Sulfonated polysulfone without floating foam during film forming and preparation method thereof

Abstract

The invention discloses sulfonated polysulfone without floating foam during film forming and a preparation method thereof, and relates to the technical field of sulfonated polysulfone. According to the invention, a sulfonated monomer SDCDPS is used for replacing part of DCDPS and is copolymerized with bisphenol A, and the sulfonation degree is 1-5%; when methyl chloride is adopted for blocking after polymerization is completed, a quaternary ammonium salt catalyst TBAB and ionic liquid are added, so that the blocking activity of methyl chloride on sulfonated polysulfone and small-molecule sulfonated polysulfone in the polymerization process is improved, and the content of unblocked small-molecule sulfonated polysulfone is reduced; in the washing process of the sulfonated polysulfone, a mixed system of a polar aprotic solvent and water in a proper proportion is adopted for post-treatment, the content of small molecules in the sulfonated polysulfone is further reduced, the generation of floating foam is finally reduced, and the application of the sulfonated polysulfone in downstream membrane preparation is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of sulfonated polysulfone, in particular to sulfonated polysulfone without foam during film formation and a preparation method thereof. Background Art

[0002] Polysulfone resin (PSU) is a non-crystalline special engineering plastic. Because it contains sulfone group, isopropyl group and benzene ring, it has good antioxidant properties, mechanical properties and thermal stability. The presence of ether bond provides it with a certain toughness. Therefore, due to its excellent properties, polysulfone resin is widely used in high-end medical, electronic products, water treatment, aerospace and other fields.

[0003] Polysulfone is usually hydrophobic, and hollow fiber ultrafiltration membranes, flat membranes, etc. containing hydrophobic polysulfone have poor wettability, are easy to scale, and are difficult to clean when used for separation and filtration. Therefore, in order to improve the hydrophilicity of polysulfone, the hydrophilicity of polysulfone can be improved by introducing polar groups such as carboxyl, hydroxyl, sulfonic acid, and amino groups. Among them, sulfonated polysulfone has a long history of research and development and has been commercially produced.

[0004] The sulfonation degree of common sulfonated polysulfones on the market ranges from 5% to 100%. The polymerization process of sulfonated polysulfone is similar to that of conventional polysulfone, that is, bisphenol A, sulfonated 4,4'-dichlorodiphenyl sulfone and 4,4'-dichlorodiphenyl sulfone monomers are subjected to salt formation and nucleophilic substitution polycondensation in the presence of alkaline nucleophiles. The alkaline nucleophiles are usually potassium carbonate, and the solvents are N,N-dimethylacetamide (DMCA), N-methylpyrrolidone (NMP), etc.; after the polymerization, the polymer solution is capped with chloroform, and then separated, purified, dried, granulated and packaged to obtain the product. There are also methods that directly sulfonate the polymerized polysulfone after capping, but this method is difficult to accurately control the sulfonation degree, and it is not easy to obtain polysulfone with a low sulfonation degree. The obtained sulfonated polysulfone is easy to agglomerate and yellow, and the industrial application prospects are not good.

[0005] Sulfonated polysulfone with a sulfonation degree of more than 10% has a high hydrophilicity and poor film strength, and does not meet the use standards. Therefore, sulfonated polysulfone with a high sulfonation degree is often used as a hydrophilic additive and mixed with conventional polysulfone to form a film. However, in this type of film formation method, when the casting liquid contacts the coagulation bath (water), the hydrophilic small molecules in the highly sulfonated polysulfone are very easy to separate from the membrane body during the exchange process between the solvent and water, enter the water to form a large amount of foam, and then adhere to the membrane surface, blocking the membrane pores and reducing the membrane flux.

[0006] The hydrophilic small molecules in sulfonated polysulfone mainly come from: the high sulfonation degree polysulfone has a slow polymerization rate, a wide molecular weight distribution, and a large number of residual small molecules; the sulfonate group is large in size and has strong polarity, which will limit the non-polar methyl chloride from approaching the active site of the terminal phenolate group through physical hindrance, hindering the nucleophilic attack of methyl chloride, and the steric hindrance is obvious. In the high sulfonation degree system, the dense distribution of sulfonate groups will further aggravate the steric hindrance effect, and the terminal hydroxyl group of small molecule sulfonated polysulfone further increases its hydrophilicity. This type of hydrophilic small molecules that have not been capped are easy to detach from the membrane body to form foam during the solvent exchange process during membrane formation, affecting the membrane quality.

