Cross-linked poly (diphenyl sulfide piperidine) anion exchange membrane material as well as preparation method and application thereof

Abstract

The invention provides a cross-linked poly (diphenyl sulfide piperidine) anion exchange membrane material and a preparation method and application thereof, and belongs to the field of ion exchange membranes and preparation thereof.The molecular structural formula of the anion exchange membrane material is as shown in the formula 1: in the formula 1 # imgabs0 #, the content of a functional structural unit is 0.35, the content x of a cross-linked structural unit is 0.30-0.60, and the content x of the cross-linked structural unit is 0.30-0.60. The content x of the non-functionalized structural unit is 0.65-x = 0.05-0.35, and the polymerization degree n = 300-1000. The cross-linked poly (diphenyl sulfide piperidine) anion exchange membrane material is prepared through a Friedel-Crafts condensation polymerization reaction and a Menshutkin reaction, and a hydrophobic cross-linked structure introduced into the anion exchange membrane material can inhibit swelling of the membrane material.

Description

Technical Field

[0001] The present invention belongs to the field of ion exchange membranes and their preparation, and in particular relates to a cross-linked poly (piperidinium diphenyl sulfide) anion exchange membrane material, a preparation method and an application thereof. Background Art

[0002] Polymer electrolyte membrane water electrolysis technology for hydrogen production offers advantages such as zero carbon emissions and efficient hydrogen production. Combining it with renewable energy is a promising technology for synergistically promoting carbon reduction, pollution reduction, green energy expansion, and economic growth. Compared with proton exchange membrane water electrolysis and alkaline water electrolysis, anion exchange membrane water electrolysis offers faster redox reaction kinetics and lower electrode costs, making it an emerging technology.

[0003] Anion exchange membranes are the core material in hydrogen production by water electrolysis. They primarily transport ions, prevent gas cross-contamination, and separate the two electrodes of the battery. Their performance directly impacts the efficiency and lifespan of individual cells. Currently, there is a pressing need to find a balance between chemical stability, dimensional stability, and ionic conductivity in oxygen-free backbone anion exchange membrane materials with excellent chemical stability and design flexibility.

[0004] CN118930784A proposes an anion exchange membrane material with a grafted flexible side chain cationic group containing a thioether flexible spacer. The presence of the thioether flexible spacer improves the toughness of the polymer membrane material and synergistically introduces a piperidinium ion salt with a long flexible side chain to form a bipiperidinium structure to improve ion conductivity. However, severe water absorption and swelling lead to ion dilution in the membrane, which has an adverse effect on ion conductivity. When the IEC value of the anion exchange membrane reaches 1.96 mmol g -1 When the WU (percentage of membrane mass change before and after water absorption) at 80℃ is 57.5%, SR (change in membrane length before and after water absorption) is 20.6%, and OH - The ionic conductivity reaches 117.1 mS cm -1 After 520 hours of treatment in 2M NaOH, the conductivity retention of the membrane sample reached 89.1%. However, this anion exchange membrane grafted with flexible side-chain cationic groups and containing thioether flexible spacers suffers from high water absorption and swelling rates. Summary of the Invention

[0005] The purpose of the present invention is to address the above shortcomings and provide a cross-linked poly (piperidine diphenyl sulfide) anion exchange membrane material and its preparation method and application. The invention aims to prepare a cross-linked poly (piperidine diphenyl sulfide) anion exchange membrane material through Friedel-Crafts polycondensation reaction and Menshutkin reaction. The hydrophobic cross-linked structure introduced into the anion exchange membrane material can inhibit the swelling of the membrane material, hinder the dilution of ions in the membrane material, and significantly improve the hydroxide ion conductivity. At the same time, the cross-linked network formed by the hydrophobic cross-linking agent can also improve the mechanical strength of the membrane.

[0006] In one aspect, the present invention provides a cross-linked poly (piperidinium diphenyl sulfide) anion exchange membrane material, the molecular structure of which is shown in Formula 1:

[0007] Formula 1 In formula 1, 0.35 is the content of functionalized structural units; x is the content of cross-linked structural units, x = 0.30 to 0.60; 0.65-x is the content of non-functionalized structural units, 0.65-x = 0.05 to 0.35; and the degree of polymerization n = 300 to 1000.

