Ionic cross-linked porous polyimide polymer as well as preparation method and application thereof
By preparing ionic crosslinked porous polyimide polymers, the defects of existing catalysts in carbon dioxide cycloaddition reactions were solved, achieving efficient and environmentally friendly catalytic effects, simplifying the preparation process and reducing costs.
Patent Information
- Application Number
- CN202511198514.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-26
- Publication Date
- 2025-10-28
AI Technical Summary
Existing catalysts, such as metal complexes, ionic liquids, and traditional inorganic solid catalysts, suffer from problems such as metal loss, high cost, high viscosity, few active sites, and environmental pollution in carbon dioxide cycloaddition reactions. The alkylation process in Friedel-Crafts reactions is prone to causing environmental pollution.
Ionic crosslinked porous polyimide polymers were prepared by using 5-amino-2-(4-aminophenyl)benzimidazole and hexafluorodianhydride as raw materials, and acetic anhydride and pyridine as catalysts via quaternization. This method avoids the Friedel-Crafts reaction, and the preparation process is simple, environmentally friendly, and produces a permanent porous structure with a large specific surface area.
The prepared ionic crosslinked porous polyimide polymer has precise chloride ion active sites and a large specific surface area, which improves catalytic performance and adsorption capture performance. The reactants are in full contact with the active sites, which significantly improves the efficiency and selectivity of carbon dioxide cycloaddition reaction.
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Figure CN120842573A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of polymer materials technology, specifically relating to an ion-crosslinked porous polyimide polymer, its preparation method, and its application. Background Technology
[0003] Currently, catalysts used for this reaction, such as metal complexes, ionic liquids, and traditional inorganic solids, each have their own drawbacks. Metal complex catalysts suffer from problems such as easy metal loss, high cost, and difficulty in recovery; ionic liquid catalysts have high viscosity, complex synthesis, and high cost; and traditional inorganic solid catalysts have few active sites and require harsh reaction conditions.
[0004] In existing technologies, porous organic polymer materials capable of carbon dioxide cycloaddition include metal-organic frameworks (MOFs), covalent organic frameworks (COFs), polyionic liquids (PILs), and ionic porous organic polymers (HCPs). Compared to other types of polymeric organic materials, ionic porous organic polymer (HCP) catalysts have advantages such as simple preparation, low cost, and readily available starting materials. Furthermore, the preparation of HCPs involves direct synthesis via the Friedel-Crafts reaction, eliminating the need for noble metal coupling catalysts or specific functionalized building blocks. However, the Friedel-Crafts reaction involves alkylation of the reactants, a process using highly corrosive AlCl3, which generates HCl waste gas and large amounts of acidic waste liquid, potentially causing environmental pollution. Therefore, this application proposes a method for preparing ionic crosslinked porous polyimide polymers without the Friedel-Crafts reaction, along with its preparation method. Summary of the Invention
[0005] In view of this, and to solve the problems mentioned in the background art, the purpose of this invention is to provide an ionic crosslinked porous polyimide polymer, its preparation method, and its application. First, using 5-amino-2-(4-aminophenyl)benzimidazole and hexafluorodianhydride as raw materials, acetic anhydride as a dehydrating agent, and pyridine as a catalyst to promote dehydration, an ionic linear polymer is obtained through an oil bath reaction under nitrogen protection. Then, using the ionic linear polymer as a raw material and 1,4-dichlorobenzyl as a crosslinking agent, an ionic crosslinked porous polyimide polymer is prepared via a quaternization method. The entire process does not require a Friedel-Crafts reaction, and the obtained polymer has a permanent porous structure and a large specific surface area.
[0006] To achieve the above objectives, the present invention provides the following technical solution:
[0007] 1. A method for preparing an ionic crosslinked porous polyimide polymer, comprising:
[0008] S1. Using 5-amino-2-(4-aminophenyl)benzimidazole and hexafluorodianhydride as raw materials, an ionic linear polymer was prepared.
[0009] S2. The ionic linear polymer prepared in step S1 and 1,4-dichlorobenzyl are placed in N,N-dimethylformamide, stirred at 80°C for 24 h and refluxed to obtain a hypercrosslinked ionic polymer solution.
[0010] S3. The hypercrosslinked ionic polymer solution was filtered and washed until neutral, then purified by Soxhlet extraction and vacuum dried to obtain the ionic crosslinked porous polyimide polymer.
[0011] Preferably, in step S1, the preparation of the ionic linear polymer includes: adding the raw materials and catalyst to an N-methylpyrrolidone solvent under nitrogen protection, reacting for 6 hours in an oil bath at 100°C to 110°C, washing the reaction product with deionized water, and drying under vacuum to obtain the ionic linear polymer.
[0012] Preferably, the mass ratio of 5-amino-2-(4-aminophenyl)benzimidazole to hexafluorodianhydride in the raw materials is 1:2.
