Polyimide intrinsic microporous membrane, diamine monomer adopted by polyimide intrinsic microporous membrane and preparation methods of polyimide intrinsic microporous membrane and diamine monomer

Abstract

The invention discloses a polyimide intrinsic microporous membrane, a diamine monomer adopted by the polyimide intrinsic microporous membrane and a preparation method of the polyimide intrinsic microporous membrane and the diamine monomer. The polyimide intrinsic microporous membrane is prepared from a dianhydride monomer and the diamine monomer with a dibenzo spirofluorene xanthene structure, the diamine monomer with the dibenzo spirofluorene xanthene structure is prepared by the following steps: firstly, condensing substituted or unsubstituted 2-nitro-9-fluorenone with 1-naphthol, then carrying out nitration, and finally, carrying out reduction, thereby obtaining the diamine monomer with the dibenzo spirofluorene xanthene structure. The dibenzo spirofluorene xanthene structure contained in the polyimide intrinsic microporous membrane can effectively reduce the dielectric constant of a polymer, the polyimide intrinsic microporous membrane can be applied to the technical field of electronics and microelectronics, the asymmetric diamine structure enables a main chain of a macromolecular chain to be twisted, the twisted macromolecular chain can effectively enlarge interchain pores, and therefore the polyimide intrinsic microporous membrane has the advantages that the dielectric constant of the polymer can be effectively reduced; therefore, the free volume of the polymer is increased, the polymer has higher permeability, selectivity can be balanced, and the polymer can be applied to the technical field of membrane separation.

Description

Technical Field

[0001] This invention belongs to the field of polymer technology, specifically relating to a polyimide self-porous membrane, the diamine monomer used therein, and their preparation methods. Background Technology

[0002] In the field of membrane separation, traditional separation and purification processes are typically accompanied by high energy consumption, while membrane separation technology, because it does not involve phase change, significantly reduces energy consumption. However, currently used separation membranes generally suffer from low gas permeability and insufficient selectivity. Therefore, the preparation of separation membranes with both high permeability and high selectivity is of great significance for realizing the national low-carbon development strategy and addressing the global energy crisis.

[0003] On the other hand, the rapid development of microelectronics and large-scale intelligent technologies has driven the evolution of electronic devices towards integration, miniaturization, and multifunctionality, but it has also led to problems such as signal transmission delay, crosstalk, and increased energy consumption. To address these challenges, the application of low-dielectric-constant materials is considered key to driving technological innovation in the field of microelectronics. However, traditional dielectric materials generally have high dielectric constants (k≈4.0), making it difficult to meet the current urgent need for low-dielectric-constant (k<3.0) materials.

[0004] Polyimide, as a class of aromatic heterocyclic polymers containing imide groups in its molecular structure, possesses excellent thermal stability, mechanical properties, film-forming properties, and solvent resistance, and has shown broad application prospects. However, its application in membrane separation is still limited by the inability to simultaneously achieve high permeability and high selectivity, which severely restricts its practical use. Therefore, developing polyimide separation membranes with both high permeability and high selectivity has become a critical problem that urgently needs to be solved.

[0005] Furthermore, in the fields of electronics and microelectronics, there is an urgent need to develop monomers that are widely available, inexpensive, and possess rigid, tortuous structures to reduce the dielectric constant of polymers, thereby enabling the large-scale preparation of low-dielectric polyimide materials. Therefore, the development of polyimide film materials with low dielectric constants and controllable costs is also of great significance for promoting the development of related technologies. Summary of the Invention

[0006] One of the objectives of this invention is to solve the above-mentioned problems and provide a polyimide self-porous membrane that not only has a low dielectric constant but also high permeability and high selectivity, as well as its preparation method and application.

[0007] Another object of the present invention is to provide a diamine monomer used in the above-mentioned polyimide self-porous membrane and a method for preparing the same.

[0008] One of the technical solutions to achieve the objective of this invention is: a diamine monomer, the general structural formula of which is shown below: .

[0009] In the formula, R 1 R 2 Each group is independently selected from hydrogen, deuterium, fluorine, chlorine, bromine, iodine, trifluoromethyl, hydroxyl, nitro, cyano, carboxyl, ester, amide, acyl, aldehyde, sulfonic acid, and C atoms. 1-50 Substituted or unsubstituted alkyl, C 1-50 Substituted or unsubstituted alkoxy groups, C 1-50 One or more of the substituted or unsubstituted aryl groups.

[0010] The C 1-50 Substituted or unsubstituted alkyl groups are further preferably C14. 1-8 The substituted or unsubstituted alkyl group is more preferably methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, n-pentyl, isopentyl, neopentyl, cyclopentyl, n-hexyl, cyclohexyl, n-octyl, etc.

[0011] The C 1-50 The substituted or unsubstituted alkoxy group is further preferably C. 1-8 The substituted or unsubstituted alkoxy group is more preferably methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, sec-butoxy, tert-butoxy, n-pentoxy, isopentoxy, neopentoxy, cyclopentoxy, n-hexyloxy, cyclohexyloxy, n-octoxy, etc.

[0012] The C 1-50 Substituted or unsubstituted aryl groups include all-carbon aryl groups and heteroaryl groups, wherein the heteroatoms of the heteroaryl group are oxygen atoms, nitrogen atoms, sulfur atoms, selenium atoms, etc.

[0013] Furthermore, the all-carbon aryl group is phenyl, naphthyl, anthracene, pyrene, perylene, etc.; the heteroaryl group is furanyl, pyridyl, naphthidyl, quinolinyl, isoquinolinyl, thiophene, etc.

[0014] The diamine monomer includes, but is not limited to, the following monomers: , , , , , , , , , , , , , , , , , , , .

[0015] The preparation method of the above-mentioned diamine monomer includes the following steps: ① The condensation reaction of substituted or unsubstituted 2-nitro-9-fluorenone (compound 1) with 1-naphthol yields the substituted or unsubstituted dibenzospirofluorenoxanthracene mononitro intermediate (compound 2). ②The substituted or unsubstituted dibenzospirofluoroxanthracene mononitro intermediate (compound 2) is nitrated to obtain the substituted or unsubstituted dibenzospirofluoroxanthracene dinitro intermediate (compound 3). ③ The substituted or unsubstituted dibenzospirofluorenexanthracene dinitro intermediate (compound 3) first undergoes an electrophilic substitution reaction to obtain R. 2 The substituted dibenzospirofluorenexanthracene dinitro intermediate (compound 4) was then reduced to give R. 2 Substituted dibenzospirofluorenexanthracene diamine monomer (compound 5); Alternatively, the substituted or unsubstituted dibenzospirofluoroxanthracene dinitro intermediate (compound 3) can be directly reduced to obtain the substituted or unsubstituted dibenzospirofluoroxanthracene diamine monomer [R]. 2 [It is a hydrogen atom].

