A hierarchical porous covalent organic framework material and preparation method thereof

Abstract

The invention discloses a hierarchical porous covalent organic framework material and a preparation method thereof, belonging to the technical field of preparation of covalent organic framework materials. The covalent organic framework material is formed by condensation of aldehyde-type trimesic acid as a three-connected building unit and amino-type hydrazine hydrate linear connecting unit through Schiff base reaction; the invention synthesizes hierarchical porous COFs with large mesopores in a micellar system for the first time, and the synthesis method of the invention is simple, and there is no need to remove the template under harsh conditions later, so the structure of COFs will not be damaged. In addition, the synthesis method in the invention has a high degree of controllability, and hierarchical porous covalent organic framework materials with different pore sizes or morphologies can be synthesized by changing the amount of mesitylene added or the amount of surfactant.

Description

Technical Field

[0001] The invention belongs to the technical field of preparation of covalent organic framework materials, and in particular relates to a hierarchical porous covalent organic framework material and a preparation method thereof. Background Art

[0002] Covalent organic frameworks (COFs) have advantages such as ordered pore structure, high specific surface area, excellent chemical stability and easy functionalization, and show great potential in the fields of biomedicine, catalysis and energy storage. However, the microporous nature of traditional COFs materials poses considerable challenges to mass diffusion, which limits the full utilization of the abundant active sites in the COFs matrix. Therefore, it is of great significance to develop a method for preparing hierarchically porous COFs with intrinsic micropores and tunable mesopores.

[0003] At present, although some studies have shown that sacrificial templates can be used to construct macropores in COFs, they still face the following limitations:

[0004] (1) Among these COFs pore-forming methods, the hard template strategy is mainly used. The template removal process not only increases the complexity of the experiment, but also destroys the crystallinity of COFs.

[0005] (2) In the study of using hard templates to create pores in COFs, the pore size is basically concentrated on the macropore scale, and it is difficult to easily and simultaneously control its morphology and multi-level pore structure;

[0006] (3) The COFs synthesis process is generally carried out under harsh conditions, resulting in poor compatibility between the template and the reaction system and difficulty in matching the surface properties of the template and the precursor, which also poses great challenges to the nucleation growth kinetics and structural regulation of COFs. Summary of the invention

[0007] In order to solve the above-mentioned defects existing in the prior art, the present invention provides a hierarchical porous covalent organic framework material and a preparation method thereof. The method comprises the following steps: synthesizing COF hierarchical porous nanorods and hierarchical porous nanospheres (HPNRs, HPNSs) of different pore sizes through a condensation reaction of trimesicol and hydrazine hydrate in the presence of a surfactant; the pore size of the COF HPNRs is controllably adjusted by regulating the amount of mesitylene, and the pore size increases as the amount of mesitylene increases; the morphology of the COF hierarchical porous nanoparticles can be regulated by regulating the amount of the surfactant, and the morphology of the COF hierarchical porous nanoparticles changes from nanospheres to short nanorods and finally to longer nanorods as the amount of the surfactant increases.

[0008] The present invention is achieved through the following technical solutions:

[0009] A method for preparing a hierarchical porous covalent organic framework material comprises the following steps:

[0010] Step 1: Preparation of mixed solvent;

[0011] Mixing acetic acid, water and mesitylene in a certain proportion to obtain a mixed solvent;

[0012] Step 2: dissolving the surfactant in the mixed solvent;

[0013] Step 3: adding hydrazine hydrate and trimesaldehyde in a certain proportion to the mixed solution obtained in step 2;

[0014] Step 4: Preparation of covalent organic polymers COPs;

[0015] The mixed solution obtained in step 3 is stirred in an oil bath, and after sufficient reaction, centrifuged, washed and dried to obtain a covalent organic polymer COPs;

[0016] Step 5: Preparation of hierarchical porous covalent organic framework materials;

[0017] The covalent organic polymer COPs obtained in step 3 is added to a glass tube, an organic solvent is added, and then a catalyst is added. The glass tube is placed in liquid nitrogen for freezing, the tube is sealed with a vacuum flame, and finally placed in an oven for heating. At the end of the reaction, the solid product is collected by centrifugation and washed; the thoroughly washed product is dried under vacuum to obtain a hierarchical porous covalent organic framework material.

