A kind of bowl-shaped crosslinked polystyrene particles and its preparation method

Abstract

The present invention provides a method for preparing bowl-shaped cross-linked polystyrene particles, comprising the following steps: a) dispersing polystyrene seed microspheres in an aqueous emulsifier solution to obtain a seed microsphere emulsion; b) swelling the seed microspheres in the emulsion obtained in step a), then purging the system with nitrogen, sealing it, and then placing it 60 in a Coγ-ray radiation field for irradiation to obtain a reaction mixture; c) separating the solid product in the reaction mixture obtained in step b), and then successively washing and drying to obtain bowl-shaped cross-linked polystyrene particles. In the present invention, non-cross-linked polystyrene microspheres are used as seeds. After swelling the seed microspheres with an appropriate cross-linking monomer / swelling agent system, 60 Coγ-ray is used to initiate the polymerization of the swollen monomer at room temperature to obtain bowl-shaped cross-linked PS particles; this preparation method has the advantages of simple process, mild reaction conditions, environmental friendliness, etc., is more conducive to regulating the polymer and solvent phase separation process, and better ensures the monodispersity of the bowl-shaped particle size.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer material synthesis, and more particularly to a bowl-shaped crosslinked polystyrene particle and a preparation method thereof. Background Art

[0002] As early as in 2001, Okubo M et al. reported using polystyrene (PS) microspheres with a particle size of about 1.71 μm as seeds, selecting divinylbenzene (DVB) and vinylbiphenyl as swelling monomers, and xylene as a swelling agent for swelling and polymerization. Finally, xylene was removed by evaporation to obtain PS particles in the shape of a bowl with a particle size of about 3.5 μm, thus initiating the research on the preparation and properties of bowl-shaped polymer particles [Okubo M, Minami H, Morikawa K. Colloid and Polymer Science, 2001, 279: 931 - 935.]. The unique anisotropic morphology of bowl-shaped particles makes them have many potential applications in the fields of preparing optical materials, specific recognition and separation materials, etc. [Yang Y, Kim J B, Nam S K, et al. Nature Communications, 2023, 14(1): 793; Song Y Y, Zhou J J, Fan J B, et al. Advanced Functional Materials, 2018, 28(32): 1802493; Fan J B, Song Y Y, Liu H, et al. Science Advances, 2017, 3(6): e1603203]. The formation mechanism of bowl-shaped polymer particles is based on the phase separation principle between non-crosslinked PS microspheres and swelling agents, and currently, it is mainly achieved through two methods, namely the thermally induced phase separation (TIPS) method and the polymerization-induced phase separation (PIPS) method. The TIPS method is to first disperse PS microspheres in an alcohol-water system with a certain ratio, and then uniformly mix them with a poor solvent for PS microspheres (such as decane, silicone oil, etc.) under appropriate conditions (such as high temperature or adding a co-solvent), and finally induce phase separation of the polymer and the swelling agent by cooling or evaporating the co-solvent [Yang Y, Kim J B, Nam S K, et al. Nature Communications, 2023, 14(1): 793; Kim S H, Hollingsworth A D, Sacanna S, et al. Journal of the American Chemical Society, 2012, 134(39): 16115 - 16118.]. For example, Okubo M et al. heated the PS microsphere and decane mixed system to above 55 °C to enable decane to swell PS microspheres better. Subsequently, during the process of programmed cooling, thermodynamic phase separation occurred between decane and linear PS chains, resulting in bowl-shaped PS particles with a particle size of 2.54 μm [Tanaka T, Komatsu Y, Fujibayashi T, et al. Langmuir, 2010, 26(6): 3848 - 3853.].Obviously, the TIPS method yields non-crosslinked bowl-shaped PS particles. Generally, non-crosslinked polymers have poor thermal and chemical stabilities, which impose many limitations in practical applications. The PITS method is used to prepare bowl-shaped crosslinked PS particles. It uses a specific swelling system containing crosslinking monomers to swell non-crosslinked PS seed microspheres, and then initiates the polymerization of the crosslinking monomers. The phase separation of the polymer and the swelling agent is induced by the tension of the newly formed polymer crosslinking network, resulting in bowl-shaped polymer particles. Compared with the TIPS method, the PITS method can obtain crosslinked polymer bowl-shaped particles with more components, morphologies, functions, better mechanical properties, and superior thermal and chemical stabilities due to the wide range of compositions of the crosslinking monomer swelling systems that can be used. For example, Xie D et al. used an ethanol aqueous solution as the continuous phase, polyvinylpyrrolidone (PVP) as the dispersant, and styrene (St) as the polymerization monomer to conduct dispersion polymerization to obtain PS seed microspheres. Then, a swelling system composed of St, DVB, and ethanol was added dropwise to this polymerization system at a certain rate to simultaneously carry out the swelling of the seed microspheres and the polymerization of the monomers, successfully preparing monodisperse bowl-shaped crosslinked PS particles with a particle size of 1 - 3 μm [Xie D, Ren X, Xie Y, et al. ACS Macro Letters, 2016, 5(2): 174 - 176.]. Huang Y et al. used St / methyl methacrylate (MMA) / acrylic acid (AA) as the polymerization monomers, sodium dodecylbenzenesulfonate as the emulsifier, and ammonium persulfate (APS) as the initiator to conduct emulsion polymerization (polymerization temperature was 70 °C), and pre-synthesized PS seed microspheres with a particle size of 100 nm. Then, the temperature was raised to 80 °C, and the crosslinking monomer DVB was added dropwise to the polymerization system at a certain rate to obtain crosslinked PS particles with single or multiple depressions on the surface. The particle size of these particles was approximately 400 nm, and they had superhydrophilic properties [Huang Y, Wang J X, Zhou J M, et al. Macromolecules, 2011, 44(8): 2404 - 2409].

