Polyimide gas separation membranes and methods comprising dibasic amines containing the ddsq motif and their preparation

Abstract

The application discloses a diamine containing a DDSQ base element and a preparation method thereof, and belongs to the technical field of gas separation and purification. The preparation method of the diamine containing the DDSQ base element is suitable for synthesizing DSDQ functional molecules with different molecular structures and reaction activities, and meets the polymerization requirements. The preparation method of the polyimide gas separation membrane is as follows: firstly, a nitro aryl amine functional molecule is synthesized; then, the nitro aryl amine functional molecule is reacted with a DSDQ binary anhydride synthesized by using a disclosed technical solution to obtain a double-nitro compound containing the DSDQ; finally, the double-nitro compound is hydrogenated and reduced to obtain a target molecule, namely, a DSDQ diamine. The DSDQ diamine is condensed with a binary anhydride to obtain a polyamide acid precursor, and the polyamide acid precursor is cyclized and dehydrated to obtain a polyimide. Finally, the polyimide gas separation membrane containing the DSDQ base element is obtained by using a dissolving-tape casting method. The separation membrane still has stable gas permeability and relatively constant selectivity after physical aging for 300 days at room temperature, and has outstanding anti-aging performance.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of gas separation and purification, and particularly relates to a binary amine containing a DDSQ motif and a polyimide gas separation membrane and a method for preparing the same. BACKGROUND

[0002] In the 21st century, with the rapid development of global population and industry, the massive emission of greenhouse gases such as CO2 and CH4 has led to global warming. Global warming is a serious threat, not only causing glaciers to melt, sea levels to rise, and water resources to dry up, but also leading to the emergence of a series of new polar viruses, which seriously threaten human survival. In order to control the growth rate of global temperature, the double carbon target, i.e., "carbon peak" and "carbon neutrality", has emerged. At present, many developed countries have replaced traditional fossil energy with natural gas to achieve carbon peak, because the CO2 emission of burning natural gas is only 55% of that of burning coal and 70% of that of burning oil. Natural gas is a clean energy with abundant reserves and is renewable, but it often contains 2%-10% of CO2 in its original gas, which will cause a series of problems such as pipeline corrosion, decreased combustion heat value, and increased carbon emissions. Therefore, natural gas must be separated and purified before being burned. Compared with traditional gas purification methods such as cryogenic separation and pressure swing adsorption separation, membrane separation method does not require complex equipment, has the advantages of high energy efficiency, low cost, small equipment, flexible operation, and environmental friendliness, and can realize efficient separation under mild conditions. At present, membrane separation method has replaced high-energy consumption separation processes such as cryogenic separation and amine adsorption, and has been successfully applied in the fields of nitrogen enrichment, oxygen enrichment, hydrogen recovery, removal of acid gases (H2S, CO2, etc.) in natural gas, air and natural gas dehumidification, and has become a green separation method that has attracted much attention.

[0003] In the membrane separation device, the polymer membrane with micro-pores (PIM) is the most critical separation component. At present, the commercial separation membrane materials include cellulose (CA), polysulfone (PSF), polycarbonate (PC) and polyimide (PI) etc. In recent years, PI membrane has attracted more and more attention in the membrane separation industry due to its excellent mechanical stability, high heat resistance and good chemical medium corrosion resistance, especially its superior comprehensive physical properties can meet the gas separation and purification under complex conditions such as high pressure and high heat. Through a large number of studies, membrane separation expert Robeson pointed out that there is a mutual restriction problem between the gas separation flux and the selectivity of specific gas pairs of the polymer membrane in the gas separation process [Journal of Membrane Science, 1991, 62, 165-185; Journal of Membrane Science, 2008, 320, 390-400.], that is, the polymer membrane with high separation flux usually shows an undesirable gas pair selectivity, which is not conducive to high-efficiency separation. In addition, the permeability of the polymer separation membrane gradually decreases in the long-term separation process, while the selectivity is basically unchanged or only slightly improved, which will deteriorate the separation effect. And the removal of CO2 from methane is often completed under a pressure of 20 bar or even higher. High-pressure CO2 often swells the polymer skeleton, resulting in a decrease in CO2 / CH4 selectivity and plasticization, which also reduces the separation efficiency of the membrane. Through more than 20 years of development, scholars at home and abroad have been conducting continuous research work on the technical bottleneck of the mutual restriction between the separation flux and the selectivity of the gas pair of the polymer separation membrane, and the aging and plasticization problems existing in the separation process. However, there is a lack of effective solutions to inhibit plasticization and the aging decay of separation performance over time. SUMMARY

[0004] Technical problems to be solved:

[0005] In order to avoid the shortcomings of the prior art, and because the DDSQ functional molecule has significant steric hindrance, the polymerization activity is low, it is difficult to obtain a high molecular weight polyimide gas separation membrane by direct polymerization, and the free energy of the DDSQ functional molecule is low, which tends to aggregate or self-assemble in the polymer matrix and induce phase separation when the addition amount is high, thereby destroying the uniformity of the membrane material, etc. The present application provides a binary amine containing a DDSQ motif and a preparation method of a polyimide gas separation membrane and a method thereof. The present application develops a technical method for improving the polymerization activity of the DDSQ functional molecule by chain extension, which is suitable for synthesizing a series of DDSQ functional molecules with different molecular structures and reaction activities that can meet the polymerization requirements (molecular structure as shown in Figure 3The application discloses a kind of polyimide gas separation membrane material containing DDSQ base element, and the technical scheme is as follows: a kind of binary amine containing DDSQ base element, the molecular structure formula of the binary amine is as follows:

[0006] The technical scheme of the application is: a kind of binary amine containing DDSQ base element, the molecular structure formula of the binary amine is as follows:

[0007]

[0008] Wherein, R2 represents methyl or phenyl, R3 represents the residue in alkenyl anhydride, R4 represents the residue in product E, and Ph represents benzene ring.

[0009] A kind of binary amine containing DDSQ base element is prepared, and the specific steps are as follows:

[0010] Step 1: a reaction vessel equipped with magnetic sub and condenser is sequentially added with base compound, silane coupling agent, alcohol, deionized water; stirring is started and the system is heated, and when the temperature rises to 60-120 DEG C, reflux stirring reaction is continued for 10-30 h; when the system is cooled to 20-35 DEG C, the reaction system is filtered, the filter cake is washed with alcohol for 2-3 times, and the filter cake is dried in vacuum oven at 60-120 DEG C for 12-24 h to obtain white powder product F;

[0011] The molar ratio of the base compound to the silane coupling agent is 1:1-3.0, and the molar ratio of deionized water to the silane coupling agent is 1:0.2-2.0;

[0012] The solute content is controlled to be 15wt%-40wt%;

[0013] Step 2: product F is added to a three-necked flask equipped with magnetic sub, and tertiary amine compound, low-boiling-point solvent and dichlorosilane are sequentially added and stirring is started; sequentially reacting at-5-5 DEG C for 1-3 h and at 15-30 DEG C for 3-8 h, filtering, washing the filter cake with low-boiling-point solvent for 2-4 times, collecting the filtrate and concentrating, filtering, washing the filter cake with alcohol for 2-3 times and drying at 60-120 DEG C under vacuum for 12-24 h to obtain white powder product H;

[0014] The molar ratio of the product F to the tertiary amine compound is 1:2-5, and the molar ratio of the product F to dichlorosilane is 1:2-5;

[0015] The solute content is controlled to be 5wt%-25wt%;

[0016] Step 3: sequentially adding the product H, the alkenyl anhydride, the low-boiling-point solvent, and the Karstedt catalyst into a reaction container equipped with a magnetic bar, heating the reaction system to 60-120°C under an argon atmosphere for 24-72h; after cooling to 15-25°C, pouring the reaction liquid into alcohol and adding deionized water into the alcohol, suction-filtering, washing the filter cake with deionized water for 2-3 times, and vacuum drying at 80-160°C for 12-36h to obtain the D D S Q anhydride;

[0017] The molar ratio of the product H to the alkenyl anhydride is 1:5-8, and the volume fraction of the Karstedt catalyst in the reaction system is 0.01-0.1%;

[0018] The solute mass fraction is 15%-35%;

[0019] Step 4: sequentially adding the carbonic compound, the phenolic compound, the high-boiling-point solvent, the nitro compound D, and the phosphorus-containing stabilizer M into a reaction container equipped with mechanical stirring, stirring and heating the system under an argon atmosphere; when the temperature is increased to 80-160°C, continuing to stir for 15-30h;

[0020] The molar ratio of the carbonic compound to the phenolic compound is 1-1.5:1;

[0021] The molar ratio of the nitro compound D to the phenolic compound is 1:1-2.0;

[0022] The mass fraction of the phosphorus-containing stabilizer M is 0.5%-3.0%, and the solute content is controlled to be 20wt%-30wt%;

[0023] The sum of the mass percentages of the above components is 100%;

[0024] Step 5: when the system is cooled to 20-35°C, pouring the reaction system into deionized water, and precipitating a brown precipitate; suction-filtering, washing the filter cake with deionized water for 2-3 times, to obtain a crude product; recrystallizing the crude product, filtering to collect the filter cake, and drying in a vacuum oven at 60-120°C for 12-24h to obtain the product E;

[0025] Step 6: DDDSQ anhydride is added into a three-necked flask equipped with a water separator and a condenser reflux device, a carboxylic acid solvent G is added under argon atmosphere, and mechanical stirring is started, then product E and cyclohexane are added in sequence, and the system is heated to reflux; after refluxing for 5-12 h, the reaction system is slowly cooled to 20-35℃, the reaction solution is poured into distilled water, and the filter cake is washed with distilled water for 2-3 times; the filter cake is dried in a vacuum oven at 60-120℃ for 12-24 h to obtain powder product C;

[0026] The molar ratio of the DDDSQ anhydride to product E is 1:2;

[0027] The molar ratio of the product E to the carboxylic acid solvent G is 1:100-150;

[0028] The volume ratio of the cyclohexane to the carboxylic acid solvent G is 1:3-6;

[0029] Step 7: product C is dissolved in solvent J, palladium-carbon catalyst and phosphorus-containing stabilizer M are added, and the reaction system is placed in a high-pressure reaction kettle for reaction in a hydrogen atmosphere at room temperature for 5-25 h; during the reaction, the hydrogen pressure is maintained at 5-35 bar; after the reaction, the catalyst is filtered off, solvent J is removed by reduced pressure distillation, and the product is washed with toluene for 2-3 times and then dried in a vacuum oven at 60-120℃ for 12-24 h to obtain DDDSQ diamine;

[0030] The mass fraction of the solute is 10%-20%;

[0031] The volume fraction of the phosphorus-containing stabilizer M is 1%-2%;

[0032] The amount of the palladium-carbon catalyst added is determined according to 30-100 mg of catalyst corresponding to 1 mmol of nitro group.

