surface-modified microspheres.

[0032] In this invention, the centrifugal separation speed is preferably 2000~8000 r / min, more preferably 3000~7000 r / min, and even more preferably 5000~6000 r / min; the centrifugal separation time is preferably 3~15 min, more preferably 5~12 min, and even more preferably 8~10 min; the washing reagent is preferably an organic solvent and water, and the number of independent washings with organic solvent and water is preferably 3~5 times, and even more preferably 4 times; the organic solvent is preferably anhydrous ethanol; the drying temperature is preferably 60~80℃, more preferably 65~75℃, and even more preferably 70℃; the drying time is preferably 4~6 h, more preferably 4.5~5.5 h, and even more preferably 5 h.

[0033] The present invention also provides monodisperse polymethyl methacrylate surface-modified microspheres prepared by the preparation method described above, wherein the surface of the monodisperse polymethyl methacrylate surface-modified microspheres is grafted with one or more of hydroxyl, amino and carboxyl groups, and the particle size of the monodisperse polymethyl methacrylate surface-modified microspheres is 10 nm to 100 μm.

[0034] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0035] Unless otherwise specified, the methods used in the examples are conventional methods; unless otherwise specified, the materials and reagents used in the examples are commercially available; the monodisperse polymethyl methacrylate microspheres were prepared by emulsion polymerization, which is well known in the art; the specific process for drying toluene with anhydrous calcium chloride and 3A molecular sieve is as follows: first, anhydrous calcium chloride is used to dry toluene at room temperature for 6 hours, and then 3A molecular sieve activated at 350°C for 2 hours in a muffle furnace is added to toluene and dried at room temperature for 24 hours.

[0036] Example 1

[0037] 2g of monodisperse PMMA microspheres with a particle size of 500nm (coefficient of variation of 4.8%) were added to 100g of toluene that had been dried with anhydrous calcium chloride and 3A molecular sieve, and the mixture was dispersed by ultrasonic dispersion (ultrasonic frequency of 20kHz) for 5min to obtain a uniform and stable pretreated PMMA microsphere suspension.

[0038] The pretreated PMMA microsphere suspension, 10g of ethylene glycol, and 0.04g of sodium methoxide were added sequentially to a three-necked flask. Nitrogen gas was introduced for protection, and the mixture was refluxed and stirred at 300r / min at 90℃ for 7h until the reaction was complete.

[0039] After the reaction was completed, the reaction solution was naturally cooled to room temperature and centrifuged at 5000 r / min for 10 min to collect the solid product. The solid product was washed three times each with anhydrous ethanol and deionized water to remove residual solvent, unreacted ethylene glycol and sodium methoxide. The washed solid was placed in a drying oven at 60℃ and dried for 5 h to obtain monodisperse PMMA surface hydroxyl-modified microspheres with a particle size of 510 nm and a coefficient of variation of 5.0%.

[0040] Example 2

[0041] 1g of monodisperse PMMA microspheres with a particle size of 200nm (coefficient of variation of 3.9%) was added to 100g of toluene that had been dried with anhydrous calcium chloride and 3A molecular sieve, and the mixture was dispersed by ultrasonic dispersion (ultrasonic frequency of 20kHz) for 5min to obtain a uniform and stable pretreated PMMA microsphere suspension.

[0042] The pretreated PMMA microsphere suspension, 5g polyethylene glycol (PEG-400), and 0.05g sodium methoxide were added sequentially to a three-necked flask. After sealing the reaction vessel, the mixture was refluxed under nitrogen protection and stirred at 200r / min at 80℃ for 8 hours until the reaction was complete.

[0043] After the reaction was completed, the reaction solution was naturally cooled to room temperature and centrifuged at 6000 r / min for 3 min to collect the solid product. The solid product was washed three times each with anhydrous ethanol and deionized water to remove residual solvent, unreacted polyethylene glycol and sodium methoxide. The washed solid was placed in a drying oven at 60℃ and dried for 5 h to obtain monodisperse PMMA surface hydroxyl-modified microspheres with a particle size of 205 nm and a coefficient of variation of 3.9%.

