Block copolymer containing ionic side chain as well as preparation method and application of block copolymer

Abstract

The invention provides a segmented copolymer containing an ionic side chain as well as a preparation method and application of the segmented copolymer. The preparation method comprises the following steps: (1) synthesizing methyl polyaryletherketone of which the end group is halogen; (2) synthesis of polyether sulfone ketone with hydroxyl as a terminal group; (3) synthesizing a block copolymer; (4) synthesizing a brominated block copolymer; (5) synthesizing a quaternized alkyl diamine ionic compound; and (6) mixing the brominated block copolymer, a quaternized alkyl diamine ionic compound and a first solvent, reacting, and performing post-treatment to obtain the block copolymer containing the ionic side chain. The side chain of the block copolymer containing the ion side chain obtained by the preparation method provided by the invention has two positive charges and one negative charge, and when the block copolymer containing the ion side chain is applied to an exchange membrane, the exchange membrane can have selectivity on monovalent cations, and the block copolymer containing the ion side chain is high in ion flux, selectivity and stability. In addition, the preparation method of the block copolymer containing the ionic side chain is simple.

Description

Technical Field

[0001] The invention belongs to membrane separation, and relates to a block copolymer containing ionic side chains, a preparation method and application thereof, and specifically relates 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 by surface modification can achieve efficient separation by using a thinner separation skin layer, which has less influence on membrane resistance, etc. Currently, a large number of studies are focused on this method. However, problems such as complex surface modification methods or poor stability caused by poor modified layer-group structure still limit its application.

[0004] The selective cation exchange membrane prepared by the matrix modification method can achieve selective separation of ions through a denser structure or suitable affinity, but the improvement of overall density often leads to an increase in membrane resistance and a decrease in flux. At the same time, due to the inherent characteristics of polymer membrane materials, the precise regulation of their microstructure performance is limited, making it difficult to significantly improve the selective separation performance of the membrane.

[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 in the prior art, the purpose of the present invention is to provide a block copolymer containing ionic side chains and a preparation method and application thereof, and specifically to provide a block copolymer containing ionic side chains and 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 having a halogen terminal group;

[0011] (2) Synthesis of polyether sulfone ketone with hydroxyl terminal 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 halogen terminal group obtained in step (1), the polyethersulfoneketone with hydroxyl terminal group obtained in step (2), an acid binding agent, a first solvent and a second solvent are added into a reactor for reaction and post-treatment to obtain a block copolymer;

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

[0016] The bromination reagent, the initiator, the block copolymer obtained in step (3), and the third solvent are mixed, reacted, and post-treated 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 quaternary ammonium alkyl diamine ion compound;

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

[0020] The block copolymer containing ionic side chains obtained by the preparation method provided by 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.

[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 hydroxy 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 of 1,3-propane sultone, 3-bromopropionic acid, 3-bromopropanesulfonic acid, 4-bromophenol, 4-bromobutyric acid, and 5-bromovaleric acid, or a combination of at least two thereof.

[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 filtering, 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) comprises 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 as described in 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 the synthesized block copolymer material containing ionic side chains to prepare monovalent selective cation exchange membranes, which can regulate specific functional groups or spatial structures in the membrane at the molecular level to accurately regulate 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 monovalent selective cation exchange membranes in one step, and the preparation method is simple and stable, and there is no need to change the existing industrial membrane preparation process, which is easy to industrialize. By introducing functional groups that can be ion-crosslinked into the membrane material and constructing a block copolymer material that can be microscopically phase-separated, it is expected to accurately regulate the microstructure of the membrane material and the affinity with ions, thereby achieving efficient selective separation of cations; the one-step preparation of highly selective ion exchange membranes using new functionalized 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 with the prior art, the present invention has the following beneficial effects: the block copolymer containing ionic side chains obtained by the preparation method provided by the present invention has two positive charges and one negative charge on its side chains, and when applied to an exchange membrane, the exchange membrane can be selective for monovalent cations. In addition, the preparation method of the block copolymer containing ionic side chains provided by the present invention is simple, and the preparation method of the monovalent selective cation exchange membrane is simple, 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 specific implementation methods. It should be understood by those skilled in the art that the embodiments are only 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 comprises 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 into a 500 mL four-necked flask with a nitrogen inlet, a mechanical stirrer, a thermometer, a reflux condenser and a Dean-Stark apparatus. Before operation, ensure that the entire reactor is filled with nitrogen to maintain an inert atmosphere. Next, the mixture was heated to 140 ° C and kept at this temperature for 4 h to ensure that the water was completely separated. Then, the temperature was increased to 165 ° C and the reaction was continued at this temperature for 6 h. After the reaction was completed, the viscous mixture was precipitated in deionized water. Subsequently, the precipitate was collected and washed with deionized water and methanol, and the process was repeated several times to remove impurities. Finally, the washed product was placed in a drying oven at 60 ° C and dried for 24 h 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 h until the water was completely separated. The temperature was then raised to 165 ° C and maintained for another 12 h. After that, 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 h to obtain PESK.

