Preparation method of polystyrene microspheres with controllable particle size

Abstract

The invention belongs to the field of synthesis of polymer microspheres by a microfluidic technology, discloses a preparation method of polystyrene microspheres with controllable particle sizes, and solves the problem of wide particle size distribution of polymer microspheres in a conventional suspension polymerization method at present. The method comprises the following steps: firstly, preparing a surfactant solution with a certain concentration as a water phase, and taking a cross-linking agent, an initiator and monomer styrene in a certain proportion as an oil phase; then collecting the two phases to generate polystyrene micro-droplets at the intersection of the T-shaped micro-mixer; and finally, successfully preparing the polystyrene microspheres with uniform size and controllable particle size by combining a suspension polymerization method. Compared with a traditional method for generating polystyrene through suspension polymerization, the particle size of the polymer microspheres prepared by combining the microchannel technology with the suspension polymerization is 30-260 microns, the size is uniform, the particle size distribution is narrow, and the coefficient of variation is low. The method has the characteristics of simple and easy preparation process, easy control and environmental protection.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer microsphere preparation, and specifically relates to a preparation method of polystyrene microspheres with controllable particle size synthesized based on microfluidic technology. Background Art

[0002] As an important polymer material, polystyrene microspheres have relatively active benzene rings in their structure and are easy to undergo electrophilic substitution reactions. A variety of active groups (such as -SO3H, -COOH, -NO2, -NH2, -CH2Cl, -COCH2Cl, etc.) can be modified on their surfaces to give them new functions. This can better utilize the characteristics of polystyrene and therefore has broad application prospects in the fields of materials science, medical engineering, and biomedicine.

[0003] At present, the methods for synthesizing polystyrene microspheres include suspension, emulsion, dispersion, precipitation and seed polymerization. The synthesized microspheres vary depending on the selected preparation method. The seed polymerization method is expensive and the preparation process is cumbersome, which takes a lot of time. The dispersion polymerization method and precipitation polymerization method are relatively easy and effective for synthesizing monodisperse PS polymers, but the organic solvents used as dispersants are not environmentally friendly. Both suspension and emulsion polymerization methods can be used to obtain porous polymers, but the post-processing operation of emulsion polymerization is cumbersome, and demulsifiers or coagulants need to be added. In addition, the synthesized particles are small, mostly nanoscale, and not easy to recycle. The suspension polymerization method is simple and easy to operate, low cost, and easy post-processing, so it is the most widely used. In terms of the size of polymer microspheres, the traditional method for polymer microspheres has the following limitations: the size distribution of microspheres prepared by suspension polymerization is large and difficult to control, while methods such as porous glass membrane emulsification can improve the particle size distribution, but the cost is high. Emulsion polymerization can prepare microspheres with narrow distribution, but it is difficult to synthesize polymer microspheres with a particle size greater than 10μm. Therefore, it is still challenging to synthesize microspheres with uniform particle sizes ranging from tens to hundreds of microns.

[0004] Chinese patent (CN 114471747 B) discloses a method for preparing porous sodium polystyrene sulfonate cation exchange resin, in which suspension polymerization is used to prepare cross-linked polystyrene microspheres, and the particle size of the obtained microspheres is about 160μm. Chinese patent (CN 113845610 B) discloses a method for preparing sodium polystyrene sulfonate, in which suspension polymerization is also used to prepare polystyrene microspheres with a particle size of less than 50μm. The above method requires a high rotation speed to obtain polystyrene microspheres of tens of microns and the particle size distribution of the microspheres is relatively wide. However, the use of droplet microfluidics technology may realize the preparation of monodisperse, high-yield micron-sized polystyrene microspheres, and synthesize microspheres with uniform particle sizes ranging from tens to hundreds of microns, which can be used as drug loading or chemical grafting substrate materials. No relevant reports have been seen so far. Summary of the invention

[0005] Therefore, in order to solve the problems of poor particle size dispersion and difficult particle size control in the current synthesis process of polystyrene microspheres, the present invention proposes a method for preparing polystyrene microspheres with uniform and controllable particle size using microfluidic technology, and polystyrene microspheres with narrow particle size distribution, uniform particle size and a size of 30 to 260 μm are prepared.

