Monodisperse conjugated microporous polymer microsphere with controllable particle size and preparation method of monodisperse conjugated microporous polymer microsphere

Abstract

The invention relates to the technical field of high polymer materials, in particular to a monodisperse conjugated microporous polymer microsphere with controllable particle size and a preparation method thereof, and the method comprises the following steps: dissolving two organic framework building elements containing amino and aldehyde in an organic solvent, adding an acetic acid solution with proper concentration, uniformly mixing, standing at room temperature for reaction, filtering, washing, and drying to obtain the monodisperse conjugated microporous polymer microsphere with controllable particle size. And after the reaction is finished, centrifugally collecting a yellow precipitation product, and washing and drying in vacuum to obtain the conjugated microporous polymer microspheres. The preparation method disclosed by the invention is simple and convenient, does not need excessive process operation, can be carried out at room temperature, avoids large energy consumption caused by preparation by a conventional solvothermal method, saves a large amount of production cost, is high in monomer conversion rate, controllable in particle size and good in monodispersity, and can be applied to the fields of gas absorption, heterogeneous catalysis and the like.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to a monodisperse conjugated microporous polymer microsphere with controllable particle size and a preparation method thereof. Background Art

[0002] Conjugated microporous polymers (CMPs) are a class of attractive organic porous materials. Their structural characteristics are that they are composed of many CC bonds and aromatic rings connected to each other, forming a conjugated system and inherent nanopores, with high specific surface area, good stability, and precisely controllable micropore size and volume. CMPs not only have the compositional advantages of rich building blocks, diverse synthetic strategies, high tunability of skeleton structure, and easy functional modification, but also have an extended conjugated system in structure, which can construct functional porous materials at the molecular level, and can chemically change CMPs according to the target application, and finely adjust the function in the ever-changing environment and needs.

[0003] Spherical CMPs usually have a uniform pore structure and a high specific surface area, which allows gas molecules to enter and diffuse into the polymer more effectively, thereby improving adsorption efficiency. In addition, the spherical CMP structure will be more stable and can extend the service life. As the particle size of CMP microspheres decreases, it helps to form a more uniform and dense pore size, and the specific surface area will increase significantly, providing more adsorption sites, increasing the adsorption capacity and efficiency of gas molecules, and has great application potential in the field of gas adsorption. Journal of CO2 Utilization, 2022, 58:101924. CMPs microspheres were prepared using pyrrole and terephthalaldehyde as raw materials by the solvothermal method, but the CMPs microspheres were bonded and had different particle sizes; Journal of Colloid and Interface Science, 2024, 675:1091-1099. A solvothermal method was introduced to prepare CMPs microspheres at 60°C using F127 surfactant, m-phenylenediamine, and tetrachloro-1,4-benzoquinone. The role of F127 is to form micelles and then guide oligomers to form microspheres. Compared with the solvothermal method that requires high temperature, the reaction temperature is also mild, but the prepared microspheres still have different particle sizes, and the excess F127 must be thermally removed later, which is cumbersome.

[0004] At present, the synthesis and preparation of CMPs microspheres mostly use the solvothermal method, which will face the problems of high energy consumption and high production cost in practical applications. There are few reports on the preparation of CMPs under mild conditions and the controllable and uniform particle size of microspheres. Therefore, we invented a method for preparing CMPs microspheres at room temperature with controllable particle size. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing conjugated microporous polymer microspheres (CMPs) in view of the deficiencies of the prior art. Two organic framework building blocks containing amino groups and aldehyde groups are used as raw materials, dissolved in an organic solvent, and the Schiff base reaction of amino groups and aldehyde groups is used. Only a small amount of acetic acid is added as a catalyst to enable the reaction to proceed rapidly at room temperature. The operation is simple, no additional heating is required, a large amount of cost is saved, and the post-processing is simple. Another purpose of the present invention is to provide a method for regulating the particle size of conjugated microporous polymer microspheres based on the above-mentioned preparation method of conjugated microporous polymer microspheres, and microspheres of different particle sizes are prepared by adding different amounts of organic acids. In addition, the microspheres will not stick to each other and are uniform in size, that is, the monodispersity is good.