[0018] Furthermore, in step 1, the volume of acetic acid is 0.2-1 mL, the volume of water is 8-9.75 mL, the volume of mesitylene is 0.05-1 mL, and the total volume of the three is maintained at 10 mL.

[0019] Furthermore, in step 2, the surfactant is F127, and its mass percentage in the mixed solvent is 0.5-5 w%.

[0020] Furthermore, in step three, the molar ratio of trimesaldehyde to hydrazine hydrate is 1:3, and the molar concentration of trimesaldehyde in the mixed solvent is 10-20 mM.

[0021] Furthermore, in step 4, the temperature of the oil bath is 60-80°C, the stirring rate is 500 rpm, the reaction time is 12 h, the centrifugal speed is 4000 rpm, and the time is 3 min; the washing solvent is ethanol; and the drying temperature is 60°C.

[0022] Furthermore, in step five, the organic solvent is 1,4-dioxane, and the volume is 1 mL; the catalyst is an acetic acid aqueous solution, and the concentration of the acetic acid aqueous solution is 6 M; the heating temperature is 120 ° C, and the reaction time is 3 days.

[0023] Furthermore, in step five, the centrifugal speed is 4000 rpm and the time is 3 min; the washing solvent is 1,4-dioxane, tetrahydrofuran and acetone; and the drying temperature is 80°C.

[0024] On the other hand, the present invention also provides a hierarchical porous covalent organic framework material prepared by the above preparation method.

[0025] Compared with the prior art, the advantages of the present invention are as follows:

[0026] 1. The synthesis method of the present invention is simple and does not require harsh conditions to remove the template. In the past, the method using a hard template would inevitably destroy the structure of COFs during the template removal process.

[0027] 2. This invention synthesized hierarchical porous COFs with large mesopores in a micellar system for the first time;

[0028] 3. The synthesis method of the present invention is highly controllable. By changing the amount of mesitylene or the amount of surfactant added, hierarchical porous COFs with different pore sizes or morphologies can be synthesized. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the specific implementation of the present invention or the technical solution in the prior art, the drawings required for use in the specific implementation or the description of the prior art are briefly introduced below.

[0030] Figure 1 This is a scanned image of the COP HPNRs-5 synthesized in Example 1;

[0031] Figure 2 This is a transmission image of the COP HPNRs-5 synthesized in Example 1;

[0032] Figure 3 The powder X-ray diffraction spectra of COP HPNRs-5 synthesized in Example 1 and the monomer trimesic acid aldehyde;

[0033] Figure 4 The infrared spectra of the COP HPNRs-5 synthesized in Example 1 and the monomer trimesic acid aldehyde;

[0034] Figure 5 The powder X-ray diffraction spectra of the COF HPNRs-5 and the monomer trimesic acid aldehyde synthesized in Example 1;

[0035] Figure 6 The infrared spectra of the COF HPNRs-5 and the monomer trimesaldehyde synthesized in Example 1 are shown in FIG.

[0036] Figure 7 This is a scanned image of COP HPNRs-20 synthesized in Example 2;

[0037] Figure 8 This is a transmission image of COP HPNRs-20 synthesized in Example 2;

[0038] Fig. 9 The powder X-ray diffraction spectra of COP HPNRs-20 and monomer trimesic acid aldehyde synthesized in Example 2 are shown in FIG.

