A block copolymer containing ionic side chains and its preparation method and application

Abstract

The present invention provides a block copolymer containing ionic side chains, a preparation method thereof, and an application thereof. The preparation method comprises the following steps: (1) synthesis of a methyl polyaryletherketone having a halogen terminal group; (2) synthesis of a polyethersulfoneketone having a hydroxyl terminal group; (3) synthesis of a block copolymer; (4) synthesis of a brominated block copolymer; (5) synthesis of a quaternized alkyldiamine ionic compound; and (6) mixing the brominated block copolymer, the quaternized alkyldiamine ionic compound, and a first solvent, reacting, and post-treating to obtain the block copolymer containing ionic side chains. The block copolymer containing ionic side chains obtained by the preparation method of the present invention has two positive charges and one negative charge on its side chains. When applied to an exchange membrane, the exchange membrane can be selective for monovalent cations and has high ion flux, high selectivity, and high stability. In addition, the preparation method of the block copolymer containing ionic side chains provided by the present invention is simple.

Description

Technical Field

[0001] The present invention belongs to membrane separation, and relates to a block copolymer containing ionic side chains, a preparation method and application thereof, and in particular to a block copolymer containing ionic side chains, a preparation method thereof and a monovalent selective cation exchange membrane. Background Art

[0002] With the development of electrodialysis technology, the demand for monovalent ion separation has increased dramatically. Currently, the commonly used methods for preparing monovalent ion separation membranes include surface modification and matrix modification.

[0003] Cation exchange membranes prepared using surface modification methods can achieve efficient separations by utilizing a thinner separation skin layer, minimizing the impact of factors such as membrane resistance. Currently, extensive research is focused on this approach. However, issues such as complex surface modification methods or poor stability resulting from poorly structured modified layers and groups continue to limit their application.

[0004] Selective cation exchange membranes prepared using matrix modification methods can achieve selective ion separation through a denser structure or appropriate affinity. However, this increased overall density often leads to increased membrane resistance and reduced flux. Furthermore, the inherent properties of polymer membrane materials limit the precise control of their microstructural properties, making it difficult to significantly improve the membrane's selective separation performance.

[0005] In summary, monovalent ion separation membranes prepared by common surface modification and matrix modification methods often have problems such as poor stability or high membrane resistance. Therefore, it has become more important and urgent to develop monovalent selective cation exchange membranes with high ion flux, high selectivity, high stability and simple preparation process. Summary of the Invention

[0006] In view of the deficiencies of the prior art, the present invention aims to provide a block copolymer containing ionic side chains, a preparation method and applications thereof, and specifically to provide a block copolymer containing ionic side chains, a preparation method thereof and a monovalent selective cation exchange membrane.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing a block copolymer containing ionic side chains, the preparation method comprising the following steps:

[0009] (1) Synthesis of methyl polyaryletherketone with halogen terminal group:

[0010] Adding raw material A, raw material B, an acid-binding agent, a first solvent, and a second solvent into a reactor, reacting, and post-treating to obtain a methyl polyaryletherketone with a halogen terminal group;

[0011] (2) Synthesis of polyethersulfoneketone with hydroxyl end groups:

[0012] Adding raw material C, raw material D, an acid-binding agent, a first solvent, and a second solvent into a reactor, reacting, and post-treating to obtain a polyethersulfoneketone having a hydroxyl terminal group;

[0013] (3) Synthesis of block copolymers:

[0014] The methyl polyaryletherketone with a halogen terminal group obtained in step (1), the polyethersulfoneketone with a hydroxyl terminal group obtained in step (2), an acid binding agent, a first solvent, and a second solvent are added into a reactor, reacted, and post-treated to obtain a block copolymer;

[0015] (4) Synthesis of brominated block copolymers:

[0016] Mixing a brominating agent, an initiator, the block copolymer obtained in step (3), and a third solvent, reacting, and post-treating to obtain a brominated block copolymer;

[0017] (5) Synthesis of quaternized alkyl diamine ion compounds

[0018] Mixing raw material E, raw material F, and a fourth solvent, reacting, and post-treating to obtain a quaternized alkyl diamine ion compound;

[0019] (6) mixing the brominated block copolymer obtained in step (4), the quaternized alkyl diamine ion compound obtained in step (5), and the first solvent, reacting, and post-treating to obtain the block copolymer containing ionic side chains.

