Ordered defect-free covalent organic framework membrane material as well as preparation method and application thereof

Abstract

The invention discloses an ordered defect-free covalent organic framework membrane material as well as a preparation method and application thereof. The membrane material is grown on a base membrane through a solvothermal reaction in a liquid phase reaction system. The liquid phase reaction system comprises an amine monomer, an aldehyde monomer, a catalyst and a solvent. The amine monomer and the aldehyde monomer contain different quantities of triazine structural units. Interlayer interaction of the covalent organic framework film is regulated and controlled through molecular structure design, and ordered and defect-free growth of the film is effectively driven. The membrane material provided by the invention has a regular pore structure and a relatively narrow interlayer spacing, shows excellent membrane forming property and structural integrity, and shows high separation performance on drug molecules with molecular weight greater than 400 Da when being applied to organic solvent nanofiltration, and the rejection rate exceeds 90%. Meanwhile, the membrane material is still stable under the organic solvent operation pressure of 2 bar, the separation performance is not attenuated in multiple times of recycling, and good operation stability is shown.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of covalent organic framework materials (COFs), specifically to a kind of ordered defect-free covalent organic framework film material, its preparation method and its application in organic solvent nanofiltration, belong to the field of high polymer materials. BACKGROUND

[0003] Traditional separation techniques (such as distillation processes used in petroleum refining and pharmaceutical engineering) usually have the characteristics of high energy consumption and high cost. Membrane-based separation technology has attracted much attention in the separation field in recent years due to its low energy consumption, simple operation, and especially its small pollution. As the core component of membrane separation technology, membrane materials with ingenious design can meet various high-difficulty separation requirements. Among them, organic solvent nanofiltration (OSN) technology has made significant breakthroughs in the past decade. Although traditional polymer membrane materials such as polyimide exhibit good OSN performance, their inherent solvent swelling and irregular mass transfer channels limit long-term use performance and separation selectivity. Therefore, it is urgent to develop a new generation of membrane materials with long-term stability and higher selectivity.

[0004] Currently, the main nanofiltration membranes are mainly prepared by cross-linked polymer materials such as polyimide, but such materials have inherent defects such as uneven pore distribution and poor connectivity, which not only lack ordered and adjustable pore structure, but also limit the solvent permeation efficiency. Crystal porous materials (such as zeolites and MOFs) are attracting attention due to their excellent molecular sieving performance, which is expected to improve both the permeability and selectivity of the membrane. However, the preparation of crystal porous material separation membranes by filler doping method is prone to uneven membrane layer, and the in-situ growth method has weak interfacial bonding. Therefore, researchers are working to develop innovative materials that have both uniform film-forming ability and strong interfacial bonding, in order to achieve efficient and precise molecular sieving. Covalent organic frameworks, as a new type of crystalline porous material, are known for their long-range ordered structure, which can form two-dimensional (2D) or three-dimensional (3D) pore structures. Its well-controlled pore structure has both designed topology and functional characteristics, which provides the possibility for customized high-selectivity separation membranes. With the continuous breakthroughs in preparation technology and cost reduction, COF membranes, with their precise molecular sieving ability and excellent solvent stability, create significant economic and environmental benefits for the pharmaceutical industry.

[0005] COFs are crystalline porous materials composed of organic building units that are connected within their layers by covalent bonds but are connected between layers by van der Waals forces and other non-covalent interactions. The exact stacking order of these layers is critical to the properties of these polymeric materials. Weak interlayer interactions lead to various stacking geometries of COFs, resulting in complex or ambiguous polymorphs; these stacking geometries are difficult to characterize and poorly understood due to low crystallinity. Therefore, detailed understanding of stacking geometries in COFs remains largely elusive. Furthermore, weak interlayer interactions, leading to stacking disorder, pose considerable challenges in fabricating, processing, and applying COF membranes, hindering the reproducibility of membrane synthesis and stability of long-term performance. Therefore, regulating interlayer strong forces to construct ordered structures is a new technology for preparing high-performance 2D COF membranes.

[0006] Currently, the strategies for regulating the interlayer forces of two-dimensional COF membranes mainly include MXene intercalation and post-modification. In the application of organic solvent nanofiltration, MXene intercalation can increase the interlayer spacing to improve the solvent flux, but it is often difficult to maintain high rejection. On the other hand, COF membrane post-modification can simultaneously adjust the planar pore and interlayer force of the COF membrane, but often causes the effective pore size to decrease while increasing the interlayer spacing, resulting in a decrease in permeation flux. Therefore, balancing the relationship between flux and rejection caused by interlayer spacing adjustment becomes a key problem. SUMMARY

[0007] The main purpose of the present application is to provide an ordered and defect-free covalent organic framework membrane material, a preparation method and application thereof, to overcome the deficiencies in the prior art.

[0008] In order to achieve the above-mentioned purposes of the application, the following technical solutions are adopted.

[0009] The first aspect of the present application provides a preparation method of an ordered and defect-free covalent organic framework membrane material, which comprises: providing a liquid phase reaction system comprising amine monomers, aldehyde monomers, a catalyst and a solvent, the amine monomers and the aldehyde monomers containing different numbers of triazine structural units; subjecting the liquid phase reaction system to a solvothermal reaction, so as to grow and form an ordered and defect-free covalent organic framework membrane material on the base film.

[0010] The second aspect of the present application provides an ordered and defect-free covalent organic framework membrane material, which is prepared by the preparation method of the ordered and defect-free covalent organic framework membrane material.

[0011] A third aspect of the present invention provides a method for controlling the interlayer forces of an ordered, defect-free covalent organic framework membrane material, comprising: when a liquid-phase reaction system is subjected to a solvothermal reaction to form the ordered, defect-free covalent organic framework membrane material, controlling the interlayer forces of the ordered, defect-free covalent organic framework membrane material by at least adjusting the types of amine monomers and / or aldehyde monomers in the liquid-phase reaction system; The liquid-phase reaction system comprises an amine monomer, an aldehyde monomer, a catalyst, and a solvent, wherein the amine monomer and the aldehyde monomer contain different numbers of triazine structural units.

[0012] A fourth aspect of the invention provides the use of the ordered, defect-free covalent organic framework membrane material in organic solvent nanofiltration.

[0013] Compared with the prior art, the present invention has at least the following significant advantages: (1) Triazine structural units were innovatively introduced, and a two-dimensional covalent organic framework membrane material with imine bonds was successfully constructed through an optimized solvothermal synthesis process.

[0014] (2) The prepared two-dimensional covalent organic framework membrane material exhibits unique structural advantages, including but not limited to: ① having a highly uniform pore structure and a narrow interlayer spacing, achieving excellent film-forming properties and precise molecular sieving; ② exhibiting excellent chemical and thermal stability, and can operate stably for a long time in harsh organic solvent environments; ③ exhibiting excellent selectivity in drug molecular sieving while maintaining excellent solvent permeation flux.

