Ordered block type polyacylated aryl piperidine membrane as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of anion exchange membranes, and discloses an ordered block type polyacylated aryl piperidine membrane as well as a preparation method and application thereof. The preparation method comprises the following steps: acylating part of p-terphenyl by adopting paraphthaloyl chloride to obtain an aromatic ketone block prepolymer which is arranged in order, then adding N-methyl-4-piperidone for copolymerization, then performing quaternization by using methyl iodide, and casting a membrane to obtain the block type polyacylated aryl piperidine membrane which is stacked in order locally. Rigid arone block limited crystals in the ordered block type polyacylated aryl piperidine membrane disclosed by the invention can strengthen hydrophilic and hydrophobic microphase separation, and can broaden and provide partially ordered limited nano channels, so that the chloride ion conductivity of the membrane is improved; and the highly-oriented rigid nano-channel skeleton cooperates with the size effect, so that permeation of active substances is blocked, the selectivity of the membrane is greatly improved, and the performance is excellent when the membrane is applied to the neutral organic flow battery.

Description

Technical Field

[0001] The invention belongs to the technical field of anion exchange membranes and relates to an ordered block polyacylated arylpiperidine membrane and a preparation method and application thereof. Background Art

[0002] Natural renewable energy sources, such as wind and solar energy, are intermittent and unstable, necessitating the use of fixed, large-scale electrochemical energy storage devices. Aqueous organic flow batteries, which utilize organic matter as redox-active materials, have attracted widespread attention due to their safety and cost-effectiveness. In particular, neutral organic flow batteries, due to their chemically less corrosive electrolytes, have shown promising application prospects.

[0003] Ion exchange membranes are a core component of flow batteries. The battery's performance depends largely on the membrane's ability to conduct charge carriers and block active materials. Neutral organic flow batteries typically need to conduct chloride ions while blocking cross-permeation of active materials at the positive and negative electrodes. The positive electrode typically uses the nitroxide free radical piperidinol, while the negative electrode uses methyl viologen and its derivatives. These materials have significantly different kinetic diameters from chloride ions. Therefore, it is crucial to design and develop membranes with high ion conductivity and selectivity by exploiting the size difference between chloride ions and active materials.

[0004] For anion exchange membranes, researchers have attempted to improve ion conductivity by designing structures with long side chains, branched structures, and block structures. However, this often results in increased permeation of active substances. Therefore, it is essential to improve selectivity while maintaining high ion conductivity. In Angew. Chem. Int. Ed., 2023, 62, e202215017, Tongwen Xu et al. utilized interchain π-π stacking between adjacent benzene rings to induce directional self-assembly and achieve highly ordered ion conduction channels. In Adv. Funct. Mater., 2023, 33, 2307041, Zidong Wei et al. prepared a novel poly(vinyl-carbazolyl arylpiperidine) copolymer containing confined ion channels measuring only 1.8 nm. These unique sub-2 nm ion channels impart high ionic conductivity and dimensional stability to the membrane. Therefore, developing poly(arylpiperidine) membranes with both high ionic conductivity and high selectivity for use in neutral organic flow batteries is of great research significance. Summary of the Invention

[0005] The present invention aims to improve the chloride ion conductivity and selectivity of an anion exchange membrane and provides a method for preparing an ordered segmented polyacylated arylpiperidine membrane. The method comprises: firstly acylating a portion of p-terphenyl with terephthaloyl chloride to obtain an ordered aromatic ketone segment prepolymer; then, adding N-methyl-4-piperidone for copolymerization to obtain a locally ordered stacked segmented polyacylated arylpiperidine polymer. The oriented local microcrystals help to block the permeation of active substances, while the restricted nanochannels provide high chloride ion conductivity, thereby preparing an anion exchange membrane with high chloride ion conductivity and high selectivity.

