Continuous synthesis method of monodisperse polystyrene microspheres
By emulsifying the aqueous and oil phases in an ultrasonic micro reactor, the nanoemulsion was prepared and heated in a standstill state, the problems of uneven particle size and poor monodispersity in the existing polystyrene microsphere production were solved, and continuous production and controllable particle size were achieved.
Patent Information
- Application Number
- CN202510619044.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-14
- Publication Date
- 2025-08-08
AI Technical Summary
The existing polystyrene microsphere production process is batch production, and the stirring efficiency and effect have a great impact on product quality, resulting in uneven particle size distribution between batches and poor monodispersity, and the local temperature gradient of the reaction system affects side reactions and reduces product purity.
The aqueous and oil phases are emulsified by an ultrasonic micro reactor to prepare a nanoemulsion heated under a standstill state to form polystyrene microspheres with uniform particle size. Continuous production is achieved by controlling the ultrasonic treatment parameters and heating conditions without stirring.
The synthesis of polystyrene microspheres without stirring is achieved. The product batch quality is stable and the particle size is controllable, which improves production efficiency and output, and reduces production costs and environmental impact.
Smart Images
Figure CN120441738A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of organic polymers, and particularly relates to a continuous synthesis method of monodisperse polystyrene microspheres. Background Art
[0002] Polystyrene is synthesized by the addition polymerization of styrene monomers. Polystyrene microspheres are one of the polystyrene products. With their controllable particle size, surface modifiability and diverse functions (such as fluorescence, magnetism, and porosity), polystyrene microspheres have shown broad application potential in biomedicine, environmental governance, industrial catalysis, and advanced materials.
[0003] Currently, polystyrene microspheres can be produced through soap-free emulsion polymerization, a technique that uses no or only trace amounts of emulsifiers. Its core principle is to introduce polar groups into the polymer chain using initiators or hydrophilic monomers, thus imparting surface activity to the polymer. The advantage of soap-free emulsion polymerization is that it avoids the negative effects of emulsifier residue on the material's electrical properties, water resistance, and surface finish, and can produce highly monodisperse polymer particles with clean surfaces.
[0004] However, the existing polystyrene microsphere production process is a batch production process, generally stirring and synthesizing in a reactor. The stirring efficiency and stirring effect have a significant impact on the product. During the production process of polystyrene microspheres, parameters such as monomer concentration, emulsifier ratio and reaction temperature need to be frequently adjusted, which can easily lead to uneven particle size distribution between batches (such as particle size fluctuation range >20%) and poor monodispersity. At the same time, the reaction system is affected by local temperature gradients, which may trigger side reactions and reduce product purity. Based on this, it is necessary to improve the existing polystyrene production process. Summary of the Invention
[0005] To solve the above technical problems, the purpose of the present invention is to provide a continuous synthesis method for monodisperse polystyrene microspheres, which has the advantages of continuous production, no need for stirring, and controllable particle size, and the product batch quality is stable.
[0006] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is as follows:
[0007] A continuous synthesis method for monodisperse polystyrene microspheres is as follows:
[0008] The aqueous phase and the oil phase are respectively input into an ultrasonic microreactor for ultrasonic emulsification treatment to obtain a nanoemulsion. The nanoemulsion is heated in a static state to polymerize the styrene droplets in the nanoemulsion into polystyrene to obtain polystyrene microspheres, wherein the aqueous phase contains an initiator and the oil phase is a styrene monomer.
[0009] Preferably, the initiator includes any one or more of a free radical polymerization initiator, an anionic polymerization initiator, cumene hydroperoxide and a rare earth complex catalyst;
[0010] More preferably, the initiator includes one or more of potassium persulfate, ammonium persulfate, azobisisobutyronitrile (AIBN) and dibenzoyl peroxide (BPO).
[0011] Preferably, based on the mass of the oil phase, the mass of the initiator in the water phase accounts for 0.3 to 5% of the mass of the oil phase;
[0012] More preferably, the mass of the initiator accounts for 4% of the mass of the oil phase.
[0013] Preferably, the aqueous phase further contains a stabilizer, which includes sodium bisulfate and / or sodium chloride;
[0014] Based on the mass of the oil phase, the percentage of the mass of the stabilizer in the water phase to the mass of the oil phase is ≤3%.
