COF-based hydrogel based on long-chain modified aldehyde group monomer as well as preparation method and application of COF-based hydrogel

Abstract

The invention provides COF-based hydrogel based on a long-chain modified aldehyde group monomer as well as a preparation method and application of the COF-based hydrogel, and relates to the technical field of hydrogel for water treatment. The preparation method comprises the following steps: synthesizing a required TPAD-NHBoc amido monomer by using medicines such as 1, 4, 5, 8-tetrachloroanthraquinone, N-Boc-1, 4-phenylenediamine and the like, sequentially adding the TPAD-NHBoc amido monomer, a Dha aldehyde monomer modified by different long chains, dioxane and trifluoroacetic acid into a glass tube according to a certain proportion, carrying out ultrasonic treatment and stirring to fully dissolve, and finally putting the mixture into a reaction kettle to react, thereby obtaining the TPAD-NHBoc amido monomer. After the reaction is finished and cooling, carefully taking out the blocky gel from the glass tube, respectively immersing the blocky gel into dioxane, DMF, acetone, methanol and deionized water, and repeatedly replacing the solvent to wash unreacted monomers and impurities to obtain the hydrogel. The COF-based hydrogel based on the long-chain modified aldehyde group monomer has excellent solar photo-thermal water evaporation performance.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydrogel for water treatment, in particular to a COF-based hydrogel based on long-chain modified aldehyde monomers and a preparation method and application thereof. BACKGROUND

[0002] With the increasingly serious global water shortage problem, solar-driven interfacial water evaporation technology is considered as a promising solution for seawater desalination and wastewater purification due to its high efficiency, low energy consumption and environmental protection. The core of this technology is to develop high-performance photothermal evaporation materials, which can locally limit solar energy at the gas-liquid interface and efficiently convert it into heat energy, thereby achieving rapid water evaporation.

[0003] In recent years, various porous composite materials (carbon nanotubes, graphene, polypyrrole, polydopamine chitosan) have been developed to improve solar-driven interfacial evaporation, however, for such composite systems, there may be defects such as disordered and non-uniform pore structure, limited loading capacity of photothermal components affecting efficiency, easy swelling of structure to damage vapor escape channels, and difficult to accurately control the chemical properties such as hydrophilic and hydrophobic properties. Covalent organic framework (COF) material is a kind of crystalline porous material with periodic pore structure formed by covalent bonding of organic structural units. Due to its high specific surface area, adjustable pore structure, excellent structural stability and easy functional modification, COF material has great application potential in the field of interfacial evaporation. SUMMARY

[0004] In view of this, the present application provides a COF-based hydrogel based on long-chain modified aldehyde monomers and a preparation method and application thereof. The present application uses 2,5-dihydroxyterephthaldehyde (Dha) as raw material, utilizes the hydroxyl active site to react with different chain length aliphatic primary bromoalkane, respectively obtains Dha-EO2 and Dha-Cx series derivatives, and further synthesizes COF-based hydrogel by reacting with TPAD-NHBoc amine monomer, which helps to develop the next generation of efficient and customizable COF evaporation materials.

[0005] The technical scheme of the present application is as follows: A preparation method of a COF-based hydrogel based on long-chain modified aldehyde monomers, comprising the following steps: S1, dissolve 1,4,5,8-tetrachloro-9,10-anthracenedione, tert-butyl N-(4-aminophenyl) carbamate and Cs2CO3 in toluene, then add Pd2(dba)3 and 2,2'-bis(diphenylphosphino)-1,1'-binaphthalene, stir the reaction solution and cool the reaction solution, filter the residue, dry the residue to obtain residue solid, soak the obtained residue solid in water and stir, continue to filter the residue, dry the residue in vacuum, then dissolve the residue in tetrahydrofuran, filter the filtrate, and purify the filtrate by column chromatography to obtain TPAD-NHBoc amine monomer; S2, add 2,5-dihydroxyterephthaldehyde and potassium carbonate to N,N-dimethylformamide, stir, then add bromoalkane dropwise, heat, quench with water, extract with dichloromethane, dry the combined organic layers over anhydrous magnesium sulfate, filter the filtrate, and purify the filtrate by column chromatography to obtain Dha aldehyde monomer; S3, add TPAD-NHBoc amine monomer and Dha aldehyde monomer to a glass tube, then add dioxane and water to the glass tube and ultrasonically stir, then add trifluoroacetic acid and place the glass tube in a reaction kettle to react, cool to room temperature after the reaction is completed, and take out the block-shaped gel; S4, soak the block-shaped gel in a solvent and wash to obtain the target hydrogel.

