All-carbon-carbon-connected sulfonated polymer as well as synthesis method and application thereof

Abstract

The invention relates to the technical field of high polymer materials, in particular to an all-carbon-carbon-connected sulfonated polymer and a synthesis method and application thereof, and a main chain of the sulfonated polymer comprises a plurality of Ar1 structural units, a plurality of Ar2 structural units and a plurality of Ar3 structural units; the Ar < 1 > structural unit is a unit containing a sulfonated phenylene structure; the Ar2 structural unit is a unit containing a biphenyl structure; the Ar3 structural unit is a unit containing a stilbene structure. By virtue of the rigid characteristic of a biphenyl structure and the flexible characteristic of an olefin structure, the sulfonated polymer is endowed with good deformation capacity, so that the sulfonated polymer material has relatively high stability and toughness and good air tightness; the proton exchange membrane prepared based on the sulfonated polymer has relatively high proton conductivity and chemical durability and excellent toughness; the problems that an existing sulfonated hydrocarbon ion polymer is low in chemical stability, poor in durability and the like are solved.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to a fully carbon-carbon-connected sulfonated polymer and a synthesis method and application thereof. Background Art

[0002] Proton exchange membrane (PEM) plays a vital role in electrochemical devices such as water electrolysis, hydrogen production, fuel cells, flow batteries, and electrodialysis. It is mainly responsible for transmitting protons, blocking electrons and reaction gases; its cost, performance, and durability directly determine the performance and service life of electrochemical devices. Currently, the commonly used proton exchange membrane is made of perfluorosulfonic acid (PFSA) material, such as the product named Perfluorosulfonic acid proton exchange membrane (PFSA membrane); however, the preparation cost of PFSA materials is high, which will affect the overall economic efficiency of proton exchange membranes; in addition, PFSA membranes have low tensile strength, and their degradation products are also more polluting to the environment. Compared with PFSA materials, sulfonated hydrocarbon ion polymers have significant advantages, such as low preparation cost, higher mechanical properties, and more environmentally friendly. However, sulfonated hydrocarbon ion polymers have obvious deficiencies in chemical stability. Since the main chain of sulfonated hydrocarbon ion polymers usually contains more ether bonds, free radicals such as OH· and OOH· will attack the ether bonds on its main chain during electrochemical reactions, thereby degrading the ether bonds of the sulfonated polymers and destroying their chemical stability and durability.

[0003] With the development of polymer material technology, sulfonated hydrocarbon ion polymers with a full carbon-carbon structure without ether bonds on the main chain have become a hot spot for the development of proton exchange membrane raw materials due to their extremely high chemical stability and durability due to their fewer oxidation reaction sites. However, the rigidity of the main chain of the fully aromatic carbon-carbon-connected sulfonated hydrocarbon ion polymer material is too large, which will lead to the brittleness of the sulfonated hydrocarbon ion polymer material; when the sulfonic acid group density of the sulfonated hydrocarbon ion polymer is high, the proton exchange membrane made from it as raw material is prone to mechanical deterioration during actual use, which in turn affects the use effect and service life of the proton exchange membrane.

[0004] The invention provides a fully carbon-carbon linked sulfonated polymer and a synthesis method and application thereof, so as to solve the problems of low chemical stability, poor durability and poor mechanical properties of the existing sulfonated hydrocarbon ion polymers in the prior art. Summary of the invention

[0005] The purpose of the present invention is to provide a fully carbon-carbon linked sulfonated polymer and a synthesis method and application thereof, so as to solve the problems of the existing sulfonated hydrocarbon ion polymers in the prior art, such as low chemical stability, poor durability, poor mechanical properties, etc.

[0006] The technical solution of the present invention is: a fully carbon-carbon linked sulfonated polymer, and the main chain of the sulfonated polymer includes: several Ar1 structural units, several Ar2 structural units, and several Ar3 structural units; the Ar1 structural unit is a unit containing a sulfonated phenylene structure; the Ar2 structural unit is a unit containing a biphenyl structure; the Ar3 structural unit is a unit containing a stilbene structure.