[0033] In a further technical solution of the present application, the solvent J is any one or a combination of methanol, tetrahydrofuran, ethyl acetate, acetonitrile, dichloromethane, ethanol, N,N-dimethylformamide and N,N-dimethylacetamide.

[0034] A polyimide gas separation membrane prepared by using a diamine containing a DDDSQ motif, and the molecular structure is as follows:

[0035]

[0036] In the formula, the molar fraction of the DDDSQ diamine part is 10%-50%, the molar fraction of the diamine part is 0-40%, and the molar fraction of the dianhydride part is 50%; R1 represents a residue in the dianhydride, and R5 represents a residue in the diamine.

[0037] A method for preparing a polyimide gas separation membrane using a binary amine containing a DDSQ motif, the specific steps are as follows:

[0038] Step 1: A reaction vessel equipped with mechanical stirring is sequentially added with DDSQ binary amine, binary anhydride, binary amine and high boiling point solvent, argon protection, start stirring and cool the system; continue to stir for 10-15h when the system temperature is reduced to 0-10℃;

[0039] The molar ratio of the DDSQ binary amine, binary amine, binary anhydride is (1-x):x:1-1.05, wherein x is in the range of 0-0.9; the solid content is controlled in the range of 10wt%-30wt%.

[0040] Step 2: The temperature of the system is raised to 15-25℃, argon protection, dehydrating agent and catalyst are added, and stirring is continued for 12-15h;

[0041] Step 3: The temperature of the system is raised to 50-80℃, argon protection, continue to stir for 4-8h;

[0042] Step 4: When the system is cooled to 20-35℃, pour the reaction solution into an alcohol solution to precipitate fibrous solid product, filter and wash the filter cake with alcohol for 2-4 times, and dry the filter cake in a vacuum oven at 80-160℃ for 12-24h to obtain polymer R;

[0043] Step 5: Dissolve the polymer R in a low boiling point solvent, control the solid content in the range of 4wt%-15wt%, filter and cast on a previously adjusted horizontal glass plate; place the glass plate in a vacuum oven at 25-40℃ for 10-20h, then raise the temperature to 80-120℃ for 2-6h; after the temperature is reduced to 20-35℃, take out the film to obtain a polyimide gas separation film containing a DDSQ motif.

[0044] A further technical solution of the present application is: in step 2, the molar ratio of the dehydrating agent to the binary anhydride is 3-5:1; the molar ratio of the catalyst to the binary anhydride is 1-2:1.

[0045] A further technical solution of the present application is: the high boiling point solvent is any one or a combination of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone and dimethyl sulfoxide.

[0046] A further technical solution of the present application is: the low boiling point solvent is any one or a combination of chloroform, dichloromethane, tetrahydrofuran, acetone, acetonitrile and ethyl acetate.

[0047] A further technical solution of the present application is: the binary amine is any one or a combination of the following compounds, and the chemical structural formula is:

[0048]

[0049] The further technical scheme of the present application is that the binary anhydride is any one of the following compounds or a combination thereof, and the chemical structural formula is as follows:

[0050]

[0051] Beneficial effects

[0052] The beneficial effects of the present application are that the present application develops a technical method for improving the polymerization activity of DSSQ functional molecules by chain extension from the perspective of molecular structure design on the basis of the currently reported DSSQ functional molecules. The method can be used for synthesizing a series of DSSQ functional molecules with different molecular structures and reaction activities that can meet the polymerization requirements, greatly enriching the diversity of DSSQ functional molecules, solving the problem that the polymerization activity of DSSQ functional molecules is low due to significant steric hindrance, and making it difficult to obtain a high molecular weight polyimide gas separation membrane through polymerization; and a series of polyimide membrane materials with different DSSQ contents and excellent separation performance are prepared.

[0053] The polyimide film prepared by the present application has a thermal decomposition temperature of 480 DEG C or higher, a glass transition temperature of higher than 260 DEG C, a tensile strength of higher than 70 MPa, a tensile modulus close to 2.0 GPa, a breaking elongation of greater than 7%, and the permeation coefficients of the film to CO2 and O2 are P (CO2) = 38.8 barrer and P (O2) = 5.95 barrer, respectively, and the selectivities of the film to CO2 / CH4 and O2 / N2 gas pairs can reach alpha (CO2 / CH4) = 44 and alpha (O2 / N2) = 6.33, respectively, almost reaching the upper limit of Robeson in 1991. In the test of a binary mixed gas with CO2 / CH4 = 1:1, the film shows good plasticization resistance at a pressure as high as 20 bar, and still shows good separation performance to the CO2 / CH4 mixed gas. In addition, the polyimide separation film prepared by the present application still has stable gas permeability and relatively constant selectivity after physical aging for 300 days at room temperature, and has outstanding aging resistance.

[0054] The synthesis route proposed by the present application mainly includes three steps, the product of each step has a precise molecular structure, and the raw materials are all fed according to the chemical reaction equivalent, without waste of raw materials and with high yield, and the overall yield can reach more than 90%. Through targeted molecular structure design, Figure 3The mononitro aromatic amine compound prepared in the first step has diversity in molecular structure, which makes the DDDSQ functional monomer have greater flexibility and controllability in molecular structure design, is more widely applied, has more diversified molecular structure, and the synthesis process is more suitable for batch production. The technical route provided by the application can provide diversified design ideas and raw material basis for molecular structure design and efficient preparation of the polyimide gas separation membrane containing the DDDSQ element, and helps to promote the wide application of the polyimide gas separation membrane in the separation and purification field. BRIEF DESCRIPTION OF DRAWINGS

[0055] Figure 1 is a schematic diagram of the molecular structure of the DDDSQ functional molecule;

[0056] Figure 2 is a schematic diagram of the synthesis route of the DDDSQ diamine functional molecule reported by Kakimoto et al. in the prior art;

[0057] Figure 3 is a schematic diagram of the synthesis route of the DDDSQ diamine functional molecule provided by the application;

[0058] Figure 4 is a schematic diagram of the molecular structure of the product that may be obtained when the asymmetric diamine is selected and the DDDSQ diamine is prepared according to the experimental method reported by Kakimoto et al.;

[0059] Figure 5 is a schematic diagram of the reaction route for preparing the DDDSQ diamine by selecting the asymmetric diamine 3FODA and according to the experimental method reported by Kakimoto et al.;

[0060] Figure 6 is a nuclear magnetic resonance hydrogen spectrum spectrum of the DDDSQ diamine prepared according to the technical method shown in Figure 5

[0061] is a nuclear magnetic resonance hydrogen spectrum spectrum of the DDDSQ diamine prepared according to the technical method shown in Figure 7 Figure 3

[0062] Figure 8 is a schematic diagram of the synthesis route of the polyimide containing the DDDSQ element;

[0063] Figure 9 is a photograph of the polyimide gas separation membrane containing the DDDSQ element;

[0064] Figure 10 is the thermal performance of the polyimide gas separation membrane containing the DDDSQ element: (a) TGA curve, (b) curve of the internal friction factor with temperature;

[0065] Figure 11 ​​These are the tensile stress-strain curves of polyimide films with different DDSQ element contents;

[0066] Figure 12 The following are the nitrogen adsorption performance data of polyimide with different DDSQ unit contents: (a) adsorption-desorption curves, (b) pore size distribution;

[0067] Figure 13 The Robeson upper limit diagram shows the gas separation performance of polyimide films with different DDSQ element contents.

[0068] Figure 14 (a) The CO2 / CH4 (1:1) gas separation performance of DDSQ-25 polyimide film varies with the test pressure in the upper chamber, and (b) The upper limit of CO2 / CH4 gas separation of DDSQ-25 polyimide film. The red solid dots represent the selective / permeable test results of the gas mixture under the conditions of 35℃ and upstream pressure of 2-20 bar. Detailed Implementation

[0069] The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the invention, and should not be construed as limiting the invention.

[0070] Phenyl-substituted bilayer silsesquioxanes (DDSQ) are large organic-inorganic hybrid molecules (molecular structures such as...). Figure 1As shown, it has nanoscale pores and high specific surface area, and is easy to functionalize, and its inorganic Si-O-Si core has an exceptionally stable physicochemical property. Therefore, from the inherent nanoscale pores and significant steric hindrance of DDSQ molecules, introducing DDSQ units into the polymer molecular skeleton is beneficial to improve the microporous structure and free volume content of the polymer, and thus is expected to improve the gas separation flux and selectivity of the gas pair of the final polymer. In addition, the stable inorganic core of DDSQ is also beneficial to inhibit the "plasticization" and "aging" phenomena of the separation membrane in the actual separation process, and the DDSQ functional molecule has potential application value in constructing high polymer gas separation membranes [ACS Applied Materials & Interfaces, 2023, 5, 743-750.]. It should be noted that through extensive literature research, it is found that there are few reports on high polymer gas separation membranes constructed by DDSQ functional molecules so far. Some research works introduce DDSQ units only to improve the thermal performance or dielectric performance of the final polymer, and have not involved gas separation performance. The possible reason for analysis is that due to the outstanding steric hindrance of DDSQ molecules, the polymerization activity is too low, and it is difficult to obtain high molecular weight, so that the self-supporting polymer membrane material with comprehensive physical properties cannot meet the needs of the separation industry [Macromolecules, 2008, 41, 3481-3487]. In addition, it is reported that when the addition amount of DDSQ is high, due to its low free energy, it tends to aggregate or self-assemble in the polymer matrix and induce phase separation, destroying the uniformity of the membrane material [Journal of Material Chemistry A, 2020, 8, 9013-9020]. In summary, due to the technical difficulties of low activity and easy to induce phase separation of DDSQ functional molecules, it is difficult to effectively prepare high polymer gas separation membrane materials constructed by DDSQ functional molecules.

