Sulfonated modified COF-based hydrogel based on TPAD skeleton and preparation method and application thereof

Abstract

The invention provides a sulfonated modified COF-based hydrogel based on a TPAD skeleton, and a preparation method and application thereof, and belongs to the field of water treatment. The preparation method comprises the following steps: S1, synthesizing a TPAD-NHBoc amino monomer by using reagents such as 1, 4, 5, 8-tetrachloroanthraquinone and the like; s2, sequentially adding a TPAD-NHBoc amino monomer, a Dha aldehyde monomer, dioxane and trifluoroacetic acid into a glass tube according to a certain proportion, carrying out ultrasonic treatment, stirring, putting into a reaction kettle, and reacting at 115-125 DEG C for 96-120 hours; s3, after the reaction is finished and cooling is performed, carefully taking out the blocky gel from the glass tube, respectively immersing the blocky gel into dioxane and DMF, and repeatedly replacing the solvent for washing; s4, washing the gel, soaking the washed gel in a DMF solution containing 1, 3-propane sultone, and carrying out a reaction at 75-85 DEG C for 16-20 h to obtain sulfonated modified gel; s5, the obtained sulfonated modified COF-based gel is soaked in DMF, acetone, methanol and water for multiple times of soaking and washing, and the hydrogel is obtained. The sulfonated modified hydrogel based on the TPAD skeleton has excellent solar photo-thermal water evaporation performance.

Description

Technical Field

[0001] This invention relates to the field of water treatment, and specifically to a COF-based hydrogel based on TPAD skeleton sulfonation modification, its preparation method, and its application. Background Technology

[0002] Global population growth and accelerated industrialization have exacerbated freshwater shortages. While the Earth has abundant ocean water, freshwater resources are limited, making the development of seawater desalination technology crucial. Solar-powered interfacial evaporation technology has attracted significant attention in the seawater desalination field due to its high energy efficiency, simple structure, and low maintenance costs. Therefore, developing interfacial evaporation materials with efficient photothermal conversion, rapid water transport, and low enthalpy of vaporization is key to advancing the practical application of this technology.

[0003] Covalent organic frameworks (COFs) are a class of crystalline porous polymers with regular channels and highly ordered structures, formed by organic units linked by strong covalent bonds. Due to their advantages such as large specific surface area, high porosity, strong structural designability, and good chemical stability, they have shown great potential in gas storage, catalysis, and sensing. In recent years, the application of COF materials in photothermal conversion has also been gradually explored, making them potential interfacial evaporation materials.

[0004] Achieving low-enthalpy evaporation requires optimizing water transport and activation. The macroporous structure of simple gels facilitates rapid water transport, but their surface polar groups can only passively form water clusters, lacking active activation capabilities. Conversely, the high micropore density of covalent organic frameworks (COFs) makes them ideal templates for water clusters, actively promoting their formation within nano-confined pores, thereby accelerating activation and reducing enthalpy of evaporation. However, pure COF materials lack rapid water transport channels. In particular, COF hydrogels or gel materials prepared through dynamic covalent chemistry (such as imine exchange) not only inherit the structural characteristics of COFs but also possess the three-dimensional network structure of gels, which facilitates water transport and vapor escape, contributing to the synergistic achievement of efficient water transport and low-enthalpy evaporation.

