Multifunctional monodisperse homogeneous fluorescent microspheres, fluorescent microspheres with core-shell structure, preparation method and application

Abstract

The application relates to the field of new materials, and discloses a multifunctional monodisperse homogeneous fluorescent microsphere, a fluorescent microsphere with a core-shell structure and a preparation method. The average particle size of the monodisperse homogeneous fluorescent microsphere is 80-500 nm, the PDI is 0.008-0.182, and the fluorescent peak value is 415-625 nm. The fluorescent polymer microsphere with homogeneity and a core-shell structure is prepared by using the monodisperse homogeneous fluorescent microsphere, the brightness of the above microsphere is controllable, the microsphere is high in light emission efficiency, and the microsphere shows great application potential in the fields of biomedicine, electronic information, analysis and detection and the like.

Description

Technical Field

[0001] This invention relates to the field of new materials, specifically to a multifunctional monodisperse homogeneous fluorescent microsphere, a core-shell structured fluorescent microsphere, and a preparation method thereof. Background Technology

[0002] Since Vanderhoff and Bradford announced the successful preparation of polystyrene microspheres with uniform particle size in the 1950s, monodisperse microspheres have become a hot area of ​​research in polymer science due to their advantages such as uniform size, small volume, large specific surface area, and easy surface modification.

[0003] Monodisperse microspheres are generally prepared using two main strategies: physical methods and chemical methods. Physical methods have drawbacks such as a wide microsphere size distribution, poor controllability, and unsuitability for preparing hierarchical microspheres. Chemical methods refer to the preparation of microspheres through heterogeneous polymerization of monomers, including techniques such as suspension polymerization, emulsion polymerization, precipitation polymerization, and dispersion polymerization. Microspheres obtained through polymerization have advantages such as uniform particle size, good monodispersity, and designable structure. Furthermore, polymerization methods are relatively low-cost, easy to operate, and have potential industrial value. Based on monodisperse microspheres, researchers have designed and prepared microspheres with different structures and functions according to various practical needs. Currently, various functional microspheres such as magnetic microspheres, fluorescent microspheres, colored microspheres, and conductive microspheres have been developed. Among them, fluorescent microspheres, as microspheres with fluorescent substances loaded on their surface or internally, have excellent fluorescence properties and high fluorescence sensitivity, and are widely used in biomedicine, electronic information, and analytical detection fields. However, the fluorescent molecules used in current fluorescent microspheres exhibit aggregation-induced quenching (ACQ) phenomena, which limit the increase in the content of fluorescent molecules in the fluorescent microspheres, thus affecting the improvement of their luminescent performance. The concept of aggregation-induced emission (AIE) solves the ACQ problem commonly encountered by traditional fluorescent molecules. Using fluorescent molecules based on the AIE concept, the content of fluorescent molecules in microspheres can be increased, improving the optical properties of the microspheres and opening a new path for designing and fabricating monodisperse homogeneous fluorescent microspheres with high-efficiency luminescence and controllable performance.

[0004] Although there are many methods available for the preparation of fluorescent polymer microspheres, there are few literature reports on the preparation of monodisperse fluorescent polymer microspheres with controllable brightness and layered structure design. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention proposes a multifunctional monodisperse homogeneous fluorescent microsphere and its preparation method, and uses it to prepare homogeneous, core-shell fluorescent polymer microspheres. The brightness of these microspheres is controllable, and they emit light efficiently, demonstrating great application potential in the fields of biomedicine, electronic information, and analytical detection.

[0006] One objective of this invention is to provide a monodisperse homogeneous fluorescent microsphere, wherein the monodisperse homogeneous fluorescent microsphere has an average particle size of 80-500 nm, a PDI of 0.008-0.182, and a fluorescence peak of 415-625 nm.

[0007] The polydispersity index (PDI) is a dispersion factor used to describe the particle size distribution. The smaller the PDI, the more uniform the particle size.

[0008] According to the present invention, the selection range of parameters of the monodisperse homogeneous fluorescent microspheres is relatively wide. In a preferred embodiment of the present invention, the average particle size of the monodisperse homogeneous fluorescent microspheres is 120-480 nm, the PDI is 0.022-0.063, and the fluorescence peak value is 415-625 nm.

[0009] In a preferred embodiment of the present invention, the monodisperse homogeneous fluorescent microspheres have a polymer matrix and polymerizable units with AIE properties copolymerized on the polymer matrix.