[0006] The present invention is specifically implemented through the following technical solutions:

[0007] The specific preparation steps are as follows:

[0008] (1) Configuration of continuous phase A solution

[0009] The surfactant is mixed evenly with water under heating conditions to obtain a continuous phase A solution.

[0010] Wherein, the surfactant is one or more of sodium lauryl sulfate, polyvinyl alcohol and polyvinyl pyrrolidone.

[0011] The mass concentration of the surfactant in the continuous phase A solution is 1-5%.

[0012] The mass concentration of the above-mentioned surfactant has a certain influence on the diameter of the microdroplets. The particle size of the obtained polymer microspheres varies with the diameter of the microdroplets. The particle size of the polymer microspheres can be controlled by changing the mass concentration of the surfactant.

[0013] (2) Preparation of dispersed phase B solution

[0014] The monomer styrene (St), the crosslinking agent divinylbenzene (DVB) and the initiator are mixed, and ultrasonically mixed at room temperature to obtain a dispersed phase B solution;

[0015] Wherein, the initiator is one of benzoyl peroxide, azobisisobutyronitrile and azobisisoheptanenitrile. Preferably, the initiator is benzoyl peroxide.

[0016] The mass ratio of the monomer styrene, the crosslinking agent divinylbenzene and the initiator is 7.0: 0.35-1.75: 0.2-0.6.

[0017] Preferably, the mass ratio of monomer styrene, cross-linking agent divinylbenzene, and initiator is 7.0:1.0 to 1.4:0.4.

[0018] (3) Generation of polystyrene microdroplets

[0019] The continuous phase A solution and the dispersed phase B solution prepared above are respectively injected into the microchannel droplet generation device through two injection pumps. The flow rate of the continuous phase is 0.5mL / min~3mL / min, and the flow rate of the dispersed phase is 10~50μL / min; the two-phase solution passes through a T-type micro-mixer, and at the intersection, oil-in-water polystyrene micro-droplets are generated under the shear force of the continuous phase and the dispersed phase, and pass through the capillary channel and are collected in the reaction bottle at the end of the capillary channel;

[0020] The flow rate of the continuous phase is used to control the diameter of the microdroplets, thereby changing the particle size of the polymer microspheres, thereby achieving the purpose of controlling the particle size of the polymer microspheres.

[0021] (4) Generation of polystyrene microspheres

[0022] The polymer droplets are heated in a reaction bottle for suspension polymerization. After the polymerization is completed, polystyrene microspheres are obtained by washing and vacuum drying. The microspheres are dispersed in dichloromethane for post-treatment to remove unreacted monomer impurities and obtain non-toxic and harmless polystyrene microspheres.

[0023] In the range of continuous phase flow rate of 0.5 to 3 mL / min, polymer microspheres with target particle size (30 to 260 μm) are obtained. As the continuous phase flow rate increases, the diameter of the microdroplets decreases, and the particle size of the polymer microspheres also decreases. The present invention regulates the particle size of the polystyrene microspheres by adjusting the flow rate of the continuous phase.

[0024] From the experimental results, the concentration of surfactant in the continuous phase (1% to 5%) increases and the continuous phase flow rate (0.5 to 3 mL / min) continues to accelerate, resulting in a decrease in the diameter of the microdroplets, and then the particle size of the polymer microspheres also continues to shrink, indicating that the particle size of the styrene microspheres and the diameter of the microdroplets determine the particle size of the product polystyrene microspheres. The concentration of surfactant in the continuous phase affects the stability of the droplets. When the concentration of surfactant is lower than 1%, the microdroplets are unstable and easy to break; when the concentration of surfactant is too high, the subsequent washing of the microspheres is difficult, so the concentration of surfactant in the continuous phase is in the range of 1% to 5%. Therefore, the synthesis of polystyrene microspheres with uniform and controllable particle sizes of 30 to 260 μm is affected by the concentration of surfactant and the flow rate of the continuous phase. By adjusting the mass concentration of surfactant in the continuous phase and the flow rate of the continuous phase, the diameter of the microdroplets can be controlled, thereby changing the particle size of the polymer microspheres and achieving particle size control of the polymer microspheres.