[0016] The specific synthesis route is as follows: .

[0017] In the above synthetic route, R 1 R 2 The definition is the same as above.

[0018] In step ① above, the molar ratio of the substituted or unsubstituted 2-nitro-9-fluorenone to the 1-naphthol is 1:2 to 1:4.

[0019] The condensation reaction in step ① above is carried out in a first solvent; the first solvent is one or more of water, acetic acid, acetic anhydride, sulfuric acid, hydrobromic acid, methanesulfonic acid, trifluoromethanesulfonic acid, n-hexane, dichloroethane, dichloromethane, chloroform, bromoethane, N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, N-methylpyrrolidone, dioxane, methanol, ethanol and isopropanol, preferably acetic acid and / or hydrobromic acid.

[0020] The condensation reaction temperature in step ① above is 20 to 200°C, preferably 50 to 150°C, and more preferably 110 to 130°C.

[0021] The nitration reaction in step ② above is carried out in a second solvent; the second solvent is one or more of the following: water, acetic acid, acetic anhydride, sulfuric acid, hydrobromic acid, methanesulfonic acid, trifluoromethanesulfonic acid, n-hexane, dichloroethane, dichloromethane, chloroform, bromoethane, N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, N-methylpyrrolidone, dioxane, methanol, ethanol, and isopropanol, preferably acetic acid.

[0022] The nitrification reaction in step ② above uses one or more of the following nitrifying reagents: nitric acid, copper nitrate, potassium nitrate, sodium nitrate, sodium nitrite, ammonium nitrate, and silver nitrate, with nitric acid being preferred.

[0023] The nitration reaction temperature in step ② above is 0 to 150°C, preferably 20 to 100°C, and more preferably 50 to 70°C.

[0024] The reduction reaction in step ③ above is a conventional method in the field for reducing nitro compounds to amino compounds.

[0025] For example, precious metal catalysts such as palladium on carbon and Raney nickel can be used for catalytic hydrogenation, and reducing agents such as iron powder and zinc powder can be used for metal reduction. Reduction can also be carried out using reducing agents such as hydrazine hydrate, tetrahydroxydiborane, and stannous chloride.

[0026] The electrophilic substitution reaction in step ③ above is carried out in a third solvent; the third solvent is one or more of water, acetic acid, acetic anhydride, sulfuric acid, hydrobromic acid, methanesulfonic acid, trifluoromethanesulfonic acid, n-hexane, dichloroethane, dichloromethane, chloroform, N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, N-methylpyrrolidone, dioxane, methanol, ethanol and isopropanol, preferably dichloromethane.

[0027] The electrophilic substitution reagent used in step ③ above is based on R. 2 Depending on the substituent, for example, it can be R 2 -X, where X is a halogen, R 2 The definition is the same as above, and for example, it can be bromine, chlorine, etc.

[0028] The electrophilic substitution reaction temperature in step ③ above is -10 to 10℃.

[0029] Another technical solution to achieve the objective of this invention is: a polyimide microporous membrane, the general structural formula of which is shown below: .

[0030] In the formula, Ar is a dianhydride monomer residue, and R 1 R 2 The definition is the same as above.

[0031] In the formula, Ar is selected from one of the following structures: , , , , , , , , .

[0032] The above-mentioned method for preparing polyimide microporous membranes includes the following steps: ① Equimolar amounts of diamine monomer and dianhydride monomer are reacted in the presence of a catalyst and solvent at a temperature of 150–180°C to obtain a polyamic acid solution. ② Polyimide powder was prepared from the polyamic acid solution obtained in step ① using a solvent precipitation method; ③ After dissolving the polyimide powder obtained in step ② in a volatile solvent, the resulting solution is added to a petri dish, the solvent evaporates, and finally dried to obtain a polyimide microporous membrane.

[0033] In step ① above, the catalyst is one or more of isoquinoline, pyridine, triethylamine, benzoic acid, and acetic anhydride.

[0034] In step ① above, the solvent is one or more of m-cresol, tetrahydrofuran, N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, 1,4-dioxane, and chloroform.

[0035] In step ② above, the solvent used in the solvent precipitation method is one or more of water, ethanol, and methanol.

[0036] In step ③ above, the volatile solvent is one or more of chloroform, dichloromethane, 1,2-dichloroethane, 1,4-dioxane, tetrahydrofuran, N-methylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide.

[0037] In step ③ above, the drying temperature is 80–120°C and the time is 2–48 hours.

[0038] The above-mentioned applications of polyimide microporous membranes in the field of gas separation include: separating O2 from O2 / N2 mixed gas, or separating H2 from H2 / N2 mixed gas, or separating CO2 from CO2 / CH4 mixed gas, or separating H2 from H2 / CH4 mixed gas, or separating CO2 from CO2 / N2 mixed gas.

[0039] The aforementioned applications of polyimide microporous membranes in the electronics and microelectronics fields include: use as chip packaging materials to reduce signal transmission delay and crosstalk, and improve high-frequency performance; replacing traditional FR-4 materials, suitable for high-frequency and high-speed scenarios such as 5G communication and millimeter-wave radar; and reducing parasitic capacitance and improving chip speed in advanced processes (such as below 7nm).

[0040] The positive effects of this invention are: (1) The polyimide self-porous membrane of the present invention contains a dibenzospirofluorenexanthracene structure that inhibits polymer chain stacking through a vertical conformation of quaternary carbon linkage, thereby reducing the polymer density and thus reducing the dielectric constant of the polymer, and can be applied to the fields of electronics and microelectronics.

[0041] (2) The polyimide microporous membrane of the present invention contains a dibenzospirofluorenexanthracene structure that restricts the rotation of polymer chains through the quaternary carbon connection of the vertical conformation, thereby limiting the rotational movement between benzene rings. In particular, the asymmetric diamine structure causes the main chain of the polymer chain to be twisted. The twisted polymer chain can effectively increase the inter-chain porosity, thereby increasing the free volume of the polymer, making the polymer more permeable and able to balance selectivity. It can be applied to the field of membrane separation technology. Attached Figure Description

[0042] Figure 1 The image shows the 1H NMR spectrum of the diamine monomer prepared in Example 1.