[0044] Example 3

[0045] 3g of monodisperse PMMA microspheres with a particle size of 500nm (coefficient of variation of 4.3%) were added to 100g of isopropanol that had been dried with anhydrous calcium chloride and 3A molecular sieve. The mixture was then dispersed by ultrasonic dispersion (ultrasonic frequency of 20kHz) for 5min to obtain a uniform and stable pretreated PMMA microsphere suspension.

[0046] The pretreated PMMA microsphere suspension, 15g of polyethylene glycol monomethyl ether, and 0.09g of sodium hydroxide were added sequentially to a three-necked flask. After sealing the reaction vessel, the mixture was refluxed under nitrogen protection and stirred at 400r / min at 90℃ for 5h until the reaction was complete.

[0047] After the reaction was completed, the reaction solution was naturally cooled to room temperature and centrifuged at 6000 r / min for 8 min to collect the solid product. The solid product was washed three times each with anhydrous ethanol and deionized water to remove residual solvent, unreacted polyethylene glycol monomethyl ether and sodium hydroxide. The washed solid was placed in a drying oven at 70℃ and dried for 4.5 h to obtain monodisperse PMMA surface hydroxyl-modified microspheres with a particle size of 510 nm and a coefficient of variation of 4.5%.

[0048] Example 4

[0049] 5g of monodisperse PMMA microspheres with a particle size of 1μm (coefficient of variation of 2.5%) were added to 100g of xylene that had been dried with anhydrous calcium chloride and 3A molecular sieve, and the mixture was dispersed by ultrasonic dispersion (ultrasonic frequency of 20kHz) for 5min to obtain a uniform and stable pretreated PMMA microsphere suspension.

[0050] The pretreated PMMA microsphere suspension, 25g ethanolamine, and 0.15g potassium hydroxide were added sequentially to a three-necked flask. After sealing the reaction vessel, the mixture was refluxed under nitrogen protection and stirred at 300r / min at 85℃ for 7h until the reaction was complete.

[0051] After the reaction was completed, the reaction solution was naturally cooled to room temperature and centrifuged at 5000 r / min for 10 min to collect the solid product. The solid product was washed four times each with anhydrous ethanol and deionized water to remove residual solvent, ethanolamine and potassium hydroxide. The washed solid was placed in a drying oven at 65℃ and dried for 5 h to obtain monodisperse PMMA surface amino-modified microspheres with a particle size of 1.03 μm and a coefficient of variation of 2.8%.

[0052] Example 5

[0053] 20g of monodisperse PMMA microspheres with a particle size of 5.5μm (coefficient of variation of 2.6%) were added to 200g of a toluene-isopropanol mixed solvent (mass ratio of toluene to isopropanol of 1:1) after drying with anhydrous calcium chloride and 3A molecular sieve. The mixture was then dispersed by ultrasonic dispersion (ultrasonic frequency of 20kHz) for 5min to obtain a uniform and stable pretreated PMMA microsphere suspension.

[0054] The pretreated PMMA microsphere suspension, 100g of 3-hydroxypropionic acid, and 0.4g of sodium carbonate were added sequentially to a three-necked flask. After sealing the reaction vessel, the mixture was refluxed under nitrogen protection and stirred at 300r / min at 75℃ for 8 hours until the reaction was complete.

[0055] After the reaction was completed, the reaction solution was naturally cooled to room temperature and centrifuged at 3000 r / min for 3 min to collect the solid product. The solid product was washed three times each with anhydrous ethanol and deionized water to remove residual solvent, unreacted 3-hydroxypropionic acid and sodium carbonate. The washed solid was placed in a drying oven at 60℃ and dried for 6 h to obtain monodisperse PMMA surface carboxyl modified microspheres with a particle size of 5.9 μm and a coefficient of variation of 2.7%.

[0056] Example 6

[0057] 4g of monodisperse PMMA microspheres with a particle size of 10μm (coefficient of variation of 2.4%) were added to 100g of a toluene-xylene mixed solvent (mass ratio of toluene to xylene 3:1) that had been dried with anhydrous calcium chloride and 3A molecular sieve. The mixture was then dispersed by ultrasonic dispersion (ultrasonic frequency of 20kHz) for 5min to obtain a uniform and stable pretreated PMMA microsphere suspension.

