Functionalized polystyrene composite microsphere and preparation method thereof

Abstract

The invention discloses a functionalized polystyrene composite microsphere and a preparation method thereof, and belongs to the technical field of high polymer chemistry and high polymer materials. The functionalized polystyrene composite microspheres are prepared by adopting a one-pot method. A dispersing agent is dissolved in a mixed solution of deionized water and ethyl alcohol to form a dispersion medium, and the dispersion medium and the dispersion medium are mixed uniformly through mechanical stirring; the preparation method comprises the following steps: adding an initiator, a cross-linking agent, a functional polymer or / and a functional monomer into styrene, ultrasonically mixing uniformly, pouring into a dispersion medium, continuously mechanically mixing to obtain a stable reaction system, and starting a heating reaction; after the reaction is finished, filtering, washing and drying a sample after the sample is cooled to room temperature, so as to obtain the functionalized polystyrene composite microspheres. The microspheres prepared by the invention not only have good stability, but also solve the problems of complex preparation process, low functionalization degree and high price of functionalized polystyrene microspheres, and are beneficial to subsequent popularization and application of the functionalized polystyrene composite microspheres.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer chemistry and polymer materials, and specifically relates to a "one-pot method" for preparing functionalized polystyrene composite microspheres and a preparation method thereof. Background Art

[0002] Polystyrene microspheres are non-toxic, tasteless, inexpensive, chemically stable, mechanically strong, and can be functionalized. They are widely used in hydrometallurgy, food processing, biological detection, drug delivery, plant extraction, water treatment, analytical chemistry, chromatography, and water and waste gas treatment. In order to adapt to different application fields, functionalization of polystyrene microspheres is an important prerequisite for their various applications. To this end, researchers usually use the activity of the benzene ring in polystyrene microspheres to introduce functional groups such as chlorination, amination, carboxylation, sulfonation, and nitration on the aromatic ring through substitution reactions, thereby giving the microspheres new functions such as adsorption and catalysis, and preparing solid phase carriers with different uses.

[0003] At present, functionalized polystyrene microspheres are usually prepared by two methods: chemical bonding and physical adsorption. Chemical bonding is to bond functional groups such as benzyl chloride or hexanoyl chloride (bromine) to the surface of polystyrene microspheres to make the polystyrene microspheres active functional groups. A Chinese patent application (CN 115722159 A) discloses an adsorbent for treating hexavalent molybdenum in alkaline wastewater. The method first reacts tetramethylethylenediamine with bromoalkane to generate a monoquaternary ammonium salt intermediate, and then reacts the cross-linked polystyrene microspheres with the monoquaternary ammonium salt intermediate in one step by chemical bonding to obtain a diquaternary ammonium chloride microsphere adsorbent; however, its functionalization preparation process is relatively complicated and requires the use of a large amount of organic solvents, which is not conducive to the green mass production and environmental protection of functionalized polystyrene microspheres. Physical adsorption is to directly adsorb a layer of hydrophilic polymer on the surface of the microsphere, and then cross-link the adsorption layer with a cross-linking agent to increase the stability of the adsorption layer. However, this type of physical coating method has the problem that the adsorption layer needs to be cross-linked and fixed at the end, and the adsorption layer is easy to fall off.

[0004] In summary, there is an urgent need to find a method for preparing functionalized polystyrene composite microspheres with a simple functionalization method, good compatibility and stable functional groups. Summary of the invention

[0005] The purpose of the present invention is to provide a "one-pot" preparation method of functionalized polystyrene composite microspheres and a preparation method thereof in view of the above-mentioned deficiencies in the prior art, so as to solve the problems of complex preparation process, low degree of functionalization and poor compatibility of functionalized polystyrene microspheres.