[0043] Figure 2 The image shows the carbon NMR spectrum of the diamine monomer prepared in Example 1. Detailed Implementation

[0044] (Example 1) The structure of the diamine monomer in this example is as follows: .

[0045] The preparation method of this diamine monomer is as follows: ① Under a nitrogen atmosphere, 10g of 2-nitro-9-fluorenone and 15.36g of 1-naphthol were added to a mixed solution of 100mL hydrobromic acid and 100mL acetic acid, and the mixture was reacted at 120℃ for 24h.

[0046] After the reaction was completed, the organic phase was extracted with water and dichloromethane. The organic phase was dried by rotary evaporation and recrystallized. The solid was dried under vacuum to obtain 19.5 g of 2'-nitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene], with a yield of 92.0%.

[0047] ② Under a nitrogen atmosphere, 10 g of 2'-nitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene] was added to a mixed solution of 10 mL nitric acid and 100 mL acetic acid, and the reaction was carried out at 60 °C for 2 h.

[0048] After the reaction was completed, the organic phase was extracted with water and dichloromethane. The organic phase was dried by rotary evaporation and recrystallized. The solid was dried under vacuum to obtain 10.4 g of 2',5-dinitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene], with a yield of 95.0%.

[0049] ③ Under a hydrogen atmosphere, 10g of 2',5-dinitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene] was added to a 500mL three-necked flask, along with 200mL of ethyl acetate and 0.5g of 10wt% Pd / C catalyst. The reaction was carried out at room temperature for 48h.

[0050] After the reaction was completed, the mixture was filtered and evaporated to dryness to obtain 8.7 g of the diamine monomer spiro[dibenzo[c,h]xanthon-7,9'-fluorene]-2',5-diamine, with a yield of 98.3%.

[0051] The 1H NMR spectrum of the diamine monomer is shown below. Figure 1 The carbon NMR spectrum is shown below. Figure 2 The proton, carbon, and mass spectrometry data are as follows: 1 H NMR (400MHz, DMSO) d6 ): δ = 8.71 (d, 1H, J = 8.36 Hz), 8.65 (d, 1H, J = 8.48Hz), 8.05 (d, 1H, J = 8.40 Hz), 7.83 (d, 1H, J = 8.04 Hz), 7.76 (d, 1H, J = 7.88Hz), 7.72 (d, 1H, J = 9.36 Hz), 7.70 (t, 1H, J = 7.32 Hz, J = 7.92 Hz), 7.65 (d, 1H, J = 8.16 Hz), 7.59 (t, 1H, J = 7.28 Hz, J = 7.60 Hz), 7.52 (t, 1H, J = 7.60 Hz, J =7.64 Hz), 7.33 (d, 1H, J= 8.80 Hz), 7.32 (t, 1H, J = 7.52 Hz, J = 7.08 Hz), 7.02(t, 1H, J = 7.44 Hz, J = 7.12 Hz), 6.99 (t, 1H, J = 4.56 Hz, J = 7.36 Hz), 6.59 (d, 1H, J = 8.32 Hz), 6.29 (d, 1H, J = 8.76 Hz), 6.28 (s, 1H), 5.60 (s, 1H), 5.33 (s, 2H), 5.20 (s, 2H).

[0052] 13 C NMR (100MHz, DMSO) d6 ): δ= 157.97, 154.72, 150.161, 145.52, 141.51,140.86, 136.80, 133.26, 128.25, 128.04, 127.51, 127.11, 126.94, 126.79,126.21, 126.08,125.88, 125.32, 124.89, 124.33, 123.73, 123.07, 122.71,121.76, 121.68, 121.53, 119.72, 118.83, 118.68, 114.11, 110.98, 105.23, 53.96.

[0053] HRMS (ESI): calcd for C 33 H 23 N2O + [M+H] + , 463.1805; found, 463.1806.

[0054] (Example 2) The structure of the diamine monomer in this example is as follows: .

[0055] The preparation method of this diamine monomer is as follows: ① Under a nitrogen atmosphere, 10g of 2-methyl-7-nitro-9-fluorenone and 16.54g of 1-naphthol were added to a mixed solution of 100mL hydrobromic acid and 100mL acetic acid, and the mixture was reacted at 120℃ for 24h.

[0056] After the reaction was completed, the organic phase was extracted with water and dichloromethane. The organic phase was dried by rotary evaporation and recrystallized. The solid was dried under vacuum to obtain 17.7 g of 2'-methyl-7'-nitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene], with a yield of 86.2%.

[0057] ② Under a nitrogen atmosphere, 10 g of 2'-methyl-7'-nitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene] was added to a mixed solution of 10 mL nitric acid and 100 mL acetic acid, and the reaction was carried out at 60 °C for 2 h.

[0058] After the reaction was completed, the organic phase was extracted with water and dichloromethane. The organic phase was dried by rotary evaporation and recrystallized. The solid was dried under vacuum to give 10.1 g of 2'-methyl-5,7'-dinitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene], with a yield of 92.5%.

[0059] ③ Under a hydrogen atmosphere, 10g of 2'-methyl-5,7'-dinitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene] was added to a 500mL three-necked flask, along with 200mL of ethyl acetate and 0.5g of 10wt% Pd / C catalyst. The reaction was carried out at room temperature for 48h.

[0060] After the reaction was completed, the mixture was filtered and evaporated to dryness to obtain 8.7 g of the diamine monomer 7'-methylspiro[dibenzo[c,h]xanthon-7,9'-fluorene]-2',5-diamine, with a yield of 98.0%.

[0061] The proton, carbon, and mass spectrometry data of the diamine monomer are as follows: 1 H NMR (400MHz, DMSO) d6 ): δ = 8.81 (d, 1H, J = 8.16 Hz), 8.63 (d, 1H, J = 8.08Hz), 8.15 (d, 1H, J = 8.30 Hz), 7.81 (d, 1H, J = 8.34 Hz), 7.76 (d, 1H, J = 7.38Hz), 7.70 (d, 1H, J = 9.36 Hz), 7.68 (t, 1H, J = 7.32 Hz, J = 7.92 Hz), 7.63 (d, 1H, J = 8.16 Hz), 7.55 (t, 1H, J= 7.28 Hz, J = 7.60 Hz), 7.46 (t, 1H, J = 7.60 Hz, J =7.64 Hz), 7.31 (t, 1H, J = 7.52 Hz, J = 7.08 Hz), 7.06 (t, 1H, J = 7.44 Hz, J = 7.12Hz), 6.89 (d, 1H, J = 7.36 Hz), 6.56 (d, 1H, J = 8.32 Hz), 6.28 (d, 1H, J = 8.76Hz), 6.25 (s, 1H), 5.79 (s, 1H), 5.37 (s, 2H), 5.25 (s, 2H), 2.37 (s, 3H).