[0039] Fig.10 The infrared spectra of COP HPNRs-20 synthesized in Example 2 and the monomer trimesic acid aldehyde;

[0040] Fig.11 This is a scanned image of the COF HPNRs-20 synthesized in Example 2;

[0041] Fig.12 This is a transmission image of the COF HPNRs-20 synthesized in Example 2;

[0042] Fig.13 The powder X-ray diffraction spectra of the COF HPNRs-20 and the monomer trimesaldehyde synthesized in Example 2;

[0043] Fig.14 The infrared spectra of the COF HPNRs-20 and the monomer trimesaldehyde synthesized in Example 2 are shown in FIG.

[0044] Fig.15 The powder X-ray diffraction spectra of COP HPNRs-50 and monomer trimesic acid aldehyde synthesized in Example 3 are shown in FIG.

[0045] Fig.16 The infrared spectra of COP HPNRs-50 synthesized in Example 3 and the monomer trimesic acid aldehyde;

[0046] Fig.17 The powder X-ray diffraction spectra of the COF HPNRs-50 and the monomer trimesic acid aldehyde synthesized in Example 3;

[0047] Fig.18 The infrared spectra of the COF HPNRs-50 and the monomer trimesaldehyde synthesized in Example 3 are shown in FIG.

[0048] Fig.19 The powder X-ray diffraction spectra of COP HPNRs-100 and monomer trimesic acid aldehyde synthesized in Example 4 are shown in FIG.

[0049] Fig. 20 The infrared spectra of COP HPNRs-100 and the monomer trimesaldehyde synthesized in Example 4 are shown in FIG.

[0050] Fig.21 The powder X-ray diffraction spectra of the COF HPNRs-100 and the monomer trimesaldehyde synthesized in Example 4;

[0051] Fig. 22 The infrared spectra of the COF HPNRs-100 and the monomer trimesaldehyde synthesized in Example 4 are shown in FIG.

[0052] Fig.23 This is a scanned image of COP HPNRs-F127-70 synthesized in Example 5;

[0053] Fig.24 This is a transmission image of COP HPNRs-F127-70 synthesized in Example 5;

[0054] Fig.25 The powder X-ray diffraction spectra of COP HPNSs-F127-70 and monomer trimesic acid aldehyde synthesized in Example 5 are shown in FIG.

[0055] Fig.26 The infrared spectra of COP HPNSs-F127-70 and the monomer trimesaldehyde synthesized in Example 5 are shown in FIG.

[0056] Fig. 27 The powder X-ray diffraction spectra of the COF HPNSs-F127-70 and the monomer trimesic acid aldehyde synthesized in Example 5;

[0057] Fig.28 The infrared spectra of the COF HPNSs-F127-70 and the monomer trimesaldehyde synthesized in Example 5;

[0058] Fig.29 This is a scanned image of COP HPNRs-F127-200 synthesized in Example 6;

[0059] Fig.30 This is a transmission image of COP HPNRs-F127-200 synthesized in Example 6;

[0060] Fig.31 The powder X-ray diffraction spectra of COP HPNRs-F127-200 and monomer trimesic acid aldehyde synthesized in Example 6;

[0061] Fig.32 The infrared spectra of COP HPNRs-F127-200 and the monomer trimesaldehyde synthesized in Example 6 are shown in FIG.

[0062] Fig.33The infrared spectra of the COF HPNRs-F127-200 and the monomer trimesaldehyde synthesized in Example 6;

[0063] Fig.34 The powder X-ray diffraction spectra of COP HPNRs-F127-300 and monomer trimesic acid aldehyde synthesized in Example 7;

[0064] Fig.35 The infrared spectra of COP HPNRs-F127-300 and the monomer trimesaldehyde synthesized in Example 7 are shown in FIG.