[0007] Therefore, it is of great significance to synthesize low-sulfonation degree polysulfone to form a single membrane, accelerate the polymerization reaction rate of sulfonated polysulfone, reduce the content of hydrophilic small molecules in sulfonated polysulfone, increase the end-capping rate of hydrophilic small molecules, and reduce the generation of foam, which is of great significance for promoting the application of sulfonated polysulfone. Summary of the invention

[0008] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art, provide a sulfonated polysulfone without foam during film formation and a preparation method thereof, the synthesized low-sulfonation-degree polysulfone can form a film alone, the sulfonated polysulfone has a low content of hydrophilic small molecules and a high end-capping rate of the hydrophilic small molecules, can reduce the generation of foam, and is conducive to its application in downstream film making.

[0009] The technical solution of the present invention is: In one aspect, the present invention provides a method for preparing a sulfonated polysulfone without foaming during film formation, comprising the following steps: S1: put bisphenol A, dichloromonomer, salt-forming agent and water-separating agent into a polar aprotic solvent, introduce protective gas, heat to 120-150°C, keep warm for 2-8 hours, and perform salt-forming reaction; after the water extraction reaches the theoretical value and the salt-forming reaction is completed, continue to heat to 160-200°C, keep warm for 2-10 hours, and perform nucleophilic polycondensation reaction to obtain sulfonated polysulfone resin polymerization liquid; wherein the salt-forming agent is cesium carbonate, potassium carbonate or sodium carbonate; the water-separating agent is toluene, xylene, trimethylbenzene, ethylbenzene or ethylbenzene; the dichloromonomer is 3,3'-sodium disulfonate-4,4'-dichlorodiphenyl sulfone (SDCDPS) and 4,4'-dichlorodiphenyl sulfone (DCDPS), and the molar percentage of 3,3'-sodium disulfonate-4,4'-dichlorodiphenyl sulfone in the dichloromonomer is 1-5%; S2: cooling the sulfonated polysulfone resin polymerization liquid, adding ionic liquid and quaternary ammonium salt catalyst tetrabutylammonium bromide (TBAB), and introducing methyl chloride for end-capping to obtain an end-capped sulfonated polysulfone resin polymerization liquid; wherein the ionic liquid is 1-butyl-3-methylimidazolium bistrifluoromethylsulfonyl imide, 1-ethyl-3-methylimidazolium bistrifluoromethylsulfonyl imide salt or N-ethylpyridine bistrifluoromethylsulfonyl imide salt; S3: crushing the blocked sulfonated polysulfone resin polymer solution, extracting with a mixed solvent, filtering, and drying to obtain a sulfonated polysulfone without foam during film formation; wherein the mixed solvent is a mixture of a polar aprotic solvent and deionized water.

[0010] Preferably, in step S2, the molar ratio of the quaternary ammonium salt catalyst tetrabutylammonium bromide to 3,3'-sodium disulfonate-4,4'-dichlorodiphenyl sulfone is (1.05-1.2):1.

[0011] Preferably, in step S1, the molar ratio of bisphenol A, dichloro monomer and salt-forming agent is 1:(0.85-1):(1-3); the mass ratio of the total mass of bisphenol A and dichloro monomer to the polar aprotic solvent is 1:(2.5-5).

[0012] Preferably, in step S1, the mass ratio of the water-separating agent to the polar aprotic solvent is (0.2-0.4):1.

[0013] Preferably, in step S1 and step S3, the polar aprotic solvent is N,N-dimethylacetamide (DMAC) or N-methylpyrrolidone (NMP).

[0014] Preferably, in step S2, the amount of ionic liquid added is 1-5 wt.% of the polar aprotic solvent in step S1.

[0015] Preferably, in step S2, the end-capping process of the sulfonated polysulfone resin polymer solution is: after adding the ionic liquid and the quaternary ammonium salt catalyst tetrabutylammonium bromide, cooling to 90-150° C., introducing methyl chloride, and reacting for 1-4 hours to obtain the end-capped sulfonated polysulfone resin polymer solution.

[0016] Preferably, in step S3, the content of the polar aprotic solvent in the mixed solvent is 5-25 wt.%.

