A crystalline imide covalent organic framework film material and preparation method thereof

Abstract

The present invention belongs to the field of polymer film preparation, and discloses a crystalline imide covalent organic framework film material and a preparation method thereof, and a synthesis method of an imide COFs film generated by a dehydration condensation reaction of an anhydride compound and an amine compound under solvent thermal conditions. The COFs polymer film prepared by the present invention has good light transmittance and strong stability in the long wavelength range (>700 nm), and has good potential application prospects, such as application in ultraviolet protection.

Description

Technical Field

[0001] The invention belongs to the field of polymer film preparation, and in particular relates to a method for preparing an imide COFs film material. Background Art

[0002] COFs are a type of porous crystalline polymer material with adjustable structural functions, large specific surface area, and ordered pore structure. They have application prospects in gas storage, energy storage, photocatalysis, analytical chemistry, and other fields. In the field of material synthesis, the preparation of membrane materials has always attracted much attention. Previously, people synthesized COFs membrane materials mostly by using the phase interface synthesis method or the in-situ diffusion growth method. However, the phase interface synthesis method usually requires two solvents, and the reaction itself needs to be fast or the reaction reversible. The in-situ diffusion film growth method can only be achieved under high vacuum conditions and requires that one of the monomers has a certain volatility. For monomers that are difficult to volatilize or cannot volatilize, this method is not suitable for synthesis. There is currently almost no membrane synthesis for imide COFs materials.

[0003] In the present invention, a simple synthesis method is proposed, which can realize the synthesis of crystalline imide COFs film materials by only controlling the ratio and amount of the solvent. Compared with the interfacial synthesis, the synthesis process of this method is simpler, and the film material can be prepared only in a single liquid phase. In addition, the diffusion method for synthesizing film materials usually uses imide materials, and the reaction speed is fast, and it is easy to form COFs film materials with surface doped opaque powder particles; compared with the in-situ diffusion growth synthesis method, the imide COFs film synthesized by the solvent thermal method of the present invention does not require a high vacuum diffusion furnace, and the synthesis equipment is simple. And the film material synthesized by this method has a certain light transmittance, which enhances its potential application potential. The synthesis of this method is simple and feasible, and has good practical significance. Summary of the invention

[0004] The present invention discloses a method for preparing a light-transmissive and crystalline imide COFs film, which has innovative significance and potential application prospects.

[0005] In order to achieve the above-mentioned invention object, the present invention adopts the following technical scheme:

[0006] The invention discloses a preparation method of an imide COFs film, which is synthesized by dehydration condensation reaction of anhydride and amine compounds under solvent thermal conditions.

[0007] The preparation method of the PI-COF:

[0008] According to a certain stoichiometric ratio, two monomers: pyromellitic anhydride and amine compounds such as 1,3,5-tri(4-aminophenyl)benzene are weighed separately, placed in an ampoule, and mixed solvents such as mesitylene, N-methylpyrrolidone, and isoquinoline are added. The mixture is frozen and vacuumed in a liquid nitrogen bath, flame-sealed, and placed in an oven for solvothermal reaction. The oven program is heated from room temperature to 120-250°C, and the temperature is kept for 1-5 days. The crude product of imide COFs film is obtained by solvothermal method. The reaction product is washed, extracted with THF, and the product is collected and dried in a vacuum drying oven overnight to obtain a transparent imide COFs film material.

[0009] The preferred volume ratio of the solvent is mesitylene:N-methylpyrrolidone:isoquinoline=0.4:0.4:0.2.

[0010] The preferred reaction temperature is 150°C.

[0011] Application: The imide COFs film material is used in the field of ultraviolet protection.

[0012] The beneficial effects of the present invention are:

[0013] 1) The present invention uses a solvent thermal reaction to synthesize a class of transparent crystalline imide COFs thin film materials using pyromellitic dianhydride and amine monomers, thereby realizing the synthesis of large-area imide COFs thin film materials, and has the characteristics of low reaction cost and safe and reliable production process.

