Multi-branched polymer, preparation method thereof, anion exchange membrane and alkaline electrolysis device

Abstract

The embodiment of the invention relates to the technical field of polymer functional materials, and provides a multi-element branched polymer, a preparation method thereof, an anion exchange membrane and an alkaline electrolysis device. The multi-element branched polymer in the embodiment of the invention comprises a first chain segment, a second chain segment and a third chain segment, wherein a linking group is also arranged in the chain segment. The multi-element branched polymer in the embodiment of the invention is at least beneficial to improving the conductivity, the water absorption performance, the alkaline stability and the mechanical strength of the anion exchange membrane.

Description

TECHNICAL FIELD

[0001] The embodiments of the present application relate to the technical field of high polymer functional materials, in particular to a multi-branched polymer, a preparation method thereof, an anion exchange membrane and an alkaline electrolytic device. BACKGROUND

[0002] An anion exchange membrane (AEM) is one of the core components of an alkaline electrolytic device, which plays a role of conducting OH-, blocking gas and separating anode and cathode in the electrolytic device. Therefore, an excellent AEM needs to have high ionic conductivity, excellent dimensional stability, high mechanical strength and high alkaline stability.

[0003] However, the service life of the mainstream AEM in 60℃, 1mol / L KOH solution is usually several thousand hours, which is difficult to meet the commercial demand. Moreover, there is a "trade-off" effect between the ionic conductivity and the dimensional stability of the AEM, and both are difficult to be considered. SUMMARY

[0004] The embodiments of the present application provide a multi-branched polymer, a preparation method thereof, an anion exchange membrane and an alkaline electrolytic device, which are at least beneficial to improve the alkaline stability of the anion exchange membrane, and can also consider the ionic conductivity and the dimensional stability.

[0005] According to some embodiments of the present application, the embodiments of the present application provide a multi-branched polymer, which includes a first segment, a second segment and a third segment as shown below: The first segment includes: ; The second segment includes: ; The third segment includes: or at least one of the above; wherein Ar1 is a biphenyl group, and the number of benzene rings in the biphenyl group is 2-4; Ar2 is at least one of a fused ring aryl group or a fused heterocyclic group; Ar3 and Ar4 are both branched structures, and the connection site of Ar3 is three, and the connection site of Ar4 is four; the structure general formula of A is as shown below:

[0006] wherein R1 is a C1-C6 linear alkyl group.

[0007] In some embodiments of the present application, based on the amount of substance of the multi-branched polymer, the content of the amount of substance of the first segment is 60%-95%, the content of the amount of substance of the second segment is 1%-25%, and the content of the amount of substance of the third segment is 1%-25%.

[0008] In some embodiments of the present application, the content of the amount of substance of the first segment is 70% to 95%, the content of the amount of substance of the second segment is 1% to 15%, and the content of the amount of substance of the third segment is 1% to 15%, based on the amount of substance of the multi-branched polymer.

[0009] In some embodiments of the present application, the structural monomer corresponding to Ar1 includes at least one of the monomers shown as follows: .

[0010] In some embodiments of the present application, the fused ring aryl group includes at least one of a fluorene group substituted with a first substituent or unsubstituted, a naphthyl group substituted with a first substituent or unsubstituted, an anthracene group substituted with a first substituent or unsubstituted, or a phenanthrene group substituted with a first substituent or unsubstituted, the first substituent being at least one of an aromatic hydrocarbon and an alkyl group; and the fused heterocyclic group includes at least one of a carbazole group substituted with a second substituent or unsubstituted, a dibenzothiophene group substituted with a second substituent or unsubstituted, and a dibenzofuran group substituted with a second substituent or unsubstituted, the second substituent being at least one of an aryl group and an alkyl group.

[0011] In some embodiments of the present application, the structural monomer corresponding to the fused ring aryl group includes at least one of the monomers shown as follows: wherein R1 is a phenyl group or a C1-C6 alkyl group; The structural monomer corresponding to the fused heterocyclic group includes at least one of the monomers shown as follows: wherein R2 is a phenyl group or a C1-C6 alkyl group.

[0012] In some embodiments of the present application, the structural monomer corresponding to Ar3 includes at least one of the monomers shown as follows: ; The structural monomer corresponding to Ar4 includes at least one of the monomers shown as follows: .

[0013] In some embodiments of the present application, the weight average molecular weight of the multi-branched polymer is 10,000 g / mol to 600,000 g / mol.

[0014] In some embodiments of the present application, the polymer dispersity index of the multi-branched polymer is 1.1 to 3.2.

[0015] In some embodiments of the present application, the ion exchange capacity of the multi-branched polymer is 2.0 mmol / g to 3.0 mmol / g.

[0016] In some embodiments of the present application, the thermal degradation temperature of the multi-branched polymer is > 350℃.

[0017] The second aspect of the embodiments of the present application provides a preparation method of a multi-branched polymer, comprising the following steps: dissolving a polymer monomer and 3-quinuclidinone hydrochloride in an organic solvent, and then performing a Friedel-Crafts reaction under the condition of a Lewis acid to obtain an intermediate polymer, the polymer monomer comprising a first polymer monomer, a second polymer monomer and a third polymer monomer; subsequently, mixing and reacting the intermediate polymer, a haloalkane and an acid binding agent to obtain the multi-branched polymer; the first polymer monomer comprises biphenyl, and the number of benzene rings in the biphenyl is 2-4; the second polymer monomer is at least one of a fused ring group or an aromatic heterocyclic group, and the third polymer monomer is a branched structure, and the number of connection sites of the branched structure is 3 or 4; the content of the amount of substance of the first polymer monomer is 60%-95%, the content of the amount of substance of the second polymer monomer is 1%-25%, and the content of the amount of substance of the third polymer monomer is 1%-25%, based on the amount of substance of the polymer monomer; the haloalkane is R1X, wherein R1 is a linear alkyl group with 1-6 carbon atoms, and X is a halogen atom.