[0006] In order to solve the above technical problems, the technical solution of the present invention is as follows:

[0007] A functionalized polystyrene composite microsphere, the invention adopts a "one-pot method" to in-situ polymerize a styrene monomer, a functional polymer or / and a mixed system of functional monomers, and in-situ forms functionalized polystyrene composite microspheres with a particle size of 40 to 200 μm during the formation of the polystyrene microspheres. The functionalized polystyrene composite microspheres are formed by suspension polymerization of a styrene mixed system, and the functional components are in-situ copolymerized or blended in the polystyrene microspheres during the suspension polymerization of styrene.

[0008] A method for preparing functionalized polystyrene composite microspheres comprises the following steps:

[0009] (1) At room temperature, in a three-necked flask equipped with a condenser and a mechanical stirrer, a mixed solution of deionized water and ethanol is used as a solvent, and a dispersant solution is added to prepare a dispersion medium. The dispersion medium is mechanically stirred at a speed of 300 to 500 rpm for 5 to 25 minutes to mix the dispersion medium evenly.

[0010] (2) Taking styrene as the monomer, the initiator, the cross-linking agent, the functional polymer or / and the functional monomer are dissolved in the styrene monomer by ultrasonication for 5 to 20 minutes. After being uniformly mixed by ultrasonication, the mixture is poured into the above-mentioned reactor containing the dispersion medium to obtain a mixed solution, and the mixed solution is continuously mechanically stirred to obtain a stable suspension polymerization system.

[0011] (3) The temperature of the reaction system is gradually raised to 60-80°C, and the reaction time is 8-16 hours. After the reaction is completed, the reaction system is cooled to room temperature, and the sample is centrifuged, washed with hot water at 80°C, centrifuged, washed with alcohol, centrifuged and dried to obtain functionalized polystyrene composite microspheres.

[0012] In step (1): in the mixed solution, the volume fraction of ethanol is 10-30%, preferably 20%, and the rest is deionized water. The mass fraction of the dispersant solution is 1-5%, preferably 3%. In the dispersion medium, the volume percentage of the dispersant is 6-10%, preferably 8%.

[0013] In step (1): the dispersant is one or more of polyvinyl alcohol, polyvinyl pyrrolidone, hydroxypropyl methylcellulose, calcium carbonate, calcium phosphate, and magnesium hydroxide, and the dispersant is preferably polyvinyl alcohol.

[0014] In step (1): the mechanical stirring speed is 300 to 500 rpm, preferably 400 rpm;

[0015] In step (2): in the mixed solution, the styrene monomer accounts for 5 to 30% of the volume fraction of the solvent, and the volume fraction is preferably 15%;

[0016] In step (2): the initiator is one or more of azobisisobutyronitrile, azobisisoheptanenitrile, and benzoyl peroxide, and the initiator is preferably azobisisobutyronitrile. The crosslinking agent is one or more of divinylbenzene, diisopropylbenzene peroxide, di-tert-butyl peroxide, and 2,5-dimethyl-2,5-di(tert-butylperoxide)hexane, and the crosslinking agent is preferably divinylbenzene. The functional polymer or / and functional monomer is one or more of polystyrene-vinyl acetate copolymer, polystyrene-butadiene-styrene copolymer, derivatives of polystyrene-butadiene-styrene copolymer, polystyrene-isoprene-styrene copolymer, derivatives of polystyrene-isoprene-styrene copolymer, polystyrene-methyl acrylate copolymer, polylactic acid-hydroxyacetic acid copolymer, polyvinyl chloride, 4-chloromethylstyrene, 4-(N,N-diethylamino)methylstyrene, and 4-hydroxymethylstyrene, and the functional polymer or / and functional monomer is preferably polystyrene-vinyl acetate copolymer or / and 4-chloromethylstyrene.

[0017] In step (2): the initiator accounts for 2-4% of the mass fraction of the styrene monomer, preferably 3%. The crosslinker accounts for 1-3% of the mass fraction of the styrene monomer, preferably 2%. The functional polymer or / and functional monomer accounts for 10-30% of the mass fraction of the styrene monomer, preferably 20%;

[0018] In step (3): the reaction temperature is preferably 70°C, and the reaction time is preferably 12h.