[0005] However, when the unmodified COF gels are directly applied to interfacial evaporation, their performance is often limited by a series of inherent factors. Current research on the modification of COF evaporation materials focuses on macroscopic compositing (such as mixing with hydrophilic polymers) or surface coating. These methods may block the inherent ordered pores of COF, sacrificing its advantages of high specific surface area and rapid mass transport. How to fundamentally change the interfacial hydrophilicity and interaction with water molecules through precise chemical modification while maintaining the integrity of the porous network and photothermal activity of COF gel, thereby affecting the evaporation performance of COF-based hydrogel materials, is a challenge that has not yet been fully solved. To address the shortcomings of existing technologies, a sulfonated imine covalent organic framework is designed. The enol-imine bond in TPAD-Dha-COF is irreversibly converted into a β-ketoamine bond through a tautomerism reaction. A flexible side chain (1-propanesulfonyl) with a sulfonic acid group at the end is covalently grafted onto the material framework. The effect of COF-based gel sulfonation modification on evaporation performance is further investigated. A novel high-efficiency interfacial evaporation material with excellent photothermal performance, high-speed water transport capability, and low enthalpy of vaporization is developed to meet the urgent needs of high-performance, low-cost evaporation devices in fields such as seawater desalination and high-salinity wastewater treatment. Summary of the Invention

[0006] This invention proposes a TPAD-based COF-based hydrogel with sulfonation modification, its preparation method, and its application. Using TPAD-Dha-COF as the base COF gel, while maintaining the integrity of the porous network and photothermal activity of the COF gel, flexible side chains (1-propanesulfonyl) with sulfonic acid groups are introduced into the COF backbone through precise chemical modification, revealing the effect of COF-based gel sulfonation modification on evaporation performance.

[0007] The technical solution of this invention is implemented as follows: A method for preparing COF-based hydrogels based on TPAD skeleton sulfonation modification, comprising the following steps: S1. Dissolve 1,4,5,8-tetrachloro-9,10-anthradinone, tert-butyl N-(4-aminophenyl)carbamate, and Cs2CO3 in toluene, then add Pd2(dba)3 and 2,2'-bis(diphenylphosphine)-1,1'-dinaphthalene, stir the reaction, cool the reaction solution, filter, and dry the filter residue to obtain a solid filter residue. Soak the obtained solid filter residue in water and stir, continue to filter, collect the filter residue, and dry it under vacuum. Then dissolve the filter residue in tetrahydrofuran and filter it. The obtained filtrate is purified by rotary evaporation and column chromatography to obtain the TPAD-NHBoc amino monomer.

[0008] S2. Add TPAD-NHBoc amine monomer, Dha (2,5-dihydroxy-terephthalaldehyde) aldehyde monomer, dioxane, and deionized water to a glass tube, and sonicate and stir to fully dissolve the monomers. Add trifluoroacetic acid, and then place the tube in a reaction vessel to react.

[0009] S3. After the reaction is complete, cool the reactor to room temperature, carefully remove the block gel from the glass tube, soak it in dioxane and DMF, and wash away unreacted monomers and impurities by changing the solvent several times.

[0010] S4. Place the washed gel obtained in S3 into a glass tube, add a DMF solution containing 1,3-propanesulfonic acid lactone, then place it in a vacuum glove box overnight, and seal it in a reaction vessel to obtain sulfonated modified COF-based gel.

[0011] S5. The sulfonated modified COF-based gel obtained in S4 is immersed in DMF, acetone, methanol and water for multiple soaking and washing to obtain the target hydrogel.

[0012] The synthetic route for the invented TPAD-Dha-SO3H is as follows: Furthermore, in step S1, the 1,4,5,8-tetrachloro-9,10-anthradinone, tert-butyl N-(4-aminophenyl)carbamate, and Cs2CO... 3、 The mass ratio of Pd2(dba)3 to 2,2'-bis(diphenylphosphine)-1,1'-dinaphthalene is 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; the stirring reaction temperature is 110~120℃ and the time is 46~50h; the stirring time is 8~12h. Furthermore, in step S2, the amounts of TPAD-NHBoc amine monomer and Dha aldehyde monomer are 88-98 mg and 28-32 mg, respectively; the volume ratio of dioxane, water, and trifluoroacetic acid is 5-5.5:0.88-0.97:0.088-0.097; the ultrasonication time is 10-12 min; the glass tube dimensions are 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 vessel is 25-30 mL; the reaction temperature is 118-122 °C; and the reaction time is 94-98 h.