[0006] Further, in step S1, the mass ratio of 1,4,5,8-tetrachloro-9,10-anthracenedione, tert-butyl N-(4-aminophenyl) carbamate, Cs2CO3, Pd2(dba)3, and 2,2'-bis(diphenylphosphino)-1,1'-binaphthalene is 1.0-1.2:3.5-3.8:7.6-7.9:0.10-0.15:0.30-0.35.

[0007] Further, in step S1, the mass ratio of 1,4,5,8-tetrachloro-9,10-anthracenedione, tert-butyl N-(4-aminophenyl) carbamate, Cs2CO3, Pd2(dba)3, and 2,2'-bis(diphenylphosphino)-1,1'-binaphthalene is 1.04:3.75:7.8:0.11:0.33; and the toluene is dry toluene.

[0008] Further, in step S1, the stirring reaction temperature is 110-120°C, and the stirring reaction time is 46-50h.

[0009] Further, in step S1, the stirring reaction temperature is 110°C, and the stirring reaction time is 48h.

[0010] Further, in step S1, the stirring time is 8-12h.

[0011] Further, in step S2, the mass ratio of 2,5-dihydroxyterephthaldehyde, potassium carbonate, and bromoalkane is 0.4-0.6:1.5-1.8:1.2-2.0; the ratio of the amount of 2,5-dihydroxyterephthaldehyde to N,N-dimethylformamide is 0.4-0.6 g:30-40 mL; and the heating is carried out at 100-105°C for 46-48 h under a nitrogen atmosphere.

[0012] Further, in step S2, the mass ratio of 2,5-dihydroxyterephthaldehyde, potassium carbonate, and bromoalkane is 0.498:1.742:1.2-2.0.

[0013] Further, the ratio of the amount of 2,5-dihydroxyterephthaldehyde to N,N-dimethylformamide is 498 mg:35 mL.

[0014] Further, the heating is carried out at 100°C for 48 h under a nitrogen atmosphere.

[0015] Further, in step S3, the bromoalkane is selected from one or more of 1-bromo-2-(2-methoxyethoxy)ethane, 1-bromoheptane, 1-bromododecane, and 1-bromooctadecane.

[0016] Further, in step S3, the mass ratio of TPAD-NHBoc amine monomer to Dha aldehyde monomer is 88-98:28-127; the mass-volume ratio of TPAD-NHBoc amine monomer to dioxane is 88-98 mg:4.8-5.4 mL; and the volume ratio of dioxane, water, and trifluoroacetic acid is 5-5.5:0.88-0.97:0.088-0.097.

[0017] Further, the ratio of the amount of TPAD-NHBoc amine monomer to dioxane is 93 mg:5.1 mL.

[0018] Further, the volume ratio of dioxane, water, and trifluoroacetic acid is 5.1:0.9:0.09.

[0019] Further, when the bromoalkane is selected from 1-bromo-2-(2-methoxyethoxy)ethane, the Dha-EO2 aldehyde monomer is prepared in step S2, and the mass ratio of TPAD-NHBoc amine monomer to Dha-EO2 aldehyde monomer is 88-98:28-31.

[0020] Further, when the bromoalkane is selected from 1-bromoheptane, the Dha-C7 aldehyde monomer is prepared in step S2, and the mass ratio of TPAD-NHBoc amine monomer to Dha-EO2 aldehyde monomer is 88-98:64-70.

[0021] Further, when the bromoalkane is selected from 1-bromododecane, Dha-C is prepared in step S2 12 aldehyde monomer, the mass ratio of the TPAD-NHBoc amine monomer to the Dha-EO2 aldehyde monomer is 88-98:85-94.

[0022] Further, when the bromoalkane is selected from 1-bromododecane, Dha-C is prepared in step S2 18 aldehyde monomer, the mass ratio of the TPAD-NHBoc amine monomer to the Dha-EO2 aldehyde monomer is 88-98:85-94.

[0023] Further, in step S3, the glass tube has a size of an outer diameter of 22-25 mm, an inner diameter of 18-20 mm, and a height of 30-35 mm; the volume of the reaction kettle is 25-30 mL; and the ultrasonic stirring time is 10-12 min.

[0024] Further, in step S4, the soaking time is 24-26 h, and the solvent is replaced 3-4 times during the soaking process; the solvent is selected from one or more of dioxane, DMF, acetone, methanol, and water.

[0025] A COF-based hydrogel based on a long-chain modified aldehyde monomer is prepared by the preparation method.

[0026] Further, the COF-based hydrogel based on the long-chain modified aldehyde monomer has a structural formula as shown in the following formula I: Formula I, In formula I, R is selected from an alkoxy group or an oxyether group.

[0027] Further, in formula I, R is selected from an alkoxy group or an oxyether group.

