Method for preparing high-temperature-resistant homogeneous cation exchange membrane by in-situ polymerization method

Abstract

The invention provides a method for preparing a high-temperature-resistant homogeneous cation exchange membrane by an in-situ polymerization method, which comprises the following steps: co-dissolving reactable alkenyl sulfonate Gemini surfactant, aromatic monoolefine, unsaturated carboxylic acid and other monomers, a skeleton polymer and a hydrophilic modifier in a solvent by a one-pot process, and carrying out in-situ polymerization to generate a block polymer, thereby obtaining the high-temperature-resistant homogeneous cation exchange membrane. The block polymer and the skeleton polymer form a semi-interpenetrating network structure, and the compounding effect further enhances the high-temperature stability and mechanical properties of the membrane. The prepared homogeneous cation exchange membrane does not need multi-step post-treatment, the membrane preparation process is simple and convenient, and large-scale popularization is easy; the obtained membrane material has excellent thermal stability and mechanical strength under a high-temperature condition, keeps low resistance and good desalination performance, and is suitable for electrodialysis, fuel cells and other scenes with high requirements for ion conduction and heat resistance.

Description

Technical Field

[0001] The present invention relates to a high-temperature resistant homogeneous cation exchange membrane (CEM) prepared by an in-situ polymerization method, which is particularly suitable for water treatment technologies such as electrodeionization (EDI) and electrodialysis (ED), and is particularly suitable for ion separation and purification in high-temperature environments, and belongs to the field of membrane science and technology. Background Art

[0002] Ion exchange membranes (IEMs), as functional materials with ion-selective permeability, play an important role in a variety of fields, including water treatment, energy, chemical production, environmental protection, and resource recovery. IEM prices vary significantly depending on type, brand, specification, and application. Imported products (such as Gore in the United States and Astron in Japan) use high-end materials such as perfluorosulfonic acid resins, resulting in superior membrane structural stability and ion transmission efficiency, with surface resistance controlled at 3Ω·cm. 2 Domestic ion exchange membranes have been optimized through polymer matrix, and some indicators are close to international levels, but there is still a gap in overall durability. Currently, domestic ion exchange membranes are constantly breaking through technical barriers. For example, the research and development of high-end materials such as perfluorosulfonic acid resins has been accelerated, and the surface resistance of domestic cation exchange membranes has exceeded 3Ω·cm. 2 Technical bottleneck.

[0003] With the development of fuel cells, the hydrogen energy industry, and high-temperature electrodialysis technology, IEM performance requirements in high-temperature, hot and humid environments above 120°C are increasing. They must simultaneously meet high ionic conductivity, high-temperature resistance, and good mechanical strength. In applications such as high-temperature fuel cells, nuclear wastewater treatment, and ultrapure water production, ion membranes face multiple challenges such as thermal degradation, dehydration, interfacial delamination, and mechanical fatigue, which limit the long-term use and engineering reliability of the membrane materials.

[0004] Existing ion exchange membranes are mainly divided into three categories: homogeneous membranes, heterogeneous membranes and alloy membranes. Among them, homogeneous membranes have a completely uniform microstructure due to their functional groups fixed to the polymer skeleton through chemical bonds, with no phase interface, low porosity (<10nm) and uniform distribution, and the membrane resistance can be as low as 3Ω·cm 2 , with excellent ionic conductivity and thermal stability, has become a research focus for high-performance membrane materials. However, the preparation process of homogeneous membranes usually involves the introduction of sulfonic acid groups in multiple steps, with harsh reaction conditions and complex processes, resulting in high costs and poor scalability. In contrast, although heterogeneous membranes and alloy membranes are easy to form and have good mechanical strength, they have high resistance due to problems such as multiphase interfaces and uneven pores. In addition, there is a high risk of resin-substrate interface peeling at high temperatures, and their long-term stability is limited.