[0018] In some embodiments of the present application, the ratio of the total amount of substance of the polymer monomer to the amount of substance of 3-quinuclidinone hydrochloride is 1:1-1:1.5, and the ratio of the amount of substance of the haloalkane to the amount of substance of 3-quinuclidinone hydrochloride is 1:1-10:1.

[0019] In some embodiments of the present application, the ratio of the amount of substance of the multi-branched polymer to the amount of substance of the acid binding agent is 1:0.2-1:2.

[0020] The third aspect of the embodiments of the present application provides an anion exchange membrane comprising the multi-branched polymer described above or the multi-branched polymer prepared by the preparation method described above.

[0021] The fourth aspect of the embodiments of the present application provides an alkaline electrolytic device comprising an electrolytic cell, the electrolytic cell being provided with an anode and a cathode, and the anion exchange membrane described above being arranged between the anode and the cathode.

[0022] The technical solutions provided by the embodiments of the present application have at least the following advantages: In this embodiment, the branched structure in the third segment effectively increases the free volume of the multi-component branched polymer, thereby improving its water absorption and ionic conductivity. The fused-ring aryl and fused heterocyclic groups in the second segment have a large rigid planar structure, which can enhance the mechanical strength of the multi-component branched polymer. In the first segment, since the biphenyl group is connected by single bonds, the polymer groups can be guaranteed to have a certain degree of spatial flexibility, which can improve the flexibility of the multi-component branched polymer. Moreover, the quinine ring in the segment has excellent alkali stability, which can improve the alkali resistance of the multi-component branched polymer. Therefore, the multi-component branched polymer in this embodiment has good alkali stability, while also taking into account ionic conductivity and dimensional stability. Attached Figure Description

[0023] One or more embodiments are illustrated by way of example with corresponding pictures in the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Unless otherwise stated, the pictures in the accompanying drawings do not constitute a limitation on scale. In order to more clearly illustrate the technical solutions in the embodiments of this application or in the conventional technology, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 The proton NMR spectrum of the multi-branched polymer provided in Example 1 of this application; Figure 2 Infrared spectrum of the multi-branched polymer provided in Example 1 of this application; Figure 3 SEM image of the cross-section of the anion exchange membrane provided in Embodiment 1 of this application; Figure 4 A graph showing the change in conductivity of the anion exchange membrane provided in Example 1 of this application as a function of temperature; Figure 5 The water absorption performance test diagram of the multi-branched polymer provided in Example 1 of this application; Figure 6 The polarization curve of the electrolysis chamber provided in Embodiment 1 of this application. Detailed Implementation

[0025] As known from the background art, the current AEMs have insufficient alkaline stability, and it is difficult to balance the ion conductivity and dimensional stability. Specifically, the technical routes of traditional AEMs are mainly divided into polyalkane and polyaromatic. The polyalkane AEM main chain usually has PE (Polyethylene), PS (Polystyrene), PNB (Polynorbornene) and the like. For example, PS is prepared into AEM after chloromethylation and quaternization reaction, but this structure has poor mechanical properties due to the rigidity of PS, and water absorption swelling is difficult to control, and needs to be modified and regulated (such as European Patent EP2017184752, Chinese Patent CN116272397A, Japanese Patent JP2012512897); PE main chain can be used to synthesize AEM by olefin insertion polymerization, ring-opening metathesis polymerization and radiation grafting, but the types of cations that can be anchored are limited, and the alkaline stability is poor; PNB main chain is usually used to prepare AEM by metal-catalyzed olefin addition polymerization, but the synthesized AEM has the problems of poor mechanical strength and large water absorption swelling, and the alkaline stability can only be maintained for thousands of hours (such as CN117229451A). The polyaromatic AEM mainly refers to the AEM with a main chain mostly composed of benzene rings. This kind of material is easy to modify, but the intrinsic chemical stability of the heteroatom main chain is poor, and it is easy to degrade by chain breaking in alkaline medium, causing the performance of the membrane to deteriorate and failing to meet the long-term use requirements. For example, the AEM prepared by a polymer with a biphenyl-piperidine structure as the main chain has an alkaline stability of only thousands of hours, which cannot meet the long-time stable operation requirement of tens of thousands of hours. Although the AEM prepared by a polymer with a biphenyl-quinine structure as the main chain has high alkaline stability, its water absorption rate is not high, and the ion conductivity is general (such as CN119264352A, US12139580B2).

[0026] Based on this, the present application provides a multi-branched polymer, a preparation method thereof, an anion exchange membrane and an alkaline electrolytic device. In the multi-branched polymer of the present application, through the action of different chain segments and groups in the chain segments, the multi-branched polymer not only has good alkaline stability, but also can well balance the ion conductivity and dimensional stability. The anion exchange membrane prepared by using the multi-branched polymer in the embodiments of the present application also has the above-mentioned performance, and can be used in the alkaline electrolytic device to improve the use performance of the alkaline electrolytic device.

[0027] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise explicitly and specifically limited. Similarly, "multiple groups" means more than two groups (including two groups), and "multiple pieces" means more than two pieces (including two pieces). "M" refers to mol / L.

[0028] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the application. The appearance of the phrase in various places in the specification does not necessarily all refer to the same embodiment, nor is it necessarily independent or alternative embodiments to other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0029] In the description of the embodiments of the present application, the term "and / or" is only a description of the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B, which means that there are A, A and B, and B. In addition, the character " / " in this paper generally represents that the front and rear associated objects are a "or" relationship.

[0030] In the description of the embodiments of the present application, the technical terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the embodiments of the present application. For example, if the device or element in the drawing is inverted, the element described as "below" or "under" or "lower" or "bottom" of the other element or feature will be oriented "above" or "top" of the other element or feature. Therefore, the term "below" can cover both upward and downward orientations depending on the context in which the term is used, which will be apparent to those skilled in the art. The material can be oriented in other ways (e.g., rotated 90 degrees, inverted, flipped), and the spatial relative descriptions used herein can be interpreted accordingly.