[0025] The present invention provides a preparation method for synthesizing polystyrene microspheres with uniform and controllable particle sizes of 30 to 260 μm by using microfluidic technology. By means of a droplet microfluidic generation device, the size of the generated microdroplets is regulated by setting the flow rate ratio of the continuous phase to the dispersed phase and changing the concentration of the surfactant in the continuous phase, a large number of uniform polymer droplets are obtained, and the polymer microspheres with uniform and stable particle sizes ranging from tens of micrometers to hundreds of meters are obtained under thermal initiation conditions. The polystyrene microspheres can be used for enrichment analysis, instrument detection, calibration of molecular carrier flow cytometers and other instruments, etc.; after chemical grafting modification, the polystyrene microspheres can also be used for medical applications such as drug loading, water purification, and blood perfusion. Therefore, polystyrene microspheres with uniform size and controllable particle size have good application prospects.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. The present invention obtains water-in-oil droplets with uniform size and narrow diameter distribution, providing a template for the subsequent preparation of polystyrene microspheres; compared with the microdroplets obtained by the traditional stirring method, the method proposed by the present invention is easier to control the size of the polymer microdroplets.

[0028] 2. The polystyrene microspheres prepared by the present invention have good dispersibility, uniform particle size, size distribution in the range of tens of microns to hundreds of microns, and the particle size of the microspheres is controllable, making the polystyrene microspheres more widely used.

[0029] 3. The present invention uses conventional initiators and dispersants, and prepares micron-sized polystyrene microspheres with excellent monodispersity, narrow particle size distribution, and controllable particle size by microfluidic method without nitrogen protection. The preparation process is simple, easy to control, green, environmentally friendly, and economical.

[0030] 4. The polystyrene microspheres prepared by the present invention are non-toxic and harmless, and after chemical grafting modification, can be applied to the fields of drug loading, blood perfusion, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Diagram of the apparatus for preparing polystyrene microspheres for microchannel technology;

[0032] Figure 2 This is an infrared characterization image of the polystyrene microspheres prepared in Example 1;

[0033] Figure 3 XRD pattern of the polystyrene microspheres prepared in Example 2;

[0034] Figure 4 Microscope images of polystyrene microdroplets prepared in Example 1 and Example 2;

[0035] Figure 5Microscope images of the polystyrene microspheres prepared in Comparative Example 1 and Example 3. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is further described in detail below in conjunction with specific implementations and drawings:

[0037] The microchannel droplet generation device is composed of two injection pumps, a syringe, a continuous phase A solution capillary channel, a dispersed phase B solution capillary channel, a T-type micro mixer, a capillary and a droplet collection reactor. The continuous phase A solution capillary channel and the dispersed phase B solution capillary channel are respectively connected to the feed port of the T-type micro mixer, the discharge port of the T-type micro mixer is connected to the liquid inlet of the capillary, and the liquid outlet of the capillary is connected to the liquid inlet of the reactor for receiving droplets. The aperture of the T-type micro mixer is 0.5 mm, the inner diameter of the capillary channel is 0.5 mm, and the outer diameter is 1.6 mm. A steel needle is inserted into the end of the capillary channel of the droplet collection port, and the steel needle has an outer diameter of 0.5 mm, an inner diameter of 0.4 mm, and a length of 2 cm.

[0038] The embodiment aims to investigate the regulation of the continuous phase flow rate on the microdroplet diameter during the microsphere synthesis process, thereby achieving the controllable particle size preparation of polystyrene microspheres.

[0039] Embodiment 1:

[0040] The method for synthesizing polystyrene microspheres (PS) with uniform particle size using microfluidic technology comprises the following steps:

[0041] (1) Configuration of continuous phase A solution

[0042] Weigh 5 g of polyvinyl alcohol powder and dissolve it in 100 mL of water under heating conditions at 60° C. for 6 h to obtain a continuous phase A solution.