[0062] 13 C NMR (100MHz, DMSO) d6 ): δ= 156.87, 153.52, 151.11, 147.32, 143.21,141.83, 137.81, 135.21, 129.21, 128.33, 127.89, 127.21, 126.84, 126.54,126.11, 126.00, 125.67,125.25, 124.55, 124.11, 123.53, 123.02, 122.51,121.76, 121.53, 121.22, 119.24, 118.25, 118.58, 114.42, 110.23, 104.27, 52.84, 21.37.

[0063] HRMS (ESI): calcd for C 34 H 25 N2O + [M+H] + , 477.1961; found, 477.1960.

[0064] (Example 3) The structure of the diamine monomer in this example is as follows: .

[0065] The preparation method of this diamine monomer is as follows: ① Under a nitrogen atmosphere, 10g of 2-tert-butyl-7-nitro-9-fluorenone and 15.86g of 1-naphthol were added to a mixed solution of 100mL hydrobromic acid and 100mL acetic acid, and the mixture was reacted at 120℃ for 24h.

[0066] After the reaction was completed, the organic phase was extracted with water and dichloromethane. The organic phase was dried by rotary evaporation and recrystallized. The solid was dried under vacuum to obtain 17.1 g of 2'-tert-butyl-7'-nitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene], with a yield of 90.2%.

[0067] ② Under a nitrogen atmosphere, 10 g of 2'-tert-butyl-7'-nitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene] was added to a mixed solution of 10 mL nitric acid and 100 mL acetic acid, and the reaction was carried out at 60 °C for 2 h.

[0068] After the reaction was completed, the organic phase was extracted with water and dichloromethane. The organic phase was dried by rotary evaporation and recrystallized. The solid was dried under vacuum to obtain 9.5 g of 2'-tert-butyl-5,7'-dinitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene], with a yield of 87.6%.

[0069] ③ Under a hydrogen atmosphere, 10g of 2'-tert-butyl-5,7'-dinitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene] was added to a 500mL three-necked flask, along with 200mL of ethyl acetate and 0.5g of 10wt% Pd / C catalyst. The reaction was carried out at room temperature for 48h.

[0070] After the reaction was completed, the mixture was filtered and evaporated to dryness to obtain 8.5 g of the diamine monomer 7'-tert-butylspiro[dibenzo[c,h]xanthon-7,9'-fluorene]-2',5-diamine, with a yield of 94.8%.

[0071] The proton, carbon, and mass spectrometry data of the diamine monomer are as follows: 1 H NMR (400MHz, DMSO) d6 ): δ = 8.83 (d, 1H, J = 8.18 Hz), 8.65 (d, 1H, J = 8.10Hz), 8.17 (d, 1H, J = 8.32 Hz), 7.83 (d, 1H, J = 8.36 Hz), 7.78 (d, 1H, J = 7.42Hz), 7.72 (d, 1H, J = 9.30 Hz), 7.70 (t, 1H, J = 7.32 Hz,J = 7.92 Hz), 7.65 (d, 1H, J = 8.18 Hz), 7.57 (t, 1H, J = 7.30 Hz, J = 7.62 Hz), 7.48 (t, 1H, J = 7.62 Hz, J = 7.22 Hz), 7.33 (t, 1H, J = 7.52 Hz, J = 7.18 Hz), 7.08 (t, 1H, J = 7.46 Hz,[[ID=​​​​​​​​​​​​​​​​​​​​​​​​​​​​The structure of the diamine monomer in this example is as follows: .

[0075] The preparation method of this diamine monomer is as follows: ① Under a nitrogen atmosphere, 10g of 2-fluoro-7-nitro-9-fluorenone and 16.89g of 1-naphthol were added to a mixed solution of 100mL hydrobromic acid and 100mL acetic acid, and the mixture was reacted at 120℃ for 24h.

[0076] After the reaction was completed, the organic phase was extracted with water and dichloromethane. The organic phase was dried by rotary evaporation and recrystallized. The solid was dried under vacuum to obtain 17.0 g of 2'-fluoro-7'-nitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene], with a yield of 83.5%.

[0077] ② Under a nitrogen atmosphere, 10g of 2'-fluoro-7'-nitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene] was added to a mixed solution of 10mL nitric acid and 100mL acetic acid, and the reaction was carried out at 60℃ for 2h.

[0078] After the reaction was completed, the organic phase was extracted with water and dichloromethane. The organic phase was dried by rotary evaporation and recrystallized. The solid was dried under vacuum to obtain 9.9 g of 2'-fluoro-5,7'-dinitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene], with a yield of 90.8%.

[0079] ③ Add 10g of iron powder and 10g of 2'-fluoro-5,7'-dinitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene] to 180mL of boiling ethanol, add 250mL of concentrated hydrochloric acid dropwise over 1 hour, and continue the reaction for 2 hours. After cooling, wash with a small amount of ethanol and alkaline water, and finally extract and evaporate to dryness to obtain 8.4g of the diamine monomer 7'-fluorospiro[dibenzo[c,h]xanthon-7,9'-fluorene]-2',5-diamine, with a yield of 94.5%.

[0080] The proton, carbon, and mass spectrometry data of the diamine monomer are as follows: 1 H NMR (400MHz, DMSO) d6 ): δ = 8.88 (d, 1H, J = 8.00 Hz), 8.72 (d, 1H, J = 8.02Hz), 8.13 (d, 1H, J = 7.90 Hz), 7.91 (d, 1H, J = 8.54 Hz), 7.77 (d, 1H, J = 7.36Hz), 7.69 (d, 1H,J = 8.24 Hz), 7.67 (t, 1H, J = 7.68 Hz, J = 7.88 Hz), 7.65 (d,1H, J = 7.86 Hz), 7.59 (t, 1H, J = 7.60 Hz, J = 7.60 Hz), 7.47 (t, 1H, J = 7.60 Hz, J =7.64 Hz), 7.30 (t, 1H, J = 7.52 Hz, J = 7.52 Hz), 7.21 (t, 1H, J = 7.44 Hz, J = 7.44Hz), 6.93 (d, 1H, J = 7.38 Hz), 6.58 (d, 1H, J = 8.12 Hz), 6.70 (d, 1H, J = 8.46Hz), 6.35 (s, 1H), 5.59 (s, 1H), 5.37 (s, 2H), 5.25 (s, 2H)。

[0081] 13 C NMR(100MHz,DMSO d6 ):δ= 156.57, 152.52, 150.12, 148.34, 144.61,142.73, 139.11, 136.74, 133.75, 130.29, 128.74, 127.59, 126.99, 126.44,126.23, 126.02, 125.86,125.37, 124.48, 124.07, 123.68, 123.09, 122.41,121.54, 121.01, 120.23, 119.27, 118.77, 118.23, 113.12, 110.33, 103.74,53.97。

[0082] HRMS(ESI):calcd for C 33 H 22 FN2O + [M+H] + ,481.1711;found,481.1707。

[0083] (Example 5) The structure of the diamine monomer in this example is as follows: .

