CN111303437A - Phosphonated (polyolefin-g-hyperbranched polybenzimidazole) graft copolymer and preparation method and application thereof - Google Patents

Phosphonated (polyolefin-g-hyperbranched polybenzimidazole) graft copolymer and preparation method and application thereof Download PDF

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CN111303437A
CN111303437A CN202010153592.6A CN202010153592A CN111303437A CN 111303437 A CN111303437 A CN 111303437A CN 202010153592 A CN202010153592 A CN 202010153592A CN 111303437 A CN111303437 A CN 111303437A
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CN111303437B (en
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莫肇华
李素丽
李俊义
徐延铭
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Zhuhai Coslight Battery Co Ltd
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Abstract

The invention relates to the field of graft copolymers, in particular to a phosphonated (polyolefin-g-hyperbranched polybenzimidazole) graft copolymer and a preparation method and application thereof. The material of the invention uses polyolefin as a main chain and HBPBI as a branch chain to synthesize the graft copolymer. The polymer with two properties is utilized to construct a proton transmission channel in a micro phase separation state, so that the proton conductivity is improved; in addition, the flexible main chain drives the HBPBI branched chain to move at high temperature so as to reduce proton migration activation energy, promote migration of phosphoric acid or protons and improve proton conductivity. The hyperbranched structure can contain more phosphoric acid, a large number of active sites in the hyperbranched structure can be grafted with a large number of organic phosphonic acids, and the effects of reducing phosphoric acid loss and improving the proton conductivity retention rate are achieved under double conditions, so that the high proton conductivity (0.09S/cm) can be obtained at a lower phosphoric acid doping level (ADL < 9).

Description

Phosphonated (polyolefin-g-hyperbranched polybenzimidazole) graft copolymer and preparation method and application thereof
Technical Field
The invention relates to the field of graft copolymers, in particular to a phosphonated (polyolefin-g-hyperbranched polybenzimidazole) graft copolymer and a preparation method and application thereof.
Background
Benzimidazole Polymers (PBIs) are polymers containing benzimidazole rings in a main chain structure, have excellent physicochemical properties such as chemical stability, thermal stability, flame retardance, mechanical property and the like, and are widely applied to high-temperature-resistant fabrics, fireproof flame-retardant materials, industrial product filter materials and the like. With the development of fuel cell research, the conventional perfluorosulfonic acid proton exchange membrane cannot meet the operation of the fuel cell under the conditions of high temperature and low humidity due to the defects of proton conductivity, mechanical property reduction and the like under the conditions of high temperature and low humidity, and researchers begin to search and research novel proton exchange membrane materials. PBIs are favored because of their excellent chemical and thermal stability, and researchers have found that although PBIs are not proton conductive, PBIs exhibit basicity due to their specific imidazole ring structure, and protonate with inorganic acids, especially Phosphoric Acid (PA), to form ion pairs, resulting in certain ionic conductivity.
In the field of high temperature proton exchange membranes, the proton conductivity of PBIs-based proton exchange membranes is heavily dependent on their phosphoric acid doping level (ADL, number of moles of phosphoric acid bound per mole of polymer repeat unit),to make such membranes have high proton conductivity, a large amount of phosphoric acid needs to be incorporated, which leads to a significant reduction in the mechanical properties of the membrane, and therefore, a balance between proton conductivity and mechanical properties needs to be considered; in addition, more phosphoric acid is easy to run off along with water generated by the cathode in the using process, and the proton conductivity of the membrane is reduced. The conventional solution to the above problems is crosslinking, incorporation of proton carriers such as zirconium phosphate, heteropoly acid, ionic liquid, etc., or introduction of SiO2、TiO2Clay, zeolite, and montmorillonite. In the prior art, a cross-linking type high-temperature proton exchange membrane is formed by self-crosslinking by taking polybenzimidazole as a polymer framework and triazole ionic liquid-based polyethylene as a cross-linking agent; in the prior art, it has also been reported that 0.1-30% of acid modified ordered mesoporous SiO is doped into the composite high-temperature proton exchange membrane2The proton transfer is promoted, and the proton conductivity is improved; or doping inorganic porous materials in the PBIs membrane to prepare the composite membrane.
Therefore, how to reduce the phosphoric acid doping level in the PBIs matrix proton exchange membrane doped with phosphoric acid and obtain high proton conductivity and high conductivity retention rate under the high-temperature anhydrous condition is a very challenging research direction and has a very good research and application prospect.
Disclosure of Invention
As mentioned above, the benzimidazole polymer as a proton exchange membrane material has the problem of how to achieve higher proton conductivity and conductivity retention rate under the condition of less phosphoric acid. Therefore, the invention designs and synthesizes a graft copolymer which takes polyolefin as a main chain and hyperbranched polybenzimidazole (HBPBI) as a branched chain, the graft copolymer constructs a proton transmission channel through a phase separation structure of two chain segments, thereby improving the proton conductivity, a large amount of organic phosphonic acid can be introduced through the multi-end group characteristic of the hyperbranched structure, simultaneously, the hyperbranched structure can contain more phosphoric acid, the loss of the phosphoric acid can be reduced, the effect of improving the proton conductivity retention rate is achieved, and the high-temperature proton exchange membrane (the test temperature reaches 180 ℃) with higher proton conductivity (the highest can reach 0.09S/cm) and higher proton conductivity retention rate (the highest can reach 93%) is obtained under the condition of lower phosphoric acid doping level (ADL < 9).
Specifically, the invention provides the following technical scheme:
a graft copolymer is prepared by mixing and reacting an amino-containing hyperbranched benzimidazole polymer, a partially phosphonated olefin polymer with a side chain containing carboxyl and carboxyl-containing phosphonic acid.
The graft copolymer is a polymer obtained by the condensation reaction of terminal amino in amino-containing hyperbranched benzimidazole polymer and carboxyl of partially phosphonated olefin polymer with carboxyl on the side chain, wherein the amino-containing hyperbranched benzimidazole polymer is grafted to the main chain of the partially phosphonated olefin polymer with carboxyl on the side chain, and the polymer is the polyolefin-g-hyperbranched benzimidazole polymer with amino on the side chain; and then, further grafting phosphonic acid containing carboxyl on the polyolefin-g-hyperbranched benzimidazole polymer with the side chain containing amino to obtain the graft copolymer, which is marked as a phosphonated (polyolefin-g-hyperbranched benzimidazole polymer) graft copolymer.
The invention also provides a preparation method of the graft copolymer, which comprises the following steps:
(1) mixing olefin polymer with side chain containing carboxyl and phosphonic acid containing amino, and reacting to obtain partially phosphonated olefin polymer with side chain containing carboxyl;
(2) dissolving hyperbranched benzimidazole polymer containing amino, olefin polymer with partial phosphonic acid containing carboxyl on side chain and phosphonic acid containing carboxyl in an organic solvent, and reacting under heating to prepare the graft copolymer.
The invention also provides a proton exchange membrane which comprises the graft copolymer.
Wherein, the proton exchange membrane is also doped with phosphoric acid.