[0028] Further, in formula I, R is selected from a C7-C18 alkoxy group.

[0029] Application of the COF-based hydrogel based on the long-chain modified aldehyde monomer in interfacial water evaporation.

[0030] Compared with the prior art, the present application has the following beneficial effects: The COF material grafted with oxyether long chains and alkane long chains having different lengths and chemical properties is designed and synthesized innovatively, a flexible side chain having different chain lengths and chemical properties is constructed in the COF channel, the structure is accurate at the molecular level, the COF-based hydrogel prepared by the present application has good water transmission and evaporation, has excellent solar light-heat water evaporation performance, and can effectively remove pollutants in water, thereby providing a good material for obtaining fresh water resources. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 The NMR spectrum of the Dha-EO2 aldehyde monomer is shown in the form of a hydrogen NMR spectrum.

[0032] Figure 2 The image shows the 1H NMR spectrum of the Dha-C7 aldehyde monomer. Figure 3 The NMR spectrum of the Dha-C12 aldehyde monomer is shown in the 1H NMR spectrum.

[0033] Figure 4 The NMR spectrum of the Dha-C18 aldehyde monomer is shown in the 1H NMR spectrum.

[0034] Figure 5 The infrared spectra of the hydrogels prepared in Examples 1-4 and Comparative Example 1 are shown.

[0035] Figure 6 The images are scanning electron microscope (SEM) images of the hydrogels prepared in Examples 1-4 and Comparative Example 1.

[0036] Figure 7 The X-ray diffraction patterns are of the hydrogels prepared in Examples 1-4 and Comparative Example 1.

[0037] Figure 8 The contact angle diagrams are for the hydrogels prepared in Examples 1-4 and Comparative Example 1.

[0038] Figure 9 The images show water wetting test results of the hydrogels prepared in Examples 1-4 and Comparative Example 1.

[0039] Figure 10 The above are the powder temperature rise diagrams of the hydrogels prepared in Examples 1-4 and Comparative Example 1.

[0040] Figure 11 The graph shows the change in water evaporation mass of the hydrogels prepared in Examples 1-4 and Comparative Example 1.

[0041] Figure 12 Raman images of the hydrogels prepared in Examples 1-4 and Comparative Example 1.

[0042] Figure 13 This is a diagram showing the seawater evaporation of TPAD-Dha-EO2 in Example 1.

[0043] Figure 14 This is a diagram showing the purification of organic polluted water by TPAD-Dha-EO2 in Example 1. Detailed Implementation

[0044] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0045] Unless otherwise specified, the experimental methods used in the embodiments of this application are all conventional methods.

[0046] In the following examples and comparative examples, unless otherwise specified, all raw materials can be prepared by commercial purchase or conventional methods.

[0047] According to the aldehyde monomers used, these are named TPAD-Dha-EO2, TPAD-Dha-C7, TPAD-Dha-C12, and TPAD-Dha-C18, respectively.

[0048] The overnight time of this invention is 8-12 hours.

[0049] Example 1 The preparation method of hydrogel TPAD-Dha-EO2 includes the following steps: S1. 1,4,5,8-Tetrachloro-9,10-anthradinone (1.04 g, 3.00 mmol), tert-butyl N-(4-aminophenyl)carbamate (3.75 g, 18.00 mmol) and Cs2CO3 (7.80 g, 24.00 mmol) were dissolved in 50 mL of dry toluene and dissolved under an argon atmosphere. After argon bubbling for 20 minutes, Pd2(dba)3 (110 mg, 4% mol) and 2,2'-bis(diphenylphosphine)-1,1'-dinaphthalene (BINAP, 330 mg, 12% mol) were added and stirred at 110 °C for 48 h. The reaction solution was cooled, filtered, and the filter residue was dried. The obtained filter residue solid was soaked in water and stirred overnight. The filter residue was collected by filtration and vacuum dried. The filter residue was then dissolved in tetrahydrofuran and filtered. The obtained filtrate was purified by column chromatography by rotary evaporation to obtain TPAD-NHBoc amino monomer. S2. 2,5-Dihydroxyterephthalaldehyde (498 mg, 3 mmol) and potassium carbonate (1.742 g, 12.6 mmol) were added to 35 mL of LDM and stirred for 30 minutes. Then, 1-bromo-2-(2-methoxyethoxy)ethane (1.373 g, 7.5 mmol) was slowly added dropwise. The resulting mixture was heated at 100 °C for 48 h under a nitrogen atmosphere, quenched with 35 mL of water, and then extracted with dichloromethane. The combined organic layers were dried on anhydrous magnesium sulfate. The filtrate was purified by column chromatography after rotary evaporation to obtain the Dha-EO2 aldehyde monomer. S3. Add 93 mg (0.09 mmol) of TPAD-NHBoc amine monomer and 30 mg (0.18 mmol) of Dha-EO2 aldehyde monomer to a glass tube (size: outer diameter 22 mm, inner diameter 18 mm, height 35 mm, bottom sealed). S4. Add 5.1 mL of dioxane and 0.9 mL of deionized water to the glass tube of S3, sonicate for 10 min, stir to fully dissolve the monomer, add 90 μL of trifluoroacetic acid, and then place in a 25 mL reactor and react at 120 °C for 120 h. S5. After the reaction is complete, the reactor is cooled to room temperature. The block gel is carefully removed from the glass tube and immersed in dioxane for 24 hours. The unreacted monomers and other impurities are washed off 3-4 times with fresh solvent. S6. Replace the dioxane in step S5 with DMF, methanol, acetone, and deionized water respectively, soak for 24 hours, and wash 3-4 times with fresh solvents in between to obtain hydrogel, denoted as TPAD-Dha-EO2.