[0020] The block copolymer containing ionic side chains obtained using the preparation method provided by the present invention has two positive charges and one negative charge on its side chains. When used in an exchange membrane, the membrane is selective for monovalent cations and exhibits high ion flux, high selectivity, and high stability. Furthermore, the preparation method of the block copolymer containing ionic side chains provided by the present invention is simple.

[0021] Preferably, the raw material A in step (1) comprises 4,4'-difluorobenzophenone and / or p-benzophenone.

[0022] Preferably, the raw material B in step (1) comprises methylhydroquinone.

[0023] Preferably, in step (1), the molar ratio of raw material A to raw material B is (0.8-1.2):1, for example, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, etc.

[0024] Preferably, the reaction in step (1) is first reacted at 130-150°C (e.g., 130°C, 133°C, 135°C, 138°C, 140°C, 143°C, 145°C, 148°C, 150°C, etc.) for 3-5h (e.g., 3h, 3.5h, 4h, 4.5h, 5h, etc.), and then reacted at 160-170°C (e.g., 160°C, 163°C, 165°C, 168°C, 170°C, etc.) for 5-7h (e.g., 5h, 5.5h, 6h, 6.5h, 7h, etc.).

[0025] Preferably, the post-treatment in step (1) includes precipitation, washing and drying.

[0026] Preferably, the raw material C in step (2) comprises 4,4'-difluorodiphenyl sulfone.

[0027] Preferably, the raw material D in step (2) comprises 4,4'-dihydroxybenzophenone and / or bisphenol A.

[0028] Preferably, in step (2), the molar ratio of raw material C to raw material D is (0.8-1.2):1, for example, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, etc.

[0029] Preferably, the reaction in step (2) is first reacted at 130-150°C (e.g., 130°C, 133°C, 135°C, 138°C, 140°C, 143°C, 145°C, 148°C, 150°C, etc.) for 3-5h (e.g., 3h, 3.5h, 4h, 4.5h, 5h, etc.), and then reacted at 160-170°C (e.g., 160°C, 163°C, 165°C, 168°C, 170°C, etc.) for 10-14h, for example, 10h, 11h, 12h, 13h, 14h, etc.

[0030] Preferably, the post-treatment in step (2) includes precipitation, washing and drying.

[0031] Preferably, in step (3), the molar ratio of the methyl polyaryletherketone with a halogen terminal group to the polyethersulfoneketone with a hydroxyl terminal group is (0.8-1.2):1, for example, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, etc.

[0032] Preferably, the reaction in step (3) is first reacted at 130-150°C (e.g., 130°C, 133°C, 135°C, 138°C, 140°C, 143°C, 145°C, 148°C, 150°C, etc.) for 3-5h (e.g., 3h, 3.5h, 4h, 4.5h, 5h, etc.), and then reacted at 160-170°C (e.g., 160°C, 163°C, 165°C, 168°C, 170°C, etc.) for 12-15h, for example, 12h, 13h, 14h, 15h, etc.

[0033] Preferably, the post-treatment in step (3) includes precipitation, washing and drying.

[0034] Preferably, the bromination reagent in step (4) comprises N-bromosuccinimide.

[0035] Preferably, the initiator in step (4) comprises dibenzoyl peroxide.

[0036] Preferably, the third solvent in step (4) comprises 1,1,2,2-tetrachloroethane.

[0037] Preferably, the reaction temperature in step (4) is 70-90°C, for example, 70°C, 73°C, 75°C, 78°C, 80°C, 83°C, 85°C, 88°C, 90°C, etc., and the reaction time is 7-9h, for example, 7h, 8h, 9h, etc.

[0038] Preferably, the post-treatment in step (4) includes precipitation, washing and drying.

[0039] Preferably, the raw material E in step (5) includes any one of N,N,N′,N′-tetramethyl-1,6-hexanediamine, N,N,N′,N′-tetramethyl-1,5-pentanediamine, and tetramethylhexanediamine, or a combination of at least two thereof.

[0040] Preferably, the raw material F in step (5) comprises any one or a combination of at least two of 1,3-propane sultone, 3-bromopropionic acid, 3-bromopropanesulfonic acid, 4-bromophenol, 4-bromobutyric acid, and 5-bromovaleric acid.

[0041] Preferably, in step (5), the molar ratio of raw material E to raw material F is (1-5):1, for example, 1:1, 2:1, 3:1, 4:1, 5:1, etc.

[0042] Preferably, the fourth solvent in step (5) comprises any one of ethyl acetate, chloroform or methanol, or a combination of at least two of them.

[0043] Preferably, the reaction temperature in step (5) is 20-25°C, for example, 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, etc., and the reaction time is 20-28h, for example, 20h, 21h, 22h, 23h, 24h, 25h, 26h, 27h, 28h, etc.