[0084] The preparation method of this diamine monomer is as follows: ① Under a nitrogen atmosphere, 10 g of 2-bromo-7-nitro-9-fluorenone and 15.29 g of 1-naphthol were added to a mixed solution of 100 mL of hydrobromic acid and 100 mL of acetic acid, and the mixture was reacted at 120 °C for 24 h.

[0085] After the reaction was completed, the organic phase was extracted with water and dichloromethane. The organic phase was dried by rotary evaporation and recrystallized. The solid was dried under vacuum to give 16.1 g of 2'-bromo-7'-nitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene], with a yield of 88.0%.

[0086] ② Under a nitrogen atmosphere, 10 g of 2'-bromo-7'-nitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene] was added to a mixed solution of 10 mL nitric acid and 100 mL acetic acid, and the reaction was carried out at 60 °C for 2 h.

[0087] After the reaction was completed, the organic phase was extracted with water and dichloromethane. The organic phase was dried by rotary evaporation and recrystallized. The solid was dried under vacuum to obtain 9.9 g of 2'-bromo-5,7'-dinitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene], with a yield of 91.6%.

[0088] ③ Add 10g of iron powder and 10g of 2'-bromo-5,7'-dinitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene] to 180mL of boiling ethanol, add 250mL of concentrated hydrochloric acid dropwise over 1 hour, and continue the reaction for 2 hours. After cooling, wash with a small amount of ethanol and alkaline water, and finally extract and evaporate to dryness to obtain 8.7g of the diamine monomer 7'-bromospiro[dibenzo[c,h]xanthon-7,9'-fluorene]-2',5-diamine, with a yield of 96.6%.

[0089] The proton, carbon, and mass spectrometry data of the diamine monomer are as follows: 1 H NMR (400MHz, DMSO) d6 ): δ = 8.79 (d, 1H, J = 7.56 Hz), 8.52 (d, 1H, J = 8.10Hz), 8.19 (d, 1H, J = 7.60 Hz), 7.98 (d, 1H, J = 8.20 Hz), 7.79 (d, 1H, J= 7.46Hz), 7.68 (d, 1H, J = 8.34 Hz), 7.66 (t, 1H, J = 7.78 Hz, J = 7.88 Hz), 7.63 (d,1H, J = 7.86 Hz), 7.53 (t, 1H, J = 7.60 Hz, J = 7.50 Hz), 7.43 (t, 1H, J = 7.62 Hz, J =7.64 Hz), 7.32 (t, 1H, J = 7.52 Hz, J = 7.54 Hz), 7.21 (t, 1H, J = 7.48 Hz, J = 7.44Hz), 6.99 (d, 1H, J = 7.32 Hz), 6.58 (d, 1H, J = 8.02 Hz), 6.70 (d, 1H, J = 8.06Hz), 6.33 (s, 1H), 5.66 (s, 1H), 5.39 (s, 2H), 5.23 (s, 2H)。

[0090] 13 C NMR(100MHz,DMSO d6 ):δ= 156.62, 152.51, 151.47, 148.39, 144.65,142.70, 139.16, 136.72, 133.78, 130.25, 128.71, 127.56, 126.94, 126.42,126.20, 126.05, 125.83,125.35, 124.45, 124.03, 123.66, 123.07, 122.43,121.57, 121.04, 120.21, 119.29, 118.75, 118.26, 113.15, 110.30, 103.77,53.99。

[0091] HRMS(ESI):calcd for C 33 H 22 BrN2O + [M+H] +, 541.0910; found, 541.0907.

[0092] (Example 6) The structure of the diamine monomer in this example is as follows: .

[0093] The preparation method of this diamine monomer is as follows: ① Same as Example 1.

[0094] ② Same as Example 1.

[0095] ③ Under a nitrogen atmosphere and at 0°C, add 10g of 2',5-dinitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene], a catalytic amount of elemental iodine, and 100mL of dichloromethane to a 250mL three-necked flask, stir for 10min, then add a mixed solution of 1mL bromine and 40mL dichloromethane dropwise. After the addition is complete, stir the reaction at 0°C for 3h.

[0096] After the reaction was completed, the product was extracted by adding 200 mL of water and sodium bisulfite solution. The extraction was repeated three times, and the dichloromethane phase was retained. The dichloromethane phase was evaporated to dryness, and the resulting viscous solution was recrystallized with 100 mL of anhydrous ethanol to give 8.6 g of 5-bromo-2',9-dinitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene], with a yield of 74.7%.

[0097] ④ Add 10g of iron powder and 10g of 5-bromo-2',9-dinitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene] to 180mL of boiling ethanol, add 250mL of concentrated hydrochloric acid dropwise over 1 hour, and continue the reaction for 2 hours. After cooling, wash with a small amount of ethanol and alkaline water, and finally extract and evaporate to dryness to obtain 8.3g of the diamine monomer 9-bromospiro[dibenzo[c,h]xanthon-7,9'-fluorene]-2',5-diamine, with a yield of 92.2%.