[0017] In another aspect, the present invention provides sulfonated polysulfone without foaming during film formation, which is prepared by the above-mentioned method for preparing sulfonated polysulfone without foaming during film formation.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The present invention reduces the proportion of sulfonated monomers in dichloromonomers, reduces the proportion of sulfonate groups, increases the polymerization rate, and reduces the generation of small molecules in sulfonated polysulfone. At the same time, the present invention adds an ionic liquid and a quaternary ammonium salt catalyst TBAB in the end-capping stage when the polymerization is completed, and the quaternary ammonium cation in the TBAB combines with the sulfonate group through electrostatic attraction to form an ion pair. This effect can shield the negative charge of the sulfonate group, thereby reducing the obstacle to the nucleophilic attack of methyl chloride, increasing the end-capping rate of the sulfonated polysulfone small molecules, reducing the hydrophilicity of the small molecules, and avoiding the formation of foam when the film is formed. At the same time, the anion Tf2N in the ionic liquid -With Br - Dynamic exchange occurs to form a more stable tetrabutylammonium-Tf2N complex with stronger catalytic ability. In addition, in the precipitation process of the polymer solution, 5-25wt.% of a polar aprotic solvent is added to the washing water, and the solubility difference of the polar aprotic solvent on the sulfonated polysulfone macromolecule and the small molecule is utilized to further remove the sulfonated polysulfone small molecule. DETAILED DESCRIPTION

[0019] In order to enable persons skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0020] Example 1 The preparation method of the sulfonated polysulfone without foaming during film formation of the present embodiment comprises the following steps: S1: Add 68.96 kg of DMAC, 6084.34 g of bisphenol A, 130.93 g of SDCDPS, 7576.8 g of DCDPS, 3866.67 g of potassium carbonate and 13.79 kg of xylene into a 100 L polymerization reactor. After nitrogen replacement three times, introduce nitrogen to react at normal pressure. Nitrogen protection is performed throughout the polymerization reaction; heat to 120° C. and keep the temperature for 8 hours; after reaching the theoretical water extraction rate, evaporate all the xylene, heat to 160° C. and keep the temperature for 10 hours to obtain a sulfonated polysulfone resin polymerization liquid; S2: Cool the sulfonated polysulfone resin polymer solution to 150° C., add 689.6 g of 1-butyl-3-methylimidazole bis(trifluoromethylsulfonyl)imide and 90.21 g of TBAB, introduce methyl chloride, and cap for 1 hour to obtain a capped sulfonated polysulfone resin polymer solution; S3: Pour the blocked sulfonated polysulfone resin polymer solution into cold water to cool and precipitate, grind it into powder mechanically, boil it several times with a mixed water solvent containing 5wt.% DMAC, filter and dry it to obtain a sulfonated polysulfone without foam when forming a film.

[0021] Example 2 The preparation method of the sulfonated polysulfone without foaming during film formation of the present embodiment comprises the following steps: S1: Add 62.31 kg of NMP, 6084.34 g of bisphenol A, 261.85 g of SDCDPS, 7500.27 g of DCDPS, 2965.26 g of sodium carbonate and 18.69 kg of toluene into a 100 L polymerization reactor. After nitrogen replacement three times, introduce nitrogen to react at normal pressure, and carry out nitrogen protection throughout the polymerization reaction; heat to 125° C. and keep warm for 4 hours; after reaching the theoretical water extraction rate, evaporate all the toluene, heat to 170° C. and keep warm for 9 hours to obtain a sulfonated polysulfone resin polymerization liquid; S2: Cool the sulfonated polysulfone resin polymer solution to 90° C., add 1246.18 g of 1-ethyl-3-methylimidazole bis(trifluoromethanesulfonyl)imide salt and 189.02 g of TBAB, introduce methyl chloride, and cap for 2 h to obtain a capped sulfonated polysulfone resin polymer solution; S3: Pour the blocked sulfonated polysulfone resin polymer solution into cold water to cool and precipitate, grind it into powder mechanically, boil it several times with a mixed water solvent containing 10wt.% NMP, filter and dry it to obtain a sulfonated polysulfone without foam when forming a film.