[0006] The technical solution of the present invention:

[0007] An ordered block polyacylated arylpiperidine film, the structure of which is as follows:

[0008]

[0009] Where, 0<y≤0.15, x+y=1;

[0010] A method for preparing an ordered block polyacylated arylpiperidine film comprises the following steps:

[0011] (1) Synthesis of polyacylated arylpiperidine: first, terephthaloyl chloride and p-terphenyl are mixed, then dichloromethane is added and stirred to disperse them uniformly; the reaction system is placed in an ice bath to keep the solution temperature at 0-5°C, then trifluoroacetic acid and trifluoromethanesulfonic acid are added dropwise in sequence under ice bath conditions, and the temperature is gradually raised to room temperature after reaction for 30-40 minutes; then the reaction system is raised to 45-50°C and the reaction is continued for 5-8 hours; then the reaction temperature is lowered to room temperature, and then the solution temperature is kept at 0-5°C in an ice bath, and N-methyl-4-piperidone is added, and the temperature is reacted under ice bath conditions for 30-40 minutes, and then the temperature is raised to room temperature, and the temperature is further reacted for 20-25 minutes to obtain a black viscous solution, and the reaction is stopped; the reactants are poured into precipitant A for precipitation, and the polyacylated arylpiperidine is obtained after drying;

[0012] The molar ratio of p-terphenyl: N-methyl-4-piperidone: terephthaloyl chloride is: 1: 0.95-1.05: 0.15-0.05;

[0013] The molar concentration of N-methyl-4-piperidone in the reaction system is 0.68 to 0.75 mol / L;

[0014] The volume ratio of trifluoroacetic acid to dichloromethane is 1:7-8;

[0015] The volume ratio of trifluoromethanesulfonic acid to dichloromethane is 1:0.6-0.7;

[0016] The molar ratio of p-terphenyl to dichloromethane is 1:7-8;

[0017] The precipitant A is methanol, ethanol or deionized water;

[0018] The specific conditions of the drying are: drying temperature is 60-80°C, and time is 24-36h;

[0019] (2) Synthesis of quaternized polyacylated arylpiperidine: The polyacylated arylpiperidine obtained in step (1) is dissolved in solvent B, potassium carbonate is added after dissolution, iodomethane is added after stirring, and the mixture is reacted at 40-45° C. in the dark for 24-36 hours. After the reaction is completed, the solution is centrifuged, and the supernatant is precipitated in ethyl acetate, washed with ethyl acetate 3-4 times, filtered, dried, and then washed with deionized water 2-3 times to remove the salt that is not completely removed. The mixture is filtered and dried to obtain the quaternized polyacylated arylpiperidine;

[0020] The mass concentration of the polyacylated arylpiperidine in solvent B is 0.025 to 0.033 g / ml;

[0021] The solvent B is N-methylpyrrolidone or dimethyl sulfoxide;

[0022] The molar ratio of the repeating unit in the polyacylated arylpiperidine: potassium carbonate: methyl iodide is 1:2.3-2.4:2.6;

[0023] The specific conditions of the drying are: drying temperature is 60-70°C, and time is 12-36 hours;

[0024] (3) Preparation of quaternized polyacylated arylpiperidine membrane: dissolving the quaternized polyacylated arylpiperidine obtained in step (2) in dimethyl sulfoxide, filtering to remove impurities after dissolution to obtain a casting solution; casting the casting solution into a glass mold, drying the solvent, peeling off the membrane, and soaking it in a 2-3 mol / L sodium chloride solution for 24-36 hours to perform sufficient ion exchange, and then soaking the membrane in deionized water to remove excess sodium chloride, thereby obtaining a quaternized polyacylated arylpiperidine membrane;

[0025] The mass concentration of the casting solution is 0.020-0.025 g / ml;

[0026] The specific conditions of the drying solvent are: drying temperature is 60-70° C., and time is 12-24 hours.

[0027] Beneficial effects of the present invention:

[0028] (1) An ordered block polyacylated arylpiperidine membrane was prepared by a one-step superacid-catalyzed acylation and Friedel-Crafts alkylation reaction. First, terphenyl and terephthaloyl chloride were prepolymerized to obtain a fully para-positioned aryl ketone rigid unit. N-methyl-4-piperidone was then added for copolymerization. The molecular chain grew in an orderly manner along the aryl ketone rigid unit. The rigid aryl ketone block crystallized in a restricted manner to obtain a partially ordered copolymer. The key to obtaining the ordered block polyacylated arylpiperidine membrane was to first add the materials in steps and then increase the temperature in stages. This highly oriented rigid nanochannel skeleton helps to block the permeation of active substances and significantly improves the selectivity of the anion exchange membrane.

