Polybenzimidazole, preparation method therefor, and use thereof

Abstract

A polybenzimidazole polymer has excellent gas adsorption and separation properties, and also has a mechanochromic characteristic. The polybenzimidazole polymer can be used for adsorption and separation of a carbon dioxide-containing gas.

Description

Polybenzimidazole, preparation method and application thereof Technical Field

[0001] The present invention relates to the field of polymer materials, and more particularly to polybenzimidazole containing tetraphenylethylene groups, a method for separating gases by adsorption using the polybenzimidazole, and use of the polybenzimidazole for gas adsorption separation. Background Art

[0002] Polybenzimidazole (PBI) refers to a class of heterocyclic polymers containing imidazole rings in the repeating units, which has excellent thermal stability, mechanical stability and chemical stability.

[0003] Due to their excellent processing properties, polymers are often processed into membrane products such as nanofiltration membranes and hollow fiber membranes for gas separation and purification. Despite their excellent separation performance, polymer membrane products typically lack adsorption properties. The present invention provides novel polybenzimidazole polymers that exhibit excellent gas adsorption properties and varying adsorption selectivity for different gases.

[0004] Summary of the Invention

[0005] The purpose of the present invention is to provide a novel polybenzimidazole polymer having gas adsorption and separation properties. In addition, the polybenzimidazole polymer of the present application has mechanochromic properties.

[0006] The first aspect of the present invention provides a polybenzimidazole, wherein the polybenzimidazole comprises a structural unit A, wherein the structural unit A has a structure shown in formula (1);

[0007] Wherein, the X1 group is a connecting group provided by an aromatic hydrocarbon compound containing 1 to 10 benzene rings; and the Y group is a connecting group based on tetraphenylethylene; wherein, the X1 group and the Y group independently have or do not have at least one substituent selected from hydroxyl, amino, cyano, halogen, C1-C4 alkyl, and C1-C4 haloalkyl.

[0008] In some embodiments, the polybenzimidazole contains structural unit A and structural unit C, contains structural unit A and structural unit D, or contains structural unit A, structural unit B, structural unit C and structural unit D;

[0009] wherein the structural unit A has a structure represented by formula (1), the structural unit B has a structure represented by formula (2), the structural unit C has a structure represented by formula (1-1), and the structural unit D has a structure represented by formula (2-2):

[0010] wherein the X1 and X2 groups are each independently a linking group provided by an aromatic compound containing 1-10 benzene rings; the Y group is a linking group based on tetraphenylethylene; and the Z group is an aromatic hydrocarbon containing 1-10 benzene rings, a heteroaromatic hydrocarbon containing 1-10 heterocycles, an aromatic hydrocarbon containing 1-3 heterocycles and 1-8 benzene rings, a C4-C 10 A connecting group provided by at least one compound selected from cycloalkanes, C1-C8 alkanes, and C2-C8 olefins; wherein the X1, X2, Y, and Z groups independently contain or do not contain at least one substituent selected from hydroxyl, amino, cyano, halogen, C1-C4 alkyl, and C1-C4 haloalkyl.

[0011] In some embodiments, the polybenzimidazole comprises a structural unit A and an optional structural unit B, wherein the structural unit A has a structure represented by formula (1) and the structural unit B has a structure represented by formula (2);

[0012] wherein the X1 and X2 groups are each independently a linking group provided by an aromatic compound containing 1-10 benzene rings; the Y group is a linking group based on tetraphenylethylene; and the Z group is an aromatic hydrocarbon containing 1-10 benzene rings, a heteroaromatic hydrocarbon containing 1-10 heterocycles, an aromatic hydrocarbon containing 1-3 heterocycles and 1-8 benzene rings, a C4-C 10 The connecting group is provided by at least one compound selected from cycloalkanes, C1-C8 alkanes, and C2-C8 olefins, and when the structural unit B is present, Z and Y are different; wherein, the X1, X2, Y groups and Z groups each independently have or do not have at least one substituent selected from hydroxyl, amino, cyano, halogen, C1-C4 alkyl, and C1-C4 haloalkyl.

[0013] The present invention also provides a method for preparing the polybenzimidazole of the present invention, which comprises reacting at least one compound having a structure represented by formula (6) with HOOC-Y-COOH and optionally HOOC-Z-COOH;

[0014] wherein the X group in formula (6) is the same as the X1 and / or X2 groups defined in the first aspect, and the Y and Z groups in HOOC-Y-COOH and the optional HOOC-Z-COOH are each the same as the Y and Z groups defined in the first aspect.

[0015] The present invention also provides a method for separating CO2 gas by adsorption, wherein the polybenzimidazole of the present invention is used as an adsorbent.

[0016] The present invention also provides use of the polybenzimidazole of the present invention as an adsorbent for gas adsorption separation. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG1 is a hydrogen nuclear magnetic spectrum of the polymer of Example 1 (PBI-1) and the polymer of Example 2 (PBI-2).