[0022] Example 3 The preparation method of the sulfonated polysulfone without foaming during film formation of the present embodiment comprises the following steps: S1: Add 41.7 kg of NMP, 6084.34 g of bisphenol A, 392.78 g of SDCDPS, 7423.73 g of DCDPS, 9115.38 g of cesium carbonate and 16.68 kg of trimethylbenzene into a 100 L polymerization reactor. After nitrogen replacement three times, introduce nitrogen to react at normal pressure, and carry out nitrogen protection throughout the polymerization reaction; heat to 130° C. and keep warm for 5 hours; after reaching the theoretical water extraction rate, evaporate all trimethylbenzene, heat to 185° C. and keep warm for 7 hours to obtain a sulfonated polysulfone resin polymerization liquid; S2: Cool the sulfonated polysulfone resin polymer solution to 150° C., add 1668.1 g of N-ethylpyridine bistrifluoromethanesulfonyl imide salt and 309.3 g of TBAB, introduce chloroform, and cap for 4 hours to obtain a capped sulfonated polysulfone resin polymer solution; S3: Pour the blocked sulfonated polysulfone resin polymer solution into cold water to cool and precipitate, grind it into powder mechanically, boil it several times with a mixed water solvent containing 15wt.% NMP, filter and dry it to obtain a sulfonated polysulfone without foam when forming a film.

[0023] Example 4 The preparation method of the sulfonated polysulfone without foaming during film formation of the present embodiment comprises the following steps: S1: Add 34.89 kg of NMP, 6084.34 g of bisphenol A, 523.71 g of SDCDPS, 7347.2 g of DCDPS, 2801.03 g of potassium carbonate and 13.96 kg of ethylbenzene into a 100 L polymerization reactor. After nitrogen replacement three times, introduce nitrogen to react at normal pressure, and carry out nitrogen protection throughout the polymerization reaction; heat to 145° C. and keep the temperature for 4 hours; after reaching the theoretical water extraction rate, evaporate all the ethylbenzene, heat to 190° C. and keep the temperature for 4 hours to obtain a sulfonated polysulfone resin polymerization liquid; S2: Cool the sulfonated polysulfone resin polymer solution to 150° C., add 1071.12 g of 1-butyl-3-methylimidazole bis(trifluoromethylsulfonyl)imide and 412.4 g of TBAB, introduce methyl chloride, and cap for 2 h to obtain a capped sulfonated polysulfone resin polymer solution; S3: Pour the blocked sulfonated polysulfone resin polymer solution into cold water to cool and precipitate, grind it into powder mechanically, boil it several times with a mixed water solvent containing 20wt.% NMP, filter and dry it to obtain a sulfonated polysulfone without foam when forming a film.

[0024] Example 5 The preparation method of the sulfonated polysulfone without foaming during film formation of the present embodiment comprises the following steps: S1: Add 70.05 kg of NMP, 6084.34 g of bisphenol A, 654.64 g of SDCDPS, 7270.67 g of DCDPS, 2350.33 g of sodium carbonate and 21.01 kg of ethylbenzene into a 100 L polymerization reactor, replace the nitrogen three times, introduce nitrogen to react at normal pressure, and carry out nitrogen protection throughout the polymerization reaction; heat up to 150° C. and keep the temperature for 2 h; after reaching the theoretical water extraction rate, evaporate all the ethylbenzene, heat up to 200° C. and keep the temperature for 2 h to obtain a sulfonated polysulfone resin polymerization liquid; S2: Cool the sulfonated polysulfone resin polymer solution to 120° C., add 3502.41 g of 1-butyl-3-methylimidazole bis(trifluoromethylsulfonyl)imide and 515.5 g of TBAB, introduce methyl chloride, and cap for 2 h to obtain a capped sulfonated polysulfone resin polymer solution; S3: Pour the blocked sulfonated polysulfone resin polymer solution into cold water to cool and precipitate, grind it into powder mechanically, boil it several times with a mixed water solvent containing 25wt.% NMP, filter and dry it to obtain a sulfonated polysulfone without foam when forming a film.

[0025] Comparative Example 1 The difference from Example 1 is that in step S1, the amount of SDCDPS added is 1309.27 g, and the amount of DCDPS added is 6888 g.

[0026] Comparative Example 2 The difference from Example 1 is that in step S2, TBAB is replaced by an equimolar amount of tetraethylammonium chloride (TEAC).

[0027] Comparative Example 3 The difference from Example 1 is that in step S3, deionized water is used instead of the mixed water solvent containing 5 wt.% DMAC.