[0019] The reaction principle of the present invention is: select functional polymers and / or functional monomers with good compatibility with styrene, dissolve them in styrene monomers, form micro droplet reaction units in a dispersion medium of suspension polymerization through mechanical stirring, and in the free radical polymerization process of styrene and functional monomers, the functional polymers and polystyrene molecular chains generated by free radical reactions are entangled and mixed, thereby forming functionalized polystyrene composite microspheres in situ.

[0020] The present invention has the following beneficial effects:

[0021] (1) The functional polymer or / and functional monomer used in the functionalized polystyrene composite microspheres prepared by the present invention are cheap, non-toxic, harmless and easy to obtain, which reduces the preparation cost of the functionalized polystyrene composite microspheres and increases the content of functional groups in the microspheres, which is beneficial to the subsequent promotion and application of the functionalized polystyrene composite microspheres.

[0022] (2) The present invention can achieve one-time synthesis of functionalized polystyrene composite microspheres with good dispersibility and large particle size for different purposes and different particle sizes by using only one set of equipment and a "one-pot method", thereby simplifying the preparation process of micron-sized functionalized polystyrene composite microspheres and realizing large-scale industrial production in the later stage.

[0023] (3) The functional group compounding principle in the functionalized polystyrene composite microspheres prepared by the present invention is simple and has strong stability. The functionalization of the microspheres can be achieved through simple physical adsorption. The solubility test found that the functional groups are still successfully attached to the polystyrene microspheres. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a diagram of the reaction apparatus for polymerization reaction.

[0025] Figure 2 This is a scanning electron microscope image of the functionalized polystyrene composite microspheres prepared in Example 2.

[0026] Figure 3 This is the energy spectrum of the functionalized polystyrene composite microspheres prepared in Example 2. Figure 3 (a) is a scanning electron microscope image of functionalized polystyrene composite microspheres; Figure 3 (b) is the C element distribution diagram corresponding to the microsphere in Figure (a); Figure 3 (c) in Figure 3 is the Cl element distribution map corresponding to the microspheres in Figure 3 (a).

[0027] Figure 4 This is the energy spectrum of the functionalized polystyrene composite microspheres prepared in Example 2 after being immersed in a solvent. Figure 4 (a) is the scanning electron microscope image of the cross section of the microsphere after immersion; Figure 4 (b) is the Cl element distribution diagram corresponding to the microspheres in Figure (a). DETAILED DESCRIPTION

[0028] The technical solution of the present invention is further illustrated and described below through specific implementation modes in combination with the accompanying drawings.

[0029] Example 1

[0030] (1) At room temperature, in a three-necked flask equipped with a condenser and a mechanical stirrer (see Figure 1 ), using a mixed solution of 90 mL of deionized water and 10 mL of ethanol as the solvent, adding 6 mL of a 1 wt% polyvinyl alcohol solution, and mechanically stirring at a speed of 300 rpm for 5 min to mix the dispersion medium evenly.

[0031] (2) At room temperature, using 5 mL of styrene as a monomer, 0.1 g of azobisisoheptanenitrile, 0.05 g of divinylbenzene, and 0.5 g of polystyrene-vinyl acetate copolymer were ultrasonically dissolved in the styrene monomer. After being uniformly mixed by ultrasonication for 5 min, the mixture was poured into the reactor containing the dispersion medium in the above step (1), and a stable suspension polymerization system was obtained by continuous mechanical mixing.

[0032] (3) The temperature of the reaction system is gradually raised to 60°C, and the reaction time is 8 hours. After the reaction is completed, the reaction system is cooled to room temperature, and the sample is centrifuged, washed with hot water at 80°C, centrifuged, washed with alcohol, centrifuged and dried to obtain functionalized polystyrene composite microspheres.