[0015] Preferably, the aqueous phase further contains a particle size control agent, and the particle size control agent includes sodium p-styrene sulfonate;
[0016] Based on the mass of the oil phase, the mass percentage of the particle size control agent in the water phase to the mass of the oil phase is ≤5%.
[0017] Preferably, before the water phase and the oil phase are respectively fed into the ultrasonic microreactor, the water phase and the oil phase are respectively subjected to nitrogen bubbling treatment to discharge oxygen in the water phase and the oil phase, and to discharge water in the oil phase.
[0018] Preferably, before the water phase and the oil phase are respectively input into the ultrasonic microreactor, the water phase and the oil phase are preheated at a temperature of 80°C.
[0019] Preferably, the flow rate of the oil phase input into the ultrasonic microreactor is 0.1-0.8 ml / min, and the flow rate of the water phase input into the ultrasonic microreactor is 5-6 ml / min.
[0020] More preferably, the flow rate ratio of the oil phase to the water phase is 1:(6-60).
[0021] Preferably, the residence time of the oil phase and the water phase in the ultrasonic microreactor is 2 to 8 minutes.
[0022] Preferably, the ultrasonic power of the ultrasonic microreactor is 30-200W, more preferably, the ultrasonic power is 120W.
[0023] Preferably, the temperature for heating the nanoemulsion is 60-80° C., and the heating time is 5-12 hours.
[0024] Beneficial effects:
[0025] The present invention realizes continuous production based on an ultrasonic microreactor, does not require stirring during the production process, effectively improves production efficiency and output, and does not require the use of soap solution during the emulsion preparation process, simplifies the preparation process, and is conducive to reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Figure 1 Shown is an electron microscope image of the polystyrene microspheres prepared in Example 1;
[0027] Figure 2 Shown is an electron microscope image of polystyrene microspheres prepared in Example 2;
[0028] Figure 3 Shown is an electron microscope image of polystyrene microspheres prepared in Example 3;
[0029] Figure 4 Shown is an electron microscope image of polystyrene microspheres prepared in Comparative Example 1;
[0030] Figure 5 Shown is an electron microscope image of polystyrene microspheres prepared in Comparative Example 2;
[0031] Figure 6 Shown is a comparison chart of the yields of the preparation processes of Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3.
[0032] Figure 7 The figure shows a comparison of the particle size and dispersibility of the polystyrene microspheres prepared in Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3.
[0033] Figure 8 Shown is a comparison of the particle size and dispersibility of styrene microspheres prepared in Examples 2, 4, 5 and Comparative Example 4;
[0034] Figure 9 Shown is an electron microscope image of the polystyrene obtained in Comparative Example 5;
[0035] Figure 10 Shown is an electron microscope image of the polystyrene prepared in Comparative Example 6. DETAILED DESCRIPTION
[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the specific embodiments of the present invention will be described below with reference to the accompanying drawings. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings and other embodiments can be obtained based on these drawings without inventive work.
[0037] The present invention provides a continuous synthesis method for monodisperse polystyrene microspheres. The method comprises the following steps: emulsifying a mixed liquid of an oil phase and an aqueous phase using an ultrasonic microreactor to obtain emulsion droplets with uniform particle size; heating the emulsion droplets in a static state to polymerize the emulsion droplets into polystyrene microspheres, thereby forming a polystyrene microsphere product with uniform particle size.
[0038] The emulsification process of the present invention is achieved using an ultrasonic microreactor. The aqueous and oil phases are continuously fed into the ultrasonic microreactor for emulsification, and the ultrasonic microreactor continuously outputs a nanoemulsion with uniform particle size. During the subsequent heating process, the nanoemulsion is no longer stirred, and polystyrene microspheres are generated in situ within the nanoemulsion, addressing the poor batch stability of existing batch production processes. By regulating the input parameters of the aqueous and oil phases and controlling the ultrasonic processing parameters, the droplet size of the nanoemulsion, and thus the particle size of the polystyrene microspheres, can be controlled.
[0039] The continuous synthesis method of the present invention comprises the following steps: respectively inputting an aqueous phase and an oil phase into an ultrasonic microreactor for ultrasonic emulsification treatment to obtain a nanoemulsion; heating the nanoemulsion in a static state to polymerize styrene droplets in the nanoemulsion into polystyrene to obtain polystyrene microspheres, wherein the aqueous phase contains an initiator and the oil phase is a styrene monomer.