[0071] Based on the problems existing in the prior art, the present application will first focus on solving the technical problems of low activity and easy to induce phase separation of DDSQ functional molecules. Based on the currently reported DDSQ functional molecules, a technical method for improving the polymerization activity of DDSQ functional molecules by chain extension is developed, which is suitable for synthesizing a series of DDSQ functional molecules with different molecular structures and reaction activity meeting the polymerization requirements (molecular structure as shown in Figure 3 Compared with the technical method for improving the polymerization activity of DDSQ functional molecules proposed by Kakimoto et al. [Macromolecules, 2007, 40, 5698-5705.] (technical route as shown in Figure 2As shown in the reaction route shown in the figure, the technical route of the present application is creative in that a nitro arylamine functional molecule is first synthesized, and then the nitro arylamine functional molecule is reacted with DSSQ dianhydride to obtain a bis-nitro compound containing a DSSQ unit, and after hydrogenation reduction, the target molecule DSSQ diamine is obtained. The technical route is shown in the figure. Figure 3 Although Kakimoto et al. can obtain DSSQ diamine by one-step chemical synthesis, the reaction is achieved by end-capping reaction of DSSQ dianhydride with excess 5 times of raw material diamine. Due to the excess of raw material diamine, the target molecule inevitably contains raw material diamine, making it difficult to purify the target molecule. In addition, the technical solution proposed by Kakimoto et al. is limited to using raw material diamine with symmetrical molecular structure to construct DSSQ diamine functional molecule. If the selected raw material diamine has an asymmetrical molecular structure, such as containing methyl, trifluoromethyl, phenyl and other substituents, as in the technical solution proposed by the present application, Figure 3 Due to the influence of reaction disorder, steric hindrance and electronic effect, the reaction of asymmetrical diamine with DSSQ dianhydride will obtain a mixture of multiple monomers (possible monomer molecular structures are shown in the figure Figure 4 ), which cannot achieve precise synthesis of the target molecule, thus limiting the diversity of DSSQ functional molecules. Referring to the technical method proposed by Kakimoto et al., the inventors used asymmetrical diamine (3FODA) to react with DSSQ dianhydride (Example 9) to try to prepare diamine with the molecular structure shown in the figure Figure 5 . The reaction route is shown in the figure Figure 5 . The inventors characterized the final obtained compound by hydrogen spectrum nuclear magnetic resonance, and the results are shown in the figure Figure 6 . It is found that the final obtained compound has three different chemical environments of primary amino groups, and the final product contains a large amount of unreacted raw material diamine 3FODA, and the product is obviously a mixture. In contrast, the diamine prepared by the technical method proposed by the present application has a clear molecular structure, and the hydrogen spectrum analysis results are shown in the figure Figure 7 , which is completely consistent with the theoretical molecular composition, and the high-resolution mass spectrometry data further confirms that the molecular weight of the diamine monomer prepared by the technical solution proposed by the present application is completely consistent with the theoretical result, proving that the technical solution proposed by the present application has a significant advantage in constructing diamine monomer with precise molecular structure.

[0072] As can be found from the above comparison, the technical solution proposed by the present application is divided into three steps, but the product of each step has a precise molecular structure, and the raw materials are added according to the chemical reaction equivalent, without waste of raw materials and with high yield. The overall yield can reach more than 90%. Through targeted molecular structure design, Figure 3The mononitro arylamine compound prepared in the first step has diversity in the molecular structure, which makes the DDSQ functional monomer have greater flexibility and controllability in the molecular structure design, is more widely applied, has more diversified molecular structure, and is more suitable for batch production. The technical route provided in the application can provide diversified design ideas and raw material basis for the molecular structure design and efficient preparation of the polyimide gas separation membrane containing the DDSQ unit, and is helpful to promote the wide application of the polyimide gas separation membrane in the separation and purification field.

[0073] The specific steps for preparing the polyimide film in the embodiment are as follows:

[0074] Step 1: sequentially add the base compound, silane coupling agent, alcohol, and deionized water into a reaction container provided with a magnetic stirrer and a condenser, start stirring and heat the system, continue refluxing and stirring for 10-30 h when the temperature is increased to 60-120 DEG C, filter the reaction system when the system is cooled to 20-35 DEG C, wash the filter cake with alcohol for 2-3 times, dry the filter cake in a vacuum oven at 60-120 DEG C for 12-24 h, and obtain white powder product F;

[0075] The molar ratio of the base compound to the silane coupling agent is 1:1-3.0, and the molar ratio of the deionized water to the silane coupling agent is 1:0.2-2.0;

[0076] The solute content is controlled to be 15wt%-40wt%;

[0077] Step 2: sequentially add the product F, tertiary amine compound, low-boiling-point solvent, and dichlorosilane into a three-necked flask provided with a magnetic stirrer, start stirring, react for 1-3 h at-5-5 DEG C and 3-8 h at 15-30 DEG C, filter, wash the filter cake with the low-boiling-point solvent for 2-4 times, collect the filtrate, concentrate, filter, wash the filter cake with alcohol for 2-3 times, and dry at 60-120 DEG C under vacuum for 12-24 h to obtain white powder product H;

[0078] The molar ratio of the product F to the tertiary amine compound is 1:2-5, and the molar ratio of the product F to the dichlorosilane is 1:2-5;

[0079] The solute content is controlled to be 5wt%-25wt%;

[0080] Step 3: sequentially add the product H, alkenyl anhydride, low-boiling-point solvent, and Karstedt catalyst into a reaction container provided with a magnetic stirrer, heat the reaction system to 60-120 DEG C under argon atmosphere, react for 24-72 h, cool to 15-25 DEG C, pour the reaction liquid into alcohol, add deionized water into the alcohol, filter, wash the filter cake with deionized water for 2-3 times, and dry at 80-160 DEG C under vacuum for 12-36 h to obtain DDSQ anhydride;

[0081] The molar ratio of the product H to the alkenyl anhydride is 1:5-8, and the volume fraction of the Karstedt catalyst in the reaction system is 0.01-0.1%;

[0082] The mass fraction of the solute is 15%-35%;

[0083] Step 4: A reaction container equipped with mechanical stirring is sequentially added with a carbonic compound, a phenolic compound, a high-boiling-point solvent, a nitro compound D, and a phosphorus-containing stabilizer M, and stirred under argon protection and the system is heated; when the temperature is increased to 80-160℃, the stirring is continuously performed for 15-30 hours;

[0084] The molar ratio of the carbonic compound to the phenolic compound is 1-1.5:1;

[0085] The molar ratio of the nitro compound D to the phenolic compound is 1:1-2.0;

[0086] The mass fraction of the phosphorus-containing stabilizer M is 0.5%-3.0%, and the solute content is controlled to be 20wt%-30wt%;

[0087] The sum of the mass percentages of the above components is 100%;

[0088] Step 5: When the system is cooled to 20-35℃, the reaction system is poured into deionized water, and a brown precipitate is separated out; the filter cake is washed with deionized water for 2-3 times, and a crude product is obtained; the crude product is recrystallized, the filter cake is collected after filtration and dried in a vacuum oven at 60-120℃ for 12-24 hours, and a product E is obtained;

[0089] Step 6: The DDSQ anhydride is added to a three-necked flask equipped with a water separator and a condensing reflux device, the carboxylic acid solvent G is added under argon atmosphere and mechanical stirring is started, the product E and cyclohexane are sequentially added and the system is heated to reflux; after reflux reaction for 5-12 hours, the reaction liquid is slowly cooled to 20-35℃, poured into distilled water, and the filter cake is washed with distilled water for 2-3 times; the filter cake is dried in a vacuum oven at 60-120℃ for 12-24 hours to obtain a powder product C;

[0090] The molar ratio of the DDSQ anhydride to the product E is 1:2;

[0091] The molar ratio of the product E to the carboxylic acid solvent G is 1:100-150;

[0092] The volume ratio of the cyclohexane to the carboxylic acid solvent G is 1:3-6;

[0093] Step 7: Dissolve product C in solvent J, add palladium-carbon catalyst and phosphorus-containing stabilizer M, and place the reaction system in a high-pressure reactor to react in a hydrogen atmosphere at room temperature for 5-25 h; the hydrogen pressure is maintained at 5-35 bar during the reaction; after the reaction, filter off the catalyst, remove solvent J by distillation under reduced pressure, and wash the product with toluene 2-3 times, and then dry the filter cake in a vacuum oven at 60-120 °C for 12-24 h to obtain D D S Q diamine;

[0094] The mass fraction of the solute is 10%-20%;

[0095] The volume fraction of the phosphorus-containing stabilizer M is 1%-2%;

[0096] The amount of the palladium-carbon catalyst added is determined according to 30-100 mg of catalyst corresponding to 1 mmol of nitro group;

[0097] The molecular structural formula of the D D S Q diamine is:

[0098]

[0099] Step 8: Add D D S Q diamine, diacid anhydride, diamine, and high-boiling-point solvent into a reaction vessel equipped with mechanical stirring under argon protection, start stirring, and cool the system; continue stirring for 10-15 h after the system temperature is reduced to 0-10 °C;

[0100] The molar ratio of the D D S Q diamine, diamine, and diacid anhydride is (1-x):x:1-1.05, wherein x is in the range of 0-0.9; and the solid content is controlled in the range of 10 wt%-30 wt%;

[0101] Step 9: Increase the system temperature to 15-25 °C, add a dehydrating agent and a catalyst under argon protection, and continue stirring for 12-15 h;

[0102] The molar ratio of the dehydrating agent to diacid anhydride is 3-5:1;

[0103] The molar ratio of the catalyst to diacid anhydride is 1-2:1;

[0104] Step 10: Increase the system temperature to 50-80 °C, continue stirring under argon protection for 4-8 h;

[0105] Step 11: After the system is cooled to 20-35 °C, pour the reaction solution into an alcohol solution to precipitate fibrous solid product, filter and wash the filter cake with alcohol 2-4 times, and dry the filter cake in a vacuum oven at 80-160 °C for 12-24 h to obtain polymer R;

[0106] Step 12: Dissolve the polymer R in a low boiling point solvent, the solid content is controlled at 4wt%~15wt%, after filtration, flow on the previously adjusted to the level of the glass plate; the glass plate is placed in a vacuum oven at 25~40℃ for 10~20h, then the temperature is raised to 80~120℃ for 2~6h; after the temperature drops to 20~35℃, the film is taken out, and the polyimide gas separation film containing DDSQ unit is obtained.

[0107] The diamine is any one or combination of the following compounds, and the chemical structure is as follows:

[0108]

[0109] The diamine is any one or combination of the following compounds, and the chemical structure is as follows:

[0110]

[0111] The product E is any one or combination of the following compounds: 2-methyl-4-nitroaniline, 3-methyl-4-nitroaniline, 2-methyl-3-nitroaniline, 2-trifluoromethyl-4-nitroaniline, 3-trifluoromethyl-4-nitroaniline, 2-trifluoromethyl-3-nitroaniline, 2-phenyl-4-nitroaniline, 3-phenyl-4-nitroaniline, 2-phenyl-3-nitroaniline, 2-isopropyl-4-nitroaniline, 3-isopropyl-4-nitroaniline, 2-isopropyl-3-nitroaniline, p-nitroaniline, o-nitroaniline, m-nitroaniline.

[0112] The carbonic acid compound is any one or combination of the following compounds: sodium carbonate, potassium carbonate, cesium carbonate, rubidium carbonate.

[0113] The phenolic compound is any one or combination of the following compounds: p-aminophenol, o-aminophenol, m-aminophenol, 2-methyl-4-aminophenol, 3-methyl-4-aminophenol, 2-methyl-3-aminophenol, 3-methyl-2-aminophenol, 4-amino-3-trifluoromethylphenol, 4-amino-2-trifluoromethylphenol, 3-amino-2-trifluoromethylphenol, 2-phenyl-4-aminophenol, 3-isopropyl-4-aminophenol, 2-phenyl-3-aminophenol, 3-isopropyl-2-aminophenol, 3-phenyl-4-aminophenol, 3-phenyl-2-aminophenol, 2-amino-3-trifluoromethylphenol, p-aminophenylthiol, o-aminophenylthiol, m-aminophenylthiol, 2-methyl-4-aminophenylthiol, 3-methyl-4-aminophenylthiol, 2-methyl-3-aminophenylthiol, 3-methyl-2-aminophenylthiol, 4-amino-3-trifluoromethylphenylthiol, 4-amino-2-trifluoromethylphenylthiol, 3-amino-2-trifluoromethylphenylthiol, 2-amino-3-trifluoromethylphenylthiol.