[0043] (2) Preparation of dispersed phase B solution

[0044] 7 g of monomer styrene (St), 1.4 g of cross-linking agent divinylbenzene (DVB) and 0.4 g of benzoyl peroxide were weighed and mixed uniformly under ultrasonication at room temperature for 60 min to obtain a dispersed phase B solution.

[0045] (3) Generation of polystyrene microdroplets

[0046] The prepared continuous phase A solution and dispersed phase B solution were injected into the microchannel droplet generation device through two injection pumps respectively. The continuous phase flow rate was 0.5mL / min, and the dispersed phase flow rate was 20μL / min; the two-phase solution passed through a T-type micromixer, and water-in-oil polystyrene microdroplets were generated at the intersection under the shear force of the continuous phase and the dispersed phase. The microdroplets were collected into a reaction bottle through a capillary tube, and a steel needle was inserted at the end of the capillary tube; the size of the collected droplets was observed and recorded with an inverted microscope. The average diameter of the obtained polystyrene microdroplets was 466.80μm, and the coefficient of variation was 4.21%.

[0047] (4) Generation of polystyrene microspheres

[0048] The polymer droplets collected in the reaction bottle were subjected to solidification suspension polymerization, with stirring and heating temperature of 90°C and polymerization time of 2h. After the polymerization was completed, the polymer was washed with water and acetone several times and vacuum dried at 60°C to obtain polystyrene microspheres. The average diameter of the polystyrene microspheres was 262.8μm, and the coefficient of variation was 6.64%.

[0049] Embodiment 2:

[0050] Compared with Example 1, the continuous phase flow rate is set to 1 mL / min in Example 2. The method for synthesizing polystyrene microspheres (PS) with uniform particle size using microfluidic technology comprises the following steps:

[0051] (1) Configuration of continuous phase A solution

[0052] Weigh 5 g of polyvinyl alcohol powder and dissolve it in 100 mL of water under heating conditions at 60° C. for 6 h to obtain a continuous phase A solution.

[0053] (2) Preparation of dispersed phase B solution

[0054] 7 g of monomer styrene (St), 1.4 g of cross-linking agent divinylbenzene (DVB) and 0.4 g of benzoyl peroxide were weighed and mixed uniformly under ultrasonication at room temperature for 60 min to obtain a dispersed phase B solution.

[0055] (3) Generation of polystyrene microdroplets

[0056] The continuous phase A solution and dispersed phase B solution prepared above were injected into the microchannel droplet generation device through two injection pumps respectively. The flow rate of the continuous phase was 1mL / min, and the flow rate of the dispersed phase was 20μL / min; the two-phase solution passed through a T-type micromixer, and water-in-oil polystyrene microdroplets were generated at the intersection under the shear force of the continuous phase and the dispersed phase. The microdroplets were collected into a reaction bottle through a capillary, and a steel needle was inserted at the end of the capillary. The size of the collected droplets was observed and recorded with an inverted microscope. The average diameter of the obtained polystyrene microdroplets was 273.45μm, and the coefficient of variation was 3.72%.

[0057] (4) Generation of polystyrene microspheres

[0058] The polymer droplets collected in the reaction bottle were subjected to solidification suspension polymerization, with stirring and heating temperature of 90°C and polymerization time of 2h. After the polymerization was completed, the polymer was washed with water and acetone several times and vacuum dried at 60°C to obtain polystyrene microspheres. The average diameter of the polystyrene microspheres was 143.7μm, and the coefficient of variation was 5.72%.

[0059] Embodiment 3:

[0060] The method for synthesizing polystyrene microspheres (PS) using microfluidic technology comprises the following steps:

[0061] (1) Configuration of continuous phase A solution

[0062] Weigh 5 g of polyvinyl alcohol powder and dissolve it in 100 mL of water under heating conditions at 60° C. for 6 h to obtain a continuous phase A solution.

[0063] (2) Preparation of dispersed phase B solution

[0064] 7 g of monomer styrene (St), 0.7 g of cross-linking agent divinylbenzene (DVB) and 0.4 g of benzoyl peroxide were weighed and mixed uniformly under ultrasonication at room temperature for 60 min to obtain a dispersed phase B solution.

