A covalent triazine polymer material and a method of making the same

Abstract

The application discloses a preparation method of a covalent triazine polymer material and belongs to the technical field of polymer material synthesis. The covalent triazine polymer material is prepared by adopting a one-pot method, dispersing an aldehyde-based compound and an inorganic ammonium salt in an organic solvent in proportion, and reacting under a Lewis acid catalyst. The synthesis method is simple and efficient, the condition is mild, a complex synthesis process is not needed, and the material is easy to prepare in a large amount, so that large-scale production is expected to be realized.

Description

Technical Field

[0001] This invention belongs to the field of polymer material preparation technology, specifically relating to a covalent triazine polymer material and its preparation method. Background Technology

[0002] Covalent triazine polymers are an important branch of porous organic materials and have been widely used in catalysis, adsorption, energy storage and other fields.

[0003] In 2008, Thomas et al. first used ZnCl2 as a catalyst to obtain CTFs via cyano trimerization in a closed system under high temperature (>400℃) using an ionothermal method. The product had a high specific surface area, but the high reaction temperature of this method led to partial carbonization of the material. In 2012, Cooper et al. used trifluoromethanesulfonic acid as a catalyst to polymerize cyano monomers at low temperature to obtain CTFs. The CTFs obtained by this method retained the intrinsic band structure of the material and had strong application prospects in the field of photocatalysis. However, the specific surface area was low, and the strong acid conditions easily corroded the equipment, which was not conducive to large-scale production. In addition, the monomers containing heteroatoms had low reactivity. In 2017, Tan Bi'en et al. synthesized covalent triazine polymer materials (CTF-HUSTs) with good band structure and high specific surface area by reacting aldehyde monomers and amidine monomers under relatively mild conditions. Subsequently, the research group further expanded the monomer range of CTFs by using corresponding monomers such as benzyl alcohol, benzylamine, and benzyl bromide to replace the aldehyde group in the reaction with amidine, thereby improving the crystallinity of the materials. However, the amidine monomers used in this method are derived from cyano monomers, and the synthesis process of amidine monomers is complex, increasing the cost and time required for synthesis.

[0004] It can be seen that the CTFs synthesized by the above methods all use cyano compounds (or their derivatives) as nitrogen sources, have limited monomer types, and require harsh synthesis conditions or complex processes, which cannot meet the needs of practical applications. Therefore, it is of great significance to develop a synthesis method that uses inexpensive and readily available raw materials, operates under mild conditions, and is easy to mass-produce. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the present invention aims to provide a covalent triazine polymer material and its preparation method, so as to solve the technical problems that the existing synthesis methods must use cyano compounds as nitrogen sources, that is, the types of monomers are limited, and the synthesis conditions are harsh and the reaction process is complex.

[0006] To achieve the above objectives, the present invention employs the following technical solution:

[0007] This invention provides a method for preparing covalent triazine polymers (one-pot method), in which a dialdehyde compound or a polyaldehyde compound, an inorganic ammonium salt, an organic solvent and a Lewis acid catalyst are mixed evenly and reacted at 40℃~200℃ for 24~120h. After separation and purification, the covalent triazine polymer is obtained.

[0008] Preferably, the aldehyde compounds preferred in this invention are dialdehyde or polyaldehyde aromatic compounds, including aromatic aldehyde compounds such as terephthalaldehyde; branched polyaldehyde aromatic compounds such as tris(4-formylphenyl)amine; and monomers with special functional groups such as tetrafluoroterephthalaldehyde.

[0009] Preferably, the inorganic ammonium salt is ammonium chloride, ammonium sulfate, ammonium nitrate, ammonium carbonate, ammonium iodide, ammonium bromide, etc.

[0010] More preferably, since the above-mentioned inorganic ammonium salt is easily decomposed under heating, the amount of ammonium salt has an important influence on the reaction yield and the specific surface area of ​​the product. Therefore, the amount of ammonium salt is 1.2 to 2 times the molar amount of aldehyde group.