[0040] The technical solution of the present invention is introduced below through the description of specific preparation steps.
[0041] The aqueous phase contains an initiator, which is a conventional substance capable of initiating styrene polymerization, including any one or more of free radical polymerization initiators, anionic polymerization initiators, cumene hydroperoxide, and rare earth complex catalysts. Preferably, a water-soluble initiator is used. The initiator is dissolved in the aqueous phase, comes into contact with the styrene monomer only during the emulsification process, and polymerizes the styrene during the heating reaction. More preferably, the initiator includes one or more of potassium persulfate, ammonium persulfate, azobisisobutyronitrile (AIBN), and dibenzoyl peroxide (BPO).
[0042] Based on the mass of the oil phase, the mass of the initiator in the water phase accounts for 0.3-5% of the mass of the oil phase. Preferably, the mass of the initiator accounts for 4% of the mass of the oil phase.
[0043] In some embodiments, the aqueous phase further contains a stabilizer, which serves to stabilize the emulsion during subsequent emulsion preparation. The stabilizer comprises sodium bisulfate and / or sodium chloride. Based on the mass of the oil phase, the mass of the stabilizer in the aqueous phase accounts for ≤3% of the mass of the oil phase. It will be readily understood that a stabilizer is not essential for nanoemulsion preparation, and the amount of stabilizer used may be zero.
[0044] In some embodiments, the aqueous phase also contains a particle size control agent. During the subsequent emulsion preparation process, the particle size control agent contacts the droplets, reduces the surface tension of the droplets, and stabilizes the droplets and reduces the particle size. The particle size control agent includes sodium p-styrene sulfonate. Based on the mass of the oil phase, the mass of the particle size control agent in the aqueous phase accounts for ≤5% of the mass of the oil phase. It is easy to understand that the particle size control agent is not necessary for the preparation of the nanoemulsion, and the amount of particle size control agent can be zero.
[0045] Preferably, the aqueous phase and the oil phase are both bubbled with nitrogen before entering the ultrasonic microreactor to remove oxygen from the aqueous phase and the oil phase, and to remove water from the oil phase. For example, the aqueous phase and the oil phase are each bubbled with nitrogen for 10 minutes.
[0046] In some embodiments, the aqueous phase and the oil phase are preheated before being input into the ultrasonic microreactor. After the preheated aqueous phase and the oil phase are input into the ultrasonic microreactor, first, at the nanoscale, the monomers undergo oligomer polymerization through a free radical initiator to generate short-chain polymers. These short-chain polymers exhibit amphiphilicity, with one end being hydrophilic and the other end being hydrophobic, causing them to behave like surfactants in the liquid phase system. Next, under the action of ultrasound, the strong acoustic cavitation effect causes high-energy microbubbles to be generated in the liquid phase. During the collapse of the microbubbles, an extreme environment of local high temperature and high pressure is formed, accompanied by severe shear force and turbulence effects. This process helps to emulsify styrene monomers and styrene oligomers into stable nanoscale emulsion droplets, and the oligomer chains are adsorbed on the surface of the emulsion droplets, ultimately forming a nanoemulsion.
[0047] Subsequently, during the subsequent heating process, these stable ultrasonic emulsion droplets further polymerize to form the final polymer microspheres. Because the ultrasonic emulsification process does not require additional traditional emulsifiers, but relies on the self-stabilization of the oligomer chains, soap-free miniemulsion polymerization can be achieved. In large-scale production processes, the present invention can be continuously operated through a tubular ultrasonic microreactor to prepare stable nanoemulsions under the action of ultrasound, and the size and morphology of the polymer microspheres formed by subsequent heating polymerization can be optimized by controlling parameters such as ultrasonic energy, monomer concentration, and temperature.
[0048] Preferably, the preheating temperature of the water phase and the oil phase is 80° C. The preheating temperature is close to the temperature of the styrene polymerization reaction. The preheated water phase and the oil phase come into contact in the ultrasonic microreactor to cause oligomer polymerization.