[0065] Fig.36 This is the infrared spectra of the COF HPNRs-F127-300 synthesized in Example 7 and the monomer trimesaldehyde. DETAILED DESCRIPTION

[0066] In order to clearly and completely describe the technical solution and its specific working process of the present invention, the specific implementation methods of the present invention are as follows in conjunction with the accompanying drawings of the specification:

[0067] Example 1: This example provides a method for preparing a hierarchical porous covalent organic framework material, wherein COF HPNRs-5 is synthesized under the condition that the volume of mesitylene is 0.05 mL, and specifically comprises the following steps:

[0068] 100 mg of surfactant F127 was dissolved in a mixed solution of 0.5 mL of acetic acid, 9.5 mL of water and 0.05 mL of mesitylene, stirred for 20 min at an oil bath temperature of 60 °C and a speed of 500 rpm, then 10 μL (0.15 mmol) of hydrazine hydrate was added and continued to stir for 20 min, and finally 16.2 mg (0.1 mmol) of trimesaldehyde was added; stirred for 12 h, and after sufficient reaction, the solid product was collected by centrifugation at a speed of 4000 rpm for 3 min, washed three times with ethanol, and dried at 60 °C overnight to obtain the covalent organic polymer COP HPNRs-5. 20 mg of the covalent organic polymer prepared above was added to a glass tube, 1 mL of 1,4-dioxane was added, and then 0.1 mL of acetic acid aqueous solution (6 M) was added as a catalyst, the glass tube was frozen in liquid nitrogen, the tube was sealed with a vacuum flame, and finally heated in a 120 °C oven for 3 days. At the end of the reaction, the solid product was collected by centrifugation at 4000 rpm for 3 min, washed with 1,4-dioxane, tetrahydrofuran and acetone respectively, and the thoroughly washed product was dried at 80 °C under vacuum overnight to obtain the hierarchical porous covalent organic framework material COFHPNRs-5.

[0069] like Figure 1 Scan and Figure 2As shown in the transmission image, the COP HPNRs-5 synthesized in this example has small pores and the morphology is shorter nanorods, which proves the feasibility of the hierarchical porous material obtained by the preparation method of this example;

[0070] Figure 3 The powder X-ray diffraction spectra of COP HPNRs-5 and the monomer trimesaldehyde revealed that it was an amorphous polymer;

[0071] like Figure 4 The Fourier transform infrared spectrum of COP HPNRs-5 is shown, with the 1697 cm -1 The disappearance of the carbonyl stretching band at 1621 cm -1 The formation of C=N bonds at 100 nm proves the occurrence of polymerization reaction;

[0072] like Figure 5 The powder X-ray diffraction spectra of the synthesized COF HPNRs-5 and the monomer trimesicaldehyde can be determined that a two-dimensional covalent organic framework material with a P6 space group is successfully synthesized by the method of this embodiment;

[0073] Figure 6 The Fourier transform infrared spectra of the synthesized COF HPNRs-5 and the raw material monomers are shown in Figure 1. Compared with the monomer trimesic acid, the infrared spectrum of COF HPNRs-5 has a peak at 1625 cm -1 The characteristic stretching bands originating from the C=N bond and the monomer 1697 cm -1 The disappearance of the carbon-based stretching band at , together confirms the formation of COFs.

[0074] Example 2: This example provides a method for preparing a hierarchical porous covalent organic framework material, wherein COF HPNRs-20 is synthesized under the condition that the volume of mesitylene is 0.2 mL, and specifically comprises the following steps:

[0075] 100 mg of surfactant F127 was dissolved in a mixed solution of 0.5 mL of acetic acid, 9.5 mL of water and 0.2 mL of mesitylene, stirred for 20 min at an oil bath temperature of 60 °C and a speed of 500 rpm, then 10 μL (0.15 mmol) of hydrazine hydrate was added and stirring continued for 20 min, and finally 16.2 mg (0.1 mmol) of trimesic acid was added. After stirring for 12 h and sufficient reaction, the solid product was collected by centrifugation at a speed of 4000 rpm for 3 min, washed three times with ethanol, and dried at 60 °C overnight to obtain the covalent organic polymer product COP HPNRs-20. 20 mg of the covalent organic polymer prepared above was added to a glass tube, 1 mL of 1,4-dioxane was added, and then 0.1 mL of acetic acid aqueous solution (6 M) was added as a catalyst, the glass tube was frozen in liquid nitrogen, the tube was sealed with a vacuum flame, and finally heated in a 120 °C oven for 3 days. At the end of the reaction, the solid product was collected by centrifugation at 4000 rpm for 3 min, washed with 1,4-dioxane, tetrahydrofuran and acetone respectively, and the thoroughly washed product was dried at 80 °C under vacuum overnight to obtain the hierarchical porous covalent organic framework material COFHPNRs-20.

