A polyimide material with high solubility and high gas separation performance, and its preparation method and application

Abstract

The present invention provides a polyimide material with high solubility and high gas separation performance, and its preparation method and application. The polyimide material with high solubility and high gas separation performance includes a modified polyimide polymer, an antioxidant, and a fluoropolymer. Calculated based on the total mass content of 100%, the mass fraction of the modified polyimide polymer in the polyimide material with high solubility and high gas separation performance is 75 - 85%, the mass fraction of the antioxidant is 5 - 8%, and the balance is the fluoropolymer. The preparation method is to mix the modified polyimide polymer, the antioxidant, and the fluoropolymer, perform melt blending at 200 - 300 °C, and extrude and pelletize using a twin-screw extruder to obtain the polyimide material with high solubility and high gas separation performance. This polyimide material has good solubility and gas separation performance.

Description

Technical Field

[0001] The present invention relates to the technical field of gas separation membrane material preparation, and particularly relates to a polyimide material with high solubility and high gas separation performance, and a preparation method and application thereof. Background Art

[0002] Polyimide is a type of high molecular polymer containing imide groups in the main chain. It was first produced by Bogert and Renshaw in 1908. In 1955, DuPont in the United States reacted pyromellitic dianhydride with diamine to obtain a high molecular weight polyimide. Due to its excellent thermal stability, mechanical properties, and good solvent resistance, it has attracted the attention of a large number of researchers. Since then, polyimide has developed rapidly, and products such as polyimide fibers, films, resins, and adhesives have been successively introduced and widely used in multiple fields such as gas separation, microelectronics, photovoltaics, aerospace, automotive, and solar cells.

[0003] The main chain of the polyimide molecule contains a large number of imide rings and aromatic rings, and there is a strong conjugation effect between the rings. The molecular chain has strong rigidity and strong intermolecular forces, which endow polyimide with many excellent properties, such as good thermal properties, mechanical properties, dimensional stability, and adjustable optical properties. However, the rigid structure of the polyimide main chain and the strong interaction between molecular chains also bring certain disadvantages, making it difficult to dissolve and melt, resulting in difficult forming and processing, and its application is greatly limited. Therefore, improving the solubility of polyimide is an important research direction. Currently, the reported methods for improving the solubility of polyimide mainly include introducing flexible groups, non - coplanar structures, and hyperbranched structures into the polyimide backbone structure, but its solubility still needs to be further improved. At the same time, the molecular structure of polyimide determines its gas separation performance. Some researchers have improved the solubility by introducing flexible groups in polyimide, but this has weakened the gas separation performance, which has certain deficiencies.

[0004] Therefore, in order to better meet the application requirements in gas separation membranes, it is necessary to provide a polyimide material with high solubility and high gas separation performance. Summary of the Invention

[0005] Aiming at the problems existing in the prior art, the purpose of the present invention is to provide a polyimide material with high solubility and high gas separation performance.

[0006] To achieve this purpose, the technical solution of the present invention is as follows:

[0007] The present invention provides a polyimide material with high solubility and high gas separation performance. The polyimide material with high solubility and high gas separation performance includes a modified polyimide polymer, an antioxidant, and a fluoropolymer.

[0008] In some embodiments of the present invention, based on the total mass content of the polyimide material having high solubility and high gas separation property being 100%, the mass fraction of the modified polyimide polymer in the polyimide material having high solubility and high gas separation property is 75 - 85%, the mass fraction of the antioxidant is 5 - 8%, and the balance is a fluoropolymer.

[0009] In some embodiments of the present invention, the antioxidant is antioxidant 1010 or antioxidant 168.

[0010] In some embodiments of the present invention, the fluoropolymer is polytetrafluoroethylene or polyvinylidene fluoride.

[0011] In some embodiments of the present invention, the modified polyimide polymer has the structure shown in Formula I below:

[0012]

[0013] Wherein, x is an integer from 1 to 3, y is an integer from 1 to 6, and * is the connection site of the repeating segment.