[0013] Furthermore, in step S3, the soaking time is 24-26 hours, and the solvent is replaced 3-4 times during the soaking process.

[0014] Furthermore, in step S4, the DMF solution containing 1,3-propanesulfonic acid lactone is prepared by dissolving 0.34-0.38g of 1,3-propanesulfonic acid lactone in 1.8-2.2ml of DMF. The solution needs to be sealed in a vacuum glove box to ensure an inert gas environment. The reaction temperature is 75-85℃ and the reaction time is 16-20h.

[0015] Furthermore, in step S5, the soaking time in a single solvent is 12-24 hours, and the solvent is replaced 3-4 times during this period.

[0016] The present invention also provides a COF-based hydrogel based on TPAD skeleton sulfonation modification, which is prepared by any of the above preparation methods.

[0017] The application of the TPAD-based skeleton sulfonated modified COF-based hydrogel prepared by the above preparation method, or the TPAD-based skeleton sulfonated modified COF-based hydrogel, in the field of water treatment.

[0018] Compared with the prior art, the beneficial effects of the present invention are: This invention proposes a method for preparing COF-based hydrogels based on sulfonation modification of a TPAD backbone. A COF-based gel with flexible side chains (1-propanesulfonyl) terminally grafted onto a COF backbone was designed and synthesized, revealing the effect of sulfonation modification on the evaporation performance of the COF-based gel. This application provides a good material for obtaining freshwater resources. Attached Figure Description

[0019] Figure 1 The 1H NMR spectrum of the TPAD-NHBoc amine monomer in Example 1 Figure 2 This is a schematic diagram of the synthesis of Example 1 and the comparative example. Figure 3 Infrared spectra of TPAD-NHBoc, Dha, and TPAD-Dha-COF in the comparative examples Figure 4 Infrared spectra of the hydrogels prepared in Example 1 and Comparative Example 1 Figure 5 Scanning electron microscope (SEM) images of the hydrogels prepared in Example 1 and Comparative Example 1. Figure 6 The XRD diffraction patterns of the hydrogels prepared in Example 1 and Comparative Example 1 are shown below. Figure 7 The contact angle diagrams are for the hydrogels prepared in Example 1 and Comparative Example 1. Figure 8 The UV absorption spectra of the hydrogels prepared in Example 1 and Comparative Example 1 are shown. Figure 9The graph shows the water evaporation properties of the hydrogels prepared in Example 1 and Comparative Example 1. Figure 10 The differential scanning calorimetry (DSC) graphs are shown for the hydrogels prepared in Example 1 and Comparative Example 1. Figure 11 The diagram shows the seawater evaporation in Example 1. Figure 12 Diagram of organic polluted water purification in Example 1 Detailed Implementation

[0020] 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.

[0021] Unless otherwise specified, the experimental methods used in the embodiments of this application are all conventional methods.

[0022] In the following examples and comparative examples, unless otherwise specified, all raw materials can be prepared by commercial purchase or conventional methods. Example

[0023] The sample was TPAD-Dha-SO3H S1. Dissolve 1.04 g of 1,4,5,8-tetrachloroanthraquinone, 3.75 g of tert-butyl N-(4-aminophenyl)carbamate, and 7.80 g of Cs₂CO₃ in 50 mL of dry toluene. Dissolve under an argon atmosphere and bubble with argon for 20 minutes. Add 110 mg of Pd₂(dba)₃ and 330 mg of 2,2'-bis(diphenylphosphine)-1,1'-dinaphthalene (BINAP). Stir at 110 °C for 48 h, cool the reaction solution, filter, dry the filter residue, soak the obtained filter residue solid in water and stir overnight, continue filtering and collect the filter residue, dry under vacuum, dissolve the filter residue in tetrahydrofuran and filter, and purify the filtrate by rotary evaporation and column chromatography to obtain the TPAD-NHBoc amino monomer.