[0076] like Figure 7 Scan and Figure 8 As shown in the transmission image, the morphology of COP HPNRs-20 synthesized in this example is still a short rod, and the pore size is significantly larger than that of COP HPNRs-5, indicating that the pore size can be increased with the increase of the amount of mesitylene;

[0077] Fig. 9 The powder X-ray diffraction spectra of COP HPNRs-20 and the monomer trimesaldehyde revealed that it was an amorphous polymer;

[0078] like Fig.10 Shown are the Fourier transform infrared spectra of COP HPNRs-20 and raw material monomers, proving the occurrence of polymerization reaction;

[0079] like Fig.11 Scan and Fig.12 As shown in the transmission image, the pore structure and morphology of the COF HPNRs-20 synthesized in this example are retained after recrystallization;

[0080] like Fig.13 The powder X-ray diffraction spectra of the COF HPNRs-20 and the monomer trimesic acid aldehyde synthesized in this example can confirm that a two-dimensional covalent organic framework material with good crystallinity is successfully synthesized by the method of the present invention;

[0081] Fig.14The Fourier transform infrared spectra of the COF HPNRs-20 and the raw material monomers synthesized in this example confirm the formation of COFs.

[0082] Example 3: This example provides a method for preparing a hierarchical porous covalent organic framework material, wherein COF HPNRs-50 is synthesized under the condition that the volume of mesitylene is 0.5 mL, comprising the following steps:

[0083] 100 mg of surfactant F127 was dissolved in a mixed solution of 0.5 mL of acetic acid, 9.5 mL of water and 0.5 mL of mesitylene, stirred at an oil bath temperature of 60 °C and a speed of 500 rpm for 20 min, then 10 μL (0.15 mmol) of hydrazine hydrate was added and stirring continued for 20 min, and finally 16.2 mg (0.1 mmol) of trimesaldehyde was added. After stirring for 12 h and sufficient reaction, the solid product was collected by centrifugation at a speed of 4000 rpm for 3 min, washed three times with ethanol, and dried at 60 °C overnight to obtain the covalent organic polymer product COP HPNRs-50. 20 mg of the covalent organic polymer prepared above was added to a glass tube, 1 mL of 1,4-dioxane was added, and then 0.1 mL of acetic acid aqueous solution (6 M) was added as a catalyst, the glass tube was frozen in liquid nitrogen, the tube was sealed with a vacuum flame, and finally heated in a 120 °C oven for 3 days. At the end of the reaction, the solid product was collected by centrifugation at 4000 rpm for 3 min, washed with 1,4-dioxane, tetrahydrofuran and acetone respectively, and the thoroughly washed product was dried at 80 °C under vacuum overnight to obtain the hierarchical porous covalent organic framework material COFHPNRs-50.

[0084] Fig.15 The powder X-ray diffraction spectra of COP HPNRs-50 and the monomer trimesaldehyde revealed that it was an amorphous polymer;

[0085] like Fig.16 Shown are the Fourier transform infrared spectra of COP HPNRs-50 and raw material monomers, proving the occurrence of polymerization reaction;

[0086] like Fig.17 The powder X-ray diffraction spectra of the COF HPNRs-50 and the monomer trimesic acid aldehyde synthesized in this example can confirm that the two-dimensional covalent organic framework material with good crystallinity is successfully synthesized by the method of the present invention;

[0087] Fig.18 The Fourier transform infrared spectra of the COF HPNRs-50 and the raw material monomer synthesized in this example confirm the formation of COFs.