[0098] The proton, carbon, and mass spectrometry data of the diamine monomer are as follows: 1 H NMR (400MHz, DMSO) d6 ): δ = 8.73 (d, 1H, J = 8.38 Hz), 8.67 (d, 1H, J = 8.52Hz), 8.07 (d, 1H, J = 8.40 Hz), 7.85 (d, 1H, J = 8.06 Hz), 7.78 (d, 1H, J = 7.90Hz), 7.72 (t, 1H,J = 7.32 Hz, J = 7.98 Hz), 7.67 (d, 1H, J = 8.16 Hz), 7.61 (t,1H, J = 7.30 Hz, J = 7.62 Hz), 7.54 (t, 1H, J = 7.64 Hz, J = 7.24 Hz), 7.35 (d, 1H, J =8.42 Hz), 7.34 (t, 1H, J = 7.52 Hz, J = 7.14 Hz), 7.04 (t, 1H, J = 7.42 Hz, J = 7.16Hz), 7.01 (t, 1H, J = 5.58 Hz, J = 7.32 Hz), 6.61 (s, 1H), 6.52 (d, 1H, J = 8.76Hz), 6.30 (s, 1H), 5.62 (s, 1H), 5.35 (s, 2H), 5.22 (s, 2H)。

[0099] 13 C NMR(100MHz,DMSO d6 ):δ= 157.99, 154.75, 150.19, 145.55, 141.54,140.89, 136.83, 133.29, 128.28, 128.07, 127.54, 127.14, 126.97, 126.82,126.24, 126.11, 125.91,125.35, 124.92, 124.36, 123.76, 123.10, 122.74,121.79, 121.71, 121.56, 119.75, 118.86, 118.71, 114.14, 111.01, 105.26,54.20。

[0100] HRMS(ESI):calcd for C 33 H 22 BrN2O + [M+H] + ,541.0910;found,541.0913。

[0101] (Example 7) The structure of the diamine monomer in this example is as follows: .

[0102] The preparation method of this diamine monomer is as follows: ① Same as Example 1.

[0103] ② Same as Example 1.

[0104] ③ Under a nitrogen atmosphere and at 0°C, add 10g of 2',5-dinitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene], an equivalent amount of aluminum trichloride, and 100mL of dichloromethane to a 250mL three-necked flask, stir for 10min, and then add dropwise 40mL of a mixed solution of bromoethane and dichloromethane. After the addition is complete, stir the reaction at 0°C for 3h.

[0105] After the reaction was completed, the product was extracted with 200 mL of water. The extraction was repeated three times, and the dichloromethane phase was retained. The dichloromethane phase was evaporated to dryness, and the resulting viscous solution was recrystallized with 100 mL of anhydrous ethanol to obtain 8.5 g of 5-ethyl-2',9-dinitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene], with a yield of 80.7%.

[0106] ④ Under a hydrogen atmosphere, 10g of 5-ethyl-2',9-dinitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene] was added to a 500mL three-necked flask, along with 200mL of ethyl acetate and 0.5g of 10wt% Pd / C catalyst. The reaction was carried out at room temperature for 48h.

[0107] After the reaction was completed, the mixture was filtered and evaporated to dryness to obtain 8.2 g of the diamine monomer 9-ethylspiro[dibenzo[c,h]xanthon-7,9'-fluorene]-2',5-diamine, with a yield of 92.0%.

[0108] The proton, carbon, and mass spectrometry data of the diamine monomer are as follows: 1 H NMR (400MHz, DMSO) d6 ): δ = 8.77 (d, 1H, J = 8.32 Hz), 8.64 (d, 1H, J = 8.56Hz), 8.04 (d, 1H, J = 8.30 Hz), 7.81 (d, 1H, J = 8.02 Hz), 7.77 (d, 1H, J = 7.60Hz), 7.70 (t, 1H, J = 7.42 Hz,J = 7.68 Hz), 7.65 (d, 1H, J = 8.36 Hz), 7.61 (t,1H, J = 7.20 Hz, J = 7.52 Hz), 7.56 (t, 1H, J = 7.64 Hz, J = 7.34 Hz), 7.36 (d, 1H, J =8.32 Hz), 7.33 (t, 1H, J = 7.32 Hz, J = 7.54 Hz), 7.03 (t, 1H, J = 7.52 Hz, J = 7.12Hz), 7.00 (t, 1H, J = 6.58 Hz, J = 7.32 Hz), 6.60 (s, 1H), 6.51 (d, 1H, J = 8.36Hz), 6.30 (s, 1H), 5.61 (s, 1H), 5.37 (s, 2H), 5.23 (s, 2H), 3.17 (q, 2H, J =7.48 Hz, J = 7.16 Hz, J = 7.32 Hz), 1.33 (t,3H, J = 7.58 Hz, J = 7.26 Hz, J = 7.46 Hz)。

[0109] 13 C NMR(100MHz,DMSO d6): δ= 157.92, 154.72, 150.15, 145.54, 141.52,140.89, 136.85, 133.20, 128.23, 128.00, 127.56, 127.13, 126.87, 126.81,126.17, 126.11, 125.71,125.36, 124.91, 124.23, 123.86, 123.30, 122.64,121.76, 121.75, 121.57, 119.86, 118.75, 118.55, 114.35, 111.03, 105.27, 54.33, 26.55, 14.64.

[0110] HRMS (ESI): calcd for C 35 H 27 N2O + [M+H] + , 491.2118; found, 491.2115.

[0111] (Example 8) The structure of the diamine monomer in this example is as follows: .

[0112] The preparation method of this diamine monomer is as follows: ① Same as Example 1.

[0113] ② Same as Example 1.

[0114] ③ Under a nitrogen atmosphere and at 0°C, add 10g of 2',5-dinitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene], an equivalent amount of aluminum trichloride, and 100mL of dichloromethane to a 250mL three-necked flask, stir for 10min, and then add dropwise 40mL of a mixed solution of an equivalent amount of tert-butyl chloride and dichloromethane. After the addition is complete, stir the reaction at 0°C for 3h.

[0115] After the reaction was completed, the product was extracted with 200 mL of water. The extraction was repeated three times, and the dichloromethane phase was retained. The dichloromethane phase was evaporated to dryness, and the resulting viscous solution was recrystallized with 100 mL of anhydrous ethanol to give 8.3 g of 5-tert-butyl-2',9-dinitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene], with a yield of 75.0%.

[0116] ④ Under a hydrogen atmosphere, 10 g of 5-tert-butyl-2',9-dinitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene] was added to a 500 mL three-necked flask, along with 200 mL of ethyl acetate and 0.5 g of 10 wt% Pd / C catalyst. The reaction was carried out at room temperature for 48 h.

[0117] After the reaction was completed, the mixture was filtered and evaporated to dryness to obtain 8.3 g of the diamine monomer 9-tert-butylspiro[dibenzo[c,h]xanthon-7,9'-fluorene]-2',5-diamine, with a yield of 92.6%.