[0033] Example 2

[0034] (1) At room temperature, in a three-necked flask equipped with a condenser and a mechanical stirrer, a mixed solution of 80 mL of deionized water and 20 mL of ethanol was used as the solvent, 4 mL of a 3 wt % polyvinyl pyrrolidone solution and 4 mL of a 3 wt % hydroxypropyl methylcellulose solution were added respectively, and mechanical stirring was performed at 370 rpm for 10 min to mix the dispersion medium evenly.

[0035] (2) Using 15 mL of styrene as a monomer, 0.3 g of azobisisobutyronitrile, 0.15 g of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, 1 g of 4-chloromethylstyrene, and 1.25 g of polyvinyl chloride were ultrasonically dissolved in the styrene monomer. After being uniformly mixed by ultrasonication for 10 min, the mixture was poured into the reactor containing the dispersion medium in the above step (1), and a stable suspension polymerization system was obtained by continuous mechanical mixing.

[0036] (3) The temperature of the reaction system was gradually raised to 70°C, and the reaction time was 12 hours. After the reaction was completed, the reaction system was cooled to room temperature, and the sample was centrifuged, washed with hot water, centrifuged, washed with alcohol, centrifuged and dried to obtain functionalized polystyrene composite microspheres (see Figure 2 ).

[0037] Example 3

[0038] (1) At room temperature, in a three-necked flask equipped with a condenser and a mechanical stirrer, a mixed solution of 70 mL of deionized water and 30 mL of ethanol was used as the solvent, and 10 mL of a 5 wt% calcium carbonate solution was added. The mixture was mechanically stirred at 440 rpm for 15 min to uniformly mix the dispersion medium.

[0039] (2) Using 30 mL of styrene as a monomer, 0.6 g of dibenzoyl peroxide, 0.3 g of diisopropylbenzene peroxide, and 6 g of polystyrene-vinyl acetate copolymer were ultrasonically dissolved in the styrene monomer. After being uniformly mixed by ultrasonication for 15 min, the mixture was poured into the reactor containing the dispersion medium in the above step (1), and a stable suspension polymerization system was obtained by continuous mechanical mixing.

[0040] (3) The temperature of the reaction system is gradually raised to 80°C, and the reaction time is 16 hours. After the reaction is completed, the reaction system is cooled to room temperature, and the sample is centrifuged, washed with hot water, centrifuged, washed with alcohol, centrifuged and dried to obtain functionalized polystyrene composite microspheres.

[0041] Example 4

[0042] (1) At room temperature, in a three-necked flask equipped with a condenser and a mechanical stirrer, a mixed solution of 70 mL of deionized water and 30 mL of ethanol was used as the solvent, and 10 mL of a 5 wt % calcium phosphate solution was added. The mixture was mechanically stirred at 500 rpm for 20 min to uniformly mix the dispersion medium.

[0043] (2) Using 30 mL of styrene as a monomer, 0.6 g of azobisisobutyronitrile, 0.3 g of divinylbenzene, and 7.5 g of polystyrene-butadiene-styrene copolymer were ultrasonically dissolved in the styrene monomer. After being uniformly mixed by ultrasonication for 20 min, the mixture was poured into the reactor containing the dispersion medium in the above step (1), and a stable suspension polymerization system was obtained by continuous mechanical mixing.

[0044] (3) The temperature of the reaction system is gradually raised to 70°C, and the reaction time is 12 hours. After the reaction is completed, the reaction system is cooled to room temperature, and the sample is centrifuged, washed with hot water, centrifuged, washed with alcohol, centrifuged and dried to obtain functionalized polystyrene composite microspheres.

[0045] Example 5

[0046] (1) At room temperature, in a three-necked flask equipped with a condenser and a mechanical stirrer, a mixed solution of 80 mL of deionized water and 20 mL of ethanol was used as the solvent, 4 mL of a 3 wt % polyvinyl pyrrolidone solution and 4 mL of a 3 wt % magnesium hydroxide solution were added respectively, and mechanical stirring was performed at 370 rpm for 25 min to mix the dispersion medium evenly.