The invention also provides a preparation method of the proton exchange membrane, which comprises the following steps:
(s1) mixing the olefin polymer having carboxyl in the side chain and phosphonic acid having amino group, and reacting to obtain partially phosphonated olefin polymer having carboxyl in the side chain;
dissolving amino-containing hyperbranched benzimidazole polymer, olefin polymer with partial phosphonic acid containing carboxyl on side chains and carboxyl-containing phosphonic acid in an organic solvent, and reacting under heating;
(s2) after the reaction is finished, pouring the solution into the surface of the base material for tape casting while the solution is hot, volatilizing the solvent at the temperature of 60-120 ℃, and obtaining a polymer film after the solvent is completely volatilized;
(s3) soaking the polymer membrane obtained in the step (s2) in a phosphoric acid solution, taking out and drying to obtain the phosphoric acid doped proton exchange membrane.
The invention also provides the application of the proton exchange membrane in the fields of fuel cells, flow batteries and the like.
It is to be understood that the above-described technical features of the present invention and the respective technical features described in detail hereinafter may be combined with each other to constitute a new or preferred technical solution.
The invention has the beneficial effects that:
the material of the invention uses polyolefin as a main chain and HBPBI as a branch chain to synthesize the graft copolymer. The polymer with two properties is utilized to construct a proton transmission channel in a micro phase separation state, so that the proton conductivity is improved; in addition, the flexible main chain of the polyolefin group drives the HBPBI branched chain to move at high temperature so as to reduce the proton migration activation energy, promote the migration of phosphoric acid or protons and improve the proton conductivity. The hyperbranched structure can contain more phosphoric acid, a large number of active sites in the hyperbranched structure can be grafted with a large number of organic phosphonic acids, and the effects of reducing phosphoric acid loss and improving the proton conductivity retention rate are achieved under double conditions, so that the high proton conductivity (0.09S/cm) can be obtained at a lower phosphoric acid doping level (ADL < 9).
Drawings
FIG. 1 Infrared spectrum of polyacrylic acid (PAA), partially phosphonated polyacrylic acid (LPAA), hyperbranched polybenzimidazole (HBPBI), and phosphonated (polyacrylic acid-g-hyperbranched polybenzimidazole) (L (PAA-g-HBPBI)) in example 1.
FIG. 2 is a schematic representation of the molecular structures of examples 1-6 (phosphonation # 1 (PAA-g-HBPBI)) and examples 7-12 (phosphonation # 2 (PMAA-g-HBPBI)).
Detailed Description
< graft copolymer >
A graft copolymer is prepared by mixing and reacting an amino-containing hyperbranched benzimidazole polymer, a partially phosphonated olefin polymer with a side chain containing carboxyl and carboxyl-containing phosphonic acid.
According to the invention, the partially phosphonated olefin polymer has a degree of phosphonated 1% to 99%, for example 1%, 2%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 88%, 90%, 95% or 99%.
According to the invention, the graft copolymer is a polymer obtained by a condensation reaction of a terminal amino group in an amino-containing hyperbranched benzimidazole polymer and a carboxyl group of a partially phosphonated olefin polymer with a side chain containing a carboxyl group, wherein the amino-containing hyperbranched benzimidazole polymer is grafted to a main chain of the partially phosphonated olefin polymer with a side chain containing a carboxyl group, and the polymer is a polyolefin-g-hyperbranched benzimidazole polymer with a side chain containing an amino group; and then, further grafting phosphonic acid containing carboxyl on the polyolefin-g-hyperbranched benzimidazole polymer with the side chain containing amino to obtain the graft copolymer, which is marked as a phosphonated (polyolefin-g-hyperbranched benzimidazole polymer) graft copolymer.
Specifically, the graft copolymer contains a structural unit represented by the following formula (I):
Figure BDA0002403267880000051
in the formula (I), R' is selected from H and alkyl; r' is selected from the group consisting of absent, substituted or unsubstituted arylene, substituted or unsubstituted alkylene wherein the substituents may be selected from the group consisting of alkyl, carboxy, C, O,halogen; r1Through a terminal amino group (-NH)2) A phosphorylated hyperbranched benzimidazole polymer chain segment grafted to a partially phosphorylated olefin polymer backbone after undergoing a condensation reaction with-COOH on R'; r2A residue selected from amino-containing phosphonic acids; r3A residue selected from carboxyl-containing phosphonic acids; m is an integer between 100 and 50000;
when R' is absent, z is 0, 1 ≧ x >0, y1+ y2 is 1-x; when R' is arylene or alkylene, 1> z ≧ 0, 1 ≧ x >0, y1+ y2 ═ 1-z-x.
Wherein x is preferably 0.001 to 0.5, more preferably 0.01 to 0.4, and still more preferably 0.05 to 0.3.
Wherein y2 may be 0.
Specifically, the R' is selected from H, C1-6An alkyl group; still more specifically, said R "is selected from H, methyl.
Specifically, R' is selected from the group consisting of absent, substituted or unsubstituted alkylene, substituted or unsubstituted phenylene, wherein the substituent may be selected from the group consisting of alkyl, carboxyl. For example, the R' is selected from absent, or one or more of the following:
Figure BDA0002403267880000061
wherein denotes the connection point.
Specifically, the polyolefin-g-hyperbranched benzimidazole polymer with the side chain containing amino comprises a structural unit shown as the following formula (I'):
Figure BDA0002403267880000062
in the formula (I '), R', R2M, x, y1, y2, z are as defined above, R'1Through a terminal amino group (-NH)2) And (3) the hyperbranched benzimidazole polymer containing amino groups grafted to the main chain of the partially phosphonated olefin polymer after undergoing a condensation reaction with-COOH on R'.
More specifically, the molecular structural formula of the polyolefin-g-hyperbranched benzimidazole polymer with the side chain containing amino is one of the following:
Figure BDA0002403267880000063
Figure BDA0002403267880000071
wherein x, y1, y2, z, m and R'1And R2The definition of (1) is as before; ar is selected from one or more of the following groups:
Figure BDA0002403267880000072
denotes the connection point.
Specifically, the amino-containing hyperbranched benzimidazole polymer is a polymer with a main chain structure containing benzimidazole rings and a side chain containing a branched structure. More specifically, the amino-containing hyperbranched benzimidazole polymer is a main chain structure containing benzimidazole rings, the side chain contains a branched structure, and one end of the main chain and one end of the branched structure are connected with amino (-NH)2) The polymer of (1). According to requirements, the polymerization degree of the amino-containing hyperbranched benzimidazole polymer can be 1-100.
Specifically, the amino-containing hyperbranched benzimidazole polymer is prepared by taking a compound containing three carboxyl groups and a compound containing four amino groups as monomers and performing solution condensation reaction.
Wherein, the compound containing three carboxyl groups is, for example, a six-membered ring compound containing three carboxyl groups; substituted or unsubstituted, straight or branched chain aliphatic compounds containing three carboxyl groups (e.g., alkanes); or at least one compound having a structure represented by the following formula (III):
Figure BDA0002403267880000081
in the formula (III), theY is selected from,
Figure BDA0002403267880000082
-S-、-O-、
Figure BDA0002403267880000083
Wherein the six-membered ring compound may be benzene, pyridine or imidazole; the aliphatic compound may be C3-10An alkane; the substituent may be H2PO3、C1-6An alkyl group.