[0014] Furthermore, the preparation method of the modified polyimide polymer shown in Formula I includes the following steps:

[0015] (1) Add 2,4 - dinitrobromobenzene, 4 - cinnamylphenol, and anhydrous potassium carbonate into a solvent and mix. Under nitrogen protection, heat to 110 - 120 °C and react for 2 - 3 h, then continue to heat to 135 - 145 °C and react for 6 - 8 h. Cool to room temperature, and after filtration and rotary evaporation, separate and purify to obtain an intermediate product shown in Formula I - 1:

[0016]

[0017] (2) Add the intermediate product shown in Formula I - 1 and a reducing agent into a solvent, and carry out a constant - temperature reflux reaction. After the reaction is completed, remove the solvent to obtain an intermediate product shown in Formula I - 2:

[0018]

[0019] (3) Add the intermediate shown in Formula I-2, 5-[(1,3-dioxo-1,3-dihydro-2-benzofuran-5-yl)oxy]-1,3-dihydro-2-benzofuran-1,3-dione, and hexafluorodiacid anhydride into a solvent, stir at room temperature for 6-12 h, then add a catalyst and a water absorbent and react for 3-5 h. After the reaction is completed, filter and dry. The obtained product is the modified polyimide polymer shown in Formula I. The structure of 5-[(1,3-dioxo-1,3-dihydro-2-benzofuran-5-yl)oxy]-1,3-dihydro-2-benzofuran-1,3-dione is shown in Formula I-3:

[0020]

[0021] In some embodiments of the present invention, the molar ratio of 2,4-dinitrobromobenzene to 4-cinnamylphenol in step (1) is 1:1-2 (for example, it can be 1:1, 1:1.1, 1:2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:

[0022] 1.7, 1:1.8, 1:1.9, 1:2 or any value therebetween); the solvent is a mixture of toluene and N,N-dimethylacetamide, and the mass ratio of toluene to N,N-dimethylacetamide is 1:1.5-2 (for example, it can be 1:1.5, 1:1.6, 1:

[0023] 1.7, 1:1.8, 1:1.9, 1:2 or any value therebetween).

[0024] In some embodiments of the present invention, the solvent in step (2) is selected from N-methylpyrrolidone or N,N-dimethylformamide; the reducing agent is selected from aqueous hydrazine solution or aniline; the concentration of the aqueous hydrazine solution is 60-80 mg / mL (for example, it can be 60 mg / mL, 61 mg / mL, 62 mg / mL, 63 mg / mL, 64 mg / mL, 65 mg / mL, 66 mg / mL, 67 mg / mL, 68 mg / mL, 69 mg / mL, 70 mg / mL, 71 mg / mL, 72 mg / mL, 73 mg / mL, 74 mg / mL, 75 mg / mL, 76 mg / mL, 77 mg / mL, 78 mg / mL, 79 mg / mL, 80 mg / mL or any value therebetween); the temperature of the constant temperature reflux reaction is 90-120 °C (for example, it can be 90 °C, 95 °C, 100 °C, 105 °C, 110 °C, 115 °C, 120 °C or any value therebetween), and the reaction time is 2-4 h (for example, it can be 2 h, 2.5 h, 3 h, 3.5 h, 4 h or any value therebetween).

[0025] In some embodiments of the present invention, the molar ratio of the intermediate product represented by Formula I-2, 5-[(1,3-dioxo-1,3-dihydro-2-benzofuran-5-yl)oxy]-1,3-dihydro-2-benzofuran-1,3-dione, and hexafluorodiacid anhydride in step (3) is 2-8:1:1-3 (for example, it can be 2:1:1, 2:1:2, 2:1:3, 8:1:1, 8:1:2, 8:1:3 or any value therebetween); the solvent is N,N-dimethylacetamide or N-methylpyrrolidone; the catalyst is selected from one or a combination of N,N-dimethylethanolamine, trimethylamine, triethylamine, and dimethylethanolamine; the water absorbent is acetic anhydride.

[0026] A method for preparing a polyimide material with high solubility and high gas separation performance, characterized in that the method for preparing the polyimide material with high solubility and high gas separation performance is: mixing a modified polyimide polymer, an antioxidant, and a fluoropolymer, melt-blending at 200-300 °C, and extruding and pelletizing using a twin-screw extruder to obtain the polyimide material with high solubility and high gas separation performance.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The polyimide material with high solubility and high gas separation performance provided by the present invention, by adding a modified polyimide polymer, introduces a large side-chain structure into the polyimide molecular structure, increases the free volume of the polymer molecular structure space, enables the polyimide material to exhibit good solubility, and at the same time introducing a trifluoromethyl structure into the polyimide material can make it exhibit good lipophilicity, enabling the trifluoromethyl group to synergistically improve the solubility of the polyimide with the large side-chain structure.

