Ultrahigh molecular weight alkaline polymer electrolyte and preparation method thereof

Abstract

The invention provides an ultra-high molecular weight alkaline polymer electrolyte and a preparation method thereof, and belongs to the technical field of alkaline polymer electrolytes. A small amount of polymeric monomers with multiple reaction sites and high reaction activity are introduced in the polymerization reaction process by adopting a collaborative slow polycondensation method, and the alkaline polymer is prepared by controlling the reaction temperature, the feeding mode, the nodes of monomer addition, the nodes of reaction completion and the like. And further carrying out nucleophilic substitution modification to prepare the ultra-high molecular weight alkaline polymer electrolyte. The ultra-high molecular weight alkaline polymer electrolyte has a'multilevel structure 'similar to a protein folding structure, and further has excellent mechanical properties and processing capacity, so that the ultra-high molecular weight alkaline polymer electrolyte has good application and development prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of alkaline polymer electrolytes, and particularly relates to an ultra-high molecular weight alkaline polymer electrolyte and a preparation method thereof. Background Art

[0002] Energy conversion devices with solid polymer electrolytes (such as fuel cells, electrolyzers, etc.) have high thermodynamic efficiency, can directly achieve efficient conversion between clean energy and substances, and at the same time effectively avoid energy depletion and environmental pollution problems caused by energy development and use. The development and application of alkaline polymer electrolytes is an important part of the development and use of solid polymer electrolyte energy conversion devices, and plays an important role in conducting ions and separating electrode reactions in the devices. Therefore, alkaline polymer electrolytes should have good conductivity and low gas permeability. To achieve the purpose of tight assembly of devices, they should also have high mechanical strength, low water absorption and swelling, etc.

[0003] To improve the mechanical strength of alkaline polymer electrolytes and reduce their water absorption and swelling, the strategy of adding crosslinking agents is mainly adopted. Through chemical interactions between functional groups to form chemical bonds or intermolecular forces (such as hydrogen bonds, van der Waals forces), the originally linear polymer molecules are modified into crosslinked polymers with chemical crosslinking networks or physical crosslinking networks, effectively improving the cohesion between molecules and reducing the movement ability of polymer segments and the whole molecule, so as to achieve the purpose of improving the mechanical strength of polymer electrolyte materials and reducing water absorption and swelling. However, crosslinked polymers, especially chemically crosslinked ones, are difficult to melt or dissolve due to the existence of crosslinking networks, which limits the processing and application capabilities of polymers.

[0004] At present, the method for preparing alkaline polymer electrolytes in the prior art is generally as follows: linear structure aromatic monomers, N-methyl-4-piperidone and highly active aromatic monomers are added to organic reagents, and then superacid is added to catalyze the polymerization reaction (for example, patents CN117843933A, CN118307753A, etc.). In this process, since highly active aromatic monomers with multiple active sites have higher reactivity, they often react with N-methyl-4-piperidone before linear structure aromatic monomers. This process will lead to two results: 1) The high-activity aromatic monomers react too quickly, resulting in an increased probability of intramolecular ring formation, especially when the molar proportion of the highly active aromatic monomers exceeds 1% of the total amount of aromatic monomers, the molecular chains form severe cross-linking, resulting in increased difficulty in subsequent modification processing and application; at the same time, the faster reaction of the highly active aromatic monomers will also result in more short side chains in the molecular structure of the obtained polymer, affecting the entanglement of the polymer, resulting in a serious decrease in solution viscosity and decreased film-forming properties. 2) Since the highly active aromatic monomer has multiple active sites, its reaction rate is much higher than that of the linear aromatic monomer, resulting in the highly active aromatic monomer completing the polycondensation conversion at the early stage of the addition of the superacid to the reaction system. The reaction has serious reverse reactions and side reactions. Therefore, in the process of continuing to add superacid, the degradation process of the oligomers produced by the polymerization of the highly active aromatic monomer and N-methyl-4-piperidone, the irreversible side reaction process, and the polymerization process of the linear aromatic monomer and N-methyl-4-piperidone and oligomers will occur simultaneously, resulting in unfavorable results such as complex reaction process, difficult reaction control, non-uniform reaction products, and unstable properties of the polymerization products. In the actual operation process, it can be observed that when the superacid is first added, the reaction in the system is violent, the temperature rises sharply, and even obvious boiling and large granular solids appear locally. The viscosity of the system increases significantly within a certain period of time. After further addition of superacid, the viscosity in the reaction system decreases significantly, and the final product is a lumpy gel substance. During the entire reaction process, a good pole climbing phenomenon cannot be formed; at the same time, the obtained product cannot be effectively dissolved in any organic reagent, and can only swell in some organic reagents, showing the solubility properties of cross-linked polymers. The polymer electrolyte obtained by further quaternization reaction cannot be used due to solubility problems. In addition, the anion exchange membrane obtained by solution casting will show an obvious inhomogeneous structure, which seriously affects its air tightness and mechanical strength. Summary of the invention

[0005] In view of the above deficiencies of the prior art, the present invention provides a super high molecular weight alkaline polymer electrolyte and a preparation method thereof. By adopting a cooperative slow polycondensation method, a small amount of polymer monomers with multiple reaction sites and high reaction activity are introduced during the polymerization process to achieve a significant increase in the molecular weight of the alkaline polymer. Through further nucleophilic substitution modification, a super high molecular weight alkaline polymer electrolyte with excellent mechanical properties and processing properties is prepared.