[0050] Example 2 The preparation method of hydrogel TPAD-Dha-C7 includes the following steps: S1. 1,4,5,8-Tetrachloro-9,10-anthradinone (1.04 g, 3.00 mmol), tert-butyl N-(4-aminophenyl)carbamate (3.75 g, 18.00 mmol) and Cs2CO3 (7.80 g, 24.00 mmol) were dissolved in 50 mL of dry toluene under an argon atmosphere. After argon bubbling for 20 minutes, Pd2(dba)3 (110 mg, 4% mol) and 2,2'-bis(diphenylphosphine)-1,1'-dinaphthalene (BINAP, 330 mg, 12% mol) were added. The mixture was stirred at 110 °C for 48 h. The reaction solution was cooled, filtered, and the filter residue was dried. The obtained filter residue solid was soaked in water and stirred overnight. The filter residue was collected by filtration and vacuum dried. The filter residue was then dissolved in tetrahydrofuran and filtered. The filtrate was purified by column chromatography by rotary evaporation to obtain TPAD-NHBoc amino monomer. S2. 2,5-Dihydroxyterephthalaldehyde (498 mg, 3 mmol) and potassium carbonate (1.742 g, 12.6 mmol) were added to 35 mL of LDM and stirred for 30 minutes. Then, 1-bromoheptane (1.344 g, 7.5 mmol) was slowly added dropwise. The resulting mixture was heated at 100 °C for 48 h under a nitrogen atmosphere, quenched with 35 mL of water, and then extracted with dichloromethane. The combined organic layers were dried on anhydrous magnesium sulfate. The filtrate was purified by column chromatography after rotary evaporation to obtain the Dha-C7 aldehyde monomer. S3. Add 93 mg (0.09 mmol) of TPAD-NHBoc amine monomer and 67 mg (0.18 mmol) of Dha-C7 aldehyde monomer to a glass tube (dimensions: outer diameter 22 mm, inner diameter 18 mm, height 35 mm, bottom sealed). S4. Add 5.1 mL of dioxane and 0.9 mL of deionized water to the glass tube of S3, sonicate for 10 min, stir to fully dissolve the monomer, add 90 μL of trifluoroacetic acid, and then place in a 25 mL reactor and react at 120 °C for 120 h. S5. After the reaction is complete, the reactor is cooled to room temperature. The block gel is carefully removed from the glass tube and immersed in dioxane for 24 hours. The unreacted monomers and other impurities are washed off 3-4 times with fresh solvent. S6. Replace the dioxane in step S5 with DMF, methanol, acetone, and deionized water respectively, soak for 24 hours, and wash 3-4 times with fresh solvents in between to obtain hydrogel, denoted as TPAD-Dha-C7.