[0018] FIG2 is a graph showing the probability distribution function of the free volume of PBI-4.

[0019] Figure 3 is the fluorescence spectra of PBI-2 before and after grinding.

[0020] FIG4 is a physical picture of a polybenzimidazole polymer not according to the present invention (left) and the polymer of Example 4 (PBI-4, right). DETAILED DESCRIPTION

[0021] The first aspect of the present invention provides a polybenzimidazole, wherein the polybenzimidazole comprises a structural unit A, wherein the structural unit A has a structure shown in formula (1);

[0022] wherein the X1 group is a linking group provided by an aromatic compound containing 1-10 benzene rings; and the Y group is a linking group based on tetraphenylethylene; wherein the X1 group and the Y group are each independently present or absent at least one substituent selected from the group consisting of hydroxyl, amino, cyano, halogen, C1-C4 alkyl, and C1-C4 haloalkyl. In some embodiments, the polybenzimidazole is composed of structural unit A.

[0023] In some embodiments, the polybenzimidazole contains structural unit A and structural unit C, contains structural unit A and structural unit D, or contains structural unit A, structural unit B, structural unit C and structural unit D;

[0024] wherein the structural unit A has a structure represented by formula (1), the structural unit B has a structure represented by formula (2), the structural unit C has a structure represented by formula (1-1), and the structural unit D has a structure represented by formula (2-2):

[0025] wherein the X1 and X2 groups are each independently a linking group provided by an aromatic compound containing 1-10 benzene rings; the Y group is a linking group based on tetraphenylethylene; and the Z group is an aromatic hydrocarbon containing 1-10 benzene rings, a heteroaromatic hydrocarbon containing 1-10 heterocycles, an aromatic hydrocarbon containing 1-3 heterocycles and 1-8 benzene rings, a C4-C 10A linking group is provided by at least one compound selected from the group consisting of a cycloalkane, a C1-C8 alkane, or a C2-C8 alkene; wherein each of the X1, X2, Y, and Z groups independently contains or does not contain at least one substituent selected from the group consisting of hydroxyl, amino, cyano, halogen, C1-C4 alkyl, and C1-C4 haloalkyl. In some embodiments, the polybenzimidazole is composed of structural units A and C. In some embodiments, the polybenzimidazole is composed of structural units A and D. In some embodiments, the polybenzimidazole is composed of structural units A, B, C, and D.

[0026] In some embodiments, the polybenzimidazole comprises a structural unit A and an optional structural unit B, wherein the structural unit A has a structure shown in formula (1) and the structural unit B has a structure shown in formula (2);

[0027] Wherein, the X1 and X2 groups are each independently a linking group provided by an aromatic compound containing 1-10 benzene rings; the Y group is a linking group based on tetraphenylethylene; the Z group is an aromatic hydrocarbon containing 1-10 benzene rings, a heteroaromatic hydrocarbon containing 1-10 heterocyclic rings, an aromatic hydrocarbon containing 1-3 heterocyclic rings and 1-8 benzene rings, a C4-C 10 The connecting group is provided by at least one of cycloalkane, C1-C8 alkane and C2-C8 alkene, and Z is different from Y when the structural unit B is present; wherein the X1, X2, Y group and Z group are each independently present or absent at least one substituent selected from hydroxyl, amino, cyano, halogen, C1-C4 alkyl and C1-C4 haloalkyl.

[0028] In the present invention, those skilled in the art will be able to know the connection mode of X1 and X2 groups in formula (1) and formula (2). For example, when X1 and X2 groups are each independently a connecting group provided by benzene, the structural formulas of formula (1) and formula (2) can be respectively That is, the benzene ring and the imidazole ring share two pairs of carbon atoms.

[0029] In the present invention, C4-C 10 The cycloalkane may be, for example, cyclobutane, cyclopentane, cyclohexane, cycloheptane, cyclooctane, cyclononane or cyclodecane.

[0030] In the present invention, C1-C8 alkane can be, for example, methane, ethane, n-propane, isopropane, butane, pentane, hexane, heptane, or octane. In some embodiments, the C1-C8 alkane can be a C1-C8 alkane substituted with one or more halogen atoms, wherein the halogen atoms can be selected from fluorine atoms, chlorine atoms, and bromine atoms.

[0031] In the present invention, the C2-C8 olefin may be, for example, ethylene, propylene, butene, pentene, hexene, heptene, or octene.

[0032] In the present invention, the halogen can be selected from, for example, fluorine, chlorine and bromine.

[0033] In the present invention, the C1-C4 alkyl group may be, for example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a sec-butyl group, an isobutyl group, or a tert-butyl group.