[0006] To achieve the above object, the present invention provides a method for preparing monodisperse conjugated microporous polymer microspheres with controllable particle size, which comprises the following steps:

[0007] S1, adding two organic backbone building blocks containing amino group and aldehyde group with molecular structures shown in the following formula (1) and formula (2) to an organic solvent, dissolving them by ultrasonication at room temperature, adding catalyst acetic acid after dissolution and mixing, and reacting at room temperature;

[0008]

[0009] In the formula, R1 is selected from one of triazine, nitrogen atom, and benzene ring; R2 is selected from one of hydrogen, hydroxyl, vinyl, methyl, ethyl, methoxy, and ethynyloxy;

[0010] S2. After the reaction is completed at room temperature, the yellow precipitate product is collected by centrifugation at 8000-12000 r / min using a high-speed centrifuge, washed multiple times with tetrahydrofuran and anhydrous ethanol, and dried in vacuo to obtain a conjugated microporous polymer microsphere solid powder of the following formula (3);

[0011]

[0012] In the formula, R1 and R2 are the same as those in formula (1) and formula (2).

[0013] As a further preferred technical solution of the present invention, the amino-containing organic skeleton building block is selected from any one of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, tris(4-aminophenyl)amine, and 1,3,5-tris(4-aminophenyl)benzene.

[0014] As a further preferred technical solution of the present invention, the aldehyde-containing organic skeleton building unit is selected from any one of terephthalaldehyde, 2,5-dihydroxyterephthalaldehyde, 2,5-divinylterephthalaldehyde, 2,5-dimethylterephthalaldehyde, 2,5-diethylterephthalaldehyde, 2,5-dimethoxybenzene-1,4-dicarboxaldehyde, and 2,5-diethynyloxyterephthalaldehyde.

[0015] As a further preferred technical solution of the present invention, the molar ratio of the aldehyde-containing organic backbone building unit to the aldehyde-containing organic backbone building unit is 2:3; and / or the molar ratio of the organic solvent to the aldehyde-containing organic backbone building unit is 50-110:1, and the volume ratio of the catalyst acetic acid to the organic solvent is 2-5:50.

[0016] As a further preferred technical solution of the present invention, the organic solvent is one or more of acetonitrile, dimethyl sulfoxide, mesitylene, and dioxane.

[0017] As a further preferred technical solution of the present invention, the concentration of the catalyst acetic acid is 1 to 12 mol / L, and more preferably 6 mol / L.

[0018] As a further preferred technical solution of the present invention, in step S1, after the catalyst acetic acid is added, a vortex oscillator is used to oscillate and mix evenly.

[0019] As a further preferred technical solution of the present invention, in step S1, the reaction is carried out at room temperature in a static manner, the temperature is 15-35° C., and the time is 24-84 hours.

[0020] As a further preferred technical solution of the present invention, in step S2, vacuum drying is performed in a vacuum drying oven at a temperature of 60-65° C. for 12-24 hours.

[0021] The present invention also provides a conjugated microporous polymer microsphere, which is prepared by the above method.

[0022] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0023] (1) The preparation method provided by the present invention is simple and convenient, does not require excessive process operations, and the reaction can be carried out at room temperature, avoiding the large amount of energy consumption caused by the previous solvent thermal preparation method, thereby saving a large amount of production costs.

[0024] (2) The conjugated microporous polymer microspheres (CMPs) prepared by the present invention have high monomer conversion rate, controllable particle size, and good monodispersity, and can be applied to the fields of gas absorption, heterogeneous catalysis, etc.

[0025] (3) In the preparation method of the present invention, the particle size of the CMPs microspheres can be regulated by adding different amounts of acetic acid solution. The acetic acid not only plays a role in catalyzing the reaction, but also changes the solubility of the CMPs microspheres in the solvent system, thereby achieving the regulation of the particle size of the CMPs microspheres.