[0003] Although the PITS method has a greater adjustment space in controlling the chemical composition and morphology of bowl-shaped particles compared with the TIPS method, there are many factors affecting the phase separation process of the polymer and the swelling agent in this method, such as the dropping rate of the crosslinking monomer, the composition of the continuous phase, and the polymerization temperature. Therefore, it is also difficult to precisely control the morphology of bowl-shaped crosslinked PS particles. On the other hand, usually, chemical polymerization initiation needs to be carried out at a relatively high temperature (decomposition of the initiator). At high temperatures, the reaction is fast, and the stability of the multiphase system is poor, further increasing the difficulty of controlling the morphology of bowl-shaped particles. Summary of the Invention

[0004] In view of this, the object of the present invention is to provide a kind of bowl-shaped cross-linked polystyrene particles and its preparation method. The preparation method provided by the present invention has the advantages of mild reaction conditions, green environmental protection, etc., is more conducive to regulating the polymer and solvent phase separation process, and better ensures the monodispersity of the bowl-shaped particle size.

[0005] The present invention provides a preparation method of bowl-shaped cross-linked polystyrene particles, comprising the following steps:

[0006] a) Dispersing polystyrene seed microspheres in an aqueous solution of an emulsifier to obtain a seed microsphere emulsion;

[0007] b) After swelling the seed microspheres in the emulsion obtained in step a), the system is purged with nitrogen, sealed, and then placed in 60 a Coγ-ray radiation field for irradiation to obtain a reaction mixture;

[0008] c) After separating the solid product in the reaction mixture obtained in step b), washing and drying are carried out in sequence to obtain bowl-shaped cross-linked polystyrene particles.

[0009] Preferably, the polystyrene seed microspheres in step a) are non-cross-linked PS microspheres with a particle size of 100 nm to 10 μm.

[0010] Preferably, the emulsifier in step a) is an anionic emulsifier; the mass ratio of the emulsifier to the polystyrene seed microspheres is 1:(5 - 20).

[0011] Preferably, the dispersing method in step a) is ultrasonic dispersion for 2 min to 10 min.

[0012] Preferably, the swelling process in step b) is specifically as follows:

[0013] Using sodium dodecyl sulfate as an emulsifier, dibutyl phthalate is emulsified to prepare swelling solution I, and then swelling solution I is added dropwise to the seed microsphere emulsion, and stirred for 3 h to 5 h to obtain a first swelling system; then using sodium dodecyl sulfate as an emulsifier, styrene and divinylbenzene are emulsified to prepare swelling solution II, and finally swelling solution II is added to the first swelling system, and stirring is continued for 10 h to 14 h to complete the swelling process;

[0014] Or,

[0015] Using sodium dodecyl sulfate as an emulsifier, styrene and divinylbenzene are emulsified to prepare swelling solution II, and then swelling solution II is added to the seed microsphere emulsion, and stirring is continued for 10 h to 14 h to complete the swelling process.

[0016] Preferably, the concentration of the aqueous solution of sodium dodecyl sulfate used in the swelling solution I is 6×10 -3 ~2.4×10- 2 mol / L.

[0017] Preferably, the concentration of the sodium dodecyl sulfate aqueous solution used in the swelling solution II is 6×10 -3 ~2.4×10 -2 mol / L, where the monomer content is 1 wt% to 10 wt%, and the mass ratio of styrene to divinylbenzene is (0.5~4):1.