[0014] 2) The equipment and chemical reagents used in the present invention are easy to obtain, the synthesis process is simple to operate, the synthesis process conditions are simple, the practicability is strong, and it is easy to promote and apply. The synthesized COF film material can absorb ultraviolet light with a wavelength less than 420nm, and at the same time has a transmittance of more than 70% for visible light with a wavelength greater than 650nm, and can be used as a UV protection material. The imide COFs film material synthesized by the solvent thermal method of the present invention has good chemical stability and has innovative significance for the synthesis of imide films. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the synthesis of the imide covalent organic framework thin film materials PMDA-TAPB and PMDA-TATTA in the present invention;

[0016] Figure 2 is an X-ray diffraction pattern of the imide COFs thin film material of the present invention;

[0017] Figure 3 is the infrared absorption diagram of the imide COFs thin film material in the present invention;

[0018] Figure 4It is a transmittance diagram of the imide COFs thin film material in the 400-1000nm band of light;

[0019] Figure 5 This is a thermogravimetric test diagram of the imide COFs film material of the present invention;

[0020] Figure 6 The stability test results of the imide COFs film of the present invention are as follows, and the X-ray diffraction pattern of the film material obtained after being immersed in a chemical solution;

[0021] Figure 7 This is a real picture of the imide COFs thin film material PMDA-TATTA in the present invention under a microscope. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the present invention clearer and easier to understand, the present invention is further described in detail below in conjunction with embodiments. It should be understood that the specific implementation described here is only used to explain the present invention and is not used to limit the present invention.

[0023] A method for preparing a crystalline imide covalent organic framework film material, under solvent-thermal synthesis conditions, synthesizes a mesoporous imide COFs film material with a pore size of 2-4nm, the imide COFs film material has a transmittance of more than 60% at a wavelength greater than 600nm; and a transmittance of more than 70% at a wavelength greater than 650nm.

[0024] Furthermore, the preparation method specifically comprises the following steps:

[0025] 1) Mix the acid anhydride and the amine monomer in a molar ratio of 3:2 in an ampoule bottle, and add the mixed solvent;

[0026] 2) subjecting the mixture obtained in step 1) to ultrasonic treatment for 3-10 minutes to make the system uniformly mixed;

[0027] 3) Using a flame gun to seal the ampoule under vacuum conditions;

[0028] 4) placing the sealed ampoule into an oven or muffle furnace and reacting at 120-250° C. for 1-5 days;

[0029] 5) The product obtained in step 4) is washed with acetone and THF, and dried to obtain a crystalline imide COFs thin film material.

[0030] Furthermore, the acid anhydride is pyromellitic dianhydride.

[0031] Furthermore, the amine monomer is any one of 1,3,5-tris(4-aminophenyl)benzene (CAS 118727-34-7) or 2,4,6-tris(4-aminophenyl)-1,3,5-triazine.

[0032] Furthermore, the mixed solvent consists of mesitylene, N-methylpyrrolidone and isoquinoline.

[0033] Furthermore, the volume ratio of mesitylene, N-methylpyrrolidone and isoquinoline in the mixed solvent is 1-xy:x:y, wherein x≥0.5, 0.02≤y≤0.5, and 1-xy>0 is satisfied.

[0034] Furthermore, the volume ratio of mesitylene, N-methylpyrrolidone and isoquinoline in the mixed solvent is 4:4:2. Furthermore, the volume of the ampoule, the volume of the added mixed solvent and the amount of the reactant anhydride are mutually restricted, wherein the ratio of the volume of the ampoule to the volume of the mixed solvent is 500-50; the ratio between the volume of the mixed solvent / 0.1 mL and the mass of the anhydride / 1 mg is 1-5.

[0035] Example 1 Preparation of imide COF film PMDA-TAPB:

[0036] Pyromellitic anhydride (3.3 mg, 0.015 mmol) and 1,3,5-(p-aminophenyl)benzene (3.5 mg, 0.01 mmol) were placed in a 10 mL ampoule, and mesitylene (0.15 mL), N-methylpyrrolidone (0.15 mL) and isoquinoline (0.03 mL) were added. Ultrasonic treatment was performed for 3 min, and then the ampoule was flame-sealed under vacuum (~10 mbar), and then the ampoule was placed in an oven at 150 ° C for 5 days. The crude product was washed 3 times with acetone and THF, and the product was collected. The product was vacuum dried overnight to obtain a transparent light yellow film PMDA-TAPB.

[0037] Example 2 Preparation of imide COF film PMDA-TATTA:

[0038] Pyromellitic anhydride (3.3 mg, 0.015 mmol) and 2,4,6-tris(4-aminophenyl)-1,3,5-triazine (3.5 mg, 0.01 mmol) were placed in a 10 mL ampoule, and mesitylene (0.15 mL), N-methylpyrrolidone (0.15 mL) and isoquinoline (0.03 mL) were added. Ultrasonic treatment was performed for 3 min, and then the ampoule was flame-sealed under vacuum (~10 mbar), and then the ampoule was placed in an oven at 150 ° C for 5 days. The crude product was washed 3 times with acetone and THF, and the product was collected. The product was vacuum dried overnight to obtain a transparent light yellow film PMDA-TATTA.