[0065] (3) Generation of polystyrene microdroplets

[0066] The continuous phase A solution and dispersed phase B solution prepared above were injected into the microchannel droplet generation device through two injection pumps respectively. The flow rate of the continuous phase was 2mL / min, and the flow rate of the dispersed phase was 20μL / min; the two-phase solution passed through a T-type micromixer, and water-in-oil polystyrene microdroplets were generated at the intersection under the shear force of the continuous phase and the dispersed phase. The microdroplets were collected into a reaction bottle through a capillary channel, and a steel needle was inserted at the end of the capillary channel; the size of the collected droplets was observed and recorded with an inverted microscope. The average diameter of the obtained polystyrene microdroplets was 104.64μm, and the coefficient of variation was 3.47%.

[0067] (4) Generation of polystyrene microspheres

[0068] The polymer droplets collected in the reaction bottle were subjected to suspension polymerization, with stirring and heating at 90°C for 2 hours. After the polymerization was completed, the polymer was washed with water and acetone several times and vacuum dried at 60°C to obtain polystyrene microspheres. The average diameter of the polystyrene microspheres was 68.47 μm, and the coefficient of variation was 5.87%.

[0069] Embodiment 4:

[0070] The method for synthesizing polystyrene microspheres (PS) using microfluidic technology comprises the following steps:

[0071] (1) Configuration of continuous phase A solution

[0072] Weigh 3 g of sodium dodecyl sulfate and 2 g of polyvinyl pyrrolidone powder and dissolve them in 100 mL of water at 60° C. for 6 h to obtain a continuous phase A solution.

[0073] (2) Preparation of dispersed phase B solution

[0074] 7 g of monomer styrene (St), 0.7 g of cross-linking agent divinylbenzene (DVB) and 0.4 g of benzoyl peroxide were weighed and mixed uniformly under ultrasonication at room temperature for 60 min to obtain a dispersed phase B solution.

[0075] (3) Generation of polystyrene microdroplets

[0076] The prepared continuous phase A solution and dispersed phase B solution were injected into the microchannel droplet generation device through two injection pumps respectively. The flow rate of the continuous phase was 3mL / min, and the flow rate of the dispersed phase was 20μL / min; the two-phase solution passed through a T-type micromixer, and water-in-oil polystyrene microdroplets were generated at the intersection under the shear force of the continuous phase and the dispersed phase. The microdroplets were collected into a reaction bottle through a capillary channel, and a steel needle was inserted at the end of the capillary channel; the size of the collected droplets was observed and recorded with an inverted microscope. The average diameter of the obtained polystyrene microdroplets was 63.64μm, and the coefficient of variation was 3.86%.

[0077] (4) Generation of polystyrene microspheres

[0078] The polymer droplets collected in the reaction bottle were subjected to solidification suspension polymerization, with stirring and heating temperature of 85°C and polymerization time of 2h. After the polymerization was completed, water and acetone were washed several times, and polystyrene microspheres were obtained after vacuum drying at 60°C for 10h. The average diameter of the polystyrene microspheres was 36.85μm, and the coefficient of variation was 5.26%.

[0079] Examples 1 to 4 investigated the diameter distribution of the generated polymer microdroplets when the flow rate of the continuous phase was in the range of 0.5 to 3 mL / min, and finally obtained polymer microspheres of the target particle size (30 to 260 μm) through droplet solidification. As the flow rate of the continuous phase continued to increase, the diameter of the microdroplets decreased, and then the particle size of the polymer microspheres also continued to shrink, indicating that the particle size of the polystyrene microspheres can be regulated by adjusting the flow rate of the continuous phase.

[0080] Embodiment 5:

[0081] The method for synthesizing polystyrene microspheres (PS) using microfluidic technology comprises the following steps:

[0082] (1) Configuration of continuous phase A solution

[0083] Weigh 3 g of sodium dodecyl sulfate and 2 g of polyvinyl pyrrolidone powder and dissolve them in 100 mL of water at 60° C. for 6 h to obtain a continuous phase A solution.