[0018] Preferably, the dose rate of the irradiation in step b) is 4 Gy / min to 78 Gy / min, and the total absorbed dose is 6 kGy to 70 kGy.

[0019] Preferably, the separation method in step c) is centrifugal separation; the cleaning method is ethanol cleaning; the drying method is heating and drying, and the temperature is 50°C to 70°C.

[0020] The present invention also provides a bowl-shaped crosslinked polystyrene particle prepared by using the preparation method described in the above technical solution.

[0021] The present invention provides a bowl-shaped crosslinked polystyrene particle and a preparation method thereof; the preparation method includes the following steps: a) dispersing polystyrene seed microspheres in an aqueous solution of an emulsifier to obtain a seed microsphere emulsion; b) swelling the seed microspheres in the emulsion obtained in step a), then purging the system with nitrogen, sealing, and then placing it in 60 a Coγ-ray radiation field for irradiation to obtain a reaction mixture; c) separating the solid product in the reaction mixture obtained in step b), and then successively cleaning and drying to obtain bowl-shaped crosslinked polystyrene particles. Compared with the prior art, the present invention uses non-crosslinked polystyrene microspheres as seeds, swells them in a proper crosslinking monomer / swelling agent system at room temperature, and then uses 60 Coγ-rays to initiate the polymerization of the swollen monomers at room temperature to prepare bowl-shaped crosslinked polystyrene particles with regular morphology; using the preparation method provided by the present invention to prepare bowl-shaped crosslinked PS particles has the advantages of simple preparation method, mild reaction conditions, environmental friendliness, etc., is more conducive to regulating the polymer and solvent phase separation process, and better ensures the monodispersity of the bowl-shaped particle size; at the same time, the prepared bowl-shaped crosslinked polystyrene particles have potential applications in the fields of preparing optical materials, specific recognition and separation materials, etc. Description of the Drawings

[0022] Figure 1 is the SEM picture of the PS seed microspheres prepared in the embodiment of the present invention;

[0023] Figure 2 is the infrared spectrum of the PS seed microspheres prepared in the embodiment of the present invention;

[0024] Figure 3 SEM image of the bowl-shaped crosslinked PS particles prepared in Example 1 of the present invention;

[0025] Figure 4 Infrared spectrum of the bowl-shaped crosslinked PS particles prepared in Example 1 of the present invention;

[0026] Figure 5 SEM image of the bowl-shaped crosslinked PS particles prepared in Example 2 of the present invention;

[0027] Figure 6 Infrared spectrum of the bowl-shaped crosslinked PS particles prepared in Example 2 of the present invention;

[0028] Figure 7 SEM image of the bowl-shaped crosslinked PS particles prepared in Example 3 of the present invention;

[0029] Figure 8 Infrared spectrum of the bowl-shaped crosslinked PS particles prepared in Example 3 of the present invention;

[0030] Figure 9 SEM image of the bowl-shaped crosslinked PS particles prepared in Example 4 of the present invention;

[0031] Figure 10 Infrared spectrum of the bowl-shaped crosslinked PS particles prepared in Example 4 of the present invention;

[0032] Figure 11 SEM image of the anisotropic crosslinked PS particles prepared in the comparative example. Detailed implementation mode

[0033] Next, in combination with the embodiments of the present invention, the technical solutions of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0034] The present invention provides a method for preparing bowl-shaped crosslinked polystyrene (PS) particles, comprising the following steps:

[0035] a) Dispersing PS seed microspheres in an aqueous solution of an emulsifier to obtain a seed microsphere emulsion;

[0036] b) After swelling the seed microspheres in the emulsion obtained in step a), the system is purged with nitrogen, sealed, and then placed in 60 a Coγ-ray radiation field for irradiation to obtain a reaction mixture;

[0037] c) After separating the solid product in the reaction mixture obtained in step b), it is successively washed and dried to obtain bowl-shaped crosslinked polystyrene particles.

[0038] The preparation method provided by the present invention prepares bowl-shaped crosslinked PS particles through radiation seed emulsion polymerization. Specifically, non-crosslinked PS microspheres are used as seed microspheres. At room temperature, first, the seed microspheres are swollen in a specific swelling system for a certain period of time, and then 60 irradiated with Coγ-rays, and bowl-shaped crosslinked PS particles can be obtained.

[0039] The present invention first disperses PS seed microspheres in an aqueous solution of an emulsifier to obtain a seed microsphere emulsion. In the present invention, the PS seed microspheres are preferably non-crosslinked PS microspheres, and the particle size is preferably 100 nm to 10 μm, more preferably 2 μm to 5 μm. The present invention has no special limitation on the source of the non-crosslinked PS microspheres, and commercially available products or self-made products well-known to those skilled in the art can be used.