[0026] (4) The acetic acid catalyst used in the preparation system of the present invention is green and environmentally friendly, and the organic solvent for dissolving the monomer can also be recovered, purified and reused, thereby achieving green synthesis. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0028] Figure 1 This is a scanning electron microscope image of the conjugated microporous polymer microspheres in Example 1.

[0029] Figure 2 This is a scanning electron microscope image of the conjugated microporous polymer microspheres in Example 2.

[0030] Figure 3 This is a scanning electron microscope image of the conjugated microporous polymer microspheres in Example 3.

[0031] Figure 4 This is a scanning electron microscope image of the conjugated microporous polymer microspheres in Example 4.

[0032] Figure 5 This is a scanning electron microscope image of the conjugated microporous polymer microspheres in Example 5.

[0033] Figure 6 This is the infrared spectrum of the conjugated microporous polymer microspheres in Example 5.

[0034] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings in conjunction with the embodiments. DETAILED DESCRIPTION

[0035] The specific implementation of the present invention is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the present invention.

[0036] Unless otherwise defined, the technical terms used in the following examples have the same meanings as those generally understood by those skilled in the art to which the present invention belongs. The test reagents used in the following examples, unless otherwise specified, are all conventional biochemical reagents; the experimental methods, unless otherwise specified, are all conventional methods.

[0037] Embodiment 1:

[0038] 1) According to the molar ratio of the two organic skeleton building blocks containing amino groups and aldehyde groups of 2:3, weigh 0.06mmol (about 21.26mg) of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 0.09mmol (about 17.12mg) of 2,5-diethylterephthalaldehyde, put the weighed sample into a 20mL centrifuge tube, use a pipette to take 10.0mL of dimethyl sulfoxide solvent and add it to the centrifuge tube, then cover the centrifuge tube and wrap the tube mouth with a sealing film, use ultrasonic treatment at room temperature until the sample is completely dissolved in the solvent, then use a pipette to take 0.4mL of 6mol / L acetic acid and add it to the centrifuge tube, also wrap the tube mouth with a sealing film, use a vortex oscillator to vigorously oscillate to mix the solution in the centrifuge tube evenly, at this time, it can be observed that the solution changes from clear to light yellow, and stand at room temperature 25°C for 48h.

[0039] 2) After the reaction at room temperature is completed, a high-speed centrifuge is used to centrifuge at 10000r / min for 10 minutes to collect the yellow precipitate product, the upper layer solution is removed, and the collected yellow precipitate product is washed 3 times with tetrahydrofuran and anhydrous ethanol respectively, the washed yellow precipitate product is put into a culture dish, sealed with a plastic wrap and pierced with several holes, and placed in a vacuum drying oven at 65°C for 24 hours to remove the residual solvent, and a conjugated microporous polymer microsphere solid powder is obtained. The conversion rate is 96.1%, which is the ratio of the mass of the monomer before the reaction to the mass of the product after the reaction.

[0040] The scanning electron microscope image of the conjugated microporous polymer microspheres obtained in this example is as follows: Figure 1 As shown, it can be seen that the microspheres do not stick to each other and are uniform in size, that is, the monodispersity is good, and the average particle size is 780.4nm.

[0041] Embodiment 2:

[0042] 1) According to the molar ratio of the two organic skeleton building blocks containing amino groups and aldehyde groups of 2:3, weigh 0.06mmol (about 21.26mg) of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 0.09mmol (about 17.12mg) of 2,5-diethylterephthalaldehyde, put the weighed sample into a 20mL centrifuge tube, use a pipette to take 10.0mL of dimethyl sulfoxide solvent and add it to the centrifuge tube, then cover the centrifuge tube and wrap the tube mouth with a sealing film, use ultrasonic treatment at room temperature until the sample is completely dissolved in the solvent, then use a pipette to take 0.5mL of 6mol / L acetic acid and add it to the centrifuge tube, also wrap the tube mouth with a sealing film, use a vortex oscillator to vigorously oscillate to mix the solution in the centrifuge tube evenly, at this time, it can be observed that the solution changes from clear to light yellow, and stand at room temperature 25°C for 48h.