[0007] Preferably, the Ar1 structural unit is any one or more of;

[0008] The structural formula of the Ar3 structural unit is

[0009] The Ar2 structural unit is any one or more of;

[0010] Among them, the benzene rings in structural formulas E-1 to E-5 do not contain substituents or one or more of the benzene rings in structural formulas E-1 to E-5 contain substituents other than sulfonic acid groups.

[0011] Preferably, on the main chain of the sulfonated polymer, the number of repeating units of the Ar3 structural unit accounts for 5-30% of the total number of repeating units on the main chain of the sulfonated polymer.

[0012] Preferably, the substituent group is trifluoromethyl or methyl.

[0013] Preferably, the density of sulfonic acid groups in the sulfonated polymer is 1-3 mmol / g.

[0014] The present invention also provides a synthesis method of the above-mentioned fully carbon-carbon linked sulfonated polymer, including the following steps:

[0015] S1. Add a dihalogen monomer containing an Ar1 structural unit, a dihalogen monomer containing an Ar2 structural unit, and a dihalogen monomer containing an Ar3 structural unit to a reactor, and then sequentially add a catalyst and an organic solvent to the reaction vessel. Then, stir for several hours at 120-180 °C to carry out a dehydration pre-synthesis reaction to obtain a pre-synthesis reaction solution;

[0016] S2. First, cool the temperature of the obtained pre-synthesis reaction solution to 50-100 °C, then add a metal catalyst to the pre-synthesis reaction solution, and then continue to stir for several hours to carry out a coupling reaction. After the coupling reaction ends, a mixed solution containing the sulfonated polymer is obtained;

[0017] S3. Cool the obtained mixture and then add it to a hydrochloric acid solution for precipitation to obtain a crude sulfonated polymer. Then, perform filtration, washing, and drying treatments in sequence to obtain the sulfonated polymer.

[0018] The catalyst includes 2,2'-bipyridine and an inorganic salt that is alkaline.

[0019] Preferably, the dihalogen monomer containing the Ar1 structural unit is any one or more of 2,5-dichlorobenzenesulfonic acid, 2,5-dibromobenzenesulfonic acid, 2,5-dichlorobenzene-1,4-disulfonic acid, 2,5-dibromobenzene-1,4-disulfonic acid, 5,5'-carbonylbis(2-chlorobenzenesulfonic acid), 5,5'-carbonylbis(2-bromobenzenesulfonic acid);

[0020] Preferably, the structural formula of the dihalogen monomer containing the Ar2 structural unit is

[0021] wherein M is a halogen, and the benzene ring in the structural formulas E-11 to E-51 does not contain substituents or one or more of the benzene rings in the structural formulas E-11 to E-51 contain substituents other than sulfonic acid groups;

[0022] The dihalogen monomer containing the Ar3 structural unit is 1,2-bis(4-chlorophenyl)ethylene and / or 1,2-bis(4-bromophenyl)ethylene.

[0023] Preferably, the organic solvent is any one or more of dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, sulfolane, diphenyl sulfone, toluene, cyclohexane;

[0024] The inorganic salt is any one or more of potassium carbonate, sodium carbonate, calcium carbonate.

[0025] Preferably, the metal catalyst is bis(1,5-cyclooctadiene)nickel.

[0026] The present invention also provides an application of the above-mentioned all-carbon-carbon-linked sulfonated polymer, including its application in an electrochemical device after being made into a proton exchange membrane.