[0034] In the present invention, the C1-C4 haloalkyl group may be, for example, a halomethyl group, a haloethyl group, a halopropyl group, a haloisopropyl group, a halobutyl group, a halosec-butyl group, a haloisobutyl group, or a halotert-butyl group; and the halogen atom in the C1-C4 haloalkyl group may be, for example, a fluorine atom, a chlorine atom, or a bromine atom.

[0035] According to the present invention, preferably, in some embodiments, the X1 and X2 groups are each independently a linking group provided by at least one compound selected from benzene, biphenyl, terphenyl, bridged phenyl, pterygene, and a condensed aromatic hydrocarbon containing 1 to 10 benzene rings; preferably, the X1 and X2 groups are each independently a linking group provided by at least one compound selected from benzene, biphenyl, bridged phenyl, pterygene, and naphthalene; more preferably, the bridged phenyl has a structure shown in formula (3), formula (4), or formula (5), wherein R1, R3, and R4 are each independently selected from one of an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, a methylene group, and a halogen-substituted methylene group; and R2 is selected from a heteroaromatic ring;

[0036] In the present invention, the heteroaromatic ring may be, for example, pyridine or pyrimidine.

[0037] In the present invention, the connection positions (indicated by "dashed lines") of the structures represented by formula (3), formula (4) and formula (5) can be as follows:

[0038] In the present invention, the connection positions include but are not limited to the above-mentioned representations; for example, any two adjacent connection positions on the same benzene ring are feasible.

[0039] According to the present invention, preferably, the X1 and X2 groups are each independently selected from the following linking groups:

[0040] wherein G is selected from a hydrogen atom, a methyl group, and a trifluoromethoxy group; J is selected from an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, a methylene group, and a methylene group substituted with a methyl group or a trifluoromethyl group; L is selected from a bromine atom, a phenyl group, and a phenyl group substituted with a trifluoromethyl group; and R is selected from a hydrogen atom, a carboxyl group, a hydroxyl group, and a trifluoromethyl group.

[0041] In some embodiments of the present invention, the connection positions of the X1 and X2 groups may include but are not limited to the following connection positions:

[0042] According to the present invention, in some embodiments, the molar content ratio of the X2 and X1 groups can be 0-9999, preferably 0-99; for example, it can be 0, 0.001, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 99, 100, and ranges consisting of any two of the above points. In the present invention, unless otherwise specified, the content ratio of the X2 and X1 structural units or groups in the polybenzimidazole is calculated based on the feed amount.

[0043] According to the present invention, preferably, the Y group is derived from at least one of the following compounds:

[0044] According to the present invention, preferably, in some embodiments, the Z group is benzene, a 5-6 membered nitrogen-containing heterocyclic compound, an aromatic compound containing 2-7 benzene rings, an aromatic compound containing 1-2 nitrogen-containing heterocyclic rings and 1-4 benzene rings, a C4-C 10 The linking group is provided by a compound of at least one of cycloalkanes, C1-C8 alkanes, and C2-C8 alkenes.

[0045] According to the present invention, preferably, the Z group is a linking group selected from the following:

[0046] C1-C8 chain alkyl;

[0047] wherein M is selected from a hydrogen atom, a cyano group, a methyl group, a phenyl group, and a phenyl group substituted with a methyl group or a trifluoromethyl group; P is selected from an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, a cyclobutyl group, a cyclobutyl group substituted with a halogen group, a methylene group, and a methylene group substituted with a methyl group or a trifluoromethyl group; Q is selected from a bromine atom, a phenyl group, and a phenyl group substituted with a trifluoromethyl group; and T is selected from a hydrogen atom and a methyl group.

[0048] In the present invention, the attachment position of the Z group is not particularly limited and can be any position on the linking group. For example, when the Z group contains a cyclic structure, the attachment position can be a carbon atom on the cyclic structure; when the Z group is a C1-C8 alkyl group, the attachment position can be any carbon atom in the alkyl group. In the present invention, the attachment position of the Z group can include, but is not limited to, the following attachment positions:

[0049] According to the present invention, the molar content ratio of the Z and Y groups can be 0-9999, more preferably 0-99; for example, it can be 0, 0.001, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 99, 100, and ranges consisting of any two of the above points. In the present invention, unless otherwise specified, the content ratio of the Z and Y structural units or groups in the polybenzimidazole is calculated based on the feed amount.

[0050] In the present invention, the free volume of the polybenzimidazole can be Preferably And the pore size of the polybenzimidazole can be Preferably 2.6-

[0051] In the present invention, the intrinsic viscosity of the polybenzimidazole can be 0.45-3.0 dL g -1 ; For example, it can be 0.45dL g -1 、0.5dL g -1 、0.6dL g -1 、0.7dL g -1 、0.8dL g -1 、0.9dL g -1 、1dL g -1 、1.1dL g -1 、1.2dL g -1 、1.3dL g -1 、1.4dL g -1 、1.5dL g -1 、1.6dL g -1 、1.7dL g -1 、1.8dL g -1 、1.9dL g -1 , 2.0dL g -1 、2.1dL g -1 、2.2dL g -1 、2.3dL g -1 、2.4dL g -1 、2.5dL g -1 、2.6dL g -1 、2.7dL g -1 、2.8dL g -1 、2.9dL g -1 、3.0dL g -1 , and the range consisting of any two of the above points.