[0029] (2) The designed and prepared ordered block polyacylated arylpiperidine membrane exhibited excellent battery performance when applied in neutral organic flow batteries. Compared with the di-monomer ion exchange membrane without terephthaloyl chloride modification, the energy efficiency was significantly improved, and the energy efficiency was far superior to the commercial membrane AMVN. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The permeability diagram of the commercial membrane, the membranes of Examples 1-3 and the membrane of Comparative Example 1 to the electrolyte methyl viologen and sodium chloride is shown in FIG. Figure 1 It can be seen that the methyl viologen permeabilities of the membranes of Examples 1-3 are all lower than those of the commercial membrane AMVN and the membrane of Comparative Example 1, and the methyl viologen permeability of the membrane of Example 3 is one order of magnitude lower than that of the membrane of Comparative Example 1, thereby improving the selectivity by one order of magnitude.

[0031] Figure 2 This is the nuclear magnetic hydrogen spectrum of the film of Example 3. Figure 2 The attribution of each peak proves that the quaternized polyacylated arylpiperidine membrane (x=0.85; y=0.15) was successfully synthesized.

[0032] Figure 3 The X-ray diffraction patterns of the film of Example 3 and the film of Comparative Example 1 are shown in FIG. Figure 3 The film of Example 3 has a sharp peak compared to the broad peak of the film of Comparative Example 1, which can prove the local orderliness of the polyacylated arylpiperidine film. DETAILED DESCRIPTION

[0033] The specific implementation of the present invention is further described below in conjunction with the accompanying drawings and technical solutions.

[0034] Example 1 (x=0.95; y=0.05)

[0035] An ordered block polyacylated arylpiperidine film, the structural formula of which is:

[0036]

[0037] A method for preparing an ordered block polyacylated arylpiperidine film is as follows:

[0038] Synthesis of polyacylated arylpiperidine: First, 0.083 g (0.4 mmol) of terephthaloyl chloride and 1.880 g (8.0 mmol) of p-terphenyl were added to a three-necked flask, and then 4.0 mL of dichloromethane was added and uniformly dispersed by mechanical stirring. The reaction system was then placed in an ice bath for 10 minutes to make the solution temperature less than 5°C. 0.60 mL (8.4 mmol) of trifluoroacetic acid and 6.00 mL (73 mmol) of trifluoromethanesulfonic acid were added dropwise in the ice bath. After reacting for 40 minutes under ice bath conditions, the temperature was gradually raised to room temperature, and then the reaction system was raised to 45°C and the reaction was continued for 8 hours. The viscosity of the reaction system did not increase significantly. Next, the reaction was cooled to room temperature, and then the solution temperature was adjusted to less than 5°C in an ice bath. 0.970 g (8.4 mmol) of N-methyl-4-piperidone was added, and the reaction was continued in an ice bath for 30 minutes. The temperature was then raised to room temperature and the reaction was continued for another 20 minutes to obtain a black viscous solution. The reaction was stopped, and the reactant was poured into deionized water for precipitation. After drying at 60°C for 36 hours, polyacylated aryl piperidine was obtained with a yield of 99%.

[0039] Synthesis of quaternized polyacylated arylpiperidine: 1.000 g (3.06 mmol) of polyacylated arylpiperidine was dissolved in 40 mL of dimethyl sulfoxide. After dissolution, 1.000 g (7.16 mmol) of potassium carbonate was added, and the mixture was stirred evenly. Then, 0.5 mL (7.99 mmol) of iodomethane was added. The mixture was reacted at 40° C. in the dark for 24 to 36 hours. After the reaction, the solution was centrifuged, and the supernatant was precipitated in ethyl acetate. The mixture was washed 3 to 4 times with ethyl acetate, filtered, and dried at 60° C. for 12 hours. The mixture was then washed with deionized water 2 to 3 times to remove unremoved salts. The mixture was filtered and dried at 60° C. for 24 hours to obtain the quaternized polyacylated arylpiperidine with a yield of 98%.