[0058] The pretreated PMMA microsphere suspension, 20g glycerol, and 0.08g zinc acetate were added sequentially to a three-necked flask. After sealing the reaction vessel, the mixture was refluxed under nitrogen protection and stirred at 200r / min at 95℃ for 4h until the reaction was complete.

[0059] After the reaction was completed, the reaction solution was naturally cooled to room temperature and centrifuged at 7000 r / min for 8 min to collect the solid product. The solid product was washed four times each with anhydrous ethanol and deionized water to remove residual solvent, unreacted glycerol and zinc acetate. The washed solid was placed in a drying oven at 75℃ and dried for 4 h to obtain monodisperse PMMA surface polyhydroxy modified microspheres with a particle size of 10.5 μm and a coefficient of variation of 2.5%.

[0060] Example 7

[0061] 4g of monodisperse PMMA microspheres with a particle size of 25μm (coefficient of variation of 4.6%) were added to 100g of toluene that had been dried with anhydrous calcium chloride and 3A molecular sieve, and the mixture was dispersed by ultrasonic dispersion (ultrasonic frequency of 20kHz) for 5min to obtain a uniform and stable pretreated PMMA microsphere suspension.

[0062] The pretreated PMMA microsphere suspension, 20g tetraethylenepentamine, and 0.08g zinc acetate were added sequentially to a three-necked flask. After sealing the reaction vessel, the mixture was refluxed under nitrogen protection and stirred at 300r / min at 95℃ for 4h until the reaction was complete.

[0063] After the reaction was completed, the reaction solution was naturally cooled to room temperature and centrifuged at 7000 r / min for 8 min to collect the solid product. The solid product was washed four times each with anhydrous ethanol and deionized water to remove residual solvent, unreacted tetraethylenepentamine and zinc acetate. The washed solid was placed in a drying oven at 75℃ and dried for 4 h to obtain monodisperse PMMA surface amino-modified microspheres with a particle size of 25.8 μm and a coefficient of variation of 4.6%.

[0064] Example 8

[0065] 100g of monodisperse PMMA microspheres with a particle size of 80μm (coefficient of variation of 4.1%) were added to 1000g of toluene that had been dried with anhydrous calcium chloride and 3A molecular sieve, and the mixture was dispersed by ultrasonic dispersion (ultrasonic frequency of 20kHz) for 5min to obtain a uniform and stable pretreated PMMA microsphere suspension.

[0066] The pretreated PMMA microsphere suspension, 20g lactic acid, and 0.08g sodium methoxide-sodium hydroxide moderating catalyst (sodium methoxide and sodium hydroxide in a mass ratio of 1:1) were sequentially added to a three-necked flask. After sealing the reaction vessel, the mixture was refluxed under nitrogen protection and stirred at 300r / min at 100℃ for 4h until the reaction was complete.

[0067] After the reaction was completed, the reaction solution was naturally cooled to room temperature and centrifuged at 2000 r / min for 5 min to collect the solid product. The solid product was washed four times each with anhydrous ethanol and deionized water to remove residual solvent, unreacted lactic acid and mildening catalyst. The washed solid was placed in a drying oven at 75℃ and dried for 4 h to obtain monodisperse PMMA surface carboxyl modified microspheres with a particle size of 80.7 μm and a coefficient of variation of 4.3%.

[0068] Scanning electron microscope (SEM) image of the monodisperse PMMA surface carboxyl-modified microspheres prepared in Example 5 is shown below. Figure 1 As shown; by Figure 1 As can be seen, the modified microspheres have a smooth surface, uniform particle size (5.9 μm), and a coefficient of variation of 2.7%.

