Block sulfonated polymer, synthetic method thereof, proton exchange membrane and application of proton exchange membrane

Abstract

The invention relates to the technical field of high polymer materials, in particular to a block sulfonated polymer, a synthesis method of the block sulfonated polymer, a proton exchange membrane and application of the proton exchange membrane. The chain segment A2 comprises one or two of a formula 1 and a formula 2; the chain segment A1 comprises one or two of a formula 3 and a formula 4; according to the block sulfonated polymer, an ion transmission channel containing micropores is constructed by virtue of the rigidity and nonlinearity of sulfonic acid groups on the chain segment A1 and benzimidazole structures on the chain segment A1 and the chain segment A2, so that the proton exchange membrane prepared by taking the block sulfonated polymer as a raw material has excellent ion selectivity and ion conductivity; the proportion of ether bonds in the block sulfonated polymer can be effectively reduced, so that the probability that the proton exchange membrane is attacked by free radicals such as OH. And OOH. Is reduced, the chemical stability of the block sulfonated polymer and the proton exchange membrane thereof is improved, and the application range is expanded.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, and particularly relates to a block sulfonated polymer, a synthesis method thereof, a proton exchange membrane and an application thereof. Background Art

[0002] A proton exchange membrane (PEM) is a core component of electrochemical energy conversion devices, such as fuel cells, hydrogen production electrolyzers, flow batteries, etc., and plays a key role in their performance; and proton exchange membranes are usually made of materials such as perfluorosulfonic acid (PFSA) materials, partially fluorinated polymer materials, non-fluorinated polymer materials, composite materials (the combination of perfluorosulfonic acid and other materials such as inorganic nanoparticles, porous matrices, etc.); among them, fluorinated polymers are the dominant materials, such as the trade name

[0003] Traditional PFSA materials used to make proton exchange membranes usually have high proton conductivity, balanced water absorption, retention and distribution capabilities, limited swelling, volume expansion and contraction behaviors during the process of moisture absorption and / or dehumidification, relatively high chemical stability, etc.; however, the preparation cost of PFSA materials is relatively high, which will affect the overall economy of proton exchange membranes; and the heat resistance and mechanical strength of PFSA materials are also poor. Compared with traditional PFSA materials, sulfonated carbon hydrogen ion polymers have significant advantages, such as simple preparation process, low preparation cost, high thermo-mechanical stability, environmental friendliness, etc.; however, there are still certain deficiencies in the ionic conductivity and chemical stability of sulfonated carbon hydrogen ion polymers; although the ionic conductivity can be improved by increasing the sulfonic acid group density; however, a higher sulfonic acid group density will cause higher water absorption and swelling, reducing the mechanical properties of the material; and the main chain of sulfonated carbon hydrogen ion polymers usually contains more ether bonds, and in electrochemical reactions, free radicals such as OH· and OOH· will deteriorate the ether bonds of the sulfonated polymer and damage its durability. Therefore, it is necessary to optimize the sulfonated carbon hydrogen ion polymer to solve the above problems.

[0004] The present invention provides a block sulfonated polymer, a synthesis method thereof, a proton exchange membrane and an application thereof to solve the problems existing in the prior art, such as poor ionic conductivity and insufficient chemical stability of existing sulfonated carbon hydrogen ion polymers. Summary of the Invention

[0005] The object of the present invention is: a block sulfonated polymer, a synthesis method thereof, a proton exchange membrane and an application thereof to solve the problems existing in the prior art, such as poor ionic conductivity and insufficient chemical stability of existing sulfonated carbon hydrogen ion polymers.

[0006] The technical solution of the present invention is: a block sulfonated polymer, which comprises a chain segment A1 and a chain segment A2; on the chain segment A2, there is / are one or both of the following; on the chain segment A1, there is / are one or both of the following; wherein, X1 represents a carbonyl group or a sulfone group, and Y1 represents a nitrogen-containing heterocyclic unit.

[0007] Preferably, on the chain segment A2, the quantity of the formula 1 and the formula 2 accounts for more than 10% of the total quantity of the repeating units on the chain segment A2;

[0008] on the chain segment A1, the quantity of the formula 3 and the formula 4 accounts for more than 0.3% of the total quantity of the repeating units on the chain segment A1.

[0009] Preferably, the nitrogen-containing heterocyclic unit is any one of the following.

[0010] Preferably, on the chain segment A1, there is also wherein, Y2 is any one of a carbonyl group, an isopropylidene group, a hexafluoroisopropylidene group, and a directly-connected carbon chain structure; n is 0 or 1.

[0011] Preferably, the density of the sulfonic acid groups on the block sulfonated polymer is 0.3 - 2.8 mmol / g.

[0012] The present invention also provides a synthesis method of the above block sulfonated polymer, comprising the following steps:

[0013] S1. Weigh the disulfonated aromatic dihalide monomer, aromatic dihydroxy monomer, and monomer containing a benzimidazole structural unit, add them to a reaction vessel, then successively add an organic solvent and a catalyst, and then stir at 140°C - 200°C for 2 - 10 h to carry out a condensation polymerization reaction;

[0014] S2. After the reaction is completed, first add an organic solvent to the reaction vessel for dilution, then add a fluorine-containing organic compound, and react at 70 - 120°C for 1 - 5 hours. Then, add a diluent to precipitate and deposit the chain segment A1 oligomer with both ends being fluorine terminals in the reaction solution, and then carry out filtration, washing treatment, and drying treatment to obtain the chain segment A1 oligomer with both ends being fluorine terminals for standby;

[0015] S3. Weigh the dihaloaromatic monomer, aromatic dihydroxy monomer, and monomer containing benzimidazole structural unit, add them to a reaction vessel, then successively add an organic solvent and a catalyst, stir at 140 °C - 200 °C for 2 - 10 h to carry out a polycondensation reaction. After the reaction is completed, add a diluent to precipitate and deposit the oligomer of segment A2 in the reaction solution, then carry out filtration, washing, and drying treatments to obtain the oligomer of segment A2 for use;

[0016] S4. Add the oligomer of segment A1 obtained in S2 and the oligomer of segment A2 obtained in S3 to a reactor, then successively add an organic solvent and a catalyst, stir at 70 - 120 °C for 2 - 10 h to carry out a polycondensation reaction;

[0017] S5. After the reaction is completed, add a diluent to precipitate and deposit the block sulfonated polymer in the reaction solution, then carry out filtration, washing, and drying treatments to obtain the block sulfonated polymer;

[0018] Among them, the catalyst is an inorganic salt or organic reagent with basicity.