[0040] Preparation of quaternized polyacylated arylpiperidine membrane: 0.08 g of quaternized polyacylated arylpiperidine was dissolved in 4 mL of dimethyl sulfoxide. After dissolution, impurities were removed by filtration to obtain a casting solution. The casting solution was then cast into a glass mold and dried in a 70°C oven for 12 hours. The membrane was then removed and immersed in a 3 mol / L sodium chloride solution for 24 hours to allow for sufficient ion exchange. The membrane was then immersed in deionized water to remove excess sodium chloride to obtain a quaternized polyacylated arylpiperidine membrane.

[0041] The test results show that the quaternized polyacylated arylpiperidine film prepared in this embodiment has a Cl - Conductivity is 26.3 mS cm -1 In 3 mol / L sodium chloride solution, the water absorption rate is 23%, the swelling degree is 7%, and the permeability to the negative electrode electrolyte methyl viologen is 5.2×10 -12 cm 2 s-1 , the selectivity is 3.8×10 4 In a neutral organic flow battery (the cathode electrolyte is 0.1 mol / L nitroxyl piperidinol and the anode electrolyte is 0.15 mol / L methyl viologen), 100 mA cm -2 When the coulombic efficiency is 99.93%, the voltage efficiency is 80.75%, and the energy efficiency is 80.69%.

[0042] Example 2 (x=0.90; y=0.10)

[0043] An ordered block polyacylated arylpiperidine film, the structural formula of which is:

[0044]

[0045] A method for preparing an ordered block polyacylated arylpiperidine film is as follows:

[0046] Synthesis of polyacylated arylpiperidine: First, 0.166 g (0.8 mmol) of terephthaloyl chloride and 1.880 g (8.0 mmol) of p-terphenyl were added to a three-necked flask, and then 4.0 mL of dichloromethane was added and uniformly dispersed by mechanical stirring. The reaction system was then placed in an ice bath for 10 minutes to make the solution temperature less than 5°C. 0.50 mL (7.0 mmol) of trifluoroacetic acid and 6.70 mL (82 mmol) of trifluoromethanesulfonic acid were added dropwise in the ice bath. After reacting for 30 minutes under ice bath conditions, the temperature was gradually raised to room temperature, and then the reaction system was raised to 50°C and the reaction was continued for 5 hours. The viscosity of the reaction system did not increase significantly. Next, the reaction was cooled to room temperature, and then the solution temperature was adjusted to less than 5°C in an ice bath. 0.920 g (8.0 mmol) of N-methyl-4-piperidone was added. The reaction was continued in an ice bath for 30 minutes, and then the temperature was raised to room temperature and the reaction was continued for another 22 minutes to obtain a black viscous solution. The reaction was stopped, and the reactant was poured into deionized water for precipitation. After drying at 80°C for 24 hours, polyacylated aryl piperidine was obtained with a yield of 99%.

[0047] Synthesis of quaternized polyacylated arylpiperidine: 1.000 g (3.04 mmol) of polyacylated arylpiperidine was dissolved in 30 mL of N-methylpyrrolidone. After dissolution, 1.000 g (7.16 mmol) of potassium carbonate was added, and the mixture was stirred uniformly. Then, 0.5 mL (7.99 mmol) of iodomethane was added. The mixture was reacted at 42° C. in the dark for 24 to 36 hours. After the reaction, the solution was centrifuged, and the supernatant was precipitated in ethyl acetate. The mixture was washed 3 to 4 times with ethyl acetate, filtered, and dried at 65° C. for 12 hours. The mixture was then washed 2 to 3 times with deionized water to remove any unremoved salts. The mixture was filtered and dried at 70° C. for 12 hours to obtain the quaternized polyacylated arylpiperidine in a yield of 98%.

[0048] Preparation of quaternized polyacylated arylpiperidine membrane: 0.09 g of quaternized polyacylated arylpiperidine was dissolved in 4 mL of dimethyl sulfoxide. After dissolution, impurities were removed by filtration to obtain a casting solution. The casting solution was then cast into a glass mold and dried in a 60°C oven for 24 hours. The membrane was then removed and immersed in a 2 mol / L sodium chloride solution for 36 hours to allow for sufficient ion exchange. The membrane was then immersed in deionized water to remove excess sodium chloride to obtain a quaternized polyacylated arylpiperidine membrane.