[0047] (2) Using 30 mL of styrene as a monomer, 0.6 g of azobisisobutyronitrile, 0.3 g of di-tert-butyl peroxide, and 10 g of polystyrene-isoprene-styrene copolymer were ultrasonically dissolved in the styrene monomer. After being uniformly mixed by ultrasonication for 25 min, the mixture was poured into the reactor containing the dispersion medium in the above step (1), and a stable suspension polymerization system was obtained by continuous mechanical mixing.

[0048] (3) The temperature of the reaction system is gradually raised to 70°C, and the reaction time is 16 hours. After the reaction is completed, the reaction system is cooled to room temperature, and the sample is centrifuged, washed with hot water, centrifuged, washed with alcohol, centrifuged and dried to obtain functionalized polystyrene composite microspheres.

[0049] The statistical results of the average particle size, coefficient of variation and functional group content of the functional composite microspheres of the above four embodiments are shown in the following table:

[0050] Example 1 Example 2 Example 3 Example 4 Example 5 Average particle size 40.12μm 89.72μm 122.63μm 160.87μm 199.75μm Coefficient of variation 8.15％ 7.71％ 6.17％ 6.42％ 6.97％ Functional group content 51.63％ 39.67％ 18.16％ 27.8％ 31.29％

[0051] The coefficient of variation reflects the monodispersity of the microspheres. The smaller the value, the more regular the particle size of the microspheres. The functional polystyrene composite microspheres prepared in Examples 1 to 5 above were tested by a laser particle size diffractometer and found to have good monodispersity, with a coefficient of variation of less than 10%. The test of the content of functional groups in the microspheres proved that the content of functional groups in the microspheres can be increased by the polymerization method, and the elements are evenly distributed in the microspheres. The immersion experiment proved that the functional groups in the microspheres are highly stable (see Figure 4 ).

[0052] The present invention adopts a "one-pot method" and can realize one-time synthesis of functionalized polystyrene composite microspheres with good dispersibility and large particle size for different purposes and different particle sizes through only one set of equipment. The selected functional polymers and / or functional monomers are cheap, non-toxic, harmless and easy to obtain. The functional group compounding principle is simple and has strong stability. The functionalization of the microspheres can be achieved through simple physical adsorption. It is found through solubility tests that the functional groups are still successfully attached to the polystyrene microspheres. Not only the preparation cost of the functionalized polystyrene composite microspheres is reduced, but also the preparation process of the micron-level functionalized polystyrene composite microspheres is simplified, which is beneficial to the subsequent promotion and application of the functionalized polystyrene composite microspheres and the realization of large-scale industrial production.

[0053] The above-described embodiments merely express the implementation methods of the present invention, but they cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for preparing functionalized polystyrene composite microspheres, characterized in that: The preparation method adopts a "one-pot method" to in-situ polymerize a styrene monomer, a functional polymer or / and a mixed system of functional monomers, and in-situ forms functionalized polystyrene composite microspheres during the formation of polystyrene microspheres; the method comprises the following steps: Step (1) using a mixed solution of deionized water and ethanol as a solvent, adding a dispersant solution to prepare a dispersion medium, and mechanically stirring to mix the mixture uniformly; Step (2) using styrene as a monomer, dissolving an initiator, a crosslinking agent, a functional polymer or / and a functional monomer in the styrene monomer, and after being uniformly mixed by ultrasonication, pouring the mixture into the mixed solution obtained in step (1), and mixing by continuous mechanical stirring to obtain a stable suspension polymerization system; Step (3) gradually raising the temperature of the reaction system to 60-80° C. for a reaction time of 8-16 hours; cooling to room temperature after the reaction, and then post-treating the sample to obtain functionalized polystyrene composite microspheres.