[0019] Preferably, the disulfonated aromatic dihalo monomer is any one or more of 3,3'-disodium sulfonate - 4,4'-difluorobenzophenone, 3,3'-disodium sulfonate - 4,4'-difluorodiphenyl sulfone, 3,3'-disodium sulfonate - 4,4'-dichlorobenzophenone, 3,3'-disodium sulfonate - 4,4'-dichlorodiphenyl sulfone;

[0020] The aromatic dihydroxy monomer is any one or more of 4,4'-dihydroxybiphenyl, 4,4'-dihydroxybenzophenone, bisphenol A, bisphenol AF;

[0021] The monomer containing benzimidazole structural unit is any one or more of benzimidazolone, nitrogen-containing heterocyclic bisbenzimidazole monomer;

[0022] The structural formula of the nitrogen-containing heterocyclic bisbenzimidazole monomer is

[0023] The dihaloaromatic monomer is any one or more of 4,4'-difluorobenzophenone, 4,4'-difluorodiphenyl sulfone, 4,4'-dichlorobenzophenone, 4,4'-dichlorodiphenyl sulfone;

[0024] The fluorinated organic compound is decafluorobiphenyl or hexafluorobenzene.

[0025] Preferably, the organic solvent is any one or more of dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, sulfolane, diphenyl sulfone, toluene, cyclohexane;

[0026] The diluent is any one of deionized water, methanol, ethanol, isopropanol, n-butanol, and acetone;

[0027] The inorganic salt is any one or more of potassium carbonate, sodium carbonate, and calcium carbonate.

[0028] The present invention also provides a proton exchange membrane, which is made of the above-mentioned block sulfonated polymer.

[0029] The present invention also provides the application of the above-mentioned proton exchange membrane, including the application of the above-mentioned proton exchange membrane in fuel cells, proton exchange membrane electrolyzers, and flow batteries.

[0030] Compared with the prior art, the advantages of the present invention are:

[0031] (1) The present invention provides a block sulfonated polymer and its synthesis method, a proton exchange membrane and its application. The structural unit shown in Formula 3 and / or Formula 4 containing a benzimidazole structure is included on the segment A1 in the block sulfonated polymer, and the structural unit shown in Formula 1 and / or Formula 2 containing a benzimidazole structure is included on the segment A2. By relying on the sulfonic acid groups on the segment A1 and the rigidity and non-linearity of the benzimidazole structures on the segment A1 and the segment A2, an ion transport channel containing micropores is constructed, so that the proton exchange membrane made of the block sulfonated polymer has excellent ion selectivity and ion conductivity; moreover, the structural unit shown in Formula 3 and / or Formula 4 is included on the segment A1, and the structural unit shown in Formula 1 and / or Formula 2 is included on the segment A2, which can effectively reduce the proportion of ether bonds in the block sulfonated polymer, thereby reducing the probability of the block sulfonated polymer and its proton exchange membrane being attacked by free radicals such as OH· and OOH·, improving the chemical stability of the block sulfonated polymer and its proton exchange membrane, and expanding its application range; at the same time, the non-glass transition temperature can also be increased through the rigidity of the benzimidazole structures on the segment A1 and the segment A2, thereby improving the heat resistance of the block sulfonated polymer; the problems of poor ion conductivity and insufficient chemical stability of the existing sulfonated carbon hydrogen ion polymers in the prior art are solved. Detailed Embodiments

[0032] The following combines specific embodiments to further elaborate on the content of the present invention:

[0033] It should be noted that the preparation process of the proton exchange membrane from the purified block sulfonated polymer solid materials in Examples 1-6 and Comparative Examples 1-3 below is as follows: The purified block sulfonated polymer solid materials are dissolved in dimethylformamide, and the solid content is controlled between 14-16%; after complete dissolution, the solution is filtered with a 1μm glass fiber filter paper, and the filtrate is coated on a PET base film with a flat blade; then, it is dried in a hot air oven at 60-100°C for 3 hours to obtain a thin film; finally, it is soaked in a 10wt% dilute sulfuric acid solution for 24 hours, then washed with a large amount of deionized water and dried to obtain the proton exchange membrane.

[0034] It should be noted that the method for measuring the sulfonic acid group density of the proton exchange membrane is as follows: After the proton exchange membrane is peeled off from the PET base film, it is cut into thin films about 30mg in size and placed in a 100mL glass bottle. It is dried in a vacuum oven at 120°C for more than 12 hours until the proton exchange membrane is completely dry. Then, the weight M1 of the dried proton exchange membrane is quickly weighed with a precision balance; then, 50mL of 5wt% sodium sulfate solution is added to the glass bottle and left to stand for replacement; then, it is titrated with 0.01mol / L sodium hydroxide aqueous solution, using phenolphthalein as an indicator, and the solution turning light purple-red is used as the titration end point, and the volume V1 of the sodium hydroxide solution used is recorded; Sulfonic acid group density (mmol / g) = (V1x0.01mol / L) / M1; Each proton exchange membrane is tested three times and the average value is taken.

[0035] It should be noted that the method for testing the proton conductivity of the proton exchange membrane is as follows: The membrane is cut into 1cmx4cm strips and clamped in a test mold. Using platinum as the electrode, the test mold is placed in a thermostatic and humidified box and left for more than 30 minutes at 80°C and a relative humidity of 95%; then, when the AC amplitude is 50mV, the AC impedance spectrum is measured to obtain the impedance value R of the thin film, and the proton conductivity σ = (L / RxA), where L is the distance between the platinum electrodes, R is the impedance value, and A is the effective cross-sectional area of the thin film.