[0052] The preparation of polybenzimidazole is known in the art. Various preparation methods known in the art can be used to prepare the polybenzimidazole of the present invention.

[0053] In another aspect, the present invention also provides a method for preparing the polybenzimidazole described in the first aspect, the method comprising reacting at least one compound having a structure represented by formula (6) with HOOC-Y-COOH and optionally HOOC-Z-COOH;

[0054] Wherein, the X group in formula (6) is the same as the X1 and / or X2 group in the above formula (1) and formula (2), and the Y and Z groups in HOOC-Y-COOH and the optional HOOC-Z-COOH are respectively the same as the Y and Z groups defined in the above formula (1) and formula (2), and are not repeated here.

[0055] According to the preparation method of the present invention, preferably, in some embodiments, the compound having the structure shown in formula (6) is selected from at least one of the following compounds:

[0056] Wherein, G is selected from hydrogen atom, methyl and trifluoromethoxy, i.e. -H, -CH3, -OCF3;

[0057] J is selected from oxygen atoms, sulfur atoms, carbonyl groups, sulfonyl groups, methylene groups and methylene groups substituted with methyl or trifluoromethyl groups, for example, -O-, -S-,

[0058] L is selected from bromine atoms, phenyl groups and trifluoromethyl-substituted phenyl groups, for example, -Br, as well as

[0059] R is selected from hydrogen, carboxyl, hydroxyl and trifluoromethyl, i.e., -H, -COOH, -OH, -CF3.

[0060] According to the preparation method of the present invention, preferably, in some embodiments, the reaction is carried out in a solvent, more preferably, the solvent is a mixed solution of methanesulfonic acid / phosphorus pentoxide or polyphosphoric acid, further preferably a mixed solution of methanesulfonic acid / phosphorus pentoxide, wherein the mass of phosphorus pentoxide is 2-10% of the mass of methanesulfonic acid. The concentration of the mixed monomers in the reaction system may be 3 wt% to 20 wt%.

[0061] According to the preparation method of the present invention, preferably, in some embodiments, the ratio of the molar amount of the compound having the structure represented by formula (6) to the total molar amount of HOOC-Y-COOH and optional HOOC-Z-COOH is 1:0.6-2, preferably 1:0.8-1.2.

[0062] According to the preparation method of the present invention, preferably, in some embodiments, the reaction time can be 1-9 hours, preferably 3-5 hours. The reaction temperature can be 60-230° C., preferably 60-170° C., more preferably 100-150° C. The reaction pressure can be normal pressure.

[0063] According to the preparation method of the present invention, preferably, HOOC-Y-COOH is selected from at least one of the following compounds:

[0064] According to the preparation method of the present invention, preferably, in some embodiments, HOOC-Z-COOH is selected from at least one of the following compounds:

[0065] Wherein, n is 1-8; M, P, Q, and T each refer to a substituent, which is the same as described in the first aspect and will not be repeated here.

[0066] According to the preparation method of the present invention, preferably, in some embodiments, the ratio of the molar amount of the compound having the structure represented by formula (6) to the total molar amount of HOOC-Y-COOH and optional HOOC-Z-COOH is 1:0.6-2; for example, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, and the range consisting of any two of the above points; preferably 1:0.8-1.2; The molar ratio of the X2 to X1 groups can be 0-9999, preferably 0-99, for example, 0, 0.001, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 99, 100, and ranges consisting of any two of the above; The molar ratio of the Z to Y groups can be 0-9999, preferably 0-99, for example, 0, 0.001, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 99, 100, and ranges consisting of any two of the above.

[0067] In some embodiments, the polybenzimidazole of the present invention may have one of the following structures:

[0068] In the above structures, for copolymers, the structure indicates only that the polymer segments contain or consist of the indicated repeating units and does not indicate the distribution of the indicated repeating units within the polymer chain. The present invention also provides applications of the aforementioned polybenzimidazole polymers for gas adsorption separation.

[0069] In one aspect, the present invention provides a method for separating CO2 gas by adsorption, wherein the polybenzimidazole described in the first aspect of the present invention is used as an adsorbent.

[0070] It was unexpectedly found in the present invention that the polybenzimidazole of the present invention has a high adsorption capacity for CO2 and a low adsorption capacity for N2 and O2, thereby providing a high carbon dioxide / nitrogen separation coefficient and a high carbon dioxide / oxygen separation coefficient, so that it can be used to separate CO2 from a gas selected from N2, O2 or a mixture thereof.

