Semi-aromatic polyimide, preparation method and application thereof, and gas separation membrane comprising semi-aromatic polyimide
阅读说明：本技术 一种半芳香型聚酰亚胺、其制备方法、用途和包含其的气体分离膜 (Semi-aromatic polyimide, preparation method and application thereof, and gas separation membrane comprising semi-aromatic polyimide ) 是由 庄永兵 张宇 万印华 于 2019-10-15 设计创作，主要内容包括：本发明提供了一种半芳香型聚酰亚胺材料、其制备方法、用途和包含其的气体分离膜。所述半芳香型聚酰亚胺具有式I所示结构,可用作气体分离膜材料,是通过采用芳族二酐和芳族或脂族二胺合成含酰亚胺链节的二胺单体I,脂环族二酐和芳族或脂族二胺合成含酰亚胺链节的二胺单体II,然后将二胺单体I和二胺单体II在起源剂的作用下聚合得到。本发明提供的半芳香型聚酰亚胺分子链中具有朝格尔碱基结构,且主链中芳环结构与脂环结构相配合,由其制备的气体分离膜具有良好的机械性能和耐热稳定性,用于氢气分离和空气分离时具有高的渗透系数和较好的选择性。(The invention provides a semi-aromatic polyimide material, a preparation method and application thereof, and a gas separation membrane containing the semi-aromatic polyimide material. The semi-aromatic polyimide has a structure shown in a formula I, can be used as a gas separation membrane material, and is prepared by synthesizing a diamine monomer I containing imide chain segments by adopting aromatic dianhydride and aromatic or aliphatic diamine, synthesizing a diamine monomer II containing imide chain segments by adopting alicyclic dianhydride and aromatic or aliphatic diamine, and polymerizing the diamine monomer I and the diamine monomer II under the action of an initiator. The semi-aromatic polyimide molecular chain provided by the invention has a Ruger base structure, and an aromatic ring structure in a main chain is matched with an alicyclic structure, so that the prepared gas separation membrane has good mechanical property and heat-resistant stability, and has high permeability coefficient and good selectivity when being used for hydrogen separation and air separation.)
1. A semi-aromatic polyimide, wherein the semi-aromatic polyimide has a structure represented by formula I:
in the formula I, R1Is an aromatic dianhydride residue, R3Is a cycloaliphatic dianhydride residue, R2、R4Each independently an aromatic diamine residue or an aliphatic diamine residue;
x and y are each independently integers from 1 to 50, and m: n is 1:9 to 9: 1.
2. The semi-aromatic polyimide according to claim 1, wherein the molecular chain of the semi-aromatic polyimide has a troger base structure;
preferably, the semi-aromatic polyimide has a weight average molecular weight of 5 to 100 ten thousand, preferably 5 to 50 ten thousand.
3. The semi-aromatic polyimide according to claim 1 or 2, wherein R in formula I1Any one selected from the following substituted or unsubstituted groups:
preferably, in formula I, R3Any one selected from the following substituted or unsubstituted groups:
wherein the dotted line represents the position of the group attachment, and when the group contains a substituent as described above, the substituent is selected from any one of methyl, methoxy, halogen, hydroxy, cyano, heteroaryl, heterocycloalkyl, and amino.
4. According to the rightThe semi-aromatic polyimide according to any one of claims 1 to 3, wherein R in formula I2、R4Each independently selected from any one of the following substituted or unsubstituted groups:
wherein the dotted line represents the position of the group attachment, and when the group contains a substituent as described above, the substituent is selected from any one of methyl, methoxy, halogen, hydroxy, cyano, heteroaryl, heterocycloalkyl, and amino;
preferably, x and y are each independently an integer of 1 to 4.
5. A process for preparing a semi-aromatic polyimide according to any of claims 1 to 4, comprising the steps of:
step (1): with aromatic dianhydrides AAnd aromatic or aliphatic diamines B H2N-R2-NH2Synthesizing a diamine monomer I containing imide chain links as a raw material
Step (2): with alicyclic dianhydrides CAnd aromatic or aliphatic diamines D H2N-R4-NH2Synthesizing a diamine monomer II containing imide chain links as a raw material
And (3): dissolving a diamine monomer I obtained in the step (1) and a diamine monomer II obtained in the step (2) in an acidic solvent, wherein the mass ratio of the diamine monomer I to the diamine monomer II is 1:9-9:1, preparing a monomer mixed solution, adding an initiator, and reacting under a protective atmosphere to obtain the semi-aromatic polyimide;
wherein, x, y, R1、R2、R3And R4Having the same limitations as any one of claims 1 to 4.