[0027] Compared with the prior art, the advantages of the present invention are:

[0028] A sulfonated polymer with all-carbon-carbon linkages, its synthesis method and application provided by the present invention. The main chain of the sulfonated polymer simultaneously includes an Ar1 structural unit containing a sulfonic acid group, an Ar2 structural unit with a biphenyl structure, and an Ar3 structural unit with an olefin structure. Relying on the rigid characteristics of the biphenyl structure and the flexible characteristics of the olefin structure, the sulfonated polymer is endowed with good deformation ability, making the sulfonated polymer material have high stability and toughness. The rigid biphenyl structure and the flexible olefin structure cooperate with each other, and can also make the sulfonated polymer material have good airtightness and high thermomechanical stability. At the same time, the sulfonic acid group density of the sulfonated polymer is adjustable, and its main chain structure does not contain ether bonds. This design can further optimize the performance of the sulfonated polymer material, making the proton exchange membrane made of the sulfonated polymer have high proton conductivity, chemical durability and excellent toughness, and making the proton exchange membrane have a broader application prospect, solving the problems of low chemical stability, poor durability and poor mechanical properties existing in the existing sulfonated carbon-hydrogen ion polymers in the prior art. Detailed implementation manners

[0029] The following combines specific embodiments to further elaborate on the content of the present invention:

[0030] It should be noted that the preparation process of preparing the sulfonated polymer solid materials obtained by purification in the following Examples 1-6 and Comparative Examples 1-2 into proton exchange membranes is as follows: The sulfonated polymer solid materials obtained by purification 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, and then washed with a large amount of deionized water and dried to obtain a proton exchange membrane.

[0031] 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; the sulfonic acid group density (mmol / g) = (V1x0.01mol / L) / M1; each proton exchange membrane is tested three times and the average value is taken.

[0032] It should be noted that the proton conductivity test method of the proton exchange membrane is as follows: Cut the membrane into 1 cm x 4 cm strips and clamp them in the test mold. Use platinum as the electrode, put the test mold into a constant temperature and humidity chamber, and place it for more than 30 minutes at 80 °C and a relative humidity of 95%; then, when the AC amplitude is 50 mV, measure the AC impedance spectrum to obtain the impedance value R of the thin film. The proton conductivity σ = (L / R x A), 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.

[0033] It should be noted that the oxidation 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 and record W0 for three pieces of dried proton exchange membranes of about 20 mg each; in an 80 °C environment, put the proton exchange membranes into Fenton's reagent (3% H2O2, 3 ppm Fe 2+ )), take out one proton exchange membrane every 1 h, rinse it with deionized water and soak it for 24 h, repeat three times, then soak it in 1 mol / L HCl for 24 h, repeat three times; finally, vacuum dry the proton exchange membranes overnight at 80 °C, weigh and record W1, and calculate the mass change: Mass loss = (W0 - W1) / W0 x 100%.

[0034] A fully carbon-carbon linked sulfonated polymer, and the structural formula of the sulfonated polymer is That is, the main chain of the sulfonated polymer includes several Ar1 structural units, several Ar2 structural units, and several Ar3 structural units. Among them, the Ar1 structural unit is a unit containing a sulfonated phenylene structure; the Ar2 structural unit is a unit containing a biphenyl structure; the Ar3 structural unit is a unit containing a stilbene structure.

[0035] The Ar1 structural unit is One or more of the following structural formulas; Considering from the perspectives of the mechanical properties and proton conduction properties of the proton exchange membrane, the structural formula of the Ar1 structural unit is preferably Considering from the perspective of the high airtightness of the proton exchange membrane, the Ar3 structural unit may contain a trans-stilbene structure or a cis-stilbene structure; its specific structural formula is preferably The structural formula of the Ar2 structural unit is

[0036] One or more of the following structural formulas; wherein, the benzene rings in the structural formulas E-1 to E-5 may not contain substituents, or one or more of the benzene rings may contain any substituent groups such as alkyl groups, trifluoromethyl groups, etc. other than sulfonic acid groups. Considering the mechanical properties and chemical stability of the proton exchange membrane, it is preferred that some of the benzene rings in the structural formulas shown in E-1 to E-5 of the Ar2 structural unit are substituted by trifluoromethyl (-CF3) or methyl (-CH3).