[0010] According to the present invention, the range of polymer matrix selection is relatively wide. In a preferred embodiment of the present invention, the polymer matrix is ​​at least one selected from polystyrene, polybromostyrene, polychlorostyrene, polymethyl methacrylate, polydodecyl methacrylate, polyα-methylstyrene, polyacrylonitrile, polyacrylic acid, and polyethyl methacrylate.

[0011] In a preferred embodiment of the present invention, the polymerizable unit having AIE properties is copolymerized on the polymer matrix by olefin polymerization.

[0012] According to the present invention, the mass ratio of the polymerizable unit with AIE properties to the polymer matrix has a wide range. In a preferred embodiment of the present invention, the mass ratio of the polymerizable unit with AIE properties to the polymer matrix is ​​(0-20):100.

[0013] A second objective of this invention is to provide a method for preparing monodisperse homogeneous fluorescent microspheres according to one objective, comprising polymerizing a monomer, polymerizable AIE molecules, and optionally a crosslinking agent in a solvent in the presence of a dispersant and an initiator to obtain the monodisperse homogeneous fluorescent microspheres.

[0014] According to the present invention, the monomer can be selected from a wide range. In a preferred embodiment of the present invention, the monomer is selected from at least one of styrene, bromostyrene, chlorostyrene, methyl methacrylate, dodecyl methacrylate, α-methylstyrene, acrylonitrile, acrylic acid, and ethyl methacrylate.

[0015] According to the present invention, the solvent can be selected from a wide range. In a preferred embodiment of the present invention, the solvent is selected from water and at least one of the following solvents: acetonitrile, ethanol, n-butanol, and methanol.

[0016] According to the present invention, the solvent ratio can be selected from a wide range. In a preferred embodiment of the present invention, the total ratio of water to the following solvents (at least one of acetonitrile, ethanol, n-butanol or methanol) is 1:2-5.

[0017] According to the present invention, the dispersant has a wide range of selection. In a preferred embodiment of the present invention, the dispersant is selected from at least one of polyvinylpyrrolidone, hydroxypropyl cellulose, polyacrylic acid, polyethylene glycol, sodium styrene sulfonate, and methacryloyloxyethyltrimethylammonium chloride.

[0018] According to the present invention, the polymerizable AIE molecule has a wide range of selection and is a polymerizable unit with AIE properties, which endows the polymer microspheres with specific functions. In a preferred embodiment of the present invention, the polymerizable AIE molecule is an AIE molecule containing double bond modification; preferably, the polymerizable AIE molecule includes, but is not limited to, at least one selected from the following AIE molecules:

[0019]

[0020] According to the present invention, the selection range of the initiator is relatively wide. For example, the initiator is selected from initiators capable of initiating olefin polymerization. In a preferred embodiment of the present invention, azobisisobutyronitrile and / or benzoyl peroxide are preferred.

[0021] According to the present invention, the selection range of the crosslinking agent is relatively wide. In a preferred embodiment of the present invention, the crosslinking agent is selected from at least one of divinylbenzene, N,N-methylenebisacrylamide, ethylene glycol dimethacrylate and maleic rosin ethylene glycol acrylate.

[0022] According to the present invention, the range of selection for the amount of monomer and solvent is relatively wide. In a preferred embodiment of the present invention, the volume of monomer used is 5-15 parts, based on 100 parts of solvent volume.

[0023] According to the present invention, the selection range of the initiator is relatively wide. In a preferred embodiment of the present invention, the amount of the initiator is 0.1-10 parts by mass, based on 100 parts by mass of the monomer.

[0024] According to the present invention, the amount of the crosslinking agent can be selected from a wide range. In a preferred embodiment of the present invention, the amount of the crosslinking agent is 0-50 parts by mass, based on 100 parts by mass of the monomer.

[0025] According to the present invention, the range of selectable amounts of polymerizable AIE molecules is relatively wide. In a preferred embodiment of the present invention, the amount of polymerizable AIE molecules is 0-20 parts by mass, with the mass of the monomer being 100 parts.

[0026] According to the present invention, the range of the amount of the dispersant is relatively wide. In a preferred embodiment of the present invention, the amount of the dispersant is 0.25-10 parts by mass, based on 100 parts by mass of the monomer.

[0027] In a more preferred embodiment of the present invention, the volume of the monomer is 5-15 parts per 100 parts of the solvent; by mass, the amount of the initiator is 0.1-10 parts per 100 parts of the monomer, the amount of the crosslinking agent is 0-50 parts per 100 parts of the monomer, the amount of the polymerizable AIE molecule is 0-20 parts per 100 parts of the monomer, and the amount of the dispersant is 0.25-10 parts per 100 parts of the monomer.