[0015] (3) The prepared two-dimensional covalent organic framework membrane material has strong interlayer interaction forces, which makes it easier for COF to grow into a smooth and defect-free membrane material on the base membrane. It provides a new material solution for organic solvent nanofiltration and has important application value in the separation and purification process in the fields of medicine and chemical industry. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is the 1H NMR spectrum of the monomer 1,3,5-tris(4-aminophenyl)triazine obtained in Example 1 of this invention.

[0018] Figure 2 This is the 1H NMR spectrum of the monomer 1,3,5-tris(4-formylphenyl)triazine obtained in Example 2 of the present invention.

[0019] Figures 3a-3d are infrared spectra of the two-dimensional covalent organic framework materials TT-COF, TB-COF, BT-COF and BB-COF obtained in Example 3 and Example 4 of the present application.

[0020] Figure 4 are thermogravimetric curves of the two-dimensional covalent organic framework materials TT-COF, TB-COF, BT-COF and BB-COF obtained in Example 3 and Example 4 of the present application.

[0021] Figures 5a-5b are nitrogen adsorption-desorption isotherms and pore size distribution diagrams of the two-dimensional covalent organic framework materials TT-COF, TB-COF, BT-COF and BB-COF obtained in Example 3 and Example 4 of the present application, respectively.

[0022] Figures 6a-6d are X-ray powder diffraction experiment and packing simulation diagrams of the two-dimensional covalent organic framework materials TT-COF, TB-COF, BT-COF and BB-COF obtained in Example 3 and Example 4 of the present application, respectively.

[0023] Figure 7 are X-ray powder diffraction diagrams of the two-dimensional covalent organic framework materials TT-COF, TB-COF, BT-COF and BB-COF (2θ is 10-30 o ) obtained in Example 3 and Example 4 of the present application.

[0024] Figures 8a-8d are scanning electron microscope diagrams of the two-dimensional covalent organic framework materials TT-COF, TB-COF, BT-COF and BB-COF obtained in Example 3 and Example 4 of the present application, respectively.

[0025] Figures 9a-9d are transmission electron microscope diagrams of the two-dimensional covalent organic framework materials TT-COF, TB-COF and BT-COF obtained in Example 3 of the present application, respectively.

[0026] Figures 10a-10b are scanning electron microscope diagrams of the surface and cross section of the CPI base film obtained in Example 5 of the present application, respectively.

[0027] Figures 11a-11d are scanning electron microscope diagrams of the surface of the two-dimensional covalent organic framework film materials TT-COF film obtained in Example 6 when the monomer concentration is 1 mmol / L, 1.5 mmol / L, 2.5 mmol / L and 4 mmol / L, respectively.

[0028] Figures 12a-12dare scanning electron microscope images of the film surface of the two-dimensional covalent organic framework film material TB-COF obtained in Example 7 at monomer concentrations of 1 mmol / L, 1.5 mmol / L, 2.5 mmol / L, and 4 mmol / L, respectively.

[0029] Figures 13a-13d are scanning electron microscope images of the film surface of the two-dimensional covalent organic framework film material BT-COF obtained in Example 8 at monomer concentrations of 1 mmol / L, 1.5 mmol / L, 2.5 mmol / L, and 4 mmol / L, respectively.

[0030] Figures 14a-14d are scanning electron microscope images of the film surface of the two-dimensional covalent organic framework film material BB-COF obtained in Example 9 at monomer concentrations of 1 mmol / L, 1.5 mmol / L, 2.5 mmol / L, and 4 mmol / L, respectively.

[0031] Figures 15a-15d are scanning electron microscope images of the cross section of the two-dimensional covalent organic framework film material TT-COF, TB-COF, BT-COF, and BB-COF obtained in Example 6-Example 9 of the present application at a monomer concentration of 2.5 mmol / L, respectively.

[0032] Figures 16a-16b are scanning electron microscope images of the two-dimensional covalent organic framework film material TT-COF and BB-COF obtained in Example 7 of the present application at different synthesis times and a monomer concentration of 2.5 mmol / L.

[0033] Figure 17 is a graph of the methanol permeability of the two-dimensional covalent organic framework film material TT-COF, TB-COF, BT-COF, and BB-COF obtained in Example 8 of the present application as a function of monomer concentration.

[0034] Figure 18 is a performance test graph of the two-dimensional covalent organic framework film material TT-COF, TB-COF, BT-COF, and BB-COF obtained in Example 8 of the present application at a monomer concentration of 2.5 mmol / L for drug molecules of different molecular weights.

[0035] Figure 19 is a graph of the drug molecule rifampicin rejection rate of the two-dimensional covalent organic framework film material TT-COF, TB-COF, BT-COF, and BB-COF obtained in Example 8 of the present application as a function of monomer concentration.

[0036] Figure 20is the UV chart of selective interception of the mixed solution of tetracycline / rifampicin (1:1) in methanol by the two-dimensional covalent organic framework film material TT-COF, TB-COF, BT-COF, BB-COF film obtained in Example 8 of the present application.

[0037] Figure 21 is the flux test chart of the two-dimensional covalent organic framework film material TT-COF film obtained in Example 8 of the present application to solvents with different viscosities. DETAILED DESCRIPTION

[0038] To overcome the shortcomings of the prior art, realize fast and simple preparation, and improve the separation performance of organic solvents and specific molecules, the present application mainly introduces a rigid planar triazine unit at the center of aldehyde and amino monomers with C3 symmetry through a molecular engineering strategy. By preparing COF films with different central structures, the influence of the triazine structural unit on the interlayer force of the film material, its film-forming property and separation performance is systematically elucidated. Through the unique rigid planar structure and π-π stacking effect of the triazine unit, the interlayer spacing of the COF film is accurately regulated, and the structure-parameter-separation performance structure-activity relationship is established, so as to realize fast and simple defect-free preparation while improving the separation performance of small molecules. The technical solutions of the present application will be described in detail as follows.

[0039] Firstly, the present application provides a kind of two-dimensional covalent organic framework film material, these materials have different number of triazine structural units, which can be named as TT-COF, TB-COF, BT-COF, BB-COF respectively, and the corresponding structural formulae are as follows: BB-COF BT-COF TB-COF TT-COF The present application finds through systematic characterization and performance test that among the above four kinds of COF film materials, TT-COF containing the largest number of triazine units exhibits excellent performance molecular interception performance and film-forming property, thereby confirming that the triazine unit can effectively regulate the interlayer spacing of the COF film through its rigid planar structure and π-π stacking effect, providing a new theoretical basis for more in-depth understanding of the film-forming mechanism of the COF film, providing important molecular engineering guidance for designing high-performance COF separation film materials, opening up a new way for developing efficient and stable organic solvent nanofiltration membranes, and having important application value in the fields of fine chemical separation and drug purification.