[0037] In this application, on the main chain of the all-carbon-carbon-linked sulfonated polymer, the number of repeating units of the Ar3 structural unit accounts for 5-30% of the total number of all repeating units on the main chain of the sulfonated polymer; and when the proportion of the number of repeating units of the Ar3 structural unit on the main chain of the sulfonated polymer is relatively low, there are obvious deficiencies in the toughness of the sulfonated polymer material; while when the proportion of the number of repeating units of the Ar3 structural unit on the main chain of the sulfonated polymer is too high, the solubility of the sulfonated polymer material decreases, which will further lead to problems such as difficulty in film formation and low mechanical strength. Therefore, starting from the toughness, solubility and other properties of the all-carbon-carbon-linked sulfonated polymer material, it is preferred that the number of repeating units of the Ar3 structural unit accounts for 10-20% of the total number of all repeating units on the main chain of the all-carbon-carbon-linked sulfonated polymer.

[0038] A structural unit refers to the basic composition unit in which monomer molecules enter the polymer main chain through a polymerization reaction, such as the Ar1 structural unit, the Ar2 structural unit, the Ar3 structural unit, etc.; a repeating unit refers to the smallest basic composition unit that repeats in chemical composition and structure on the polymer main chain, and can also be called a chain link; it can be composed of one or more structural units. In this application, the repeating unit refers to the structural units such as the Ar1 structural unit, the Ar2 structural unit, the Ar3 structural unit, etc. that repeat on the main chain of the all-carbon-carbon-linked sulfonated polymer; the total number of all repeating units on the main chain of the all-carbon-carbon-linked sulfonated polymer refers to the sum of the numbers of structural units such as the Ar1 structural unit, the Ar2 structural unit, the Ar3 structural unit, etc. that repeat on the main chain.

[0039] Considering the high proton conductivity, high mechanical properties and chemical durability of the proton exchange membrane, the density of sulfonic acid groups in the sulfonated polymer needs to be controlled within the range of 1-3 mmol / g; wherein, 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.

[0040] This application also provides a synthesis method of an all-carbon-carbon-linked sulfonated polymer, and the synthesis method specifically includes the following steps:

[0041] S1. Weigh the dihalogen monomers containing Ar1 structural units, dihalogen monomers containing Ar2 structural units, and dihalogen monomers containing Ar3 structural units respectively according to a ratio. Then add the weighed dihalogen monomers containing Ar1 structural units, dihalogen monomers containing Ar2 structural units, and dihalogen monomers containing Ar3 structural units into a reactor equipped with an oil-water separator. Next, add a catalyst and an organic solvent to the reaction vessel in sequence. After that, under the condition of 120 - 180 °C, stir for 1 - 4 h to carry out a dehydration pre-synthesis reaction to obtain a pre-synthesis reaction solution. Among them, the catalyst includes 2,2'-bipyridine and an inorganic salt with alkalinity. The inorganic salt with alkalinity can be one or more of potassium carbonate, sodium carbonate, calcium carbonate, etc. The organic solvent is one or more of dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, sulfolane, diphenyl sulfone, toluene, cyclohexane, etc.

[0042] S2. First, cool the temperature of the obtained pre-synthesis reaction solution to 50 - 100 °C, then add a metal catalyst to the cooled pre-synthesis reaction solution. After that, continue to stir for 2 - 6 hours under the condition of 50 - 100 °C to carry out a coupling reaction. After the coupling reaction ends, a mixed solution containing a sulfonated polymer is obtained. Among them, the metal catalyst is one of bis(1,5-cyclooctadiene)nickel, octadienediylnickel(II), diimine Ni(II) complex, etc. It is preferred to use bis(1,5-cyclooctadiene)nickel as the metal catalyst.