[0005] At present, some studies have attempted to improve the temperature resistance of membranes by material composite or cross-linking modification, such as sulfonated polyarylethersulfone copolymer membranes, inorganic nanocomposite membranes, sulfonated polyaryletherketone cross-linked membranes, etc., but there are problems such as difficult structural control, particle agglomeration, and excessive cross-linking leading to a decrease in ion exchange capacity. For example, although the high-temperature thermal stability of the inorganic nano-doped SiO2@Nafion composite membrane is significantly improved, the conduction path is discontinuous; and when the cross-linking degree exceeds 15%, the ion exchange capacity of the sulfonated polyaryletherketone cross-linked membrane drops sharply. In addition, existing high-performance membranes mostly rely on fluorine materials (such as Nafion), which have extremely high preparation costs and are not suitable for large-scale industrial scenarios.

[0006] Therefore, there is an urgent need to develop a homogeneous cation exchange membrane with a simple preparation process, manageable costs, and the ability to maintain excellent mechanical strength and ion conductivity in high-temperature environments. Utilizing a high-temperature-resistant polymer backbone and uniformly introducing functional groups into the backbone through in-situ polymerization can effectively improve the membrane's structural stability and conductivity consistency, avoiding the issues of multi-step post-processing and heterogeneous interface failure. This is an important research direction for achieving high-performance, low-cost homogeneous cation exchange membranes. Summary of the Invention

[0007] In response to the technical problems raised above, a method for preparing a high-temperature resistant homogeneous cation exchange membrane by in-situ polymerization is provided. The present invention mainly utilizes a self-made reactive olefin sulfonate Gemini surfactant, and then in-situ polymerizes the reactive olefin sulfonate Gemini surfactant, aromatic monoolefins, and unsaturated carboxylic acids containing carbon-carbon double bonds into block polymers in a casting solution containing a backbone polymer and a hydrophilic modifier. The block polymer runs through the backbone polymer to form a semi-interpenetrating network structure. The reactive olefin sulfonate Gemini surfactant chain segments in the block polymer and the hydrophilic modifier react with each other, and the semi-interpenetrating network structure and the reacting reaction synergistically enhance the high-temperature resistance of the ion membrane. The casting solution after in-situ polymerization is subjected to ultrasonic degassing, film casting, gradient heating, and cooling and peeling processes to obtain the low-cost, high-temperature resistant homogeneous cation exchange membrane of the present invention.

[0008] The technical means adopted in the present invention are as follows:

[0009] A method for preparing a high-temperature resistant homogeneous cation exchange membrane by in-situ polymerization comprises the following steps:

[0010] Step 1: Preparation of reactive olefin sulfonate Gemini surfactant:

[0011] Maleic anhydride and lauryl alcohol were used as the starting materials to synthesize maleic acid monoester under the catalysis of sodium acetate, and then reacted with anhydrous sodium carbonate, dichloroolefin and sodium bisulfite to prepare reactive olefin sulfonate Gemini surfactant.

[0012] Step 2: Prepare the casting solution:

[0013] The backbone polymer is dissolved in a solvent, with the solvent accounting for 40% to 60% and the backbone polymer material accounting for 5% to 25% in the casting solution; after complete dissolution, the reactive olefin sulfonate Gemini surfactant, aromatic monoolefin and unsaturated carboxylic acid containing carbon-carbon double bonds are added in sequence; after sufficient dissolution, an initiator is added to initiate in-situ polymerization to generate a block polymer, and a Semi-IPN structure is constructed with the backbone polymer, and then a hydrophilic additive is added to form a uniform casting solution of the composite system; wherein, the semi-interpenetrating network structure formed by the cation exchange membrane has a penetrating distribution of sulfonate ion channels, which realizes stable ion conduction under high temperature conditions;

[0014] Step 3: Film formation and curing:

[0015] The casting solution prepared in step 2 is subjected to ultrasonic degassing and then cast and scraped to ensure uniform film thickness, and then cured into a film by a gradient heating method; the ultrasonic treatment is used to eliminate bubbles and prevent the block polymer and the hydrophilic agent from agglomerating due to the molecular chain complexing effect, thereby ensuring that the functional groups are evenly distributed throughout the film during the polymer film formation process;

[0016] Step 4: Post-processing:

[0017] The membrane was soaked in deionized water for 48 hours, and the membrane automatically fell off the smooth flat plate and was washed to obtain the high-temperature resistant homogeneous cation exchange membrane, which was then stored for later use.