[0044] Preferably, the post-treatment in step (5) includes filtration, washing and drying.

[0045] Preferably, the reaction temperature in step (6) is 50-70°C, for example, 50°C, 53°C, 55°C, 58°C, 60°C, 63°C, 65°C, 68°C, 70°C, etc., and the reaction time is 20-28h, for example, 20h, 21h, 22h, 23h, 24h, 25h, 26h, 27h, 28h, etc.

[0046] Preferably, the post-treatment in step (6) includes precipitation, washing and drying.

[0047] Preferably, the acid binding agent in steps (1) to (3) independently comprises anhydrous potassium carbonate and / or anhydrous sodium carbonate.

[0048] Preferably, the first solvent in steps (1) to (3) and (6) independently comprises any one of N,N-dimethylacetamide (DMAc), N-methylpyrrolidone (NMP) or dimethyl sulfoxide (DMSO) or a combination of at least two thereof.

[0049] Preferably, the second solvent in steps (1) to (3) includes toluene.

[0050] Preferably, the reactions in steps (1) to (3) are all carried out under an inert atmosphere.

[0051] Preferably, the inert atmosphere comprises nitrogen.

[0052] In a second aspect, the present invention provides a block copolymer containing ionic side chains, wherein the block copolymer containing ionic side chains is prepared by the preparation method described in the first aspect.

[0053] In a third aspect, the present invention provides a monovalent selective cation exchange membrane, which is prepared from the block copolymer containing ionic side chains described in the second aspect.

[0054] In a fourth aspect, the present invention provides a method for preparing the monovalent selective cation exchange membrane according to the third aspect, the preparation method comprising the following steps:

[0055] The block copolymer containing ionic side chains is dissolved in an organic solvent, degassed, and the degassed solution is cast onto a substrate and dried to obtain the monovalent selective cation exchange membrane.

[0056] The present invention uses a synthesized block copolymer material containing ionic side chains to prepare a monovalent selective cation exchange membrane. It can regulate specific functional groups or spatial structures in the membrane at the molecular level to precisely control the interaction force between the membrane material and ions and the microscopic phase separation structure. At the same time, the block copolymer containing ionic side chains can be used to prepare a monovalent selective cation exchange membrane in one step. The preparation method is simple and stable, and there is no need to change the existing industrial membrane production process, which is easy to industrialize. By introducing ion-crosslinkable functional groups into the membrane material and constructing a block copolymer material that can be microphase-separated, it is expected to precisely control the microstructure of the membrane material and its affinity with ions, thereby achieving efficient selective separation of cations. The one-step preparation of highly selective ion exchange membranes using new functional block copolymer materials also has important research significance and practical needs.

[0057] In a fifth aspect, the present invention provides a use of the monovalent selective cation exchange membrane as described in the third aspect in electrodialysis.

[0058] Compared to existing technologies, the present invention offers the following advantages: The block copolymer containing ionic side chains obtained using the preparation method provided herein has two positive charges and one negative charge on its side chains. When applied to an exchange membrane, this block copolymer can be selective for monovalent cations. Furthermore, the preparation method for the block copolymer containing ionic side chains provided by the present invention is simple, resulting in a simple method for preparing a monovalent selective cation exchange membrane with high ion flux, high selectivity, and high stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Figure 1 This is the Fourier transform infrared spectrum of the mPEEK product in Example 1.

[0060] Figure 2 is the mPEEK product in Example 1 1 H NMR spectrum.

[0061] Figure 3 This is the Fourier transform infrared spectrum of PESK in Example 1.

[0062] Figure 4 is the PESK in Example 1 1 H NMR spectrum.

[0063] Figure 5 is the KBS in Example 1 1 H NMR spectrum.

[0064] Figure 6 is the BKBS in Example 1 1 H NMR spectrum.

[0065] Figure 7 is the SQTMHDA in Example 11 H NMR spectrum.