6. The method according to claim 5, wherein the aromatic dianhydride A is selected from the group consisting of pyromellitic dianhydride, 4' - (hexafluoroisopropylidene) diphthalic anhydride, 1,4,5, 8-naphthalene tetracarboxylic anhydride, 3,4,9, 10-perylene tetracarboxylic dianhydride, triptycene-2, 3,6, 7-tetracarboxylic dianhydride, one or a combination of at least two of 9,9 '-spirobifluorene-2, 2',3,3 '-tetracarboxylic dianhydride, 3,3',4,4 '-benzophenone tetracarboxylic dianhydride, 3,3',4,4 '-diphenyl ether tetracarboxylic dianhydride, 3,3',4,4 '-biphenyl tetracarboxylic dianhydride, 9-bis (3, 4-dicarboxyphenyl) fluorene dianhydride, or 4,4' -dinaphthalene-1, 1',8,8' -tetracarboxylic dianhydride;
preferably, the alicyclic dianhydride C is selected from 1,2,4, 5-cyclohexanetetracarboxylic dianhydride, 5,6,7, 8-bicyclo [2.2.2] -2-heptenetetracarboxylic dianhydride, 1,2,3, 4-cyclobutanetetracarboxylic dianhydride, 1,2,3, 4-cyclopentanetetracarboxylic dianhydride, 1,2,3, 4-tetramethyl-1, 2,3, 4-cyclobutanetetracarboxylic dianhydride, 4,5,6, 7-bicyclo [2.2.1] heptanetetracarboxylic dianhydride, 2,3,5, 6-bicyclo [2.2.2] octanetetracarboxylic dianhydride, 2R,5R,7S, 10S-naphthalenetetracarboxylic dianhydride or 6H,12H-5, 11-methylenedibenzo [ b, f ] [1,5] diazacyclooctane-2, 3,8, 9-tetracarboxylic dianhydride, or a combination of at least two thereof;
preferably, the aromatic or aliphatic diamine B and the aromatic or aliphatic diamine D are each independently selected from the group consisting of 2, 6-diaminotoluene, 2, 5-dimethyl-1, 4-phenylenediamine, 4' -diamino-3, 3' -dimethylbiphenyl, 1' -binaphthyl-2, 2' -diamine, 1, 5-naphthalenediamine, 9' -spirobi [ 9H-fluorene ] -2,2' -diamine, 3' -dimethyl-9, 9' -spirobi [ 9H-fluorene ] -2,2' -diamine, 6-amino-2- (3-aminophenyl) benzimidazole, 9-di (4-amino-3-tolyl) fluorene or 9, 9-bis (4-aminophenyl) fluorene, 4,4' -diaminodiphenylethane, 4' - (cyclohexane-1, 4-dithiodiphenylamine), 1, 4-bis [ 2-amino-4- (trifluoromethyl) phenyl ] piperazine, 5' -isopropylidene bis (2-furfuryl amine), 2-bis (4-aminophenyl) norbornane, 3-bis (4-aminophenyl) quinuclidine, 1-bis (4-aminophenyl) -4-methylcyclohexane, 1-bis (4-aminophenyl) cyclohexane, 1,4:3, 6-dianhydro-2, 5-di-O- (4-aminophenyl) -D-mannitol or 1, 3-bis (4-aminophenoxymethylene) -1, one or a combination of at least two of 2, 2-trimethylcyclopentane;
preferably, the method of synthesis in step (1) or step (2) is: dissolving aromatic dianhydride A and aromatic or aliphatic diamine B, or alicyclic dianhydride C and aromatic or aliphatic diamine D in a high boiling point solvent, reacting for 6-24h at 0-70 ℃ under a protective atmosphere, then adding a water-carrying agent, and carrying out reflux reaction for 2-80h at 150-200 ℃ to obtain a diamine monomer I containing imide chain segments, or obtain a diamine monomer II containing imide chain segments;
preferably, the high boiling point solvent is selected from one or a combination of at least two of N-methyl pyrrolidone, N-dimethylformamide, N-dimethylacetamide, m-cresol or dimethyl sulfoxide;
preferably, the water-carrying agent is selected from one or a combination of at least two of toluene, xylene or chlorobenzene;
preferably, the method of synthesis in step (1) further comprises a purification step: after the reaction is finished, evaporating out the water-carrying agent, adding the reaction solution into a mixed solution of methanol and water, separating out a solid product, then dissolving again, pouring into methanol, separating out, filtering and drying;
preferably, the solvent used for re-dissolution is selected from one or a combination of at least two of N, N-dimethylformamide, N-dimethylacetamide, chloroform, dichloromethane or acetone.