[0018] Furthermore, in step 1, the dichloroolefin is at least one of 3,4-dichloro-1-butene, 1,3-dichloropropylene, 2,3-dichloropropylene, and 3,4-dichloro-1-pentene. The type of dichloroolefin can be adjusted to control the structural characteristics and polymerization activity of the Gemini surfactant.

[0019] Furthermore, in step 2, a block polymer is prepared by in-situ polymerization, and the block polymer simultaneously provides the sulfonic acid group and the carboxyl group bifunctional groups required for the cation exchange membrane.

[0020] Furthermore, in step 2, the backbone polymer is one of polystyrene, ethylene naphthylene, p-methylstyrene and p-ethylstyrene.

[0021] Furthermore, in step 2, the aromatic monoolefin is one of polystyrene, naphthalene vinyl, p-methylstyrene and p-ethylstyrene.

[0022] Furthermore, in step 2, the unsaturated carboxylic acid containing a carbon-carbon double bond is at least one of acrylic acid, n-butenoic acid, crotonic acid, and trans-2-hexenoic acid.

[0023] Furthermore, in step 2, the solvent is at least one of N-methylpyrrolidone, dimethylacetamide, dimethylformamide, dimethyl sulfoxide, dichloromethane, chloroform, and furan.

[0024] Furthermore, in step 2, the hydrophilic additive is at least one of polyethylene glycol, polyvinyl alcohol, and polyvinyl pyrrolidone. The Gemini surfactant chain segments and the hydrophilic additive undergo molecular complexation to enhance the interfacial stability of the membrane at high temperatures.

[0025] Furthermore, in step 2, in the casting solution, the block polymer accounts for 5% to 25%, the hydrophilic additive accounts for 5% to 8%, and the rest is the backbone polymer and the solvent, and the sum of the mass percentages of each component is 100%.

[0026] Furthermore, in step 3, the gradient heating method is: heating at 60°C to 80°C for 2 to 3 hours in the first stage, heating at 60°C to 90°C for 5 to 6 hours in the second stage, and then taking the film out of the oven and naturally cooling it to room temperature in the air.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] 1. The present invention adopts in-situ polymerization technology to dissolve functional monomers, backbone polymers and hydrophilic modifiers in the same solvent system, and completes film formation and modification in one step through a "one-pot process", making the film preparation process simple and easy to implement industrially. The monomers and backbone matrix materials used are easily available, and the overall preparation cost of CEM is significantly reduced.

[0029] 2. The present invention introduces reactive olefin sulfonate Gemini surfactants and utilizes the composite bridging effect between their functional groups and hydrophilic modifiers to synergistically construct a semi-interpenetrating network structure, thereby effectively enhancing the structural stability and mechanical strength of the membrane in a high-temperature environment.

[0030] 3. The ion membrane prepared by the present invention is a homogeneous high-temperature resistant ion membrane, and the functional groups are evenly distributed in the membrane, avoiding the interruption of the conduction path caused by the heterogeneous interface, showing lower membrane resistance and higher desalination efficiency.

[0031] 4. The monomers and backbone polymer raw materials used in the present invention are widely available and inexpensive. The overall process and material system are more suitable for large-scale promotion and application, and are particularly suitable for water treatment technology fields such as electrodeionization (EDI) and electrodialysis (ED), and have good industrialization prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0033] Figure 1 This is a schematic diagram of the preparation principle of the reactive olefin sulfonate Gemini surfactant according to Example 1 of the present invention.

[0034] Figure 2 This is a schematic diagram of the polymerization process of the block copolymer of Example 1 of the present invention.

[0035] Figure 3 This is a physical picture of the cation exchange membrane obtained in Example 1 of the present invention.