[0114] The high-boiling solvent is any one or combination of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, dimethyl sulfoxide.

[0115] The nitro compound D is any one or combination of o-nitrohalobenzene, m-nitrohalobenzene, p-nitrohalobenzene, 2-methyl-4-nitrohalobenzene, 3-methyl-4-nitrohalobenzene, 4-nitro-3-trifluoromethylhalobenzene, 4-nitro-2-trifluoromethylhalobenzene, 2-isopropyl-4-nitrohalobenzene, 3-phenyl-4-nitrohalobenzene, 4-nitro-3-phenylhalobenzene, 4-nitro-2-phenylhalobenzene, 3-isopropyl-4-nitrohalobenzene; and the halogen element is fluorine, chlorine, bromine or iodine.

[0116] The phosphorus-containing stabilizer M is any one or combination of triphenyl phosphite, triphenyl phosphate, triphenyl phosphine, triphenyl phosphine oxide.

[0117] The base compound is any one or combination of sodium hydroxide, potassium hydroxide, calcium hydroxide, cesium hydroxide, sodium carbonate, potassium carbonate, cesium carbonate, sodium ethoxide, sodium methoxide, sodium tert-butoxide, potassium tert-butoxide, potassium ethoxide, potassium methoxide.

[0118] The silane coupling agent is any one or combination of phenyltrimethoxysilane, phenyltriethoxysilane, phenyltrichlorosilane.

[0119] The alcohol is any one or combination of ethanol, methanol, isopropanol.

[0120] The tertiary amine compound is any one or combination of triethylamine, trimethylamine, triphenylamine, tripropylamine, N-methyldiethylamine, N-methyldipropylamine, N,N-dimethylethylamine, N,N-dimethylpropylamine.

[0121] The low-boiling solvent is any one or combination of chloroform, dichloromethane, tetrahydrofuran, acetone, acetonitrile, ethyl acetate.

[0122] The dichlorosilane is any one or combination of methyl dichlorosilane, ethyl dichlorosilane, propyl dichlorosilane, phenyl dichlorosilane.

[0123] The alkenyl acid anhydride is any one or combination of the following compounds, whose chemical structural formula is:

[0124]

[0125] The carboxylic acid solvent G is any one or combination of formic acid, acetic acid, propionic acid, trifluoroacetic acid, perfluoropropionic acid, trichloroacetic acid, trichloropropionic acid, trifluoropropionic acid.

[0126] The solvent J is any one of methanol, tetrahydrofuran, ethyl acetate, acetonitrile, dichloromethane, ethanol, N,N-dimethylformamide, N,N-dimethylacetamide or a combination thereof.

[0127] The dehydrating agent is any one of acetic anhydride, trifluoroacetic anhydride, acetyl chloride or sulfoxide chloride or a combination thereof.

[0128] The catalyst is any one of triethylamine, trimethylamine, tripropylamine, N,N- dimethylethylamine, pyridine, N,N-dimethylethanolamine, t-butylpyridine, quinoline, isoquinoline, sodium methoxide or sodium ethoxide or a combination thereof.

[0129] Example 1

[0130] Into a reaction vessel equipped with a magnetic bar and a condenser, 4.20 g of sodium hydroxide, 31.5 g of phenyltrimethoxysilane, 90 mL of isopropyl alcohol and 3.01 g of deionized water were sequentially added; the stirring was started and the system was warmed up, and when the temperature rose to 75 °C, the refluxing and stirring were continued for 24 h; when the system was cooled to 25 °C, the reaction system was suction filtered, and the filter cake was washed with isopropyl alcohol for 3 times, and the filter cake was dried in a vacuum oven at 60 °C for 24 h to obtain white powder product F (yield 69.1%); 17.41 g of product F was added to a three-necked flask equipped with a magnetic bar, 6.00 g of triethylamine, 300 mL of tetrahydrofuran, 5.75 g of methyldichlorosilane were sequentially added and the stirring was started; the reaction was carried out at 0 °C for 1 h and at 25 °C for 5 h, the filter cake was washed with low boiling point solvent for 3 times, the filtrate was collected and concentrated, the filter cake was washed with alcohol for 3 times and dried in a vacuum oven at 60 °C for 24 h to obtain white powder product H (yield 55.1%); into a reaction vessel equipped with a magnetic bar, 9.33 g of product H, 8.66 g of cis-5-norbornene-endo-2,3-dicarboxylic anhydride (ND), 45 mL of super dry tetrahydrofuran and 5 drops of Karstedt catalyst (Pt(dvs)) were sequentially added, and the reaction system was heated to 80 °C under argon atmosphere for 48 h; after cooling to 25 °C, the reaction liquid was poured into methanol and deionized water was added to the methanol, the filter cake was washed with deionized water for 3 times, and dried in a vacuum oven at 140 °C for 24 h to obtain DDSQ anhydride (yield 86.4%);

[0131] To a reaction vessel equipped with mechanical stirring, 21.24 g of sodium carbonate, 15.10 g of p-aminophenol, 164.12 g of N,N-dimethylformamide, 15.68 g of p-fluoronitrobenzene and 2.45 mL of triphenyl phosphite were added in sequence, and the system was stirred and heated under argon protection; when the temperature rose to 90°C, the stirring was continued for 15 h; when the system cooled to 25°C, the reaction system was poured into deionized water, and a brown precipitate was separated out; the filter cake was washed with deionized water for 3 times, and a crude product was obtained; the crude product was recrystallized, the filter cake was collected after filtration and dried in a vacuum oven at 80°C for 24 h, and a product E was obtained (yield 89.5%); 8.87 g of DDSQ anhydride was added to a three-necked flask equipped with a water separator and a condensing reflux device, 100 g of glacial acetic acid was added under argon atmosphere, and mechanical stirring was started, 2.75 g of product E and 30 g of cyclohexane were added in sequence, and the system was heated to reflux; after refluxing for 8 h, the system was slowly cooled to 25°C, the reaction solution was poured into distilled water, and the filter cake was washed with distilled water for 3 times; the filter cake was dried in a vacuum oven at 80°C for 24 h to obtain a powder product C (yield 97.8%); 10 g of product C was dissolved in 60 g of tetrahydrofuran, 1.01 g of palladium-carbon catalyst and 1.1 g of triphenyl phosphate were added, and the reaction system was placed in a high-pressure reaction kettle for reaction in a hydrogen atmosphere at room temperature for 16 h; the hydrogen pressure was maintained at 12 bar during the reaction; after the reaction was completed, the catalyst was filtered off, tetrahydrofuran was removed by reduced pressure distillation, and the product was washed with toluene for 3 times and dried in a vacuum oven at 80°C for 12 h to obtain DDSQ diamine (yield 98.4%);

[0132] To a reaction vessel equipped with mechanical stirring, 0.74 g of DDSQ diamine, 0.32 g of ODA, 0.89 g of 6FDA and 10.12 g of N,N-dimethylacetamide were added in sequence, argon protection, and stirring was started; when the system temperature dropped to 0°C, the stirring was continued for 12 h; the system temperature was raised to 25°C, argon protection, 0.95 g of acetic anhydride and 0.40 g of triethylamine were added, and the stirring was continued for 12 h; the system temperature was raised to 60°C, argon protection, and the stirring was continued for 6 h; when the system cooled to 25°C, the reaction solution was poured into a methanol solution to separate out a fibrous solid product, which was filtered and washed with methanol for 3 times, and the filter cake was dried in a vacuum oven at 90°C for 24 h to obtain polymer R (yield 99.2%); 1.5 g of polymer R was dissolved in 20 g of trichloromethane, filtered and cast on a previously leveled glass plate; the glass plate was placed in a vacuum oven at 25°C for 10 h, and then the temperature was raised to 80°C for 4 h; after the temperature dropped to 25°C, the film was taken out, and a polyimide gas separation film containing DDSQ units was obtained.

[0133] Example 2

[0134] To a reaction vessel equipped with a magnetic bar and a condenser, 8.4 g of sodium hydroxide, 63.10 g of phenyltrimethoxysilane, 200 mL of isopropyl alcohol and 6.00 g of deionized water were added in sequence; the stirring was started and the system was warmed up, and when the temperature reached 80°C, the refluxing and stirring were continued for 26 h; when the system was cooled to 23°C, the reaction system was suction filtered, and the filter cake was washed with isopropyl alcohol for 3 times, and the filter cake was dried in a vacuum oven at 60°C for 24 h to obtain the white powder product F (yield 78.5%); 17.40 g of product F was added to a three-necked flask equipped with a magnetic bar, 6.05 g of triethylamine, 310 mL of tetrahydrofuran, 6.75 g of methyldichlorosilane were added in sequence and the stirring was started; the reaction was carried out at 0°C for 2 h and at 25°C for 6 h, the suction filtration was performed, the filter cake was washed with tetrahydrofuran for 3 times, the filtrate was collected and concentrated, the filter cake was washed with methanol for 3 times and dried in a vacuum oven at 60°C for 24 h to obtain the white powder product H (yield 58.3%); to a reaction vessel equipped with a magnetic bar, 11.20 g of product H, 10.39 g of cis-5-norbornene-endo-2,3-dicarboxylic anhydride, 55 mL of super dry tetrahydrofuran and 5 drops of Karstedt catalyst were added in sequence, the reaction system was heated to 85°C under argon atmosphere and reacted for 50 h; after being cooled to 25°C, the reaction liquid was poured into methanol and deionized water was added to the methanol, the suction filtration was performed, the filter cake was washed with deionized water for 3 times and dried in a vacuum oven at 140°C for 24 h to obtain D D SQ anhydride (yield 88.6%);

[0135] To a reaction vessel equipped with mechanical stirring, 26.77 g of sodium carbonate, 22.05 g of p-aminophenol, 207.6 g of N,N-dimethylacetamide, 20.38 g of p-fluoronitrobenzene and 2.9 mL of triphenyl phosphite were added in sequence, and the system was stirred and heated under argon protection; when the temperature rose to 100°C, the stirring was continued for 15 h; when the system cooled to 25°C, the reaction system was poured into deionized water, and a brown precipitate was separated out; the filter cake was washed with deionized water for 3 times, and a crude product was obtained; the crude product was recrystallized, the filter cake was collected after filtration and dried in a vacuum oven at 80°C for 24 h, and a product E was obtained (yield 90.6%); 8.87 g of DDSQ anhydride was added to a three-necked flask equipped with a water separator and a condenser reflux device, 100 g of glacial acetic acid was added under argon atmosphere, and mechanical stirring was started, 2.75 g of product E and 20 g of cyclohexane were added in sequence, and the system was heated to reflux; after refluxing for 9 h, the system was slowly cooled to 25°C, the reaction solution was poured into distilled water, and the filter cake was washed with distilled water for 3 times; the filter cake was dried in a vacuum oven at 80°C for 24 h to obtain a powder product C (yield 98.0%); 10 g of product C was dissolved in 60 g of tetrahydrofuran, 0.59 g of palladium-carbon catalyst and 1.1 g of triphenyl phosphate were added, and the reaction system was placed in a high-pressure reaction kettle for reaction in a hydrogen atmosphere at room temperature for 16 h; the hydrogen pressure was maintained at 12 bar during the reaction; after the reaction was completed, the catalyst was filtered off, tetrahydrofuran was removed by reduced pressure distillation, and the product was washed with toluene for 3 times and dried in a vacuum oven at 80°C for 12 h to obtain DDSQ diamine (yield 90.3%);