[0051] Example 3 Hydrogel TPAD-Dha-C 12 The preparation method includes the following steps: S1. 1,4,5,8-Tetrachloro-9,10-anthradinone (1.04 g, 3.00 mmol), tert-butyl N-(4-aminophenyl)carbamate (3.75 g, 18.00 mmol) and Cs2CO3 (7.80 g, 24.00 mmol) were dissolved in 50 mL of dry toluene under an argon atmosphere. After argon bubbling for 20 minutes, Pd2(dba)3 (110 mg, 4% mol) and 2,2'-bis(diphenylphosphine)-1,1'-dinaphthalene (BINAP, 330 mg, 12% mol) were added. The mixture was stirred at 110 °C for 48 h. The reaction solution was cooled, filtered, and the filter residue was dried. The obtained filter residue solid was soaked in water and stirred overnight. The filter residue was collected by filtration and vacuum dried. The filter residue was then dissolved in tetrahydrofuran and filtered. The filtrate was purified by column chromatography by rotary evaporation to obtain TPAD-NHBoc amino monomer. S2. 2,5-Dihydroxyterephthalaldehyde (498 mg, 3 mmol) and potassium carbonate (1.742 g, 12.6 mmol) were added to 35 mL of LDM and stirred for 30 minutes. Then, 1-bromododecane (1.870 g, 7.5 mmol) was slowly added dropwise. The resulting mixture was heated at 100 °C for 48 h under a nitrogen atmosphere, quenched with 35 mL of water, and then extracted with dichloromethane. The combined organic layers were dried on anhydrous magnesium sulfate, and the filtrate was purified by column chromatography after rotary evaporation to obtain Dha-C. 12 Aldehyde monomers; S3, 93 mg (0.09 mmol) of TPAD-NHBoc amino monomer and 90 mg (0.18 mmol) of Dha-C 12 Aldehyde monomers are added to a glass tube (dimensions: outer diameter 22mm, inner diameter 18mm, height 35mm, bottom sealed); S4. Add 5.1 mL of dioxane and 0.9 mL of deionized water to the glass tube of S3, sonicate for 10 min, stir to fully dissolve the monomer, add 90 μL of trifluoroacetic acid, and then place in a 25 mL reactor and react at 120 °C for 120 h. S5. After the reaction is complete, the reactor is cooled to room temperature. The block gel is carefully removed from the glass tube and immersed in dioxane for 24 hours. The unreacted monomers and other impurities are washed off 3-4 times with fresh solvent. S6. Replace the dioxane in step S5 with DMF, methanol, acetone, and deionized water respectively, and soak for 24 hours, changing the solvent 3-4 times during the process to obtain a hydrogel, denoted as TPAD-Dha-C. 12 .

[0052] Example 4 Hydrogel TPAD-Dha-C 18 The preparation method includes the following steps: S1. 1,4,5,8-Tetrachloro-9,10-anthradinone (1.04 g, 3.00 mmol), tert-butyl N-(4-aminophenyl)carbamate (3.75 g, 18.00 mmol) and Cs2CO3 (7.80 g, 24.00 mmol) were dissolved in 50 mL of dry toluene under an argon atmosphere. After argon bubbling for 20 minutes, Pd2(dba)3 (110 mg, 4% mol) and 2,2'-bis(diphenylphosphine)-1,1'-dinaphthalene (BINAP, 330 mg, 12% mol) were added. The mixture was stirred at 110 °C for 48 h. The reaction solution was cooled, filtered, and the filter residue was dried. The obtained filter residue solid was soaked in water and stirred overnight. The filter residue was collected by filtration and vacuum dried. The filter residue was then dissolved in tetrahydrofuran and filtered. The filtrate was purified by column chromatography by rotary evaporation to obtain TPAD-NHBoc amino monomer. S2. 2,5-Dihydroxyterephthalaldehyde (498 mg, 3 mmol) and potassium carbonate (1.742 g, 12.6 mmol) were added to 35 mL of LDM and stirred for 30 minutes. Then, 1-bromooctadecane (2.501 g, 7.5 mmol) was slowly added dropwise. The resulting mixture was heated at 100 °C for 48 h under a nitrogen atmosphere, quenched with 35 mL of water, and then extracted with dichloromethane. The combined organic layers were dried on anhydrous magnesium sulfate, and the filtrate was purified by column chromatography after rotary evaporation to obtain Dha-C. 18 Aldehyde monomers; S3, 93 mg (0.09 mmol) of TPAD-NHBoc amino monomer and 121 mg (0.18 mmol) of Dha-C 12 Aldehyde monomers are added to a glass tube (dimensions: outer diameter 22mm, inner diameter 18mm, height 35mm, bottom sealed); S4. Add 5.1 mL of dioxane and 0.9 mL of deionized water to the glass tube of S3, sonicate for 10 min, stir to fully dissolve the monomer, add 90 μL of trifluoroacetic acid, and then place in a 25 mL reactor and react at 120 °C for 120 h. S5. After the reaction is complete, the reactor is cooled to room temperature. The block gel is carefully removed from the glass tube and immersed in dioxane for 24 hours. The unreacted monomers and other impurities are washed off 3-4 times with fresh solvent. S6. Replace the dioxane in step S5 with DMF, methanol, acetone, and deionized water respectively, and soak for 24 hours, changing the solvent 3-4 times during the process to obtain a hydrogel, denoted as TPAD-Dha-C. 18 .

[0053] Comparative Example 1 The preparation method of this comparative example can be referred to in Examples 1-4, the difference being that: the aldehyde monomer was not modified with a long chain, but otherwise it is the same as in Examples 1-4.