[0036] Figure 4 for Figure 3 The cross-sectional SEM image of the cation exchange membrane was obtained.

[0037] Figure 5 This is a physical picture of the cation exchange membrane obtained in Example 2 of the present invention.

[0038] Figure 6 for Figure 5 The cross-sectional SEM image of the cation exchange membrane was obtained

[0039] Figure 7 This is a physical picture of the cation exchange membrane obtained in Example 3 of the present invention.

[0040] Figure 8 for Figure 7 The cross-sectional SEM image of the cation exchange membrane was obtained.

[0041] Figure 9 This is a physical picture of the cation exchange membrane obtained in Example 4 of the present invention.

[0042] Figure 10 for Figure 9 The cross-sectional SEM image of the cation exchange membrane was obtained.

[0043] Figure 11 This is a physical picture of the cation exchange membrane obtained in Example 5 of the present invention.

[0044] Figure 12 for Figure 11 The cross-sectional SEM image of the cation exchange membrane was obtained.

[0045] Figure 13 This is a physical picture of the cation exchange membrane obtained in Example 6 of the present invention.

[0046] Figure 14 for Figure 13 The cross-sectional SEM image of the cation exchange membrane was obtained.

[0047] Figure 15 This is a physical picture of the cation exchange membrane obtained in Example 7 of the present invention.

[0048] Figure 16 for Figure 15 The cross-sectional SEM image of the cation exchange membrane was obtained.

[0049] Figure 17 This is a physical picture of the cation exchange membrane obtained in Example 8 of the present invention.

[0050] Figure 18 for Figure 17 The cross-sectional SEM image of the cation exchange membrane was obtained. DETAILED DESCRIPTION

[0051] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0052] Example 1

[0053] The present invention provides a method for preparing a high-temperature resistant homogeneous cation exchange membrane by in-situ polymerization, which specifically comprises the following steps:

[0054] Weigh 10g of maleic anhydride and 10g of lauryl alcohol as the initial raw materials and dissolve them in 100g of distilled water. Add 10g of anhydrous sodium acetate as a catalyst to synthesize maleic acid monoester. Then add 5g of anhydrous sodium carbonate, 20g of 3,4-dichloro-1-butene, and 10g of sodium bisulfite to generate a reactive olefin sulfonate Gemini surfactant. The preparation principle is as shown in the attached figure. Figure 1 10g polyethersulfone was dissolved in 100g dimethylacetamide and mixed. After complete dissolution, 5g reactive olefin sulfonate Gemini surfactant, 4g styrene and 4g acrylic acid were added in sequence. After full dissolution, initiator azobisisobutyronitrile was added to initiate in-situ polymerization to generate block polymer. The polymerization principle is shown in the attached figure. Figure 2As shown, finally 3g of polyvinyl pyrrolidone K60 was added and the hydrophilic modifier was completely dissolved. The prepared casting solution was ultrasonicated for 6 hours, and the obtained casting solution was scraped onto a smooth flat plate to form a film. Then, it was placed in an oven and heated at 60°C for 2 hours and then at 90°C for 6 hours. The film was then taken out of the oven and cooled to room temperature in air. The cooled film was placed in deionized water for 48 hours. The film automatically fell off the smooth flat plate, which is the homogeneous high-temperature resistant ion exchange membrane of the present invention (the actual object is shown in the attached figure). Figure 3 The cross-sectional structure is shown in the attached Figure 4 Tests have shown that the cationic membrane has a thickness of 167 μm, a water absorption rate of 12% at 40°C, an ion exchange capacity of 1.67 meq / mg, and no degradation in desalination performance after being placed in a 90°C high-temperature solution for 2 hours and undergoing 30 cycles of high-temperature treatment.