[0008] The second aspect of the present invention provides a method for preparing a cross-linked poly (piperidinium diphenyl sulfide) anion exchange membrane material, and the reaction route equation is:

[0009] The steps include: Step A. Preparation of polyphenylene sulfide-piperidine polymer with sulfide flexible spacer: using phenylene sulfide and 1-methyl-4-piperidone as raw materials, carrying out Friedel-Crafts polycondensation reaction in an organic solvent with trifluoromethanesulfonic acid as catalyst to obtain polyphenylene sulfide-piperidine polymer with sulfide flexible spacer; Step B. Preparation of 6-bromohexyl-1-methylpiperidinium bromide: Under N2 conditions, 1,6-dibromohexane is used as a raw material, and a mixture of 1-methylpiperidine and an organic solvent is added dropwise in an organic solvent environment. After post-treatment, 6-bromohexyl-1-methylpiperidinium bromide is obtained; Step C. Preparation of cross-linked poly (piperidine diphenyl sulfide) anion exchange membrane material: The sulfide flexible spacer poly (piperidine diphenyl sulfide) polymer prepared in step A and N-methylpyrrolidone are heated and stirred in an inert gas atmosphere, K2CO3 is added first, and then the 6-bromohexyl-1-methylpiperidinium bromide prepared in step B is added. After keeping the temperature for a period of time, 1,6-dibromohexane is added to carry out a Menshutkin reaction. After the reaction is completed, the reaction solution is filtered and poured into a membrane mold to obtain a cross-linked poly (piperidine diphenyl sulfide) anion exchange membrane.

[0010] Furthermore, the specific steps are as follows: Step A. Preparation of a sulfide flexible spacer polyphenylene sulfide-piperidine polymer: Phenylene sulfide, 1-methyl-4-piperidone, and dichloromethane are added to a three-necked flask and stirred in an ice bath. Trifluoromethanesulfonic acid is added thereto, and the reaction is continued in an ice bath. The ice bath is then removed and the reaction is continued at room temperature. The mixture is diluted with dichloromethane and precipitated in an alkaline solution to obtain a white, thin solid. The solid is separated and washed several times with deionized water until neutral, and dried to obtain a sulfide flexible spacer polyphenylene sulfide-piperidine polymer. The structural formula of the sulfide flexible spacer polyphenylene sulfide piperidine polymer is shown in Formula 2:

[0011] Formula 2 Step B. Preparation of 6-bromohexyl-1-methylpiperidinium bromide: 1,6-dibromohexane and ethyl acetate were added to a three-necked flask equipped with a stirrer and a N2 inlet and outlet. After heating and stirring thoroughly, a mixture of 1-methylpiperidine and ethyl acetate was added dropwise to the three-necked flask through a constant pressure funnel, and the mixture was further stirred. After the reaction was completed, the product was filtered and washed several times with ethyl acetate, and then dried to obtain a white solid powder containing 6-bromohexyl-1-methylpiperidinium bromide; The reaction equation for this step is:

[0012] The structural formula of 6-bromohexyl-1-methylpiperidinium bromide is shown in Formula 3:

[0013] Formula 3 Step C. Preparation of cross-linked poly (piperidine diphenyl sulfide) anion exchange membrane material: add the sulfide flexible spacer poly (piperidine diphenyl sulfide) polymer prepared in step A and N-methylpyrrolidone to a flask with a nitrogen inlet and outlet, heat and stir, add K2CO3 after the polymer is dissolved, and then add the 6-bromohexyl-1-methylpiperidinium bromide prepared in step B. After keeping warm for a period of time, cool to room temperature, add 1,6-dibromohexane, continue stirring, filter the reaction solution, pour it into a membrane mold, and dry it to obtain a cross-linked poly (piperidine diphenyl sulfide) anion exchange membrane.

[0014] Furthermore, in step A, the molar ratio of diphenyl sulfide to 1-methyl-4-piperidone is 1:1 to 1:1.3.

[0015] Furthermore, in step A, the molar ratio of trifluoromethanesulfonic acid to 1-methyl-4-piperidone is 3:1 to 4:1.

[0016] Furthermore, in step B, the amount of 1,6-dibromohexane used is 3 to 5 times that of 1-methylpiperidine, the reaction temperature is 40 to 60° C., and the reaction time is 6 to 12 hours.

[0017] Furthermore, in the step C, the amount of N-methylpyrrolidone used is 40 to 80 times the mass of the sulfide flexible spacer polyphenylene sulfide piperidine polymer.

[0018] Furthermore, in the step C, the molar ratio of K2CO3 to the sum of 6-bromohexyl-1-methylpiperidinium bromide and 2 times the amount of 1,6-dibromohexane is 1:1.

[0019] Furthermore, in the step C, the molar ratio of 1,6-dibromohexane to the sulfide flexible spacer polyphenylene sulfide piperidine polymer is 0.15 to 0.30:1.

[0020] Furthermore, in step C, the molar ratio of 1,6-dibromohexane to the sulfide flexible spacer polyphenylene sulfide piperidine polymer is 0.15 to 0.30:1; the reaction conditions for adding 1,6-dibromohexane are: reaction temperature of 20 to 30°C, and reaction time of 0.5 to 2 h.