[0040] The present application mainly adopts two benzene-centered monomers TAPB and TFPB and two triazine-based monomers TAPT and TFPT as structural units, through the interaction of aldehyde monomers and amino monomers, the rigidity and planar triazine unit of the aldehyde and amino monomer center dominate the structure stacking behavior in the process of microcrystal growth, thereby obtaining the above four COF film materials with different number and chemical positions of triazine units.

[0041] The preparation method of the two-dimensional covalent organic framework material provided by some embodiments of the present application specifically comprises the following steps: under a vacuum environment, a uniform mixed reaction system comprising an amine monomer, an aldehyde monomer, an acetic acid aqueous solution and a solvent is subjected to a reaction at 100-150 o C for 3-7 days to obtain the two-dimensional covalent organic framework material.

[0042] Further, the amine monomer, the aldehyde monomer, the acetic acid aqueous solution and the solvent can be used in a ratio of 0.05 mmol:0.05 mmol:0.2 mL:1 mL.

[0043] Further, the preparation method can further comprise the following steps: after the reaction is completed, the obtained mixture is subjected to a centrifugal, washing and drying treatment.

[0044] Further, the washing liquid used in the washing treatment can be selected from, but is not limited to, tetrahydrofuran and acetone.

[0045] Further, the method used in the washing treatment is Soxhlet extraction. Further, the drying treatment can comprise the following steps: the obtained solid is vacuum dried at 70-80 o C for 12-24 h.

[0046] In some more specific embodiments, the preparation method of the two-dimensional covalent organic framework material specifically comprises the following steps: (1) the amine monomer and the aldehyde monomer are added to a certain amount of solvent under a vacuum atmosphere to prepare a solution, and a certain amount of acetic acid aqueous solution is added; (2) the mixed system prepared in step (1) is placed in a reaction container and transferred to a constant-temperature oven to be heated to 120 o C and kept for 3 days; (3) after the heating reaction is completed, the reaction container is cooled to room temperature, the solid is collected by centrifugation, the obtained solid is washed with tetrahydrofuran and acetone for multiple times and is subjected to Soxhlet extraction at 80 ℃, and then vacuum drying is performed, finally obtaining the two-dimensional organic framework material.

[0047] Further, the amine monomer in step (1) comprises 1,3,5-tris(4-aminophenyl)triazine and 1,3,5-tris(4-aminophenyl)benzene, and is not limited thereto.

[0048] Further, the aldehyde monomer of step (1) includes 1,3,5-tris(4-formylphenyl)triazine, 1,3,5-tris(p-formylphenyl)benzene, and the like, but is not limited thereto.

[0049] Further, the solvent of step (1) is a high-boiling solvent, such as mesitylene, 1,4-dioxane, and the like, but is not limited thereto.

[0050] Further, the amount of the solvent is 1 mL, but can be more or less.

[0051] Further, the concentration of the aqueous acetic acid solution of step (1) is 6 mol / L, but can be higher or lower.

[0052] The temperature of the vacuum drying of step (3) can be more or less. o C, and the drying time is 12 h.

[0053] Secondly, the present application provides a preparation method of an ordered and defect-free covalent organic framework film material (hereinafter referred to as COF film), which comprises: providing a liquid-phase reaction system containing an amine monomer, an aldehyde monomer, a catalyst, and a solvent, wherein the amine monomer and the aldehyde monomer both contain a triazine structural unit; subjecting the liquid-phase reaction system to a solvothermal reaction, so as to grow and form an ordered and defect-free covalent organic framework film material.

[0054] In one embodiment, the amine monomer includes 1,3,5-tris(4-aminophenyl)triazine (TAPT) or 1,3,5-tris(4-aminophenyl)benzene (TAPB), but is not limited thereto.

[0055] In one embodiment, the aldehyde monomer includes 1,3,5-tris(4-formylphenyl)triazine (TFPT) or 1,3,5-tris(p-formylphenyl)benzene (TFPB), but is not limited thereto.

[0056] In one embodiment, the catalyst includes an aqueous acetic acid solution with a concentration of 3-9 mol / L.

[0057] In one embodiment, the solvent includes a high-boiling solvent with a boiling point of 75-180 o C, for example, can include a combination of one or more of mesitylene, 1,4-dioxane, ethanol, and o-dichlorobenzene.

[0058] In one embodiment, the concentration of the amine monomer in the liquid-phase reaction system is 1-4 mmol / L.

[0059] In one embodiment, the concentration of the aldehyde monomer in the liquid-phase reaction system is 1-4 mmol / L.

[0060] In one embodiment, the temperature of the reaction is 80~150 o C, preferably 100~150 o C, for 3~7 days.

[0061] In one embodiment, the preparation method comprises: contacting the liquid phase reaction system with a base film, and allowing the liquid phase reaction system to undergo the solvothermal reaction, thereby growing the ordered defect-free covalent organic framework film material on the base film.

[0062] Further, the material of the base film includes polyimide, and is not limited thereto.

[0063] In one embodiment, the preparation method further comprises: after the reaction is completed, washing the obtained film material with ethanol and / or methanol, and storing in deionized water.

[0064] In a more specific embodiment, the preparation method can specifically comprise: under a sealed environment, allowing a uniform mixed reaction system comprising amine monomers, aldehyde monomers, acetic acid aqueous solution and solvent to react at 80~150 o C for 3~7 days, to obtain a rhombic pore-shaped two-dimensional covalent organic framework film material.

[0065] Further, the preparation method can comprise the following steps: (1) adding amine monomers and aldehyde monomers to a certain amount of solvent to prepare a solution, and adding a certain amount of acetic acid aqueous solution.

[0066] (2) placing the liquid phase reaction system prepared in step (1) in a hydrothermal kettle, and transferring to a constant temperature oven to heat to 85°C, and incubating for 3 days to complete the solvothermal reaction.

[0067] (3) after the solvothermal reaction is completed, after the reaction container is cooled to room temperature, the obtained COFs film is washed with ethanol and methanol and immersed in deionized water.

[0068] Further, the amount of the solvent in step (1) is 20 mL, but can also be more or less.

[0069] Further, the concentration of the acetic acid aqueous solution in step (1) is 6 mol / L, but can also be higher or lower.