[0055] Example 2

[0056] 10g of maleic anhydride and 10g of lauryl alcohol were weighed as the starting materials and dissolved in 100g of distilled water. 10g of anhydrous sodium acetate was added as a catalyst to synthesize maleic acid monoester. 5g of anhydrous sodium carbonate, 21g of 3,4-dichloro-1-pentene, and 10g of sodium bisulfite were then added to generate a reactive olefin sulfonate Gemini surfactant. 11g of polyetheretherketone was dissolved in 100g of furan and mixed. After complete dissolution, 4.5g of the reactive olefin sulfonate Gemini surfactant, 4g of styrene, and 4g of crotonic acid were added in sequence. After full dissolution, azobisisobutyronitrile (ABI) was added as an initiator to initiate in-situ polymerization to form a block polymer. Finally, 3.5g of polyethylene glycol was added to completely dissolve the hydrophilic modifier. The prepared casting solution was ultrasonically treated for 6.5 hours, and the obtained casting solution was scraped onto a smooth flat plate to form a film. The film was then placed in an oven and heated at 65°C for 2 hours and then at 90°C for 6.55 hours. The film was then removed from the oven and cooled to room temperature in air. The cooled film was placed in deionized water for 48 hours, and the film automatically fell off the smooth flat plate, which is the homogeneous high-temperature resistant ion exchange membrane of the present invention (see attached). Figure 5 The cross-sectional structure is shown in the attached Figure 6 Tests have shown that the cationic membrane has a thickness of 166 μm, a water absorption rate of 14% at 40°C, an ion exchange capacity of 1.74 meq / mg, and no degradation in desalination performance after being placed in a 90°C high-temperature solution for 2 hours and undergoing 30 cycles of high-temperature treatment.

[0057] Example 3

[0058] 10g of maleic anhydride and 10g of lauryl alcohol were weighed as starting materials and dissolved in 100g of distilled water. 10g of anhydrous sodium acetate was added as a catalyst to synthesize maleic acid monoester. 5g of anhydrous sodium carbonate, 22g of 2,3-dichloropropylene, and 10g of sodium bisulfite were then added to generate a reactive olefin sulfonate Gemini surfactant. 9.5g of polyether ketone was dissolved in 95g of chloroform and mixed until completely dissolved. 5.5g of reactive olefin sulfonate Gemini surfactant, 4.3g of naphthalene vinyl, and 4.3g of crotonic acid were then added. After complete dissolution, azobisisobutyronitrile (ABI) was added as an initiator to initiate in situ polymerization to form a block polymer. Finally, 3.2g of polyethylene glycol was added to completely dissolve the hydrophilic modifier. The prepared casting solution was ultrasonically treated for 7 hours, and the obtained casting solution was scraped onto a smooth flat plate to form a film. The film was then placed in an oven and heated at 65°C for 1.7 hours and then at 90°C for 6.5 hours. The film was then removed from the oven and cooled to room temperature in air. The cooled film was placed in deionized water for 48 hours, and the film automatically fell off the smooth flat plate, which is the homogeneous high-temperature resistant ion exchange membrane of the present invention (see attached). Figure 7 The cross-sectional structure is shown in the attached Figure 8 Tests have shown that the cationic membrane has a thickness of 162 μm, a water absorption rate of 15% at 40°C, an ion exchange capacity of 1.69 meq / mg, and no degradation in desalination performance after being placed in a 90°C high-temperature solution for 2 hours and undergoing 30 cycles of high-temperature treatment.