[0024] S2. Add 93 mg TPAD-NHBoc amine monomer, 30 mg Dha (2,5-dihydroxy-terephthalaldehyde) aldehyde monomer, 5.1 mL dioxane, and 0.9 mL deionized water to a glass tube, sonicate for 10 min, stir to fully dissolve the monomer, add 90 μL trifluoroacetic acid, and then place in a reaction vessel and react at 120 °C for 96 h.

[0025] S3. After the reaction is complete, cool the reactor to room temperature, carefully remove the block gel from the glass tube, and soak it in dioxane and DMF for 24 hours respectively. Replace the solvent three times during the soaking and washing to remove unreacted monomers and impurities.

[0026] S4. Place the washed gel obtained in S3 into a glass tube, add 2 mL of LDMF solution containing 3.6 g of 1,3-propanesulfonic acid lactone, then place it in a vacuum glove box overnight, and then seal it in a reaction vessel under an inert gas environment and react at 80 °C for 16 h to obtain sulfonated modified COF-based gel.

[0027] S5. The sulfonated modified COF-based gel obtained in S4 was soaked in DMF, acetone, methanol, and water for 24 hours, with the solvent changed three times during the soaking and washing process to obtain the hydrogel TPAD-Dha-SO3H.

[0028] Comparative Example The sample was TPAD-Dha-COF S1. Dissolve 1.04 g of 1,4,5,8-tetrachloroanthraquinone, 3.75 g of tert-butyl N-(4-aminophenyl)carbamate, and 7.80 g of Cs₂CO₃ in 50 mL of dry toluene. Dissolve under an argon atmosphere and bubble with argon for 20 minutes. Add 110 mg of Pd₂(dba)₃ and 330 mg of 2,2'-bis(diphenylphosphine)-1,1'-dinaphthalene (BINAP). Stir at 110 °C for 48 h, cool the reaction solution, filter, dry the filter residue, soak the obtained filter residue solid in water and stir overnight, continue filtering and collect the filter residue, dry under vacuum, dissolve the filter residue in tetrahydrofuran and filter, and purify the filtrate by rotary evaporation and column chromatography to obtain the TPAD-NHBoc amino monomer.

[0029] S2. Add 93 mg TPAD-NHBoc amine monomer, 30 mg Dha (2,5-dihydroxy-terephthalaldehyde) aldehyde monomer, 5.1 mL dioxane, and 0.9 mL deionized water to a glass tube, sonicate for 10 min, stir to fully dissolve the monomer, add 90 μL trifluoroacetic acid, and then place in a reaction vessel and react at 120 °C for 96 h.

[0030] S3. After the reaction is complete, the reactor is cooled to room temperature. The block gel is carefully removed from the glass tube and soaked in dioxane, DMF, acetone, methanol, and deionized water for 24 hours, respectively. The unreacted monomers and impurities are washed off three times with fresh solvents during the soaking process to obtain TPAD-Dha-COF.

[0031] Test case 1. The monomer TPAD-NHBoc used in Example 1 and the comparative example were subjected to proton nuclear magnetic resonance (NMR) spectroscopy. Figure 1By analyzing the chemical shifts, peak assignments, and integral ratios of the spectra, all signals were found to be precisely matched with the structure of the compound TPAD-NHBoc, proving the successful synthesis of TPAD-NHBoc.

[0032] 2. For example Figure 2 A schematic diagram of the synthesis of COF-based gel formed by the condensation of two monomers through aldehyde-amine and further sulfonation modification.