[0084] (2) Preparation of dispersed phase B solution

[0085] 7 g of monomer styrene (St), 1.4 g of cross-linking agent divinylbenzene (DVB) and 0.4 g of benzoyl peroxide were weighed and mixed uniformly under ultrasonication at room temperature for 60 min to obtain a dispersed phase B solution.

[0086] (3) Generation of polystyrene microdroplets

[0087] The prepared continuous phase A solution and dispersed phase B solution were injected into the microchannel droplet generation device through two injection pumps respectively. The flow rate of the continuous phase was 2mL / min, and the flow rate of the dispersed phase was 50μL / min; the two-phase solution passed through a T-type micromixer, and water-in-oil polystyrene microdroplets were generated at the intersection under the shear force of the continuous phase and the dispersed phase. The microdroplets were collected into a reaction bottle through a capillary channel, and a steel needle was inserted at the end of the capillary channel; the size of the collected droplets was observed and recorded with an inverted microscope. The average diameter of the obtained polystyrene microdroplets was 117.72μm, and the coefficient of variation was 2.19%.

[0088] (4) Generation of polystyrene microspheres

[0089] The polymer droplets collected in the reaction bottle were subjected to solidification suspension polymerization, with stirring and heating temperature of 85°C and polymerization time of 4h. After the polymerization was completed, the polystyrene microspheres were washed with water and acetone several times and vacuum dried at 60°C for 10h to obtain the polystyrene microspheres. The average diameter of the polystyrene microspheres was 69.86μm, and the coefficient of variation was 6.28%.

[0090] Embodiment 6:

[0091] The method for synthesizing polystyrene microspheres (PS) using microfluidic technology comprises the following steps:

[0092] (1) Configuration of continuous phase A solution

[0093] Weigh 0.6 g of sodium dodecyl sulfate and 0.4 g of polyvinyl pyrrolidone powder and dissolve them in 100 mL of water at 60° C. for 6 h to obtain a continuous phase A solution.

[0094] (2) Preparation of dispersed phase B solution

[0095] 7 g of monomer styrene (St), 0.7 g of cross-linking agent divinylbenzene (DVB) and 0.4 g of benzoyl peroxide were weighed and mixed uniformly under ultrasonication at room temperature for 60 min to obtain a dispersed phase B solution.

[0096] (3) Generation of polystyrene microdroplets

[0097] The continuous phase A solution and dispersed phase B solution prepared above were injected into the microchannel droplet generation device through two injection pumps respectively. The flow rate of the continuous phase was 2mL / min, and the flow rate of the dispersed phase was 20μL / min; the two-phase solution passed through a T-type micromixer, and water-in-oil polystyrene microdroplets were generated at the intersection under the shear force of the continuous phase and the dispersed phase. The microdroplets were collected into a reaction bottle through a capillary channel, and a steel needle was inserted at the end of the capillary channel; the size of the collected droplets was observed and recorded with an inverted microscope. The average diameter of the obtained polystyrene microdroplets was 213.80μm, and the coefficient of variation was 2.81%.

[0098] (4) Generation of polystyrene microspheres

[0099] The polymer droplets collected in the reaction bottle were subjected to suspension polymerization, with stirring and heating at 90°C for 2 hours. After the polymerization was completed, the polymer was washed with water and acetone several times and vacuum dried at 60°C to obtain polystyrene microspheres. The average diameter of the polystyrene microspheres was 121.3 μm, and the coefficient of variation was 5.96%.

[0100] Examples 5 and 6 investigated the diameter distribution of the generated polymer microdroplets when the surfactant concentration in the continuous phase was in the range of 1% to 5%, and finally polymer microspheres of the target particle size were obtained by solidification of the droplets.

[0101] Comparative Example 1:

[0102] Polystyrene (PS) microspheres were synthesized by conventional suspension polymerization.