[0066] Figure 8 is the SQKBS in Example 1 1 H NMR spectrum. DETAILED DESCRIPTION

[0067] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0068] Example 1

[0069] In this embodiment, a block copolymer containing ionic side chains is provided, and the preparation method includes the following steps:

[0070] (1) Synthesis of methyl polyetheretherketone (mPEEK):

[0071] First, 4,4'-difluorobenzophenone (0.052 mol), methylhydroquinone (0.05 mol), potassium carbonate (0.10 mol), N,N-dimethylacetamide (180 mL), and toluene (20 mL) were added sequentially to a 500 mL four-necked flask equipped with a nitrogen inlet, mechanical stirrer, thermometer, reflux condenser, and Dean-Stark apparatus. Prior to operation, the entire reactor was filled with nitrogen to maintain an inert atmosphere. Next, the mixture was heated to 140°C and maintained at this temperature for 4 hours to ensure complete water separation. The temperature was then raised to 165°C and the reaction continued at this temperature for 6 hours. After the reaction, the resulting viscous mixture was precipitated in deionized water. The precipitate was then collected and washed several times with deionized water and methanol to remove impurities. Finally, the washed product was dried in a drying oven at 60°C for 24 hours to obtain the mPEEK product.

[0072] The synthetic route is as follows:

[0073]

[0074] The Fourier transform infrared spectrum of mPEEK product is shown in Figure 1 As shown, 1 H NMR spectrum Figure 2 shown.

[0075] (2) Synthesis of polyethersulfoneketone (PESK):

[0076] First, 4,4'-difluorodiphenyl sulfone (0.05 mol), 4,4'-dihydroxybenzophenone (0.055 mol), potassium carbonate (0.11 mol), N,N-dimethylacetamide (180 mL), and toluene (20 mL) were added to a 500 mL four-necked flask equipped with a nitrogen inlet, a mechanical stirrer, a thermometer, a reflux condenser, and a Dean-Stark apparatus. The entire reactor was filled with nitrogen before heating. The mixture was then heated to 140°C and maintained at this temperature for 4 hours until the water was completely separated. The temperature was then raised to 165°C and maintained for another 12 hours. Afterwards, the viscous mixture was precipitated in methanol. The precipitate was then collected and washed three times with deionized water and methanol, and then dried in a drying oven at 60°C for 24 hours to obtain PESK.

[0077] The synthetic route is as follows:

[0078]

[0079] The Fourier transform infrared spectrum of PESK is shown in the figure below: Figure 3 As shown, 1 H NMR spectrum Figure 4 shown.

[0080] (3) Synthesis of methyl polyetheretherketone and polyethersulfoneketone block copolymer (KBS):

[0081] mPEEK (0.001 mol) obtained in step (1), PESK (0.001 mol) obtained in step (2), potassium carbonate (0.002 mol), N,N-dimethylacetamide (500 mL) and toluene (20 mL) were added to a 1000 mL four-necked flask equipped with a nitrogen inlet, a mechanical stirrer, a thermometer, a reflux condenser and a Dean-Stark apparatus. The mixture was then heated to 140°C and maintained at this temperature for 4 h until the water was completely separated. The temperature was raised to 165°C and maintained for another 15 h. Thereafter, the viscous mixture was precipitated in deionized water. The precipitate was then collected and washed three times with deionized water and methanol, and then dried in a drying oven at 60°C for 24 h to obtain KBS.

[0082] The synthetic route is as follows:

[0083]

[0084] KBS 1 H NMR spectrum Figure 5 shown.

[0085] (4) Synthesis of brominated block copolymer (BKBS) BKBS was prepared using N-bromosuccinimide as the bromination reagent and dibenzoyl peroxide as the initiator. The degree of bromine substitution (DBr) was determined by the amount of N-bromosuccinimide and the reaction time. In order to control the prepared MCEMs (monovalent selective cation exchange membranes) to have similar ion exchange capacities, the input amounts of different N-bromosuccinimide and dibenzoyl peroxide were controlled. Taking 80% bromination degree as an example, the synthesis process was as follows: N-bromosuccinimide (0.01 mol) and dibenzoyl peroxide (0.0008 mol) were added to a 1,1,2,2-tetrachloroethane (120 mL) solution of KBS (10 g) obtained in step (3) under mechanical stirring. The mixture was heated to 80°C and maintained for 8 h. After the reaction, the reaction mixture was poured into methanol to obtain a reddish-brown precipitate, which was filtered and washed three times with methanol. Finally, BKBS was obtained after drying at 60° C. in a drying oven for 24 h.

[0086] The synthetic route is as follows:

[0087]

[0088] BKBS 1 H NMR spectrum Figure 6 shown.