[0033] 3. Fourier transform infrared spectroscopy analysis was performed on the monomers TPAD-NHBoc, Dha, and TPAD-Dha-COF used in Comparative Example 1, such as... Figure 3 Comparing the FT-IR spectra of TPAD-NHBoc, Dha, and TPAD-Dha-COF, it can be seen that the aldehyde C=O (1672 cm⁻¹) in the monomer Dha of the TPAD-Dha-COF reaction was not found. -1 ) and the NH (3385 cm) in the Boc group of TPAD-NHBoc -1 CH3 (3352 cm) -1 2977 cm -1 C=O (1696 cm) -1 The signal was detected, and C=N (1596 cm⁻¹) appeared in TPAD-Dha-COF. -1 The signal confirmed that the two monomers underwent an aldehyde-amine condensation reaction in the reactor.

[0034] 4. Perform Fourier transform infrared spectroscopy analysis on Example 1, such as... Figure 4 Compared to TPAD-Dha-COF, TPAD-Dha-SO3H exhibits -SO3H (1047 cm⁻¹). -1 ) signal and methylene (2930 cm -1 2870 cm -1 The reaction of 3-sulfopropyl (-(CH2)3SO3H) with the C=N double bond causes the signal peak of the C=N double bond to rise from 1596 cm⁻¹. -1 Redshifted to 1583 cm -1 The above results confirm the successful modification of 3-sulfopropyl.

[0035] 5. Perform scanning electron microscopy (SEM) tests on Example 1, such as... Figure 5 TPAD-Dha-COF and TPAD-Dha-SO3H exhibit a uniform spherical structure, both possessing sponge-like multi-scale pores and interpenetrating macroporous frameworks.

[0036] 6. Perform X-ray diffraction analysis on Example 1 and the comparative example, such as... Figure 5The X-ray diffraction patterns of TPAD-Dha-COF and TPAD-Dha-SO3H were basically consistent, revealing that the sulfonation modification did not change its basic crystal structure. The simulation results of TPAD-Dha-COF were obtained by using Materials Studio software, and the simulation results were in good agreement with the experimental results.

[0037] 7. Conduct contact angle tests on Example 1 and the comparative example, such as... Figure 5 Water droplets applied to the surfaces of TPAD-Dha-COF and TPAD-Dha-SO3H were rapidly absorbed within 0.08 s and 0.04 s, respectively. TPAD-Dha-SO3H still exhibited super hydrophilicity after modification.

[0038] 8. Perform UV absorption tests on Example 1 and the comparative example, such as... Figure 7 The solar energy absorption rates of TPAD-Dha-COF and TPAD-Dha-SO3H are approximately 88%, exhibiting broad-spectrum absorption characteristics overall.

[0039] 9. Perform water evaporation tests on Example 1 and the comparative example, such as... Figure 8 TPAD-Dha-SO3H exhibited a better water evaporation rate than TPAD-Dha-COF under one day of sunlight.

[0040] 10. Differential scanning calorimetry (DSC) tests were performed on Example 1 and the comparative example. Figure 9 The enthalpy of vaporization calculated by TPAD-Dha-COF and TPAD-Dha-SO3H are 2084 J / g and 1861 J / g, respectively, both lower than the enthalpy of vaporization of pure water (2383 J / g), and TPAD-Dha-SO3H exhibits an even lower enthalpy of vaporization.

[0041] 11. An evaporation test was conducted on Example 1, such as... Figure 10 The collected condensate was analyzed by inductively coupled plasma mass spectrometry (ICP-MS) to detect the Na content in the 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, meeting the drinking water requirements set by the World Health Organization (WHO).

[0042] 12. Example 1 was subjected to an organic polluted water purification test, such as... Figure 11 Using Rhodamine B and methylene blue as simulated pollutants, UV-Vis absorption spectroscopy 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 in the condensate had been basically removed.