[0049] Preferably, in the present invention, the flow rate of the oil phase into the ultrasonic microreactor is 0.1 to 0.8 ml / min, the flow rate of the water phase into the ultrasonic microreactor is 5 to 6 ml / min, and the residence time of the oil phase and the water phase in the ultrasonic microreactor is 2 to 8 minutes.
[0050] More preferably, the flow rate ratio of the oil phase to the water phase is 1:(6-60).
[0051] In the present invention, the ultrasonic power is 30-200W, preferably, the ultrasonic power is 120W.
[0052] The present invention does not impose any specific restrictions on the structure of the ultrasonic microreactor. For example, the hydraulic diameter of the ultrasonic microreactor is 0.1 to 50 mm, preferably, the hydraulic diameter of the ultrasonic microreactor is 0.5 to 10 mm.
[0053] In the present invention, the nanoemulsion produced by ultrasonic microreactor emulsification should be kept static as much as possible to avoid changes in the emulsion droplet size due to stirring. While the nanoemulsion is still in a heated state, styrene monomer forms droplets that polymerize in situ to produce polystyrene, which then transforms into microspheres. Because the aqueous and oil phases are continuously fed into the ultrasonic microreactor, the ultrasonic microreactor also continuously outputs a nanoemulsion of stable quality. The resulting polystyrene microspheres have a uniform particle size and good dispersibility.
[0054] Preferably, the heating reaction temperature is 60-80° C., which meets the reaction temperature requirement of styrene polymerization.
[0055] Preferably, the heating reaction time is 5 to 12 hours.
[0056] The polystyrene microspheres obtained by heating are post-treated to produce a polystyrene microsphere product. The post-treatment includes washing, wherein the polystyrene microspheres are first washed with water and then washed with anhydrous ethanol. Preferably, the washing is performed by centrifugal washing at a speed of 8000 rpm, wherein the polystyrene microspheres are washed twice with water and then washed twice with anhydrous ethanol, with the first water wash lasting 45 minutes, and the second water wash and the two anhydrous ethanol washes lasting 15 minutes each.
[0057] The present invention allows for continuous scale-up production without the need for high-speed stirring during heating, while also producing stably reproducible polystyrene microspheres. This allows for continuous production without stirring, and compared to conventional preparation methods, the present invention eliminates the need for intermittent stirring and mixing stops, thereby improving production efficiency and output. While conventional kettle-type soap-free emulsion polymerization is limited by the uniformity of stirring efficiency, batch differences are difficult to control, with the smallest difference limited to 100 nm. However, the present invention can achieve batch differences as small as 10 nm.
[0058] The present invention reduces the use of chemical additives and the generation of waste. At the same time, the continuous production feature also helps to reduce energy consumption and reduce environmental impact, meets the requirements of sustainable development, and provides more possibilities for the application of polystyrene microspheres.
[0059] The technical solution of the present invention is described in detail below with reference to specific embodiments.
[0060] Example 1
[0061] In this example, 300 nm polystyrene microspheres were prepared as follows:
[0062] A water phase and an oil phase are prepared, potassium persulfate and sodium bisulfate are added to the water phase, and styrene is added to the oil phase; wherein, based on the mass of the oil phase, the mass of potassium persulfate accounts for 4% of the mass of the oil phase, and the mass of sodium bisulfate accounts for 3% of the mass of the oil phase;
[0063] Nitrogen was bubbled through the oil phase and the aqueous phase for 10 minutes respectively.
[0064] After the oil phase and the water phase were heated in a water bath coil at 80°C, the oil phase was introduced into an ultrasonic microreactor at a flow rate of 0.8 ml / min, and the water phase was introduced into the ultrasonic microreactor at a flow rate of 5.5 ml / min. After ultrasonic treatment with an ultrasonic power of 120 W, a nanoemulsion was obtained.
[0065] The nanoemulsion is heated at 80° C. for 12 hours while being at rest, without stirring during the heating process, and the styrene droplets are polymerized in situ into solid polystyrene microspheres.
[0066] The polystyrene microspheres were first washed twice with water and then washed twice with anhydrous ethanol, wherein the first water washing time was 45 minutes, and the second water washing and the two anhydrous ethanol washing times were both 15 minutes.