[0089] (5) Synthesis of quaternized N,N,N′,N′-tetramethyl-1,6-hexanediamine (SQTMHDA):

[0090] In a three-necked flask, N,N,N′,N′-tetramethyl-1,6-hexanediamine (0.05 mol) was dissolved in 300 mL of ethyl acetate and stirred at room temperature to form a homogeneous solution. 1,3-Propane sultone (0.01 mol) was then dissolved in 50 mL of ethyl acetate and stirred to form a homogeneous solution. The solution was then added dropwise to the ethyl acetate solution using a constant pressure dropping funnel. The mixture was stirred at room temperature for 24 hours. After the reaction, the white precipitate was filtered, washed three times with ethyl acetate, and dried in a vacuum oven at 60°C for 24 hours to obtain SQTMHDA.

[0091] The synthetic route is as follows:

[0092]

[0093] SQTMHDA 1 H NMR spectrum Figure 7 shown.

[0094] (6) Synthesis of block copolymers containing ionic side chains (SQKBS)

[0095] BKBS (20 g) obtained in step (4) was dissolved in 300 mL of N-methylpyrrolidone to form a homogeneous solution, to which a solution of SQTMHDA (obtained in step (5)) dissolved in 100 mL of N-methylpyrrolidone was then added, and the mixture was heated to 60° C. and stirred for 24 hours. After the reaction, the mixture was poured into ethyl acetate and washed three times, and then dried in a vacuum drying oven at 60° C. for 24 hours to obtain SQKBS, i.e., the block copolymer containing ionic side chains.

[0096] The synthetic route is as follows:

[0097]

[0098] SQKBS 1 H NMR spectrum Figure 8 shown.

[0099] Example 2

[0100] The difference between this embodiment and embodiment 1 is only that step (1) is different, which is as follows:

[0101] (1) Synthesis of methyl polyether ketone (mPEK):

[0102] First, terephthaloyl chloride (0.052 mol), methylhydroquinone (0.05 mol), potassium carbonate (0.10 mol), N,N-dimethylacetamide (180 mL), and toluene (20 mL) were added sequentially to a 500 mL four-necked flask equipped with a nitrogen inlet, mechanical stirrer, thermometer, reflux condenser, and Dean-Stark apparatus. Prior to operation, the entire reactor was filled with nitrogen to maintain an inert atmosphere. Next, the mixture was heated to 140°C and maintained at this temperature for 4 hours to ensure complete water separation. The temperature was then raised to 165°C and the reaction continued at this temperature for 6 hours. After the reaction, the resulting viscous mixture was precipitated in deionized water. The precipitate was then collected and washed several times with deionized water and methanol to remove impurities. Finally, the washed product was dried in a drying oven at 60°C for 24 hours to obtain the mPEK product.

[0103] The subsequent steps are the same.

[0104] Example 3

[0105] The difference between this embodiment and embodiment 1 is only that step (2) is different, which is as follows:

[0106] (2) Synthesis of polyethersulfone (PES):

[0107] First, 4,4'-difluorodiphenyl sulfone (0.05 mol), bisphenol A (0.055 mol), potassium carbonate (0.11 mol), N,N-dimethylacetamide (180 mL), and toluene (20 mL) were added to a 500 mL four-necked flask equipped with a nitrogen inlet, mechanical stirrer, thermometer, reflux condenser, and Dean-Stark apparatus. The entire reactor was flushed with nitrogen before heating. The mixture was then heated to 140°C and maintained at this temperature for 4 hours until the water completely separated. The temperature was then raised to 165°C and maintained for an additional 12 hours. Afterwards, the viscous mixture was precipitated in methanol. The precipitate was then collected and washed three times with deionized water and methanol, then dried in a drying oven at 60°C for 24 hours to obtain PES.

[0108] Example 4

[0109] The difference between this embodiment and embodiment 1 is only that step (5) is different, which is as follows:

[0110] (5) Synthesis of quaternized tetramethylhexanediamine (SQTMEDA):

[0111] In a three-necked flask, tetramethylhexanediamine (0.05 mol) was dissolved in 300 mL of ethyl acetate at room temperature and stirred to form a homogeneous solution. 1,3-Propane sultone (0.01 mol) was then dissolved in 50 mL of ethyl acetate and stirred to form a homogeneous solution. The solution was then added dropwise to the tetramethylhexanediamine ethyl acetate solution via a constant pressure dropping funnel and stirred at room temperature for 24 hours. After the reaction, the white precipitate was filtered, washed three times with ethyl acetate, and finally dried in a vacuum drying oven at 60°C for 24 hours to obtain SQTMEDA.