[0043] S3. Purify the obtained mixed solution containing a sulfonated polymer, that is, first cool the obtained mixed solution to room temperature, and then slowly add it to a large amount of hydrochloric acid solution with a concentration of 5 - 7 mol / L for precipitation to obtain a crude sulfonated polymer. Then, first filter the crude sulfonated polymer, and then wash it repeatedly with concentrated hydrochloric acid and deionized water. Then place the washed solid in a drying device for drying. After vacuum drying for several hours, a solid material of the sulfonated polymer is obtained.

[0044] From the perspective of the reaction difficulty of synthesizing sulfonated polymers and the availability and cost of dihalogen monomers containing Ar1 structural units, dihalogen monomers containing Ar2 structural units, and dihalogen monomers containing Ar3 structural units, in step S1, the dihalogen monomers containing Ar1 structural units, the dihalogen monomers containing Ar2 structural units, and the dihalogen monomers containing Ar3 structural units preferably use their corresponding dibromo monomers or dichloro monomers. Specifically, the dihalogen monomer containing Ar1 structural units preferably uses one or more of 2,5-dichlorobenzenesulfonic acid, 2,5-dibromobenzenesulfonic acid, 2,5-dichlorobenzene-1,4-disulfonic acid, 2,5-dibromobenzene-1,4-disulfonic acid, 5,5'-carbonylbis(2-chlorobenzenesulfonic acid), 5,5'-carbonylbis(2-bromobenzenesulfonic acid), etc.; the dihalogen monomer containing Ar3 structural units preferably uses 1,2-bis(4-chlorophenyl)ethylene and / or 1,2-bis(4-bromophenyl)ethylene; from the perspective of the high airtightness of the proton exchange membrane, the dihalogen monomer containing Ar3 structural units preferably uses trans-1,2-bis(4-chlorophenyl)ethylene and / or trans-1,2-bis(4-bromophenyl)ethylene. The structural formula of the dihalogen monomer containing Ar2 structural units is wherein, M is a halogen, the benzene ring in the structural formulas E-11 to E-51 may not contain substituents, or one or more of the benzene rings in the structural formulas E-11 to E-51 may also contain substituents other than sulfonic acid groups; and, the dihalogen monomer containing Ar2 structural units preferably uses the structural monomers in which M is Cl or Br in the structural formulas E-11 to E-51.

[0045] The present application also provides the application of the above-mentioned all-carbon-carbon-linked sulfonated polymer, including dissolving the all-carbon-carbon-linked sulfonated polymer with an organic solvent to prepare a membrane-forming solution, preparing a proton exchange membrane in a base membrane material by a casting method, and then applying the prepared proton exchange membrane to an electrochemical device.

[0046] Example 1

[0047] S1. Weigh 2,5-dichlorobenzenesulfonic acid (11.3 g, 50 mmol), 4,4'-dibromo-2,2'-bis(trifluoromethyl)-1,1'-biphenyl (22.4 g, 50 mmol), trans-1,2-bis(4-bromophenyl)ethylene (4 g, 12 mmol), 8.4 g of potassium carbonate, and 3.9 g of 2,2'-bipyridine, and add them to the reactor in sequence. Then, introduce nitrogen into the reactor and add 200 mL of N-methylpyrrolidone and 45 mL of toluene; thereafter, stir at 150 °C for several hours to carry out a dehydration pre-synthesis reaction to obtain a pre-synthesis reaction solution;

[0048] S2. First, cool the temperature of the obtained pre-synthesis reaction solution to 80 °C, then add 4.5 g of bis(1,5-cyclooctadiene)nickel to the pre-synthesis reaction solution. After that, continue stirring for several hours at 80 °C to carry out the coupling reaction. After the coupling reaction ends, a mixed solution containing the sulfonated polymer is obtained;

[0049] S3. Cool the obtained mixed solution and add it to a hydrochloric acid solution for precipitation to obtain a crude sulfonated polymer. Then, perform filtration, washing, and drying treatments in sequence to obtain the sulfonated polymer, P1.