[0067] The electron microscope images of the polystyrene microspheres prepared in this embodiment are as follows: Figure 1 As shown, the particle size of the polystyrene microspheres is uniform and narrowly distributed, and the dispersion is good.
[0068] Example 2
[0069] In this example, 200 nm polystyrene microspheres were prepared as follows:
[0070] A water phase and an oil phase are prepared, potassium persulfate and sodium bisulfate are added to the water phase, and styrene is added to the oil phase; wherein, based on the mass of the oil phase, the mass of potassium persulfate accounts for 4% of the mass of the oil phase, and the mass of sodium bisulfate accounts for 3% of the mass of the oil phase;
[0071] Nitrogen was bubbled through the oil phase and the aqueous phase for 10 minutes respectively.
[0072] After the oil phase and the water phase were heated in a water bath coil at 80°C, the oil phase was introduced into an ultrasonic microreactor at a flow rate of 0.3 ml / min, and the water phase was introduced into the ultrasonic microreactor at a flow rate of 6 ml / min. After ultrasonic treatment with an ultrasonic power of 120 W, a nanoemulsion was prepared.
[0073] The nanoemulsion is heated at 80° C. for 12 hours while being at rest, without stirring during the heating process, and the styrene droplets are polymerized in situ into solid polystyrene microspheres.
[0074] The polystyrene microspheres were first washed twice with water and then washed twice with anhydrous ethanol, wherein the first water washing time was 45 minutes, and the second water washing and the two anhydrous ethanol washing times were both 15 minutes.
[0075] The electron microscope images of the polystyrene microspheres prepared in this embodiment are as follows: Figure 2 As shown, the particle size of the polystyrene microspheres is uniform and narrowly distributed, and the dispersion is good.
[0076] Example 3
[0077] In this example, 100 nm polystyrene microspheres were prepared as follows:
[0078] An aqueous phase and an oil phase are prepared, wherein potassium persulfate, sodium bisulfate, and sodium p-styrene sulfonate are added to the aqueous phase, and styrene is added to the oil phase; wherein, based on the total mass of the aqueous phase, the mass percentage of potassium persulfate is 4%, the mass percentage of sodium bisulfate is 3%, and the mass percentage of sodium p-styrene sulfonate is 5%;
[0079] Nitrogen was bubbled through the oil phase and the aqueous phase for 10 minutes respectively.
[0080] After the oil phase and the water phase were heated in a water bath coil at 80°C, the oil phase was introduced into an ultrasonic microreactor at a flow rate of 0.3 ml / min, and the water phase was introduced into the ultrasonic microreactor at a flow rate of 6 ml / min. After ultrasonic treatment with an ultrasonic power of 120 W, a nanoemulsion was prepared.
[0081] The nanoemulsion is heated at 80° C. for 12 hours while being at rest, without stirring during the heating process, and the styrene droplets are polymerized in situ into solid polystyrene microspheres.
[0082] The polystyrene microspheres were first washed twice with water and then washed twice with anhydrous ethanol, wherein the first water washing time was 45 minutes, and the second water washing and the two anhydrous ethanol washing times were both 15 minutes.
[0083] The electron microscope images of the polystyrene microspheres prepared in this embodiment are as follows: Figure 3 As shown, the particle size of the polystyrene microspheres is uniform and narrowly distributed, and the dispersion is good.
[0084] Example 4
[0085] Compared with Example 2, in this example, the oil phase was introduced into the ultrasonic microreactor at a flow rate of 0.2 ml / min, and the water phase was introduced into the ultrasonic microreactor at a flow rate of 6 ml / min, and the remaining steps were the same.
[0086] Example 5
[0087] Compared with Example 2, in this example, the oil phase was introduced into the ultrasonic microreactor at a flow rate of 0.1 ml / min, and the water phase was introduced into the ultrasonic microreactor at a flow rate of 6 ml / min, and the remaining steps were the same.
[0088] Comparative Example 1
[0089] In this comparative example, polystyrene microspheres were prepared using a conventional kettle stirring process.
[0090] The reaction solution was prepared by adding 20 ml of styrene monomer, 400 ml of water and initiator potassium persulfate (based on the mass of styrene monomer, the mass of initiator accounted for 1% of the mass of styrene monomer) into a three-necked flask, and then bubbling nitrogen for 30 minutes to remove oxygen.