[0036] It should be noted that the oxidative stability of the proton exchange membrane is judged by the mass loss after Fenton test. The less the proton loss, the stronger the antioxidant property; The specific method is: Weigh three dried proton exchange membranes of about 20mg each and record W0; At 80°C, place the proton exchange membrane in Fenton reagent (3% H2O2, 3ppm Fe 2+ )), take out one proton exchange membrane every 1h, rinse it with deionized water and soak it for 24h, repeat three times, then soak it in 1mol / L HCl for 24h, repeat three times; Finally, vacuum dry the proton exchange membrane at 80°C overnight, weigh and record W1, and calculate the mass change: Mass loss = (W0 - W1) / W0 x 100%.

[0037] A block sulfonated polymer, comprising a sulfonic acid group-containing segment A1 and a sulfonic acid group-free segment A2; wherein, the main chain of segment A2 includes one or both of several structural units shown in Formula 2; the main chain of segment A1 includes one or both of several structural units shown in ; wherein, X1 represents a carbonyl group or a sulfone group, and Y1 represents a nitrogen-containing heterocyclic unit.

[0038] In the present application, the nitrogen-containing heterocyclic unit is preferably one of . On the main chain of the sulfonic acid group-free segment A2, the number of repeating units of the structural units shown in Formula 1 and Formula 2 or the total number of repeating units of the structural units shown in Formula 1 and Formula 2 both account for more than 10% of the total number of repeating units on segment A2; when the number of the structural units shown in Formula 1 and / or Formula 2 is insufficient, it may cause insufficient solubility of segment A2, thereby leading to difficulties in the synthesis of the block sulfonated polymer, insufficient mechanical properties, and inability to be prepared into a proton exchange membrane, etc.; therefore, from the perspective of more easily obtaining the block polymer and preparing a proton exchange membrane with higher mechanical properties, on the main chain of segment A2, the number of the structural units shown in Formula 1 and / or Formula 2 accounts for more than 20% of the total number of all repeating units on segment A2, more preferably more than 30%. On the main chain of the sulfonic acid group-containing segment A1, the number of the structural units shown in Formula 3 and Formula 4 accounts for more than 0.3% of the total number of repeating units on the main chain of segment A1; and, considering chemical durability and cost, it is preferred that the main chain of segment A1 contains both the structural units shown in Formula 3 and Formula 4 at the same time.

[0039] The segment A1 further includes several wherein, Y2 is any one of a carbonyl group, an isopropylidene group, a hexafluoroisopropylidene group, and a directly connected carbon chain structure (i.e., two benzene rings are directly connected, such as Formula 3 is 4,4'-dihydroxybiphenyl); n is 0 or 1.

[0040] The structural unit refers to the basic composition unit in which monomer molecules enter the main chains of segment A1 and segment A2 through a polymerization reaction, such as Formula 1, Formula 2, Formula 3, Formula 4, Formula 5, etc.; the repeating unit refers to the smallest basic composition unit in which the chemical composition and structure repeatedly appear on the main chain of a polymer or oligomer, and can also be called a chain link; it can be composed of one or more structural units. In the present application, the repeating unit refers to the structural units such as Formula 1, Formula 2, Formula 3, Formula 4, Formula 5, etc. that repeatedly appear on the main chains of segment A1 and segment A2; the total number of all repeating units on the main chains of segment A1 and segment A2 refers to the sum of the numbers of the structural units such as Formula 1, Formula 2 or Formula 3, Formula 4, etc. that repeatedly appear on the main chain.

[0041] In this application, the density of sulfonic acid groups in the block sulfonated polymerization needs to be controlled within the range of 0.3 - 2.8 mmol / g; and, considering high proton conductivity, high mechanical properties, and chemical durability, the density of sulfonic acid groups is preferably 0.5 - 2.6 mmol / g; more preferably, the density of sulfonic acid groups is 0.8 - 2.4 mmol / g. Among them, the density of sulfonic acid groups refers to the molar amount of sulfonic acid groups in the sulfonated polymer per unit dry weight, and the larger the value, the higher the degree of sulfonation.

[0042] This application also provides a synthesis method for the above-mentioned block sulfonated polymerization, which specifically includes the following steps:

[0043] S1. Add the weighed raw materials into a reaction vessel, then successively add an organic solvent and a catalyst, and then stir at 140°C - 200°C for 2 - 10 h to carry out a condensation polymerization reaction; among them, the raw materials include a disulfonated aromatic dihalide monomer and an aromatic dihydroxy monomer, and may also include a monomer containing a benzimidazole structural unit;

[0044] S2. After the reaction is completed, first add an organic solvent to the reaction vessel for dilution, then add a fluorine-containing organic substance, and react at 70 - 120°C for 1 - 5 hours. Then, add a diluent to precipitate and deposit the chain segment A1 oligomer with fluorine terminals at both ends in the reaction solution, and then carry out filtration, washing treatment, and drying treatment to obtain the chain segment A1 oligomer with fluorine terminals at both ends for use; among them, "filtration, washing treatment, drying treatment", etc. recorded here and below are all purification steps; and, the drying treatment refers to drying in a vacuum oven at 100°C - 150°C for more than 12 hours;

[0045] S3. Add the weighed dihalide aromatic monomer, aromatic dihydroxy monomer, and monomer containing a benzimidazole structural unit into a reaction vessel, then successively add an organic solvent and a catalyst, stir at 140°C - 200°C for 2 - 10 h to carry out a condensation polymerization reaction. After the reaction is completed, add a diluent to precipitate and deposit the chain segment A2 oligomer in the reaction solution, and then carry out filtration, washing treatment, and drying treatment to obtain the chain segment A2 oligomer for use;

[0046] S4. Add the chain segment A1 oligomer obtained in S2 and the chain segment A2 oligomer obtained in S3 into a reactor, then successively add an organic solvent and a catalyst, and stir at 70 - 120°C for 2 - 10 h to carry out a condensation polymerization reaction;

[0047] S5. After the reaction is completed, add a diluent to precipitate and deposit the block sulfonated polymer in the reaction solution, and then carry out filtration, washing treatment, and drying treatment to obtain the block sulfonated polymer.