Specifically, the compound containing three carboxyl groups is selected from:
Figure BDA0002403267880000084
specifically, the compound containing four amino groups is selected from at least one of the following structures of formula (IV) or formula (V):
Figure BDA0002403267880000085
in the formulae (IV) to (V), X is selected from,
Figure BDA0002403267880000091
-S-、-O-、
Figure BDA0002403267880000092
Halogen substituted or unsubstituted C1-6An alkyl group.
Specifically, the amino-containing hyperbranched benzimidazole polymer is selected from at least one of the following structures of formula (VI) to formula (VII):
Figure BDA0002403267880000093
in formulae (VI) to (VII), X is as defined above; n is an integer between 1 and 100; represents a branch point; r is selected from the group consisting of residues of compounds containing three carboxyl groups.
Specifically, R is selected from at least one of the following structures:
Figure BDA0002403267880000094
denotes the connection point.
In one embodiment of the invention, X is selected from absent,
Figure BDA0002403267880000095
-S-、-O-、-C(CH3)2-、-C(CF3)2-、-CH2-。
Illustratively, the amino group-containing hyperbranched benzimidazole polymer is selected from at least one of the following structures:
Figure BDA0002403267880000101
wherein n and R are as defined above and are branch points.
Also illustratively, the structure of the amino group-containing hyperbranched benzimidazole polymer is shown as follows:
Figure BDA0002403267880000111
wherein n, R and X are as defined above, n' is an integer between 1 and 100, and X is a branching point.
According to the present invention, the structural formula of the partially phosphonated olefin-based polymer having a carboxyl group in a side chain is shown as the following formula (VIII):
Figure BDA0002403267880000112
in formula (VIII), t ═ x + y2, R', R2M, z, x, y1, y2 are as defined above. Further, y1/(y1+ t) is 0.01 to 0.99.
According to the invention, the partially phosphonated olefin polymer with side chain containing carboxyl is prepared after the grafting reaction of the olefin polymer with side chain containing carboxyl and phosphonic acid containing amino.
Wherein the molar ratio of the amino-containing phosphonic acid to the carboxyl functional groups in the olefin polymer with the side chains containing carboxyl groups is 0.01-0.99: 1.
Specifically, the olefin polymer having a carboxyl group in a side chain is at least one selected from polyacrylic acid (PAA), polymethacrylic acid (PMAA), and carboxylated polystyrene.
Specifically, the structural formula of the amino-containing phosphonic acid is NH2-R2-H2PO3(ii) a Wherein R is2Is as defined above.
Still more specifically, the amino group-containing phosphonic acid is selected from at least one of 4-amino-1-hydroxybutylidene-1, 1-diphosphonic acid (alendronic acid), 4-aminobutylphosphonic acid, 2-aminoethylphosphonic acid, 3-aminobutylphosphonic acid, 3-aminopropylphosphonic acid, (1-aminoethyl) phosphonic acid, (1-aminopropyl) phosphonic acid, (1-aminobutyl) phosphonic acid, 2-amino-5-phosphonovaleric acid, 5-aminopentylphosphonic acid, 4-aminopentylphosphonic acid, 3-aminopentylphosphonic acid, (4-aminophenyl) phosphonic acid, (3-aminophenyl) phosphonic acid, (2-aminophenyl) phosphonic acid; preferably, it is selected from at least one of 4-amino-1-hydroxybutylidene-1, 1-diphosphonic acid (alendronic acid), 4-aminobutylphosphonic acid, 2-aminoethylphosphonic acid, 3-aminobutylphosphonic acid.
Specifically, the structural formula of the phosphonic acid containing carboxyl is COOH-R3-H2PO3(ii) a Wherein R is3Is as defined above.
Still more specifically, the carboxyl group-containing phosphonic acid is selected from phosphonoacetic acid, phosphonopropionic acid, phosphonobutyric acid, 5-phosphonovaleric acid, 6-phosphonohexanoic acid, 7-phosphonoheptanoic acid, 8-phosphonooctanoic acid, 9-phosphonononanoic acid, 10-phosphonodecanoic acid, 11-phosphonoundecanoic acid, 16-phosphonohexadecanoic acid, 3-phosphonopropionic acid, 4-phosphonobutyric acid, DL-2-amino-3-phosphonopropionic acid, DL-2-amino-4-phosphonobutyric acid, DL-2-amino-5-phosphonovaleric acid, DL-2-amino-6-phosphonohexanoic acid, DL-2-amino-7-phosphonoheptanoic acid, DL-2-amino-6-phosphono-hexanoic acid, DL-4-phosphono-1, 4-phosphobutyric acid, 2- (phosphomethyl) pentanedioic acid, 4-phosphorylbenzoic acid, 3-phosphorylbenzoic acid, and glyphosate.
According to the invention, from the design of a polymer structure, firstly, partial phosphorylation is carried out on an olefin polymer with a side chain containing carboxyl by using phosphonic acid containing amino, and the partially phosphorylated olefin polymer with the side chain containing carboxyl is obtained; then, carrying out condensation reaction on terminal amino groups in the amino-containing hyperbranched benzimidazole polymer and carboxyl groups of the partially phosphonated olefin polymer with side chains containing carboxyl groups to obtain a polymer in which the amino-containing hyperbranched benzimidazole polymer is grafted to a main chain of the partially phosphonated olefin polymer with side chains containing carboxyl groups, namely the polyolefin-g-hyperbranched benzimidazole polymer with side chains containing amino groups; and then, further grafting phosphonic acid containing carboxyl on the polyolefin-g-hyperbranched benzimidazole polymer with the side chain containing amino to obtain the graft copolymer, and marking as a phosphonated (polyolefin-g-hyperbranched polybenzimidazole) graft copolymer. Researches show that the proton exchange membrane containing the phosphonated graft copolymer is suitable for being used as a high-temperature proton exchange membrane, and has higher proton conductivity (up to 0.09S/cm) and higher proton conductivity retention rate (up to 93%) under the condition of lower phosphoric acid doping level (ADL <9), thereby achieving the aim of the invention.
The "halogen" in the invention refers to fluorine, chlorine, bromine or iodine.
"alkyl" used herein alone or as suffix or prefix, is intended to include both branched and straight chain saturated aliphatic hydrocarbon groups having from 1 to 20, preferably from 1 to 6, carbon atoms. For example, "C1-6Alkyl "denotes straight-chain and branched alkyl groups having 1,2, 3, 4, 5 or 6 carbon atoms. Examples of alkyl groups include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, tert-butyl, pentyl, and hexyl.
"aryl" used herein alone or as a suffix or prefix, refers to an aromatic ring structure made up of 5 to 20 carbon atoms. For example: the aromatic ring structure containing 5, 6, 7 and 8 carbon atoms may be a monocyclic aromatic group such as phenyl; the ring structure containing 8, 9, 10, 11, 12, 13 or 14 carbon atoms may be polycyclic, for example naphthyl. The aromatic ring may be substituted at one or more ring positions with substituents such as alkyl, carboxyl and the like, for example tolyl.