[0031] In the description of the embodiments of the present application, unless specifically defined and limited, the terms "mount", "connected", "connection", "fixed", and the like should be understood broadly, for example, can be fixed connection, can also be detachable connection, or integral; can be mechanical connection, can also be electrical connection; can be direct connection, can also be indirect connection through an intermediate medium, can be internal communication of two elements or interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0032] In the description of the embodiments of the present application, "about", "approximately", "approximately" or "approximately" of a specific parameter value includes the value and the degree of deviation from the value that a person skilled in the art would understand within the acceptable tolerance of the specific parameter. For example, "about" or "approximately" of a value can include an additional value within 90.0% to 110.0% of the value, such as within 95.0% to 105.0% of the value, within 97.5% to 102.5% of the value, within 99.0% to 101.0% of the value, within 99.5% to 100.5% of the value, or within 99.9% to 100.1% of the value.

[0033] In the corresponding drawings of the embodiments of the present application, the thickness and area of the layers are exaggerated for better understanding and ease of description. In addition, when it is described that one component is "formed substantially" on another component, it means that the component is not formed on the entire surface (or front surface) of the other component, nor on a part of the edge of the entire surface.

[0034] In the description of the embodiments of the present application, when a certain component "includes" another component, unless otherwise specified, other components are not excluded, and other components can also be further included. The second component is formed or disposed above or on the first component, or is formed or disposed on the surface of the first component, or is formed or disposed on one side of the first component. It can include embodiments in which the first component and the second component are in direct contact, and can also include embodiments in which additional components can be between the first component and the second component, so that the first component and the second component can not be in direct contact. For the sake of simplicity and clarity, various components can be arbitrarily drawn in different proportions. In the drawings, some layers / components can be omitted for simplicity. Unless otherwise specified, the second component formed or disposed on the surface of the first component means that the first component is in direct contact with the second component. Among them, the above "component" can refer to layer, film, region, part, structure, etc.

[0035] The terminology used in the description of the various embodiments herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various embodiments and the appended claims, "component" is also intended to encompass a plurality of components, unless the context clearly dictates otherwise. In this regard, the components can include a layer, a film, a region, or a plate, among other components.

[0036] The embodiments of the present application will be described in detail with reference to the drawings. However, those skilled in the art can understand that, in the embodiments of the present application, many technical details are presented in order to make the reader better understand the present application. However, the technical solutions claimed by the present application can be implemented even without these technical details and based on various changes and modifications of the following embodiments.

[0037] In the embodiments of the present application, the multi-branched polymer comprises a first segment, a second segment and a third segment as shown below: The first segment comprises: ; The second segment comprises: ; The third segment comprises: or at least one of the following: wherein Ar1 is a biphenyl group, and the number of benzene rings in the biphenyl group is 2-4; Ar2 is at least one of a fused ring aryl group or a fused heterocyclic group; Ar3 and Ar4 are both branched structures, and the connection site of Ar3 is three, and the connection site of Ar4 is four; the general structure of A is as shown below:

[0038] wherein R1 is a C1-C6 linear alkyl group.

[0039] Based on the amount of substance of the multi-branched polymer, the content of the amount of substance of the first segment is 60%-95%, the content of the amount of substance of the second segment is 1%-25%, and the content of the amount of substance of the third segment is 1%-25%.

[0040] In the embodiments of the present application, the branched structure with 3 or 4 connection sites in the third segment can well increase the free volume of the multi-branched polymer, thereby being beneficial to improving the water absorption and ionic conductivity thereof; the fused ring aryl and the fused heterocyclic group in the second segment have a large rigid planar structure, which can improve the mechanical strength of the multi-branched polymer; in the first segment, since the biphenyl group is connected by a single bond, the macromolecular group has a certain spatial flexibility, which can improve the flexibility of the multi-branched polymer; and the linking group A has excellent alkali stability, which can improve the alkali resistance of the multi-branched polymer. Therefore, the multi-branched polymer in the embodiments of the present application has good conductivity, water absorption and swelling performance, mechanical strength and alkali stability, and the anion exchange membrane in the alkaline electrolytic device prepared by using the same also has corresponding performance. In addition, in some embodiments of the present application, by controlling the mass ratio of the amount of substance of the three segments, the mechanical stability and dimensional stability of the multi-branched polymer can be ensured to achieve the best balance; specifically, in some embodiments of the present application, based on the amount of substance of the multi-branched polymer, the content of the amount of substance of the first segment is 60% to 95%, the content of the amount of substance of the second segment is 1% to 25%, and the content of the amount of substance of the third segment is 1% to 25%; preferably, the content of the amount of substance of the first segment is 70% to 95%, the content of the amount of substance of the second segment is 1% to 15%, and the content of the amount of substance of the third segment is 1% to 15%.

[0041] It should be noted that the multi-branched polymer in the embodiments of the present application does not have any requirement for the connection order between the first segment, the second segment and the third segment, as long as the purpose of the present application can be met. For example, for two segments connected to each other, the same segment can be connected, or different segments can be connected, the first segment can be connected to the first segment, the first segment can be connected to the third segment, the first segment can be connected to the second segment, etc. This is because the reaction order is unnecessary during the polymerization process of the multi-branched polymer, and therefore the connection between the segments of the multi-branched polymer formed is also disordered.

[0042] In some embodiments of the present application, the fused ring aryl includes at least one of a fluorene group substituted with a first substituent or unsubstituted, a naphthyl group substituted with a first substituent or unsubstituted, an anthracene group substituted with a first substituent or unsubstituted, or a phenanthrene group substituted with a first substituent or unsubstituted, and the first substituent is at least one of an aryl group or an alkyl group; and / or, the fused heterocyclic group includes at least one of a carbazole substituted with a second substituent or unsubstituted, a dibenzothiophene substituted with a second substituent or unsubstituted, or a dibenzofuran substituted with a second substituent or unsubstituted, and the second substituent is at least one of an aryl group or an alkyl group.