[0077] The synthetic route is as follows:

[0078]

[0079] The Fourier transform infrared spectrum of PESK is shown in 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 agent 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 is 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 was completed, the reaction mixture was poured into methanol to obtain a reddish brown precipitate, the precipitate was filtered and washed three times with methanol, and finally dried in a drying oven at 60° C. for 24 h to obtain BKBS.

[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] At room temperature, N,N,N′,N′-tetramethyl-1,6-hexanediamine (0.05 mol) was dissolved in 300 mL of ethyl acetate in a three-necked flask and stirred to form a uniform solution. Then, 1,3-propane sultone (0.01 mol) was dissolved in 50 mL of ethyl acetate and stirred to form a uniform solution. Then, the solution was added dropwise to the ethyl acetate solution of N,N,N′,N′-tetramethyl-1,6-hexanediamine through a constant pressure dropping funnel and stirred at room temperature for 24 hours. After the reaction was completed, the white precipitate was filtered and washed three times with ethyl acetate, and finally placed in a vacuum drying 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] The BKBS (20 g) obtained in step (4) was dissolved in 300 mL of N-methylpyrrolidone to form a uniform solution, and then a solution of SQTMHDA (obtained in step (5)) dissolved in 100 mL of N-methylpyrrolidone was added thereto, and the mixture was heated to 60° C. and stirred for 24 h. After the reaction was completed, the mixture was immersed in ethyl acetate and washed three times, and then placed in a vacuum drying oven at 60° C. and dried for 24 h to obtain SQKBS, that is, the block copolymer containing ionic side chains was obtained.

[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 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 in sequence to a 500 mL four-necked flask with a nitrogen inlet, a mechanical stirrer, a thermometer, a reflux condenser and a Dean-Stark apparatus. Before operation, ensure that the entire reactor is filled with nitrogen to maintain an inert atmosphere. Next, the mixture is heated to 140 ° C and maintained at this temperature for 4 h to ensure that the water is completely separated. Then, the temperature is increased to 165 ° C and the reaction is continued at this temperature for 6 h. After the reaction is completed, the viscous mixture is precipitated in deionized water. Subsequently, the precipitate is collected and washed with deionized water and methanol, and repeated several times to remove impurities. Finally, the washed product is placed in a drying oven at 60 ° C and dried for 24 h 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 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, 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 h until the water was completely separated. The temperature was then raised to 165 ° C and maintained for another 12 h. After that, 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 h to obtain PES.

[0108] Example 4

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

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

[0111] At room temperature, tetramethylhexanediamine (0.05 mol) was dissolved in 300 mL of ethyl acetate in a three-necked flask and stirred to form a uniform solution. Then, 1,3-propane sultone (0.01 mol) was dissolved in 50 mL of ethyl acetate and stirred to form a uniform solution. Then, the solution was dripped into the ethyl acetate solution of tetramethylhexanediamine through a constant pressure dropping funnel and stirred at room temperature for 24 hours. After the reaction was completed, the white precipitate was filtered and washed three times with ethyl acetate, and finally placed 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 that step (5) is different, which is as follows:

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

[0115] At room temperature, N,N,N′,N′-tetramethyl-1,6-hexanediamine (0.05 mol) was dissolved in 300 mL of ethyl acetate in a three-necked flask and stirred to form a uniform solution. Then, 3-bromopropionic acid (0.01 mol) was dissolved in 50 mL of ethyl acetate and stirred to form a uniform solution. Then, the solution was dripped into the ethyl acetate solution of N,N,N′,N′-tetramethyl-1,6-hexanediamine through a constant pressure dropping funnel and stirred at room temperature for 24 hours. After the reaction was completed, the white precipitate was filtered and washed three times with ethyl acetate, and finally placed in a vacuum drying 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 spectrum (FT-IR) and nuclear magnetic resonance hydrogen spectrum ( 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 tablet 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 comprises 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; then the solution was allowed to stand for degassing for 12 hours, and the degassed solution was cast onto a clean glass plate with a spatula; then the solution was dried in a drying oven at 60°C for 24 hours to evaporate the residual solvent; then the prepared membrane was 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 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, respectively.

[0128] The performance test is carried out on the exchange membrane provided in the corresponding use case and the comparative application case. The test method is 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 anion exchange capacity (AEC) and 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 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 Na2SO4 aqueous solution for 24 h to release the Cl in the membrane. － Finally, the solution was titrated with a 0.01 mol / L AgNO3 aqueous solution, and K2CrO4 was used as an indicator. CEC measurement: The membrane sample was immersed in a 1 mol / L HCl aqueous solution for 24 h at room temperature, and 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; 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 two are added together to get IEC.