7. The production method according to claim 5 or 6, wherein the acidic solvent in step (3) is selected from one or a combination of at least two of trifluoroacetic acid, polyphosphoric acid, or hydrochloric acid;
preferably, in the monomer mixed solution in the step (3), the total content of the diamine monomer I and the diamine monomer II is 1 to 25 wt%;
preferably, the origin agent in the step (3) is selected from one or a combination of at least two of formaldehyde, paraformaldehyde, hexamethylenetetramine or dimethoxymethane;
preferably, the ratio of the amount of the material of the prover to the total amount of the diamine monomer I and the diamine monomer II is 4-10: 1;
preferably, the reaction temperature in the step (3) is-20-50 ℃, and the reaction time is 2-144 h;
preferably, step (3) further comprises a purification step: after the reaction is finished, adding alkali liquor into the reaction solution to separate out a fibrous or powdery solid product, re-dissolving the obtained fibrous or powdery solid product, pouring the fibrous or powdery solid product into methanol, separating out, washing and drying;
preferably, the alkali liquor is ammonia water, sodium carbonate solution or sodium bicarbonate solution.
8. Use of a semi-aromatic polyimide according to any of claims 1 to 4 as a gas separation membrane material.
9. A gas separation membrane, characterized in that it is composed of a semi-aromatic polyimide according to any one of claims 1 to 4;
preferably, the gas separation membrane has a thickness of 5 to 150 μm.
10. Use of a gas separation membrane according to claim 9 for H2/CO2Separation, H2/CH4Separation, H2/N2Separation or O2/N2And (5) separating.
Technical Field
The invention belongs to the technical field of polyimide materials, and particularly relates to a semi-aromatic polyimide material, a preparation method and application thereof, and a gas separation membrane containing the semi-aromatic polyimide material.
Background
The membrane separation technology for gas mixtures is a technology for separating target gases from mixed gases by using the difference of the permeability and selectivity of a polymer membrane to different gas molecules. For example, oxygen and nitrogen are separated from air, and hydrogen is separated from cracked petroleum gas. Polyimide is an ideal raw material for gas separation membranes because of its high heat resistance, solvent resistance and good overall performance. However, conventional polyimide resins are difficult to dissolve, do not melt, have high processing difficulties, and have extremely low gas permeability, thus limiting the possibility of their wide industrial application.
The polyimide resins commercially used for gas separation membranes are only two of Matrimid 5218 and P84, wherein Matrimid 5218 is obtained by polymerizing 3,3',4,4' -benzophenonetetracarboxylic dianhydride (BTDA) with 5(6) -amino-1- (4-aminophenyl) -1,3, 3-trimethylindane (PIDA). P84 is prepared by copolycondensating three monomers, namely 3,3',4,4' -benzophenonetetracarboxylic dianhydride (BTDA), diphenylmethane diisocyanate (MDI) and Toluene Diisocyanate (TDI). The permeability coefficients of both of these commercial polyimide gas separation membranes are low, e.g., H2Has a permeability coefficient of less than 30Barrer, CO2The permeability coefficient of (a) is lower than 10Barrer (reference: J.Appl.Polym.Sci.2010,116, (5), 2906-.