[0028] According to the present invention, the selection range of the polymerization reaction conditions is relatively wide. In a preferred embodiment of the present invention, the polymerization reaction conditions include: a temperature of 55-110°C, and / or a rotation speed of 180-300 rpm, and / or a time of 20-480 min.

[0029] In a more preferred embodiment of the present invention, the method for preparing monodisperse homogeneous fluorescent microspheres includes:

[0030] A specific ratio of monomers, dispersants, initiators, crosslinking agents, polymerizable AIE molecules, and solvents is added to a reaction vessel equipped with a reflux condenser. The mixture is stirred and heated under a nitrogen atmosphere to carry out the polymerization reaction. After a certain reaction time, the reaction is stopped, and the microspheres are washed by centrifugation at 3000-8000 rpm and then dried to obtain pure polymer microspheres.

[0031] The monomer includes at least one of styrene, bromostyrene, chlorostyrene, methyl methacrylate, dodecyl methacrylate, α-methylstyrene, acrylonitrile, acrylic acid, and ethyl methacrylate, with the monomer content being 5-15% of the solvent volume; the initiator has no specific requirements and can be a traditional free radical polymerization initiator such as azobisisobutyronitrile, benzoyl peroxide, etc., with the amount of initiator being 0.1-10% of the monomer mass;

[0032] The crosslinking agent may be selected from at least one of divinylbenzene, N,N-methylenebisacrylamide, ethylene glycol dimethacrylate, and maleic rosin ethylene glycol acrylate, and the amount of crosslinking agent used is 0-50% of the monomer mass;

[0033] The AIE molecule is applicable to all polymerizable AIE molecules; the mass content is 0-20% of the monomer;

[0034] The dispersant may be selected from at least one of polyvinylpyrrolidone, hydroxypropyl cellulose, polyacrylic acid, polyethylene glycol, sodium styrene sulfonate, methacryloyloxyethyltrimethylammonium chloride, etc., and the mass content is 0.25-10% of the monomer content;

[0035] The solvent is selected from water and at least one of the following solvents: acetonitrile, ethanol, n-butanol, and methanol;

[0036] The polymerization temperature range is 55-110℃, and the stirring speed is 180-300 rpm.

[0037] A third objective of this invention is to provide a method for preparing fluorescent microspheres with a core-shell structure, comprising: preparing a seed dispersion and preparing the fluorescent microspheres with the core-shell structure.

[0038] Nanoparticles are dispersed in a solvent to obtain a seed dispersion; the seed dispersion is added to a polymerization system, and a polymerization reaction is carried out under the conditions of the preparation method described in Objective 2 to obtain the core-shell structured fluorescent microspheres; the polymerization system is the polymerization liquid before the start of dispersion polymerization in the preparation method described in Objective 2, which may or may not contain the polymerizable AIE molecules.

[0039] According to the present invention, a method for preparing fluorescent microspheres with a core-shell structure includes the preparation of a seed dispersion and the preparation of fluorescent microspheres with a core-shell structure: the seed dispersion is obtained by nano-coprecipitation, polymerization, or other methods; a polymerization system is obtained by mixing monomers, optional polymerizable AIE molecules, and optional crosslinking agents in a solvent in the presence of a dispersant and an initiator; the seed dispersion is added to the polymerization system, and a polymerization reaction is carried out according to the polymerization reaction conditions described above (Objective 2) to obtain fluorescent microspheres with a core-shell structure.

[0040] The specific polymerization reaction ratios and reaction conditions, as well as the preparation method of the core-shell structured fluorescent microspheres, are the same as those described in the previous section (Objective Two) on the preparation method of monodisperse homogeneous fluorescent microspheres.

[0041] According to the present invention, the volume ratio of the seed dispersion to the polymerization system can be selected within a wide range. In a preferred embodiment of the present invention, the volume ratio of the seed dispersion to the polymerization system is (0.005-0.25):1.

[0042] According to the present invention, the range of selection of nanoparticle seeds is relatively wide. In a preferred embodiment of the present invention, the nanoparticle seeds are selected from at least one of particles obtained by polymerization method and AIE particles obtained by nano-coprecipitation method, preferably AIE particles obtained by coprecipitation method; the polymerization method is preferably dispersion polymerization or emulsion polymerization.

[0043] The seed dispersion of the coprecipitated AIE particles is prepared by the following method: the second AIE molecule and the polymer matrix are dissolved in a good solvent, ultrasonically mixed, and then dropped into water to obtain the seed dispersion; preferably, the amount of polymer matrix is ​​0.1-5 mg / mL relative to the total volume of the good solvent and water; the amount of the second AIE molecule is 0-20 parts based on 100 parts by mass of the polymer matrix; the second AIE molecule is selected from at least one of all molecules with AIE function.