[0048] Among them, the fluorinated organic compound in step S2 is decafluorobiphenyl or hexafluorobenzene; in order to obtain the segment A1 oligomer with fluorine terminals at both ends, the molar amount of the disulfonated aromatic dihalide monomer in step S1 needs to be slightly lower than the total molar amount of the aromatic dihydroxy monomer and the monomer containing a benzimidazole structural unit. After the condensation polymerization reaction is completed, it is capped with decafluorobiphenyl or hexafluorobenzene to prepare the segment A1 oligomer with fluorine terminals at both ends.

[0049] The disulfonated aromatic dihalide monomer is one or more of 3,3'-disodium sulfonate-4,4'-difluorobenzophenone, 3,3'-disodium sulfonate-4,4'-difluorodiphenyl sulfone, 3,3'-disodium sulfonate-4,4'-dichlorobenzophenone, 3,3'-disodium sulfonate-4,4'-dichlorodiphenyl sulfone, etc.; the aromatic dihydroxy monomer is one or more of 4,4'-dihydroxybiphenyl, 4,4'-dihydroxybenzophenone, bisphenol A, bisphenol AF, etc.; the dihaloaromatic monomer is one or more of 4,4'-difluorobenzophenone, 4,4'-difluorodiphenyl sulfone, 4,4'-dichlorobenzophenone, 4,4'-dichlorodiphenyl sulfone, etc.; the monomer containing a benzimidazole structural unit is one or more of benzimidazolone and nitrogen-containing heterocyclic bisbenzimidazole monomers. The structural formula of the nitrogen-containing heterocyclic bisbenzimidazole monomer is And, the nitrogen-containing heterocyclic bisbenzimidazole monomer is prepared by reacting a nitrogen-containing heterocyclic dicarboxylic acid monomer with o-phenylenediamine monomer, using polyphosphoric acid as a condensing agent and solvent, reacting at 130 - 230 °C for 2 - 10 hours, and then purifying by dilution with deionized water, neutralization, and recrystallization with ethanol.

[0050] In addition, the above catalyst is an alkaline inorganic salt or organic reagent; the inorganic salt is preferably one or more of potassium carbonate, sodium carbonate, calcium carbonate, etc.; the above diluent is one of deionized water, methanol, ethanol, isopropyl alcohol, n-butanol, acetone, etc.; the above organic solvent is one or more of dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, sulfolane, diphenyl sulfone, toluene, cyclohexane, etc.

[0051] This application also provides a proton exchange membrane made of the above block sulfonated polymer and its applications in fuel cells, proton exchange membrane electrolyzers, flow batteries, etc.; the proton exchange membrane is prepared by dissolving the block sulfonated polymer material in an organic solvent to prepare a membrane-forming solution, and then obtaining it in a base membrane material by the casting method.

[0052] Example 1

[0053] S1. Add 3,3'-disulfonate-4,4'-difluorobenzophenone (20.7 g, 49 mmol), 4,4'-dihydroxybenzophenone (10.7 g, 50 mmol), and potassium carbonate (7.7 g) into a reactor. Then, introduce nitrogen into the reactor and add 126 ml of N-methylpyrrolidone and 30 ml of toluene. After that, first carry out a water-removing reaction at 140 °C for 2 hours, and then raise the temperature to 180 °C and react for another 4 hours.

[0054] S2. After the reaction is completed, first add 126 ml of N-methylpyrrolidone to the reaction vessel for dilution, then add 2.6 g of decafluorobiphenyl, and react at 80 °C for 3 hours. After that, add acetone to precipitate and separate the A1 oligomer with fluorine terminals at both ends in the reaction solution. After purification, the A1 oligomer with fluorine terminals at both ends is obtained for use.

[0055] S3. Add 4,4'-difluorobenzophenone (10.7 g, 49 mmol), benzimidazolone (6.6 g, 50 mmol), potassium carbonate (4.2 g), and calcium carbonate (1.0 g) into a reactor. Then, introduce nitrogen into the reactor and add 80 ml of N-methylpyrrolidone and 25 ml of toluene. Immediately, first carry out a water-removing reaction at 140 °C for 2 hours, and then raise the temperature to 200 °C and react for another 4 hours. After that, add methanol to precipitate and separate the A2 oligomer in the reaction solution. After purification, the A2 oligomer is obtained for use.

[0056] S4. Add 10 g of the A1 oligomer obtained in step S2 and 4.6 g of the A2 oligomer obtained in step S3 into a reactor. Then, introduce nitrogen into the reactor and add 150 ml of N-methylpyrrolidone, and react at 100 °C for 4 hours.

[0057] S5. After the reaction is completed, add acetone to precipitate and separate the block sulfonated polymer in the reaction solution, and obtain the block sulfonated polymer after purification.

[0058] Example 2

[0059] S1. Add 3,3'-disulfonate-4,4'-difluorobenzophenone (20.7 g, 49 mmol), 4,4'-dihydroxybenzophenone (10.7 g, 50 mmol), and potassium carbonate (7.7 g) into a reactor. Then, introduce nitrogen into the reactor and add 126 ml of N-methylpyrrolidone and 30 ml of toluene. After that, first carry out a water-removing reaction at 140 °C for 2 hours, and then raise the temperature to 180 °C and react for another 4 hours.