[0071] The present invention is not limited to the specific separation operation, but generally includes contacting the polybenzimidazole of the present invention with a gas mixture containing CO2. When the polybenzimidazole of the present invention has adsorbed a sufficient amount of CO2, the polybenzimidazole can be removed and regenerated by desorption. The regenerated polybenzimidazole can be contacted with a gas mixture containing CO2 again to adsorb CO2.

[0072] The present invention also provides the use of the polybenzimidazole described in the first aspect of the present invention as an adsorbent for gas adsorption separation. Because the polybenzimidazole of the present invention has a high adsorption capacity for CO2 and a low adsorption capacity for N2 and O2, the polybenzimidazole of the present invention can be used as an adsorbent to separate CO2 from a gas selected from N2, O2, or a mixture thereof.

[0073] The present invention provides a polybenzimidazole polymer having beneficial gas adsorption separation properties and excellent thermal stability, so that the polybenzimidazole polymer can be used in some gas adsorption separation applications under high temperature conditions.

[0074] Furthermore, the polybenzimidazole polymers of the present invention exhibit mechanochromic properties. Mechanochromic materials are materials whose color, luminescence, and other properties change when subjected to external stimuli, such as abrasion, stretching, and compression. The polybenzimidazole polymers of the present invention exhibit a significant shift in their fluorescence emission peak under external stimuli, making them mechanochromic.

[0075] In some embodiments, the polybenzimidazole of the present invention can be used to monitor the flow of carbon dioxide-containing gases. For example, the polybenzimidazole of the present invention can be coated on the inner surface of a microchannel and placed at the end of the gas path where the carbon dioxide flow or emission needs to be monitored. When a slight carbon dioxide leak occurs, the polybenzimidazole absorbs the carbon dioxide through its adsorption properties. When the carbon dioxide leak increases, the impact of the flow stresses the material, causing a change in the peak fluorescence emission signal, which is detected by the detector and triggers an alarm.

[0076] Polybenzimidazole without tetraphenylethylene groups is generally reddish brown, while polybenzimidazole containing tetraphenylethylene groups is generally yellow. The introduction of tetraphenylethylene groups increases the diversity of polybenzimidazole chromaticity and can expand the application scenarios of polybenzimidazole. Figure 4 shows a physical picture of a polybenzimidazole polymer not of the present invention (left side; prepared by a method similar to the embodiment of the present application using 3,3′,4,4′-tetraaminobiphenyl and 4,4′-diphenyl ether dicarboxylic acid with a molar ratio of 1:1.05) and the polymer of Example 4 (PBI-4, right side).

[0077] To make the present invention easier to understand, the present invention will be described in detail below with reference to the following examples. These examples are merely illustrative and do not limit the scope of application of the present invention. It should be noted that reasonable modifications made by those skilled in the art inspired by this patent fall within the scope of protection of this patent.

[0078] In the following examples,

[0079] The yield of the polymerization product was calculated according to the following formula:

[0080] Yield = actual polymer yield ÷ theoretical polymer yield × 100%;

[0081] The theoretical yield of the polymer = the number of moles of the compound represented by formula (6) × the molar mass of the repeating units in the polymer structure.

[0082] 3,3′,4,4′-Tetraaminobiphenyl: Sigma-Aldrich; purity: 98%;

[0083] 4,4′-Diphenylether dicarboxylic acid: J&K Technology; purity 98%;

[0084] 4,4'-(2,2-diphenylethylene-1,1-diyl)dibenzoic acid: Anaiji Chemical, purity 98%;

[0085] 4,4'-(1,2-Diphenylethylene-1,2-diyl)dibenzoic acid: Anaiji Chemical, purity is 91%.

[0086] Example 1

[0087] A mixture of 3,3',4,4'-tetraaminobiphenyl (2.14 g), 4,4'-diphenylether dicarboxylic acid (1.9 g), and 4,4'-(2,2-diphenylethylene-1,1-diyl)dibenzoic acid (1.32 g) in a molar ratio of 1:0.735:0.315 was added to a methanesulfonic acid / phosphorus pentoxide solution (62 g solvent) to form a reaction system. The reaction was carried out at 140°C for 5 hours to obtain a reaction solution. The reaction solution was then introduced into water to precipitate the polymer, which was then neutralized (with sodium bicarbonate) and filtered to obtain the polymer product PBI-1. The weight ratio of methanesulfonic acid to phosphorus pentoxide in the methanesulfonic acid / phosphorus pentoxide solution was 12:1, and the concentration of the mixed monomers in the reaction system was 8 wt%. The yield of the polymer was 99%. The H NMR spectrum of PBI-1 was measured in Test Example 6 and is shown in Figure 1. Its structure was confirmed by H NMR spectrum.