[0088] Example 4: This example provides a method for preparing a hierarchical porous covalent organic framework material, wherein COF HPNRs-100 is synthesized under the condition that the volume of mesitylene is 1 mL, comprising the following steps:

[0089] 100 mg of surfactant F127 was dissolved in a mixed solution of 0.5 mL of acetic acid, 9.5 mL of water and 1 mL of mesitylene, stirred for 20 min at an oil bath temperature of 60 °C and a speed of 500 rpm, then 10 μL (0.15 mmol) of hydrazine hydrate was added and stirring continued for 20 min, and finally 16.2 mg (0.1 mmol) of trimesic acid was added. After stirring for 12 h and sufficient reaction, the solid product was collected by centrifugation at a speed of 4000 rpm for 3 min, washed three times with ethanol, and dried at 60 °C overnight to obtain the covalent organic polymer product COP HPNRs-100. 20 mg of the covalent organic polymer prepared above was added to a glass tube, 1 mL of 1,4-dioxane was added, and then 0.1 mL of acetic acid aqueous solution (6 M) was added as a catalyst, the glass tube was frozen in liquid nitrogen, the tube was sealed with a vacuum flame, and finally heated in a 120 °C oven for 3 days. At the end of the reaction, the solid product was collected by centrifugation at 4000 rpm for 3 min, washed with 1,4-dioxane, tetrahydrofuran and acetone respectively, and the thoroughly washed product was dried at 80 °C under vacuum overnight to obtain the hierarchical porous covalent organic framework material COFHPNRs-100.

[0090] Fig.19 The powder X-ray diffraction spectra of COP HPNRs-100 and the monomer trimesaldehyde revealed that it was an amorphous polymer;

[0091] like Fig. 20 Shown are the Fourier transform infrared spectra of COP HPNRs-100 and raw material monomers, proving the occurrence of polymerization reaction;

[0092] like Fig.21 The powder X-ray diffraction spectra of the COF HPNRs-100 and the monomer trimesic acid aldehyde synthesized in this embodiment can confirm that a two-dimensional covalent organic framework material with good crystallinity is successfully synthesized by the method of this embodiment;

[0093] Fig. 22 The Fourier transform infrared spectra of the COF HPNRs-100 and the raw material monomers synthesized in this example confirm the formation of COFs.

[0094] Example 5: This example provides a method for preparing a hierarchical porous covalent organic framework material, wherein COF HPNSs-F127-70 is synthesized under the condition that the mass of the surfactant is 70 mg, comprising the following steps:

[0095] 70 mg of surfactant F127 was dissolved in a mixed solution of 0.5 mL of acetic acid, 9.5 mL of water and 0.2 mL of mesitylene, stirred for 20 min at an oil bath temperature of 60 °C and a speed of 500 rpm, then 10 μL (0.15 mmol) of hydrazine hydrate was added and stirring continued for 20 min, and finally 16.2 mg (0.1 mmol) of trimesic acid was added. After stirring for 12 h and sufficient reaction, the solid product was collected by centrifugation at a speed of 4000 rpm for 3 min, washed three times with ethanol, and dried at 60 °C overnight to obtain the covalent organic polymer product COP HPNSs-F127-70. 20 mg of the covalent organic polymer prepared above was added to a glass tube, 1 mL of 1,4-dioxane was added, and then 0.1 mL of acetic acid aqueous solution (6 M) was added as a catalyst, the glass tube was frozen in liquid nitrogen, the tube was sealed with a vacuum flame, and finally heated in a 120 °C oven for 3 days. At the end of the reaction, the solid product was collected by centrifugation at 4000 rpm for 3 min, washed with 1,4-dioxane, tetrahydrofuran and acetone respectively, and the thoroughly washed product was dried at 80 °C under vacuum overnight to obtain the hierarchical porous covalent organic framework material COFHPNSs-F127-70.