[0028] Comparative Example 4 The difference from Example 1 is that in step S2, 1-butyl-3-methylimidazole bistrifluoromethylsulfonimide is not added.

[0029] Comparative Example 5 The difference from Example 1 is that in step S2, 1-butyl-3-methylimidazole bis(trifluoromethylsulfonyl)imide and TBAB are not added.

[0030] The sulfonated polysulfones prepared in Examples 1-5 and Comparative Examples 1-5 were subjected to pilot continuous film formation, comprising the following steps: 1) Dry the sulfonated polysulfone under vacuum at 80°C for 8 hours; 2) Dissolve the dried sulfonated polysulfone in DMAC to prepare a casting solution with a solid content of 20 wt.%, and perform vacuum degassing for 4 hours; 3) The degassed casting solution passes through the spinneret of the spinning machine to form a spinning fine flow, passes through the air gap between the spinneret and the gel tank and enters the coagulation bath in the gel tank to form a sulfonated polysulfone hollow fiber membrane.

[0031] After running continuously in the coagulation bath for 1h and 5h, the water flux of the sulfonated polysulfone hollow fiber membrane was measured respectively.

[0032] The water flux detection method is as follows: Testing instrument: MOIST 3A; Testing process: pre-press at 0.2MPa for 30min, and after the pre-press, measure the volume of pure water passing through the sulfonated polysulfone hollow fiber membrane at 0.1MPa pressure within a certain period of time. The volume is measured with a measuring cylinder; the water flux of the sulfonated polysulfone hollow fiber membrane is calculated according to the following formula: J = V / (S·t); Where, J-water flux, L / m 2 h; V-pure water volume, L; S-effective membrane area, m 2 ; t-measurement time, h.

[0033] The tensile strength test method of sulfonated polysulfone hollow fiber membrane is as follows: The membrane filaments of the sulfonated polysulfone hollow fiber membrane were clamped on a universal testing machine, the tensile rate was set to 50 mm / min, the mold spacing was 50 mm, and the maximum tensile force F when the membrane filaments broke was recorded. The tensile strength was calculated by the following formula: δ = F / [π (D 2 -d 2 )]; Where: δ-tensile strength, MPa; F-maximum tensile force F when the membrane breaks, N; D-outer diameter of the membrane, m; d-inner diameter of the membrane, m.

[0034] The test results of water flux and tensile strength of the sulfonated polysulfone hollow fiber membranes of Examples 1-5 and Comparative Examples 1-5 are shown in Table 1: Table 1 Test results of water flux and tensile strength of sulfonated polysulfone hollow fiber membranes of Examples 1-5 and Comparative Examples 1-5

[0035] Comparing the data of Comparative Examples 1-5 and Example 1 in Table 1, it can be seen that in Comparative Example 1, due to the excessive addition of the sulfonated monomer SDCDPS in the dichloromonomer, the sulfonation degree of the sulfonated polysulfone increased to 10%, and its hydrophilicity was too strong when it was formed into a film alone. It was in a gel state during the storage period after the film was formed, and it broke when it touched the fixture after drying, making it difficult to test its mechanical properties. In Comparative Example 2, the catalyst used TEAC. Compared with TBAB, the ethyl chain length of TEAC is shorter and the flexibility is weakened. The nucleophilicity of chloride ions is also weaker than that of bromide ions, and the inhibitory effect on steric hindrance is greatly weakened, resulting in a poor end-capping effect of the sulfonated polysulfone. The small molecule sulfonated polysulfone with strong hydrophilicity will still form foam, causing the water flux of the product to drop to 171.6L / m when it is continuously formed for 5h. 2 ·h. In Comparative Example 3, deionized water was used instead of the mixed water solvent, which failed to eliminate the residual uncapped sulfonated polysulfone small molecules, resulting in a significant attenuation in the water flux of the sulfonated polysulfone hollow fiber membrane. In Comparative Example 4, no ionic liquid was added during the end-capping, resulting in a weakened TBAB effect, causing a decrease in the water flux after 5 hours of continuous membrane formation. In Comparative Example 5, no ionic liquid and TBAB were added during the end-capping, and a large number of uncapped sulfonated polysulfone small molecules were encapsulated in the high molecular weight sulfonated polysulfone product. This part of the encapsulated uncapped sulfonated polysulfone small molecules was difficult to separate only by subsequent mixed water solvent extraction, resulting in a significant decrease in the water flux after 5 hours of continuous membrane formation.