[0088] Example 2

[0089] The method of Example 1 was followed, except that 4,4'-(2,2-diphenylethylene-1,1-diyl)dibenzoic acid was replaced with an equal molar amount of 4,4'-(1,2-diphenylethylene-1,2-diyl)dibenzoic acid. The yield of polymer PBI-2 was 99%. The H-NMR spectrum of PBI-2 was measured in Test Example 6 and is shown in Figure 1. Its structure was confirmed by H-NMR spectrum.

[0090] Example 3

[0091] The reaction was carried out according to the method of Example 1, except that 4,4'-diphenylether dicarboxylic acid was replaced with an equal molar amount of 4,4'-(2,2-diphenylethylene-1,1-diyl)dibenzoic acid. The reaction time was 3 h. The yield of polymer PBI-3 was 99%. Its structure was confirmed by H NMR spectroscopy.

[0092] Example 4

[0093] The reaction was carried out according to the method of Example 1, except that 4,4'-diphenylether dicarboxylic acid was replaced with an equal molar amount of 4,4'-(1,2-diphenylethylene-1,2-diyl)dibenzoic acid. The reaction time was 3 h. The yield of polymer PBI-4 was 99%. Its structure was confirmed by H NMR spectroscopy.

[0094] Test Example 1

[0095] The thermal stability of the polymers prepared in the above examples was tested.

[0096] Test method: The test was conducted using a TA Q500 thermogravimetric analyzer from the United States in a nitrogen atmosphere. The heating rate was 10°C / min and the temperature range was 25-700°C.

[0097] Thermal decomposition temperature of polymer T d5％ (Temperature at 5% mass loss) is shown in Table 1.

[0098] Table 1

[0099] Test Example 2

[0100] The free volume and pore size were determined using positron annihilation lifetime spectroscopy.

[0101] Test method: DPLS3000 is used to test the positron annihilation lifetime spectrum in an atmospheric environment at room temperature and pressure. The activity used is approximately 2E +6A 22Na positron source (Bq) was sandwiched between the sample to form a sandwich structure. A total of 1.5 million counts were measured to obtain the positron annihilation lifetime spectrum of the sample. The system had a time resolution of 190 ps, ​​a channel width of 20 ps, ​​and 4096 channels. The measured positron annihilation lifetime spectrum was interpreted using the Melt 4.0 program to obtain the positron annihilation lifetime and intensity, and to determine the polymer free volume and pore size.

[0102] The test results of polymer free volume and pore size are shown in Table 2.

[0103] Table 2

[0104] Test Example 3

[0105] The isothermal adsorption properties of polybenzimidazole for gases were tested.

[0106] Testing Method: Micromeritics ASAP2020 was used for testing. Samples were placed in sample tubes and placed in a degassing station for high-temperature vacuum degassing. The degassed samples were weighed and placed in an analysis station. The adsorption and desorption isotherms of N2, O2, and CO2 were measured at room temperature. The pressure range for the adsorption isotherm was 10 mmHg to 800 mmHg, and the pressure range for the desorption isotherm was 800 mmHg to 60 mmHg.

[0107] The test results are shown in Table 3.

[0108] Table 3

[0109] Test Example 4

[0110] The polymers prepared in Examples 1-4 above were tested for their mechanochromic properties.

[0111] Testing method: Polymer powder is placed in a solid fixture (two transparent quartz plates, one of which has a sample placement recess) and placed in a fluorimeter (Edinburgh Steady-State / Transient Fluorescence Spectrometer FLS1000) to measure the resulting fluorescence emission spectrum. The polymer powder is then manually ground in a mortar for 30 seconds, placed in the solid fixture, and again placed in the fluorimeter to measure the fluorescence emission spectrum.

[0112] The peak shifts of the strongest fluorescence emission before and after polymer grinding are shown in Table 4.

[0113] Table 4

[0114] Note: “#” indicates the emission peak is blue-shifted; “*” indicates the emission peak is red-shifted.

[0115] Test Example 5

[0116] The intrinsic viscosities of the polymers prepared in Examples 1-4 above were tested.

[0117] Test method: Dissolve PBI in concentrated sulfuric acid to a concentration of 0.6 g dL -1 Sulfuric acid solution. Add the sulfuric acid solution to the Ubbelohde viscometer and place it in a 25°C constant temperature water bath to stabilize for 30 minutes. Measure the outflow time of the solution. Each sample is measured three times, and the time difference is no more than 1 second. The average value is recorded as t1, and the outflow time of concentrated sulfuric acid is recorded as t0. The formula for calculating the intrinsic viscosity [η] of PBI is as follows: Intrinsic viscosity Wherein, C is the concentration of PBI sulfuric acid solution.

[0118] The test results are shown in Table 5.