[0040] In the present invention, the emulsifier is preferably an anionic emulsifier, more preferably sodium dodecyl sulfate (SDS); the present invention has no special limitation on the source of the emulsifier, and commercially available products well-known to those skilled in the art can be used. In the present invention, the concentration of the aqueous solution of the emulsifier is preferably the critical micelle concentration (CMC) of the emulsifier.

[0041] In the present invention, the mass ratio of the emulsifier to the PS seed microspheres is preferably 1:(5 - 20), more preferably 1:10.

[0042] In the present invention, the dispersion method is preferably ultrasonic dispersion, and the time is preferably 2 min to 10 min, more preferably 5 min.

[0043] After obtaining the seed microsphere emulsion, the present invention swells the seed microspheres in the obtained emulsion, purges the system with nitrogen, seals it, and then places it in 60 the Coγ-ray radiation field for irradiation to obtain a reaction mixture.

[0044] In the present invention, the swelling process is preferably specifically:

[0045] Using SDS as an emulsifier, dibutyl phthalate (DBP) is emulsified to prepare swelling solution I, and then swelling solution I is added dropwise to the seed microsphere emulsion and stirred for 3 h to 5 h to obtain the first swelling system; then using SDS as an emulsifier, styrene (St) and divinylbenzene (DVB) are emulsified to prepare swelling solution II, and finally swelling solution II is added to the first swelling system and stirring is continued for 10 h to 14 h to complete the swelling process;

[0046] Or,

[0047] Using SDS as an emulsifier, St and DVB were emulsified to obtain swelling solution II. Then, swelling solution II was added to the seed microsphere emulsion, and stirring was continued for 10 h to 14 h to complete the swelling process.

[0048] More preferably:

[0049] Using SDS as an emulsifier, DBP was emulsified to obtain swelling solution I. Then, swelling solution I was added dropwise to the seed microsphere emulsion, and stirring was carried out for 3 h to 5 h to obtain the first swelling system. Then, using SDS as an emulsifier, St and DVB were emulsified to obtain swelling solution II. Finally, swelling solution II was added to the first swelling system, and stirring was continued for 10 h to 14 h to complete the swelling process.

[0050] In the present invention, the swelling solution I is a DBP emulsion using SDS as an emulsifier. The concentration of the SDS aqueous solution used is preferably 6×10 -3 ~2.4×10 -2 mol / L, more preferably 0.008 mol / L; wherein, the mass ratio of DBP to PS seed microspheres is preferably (0.1 - 6.7):1.

[0051] In the present invention, the swelling solution II is a St-DVB emulsion using SDS as an emulsifier. The concentration of the SDS aqueous solution used is preferably 6×10 -3 ~2.4×10 -2 mol / L, more preferably 0.008 mol / L; wherein, the monomer content in the monomer emulsion is preferably 1 wt% - 10 wt%, the mass ratio of St to DVB is preferably (0.5 - 4):1, and more preferably 1:1.

[0052] After that, nitrogen was introduced, sealed, and then placed in 60 a Coγ-ray radiation field for irradiation to obtain a reaction mixture. In the present invention, the sealing method is preferably sealing with a sealing film.

[0053] In the present invention, the irradiation process is preferably carried out under magnetic stirring. The absorption dose rate of the irradiation is preferably 4 Gy / min to 78 Gy / min, more preferably 11 Gy / min to 48 Gy / min, and the total absorption dose is preferably 6 kGy to 70 kGy, more preferably 67 kGy.

[0054] After obtaining the reaction mixture, in the present invention, the solid product in the reaction mixture was separated, and then washed and dried in sequence to obtain bowl-shaped crosslinked PS particles.

[0055] In the present invention, the separation method is preferably centrifugal separation; the cleaning method is preferably ethanol cleaning; the drying method is heating and drying, and the temperature is preferably 50°C to 70°C, more preferably 60°C.

[0056] In the present invention, non-crosslinked PS microspheres are used as seeds. After swelling at room temperature in a suitable crosslinking monomer / swelling agent system, 60 Coγ-rays are used to initiate the polymerization of the swollen monomers at room temperature to prepare bowl-shaped crosslinked PS particles with regular morphology; the preparation method of bowl-shaped crosslinked PS particles provided by the present invention has the advantages of simple preparation method, mild reaction conditions, environmental friendliness, etc., is more conducive to controlling the polymer and solvent phase separation process, and better ensures the monodispersity of the bowl-shaped particle size.