[0044] According to the present invention, the range of polymer matrix selection is relatively wide when preparing seed dispersion. In a preferred embodiment of the present invention, the polymer matrix is ​​selected from at least one of amphiphilic block PEG, polystyrene maleic anhydride polymer, polyvinyl acetate maleic anhydride polymer, polyN-vinylpyrrolidone maleic anhydride polymer, polyvinyl alcohol, chitosan, polypeptide, etc.

[0045] According to the present invention, the range of good solvents is relatively wide. In a preferred embodiment of the present invention, the good solvent is selected from at least one of acetone, acetonitrile, dimethyl sulfoxide, tetrahydrofuran, and N,N-dimethylformamide.

[0046] In a more preferred embodiment of the present invention, the method for preparing core-shell structured microspheres is as follows:

[0047] A certain proportion of AIE molecules and polymer matrix were dissolved in 1 mL of a good solvent. After being sonicated to mix evenly, the good solvent was added dropwise to 9 mL of deionized water under the sonication of a cell disruptor to obtain a seed dispersion. Subsequently, core-shell structured microspheres were obtained through polymerization.

[0048] The good solvent may be selected from at least one of acetone, acetonitrile, dimethyl sulfoxide, tetrahydrofuran, and N,N-dimethylformamide.

[0049] The AIE molecule described applies to all AIE molecules, regardless of whether they contain polymerizable double bonds.

[0050] The polymer matrix may be selected from at least one of the following: amphiphilic block PEG, polystyrene maleic anhydride polymer, polyvinyl acetate maleic anhydride polymer, polyN-vinylpyrrolidone maleic anhydride polymer, polyvinyl alcohol, chitosan, polypeptide, etc.

[0051] The preferred ratios and conditions for the polymerization implementation scheme are the same as those described in the "Implementation Method for Preparation of Monodisperse Homogeneous Microspheres" above.

[0052] The fourth objective of this invention is to provide a fluorescent microsphere with a core-shell structure, which is prepared according to the preparation method of the fluorescent microsphere with a core-shell structure described in the third objective.

[0053] The fifth objective of this invention is to provide applications of the monodisperse homogeneous fluorescent microspheres described in the first objective, or the core-shell structure fluorescent microspheres described in the fourth objective, in the fields of biomedicine, electronic information, and analytical detection.

[0054] Compared with the prior art, the present invention has the following advantages:

[0055] (1) The obtained microspheres have the advantages of uniform and controllable size, designable structure, and controllable brightness;

[0056] (2) Different fluorescent functional microspheres can be obtained by changing the fluorescent molecules used;

[0057] (3) The seed dispersion polymerization method used can combine any fluorescent molecule, regardless of whether it has polymerizable double bonds, with nanoparticles to obtain a seed dispersion, and then use polymerization as a seed to prepare core-shell structured microspheres, which has universality.

[0058] (4) The present invention can obtain monodisperse homogeneous fluorescent microspheres with uniform size; it can also obtain microspheres with adjustable fluorescence color and core / shell structure (layered structure).

[0059] (5) The brightness of the above microspheres is controllable and they emit light efficiently, demonstrating great application potential in fields such as biomedicine, electronic information, and analytical testing. Attached Figure Description

[0060] Figure 1 Scanning electron microscope images of homogeneous fluorescent microspheres of different sizes.

[0061] Figure 2 Fluorescence spectra of fluorescent microspheres with different AIE molecule contents.

[0062] Figure 3 Scanning electron microscope images of fluorescent microspheres with different dispersant contents.

[0063] Figure 4 Transmission electron microscopy images of fluorescent microspheres with different shell thicknesses and core / shell structures.

[0064] Figure 5a Fluorescence spectrum and CIE (Commission Internationale de L'Eclairage) chromaticity diagram of the core / shell structured luminescent microspheres in Example 8.

[0065] Figure 5b Fluorescence spectrum and CIE chromaticity diagram of the core / shell structured luminescent microspheres in Example 9.

[0066] Figure 5c Fluorescence spectrum and CIE chromaticity diagram of the core / shell structured luminescent microspheres in Example 10.

[0067] Figure 5d Fluorescence spectrum and CIE chromaticity diagram of the core / shell structured luminescent microspheres in Example 11.