[0050] In Examples 2-6, the same synthesis method as in Example 1 was used to synthesize sulfonated polymers P2-P6 respectively.

[0051] Comparative Example 1

[0052] S1. Weigh 2,5-dichlorobenzenesulfonic acid (11.3 g, 50 mmol), 4,4”-dichloro-1,1':4',1”-terphenyl (14.9 g, 50 mmol), potassium carbonate 8.4 g, 2,2'-bipyridine 3.9 g, and add them to the reactor in sequence. Then, introduce nitrogen into the reactor and add 200 mL of N-methylpyrrolidone and 45 mL of toluene. After that, stir for several hours at 150 °C to carry out the dehydration pre-synthesis reaction to obtain a pre-synthesis reaction solution;

[0053] S2. First, cool the temperature of the obtained pre-synthesis reaction solution to 80 °C, then add 4.5 g of bis(1,5-cyclooctadiene)nickel to the pre-synthesis reaction solution. After that, continue stirring for several hours at 80 °C to carry out the coupling reaction. After the coupling reaction ends, a mixed solution containing the sulfonated polymer is obtained;

[0054] S3. Cool the obtained mixed solution and add it to a hydrochloric acid solution for precipitation to obtain a crude sulfonated polymer. Then, perform filtration, washing, and drying treatments in sequence to obtain the sulfonated polymer, Q1.

[0055] Comparative Example 2

[0056] S1. Weigh 5,5'-carbonylbis(2-chlorobenzenesulfonic acid) (20.5 g, 50 mmol), 4,4'-dibromo-2,2'-bis(trifluoromethyl)-1,1'-biphenyl (22.4 g, 50 mmol), potassium carbonate 8.4 g, 2,2'-bipyridine 3.9 g, and add them to the reactor in sequence. Then, introduce nitrogen into the reactor and add 200 mL of N-methylpyrrolidone and 45 mL of toluene. After that, stir for several hours at 150 °C to carry out the dehydration pre-synthesis reaction to obtain a pre-synthesis reaction solution;

[0057] S2. First, cool the temperature of the obtained pre-synthesis reaction solution to 80 °C, then add 4.5 g of bis(1,5-cyclooctadiene)nickel to the pre-synthesis reaction solution. After that, continue stirring for several hours at 80 °C to carry out the coupling reaction. After the coupling reaction ends, a mixed solution containing the sulfonated polymer is obtained;

[0058] S3. After cooling the obtained mixed solution, add it to a hydrochloric acid solution for precipitation to obtain a crude product of the sulfonated polymer. Then, perform filtration treatment, washing treatment, and drying treatment in sequence to obtain the sulfonated polymer, Q2.

[0059] For the sulfonated polymers P1 - P6 synthesized in Examples 1 - 6 above and the sulfonated polymers Q1 - Q2 synthesized in Comparative Examples 1 - 2, the structural formulas of the Ar1 structural unit, Ar2 structural unit, and Ar3 structural unit on the main chain and the proportion of the number of repeating units of the Ar1 structural unit, Ar2 structural unit, and Ar3 structural unit on the main chain are shown in Table 1.

[0060] Table 1. Structural formulas and proportions of different structural units on the main chain of the synthesized sulfonated polymers

[0061]

[0062] Respectively fabricate the sulfonated polymers P1 - P6 synthesized in Examples 1 - 6 above and the sulfonated polymers Q1 - Q2 synthesized in Comparative Examples 1 - 2 into proton exchange membranes, and detect the performance of the proton exchange membranes. The test results are shown in Table 2.