Further, there is also a document disclosing a polyimide gas separation membrane. CN 109963641a discloses a polyimide separation membrane composed of a polyimide, a halogen compound soluble in the polyimide (e.g., halogenated aromatic epoxide), and a hydrocarbon having 2 to 5 carbons (e.g., ethane, ethylene, propane, or propylene), which has improved selectivity for small gas molecules such as hydrogen compared to a polyimide membrane that does not contain the halogen compound or hydrocarbon. CN108114615A adopts 2,2' -bis (3, 4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) as a dianhydride monomer and 2, 4-diaminobenzene sulfonate (MPDSAM) as a diamine monomer, and adopts a solution copolycondensation method to synthesize polyimide containing metal ions; CN103846023A adopts 2,2' -bis (3, 4-dicarboxyphenyl) hexafluoropropane dianhydride (6FDA) as a dianhydride monomer, and 2,4, 6-trimethyl-1, 3-phenylenediamine (TMPDA) and 2, 7-Diaminofluorene (DAF) as diamine monomers for copolymerization reaction to synthesize a polyimide material; CN 109833784A adopts silicon-containing diamine, aromatic diamine and aromatic dianhydride monomer in aprotic polarityPolymerizing in solvent to obtain the silicon-containing high molecular weight polyimide. But a gas separation membrane pair H prepared from the above polyimide2、CO2、CH4、N2、O2Low permeability and selectivity. Therefore, a gas separation membrane having a better separation performance for the above-mentioned gases has yet to be developed.
Disclosure of Invention
In view of the defects in the prior art, the invention aims to provide semi-aromatic polyimide, a preparation method and application thereof and a gas separation membrane comprising the semi-aromatic polyimide. The gas separation membrane prepared from the semi-aromatic polyimide provided by the invention has good dissolubility processability, mechanical property and heat-resistant stability, and is used for hydrogen separation (such as H)2/CO2、H2/CH4、H2/N2Separation) and air separation (i.e., O)2/N2Separation) has a high permeability coefficient and better selectivity.
In order to achieve the purpose, the invention adopts the following technical scheme:
in one aspect, the present invention provides a semi-aromatic polyimide having a structure represented by formula I below:
in the formula I, R1Is an aromatic dianhydride residue, R3Is a cycloaliphatic dianhydride residue, R2、R4Each independently an aromatic diamine residue or an aliphatic diamine residue;
x and y are each independently integers from 1 to 50, and m: n is 1:9 to 9: 1.
In the present invention, the aromatic dianhydride residue, alicyclic dianhydride residue, aromatic diamine residue, and aliphatic diamine residue refer to those remaining after removing an acid anhydride group or an amino group from an aromatic dianhydride, alicyclic dianhydride, aromatic diamine, or aliphatic diamine; m and n represent average polymerization degrees.
The semi-aromatic polyimide provided by the invention has diazacyclo ringThe polyimide film is of a twisted structure, and is beneficial to increasing the stacking distance between polyimide molecular chains, so that the gas permeability of the polyimide film is improved; the aromatic ring structure is matched with the alicyclic structure, which is favorable for reducing the ordered stacking degree of polyimide molecular chains, homogenizing the molecular chain spacing or micropore size and distribution in the polyimide film, and adjusting H2Selectivity of separation from other gases.
In the present invention, m: n is selected from 1:9 to 9:1, and may be, for example, 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, or 9: 1. When m is too large, the proportion of the alicyclic structure in the molecular chain is too low, and the regulation effect on the gas selectivity is not obvious; when m: n is too small, the proportion of the alicyclic structure in the molecular chain is too high and the proportion of the aromatic ring structure is too low, resulting in a semi-aromatic polyimide having low heat resistance.
In the present invention, x and y are each independently an integer of 1 to 50, and may be, for example, 1,2,3,4, 5,6,7,8, 9,10, 12, 15, 18, 20, 25, 30, 35, 40, 45, or 50.
In a preferred embodiment of the present invention, the molecular chain of the semi-aromatic polyimide contains a troger base (f: (a))Base, abbreviation TB)And (5) structure.
As a preferable technical scheme of the invention, the weight average molecular weight of the semi-aromatic polyimide is 5-100 ten thousand; for example, 5,6,7,8, 9,10, 12, 15, 18, 20, 22, 25, 28, 30, 32, 35, 38, 40, 45, 50, 60, 70, 80, 90, or 100 tens of thousands, etc. may be used. More preferably 5 to 50 ten thousand.