[0070] For example, to prepare a TT-COF film in situ on a polyimide (CPI) support (i.e., the aforementioned base film) by a solvothermal synthesis, amine monomer 1,3,5-tris(4- aminophenyl)triazine and aldehyde monomer 1,3,5-tris(4-formylphenyl)triazine can be added to a 100 mL Teflon container, followed by 20 mL of a mixture of mesitylene / 1,4-dioxane. The mixture is sonicated for 3 min, followed by the addition of 50 μL of 6 M AcOH as a catalyst. The CPI substrate is inserted horizontally into a self-made rack with the front face facing down. The Teflon container is placed in a stainless steel autoclave and heated at 85 °C for 3 days. After the reaction is completed, the COF film is cooled to room temperature, washed thoroughly with ethanol and methanol, soaked in tetrahydrofuran for one hour to remove unreacted monomers, and then immersed in deionized water for storage before further testing. o The reaction is carried out at a constant temperature of 85 °C for 72 hours under C conditions. After the reaction is completed, the resulting COF film material is naturally cooled to room temperature, removed, and washed repeatedly with anhydrous ethanol to completely remove residual monomers and reaction byproducts. Finally, the prepared COF film is stored in deionized water for use. This method successfully realizes the uniform growth of the four two-dimensional COF films on the CPI substrate by precisely controlling the reaction temperature, time, and monomer ratio. The resulting film material has a regular pore arrangement and excellent interface bonding strength.

[0071] For example, to prepare a TT-COF film in situ on a polyimide (CPI) support (i.e., the aforementioned base film) by a solvothermal synthesis, amine monomer 1,3,5-tris(4- aminophenyl)triazine and aldehyde monomer 1,3,5-tris(4-formylphenyl)triazine can be added to a 100 mL Teflon container, followed by 20 mL of a mixture of mesitylene / 1,4-dioxane. The mixture is sonicated for 3 min, followed by the addition of 50 μL of 6 M AcOH as a catalyst. The CPI substrate is inserted horizontally into a self-made rack with the front face facing down. The Teflon container is placed in a stainless steel autoclave and heated at 85 °C for 3 days. After the reaction is completed, the COF film is cooled to room temperature, washed thoroughly with ethanol and methanol, soaked in tetrahydrofuran for one hour to remove unreacted monomers, and then immersed in deionized water for storage before further testing.

[0072] With reference to such a method, TB-COF, BT-COF, and BB-COF films can also be prepared.

[0073] The present application provides an ordered and defect-free covalent organic framework film material, which is prepared by a method for preparing the ordered and defect-free covalent organic framework film material.

[0074] Further, the film material comprises a two-dimensional covalent organic framework material having a triazine structure, which has a long-range ordered crystalline structure and a uniform pore size distribution. In one embodiment, the specific surface area of the two-dimensional covalent organic framework material (TT-COF) is 1521 m 2 / g, and the pore size is 2.2 nm.

[0075] In one embodiment, the specific surface area of the two-dimensional covalent organic framework material (TB-COF) is 1205 m 2 / g, and the pore size is 2.3 nm.

[0076] In one embodiment, the specific surface area of the two-dimensional covalent organic framework material (BT-COF) is 408 m 2 / g, and the pore size is 2.3 nm.

[0077] In one embodiment, the specific surface area of the two-dimensional covalent organic framework material (BB-COF) is 165 m 2 / g, and the pore size is 2.4 nm.

[0078] The application also provides a method for regulating interlayer force of an ordered and defect-free covalent organic framework film material, which comprises: at least by adjusting the types of amine monomers and / or aldehyde monomers in a liquid phase reaction system, so as to regulate the interlayer force of the ordered and defect-free covalent organic framework film material, when the liquid phase reaction system is subjected to a solvothermal reaction to form the ordered and defect-free covalent organic framework film material. The liquid phase reaction system comprises amine monomers, aldehyde monomers, a catalyst and a solvent, and the amine monomers and the aldehyde monomers both contain triazine structural units.

[0079] In one embodiment, the method comprises: contacting the liquid phase reaction system with a base film, and making the liquid phase reaction system subjected to the solvothermal reaction, so as to grow and form the ordered and defect-free covalent organic framework film material on the base film, and the material of the base film comprises polyimide.

[0080] The application also provides an application of the ordered and defect-free covalent organic framework film material in organic solvent nanofiltration (OSN).

[0081] In the application of OSN, the film-forming property of the TT-COF film containing triazine units is superior to that of the BB-COF film not containing triazine units.

[0082] Specifically, the two-dimensional covalent organic framework TT-COF film material containing triazine structural units can separate small-sized drug molecules and organic solvents at room temperature, the methanol flux thereof can reach 18 Lm -2 h -1 bar -1 , can effectively intercept dye molecules greater than 400 Da, with an interception rate of >90%; the separation performance thereof is unchanged in multiple cycles, and the above-mentioned film material can withstand an organic solvent intrusion pressure of 2 bar.

[0083] The application further provides an organic solvent nanofiltration method, comprising: subjecting an organic solvent to nanofiltration treatment by using the ordered defect-free covalent organic framework film material.

[0084] Compared with a two-dimensional covalent organic framework BB-COF film material without a triazine structural unit, the TT-COF film material with the triazine structural unit exhibits significantly enhanced molecular interception performance and more excellent molecular selective separation capacity.

[0085] The technical solutions of the application are further described below in combination with the accompanying drawings and several embodiments.

[0086] The method for testing the solvent permeability and the molecular interception rate of the TT-COF film in the following embodiments of the application comprises: testing under 0.15 MPa using a dead-end filtration device with an effective filtration area of 1.54 cm 2 . The solvent permeability (P, L m -2 h -1 bar -1 ) is calculated by the following equation:

[0087] wherein V (L) is the volume of the feed solution; A is the effective area (m 2 ) of the COFs film; is the filtration interval; is the applied pressure.

[0088] The rejection rate is calculated by the following equation: R = (1 - Cp / Cf) x 100% wherein Cf and Cp are the dye concentrations in the feed solution and the permeate, respectively. The concentration of the dye is determined using a Nanodrop 2000c UV-vis spectrophotometer.

[0089] Example 1 Preparation of monomer 1,3,5-tris(4-aminophenyl)triazine (TAPT): 4-aminobenzonitrile (600 mg, 5.0 mmol) and 10 mL chloroform were added to a 50 mL round-bottom flask, which was protected by argon replacement and cooled to 0 ℃. Then 2 mL trifluoromethanesulfonic acid was slowly added dropwise, and the reaction was continuously stirred at room temperature for 48 hours. After the reaction was completed, the reaction system was diluted with 20 mL distilled water, and neutralized to neutral with a sodium hydroxide solution (2 M). The precipitate was collected by filtration and washed with distilled water, and finally a light yellow TAPT solid (540 mg, yield 90%) was obtained. 1 H NMR (400 MHz, CDCl3) δ 8.35 (d, J= 8.7 Hz, 6H), 6.69 (d, J = 8.8 Hz, 6H), 5.92 (s, 6H).