[0029] (2) The polyimide material with high solubility and high gas separation performance provided by the present invention, by adding a modified polyimide polymer, the introduction of its large side-chain structure and trifluoromethyl group further breaks the stacking of the main chain, increases the permeability coefficient of the polymer, enables the material to have both good gas selectivity and gas permeability, can effectively separate CO2 / N2, CO2 / CH4, and O2 / N2, and enhances the interaction between the polymer and CO2, having good gas separation performance. Detailed Embodiments

[0030] The present invention will be described below in conjunction with specific embodiments. It should be noted that the following examples are examples of the present invention, only for illustrating the present invention, and not for limiting the present invention. Without departing from the gist or scope of the present invention, other combinations and various improvements within the concept of the present invention can be made.

[0031] In the following examples, the compounds and related reagents used can be purchased from the market. Among them, 2,4-dinitrobromobenzene (purity: 99%) was purchased from Shanghai Jiachen Chemical Co., Ltd., 4-cinnamylphenol (purity: 98%) was purchased from Shanghai Yuanye Bio-Technology Co., Ltd., 5-[(1,3-dioxo-1,3-dihydro-2-benzofuran-5-yl)oxy]-1,3-dihydro-2-benzofuran-1,3-dione, and hexafluorodiacid anhydride (CAS#: 1107-00-2) were purchased from Tianjin Zhongtai Material Technology Co., Ltd., hydrazine hydrate was purchased from Shandong Hengxin Chemical Co., Ltd., and polytetrafluoroethylene was purchased from Zhejiang Jusheng Fluorochemical Co., Ltd.

[0032] Preparation of Modified Polyimide Polymer 1

[0033] (1) Add 1 mol of 2,4-dinitrobromobenzene, 1 mol of 4-cinnamylphenol, and 10 g of anhydrous potassium carbonate to 1500 g of a solvent (the mass ratio of toluene and N,N-dimethylacetamide is 1:2) and mix. Under nitrogen protection, heat to 120 °C and react for 3 h, then continue to heat to 145 °C and react for 8 h. Cool to room temperature, and after filtration and rotary evaporation, separate and purify to obtain intermediate I-1, whose 1 The HNMR analysis results are as follows: 1 HNMR, (CDCl3, 500 MHz), 8.88 (S, 1H); 8.61 (d, 1H); 7.10 - 7.37 (m, 10H); 1.56 (S, 6H);

[0034] (2) Add 100 g of intermediate I-1 and 5 g of an 80 mg / ml hydrazine hydrate aqueous solution to 500 g of N,N-dimethylformamide, and react at a constant temperature of 120 °C for 4 h. After the reaction, remove N,N-dimethylformamide to obtain intermediate I-2, whose 1 The HNMR analysis results are as follows: 1 HNMR (DMSO, 500 MHz), 3.54 (d, 2H); 3.87 (d, 2H); 5.73 (S, 1H); 6.09 (d, 1H); 6.64 (d, 1H); 7.10 - 7.37 (m, 10H); 1.56 (S, 6H);

[0035] (3) Add 4 mol of intermediate I-2, 1 mol of 5-[(1,3-dioxo-1,3-dihydro-2-benzofuran-5-yl)oxy]-1,3-dihydro-2-benzofuran-1,3-dione, and 3 mol of hexafluorodiacid anhydride to 13.5 kg of N,N-dimethylacetamide, stir at room temperature for 12 h, then add 12 g of triethylamine and 120 g of acetic anhydride and react for 5 h. After the reaction, filter and dry. The resulting product is modified polyimide polymer 1. Perform infrared spectroscopy analysis on the product. At 3300 - 3500 cm-1 No obvious absorption peaks of amino or hydroxyl groups appeared nearby, indicating that the imidization degree was relatively complete during the polymerization process.

[0036] Preparation of Modified Polyimide Polymer 2

[0037] 10 mmol of m-phenylenediamine (purity 99%, purchased from J&K Scientific Ltd.) and 10 mmol of 4,4'-hexafluoroisopropylidene-phthalic anhydride (purity 99%, purchased from Clariant Chemicals (China) Co., Ltd.) were added to 250 g of N-methylpyrrolidone, stirred at room temperature for 12 h, then 1 g of triethylamine and 10 g of acetic anhydride were added and reacted for 5 h. After the reaction, filtration and drying were carried out. The obtained product was modified polyimide polymer 2. The product was analyzed by infrared spectroscopy. There was no absorption peak of hydroxyl stretching vibration at 3300 - 3400 cm -1 , indicating that the imidization of the polymer was relatively complete.