[0057] The present invention also provides a kind of bowl-shaped crosslinked PS particles, which are prepared by the preparation method described in the above technical solution. The bowl-shaped crosslinked PS particles prepared by the present invention present a bowl shape with regular morphology, and the overall diameter is preferably 2 μm to 5 μm, and there are potential applications in the fields of preparing optical materials, specific recognition and separation materials, etc.

[0058] The present invention provides a kind of bowl-shaped crosslinked PS particles and a preparation method thereof; the preparation method includes the following steps: a) dispersing PS seed microspheres in an aqueous emulsifier solution to obtain a seed microsphere emulsion; b) swelling the seed microspheres in the emulsion obtained in step a), then passing nitrogen through the system, sealing it, and then placing it 60 in a Coγ-ray radiation field for irradiation to obtain a reaction mixture; c) separating the solid product in the reaction mixture obtained in step b), and then successively performing cleaning and drying to obtain bowl-shaped crosslinked PS particles. Compared with the prior art, in the present invention, non-crosslinked PS microspheres are used as seeds. After swelling at room temperature in a suitable crosslinking monomer / swelling agent system, 60 Coγ-rays are used to initiate the polymerization of the swollen monomers at room temperature to prepare bowl-shaped crosslinked PS particles with regular morphology; the preparation method of bowl-shaped crosslinked PS particles provided by the present invention has the advantages of simple preparation method, mild reaction conditions, environmental friendliness, etc., is more conducive to controlling the polymer and solvent phase separation process, and better ensures the monodispersity of the bowl-shaped particle size; at the same time, the prepared bowl-shaped crosslinked polystyrene particles have potential applications in the fields of preparing optical materials, specific recognition and separation materials, etc.

[0059] In order to further illustrate the present invention, the following examples are used for detailed description. The raw materials used in the following examples of the present invention are all commercially available; among them, the two different particle size monodisperse PS seed microspheres used are respectively prepared by the following preparation methods:

[0060] (1) Preparation of PS seed microspheres with a particle size of 2.04 μm:

[0061] 90 g of absolute ethanol and 10 g of deionized water were poured into a 250 mL beaker, 1.5 g of PVP-K30 was added, and ultrasonically dispersed for 5 min. Then 18 g of St was added and ultrasonically dispersed for another 3 min. Nitrogen was passed through the system for 5 min, and the temperature was raised to 70 °C under magnetic stirring. 3 g of St (dissolved with 200 mg of azobisisobutyronitrile AIBN) was quickly added and reacted for 20 h. The reaction solution was centrifuged to obtain a solid product, washed with ethanol, and then centrifuged again (Zhongjia HC-2518 high-speed centrifuge, rotation speed 5000 rpm). The above ethanol washing - centrifugation process was repeated three times. Finally, the product was placed in an oven at 60 °C to dry for standby, and PS seed microspheres were obtained.

[0062] The morphology of the PS seed microspheres was observed by a cold field emission scanning electron microscope (SEM, SU8200, 3 kV), as Figure 1 shown in a. The particle size was 2.04 μm, and the calculated PDI = 1.03; the infrared spectrum (FTIR, Bruker TENSORII) of the product was as Figure 2 shown, where 3030 cm -1 was the stretching vibration peak of olefin C-H, 2930 cm -1 was the asymmetric stretching vibration peak of the main chain methylene, 1670 cm -1 was the C=O vibration peak of PVP-K30, 1600 cm -1 , 1490 cm -1 , 1450 cm -1 were the skeletal vibration absorption peaks of the benzene ring, 760 cm -1 , 694 cm -1 were the characteristic absorption peaks of the monosubstituted benzene ring. In summary, non-crosslinked polystyrene microspheres were polymerized.

[0063] (2) Preparation of 100 nm PS seed microspheres:

[0064] 40 mL of deionized water was poured into a 100 mL beaker, 50 mg of SDS was added, and ultrasonically dispersed for 5 min. Then 2.5 g of St, 40 mg of n-hexadecane, and 25 mg of AIBN were added and ultrasonically dispersed for another 15 min. The prepared emulsion was transferred to a 100 mL three-necked flask, nitrogen was passed through the system for 5 min, and the temperature was raised to 75 °C under magnetic stirring and reacted for 20 h. The reaction solution was centrifuged to obtain a solid product, washed with ethanol, and then centrifuged again (Zhongjia HC-2518 high-speed centrifuge, rotation speed 10000 rpm). The above ethanol washing - centrifugation process was repeated three times. Finally, the product was placed in an oven at 60 °C to dry for standby, and PS seed microspheres were obtained.