[0006] To achieve the above object, the specific technical solution of the present invention is as follows:

[0007] A preparation method of a super high molecular weight alkaline polymer electrolyte, comprising the following steps:

[0008] Step 1: Polymerization reaction process

[0009] Mix the linear aryl monomer, the super electrophilic monomer and the solvent evenly, then add the super strong acid in a low-temperature environment and continuously stir; when the viscosity of the mixture in the system increases significantly, add the highly active aryl monomer (branched monomer) dissolved in the solvent to the system for reaction; after adding the highly active aryl monomer, the viscosity of the mixture in the system will further increase. When the viscosity of the mixture in the system reaches the maximum, add the mixture to an alkaline solution at room temperature to terminate the reaction, and obtain a super high molecular weight alkaline polymer;

[0010] Step 2: Nucleophilic substitution modification process

[0011] React the alkaline polymer with an organic amine or a halogenated hydrocarbon to obtain a super high molecular weight alkaline polymer electrolyte.

[0012] In the polymerization reaction process of the present invention, after the linear aryl monomer, the super electrophilic monomer and the solvent are mixed evenly, the system presents a suspension / solution state at this time, and the viscosity of the mixture in the system is small, 0.4~1.5 mPa·s; after adding the super strong acid to the system, the viscosity of the system gradually increases. When the viscosity increase of the mixture in the system reaches 500~2000 mPa·s, an obvious sol appears and a shear thinning phenomenon occurs, and then the highly active aryl monomer dissolved in the solvent can be added to the system for reaction; after adding the highly active aryl monomer, the reaction time is 0.5~5 h. After adding the highly active aryl monomer, due to the depolymerization reaction, the viscosity of the mixture in the system shows a trend of first increasing and then decreasing. The present invention selects when the viscosity of the mixture in the system reaches the maximum, that is, when the mixture in the system produces an obvious rod climbing phenomenon at a rotation speed of 40~50 rpm, and the rod climbing phenomenon persists after stopping stirring for 10 seconds. At this time, it can be judged that the reaction is completed. After the reaction is completed, the substances in the reaction system should be taken out in time and placed in an alkaline solution to terminate the reaction and avoid the occurrence of multiple side reactions.

[0013] In the polymerization process, the present invention adopts a synergistic slow polycondensation method to introduce a small amount of polymer monomers with multiple reaction sites and high reactivity, and controls the reaction temperature, feeding method, monomer addition node and reaction end node, etc., to achieve a substantial increase in the molecular weight of the alkaline polymer electrolyte. The ultra-high molecular weight alkaline polymer electrolyte prepared by the present invention has a folding structure (multi-level structure) similar to that of protein, and has excellent mechanical properties and processing capabilities. Specifically, the present invention first places a linear aromatic monomer, a super-electrophilic monomer and part of the solvent in a suitable container in a certain proportion, then adds a super acid for catalysis under a low temperature environment, and uses a mechanical stirrer to mix the substances in the system evenly. After the super acid is mixed into the system for a period of time, when the viscosity of the system increases significantly, a highly active aromatic monomer dissolved in an organic solvent is added dropwise. After the highly active aromatic monomer is added, the viscosity in the system will be further increased. When the viscosity in the system reaches the maximum, the viscous substance in the reaction system is placed in an alkaline solution at room temperature to stop the reaction to obtain a solid polymer; and further, an ultra-high molecular weight alkaline polymer electrolyte is prepared by nucleophilic substitution modification. The method of collaborative slow polycondensation in the present invention can avoid the presence of more short branches in the polymer structure. The polymerization process is a step-by-step polymerization. Before adding the highly active aromatic monomer, the system has a certain viscosity, proving that some monomers in the system have been converted into linear polymers with a certain chain length structure; after adding the highly active aromatic monomer, the highly active aromatic monomer will link the linear polymer on the basis of the linear polymer to form a branched polymer with a long branched polymer. This long branched branched polymer will not affect the entanglement of the polymer, and due to the presence of branching nodes, the movement resistance of the entire molecular chain will be greatly improved (i.e., entanglement between molecular chains makes it difficult to relative slip), resulting in a significant improvement in the mechanical strength and solution viscosity of the final polymer. In addition, when adding a highly active aromatic monomer, the linear polymer molecular chain in the system has a certain length, and the end group has a reduced reactivity due to the chain embedding effect, which reduces the probability that both ends of the molecular chain react with the highly active aromatic monomer at the same time, and effectively avoids intramolecular cyclization.

[0014] Furthermore, the molar ratio of the linear aromatic monomer, the highly active aromatic monomer, and the super electrophilic monomer is (90-99): (10-1): (150-100).

[0015] Furthermore, the molar volume ratio of the linear aromatic monomer to the solvent (including the solvent for dissolving the linear aromatic monomer, the super-electrophilic monomer and the solvent for dissolving the highly active aromatic monomer) is (90-99): (0.2-0.6) mol / L.

[0016] Furthermore, the molar volume ratio of the linear aromatic monomer to the superacid is (90-99) : (0.8-1.2) mol / L.

[0017] Further, the linear aryl monomer is selected from one or more of the following compounds:

[0018] (a) ;

[0019] (b) ;

[0020] (c) , where R is H, NH2, OH or a halogen (including F, Cl, Br or I);

[0021] (d) ;

[0022] (e) ;

[0023] (f) ;

[0024] (g) , where n = 0, 1, 2, 3…8;

[0025] (h) , where R is CH2, NH, O or S;

[0026] (i) , where R is an aliphatic hydrocarbon substituent and its derivatives, a halogenated hydrocarbon substituent or an unsaturated hydrocarbon group and its derivatives;

[0027] (j) , where R is an aliphatic hydrocarbon substituent and its derivatives, a halogenated hydrocarbon substituent or an unsaturated hydrocarbon group and its derivatives;

[0028] (k) derivatives of the compounds listed in a-j.