[0054] The preparation method of hydrogel TPAD-Dha-COF includes the following steps: S1. 1,4,5,8-Tetrachloro-9,10-anthradinone (1.04 g, 3.00 mmol), tert-butyl N-(4-aminophenyl)carbamate (3.75 g, 18.00 mmol) and Cs2CO3 (7.80 g, 24.00 mmol) were dissolved in 50 mL of dry toluene under an argon atmosphere. After argon bubbling for 20 minutes, Pd2(dba)3 (110 mg, 4% mol) and 2,2'-bis(diphenylphosphine)-1,1'-dinaphthalene (BINAP, 330 mg, 12% mol) were added. The mixture was stirred at 110 °C for 48 h. The reaction solution was cooled, filtered, and the filter residue was dried. The obtained filter residue solid was soaked in water and stirred overnight. The filter residue was collected by filtration and vacuum dried. The filter residue was then dissolved in tetrahydrofuran and filtered. The filtrate was purified by column chromatography by rotary evaporation to obtain TPAD-NHBoc amino monomer. S2. Add 93 mg (0.09 mmol) of TPAD-NHBoc amine monomer and 30 mg (0.18 mmol) of Dha aldehyde monomer to a glass tube (dimensions: outer diameter 22 mm, inner diameter 18 mm, height 35 mm, bottom sealed); S3. Add 5.1 mL of dioxane and 0.9 mL of deionized water to the glass tube of S3, sonicate for 10 min, stir to fully dissolve the monomer, add 90 μL of trifluoroacetic acid, and then place in a 25 mL reactor and react at 120 °C for 120 h. S4. After the reaction is complete, cool the reactor to room temperature, carefully remove the block gel from the glass tube, immerse it in dioxane for 24 hours, and wash away unreacted monomers and other impurities by changing the solvent 3-4 times. S5. Replace the dioxane in step S4 with DMF, methanol, acetone, and deionized water respectively, soak for 24 hours, and wash 3-4 times with fresh solvents in between to obtain hydrogel, denoted as TPAD-Dha-COF.

[0055] Test case The performance of the hydrogels prepared in Examples 1-4 and Comparative Example 1 was tested, as shown below.

[0056] 1. The Dha-EO2 aldehyde monomer, Dha-C7 aldehyde monomer, Dha-C12 aldehyde monomer, and Dha-C18 aldehyde monomer used in Examples 1-4 were subjected to 1H NMR spectroscopy. The results are as follows: Figures 1-4 As shown.

[0057] like Figures 1-4 By analyzing the chemical shifts, peak assignments, and integral ratios of the spectra, all signals were found to be precisely matched with the structures of the compounds, proving the successful synthesis of the above compounds.

[0058] 2. Fourier transform infrared spectroscopy analysis was performed on the hydrogels prepared in Examples 1-4 and Comparative Example 1. The results are as follows: Figure 5 As shown.

[0059] like Figure 5 The FT-IR spectra of the TPAD-Dha series samples all showed a C=N stretching vibration peak of the imine bond (1597 cm⁻¹). -1 C–O–C (1053 cm⁻¹) appeared in TPAD-Dha-EO₂. -1 ) and methylene characteristic peak (2923 cm⁻¹) -1 2850 cm -1 Furthermore, TPAD-Dha-EO2, along with TPAD-Dha-C7, TPAD-Dha-C12, and TPAD-Dha-C18, were at 1309 cm⁻¹. -1 The O–H bending vibration at 717 cm⁻¹ was significantly reduced. -1The presence of in-plane rocking vibrations at CH2 indicates that the hydroxyl group of Dha is replaced by an alkyl chain. The intensity of the methylene characteristic peak gradually increases with the length of the alkyl chain, confirming that Dha with different chain types and lengths can successfully react with TPAD-NHBoc.

[0060] 3. The morphology and structure of the hydrogels prepared in Examples 1-4 and Comparative Example 1 were observed using scanning electron microscopy. The results are as follows: Figure 6 As shown.

[0061] like Figure 6 The TPAD-Dha series samples exhibit a generally similar morphology, all composed of spheroidal aggregates. Additional long rod-like structures are observed in TPAD-Dha-C7 and TPAD-Dha-C12, but their basic building blocks remain spherical. Higher resolution images show that as the length of the alkyl chain modification increases, the nanofiber size increases, while the pores in the spherical structures are gradually filled.

[0062] 4. X-ray diffraction analysis of the hydrogels prepared in Examples 1-4 and Comparative Example 1 was performed, and the results are as follows: Figure 7 As shown.