[0049] The test results show that the quaternized polyacylated arylpiperidine film prepared in this embodiment has a Cl - Conductivity is 35.7 mS cm -1 In 3 mol / L sodium chloride solution, the water absorption rate is 22% and the swelling degree is 4%. The permeability to the negative electrode electrolyte methyl viologen is 6.3×10 -12 cm 2 s -1 , the selectivity is 3.9×10 4 In a neutral organic flow battery (the cathode electrolyte is 0.1 mol / L nitroxyl piperidinol and the anode electrolyte is 0.15 mol / L methyl viologen), 100 mA cm -2 When the coulombic efficiency is 99.85%, the voltage efficiency is 83.21%, and the energy efficiency is 83.08%.

[0050] Example 3 (x=0.85; y=0.15)

[0051] An ordered block polyacylated arylpiperidine film, the structural formula of which is:

[0052]

[0053] A method for preparing an ordered block polyacylated arylpiperidine film is as follows:

[0054] Synthesis of polyacylated arylpiperidine: 0.249 g (1.2 mmol) of terephthaloyl chloride and 1.880 g (8.0 mmol) of p-terphenyl were first added to a three-necked flask, then 4.0 mL of dichloromethane was added and dispersed uniformly by mechanical stirring, and the reaction system was placed in an ice bath for 10 min to make the solution temperature less than 5°C. 0.50 mL (7.0 mmol) of trifluoroacetic acid and 6.70 mL (82 mmol) of trifluoromethanesulfonic acid were added dropwise under the ice bath, and the reaction was carried out for 30 min under the ice bath, then the reaction system was gradually raised to room temperature, and then the reaction system was raised to 50°C for further reaction for 5 h. The viscosity of the reaction system did not increase significantly. Next, the reaction was lowered to room temperature, then the solution temperature was made less than 5°C in the ice bath, and then 0.878 g (7.6 mmol) of N-methyl-4-piperidone was added. After the reaction was carried out for 40 min under the ice bath and then raised to room temperature for 25 min, a black viscous solution was obtained, the reaction was stopped, and the reaction was poured into deionized water to precipitate. After drying at 70°C for 30 h, polyacylated arylpiperidine was obtained with a yield of 98%.

[0055] Synthesis of quaternary ammonium polyacylated arylpiperidine: 1.000 g (3.02 mmol) of polyacylated arylpiperidine was dissolved in 40 mL of N-methylpyrrolidone, 1.000 g (7.16 mmol) of potassium carbonate was added after dissolution, and 0.5 mL (7.99 mmol) of methyl iodide was added after stirring uniformly. The reaction was carried out at 45°C for 24-36 h in the dark. After the reaction was completed, the solution was centrifuged, and the supernatant was precipitated in ethyl acetate. Ethyl acetate was washed 3-4 times, filtered, and then dried at 70°C for 12 h. Then, deionized water was washed 2-3 times to remove the salt that was not completely removed, filtered, and then dried at 70°C for 30 h to obtain quaternary ammonium polyacylated arylpiperidine with a yield of 97%.

[0056] Preparation of quaternary ammonium polyacylated arylpiperidine membrane: 0.10 g of quaternary ammonium polyacylated arylpiperidine was dissolved in 4 mL of dimethyl sulfoxide, and the casting solution was obtained after filtration to remove impurities. The casting solution was cast in a glass mold, and the membrane was removed after being baked in an oven at 60°C for 24 h. The membrane was immersed in a 3 mol / L sodium chloride solution for 36 h for sufficient ion exchange, and then the membrane was immersed in deionized water to remove excess sodium chloride to obtain the quaternary ammonium polyacylated arylpiperidine membrane.