[0029] Further, the super electrophilic monomer is selected from one or more of the following compounds:

[0030] (a) , where R is H, an aliphatic hydrocarbon substituent and its derivatives or an unsaturated hydrocarbon group and its derivatives;

[0031] (b) , where R is H, an aliphatic hydrocarbon substituent and its derivatives or an unsaturated hydrocarbon group and its derivatives;

[0032] (c) ;

[0033] (d) ;

[0034] (e) , where n = 0, 1, 2, 3... 8, and R is an aliphatic hydrocarbon substituent and its derivatives, a halogenated hydrocarbon substituent, or an unsaturated hydrocarbon group and its derivatives;

[0035] (f) derivatives of the compounds listed in a - e.

[0036] Further, the highly active aryl monomer is selected from one or more of the following compounds:

[0037] (a) ;

[0038] (b) ;

[0039] (c) ;

[0040] (d) ;

[0041] (e) ;

[0042] (f) ;

[0043] (g) ;

[0044] (h) ;

[0045] (i) ;

[0046] (k) derivatives of the compounds listed in a - i.

[0047] Further, the solvent includes but is not limited to at least one of dichloromethane, chloroform, carbon tetrachloride, dichloroethane, acetonitrile, and tetrahydrofuran.

[0048] Further, the superacid includes but is not limited to at least one of trifluoroacetic acid, trifluoromethanesulfonic acid, fluorosulfonic acid, and chlorosulfonic acid.

[0049] Further, the basic solution includes but is not limited to an aqueous solution or an organic solvent suspension of an alkali metal hydroxide, an alkali metal carbonate, or an alkali metal bicarbonate; wherein, the alkali metal hydroxide includes but is not limited to KOH, NaOH, and LiOH; the alkali metal carbonate includes but is not limited to K2CO3 and Na2CO3; the bicarbonate includes but is not limited to KHCO3 and NaHCO3.

[0050] Further, the amount of the solvent mixed with the linear aryl monomer and the super - electrophilic monomer is two - thirds of the total solvent amount, and the amount of the solvent for the highly active aryl monomer is one - third of the total solvent amount.

[0051] Further, the temperature of the low-temperature environment is -20~20 °C.

[0052] Still further, the temperature of the low-temperature environment is 0~4 °C.

[0053] Further, the polymerization reaction process is carried out under mechanical stirring. The rotation speed of the stirring is controlled above 100 rpm at the initial stage of the reaction to fully mix the materials. As the reaction proceeds, the rotation speed is controlled to gradually decrease, and when the reaction stops, the rotation speed is controlled at 40~50 rpm.

[0054] Further, the high-activity aryl monomer is added dropwise.

[0055] Further, the organic amine includes but is not limited to trimethylamine and / or triethylamine.

[0056] Further, the halogenated hydrocarbon includes but is not limited to at least one of monohalogenated and dihalogenated alkanes of C 1-10 For example, the halogenated hydrocarbon can be at least one of methyl iodide, methyl bromide, ethyl iodide, ethyl bromide, 1,6-dibromohexane, 1,5-dibromopentane.

[0057] Further, in the nucleophilic substitution modification process, when the main chain of the polymer obtained in step 1 has a halogenated hydrocarbon side group, the nucleophilic substitution modification steps are as follows: dissolving the polymer obtained in step 1 in an organic solvent, and then adding an organic amine for reaction; after the reaction is completed, adding the reaction solution to a precipitant for precipitation to obtain a basic polymer electrolyte;

[0058] When the main chain of the polymer obtained in step 1 has an amino functional group, the nucleophilic substitution modification steps are as follows: dissolving the polymer obtained in step 1 in an organic solvent, and then adding a halogenated hydrocarbon for reaction; after the reaction is completed, adding the reaction solution to a precipitant for precipitation to obtain a basic polymer electrolyte.

[0059] Further, the mass-volume ratio g / mL of the polymer obtained in step 1 to the organic solvent is 1:(5~30).

[0060] Further, the organic solvent includes but is not limited to at least one of dimethyl sulfoxide, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, tetrahydrofuran, 1,4-dioxane, toluene.

[0061] Further, the molar ratio of the organic amine to the halogenated side group in the polymer is (0.5~10):1.

[0062] Further, the molar ratio of the halogenated hydrocarbon to the amino functional group in the polymer is (0.3~5):1.

[0063] Further, the precipitant includes but is not limited to the following solutions:

[0064] (a) Aqueous solutions of alkali metal hydroxides (including KOH, NaOH, LiOH) and organic suspensions, aqueous solutions of alkali metal carbonates (including K2CO3, Na2CO3) and their organic solvent suspensions, aqueous solutions of alkali metal bicarbonates (including KHCO3, NaHCO3) and their organic solvent suspensions; (b) Diethyl ether; (c) Ethyl acetate; (d) Dichloromethane; (e) Chloroform; (f) Mixtures of various proportions of a - e.

[0065] The present invention also provides a ultra - high molecular weight alkaline polymer electrolyte prepared by the described method.

[0066] The present invention also provides the application of the ultra - high molecular weight alkaline polymer electrolyte in an alkaline polyelectrolyte fuel cell.