[0090] Example 2 Preparation of monomer 1,3,5-tris(4-formylphenyl)triazine (TFPT): Synthesis of 2,4,6-tris(4-bromophenyl)-1,3,5-triazine: First, 0.91 g of 4-bromobenzonitrile (5 mmol) was dissolved in 12 mL of chloroform under nitrogen protection. Then, a mixture solution of 2.4 mL of trifluoromethanesulfonic acid (27 mmol) and 9 mL of chloroform was transferred to a constant pressure dropping funnel and slowly added to the reaction system at 0 °C. After the reaction solution was stirred vigorously at 25 °C for 24 hours, the reaction was quenched with saturated sodium bicarbonate solution at 0 °C. The product was collected by suction filtration and washed with water and methanol in turn, and vacuum dried at 80 °C overnight to obtain the white powder product (0.59 g, yield 65%). 1 H NMR (400 MHz, CDCl3) δ = 10.19 (s, 3H), 8.96 (d, J = 8.4 Hz, 6H), 7.71 (d, J = 8.4 Hz, 6H) Synthesis of 1,3,5-tris(4-formylphenyl)triazine (TFPT): Compound 2,4,6-tris(4-bromophenyl)-1,3,5-triazine (0.59 g, 1 mmol) was dissolved in 70 mL of anhydrous THF under nitrogen atmosphere, and n-butyllithium (2.4 mL, 6 mmol) was slowly added dropwise at -78 °C. After the reaction mixture was continuously stirred at -60 °C for 3 hours, it was cooled to -78 °C and 1 mL of DMF was slowly added, and then it was warmed to 25 °C and continuously stirred for 12 hours. After the reaction was quenched with 25 mL of 3 M hydrochloric acid, it was stirred for another hour. The product was collected by suction filtration and washed with water, petroleum ether and ethanol in turn, and dried at 80 °C under vacuum to obtain compound TFPT (0.14 g, yield 33%). 1 H NMR (400 MHz, CDCl3) δ = 10.19 (s, 3H), 8.96 (d, J = 8.4, 6H), 8.12 (d, J = 8.7, 6H).

[0091] Example 3 Preparation of two-dimensional covalent organic framework materials TT-COF and TB-COF: Into a 10 mL ampoule, 17.7 mg of 1,3,5-tris(4-aminophenyl) triazine (TAPT) or 17.6 mg of 1,3,5-tris(4-aminophenyl) benzene (TAPB) and 19.67 mg of 1,3,5-tris(4-formylphenyl) triazine (TFPT) were added, followed by 1 mL of a mixed solvent of mesitylene / 1,4-dioxane, and after ultrasonic dissolution, 0.2 mL of an aqueous acetic acid solution with a concentration of 6 mol / L was added. The reaction system was degassed by freezing-vacuum-thawing cycles three times in liquid nitrogen, and the reaction mixture was sealed in a constant-temperature oven and heated to 120 °C for 3 days. After the reaction was completed, it was cooled to room temperature, and the obtained mixture was centrifuged to collect the solid, which was then washed with tetrahydrofuran by centrifugation, and vacuum dried at 80 °C for 12 h to obtain COF powder. The yields of the two-dimensional covalent organic framework materials TT-COF and TB-COF were 89% and 93%, respectively. o C for 3 days. After the reaction was completed, it was cooled to room temperature, and the obtained mixture was centrifuged to collect the solid, which was then washed with tetrahydrofuran by centrifugation, and vacuum dried at 80 °C for 12 h to obtain COF powder. The yields of the two-dimensional covalent organic framework materials TT-COF and TB-COF were 89% and 93%, respectively. o C for 3 days. After the reaction was completed, it was cooled to room temperature, and the obtained mixture was centrifuged to collect the solid, which was then washed with tetrahydrofuran by centrifugation, and vacuum dried at 80 °C for 12 h to obtain COF powder. The yields of the two-dimensional covalent organic framework materials TT-COF and TB-COF were 89% and 93%, respectively.

[0092] Example 4 Preparation of two-dimensional covalent organic framework materials BT-COF and BB-COF Into a 10 mL ampoule, 17.7 mg of 1,3,5-tris(4-aminophenyl) triazine (TAPT) or 17.6 mg of 1,3,5-tris(4-aminophenyl) benzene (TAPB) and 19.67 mg of 1,3,5-tris(4-formylphenyl) triazine (TFPT) were added, followed by 1 mL of a mixed solvent of mesitylene / 1,4-dioxane, and after ultrasonic dissolution, 0.2 mL of an aqueous acetic acid solution with a concentration of 6 mol / L was added. The reaction system was degassed by freezing-vacuum-thawing cycles three times in liquid nitrogen, and the reaction mixture was sealed in a constant-temperature oven and heated to 120 °C for 3 days. After the reaction was completed, it was cooled to room temperature, and the obtained mixture was centrifuged to collect the solid, which was then washed with tetrahydrofuran by centrifugation, and vacuum dried at 80 °C for 12 h to obtain COF powder. The yields of the two-dimensional covalent organic framework materials TT-COF and TB-COF were 89% and 93%, respectively. o C for 3 days. After the reaction was completed, it was cooled to room temperature, and the obtained mixture was centrifuged to collect the solid, which was then washed with tetrahydrofuran by centrifugation, and vacuum dried at 80 °C for 12 h to obtain COF powder. The yields of the two-dimensional covalent organic framework materials TT-COF and TB-COF were 89% and 93%, respectively. o C for 3 days. After the reaction was completed, it was cooled to room temperature, and the obtained mixture was centrifuged to collect the solid, which was then washed with tetrahydrofuran by centrifugation, and vacuum dried at 80 °C for 12 h to obtain COF powder. The yields of the two-dimensional covalent organic framework materials TT-COF and TB-COF were 89% and 93%, respectively.

[0093] Example 5 Preparation of cross-linked polyimide (CPI) base film The original polyimide (PI) base film was prepared by a non-solvent induced phase separation (NIPS) method: PI powder was vacuum dried at 80 °C overnight to remove absorbed water, and then the PI was dissolved in a mixed solvent of 5.125 wt% of polyethylene glycol 400 and 76.875 wt% of N-methyl-2-pyrrolidone (NMP) at 80 °C. The PI solution was then poured into a Teflon mold, and the solvent was allowed to evaporate at room temperature to obtain a PI base film. The PI base film was then placed in a vacuum oven at 80 °C for 12 h to remove the residual solvent. N- a mixture of dimethylpyrrolidinone to form an 18 wt% polymer solution, then the solution was used with mechanical stirring at 60 °C for 24 h and degassed overnight at room temperature to remove air bubbles. To prepare the PI support, the solution was knife-casted on a non-woven cloth using a 200 pm high blade, which was immediately immersed in deionized water to induce pores. The PI support was washed with isopropanol three times and then immersed in a solution of isopropanol containing 5 wt% hexanediamine. It was kept at room temperature for 24 h to crosslink the pores. Afterwards, the resulting CPI support was thoroughly washed with isopropanol to remove excess hexanediamine and stored in isopropanol before use.