[0068] Figure 5e Fluorescence spectrum and CIE chromaticity diagram of the core / shell structured luminescent microspheres in Example 12. Detailed Implementation

[0069] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0070] The raw materials used in the specific examples of this invention are all commercially available.

[0071] In this invention, the average particle size and PDI of the fluorescent microspheres are detected by dynamic light scattering (DLS), and the fluorescence peak and fluorescence intensity are measured by fluorescence spectrometer.

[0072] Example 1

[0073] Preparation of monodisperse homogeneous fluorescent microspheres by dispersion polymerization:

[0074] Four polymerization reaction solutions with identical compositions were prepared: 2.5 mg TPE-CN-1VBC, 2.5 mL styrene monomer, 11.3 mg azobisisobutyronitrile (azobisisobutyronitrile) initiator, 22.6 mg sodium styrene sulfonate (dispersant), 37.5 mL methanol, and 12.5 mL water were added to a three-necked flask equipped with a reflux condenser. Nitrogen gas was purged for 10 min, and the reaction was initiated by stirring and heating at 250 rpm. The temperature was maintained at 65 °C for 30 min, 60 min, 120 min, and 240 min, respectively. The resulting samples were centrifuged, washed, and dried to obtain pure polymer microspheres.

[0075] Scanning electron microscopy (SEM) and deep particle size distribution (DLS) analyses were performed on homogeneous fluorescent microspheres of different sizes obtained by different preparation methods. See [link to DLS analysis]. Figure 1 ad in Figure 1In the figures, a and b represent the homogeneous fluorescent microspheres obtained in Example 1, corresponding to reaction times of a) 30 min, b) 60 min, c) 120 min, and d) 240 min, respectively. Figure 1 It can be seen that the microspheres with a reaction time of 30 min have a particle size of 124 nm and a PDI of 0.041; the microspheres with a reaction time of 60 min have a particle size of 211 nm and a PDI of 0.063; the microspheres with a reaction time of 120 min have a particle size of 343 nm and a PDI of 0.022; and the microspheres with a reaction time of 240 min have a particle size of 453 nm and a PDI of 0.054.

[0076] The polydispersity index (PDI) is a dispersion factor used to describe the particle size distribution. The smaller the PDI, the more uniform the particle size.

[0077] As can be seen from this embodiment, the present invention can obtain monodisperse homogeneous fluorescent microspheres with a particle size range of 100-460 nm.

[0078] Example 2

[0079] The preparation process is basically the same as in Example 1 (reaction time is 240 min), except that the amount of AIE molecules added is 5 mg.

[0080] Example 3

[0081] The preparation process is basically the same as in Example 2, except that the amount of AIE molecules added is 10 mg.

[0082] Example 4

[0083] Preparation of monodisperse homogeneous fluorescent microspheres by dispersion polymerization:

[0084] 3 mg of TPE-BJT-VBC, 2.5 mL of styrene monomer, 11.3 mg of azobisisobutyronitrile (azobisisobutyronitrile) initiator, 22.6 mg of sodium styrene sulfonate (dispersant), 37.5 mL of methanol, and 12.5 mL of water were added to a three-necked flask equipped with a reflux condenser. Nitrogen gas was purged for 10 min, and the mixture was stirred and heated at 250 rpm to initiate the reaction. The temperature was maintained at 65 °C for 4 h. After the reaction was completed, the mixture was centrifuged, washed, and dried to obtain pure polymer microspheres.

[0085] Fluorescence emission spectroscopy analysis was performed on fluorescent microspheres prepared with different AIE molecule contents. Figure 2 . Figure 2 a corresponds to Examples 1, 2, and 3. Figure 2 b corresponds to embodiments 1 and 4. From Figure 2As can be seen from the examples, the higher the AIE molecule content, the higher the fluorescence intensity of the prepared microspheres. Increasing the AIE molecule content in the polymerization system can prepare polymer microspheres with high luminescence efficiency. Different AIE molecules can impart different luminescence to the microspheres. Specific results are shown in Table 1.

[0086] Example 5

[0087] Monodisperse homogeneous fluorescent microspheres were prepared according to the method in Example 4, except that the content of sodium styrene sulfonate was 452 mg.

[0088] Scanning electron microscopy and DLS analyses were performed on fluorescent microspheres prepared with different dispersant contents. The results are shown in the figure. Figure 3 , Figure 3 (a) corresponds to Example 4, and (b) corresponds to Example 5. Figure 3 As can be seen, with the increase of the dispersant sodium styrene sulfonate content, the microspheres no longer exhibit a regular spherical shape, and the PDI of the microspheres increases significantly, from the original 0.051 to 0.182. This indicates that the increase in dispersant content leads to changes in the morphology of the microspheres and a decrease in monodispersity. Within the preferred range of this invention, the monodispersity is relatively good. Specific results are shown in Table 1.