[0103] Accurately weigh 15.00g of styrene (St), 3g of divinylbenzene (DVB, calculated as 15.00g of St), 1.00g of benzoyl peroxide (BPO) and 20mL of toluene (diluent) in a 250mL three-necked flask, and ultrasonically disperse for 30min to fully mix the oil phase solution. After completion, add a certain amount of polyvinyl alcohol-water solution (100mL), pass N2 for 20min, seal the device, and mechanically stir at 500r / min. Slowly heat to 50℃ within 30min, adjust to 70℃ for reaction for 2h, and 90℃ for reaction for 4h. After the reaction is completed, filter while hot, wash with water five times until there is no white foam in the aqueous solution, wash with anhydrous ethanol three times, and vacuum dry at 60℃ to obtain PS microspheres. The average particle size of polystyrene microspheres prepared by conventional suspension polymerization is 70.50μm, and the coefficient of variation is 33.85%. Figure 5It can be seen that the uniformity of the obtained microspheres is poor.

[0104] Test Example 1:

[0105] Structural testing of polystyrene microspheres (PS) with uniform particle size synthesized using microfluidic technology.

[0106] Test sample: polystyrene microspheres (PS) prepared in Example 1.

[0107] 1. The prepared polystyrene (PS) microspheres were tested using a Fourier transform infrared spectrometer, with the instrument scanning wave number set to 4000-600 cm -1 The resulting spectrum is as follows Figure 2 As shown in the FTIR spectrum of PS microspheres, it can be seen that 3060cm -1 and 3024cm -1 The absorption peak at 2920 cm-1 is mainly attributed to the stretching vibration of the unsaturated CH bond on the benzene ring. -1 and 2848cm -1 The absorption peak at 1600cm corresponds to the stretching vibration of the CH bond on the alkyl group. -1 、1492cm -1 and 1451cm -1 The absorption peak at 756 cm is the result of the rigid vibration of the monosubstituted benzene ring. -1 and 696cm -1 There is a strong absorption peak at each of the two locations, which is the characteristic absorption peak of the single substitution on the benzene ring. The appearance of these characteristic absorption peaks indicates that the polystyrene (PS) microspheres are successfully prepared.

[0108] 2. X-ray diffractometer was used to detect the phase and crystallinity of the prepared polystyrene (PS) microspheres. The scanning range was 5° to 70°. The obtained XRD spectrum was as follows: Figure 3 As shown. Figure 3 It can be seen that a broad peak appears at 2θ of 19.17°, which matches the JCPDF standard card, indicating that polystyrene is an amorphous structure. This shows that polystyrene (PS) microspheres are successfully prepared.

Claims

1. A method for preparing polystyrene microspheres with controllable particle size, characterized in that: This is accomplished by following these steps: (1) Preparation of continuous phase A solution The surfactant is mixed evenly with water under heating conditions to obtain a continuous phase A solution; The surfactant is one or more of sodium lauryl sulfate, polyvinyl alcohol and polyvinyl pyrrolidone; The mass concentration of the surfactant in the continuous phase A solution is 1-5%; (2) Preparation of dispersed phase B solution The monomer styrene, the crosslinking agent divinylbenzene and the initiator are uniformly mixed, and ultrasonically mixed at room temperature to obtain a dispersed phase B solution; The initiator is one of benzoyl peroxide, azobisisobutyronitrile and azobisisoheptanenitrile; (3) Generation of polystyrene microdroplets The continuous phase A solution and the dispersed phase B solution prepared above are respectively injected into the microchannel droplet generation device through two syringe pumps; The flow rate of the continuous phase is 0.5 mL / min to 3 mL / min, and the flow rate of the dispersed phase is 10 to 50 μ L / min; the two-phase solution passes through a T-type micromixer to generate polystyrene microdroplets, which pass through a capillary channel and are collected in a reaction bottle at the end of the capillary channel; (4) Generation of polystyrene microspheres The polymer droplets are heated in a reaction bottle for suspension polymerization. After the polymerization is completed, polystyrene microspheres are obtained through washing and vacuum drying.

2. The method for preparing polystyrene microspheres according to claim 1, characterized in that: In step (2), the mass ratio of the monomer styrene, the crosslinking agent divinylbenzene, and the initiator is 7.0: (0.35-1.75): (0.2-0.6).

Images