[0060] S2. After the reaction is completed, first add 126 ml of N-methylpyrrolidone to the reaction vessel for dilution, then add 2.6 g of decafluorobiphenyl, and react at 80 °C for 3 hours. After that, add acetone to precipitate and deposit the segment A1 oligomer with fluorine terminals at both ends in the reaction solution. After purification, the segment A1 oligomer with fluorine terminals at both ends is obtained for use;

[0061] S3. Add 4,4'-difluorobenzophenone (10.7 g, 49 mmol), 4,4'-dihydroxybenzophenone (7.5 g, 35 mmol), benzimidazolone (2.0 g, 15 mmol), 4.2 g of potassium carbonate, and 1.0 g of calcium carbonate to the reactor. Then, introduce nitrogen into the reactor and add 80 ml of N-methylpyrrolidone and 25 ml of toluene. Immediately, first carry out a water-carrying reaction at 140 °C for 2 hours, then raise the temperature to 200 °C and react for another 4 hours. After that, add methanol to precipitate and deposit the segment A2 oligomer in the reaction solution. After purification, the segment A2 oligomer is obtained for use;

[0062] S4. Add 10 g of the segment A1 oligomer obtained in step S2 and 4.6 g of the segment A2 oligomer obtained in step S3 to the reactor. Then, introduce nitrogen into the reactor and add 150 ml of N-methylpyrrolidone, and react at 100 °C for 4 hours;

[0063] S5. After the reaction is completed, add acetone to precipitate and deposit the block sulfonated polymer in the reaction solution, and purify to obtain the block sulfonated polymer.

[0064] Example 3

[0065] S1. Add 3,3'-disulfonate-4,4'-difluorobenzophenone (20.7 g, 49 mmol), 4,4'-dihydroxybenzophenone (10.7 g, 50 mmol), and 7.7 g of potassium carbonate to the reactor. Then, introduce nitrogen into the reactor and add 126 ml of N-methylpyrrolidone and 30 ml of toluene. After that, first carry out a water-carrying reaction at 140 °C for 2 hours, then raise the temperature to 180 °C and react for another 4 hours;

[0066] S2. After the reaction is completed, first add 126 ml of N-methylpyrrolidone to the reaction vessel for dilution, then add 2.6 g of decafluorobiphenyl, and react at 80 °C for 3 hours. After that, add acetone to precipitate and deposit the segment A1 oligomer with fluorine terminals at both ends in the reaction solution. After purification, the segment A1 oligomer with fluorine terminals at both ends is obtained for use;

[0067] S3. Add 4,4'-difluorobenzophenone (10.7 g, 49 mmol), 4,4'-dihydroxybenzophenone (9.6 g, 45 mmol), benzimidazolone (0.7 g, 5 mmol), potassium carbonate 4.2 g, and calcium carbonate 1.0 g into a reactor. Then, introduce nitrogen into the reactor and add 80 ml of N-methylpyrrolidone and 25 ml of toluene. Immediately, first carry out a water-removing reaction at 140 °C for 2 hours, then raise the temperature to 200 °C and react for another 4 hours. After that, add methanol to precipitate and separate the oligomer A2 segment in the reaction solution, and obtain the oligomer A2 segment after purification for later use.

[0068] S4. Add 10 g of the oligomer A1 segment obtained in step S2 and 3.6 g of the oligomer A2 segment obtained in step S3 into a reactor. Then, introduce nitrogen into the reactor and add 150 ml of N-methylpyrrolidone, and react at 100 °C for 4 hours.

[0069] S5. After the reaction is completed, add acetone to precipitate and separate the block sulfonated polymer in the reaction solution, and obtain the block sulfonated polymer after purification.

[0070] Example 4

[0071] S1. Add 3,3'-disulfonate-4,4'-difluorobenzophenone (20.7 g, 49 mmol), 4,4'-dihydroxybenzophenone (10.7 g, 50 mmol), and potassium carbonate 7.7 g into a reactor. Then, introduce nitrogen into the reactor and add 126 ml of N-methylpyrrolidone and 30 ml of toluene. After that, first carry out a water-removing reaction at 140 °C for 2 hours, then raise the temperature to 180 °C and react for another 4 hours.

[0072] S2. After the reaction is completed, first add 126 ml of N-methylpyrrolidone to the reaction vessel for dilution, then add 2.6 g of decafluorobiphenyl, and react at 80 °C for 3 hours. After that, add acetone to precipitate and separate the oligomer A1 segment with fluorine terminals at both ends in the reaction solution, and obtain the oligomer A1 segment with fluorine terminals at both ends after purification for later use.

[0073] S3. Add 4,4'-difluorobenzophenone (10.7 g, 49 mmol), 4,4'-dihydroxybenzophenone (7.4 g, 34.5 mmol), benzimidazolone (2.0 g, 15 mmol), bisbenzimidazole-1,10-phenanthroline (0.21 g, 0.5 mmol), potassium carbonate 4.2 g, and calcium carbonate 1.0 g into a reactor. Then, introduce nitrogen into the reactor and add 80 ml of N-methylpyrrolidone and 25 ml of toluene. Immediately, first carry out a water-removing reaction at 140 °C for 2 hours, then raise the temperature to 200 °C and react for another 4 hours. After that, add methanol to precipitate and separate the segment A2 oligomer in the reaction solution, and obtain the segment A2 oligomer after purification for later use;

[0074] S4. Add 10 g of the segment A1 oligomer obtained in step S2 and 4.5 g of the segment A2 oligomer obtained in step S3 into a reactor. Then, introduce nitrogen into the reactor and add 150 ml of N-methylpyrrolidone, and react at 100 °C for 4 hours;

[0075] S5. After the reaction is completed, add acetone to precipitate and separate the block sulfonated polymer in the reaction solution, and obtain the block sulfonated polymer after purification.