[0069] Fourier transform infrared (FTIR) spectra of the original monodisperse PMMA microspheres, monodisperse PMMA surface hydroxyl-modified microspheres, and monodisperse PMMA surface carboxyl-modified microspheres of Example 3 and Example 5 are as follows: Figure 2 As shown. In the original PMMA microspheres, 1720 cm⁻¹ - The point ¹ represents C=O stretching vibration, 2950 cm. -1 The medium-intensity peak at 1300-1100 cm⁻¹ is due to the stretching vibration of saturated CH (-CH₃, -CH₂-); - The strong peak in the ¹ region represents the COC stretching vibration of the ester group; the carboxyl-modified sample shows a broad peak of the OH stretching vibration of -COOH in this region, and the peak is at 1720 cm⁻¹. - The shift of the C=O peak at position ¹ to a lower wavenumber indicates successful carboxyl grafting. Hydroxyl-modified samples show peak values ​​in the 3200-3600 cm⁻¹ range. -1 A broad peak of the OH stretching vibration of -OH appears, along with a peak at 1000-1200 cm⁻¹. -1 The significantly enhanced peak intensity of CO stretching vibration in the interval verifies the successful introduction of hydroxyl groups; the modified sample still retains the characteristic peaks of PMMA, indicating that the modification process did not destroy the bulk structure of PMMA.

[0070] This invention grafts a modifier onto the surface of PMMA microspheres via transesterification, thereby controlling the functional groups on the microsphere surface. The modification process is simple, efficient, and operates under mild conditions, requiring no complex equipment. It significantly improves the hydrophilicity, compatibility, and thermal stability of PMMA microspheres. The modified PMMA microspheres obtained by this invention have hydroxyl, amino, or carboxyl groups grafted onto their surface, exhibit uniform particle size, and can be widely applied in coatings, adhesives, biomedical materials, composite materials, and other fields.

[0071] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing monodisperse polymethyl methacrylate surface-modified microspheres, characterized in that, It includes the following steps: 1) Monodisperse polymethyl methacrylate microspheres and organic solvents were ultrasonically dispersed to obtain a pretreated polymethyl methacrylate microsphere suspension; 2) The pretreated polymethyl methacrylate microsphere suspension, modifier and catalyst were reacted to obtain monodisperse polymethyl methacrylate surface modified microspheres; The modifier is a hydroxyl-containing compound, an amino-containing compound, or a compound containing both carboxyl and hydroxyl groups.

2. The preparation method according to claim 1, characterized in that, Step 1) The monodisperse polymethyl methacrylate microspheres have a particle size of 10 nm to 100 μm and a coefficient of variation of ≤10%; the organic solvent includes one or more of toluene, xylene and isopropanol.

3. The preparation method according to claim 1 or 2, characterized in that, Step 1) The mass ratio of the monodisperse polymethyl methacrylate microspheres to the organic solvent is 1~10:

100.

4. The preparation method according to claim 3, characterized in that, Step 2) The modifier comprises one or more of ethylene glycol, polyethylene glycol, polyethylene glycol monomethyl ether, ethanolamine, N-thioethylenediamine, N-thiodiaminopropane, glycerol, tetraethylenepentamine, glycolic acid, 3-hydroxypropionic acid, and lactic acid; the catalyst is one or more of sodium methoxide, sodium hydroxide, potassium hydroxide, sodium carbonate, and zinc acetate.

5. The preparation method according to claim 4, characterized in that, The mass ratio of the modifier in step 2) to the monodisperse polymethyl methacrylate microspheres in step 1) is 0.2~20:1; the mass of the catalyst is 0.5~5% of the mass of the monodisperse polymethyl methacrylate microspheres.

6. The preparation method according to claim 5, characterized in that, Step 2) The reaction temperature is 60~100℃ and the reaction time is 2~10h.

7. The preparation method according to claim 5 or 6, characterized in that, Step 2) The products after the reaction is completed are cooled and centrifuged in sequence to obtain solid products. The solid products are washed and dried in sequence to obtain monodisperse polymethyl methacrylate surface-modified microspheres.

8. The preparation method according to claim 7, characterized in that, The centrifugation speed is 2000~8000 r / min, and the centrifugation time is 3~15 min; the washing reagents are organic solvent and water, and the number of washings with organic solvent and water is 3~5 times independently; the drying temperature is 60~80℃, and the drying time is 4~6 h.

9. The monodisperse polymethyl methacrylate surface-modified microspheres prepared by the preparation method according to any one of claims 1 to 8, characterized in that, The surface of the monodisperse polymethyl methacrylate surface-modified microspheres is grafted with one or more of hydroxyl, amino, and carboxyl groups, and the particle size of the monodisperse polymethyl methacrylate surface-modified microspheres is 10 nm to 100 μm.

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