[0063] like Figure 7 The COF, after being modified with long chains, still retains its crystalline structure. The spectra of TPAD-Dha-C7, TPAD-Dha-C12, and TPAD-Dha-C18 are similar to those of TPAD-Dha-COF, while the diffraction peaks of TPAD-Dha-EO2 are shifted to the right overall. This is due to the weak hydrogen bonding between the oxygen ether chain and the COF skeleton, which brings the interlayer or pore spacing closer together.

[0064] 5. The contact angles of the hydrogels prepared in Examples 1-4 and Comparative Example 1 were tested, and the results are as follows. Figure 8 As shown.

[0065] like Figure 8 Contact angle tests showed that both TPAD-Dha-COF and TPAD-Dha-EO2 were superhydrophilic, with droplets completely wetted within 0.08 s and 0.12 s, respectively. Conversely, TPAD-Dha-C7, TPAD-Dha-C12, and TPAD-Dha-C18, modified with long alkane chains, exhibited hydrophobicity, with contact angles increasing with chain length. This hydrophilic-hydrophobic shift is primarily attributed to the covering effect of the hydrophobic long chains on the hydrophilic backbone.

[0066] 6. The hydrogels prepared in Examples 1-4 and Comparative Example 1 were subjected to water wetting tests, and the results are as follows. Figure 9 As shown.

[0067] like Figure 9TPAD-Dha-COF and TPAD-Dha-EO2 can form stable colloids in water and exhibit the Tyndall effect; while TPAD-Dha-C7, TPAD-Dha-C12, and TPAD-Dha-C18 float on the liquid surface due to their strong hydrophobicity and cannot be submerged even after stirring or sonication. This is consistent with their contact angle test results, confirming the fundamental difference in their surface hydrophilicity and hydrophobicity.

[0068] 7. The hydrogels prepared in Examples 1-4 and Comparative Example 1 were subjected to powder heating tests, and the results are as follows. Figure 10 As shown.

[0069] like Figure 10 Under simulated solar illumination conditions (1 kW·m -2 The hydrogels prepared in Examples 1-4 and Comparative Example 1 were made into aerogel powder and filled into circular holes with a diameter of 1.5 cm for surface temperature testing. All samples heated up rapidly under light and reached equilibrium within tens of seconds. The equilibrium temperature of TPAD-Dha-COF reached 70℃, which may be due to the excessively long chain covering the photothermal active sites on the COF backbone, resulting in slightly poorer performance of TPAD-Dha-C18, with an equilibrium temperature of 66℃. However, all samples showed good photothermal absorption and conversion effects.

[0070] 8. The hydrogels prepared in Examples 1-4 and Comparative Example 1 were subjected to water evaporation tests, and the results are as follows. Figure 11 As shown.

[0071] like Figure 11 Grafting short chains can increase the evaporation rate, while excessively long chains, although they also have good evaporation effects, will reduce the evaporation rate.

[0072] 9. Raman spectroscopy was performed on the hydrogels prepared in Examples 1-4 and Comparative Example 1. The results are as follows. Figure 12 As shown.

[0073] like Figure 12 The water state was analyzed by Gaussian fitting of the hydroxyl stretching region using Raman spectroscopy, where 3233 cm⁻¹ was the optimal value. -1 and 3401 cm -1 It belongs to the FW with a complete hydrogen bond structure, and 3514 cm -1 and 3630 cm -1 This corresponds to IW with partially broken hydrogen bonds. Appropriate modification of short chains (such as oxygen ether chains or short alkane chains) can enhance the interaction between the COF network and water molecules, thereby increasing the IW content; among them, the hydrogen bond forming ability of the oxygen ether structure in TPAD-Dha-EO2 further promotes the enrichment of IW.

[0074] 10. The hydrogel prepared in Example 1 was subjected to a seawater evaporation test, and the results are as follows.Figure 13 As shown.

[0075] like Figure 13 Using real seawater as the water source, the collected condensate was analyzed by inductively coupled plasma mass spectrometry (ICP-MS) to detect the Na content in water samples before and after treatment. + Mg 2+ K + Ca 2+ After desalination, the ion concentration in the condensate was significantly reduced by 3-4 orders of magnitude, fully meeting the drinking water requirements stipulated by the World Health Organization (WHO).

[0076] 11. The hydrogel prepared in Example 1 was subjected to a water purification test for organic pollutants. The results are as follows: Figure 14 As shown.

[0077] like Figure 14 The performance of COF-based gels in wastewater treatment was evaluated using Rhodamine B and methylene blue as simulated pollutants. UV-Vis absorption spectra ( Figure X The results showed that the characteristic absorption peaks at 555 nm (Rhodamine B) and 660 nm (methylene blue) of the treated condensate completely disappeared, indicating that the pollutants were effectively removed and that the hydrogel has good wastewater treatment performance.