[0136] To a reaction vessel equipped with mechanical stirring, 0.74 g of DDSQ diamine, 0.32 g of ODA, 0.89 g of 6FDA and 10.12 g of N,N-dimethylacetamide were added in sequence, argon protection, and stirring was started; when the system temperature dropped to 1°C, the stirring was continued for 13 h; the system temperature was raised to 20°C, argon protection, 0.85 g of acetic anhydride and 0.38 g of triethylamine were added, and the stirring was continued for 13 h; the system temperature was raised to 75°C, argon protection, and the stirring was continued for 5 h; when the system cooled to 25°C, the reaction solution was poured into a methanol solution to separate out a fibrous solid product, which was filtered and washed with methanol for 3 times, and the filter cake was dried in a vacuum oven at 130°C for 20 h to obtain polymer R (yield 99.6%); 1.5 g of polymer R was dissolved in 22 g of trichloromethane, filtered and cast on a previously leveled glass plate; the glass plate was placed in a vacuum oven at 25°C for 12 h, and then the temperature was raised to 100°C for 3 h; after the temperature dropped to 25°C, the film was taken out, and a polyimide gas separation film containing DDSQ units was obtained.

[0137] Example 3

[0138] To a reaction vessel equipped with a magnetic bar and a condenser, 4.21 g of sodium hydroxide, 31.54 g of phenyltrimethoxysilane, 90 mL of isopropyl alcohol and 3.00 g of deionized water were added in sequence; the stirring was started and the system was warmed up, and when the temperature rose to 83 °C, the refluxing and stirring were continued for 25 h; when the system was cooled to 24 °C, the reaction system was suction filtered, and the filter cake was washed with isopropyl alcohol three times; the filter cake was dried in a vacuum oven at 60 °C for 24 h to obtain the white powder product F (yield 82.5%); 17.43 g of product F was added to a three-necked flask equipped with a magnetic bar, 6.01 g of triethylamine, 300 mL of tetrahydrofuran, 6.90 g of methyldichlorosilane were added in sequence, and the stirring was started; the reaction was carried out at 0 °C for 2 h and at 25 °C for 7 h, the suction filtration was performed, the filter cake was washed with tetrahydrofuran three times, the filtrate was collected and concentrated, the filter cake was washed with methanol three times, and then dried in a vacuum oven at 60 °C for 24 h to obtain the white powder product H (yield 59.6%); to a reaction vessel equipped with a magnetic bar, 12.30 g of product H, 11.43 g of cis-5-norbornene-endo-2,3-dicarboxylic anhydride, 65 mL of super dry tetrahydrofuran and 5 drops of Karstedt catalyst were added in sequence, the reaction system was heated to 84 °C under argon atmosphere and reacted for 50 h; after cooling to 23 °C, the reaction liquid was poured into methanol, deionized water was added to the methanol, suction filtration was performed, the filter cake was washed with deionized water three times, and dried in a vacuum oven at 140 °C for 24 h to obtain D D S Q anhydride (yield 89.2%);

[0139] To a reaction vessel equipped with mechanical stirring, 27.92 g of potassium carbonate, 22.05 g of p-aminophenol, 278.3 g of N,N-dimethylacetamide, 28.51 g of p-fluoronitrobenzene and 4 mL of triphenyl phosphite were added in sequence, and the system was stirred and heated under argon protection. When the temperature reached 100°C, the stirring was continued for 15 h. When the system cooled to 25°C, the reaction system was poured into deionized water, and a brown precipitate was separated out. The filter cake was washed with deionized water three times, and the crude product was obtained. The crude product was recrystallized, the filter cake was collected and dried in a vacuum oven at 80°C for 24 h, and the product E was obtained (yield 91.5%). 8.87 g of DDSQ anhydride was added to a three-necked flask equipped with a water separator and a reflux condenser, 100 g of glacial acetic acid was added under argon protection, and mechanical stirring was started. 2.75 g of product E and 18 g of cyclohexane were added in sequence, and the system was heated to reflux. After refluxing for 10 h, the system was slowly cooled to 25°C, the reaction solution was poured into distilled water, and the filter cake was washed with distilled water three times. The filter cake was dried in a vacuum oven at 80°C for 24 h to obtain the powder product C (yield 98.5%). 10 g of product C was dissolved in 60 g of tetrahydrofuran, 0.74 g of palladium-carbon catalyst and 1.15 g of triphenyl phosphate were added, and the reaction system was placed in a high-pressure reaction kettle for reaction under hydrogen atmosphere at room temperature for 17 h. The hydrogen pressure was maintained at 12 bar during the reaction. After the reaction was completed, the catalyst was filtered off, tetrahydrofuran was removed by reduced pressure distillation, and the product was washed with toluene three times and dried in a vacuum oven at 80°C for 12 h to obtain DDSQ diamine (yield 93.4%).

[0140] To a reaction vessel equipped with mechanical stirring, 0.76 g of DDSQ diamine, 0.33 g of ODA, 0.93 g of 6FDA and 10.31 g of N,N-dimethylacetamide were added in sequence, argon protection, and stirring was started. When the system temperature dropped to 0°C, the stirring was continued for 13 h. The system temperature was raised to 20°C, argon protection, 0.91 g of acetic anhydride and 0.33 g of triethylamine were added, and the stirring was continued for 14 h. The system temperature was raised to 60°C, argon protection, and the stirring was continued for 4.5 h. When the system cooled to 25°C, the reaction solution was poured into methanol solution to separate out fibrous solid product, which was filtered and washed with methanol three times. The filter cake was dried in a vacuum oven at 145°C for 24 h to obtain polymer R (yield 99.0%). 1.5 g of polymer R was dissolved in 24 g of chloroform, filtered and cast on a previously leveled glass plate. The glass plate was placed in a vacuum oven at 30°C for 15 h, and then the temperature was raised to 90°C for 3 h. After the temperature dropped to 25°C, the film was removed, and a polyimide gas separation film containing DDSQ units was obtained.

[0141] Example 4

[0142] To a reaction vessel equipped with a magnetic bar and a condenser, 6.32 g of sodium hydroxide, 47.58 g of phenyltrimethoxysilane, 180 mL of isopropyl alcohol and 4.45 g of deionized water were added in sequence; the stirring was started and the system was heated, and when the temperature reached 85°C, the refluxing and stirring were continued for 24 h; when the system was cooled to 25°C, the reaction system was filtered, the filter cake was washed with isopropyl alcohol for 3 times, and the filter cake was dried in a vacuum oven at 60°C for 24 h to obtain the white powder product F (yield 80.2%); 17.25 g of product F was added to a three-necked flask equipped with a magnetic bar, 5.95 g of triethylamine, 285 mL of tetrahydrofuran, 6.74 g of methyldichlorosilane were added in sequence and the stirring was started; the reaction was carried out at -1°C for 1.5 h and at 25°C for 5 h, the filter cake was filtered and washed with tetrahydrofuran for 3 times, the filtrate was collected and concentrated, the filter cake was washed with methanol for 3 times and dried in a vacuum oven at 60°C for 24 h to obtain the white powder product H (yield 60.6%); to a reaction vessel equipped with a magnetic bar, 11.35 g of product H, 10.85 g of cis-5-norbornene-endo-2,3-dicarboxylic anhydride, 60 mL of super dry tetrahydrofuran and 5 drops of Karstedt catalyst were added in sequence, the reaction system was heated to 85°C under argon atmosphere and reacted for 60 h; after cooling to 23°C, the reaction liquid was poured into ethanol and deionized water was added to the ethanol, the filter cake was filtered and washed with deionized water for 3 times, and dried in a vacuum oven at 140°C for 24 h to obtain D D SQ anhydride (yield 86.2%);

[0143] To a reaction vessel equipped with mechanical stirring, 28.30 g of potassium carbonate, 22.35 g of p-aminophenol, 202.30 g of N,N-dimethylacetamide, 20.51 g of p-fluoronitrobenzene and 3 mL of triphenyl phosphite were added in sequence, and the system was stirred and heated under argon protection. When the temperature rose to 110°C, the stirring was continued for 20 h. When the system cooled to 25°C, the reaction system was poured into deionized water, and a brown precipitate was separated out. The filter cake was washed with deionized water three times, and the crude product was obtained. The crude product was recrystallized, the filter cake was collected after filtration and dried in a vacuum oven at 80°C for 24 h to obtain product E (yield 90.8%). 11.52 g of DDSQ anhydride was added to a three-necked flask equipped with a water separator and a reflux condenser, 130 g of glacial acetic acid was added under argon protection, and mechanical stirring was started. 3.58 g of product E and 25 g of cyclohexane were added in sequence, and the system was heated to reflux. After refluxing for 8 h, the system was slowly cooled to 25°C, the reaction solution was poured into distilled water, and the filter cake was washed with distilled water three times. The filter cake was dried in a vacuum oven at 80°C for 24 h to obtain powder product C (yield 97.9%). 8 g of product C was dissolved in 49 g of tetrahydrofuran, 0.55 g of palladium-carbon catalyst and 1.08 g of triphenyl phosphate were added, and the reaction system was placed in a high-pressure reaction kettle for reaction under hydrogen atmosphere at room temperature for 18 h. The hydrogen pressure was maintained at 15 bar during the reaction. After the reaction was completed, the catalyst was filtered off, tetrahydrofuran was removed by reduced pressure distillation, and the product was washed with toluene three times and dried in a vacuum oven at 80°C for 12 h to obtain DDSQ diamine (yield 96.2%).

[0144] To a reaction vessel equipped with mechanical stirring, 0.77 g of DDSQ diamine, 0.34 g of ODA, 0.95 g of 6FDA and 10.52 g of N,N-dimethylacetamide were added in sequence, argon protection, and stirring was started. When the system temperature dropped to 3°C, the stirring was continued for 12 h. The system temperature was raised to 25°C, argon protection, 0.962 g of acetic anhydride and 0.38 g of triethylamine were added, and the stirring was continued for 12 h. The system temperature was raised to 60°C, argon protection, and the stirring was continued for 4 h. When the system cooled to 25°C, the reaction solution was poured into methanol solution to separate out fibrous solid product, which was filtered and washed with methanol three times. The filter cake was dried in a vacuum oven at 130°C for 24 h to obtain polymer R (yield 98.9%). 1.5 g of polymer R was dissolved in 26 g of chloroform, filtered and cast on a previously leveled glass plate. The glass plate was placed in a vacuum oven at 25°C for 16 h, and then the temperature was raised to 110°C for 2 h. After the temperature dropped to 25°C, the film was removed, and a polyimide gas separation film containing DDSQ units was obtained.