[0112] Example 5

[0113] The difference between this embodiment and embodiment 1 is only that step (5) is different, which is as follows:

[0114] (5) Synthesis of quaternized N,N,N′,N′-tetramethyl-1,6-hexanediamine (AQTMHDA):

[0115] In a three-necked flask, N,N,N′,N′-tetramethyl-1,6-hexanediamine (0.05 mol) was dissolved in 300 mL of ethyl acetate at room temperature and stirred to form a homogeneous solution. 3-Bromopropionic acid (0.01 mol) was then dissolved in 50 mL of ethyl acetate and stirred to form a homogeneous solution. The solution was then added dropwise to the ethyl acetate solution using a constant pressure dropping funnel. The mixture was stirred at room temperature for 24 hours. After the reaction, the white precipitate was filtered, washed three times with ethyl acetate, and dried in a vacuum oven at 60°C for 24 hours to obtain AQTMHDA.

[0116] Comparative Example 1

[0117] The only difference between this comparative example and Example 1 is that step (5) and step (6) are not included.

[0118] The Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy ( 1 The characterization method of HNMR is as follows:

[0119] (1) Fourier transform infrared spectroscopy (FT-IR)

[0120] The molecular structure of the synthesized polymer was tested by Fourier transform infrared spectroscopy with a resolution of 4 cm -1 , wavelength range is 4000-400cm -1 With potassium bromide as the background, the polymer sample needs to be dried and ground evenly with potassium bromide, and then pressed into a pellet and tested by the transmission method.

[0121] (2) H NMR spectroscopy ( 1 H NMR)

[0122] The molecular structure of the synthesized polymer was tested using a nuclear magnetic resonance spectrometer (400 MHz) with tetramethylsilane (TMS) as the internal standard and deuterated chloroform (CDCl3), deuterated dimethyl sulfoxide (DMSO-d6) and deuterated methanol (CD4O) as the solvents.

[0123] Application Example 1

[0124] In this application example, a monovalent selective cation exchange membrane is provided, and the preparation method includes the following steps:

[0125] 1.5 g of the block copolymer containing ionic side chains provided in Example 1 was dissolved in 8.5 g of N-methylpyrrolidone under stirring at room temperature to obtain a uniform solution; the solution was then allowed to stand for degassing for 12 hours, and the degassed solution was cast onto a clean glass plate with a spatula; the solution was then dried in a drying oven at 60° C. for 24 hours to evaporate the residual solvent; the prepared membrane was then peeled off by soaking in deionized water, and the prepared membrane was soaked in distilled water at room temperature for 24 hours to remove the residual solvent from the membrane to obtain the monovalent selective cation exchange membrane.

[0126] Application Examples 2-5 and Comparative Application Example 1

[0127] The only difference between Application Examples 2-5 and Comparative Application Example 1 and Application Example 1 is that the block copolymer containing ionic side chains provided in Example 1 is replaced by the block copolymer containing ionic side chains provided in Examples 2-5 and Comparative Example 1 of equal mass.

[0128] The performance test of the exchange membrane provided in the corresponding use case and comparative application example is carried out as follows:

[0129] (1) Characterization of ion exchange capacity

[0130] Due to the ionic structure of the polymer, the ion exchange capacity (IEC) of the prepared membrane includes the anion exchange capacity (AEC) and the cation exchange capacity (CEC). The actual anion exchange capacity and cation exchange capacity were determined by titration. AEC measurement: The membrane sample was immersed in a 1 mol / L NaCl aqueous solution at room temperature for 24 hours, then vacuum-dried at 60°C for 24 hours, and the mass of the membrane after drying was recorded. The membrane was then immersed in a 0.5 mol / L Na2SO4 aqueous solution for 24 hours to release the Cl in the membrane. － Finally, the solution was titrated with a 0.01 mol / L AgNO3 aqueous solution, using K2CrO4 as an indicator. CEC measurement: The membrane sample was immersed in a 1 mol / L HCl aqueous solution at room temperature for 24 h, then vacuum-dried at 60°C for 24 h, and the mass of the membrane after drying was recorded. The membrane was then immersed in a 0.5 mol / L NaCl aqueous solution for 24 h to release H + Finally, titrate with 0.01mol / L NaOH solution. The calculation formula of IEC is as follows:

[0131]

[0132] Where V represents the volume of AgNO3 or NaOH consumed during the titration process; C represents the concentration of AgNO3 or NaOH; W dry Indicates the dry film quality; AEC and CEC are calculated separately using the above formula, and then the sum of the two is IEC.