[0043] For more convenient understanding, as an example, the present application provides the kind of monomer corresponding to Ar1 in the first segment, Ar2 in the second segment and Ar3 and Ar4 in the third segment, as follows: In the first segment, the structural monomer corresponding to Ar1 includes at least one of the monomers shown as follows: .

[0044] The structural monomer corresponding to the fused ring aryl group includes at least one of the monomers shown as follows: , wherein R1 is a phenyl group or a C1-C6 alkyl group.

[0045] The structural monomer corresponding to the fused heterocyclic group includes at least one of the monomers shown as follows: , , wherein R2 is a phenyl group or a C1-C6 alkyl group.

[0046] In the third segment, the structural monomer corresponding to Ar3 includes at least one of the monomers shown as follows: ; The structural monomer corresponding to Ar4 includes at least one of the monomers shown as follows: .

[0047] It should be noted that since the monomers are subsequently distributed in the form of structural units on the main chain of the multi-branched polymer, the connection sites in the monomers are usually the positions with the highest reactivity. Taking the biphenyl of formula I-2 as an example, the para position of biphenyl has the highest reactivity, and its structure on the multi-branched polymer is usually as follows: .

[0048] The above results are due to the different positioning effects of the substituents in the monomers during the preparation of the multi-branched polymer, which needs to be determined according to the actual situation of the monomers. The related content is also explained in the preparation method provided later in the present application. However, the difference in connection sites caused by the positioning effect does not easily have a significant impact on the performance of the multi-branched polymer, so the present application does not have a particular limitation on the connection sites in the monomers.

[0049] In addition, it should be noted that the N atom in the multi-branched polymer carries a unit of positive charge, so the N atom will be connected to anions in the form of ionic bonds. Usually, OH - , Br - , Cl - , HCO3 -The solution of the anion activates the polybranched polymer, so that the nitrogen atom of the polybranched polymer usually carries a corresponding activated anion in actual use. When the polybranched polymer is prepared, the N atom of the polybranched polymer also carries an anion, the type of which is related to the raw material used in preparation, which can be seen from the subsequent content.

[0050] In some embodiments of the present application, the weight average molecular weight of the polybranched polymer is generally between 10000 g / mol and 600000 g / mol, and a suitable molecular weight can ensure the processability of the polymer, and at the same time, can also ensure that the prepared anion exchange membrane has good mechanical properties; specifically, the weight average molecular weight can be 10000 g / mol, 30000 g / mol, 100000 g / mol, 200000 g / mol, 300000 g / mol, 400000 g / mol, 500000 g / mol, 600000 g / mol, or in the range consisting of any two of the above values. In addition, in some embodiments of the present application, the PDI (Polydispersity Index, polymer dispersity index) of the polybranched polymer is generally between 1.1 and 3.2, so that the performance of the polybranched polymer can be ensured to be relatively stable.

[0051] The polybranched polymer in the embodiments of the present application generally has good ion exchange capacity (IEC, Ion-Exchange Capacity) and thermal degradation temperature. Specifically, in some embodiments of the present application, the IEC of the polybranched polymer is 2.0-3.0 mmol / g, and the thermal degradation temperature is >350℃.

[0052] The embodiments of the present application also provide a preparation method of the polybranched polymer, which can specifically include the following steps: S100, performing a Friedel-Crafts reaction to obtain an intermediate polymer.

[0053] This step is to dissolve the polymer monomer and 3-quinuclidinone hydrochloride in an organic solvent, and then perform a Friedel-Crafts reaction under the condition of a Lewis acid to obtain a polybranched polymer. In this step, the polymer monomer includes a first polymer monomer, a second polymer monomer and a third polymer monomer, which respectively correspond to Ar1 in the first chain segment, Ar2 in the second chain segment and Ar3 and Ar4 in the third chain segment in the polybranched polymer described above in the present application, and 3-quinuclidinone hydrochloride corresponds to the A group in the chain segment. Therefore, in this step, the first polymer monomer includes biphenyl, and the number of benzene rings in the biphenyl is 2-4; the second polymer monomer is at least one of a fused ring group or an aromatic heterocyclic group, and the third polymer monomer is a branched structure, and the connection site of the branched structure is three or four.

[0054] In the preparation method provided in the embodiments of the present application, the use amounts of the first polymerization monomer, the second polymerization monomer and the third polymerization monomer correspond to the amounts of the first chain segment, the second chain segment and the third chain segment of the multi-branched polymer; specifically, in some embodiments of the present application, the content of the amount of substance of the first polymerization monomer is 60% to 95%, the content of the amount of substance of the second polymerization monomer is 1% to 25%, and the content of the amount of substance of the third polymerization monomer is 1% to 25%, based on the amount of substance of the polymerization monomers; preferably, the content of the amount of substance of the first chain segment is 70% to 95%, the content of the amount of substance of the second chain segment is 1% to 15%, and the content of the amount of substance of the third chain segment is 1% to 15%.

[0055] It should be noted that the Friedel-Crafts reaction in this step is a short name of Friedel-Crafts ation, under the condition of super acid, quinuclidone hydrochloride will lose hydrochloric acid and undergo super electrophilic activation to form a dicationic super electrophilic reagent to react with benzene to undergo linear or branched polymerization according to the number of reaction sites of the benzene ring on the polymerization monomer, in order to ensure complete reaction of the monomer, quinuclidone hydrochloride is usually used in excess, and the total amount of substance ratio of quinuclidone hydrochloride to the polymerization monomers is 1.1:1 to 1.5:1, and the connecting structure between the two polymerization monomers is as follows:

[0056] In addition, during the reaction, the above-mentioned groups may be connected to specific positions of the polymerization monomers according to the specific types of the polymerization monomers. The present application does not have special limitations in this regard, as long as the purpose of the present application can be met.