[0096] like Fig.23 Scan and Fig.24 As shown in the transmission image, the morphology of COP HPNSs-F127-70 synthesized in this example is spherical, and the pore structure still exists, indicating that the morphology of the material can be changed by changing the amount of surfactant;

[0097] Fig.25 The powder X-ray diffraction spectra of COP HPNSs-F127-70 and the monomer trimesaldehyde revealed that it was an amorphous polymer;

[0098] like Fig.26 Shown are the Fourier transform infrared spectra of COP HPNSs-F127-70 and raw monomers, proving the occurrence of polymerization reaction;

[0099] like Fig. 27 The powder X-ray diffraction spectra of the COF HPNSs-F127-70 and the monomer trimesic acid aldehyde synthesized in this embodiment can confirm that a two-dimensional covalent organic framework material with good crystallinity is successfully synthesized by the method of this embodiment;

[0100] Fig.28 The Fourier transform infrared spectra of the COF HPNSs-F127-70 and the raw material monomer synthesized in this example confirm the formation of COFs.

[0101] Example 6: This example provides a method for preparing a hierarchical porous covalent organic framework material, wherein COF HPNSs-F127-200 is synthesized under the condition that the mass of the surfactant is 200 mg, comprising the following steps:

[0102] 200 mg of surfactant F127 was dissolved in a mixed solution of 0.5 mL of acetic acid, 9.5 mL of water and 0.2 mL of mesitylene, stirred for 20 min at an oil bath temperature of 60 °C and a speed of 500 rpm, then 10 μL (0.15 mmol) of hydrazine hydrate was added and stirring continued for 20 min, and finally 16.2 mg (0.1 mmol) of trimesic acid was added. After stirring for 12 h and sufficient reaction, the solid product was collected by centrifugation at a speed of 4000 rpm for 3 min, washed three times with ethanol, and dried at 60 °C overnight to obtain the covalent organic polymer product COP HPNRs-F127-200. 20 mg of the covalent organic polymer prepared above was added to a glass tube, 1 mL of 1,4-dioxane was added, and then 0.1 mL of acetic acid aqueous solution (6 M) was added as a catalyst, the glass tube was frozen in liquid nitrogen, the tube was sealed with a vacuum flame, and finally heated in a 120 °C oven for 3 days. At the end of the reaction, the solid product was collected by centrifugation at 4000 rpm for 3 min, washed with 1,4-dioxane, tetrahydrofuran and acetone respectively, and the thoroughly washed product was dried at 80 °C under vacuum overnight to obtain the hierarchical porous covalent organic framework material COF HPNRs-F127-200.

[0103] like Fig.29 Scan and Fig.30 As shown in the transmission image, the morphology of COP HPNRs-F127-200 synthesized in this example is longer nanorods, which become thinner than COPHPNRs-20, and the pore structure still exists, indicating that the morphology of the material can be changed by changing the amount of surfactant;

[0104] Fig.31 The powder X-ray diffraction spectra of COP HPNRs-F127-200 and the monomer trimesaldehyde revealed that it was an amorphous polymer;

[0105] like Fig.32 Shown are the Fourier transform infrared spectra of COP HPNRs-F127-200 and raw material monomers, proving the occurrence of polymerization reaction;

[0106] Fig.33 The Fourier transform infrared spectra of the COF HPNRs-F127-200 and the raw material monomer synthesized in the example confirm the formation of COFs.

[0107] Example 7: This example provides a method for preparing a hierarchical porous covalent organic framework material, wherein COF HPNSs-F127-300 is synthesized under the condition that the mass of the surfactant is 300 mg, comprising the following steps:

[0108] 300 mg of surfactant F127 was dissolved in a mixed solution of 0.5 mL of acetic acid, 9.5 mL of water and 0.2 mL of mesitylene, stirred for 20 min at an oil bath temperature of 60 °C and a speed of 500 rpm, then 10 μL (0.15 mmol) of hydrazine hydrate was added and continued to stir for 20 min, and finally 16.2 mg (0.1 mmol) of trimesic acid was added. After stirring for 12 h and sufficient reaction, the solid product was collected by centrifugation at a speed of 4000 rpm for 3 min, washed three times with ethanol, and dried at 60 °C overnight to obtain the covalent organic polymer product COP HPNRs-F127-300. 20 mg of the covalent organic polymer prepared above was added to a glass tube, 1 mL of 1,4-dioxane was added, and then 0.1 mL of acetic acid aqueous solution (6 M) was added as a catalyst, the glass tube was frozen in liquid nitrogen, the tube was sealed with a vacuum flame, and finally heated in a 120 °C oven for 3 days. At the end of the reaction, the solid product was collected by centrifugation at 4000 rpm for 3 min, washed with 1,4-dioxane, tetrahydrofuran and acetone respectively, and the thoroughly washed product was dried at 80 °C under vacuum overnight to obtain the hierarchical porous covalent organic framework material COF HPNRs-F127-300.

[0109] Fig.34 The powder X-ray diffraction spectra of COP HPNRs-F127-300 and the monomer trimesaldehyde revealed that it was an amorphous polymer;

[0110] like Fig.35 The Fourier transform infrared spectra of COP HPNRs-F127-300 and raw monomers are shown, proving the occurrence of polymerization reaction;

[0111] Fig.36 The Fourier transform infrared spectra of the COF HPNRs-F127-300 and the raw material monomer synthesized in this example confirm the formation of COFs.

[0112] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0113] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0114] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preparing a hierarchical porous covalent organic framework material, characterized in that: The specific steps include: Step 1: Preparation of mixed solvent; Mixing acetic acid, water and mesitylene in a certain proportion to obtain a mixed solvent; Step 2: dissolving the surfactant in the mixed solvent; Step 3: adding hydrazine hydrate and trimesaldehyde in a certain proportion to the mixed solution obtained in step 2; Step 4: Preparation of covalent organic polymers COPs; The mixed solution obtained in step 3 is stirred in an oil bath, and after sufficient reaction, centrifuged, washed and dried to obtain a covalent organic polymer COPs; Step 5: Preparation of hierarchical porous covalent organic framework materials; The covalent organic polymer COPs obtained in step 3 is added to a glass tube, an organic solvent is added, and then a catalyst is added, the glass tube is placed in liquid nitrogen for freezing, the tube is sealed by evacuating a vacuum flame, and finally placed in an oven for heating. At the end of the reaction, the solid product is collected by centrifugation and washed; the thoroughly washed product is dried under vacuum to obtain a hierarchical porous covalent organic framework material; In step 2, the surfactant is F127, and the mass percentage in the mixed solvent is 0.5-5w%; In step 5, the organic solvent is 1,4-dioxane, the volume is 1 mL; the catalyst is acetic acid aqueous solution, the concentration of acetic acid aqueous solution is 6 M; the heating temperature is 120° C., and the reaction time is 3 days; In step 1, the volume of acetic acid is 0.2-1 mL, the volume of water is 8-9.75 mL, and the volume of mesitylene is 0.05-1 mL, and the total volume of the three is maintained at 10 mL; In step 3, the molar ratio of trimesaldehyde to hydrazine hydrate is 1:3, and the molar concentration of trimesaldehyde in the mixed solvent is 10-20 mM.

2. The method for preparing a hierarchical porous covalent organic framework material according to claim 1, characterized in that: In step 4, the temperature of the oil bath is 60-80°C, the stirring rate is 500 rpm, the reaction time is 12 hours, the centrifugal speed is 4000 rpm, the time is 3 minutes, the washing solvent is ethanol, and the drying temperature is 60°C.

3. The method for preparing a hierarchical porous covalent organic framework material according to claim 1, characterized in that: In step 5, the centrifugal speed is 4000 rpm and the time is 3 min; the washing solvent is 1,4-dioxane, tetrahydrofuran and acetone; and the drying temperature is 80°C.

4. A hierarchical porous covalent organic framework material, characterized in that: The method is prepared by any one of claims 1 to 3.

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