[0065] The morphology of the PS seed microspheres was observed by a cold field emission scanning electron microscope (SEM, SU8200, 3 kV), as Figure 1 shown in b, with a particle size of 100 nm; the infrared spectrum (FTIR, Bruker TENSOR II) of the product was as Figure 2 shown, where 3026 cm -1 was the stretching vibration peak of olefin C-H, 2920 cm -1 was the asymmetric stretching vibration peak of the main chain methylene, 1606 cm -1 , 1492 cm -1 , 1453 cm -1 were the skeletal vibration absorption peaks of the benzene ring, and 759 cm -1 , 690 cm -1 were the characteristic absorption peaks of the monosubstituted benzene ring. In summary, non-crosslinked polystyrene microspheres were obtained by polymerization.

[0066] Example 1

[0067] Preparation of bowl-shaped crosslinked PS particles:

[0068] Preparation of the seed emulsion: Weigh 12.5 mg of SDS and dissolve it in 5 mL of deionized water, then add 125 mg of the above self-made PS seed microspheres (2.04 μm), and ultrasonically disperse for 5 min to obtain a PS seed microsphere emulsion.

[0069] Preparation of swelling solution I: Weigh 12.5 mg of SDS and dissolve it in 5 mL of deionized water. Add 0.5 mL of DBP dropwise to the SDS aqueous solution, and ultrasonically disperse for 5 min to obtain a DBP emulsion. Under magnetic stirring, this emulsion was added dropwise to the above PS seed microsphere emulsion and swollen for 4 h.

[0070] Preparation of swelling solution II: Take a 50 mL beaker, add 15 mL of deionized water, 37.5 mg of SDS, 0.63 g of DVB, and 0.63 g of St, and ultrasonically disperse for 10 min to obtain a monomer swelling solution; this monomer swelling solution emulsion was added dropwise into the above PS seed emulsion and swollen for another 12 h.

[0071] After the swelling was completed, nitrogen was passed through the reaction liquid system, sealed with a sealing film, and then placed in a cobalt-60 radiation source chamber (activity 4.07×10 14 Bq) for irradiation. The dose rate was selected as 48 Gy / min, and the total absorbed dose was 67 kGy; after irradiation, the solid matter in the system was centrifuged, washed with ethanol, and then placed in an oven at 60 °C to dry, obtaining the target product bowl-shaped crosslinked PS particles.

[0072] The morphology of the bowl-shaped crosslinked PS particles was observed by a cold field emission scanning electron microscope (SEM, SU8200, 3 kV), as Figure 3As shown, the particles present a bowl shape, with an overall diameter of approximately 3.51 μm; the infrared spectrum (FTIR, Bruker TENSORII) of the product is as Figure 4 shown (infrared spectrum diagram with PS seed microspheres), 1596 cm -1 , 1492 cm -1 , 1446 cm -1 are the absorption peaks of the benzene ring skeleton vibration, and 759 cm -1 , 697 cm -1 are the characteristic absorption peaks of the monosubstituted benzene ring. In summary, bowl-shaped PS particles are polymerized.

[0073] Example 2 (changing the absorption dose rate)

[0074] Preparation of the seed emulsion: Weigh 12.5 mg of SDS and dissolve it in 5 mL of deionized water, then add 125 mg of the above-mentioned self-made PS seed microspheres (2.04 μm), and ultrasonically disperse for 5 min to obtain the PS seed microsphere emulsion.

[0075] Preparation of the swelling solution I: Weigh 12.5 mg of SDS and dissolve it in 5 mL of deionized water, add 0.5 mL of DBP dropwise to the SDS aqueous solution, ultrasonically disperse for 5 min to obtain the DBP emulsion, and under magnetic stirring, drop this emulsion dropwise into the above PS seed microsphere emulsion and swell for 4 h.

[0076] Preparation of the swelling solution II: Take a 50 mL beaker, add 15 mL of deionized water, 37.5 mg of SDS, 0.63 g of DVB, and 0.63 g of St, ultrasonically disperse for 10 min to obtain the monomer swelling solution; drop this monomer swelling solution emulsion dropwise into the above PS seed emulsion and continue to swell for 12 h.

[0077] After the swelling is completed, the reaction liquid system is purged with nitrogen, sealed with a sealing film, and then placed in a cobalt-60 radiation source chamber (activity of 4.07×10 14 Bq) for irradiation. The dose rate is selected to be 11 Gy / min, and the total absorbed dose is 67 kGy; after the irradiation is completed, the solid matter in the system is centrifuged, washed with ethanol, and placed in an oven at 60 °C to dry, and the target product, bowl-shaped crosslinked PS particles, is obtained.