[0021] The third aspect of the present invention further provides an application of the cross-linked poly(piperidine diphenyl sulfide) anion exchange membrane material. The cross-linked poly(piperidine diphenyl sulfide) anion exchange membrane material can be used as a key component in an alkaline water electrolysis cell.

[0022] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention designs and synthesizes a cross-linked poly(piperidinium diphenyl sulfide) anion exchange membrane material, introduces a cross-linking structure between polymer molecular chains, and increases the IEC value of the polymer. On the one hand, the cross-linking structure inhibits the swelling rate of the membrane, increases the ion concentration in the membrane, and improves the ion conductivity of the membrane. On the other hand, the cross-linking structure reduces the membrane's absorption of electrolytes, reduces the concentration of alkali solution in the membrane, and improves the membrane's alkali resistance stability. At the same time, the increase in the IEC value can avoid a significant decrease in the membrane's water absorption capacity due to excessive cross-linking. By adjusting the degree of cross-linking, the microphase separation structure of the membrane material is improved, further improving the ion conductivity of the polymer membrane material.

[0023] (2) The cross-linked poly (piperidine diphenyl sulfide) anion exchange membrane material provided by the present invention is prepared by the Menshutkin reaction and can be directly used to prepare an ion exchange membrane by a film casting method. The prepared ion exchange membrane has good ion conductivity, dimensional stability (low water absorption and low) and chemical stability, and can be used as an ion exchange membrane material in alkaline water electrolyzers for hydrogen production. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The synthetic route of the cross-linked poly (piperidine diphenyl sulfide) anion exchange membrane material of the present invention is as follows; Figure 2 This is the NMR spectrum of the polymer containing a thioether flexible spacer prepared in Example 1 of the present invention; Figure 3 This is the NMR spectrum of the 6-bromohexyl-1-methylpiperidinium bromide prepared in Example 1 of the present invention; Figure 4 is the nuclear magnetic resonance spectrum of the cross-linked poly (piperidine diphenyl sulfide) polymer prepared in Example 1 of the present invention; Figure 5 Graph showing the ion conductivity of the cross-linked poly(piperidine diphenyl sulfide) anion exchange membranes prepared in Examples 1, 2, 3, and 4 of the present invention; Figure 6 This is a graph showing the alkali resistance stability of the cross-linked poly(piperidinium diphenyl sulfide) anion exchange membrane described in Example 3 of the present invention; Figure 7 This is a diagram showing the durability and stability of the water electrolysis cell of the cross-linked poly(piperidinyl diphenyl sulfide) anion exchange membrane described in Example 3 of the present invention. DETAILED DESCRIPTION

[0025] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the examples in the specification. Unless otherwise specified, the methods described are all conventional methods, and the raw materials described can be obtained from public commercial channels unless otherwise specified.

[0026] As used herein, "one embodiment" or "embodiment" refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0027] The sources of the drugs and reagents described in the examples are as follows: 1,6-Dibromohexane: Anaiji Chemical, ≥98.0% 1-Methylpiperidine: Anaiji Chemical, ≥97.0% Ethyl acetate: Shanghai Lingfeng Chemical Reagent Co., Ltd., AR Phenyl sulfide: Anaiji Chemical, ≥98% 1-Methyl-4-piperidone: Anaiji Chemical, ≥98% Trifluoromethanesulfonic acid: Anaiji Chemical, 99% Dichloromethane: Shanghai Lingfeng Chemical Reagent Co., Ltd., AR N-Methylpyrrolidone: aladdin, ≥99.5% Potassium carbonate: Shanghai Lingfeng Chemical Reagent Co., Ltd., ≥99.0%.

[0028] according to Figure 1 The synthesis was carried out according to the reaction scheme shown.

[0029] The specific preparation method is as follows: Step A. Preparation of a sulfide flexible spacer polyphenylene sulfide-piperidine polymer: Phenylene sulfide, 1-methyl-4-piperidone, and dichloromethane are added to a three-necked flask and stirred in an ice bath. Trifluoromethanesulfonic acid is added thereto, and the reaction is continued in an ice bath. The ice bath is then removed and the reaction is continued at room temperature. The mixture is diluted with dichloromethane and precipitated in an alkaline solution to obtain a white, thin solid. The solid is separated and washed several times with deionized water until neutral, and dried to obtain a sulfide flexible spacer polyphenylene sulfide-piperidine polymer. Step B. Preparation of 6-bromohexyl-1-methylpiperidinium bromide: 1,6-dibromohexane and ethyl acetate were added to a three-necked flask equipped with a stirrer and a N2 inlet and outlet. After heating and stirring thoroughly, a mixture of 1-methylpiperidine and ethyl acetate was added dropwise to the three-necked flask through a constant pressure funnel, and the mixture was further stirred. After the reaction was completed, the product was filtered and washed several times with ethyl acetate, and then dried to obtain a white solid powder containing 6-bromohexyl-1-methylpiperidinium bromide; Step C. Preparation of cross-linked poly (piperidine diphenyl sulfide) anion exchange membrane material: add the sulfide flexible spacer poly (piperidine diphenyl sulfide) polymer prepared in step A and N-methylpyrrolidone to a flask with a nitrogen inlet and outlet, heat and stir, add K2CO3 after the polymer is dissolved, and then add the 6-bromohexyl-1-methylpiperidinium bromide prepared in step B. After keeping warm for a period of time, cool to room temperature, add 1,6-dibromohexane, continue stirring, filter the reaction solution, pour it into a membrane mold, and dry it to obtain a cross-linked poly (piperidine diphenyl sulfide) anion exchange membrane.