[0057] Test results show that the quaternary ammonium polyacylated arylpiperidine membrane prepared in this embodiment has a Cl - conductivity of 31.9 mS cm -1 , a water absorption rate of 20% in a 3 mol / L sodium chloride solution, and a swelling degree of 4%. The permeability of the negative electrolyte methyl viologen is 2.6 x 10 -12 cm 2 s -1, the selectivity is 8.7×10 4 In a neutral organic flow battery (the cathode electrolyte is 0.1 mol / L nitroxyl piperidinol and the anode electrolyte is 0.15 mol / L methyl viologen), 100 mA cm -2 When the coulombic efficiency is 99.73%, the voltage efficiency is 82.43%, and the energy efficiency is 82.21%.

[0058] Comparative Example 1

[0059] The present invention also synthesized a polyarylpiperidine membrane without terephthaloyl chloride to verify the effect of terephthaloyl chloride on the performance of anion exchange membrane. The specific structure is as follows:

[0060]

[0061] A method for preparing a polyarylpiperidine film free of terephthaloyl chloride is as follows:

[0062] Synthesis of polyarylpiperidines free of terephthaloyl chloride: 1.880 g (8 mmol) of p-terphenyl and 1.016 g (8.8 mmol) of N-methyl-4-piperidone were mixed with 4.0 mL of dichloromethane and uniformly dispersed by mechanical stirring. The reaction system was then placed in an ice bath for 10 minutes to keep the solution temperature below 5°C. 0.50 mL (7.0 mmol) of trifluoroacetic acid and 3.75 mL (80 mmol) of trifluoromethanesulfonic acid were then added dropwise in the ice bath. The mixture was reacted for 40 minutes under ice bath conditions, then gradually warmed to room temperature and continued to react until a black viscous solution was obtained. The reaction was terminated, and the reactants were poured into methanol as a precipitant for precipitation. The mixture was dried at 60°C for 24 hours to obtain polyarylpiperidines free of terephthaloyl chloride in a yield of 99%.

[0063] Synthesis of quaternized polyarylpiperidine: 1.000 g (3.07 mmol) of polyarylpiperidine free of terephthaloyl chloride was dissolved in 30 mL of dimethyl sulfoxide. After dissolution, 1.000 g (7.16 mmol) of potassium carbonate was added, and after stirring, 0.5 mL (7.99 mmol) of iodomethane was added. The mixture was reacted at 40° C. in the dark for 24 to 36 hours. After the reaction, the solution was centrifuged, and the supernatant was precipitated in ethyl acetate. The mixture was washed 3 to 4 times with ethyl acetate, filtered, and dried at 60° C. for 12 hours. The mixture was then washed 2 to 3 times with deionized water to remove unremoved salts. The mixture was filtered and dried at 60° C. for 24 hours to obtain the quaternized polyarylpiperidine in a yield of 98%.

[0064] Preparation of quaternized polyarylpiperidine membrane: 0.08 g of quaternized polyacylated arylpiperidine was dissolved in 4 mL of dimethyl sulfoxide. After dissolution, the mixture was filtered to remove impurities to obtain a casting solution. The casting solution was then cast into a glass mold and dried in a 70°C oven for 12 h. The membrane was then removed and immersed in a 3 mol / L sodium chloride solution for 24 h to allow for sufficient ion exchange. The membrane was then immersed in deionized water to remove excess sodium chloride to obtain a quaternized polyarylpiperidine membrane.

[0065] The properties of polyarylpiperidine film without terephthaloyl chloride were tested. The results are as follows: - Conductivity is 21 mS cm -1 In 3 mol / L sodium chloride solution, the water absorption rate is 26% and the swelling degree is 9%. The permeability to the negative electrode electrolyte methyl viologen is 4.2×10 -11 cm 2 s -1 , the selectivity is 4.1×10 3 In a neutral organic flow battery, 100mAcm -2 When the coulombic efficiency is 99.78%, the voltage efficiency is 78.59%, and the energy efficiency is 78.42%.

[0066] The performance of commercial membrane AMVN was tested and the results are as follows: Commercial membrane AMVN Cl - Conductivity is 6mS cm -1 In 3 mol / L sodium chloride solution, the water absorption rate is 19% and the swelling degree is 5%. The permeability to the negative electrode electrolyte methyl viologen is 2.0×10 -11 cm 2 s -1 , the selectivity is 1.6×10 3 In a neutral organic flow battery, 100mAcm -2 When the coulombic efficiency is 99.98%, the voltage efficiency is 57.08%, and the energy efficiency is 56.67%.