[0094] Example 6 Preparation of two-dimensional covalent organic framework material TT-COF films: TT-COF films were prepared by solvothermal synthesis grown in situ on CPI supports: Monomers 1,3,5-tris(4-aminophenyl)triazine (TAPT) and 1,3,5-tris(4-formylphenyl)triazine (TFPT) (1 : 1) were added to a 100 mL Teflon container, followed by the addition of 20 mL of a mixture of mesitylene / dioxane (1 : 1). The mixture was sonicated for 3 min, followed by the addition of 50 pL of 6 M AcOH as a catalyst. The CPI substrate was inserted horizontally into a self-made rack with the front face facing down. The Teflon container was placed in a stainless steel autoclave and heated at 85 °C for 3 days. After the reaction was completed, it was cooled to room temperature, and the obtained COF film was thoroughly washed with ethanol to remove unreacted monomers, then immersed in deionized water for storage before further testing.

[0095] Example 7 Preparation of two-dimensional covalent organic framework material TB-COF films: TB-COF films were prepared by solvothermal synthesis grown in situ on CPI supports: Monomers 1,3,5-tris(4-aminophenyl)benzene (TAPB) and 1,3,5-tris(4-formylphenyl)triazine (TFPT) (1 : 1) were added to a 100 mL Teflon container, followed by the addition of 20 mL of a mixture of mesitylene / dioxane (1 : 1). The mixture was sonicated for 3 min, followed by the addition of 50 pL of 6 M AcOH as a catalyst. The CPI substrate was inserted horizontally into a self-made rack with the front face facing down. The Teflon container was placed in a stainless steel autoclave and heated at 85 °C for 3 days. After the reaction was completed, it was cooled to room temperature, and the obtained COF film was thoroughly washed with ethanol to remove unreacted monomers, then immersed in deionized water for storage before further testing.

[0096] Example 8 Preparation of two-dimensional covalent organic framework material BT-COF films: A BT-COF film was prepared by solvothermal synthesis in situ growth on CPI support: monomers 1,3,5-tris(4-aminophenyl) triazine (TAPT) and 1,3,5-tris(4-formylphenyl) benzene (TFPB) (1:1) were added to a 100 mL Teflon container, then 20 mL of a mixed solvent of mesitylene / dioxane (1:1) was added. The mixture was ultrasonically treated for 3 min, then 50 μL of 6 M AcOH was added as a catalyst. The CPI substrate was horizontally inserted into a self-made shelf with the front face facing down. The Teflon container was placed in a stainless steel autoclave and heated at 85 ℃ for 3 days. After the reaction was completed, it was cooled to room temperature, and the obtained COF film was thoroughly washed with ethanol to remove unreacted monomers, then immersed in deionized water for storage before further testing.

[0097] Example 9 Preparation of a two-dimensional covalent organic framework material BB-COF film: A BB-COF film was prepared by solvothermal synthesis in situ growth on CPI support: monomers 1,3,5-tris(4-aminophenyl) benzene (TAPB) and 1,3,5-tris(4-formylphenyl) benzene (TFPB) (1:1) were added to a 100 mL Teflon container, then 20 mL of a mixed solvent of mesitylene / dioxane (1:1) was added. The mixture was ultrasonically treated for 3 min, then 50 μL of 6 M AcOH was added as a catalyst. The CPI substrate was horizontally inserted into a self-made shelf with the front face facing down. The Teflon container was placed in a stainless steel autoclave and heated at 85 ℃ for 3 days. After the reaction was completed, it was cooled to room temperature, and the obtained COF film was thoroughly washed with ethanol to remove unreacted monomers, then immersed in deionized water for storage before further testing.

[0098] Example 10 Film-forming property test of the two-dimensional covalent organic framework material COF film in this experiment: TT-COF and BB-COF films were prepared by solvothermal synthesis in situ growth on CPI support. The steps are shown in Example 6 (monomer concentration is 1.25 mmol / L), and the reaction was heated at 85 ℃ for 5 min, 15 min, 30 min, 1 h, 3 h, 6 h, 12 h, and 24 h. After the reaction was completed, it was cooled to room temperature, and the obtained COF film was thoroughly washed with ethanol to remove unreacted monomers, then immersed in deionized water for storage before further testing.

[0099] Example 11 This example mainly tests the performance of the two-dimensional covalent organic framework material COF film: OSN performance was carried out using a dead-end filtration setup with an effective filtration area of 1.54 cm 2 All the membranes were tested at room temperature at an operating pressure of 2 bar. Prior to the permeation test, the membranes were pressurized for at least 10 min until a steady state was reached. The OSN performance was tested using a drug molecule methanol solution (50 mg L -1 ) as the feed solution. All the experiments were repeated at least 3 times using independent membranes to obtain reliable permeability and rejection values.

[0100] Structural analysis and performance characterization: The monomer 1,3,5-tri(4-aminophenyl)triazine obtained in Example 1 and Example 2 of the present application was subjected to nuclear magnetic hydrogen spectrum test, and the two-dimensional covalent organic framework materials TT-COF, TB-COF, BT-COF, and BB-COF obtained in Example 3 of the present application were subjected to infrared spectrum characterization, X-ray powder diffraction, nitrogen adsorption-desorption test, scanning electron microscope, and transmission electron microscope, respectively, to characterize their structure, crystallinity, specific surface area, pore size distribution particle, and morphology. The two-dimensional covalent organic framework membrane materials TT-COF, TB-COF, BT-COF, and BB-COF membranes obtained in Example 6 of the present application were subjected to scanning electron microscope test, and the two-dimensional covalent organic framework membrane materials TT-COF, TB-COF, BT-COF, and BB-COF membranes obtained in Example 6 of the present application were subjected to methanol solvent permeability test, various drug molecule rejection rate test, different viscosity solvent permeability test, and mixed drug molecule selective rejection test, and the characterization results are shown in Figures 1-21 .

[0101] As shown in Figure 1 is the nuclear magnetic hydrogen spectrum of the monomer 1,3,5-tri(4-aminophenyl)triazine of the present application. 1 H NMR (400MHz, CDCl3) δ 8.35 (d, J = 8.7 Hz, 6H), 6.69 (d, J = 8.8 Hz, 6H), 5.92 (s, 6H).

[0102] As shown in Figure 2 is the nuclear magnetic hydrogen spectrum of the monomer 1,3,5-tri(4-aminophenyl)triazine of the present application. 1 H NMR (400MHz, CDCl3) δ = 10.19 (s, 3H), 8.96 (d, J = 8.4, 6H), 8.12 (d, J = 8.7, 6H).

[0103] As shown inFigures 3a-3d The infrared spectra of the two-dimensional covalent organic framework materials TT-COF, TB-COF, BT-COF, and BB-COF obtained in Examples 3 and 4 are shown respectively. The results show that the disappearance of the characteristic peaks of amino (-NH2) in the amine monomer and carbonyl (C=O) in the aldehyde monomer, and the appearance of imine (C=N) bonds, prove the successful preparation of the two-dimensional covalent organic framework materials.