[0038] Preparation of Modified Polyimide Polymer 3

[0039] The difference from modified polyimide polymer 1 was only that hexafluorodiacid anhydride was not added during the preparation. The product was analyzed by infrared spectroscopy. No obvious absorption peaks of amino or hydroxyl groups appeared near 3300 - 3500 cm -1 , indicating that the imidization degree was relatively complete during the polymerization process.

[0040] Example 1

[0041] A polyimide material with high solubility and high gas separation performance. Based on the total mass content of 100%, the mass fraction of modified polyimide polymer 1 in the polyimide material with high solubility and high gas separation performance was 85%, the mass fraction of antioxidant 168 was 8%, and the balance was polytetrafluoroethylene.

[0042] Its preparation method was as follows: Modified polyimide polymer 1, antioxidant 168 and polytetrafluoroethylene were mixed and melt-blended at 250 °C, and then extruded and pelletized using a twin-screw extruder to obtain a polyimide material with high solubility and high gas separation performance.

[0043] Example 2

[0044] A polyimide material with high solubility and high gas separation performance. Based on the total mass content of 100%, the mass fraction of modified polyimide polymer 1 in the polyimide material with high solubility and high gas separation performance was 80%, the mass fraction of antioxidant 168 was 8%, and the balance was polytetrafluoroethylene.

[0045] The preparation method was the same as that of Example 1.

[0046] Example 3

[0047] A polyimide material with high solubility and high gas separation performance. Based on the total mass content being 100%, in the polyimide material with high solubility and high gas separation performance, the mass fraction of the modified polyimide polymer 1 is 75%, the mass fraction of antioxidant 168 is 8%, and the balance is polytetrafluoroethylene.

[0048] The preparation method is the same as that of Example 1.

[0049] Example 4

[0050] A polyimide material with high solubility and high gas separation performance. Based on the total mass content being 100%, in the polyimide material with high solubility and high gas separation performance, the mass fraction of the modified polyimide polymer 1 is 75%, the mass fraction of antioxidant 168 is 5%, and the balance is polytetrafluoroethylene.

[0051] The preparation method is the same as that of Example 1.

[0052] Comparative Example 1

[0053] The difference from Example 1 is that the modified polyimide polymer 1 is replaced by the modified polyimide polymer 2.

[0054] Comparative Example 2

[0055] The difference from Example 1 is that the modified polyimide polymer 1 is replaced by the modified polyimide polymer 3.

[0056] The polyimide materials with high solubility and high gas separation performance prepared in the above examples and comparative examples were subjected to performance tests. The test methods are as follows:

[0057] (1) Solubility: At room temperature, 10 mg of the polyimide material was weighed and dissolved in 1 mL of the solvent to be tested (N,N-dimethylacetamide (DMAC), N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), dimethyl sulfoxide (DMSO), tetrahydrofuran (THF) or chloroform (CHCl3)), and the dissolution situation was observed. The results are shown in Table 1. In the table, ++ indicates complete dissolution at room temperature, + indicates complete dissolution after heating, +- indicates partial dissolution, and -- indicates insoluble after heating;

[0058] (2) Gas separation performance: Test was carried out using a differential pressure method gas permeation instrument. The test results are shown in Table 2. Among them, P is the permeability coefficient, and α = P A / P B .

[0059] Table 1 Solubility test results

[0060]

[0061]

[0062] Table 2 Gas Separation Test Results

[0063]

[0064] From the comparison between Comparative Example 1 and Example 1, it can be seen that the modified polyimide polymer used in the polyimide material with high solubility and high gas separation prepared in Example 1 can exhibit good solubility in DMAC, DMF, NMP, DMSO, THF or CHCl3 by introducing a large side-chain structure. At the same time, it has a relatively high permeability and can maintain a relatively high gas selectivity coefficient. From the comparison between Comparative Example 2 and Example 1, it can be seen that the modified polyimide polymer used in the polyimide material with high solubility and high gas separation prepared in Example 1 can effectively improve the solubility of the polyimide material by introducing a trifluoromethyl structure into the main chain. While maintaining relatively high N2, CH4, O2, and CO2 permeability coefficients, it can also maintain a relatively high gas selectivity coefficient. By comprehensively comparing the test results of the above comparative examples and examples, it shows that the polyimide material with high solubility and high gas separation provided by the present invention improves the free volume of the polymer molecular structure space by introducing a large side-chain structure into the polyimide molecular structure, enabling the polyimide material to exhibit good dissolution performance. At the same time, introducing a trifluoromethyl structure into the polyimide material can make it exhibit good lipophilicity, enabling the trifluoromethyl to synergistically improve the solubility of the polyimide with the large side-chain structure. At the same time, it also breaks the stacking of the main chain, increases the permeability coefficient of the polymer, and maintains good gas separation performance.