[0145] Example 5

[0146] To a reaction vessel equipped with a magnetic bar and a condenser, 8.42 g of sodium hydroxide, 63.05 g of phenyltrimethoxysilane, 240 mL of isopropyl alcohol and 6.02 g of deionized water were added in sequence; the stirring was started and the system was heated, and when the temperature reached 85°C, the refluxing and stirring were continued for 24 h; when the system was cooled to 25°C, the reaction system was filtered, the filter cake was washed with isopropyl alcohol for 3 times, and the filter cake was dried in a vacuum oven at 60°C for 24 h to obtain the white powder product F (yield 82.5%); 17.50 g of product F was added to a three-necked flask equipped with a magnetic bar, 6.02 g of triethylamine, 300 mL of tetrahydrofuran, 6.85 g of methyldichlorosilane were added in sequence and the stirring was started; the reaction was carried out at -1°C for 2 h and at 25°C for 6 h, the filter cake was washed with tetrahydrofuran for 3 times, the filtrate was collected and concentrated, the filter cake was washed with methanol for 3 times and dried in a vacuum oven at 60°C for 24 h to obtain the white powder product H (yield 62.3%); to a reaction vessel equipped with a magnetic bar, 10.85 g of product H, 10.12 g of cis-5-norbornene-endo-2,3-dicarboxylic anhydride, 55 mL of super dry tetrahydrofuran and 4 drops of Karstedt catalyst were added in sequence, the reaction system was heated to 85°C under argon atmosphere and reacted for 55 h; after cooling to 25°C, the reaction liquid was poured into ethanol and deionized water was added to the ethanol, the filter cake was washed with deionized water for 3 times and dried in a vacuum oven at 140°C for 24 h to obtain D D SQ anhydride (yield 83.2%);

[0147] To a reaction vessel equipped with mechanical stirring, 44.17 g of potassium carbonate, 23.25 g of p-aminophenol, 292.90 g of N,N-dimethylacetamide, 30.07 g of p-fluoronitrobenzene and 2.2 mL of triphenyl phosphite were added in sequence, and the system was stirred and heated under argon protection. When the temperature reached 120°C, the stirring was continued for 20 h. When the system was cooled to 25°C, the reaction system was poured into deionized water, and a brown precipitate was separated out. The filter cake was washed with deionized water three times, and the crude product was obtained. The crude product was recrystallized, the filter cake was collected and dried in a vacuum oven at 80°C for 24 h, and the product E was obtained (yield 90.2%). 11.28 g of DDSQ anhydride was added to a three-necked flask equipped with a water separator and a reflux condenser, 130 g of glacial acetic acid was added under argon protection, and mechanical stirring was started. 3.50 g of product E and 30 g of cyclohexane were added in sequence, and the system was heated to reflux. After refluxing for 9 h, the system was slowly cooled to 25°C, the reaction solution was poured into distilled water, and the filter cake was washed with distilled water three times. The filter cake was dried in a vacuum oven at 80°C for 24 h to obtain the powder product C (yield 98.5%). 10 g of product C was dissolved in 51 g of ethyl acetate, 0.65 g of palladium-carbon catalyst and 1.19 g of triphenyl phosphate were added, and the reaction system was placed in a high-pressure reaction kettle for reaction in a hydrogen atmosphere at room temperature for 17 h. The hydrogen pressure was maintained at 13 bar during the reaction. After the reaction was completed, the catalyst was filtered off, the ethyl acetate was removed by reduced pressure distillation, and the product was washed with toluene three times and dried in a vacuum oven at 80°C for 12 h to obtain DDSQ diamine (yield 85.2%).

[0148] To a reaction vessel equipped with mechanical stirring, 2.22 g of DDSQ diamine, 0.24 g of ODA, 1.07 g of 6FDA and 18.21 g of N,N-dimethylacetamide were added in sequence, and the system was stirred and cooled under argon protection. When the system temperature reached 0°C, the stirring was continued for 12 h. The system temperature was raised to 25°C, argon protection was provided, 0.96 g of acetic anhydride and 0.30 g of triethylamine were added, and the stirring was continued for 12 h. The system temperature was raised to 70°C, argon protection was provided, and the stirring was continued for 5 h. When the system was cooled to 25°C, the reaction solution was poured into a methanol solution to separate out a fibrous solid product. The product was filtered and the filter cake was washed with methanol three times. The filter cake was dried in a vacuum oven at 130°C for 24 h to obtain polymer R (yield 98.5%). 2 g of polymer R was dissolved in 30 g of chloroform, and the solution was filtered and cast on a previously leveled glass plate. The glass plate was placed in a vacuum oven at 25°C for 17 h, and then the temperature was raised to 80°C for 4 h. After the temperature was lowered to 25°C, the film was removed, and a polyimide gas separation film containing DDSQ units was obtained.

[0149] Example 6

[0150] To a reaction vessel equipped with a magnetic bar and a condenser, 4.20 g of sodium hydroxide, 31.50 g of phenyltrimethoxysilane, 105 mL of isopropyl alcohol and 3.01 g of deionized water were added in sequence; the stirring was started and the system was warmed up, and when the temperature rose to 84°C, the refluxing and stirring were continued for 24 h; when the system was cooled to 25°C, the reaction system was suction filtered, and the filter cake was washed with isopropyl alcohol twice, and the filter cake was dried in a vacuum oven at 60°C for 24 h to obtain the white powder product F (yield 78.2%); 17.41 g of product F was added to a three-necked flask equipped with a magnetic bar, 5.98 g of triethylamine, 300 mL of tetrahydrofuran, 6.73 g of methyldichlorosilane were added in sequence, and the stirring was started; the reaction was carried out at 1°C for 2.5 h and at 25°C for 7 h, the suction filtration was performed, the filter cake was washed with tetrahydrofuran three times, the filtrate was collected and concentrated, the filter cake was washed with methanol three times, and then vacuum dried at 60°C for 24 h to obtain the white powder product H (yield 62.0%); to a reaction vessel equipped with a magnetic bar, 9.34 g of product H, 8.65 g of cis-5-norbornene-endo-2,3-dicarboxylic anhydride, 60 mL of super dry tetrahydrofuran and 4 drops of Karstedt catalyst were added in sequence, the reaction system was heated to 85°C under argon atmosphere and reacted for 48 h; after cooling to 25°C, the reaction liquid was poured into ethanol, deionized water was added to the ethanol, suction filtration was performed, the filter cake was washed with deionized water three times, and vacuum dried at 140°C for 24 h to obtain D D SQ anhydride (yield 90.3%);

[0151] To a reaction vessel equipped with mechanical stirring, 35.10 g of potassium carbonate, 23.25 g of p-aminophenol, 230.31 g of N,N-dimethylacetamide, 18.41 g of p-fluoronitrobenzene and 2.5 mL of triphenyl phosphite were added in sequence, and the system was stirred and heated under argon protection. When the temperature reached 110°C, the stirring was continued for 15 h. When the system was cooled to 25°C, the reaction system was poured into deionized water, and a brown precipitate was separated out. The filter cake was washed with deionized water three times, and the crude product was obtained. The crude product was recrystallized, the filter cake was collected after filtration and dried in a vacuum oven at 80°C for 24 h to obtain product E (yield 92.5%). 10.50 g of DDSQ anhydride was added to a three-necked flask equipped with a water separator and a reflux condenser, 120 g of glacial acetic acid was added under argon protection, and mechanical stirring was started. 3.25 g of product E and 30 g of cyclohexane were added in sequence, and the system was heated to reflux. After refluxing for 8 h, the system was slowly cooled to 25°C, and the reaction solution was poured into distilled water. The filter cake was washed with distilled water three times. The filter cake was dried in a vacuum oven at 80°C for 24 h to obtain powder product C (yield 97.9%). 10 g of product C was dissolved in 52 g of ethyl acetate, 0.75 g of palladium-carbon catalyst and 1.20 g of triphenyl phosphate were added, and the reaction system was placed in a high-pressure reaction kettle for reaction under hydrogen atmosphere at room temperature for 17 h. The hydrogen pressure was maintained at 15 bar during the reaction. After the reaction was completed, the catalyst was filtered off, the ethyl acetate was removed by reduced pressure distillation, and the product was washed with toluene three times and dried in a vacuum oven at 80°C for 12 h to obtain DDSQ diamine (yield 83.6%).

[0152] To a reaction vessel equipped with mechanical stirring, 2.24 g of DDSQ diamine, 0.25 g of ODA, 1.08 g of 6FDA and 19.01 g of N,N-dimethylacetamide were added in sequence, and the system was stirred and cooled under argon protection. When the system temperature reached 5°C, the stirring was continued for 14 h. The system temperature was raised to 25°C, argon protection was applied, 0.96 g of acetic anhydride and 0.31 g of triethylamine were added, and the stirring was continued for 14 h. The system temperature was raised to 60°C, argon protection was applied, and the stirring was continued for 4 h. When the system was cooled to 25°C, the reaction solution was poured into methanol solution to separate out fibrous solid product. The product was filtered and the filter cake was washed with methanol three times. The filter cake was dried in a vacuum oven at 120°C for 20 h to obtain polymer R (yield 99.5%). 2 g of polymer R was dissolved in 31 g of chloroform, and the solution was filtered and cast on a previously leveled glass plate. The glass plate was placed in a vacuum oven at 25°C for 15 h, and then the temperature was raised to 90°C for 4 h. After the temperature was lowered to 25°C, the film was removed, and a polyimide gas separation film containing DDSQ units was obtained.