[0076] Example 5

[0077] S1. Add 3,3'-disulfonate-4,4'-difluorobenzophenone (20.7 g, 49 mmol), 4,4'-dihydroxybenzophenone (7.4 g, 34.5 mmol), benzimidazolone (2.0 g, 15 mmol), bisbenzimidazole-1,10-phenanthroline (0.21 g, 0.5 mmol), potassium carbonate 8.2 g, and calcium carbonate 1.0 g into a reactor. Then, introduce nitrogen into the reactor and add 126 ml of N-methylpyrrolidone and 30 ml of toluene. After that, first carry out a water-removing reaction at 140 °C for 2 hours, then raise the temperature to 180 °C and react for another 4 hours;

[0078] S2. After the reaction is completed, first add 126 ml of N-methylpyrrolidone to the reaction vessel for dilution, then add 2.6 g of decafluorobiphenyl, and react at 80 °C for 3 hours. After that, add acetone to precipitate and separate the segment A1 oligomer with fluorine terminals at both ends in the reaction solution, and obtain the segment A1 oligomer with fluorine terminals at both ends after purification for later use;

[0079] S3. Add 4,4'-difluorobenzophenone (10.7 g, 49 mmol), 4,4'-dihydroxybenzophenone (7.4 g, 34.5 mmol), benzimidazolone (2.0 g, 15 mmol), bisbenzimidazole-1,10-phenanthroline (0.21 g, 0.5 mmol), potassium carbonate 4.2 g, and calcium carbonate 1.0 g into a reactor. Then, introduce nitrogen into the reactor and add 80 ml of N-methylpyrrolidone and 25 ml of toluene. Immediately, first carry out a water-carrying reaction at 140 °C for 2 hours, then raise the temperature to 200 °C and react for another 4 hours. After that, add methanol to precipitate and separate the segment A2 oligomer in the reaction solution. After purification, the segment A2 oligomer is obtained for use.

[0080] S4. Add 9 g of the segment A1 oligomer obtained in step S2 and 4.6 g of the segment A2 oligomer obtained in step S3 into a reactor. Then, introduce nitrogen into the reactor and add 150 ml of N-methylpyrrolidone, and react at 100 °C for 4 hours.

[0081] S5. After the reaction is completed, add acetone to precipitate and separate the block sulfonated polymer in the reaction solution. After purification, the block sulfonated polymer is obtained.

[0082] Example 6

[0083] S1. Add 3,3'-disulfonate-4,4'-difluorodiphenyl sulfone (22.4 g, 49 mmol), 4,4'-dihydroxybenzophenone (7.4 g, 34.5 mmol), benzimidazolone (2.0 g, 15 mmol), bisbenzimidazole-1,10-phenanthroline (0.21 g, 0.5 mmol), potassium carbonate 8.2 g, and calcium carbonate 1.0 g into a reactor. Then, introduce nitrogen into the reactor and add 126 ml of N-methylpyrrolidone and 30 ml of toluene. After that, first carry out a water-carrying reaction at 140 °C for 2 hours, then raise the temperature to 180 °C and react for another 4 hours.

[0084] S2. After the reaction is completed, first add 126 ml of N-methylpyrrolidone to the reaction vessel for dilution, then add 2.6 g of decafluorobiphenyl, and react at 80 °C for 3 hours. After that, add acetone to precipitate and separate the segment A1 oligomer with fluorine terminals at both ends in the reaction solution. After purification, the segment A1 oligomer with fluorine terminals at both ends is obtained for use.

[0085] S3. Add 4,4'-difluorodiphenyl sulfone (12.4 g, 49 mmol), 4,4'-dihydroxybenzophenone (7.4 g, 34.5 mmol), benzimidazolone (2.0 g, 15 mmol), bisbenzimidazole-1,10-phenanthroline (0.21 g, 0.5 mmol), potassium carbonate 4.2 g, and calcium carbonate 1.0 g into a reactor. Then, introduce nitrogen gas into the reactor and add 80 ml of N-methylpyrrolidone and 25 ml of toluene. Immediately, first perform a water-carrying reaction at 140 °C for 2 hours, then raise the temperature to 200 °C and react for another 4 hours. After that, add methanol to precipitate and separate the oligomer A2 segments in the reaction solution, and obtain the oligomer A2 segments after purification for standby use;

[0086] S4. Add 8.5 g of the oligomer A1 segments obtained in step S2 and 4.6 g of the oligomer A2 segments obtained in step S3 into a reactor. Then, introduce nitrogen gas into the reactor and add 150 ml of N-methylpyrrolidone, and react at 100 °C for 4 hours;

[0087] S5. After the reaction is completed, add acetone to precipitate and separate the block sulfonated polymer in the reaction solution, and obtain the block sulfonated polymer after purification.

[0088] Comparative Example 1

[0089] S1. Add 3,3'-disulfonate-4,4'-difluorodiphenyl sulfone (22.4 g, 49 mmol), 4,4'-dihydroxybenzophenone (10.7 g, 50 mmol), and potassium carbonate 7.7 g into a reactor. Then, introduce nitrogen gas into the reactor and add 126 ml of N-methylpyrrolidone and 30 ml of toluene. After that, first perform a water-carrying reaction at 140 °C for 2 hours, then raise the temperature to 180 °C and react for another 4 hours to obtain an oligomer with hydroxyl ends;

[0090] S2. After the reaction is completed, first add 126 ml of N-methylpyrrolidone to the reaction vessel for dilution, then add 2.6 g of decafluorobiphenyl, and react at 80 °C for 3 hours. After that, add acetone to precipitate and separate the oligomer A1 segments with fluorine ends at both ends in the reaction solution, and obtain the oligomer A1 segments with fluorine ends at both ends after purification for standby use;

[0091] S3. Add 4,4'-difluorodiphenyl sulfone (12.4 g, 9 mmol), 4,4'-dihydroxybenzophenone (10.7 g, 50 mmol), and 4.2 g of potassium carbonate into a reactor. Then, introduce nitrogen gas into the reactor and add 80 ml of N-methylpyrrolidone and 25 ml of toluene. Immediately, first conduct a water-removing reaction at 140 °C for 2 hours, then raise the temperature to 200 °C and react for another 4 hours. After that, add methanol to precipitate and separate the segment A2 oligomer in the reaction solution, and obtain the segment A2 oligomer after purification for later use.