[0011] Preferably, the organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dioxane, dimethyl sulfoxide, chlorobenzene, o-dichlorobenzene, mesitylene, xylene, and toluene.

[0012] More preferably, considering factors such as the solvent's solubility in monomers and intermediates in the reaction process, the preferred solvents are a mixture of o-dichlorobenzene and mesitylene, or a mixture of o-dichlorobenzene and benzene, which can yield polymer products with both high specific surface area and high yield.

[0013] The Lewis acid catalyst is one or more of the following: copper chloride, copper acetate, ferric chloride, ferric sulfate, ferric nitrate, ferric trifluoromethanesulfonate, ferric acetate, and ferric citrate.

[0014] More preferably, when the catalyst is ferric acetate, the resulting polymer has the highest specific surface area.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] This invention proposes a method for preparing covalent triazine polymers with high monomer versatility. A one-pot method is employed, reacting a dialdehyde or polyaldehyde compound with an inexpensive and readily available inorganic ammonium salt under mild conditions to obtain the covalent triazine polymer. Using the inorganic ammonium salt as the nitrogen source for the covalent triazine polymer avoids the use of highly toxic cyano monomers and the synthesis of complex amidine monomers. The proposed synthesis method is simple, efficient, and operates under mild conditions, requiring no complex synthesis process and facilitating the large-scale preparation of materials, thus promising the potential for large-scale production.

[0017] Furthermore, the preparation method of the present invention has good monomer adaptability, and it is easy to prepare functional covalent triazine polymers, such as fluorinated covalent triazine polymers, by selecting appropriate types of reactive monomers.

[0018] Furthermore, the Lewis acid catalyst used in this invention is one or more of copper chloride, copper acetate, ferric chloride, ferric sulfate, ferric nitrate, ferric trifluoromethanesulfonate, ferric acetate, and ferric citrate, which has a low cost. Attached Figure Description

[0019] Figure 1 This is a schematic diagram illustrating the mechanism of synthesizing covalent triazine polymers according to the present invention;

[0020] Figure 2 This is a schematic diagram of the synthesis scheme of the covalent triazine polymer of the present invention;

[0021] Figure 3 The infrared spectrum of the covalent triazine polymer CTF-1 synthesized in Example 1 of this invention is shown.

[0022] Figure 4 The covalent triazine polymer CTF-1 synthesized in Example 1 of this invention 13 C solid-state NMR spectrum;

[0023] Figure 5 This is a scanning electron microscope image of the covalent triazine polymer CTF-1 synthesized in this invention.

[0024] Figure 6 The image shows the 77K nitrogen adsorption-desorption curve of the covalent triazine polymer CTF-1 synthesized in Example 1 of this invention.

[0025] Figure 7 The infrared spectrum of the covalent triazine polymer CTF-TPA synthesized in Example 2 of this invention is shown.

[0026] Figure 8 The covalent triazine polymer CTF-TPA synthesized in Example 2 of this invention 13 C solid-state NMR spectrum;

[0027] Figure 9 This is a scanning electron microscope image of the covalent triazine polymer CTF-TPA synthesized in this invention.

[0028] Figure 10 The image shows the nitrogen adsorption-desorption curve at 77K for the covalent triazine polymer CTF-TPA synthesized in Example 2 of this invention.

[0029] Figure 11 The infrared spectrum of the highly fluorinated covalent triazine polymer CTF-TF synthesized in Example 3 of this invention is shown.

[0030] Figure 12 The highly fluorinated covalent triazine polymer CTF-TF synthesized in Example 3 of this invention 13 C solid-state NMR spectrum;

[0031] Figure 13 This is a scanning electron microscope image of the highly fluorinated covalent triazine polymer CTF-TF synthesized in this invention.