The "alkylene" in the present invention is a group obtained by substituting one H with the "alkyl".
The "arylene" of the present invention is a group obtained by substituting one H with the "aryl".
< preparation of graft copolymer >
The invention also provides a preparation method of the graft copolymer, which comprises the following steps:
(1) mixing olefin polymer with side chain containing carboxyl and phosphonic acid containing amino, and reacting to obtain partially phosphonated olefin polymer with side chain containing carboxyl;
(2) dissolving hyperbranched benzimidazole polymer containing amino, olefin polymer with partial phosphonic acid containing carboxyl on side chain and phosphonic acid containing carboxyl in an organic solvent, and reacting under heating to prepare the graft copolymer.
In one embodiment of the present invention, in the step (1), the olefin-based polymer having carboxyl groups in side chains is, for example, at least one selected from polyacrylic acid (PAA), polymethacrylic acid (PMAA), and carboxylated polystyrene.
In one embodiment of the present invention, in step (1), the molar ratio of the amino-containing phosphonic acid to the carboxyl functional groups in the side chain carboxyl-containing olefin-based polymer is 0.01 to 0.99: 1.
In one embodiment of the present invention, in the step (1), the temperature of the reaction is 100-150 ℃, and the time of the reaction is 6-24 h; the reaction is carried out under an inert atmosphere.
In one embodiment of the present invention, in the step (2), the organic solvent is one or a combination of more of the following: DMF (N, N-dimethylformamide), DMAc (N, N-dimethylacetamide), DMSO (dimethyl sulfoxide), NMP (N, N-dimethylpyrrolidone).
In one embodiment of the present invention, in step (2), the amino group-containing hyperbranched benzimidazole polymer may be commercially available or may be prepared by the following method:
and mixing a compound containing three carboxyl groups, a compound containing four amino groups and polyphosphoric acid, and reacting to prepare the amino-containing hyperbranched benzimidazole polymer.
For example, when the molar ratio of the compound containing four amino groups to the compound containing three carboxyl groups is 1.6:1 to 3:1, the hyperbranched benzimidazole polymer containing the amino groups is prepared.
Wherein the compound containing three carboxyl groups and the compound containing four amino groups account for 0.5-4% of the total solution by mass.
The preparation method of the amino-containing hyperbranched benzimidazole polymer specifically comprises the following steps:
dissolving a compound containing three carboxyl groups and a compound containing four amino groups in polyphosphoric acid, wherein the molar ratio of the compound containing four amino groups to the compound containing three carboxyl groups is 1.6:1-3:1, and reacting at 150-250 ℃ for 6-24h to prepare the amino-containing hyperbranched benzimidazole polymer.
Wherein, still include after the reaction stops: the solution is precipitated in water, then washed with deionized water for 2 times, added with sodium bicarbonate to be alkaline, and then washed with deionized water to be neutral. And collecting the solid, and drying the solid in vacuum at the temperature of 60 ℃ to obtain the hyperbranched benzimidazole polymer.
In one embodiment of the invention, in the step (2), the reaction is carried out under the protection of inert gas under the heating condition of 120-160 ℃; specifically, the reaction time is 6-24 h.
In one embodiment of the present invention, in the step (2), the mass ratio of the amino group-containing hyperbranched benzimidazole-based polymer to the partially phosphonated olefin-based polymer having a carboxyl group in a side chain is 3 to 0.5:1, for example, 3:1, 2.4:1, 2.2:1, 2:1, 1.75:1, 1.5:1, 1.3:1, 1.15:1, 1:1, 0.97:1, 0.95:1, 0.93:1, or 0.7: 1.
In one embodiment of the invention, in the step (2), the amount of the phosphonic acid containing carboxyl is 0.15 to 0.86 times of the molar amount of the four amino compounds used for preparing the amino-containing hyperbranched benzimidazole polymer.
In one embodiment of the present invention, in the step (2), the method specifically includes the following steps:
(2-1) dissolving an amino-containing hyperbranched benzimidazole polymer and a partially phosphonated olefin polymer of which the side chain contains carboxyl in an organic solution to obtain a solution a;
(2-2) dissolving a phosphonic acid containing a carboxyl group in a solvent to obtain a solution b;
(2-3) reacting the solution a at 120-150 ℃ for 2-10 h, then slowly dripping the solution b, and reacting at the temperature for 5-12 h.
< proton exchange Membrane and preparation thereof >
The invention also provides a proton exchange membrane which comprises the graft copolymer.
Furthermore, the proton exchange membrane is also doped with phosphoric acid.
Further, the doping level ADL of phosphoric acid is less than 9.
The invention also provides a preparation method of the proton exchange membrane, which comprises the following steps:
(s1) mixing the olefin polymer having carboxyl in the side chain and phosphonic acid having amino group, and reacting to obtain partially phosphonated olefin polymer having carboxyl in the side chain;
dissolving amino-containing hyperbranched benzimidazole polymer, olefin polymer with partial phosphonic acid containing carboxyl on side chains and carboxyl-containing phosphonic acid in an organic solvent, and reacting under heating;
(s2) after the reaction is finished, pouring the solution into the surface of the base material for tape casting while the solution is hot, volatilizing the solvent at the temperature of 60-120 ℃, and obtaining a polymer film after the solvent is completely volatilized;
(s3) soaking the polymer membrane obtained in the step (s2) in a phosphoric acid solution, taking out and drying to obtain the phosphoric acid doped proton exchange membrane.
In the present invention, the specific conditions in step (s1) are the same as in step (1) and step (2) in the above-mentioned production method of a graft copolymer.
In the step (s2), the base material is one of copper foil, aluminum foil, glass plate, polypropylene, polyester, polytetrafluoroethylene, and polyvinylidene fluoride.
In the step (s3), the concentration of phosphoric acid is 60 to 90 wt%.
In step (s3), the immersion time is 6 to 30 hours, for example 12 to 24 hours.
In the step (s3), the drying temperature is 60-90 ℃.
The invention also provides the application of the proton exchange membrane in the fields of fuel cells, flow batteries and the like.
The preparation method of the present invention will be described in further detail with reference to specific examples. It is to be understood that the following examples are only illustrative and explanatory of the present invention and should not be construed as limiting the scope of the present invention. All the technologies realized based on the above-mentioned contents of the present invention are covered in the protection scope of the present invention.
The experimental methods used in the following examples are all conventional methods unless otherwise specified; reagents, materials and the like used in the following examples are commercially available unless otherwise specified.