[0092] S4. Add 8.6 g of the segment A1 oligomer obtained in step S2 and 4.6 g of the segment A2 oligomer obtained in step S3 into a reactor. Then, introduce nitrogen gas into the reactor and add 150 ml of N-methylpyrrolidone, and react at 100 °C for 4 hours.

[0093] S5. After the reaction is completed, add acetone to precipitate and separate the block sulfonated polymer in the reaction solution, and obtain the block sulfonated polymer after purification.

[0094] Comparative Example 2

[0095] Add 4,4'-difluorodiphenyl sulfone (12.7 g, 50 mmol), 3,3'-disulfonate-4,4'-difluorodiphenyl sulfone (22.9 g, 50 mmol), 4,4'-dihydroxybenzophenone (14.8 g, 69 mmol), benzimidazolone (3.9 g, 30 mmol), bisbenzimidazole-1,10-phenanthroline (0.42 g, 1 mmol), 8.4 g of potassium carbonate, and 2.0 g of calcium carbonate into a reactor. Then, introduce nitrogen gas into the reactor and add 224 ml of N-methylpyrrolidone and 55 ml of toluene. After conducting a water-removing reaction at 140 °C for 2 hours, raise the temperature to 200 °C and react for another 4 hours to obtain a sulfonated polymer material.

[0096] Comparative Example 3

[0097] Add 4,4'-difluorodiphenyl sulfone (12.7 g, 50 mmol), 3,3'-disulfonate-4,4'-difluorodiphenyl sulfone (22.9 g, 50 mmol), 4,4'-dihydroxybenzophenone (21.4 g, 100 mmol), 8.4 g of potassium carbonate, and 2.0 g of calcium carbonate into a reactor. Then, introduce nitrogen gas into the reactor and add 220 ml of N-methylpyrrolidone and 55 ml of toluene. After conducting a water-removing reaction at 140 °C for 2 hours, raise the temperature to 200 °C and react for another 4 hours to obtain a sulfonated polymer material.

[0098] The block sulfonated polymers or sulfonated polymer materials prepared in the above Examples 1-6 and Comparative Examples 1-3 were respectively made into proton exchange membranes. Then, the performances of the prepared proton exchange membranes in terms of sulfonic acid group density, proton conductivity, oxidative stability, etc. were detected. The specific detection results are shown in Table 1.

[0099] Table 1. Performance detection results of the proton exchange membranes corresponding to Examples 1-6 and Comparative Examples 1-3

[0100]

[0101]

[0102] As can be seen from Table 1, in the block sulfonated polymers synthesized in Examples 1-3, the chain segment A2 all includes the structural unit of Formula 1, and the number of repeating units of the structural unit of Formula 1 accounts for 10% or more of the total number of all repeating units on the chain segment A2; comparing Examples 1-3 with Comparative Example 1, it can be seen that the proton exchange membranes prepared from the block sulfonated polymers synthesized in Examples 1-3 respectively have significantly better proton conductivity and mass loss after Fenton test than those of the proton exchange membranes prepared from the block sulfonated polymers synthesized in Comparative Example 1; it shows that the proton exchange membranes prepared from the block sulfonated polymers synthesized in Examples 1-3 have more excellent performances; furthermore, it shows that introducing the structural unit of Formula 1 on the chain segment A2 can assist in constructing an ion transport channel containing micropores through the rigidity and nonlinearity of the benzimidazole structure to improve its proton conductivity; and introducing the structural unit of Formula 1 can effectively reduce the proportion of ether bonds in the main chain of the chain segment A2, thereby reducing the probability of the proton exchange membrane being attacked by free radicals such as OH· and OOH·, and improving the problem of insufficient chemical stability caused by the main chain breakage of the block sulfonated polymer due to being attacked by free radicals such as OH· and OOH·.

[0103] Example 4 is based on Example 2, and a nitrogen-containing heterocyclic structural unit of Formula 2 is further introduced into the main chain of the chain segment A2; comparing Example 4 with Example 2, it can be seen that although the proton conductivity of the proton exchange membrane prepared from the block sulfonated polymer synthesized in Example 4 is slightly lower than that of the proton exchange membrane prepared from the block sulfonated polymer synthesized in Example 2, its mass loss after Fenton test is significantly lower than that of the proton exchange membrane prepared from the block sulfonated polymer synthesized in Example 2 after Fenton test; it shows that further introducing the nitrogen-containing heterocyclic structural unit of Formula 2 into the main chain of the chain segment A2, the nitrogen heterocycle and benzimidazole form a synergistic effect, which can further improve the chemical stability of the proton exchange membrane.

[0104] Example 5 is based on Example 4, and structural units of Formula 3 and Formula 4 containing benzimidazole structures are also introduced into the main chain of segment A1; comparing Example 5 with Example 4, it can be seen that for the proton exchange membrane prepared from the block sulfonated polymer synthesized in Example 5 as the raw material, its proton conductivity and mass loss after Fenton test are significantly better than those of the proton exchange membrane prepared from the block sulfonated polymer synthesized in Example 4 as the raw material. Furthermore, it shows that introducing structural units of Formula 3 and / or Formula 4 containing benzimidazole structures into the main chain of segment A1 can further improve the proton conductivity and further reduce the mass loss after Fenton test.