[0067] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0068] The present invention adopts a method of synergistic slow polycondensation. By controlling the reaction temperature, feeding mode, nodes of monomer addition, and the node of reaction end, etc., a small amount (molar ratio not exceeding 10% of the total amount of aromatic monomers) of aromatic monomers with multiple reaction sites and high reactivity are introduced during the polymerization process to achieve a substantial increase in the molecular weight of the alkaline polymer electrolyte. The ultra - high molecular weight alkaline polymer electrolyte prepared by the present invention has a "multi - level structure" similar to that of proteins and excellent mechanical properties and processing properties, making it have good application and development prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0069] Figure 1 Figures showing the results of dissolving the alkaline polymer electrolytes of Example 5 and Comparative Example 1 in DMSO respectively, with a concentration of 20 mg / mL;

[0070] Figure 2 Intrinsic viscosities of alkaline polymer electrolytes with different contents of highly active aryl monomers;

[0071] Figure 3 Films prepared by using the alkaline polymer electrolytes of Example 5 and Comparative Example 1 respectively;

[0072] Figure 4 Mechanical properties of films prepared by using alkaline polymer electrolytes with different contents of highly active aryl monomers;

[0073] Figure 5 Molecular weights and degrees of polymerization of alkaline polymer electrolytes with different contents of highly active aryl monomers;

[0074] Figure 6The second virial coefficient and the mean square radius of gyration of alkaline polymer electrolytes with different high-active aryl monomer contents;

[0075] Figure 7 The ionic conductivity of alkaline polymer electrolytes with different high-active aryl monomer contents;

[0076] Figure 8 The water diffusion coefficient of alkaline polymer electrolytes with different high-active aryl monomer contents;

[0077] Figure 9 The linear swelling ratio of alkaline polymer electrolytes with different high-active aryl monomer contents. Specific embodiments

[0078] The technical solution of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work fall within the protection scope of the present invention.

[0079] A preparation method of an ultra-high molecular weight alkaline polymer electrolyte includes the following steps:

[0080] Step 1: Polymerization reaction process

[0081] Mix the linear aryl monomer, the super-electrophilic monomer and the solvent evenly, and then add the super-strong acid in a low-temperature environment and stir continuously; when the viscosity of the mixture in the system rises significantly, add the high-active aryl monomer (branched monomer) dissolved in the solvent to the system for further reaction; after the addition of the high-active aryl monomer, the viscosity of the mixture in the system will further increase. When the viscosity of the mixture in the system reaches the maximum, add the mixture to the alkaline solution at room temperature to terminate the reaction, and obtain an ultra-high molecular weight alkaline polymer;

[0082] Step 2: Nucleophilic substitution modification process

[0083] React the alkaline polymer with an organic amine or a halogenated hydrocarbon to obtain an ultra-high molecular weight alkaline polymer electrolyte.

[0084] In some examples, the molar ratio of the linear aryl monomer, the high-active aryl monomer, and the super-electrophilic monomer is (90~99):(10~1):(150~100). The molar volume ratio mol / L of the linear aryl monomer to the solvent (including the solvent for dissolving the linear aryl monomer, the super-electrophilic monomer and the solvent for dissolving the high-active aryl monomer) is (90~99):(0.2 - 0.6). The molar volume ratio mol / L of the linear aryl monomer to the super-strong acid is (90~99):(0.8 - 1.2).

[0085] In some examples, the linear aryl monomer is selected from one or more of the following compounds:

[0086] (a) ; (b) ; (c) , where R is H, NH2, OH or a halogen (including F, Cl, Br or I); (d) ; (e) ; (f) ; (g) , where n = 0, 1, 2, 3…8;

[0087] (h) , where R is CH2, NH, O or S; (i) , where R is an aliphatic hydrocarbon substituent and its derivatives, a halogenated hydrocarbon substituent or an unsaturated hydrocarbon group and its derivatives; (j) , where R is an aliphatic hydrocarbon substituent and its derivatives, a halogenated hydrocarbon substituent or an unsaturated hydrocarbon group and its derivatives; (k) derivatives of the compounds listed in a-j. The super-electrophilic monomer is selected from one or more of the following compounds: (a) , where R is H, an aliphatic hydrocarbon substituent and its derivatives or an unsaturated hydrocarbon group and its derivatives; (b) , where R is H, an aliphatic hydrocarbon substituent and its derivatives or an unsaturated hydrocarbon group and its derivatives; (c) ; (d) ; (e) , where n = 0, 1, 2, 3…8, and R is an aliphatic hydrocarbon substituent and its derivatives, a halogenated hydrocarbon substituent or an unsaturated hydrocarbon group and its derivatives; (f) derivatives of the compounds listed in a-e. The highly active aryl monomer is selected from one or more of the following compounds: (a) ; (b) ; (c) ; (d) ; (e) ;

[0088] (f) ; (g) ; (h) ; (i) ; (k) derivatives of the compounds listed in a-i. The solvents include, but are not limited to, at least one of dichloromethane, chloroform, carbon tetrachloride, dichloroethane, acetonitrile, and tetrahydrofuran. The superacids include, but are not limited to, at least one of trifluoroacetic acid, trifluoromethanesulfonic acid, fluorosulfonic acid, and chlorosulfonic acid. The basic solution includes, but is not limited to, an aqueous solution or an organic solvent suspension of an alkali metal hydroxide, an alkali metal carbonate, or an alkali metal bicarbonate; wherein, the alkali metal hydroxides include, but are not limited to, KOH, NaOH, and LiOH; the alkali metal carbonates include, but are not limited to, K2CO3 and Na2CO3; the bicarbonates include, but are not limited to, KHCO3 and NaHCO3.

[0089] In some examples, the temperature of the low-temperature environment is -20 to 20 °C.

[0090] In some examples, the organic amine includes, but is not limited to, trimethylamine and / or triethylamine. The halogenated hydrocarbon includes, but is not limited to, at least one of monohalogenated and dihalogenated alkanes of C 1-10 and at least one of the above, for example, the halogenated hydrocarbon can be at least one of methyl iodide, methyl bromide, ethyl iodide, ethyl bromide, 1,6-dibromohexane, and 1,5-dibromopentane.