[0133] (2) Characterization of mechanical properties (tensile strength)

[0134] The mechanical properties of cation exchange membranes were tested using an electronic universal testing machine. 5 mm x 50 mm strips of cation exchange membrane material were used. Before testing, the surface moisture of the samples was removed, and the thickness and length of the samples were recorded. The samples were secured in the instrument fixture at both ends and tested at a tensile rate of 2 mm / min at room temperature in an air atmosphere. Each sample was tested five times in parallel, and the average result was used as the final test result.

[0135] (3) Selective electrodialysis

[0136] The lithium and magnesium ion flux and selectivity of the selective cation exchange membrane were tested on a laboratory-designed SED device. The operating conditions were: 120 mL of a 0.1 mol / L LiCl and 0.1 mol / L MgCl2 mixed solution as the desalination chamber solution, 120 mL of a 0.1 mol / L KCl solution as the concentration chamber solution, 240 mL of a 0.15 mol / L Na2SO4 solution as the cathode chamber solution, and an effective membrane area of ​​16 cm 2 , using atomic absorption spectrophotometer to measure Li + and Mg 2+ The concentration of ion flux and selectivity are calculated using Equations 2.4 and 2.5:

[0137]

[0138] Where J represents the ion flux (mol / cm 2 / s), C0 and C t Represent the cation concentration in the concentration chamber at time 0 and time t respectively. V represents the volume of the solution in the concentration chamber, A m represents the membrane area, and t represents the time. represents the lithium-magnesium selectivity, represents the initial magnesium ion concentration in the desalination chamber (mol / L), Indicates the initial lithium ion concentration in the desalination chamber (mol / L).

[0139] The performance test results are shown in Table 1.

[0140] Table 1

[0141]

[0142] As can be seen from Table 1, the monovalent selective cation exchange membrane prepared using the block copolymer containing ionic side chains synthesized in the embodiment of the present invention has excellent monovalent and multivalent ion separation performance. This is because the increase in hydrophobic segments leads to more significant microphase separation. At the same time, the distribution of hydrophilic and hydrophobic segments and the difference in affinity with ions promote ion transport. The prepared ion exchange membrane has high mechanical properties, which are sufficient to meet the needs of electrodialysis.

[0143] The ion exchange membrane prepared by using the block copolymer synthesized in Comparative Example 1 does not have the ability to separate monovalent and multivalent ions.

[0144] The applicant states that while the above-described embodiments illustrate the block copolymers containing ionic side chains, their preparation methods, and applications, the present invention is not limited to these embodiments. This does not necessarily mean that the present invention must rely on these embodiments for implementation. Those skilled in the art will appreciate that any improvements to the present invention, equivalent substitutions for the raw materials used, additions of auxiliary components, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for preparing a block copolymer containing ionic side chains, characterized in that: The preparation method comprises the following steps: (1) Synthesis of methyl polyaryletherketone with halogen terminal group: Adding raw material A, raw material B, an acid-binding agent, a first solvent, and a second solvent into a reactor, reacting, and post-treating to obtain a methyl polyaryletherketone with a halogen terminal group; (2) Synthesis of polyethersulfoneketone with hydroxyl end groups: Adding raw material C, raw material D, an acid-binding agent, a first solvent, and a second solvent into a reactor, reacting, and post-treating to obtain a polyethersulfoneketone having a hydroxyl terminal group; (3) Synthesis of block copolymers: The methyl polyaryletherketone with a halogen terminal group obtained in step (1), the polyethersulfoneketone with a hydroxyl terminal group obtained in step (2), an acid binding agent, a first solvent, and a second solvent are added into a reactor, reacted, and post-treated to obtain a block copolymer; (4) Synthesis of brominated block copolymers: Mixing a brominating agent, an initiator, the block copolymer obtained in step (3), and a third solvent, reacting, and post-treating to obtain a brominated block copolymer; (5) Synthesis of quaternized alkyl diamine ion compounds Mixing raw material E, raw material F, and a fourth solvent, reacting, and post-treating to obtain a quaternized alkyl diamine ion compound; (6) mixing the brominated block copolymer obtained in step (4), the quaternized alkyl diamine ion compound obtained in step (5), and the first solvent, reacting, and post-treating to obtain the block copolymer containing ionic side chains; The raw material A in step (1) comprises 4,4'-difluorobenzophenone and / or p-benzophenone; The raw material B in step (1) comprises methylhydroquinone; The raw material C in step (2) includes 4,4'-difluorodiphenyl sulfone; The raw material D in step (2) comprises 4,4'-dihydroxybenzophenone and / or bisphenol A; The raw material E in step (5) comprises any one of N,N,N′,N′-tetramethyl-1,6-hexanediamine, N,N,N′,N′-tetramethyl-1,5-pentanediamine, and tetramethylhexanediamine, or a combination of at least two thereof; The raw material F in step (5) includes any one or a combination of at least two of 1,3-propane sultone, 3-bromopropionic acid, 3-bromopropanesulfonic acid, 4-bromophenol, 4-bromobutyric acid, and 5-bromovaleric acid.