[0089] The microspheres obtained above were analyzed and characterized according to the analytical method used for the product in Example 1, and the results are shown in Table 1.

[0090] Table 1

[0091]

[0092]

[0093] The smaller the PDI, the more uniform the microspheres and the better their monodispersity. As shown in Table 1, this invention can produce microspheres with uniformity and good monodispersity.

[0094] Example 6

[0095] Monodisperse core / shell fluorescent microspheres (fluorescent molecules without polymerizable groups) were prepared by dispersion polymerization using seeds obtained by coprecipitation method:

[0096] 2.04 mg of AIE fluorescent molecules without double bonds (TPE-4OMe) and 10.03 mg of amphiphilic block PEG were dissolved in 2 mL of tetrahydrofuran, a good solvent. The tetrahydrofuran solution was then added dropwise to 18 mL of water to prepare a seed dispersion.

[0097] (1,1,2,2-Tetra(4-methoxyphenyl)ethylene, TPE-4OMe)

[0098] Four polymerization reaction solutions with identical compositions were prepared: 1.25 mL of styrene monomer, 11.3 mg of azobisisobutyronitrile (AIB) initiator, 22.6 mg of sodium styrene sulfonate dispersant, 15 mL of methanol, and 5 mL of seed dispersion were added to a three-necked flask equipped with a reflux condenser. Nitrogen gas was purged for 10 min, and the reaction was initiated by stirring and heating at 180 rpm. The temperature was maintained at 65 °C for reactions a) 30 min, b) 40 min, c) 50 min, and d) 120 min, respectively. After the reaction was completed, the mixture was centrifuged, washed, and dried to obtain pure polymer microspheres. Under ultraviolet light excitation, the microspheres exhibited a distinct blue emission.

[0099] The core / shell structure can be directly observed using transmission electron microscopy (TEM). It exhibits a layered structure, and the difference in electron density between the core and shell creates a certain contrast in the microsphere structure. See the appendix for details. Figure 4 . Figure 4 These are the core / shell fluorescent polymer microspheres from Example 10 with seed polymerization times of a) 30 min, b) 40 min, c) 50 min, and d) 120 min. Figure 4 It can be seen that as the reaction time increases, the shell thickness of the microspheres gradually increases. By controlling the polymerization time, core / shell microspheres with a shell thickness of 20-100 nm can be prepared.

[0100] Example 7

[0101] Monodisperse core / shell fluorescent microspheres (fluorescent molecules with polymerizable groups) were prepared by dispersion polymerization using seeds obtained by coprecipitation method:

[0102] A seed dispersion was prepared by dissolving 1.01 mg TPE-CN-VBC and 5.12 mg amphiphilic block PEG in 1 mL of a good solvent, dimethyl sulfoxide, and then adding the dimethyl sulfoxide solution dropwise into 9 mL of water.

[0103] 1.25 mL of styrene monomer, 11.3 mg of azobisisobutyronitrile (azobisisobutyronitrile) initiator, 22.6 mg of sodium styrene sulfonate dispersant, 15 mL of methanol, and 5 mL of seed dispersion were added to a three-necked flask equipped with a reflux condenser. Nitrogen gas was purged for 10 min, and the mixture was stirred and heated at 180 rpm to initiate the reaction. The reaction was maintained at 65 °C for 4 h. After the reaction was complete, the mixture was centrifuged, washed, and dried to obtain pure polymer microspheres. Under ultraviolet light excitation, the microspheres exhibited a distinct orange emission.

[0104] Example 8

[0105] 1.01 mg TPE-4VBC and 5.08 mg polystyrene maleic anhydride polymer were dissolved in 1 mL of tetrahydrofuran, a good solvent, and the tetrahydrofuran was added dropwise to 9 mL of water to prepare a seed dispersion.

[0106] 0.52 mg TPE-CN-VBC, 1.25 mL styrene monomer, 11.31 mg azobisisobutyronitrile (azobisisobutyronitrile) initiator, 22.68 mg sodium styrene sulfonate (dispersant), 15 mL methanol, and 5 mL seed dispersion were added to a three-necked flask equipped with a reflux condenser. Nitrogen gas was purged for 10 min, and the mixture was stirred and heated at 180 rpm to initiate the reaction. The temperature was maintained at 65 °C for 4 h. After the reaction was complete, the mixture was centrifuged, washed, and dried to obtain pure polymer microspheres.