[0091] The mixture was heated and stirred at 80° C. for 10 hours at a stirring speed of 250 rpm to obtain polystyrene microspheres.
[0092] The polystyrene microspheres were first washed twice with water and then washed twice with anhydrous ethanol, wherein the first water washing time was 45 minutes, and the second water washing and the two anhydrous ethanol washing times were both 15 minutes.
[0093] The electron microscope image of the polystyrene microspheres prepared in this comparative example is as follows Figure 4 As shown in FIG, the particle size of the polystyrene microspheres is larger.
[0094] Comparative Example 2
[0095] In this comparative example, polystyrene microspheres were prepared using a high-speed homogenizer.
[0096] The reaction solution was prepared by adding 5 ml of styrene monomer, 100 ml of water and initiator potassium persulfate (based on the mass of styrene monomer, the mass of initiator accounted for 1% of the mass of styrene monomer) into a reagent bottle, and then bubbling nitrogen for 30 minutes to remove oxygen.
[0097] The mixture was emulsified and crushed by a high-speed homogenizer at a speed of 3000 rpm for 30 minutes to prepare an emulsion.
[0098] The mixture was heated at 80°C for 10 hours to obtain polystyrene microspheres.
[0099] The polystyrene microspheres were first washed twice with water and then washed twice with anhydrous ethanol, wherein the first water washing time was 45 minutes, and the second water washing and the two anhydrous ethanol washing times were both 15 minutes.
[0100] The electron microscope image of the polystyrene microspheres prepared in this comparative example is as follows Figure 5 As shown in FIG, the particle size of the polystyrene microspheres is larger.
[0101] Comparative Example 3
[0102] In this comparative example, polystyrene microspheres were prepared using an ultrasonic crusher.
[0103] (1) Prepare the reaction solution by adding 5 ml of styrene monomer, 100 ml of water, and initiator potassium persulfate (based on the mass of styrene monomer, the mass of initiator accounts for 1% of the mass of styrene monomer) into a reagent bottle, and then bubbling nitrogen for 30 minutes to remove oxygen.
[0104] (2) The mixture was emulsified and crushed by ultrasonic crusher at a power of 400 W for 30 min to prepare an emulsion.
[0105] (3) Heat at 80°C for 10 hours to obtain polystyrene microspheres.
[0106] (4) The polystyrene microspheres were washed twice with water and then twice with anhydrous ethanol. The first water washing time was 45 min, and the second water washing and the two anhydrous ethanol washing times were both 15 min.
[0107] Comparing the yield and particle size of the preparation process of Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3, as shown in FIG. Figure 6 and 7 shown. Figure 6 and Figure 7 The vertical lines in the middle column graph represent the repeatability and particle size distribution uniformity of the preparation process, respectively.
[0108] Figure 6 and Figure 7 The effects of different preparation processes on the particle size and yield of polystyrene microspheres are demonstrated. The ultrasonic crushing method (Comparative Example 3) and the traditional stirring method (Comparative Example 1) have higher yields, but the fluctuations are large and the repeatability is poor. The yield of the ultrasonic microchannel method (Example 1) is moderate but relatively stable. Compared with Comparative Example 1, the process of the present invention is more suitable for industrial applications with higher requirements for uniformity and repeatability. The high-speed homogenization method (Comparative Example 2) has the lowest yield, indicating that it may not be suitable for efficient preparation, but it can provide more stable experimental results.
[0109] Different preparation methods can significantly affect particle size and distribution uniformity. The preparation process of the present invention demonstrates good control over both particle size and uniformity. Compared to Comparative Examples 1-3, the polystyrene microspheres prepared by the present invention have smaller and more uniform particle sizes, indicating that the present invention is more suitable for preparing small, uniformly distributed particles.
[0110] Comparative Example 4
[0111] Compared with Example 2, in this comparative example, the oil phase was introduced into the ultrasonic microreactor at a flow rate of 1.2 ml / min, the water phase was introduced into the ultrasonic microreactor at a flow rate of 6 ml / min, and the remaining steps were the same.