Example 1
(1) Polyphosphoric Acid (PPA)1219g was added to a dry three-necked flask, and the mixture was heated to 120 ℃ and then 3.43g of 3, 3-Diaminobenzidine (DAB) and 2.70g of 2-phosphonobutane-1, 2, 4-tricarboxylic acid (PBTCA) were added simultaneously in a molar ratio of 1.6:1, and the solid content was 0.5% of the total solution, and the mixture was stirred at this temperature for 4 hours to dissolve the solid sufficiently. The temperature is increased to 150 ℃, the reaction is maintained for 3 hours in a nitrogen atmosphere, and then the reaction is heated to 200 ℃ for 20 hours. After the reaction is stopped, the solution is precipitated into water, washed by deionized water for 2 times, added with sodium bicarbonate to be alkaline, and washed by deionized water to be neutral. The solid was collected and dried under vacuum at 60 ℃ to give amino-terminated hyperbranched polybenzimidazole (HBPBI).
(2) 0.3g of polyacrylic acid (PAA) is dissolved in DMAc, then 0.986g of alendronic acid (95% of carboxyl mol) is added, the reaction is carried out for 12h at 150 ℃ under the protection of nitrogen, and then the solvent is rotated and evaporated and dried to obtain the partially phosphonated PAA (LPAA).
(3) A total of 3.91g of HBPBI in (1) and LPAA in (2) was dissolved in DMAc in a mass ratio of 2.22:1 to obtain solution a. 0.588g of phosphonoacetic acid was dissolved in DMF to give a solution b. The solution a was reacted at 150 ℃ for 10h and then the solution b was slowly added dropwise and reacted at this temperature for 12 h. After the reaction was completed, the solution was coated on a glass plate by a doctor blade method and dried at 60 ℃ to obtain a phosphonated (polyacrylic acid-g-hyperbranched polybenzimidazole) (L (PAA-g-HBPBI) film.
(4) And (3) placing the (L (PAA-g-HBPBI) membrane in 85% phosphoric acid solution at 60 ℃ for 24h, taking out and drying to obtain the (L (PAA-g-HBPBI) proton exchange membrane.
The test shows that the ADL of the proton exchange membrane is 8.15, the proton conductivity is 0.0879S/cm, the proton conductivity is 0.0746S/cm after 10 times of deionized water immersion, and the retention rate of the proton conductivity is 84.9%.
Example 2
(1) The other operations are the same as example 1, except that: polyphosphoric Acid (PPA)1219g was added to a dry three-necked flask, and the mixture was heated to 120 ℃ and then DAB 3.86g and PBTCA 2.70g were added simultaneously in a molar ratio of 1.8:1, with a solid content of 0.8% of the total solution, and stirred at this temperature for 4 hours to dissolve the solid sufficiently. The temperature is increased to 150 ℃, the reaction is maintained for 3 hours in a nitrogen atmosphere, and then the reaction is heated to 200 ℃ for 20 hours.
(2) 0.45g of PAA was dissolved in DMAc, then 1.090g of alendronic acid (70% of carboxyl mol) was added and reacted at 150 ℃ for 12h under nitrogen protection, then the solvent was rotary evaporated and dried to obtain partially phosphonated PAA (LPAA).
(3) A total mass of 4.01g of (1) HBPBI and (2) LPAA was dissolved in DMAc in a mass ratio of 1.75:1 to obtain a solution a. 1.502g of phosphonoacetic acid was dissolved in DMF to give a solution b. The rest is the same as in example 1.
(4) Same as in example 1.
The test shows that the ADL of the proton exchange membrane is 7.45, the proton conductivity is 0.0915S/cm, the proton conductivity is 0.0817S/cm after 10 times of deionized water immersion, and the proton conductivity retention rate is 89.3%.
Example 3
(1) The other operations are the same as example 1, except that: PPA 691g was added to a dry three-necked flask, the temperature was raised to 120 ℃, then DAB 4.28g and PBTCA 2.70g were added simultaneously in a molar ratio of 2:1, the solid content was 1.0% of the total solution, and the mixture was stirred at this temperature for 4 hours to dissolve the solid sufficiently. The temperature is increased to 150 ℃, the reaction is maintained for 3 hours in a nitrogen atmosphere, and then the reaction is heated to 200 ℃ for 16 hours.
(2) 0.75g of PAA is dissolved in DMAc, then 1.297g of alendronic acid (50 percent of carboxyl mole) is added, and the mixture is reacted for 12h at 150 ℃ under the protection of nitrogen, and then the solvent is rotated and evaporated and dried to obtain the partially phosphonated PAA (LPAA).
(3) 4.20g of (1) HBPBI and (2) LPAA in a total mass ratio of 1.15:1 were dissolved in DMAc to obtain a solution a. 2.211g of phosphonoacetic acid was dissolved in DMF to give a solution b. The rest is the same as in example 1.
(4) Same as in example 1.
The test shows that the ADL of the proton exchange membrane is 6.27, the proton conductivity is 0.0934S/cm, the proton conductivity is 0.0869S/cm after 10 times of deionized water immersion, and the proton conductivity retention rate is 93.0%.
Example 4
(1) The other operations are the same as example 1, except that: 368g of PPA was added to a dry three-necked flask, the temperature was raised to 120 ℃, 4.82g of DAB and 2.70g of PBTCA were added simultaneously in a molar ratio of 2.25:1, the solid content was 2.0% of the total solution, and the mixture was stirred at this temperature for 4 hours to dissolve the solid sufficiently. The temperature is increased to 150 ℃, the reaction is maintained for 3 hours in a nitrogen atmosphere, and then the reaction is heated to 200 ℃ for 12 hours.
(2) 1.05g of PAA is dissolved in DMAc, then 1.090g of alendronic acid (30 percent of carboxyl mole) is added, and the mixture is reacted for 6h at 150 ℃ under the protection of nitrogen, and then the solvent is rotationally evaporated and dried to obtain the partially phosphonated PAA (LPAA).
(3) A total mass of 4.01g of (1) HBPBI and (2) LPAA was dissolved in DMAc in a mass ratio of 0.95:1 to obtain a solution a. 2.981g of phosphonoacetic acid was dissolved in DMF to give a solution b. The rest is the same as in example 1.
(4) Same as in example 1.
The test shows that the ADL of the proton exchange membrane is 5.31, the proton conductivity is 0.0903S/cm, the proton conductivity is 0.0834S/cm after 10 times of deionized water immersion, and the retention rate of the proton conductivity is 92.3%.
Example 5
(1) The other operations are the same as example 1, except that: 260g of PPA was added to a dry three-necked flask, the temperature was raised to 120 ℃, then 5.36g of DAB and 2.70g of PBTCA were added simultaneously in a molar ratio of 2.5:1, the solid content was 3.0% of the total solution, and the mixture was stirred at this temperature for 4 hours to dissolve the solid sufficiently. The temperature is increased to 150 ℃, the reaction is maintained for 3 hours in a nitrogen atmosphere, and then the reaction is heated to 200 ℃ for 8 hours.
(2) 1.35g of PAA is dissolved in DMAc, then 0.465g of alendronic acid (10 percent of carboxyl mol) is added, and the mixture is reacted for 12h at 150 ℃ under the protection of nitrogen, and then the solvent is rotated and evaporated and dried to obtain the partially phosphonated PAA (LPAA).