[0119] Table 5

[0120] Test Example 6

[0121] The polymers of Example 1 and Example 2 were tested for H NMR spectra. H NMR spectra were measured using an Agilent 400-MR DD2 NMR spectrometer at a frequency of 400 MHz, tetramethylsilane (TMS) as the internal standard, DMSO-d6 as the solvent, and a test temperature of 40°C.

[0122] The H NMR spectra of the polymerized products of Examples 1 and 2 are shown in Figure 1. The proton signal at a chemical shift of 13.0 ppm in the spectra can be attributed to the characteristic peak of active hydrogen in the PBI structural unit. The proton signals at 7.30 ppm and 8.28 ppm can be attributed to the characteristic peaks of the corresponding structural units after polymerization of 4,4′-diphenylene oxide dicarboxylic acid monomer. The proton signals at 7.08-7.24 ppm and 7.55-8.02 ppm can be attributed to the characteristic peaks of the corresponding structural units after polymerization of tetramine monomer and tetraphenylethylene dicarboxylic acid monomer, respectively. Spectral analysis results indicate that polymers PBI-1 and PBI-2 were successfully obtained.

[0123] The results of H-NMR spectra showed that polymers PBI-1 to PBI-4 were successfully obtained.

[0124] Comparative Example 1

[0125] The data reported in the following literature were used:

[0126] Facile preparation of porous polybenzimidazole networks and adsorption behavior of CO2 gas,organic and water vapors,Hao Yu et al.,Polym.Chem.,2013,4,961-968(DOI:10.1039 / c2py20908j)

[0127] The experiments in this document used the Autosorb iQ-MP test to measure gas adsorption isotherms at room temperature with an upper pressure limit of 1 bar. The test results are shown in Table 6.

[0128] Table 6

[0129] Comparative Example 2

[0130] The data reported in the following literature were used:

[0131] Influence of polybenzimidazole main chain structure on H2 / CO2separation at elevated temperatures,Xin Li et al,Journal of Membrane Science,Volume 461,1July 2014,Pages 59-68(DOI:10.1016 / j.memsci.2014.03.008)

[0132] The experiments in this paper used Kalrez TM Test, pressure 10-50psi, temperature 30-250℃.

[0133] The test results are shown in Table 7.

[0134] Table 7

[0135] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A polybenzimidazole, characterized in that: The polybenzimidazole contains a structural unit A, wherein the structural unit A has a structure shown in formula (1); Wherein, the X1 group is a connecting group provided by an aromatic compound containing 1 to 10 benzene rings; and the Y group is a connecting group based on tetraphenylethylene; wherein, the X1 group and the Y group each independently contain or do not contain at least one substituent selected from hydroxyl, amino, cyano, halogen, C1-C4 alkyl, C1-C4 haloalkyl.

2. The polybenzimidazole according to claim 1, wherein The polybenzimidazole contains structural unit A and structural unit C, structural unit A and structural unit D, or structural unit A, structural unit B, structural unit C and structural unit D; The structural unit A has a structure shown in formula (1), the structural unit B has a structure shown in formula (2), the structural unit C has a structure shown in formula (1-1), and the structural unit D has a structure shown in formula (2-2): wherein the X1 and X2 groups are each independently a linking group provided by an aromatic compound containing 1 to 10 benzene rings; the Y group is a linking group based on tetraphenylethylene; and the Z group is an aromatic hydrocarbon containing 1 to 10 benzene rings, a heteroaromatic hydrocarbon containing 1 to 10 heterocyclic rings, an aromatic hydrocarbon containing 1 to 3 heterocyclic rings and 1 to 8 benzene rings, a C4-C 10 A connecting group is provided by at least one compound selected from cycloalkanes, C1-C8 alkanes, and C2-C8 olefins; wherein the X1, X2, Y, and Z groups each independently contain or do not contain at least one substituent selected from hydroxyl, amino, cyano, halogen, C1-C4 alkyl, and C1-C4 haloalkyl.

3. The polybenzimidazole according to claim 1, wherein The polybenzimidazole contains a structural unit A and an optional structural unit B, wherein the structural unit A has a structure shown in formula (1) and the structural unit B has a structure shown in formula (2); wherein the X1 and X2 groups are each independently a linking group provided by an aromatic compound containing 1 to 10 benzene rings; the Y group is a linking group based on tetraphenylethylene; and the Z group is an aromatic hydrocarbon containing 1 to 10 benzene rings, a heteroaromatic hydrocarbon containing 1 to 10 heterocyclic rings, an aromatic hydrocarbon containing 1 to 3 heterocyclic rings and 1 to 8 benzene rings, a C4-C 10 A connecting group is provided by at least one compound selected from cycloalkanes, C1-C8 alkanes, and C2-C8 olefins, and when the structural unit B is present, Z and Y are different; wherein, at least one substituent selected from hydroxyl, amino, cyano, halogen, C1-C4 alkyl, and C1-C4 haloalkyl is present or absent on the X1, X2, Y and Z groups independently.