[0043] 2) After the reaction at room temperature is completed, the yellow precipitate product is collected by centrifugation at 10000r / min for 10 minutes in a high-speed centrifuge, and the upper solution is removed. The collected yellow precipitate product is washed three times with tetrahydrofuran and anhydrous ethanol respectively, and the washed yellow precipitate product is placed in a culture dish, sealed with a plastic wrap and pierced with several holes, and placed in a vacuum drying oven at 65°C for 24 hours to remove residual solvents, etc., to obtain a conjugated microporous polymer microsphere solid powder. The conversion rate is 96.4%.

[0044] The scanning electron microscope image of the conjugated microporous polymer microspheres obtained in this example is as follows: Figure 2 As shown, it can be seen that the microspheres do not stick together and are uniform in size, that is, they have good monodispersity, and the average particle size is 648.2nm.

[0045] Embodiment 3:

[0046] 1) According to the molar ratio of the two organic skeleton building blocks containing amino groups and aldehyde groups of 2:3, weigh 0.06mmol (about 21.26mg) of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 0.09mmol (about 17.12mg) of 2,5-diethylterephthalaldehyde, put the weighed sample into a 20mL centrifuge tube, use a pipette to take 10.0mL of dimethyl sulfoxide solvent and add it to the centrifuge tube, then cover the centrifuge tube and wrap the tube mouth with a sealing film, use ultrasonic treatment at room temperature until the sample is completely dissolved in the solvent, then use a pipette to take 0.7mL of 6mol / L acetic acid and add it to the centrifuge tube, also wrap the tube mouth with a sealing film, use a vortex oscillator to vigorously oscillate to mix the solution in the centrifuge tube evenly, at this time, it can be observed that the solution changes from clear to light yellow, and stand at room temperature 25°C for 48h.

[0047] 2) After the reaction at room temperature is completed, the yellow precipitate product is collected by centrifugation at 10000r / min for 10 minutes in a high-speed centrifuge, and the upper solution is removed. The collected yellow precipitate product is washed three times with tetrahydrofuran and anhydrous ethanol respectively, and the washed yellow precipitate product is placed in a culture dish, sealed with a plastic wrap and pierced with several holes, and placed in a vacuum drying oven at 65°C for 24 hours to remove residual solvents, etc., to obtain a conjugated microporous polymer microsphere solid powder. The conversion rate is 97.2%.

[0048] The scanning electron microscope image of the conjugated microporous polymer microspheres obtained in this example is as follows: Figure 3 As shown, it can be seen that the microspheres do not stick to each other and are uniform in size, that is, they have good monodispersity, and the average particle size is 280.7nm.

[0049] Embodiment 4:

[0050] 1) According to the molar ratio of the two organic skeleton building blocks containing amino groups and aldehyde groups of 2:3, weigh 0.06mmol (about 21.26mg) of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine and 0.09mmol (about 17.12mg) of 2,5-diethylterephthalaldehyde, put the weighed sample into a 20mL centrifuge tube, use a pipette to take 10.0mL of dimethyl sulfoxide solvent and add it to the centrifuge tube, then cover the centrifuge tube and wrap the tube mouth with a sealing film, use ultrasonic treatment at room temperature until the sample is completely dissolved in the solvent, then use a pipette to take 1.0mL of 6mol / L acetic acid and add it to the centrifuge tube, also wrap the tube mouth with a sealing film, use a vortex oscillator to vigorously oscillate to mix the solution in the centrifuge tube evenly, at this time, it can be observed that the solution changes from clear to yellow, and stand at room temperature 25°C for 48h.