[0107] Example 9

[0108] A seed dispersion was prepared by dissolving 1.03 mg TPE-4VBC and 5.12 mg polystyrene maleic anhydride polymer in 1 mL of a good solvent, tetrahydrofuran, and then adding tetrahydrofuran dropwise into 9 mL of water.

[0109] 1.25 mL of styrene monomer, 11.34 mg of azobisisobutyronitrile (AIB) initiator, 22.61 mg of sodium styrene sulfonate (NSS) dispersant, 15 mL of methanol, and 5 mL of seed dispersion were added to a three-necked flask equipped with a reflux condenser. Nitrogen gas was purged for 10 min, and the mixture was stirred and heated at 180 rpm to initiate the reaction. The temperature was maintained at 65 °C for 4 h. After the reaction was complete, the mixture was centrifuged, washed, and dried to obtain pure polymer microspheres.

[0110] Example 10

[0111] 5.03 mg of polystyrene maleic anhydride polymer was dissolved in 1 mL of a good solvent, tetrahydrofuran, and the tetrahydrofuran was added dropwise to 9 mL of water to prepare a seed dispersion.

[0112] 0.49 mg TPE-CN-VBC, 1.25 mL styrene monomer, 11.28 mg azobisisobutyronitrile (azobisisobutyronitrile) initiator, 22.66 mg sodium styrene sulfonate (dispersant), 15 mL methanol, and 5 mL seed dispersion were added to a three-necked flask equipped with a reflux condenser. Nitrogen gas was purged for 10 min, and the mixture was stirred and heated at 180 rpm to initiate the reaction. The temperature was maintained at 65 °C for 4 h. After the reaction was complete, the mixture was centrifuged, washed, and dried to obtain pure polymer microspheres.

[0113] Example 11

[0114] 0.99 mg TPE-4VBC and 5.08 mg polystyrene maleic anhydride polymer were dissolved in 1 mL of tetrahydrofuran, a good solvent, and the tetrahydrofuran was added dropwise to 9 mL of water to prepare a seed dispersion.

[0115] 0.20 mg TPE-CN-VBC, 1.25 mL styrene monomer, 11.30 mg azobisisobutyronitrile (AIBN) initiator, 22.64 mg sodium styrene sulfonate (NSSSU) dispersant, 15 mL methanol, and 5 mL seed dispersion were added to a three-necked flask equipped with a reflux condenser. Nitrogen gas was purged for 10 min, and the mixture was stirred and heated at 180 rpm to initiate the reaction. The temperature was maintained at 65 °C for 4 h. After the reaction was complete, the mixture was centrifuged, washed, and dried to obtain pure polymer microspheres.

[0116] Example 12

[0117] 1.00 mg TPE-4VBC and 5.11 mg polystyrene maleic anhydride polymer were dissolved in 1 mL of tetrahydrofuran, a good solvent, and the tetrahydrofuran was added dropwise to 9 mL of water to prepare a seed dispersion.

[0118] 0.31 mg TPE-CN-VBC, 1.25 mL styrene monomer, 11.33 mg azobisisobutyronitrile (azobisisobutyronitrile) initiator, 22.61 mg sodium styrene sulfonate (dispersant), 15 mL methanol, and 5 mL seed dispersion were added to a three-necked flask equipped with a reflux condenser. Nitrogen gas was purged for 10 min, and the mixture was stirred and heated at 180 rpm to initiate the reaction. The temperature was maintained at 65 °C for 4 h. After the reaction was complete, the mixture was centrifuged, washed, and dried to obtain pure polymer microspheres.

[0119] Table 2

[0120]

[0121] Fluorescence and CIE spectra of the core / shell structures of the luminescent microspheres in Examples 8-12 were analyzed, and the results are shown in the figure. Figures 5a-5e ; Corresponding to embodiments 8-12, by Figure 5a As can be seen, the microspheres prepared by adding 1.01 mg TPE-4VBC and 0.52 mg TPE-CN-VBC to the core and shell layers respectively in Example 8 have CIE coordinates of 0.46 and 0.41, and the corresponding fluorescence color is orange-yellow. Figure 5b As can be seen, in Example 9, 1.01 mg of TPE-4VBC was added to the core layer, and the resulting microspheres had CIE coordinates of 0.17, 0.24 and a corresponding fluorescence color of blue. Figure 5c As can be seen, the microspheres prepared by adding 0.49 mg of TPE-CN-VBC to the shell layer in Example 10 have CIE coordinates of 0.58, 0.42 and a corresponding fluorescence color of orange-red. Figure 5d As can be seen, the microspheres prepared by adding 0.99 mg TPE-4VBC and 0.20 mg TPE-CN-VBC to the core and shell layers respectively in Example 11 have CIE coordinates of 0.27 and 0.32, and the corresponding fluorescence color is cyan. Figure 5eAs can be seen from Example 12, the microspheres prepared by adding 1.00 mg TPE-4VBC to the core and 0.31 mg TPE-CN-VBC to the shell have CIE coordinates of 0.40, 0.35, and the corresponding fluorescence color is white. With the addition of core / shell fluorescent molecules, the fluorescence of the microspheres can transition from blue to orange light. By controlling the type and content of fluorescent molecules, different luminescent microspheres can be prepared.