[0078] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a COF-based hydrogel based on long-chain modified aldehyde monomers, characterized by, Comprising the following steps: S1, 1, 4, 5, 8-tetrachloro-9, 10-anthracenedione, tert-butyl N- (4-aminophenyl) carbamate and Cs2CO3 are dissolved in toluene, then Pd2 (dba) 3 and 2, 2'-bis (diphenylphosphine) -1, 1'-binaphthalene are added, the reaction solution is cooled after stirring, filtered, and the filter residue is dried to obtain filter residue solid, the obtained filter residue solid is soaked with water and stirred, the filter residue is collected by continuous filtering and vacuum drying, then the filter residue is dissolved in tetrahydrofuran and filtered, the obtained filtrate is rotary evaporated and purified by column chromatography to obtain TPAD-NHBoc amine monomer; S2, 2, 5-dihydroxy terephthaldehyde, potassium carbonate are added in N, N-dimethylformamide and stirred, then bromoalkane is added dropwise, heated, quenched with water, extracted with dichloromethane, the combined organic layers are dried over anhydrous magnesium sulfate, the obtained filtrate is rotary evaporated and purified by column chromatography to obtain Dha aldehyde monomer; S3, TPAD-NHBoc amine monomer, Dha aldehyde monomer are added into a glass tube, dioxane, water are added into the glass tube and ultrasonically stirred, then trifluoroacetic acid is added and placed in a reaction kettle for reaction, after the reaction is completed, the blocky gel is cooled to room temperature and taken out; S4, the blocky gel is soaked in a solvent and washed to obtain the target hydrogel.

2. The method for preparing COF-based hydrogels based on long-chain modified aldehyde monomers according to claim 1, characterized in that, In step S1, the 1,4,5,8-tetrachloro-9,10-anthracenedione, tert-butyl N-(4- aminophenyl)carbamate, Cs2CO 3、 Pd2(dba)3, 2,2'-bis(diphenylphosphino)-1,1'-binaphthalene in a mass ratio of 1.0~1.2:3.5~3.8:7.6~7.9:0.10~0.15:0.30~0.35; the toluene is dry toluene.

3. The method for preparing COF-based hydrogels based on long-chain modified aldehyde monomers according to claim 1, characterized in that, In step S1, the stirring reaction temperature is 110-120℃, and the stirring time is 46-50h; the stirring time is 8-12h.

4. The method for preparing COF-based hydrogels based on long-chain modified aldehyde monomers according to claim 1, characterized in that, In step S2, the mass ratio of 2, 5-dihydroxy terephthaldehyde, potassium carbonate and bromoalkane is 0.4-0.6:1.5-1.8:1.2-2.0; the amount ratio of 2, 5-dihydroxy terephthaldehyde and N, N-dimethylformamide is 0.4-0.6g:30-40mL; the heating is carried out at 100-105℃ for 46-48h under nitrogen atmosphere.

5. The method for preparing COF-based hydrogels based on long-chain modified aldehyde monomers according to claim 1, characterized in that, In step S3, the mass ratio of TPAD-NHBoc amine monomer and Dha aldehyde monomer is 88-98:28-127; the mass-volume ratio of TPAD-NHBoc amine monomer and dioxane is 88-98mg:4.8-5.4mL; the volume ratio of dioxane, water and trifluoroacetic acid is 5-5.5:0.88-0.97:0.088-0.097; the bromoalkane is selected from one or more of 1-bromo-2- (2-methoxyethoxy) ethane, 1-bromoheptane, 1-bromododecane and 1-bromooctadecane.

6. The method for preparing COF-based hydrogels based on long-chain modified aldehyde monomers according to claim 1, characterized in that, In step S3, the size of the glass tube is outer diameter 22-25mm, inner diameter 18-20mm, and height 30-35mm; the volume of the reaction kettle is 25-30mL; the ultrasonic stirring time is 10-12min.

7. The method for preparing COF-based hydrogels based on long-chain modified aldehyde monomers according to claim 1, characterized in that, In step S4, the soaking time is 24-26h, and the new solvent is replaced 3-4 times during the soaking process; the solvent is selected from one or more of dioxane, DMF, acetone, methanol and water.

8. A COF-based hydrogel based on long-chain modified aldehyde monomer, prepared by the preparation method of any one of claims 1-7.

9. The COF-based hydrogel based on long-chain modified aldehyde-based monomers of claim 8, wherein, The structure of the hydrogel is shown in the following formula I: Formula I, In formula I, R is selected from alkoxy or oxyether groups.

10. The COF-based hydrogel based on long-chain modified aldehyde monomers prepared by the preparation method of any one of claims 1-7 or the COF-based hydrogel based on long-chain modified aldehyde monomers of any one of claims 8-9 for use in interfacial water evaporation.

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