[0013] Preferably, the catalyst comprises acetic anhydride and pyridine in a mass ratio of 1 to 2:1.
[0014] Preferably, the vacuum drying of the ionic linear polymer is performed at 80°C for 12 hours.
[0015] Preferably, in step S2, the mass ratio of the ionic linear polymer to 1,4-dichlorobenzyl is 1:4.
[0016] Preferably, in step S3, the hypercrosslinked ionomer solution is filtered and washed until neutral using deionized water and methanol.
[0017] Preferably, in step S3, the product is purified by Soxhlet extraction with methanol and dichloromethane for 24 hours.
[0018] Preferably, in step S3, the polymer is vacuum dried at 50°C for 24 hours to obtain an ionic crosslinked porous polyimide polymer.
[0019] 2. An ionic crosslinked porous polyimide polymer having the structure shown in the following formula:
[0020] .
[0021] 3. The application of an ionicly cross-linked porous polyimide polymer in the carbon dioxide cycloaddition reaction. Specifically, the ionicly cross-linked porous polyimide polymer is used as a catalyst for the carbon dioxide cycloaddition reaction.
[0022] Compared with the prior art, the present invention has the following advantages:
[0023] The ionic crosslinked porous polyimide polymer of the present invention not only has precise chloride ion active sites, but also has a permanent porous structure and a large specific surface area, which enables reactants to fully contact the active sites, thereby significantly improving its catalytic performance and adsorption-capture performance.
[0024] The preparation method of the present invention can synthesize ionic cross-linked porous polyimide polymers containing chloride ion active sites without Friedel-Crafts reaction, and has the advantages of simple reaction process, low cost and environmental friendliness.
[0025] The preparation method of this invention specifically employs an ordered two-step heating and dissolution reaction. The quaternization reaction precisely targets the reaction sites, and Friedel-Crafts alkylation is omitted, reducing potential errors and variables during the preparation process and improving the repeatability and reliability of the polymer (catalyst). Furthermore, the simplified preparation process also means lower preparation costs, making this polymer (catalyst) more economical for industrial applications. Attached Figure Description
[0026] Figure 1 Scanning electron microscope (SEM) image and EDSMapping spectrum of the ionic crosslinked porous polyimide polymer prepared for the example;
[0027] Figure 2 XPS spectra of the ionic crosslinked porous polyimide polymer prepared for the example. Detailed Implementation
[0028] To further understand the content of this invention, a detailed description of the invention is provided in conjunction with the accompanying drawings and embodiments. The structures, proportions, sizes, etc., depicted in the accompanying drawings are merely for illustrative purposes and to aid those skilled in the art, and are not intended to limit the implementation conditions of the invention. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in proportions, or adjustments to size, without affecting the effects and objectives of the invention, should still fall within the scope of the technical content disclosed in this invention. Furthermore, terms such as "upper," "lower," "left," "right," and "middle" used in this specification are merely for clarity and not intended to limit the scope of implementation. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the invention. It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein.
[0029] Example
[0030] A method for preparing an ionic crosslinked porous polyimide polymer, comprising:
[0031] S1. Using 5-amino-2-(4-aminophenyl)benzimidazole and hexafluorodianhydride in a mass ratio of 1:2 as raw materials, and acetic anhydride and pyridine in a mass ratio of 1.96:1 as catalysts, the raw materials and catalysts were added to N-methylpyrrolidone solvent under nitrogen protection and stirred at room temperature for 6 hours to obtain a 0.09-0.1 mol / L mixture solution. The mixture solution was reacted in an oil bath at 100-110℃ for 6 hours. The reaction product was washed with deionized water and dried under vacuum at 80℃ for 12 hours to obtain an ionic linear polymer.
[0032] The specific reaction in this step is as follows:
[0033] .
[0034] S2. The ionic linear polymer prepared in step S1 and 1,4-dichlorobenzyl are placed in N,N-dimethylformamide at a mixing mass ratio of 1:4, stirred at 80°C for 24 h and refluxed to obtain a hypercrosslinked ionic polymer solution.
[0035] The specific reaction in this step is as follows:
[0036] .
[0037] S3. The super-crosslinked ionic polymer solution was filtered and washed until neutral using 1000 mL of deionized water and methanol. Then, it was purified by Soxhlet extraction with methanol and dichloromethane for 24 h and vacuum drying at 50 °C for 24 h to obtain a light brown solid ionic crosslinked porous polyimide polymer.
[0038] By testing the ionic crosslinked porous polyimide polymer prepared in the above examples, the following results were obtained: Figure 1 The scanning electron microscope image and EDS mapping spectrum shown are as follows: Figure 2 The XPS spectrum shown:
[0039] Figure 1 Scanning electron microscopy images show that the ionic cross-linked porous polyimide catalyst has a size of about 20 μm, an irregular morphology, a porous layered structure, and a large specific surface area.