[0057] In addition, in order to optimize the reaction process and the molecular configuration of the multi-branched polymer, quinuclidone hydrochloride and the first polymerization monomer and the second polymerization monomer can be mixed and reacted first, and the reaction time is controlled to be between 8h and 24h, and then the third polymerization monomer is added to the reaction system. This method can more effectively change the high molecular chain configuration of the multi-branched polymer, and reduce the disorder of the reaction, make the branching sites more uniform, achieve the purpose of optimizing the molecular weight distribution of the product and improving the overall performance.

[0058] Since the present step is polymerized by the Friedel-Crafts reaction, in the step, the reaction conditions need to be controlled to meet the conditions of the Friedel-Crafts reaction. For example, in the present step, a Lewis acid is generally used as a catalyst to catalyze the reaction, which can be at least one of inorganic acids such as AlCl3, FeCl3, SnCl4, BF3, TiCl4, ZnCl2, and organic acids such as trifluoroacetic acid, triflic acid, acetic acid, and methylsulfonic acid, and the present application is not particularly limited thereto. As an exemplary embodiment, in the present application, trifluoroacetic acid and triflic acid are used as the Lewis acid to catalyze the reaction.

[0059] In addition, the present step also needs to be carried out in a dry environment, so the organic solvent in the present step is generally subjected to drying treatment. The present step is not particularly limited in the selection of the organic solvent, as long as the Friedel-Crafts reaction can proceed normally. As an exemplary embodiment, in the present application, dichloromethane (DCM) is used as the organic solvent in the present step.

[0060] In addition, in order to avoid excessive reaction, in the present application, the present step is generally controlled to be reacted at -25°C to 25°C, and the reaction time is controlled to be 3h to 75h.

[0061] S200, mixing and reacting the intermediate polymer, the halogenated alkane, and the acid binding agent to obtain a multi-branched polymer; the halogenated alkane is R1X, wherein R is a linear alkyl group with 1 to 6 carbon atoms, and X is a halogen atom.

[0062] In some embodiments of the present application, in order to accelerate the reaction rate and reduce the reaction difficulty, X is generally an iodine atom, that is, an iodoalkane is used for the reaction. At this time, in the multi-branched polymer obtained, the atom connected to the N atom is I - .

[0063] In the present step, in the intermediate polymer obtained in the S100 step, the H atom connected to the N atom in the linking group between the polymerized monomers is replaced by the R1 group in the halogenated alkane to form the following structure:

[0064] At this time, the above-mentioned multi-branched polymer can be formed.

[0065] The present step is generally carried out in a solvent, and the solvent of the present step generally includes at least one of N-methylpyrrolidone (NMP), N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO). As an exemplary embodiment, in the present application, NMP is used as the reaction solvent.

[0066] In addition, the acid-binding agent in this step is a reagent used to absorb or neutralize acidic byproducts, ensuring that the substitution reaction can proceed normally. This application does not have any particular limitation on the type of acid-binding agent; it can be at least one of sodium bicarbonate, sodium carbonate, potassium bicarbonate, potassium carbonate, calcium carbonate, calcium hydroxide, sodium hydroxide, and potassium hydroxide. In this step, the molar ratio of the multi-branched polymer to the acid-binding agent is generally 1:0.2 to 1:2.

[0067] Furthermore, this step does not have specific temperature requirements, as long as the reaction can proceed. For example, the reaction temperature in this step can be 25℃~80℃, and the reaction time can be controlled between 12h and 48h.

[0068] This application also provides an anion exchange membrane, which can be prepared using the multi-branched polymer described in this application. The resulting anion exchange membrane has good electrical conductivity, water absorption, alkalinity stability, and mechanical strength.

[0069] This application does not impose any particular restrictions on the preparation method of the anion exchange membrane, as long as it meets the purpose of this application. As an example, in the embodiments of this application, a multi-branched polymer is dissolved in DMSO to prepare a slurry with a viscosity of 1000 mPa·s to 5000 mPa·s, and then the anion exchange membrane is obtained by casting.

[0070] This application also provides an alkaline electrolysis device, including an electrolysis chamber, in which an anode, an anode diffusion layer, a cathode, and a cathode diffusion layer are disposed, and the aforementioned anion exchange membrane is disposed between the anode and the cathode.

[0071] The technical solution of this application will be described in detail below with reference to the embodiments.

[0072] Test methods and equipment Polymer basic performance testing The weight-average molecular weight and PDI of the polymer to be tested were determined using GPC (Gel Permeation Chromatography) with NMP as the mobile phase and 40°C as the temperature.

[0073] Ion exchange capacity test The ion exchange capacity (IEC) of anion exchange membranes is determined by titration. Details are as follows: Before testing, the membrane to be tested was subjected to ion exchange with 1.0 M NaBr solution at room temperature for 24 hours, repeated three times to ensure complete ion exchange. - Exchange for Br - The sample was dried overnight in a vacuum oven at 80°C, and its weight was recorded (denoted as W). dry). Then, the sample was ion exchanged with 0.2M NaNO3 solution at room temperature for 24 hours, repeated three times to completely replace Br - . The solution produced in the exchange process was collected and titrated using a 0.01M AgNO3 standard solution, with K2CrO4 as an indicator, and the volume of AgNO3 consumed was recorded as V AgNO3 . The IEC (mmol g - ) of the anion exchange membrane in the form of Br - and OH -1 can be calculated by the following formula:

[0074]

[0075] Thermal degradation temperature test The thermal degradation temperature of the tested polymer was tested by Thermogravimetric Analysis (TG or TGA) with a heating rate of 10℃ / min and a test range of 30℃~800℃.

[0076] Nuclear magnetic resonance hydrogen spectrum test The nuclear magnetic resonance hydrogen spectrum (H-NMR) of the tested polymer was tested by a 500M nuclear magnetic resonance instrument, and the deuterated reagent was selected as DMSO-d6. The H-NMR of the multi-branched polymer in Example 1 is shown in Figure 1 .

[0077] Infrared test The infrared spectrum of the film was tested by using an infrared spectrometer in ATR mode. The infrared spectrum of Example 1 is shown in Figure 2 .