4. The polybenzimidazole according to any one of claims 1 to 3, wherein The X1 and X2 groups are each independently a linking group provided by at least one compound selected from benzene, biphenyl, terphenyl, bridged benzene, pterygene and condensed aromatic hydrocarbons containing 1 to 10 benzene rings; preferably, the X1 and X2 groups are each independently a linking group provided by at least one compound selected from benzene, biphenyl, bridged benzene, pterygene and naphthalene; more preferably, the bridged benzene has a structure shown in formula (3), formula (4) or formula (5), wherein R1, R3 and R4 are each independently selected from oxygen atoms, sulfur atoms, carbonyl groups, sulfonyl groups, methylene groups and halogen-substituted methylene groups; and R2 is selected from heteroaromatic rings; 5. The polybenzimidazole according to any one of claims 1 to 4, wherein The X1 and X2 groups are each independently selected from the following linking groups: wherein G is selected from a hydrogen atom, a methyl group and a trifluoromethoxy group; J is selected from an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, a methylene group and a methylene group substituted with a methyl group or a trifluoromethyl group; L is selected from a bromine atom, a phenyl group and a phenyl group substituted with a trifluoromethyl group; and R is selected from a hydrogen atom, a carboxyl group, a hydroxyl group and a trifluoromethyl group.

6. The polybenzimidazole according to any one of claims 2 to 5, wherein The Z group is benzene, a 5-6 membered nitrogen-containing heterocyclic compound, an aromatic compound containing 2-7 benzene rings, an aromatic compound containing 1-2 nitrogen-containing heterocyclic rings and 1-4 benzene rings, a C4-C 10 A linking group provided by a compound of at least one of cycloalkane, C1-C8 alkane and C2-C8 alkene; Preferably, the Z group is a linking group selected from the following: C1-C8 alkyl; wherein M is selected from a hydrogen atom, a cyano group, a methyl group, a phenyl group, and a phenyl group substituted with a methyl group or a trifluoromethyl group; P is selected from an oxygen atom, a sulfur atom, a carbonyl group, a sulfonyl group, a cyclobutyl group, a cyclobutyl group substituted with a halogen group, a methylene group, and a methylene group substituted with a methyl group or a trifluoromethyl group; Q is selected from a bromine atom, a phenyl group, and a phenyl group substituted with a trifluoromethyl group; and T is selected from a hydrogen atom and a methyl group.

7. The polybenzimidazole according to any one of claims 1 to 6, wherein The Y group is derived from at least one of the following compounds:

8. The polybenzimidazole according to any one of claims 1 to 7, wherein The intrinsic viscosity of the polybenzimidazole is 0.45-3.0 dL g -1 and / or, The molar content ratio of X2 to X1 groups in the polybenzimidazole is 0-9999, preferably 0-99; and / or, The molar content ratio of the Z group to the Y group in the polybenzimidazole is 0-9999, preferably 0-99.

9. The polybenzimidazole according to any one of claims 1 to 8, wherein The free volume of the polybenzimidazole is Preferably And the pore size of the polybenzimidazole is Preferably 10. The polybenzimidazole according to any one of claims 1 to 9, wherein The polybenzimidazole has mechanochromic properties.

11. A method for preparing a polybenzimidazole according to any one of claims 1 to 10, wherein the method comprises reacting at least one compound having a structure represented by formula (6) with HOOC-Y-COOH and optionally HOOC-Z-COOH; in, The X group in formula (6) is the same as the X1 and / or X2 group defined in any one of claims 1 to 10, and the Y and Z groups in HOOC-Y-COOH and the optional HOOC-Z-COOH are each the same as the Y and Z groups defined in any one of claims 1 to 10.

12. The method according to claim 11, wherein the reaction is carried out in a solvent, preferably, the solvent is a mixed solution of methanesulfonic acid / phosphorus pentoxide or polyphosphoric acid, more preferably a mixed solution of methanesulfonic acid / phosphorus pentoxide, and the mass of phosphorus pentoxide is 2-10% of the mass of methanesulfonic acid.

13. The method according to claim 11 or 12, wherein the ratio of the molar amount of the compound having the structure represented by formula (6) to the total molar amount of HOOC-Y-COOH and optional HOOC-Z-COOH is 1:0.6-2, preferably 1:0.8-1.

2.

14. A method for separating CO2 gas by adsorption, wherein the polybenzimidazole according to any one of claims 1 to 10 is used as an adsorbent.

15. The method according to claim 14, wherein the CO2 gas is separated from a gas selected from N2, O2 or a mixture thereof by adsorption.

16. Use of the polybenzimidazole according to any one of claims 1 to 10 as an adsorbent for gas adsorption separation.

17. The use according to claim 16, wherein the polybenzimidazole is used as an adsorbent for separating CO2 gas from a gas selected from N2, O2 or a mixture thereof.

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