[0051] 2) After the reaction at room temperature is completed, the yellow precipitate is collected by centrifugation at 10000r / min for 10 minutes in a high-speed centrifuge, and the upper solution is removed. The collected yellow precipitate product is washed three times with tetrahydrofuran and anhydrous ethanol respectively, and the washed yellow precipitate product is placed in a culture dish, sealed with a plastic wrap and pierced with several holes, and placed in a vacuum drying oven at 65°C for 24 hours to remove residual solvents, etc., to obtain a conjugated microporous polymer microsphere solid powder. The conversion rate is 97.5%.

[0052] The scanning electron microscope image of the conjugated microporous polymer microspheres obtained in this example is as follows: Figure 4 As shown, it can be seen that the microspheres do not stick to each other and are uniform in size, that is, they have good monodispersity, and the average particle size is 253.6nm.

[0053] In the above examples 1-4, when 6 mol / L acetic acid was added from 0.4 mL to 1.0 mL, the particle size of the prepared microspheres decreased from 780.4 nm to 253.6 nm, and the conversion rate increased from 96.1% to 97.5%. It can be seen that as the amount of acetic acid increases, the conversion rate of the organic skeleton building unit monomers gradually increases, the particle size of the microspheres decreases, and the particle size is controllable. Among them, Example 4 has the highest monomer conversion rate and the smallest microsphere particle size, which is the best embodiment of the present invention.

[0054] In the present invention, the particle size of the microspheres is reduced and the specific surface area is increased, which can effectively increase the adsorption efficiency. Moreover, based on the fact that the triazine group contains a large number of nitrogen atoms, it not only enhances the polarity but also provides abundant active sites, making it easier to adsorb polar gas molecules and gas molecules that can form hydrogen bonds and coordination bonds with nitrogen atoms. The conjugated microporous polymer microspheres can exhibit a strong gas adsorption capacity.

[0055] Comparative Example 1:

[0056] As a control experiment of Example 4, the same preparation method as Example 4 was adopted, except that no acetic acid catalyst was added to the reaction system. As a result, the reaction failed to proceed completely, the conversion rate was only 47.3%, and the prepared conjugated microporous polymer was irregular in shape, not spherical, and the particle size was uneven.

[0057] Embodiment 5:

[0058] 1) According to the molar ratio of two organic framework building blocks containing amino groups and aldehyde groups of 2:3, weigh 0.06mmol (about 17.42mg) of tri(4-aminophenyl)amine and 0.09mmol (about 14.95mg) of 2,5-dihydroxyterephthalaldehyde, put the weighed sample into a 20mL centrifuge tube, use a pipette to take 10.0mL of dimethyl sulfoxide solvent and add it to the centrifuge tube, then cover the centrifuge tube and wrap the tube mouth with a sealing film, use ultrasonic treatment at room temperature until the sample is completely dissolved in the solvent, then use a pipette to take 0.5mL of 6mol / L acetic acid and add it to the centrifuge tube, also wrap the tube mouth with a sealing film, use a vortex oscillator to vigorously oscillate to mix the solution in the centrifuge tube evenly, at this time, it can be observed that the solution changes from clear to light yellow, and stand at room temperature 25°C for 48h.

[0059] 2) After the reaction at room temperature is completed, the yellow precipitate product is collected by centrifugation at 10000r / min for 10 minutes in a high-speed centrifuge, the upper solution is removed, and the collected yellow precipitate product is washed 3 times with tetrahydrofuran and anhydrous ethanol respectively. The washed yellow precipitate product is placed in a culture dish, sealed with a plastic wrap and pierced with several holes, and placed in a vacuum drying oven at 65°C for 24 hours to remove residual solvents, etc., to obtain a conjugated microporous polymer microsphere solid powder. The conversion rate is 95.8%.

[0060] The scanning electron microscope image of the conjugated microporous polymer microspheres obtained in this example is as follows: Figure 5 As shown, it can be seen that the microspheres are not bonded to each other and are uniform in size, that is, they have good monodispersity and an average particle size of 623.5nm. Figure 6 As shown, it can be seen at 1602cm -1 The characteristic absorption peak of -C=N bond is found on the left and right, and the absorption peak intensity is very high, 2340cm -1 It was found that the characteristic peak of -CHO basically disappeared, 3382cm -1 On the left and right are broad peaks of the hydroxyl groups on the side groups, and no double peaks of primary amines were found, which indicates the successful synthesis of conjugated microporous polymer microspheres.