[0078] The morphology of the bowl-shaped crosslinked PS particles is observed by a cold field emission scanning electron microscope (SEM, SU8200, 3 kV), as Figure 5 shown, the particles present a bowl shape, with an overall diameter of approximately 3.2 μm; the infrared spectrum (FTIR, Bruker TENSORII) of the product is as Figure 6 shown (infrared spectrum diagram with PS seed microspheres), 1599 cm -1 , 1492 cm -1, 1453 cm -1 is the absorption peak of the skeletal vibration of the benzene ring, 754 cm -1 , 697 cm -1 are the characteristic absorption peaks of the monosubstituted benzene ring. In summary, bowl-shaped PS particles are obtained by polymerization.

[0079] Example 3 (without swelling solution I)

[0080] Preparation of seed emulsion: Weigh 12.5 mg of SDS and dissolve it in 5 mL of deionized water, then add 125 mg of the above self-made PS seed microspheres (2.04 μm), and ultrasonically disperse for 5 min to obtain a PS seed microsphere emulsion.

[0081] Preparation of swelling solution II: Take a 50 mL beaker, add 15 mL of deionized water, 37.5 mg of SDS, 0.63 g of DVB and 0.63 g of St, and ultrasonically disperse for 10 min to obtain a monomer swelling solution; dropwise add this monomer swelling solution emulsion into the above PS seed emulsion and continue to swell for 12 h.

[0082] After the swelling is completed, the reaction liquid system is purged with nitrogen, sealed with a sealing film, and then placed in a cobalt-60 radiation source chamber (activity is 4.07×10 14 Bq) for irradiation, the dose rate is selected as 48 Gy / min, and the total absorbed dose is 67 kGy; after the irradiation is completed, the solid matter in the system is centrifuged, washed with ethanol, and then placed in an oven at 60 °C to dry, and the target product, bowl-shaped crosslinked PS particles, is obtained.

[0083] The morphology of the bowl-shaped crosslinked PS particles is observed by a cold field emission scanning electron microscope (SEM, SU8200, 3 kV), as Figure 7 shown, the particles are bowl-shaped, and the overall diameter is about 2.73 μm; the infrared spectrum of the product (FTIR, Bruker TENSORII) is as Figure 8 shown (the infrared spectrum diagram with PS seed microspheres), 1599 cm -1 , 1492 cm -1 , 1453 cm -1 are the absorption peaks of the skeletal vibration of the benzene ring, 754 cm -1 , 697 cm -1 are the characteristic absorption peaks of the monosubstituted benzene ring. In summary, bowl-shaped PS particles are obtained by polymerization.

[0084] Example 4 (changing the particle size of the seed microspheres)

[0085] Preparation of seed emulsion: Weigh 12.5 mg of SDS and dissolve it in 5 mL of deionized water, then add 125 mg of 100 nm PS seed microspheres, and ultrasonically disperse for 5 min to obtain a PS seed microsphere emulsion.

[0086] Preparation of swelling solution I: Weigh 12.5 mg of SDS and dissolve it in 5 mL of deionized water. Add 0.5 mL of DBP dropwise to the SDS aqueous solution, and ultrasonically disperse for 5 min to obtain a DBP emulsion. Under magnetic stirring, dropwise add this emulsion to the PS seed microsphere emulsion and swell for 4 h.

[0087] Preparation of swelling solution II: Take a 50 mL beaker, add 15 mL of deionized water, 37.5 mg of SDS, 0.63 g of DVB, and 0.63 g of St, and ultrasonically disperse for 10 min to obtain a monomer swelling solution. Dropwise add this monomer swelling solution emulsion into the above PS seed emulsion and continue to swell for 12 h.

[0088] After the swelling is completed, the reaction liquid system is purged with nitrogen, sealed with a sealing film, and then placed in a cobalt-60 radiation source chamber (activity: 4.07×10 14 Bq) for irradiation. The dose rate is selected as 48 Gy / min, and the total absorbed dose is 67 kGy. After irradiation, the solid substances in the system are centrifuged, washed with ethanol, and then dried in an oven at 60 °C to obtain the target product, bowl-shaped cross-linked PS particles.

[0089] The morphology of the bowl-shaped cross-linked PS particles was observed using a cold field emission scanning electron microscope (SEM, SU8200, 3 kV). As Figure 9 shown, the particles are bowl-shaped; the infrared spectrum of the product (FTIR, Bruker TENSORII) is as Figure 10 shown (infrared spectrum diagram with PS seed microspheres). 1599 cm -1 , 1492 cm -1 , 1453 cm -1 are the skeletal vibration absorption peaks of the benzene ring, and 754 cm -1 , 697 cm -1 are the characteristic absorption peaks of the monosubstituted benzene ring. In summary, bowl-shaped PS particles were polymerized.