[0039] Figure 2 Figure 3 is the X-ray diffraction pattern of the imide COFs film. The obvious peak near 2.8° in the figure is the characteristic diffraction peak of PI-COF, proving the successful synthesis of PI-COF.

[0040] Figure 3 This is the infrared absorption diagram of the imide COFs film material. In the infrared absorption, it can be seen that the imide ring synthesized with pyromellitic anhydride as the raw material is at 1780cm -1 and 1720cm -1 Characteristic absorption peak at .

[0041] Figure 4 The UV absorption graph of the imide COFs film material measured at 400-1000nm shows that the two COFs film materials have less absorption in the long-wave visible light range, and the visible light transmittance is greater than 70% at wavelengths greater than 650nm; in the short wavelength, ultraviolet region, the absorption is relatively strong, and the transmittance is basically 0 at wavelengths less than 420nm. Therefore, this type of COFs film material can be used in UV protection equipment, such as snow glasses and other eyewear equipment that have certain requirements for light transmittance.

[0042] Figure 5 Thermogravimetric testing of the synthesized imide COFs film showed that the COFs film material still maintained more than 90% of its weight at 500°C, indicating that the material has good thermal stability.

[0043] Figure 6 To test the chemical stability of the synthesized imide COFs film, the COF film material was immersed in 1mol / L hydrochloric acid, 1mol / L NaOH solution, and 1mol / L NaCl solution for 24 hours, and then removed to wash away the surface residual substances. Then the crystallinity of the COFs film was tested. It can be seen that PMDA-TAPB and PMDA-TATTA still maintained good crystallinity after immersion for 24 hours, proving their good chemical stability.

[0044] Figure 7 These are photos of the synthesized imide COFs film under a microscope, where (a), (b), and (c) are local images of the COF film. It can be seen that the film surface is flat and smooth, and the overall light transmittance is uniform; (d) shows that the writing on the background paper can be seen through the COF film, indicating that the film has good light transmittance.

[0045] Although the content of the present invention has been described in detail through the above preferred embodiments, it should be appreciated that the above description should not be considered as a limitation of the present invention. After reading the above content, it is obvious for those skilled in the art to make various modifications and substitutions of the present invention. Therefore, the protection scope of the present invention should be limited by the appended claims.

Claims

1. A method for preparing a crystalline imide covalent organic framework thin film material, characterized in that: Under solvent-thermal synthesis conditions, a mesoporous imide COFs thin film material with a pore size of 2-4 nm was synthesized, and the transmittance of the imide COFs thin film material was greater than 60% at a wavelength greater than 600 nm; and the transmittance was greater than 70% at a wavelength greater than 650 nm. The following steps are involved: 1) Mix the acid anhydride and the amine monomer in a molar ratio of 3:2 in an ampoule bottle, and add the mixed solvent; 2) subjecting the mixture obtained in step 1) to ultrasonic treatment for 3-10 min to make the system uniformly mixed; 3) Using a flame gun to seal the ampoule under vacuum conditions; 4) Place the sealed ampoule in an oven or muffle furnace and react at 120~250 ºC for 1-5 days; 5) washing the product obtained in step 4) with acetone and THF, and drying to obtain a crystalline imide COFs thin film material; The acid anhydride is pyromellitic dianhydride; The amine monomer is any one of 1,3,5-tris(4-aminophenyl)benzene or 2,4,6-tris(4-aminophenyl)-1,3,5-triazine; The mixed solvent is composed of mesitylene, N-methylpyrrolidone and isoquinoline; the volume ratio of mesitylene, N-methylpyrrolidone and isoquinoline in the mixed solvent is 4:4:2; The volume of the ampoule, the volume of the added mixed solvent and the amount of the reactant anhydride are mutually restrictive, wherein the ratio of the volume of the ampoule to the volume of the mixed solvent is 500-50; the ratio between the volume of the mixed solvent / 0.1 mL and the mass of the anhydride / 1 mg is 1-5.

2. The imide COFs thin film material obtained according to the preparation method of claim 1.

3. The imide COFs film material according to claim 2 is used in the field of ultraviolet protection.

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