[0122] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

[0123] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0124] When this specification uses the prefixes “known to those skilled in the art,” “prior art,” or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those commonly used in the art at the time of this application, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0125] The endpoints and any values ​​of the ranges disclosed in this application are not limited to the precise ranges or values; such ranges or values ​​should be understood to include values ​​close to them. 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 considered as specifically disclosed herein. In principle, various technical solutions can be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0126] In the context of this specification, except where expressly stated otherwise, any matters or issues not mentioned shall apply directly to those known in the art without any modification.

[0127] Furthermore, any implementation described herein can be freely combined with one or more other implementations described herein, and the resulting technical solutions or technical ideas shall be regarded as part of the original disclosure or original record of the present invention, and should not be regarded as new content not disclosed or anticipated herein, unless those skilled in the art believe that the combination is obviously unreasonable.

Claims

1. A method for preparing monodisperse homogeneous fluorescent microspheres, comprising polymerizing monomers and polymerizable AIE molecules in a solvent in the presence of a dispersant and an initiator to obtain the monodisperse homogeneous fluorescent microspheres; the polymerizable AIE molecules are AIE molecules modified with double bonds; the amount of the polymerizable AIE molecules is 0-20 parts by mass based on 100 parts by mass of the monomers. The monodisperse homogeneous fluorescent microspheres have an average particle size of 80-500 nm, a PDI of 0.008-0.063, and a fluorescence peak value of 415-625 nm. The monomers are at least one of styrene, bromostyrene, chlorostyrene, methyl methacrylate, dodecyl methacrylate, alpha-methylstyrene, acrylonitrile, acrylic acid, and ethyl methacrylate. The solvent is selected from water and at least one of acetonitrile, ethanol, n-butanol, and methanol. The dispersant is sodium styrene sulfonate. The amount of the dispersant is 0.25-10 parts by mass based on 100 parts by mass of the monomers. The ratio of the total amount of water to at least one of acetonitrile, ethanol, n-butanol, and methanol is 1:2-5. 2.The method according to claim 1, wherein the initiator is an initiator capable of initiating olefin polymerization. 3.The method according to claim 1, wherein the polymerizable AIE molecules are at least one of the following AIE molecules: 4.The method according to claim 1, wherein the initiator is azobisisobutyronitrile and / or dibenzoyl peroxide. 5.The method according to claim 1, wherein the volume amount of the monomers is 5-15 parts based on 100 parts by volume of the solvent. 。 6.The method according to claim 1, wherein the amount of the initiator is 0.1-10 parts by mass based on 100 parts by mass of the monomers. 7.The method according to claim 1, wherein the polymerizable AIE molecules are at least one of the following AIE molecules: 8.The method according to claim 1, wherein the monodisperse homogeneous fluorescent microspheres have an average particle size of 120-480 nm, a PDI of 0.022-0.063, and a fluorescence peak value of 415-625 nm. 9.The method according to claim 3, wherein the monodisperse homogeneous fluorescent microspheres have a polymer matrix and polymerizable units having AIE properties copolymerized on the polymer matrix. 10.The method according to claim 9, wherein the polymer matrix is at least one of polystyrene, polybromostyrene, polychlorostyrene, polymethyl methacrylate, polydodecyl methacrylate, poly-alpha-methylstyrene, polyacrylonitrile, polyacrylic acid, and polyethyl methacrylate. 11.The method according to claim 9, wherein the polymerizable units having AIE properties are copolymerized on the polymer matrix by olefin polymerization. ​ The conditions of the polymerization reaction are: temperature 55-110 o C, rotation speed 180-300 rpm; time 20-480 min. ​ ​ ​ ​ ​ ​ ​ ​ 12. The method of claim 9, wherein a mass ratio of the polymerizable unit having AIE properties to the polymer matrix is (0-20):

100. ​

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