[0153] Example 7

[0154] To a reaction vessel equipped with a magnetic bar and a condenser, 8.41 g of sodium hydroxide, 63.12 g of phenyltrimethoxysilane, 210 mL of isopropyl alcohol and 6.05 g of deionized water were added in sequence; the stirring was started and the system was heated, and when the temperature reached 84°C, the refluxing and stirring were continued for 24 h; when the system was cooled to 25°C, the reaction system was filtered, the filter cake was washed twice with isopropyl alcohol, and the filter cake was dried in a vacuum oven at 60°C for 24 h to obtain white powder product F (yield 83.2%); 17.20 g of product F was added to a three-necked flask equipped with a magnetic bar, 5.90 g of triethylamine, 290 mL of tetrahydrofuran, 6.65 g of methyldichlorosilane were added in sequence, and the stirring was started; the reaction was carried out at 1°C for 2 h and at 25°C for 6 h, the filter cake was washed twice with tetrahydrofuran, the filtrate was collected and concentrated, the filter cake was washed three times with methanol, and then dried in a vacuum oven at 60°C for 24 h to obtain white powder product H (yield 63.8%); to a reaction vessel equipped with a magnetic bar, 9.28 g of product H, 8.60 g of cis-5-norbornene-endo-2,3-dicarboxylic anhydride, 52 mL of super-dry tetrahydrofuran and 6 drops of Karstedt catalyst were added in sequence, the reaction system was heated to 83°C under argon atmosphere and reacted for 46 h; after cooling to 25°C, the reaction liquid was poured into ethanol and deionized water was added to the ethanol, the filter cake was washed three times with deionized water, and then dried in a vacuum oven at 140°C for 24 h to obtain DDSQ anhydride (yield 91.6%);

[0155] To a reaction vessel equipped with mechanical stirring, 73.85 g of cesium carbonate, 22.15 g of p-aminophenol, 404.70 g of N,N-dimethylacetamide, 18.11 g of p-fluoronitrobenzene and 3.8 mL of triphenyl phosphite were added in sequence, and the system was stirred and heated under argon protection; when the temperature was raised to 120°C, the stirring was continued for 18 h; when the system was cooled to 25°C, the reaction system was poured into deionized water, and a brown precipitate was separated out; the filter cake was washed with deionized water for 3 times, and a crude product was obtained; the crude product was recrystallized, the filter cake was collected after filtration and dried in a vacuum oven at 80°C for 24 h, and a product E was obtained (yield 94.8%); 8.95 g of DDSQ anhydride was added to a three-necked flask equipped with a water separator and a condenser reflux device, 100 g of glacial acetic acid was added under argon atmosphere, and mechanical stirring was started, 2.77 g of product E and 25 g of cyclohexane were added in sequence, and the system was heated to reflux; after refluxing for 7 h, the system was slowly cooled to 25°C, the reaction solution was poured into distilled water, and the filter cake was washed with distilled water for 3 times; the filter cake was dried in a vacuum oven at 80°C for 24 h to obtain a powder product C (yield 96.8%); 10 g of product C was dissolved in a mixed solution of 24 g of tetrahydrofuran and 24 g of ethyl acetate, 0.90 g of palladium-carbon catalyst and 1.18 g of triphenyl phosphate were added, and the reaction system was placed in a high-pressure reaction kettle for reaction in a hydrogen atmosphere at room temperature for 19 h; the hydrogen pressure was maintained at 12 bar during the reaction; after the reaction was completed, the catalyst was filtered off, the ethyl acetate and tetrahydrofuran were removed by distillation under reduced pressure, and the product was washed with toluene for 3 times and dried in a vacuum oven at 80°C for 12 h to obtain DDSQ diamine (yield 90.2%);

[0156] To a reaction vessel equipped with mechanical stirring, 73.85 g of cesium carbonate, 22.15 g of p-aminophenol, 404.70 g of N,N-dimethylacetamide, 18.11 g of p-fluoronitrobenzene and 3.8 mL of triphenyl phosphite were added in sequence, and the system was stirred and heated under argon protection; when the temperature was raised to 120°C, the stirring was continued for 18 h; when the system was cooled to 25°C, the reaction system was poured into deionized water, and a brown precipitate was separated out; the filter cake was washed with deionized water for 3 times, and a crude product was obtained; the crude product was recrystallized, the filter cake was collected after filtration and dried in a vacuum oven at 80°C for 24 h, and a product E was obtained (yield 94.8%); 8.95 g of DDSQ anhydride was added to a three-necked flask equipped with a water separator and a condenser reflux device, 100 g of glacial acetic acid was added under argon atmosphere, and mechanical stirring was started, 2.77 g of product E and 25 g of cyclohexane were added in sequence, and the system was heated to reflux; after refluxing for 7 h, the system was slowly cooled to 25°C, the reaction solution was poured into distilled water, and the filter cake was washed with distilled water for 3 times; the filter cake was dried in a vacuum oven at 80°C for 24 h to obtain a powder product C (yield 96.8%); 10 g of product C was dissolved in a mixed solution of 24 g of tetrahydrofuran and 24 g of ethyl acetate, 0.90 g of palladium-carbon catalyst and 1.18 g of triphenyl phosphate were added, and the reaction system was placed in a high-pressure reaction kettle for reaction in a hydrogen atmosphere at room temperature for 19 h; the hydrogen pressure was maintained at 12 bar during the reaction; after the reaction was completed, the catalyst was filtered off, the ethyl acetate and tetrahydrofuran were removed by distillation under reduced pressure, and the product was washed with toluene for 3 times and dried in a vacuum oven at 80°C for 12 h to obtain DDSQ diamine (yield 90.2%);

[0157] Example 8

[0158] To a reaction vessel equipped with a magnetic bar and a condenser, 4.19 g of sodium hydroxide, 31.58 g of phenyltrimethoxysilane, 100 mL of isopropyl alcohol and 3.00 g of deionized water were added in sequence; the stirring was started and the system was warmed up, and when the temperature reached 95 °C, the refluxing and stirring were continued for 18 h; when the system was cooled to 25 °C, the reaction system was suction filtered, and the filter cake was washed with isopropyl alcohol three times; the filter cake was dried in a vacuum oven at 60 °C for 24 h to obtain the white powder product F (yield 86.6%); 17.30 g of product F was added to a three-necked flask equipped with a magnetic bar, 5.96 g of triethylamine, 305 mL of tetrahydrofuran, 6.71 g of methyldichlorosilane were added in sequence, and the stirring was started; the reaction was carried out at 1 °C for 1 h and at 25 °C for 7 h, the suction filtration was performed, the filter cake was washed with tetrahydrofuran three times, the filtrate was collected and concentrated, the filter cake was washed with methanol three times, and then dried in a vacuum oven at 60 °C for 24 h to obtain the white powder product H (yield 65.2%); to a reaction vessel equipped with a magnetic bar, 9.34 g of product H, 8.69 g of cis-5-norbornene-endo-2,3-dicarboxylic anhydride, 52 mL of super dry tetrahydrofuran and 4 drops of Karstedt catalyst were added in sequence, the reaction system was heated to 86 °C under argon atmosphere and reacted for 48 h; after cooling to 25 °C, the reaction liquid was poured into ethanol, deionized water was added to the ethanol, suction filtration was performed, the filter cake was washed with deionized water three times, and dried in a vacuum oven at 140 °C for 24 h to obtain D D SQ anhydride (yield 85.3%);

[0159] To a reaction vessel equipped with mechanical stirring, 80.23 g of cesium carbonate, 23.01 g of p-aminophenol, 314.60 g of N,N-dimethylacetamide, 19.11 g of p-fluoronitrobenzene and 3.6 mL of triphenyl phosphite were added in sequence, and the system was stirred and heated under argon protection; when the temperature was raised to 110°C, the stirring was continued for 22 h; when the system was cooled to 25°C, the reaction system was poured into deionized water, and a brown precipitate was separated out; the filter cake was washed with deionized water for 3 times, and a crude product was obtained; the crude product was recrystallized, the filter cake was collected after filtration and dried in a vacuum oven at 80°C for 24 h, and a product E was obtained (yield 93.4%); 11.82 g of DDSQ anhydride was added to a three-necked flask equipped with a water separator and a condensing reflux device, 130 g of glacial acetic acid was added under argon atmosphere, and mechanical stirring was started, 3.66 g of product E and 40 g of cyclohexane were added in sequence, and the system was heated to reflux; after refluxing for 10 h, the system was slowly cooled to 25°C, the reaction solution was poured into distilled water, and the filter cake was washed with distilled water for 3 times; the filter cake was dried in a vacuum oven at 80°C for 24 h to obtain a powder product C (yield 93.5%); 10 g of product C was dissolved in a mixed solution of 40 g of tetrahydrofuran and 20 g of ethyl acetate, 0.84 g of palladium-carbon catalyst and 1.23 g of triphenyl phosphate were added, and the reaction system was placed in a high-pressure reaction kettle for reaction in a hydrogen atmosphere at room temperature for 18 h; the hydrogen pressure was maintained at 13 bar during the reaction; after the reaction was completed, the catalyst was filtered off, the ethyl acetate and tetrahydrofuran were removed by distillation under reduced pressure, and the product was washed with toluene for 3 times and dried in a vacuum oven at 80°C for 12 h to obtain DDSQ diamine (yield 94.8%);

[0160] To a reaction vessel equipped with mechanical stirring, 2.70 g of DDSQ diamine, 0.64 g of 6FDA and 13.36 g of N,N-dimethylacetamide were added in sequence, argon protection, and stirring was started; when the system temperature was lowered to 2°C, the stirring was continued for 12 h; the system temperature was raised to 25°C, argon protection, 0.70 g of acetic anhydride and 0.22 g of triethylamine were added, and the stirring was continued for 12 h; the system temperature was raised to 65°C, argon protection, and the stirring was continued for 6 h; when the system was cooled to 25°C, the reaction solution was poured into a methanol solution to separate out a fibrous solid product, which was filtered and washed with methanol for 3 times, and the filter cake was dried in a vacuum oven at 140°C for 16 h to obtain polymer R (yield 99.6%); 2 g of polymer R was dissolved in 31 g of tetrahydrofuran, filtered and cast on a previously leveled glass plate; the glass plate was placed in a vacuum oven at 25°C for 16 h, and then the temperature was raised to 110°C for 4 h; after the temperature was lowered to 25°C, the film was taken out, and a polyimide gas separation film containing DDSQ units was obtained.