(3) A total of 3.43g of (1) HBPBI and (2) LPAA were dissolved in DMAc in a mass ratio of 0.93:1 to obtain a solution a. 3.518g of phosphonoacetic acid was dissolved in DMF to give a solution b. The rest is the same as in example 1.
(4) Same as in example 1.
Tests show that the ADL of the proton exchange membrane is 4.67, the proton conductivity is 0.0793S/cm, the proton conductivity is 0.0677S/cm after 10 times of deionized water immersion, and the proton conductivity retention rate is 85.4%.
Example 6
(1) The other operations are the same as example 1, except that: 209g of PPA was added to a dry three-necked flask, the temperature was raised to 120 ℃, then 6.00g of DAB and 2.70g of PBTCA were added simultaneously in a molar ratio of 2.8:1, the solid content was 4.0% of the total solution, and the mixture was stirred at this temperature for 4 hours to dissolve the solid sufficiently. The temperature is increased to 150 ℃, the reaction is maintained for 3 hours in a nitrogen atmosphere, and then the reaction is heated to 200 ℃ for 6 hours.
(2) 1.65g of PAA is dissolved in DMAc, then 0.285g of alendronic acid (5 percent of carboxyl mole) is added, and the mixture is reacted for 12 hours at 150 ℃ under the protection of nitrogen, and then the solvent is rotated and evaporated and dried to obtain the partially phosphonated PAA (LPAA).
(3) A total of 3.26g of (1) HBPBI and (2) LPAA were dissolved in DMAc in a mass ratio of 0.71:1 to obtain a solution a. 4.596g of phosphonoacetic acid was dissolved in DMF to give a solution b. The rest is the same as in example 1.
(4) Same as in example 1.
The test shows that the ADL of the proton exchange membrane is 3.77, the proton conductivity is 0.0778S/cm, the proton conductivity is 0.0621S/cm after 10 times of deionized water immersion, and the retention rate of the proton conductivity is 79.8%.
Example 7
(1) 1100g of PPA was charged into a dry three-necked flask, the temperature was raised to 120 ℃, and then 3.43g of DAB and 2.10g of trimesic acid (BTA) were simultaneously charged in a molar ratio of 1.6:1, the solid content was 0.5% of the total solution, and the mixture was stirred at this temperature for 4 hours to sufficiently dissolve the solid. The temperature is increased to 150 ℃, the reaction is maintained for 3 hours in a nitrogen atmosphere, and then the reaction is heated to 200 ℃ for 20 hours. After the reaction is stopped, the solution is precipitated into water, washed by deionized water for 2 times, added with sodium bicarbonate to be alkaline, and washed by deionized water to be neutral. The solid was collected and dried under vacuum at 60 ℃ to give amino-terminated HBPBI.
(2) 0.3g of polymethacrylic acid (PMAA) is dissolved in DMAc, then 0.816g of alendronic acid (95 percent of the mole number of carboxyl) is added, the mixture is reacted for 12 hours at 150 ℃ under the protection of nitrogen, and then the solvent is rotationally evaporated and dried to obtain the partially phosphonated PMAA.
(3) 4.25g of (1) HBPBI and (2) partially phosphonated PMAA in a total mass of 4.25g were dissolved in DMAc in a mass ratio of 3:1 to give a solution a. 0.564g of phosphonoacetic acid was dissolved in DMF to give a solution b. The solution a was reacted at 150 ℃ for 10h and then the solution b was slowly added dropwise and reacted at this temperature for 12 h. After the reaction, the solution was spread on a glass plate by a doctor blade method and dried at 60 ℃ to obtain a phosphonated (polymethacrylic acid-g-hyperbranched polybenzimidazole) (L (PMAA-g-HBPBI) membrane.
(4) And (3) putting the (L (PMAA-g-HBPBI) membrane into 85% phosphoric acid solution at 60 ℃ for 24h, taking out and drying to obtain the L (PMAA-g-HBPBI) proton exchange membrane.
The test shows that the ADL of the proton exchange membrane is 8.66, the proton conductivity is 0.0827S/cm, the proton conductivity is 0.0563S/cm after 10 times of deionized water immersion, and the retention rate of the proton conductivity is 77.5%.
Example 8
(1) The other operations are the same as those of example 7, except that: in a dry three-necked flask, 738g of PPA was charged, the temperature was raised to 120 ℃ and then 3.86g of DAB and 2.10g of BTA were simultaneously charged in a molar ratio of 1.8:1, the solid content was 0.8% of the total solution, and the mixture was stirred at this temperature for 4 hours to sufficiently dissolve the solid. The temperature is increased to 150 ℃, the reaction is maintained for 3 hours in a nitrogen atmosphere, and then the reaction is heated to 200 ℃ for 20 hours.
(2) 0.45g of PMAA is dissolved in DMAc, then 0.902g of alendronic acid (70 percent of the mol number of carboxyl) is added, and the mixture is reacted for 12 hours at 150 ℃ under the protection of nitrogen, and then the solvent is rotationally evaporated and dried to obtain the partially phosphonated PMAA.
(3) A total mass of 3.85g of (1) HBPBI and (2) partially phosphonated PMAA was dissolved in DMAc in a mass ratio of 2:1 to obtain a solution a. 1.547g of phosphonoacetic acid was dissolved in DMF to give a solution b. The rest is the same as in example 1.
(4) Same as in example 1.
The test shows that the ADL of the proton exchange membrane is 7.81, the proton conductivity is 0.0807S/cm, the proton conductivity is 0.0671S/cm after 10 times of deionized water immersion, and the proton conductivity retention rate is 83.2%.
Example 9
(1) The other operations are the same as those of example 7, except that: PPA 632g was added to a dry three-necked flask, the temperature was raised to 120 ℃, then DAB 4.28g and BTA 2.10g were added simultaneously in a molar ratio of 2:1, the solid content was 1.0% of the total solution, and the mixture was stirred at this temperature for 4 hours to dissolve the solid sufficiently. The temperature is increased to 150 ℃, the reaction is maintained for 3 hours in a nitrogen atmosphere, and then the reaction is heated to 200 ℃ for 16 hours.
(2) 0.75g of PMAA is dissolved in DMAc, then 1.074g of alendronic acid (50 percent of the mol number of carboxyl groups) is added, and the mixture is reacted for 12 hours at 150 ℃ under the protection of nitrogen, and then the solvent is rotationally evaporated and dried to obtain the partially phosphonated PMAA.
(3) 4.00g of (1) HBPBI and (2) partially phosphonated PMAA in a total mass of 4.00g were dissolved in DMAc in a mass ratio of 1.3:1 to obtain a solution a. 2.337g of phosphonoacetic acid was dissolved in DMF to give a solution b. The rest is the same as in example 1.
(4) Same as in example 1.
The test shows that the ADL of the proton exchange membrane is 6.45, the proton conductivity is 0.0856S/cm, the proton conductivity is 0.0740S/cm after 10 times of deionized water immersion, and the proton conductivity retention rate is 86.5%.