2. The preparation method according to claim 1, characterized in that In step (1), the molar ratio of raw material A to raw material B is (0.8-1.2):

1.

3. The preparation method according to claim 1, characterized in that The reaction in step (1) is first carried out at 130-150° C. for 3-5 hours, and then at 160-170° C. for 5-7 hours.

4. The preparation method according to claim 1, characterized in that The post-treatment in step (1) includes precipitation, washing and drying.

5. The preparation method according to claim 1, characterized in that In step (2), the molar ratio of raw material C to raw material D is (0.8-1.2):

1.

6. The preparation method according to claim 1, characterized in that The reaction in step (2) is first carried out at 130-150° C. for 3-5 h, and then at 160-170° C. for 10-14 h.

7. The preparation method according to claim 1, characterized in that The post-treatment in step (2) includes precipitation, washing and drying.

8. The preparation method according to claim 1, characterized in that In step (3), the molar ratio of the methyl polyaryletherketone with a halogen terminal group to the polyethersulfoneketone with a hydroxyl terminal group is (0.8-1.2):

1.

9. The preparation method according to claim 1, characterized in that The reaction in step (3) is first carried out at 130-150° C. for 3-5 h, and then at 160-170° C. for 12-15 h.

10. The preparation method according to claim 1, characterized in that The post-treatment in step (3) includes precipitation, washing and drying.

11. The preparation method according to claim 1, characterized in that The bromination reagent in step (4) includes N-bromosuccinimide.

12. The preparation method according to claim 1, characterized in that The initiator in step (4) includes dibenzoyl peroxide.

13. The preparation method according to claim 1, characterized in that The third solvent in step (4) includes 1,1,2,2-tetrachloroethane.

14. The preparation method according to claim 1, characterized in that The reaction temperature in step (4) is 70-90° C., and the reaction time is 7-9 h.

15. The preparation method according to claim 1, characterized in that The post-treatment in step (4) includes precipitation, washing and drying.

16. The preparation method according to claim 1, characterized in that In step (5), the molar ratio of raw material E to raw material F is (1-5):

1.

17. The preparation method according to claim 1, characterized in that The fourth solvent in step (5) includes any one of ethyl acetate, chloroform or methanol, or a combination of at least two of them.

18. The preparation method according to claim 1, characterized in that The reaction temperature in step (5) is 20-25° C., and the reaction time is 20-28 h.

19. The preparation method according to claim 1, characterized in that The post-processing in step (5) includes filtering, washing and drying.

20. The preparation method according to claim 1, characterized in that The reaction temperature in step (6) is 50-70° C., and the reaction time is 20-28 h.

21. The preparation method according to claim 1, characterized in that The post-treatment in step (6) includes precipitation, washing and drying.

22. The preparation method according to claim 1, characterized in that The acid binding agents in steps (1) to (3) each independently include anhydrous potassium carbonate and / or anhydrous sodium carbonate.

23. The preparation method according to claim 1, characterized in that In steps (1) to (3) and (6), the first solvent independently comprises any one of N,N-dimethylacetamide, N-methylpyrrolidone or dimethyl sulfoxide, or a combination of at least two thereof.

24. The preparation method according to claim 1, characterized in that The second solvent in steps (1) to (3) includes toluene.

25. The preparation method according to claim 1, characterized in that The reactions in steps (1) to (3) are all carried out under an inert atmosphere.

26. The preparation method according to claim 25, characterized in that The inert atmosphere includes nitrogen.

27. A block copolymer containing ionic side chains, characterized in that: The block copolymer containing ionic side chains is prepared by the preparation method according to any one of claims 1 to 26.

28. A monovalent selective cation exchange membrane, characterized in that The monovalent selective cation exchange membrane is prepared from the block copolymer containing ionic side chains according to claim 27.

29. A method for preparing a monovalent selective cation exchange membrane according to claim 28, characterized in that: The preparation method comprises the following steps: The block copolymer containing ionic side chains is dissolved in an organic solvent, degassed, and the degassed solution is cast onto a substrate and dried to obtain the monovalent selective cation exchange membrane.

30. Use of the monovalent selective cation exchange membrane according to claim 28 in electrodialysis.

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