[0063] Table 2. Performance test results of the proton exchange membranes fabricated from the synthesized sulfonated polymers

[0064]

[0065] As can be seen from Table 1, for the sulfonated polymers P1-P6 synthesized in Examples 1-6, their main chains all include a number of Ar1 structural units, a number of Ar2 structural units, and a number of Ar3 structural units; for the sulfonated polymers Q1-Q2 synthesized in Comparative Examples 1-2, their main chains only include a number of Ar1 structural units and a number of Ar2 structural units. As can be seen from Table 2, compared with the proton exchange membranes made from the sulfonated polymers Q1-Q2 synthesized in Comparative Examples 1-2, the proton exchange membranes made from the sulfonated polymers P1-P6 synthesized in Examples 1-6 have better toughness, higher chemical durability and proton conductivity; it shows that the main chain of the fully carbon-carbon linked sulfonated polymer has both a rigid biphenyl structure and a flexible olefin structure, which can endow the sulfonated polymer solid material itself with good airtightness and excellent thermomechanical stability; combined with the adjustable sulfonic acid group density in the sulfonated polymer, it endows the proton exchange membrane made from it with excellent toughness and high proton conductivity; at the same time, because the main chain of the sulfonated polymer solid material does not contain ether bonds, the proton exchange membrane made from it has extremely high chemical durability.

[0066] Comparing the proton exchange membrane made from the sulfonated polymer P1 synthesized in Example 1 with the proton exchange membrane made from the sulfonated polymer P2 synthesized in Example 2, it can be seen that increasing the sulfonic acid group density of the sulfonated polymer, although the mass loss of its proton exchange membrane slightly increases after the Fenton test, can significantly improve the proton conductivity of its proton exchange membrane; moreover, the toughness and thermomechanical stability of this proton exchange membrane are also significantly improved. Comparing the proton exchange membrane made from the sulfonated polymer P2 synthesized in Example 2 with the proton exchange membrane made from the sulfonated polymer P3 synthesized in Example 3, it can be seen that when ensuring that the sulfonic acid group density of the sulfonated polymer is basically equivalent, increasing the repeating unit percentage of the Ar3 structural unit on the main chain of the sulfonated polymer can significantly improve the toughness of its corresponding proton exchange membrane; however, the higher the proportion of the number of repeating units of the Ar3 structural unit on the main chain of the sulfonated polymer is not necessarily better; specifically, for example, comparing the performances of the proton exchange membranes made from the sulfonated polymers P1, P3, P4, and P5 synthesized in Examples 1, 3, 4, and 5 respectively, when the percentage of the number of repeating units of the Ar3 structural unit on the main chain of the sulfonated polymer is relatively high, the solubility of the sulfonated polymer decreases, making the sulfonated polymer unable to dissolve in organic solvents and be made into a proton exchange membrane; therefore, to ensure that the sulfonated polymer has high solubility, the percentage of the number of repeating units of the Ar3 structural unit on the main chain of this sulfonated polymer should not exceed 30%; and, to ensure that its corresponding proton exchange membrane has high toughness, high proton conductivity, and low mass loss after the Fenton test, the percentage of the number of repeating units of the Ar3 structural unit on the main chain of the sulfonated polymer is preferably not more than 20%. In addition, comparing the performance of the proton exchange membrane made from the sulfonated polymer P6 synthesized in Example 6 with the performance of the proton exchange membranes made from the sulfonated polymers P1 - P5 synthesized in Examples 1 - 5, it can be seen that to ensure that the proton exchange membrane has high toughness, the percentage of the number of repeating units of the Ar3 structural unit on the main chain of the sulfonated polymer should be not less than 5%; more preferably, the percentage of the number of repeating units of the Ar3 structural unit on the main chain of the sulfonated polymer should be not less than 10%.

[0067] 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 features 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 in the present invention.

Claims

1. A fully carbon-carbon linked sulfonated polymer, characterized in that, The main chain of the sulfonated polymer includes: a number of Ar1 structural units, a number of Ar2 structural units, and a number of Ar3 structural units; the Ar1 structural unit is a unit containing a sulfonated phenylene structure; the Ar2 structural unit is a unit containing a biphenyl structure; the Ar3 structural unit is a unit containing a stilbene structure.