Example 10
(1) The other operations are the same as those of example 7, except that: PPA 339g is added into a dry three-neck flask, the temperature is raised to 120 ℃, then DAB 4.82g and BTA 2.10g are simultaneously added according to the molar ratio of 2.25:1, the solid content accounts for 2.0 percent of the total solution, and the solid is fully dissolved after being stirred for 4 hours at the temperature. The temperature is increased to 150 ℃, the reaction is maintained for 3 hours in a nitrogen atmosphere, and then the reaction is heated to 200 ℃ for 12 hours.
(2) 1.05g of PMAA is dissolved in DMAc, then 0.902g of alendronic acid (30 percent of carboxyl mol) is added, and the mixture is reacted for 12 hours at 150 ℃ under the protection of nitrogen, and then the solvent is rotationally evaporated and dried to obtain the partially phosphonated PMAA.
(3) 3.84g of (1) HBPBI and (2) partially phosphonated PMAA in a total mass were dissolved in DMAc in a mass ratio of 1.03:1 to obtain a solution a. 3.227g of phosphonoacetic acid was dissolved in DMF to give a solution b. The rest is the same as in example 1.
(4) Same as in example 1.
The test shows that the ADL of the proton exchange membrane is 5.51, the proton conductivity is 0.0846S/cm, the proton conductivity is 0.0726S/cm after 10 times of deionized water immersion, and the proton conductivity retention rate is 85.8%.
Example 11
(1) The other operations are the same as those of example 7, except that: 241g of PPA was added to a dry three-necked flask, the temperature was raised to 120 ℃, then 5.36g of DAB and 2.10g of BTA were added simultaneously in a molar ratio of 2.5:1, the solid content was 3.0% of the total solution, and the mixture was stirred at this temperature for 4 hours to sufficiently dissolve the solid. The temperature is increased to 150 ℃, the reaction is maintained for 3 hours in a nitrogen atmosphere, and then the reaction is heated to 200 ℃ for 8 hours.
(2) 1.35g of PMAA is dissolved in DMAc, then 0.387g of alendronic acid (10 percent of the mol number of carboxyl) is added, and the mixture is reacted for 12 hours at 150 ℃ under the protection of nitrogen, and then the solvent is rotationally evaporated and dried to obtain the partially phosphonated PMAA.
(3) 3.36g of (1) HBPBI and (2) partially phosphonated PMAA in a total mass were dissolved in DMAc in a mass ratio of 0.97:1 to obtain a solution a. 3.925g of phosphonoacetic acid was dissolved in DMF to give a solution b. The rest is the same as in example 1.
(4) Same as in example 1.
The test shows that the ADL of the proton exchange membrane is 4.79, the proton conductivity is 0.0756S/cm, the proton conductivity is 0.0607S/cm after 10 times of deionized water immersion, and the retention rate of the proton conductivity is 80.3%.
Example 12
(1) The other operations are the same as those of example 7, except that: adding 194g of PPA into a dry three-neck flask, heating to 120 ℃, then simultaneously adding 6.00g of DAB and 2.10g of BTA according to the molar ratio of 2.8:1, wherein the solid content accounts for 4.0 percent of the total solution, and stirring for 4 hours at the temperature to fully dissolve the solid. The temperature is increased to 150 ℃, the reaction is maintained for 3 hours in a nitrogen atmosphere, and then the reaction is heated to 200 ℃ for 6 hours.
(2) 1.65g of PMAA is dissolved in DMAc, then 0.236g of alendronic acid (5 percent of the mole number of carboxyl groups) is added, and the mixture is reacted for 12 hours at 150 ℃ under the protection of nitrogen, and then the solvent is rotationally evaporated and dried to obtain the partially phosphonated PMAA.
(3) 3.20g of (1) HBPBI and (2) partially phosphonated PMAA in a total mass were dissolved in DMAc in a mass ratio of 0.7:1 to obtain a solution a. 5.122g of phosphonoacetic acid was dissolved in DMF to give a solution b. The rest is the same as in example 1.
(4) Same as in example 1.
The test shows that the ADL of the proton exchange membrane is 3.83, the proton conductivity is 0.0749S/cm, the proton conductivity is 0.0569S/cm after 10 times of deionized water immersion, and the proton conductivity retention rate is 76.0%.
Comparative example 1
3g of dry PBI were dissolved in DMAc (20% solids) and the solution was dried on a glass dish at 80 ℃ to give a membrane with a thickness of 50 μm. After being soaked in 85% phosphoric acid for 16h, the test shows that the ADL is 9.88, the proton conductivity is 0.0681S/cm, the proton conductivity is 0.0488S/cm after 10 times of soaking, and the conductivity retention rate is 71.7%.
Test example 1
Structural characterization of the graft copolymer
FIG. 1 is an infrared spectrum of polyacrylic acid (PAA), partially phosphonated polyacrylic acid (LPAA), hyperbranched polybenzimidazole (HBPBI), and phosphonated (polyacrylic acid-g-hyperbranched polybenzimidazole) (L (PAA-g-HBPBI)) in example 1. As shown in FIG. 1, the hyperbranched polybenzimidazole (HBPBI) in example 1 was at 1600cm-1，1480cm-1And 1449cm-1A peak at 3407cm appeared representing the imidazole ring-1The stronger one represents primary amine (-NH)2) Antisymmetric telescopic peak, which shows that HBPBI contains more primary amine groups and is consistent with the design; comparison of the IR spectra of partially phosphonated polyacrylic acid (LPAA) and PAA revealed that LPAA was 1693cm-1The peak at which C ═ O represents the carboxylic acid was markedly reduced and was 1658cm-1A small peak appears for carbonyl (C ═ O) representing the secondary amide; a stretching vibration peak, representing phosphonic acid P ═ O, appears at 1110, indicating successful phosphonation of PAA. The peak representing carboxyl in L (PAA-g-HBPBI) almost disappeared, while the peak representing carbonyl of secondary amide (C ═ O) was significantly enhanced, and the phosphonic acid P ═ O stretching shock peak was also significantly enhanced compared to LPAA, which all indicated successful grafting of polybenzimidazole onto polyacrylic acid to synthesize L (PAA-g-HBPBI) graft copolymer.
Test example 2
Measurement of proton conductivity
1. Determination of ADL
The polymer film prepared in the above example and the polymer film of the comparative example were respectively soaked in 85% phosphoric acid at 60 ℃ for 24 h; then, the membrane surface was taken out and acid-adsorbed by filter paper, and then dried, and the mass of the dry membrane before and after impregnation was measured, and the phosphoric Acid Doping Level (ADL) was calculated by the formula (1).
Figure BDA0002403267880000251
Wherein ADL is the acid doping level of the film, m1And m2Mass of dry film before and after phosphoric acid impregnation, MwRepeat unit molecular weight for polymer film samplesAnd 98 is the molecular weight of phosphoric acid.