[0118] The proton, carbon, and mass spectrometry data of the diamine monomer are as follows: 1 H NMR (400MHz, DMSO) d6 ): δ = 8.73 (d, 1H, J = 8.22 Hz), 8.65 (d, 1H, J = 8.54Hz), 8.01 (d, 1H, J = 8.20 Hz), 7.80 (d, 1H, J = 8.12 Hz), 7.75 (d, 1H, J = 7.50Hz), 7.71 (t, 1H, J = 7.22 Hz, J = 7.60 Hz), 7.64 (d, 1H, J = 8.34 Hz), 7.60 (t, 1H, J = 7.00 Hz, J = 7.42 Hz), 7.53 (t, 1H, J = 7.62 Hz, J = 7.32 Hz), 7.32 (d, 1H, J =8.34 Hz), 7.30 (t, 1H, J = 7.30 Hz, J = 7.24 Hz), 7.02 (t, 1H, J = 7.22 Hz, J = 7.34Hz), 7.00 (t, 1H, J = 6.56 Hz, J = 7.34 Hz), 6.65 (s, 1H), 6.50 (d, 1H, J= 8.36Hz), 6.30 (s, 1H), 5.61 (s, 1H), 5.37 (s, 2H), 5.23 (s, 2H), 1.49 (s, 9H).

[0119] 13 C NMR (100MHz, DMSO) d6 ): δ= 157.92, 154.72, 150.15, 145.54, 141.52,140.89, 136.85, 133.20, 128.23, 128.00, 127.56, 127.13, 126.87, 126.81,126.17, 126.11, 125.71,125.36, 124.91, 124.23, 123.86, 123.30, 122.64,121.76, 121.75, 121.57, 119.86, 118.75, 118.55, 114.35, 111.03, 105.27, 54.33, 35.7, 31.1.

[0120] HRMS (ESI): calcd for C 37 H 31 N2O + [M+H] + , 519.2431; found, 519.2430.

[0121] (Example 1) The structure of the polyimide microporous membrane in this embodiment is as follows: .

[0122] The preparation method of this polyimide microporous membrane is as follows: ① Under a nitrogen atmosphere, 0.924 g (2 mmol) of the diamine monomer spiro[dibenzo[c,h]xanthon-7,9'-fluorene]-2',5-diamine from Example 1 was added to a three-necked flask equipped with a magnetic stir bar. Then, 5 mL of m-cresol solvent was added and stirring was started. Next, 0.436 g (2 mmol) of pyromellitic dianhydride (PMDA) and 0.2 mL of isoquinoline catalyst were added. The temperature was raised to 170 °C. After complete dissolution, the reaction proceeded until the magnetic stir bar could no longer rotate (viscosity approximately 10 W cps), resulting in a viscous polyamic acid solution.

[0123] ② Slowly pour the obtained viscous polyamic acid solution into an ethanol solution, let it stand to precipitate, and then place the solid polymer in a vacuum oven at 120°C for 48 hours to obtain a polyimide polymer.

[0124] ③ Dissolve the polyimide polymer in chloroform and stir thoroughly to dissolve the solute. Then filter the solution through a 0.45μm PTFE filter into a petri dish with a smooth surface. After the solvent evaporates, a polyimide film is obtained. Further heat it in an oven at 120℃ for 2 hours to ensure that the remaining solvent is completely removed, and a polyimide microporous membrane is obtained.

[0125] (Example 2) The structure of the polyimide microporous membrane in this embodiment is as follows: .

[0126] The preparation method of the polyimide self-porous membrane is basically the same as that in Example 1, except that the dianhydride monomer used is an equimolar amount of hexafluorodianhydride (6FDA), as shown in Table 1.

[0127] (Example 3) The structure of the polyimide microporous membrane in this embodiment is as follows: .

[0128] The preparation method of the polyimide self-porous membrane is basically the same as that in Example 1, except that the dianhydride monomer used is an equimolar amount of 3,3',4,4'-benzophenone tetracarboxylic dianhydride (BTDA).

[0129] (Example 4) The structure of the polyimide microporous membrane in this embodiment is as follows: .

[0130] The preparation method of the polyimide self-porous membrane is basically the same as that in Example 1, except that the dianhydride monomer used is an equimolar amount of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride (BPDA).

[0131] (Example 5) The structure of the polyimide microporous membrane in this embodiment is as follows: .

[0132] The preparation method of the polyimide self-porous membrane is basically the same as that in Example 1, except that the dianhydride monomer used is an equimolar amount of 4,4'-oxybisphthalic anhydride (ODPA).

[0133] (Example 6) The structure of the polyimide microporous membrane in this embodiment is as follows: .

[0134] The preparation method of the polyimide self-porous membrane is basically the same as that in Example 1, except for the types of diamine monomer and dianhydride monomer (both 2 mmol), as shown in Table 1.

[0135] (Example 7) The structure of the polyimide microporous membrane in this embodiment is as follows: .

[0136] The preparation method of the polyimide self-porous membrane is basically the same as that in Example 1, except for the types of diamine monomer and dianhydride monomer (both 2 mmol), as shown in Table 1.

[0137] (Example 8) The structure of the polyimide microporous membrane in this embodiment is as follows: .

[0138] The preparation method of the polyimide self-porous membrane is basically the same as that in Example 1, except for the types of diamine monomer and dianhydride monomer (both 2 mmol), as shown in Table 1.

[0139] (Example 9) The structure of the polyimide microporous membrane in this embodiment is as follows: .

[0140] The preparation method of the polyimide self-porous membrane is basically the same as that in Example 1, except for the types of diamine monomer and dianhydride monomer (both 2 mmol), as shown in Table 1.

[0141] (Comparison Example 1) The structure of the diamine monomer in Comparative Example 1 is as follows: .

[0142] The preparation method of this diamine monomer is as follows: ① Under a nitrogen atmosphere, 10g of 2,7-dinitro-9-fluorenone and 15.36g of 1-naphthol were added to a mixed solution of 100mL hydrobromic acid and 100mL acetic acid, and the mixture was reacted at 120℃ for 24h.

[0143] After the reaction was completed, the organic phase was extracted with water and dichloromethane. The organic phase was dried by rotary evaporation and recrystallized. The solid was dried under vacuum to obtain 17.7 g of 2',7'-dinitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene], with a yield of 91.6%.

[0144] ② Under a hydrogen atmosphere, 10 g of 2',7'-dinitrospiro[dibenzo[c,h]xanthon-7,9'-fluorene] was added to a 500 mL three-necked flask, along with 200 mL of ethyl acetate and 0.5 g of 10 wt% Pd / C catalyst. The reaction was carried out at room temperature for 48 h.