[0059] Example 4

[0060] 10g of maleic anhydride and 10g of lauryl alcohol were weighed as starting materials and dissolved in 100g of distilled water. 10g of anhydrous sodium acetate was added as a catalyst to synthesize maleic acid monoester. 5g of anhydrous sodium carbonate, 23g of 1,3-dichloropropylene, and 10g of sodium bisulfite were then added to generate a reactive olefin sulfonate Gemini surfactant. 10.2g of polyethersulfone was dissolved in 98g of dichloromethane and mixed until completely dissolved. 5.2g of reactive olefin sulfonate Gemini surfactant, 4.2g of p-methylstyrene, and 4.2g of n-butylene acid were then added. After complete dissolution, azobisisobutyronitrile (ABI) was added as an initiator to initiate in situ polymerization to form a block polymer. Finally, 3.2g of polyethylene glycol was added to completely dissolve the hydrophilic modifier. The prepared casting solution was ultrasonically treated for 6.5 hours, and the obtained casting solution was scraped onto a smooth flat plate to form a film. The film was then placed in an oven and heated at 55°C for 2.5 hours and then at 85°C for 6.5 hours. The film was then removed from the oven and cooled to room temperature in air. The cooled film was placed in deionized water for 48 hours, and the film automatically fell off the smooth flat plate, which is the homogeneous high-temperature resistant ion exchange membrane of the present invention (see attached). Figure 9 The cross-sectional structure is shown in the attached Figure 10Tests have shown that the cationic membrane has a thickness of 168 μm, a water absorption rate of 17% at 40°C, an ion exchange capacity of 1.75 meq / mg, and no degradation in desalination performance after being placed in a 90°C high-temperature solution for 2 hours and undergoing 30 cycles of high-temperature treatment.

[0061] Example 5

[0062] 10g of maleic anhydride and 10g of lauryl alcohol were weighed as the initial raw materials and dissolved in 100g of distilled water. 10g of anhydrous sodium acetate was added as a catalyst to synthesize maleic acid monoester. 5g of anhydrous sodium carbonate, 22g of 3,4-dichloro-1-butene, and 10g of sodium bisulfite were then added to generate a reactive olefin sulfonate Gemini surfactant. 10.5g of polyvinylidene fluoride was dissolved in 100g of dimethylformamide and mixed. After complete dissolution, 4.8g of reactive olefin sulfonate Gemini surfactant, 3.8g of p-ethylstyrene, and 3.8g of trans-2-hexenoic acid were added in sequence. After full dissolution, azobisisobutyronitrile (ABI) was added as an initiator to initiate in-situ polymerization to generate a block polymer. Finally, 3g of polyvinyl alcohol was added to completely dissolve the hydrophilic modifier. The prepared casting solution was ultrasonically treated for 7 hours, and the obtained casting solution was scraped onto a smooth flat plate to form a film. The film was then placed in an oven and heated at 60°C for 2.5 hours and then at 87°C for 6 hours. The film was then removed from the oven and cooled to room temperature in air. The cooled film was placed in deionized water for 48 hours, and the film automatically fell off the smooth flat plate, which is the homogeneous high-temperature resistant ion exchange membrane of the present invention (see attached). Figure 11 The cross-sectional structure is shown in the attached Figure 12 Tests have shown that the cationic membrane has a thickness of 166 μm, a water absorption rate of 11% at 40°C, an ion exchange capacity of 1.57 meq / mg, and no degradation in desalination performance after being placed in a 90°C high-temperature solution for 2 hours and undergoing 30 cycles of high-temperature treatment.

[0063] Example 6

[0064] 10g of maleic anhydride and 10g of lauryl alcohol were weighed as starting materials and dissolved in 100g of distilled water. 10g of anhydrous sodium acetate was added as a catalyst to synthesize maleic acid monoester. 5g of anhydrous sodium carbonate, 23g of 1,3-dichloropropylene, and 10g of sodium bisulfite were then added to generate a reactive olefin sulfonate Gemini surfactant. 10.3g of polyvinylidene fluoride was dissolved in 98g of dimethylformamide and mixed. Once completely dissolved, 5.1g of reactive olefin sulfonate Gemini surfactant, 4.1g of naphthalene vinyl, and 4.1g of crotonic acid were added sequentially. After complete dissolution, azobisisobutyronitrile (ABI) was added as an initiator to initiate in situ polymerization to form a block polymer. Finally, 3g of polyvinyl alcohol was added to completely dissolve the hydrophilic modifier. The prepared casting solution was ultrasonically treated for 6 hours, and the obtained casting solution was scraped onto a smooth flat plate to form a film. The film was then placed in an oven and heated at 65°C for 1.7 hours and then at 90°C for 5.5 hours. The film was then removed from the oven and cooled to room temperature in air. The cooled film was placed in deionized water for 48 hours, and the film automatically fell off the smooth flat plate, which is the homogeneous high-temperature resistant ion exchange membrane of the present invention (see attached). Figure 13 The cross-sectional structure is shown in the attached Figure 14 Tests have shown that the cationic membrane has a thickness of 165 μm, a water absorption rate of 16% at 40°C, an ion exchange capacity of 1.81 meq / mg, and no degradation in desalination performance after being placed in a 90°C high-temperature solution for 2 hours and undergoing 30 cycles of high-temperature treatment.