[0067] Comparative Example 2

[0068] Referring to Example 3, the preparation method of the non-blocked polyacylated arylpiperidine film is as follows:

[0069] Synthesis of polyacylated arylpiperidine: First, 0.249 g (1.2 mmol) of terephthaloyl chloride, 1.880 g (8.0 mmol) of p-terphenyl and 0.878 g (7.6 mmol) of N-methyl-4-piperidone were added to a three-necked flask, and then 4.0 mL of dichloromethane was added and uniformly dispersed by mechanical stirring. The reaction system was then placed in an ice bath for 10 minutes to make the solution temperature less than 5°C. 0.50 mL (7.0 mmol) of trifluoroacetic acid and 6.70 mL (82 mmol) of trifluoromethanesulfonic acid were added dropwise in an ice bath. After reacting for 30 minutes under ice bath conditions, the temperature was gradually raised to room temperature. After reacting for 5 to 6 hours at room temperature, the viscosity of the reaction system did not increase significantly. The reactants were poured into deionized water for precipitation, and only a powdery white solid was obtained. The molecular weight was too small to meet the film-forming conditions.

[0070] Comparative Example 3

[0071] Referring to Example 3, the preparation method of the non-blocked polyacylated arylpiperidine film is as follows:

[0072] Synthesis of polyacylated arylpiperidine: First, 0.249 g (1.2 mmol) of terephthaloyl chloride, 1.880 g (8.0 mmol) of p-terphenyl and 0.878 g (7.6 mmol) of N-methyl-4-piperidone were added to a three-necked flask, and then 4.0 mL of dichloromethane was added and uniformly dispersed by mechanical stirring. The reaction system was then placed in an ice bath for 10 minutes to make the solution temperature less than 5°C. 0.50 mL (7.0 mmol) of trifluoroacetic acid and 6.70 mL (82 mmol) of trifluoromethanesulfonic acid were added dropwise in an ice bath. After reacting for 30 minutes under ice bath conditions, the temperature was gradually raised to room temperature. After reacting at room temperature for 5 hours, the viscosity of the reaction system did not increase significantly. The reaction system was then raised to 50°C and the reaction was continued for 5 hours. It was observed that the viscosity of the reaction system increased. The reactants were poured into deionized water for precipitation to obtain a lumpy white solid, but it could be crushed with a little force. It had low mechanical strength and a small molecular weight, and could not meet the film-forming conditions.

[0073] These results confirm that the preparation of ordered block-type polyacylated arylpiperidine membranes requires a step-by-step process followed by a phased temperature increase. While the viscosity of the reaction system does not increase significantly during the acylation reaction of terephthaloyl chloride with p-terphenyl, an ordered aryl ketone block is formed. With the subsequent addition of N-methyl-4-piperidone, the molecular chain continues to grow along the rigid aryl ketone block, undergoing a Friedel-Crafts alkylation polymerization reaction. Without a phased feeding process, the acylation and Friedel-Crafts alkylation reactions compete, resulting in a difficult viscosity increase in the polymer system and an inability to produce a high molecular weight polymer. Even if the viscosity increases with subsequent temperature increase, film formation conditions are not met.

[0074] Therefore, the pre-introduction of terephthaloyl chloride can produce a locally ordered stacked block-type polyacylated arylpiperidine membrane. The rigid aryl ketone block-restricted crystallization within the membrane can enhance the hydrophilic and hydrophobic microphase separation, widen and provide partially ordered confined nanochannels, and thus improve the chloride ion conductivity of the membrane. The highly oriented rigid nanochannel skeleton and the synergistic size effect help to block the permeation of active substances. It was found that the quaternized polyacylated arylpiperidine membrane of Example 3 had the lowest permeability to the negative electrode electrolyte methyl viologen, which was 2.6×10 -12 cm 2 s -1 , the selectivity reached 8.7×10 4 The selectivity of the membrane was increased by 21 times compared to that of the dimeric polyarylpiperidine membrane, fully demonstrating the advantage of locally ordered stacking of block-type polyacylated arylpiperidine membranes in improving selectivity. This is very beneficial for the high selectivity and cycling stability of neutral organic flow batteries.