As a preferred embodiment of the present invention, in formula I, R1Any one selected from the following substituted or unsubstituted groups:
wherein the dotted line represents the position of the group attachment, and when the group contains a substituent as described above, the substituent is selected from methyl, methoxy, halogen, hydroxy, oxo, cyano, heteroaryl, heterocyclic, or amino. Preferably, in formula I, R3Any one selected from the following substituted or unsubstituted groups:
wherein the dotted line represents the position of the group attachment, and when the group contains a substituent as described above, the substituent is selected from any one of methyl, methoxy, halogen, hydroxy, cyano, heteroaryl, heterocycloalkyl, and amino.
As a preferred embodiment of the present invention, in formula I, R2、R4Each independently selected from any one of the following substituted or unsubstituted groups:
wherein the dotted line represents the position of the group attachment, and when the group contains a substituent as described above, the substituent is selected from any one of methyl, methoxy, halogen, hydroxy, cyano, heteroaryl, heterocycloalkyl, and amino.
Preferably, x and y are each independently an integer of 1 to 4.
In a second aspect, the invention provides a preparation method of the semi-aromatic polyimide, which comprises the following steps:
step (1): with aromatic dianhydrides AAnd aromatic or aliphatic diamines B H2N-R2-NH2Synthesizing a diamine monomer I containing imide chain links as a raw material
Step (2): with alicyclic dianhydrides CAnd aromatic or aliphatic diamines D H2N-R4-NH2Synthesizing a diamine monomer II containing imide chain links as a raw material
And (3): dissolving a diamine monomer I obtained in the step (1) and a diamine monomer II obtained in the step (2) in an acidic solvent, wherein the mass ratio of the diamine monomer I to the diamine monomer II is 1:9-9:1, preparing a monomer mixed solution, adding an initiator, and reacting under a protective atmosphere to obtain the semi-aromatic polyimide;
wherein, x, y, R1、R2、R3And R4Having the same limitations as the semi-aromatic polyimide of the first aspect.
As a preferred embodiment of the present invention, the aromatic dianhydride A is selected from pyromellitic dianhydride (PMDA), 4,4'- (hexafluoroisopropylidene) diphthalic anhydride (6FDA), 1,4,5, 8-naphthalene tetracarboxylic anhydride (NTCDA), 3,4,9, 10-perylene tetracarboxylic dianhydride (PTCDA), triptycene-2, 3,6, 7-tetracarboxylic dianhydride (TTD), 9' -spirobifluorene-2, 2',3,3' -tetracarboxylic dianhydride (BDFDA), 3,3',4,4' -Benzophenone Tetracarboxylic Dianhydride (BTDA), 3,3',4,4' -diphenyl ether tetracarboxylic dianhydride (ODPA), 3,3',4,4' -biphenyl tetracarboxylic dianhydride (BPDA), 9-bis (3, 4-dicarboxyphenyl) fluorene dianhydride (SBDA) or 4, one or a combination of at least two of 4' -dinaphthalene-1, 1',8,8' -tetracarboxylic dianhydride (BNTDA).
The structural formula of the aromatic dianhydride is as follows:
preferably, the alicyclic dianhydride C is selected from 1,2,4, 5-cyclohexanetetracarboxylic dianhydride (HPMDA), 5,6,7, 8-bicyclo [2.2.2] -2-heptenetetracarboxylic dianhydride (BTA), 1,2,3, 4-cyclobutanetetracarboxylic dianhydride (CBDA), 1,2,3, 4-cyclopentanetetracarboxylic dianhydride (CPDA), 1,2,3, 4-tetramethyl-1, 2,3, 4-cyclobutanetetracarboxylic dianhydride (TCTD), 4,5,6, 7-bicyclo [2.2.1] heptanetetracarboxylic dianhydride (BHDA), 2,3,5, 6-bicyclo [2.2.2] octanetetracarboxylic dianhydride (BODA), 2R,5R,7S, 10S-naphthalenetetracarboxylic dianhydride (HNTDA) or 6H,12H-5, 11-methylenedibenzo [ b, f ] [1,5] diazacyclocin-2, one or a combination of at least two of 3,8, 9-tetracarboxylic dianhydride (TB-DA).