2. Determination of proton conductivity
The polymer films prepared in the above examples and comparative examples were cut into 5cm × 5cm films, respectively, the resistances at different temperatures were measured by ac impedance using an electrochemical workstation, and then the proton conductivities of the films at different temperatures were calculated by equation (2):
Figure BDA0002403267880000252
wherein σ is proton conductivity (S/cm), t is thickness (cm) of the proton exchange membrane, R is in-plane resistance (Ω) perpendicular to the membrane surface, and S is effective membrane area (cm)2)。
The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiment. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. A graft copolymer is prepared by mixing and reacting an amino-containing hyperbranched benzimidazole polymer, a partially phosphonated olefin polymer with a side chain containing carboxyl and carboxyl-containing phosphonic acid.
2. The graft copolymer of claim 1, wherein the partially phosphonated olefin polymer has a degree of phosphonated extent of 1% to 99%;
preferably, the graft copolymer is a polymer obtained by a condensation reaction of a terminal amino group in an amino-containing hyperbranched benzimidazole polymer and a carboxyl group of a partially phosphonated olefin polymer with a carboxyl group at a side chain, wherein the amino-containing hyperbranched benzimidazole polymer is grafted to a main chain of the partially phosphonated olefin polymer with a carboxyl group at a side chain, and the polymer is a polyolefin-g-hyperbranched benzimidazole polymer with an amino group at a side chain; and then, further grafting phosphonic acid containing carboxyl on the polyolefin-g-hyperbranched benzimidazole polymer with the side chain containing amino to obtain the graft copolymer, which is marked as a phosphonated (polyolefin-g-hyperbranched benzimidazole polymer) graft copolymer.
3. The graft copolymer according to claim 1 or 2, wherein the graft copolymer contains a structural unit represented by the following formula (I):
Figure FDA0002403267870000011
in the formula (I), R' is selected from H and alkyl; r' is selected from the group consisting of absent, substituted or unsubstituted arylene, substituted or unsubstituted alkylene, wherein the substituents are selected from the group consisting of alkyl, carboxyl, halogen; r1Through a terminal amino group (-NH)2) Residues of amino-containing hyperbranched benzimidazole polymers grafted to the backbone of partially phosphonated olefin polymers after condensation reaction with-COOH on R'; r2A residue selected from amino-containing phosphonic acids; r3A residue selected from carboxyl-containing phosphonic acids; m is an integer between 100 and 50000;
when R' is absent, z is 0, 1 ≧ x >0, y1+ y2 is 1-x; when R' is arylene or alkylene, 1> z ≧ 0, 1 ≧ x >0, y1+ y2 ═ 1-z-x.
4. A process for preparing a graft copolymer as claimed in any of claims 1 to 3, which comprises the steps of:
(1) mixing olefin polymer with side chain containing carboxyl and phosphonic acid containing amino, and reacting to obtain partially phosphonated olefin polymer with side chain containing carboxyl;
(2) dissolving hyperbranched benzimidazole polymer containing amino, olefin polymer with partial phosphonic acid containing carboxyl on side chain and phosphonic acid containing carboxyl in an organic solvent, and reacting under heating to prepare the graft copolymer.
5. The production process according to claim 4, wherein in step (1), the amino group-containing phosphonic acid is selected from at least one of 4-amino-1-hydroxybutylidene-1, 1-diphosphonic acid (alendronic acid), 4-aminobutylphosphonic acid, 2-aminoethylphosphonic acid, 3-aminobutylphosphonic acid, 3-aminopropylphosphonic acid, (1-aminoethyl) phosphonic acid, (1-aminopropyl) phosphonic acid, (1-aminobutyl) phosphonic acid, 2-amino-5-phosphonovaleric acid, 5-aminopentylphosphonic acid, 4-aminopentylphosphonic acid, 3-aminopentylphosphonic acid, (4-aminophenyl) phosphonic acid, (3-aminophenyl) phosphonic acid, (2-aminophenyl) phosphonic acid; preferably, at least one selected from the group consisting of 4-amino-1-hydroxybutylidene-1, 1-diphosphonic acid (alendronic acid), 4-aminobutylphosphonic acid, 2-aminoethylphosphonic acid, 3-aminobutylphosphonic acid;
preferably, in the step (1), the molar ratio of the amino-containing phosphonic acid to the carboxyl functional groups in the olefin-based polymer with carboxyl groups at the side chains is 0.01-0.99: 1;
preferably, in the step (1), the temperature of the reaction is 100-150 ℃, and the time of the reaction is 6-24 h; the reaction is carried out under an inert atmosphere.
6. The production process according to claim 4 or 5, wherein, in the step (2), the carboxyl group-containing phosphonic acid is selected from phosphonoacetic acid, phosphonopropionic acid, phosphonobutyric acid, 5-phosphonovaleric acid, 6-phosphonohexanoic acid, 7-phosphonoheptanoic acid, 8-phosphonooctanoic acid, 9-phosphonononanoic acid, 10-phosphonodecanoic acid, 11-phosphonoundecanoic acid, 16-phosphonohexadecanoic acid, 3-phosphonopropionic acid, 4-phosphonobutyric acid, DL-2-amino-3-phosphonopropionic acid, DL-2-amino-4-phosphonobutyric acid, DL-2-amino-5-phosphonovaleric acid, DL-2-amino-6-phosphonohexanoic acid, L-2-amino-5-phosphonopropionic acid, L-2-amino-6-phosphonopropionic acid, L, At least one of DL-2-amino-7-phosphoheptanoic acid, 4-phosphobutyric acid, 2- (phosphomethyl) pentanedioic acid, 4-phosphorylbenzoic acid, 3-phosphorylbenzoic acid, and glyphosate;
preferably, in the step (2), the reaction is carried out under the protection of inert gas under the heating condition of 120-160 ℃; preferably, the reaction time is 6-24 h;
preferably, in the step (2), the mass ratio of the amino-containing hyperbranched benzimidazole polymer to the side chain carboxyl-containing partially phosphonated olefin polymer is 3-0.5: 1;
preferably, in the step (2), the addition amount of the phosphonic acid containing carboxyl is 0.15-0.86 times of the molar amount of the four amino compounds for preparing the amino-containing hyperbranched benzimidazole polymer.
7. A proton exchange membrane comprising the graft copolymer of any one of claims 1-3.
8. The proton exchange membrane according to claim 7, wherein the proton exchange membrane is further doped with phosphoric acid.
9. A process for the preparation of a proton exchange membrane according to claim 7 or 8, comprising the steps of:
(s1) mixing the olefin polymer having carboxyl in the side chain and phosphonic acid having amino group, and reacting to obtain partially phosphonated olefin polymer having carboxyl in the side chain;
dissolving amino-containing hyperbranched benzimidazole polymer, olefin polymer with partial phosphonic acid containing carboxyl on side chains and carboxyl-containing phosphonic acid in an organic solvent, and reacting under heating;
(s2) after the reaction is finished, pouring the solution into the surface of the base material for tape casting while the solution is hot, volatilizing the solvent at the temperature of 60-120 ℃, and obtaining a polymer film after the solvent is completely volatilized;
(s3) soaking the polymer membrane obtained in the step (s2) in a phosphoric acid solution, taking out and drying to obtain the phosphoric acid doped proton exchange membrane.
10. Use of the proton exchange membrane of claim 7 or 8 in a fuel cell or a flow battery.
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