Claims

1. A method for preparing sulfonated polysulfone without foaming during film formation, characterized in that: The following steps are involved: S1: put bisphenol A, dichloromonomer, salt-forming agent and water-separating agent into a polar aprotic solvent, introduce protective gas, heat to 120-150°C, keep warm for 2-8 hours, and perform salt-forming reaction; after the water extraction reaches the theoretical value and the salt-forming reaction is completed, continue to heat to 160-200°C, keep warm for 2-10 hours, and perform nucleophilic polycondensation reaction to obtain a sulfonated polysulfone resin polymerization liquid; wherein the salt-forming agent is cesium carbonate, potassium carbonate or sodium carbonate; the water-separating agent is toluene, xylene, trimethylbenzene, ethylbenzene or ethylbenzene; the dichloromonomer is 3,3'-sodium disulfonate-4,4'-dichlorodiphenyl sulfone and 4,4'-dichlorodiphenyl sulfone, and the molar percentage of 3,3'-sodium disulfonate-4,4'-dichlorodiphenyl sulfone in the dichloromonomer is 1-5%; S2: cooling the sulfonated polysulfone resin polymerization liquid, adding ionic liquid and quaternary ammonium salt catalyst tetrabutylammonium bromide, and introducing methyl chloride for end-capping to obtain an end-capped sulfonated polysulfone resin polymerization liquid; wherein the ionic liquid is 1-butyl-3-methylimidazolium bistrifluoromethylsulfonyl imide, 1-ethyl-3-methylimidazolium bistrifluoromethylsulfonyl imide salt or N-ethylpyridine bistrifluoromethylsulfonyl imide salt; S3: crushing the blocked sulfonated polysulfone resin polymer solution, extracting with a mixed solvent, filtering, and drying to obtain a sulfonated polysulfone without foam during film formation; wherein the mixed solvent is a mixture of a polar aprotic solvent and deionized water.

2. The method for preparing sulfonated polysulfone without foaming during film formation as claimed in claim 1, characterized in that: In step S2, the molar ratio of the quaternary ammonium salt catalyst tetrabutylammonium bromide to 3,3'-sodium disulfonate-4,4'-dichlorodiphenyl sulfone is (1.05-1.2):

1.

3. The method for preparing sulfonated polysulfone without foaming during film formation as claimed in claim 1, characterized in that: In step S1, the molar ratio of bisphenol A, dichloro monomer and salt-forming agent is 1:(0.85-1):(1-3); the mass ratio of the total mass of bisphenol A and dichloro monomer to the polar aprotic solvent is 1:(2.5-5).

4. The method for preparing sulfonated polysulfone without foaming during film formation as claimed in claim 1, characterized in that: In step S1, the mass ratio of the water-separating agent to the polar aprotic solvent is (0.2-0.4):

1.

5. The method for preparing sulfonated polysulfone without foaming during film formation as claimed in claim 1, characterized in that: In step S1 and step S3, the polar aprotic solvent is N,N-dimethylacetamide or N-methylpyrrolidone.

6. The method for preparing sulfonated polysulfone without foaming during film formation as claimed in claim 1, characterized in that: In step S2, the amount of ionic liquid added is 1-5 wt.% of the polar aprotic solvent in step S1.

7. The method for preparing sulfonated polysulfone without foaming during film formation as claimed in claim 1, characterized in that: In step S2, the end-capping process of the sulfonated polysulfone resin polymer solution is as follows: after adding the ionic liquid and the quaternary ammonium salt catalyst tetrabutylammonium bromide, the temperature is lowered to 90-150° C., methyl chloride is introduced, and the reaction is carried out for 1-4 hours to obtain the end-capped sulfonated polysulfone resin polymer solution.

8. The method for preparing sulfonated polysulfone without foaming during film formation as claimed in claim 1, characterized in that: In step S3, the content of the polar aprotic solvent in the mixed solvent is 5-25 wt.%.

9. Sulfonated polysulfone without foaming during film formation, characterized in that: The method is prepared by the method for preparing sulfonated polysulfone without foaming during film formation as described in any one of claims 1 to 8.

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