The structural formula of the alicyclic dianhydride is as follows:
preferably, the aromatic or aliphatic diamine B and the aromatic or aliphatic diamine D are each independently selected from 2, 6-Diaminotoluene (DAP), 2, 5-dimethyl-1, 4-phenylenediamine (DPD), 4' -diamino-3, 3' -dimethylbiphenyl (o-Tolidine), 1' -binaphthyl-2, 2' -diamine (AMMA), 1, 5-Naphthalenediamine (NPD), 9' -spirobi [ 9H-fluorene ] -2,2' -diamine (SBF), 3' -dimethyl-9, 9' -spirobi [ 9H-fluorene ] -2,2' -diamine (CSBF), 6-amino-2- (3-aminophenyl) Benzimidazole (BIA), 9-di (4-amino-3-tolyl) fluorene or 9, 9-bis (4-aminophenyl) fluorene (BAMF), 4' -diaminodiphenylethane (DDE), 4' - (cyclohexane-1, 4-dithiodiphenylamine) (SCHDA), 1, 4-bis [ 2-amino-4- (trifluoromethyl) phenyl ] piperazine (AFMT), 5' -isopropylidene bis (2-furfuryl amine) (DAF), 2-bis (4-aminophenyl) norbornane (BANB), 3-bis (4-Aminophenyl) Quinuclidine (AQ), 1-bis (4-aminophenyl) -4-methylcyclohexane (BAME), 1-bis (4-aminophenyl) cyclohexane (BACH), 1,4:3, 6-dianhydro-2, 5-di-O- (4-aminophenyl) -D-mannitol (DA-IM) Or 1, 3-bis (4-aminophenoxymethylene) -1,2, 2-trimethylcyclopentane (BAMT).
The structural formula of the above aromatic or aliphatic diamine is as follows:
preferably, the method of synthesis in step (1) or step (2) is: dissolving aromatic dianhydride A and aromatic or aliphatic diamine B, or alicyclic dianhydride C and aromatic or aliphatic diamine D in high boiling point solvent, reacting at 0-70 deg.C (such as 0 deg.C, 5 deg.C, 10 deg.C, 15 deg.C, 20 deg.C, 25 deg.C, 30 deg.C, 35 deg.C, 40 deg.C, 45 deg.C, 50 deg.C, 60 deg.C, 65 deg.C or 70 deg.C) for 6-24h (such as 6h, 7h, 8h, 9h, 10h, 12h, 15h, 18h, 20h, 21h or 24 h), adding water-carrying agent, and reflux-reacting at 150-200 deg.C (such as 150 deg.C, 155 deg.C, 160 deg.C, 170 deg.C, 175 deg.C, 180 deg.C, 185 deg.C, 190 deg.C, 195 deg.C) for 2-80h (such as 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 15h, 20h, 25h, 30h, 35h, 40h, 45h, 50h, 55h, 60h, 65h, 70h, 75h, 80h, etc.) to obtain the imide linkage-containing diamine monomer I, or to obtain the imide linkage-containing diamine monomer II.
The high boiling point solvent in the present invention refers to a solvent with a boiling point of 150-220 ℃, and is preferably selected from one or a combination of at least two of N-methylpyrrolidone (NMP), N-Dimethylformamide (DMF), N-dimethylacetamide (DMAc), m-cresol or dimethyl sulfoxide (DMSO).
Preferably, the water-carrying agent is selected from one or a combination of at least two of toluene, xylene or chlorobenzene.
Preferably, the method of synthesis in step (1) further comprises a purification step: after the reaction is finished, evaporating the water-carrying agent, adding the reaction solution into a mixed solution of methanol and water, precipitating a solid product, then re-dissolving, pouring into methanol, precipitating, filtering and drying.
Preferably, the solvent used for re-dissolution is selected from one or a combination of at least two of N, N-dimethylformamide, N-dimethylacetamide, chloroform, dichloromethane or acetone.
In a preferred embodiment of the present invention, the acidic solvent in step (3) is one or a combination of at least two selected from trifluoroacetic acid (TFA), polyphosphoric acid, and hydrochloric acid.
Preferably, in the monomer mixed solution in the step (3), the total content of the diamine monomer I and the diamine monomer II is 1 to 25 wt%; for example, it may be 1 wt%, 2 wt%, 3 wt%, 5 wt%, 6 wt%, 8 wt%, 10 wt%, 12 wt%, 15 wt%, 18 wt%, 20 wt%, 22 wt%, 25 wt%, or the like.