[0104] like Figure 4 These are the thermogravimetric curves of the two-dimensional covalent organic framework materials TT-COF, TB-COF, BT-COF, and BB-COF obtained in Examples 3 and 4 of this invention. The results show that TT-COF, TB-COF, BT-COF, and BB-COF materials have good thermal stability, and the decomposition temperature increases with the increase of the number of triazine units.

[0105] like Figures 5a-5b The figure shows the nitrogen adsorption-desorption isotherm and pore size distribution curves of the obtained two-dimensional covalent organic framework material. The results indicate that the prepared two-dimensional covalent organic framework material has a porous structure. The specific surface area of ​​TT-COF is 1521 m². 2 / g, pore size distribution concentrated at 2.2 nm; TB-COF specific surface area is 1205 m² / g. 2 / g, pore size distribution concentrated at 2.3 nm; BT-COF specific surface area is 408 m² / g. 2 / g, pore size distribution concentrated at 2.3 nm; BB-COF specific surface area is 165 m² / g. 2 / g, with pore size distribution concentrated at 2.4 nm.

[0106] like Figures 6a-6b As shown, the powder X-ray diffraction pattern of the obtained two-dimensional covalent organic framework material and its AA and AB packing simulations are presented. The experimental results are consistent with the theoretical simulation results of AA. The results indicate that the prepared sample has good crystallinity.

[0107] like Figure 7 These are X-ray powder diffraction patterns of the two-dimensional covalent organic framework materials TT-COF, TB-COF, BT-COF, and BB-COF obtained in Examples 3-4 of this invention. (Angle range 2θ) = The Bragg equation calculation results (10-30°) show that the interlayer spacing decreases as the number of triazine units increases.

[0108] Fig. 8(a)-(d) are scanning electron microscope images of the two-dimensional covalent organic framework materials TT-COF, TB-COF, BT-COF, and BB-COF obtained in Examples 3-4, respectively. The results show that the morphology of TT-COF is uniform rod-like, the morphology of TB-COF is uniform ball-stick-like, and the morphology of BT-COF is uniform spherical.

[0109] Fig. 9 is a transmission electron microscope image of the two-dimensional covalent organic framework materials TT-COF, TB-COF, and BT-COF obtained in Examples 3-4. The results show that the pore size of TT-COF, TB-COF, and BT-COF is consistent with the theoretical results.

[0110] Fig. 10 is a scanning electron microscope image of the surface and cross-section of the CPI base film obtained in Example 5. The results show that the surface and cross-section of the base film are irregularly distributed with large holes.

[0111] Figs. 11(a)-(d) are scanning electron microscope images of the surface of the two-dimensional covalent organic framework film material TT-COF film obtained in Example 6 at monomer concentrations of 1 mmol / L, 1.5 mmol / L, 2.5 mmol / L, and 4 mmol / L, respectively. The results show that the TT-COF film surface forms a dense, complete, and defect-free COF film.

[0112] Figs. 12(a)-(d) are scanning electron microscope images of the surface of the two-dimensional covalent organic framework film material TB-COF film obtained in Example 7 at monomer concentrations of 1 mmol / L, 1.5 mmol / L, 2.5 mmol / L, and 4 mmol / L, respectively. The results show that the TB-COF film surface forms a dense, complete, and defect-free COF film.

[0113] Figs. 13(a)-(d) are scanning electron microscope images of the surface of the two-dimensional covalent organic framework film material BT-COF film obtained in Example 8 at monomer concentrations of 1 mmol / L, 1.5 mmol / L, 2.5 mmol / L, and 4 mmol / L, respectively. The results show that the BT-COF film surface forms a dense, complete, and defect-free COF film.

[0114] Figs. 14(a)-(d) are scanning electron microscope images of the surface of the two-dimensional covalent organic framework film material BB-COF film obtained in Example 9 at monomer concentrations of 1 mmol / L, 1.5 mmol / L, 2.5 mmol / L, and 4 mmol / L, respectively. The results show that the BB-COF film surface forms a dense, complete, and defect-free COF film.

[0115] As Figures 15a-15dare scanning electron microscope images of the 2.5 mmoL / L two-dimensional covalent organic framework film material TT-COF, TB-COF, BT-COF, and BB-COF film cross-sections obtained in Example 6-Example 9 of the present application. The results show that as the number of triazine units increases, the COF film thickness increases.

[0116] As Figures 16a-16b are scanning electron microscope images of the 2.5 mmoL / L two-dimensional covalent organic framework film material TT-COF, BB-COF obtained at different synthesis times in Example 10 of the present application. The results show that TT-COF has formed a visible COF layer on the surface at 1 h, while BB-COF has formed at 6 h. It can be seen that TT-COF is faster to form a film on the plane.

[0117] As Figure 17 is a plot of the methanol permeability of the two-dimensional covalent organic framework film material TT-COF, TB-COF, BT-COF, and BB-COF film obtained in Example 11 of the present application as a function of monomer concentration. The results show that as the monomer concentration increases, the methanol flux of the four COF films decreases; as the number of triazine units increases, the methanol flux of the COF film decreases. It shows that as the interlayer force increases, the interlayer distance decreases, and the solvent flux decreases.

[0118] As Figure 18 is a performance test plot of the two-dimensional covalent organic framework film material TT-COF, TB-COF, BT-COF, and BB-COF film obtained in Example 11 of the present application with a monomer concentration of 2.5 mmoL / L for different molecular weight drug molecules. The results show that the TT-COF film first effectively retains the drug molecule tetracycline (>90%) at 1.5 mmoL / L; BB-COF cannot retain the drug molecules tested, due to poor film-forming properties, low thickness, and other reasons.

[0119] As Figure 19 is a plot of the drug molecule rifampicin retention rate of the two-dimensional covalent organic framework film material TT-COF, TB-COF, BT-COF, and BB-COF film obtained in Example 11 of the present application as a function of monomer concentration. The results show that, except for the BB-COF film, the remaining COF films can effectively retain the rifampicin molecules (>90%) at a concentration of 2.5 mmoL / L.

[0120] As Figure 20is the UV chart of selective interception of tetracycline / rifampicin (1:1) mixed solution in methanol by 2.5 mmol / L concentration of two-dimensional covalent organic framework membrane material TT-COF, TB-COF, BT-COF and BB-COF membrane obtained in embodiment 11 of the present application. The results show that TT-COF and TB-COF membranes can effectively intercept tetracycline and rifampicin, BT-COF membrane can only effectively intercept rifampicin, and BB-COF cannot effectively intercept the above molecules.

[0121] As Figure 21 is the flux test chart of TT-COF membrane for different viscosity solvents obtained in embodiment 11 of the present application. The results show that with the increase of solvent viscosity, the flux of TT-COF membrane for the solvent decreases and shows a linear relationship.