Claims

1. A method for preparing COF-based hydrogels based on TPAD skeleton sulfonation modification, characterized in that, The specific steps include the following: S1. 1,4,5,8-Tetrachloro-9,10-anthradinone, tert-butyl N-(4-aminophenyl)carbamate, and Cs₂CO₃ were dissolved in toluene. Then, Pd₂(dba)₃ and 2,2'-bis(diphenylphosphine)-1,1'-dinaphthalene were added, the mixture was stirred, and the reaction solution was cooled. The solution was filtered, and the filter residue was dried to obtain a solid filter residue. The solid filter residue was soaked in water and stirred, then filtered again. The filter residue was collected and dried under vacuum. The filter residue was then dissolved in tetrahydrofuran and filtered. The filtrate was purified by rotary evaporation and column chromatography to obtain the TPAD-NHBoc amino monomer. S2. The TPAD-NHBoc amino monomer, Dha (2,5-dihydroxy-terephthalaldehyde) aldehyde monomer, dioxane, and deionized water were added to a glass tube. The mixture was sonicated and stirred to fully dissolve the monomer. Trifluoroacetic acid was added, and the mixture was then placed in a reaction vessel for reaction. S3. 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 and DMF, with the solvent changed multiple times to wash away unreacted monomers and impurities. S4. The washed gel obtained in S3 is placed in a glass tube, and a DMF solution containing 1,3-propanesulfonate lactone is added. The tube is then placed in a vacuum glove box overnight and sealed in the reactor to react and obtain the sulfonated modified COF-based gel. S5. The sulfonated modified COF-based gel obtained in S4 is immersed in DMF, acetone, methanol, and water multiple times for washing to obtain the target hydrogel.

2. The preparation method of COF-based hydrogel based on TPAD skeleton sulfonation modification as described in claim 1, wherein in step S1, the 1,4,5,8-tetrachloro-9,10-anthradinone, tert-butyl N-(4-aminophenyl)carbamate, and Cs2CO 3、 The mass ratio of Pd2(dba)3 to 2,2'-bis(diphenylphosphine)-1,1'-dinaphthalene is 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; the stirring reaction temperature is 110~120℃ and the time is 46~50h; the stirring time is 8~12h.

3. The preparation method of COF-based hydrogel based on TPAD skeleton sulfonation modification as described in claim 1, characterized in that, In step S2, the amounts of TPAD-NHBoc amine monomer and Dha aldehyde monomer are 88-98 mg and 28-32 mg, respectively; the volume ratio of dioxane, water, and trifluoroacetic acid is 5-5.5:0.88-0.97:0.088-0.097; the ultrasonication time is 10-12 min; the glass tube dimensions are 22-25 mm outer diameter, 18-20 mm inner diameter, and 30-35 mm height; the volume of the reaction vessel is 25-30 mL; the reaction temperature is 118-122 °C; and the reaction time is 94-98 h.

4. The preparation method of COF-based hydrogel based on TPAD skeleton sulfonation modification as described in claim 1, characterized in that, In step S3, the soaking time is 24-26 hours, and the solvent is replaced 3-4 times during the soaking process.

5. The method for preparing a COF-based hydrogel based on TPAD skeleton sulfonation modification as described in claim 1, characterized in that, In step S4, the DMF solution containing 1,3-propanesulfonic acid lactone is prepared by dissolving 0.34-0.38g of 1,3-propanesulfonic acid lactone in 1.8-2.2ml of DMF. The solution needs to be sealed in a vacuum glove box to ensure an inert gas environment. The reaction temperature is 75-85℃ and the reaction time is 16-20h.

6. The method for preparing a COF-based hydrogel based on TPAD skeleton sulfonation modification as described in claim 1, characterized in that, In step S5, the soaking time is 12-24 hours, and the solvent is replaced 3-4 times during the soaking process.

7. A COF-based hydrogel based on TPAD skeleton sulfonation modification, characterized in that, It is prepared by the preparation method according to any one of claims 1-5.

8. The application of the TPAD-based skeleton sulfonated modified COF-based hydrogel prepared by the preparation method according to any one of claims 1-5, or the TPAD-based skeleton sulfonated modified COF-based hydrogel according to claim 6, in the field of water treatment.

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