[0091] In some examples, during the nucleophilic substitution modification process, when the main chain of the polymer obtained in step 1 has a halogenated hydrocarbon side group, the nucleophilic substitution modification steps are as follows: dissolving the polymer obtained in step 1 in an organic solvent, and then adding an organic amine for reaction; after the reaction is completed, adding the reaction solution to a precipitant for precipitation to obtain a basic polymer electrolyte; when the main chain of the polymer obtained in step 1 has an amino functional group, the nucleophilic substitution modification steps are as follows: dissolving the polymer obtained in step 1 in an organic solvent, and then adding a halogenated hydrocarbon for reaction; after the reaction is completed, adding the reaction solution to a precipitant for precipitation to obtain a basic polymer electrolyte.

[0092] In some examples, the mass-volume ratio of the polymer obtained in step 1 to the organic solvent is 1:(5 - 30) g / mL. The organic solvent includes, but is not limited to, at least one of dimethyl sulfoxide, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, tetrahydrofuran, 1,4-dioxane, and toluene. The molar ratio of the organic amine to the halogenated side group in the polymer is (0.5 - 10):1. The molar ratio of the halogenated hydrocarbon to the amino functional group in the polymer is (0.3 - 5):1. The precipitating agent includes, but is not limited to, the following solutions: (a) aqueous solutions of alkali metal hydroxides (including KOH, NaOH, LiOH) and organic suspensions, aqueous solutions of alkali metal carbonates (including K2CO3, Na2CO3) and their organic solvent suspensions, aqueous solutions of alkali metal bicarbonates (including KHCO3, NaHCO3) and their organic solvent suspensions; (b) diethyl ether; (c) ethyl acetate; (d) dichloromethane; (e) chloroform; (f) mixtures of various proportions of a - e.

[0093] In the following specific examples, unless otherwise specified, the raw materials and reagents used are obtained by regular purchase.

[0094] Example 1

[0095] A super high molecular weight alkaline polymer electrolyte

[0096] Add 4.6 g of p-terphenyl, 2.54 mL of methylpiperidone, and 14 mL of dichloromethane into a 50 mL flask. Then place the flask in an ice-water mixture and add mechanical stirring. After the system temperature stabilizes, drip 30 mL of trifluoromethanesulfonic acid into the system and continue stirring. After adding trifluoromethanesulfonic acid, when the viscosity of the mixture in the system significantly increases in about 1 h, drip 7 mL of dichloromethane solution containing 0.02 g of tetraphenylethylene into the system. Then react for another 1 h, and the viscosity of the mixture in the system further significantly increases. During this period, the rotational speed of the mechanical stirring is reduced several times until a significant rod climbing phenomenon appears in the system at a low rotational speed (40 rpm), and the rod climbing phenomenon lasts for more than 10 seconds after stopping the stirring. At this time, take out the viscous substance in the system in time and soak it in a 500 mL aqueous solution of 1 M K2CO3. After half an hour, crush the solid-liquid mixture with a blender and wash it with water until the pH of the upper clear liquid is neutral. Dry the solid and weigh it for standby. Dissolve the above solid in a 100 mL mixed solution of 1-methyl-2-pyrrolidone and dimethyl sulfoxide with a volume ratio of 1:1. Then add 5 mL of iodomethane and place the system in a light-shielded environment to react for 24 h. Then add the dark reaction solution into ethyl acetate to obtain a solid precipitate. After further filtration, washing, ion exchange, and drying, a super high molecular weight alkaline polymer electrolyte is obtained.

[0097] Example 2

[0098] A super high molecular weight alkaline polymer electrolyte

[0099] Add 3.1 g of biphenyl, 3.7 g of 3 - quinuclidinone hydrochloride and 10 mL of dichloromethane into a 50 mL flask. Then place the flask in an ice - water mixture and add mechanical stirring. After the system temperature stabilizes, drop 30 mL of trifluoromethanesulfonic acid into the system and continue stirring. When the viscosity of the mixture in the system significantly increases about 5 h after adding trifluoromethanesulfonic acid, drop 5 mL of dichloromethane solution containing 0.26 g of fluorene into the system. Then react for another 3 h, and the viscosity of the mixture in the system further increases. During this period, the rotation speed of the mechanical stirrer is adjusted downwards several times until a significant rod - climbing phenomenon appears at a low rotation speed (40 rpm) in the system, and the rod - climbing phenomenon persists for more than 10 s after stopping the stirring. At this time, take out the viscous substance in the system in time and soak it in 500 mL of an aqueous solution of K2CO3 with a concentration of 1 M. After half an hour, crush the solid - liquid mixture with a blender, wash it with water until the pH of the upper clear liquid is neutral, dry the solid and weigh it for standby. Dissolve the above solid in a 100 mL mixed solution of 1 - methyl - 2 - pyrrolidone and dimethyl sulfoxide with a volume ratio of 1:1. Then add 4.7 mL of methyl iodide, and place the system in a light - proof environment to react for 24 h. Then add the dark reaction solution into ether to obtain a solid precipitate. After further suction filtration, washing, ion exchange and drying, a super high molecular weight alkaline polymer electrolyte is obtained.