[0122] In addition, the present inventors have also carried out tests with other raw materials, process operations and process conditions described in the present specification in reference to the foregoing embodiments, and all ideal results have been obtained.

[0123] The above embodiments of the present application not only systematically illustrate that the triazine unit can effectively regulate the interlayer force of the COF membrane through its rigid planar structure and π-π stacking effect by the intramolecular regulation strategy, but also regulate the interlayer force to prepare a complete and ordered COF membrane without defects, which provides a new theoretical basis for in-depth understanding of the multi-dimensional film forming mechanism of the COF membrane. At the same time, it provides important molecular engineering guidance for designing COF separation membrane materials considering flux and separation performance. This research not only provides a new idea for the rational design of COF membrane materials, but also opens up a new way for the development of efficient and stable organic solvent nanofiltration membranes, and has important application value in the field of fine chemical separation, drug purification and the like.

[0124] Aspects, embodiments, features, and examples of the present application should be considered illustrative in all aspects and are not intended to limit the present application, the scope of which is defined only by the claims. Other embodiments, modifications, and uses will be apparent to those skilled in the art without departing from the spirit and scope of the claimed application.

[0125] The use of titles and sections in the present application does not mean limitation of the present application; each section can be applied to any aspect, embodiment or feature of the present application.

[0126] Throughout the schemes of the present disclosure, where a composition is described as having, comprising, or including a particular component, or where a process is described as having, comprising, or including a particular process step, it is contemplated that a composition of the present teachings also consists essentially of, or consists of, the recited components, and a process of the present teachings also consists essentially of, or consists of, the recited process steps. Various other changes, omissions, and / or additions can be made to the elements of the described embodiments without departing from the spirit and scope of the present disclosure. Further, many modifications can be made to adapt a particular situation or material to the teachings of the present disclosure without departing from the scope of the present disclosure. Thus, the present disclosure is not intended to be limited to the particular disclosed embodiments used to exemplify the present disclosure, but the present disclosure is intended to encompass all embodiments falling within the scope of the appended claims. Furthermore, unless specifically stated, any use of the terms first, second, etc. does not indicate any order or importance, but rather the terms first, second, etc. are used to distinguish one element from another.

Claims

1. A method of preparing a class of ordered, defect-free covalent organic framework film materials, characterized in that, The application relates to a preparation method of an ordered defect-free covalent organic framework film material. The application provides a liquid-phase reaction system containing amine monomers, aldehyde monomers, a catalyst and a solvent, wherein the amine monomers and the aldehyde monomers contain different numbers of triazine structural units; and the liquid-phase reaction system is subjected to a solvothermal reaction to grow the ordered defect-free covalent organic framework film material. The amine monomers include 1,3,5-tris (4-aminophenyl) triazine or 1,3,5-tris (4-aminophenyl) benzene, and the aldehyde monomers include 1,3,5-tris (4-formylphenyl) triazine or 1,3,5-tris (p-formylphenyl) benzene.

2. The method of claim 1, wherein: The catalyst includes an acetic acid aqueous solution with a concentration of 3-9 mol / L. The concentration of the amine monomers in the liquid-phase reaction system is 1-4 mmol / L. and / or, the solvent comprises a high boiling solvent of C o C. The concentration of the aldehyde monomers in the liquid-phase reaction system is 1-4 mmol / L. The reaction temperature is 80-150 DEG C, and the reaction time is 3-7 days. The preparation method includes the following steps: contacting the liquid-phase reaction system with a base film, and making the liquid-phase reaction system subjected to the solvothermal reaction to grow the ordered defect-free covalent organic framework film material on the base film, wherein the material of the base film includes polyimide. The solvent includes a combination of one or more of mesitylene, 1,4-dioxane, ethanol and o-dichlorobenzene.

3. The method of claim 2, wherein: The application further relates to the following steps:

4. The production method according to claim 1, characterized by, After the reaction is completed, the obtained film material is washed with ethanol and / or methanol and is stored in deionized water. The film material is prepared by the method in any one of claims 1-4.

5. An ordered, defect-free covalent organic framework film material characterized by: The film material contains a two-dimensional covalent organic framework material with a triazine structure, and the two-dimensional covalent organic framework material has a long-range ordered crystal structure and a uniform pore size distribution.

6. The ordered-defect-free covalent organic framework film material of claim 5, wherein: The application relates to a preparation method of an ordered defect-free covalent organic framework film material. The specific surface area of the two-dimensional covalent organic framework material is 1521 m 2 / g, and the pore size is 2.2 nm. Alternatively, the specific surface area of the two-dimensional covalent organic framework material is 1205 m 2 / g, and the pore size is 2.3 nm, Alternatively, the specific surface area of the two-dimensional covalent organic framework material is 408 m 2 / g, and the pore size is 2.3 nm, Alternatively, the specific surface area of the two-dimensional covalent organic framework material is 165 m 2 / g, and the pore size is 2.4 nm.

7. A method for regulating interlayer forces of ordered defect-free covalent organic framework film materials, characterized in that, When the liquid-phase reaction system is subjected to a solvothermal reaction to form the ordered defect-free covalent organic framework film material, the interlayer force of the ordered defect-free covalent organic framework film material is regulated by at least adjusting the types of amine monomers and / or aldehyde monomers in the liquid-phase reaction system. The liquid-phase reaction system contains amine monomers, aldehyde monomers, a catalyst and a solvent, wherein the amine monomers and the aldehyde monomers contain different numbers of triazine structural units. The amine monomers include 1,3,5-tris (4-aminophenyl) triazine (TAPT) or 1,3,5-tris (4-aminophenyl) benzene (TAPB), and the aldehyde monomers include 1,3,5-tris (4-formylphenyl) triazine (TFPT) or 1,3,5-tris (p-formylphenyl) benzene (TFPB).

8. The method of claim 1, wherein: The catalyst includes an acetic acid aqueous solution with a concentration of 3-9 mol / L. The concentration of the amine monomers in the liquid-phase reaction system is 1-4 mmol / L. and / or, the solvent comprises a high boiling point solvent having a boiling point of 75 to 180 o C. The concentration of the aldehyde monomers in the liquid-phase reaction system is 1-4 mmol / L. The reaction temperature is 80-150 DEG C, and the reaction time is 3-7 days. ​ and / or, the method comprises: contacting the liquid phase reaction system with a base film, and allowing the liquid phase reaction system to undergo the solvothermal reaction, thereby growing to form the ordered defect-free covalent organic framework film material on the base film, the material of the base film comprising polyimide.

9. Use of the ordered defect-free covalent organic framework film material according to any one of claims 5-6 in nanofiltration of organic solvents.

10. An organic solvent nanofiltration process characterized in that, comprising: nanofiltration treatment of an organic solvent with the ordered defect-free covalent organic framework film material according to any one of claims 5-6.

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