[0161] Example 9

[0162] To a reaction vessel equipped with a magnetic bar and a condenser, 4.25 g of sodium hydroxide, 35.62 g of phenyltrimethoxysilane, 100 mL of isopropanol and 3.50 g of deionized water were added in sequence; the stirring was started and the system was heated, and when the temperature reached 120°C, the refluxing and stirring were continued for 12 h; when the system was cooled to 25°C, the reaction system was filtered, and the filter cake was washed with isopropanol for 3 times, and the filter cake was dried in a vacuum oven at 120°C for 12 h to obtain white powder product F (yield 76.4%); 17.30 g of product F was added to a three-necked flask equipped with a magnetic bar, 7.5 g of triethylamine, 300 mL of tetrahydrofuran, 8.50 g of methyldichlorosilane were added in sequence and the stirring was started; the reaction was carried out at 0°C for 2 h and at 30°C for 3 h, the filter cake was washed with tetrahydrofuran for 3 times, the filtrate was collected and concentrated, the filter cake was washed with methanol for 3 times and dried in a vacuum oven at 120°C for 12 h to obtain white powder product H (yield 70.4%); to a reaction vessel equipped with a magnetic bar, 11.53 g of product H, 10.70 g of cis-5-norbornene-endo-2,3-dicarboxylic anhydride, 125 mL of super dry tetrahydrofuran and 4 drops of Karstedt catalyst were added in sequence, the reaction system was heated to 120°C under argon atmosphere and reacted for 24 h; after cooling to 25°C, the reaction liquid was poured into ethanol and deionized water was added to the ethanol, the filter cake was washed with deionized water for 3 times and dried in a vacuum oven at 160°C for 12 h to obtain DDSQ anhydride (yield 80.3%);

[0163] Product E was prepared from commercial asymmetric diamine 2-trifluoromethyl-4,4'-diaminodiphenyl ether (3FODA) according to the reported route [Macromolecules, 2007, 40, 5698-5705.]. 1.428 g of DDSQ anhydride, 1.609 g of 3FODA and 300 mL of toluene were added to a three-necked flask equipped with a condenser reflux device and the system was heated to 105°C; after refluxing for 24 h, the reaction liquid was filtered and concentrated, and the filter cake was dried in a vacuum oven at 180°C for 24 h to obtain yellow powder product. The nuclear magnetic resonance results showed that there were characteristic peaks of primary amino hydrogen at 5.52 ppm, 5.23 ppm and 4.90 ppm, which proved that the technical scheme proposed by Kakimoto et al. could not be used to accurately synthesize DDSQ diamine functional molecules from asymmetric diamines, while the nuclear magnetic resonance results of the DDSQ diamine constructed by the technical scheme proposed in the present application showed that the diamine had an accurate chemical structure and high purity, as shown in Figure 7

[0164] Table 1 is the gas permeability and selectivity data of the gas separation membrane with 25% molar content of DDSQ diamine for pure CO2, CH4 and CO2 / CH4 (50 / 50) mixed gas at 35°C and 2-20 bar pressure;

[0165] ​Table 2. Gas permeability data (Barrer) of gas separation membranes of different mole % DDSQ diamine before and after aging for 300 days for H2, CO2, O2, N2, CH4

[0166] Table 3. Selectivity data of gas separation membranes of different mole % DDSQ diamine before and after aging for 300 days for CO2 / CH4, O2 / N2, and H2 / CH4 gas pairs

[0167] Table 1. Gas permeability and selectivity data of gas separation membranes of 25% mole % DDSQ diamine for pure CO2, CH4, and CO2 / CH4 (50 / 50) mixed gas at 35°C and 2-20 bar pressure

[0168]

[0169] Table 2. Gas permeability data (Barrer) of gas separation membranes of different mole % DDSQ diamine before and after aging for 300 days for H2, CO2, O2, N2, CH4

[0170]

[0171] 1Barrer = 10 -10 [cm 3 (STP) cm] / (cm 2 s cm Hg).

[0172] Table 3. Selectivity data of gas separation membranes of different mole % DDSQ diamine before and after aging for 300 days for CO2 / CH4, O2 / N2, and H2 / CH4 gas pairs

[0173]

[0174] Although the embodiments of the present application have been shown and described above, it is to be understood that the above-described embodiments are merely exemplary, and that the present application is not to be limited to the above-described embodiments, and that one of ordinary skill in the art can make changes, modifications, substitutions and variations to the above-described embodiments without departing from the principles and spirit of the present application within the scope of the present application.

Claims

1. A polyimide gas separation membrane prepared using a diamine containing DDSQ basic units, characterized in that: The molecular structure is as follows: Wherein, the molar fraction of the diamine portion of DDSQ is 10%-50%, the molar fraction of the diamine portion is 0-40%, and the molar fraction of the diacid anhydride portion is 50%; R1 represents the residues in the diacid anhydride, and R5 represents the residues in the diamine. The molecular structure of the diamine is: Wherein, R2 represents methyl or phenyl, R3 represents a residue in the alkenyl anhydride, R4 represents a residue in product E, and Ph represents a benzene ring; The specific steps for preparing the diamine containing the DDSQ motif are as follows: Step 1: Add an alkaline compound, a silane coupling agent, an alcohol, and deionized water sequentially to a reaction vessel equipped with a magnetic stirrer and a condenser; start stirring and heat the system until the temperature reaches 60–120 °C, then continue stirring under reflux for 10–30 h; when the system cools to 20–35 °C, filter the reaction system, wash the filter cake 2–3 times with alcohol, and dry the filter cake in a vacuum oven at 60–120 °C for 12–24 h to obtain a white powder product F; The molar ratio of the alkali compound to the silane coupling agent is 1:1 to 3.0, and the molar ratio of deionized water to the silane coupling agent is 1:0.2 to 2.

0. The solute content is controlled between 15 wt% and 40 wt%. Step 2: Add product F to a three-necked flask equipped with a magnetic stir bar, add tertiary amine compound, low-boiling solvent, and dichlorosilane in sequence, and start stirring; react at -5 to 5 °C for 1 to 3 h, and at 15 to 30 °C for 3 to 8 h in sequence, filter, wash the filter cake 2 to 4 times with low-boiling solvent, collect the filtrate, concentrate and filter, wash the filter cake 2 to 3 times with alcohol, and then dry under vacuum at 60 to 120 °C for 12 to 24 h to obtain white powder product H; The molar ratio of product F to tertiary amine compounds is 1:2 to 5, and the molar ratio of product F to dichlorosilane is 1:2 to 5. The solute content is controlled between 5 wt% and 25 wt%. Step 3: Add product H, alkenyl anhydride, low-boiling-point solvent, and Castel catalyst sequentially to a reaction vessel containing magnetic particles. Heat the reaction system to 60–120 °C under an argon atmosphere and react for 24–72 h. After cooling to 15–25 °C, pour the reaction solution into alcohol and add deionized water to the alcohol. Filter the solution and wash the filter cake 2–3 times with deionized water. Dry the filter cake under vacuum at 80–160 °C for 12–36 h to obtain DDSQ anhydride. The molar ratio of product H to alkenyl anhydride is 1:5 to 8, and the volume fraction of the cassiterite catalyst in the reaction system is 0.01 to 0.1%. The mass fraction of solute is 15%–35%; Step 4: Add carbonic acid compound, phenolic compound, high-boiling-point solvent, nitro compound D and phosphorus-containing stabilizer M sequentially to a reaction vessel equipped with mechanical stirring. Stir and heat the system under argon protection. Continue stirring and reacting for 15 to 30 hours when the temperature reaches 80 to 160 °C. The molar ratio of the carbonate compound to the phenolic compound is 1 to 1.5:1; The molar ratio of the nitro compound D to the phenolic compound is 1:1 to 2.0; The phosphorus-containing stabilizer M has a mass fraction of 0.5% to 3.0%, and the solute content is controlled at 20 wt% to 30 wt%. The sum of the mass percentages of the above components is 100%; Step 5: When the system is cooled to 20-35 °C, pour the reaction system into deionized water to precipitate a brown precipitate; filter, wash the filter cake with deionized water 2-3 times to obtain the crude product; recrystallize the crude product, filter, collect the filter cake and dry it in a vacuum oven at 60-120 °C for 12-24 h to obtain product E; Step 6: Add DDSQ anhydride to a three-necked flask equipped with a water separator and a reflux condenser. Add carboxylic acid solvent G under an argon atmosphere and start mechanical stirring. Add product E and cyclohexane sequentially and heat the system to reflux. After reflux reaction for 5-12 h, slowly cool to 20-35 °C. Pour the reaction solution into distilled water, filter, and wash the filter cake 2-3 times with distilled water. Dry the filter cake in a vacuum oven at 60-120 °C for 12-24 h to obtain powdered product C. The molar ratio of the DDSQ anhydride to product E is 1:2; The molar ratio of product E to carboxylic acid solvent G is 1:100-150; The volume ratio of cyclohexane to carboxylic acid solvent G is 1:3 to 6; Step 7: Dissolve product C in solvent J, add palladium on carbon catalyst and phosphorus-containing stabilizer M, place the reaction system in a high-pressure reactor and react at room temperature in a hydrogen atmosphere for 5-25 h; the hydrogen pressure is maintained at 5-35 bar during the reaction; after the reaction, filter off the catalyst, remove solvent J by vacuum distillation, wash the product 2-3 times with toluene, and dry it in a vacuum oven at 60-120 °C for 12-24 h to obtain DDSQ diamine; The mass fraction of the solute is 10%-20%; The volume fraction of the phosphorus-containing stabilizer M is 1%-2%; The amount of palladium on carbon catalyst added is determined according to the ratio of 30-100 mg of catalyst to 1 mmol of nitro group; The method for preparing polyimide gas separation membranes using diamines containing DDSQ units is characterized by the following specific steps: Step 1: Add DDSQ diamine, diacid anhydride, diamine and high-boiling-point solvent sequentially to a reaction vessel equipped with a mechanical stirrer. Under argon protection, start stirring and cool the system. Continue stirring and reacting for 10-15 hours when the system temperature drops to 0-10°C. The molar ratio of the DDSQ diamine, diamine, and diacid anhydride is (1-x):x:1~1.05, where x ranges from 0 to 0.9; the solid content is controlled between 10 wt% and 30 wt%. Step 2: Raise the system temperature to 15-25°C, under argon protection, add dehydrating agent and catalyst, and continue stirring for 12-15 h; Step 3: Raise the system temperature to 50–80°C, protect with argon gas, and continue stirring for 4–8 hours; Step 4: When the system is cooled to 20-35°C, the reaction solution is poured into an alcohol solution to precipitate fibrous solid product. The product is filtered and the filter cake is washed with alcohol 2-4 times. The filter cake is dried in a vacuum oven at 80-160°C for 12-24 h to obtain polymer R. Step 5: Dissolve polymer R in a low-boiling-point solvent, controlling the solid content to 4 wt%–15 wt%, filter, and then pour onto a pre-leveled glass plate; place the glass plate in a vacuum oven at 25–40°C for 10–20 h, then raise the temperature to 80–120°C for 2–6 h; after the temperature drops to 20–35°C, remove the film to obtain a polyimide gas separation film containing DDSQ units; The diamine is any one or a combination of the following compounds, and its chemical structural formula is: ； The dicarboxylic acid anhydride is any one or a combination of the following compounds, and its chemical structural formula is: 。 2. The polyimide gas separation membrane prepared using a diamine containing DDSQ basic units according to claim 1, characterized in that: The solvent J is any one or a combination of methanol, tetrahydrofuran, ethyl acetate, acetonitrile, dichloromethane, ethanol, N,N-dimethylformamide, and N,N-dimethylacetamide.

3. The polyimide gas separation membrane prepared using a diamine containing DDSQ basic units according to claim 1, characterized in that: In step 2, the molar ratio of the dehydrating agent to the diacid anhydride is 3-5:1; the molar ratio of the catalyst to the diacid anhydride is 1-2:

1.

4. The polyimide gas separation membrane prepared using a diamine containing DDSQ basic units according to claim 1, characterized in that: The high-boiling-point solvent is any one or a combination of N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and dimethyl sulfoxide.

5. The polyimide gas separation membrane prepared using a diamine containing DDSQ basic units according to claim 1, characterized in that: The low-boiling-point solvent is any one or a combination of chloroform, dichloromethane, tetrahydrofuran, acetone, acetonitrile, and ethyl acetate.

Images