[0145] After the reaction was completed, the mixture was filtered and evaporated to dryness to obtain 8.5 g of the diamine monomer spiro[dibenzo[c,h]xanthon-7,9'-fluorene]-2',7'-diamine, with a yield of 96.0%.

[0146] (Comparative Examples 1 to 2) Following the method of Example 1, polyimide films were prepared by using the diamine monomer spiro[dibenzo[c,h]xanthon-7,9'-fluorene]-2',7'-diamine of Comparative Example 1 with equimolar amounts of pyromellitic dianhydride (PMDA) and hexafluorodianhydride (6FDA), as detailed in Table 1.

[0147] Table 1 diamine monomer Dihydride monomer Dielectric constant Example 1 Example 1 PMDA 2.75 Example 2 Example 1 6FDA 2.63 Example 3 Example 1 BTDA 2.52 Example 4 Example 1 BPDA 2.68 Example 5 Example 1 ODPA 2.67 Example 6 Example 5 PMDA 2.73 Example 7 Example 5 6FDA 2.62 Example 8 Example 7 PMDA 2.63 Example 9 Example 7 6FDA 2.66 Comparative Example 1 Comparison Example 1 PMDA 3.06 Comparative Example 2 Comparison Example 1 6FDA 2.77

[0148] (Test Example 1) The dielectric constants of the polyimide films prepared in each embodiment and Comparative Examples 1 and 2 were tested, and the results are shown in Table 1.

[0149] As can be seen from Table 1, the polyimide films obtained using the diamine monomer of this application and the diamine monomer of Comparative Example 1 both have low dielectric constants.

[0150] (Test Example 2) The gas separation performance of the polyimide films prepared in Examples 1, 2, 6, and 7, as well as Comparative Examples 1 and 2, was tested, and the results are shown in Table 2.

[0151] Table 2 .

[0152] As can be seen from Table 2, the polyimide film obtained by using the asymmetric diamine monomer of this application has excellent gas permeation performance, which is significantly better than the polyimide film obtained by using the symmetric diamine monomer of Comparative Example 1.

Claims

1. A polyimide microporous membrane, the general structural formula of which is shown below: ； In the formula, Ar is a dianhydride monomer residue, and R 1 R 2 Each group is independently selected from hydrogen, deuterium, fluorine, chlorine, bromine, iodine, trifluoromethyl, hydroxyl, nitro, cyano, carboxyl, ester, amide, acyl, aldehyde, sulfonic acid, and C atoms. 1-50 Substituted or unsubstituted alkyl, C 1-50 Substituted or unsubstituted alkoxy groups, C 1-50 One or more of the substituted or unsubstituted aryl groups.

2. The polyimide self-porous membrane according to claim 1, characterized in that: In the formula, R 1 R 2 Each atom is independently selected from hydrogen, fluorine, chlorine, bromine, iodine, trifluoromethyl, cyano, acyl, sulfonic acid, and C atoms. 1-8 Substituted or unsubstituted alkyl, C 1-8 One or more of substituted or unsubstituted alkoxy groups.

3. The polyimide self-porous membrane according to claim 2, characterized in that: In the formula, R 1 R 2 Each atom is independently selected from hydrogen, fluorine, chlorine, bromine, iodine, and carbon atoms. 1-4 Substituted or unsubstituted alkyl groups.

4. The polyimide self-porous membrane according to any one of claims 1 to 3, characterized in that: In the formula, Ar is selected from one of the following structures: 、 、 、 、 、 、 、 、 。 5. A method for preparing a polyimide self-porous membrane according to any one of claims 1 to 3, characterized in that... It includes the following steps: ① Equimolar amounts of diamine monomer and dianhydride monomer are reacted in the presence of a catalyst and solvent at a temperature of 150–180°C to obtain a polyamic acid solution. ② Polyimide powder was prepared from the polyamic acid solution obtained in step ① using a solvent precipitation method; ③ After dissolving the polyimide powder obtained in step ② in a volatile solvent, the resulting solution is added to a petri dish, the solvent evaporates, and finally dried to obtain a polyimide microporous membrane.

6. The application of a polyimide self-porous membrane according to any one of claims 1 to 3 in the fields of gas separation and electronics and microelectronics.

7. A diamine monomer, the general structural formula of which is shown below: ； In the formula, R 1 R 2 Each group is independently selected from hydrogen, deuterium, fluorine, chlorine, bromine, iodine, trifluoromethyl, hydroxyl, nitro, cyano, carboxyl, ester, amide, acyl, aldehyde, sulfonic acid, and C atoms. 1-50 Substituted or unsubstituted alkyl, C 1-50 Substituted or unsubstituted alkoxy groups, C 1-50 One or more of the substituted or unsubstituted aryl groups.

8. The diamine monomer according to claim 7, characterized in that: In the formula, R 1 R 2 Each atom is independently selected from hydrogen, fluorine, chlorine, bromine, iodine, trifluoromethyl, cyano, acyl, sulfonic acid, and C atoms. 1-8 Substituted or unsubstituted alkyl, C 1-80 One or more of substituted or unsubstituted alkoxy groups.

9. The diamine monomer according to claim 8, characterized in that: In the formula, R 1 R 2 Each atom is independently selected from hydrogen, fluorine, chlorine, bromine, iodine, and carbon atoms. 1-4 Substituted or unsubstituted alkyl groups.

10. A method for preparing the diamine monomer according to any one of claims 7 to 9, characterized in that... It includes the following steps: ①The condensation reaction of substituted or unsubstituted 2-nitro-9-fluorenone with 1-naphthol yields a substituted or unsubstituted dibenzospirofluorenoxanthracene mononitro intermediate; ②The substituted or unsubstituted dibenzospirofluoroxanthracene mononitro intermediate is nitrated to obtain the substituted or unsubstituted dibenzospirofluoroxanthracene dinitro intermediate; ③ The substituted or unsubstituted dibenzospirofluorenexanthracene dinitro intermediate is first subjected to an electrophilic substitution reaction to obtain R. 2 The substituted dibenzospirofluorenexanthracene dinitro intermediate is then reduced to give R. 2 Substituted dibenzospirofluorenexanthracene diamine monomers; Alternatively, the substituted or unsubstituted dibenzospirofluoroxanthracene dinitro intermediate can be directly reduced to obtain the substituted or unsubstituted dibenzospirofluoroxanthracene diamine monomer.

Images