[0100] Example 3

[0101] A super high molecular weight alkaline polymer electrolyte

[0102] Add 3.7 g of dibenzothiophene, 2.54 mL of N-methylpiperidone and 5 mL of dichloromethane into a 50 mL flask. Subsequently, place the flask in an ice-water mixture and add mechanical stirring. After the temperature of the system stabilizes, add 30 mL of trifluoromethanesulfonic acid dropwise into the system and continue stirring. When the viscosity of the mixture in the system significantly increases about 2 h after adding trifluoromethanesulfonic acid, add a dichloromethane solution containing 0.13 g of 9,9-diphenylfluorene dropwise into the system. Then react for another 3 h, and the viscosity of the mixture in the system further increases. During this period, reduce the rotational speed of the mechanical stirrer several times until a significant rod-climbing phenomenon appears in the system at a low rotational speed (40 rpm), and the rod-climbing phenomenon persists for more than 10 s after stopping the stirring. At this time, take out the viscous substance in the system in time and soak it in 500 mL of an aqueous solution of K2CO3 with a concentration of 1 M. After half an hour, crush the solid-liquid mixture with a blender and wash it with water until the pH of the upper clear liquid is neutral. Dry the solid and weigh it for standby. Dissolve the above solid in a mixed solution of 100 mL of 1-methyl-2-pyrrolidone and dimethyl sulfoxide with a volume ratio of 1:1. Then add 4.53 mL of methyl iodide and place the system in a light-shielded environment to react for 24 h. Subsequently, add the dark reaction solution into ethyl acetate to obtain a solid precipitate. After further suction filtration, washing, ion exchange and drying, a ultra-high molecular weight alkaline polymer electrolyte is obtained.

[0103] Example 4

[0104] An ultra-high molecular weight alkaline polymer electrolyte

[0105] Add 3.1 g of biphenyl, 3.7 g of 3 - quinuclidinone hydrochloride and 10 mL of dichloromethane into a 50 mL flask. Subsequently, place the flask in an ice - water mixture and add mechanical stirring. After the system temperature stabilizes, drip 30 mL of trifluoromethanesulfonic acid into the system and continue stirring. After adding trifluoromethanesulfonic acid, when the viscosity of the mixture in the system significantly increases in about 6 h, drip 5 mL of a dichloromethane solution containing 0.26 g of fluorene into the system. Then react for another 2 h. The viscosity of the mixture in the system further increases. During this period, reduce the mechanical stirring speed several times until a significant rod - climbing phenomenon appears in the system at a low speed (40 rpm), and the rod - climbing phenomenon persists for more than 10 s after stopping the stirring. At this time, promptly take out the viscous substance in the system and soak it in 500 mL of an aqueous solution of 1 M K2CO3. After half an hour, crush the solid - liquid mixture with a blender and wash it with water until the pH of the upper clear liquid is neutral. Dry the solid and weigh it for standby. Dissolve the above - mentioned solid in a 100 mL mixed solution of 1 - methyl - 2 - pyrrolidone and dimethyl sulfoxide with a volume ratio of 1:1. Then add 4.7 mL of iodomethane and place the system in a light - proof environment to react for 24 h. Subsequently, add the dark reaction solution into diethyl ether to obtain a solid precipitate. After further suction filtration, washing, ion exchange, and drying, a super - high - molecular - weight alkaline polymer electrolyte is obtained.

[0106] Example 5

[0107] A super - high - molecular - weight alkaline polymer electrolyte

[0108] Add 2.29 g of p-terphenyl, 1.24 g of 4-methylpiperidone and 10 mL of dichloromethane into a 50 mL flask. Then place the flask in an ice-water mixture and add mechanical stirring. After the system temperature stabilizes, drop 10 mL of trifluoromethanesulfonic acid into the system and continue stirring. After adding trifluoromethanesulfonic acid, when the viscosity of the mixture in the system significantly increases in about 2 h, drop 5 mL of dichloromethane solution containing 7.9 mg of 9,9-spirobifluorene into the system. Then react for another 2 h, and the viscosity of the mixture in the system further increases. During this period, reduce the mechanical stirring speed several times until obvious rod climbing phenomenon appears in the system at a low speed (40 rpm), and the rod climbing phenomenon lasts for more than 10 s after stopping stirring. At this time, take out the viscous substance in the system in time and soak it in 500 mL of 1 M K2CO3 aqueous solution. After half an hour, crush the solid-liquid mixture with a blender, wash it with water until the pH of the upper clear liquid is neutral, and dry the solid and weigh it for standby. Dissolve the above solid in a 50 mL mixed solution of 1-methyl-2-pyrrolidone and dimethyl sulfoxide with a volume ratio of 1:1. Then add 1.5 mL of methyl iodide, and place the system in a light-proof environment to react for 24 h. Then drop the dark reaction solution into ether to obtain a solid precipitate, and after further filtration, washing, ion exchange, and drying, obtain an ultra-high molecular weight alkaline polymer electrolyte.

[0109] Using the same method as described in Example 5, adjust the dosages of the linear aryl monomer (terphenyl) and the highly active aryl monomer (9,9-spirobifluorene) during the polymerization reaction (wherein, the molar ratios of the highly active aryl monomer in the total amount of aryl monomers are 0%, 0.25%, 0.5%, 1.0%, 1.5%, 2.0% respectively) to obtain a series of alkaline polymer electrolytes with different molecular weights.

[0110] Dissolve this series of polymer electrolytes in DMSO to prepare a polymer solution with a certain concentration (see Figure 1 ), and as can be seen from Figure 1 , the ultra-high molecular weight alkaline polymer electrolyte prepared by the present invention can be completely dissolved in DMSO, clear and transparent, without insoluble impurities. Use an Ubbelohde viscometer to test the intrinsic viscosity of the polymer solution, and the results are as shown in Figure 2 . It can be seen from Figure 2 that as the proportion of the highly reactive aryl monomer increases, the intrinsic viscosity of the obtained polymer solution gradually increases, proving that the introduction of the highly active aryl monomer can indeed achieve the purpose of significantly increasing the molecular weight.