[0065] Example 7

[0066] 10g of maleic anhydride and 10g of lauryl alcohol were weighed as the starting materials and dissolved in 100g of distilled water. 10g of anhydrous sodium acetate was added as a catalyst to synthesize maleic acid monoester. 5g of anhydrous sodium carbonate, 18g of 3,4-dichloro-1-pentene, and 10g of sodium bisulfite were then added to generate a reactive olefin sulfonate Gemini surfactant. 9.5g of polyetheretherketone was dissolved in 95g of di-N-methylpyrrolidone and mixed. After complete dissolution, 5g of the reactive olefin sulfonate Gemini surfactant, 4.3g of styrene, and 4.3g of n-butylene acid were added in sequence. After full dissolution, azobisisobutyronitrile (ABI) was added as an initiator to initiate in-situ polymerization to generate a block polymer. Finally, 3.5g of polyvinylpyrrolidone K60 was added to completely dissolve the hydrophilic modifier. The prepared casting solution was ultrasonicated for 5.5 hours, and the obtained casting solution was scraped onto a smooth flat plate to form a film. The film was then placed in an oven and heated at 60°C for 2.5 hours and then at 85°C for 6.5 hours. The film was then removed from the oven and cooled to room temperature in air. The cooled film was placed in deionized water for 48 hours, and the film automatically fell off the smooth flat plate, which is the homogeneous high-temperature resistant ion exchange membrane of the present invention (see attached). Figure 15 The cross-sectional structure is shown in the attached Figure 16Tests have shown that the cationic membrane has a thickness of 170 μm, a water absorption rate of 15% at 40°C, an ion exchange capacity of 1.71 meq / mg, and no degradation in desalination performance after being placed in a 90°C high-temperature solution for 2 hours and undergoing 30 cycles of high-temperature treatment.

[0067] Example 8

[0068] 10g of maleic anhydride and 10g of lauryl alcohol were weighed as starting materials and dissolved in 100g of distilled water. 10g of anhydrous sodium acetate was added as a catalyst to synthesize maleic acid monoester. 5g of anhydrous sodium carbonate, 20g of 1,3-dichloropropylene, and 10g of sodium bisulfite were then added to form a reactive olefin sulfonate Gemini surfactant. 9.6g of polyetherketone was dissolved in 103g of dimethyl sulfoxide and mixed until completely dissolved. 5g of reactive olefin sulfonate Gemini surfactant, 4.1g of ethylene naphthylene, and 4.1g of acrylic acid were then added. After complete dissolution, azobisisobutyronitrile (ABI) was added as an initiator to initiate in-situ polymerization to form a block polymer. Finally, 3g of polyethylene glycol was added to completely dissolve the hydrophilic modifier. The prepared casting solution was ultrasonicated for 7h. The resulting casting solution was then scraped onto a smooth flat surface to form a film. The film was then placed in an oven and heated at 55°C for 2.5h and then at 90°C for 6.5h. The film was then removed from the oven and allowed to cool to room temperature in air. The cooled membrane was placed in deionized water for 48 hours, and the membrane automatically fell off from the smooth flat plate, which was the homogeneous high-temperature resistant ion exchange membrane of the present invention (the actual object is shown in the attached Figure 17 The cross-sectional structure is shown in the attached Figure 18 Tests have shown that the cationic membrane has a thickness of 168 μm, a water absorption rate of 12% at 40°C, an ion exchange capacity of 1.54 meq / mg, and no degradation in desalination performance after being placed in a 90°C high-temperature solution for 2 hours and undergoing 30 cycles of high-temperature treatment.