[0078] Conductivity test According to GB T 20042.3—2022, the conductivity test was carried out by EIS (Electrochemical Impedance Spectroscopy), the film sample with a size of 5mm×5mm was assembled into a double electrode cell, and AC impedance was used for testing in the frequency range of 1Hz to 0.1MHz. Assembly and measurement were carried out under N2 atmosphere to avoid CO2 pollution. The measurement was carried out at different temperatures under the condition of 100% relative humidity. The ionic conductivity σ (mS·cm -1 ) of the film sample can be calculated by the following formula:

[0079] where d is the thickness of the membrane, S is the contact area between the electrode and the membrane, and R is the ohmic resistance obtained from electrochemical impedance spectroscopy.

[0080] Water uptake and swelling ratio test The water uptake and swelling ratio of the membrane were measured by comparing the weight and linear dimension change between wet and dry states. The length or thickness of the dry membrane in the form of a film was recorded as L - . dry The length (L dry ) or thickness (T wet ) of the film was then recorded. wet After the film was activated by soaking in 1 M KOH solution for 24 h, it was placed in deaerated deionized water under nitrogen protection and soaked at different temperatures for 4 h. After removing the excess water on the surface, the wet weight (W wet ) and length (L wet ) or thickness (T wet ) of the sample were recorded. Finally, after drying the film sample at 80 °C for 24 h, the dry weight (W dry ) of the film sample was recorded. The water uptake (WU) and swelling ratio (SR) can be calculated by the following formulas:

[0081]

[0082] Alkali resistance test After the film was activated by soaking in 1 M KOH solution for 24 h, the initial conductivity was tested, and then the 1 M KOH solution was maintained at 80 °C. The conductivity was tested at regular intervals and the alkali solution was replaced. The results were recorded and compared with the initial conductivity. In this application, the conductivity retention rate (in %) after 2000 h was used as the test result.

[0083] Mechanical strength test According to GB T 20042.3--2022, the thickness of the sample was measured under constant temperature and humidity conditions of 23 °C ± 2 °C and 50% ± 5% relative humidity. The thickness and width of each sample should be measured at 3 points within the gauge length, and the average value was taken. The thickness measurement accuracy was ± 0.2%, and the width measurement accuracy was ± 0.5%.

[0084] The test was performed using a universal testing machine. The sample was placed in the test fixture, with the longitudinal axis of the sample coinciding with the center line of the upper and lower fixtures, and clamped.

[0085] Test speed: When determining the tensile strength and elongation at break, different tensile speeds can be used, selected within the range of 50 mm / min to 200 mm / min. For each tensile speed, a separate sample should be used. When determining the elastic modulus, the test speed should be selected so that the strain rate is close to 1% gauge length per minute.

[0086] After the sample is broken, the corresponding tensile strength and elongation at break are read. If the sample breaks at a position outside the mark, the test is invalid.

[0087] Polarization curve test The membrane is assembled in a 5x5 cm electrolysis cell, and the anode and cathode are selected as commercial electrodes. The polarization curve is tested at 60°C and 1M KOH, with a scanning range of 1.4V~2V and a scanning rate of 5mV / s. The electrolysis performance of the anion exchange membrane is determined by the polarization curve.

[0088] Morphology test The morphology of the cross section of the anion exchange membrane is tested using a scanning electron microscope (SEM), and the cross-sectional SEM image of the anion exchange membrane in Example 1 is shown in Figure 3 .

[0089] Example 1 Preparation of a multi-branched polymer 90mmol of the first polymer monomer p-terphenyl, 10mmol of the second polymer monomer fluorene, 10mmol of the third polymer monomer triphenylbenzene, and 140mmol of 3-quinuclidinone hydrochloride are dissolved in 200mL of dichloromethane, followed by the addition of 30mL of trifluoroacetic acid, 250mL of trifluoromethanesulfonic acid, and reaction under ice bath conditions for 24h to obtain an intermediate polymer. The intermediate polymer is then precipitated, washed with KOH to remove the remaining acid, and dried.

[0090] 100mmol of the dried intermediate polymer is weighed and dissolved in 100mL of NMP, 25mmol of Na2CO3 and 150mmol of iodomethane are added, stirred and reacted at 40°C for 36h to obtain a multi-branched polymer with the following general structure:

[0091] Preparation of an anion exchange membrane 20g of the multi-branched polymer is dissolved in 50mL of DMSO to form a slurry with a viscosity of 4000mPa·s, which is then scraped onto a glass plate using a doctor blade. After drying at 80°C, an anion exchange membrane is obtained.

[0092] Example 2 Except that the amount of 3-quinuclidinone hydrochloride is adjusted to 120mmol, the rest is basically the same as Example 1.

[0093] Example 3 Except that the amount of triphenylbenzene is adjusted to 15mmol, the rest is basically the same as Example 1.

[0094] Example 4 Except that the same amount of iodine ethane is used instead of iodine methane, the rest is basically the same as example 1. The structural general formula of the multi-branched polymer obtained in this example is as follows:

[0095] Example 5 Except that the multi-branched polymer is prepared in the following way, the rest is basically the same as example 1.

[0096] <Preparation of multi-branched polymer> 90 mmol of the first polymerization monomer p-terphenyl, 10 mmol of the second polymerization monomer dibenzofuran, 10 mmol of the third polymerization monomer triphenylbenzene, and 140 mmol of 3-quinuclidinone hydrochloride are dissolved in 200 mL of dichloromethane, followed by the addition of 30 mL of trifluoroacetic acid, 250 mL of trifluoromethanesulfonic acid, and reaction at 10°C for 36 h to obtain an intermediate polymer, followed by precipitation of the intermediate polymer, washing of the remaining acid with KOH, and drying.