Claims

1. An ordered block polyacylated arylpiperidine film, characterized in that: The structure of the ordered block polyacylated arylpiperidine film is as follows: Among them, 0<y≤0.15, x+y=1.

2. A method for preparing an ordered block polyacylated arylpiperidine film, characterized in that: Here are the steps: (1) Synthesis of polyacylated arylpiperidine: first, terephthaloyl chloride and p-terphenyl were mixed, then dichloromethane was added and stirred to disperse them evenly; the reaction system was placed in an ice bath for 10 minutes to make the solution temperature less than 5°C, then trifluoroacetic acid and trifluoromethanesulfonic acid were added dropwise in sequence under ice bath conditions, and the temperature was gradually raised to room temperature after 0.5 hours; then the reaction system was raised to 50°C and the reaction was continued for 5 hours; then the reaction was lowered to room temperature, and then the temperature of the solution was lowered to less than 5°C in an ice bath, and N-methyl-4-piperidone was added, and the temperature was raised to room temperature after 0.5 hours under ice bath conditions, and the temperature was further reacted for 25 minutes to obtain a black viscous solution, and the reaction was stopped; the reactants were poured into precipitant A for precipitation, and the polyacylated arylpiperidine was obtained after drying; (2) Synthesis of quaternized polyacylated arylpiperidine: The polyacylated arylpiperidine obtained in step (1) is dissolved in solvent B, potassium carbonate is added after dissolution, iodomethane is added after stirring, and the mixture is reacted at 40° C. in the dark for 24 to 36 hours. After the reaction is completed, the solution is centrifuged, and the supernatant is precipitated in ethyl acetate, washed with ethyl acetate 3 to 4 times, filtered, and dried at 60° C. for 12 hours, and then washed with deionized water 2 to 3 times to remove the salt that is not completely removed, filtered, and dried to obtain the quaternized polyacylated arylpiperidine; (3) Preparation of quaternized polyacylated arylpiperidine membrane: The quaternized polyacylated arylpiperidine obtained in step (2) is dissolved in dimethyl sulfoxide, and after dissolution, the impurities are filtered to obtain a casting solution; the casting solution is then cast into a glass mold, and after drying the solvent, the membrane is peeled off and immersed in a 3 mol / L sodium chloride solution for 24 hours to perform sufficient ion exchange, and then the membrane is immersed in deionized water for 24 hours to remove excess sodium chloride, thereby obtaining a quaternized polyacylated arylpiperidine membrane.

3. The preparation method according to claim 2, characterized in that In step (1), The molar ratio of p-terphenyl: N-methyl-4-piperidone: terephthaloyl chloride is: 1: 0.95-1.05: 0.15-0.05; The molar concentration of N-methyl-4-piperidone in the reaction system is 0.68 to 0.75 mol / L; The volume ratio of trifluoroacetic acid to dichloromethane is 1:7-8; The volume ratio of trifluoromethanesulfonic acid to dichloromethane is 1:0.6-0.7; The molar ratio of p-terphenyl to dichloromethane is 1:7-8; The precipitant A is methanol, ethanol or deionized water; The specific conditions of the drying are: a drying temperature of 60 to 80° C. and a drying time of 24 to 36 hours.

4. The preparation method according to claim 2, characterized in that In step (2), The mass concentration of the polyacylated arylpiperidine in solvent B is 0.025 to 0.033 g / ml; The solvent B is N-methylpyrrolidone or dimethyl sulfoxide; The molar ratio of the repeating unit in the polyacylated arylpiperidine: potassium carbonate: methyl iodide is 1:2.3-2.4:2.6; The specific conditions of the drying are: a drying temperature of 60 to 70° C. and a drying time of 24 to 36 hours.

5. The preparation method according to claim 2, characterized in that In step (3), The mass concentration of the casting solution is 0.020-0.025 g / ml; The specific conditions of the drying solvent are: drying temperature is 60-70° C., and time is 12-24 hours.

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