[0069] A homogeneous cation exchange membrane was successfully prepared by an in-situ polymerization method using the method described in the embodiments of the present invention. The prepared cation exchange membrane had a thickness range of 162-170 μm, a moisture content of no more than 17% when tested at 40° C., and an ion exchange capacity of 1.54-1.81 meq / mg. Its desalination performance was analyzed by ED testing. The prepared cation exchange membrane was placed in a high-temperature solution at 90° C. for 2 hours each time. After 30 cycles of high-temperature treatment, the desalination performance did not decrease in each ED test, indicating that the homogeneous cation exchange membrane prepared by the present invention had good high-temperature resistance.

[0070] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a high temperature resistant homogeneous cation exchange membrane by in situ polymerization, characterized in that: The following steps are involved: Step 1: Preparation of reactive olefin sulfonate Gemini surfactant: Maleic anhydride and lauryl alcohol were used as the starting materials to synthesize maleic acid monoester under the catalysis of sodium acetate, and then reacted with anhydrous sodium carbonate, dichloroolefin and sodium bisulfite to prepare reactive olefin sulfonate Gemini surfactant. Step 2: Prepare the casting solution: The backbone polymer is dissolved in a solvent, and the reactive olefin sulfonate Gemini surfactant, aromatic monoolefin and unsaturated carboxylic acid containing a carbon-carbon double bond are added. After the polymer is fully dissolved, an initiator is added to initiate in-situ polymerization to generate a block polymer, and a Semi-IPN structure is constructed with the backbone polymer. A hydrophilic modifier is then added to form a uniform casting solution of the composite system; Step 3: Film formation and curing: The casting solution prepared in step 2 is subjected to ultrasonic degassing and then subjected to film casting and scraping, and is cured into a film by a gradient heating method; Step 4: Post-processing: The membrane is soaked in deionized water, cooled, peeled, and then washed to obtain the high-temperature resistant homogeneous cation exchange membrane, which is then stored for later use.

2. The preparation method according to claim 1, characterized in that In the step 1, the dichloroolefin is at least one of 3,4-dichloro-1-butene, 1,3-dichloropropylene, 2,3-dichloropropylene, and 3,4-dichloro-1-pentene.

3. The preparation method according to claim 1, characterized in that In the step 2, a block polymer is prepared by in-situ polymerization, and the block polymer simultaneously provides the sulfonic acid group and the carboxyl group bifunctional groups required for the cation exchange membrane.

4. The preparation method according to claim 3, characterized in that In the step 2, the backbone polymer is one of polystyrene, ethylene naphthylene, p-methylstyrene and p-ethylstyrene.

5. The preparation method according to claim 4, characterized in that In the step 2, the aromatic monoolefin is one of polystyrene, naphthalene vinyl, p-methylstyrene and p-ethylstyrene.

6. The preparation method according to claim 5, characterized in that In step 2, the unsaturated carboxylic acid containing a carbon-carbon double bond is at least one of acrylic acid, n-butenoic acid, crotonic acid, and trans-2-hexenoic acid.

7. The preparation method according to claim 6, characterized in that In the step 2, the solvent is at least one of N-methylpyrrolidone, dimethylacetamide, dimethylformamide, dimethyl sulfoxide, dichloromethane, chloroform, and furan.

8. The preparation method according to claim 7, characterized in that In step 2, the hydrophilic modifier is at least one of polyethylene glycol, polyvinyl alcohol, and polyvinyl pyrrolidone.

9. The preparation method according to claim 8, characterized in that In step 2, in the casting solution, the block polymer accounts for 5% to 25%, the hydrophilic additive accounts for 5% to 8%, and the rest is the backbone polymer and the solvent, and the sum of the mass percentages of each component is 100%.

10. The preparation method according to claim 1, characterized in that In step 3, the gradient heating method is: heating at 60°C to 80°C for 2 to 3 hours in the first stage, heating at 60°C to 90°C for 5 to 6 hours in the second stage, and then taking the film out of the oven and naturally cooling it to room temperature in the air.

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