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

[0134] The mechanical properties of the cation exchange membrane were tested using an electronic universal testing machine. The cation exchange membrane material sample used was 5mm×50mm. Before testing, the moisture on the sample surface was removed and the thickness and length of the sample were recorded. The two ends of the sample were fixed in the instrument fixture, and the mechanical properties of the material were tested at room temperature and air atmosphere at a tensile rate of 2mm / min. Each sample was tested in parallel 5 times, and the average value was taken 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. Operating conditions: 120 mL of a mixed solution of 0.1 mol / L LiCl and 0.1 mol / L MgCl2 was used as the desalination chamber solution, 120 mL of a 0.1 mol / L KCl solution was used as the concentration chamber solution, 240 mL of a 0.15 mol / L Na2SO4 solution was used as the cathode chamber solution, and the effective membrane area was 16 cm 2 , an atomic absorption spectrophotometer was used to measure the 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 Respectively represent the cation concentration in the concentration chamber at time 0 and time t. V represents the volume of the solution in the concentration chamber, A m represents membrane area, and t represents time. Indicates lithium-magnesium selectivity, represents the initial magnesium ion concentration in the desalination chamber (mol / L), It 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 by the block copolymer containing ionic side chains synthesized in the embodiment of the present invention has excellent monovalent and polyvalent ion separation performance. This is because the increase in the hydrophobic segment leads to a more significant microscopic phase separation, and the distribution of the hydrophilic and hydrophobic segments and the difference in affinity with the ions promote the transmission of ions; the prepared ion exchange membrane has high mechanical properties, which is sufficient to meet the needs of electrodialysis.

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

[0144] The applicant declares that the present invention uses the above-mentioned embodiments to illustrate the block copolymer containing ionic side chains and its preparation method and application, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the raw materials selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope 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 having a halogen terminal group; (2) Synthesis of polyether sulfone ketone with hydroxyl terminal 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 halogen terminal group obtained in step (1), the polyethersulfoneketone with hydroxyl terminal group obtained in step (2), an acid binding agent, a first solvent and a second solvent are added into a reactor for reaction and post-treatment to obtain a block copolymer; (4) Synthesis of brominated block copolymers: The bromination reagent, the initiator, the block copolymer obtained in step (3), and the third solvent are mixed, reacted, and post-treated 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 quaternary ammonium alkyl diamine ion compound; (6) The brominated block copolymer obtained in step (4), the quaternized alkyl diamine ion compound obtained in step (5), and the first solvent are mixed, reacted, and post-treated to obtain the block copolymer containing ionic side chains.

2. The preparation method according to claim 1, characterized in that: The raw material A in step (1) comprises 4,4'-difluorobenzophenone and / or p-benzophenone; Preferably, the raw material B in step (1) comprises methylhydroquinone; Preferably, in step (1), the molar ratio of raw material A to raw material B is (0.8-1.2):1; Preferably, the reaction in step (1) is first carried out at 130-150° C. for 3-5 h, and then at 160-170° C. for 5-7 h; Preferably, the post-treatment in step (1) includes precipitation, washing and drying; Preferably, the raw material C in step (2) comprises 4,4'-difluorodiphenyl sulfone; Preferably, the raw material D in step (2) comprises 4,4'-dihydroxybenzophenone and / or bisphenol A; Preferably, in step (2), the molar ratio of raw material C to raw material D is (0.8-1.2):1; Preferably, 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; Preferably, the post-treatment in step (2) includes precipitation, washing and drying.

3. The preparation method according to claim 1 or 2, 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; Preferably, 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; Preferably, the post-treatment in step (3) includes precipitation, washing and drying.

4. The preparation method according to any one of claims 1 to 3, characterized in that The bromination reagent in step (4) includes N-bromosuccinimide; Preferably, the initiator in step (4) comprises dibenzoyl peroxide; Preferably, the third solvent in step (4) comprises 1,1,2,2-tetrachloroethane; Preferably, the reaction temperature in step (4) is 70-90° C., and the reaction time is 7-9 h; Preferably, the post-treatment in step (4) includes precipitation, washing and drying.

5. The preparation method according to any one of claims 1 to 4, characterized in that: 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; 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; Preferably, in step (5), the molar ratio of raw material E to raw material F is (1-5):1; Preferably, the fourth solvent in step (5) comprises any one of ethyl acetate, chloroform or methanol, or a combination of at least two thereof; Preferably, the reaction temperature in step (5) is 20-25°C and the reaction time is 20-28h; Preferably, the post-treatment in step (5) includes filtering, washing and drying; Preferably, the reaction temperature in step (6) is 50-70°C and the reaction time is 20-28h; Preferably, the post-treatment in step (6) includes precipitation, washing and drying.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The acid binding agents in steps (1) to (3) each independently include anhydrous potassium carbonate and / or anhydrous sodium carbonate; Preferably, the first solvent in steps (1) to (3) and (6) independently comprises any one of N,N-dimethylacetamide, N-methylpyrrolidone or dimethyl sulfoxide, or a combination of at least two thereof; Preferably, the second solvent in steps (1) to (3) comprises toluene; Preferably, the reactions in steps (1) to (3) are all carried out under an inert atmosphere; Preferably, the inert atmosphere comprises nitrogen.

7. 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 6.

8. 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 as described in claim 7.

9. A method for preparing a monovalent selective cation exchange membrane as claimed in claim 8, 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.

10. Use of the monovalent selective cation exchange membrane according to claim 8 in electrodialysis.

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