2. The method for preparing functionalized polystyrene composite microspheres according to claim 1, characterized in that: In step (1): In the mixed solution, the volume fraction of ethanol is 10-30%, and the rest is deionized water; The mass fraction of the dispersant solution is 1 to 5%; In the dispersion medium, the volume percentage of the dispersant is 6 to 10%; The dispersant is one or more of polyvinyl alcohol, polyvinyl pyrrolidone, hydroxypropyl methylcellulose, calcium carbonate, calcium phosphate and magnesium hydroxide.

3. The method for preparing functionalized polystyrene composite microspheres according to claim 1, characterized in that: In step (1): In the mixed solution, the volume fraction of ethanol is preferably 20%, and the rest is deionized water; The mass fraction of the dispersant solution is preferably 3%; In the dispersion medium, the volume percentage is preferably 8%; The dispersant is preferably polyvinyl alcohol.

4. The method for preparing functionalized polystyrene composite microspheres according to claim 1, characterized in that: In the step (1), the mechanical stirring speed is 300 to 500 rpm and the time is 5 to 25 min; in the step (2), the ultrasonic time is 5 to 20 min.

5. The method for preparing functionalized polystyrene composite microspheres according to claim 1, characterized in that: In the step (2): In the mixed solution, the styrene monomer accounts for 5 to 30% of the solvent volume fraction; The initiator accounts for 2-4% of the mass fraction of the styrene monomer; The cross-linking agent accounts for 1 to 3% of the mass fraction of the styrene monomer; The functional polymer and / or functional monomer accounts for 10-30% of the mass fraction of the styrene monomer.

6. The method for preparing functionalized polystyrene composite microspheres according to claim 1, characterized in that: In the step (2): In the mixed solution, the volume fraction of styrene monomer in the solvent is preferably 15%; The mass fraction of the initiator in the styrene monomer is preferably 3%; The cross-linking agent preferably accounts for 2% of the mass fraction of the styrene monomer; The mass fraction of the functional polymer and / or the functional monomer in the styrene monomer is preferably 20%.

7. The method for preparing functionalized polystyrene composite microspheres according to claim 1, characterized in that: The initiator is one or more of azobisisobutyronitrile, azobisisoheptanenitrile and benzoyl peroxide; The crosslinking agent is one or more of divinylbenzene, diisopropylbenzene peroxide, di-tert-butyl peroxide, and 2,5-dimethyl-2,5-di(tert-butylperoxide)hexane; The functional polymer or / and functional monomer is one or more of polystyrene-vinyl acetate copolymer, polystyrene-butadiene-styrene copolymer, derivatives of polystyrene-butadiene-styrene copolymer, polystyrene-isoprene-styrene copolymer, derivatives of polystyrene-isoprene-styrene copolymer, polystyrene-methyl acrylate copolymer, polylactic acid-glycolic acid copolymer, polyvinyl chloride, 4-chloromethylstyrene, 4-(N,N-diethylamino)methylstyrene, and 4-hydroxymethylstyrene.

8. The method for preparing functionalized polystyrene composite microspheres according to claim 1, characterized in that: The initiator is preferably azobisisobutyronitrile; The cross-linking agent is preferably divinylbenzene; The functional polymer and / or functional monomer are preferably polystyrene-vinyl acetate copolymer and / or 4-chloromethylstyrene.

9. The method for preparing functionalized polystyrene composite microspheres according to claim 1, characterized in that: In the step (3): The reaction temperature is preferably 70°C, and the reaction time is preferably 12h; The post-treatment comprises centrifugation, washing with hot water at 80°C, centrifugation, washing with alcohol, centrifugation and drying.

10. A functionalized polystyrene composite microsphere, characterized in that: The functionalized polystyrene composite microspheres are prepared by the preparation method described in any one of claims 1 to 9. The functionalized polystyrene composite microspheres are prepared by suspension polymerization of a styrene mixed system. The functional components are in situ copolymerized or blended throughout the polystyrene microspheres during the suspension polymerization of styrene. The particle size of the functionalized polystyrene composite microspheres is 40 to 200 μm.

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