[0032] Figure 14 The nitrogen adsorption-desorption curve at 77K for the highly fluorinated covalent triazine polymer CTF-TF synthesized in Example 3. Detailed Implementation

[0033] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0034] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0035] The present invention will now be described in further detail with reference to the accompanying drawings:

[0036] The method for preparing covalent triazine polymers provided by the present invention involves dispersing a dialdehyde compound or a polyaldehyde compound with an inorganic ammonium salt in a solvent, reacting the mixture at 40°C to 200°C for 24 to 120 hours in the presence of a Lewis acid catalyst, and then separating and purifying the mixture to obtain the covalent triazine polymer.

[0037] In this invention, after the reaction is completed, vacuum filtration is generally performed using a Buchner funnel to obtain an upper filter cake. The filter cake is then washed multiple times with N,N-dimethylformamide, dilute hydrochloric acid, ethanol, and deionized water to remove unreacted monomers and residual Lewis acid catalysts and solvents. Finally, the filter cake is freeze-dried to obtain a yellow powder sample.

[0038] This invention explores and reasones about the mechanism of the above-mentioned preparation method, using terephthalaldehyde as a monomer as an example to illustrate the reaction mechanism of this invention, such as... Figure 1 As shown, aldehydes first react with ammonium salts to form imine A, while the catalyst (Fe)... 3+ Oxygen I - I₂ is generated, and the imine intermediate is oxidized by I₂ to give intermediate B. Imine A and intermediate B undergo a condensation reaction to give the desired product.

[0039] Therefore, by selecting appropriate monomers and reaction conditions, the above preparation method can be used to prepare a product containing multiple functional groups with a specific surface area of ​​50–500 m². 2 / g of covalent triazine polymer.

[0040] When ferric acetate is used as the catalyst, the resulting polymer has the highest specific surface area. Therefore, ferric acetate is used as the catalyst in all embodiments of this invention.

[0041] The following are specific implementation examples of the present invention:

[0042] Example 1

[0043] 0.134 g of terephthalaldehyde, 0.35 g of ammonium iodide, and 0.10 g of ferric acetate were added to 10 mL of a mixed solvent of o-dichlorobenzene and mesitylene (V:V = 4:1), and reacted at 120 °C and 160 °C for 48 h each. After the reaction was complete, the mixture was filtered and then washed three times with 50 mL of N,N-dimethylformamide, dilute hydrochloric acid, ethanol, and deionized water to remove residual oligomers and catalyst. The resulting solid was freeze-dried to obtain product CTF-1, with a yield of 87%. The structural formula of the synthesized product CTF-1 is as follows:

[0044]

[0045] Figure 3 , Figure 4 , Figure 5 and Figure 6 The infrared spectra of CTF-1, the product of Example 1, are respectively. 13 The solid-state NMR spectrum, scanning electron microscope image, and nitrogen adsorption-desorption curves are shown below. Figure 3 1512cm -1 and 1352cm -1 The absorption peaks at points 1 and 2 are the stretching vibration absorption peaks of C=N and CN in the triazine ring, respectively. Figure 4 The peak at 170 ppm is the C peak of the triazine ring, and the carbon signals at 128.7 ppm and 138.8 ppm are the carbon signals of the benzene ring. Figure 6 This indicates that CTF-1 is predominantly microporous, with a specific surface area of ​​approximately 327 m². 2 / g.

[0046] Example 2

[0047] 0.165 g of tris(4-formylphenyl)amine, 0.35 g of ammonium iodide, and 0.15 g of ferric chloride were added to 10 mL of a mixed solvent of o-dichlorobenzene and benzene (V:V = 4:1). The reaction was carried out at 80 °C for 24 h and then at 120 °C for 72 h. After the reaction was completed, the mixture was filtered, then washed three times with 150 mL of dilute hydrochloric acid, then three times with 150 mL of acetone, and finally three times with 150 mL of N,N-dimethylformamide to remove residual oligomers and catalyst. The resulting solid was extracted with tetrahydrofuran using a Soxhlet extractor for 24 h and dried under vacuum to obtain the product CTF-TPA in 75% yield. The structural formula of the synthesized product CTF-TPA is as follows:

[0048]

[0049] Figure 7 , Figure 8 , Figure 9 and Figure 10 The infrared spectra of the product of Example 2 are respectively: 13 C solid NMR spectrum, scanning electron microscope image, and nitrogen adsorption-desorption curve, among which Figure 7 1520cm -1 and 1361cm -1 The absorption peaks at these locations represent the stretching vibrations of the C=N and CN bonds in the triazine ring, respectively. Figure 8 The peak at 170 ppm corresponds to the carbon atom in the triazine ring, the peak at 150.8 ppm corresponds to the carbon atom directly bonded to nitrogen in the triphenylamine structure, and the peak at 130.3 ppm originates from the benzene ring structure. Figure 10 This indicates that CTF-TPA is mainly composed of micropores, with a specific surface area of ​​approximately 341 m². 2 / g.

[0050] Example 3

[0051] 0.103 g of tetrafluoroterephthalaldehyde, 0.32 g of ammonium iodide, and 0.1 g of ferric trifluoromethanesulfonate were added to 10 mL of a mixed solvent of o-dichlorobenzene and benzene (V:V = 2:3). The reaction was carried out at 80 °C for 24 h and then at 120 °C for 56 h. After the reaction was completed, the mixture was filtered, then washed three times with 150 mL of dilute hydrochloric acid, followed by three washes with 150 mL of N,N-dimethylformamide to remove residual oligomers and catalyst. The resulting solid was extracted with tetrahydrofuran using a Soxhlet extractor for 24 h and dried under vacuum to obtain the product CTF-TF in 83% yield. The structural formula of the synthesized product CTF-TF is as follows:

[0052]

[0053] Figure 11 , Figure 12 , Figure 13 and Figure 14 The infrared spectra of CTF-TF, the product of Example 3, are shown below. 13 C solid NMR spectrum, scanning electron microscope image, and nitrogen adsorption-desorption curve, among which Figure 11 1523cm -1 and 1355cm -1 The absorption peaks at points 1 and 2 are the stretching vibration absorption peaks of C=N and CN in the triazine ring, respectively. Figure 12 The peak at 159 ppm corresponds to the carbon atom in the triazine ring, the peaks in the range of 130 ppm to 145 ppm correspond to the carbon atoms in the fluorinated benzene ring, and the peak at 119 ppm corresponds to the carbon atoms attached to the triazine ring. Figure 14 This indicates that CTF-TF is mainly composed of micropores, with a specific surface area of ​​approximately 407 m². 2 / g.

[0054] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A method for preparing a covalent triazine polymer material, characterized in that, A one-pot method was used to disperse aldehyde compounds and inorganic ammonium salts in an organic solvent in a certain proportion under mild conditions, and then react them under a Lewis acid catalyst to prepare covalent triazine polymer materials. The mild conditions are a reaction at 40℃~200℃ for 24~120 h; The aldehyde compound is terephthalaldehyde, tris(4-formylphenyl)amine, or tetrafluoroterephthalaldehyde; the inorganic ammonium salt is ammonium iodide. The Lewis acid catalyst is ferric acetate. The amount of the inorganic ammonium salt used is 1.2 to 2 times the molar amount of the aldehyde group in the aldehyde compound.

2. The method for preparing the covalent triazine polymer material according to claim 1, characterized in that, The organic solvent is one or more of N,N-dimethylformamide, N,N-dimethylacetamide, dioxane, dimethyl sulfoxide, chlorobenzene, o-dichlorobenzene, mesitylene, xylene, and toluene.

3. The method for preparing the covalent triazine polymer material according to claim 2, characterized in that, The organic solvent is a mixture of o-dichlorobenzene and mesitylene, or a mixture of o-dichlorobenzene and benzene.

4. A covalent triazine polymer material prepared by the preparation method according to any one of claims 1 to 3, characterized in that, Compounds with the following structure: 。

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