[0090] Comparative example (changing the initiation method)

[0091] Preparation of seed emulsion: Weigh 62.5 mg of APS and 12.5 mg of SDS, dissolve them in 5 mL of deionized water, and then add 125 mg of the above self-made PS seed microspheres (2.04 μm), and ultrasonically disperse for 5 min to obtain a PS seed microsphere emulsion.

[0092] Preparation of swelling solution I: Weigh 12.5 mg of SDS and dissolve it in 5 mL of deionized water. Add 0.5 mL of DBP dropwise to the SDS aqueous solution, and ultrasonically disperse for 5 min to obtain a DBP emulsion. Under magnetic stirring, dropwise add this emulsion to the PS seed microsphere emulsion and swell for 4 h.

[0093] Preparation of swelling solution II: Take a 50 mL beaker, add 15 mL of deionized water, 37.5 mg of SDS, 0.63 g of DVB and 0.63 g of St, and ultrasonically disperse for 10 min to obtain a monomer swelling solution; dropwise add this monomer swelling solution emulsion into the above PS seed emulsion and continue swelling for 12 h.

[0094] After the swelling is completed, nitrogen is passed through the reaction solution system and sealed with a rubber stopper. Weigh 62.5 mg of sodium sulfite and dissolve it in 1 mL of deionized water, pass nitrogen through it, suck the sodium sulfite aqueous solution with a syringe, quickly inject it into the swelling solution II, stir magnetically for 12 h. After the reaction is completed, centrifuge the solid in the system, wash it with ethanol, and then place it in an oven at 60 °C to dry to obtain the product anisotropic cross-linked PS particles.

[0095] The morphology of the anisotropic cross-linked PS particles was observed with a cold field emission scanning electron microscope (SEM, SU8200, 3 kV), as Figure 11 shown, the product particles are severely agglomerated and the morphology is disordered.

[0096] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing bowl-shaped crosslinked polystyrene particles, characterized in that, Comprising the following steps: a) Dispersing polystyrene seed microspheres in an aqueous solution of an emulsifier to obtain a seed microsphere emulsion; the polystyrene seed microspheres are non-crosslinked PS microspheres with a particle size of 100 nm to 10 μm; b) After swelling the seed microspheres in the emulsion obtained in step a), the system is purged with nitrogen, sealed, and then placed in 60 a Coγ-ray radiation field for irradiation to obtain a reaction mixture; the specific process of the swelling is as follows: Using sodium dodecyl sulfate as an emulsifier, emulsifying dibutyl phthalate to obtain a swelling solution I, then dropping the swelling solution I into the seed microsphere emulsion and stirring for 3 h to 5 h to obtain a first swelling system; then using sodium dodecyl sulfate as an emulsifier, emulsifying styrene and divinylbenzene to obtain a swelling solution II, and finally adding the swelling solution II to the first swelling system and continuing to stir for 10 h to 14 h to complete the swelling process; Or, Using sodium dodecyl sulfate as an emulsifier, emulsifying styrene and divinylbenzene to obtain a swelling solution II, then adding the swelling solution II to the seed microsphere emulsion and continuing to stir for 10 h to 14 h to complete the swelling process; The concentration of the sodium dodecyl sulfate aqueous solution used in the swelling solution I is 6×10 -3 ~2.4×10 -2 mol / L; wherein the mass ratio of dibutyl phthalate to polystyrene seed microspheres is (0.1~6.7):1; The concentration of the sodium dodecyl sulfate aqueous solution used in the swelling solution II is 6×10 -3 ~2.4×10 -2 mol / L, where the monomer content is 1 wt% to 10 wt%, and the mass ratio of styrene to divinylbenzene is (0.5 to 4):1; c) After separating the solid product in the reaction mixture obtained in step b), successively washing and drying to obtain bowl-shaped crosslinked polystyrene particles.

2. The preparation method according to claim 1, characterized in that, In step a), the emulsifier is an anionic emulsifier; the mass ratio of the emulsifier to the polystyrene seed microspheres is 1:(5 - 20).

3. The preparation method according to claim 1, wherein In step a), the dispersing method is ultrasonic dispersion for a time of 2 min to 10 min.

4. The preparation method according to claim 1, characterized in that, In step b), the dose rate of the irradiation is 4 Gy / min to 78 Gy / min, and the total absorbed dose is 6 kGy to 70 kGy.

5. The preparation method according to claim 1, characterized in that, In step c), the separating method is centrifugal separation; the washing method is ethanol washing; the drying method is heating and drying at a temperature of 50°C to 70°C.

6. A bowl-shaped crosslinked polystyrene particle, characterized in that, Prepared by the preparation method according to any one of claims 1 to 5.

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