[0112] The particle size and dispersibility of the styrene microspheres prepared in Examples 2, 4, 5 and Comparative Example 4 are as follows: Figure 8 As shown, it can be seen that when the flow rate ratio of the oil phase to the water phase (calculated by the ratio) is larger, the particle size of the prepared polystyrene microspheres becomes larger and the PDI also becomes larger.
[0113] Comparative Example 5
[0114] Compared with Example 2, in this comparative example, the oil phase and the water phase were preheated to 60° C. before being input into the ultrasonic microreactor, and the remaining steps were the same.
[0115] The polystyrene obtained in this comparative example is Figure 9 As shown in the figure, under the condition of lower preheating temperature, short-chain oligomers are not formed during ultrasonic emulsification to play the role of surfactant, and demulsification is likely to occur. After heating and polymerization, lumps are formed instead of spheres.
[0116] Comparative Example 6
[0117] Compared with Example 2, in this comparative example, stirring was performed while heating the nanoemulsion, and the stirring speed was 1300 rpm, and the remaining steps were the same.
[0118] The polystyrene obtained in this comparative example is Figure 10 As shown, stirring during heating leads to demulsification and microspheres cannot be formed.
[0119] The embodiments provided by the present invention are described in detail above. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the core idea of the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, the present invention can also be improved and modified in a number of ways, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.
Claims
1. A continuous synthesis method for monodisperse polystyrene microspheres, characterized in that: as follows: The aqueous phase and the oil phase are respectively input into an ultrasonic microreactor for ultrasonic emulsification treatment to obtain a nanoemulsion, and the nanoemulsion is heated in a static state to polymerize the styrene droplets in the nanoemulsion into polystyrene to obtain polystyrene microspheres, wherein the aqueous phase contains an initiator and the oil phase is a styrene monomer. Before the aqueous phase and the oil phase are respectively input into the ultrasonic microreactor, the aqueous phase and the oil phase are preheated.
2. The continuous synthesis method of monodisperse polystyrene microspheres according to claim 1, characterized in that: The ultrasonic power of the ultrasonic microreactor is 30-200W, preferably, the ultrasonic power is 120W.
3. The continuous synthesis method of monodisperse polystyrene microspheres according to claim 1, characterized in that: The flow rate of the oil phase input into the ultrasonic microreactor is 0.1-0.8 ml / min, and the flow rate of the water phase input into the ultrasonic microreactor is 5-6 ml / min; The flow rate ratio of the oil phase to the water phase is 1:(6-60).
4. The continuous synthesis method of monodisperse polystyrene microspheres according to claim 3, characterized in that: The residence time of the oil phase and the water phase in the ultrasonic microreactor is 2 to 8 minutes.
5. The continuous synthesis method of monodisperse polystyrene microspheres according to any one of claims 1 to 4, characterized in that: The preheating temperature of the water phase and the oil phase is 80°C.
6. The continuous synthesis method of monodisperse polystyrene microspheres according to any one of claims 1 to 4, characterized in that: The temperature of heating the nanoemulsion is 60-80° C., and the heating time is 5-12 hours.
7. The continuous synthesis method of monodisperse polystyrene microspheres according to claim 1, characterized in that: The initiator includes any one or more of a free radical polymerization initiator, an anionic polymerization initiator, cumene hydroperoxide and a rare earth complex catalyst; Preferably, the initiator includes one or more of potassium persulfate, ammonium persulfate, azobisisobutyronitrile and dibenzoyl peroxide.
8. The continuous synthesis method of monodisperse polystyrene microspheres according to claim 7, characterized in that: Based on the mass of the oil phase, the mass of the initiator in the water phase accounts for 0.3-5% of the mass of the oil phase; Preferably, the mass of the initiator accounts for 4% of the mass of the oil phase.
9. The continuous synthesis method of monodisperse polystyrene microspheres according to claim 1, characterized in that: The aqueous phase also contains a stabilizer, which includes sodium bisulfate and / or sodium chloride; Based on the mass of the oil phase, the percentage of the mass of the stabilizer in the water phase to the mass of the oil phase is ≤3%.
10. The continuous synthesis method of monodisperse polystyrene microspheres according to claim 1, characterized in that: The aqueous phase also contains a particle size control agent, which includes sodium p-styrene sulfonate; Based on the mass of the oil phase, the mass percentage of the particle size control agent in the water phase to the mass of the oil phase is ≤5%.