[0097] 100 mmol of the dried intermediate polymer is weighed and dissolved in 100 mL of NMP, 25 mmol of Na2CO3, and 150 mmol of iodine methane are added, stirred, and reacted at 10°C for 36 h to obtain a multi-branched polymer with the following structural general formula:

[0098] Example 6 Except that the same amount of triphenylene is used instead of triphenylbenzene, the rest is basically the same as example 1. The structural general formula of the multi-branched polymer obtained in this example is as follows:

[0099] Example 7 Except that the same amount of triphenylmethane is used instead of triphenylbenzene, the rest is basically the same as example 1. The structural general formula of the multi-branched polymer obtained in this example is as follows:

[0100] Example 8 Except that the same amount of diphenylmethane is used instead of triphenylbenzene, the rest is basically the same as example 1. The structural general formula of the multi-branched polymer obtained in this example is as follows:

[0101] Example 9 Except that the same amount of quaterphenyl is used instead of triphenylbenzene, the rest is basically the same as example 1. The structural general formula of the multi-branched polymer obtained in this example is as follows:

[0102] Example 10 Except that the polybranched polymer is prepared in the following manner, the rest is substantially the same as Example 1.

[0103] <Preparation of polybranched polymer> 90 mmol of the first polymerization monomer p-terphenyl, 10 mmol of the second polymerization monomer dibenzothiophene, 10 mmol of the third polymerization monomer triphenylbenzene, and 140 mmol of 3-quinuclidinone hydrochloride are dissolved in 200 mL of dichloromethane, followed by the addition of 30 mL of trifluoroacetic acid, 250 mL of trifluoromethanesulfonic acid, and reaction at 40°C for 48 h to obtain an intermediate polymer, followed by precipitation of the intermediate polymer, washing of the remaining acid with KOH, and drying.

[0104] 100 mmol of the dried intermediate polymer is weighed and dissolved in 100 mL of NMP, 25 mmol of Na2CO3, and 150 mmol of iodomethane are added, stirred, and reacted at 40°C for 36 h to obtain a polybranched polymer having the following general structure:

[0105] Example 11 Except that the same amount of iodopropyl is used instead of iodomethane, the rest is substantially the same as Example 8. The polybranched polymer obtained in this example has the following general structure:

[0106] Example 12 Except that the amount of 3-quinuclidinone hydrochloride is adjusted to 120 mmol, the rest is substantially the same as Example 10.

[0107] Comparative Example 1 Except that the polybranched polymer is prepared in the following manner, the rest is substantially the same as Example 1.

[0108] <Preparation of polybranched polymer> 90 mmol of the first polymerization monomer p-terphenyl, 10 mmol of the second polymerization monomer dibenzothiophene, 10 mmol of the third polymerization monomer triphenylbenzene, and 140 mmol of 3-quinuclidinone hydrochloride are dissolved in 200 mL of dichloromethane, followed by the addition of 30 mL of trifluoroacetic acid, 250 mL of trifluoromethanesulfonic acid, and reaction at 40°C for 48 h to obtain an intermediate polymer, followed by precipitation of the intermediate polymer, washing of the remaining acid with KOH, and drying.

[0109] Comparative Example 2 The rest is basically the same as Example 1 except that the polymer is prepared in the following manner.

[0110] <Preparation of the multi-branched polymer> 100 mmol of the first polymerization monomer p-terphenyl, 10 mmol of the third polymerization monomer triphenylbenzene, 140 mmol of 3-quinuclidinone hydrochloride were dissolved in 200 mL of dichloromethane, followed by adding 30 mL of trifluoroacetic acid, 250 mL of trifluoromethanesulfonic acid, and reacting for 24 h under ice bath conditions to obtain an intermediate polymer, followed by precipitating the intermediate polymer, washing the remaining acid with KOH, and drying.

[0111] 100 mmol of the dried intermediate polymer was weighed and dissolved in 100 mL of NMP, 25 mmol of Na2CO3, 150 mmol of iodomethane were added, stirred, and reacted for 36 h at 40°C to obtain a multi-branched polymer having the following general structure:

[0112] Comparative Example 3 The rest is basically the same as Example 1 except that the polymer is prepared in the following manner.

[0113] <Preparation of the polymer> 100 mmol of the first polymerization monomer p-terphenyl, 10 mmol of the second polymerization monomer fluorene, 140 mmol of 3-quinuclidinone hydrochloride were dissolved in 200 mL of dichloromethane, followed by adding 30 mL of trifluoroacetic acid, 250 mL of trifluoromethanesulfonic acid, and reacting for 24 h under ice bath conditions to obtain a multi-branched polymer, followed by precipitating the multi-branched polymer, washing the remaining acid with KOH, and drying.

[0114] 100 mmol of the dried intermediate polymer was weighed and dissolved in 100 mL of NMP, 25 mmol of Na2CO3, 150 mmol of iodomethane were added, stirred, and reacted for 36 h at 40°C to obtain a polymer having the following general structure:

[0115] The test results of each of the examples and comparative examples are shown in Table 1. Table 1

[0116] From the above, the multi-branched polymer in the embodiments of the present application has good alkali resistance, and also has good ionic conductivity and dimensional stability. In particular, from the contents of Comparative Example 1 and Example 1, it can be seen that the quinuclidine ring cation structure has excellent alkali stability compared to the piperidine ring, and can make the multi-branched polymer and the anion exchange membrane have excellent alkali stability. Moreover, the inventors have also set up other structures (not shown in the present application) such as imidazole ring instead of the quinuclidine ring cation structure, and found that the quinuclidine ring cation structure has the best alkali stability. From Example 1 and Comparative Example 2, it can be seen that if the second polymerization monomer is not set, the mechanical properties of the multi-branched polymer will be reduced, indicating that the second segment can well enhance the mechanical strength of the multi-branched polymer; from Example 1 and Comparative Example 3, it can be seen that if the third polymerization monomer is not set, the water absorption and ionic conductivity of the multi-branched polymer will be reduced, indicating that the branching effect of the third segment can well enhance the water absorption and ionic conductivity of the multi-branched polymer. In addition, the inventors have also found that if other polymerization monomers are used instead of the first polymerization monomer in the embodiments of the present application, the mechanical properties of the multi-branched polymer will also be reduced, because the biphenyl structure in the first segment can well improve the flexibility of the multi-branched polymer, and thus the mechanical properties of the multi-branched polymer can also be well improved. Moreover, from the SEM images of Figure 3 it can be seen that the anion exchange membrane in the embodiments of the present application is dense, uniform and pore-free, which can effectively prevent the hydrogen and oxygen crossover between the anode and the cathode, and meet the electrolysis use requirements.