2. A fully carbon-carbon linked sulfonated polymer according to claim 1, wherein The Ar1 structural unit is any one or more of; The structural formula of the Ar3 structural unit is The Ar2 structural unit is any one or more of; Among them, the benzene ring in Structural Formulas E-1 to E-5 does not contain substituents or one or more of the benzene rings in Structural Formulas E-1 to E-5 contain substituents other than sulfonic acid groups.

3. The sulfonated polymer with all-carbon-carbon linkages according to claim 2, characterized in that, On the main chain of the sulfonated polymer, the number of repeating units of the Ar3 structural unit accounts for 5-30% of the total number of repeating units on the main chain of the sulfonated polymer.

4. The sulfonated polymer with all-carbon-carbon linkages according to claim 2, characterized in that, The substituent group is trifluoromethyl or methyl.

5. The sulfonated polymer with all-carbon-carbon linkages according to claim 1, characterized in that, The density of sulfonic acid groups in the sulfonated polymer is 1-3 mmol / g.

6. A method for synthesizing a fully carbon-carbon linked sulfonated polymer according to any one of claims 1-5, characterized in that, It includes the following steps: S1. Add the dihalogen monomer containing the Ar1 structural unit, the dihalogen monomer containing the Ar2 structural unit, and the dihalogen monomer containing the Ar3 structural unit into a reactor, and then sequentially add a catalyst and an organic solvent into the reaction vessel. After that, stir for several hours at 120-180 °C to carry out a dehydration pre-synthesis reaction to obtain a pre-synthesis reaction solution; S2. First, cool the temperature of the obtained pre-synthesis reaction solution to 50-100 °C, then add a metal catalyst into the pre-synthesis reaction solution, and then continue to stir for several hours to carry out a coupling reaction. After the coupling reaction ends, obtain a mixed solution containing the sulfonated polymer; S3. Cool the obtained mixed solution and add it to a hydrochloric acid solution for precipitation to obtain a crude sulfonated polymer. After that, carry out filtration treatment, washing treatment, and drying treatment in sequence to obtain the sulfonated polymer. The catalyst includes 2,2'-bipyridine and an inorganic salt that is alkaline.

7. The synthesis method of the all-carbon-carbon-linked sulfonated polymer according to claim 6, characterized in that, The dihalogen monomer containing the Ar1 structural unit is any one or more of 2,5-dichlorobenzenesulfonic acid, 2,5-dibromobenzenesulfonic acid, 2,5-dichlorobenzene-1,4-disulfonic acid, 2,5-dibromobenzene-1,4-disulfonic acid, 5,5'-carbonylbis(2-chlorobenzenesulfonic acid), 5,5'-carbonylbis(2-bromobenzenesulfonic acid); The structural formula of the dihalogen monomer containing the Ar2 structural unit is wherein M is a halogen, the benzene ring in the structural formulas E-11 to E-51 does not contain substituents, or one or more of the benzene rings in the structural formulas E-11 to E-51 contain substituents other than sulfonic acid groups; The dihalogen monomer containing the Ar3 structural unit is 1,2-bis(4-chlorophenyl)ethylene and / or 1,2-bis(4-bromophenyl)ethylene.

8. The synthesis method of the all-carbon-carbon-linked 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, cyclohexane; The inorganic salt is any one or more of potassium carbonate, sodium carbonate, calcium carbonate.

9. The synthesis method of the all-carbon-carbon-linked sulfonated polymer according to claim 6, characterized in that: The metal catalyst is bis(1,5-cyclooctadiene)nickel.

10. Use of the all-carbon-carbon-linked sulfonated polymer according to any one of claims 1-5, characterized in that, It includes the application in an electrochemical device after being made into a proton exchange membrane.

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