[0065] The above embodiments are only for illustrating the technical concept and features of the present invention, and the purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it. It should not be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit and essence of the present invention should be covered within the protection scope of the present invention.

Claims

1. Application of a polyimide material with high solubility and high gas separation property in a gas separation membrane, characterized in that, The polyimide material includes a modified polyimide polymer, an antioxidant, and a fluoropolymer; Based on the total mass content of the polyimide material with high solubility and high gas separation property being 100%, the mass fraction of the modified polyimide polymer in the polyimide material with high solubility and high gas separation property is 75 - 85%, the mass fraction of the antioxidant is 5 - 8%, and the balance is the fluoropolymer; the fluoropolymer is polytetrafluoroethylene or polyvinylidene fluoride; the modified polyimide polymer has the structure shown in the following formula I: I Wherein, x is an integer from 1 to 3, y is an integer from 1 to 6, and * is the connection site of the repeating segment.

2. Use of the polyimide material with high solubility and high gas separation property according to claim 1 in a gas separation membrane, characterized in that, The antioxidant is antioxidant 1010 or antioxidant 168.

3. Use of the polyimide material having high solubility and high gas separation performance according to claim 1 in a gas separation membrane, characterized in that, The preparation method of the modified polyimide polymer shown in the formula I includes the following steps: (1) Add 2,4-dinitrobromobenzene, 4-cinnamylphenol, and anhydrous potassium carbonate into a solvent and mix. Under nitrogen protection, heat to 110 - 120 °C and react for 2 - 3 h, then continue to heat to 135 - 145 °C and react for 6 - 8 h. Cool to room temperature, and after filtration and rotary evaporation, separate and purify to obtain an intermediate product shown in formula I-1: I-1； (2) Add the intermediate product shown in formula I-1 and a reducing agent into a solvent, and carry out a constant-temperature reflux reaction. After the reaction ends, remove the solvent to obtain an intermediate product shown in formula I-2: I-2； (3) Add the intermediate product shown in formula I-2, 5-[(1,3-dioxo-1,3-dihydro-2-benzofuran-5-yl)oxy]-1,3-dihydro-2-benzofuran-1,3-dione, and hexafluorodiacid anhydride into a solvent, stir at room temperature for 6 - 12 h, then add a catalyst and a water absorbent and react for 3 - 5 h. After the reaction ends, carry out filtration and drying, and the obtained product is the modified polyimide polymer shown in formula I.

4. Use of the polyimide material with high solubility and high gas separation property according to claim 3 in a gas separation membrane, characterized in that, In step (1), the molar ratio of 2,4-dinitrobromobenzene to 4-cinnamylphenol is 1:1 - 2; the solvent is a mixture of toluene and N,N-dimethylacetamide, and the mass ratio of toluene to N,N-dimethylacetamide is 1:1.5 - 2; in step (2), the solvent is selected from N-methylpyrrolidone or N,N-dimethylformamide; the temperature of the constant-temperature reflux reaction is 90 - 120 °C, and the reaction time is 2 - 4 h; the reducing agent is an aqueous hydrazine solution; the concentration of the aqueous hydrazine solution is 60 - 80 mg / mL.

5. Use of the polyimide material with high solubility and high gas separation property according to claim 3 in a gas separation membrane, characterized in that, In step (3), the molar ratio of the intermediate product shown in formula I-2, 5-[(1,3-dioxo-1,3-dihydro-2-benzofuran-5-yl)oxy]-1,3-dihydro-2-benzofuran-1,3-dione, and hexafluorodiacid anhydride is 2 - 8:1:1 - 3; the solvent is N,N-dimethylacetamide or N-methylpyrrolidone; the catalyst is selected from one or a combination of N,N-dimethylethanolamine, trimethylamine, and triethylamine; the water absorbent is acetic anhydride.

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