[0040] Figure 1 The EDS mapping spectrum shows the presence of Cl - exist;
[0041] Figure 2 In the left image of the XPS spectrum: 399.88 eV represents the characteristic peak of N in benzimidazole; 531.90 eV represents the characteristic peak of O in hexafluorodianhydride; 688.12 eV represents the characteristic peak of F in hexafluorodianhydride; and 284.84 eV represents the characteristic peak of CH3.
[0042] Figure 2 In the right image of the XPS spectrum: 200.45 eV represents Cl2p 1\2 Characteristic peak; 199.42 eV indicates Cl2p 3\2 Characteristic peak; 198.60 eV indicates Cl - 2p 3\2 Characteristic peak; 197.64 eV indicates Cl - 2p 1\2 Characteristic peaks.
[0043] In summary, this demonstrates the successful preparation of ionic crosslinked porous polyimide polymers.
[0044] The ionic crosslinked porous polyimide polymer prepared above was applied to catalyze the cycloaddition reaction of epichlorohydrin with carbon dioxide. The reaction conditions were: 60 mg of ionic crosslinked porous polyimide polymer, 1.2 MPa of CO2, a reaction temperature of 130 °C, and a reaction time of 9 h, ultimately yielding cyclic carbonates. The conversion rate was 99.6%, the yield was 99.5%, and the selectivity was 99.9% during the reaction.
[0045] In summary, this embodiment synthesizes an ionic cross-linked porous polyimide polymer containing chloride ion active sites without the Friedel-Crafts reaction. This polymer not only possesses precise chloride ion active sites but also a permanent porous structure and a large specific surface area, allowing for sufficient contact between the reactants and the active sites, thereby significantly improving its catalytic performance and adsorption-capture capabilities. Specifically, the ionic cross-linked porous polyimide polymer (catalyst) containing chloride ion active sites exhibits highly efficient catalytic activity in the carbon dioxide cycloaddition reaction, significantly improving the reaction rate and product selectivity.
[0046] Note that the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the concept of the present invention. The scope of the present invention is determined by the scope of the appended claims.
Claims
1. A method for preparing an ionic crosslinked porous polyimide polymer, characterized in that, include: S1. Using 5-amino-2-(4-aminophenyl)benzimidazole and hexafluorodianhydride as raw materials, an ionic linear polymer was prepared. S2. The ionic linear polymer prepared in step S1 and 1,4-dichlorobenzyl are placed in N,N-dimethylformamide, stirred at 80°C for 24 h and refluxed to obtain a hypercrosslinked ionic polymer solution. S3. The hypercrosslinked ionic polymer solution was filtered and washed until neutral, then purified by Soxhlet extraction and vacuum dried to obtain the ionic crosslinked porous polyimide polymer.
2. The method for preparing an ionic crosslinked porous polyimide polymer according to claim 1, characterized in that, In step S1, the preparation of the ionic linear polymer includes: The raw materials and catalyst were added to N-methylpyrrolidone solvent under nitrogen protection and reacted in an oil bath at 100℃~110℃ for 6h. The reaction product was washed with deionized water and dried under vacuum at 80℃ for 12h to obtain the ionic linear polymer.
3. The method for preparing an ionic crosslinked porous polyimide polymer according to claim 2, characterized in that: The mass ratio of 5-amino-2-(4-aminophenyl)benzimidazole to hexafluorodianhydride in the raw materials is 1:
2.
4. The method for preparing an ionic crosslinked porous polyimide polymer according to claim 2, characterized in that: The catalyst comprises acetic anhydride and pyridine in a mass ratio of 1 to 2:
1.
5. The method for preparing an ionic crosslinked porous polyimide polymer according to claim 1, characterized in that: In step S2, the mass ratio of the ionic linear polymer to 1,4-dichlorobenzyl is 1:
4.
6. The method for preparing an ionic crosslinked porous polyimide polymer according to claim 1, characterized in that: In step S3, the hypercrosslinked ionomer solution is filtered and washed until neutral using deionized water and methanol.
7. The method for preparing an ionic crosslinked porous polyimide polymer according to claim 1, characterized in that: In step S3, the product is purified by Soxhlet extraction with methanol and dichloromethane for 24 hours.
8. The method for preparing an ionic crosslinked porous polyimide polymer according to claim 1, characterized in that: In step S3, the polymer is dried under vacuum at 50°C for 24 hours to obtain an ionic cross-linked porous polyimide polymer.
9. The ionotropic crosslinked porous polyimide polymer prepared by the preparation method according to any one of claims 1-8, characterized in that, It has the structure shown in the following formula: 。 10. The ionically cross-linked porous polyimide polymer prepared by the preparation method according to any one of claims 1-8, or the ionically cross-linked porous polyimide polymer according to claim 9, characterized in that: The ionic cross-linked porous polyimide polymer was used as a catalyst.