Preferably, the origin agent in step (3) is selected from one or a combination of at least two of formaldehyde, paraformaldehyde, Hexamethylenetetramine (HMTA) or Dimethoxymethane (DMM).
Preferably, the ratio of the amount of the material of the prover to the total amount of the diamine monomer I and the diamine monomer II is 4-10: 1; for example, it may be 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, 7:1, 7.5:1, 8:1, 8.5:1, 9:1, 9.5:1, or 10: 1.
Preferably, the reaction temperature in step (3) is-20 to 50 ℃, for example, -20 ℃, -10 ℃, -5 ℃, -2 ℃, 0 ℃,2 ℃,5 ℃,8 ℃,10 ℃,12 ℃, 15 ℃, 18 ℃, 20 ℃, 22 ℃, 25 ℃, 28 ℃, 30 ℃,32 ℃, 35 ℃, 38 ℃, 40 ℃, 45 ℃ or 50 ℃ and the like; the time is 2 to 144 hours, and may be, for example, 2 hours, 3 hours, 4 hours, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours, 10 hours, 15 hours, 20 hours, 25 hours, 30 hours, 40 hours, 50 hours, 60 hours, 70 hours, 80 hours, 100 hours, 120 hours, 130 hours, 140 hours, or 144 hours.
Preferably, step (3) further comprises a purification step: after the reaction is finished, adding alkali liquor into the reaction liquid to separate out a fibrous or powdery solid product, redissolving the obtained fibrous or powdery solid product, pouring the redissolved product into methanol, separating out, washing and drying.
Preferably, the alkali liquor is ammonia water, sodium carbonate solution or sodium bicarbonate solution.
In a third aspect, the present invention provides a use of the semi-aromatic polyimide of the first aspect as a material for a gas separation membrane.
In a fourth aspect, the present invention provides a gas separation membrane comprising the semi-aromatic polyimide according to the first aspect.
The method for producing the gas separation membrane of the present invention is not particularly limited, and, for example, the following methods may be employed:
dissolving the semi-aromatic polyimide provided in the first aspect in a solvent to prepare a polymer solution with a solid content of 1-20 wt%, coating the polymer solution on a substrate, sequentially drying the polymer solution in a vacuum oven at normal temperature for 2-48 hours, at 60 ℃ for 1-5 hours, at 90 ℃ for 1-5 hours and at 120 ℃ for 1-5 hours, and peeling off the film after drying to obtain the gas separation membrane;
wherein the solvent for dissolving the semi-aromatic polyimide is selected from N-methylpyrrolidone (NMP), N-Dimethylformamide (DMF), N-dimethylacetamide (DMAc), and chloroform (CHCl)3) Or dichloromethane (CH)2Cl2) Or a combination of at least two thereof.
Preferably, the thickness of the gas separation membrane is 5 to 150. mu.m, and may be, for example, 5. mu.m, 8. mu.m, 10. mu.m, 15. mu.m, 20. mu.m, 25. mu.m, 30. mu.m, 35. mu.m, 40. mu.m, 45. mu.m, 50. mu.m, 60. mu.m, 70. mu.m, 80. mu.m, 90. mu.m, 100. mu.m, 110. mu.m, 120. mu.m, 130. mu.m, 140. mu.m, 150. mu.m, or the like.
In a fifth aspect, the present invention provides a use of the gas separation membrane of the fourth aspect for H2/CO2Separation, H2/CH4Separation, H2/N2Separation or O2/N2And (5) separating.
Compared with the prior art, the invention has the following beneficial effects:
the semi-aromatic polyimide obtained by the invention has good dissolubility processability, mechanical property and heat-resistant stability by designing the molecular chain structure of the polyimide, the glass transition temperature of the semi-aromatic polyimide reaches over 380 ℃, the tensile strength reaches 70-150MPa, and the elastic modulus reaches 1.00-2.5 GPa; the gas separation membrane prepared from the semi-aromatic polyimide has high permeability coefficient to H2/CH4、H2/N2And O2/N2The separation performance of the gas pair exceeds the upper limit of Robeson 2008, and the method can be used for separating pure hydrogenChemical and air separation.
Detailed Description
The technical solution of the present invention is further illustrated by the following specific examples. It should be understood by those skilled in the art that the examples are only for the understanding of the present invention and should not be construed as the specific limitations of the present invention.
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