[0105] Compared with Example 5, in Example 6, the benzophenone structural unit is replaced with a diphenyl sulfone structural unit; the proton exchange membrane prepared from the block sulfonated polymer synthesized in Example 6 as the raw material still has a relatively low mass loss after testing and a relatively high proton conductivity. Comparing Example 6 with Comparative Example 2, it can be seen that the sulfonated polymer material synthesized in Comparative Example 2 has the same and similar proportion of repeating units as the block sulfonated polymer synthesized in Example 6, but the difference is that the arrangement and connection order between its repeating units are random; although the proton conductivity of the proton exchange membrane made from the sulfonated polymer material synthesized in Comparative Example 2 has decreased by nearly half; however, because the sulfonated polymer material contains structural units of Formula 1, Formula 2, Formula 3, and Formula 4, the mass loss of the proton exchange membrane made from it after Fenton test can still remain at a relatively low level. Comparing Example 6 with Comparative Example 3, it can be seen that the sulfonated polymer material synthesized in Comparative Example 3 does not contain structural units of Formula 1, Formula 2, Formula 3, Formula 4, etc., and the remaining repeating units are the same and in a similar proportion as the block sulfonated polymer synthesized in Example 6, but the arrangement and connection order between its repeating units are random; the proton conductivity of the proton exchange membrane made from the sulfonated polymer material synthesized in Comparative Example 3 has decreased to 67, and the mass loss after Fenton test has increased to 16.8%. It can be seen from this that the block sulfonated polymer synthesized in this application and the proton exchange membrane made from it have more excellent proton conductivity and chemical stability.

[0106] The above embodiments are only used to illustrate the technical concept and features of the present invention. The purpose is to enable those who are familiar with this technology to understand the content of the present invention and implement it accordingly, and it should not be used to limit the protection scope of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, from any point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to embrace all changes that fall within the meaning and scope of the equivalent elements of the claims within the present invention.

Claims

1. A block sulfonated polymer, characterized in that: The block sulfonated polymer includes a segment A1 and a segment A2; the segment A2 includes One or two of the following: the segment A1 includes wherein X1 represents a carbonyl group or a sulfone group, and Y1 represents a nitrogen-containing heterocyclic unit.

2. A block sulfonated polymer according to claim 1, characterized in that: On the segment A2, the number of the formula 1 and the formula 2 accounts for more than 10% of the total number of repeating units on the segment A2; On the segment A1, the number of the formula 3 and the formula 4 accounts for more than 0.3% of the total number of repeating units on the segment A1.

3. A block sulfonated polymer according to claim 2, characterized in that: The nitrogen-containing heterocyclic unit is Any one of .

4. A block sulfonated polymer according to claim 2, characterized in that: The chain segment A1 also includes Wherein, Y2 is any one of a carbonyl group, an isopropylidene group, a hexafluoroisopropylidene group, and a directly connected carbon chain structure; and n is 0 or 1.

5. A block sulfonated polymer according to claim 2, characterized in that: The density of sulfonic acid groups on the block sulfonated polymer is 0.3-2.8 mmol / g.

6. The method for synthesizing a block sulfonated polymer according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1, adding the weighed disulfonated aromatic dihalogen monomer, aromatic dihydroxy monomer, and benzimidazole structural unit-containing monomer into a reaction container, and then adding an organic solvent and a catalyst in sequence, and then stirring at 140° C.-200° C. for 2-10 hours to carry out a condensation polymerization reaction; S2. After the reaction is completed, first add an organic solvent to the reaction container for dilution, then add a fluorine-containing organic compound, and react at 70-120° C. for 1-5 hours. Then, add a diluent to precipitate and precipitate the segment A1 oligomer with fluorine ends at both ends in the reaction solution, and then filter, wash, and dry to obtain the segment A1 oligomer with fluorine ends at both ends for standby use; S3, adding the weighed dihalogen aromatic monomer, aromatic dihydroxy monomer, and benzimidazole structural unit-containing monomer into a reaction container, and then adding an organic solvent and a catalyst in sequence, stirring at 140° C.-200° C. for 2-10 hours to carry out a condensation polymerization reaction, and after the reaction is completed, adding a diluent to precipitate and precipitate the segment A2 oligomer in the reaction solution, and then filtering, washing, and drying to obtain the segment A2 oligomer for standby use; S4, adding the weighed segment A1 oligomer obtained in S2 and the segment A2 oligomer obtained in S3 into a reactor, and then sequentially adding an organic solvent and a catalyst, stirring at 70-120° C. for 2-10 hours to carry out a condensation polymerization reaction; S5. After the reaction is completed, a diluent is added to separate and precipitate the block sulfonated polymer in the reaction solution, and then filtered, washed, and dried to obtain a block sulfonated polymer; Wherein, the catalyst is an alkaline inorganic salt or an organic reagent.

7. The method for synthesizing a block sulfonated polymer according to claim 6, characterized in that: The disulfonated aromatic dihalogen monomer is any one or more of 3,3'-sodium disulfonate-4,4'-difluorobenzophenone, 3,3'-sodium disulfonate-4,4'-difluorodiphenyl sulfone, 3,3'-sodium disulfonate-4,4'-dichlorobenzophenone, and 3,3'-sodium disulfonate-4,4'-dichlorodiphenyl sulfone; The aromatic dihydroxy monomer is any one or more of 4,4'-dihydroxybiphenyl, 4,4'-dihydroxybenzophenone, bisphenol A, and bisphenol AF; The benzimidazole structural unit-containing monomer is any one or more of benzimidazolone and a nitrogen-containing heterocyclic bisbenzimidazole monomer; The structural formula of the nitrogen-containing heterocyclic bisbenzimidazole monomer is The dihalogen aromatic monomer is any one or more of 4,4'-difluorobenzophenone, 4,4'-difluorodiphenyl sulfone, 4,4'-dichlorobenzophenone, and 4,4'-dichlorodiphenyl sulfone; The fluorine-containing organic compound is decafluorobiphenyl or hexafluorobenzene.

8. The method for synthesizing a block sulfonated polymer according to claim 6, characterized in that: The organic solvent is any one or more of dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, sulfolane, diphenyl sulfone, toluene, and cyclohexane; The diluent is any one of deionized water, methanol, ethanol, isopropanol, n-butanol, and acetone; The inorganic salt is any one or more of potassium carbonate, sodium carbonate and calcium carbonate.

9. A proton exchange membrane, characterized in that: Made from the block sulfonated polymer described in any one of claims 1 to 4.

10. The use of the proton exchange membrane according to claim 9, characterized in that: This includes the application of the proton exchange membrane in fuel cells, proton exchange membrane electrolyzers, and liquid flow batteries.

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