[0117] It can be understood by those skilled in the art that the above embodiments are specific embodiments for implementing the present application, and in actual application, various changes can be made in form and details without departing from the spirit and scope of the present application. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application, and therefore the protection scope of the present application should be limited by the scope defined in the claims.

Claims

1. A multi-branched polymer, characterized in that, The multi-branched polymer comprises the following first segment, second segment, and third segment: The first chain segment includes: ; The second segment includes: ; The third segment includes: or At least one of them; Wherein Ar1 is a biphenyl group, and the number of benzene rings in the biphenyl group is 2 to 4; Ar2 is at least one of a fused-ring aryl group or a fused heterocyclic group; Ar3 and Ar4 are both branched structures, and Ar3 has three connection sites and Ar4 has four connection sites. The general structural formula of A is shown below: R1 is a C1~C6 straight-chain alkyl group.

2. The multi-branched polymer according to claim 1, characterized in that, Based on the amount of the multi-branched polymer, the amount of the first segment is 60% to 95%, the amount of the second segment is 1% to 25%, and the amount of the third segment is 1% to 25%.

3. The multi-branched polymer according to claim 2, characterized in that, Based on the amount of the multi-branched polymer, the amount of the first segment is 70% to 95%, the amount of the second segment is 1% to 15%, and the amount of the third segment is 1% to 15%.

4. The multi-branched polymer according to claim 1, characterized in that, Ar1 corresponds to at least one of the following structural monomers: 。 5. The multi-branched polymer according to claim 1, characterized in that, The fused-ring aryl group includes at least one of the following: a fluorenyl group substituted with a first substituent or unsubstituted; a naphthyl group substituted with a first substituent or unsubstituted; an anthracel group substituted with a first substituent or unsubstituted; or a phenanthryl group substituted with a first substituent or unsubstituted, wherein the first substituent is at least one aryl or alkyl group; and / or, The fused heterocyclic group includes at least one of carbazole (substituted or unsubstituted with a second substituent), dibenzothiophene (substituted or unsubstituted with a second substituent), and dibenzofuran (substituted or unsubstituted with a second substituent), wherein the second substituent is at least one of aryl or alkyl.

6. The multi-branched polymer according to claim 5, characterized in that, The structural monomer corresponding to the fused-ring aryl group includes at least one of the following monomers: R1 is a phenyl or a C1-C6 alkyl group; The structural monomer corresponding to the fused heterocyclic group includes at least one of the following monomers: ， R2 is a phenyl or a C1-C6 alkyl group.

7. The multi-branched polymer according to claim 1, characterized in that, Ar3 corresponds to at least one of the following monomers: ； Ar4 corresponds to at least one of the following monomers: 。 8. The multi-branched polymer according to claim 1, characterized in that, The weight-average molecular weight of the multi-branched polymer is 10,000 g / mol to 600,000 g / mol.

9. The multi-branched polymer according to claim 1, characterized in that, The polymer dispersibility index of the multi-branched polymer is 1.1 to 3.

2.

10. The multi-branched polymer according to claim 1, characterized in that, The ion exchange capacity of the multi-branched polymer is 2.0 mmol / g to 3.0 mmol / g.

11. The multi-branched polymer according to claim 1, characterized in that, The thermal degradation temperature of the multi-branched polymer is >350℃.

12. A method for preparing a multi-branched polymer, characterized in that, Includes the following steps: The polymeric monomers and 3-quinine cycloketone hydrochloride were dissolved in an organic solvent and then subjected to a Friedel-Crafts reaction under Lewis acid conditions to obtain an intermediate polymer. The polymeric monomers included a first polymeric monomer, a second polymeric monomer, and a third polymeric monomer. Subsequently, the intermediate polymer, a haloalkane, and an acid-binding agent were mixed and reacted to obtain a multi-branched polymer. The first polymerizable monomer includes biphenyl, and the number of benzene rings in the biphenyl is 2 to 4; the second polymerizable monomer is at least one of a fused ring group or an aromatic heterocyclic group; the third polymerizable monomer has a branched structure, and the branched structure has 3 or 4 connection sites. Based on the amount of the polymerizable monomers, the amount of the first polymerizable monomer is 60% to 95%, the amount of the second polymerizable monomer is 1% to 25%, and the amount of the third polymerizable monomer is 1% to 25%. The haloalkane is R1X, where R1 is a C1~C6 straight-chain alkyl group and X is a halogen atom.

13. The method for preparing the multi-branched polymer according to claim 12, characterized in that, The ratio of the total amount of the polymerized monomers to the amount of 3-quinine cycloketone hydrochloride is 1:1 to 1:1.5, and the ratio of the amount of the haloalkane to the amount of 3-quinine cycloketone hydrochloride is 1:1 to 10:

1.

14. The method for preparing the multi-branched polymer according to claim 12, characterized in that, The molar ratio of the multi-branched polymer to the acid-binding agent is 1:0.2 to 1:

2.

15. An anion exchange membrane, characterized in that, Includes the multi-branched polymer according to any one of claims 1 to 11, or the multi-branched polymer prepared by the method of the preparation of the multi-branched polymer according to any one of claims 12 to 14.

16. An alkaline electrolysis apparatus, characterized in that, It includes an electrolysis chamber, wherein an anode and a cathode are disposed within the electrolysis chamber, and an anion exchange membrane as described in claim 15 is disposed between the anode and the cathode.

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