[0111] Filter the polymer solution through a 600-mesh filter cloth to obtain a homogeneous solution, and then cast it on a glass plate and leave it overnight in an 80 °C environment to obtain a homogeneous high-strength polymer film (see Figure 3). Further, the mechanical properties of this series of thin films were tested, and the results are as Figure 4 shown.

[0112] To prove the improvement of the method provided by the present invention on molecular weight and molecular conformation, the present invention carried out dynamic and static light scattering tests on the polymer solution, and the results are as Figure 5 and Figure 6 shown. The results show that with the introduction of the branched monomer, the molecular weight and molecular size (radius of gyration) of the obtained polymer electrolyte have been significantly improved. Among them, with the increase of the molecular weight, the interaction between the polymer electrolyte and the solvent decreases, and the second virial coefficient will decrease significantly, but its value reaches equilibrium after the content of the branched monomer is 1.5%. Combining the above data, it can be explained that the linear long chains are connected into branched polymers with long branched chains under the action of the branched structure. After increasing the proportion of the branched monomer, additional branched structures are further formed on the periphery of the original branched long-chain molecules, resulting in an exponential increase in the entire branched molecular weight and a linear increase in the molecular size; after further increasing the amount of the branched monomer in the reaction, due to molecular entanglement addition polymerization leading to end-group embedding, limited number of single linear long chains resulting in decreased reaction, reversibility of the reaction, etc., the molecular size of the branched polymer will reach the maximum critical size. At this time, the unreacted additional branched monomers will further link multiple branched molecular clusters together to form larger molecular aggregates. The basic monomers of this kind of molecular aggregate interacting with the solvent are still single molecular clusters, so its second virial coefficient will tend to be stable. At this time, this kind of molecular aggregate not only has the improvement of the short-range structure and long-range structure of a single polymer, but also causes a significant change in the aggregation state of the polymer. This change is similar to introducing a folded structure (multi-level structure) similar to that in proteins into the polymer, resulting in a greater change in the properties of the finally formed polymer. For example, for the important properties of ion exchange membranes, ionic conductivity and transmembrane water diffusion coefficient, the proportion of end groups in this kind of molecular aggregate is severely reduced, resulting in a denser interior of the molecular cluster and an increase in the ionic concentration within the molecule, which is beneficial to ionic conduction, and the ionic conductivity will gradually increase with the increase of the branched monomer content (see Figure 7 ). At the same time, due to the too large size of this kind of molecular aggregate, it will affect its closest packing during film formation, resulting in more pores between the aggregates, which is more conducive to water transmembrane transport. As Figure 8 shown, with the gradual increase of the branched monomer content, the water diffusion coefficient of the polymer electrolyte also increases. At the same time, due to the obvious limitation of the branched structure of the present invention on the water swelling of the polymer electrolyte, it has a smaller water absorption swelling rate (see Figure 9 ), thereby enabling the polymer electrolyte of the present invention to maintain good mechanical stability.

[0113] Example 6

[0114] A super high molecular weight alkaline polymer electrolyte

[0115] Add 2.1 g of 1,3-diphenylbutane, 2.75 g of 7-bromo-1,1,1-trifluoro-2-heptanone and 10 mL of dichloromethane into a 50 mL flask. Then place the flask in an ice-water mixture and add mechanical stirring. After the system temperature stabilizes, drop 15 mL of trifluoromethanesulfonic acid into the system and continue stirring. After adding trifluoromethanesulfonic acid, when the viscosity of the mixture in the system significantly increases in about 5 h, drop 5 mL of dichloromethane solution containing 30 mg of tetraphenylmethane into the system. Then react for another 3 h. The viscosity of the mixture in the system further increases. During this period, the mechanical stirring speed is adjusted downwards several times until a significant rod climbing phenomenon appears in the system at a low speed (40 rpm), and the rod climbing phenomenon lasts for more than 10 seconds after stopping the stirring. At this time, take out the viscous substance in the system in time and soak it in 500 mL of 1 M K2CO3 aqueous solution. After half an hour, crush the solid-liquid mixture with a blender and wash it with water until the pH of the upper clear liquid is neutral. Dry the solid and weigh it for standby. Dissolve the above solid in 20 mL of 1-methyl-2-pyrrolidone, and then add trimethylamine alcohol solution, where the content of trimethylamine should not be less than 0.6 g. Place the reaction solution in a 40 °C water bath and react for 24 h. Then add the light yellow transparent reaction solution into ether to obtain a solid precipitate. After further filtration, washing, ion exchange, and drying, a high molecular weight alkaline polyelectrolyte with high ion conductivity is obtained.

[0116] Comparative Example 1

[0117] Add 2.29 g of p-terphenyl, 1.24 g of 4-methylpiperidone, 7.9 mg of 9,9-spirobifluorene and 15 mL of dichloromethane into a 50 mL flask. Then place the flask in an ice-water mixture and add mechanical stirring. After the system temperature stabilizes, drop 10 mL of trifluoromethanesulfonic acid into the system and continue stirring. After adding trifluoromethanesulfonic acid, a large amount of insoluble solids are generated in the system in about 2 h. There is no adhesion between the solids, and no obvious rod climbing phenomenon can be produced. Then take out the solids in the system and soak them in 100 mL of 1 M K2CO3 aqueous solution. After half an hour, crush the solid-liquid mixture with a blender and wash it with water until the pH of the upper clear liquid is neutral. Dry the solid and weigh it for standby. Place the above solid in a mixed solution of 50 mL of 1-methyl-2-pyrrolidone and dimethyl sulfoxide with a volume ratio of 1:1, and disperse it with vigorous stirring. Finally, the system becomes jelly-like. Then add 1.5 mL of iodomethane, and place the system in a light-shielded environment and react for 24 h. Then add the dark reaction solution into ether to obtain a solid precipitate. After further filtration, washing, ion exchange, and drying, a polymer electrolyte is obtained. Dissolve the obtained polymer electrolyte in DMSO, asFigure 1 As shown. By Figure 1 It can be seen that since the branching agent in this comparative example generates intramolecular rings, the crosslinking effect is poor, and the resulting polymer electrolyte can only swell into a gel in DMSO and cannot be completely dissolved into a solution. The mixture of it and DMSO is filtered through a 600-mesh filter cloth and then cast on a glass plate and left overnight in an environment of 80 °C, and the obtained film is as Figure 3 shown. As can be seen from the figure, this film exhibits an obvious non-uniform structure, seriously affecting its airtightness and mechanical strength.