[0061] Although specific embodiments of the present invention are described above, those skilled in the art should understand that these are merely examples and that various changes or modifications may be made to the embodiments without departing from the principles and essence of the present invention. The scope of protection of the present invention is limited only by the appended claims.

Claims

1. A method for preparing monodisperse conjugated microporous polymer microspheres with controllable particle size, characterized in that: The following steps are involved: S1, adding two organic backbone building blocks containing amino group and aldehyde group of molecular structure shown in the following formula (1) and formula (2) to an organic solvent, dissolving them by ultrasonication at room temperature, adding catalyst acetic acid to mix well, and reacting at room temperature; In the formula, R1 is selected from one of triazine, nitrogen atom, and benzene ring; R2 is selected from one of hydrogen, hydroxyl, vinyl, methyl, ethyl, methoxy, and ethynyloxy; S2. After the reaction is completed at room temperature, a high-speed centrifuge is used to centrifuge at 8000-12000 r / min to collect the yellow precipitate product, and the yellow precipitate product is washed and vacuum dried to obtain a conjugated microporous polymer microsphere solid powder of the following formula (3); In the formula, R1 and R2 are the same as those in formula (1) and formula (2).

2. The method for preparing monodisperse conjugated microporous polymer microspheres with controllable particle size according to claim 1, characterized in that: The amino-containing organic backbone building block is selected from any one of 2,4,6-tris(4-aminophenyl)-1,3,5-triazine, tris(4-aminophenyl)amine and 1,3,5-tris(4-aminophenyl)benzene.

3. The method for preparing monodisperse conjugated microporous polymer microspheres with controllable particle size according to claim 1, characterized in that: The aldehyde-containing organic skeleton building block is selected from any one of terephthalaldehyde, 2,5-dihydroxyterephthalaldehyde, 2,5-divinylterephthalaldehyde, 2,5-dimethylterephthalaldehyde, 2,5-diethylterephthalaldehyde, 2,5-dimethoxybenzene-1,4-dicarboxaldehyde, and 2,5-diethynyloxyterephthalaldehyde.

4. The method for preparing monodisperse conjugated microporous polymer microspheres with controllable particle size according to claim 1, characterized in that: The molar ratio of the organic backbone building unit containing aldehyde groups to the organic backbone building unit containing aldehyde groups is 2:3; and / or the molar ratio of the organic solvent to the organic backbone building unit containing aldehyde groups is 50-110:1, and the volume ratio of acetic acid to the organic solvent is 2-5:

50.

5. The method for preparing monodisperse conjugated microporous polymer microspheres with controllable particle size according to claim 1, characterized in that: The organic solvent is one or more of acetonitrile, dimethyl sulfoxide, mesitylene and dioxane.

6. The method for preparing monodisperse conjugated microporous polymer microspheres with controllable particle size according to claim 1, characterized in that: The concentration of the catalyst acetic acid is 1 to 12 mol / L.

7. The method for preparing monodisperse conjugated microporous polymer microspheres with controllable particle size according to claim 1, characterized in that: In step S1, after adding the catalyst acetic acid, a vortex oscillator is used to oscillate and mix evenly.

8. The method for preparing monodisperse conjugated microporous polymer microspheres with controllable particle size according to claim 1, characterized in that: In step S1, the reaction is carried out at room temperature in a static manner, the temperature is 15-35° C., and the time is 24-84 hours.

9. The method for preparing monodisperse conjugated microporous polymer microspheres with controllable particle size according to claim 1, characterized in that: In step S2, vacuum drying is performed in a vacuum drying oven at a temperature of 60-65° C. for 12-24 h.

10. A conjugated microporous polymer microsphere, characterized in that: The method is prepared by any one of claims 1 to 9.

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