[0118] In summary, the present invention uses a method of cooperative slow polycondensation to introduce a small amount of polymer monomers with multiple reaction sites and high reaction activity during the polymerization process, and by controlling the reaction temperature, feeding method, nodes of monomer addition, and the node of reaction end, etc., to achieve a substantial increase in the molecular weight of the alkaline polymer electrolyte. The ultra-high molecular weight alkaline polymer electrolyte prepared by the present invention has a folded structure (multi-level structure) similar to that of proteins, and has excellent mechanical properties and processing capabilities, making it have good application and development prospects.

[0119] The above specific embodiments have described the implementation of the present invention in detail. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the claims and technical concept of the present invention, various simple modifications and changes can be made to the technical solution of the present invention, and these simple variations all belong to the protection scope of the present invention.

Claims

1. A preparation method of an ultra-high molecular weight alkaline polymer electrolyte, characterized in that, It includes the following steps: Mix a linear aryl monomer, a super-electrophilic monomer and a solvent evenly, then add a superacid at a low temperature environment and continuously stir. When the viscosity of the mixture in the system has a significant increase, add a highly active aryl monomer dissolved in the solvent into the system for reaction. When the viscosity of the mixture in the system reaches the maximum, add the mixture into an alkaline solution to terminate the reaction, obtaining a super high molecular weight alkaline polymer; react the alkaline polymer with an organic amine or a halogenated hydrocarbon to obtain a super high molecular weight alkaline polymer electrolyte.

2. The preparation method of a super high molecular weight alkaline polymer electrolyte according to claim 1, characterized in that, The molar ratio of the linear aryl monomer, the highly active aryl monomer and the super-electrophilic monomer is (90~99):(10~1):(150~100); the molar volume ratio mol / L of the linear aryl monomer to the superacid is (90~99):(0.8 - 1.2).

3. The preparation method of a super high molecular weight alkaline polymer electrolyte according to claim 1, characterized in that, The linear aryl monomer is selected from one or more of the following listed compounds: （a） ； （b） ； (c) wherein R is H, NH2, OH or a halogen; （d） ； （e） ； （f） ； (g) , where n = 0, 1, 2, 3... 8; (h) wherein R is CH2, NH, O or S; (i) , where R is an aliphatic hydrocarbon substituent and its derivatives, a halogenated hydrocarbon substituent, or an unsaturated hydrocarbon group and its derivatives; (j) , where R is an aliphatic hydrocarbon substituent and its derivatives, a halogenated hydrocarbon substituent, or an unsaturated hydrocarbon group and its derivatives; Derivatives of the compounds listed in (k) a-j.

4. The preparation method of a super high molecular weight alkaline polymer electrolyte according to claim 1, characterized in that, The super-electrophilic monomer is selected from one or more of the following listed compounds: (a) wherein R is H, an aliphatic hydrocarbon substituent and its derivatives, or an unsaturated hydrocarbon group and its derivatives; (b) wherein R is H, an aliphatic hydrocarbon substituent and its derivatives, or an unsaturated hydrocarbon group and its derivatives; （c） ； （d） ； (e) wherein n = 0, 1, 2, 3... 8, and R is an aliphatic hydrocarbon substituent and its derivatives, a halogenated hydrocarbon substituent, or an unsaturated hydrocarbon group and its derivatives; Derivatives of the compounds listed in (f) a-e.

5. The preparation method of a super high molecular weight alkaline polymer electrolyte according to claim 1, characterized in that, The highly active aryl monomer is selected from one or more of the following listed compounds: （a） ； （b） ； （c） ； （d） ； （e） ； （f） ； （g） ； （h） ； （i） ； Derivatives of the compounds listed in (k) a-i.

6. The preparation method of a super high molecular weight alkaline polymer electrolyte according to claim 1, characterized in that, After mixing the linear aryl monomer, the super-electrophilic monomer and the solvent evenly, the viscosity of the system is 0.4~1.5 mPa·s; after adding the superacid into the system, when the viscosity increase of the mixture in the system reaches 500~2000 mPa·s, then add the highly active aryl monomer dissolved in the solvent into the system for reaction. When the mixture in the system shows an obvious rod climbing phenomenon at a rotation speed of 40~50 rpm and the rod climbing phenomenon persists after stopping stirring for 10 seconds, add the mixture into an alkaline solution to terminate the reaction.

7. The preparation method of a super high molecular weight alkaline polymer electrolyte according to claim 1, characterized in that, The superacid includes but is not limited to at least one of trifluoroacetic acid, trifluoromethanesulfonic acid, fluorosulfonic acid, and chlorosulfonic acid.

8. The preparation method of a super high molecular weight alkaline polymer electrolyte according to claim 1, characterized in that, The temperature of the low temperature environment is -20~20 °C.

9. A super high molecular weight alkaline polymer electrolyte prepared by the method according to any one of claims 1~8.

10. Application of the super high molecular weight alkaline polymer electrolyte according to claim 9 in an alkaline polyelectrolyte fuel cell.

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