[0030] The following is a detailed description of the raw material feeding amounts and specific reaction conditions in the examples.

[0031] Example 1 according to Figure 1 The synthesis route shown Step A. Preparation of polyphenylene sulfide-piperidine polymer with a sulfide flexible spacer: 3.7254 g (20 mmol) of phenylene sulfide, 2.38 g (21 mmol) of 1-methyl-4-piperidone, and 10 mL of dichloromethane were added to a 100 mL three-necked flask. After stirring in an ice bath for 20 min, 6 mL (67 mmol) of trifluoromethanesulfonic acid was slowly added. The reaction was continued in an ice bath for 30 min, after which the ice bath was removed and the reaction continued at room temperature for 12 h. The solution became highly viscous and was diluted with dichloromethane. The solution then settled in an alkaline solution to yield a white, thin solid. This solid was isolated, washed several times with deionized water until neutral, and dried at 60°C for 24 h to yield polyphenylene sulfide-piperidine polymer (PPSP). The NMR spectrum of the sulfide flexible spacer polyphenylene sulfide piperidine polymer PPSP was measured as follows Figure 2 shown.

[0032] Step B. Preparation of 6-bromohexyl-1-methylpiperidinium bromide: 49.79 g of 1,6-dibromohexane (200 mmol) and 30 mL of ethyl acetate were added to a 100 mL three-necked flask equipped with a stirrer and N2 inlet and outlet, and stirred thoroughly at 60 ° C for 30 min. Then, 4.09 g (40 mmol) of 1-methylpiperidine and 70 mL of ethyl acetate were added dropwise to the mixture through a constant pressure funnel, and the mixture was further stirred for 12 hours. After the reaction was completed, the product was filtered and washed several times with ethyl acetate. It was then dried in vacuo at 60 ° C for 12 hours to obtain 6-bromohexyl-1-methylpiperidinium bromide (Br-6-Pip) as a white solid powder; The Br-6-Pip NMR spectrum was measured by sampling. Figure 3 shown.

[0033] Step C. Preparation of cross-linked poly(piperidinium diphenyl sulfide) anion exchange membrane material: 0.60 g of PPSP and 15 mL of N-methylpyrrolidone were added to a 100 mL three-necked flask equipped with a nitrogen inlet and outlet and stirred at 80°C for approximately 30 minutes. After the polymer was completely dissolved, 0.19 g of K2CO3 (1.3858 mmol) and then 0.2561 g of Br-6-Pip (0.7462 mmol) were added. After 3 days, heating was stopped. After cooling to room temperature, 0.08 g of 1,6-dibromohexane (0.3198 mmol) was added and stirring continued for 1 hour.

[0034] The NMR spectrum of cross-linked poly (piperidine diphenyl sulfide) polymer was measured as follows: Figure 4 shown.

[0035] The reaction solution was filtered through a G4 sand core funnel and poured into the prepared membrane mold, and then dried to obtain a cross-linked poly (piperidinium diphenyl sulfide) anion exchange membrane PPSP35-Co30.

[0036] Example 2 Step A. Preparation of polyphenylene sulfide-piperidine polymer with a sulfide flexible spacer: 3.7254 g (20 mmol) of phenylene sulfide, 2.38 g (21 mmol) of 1-methyl-4-piperidone, and 10 mL of dichloromethane were added to a 100 mL three-necked flask. After stirring in an ice bath for 20 min, 6 mL (67 mmol) of trifluoromethanesulfonic acid was slowly added. The reaction was continued in an ice bath for 30 min, after which the ice bath was removed and the reaction continued at room temperature for 12 h. The solution became highly viscous and was diluted with dichloromethane. The solution then settled in an alkaline solution to yield a white, thin solid. This solid was isolated, washed several times with deionized water until neutral, and dried at 60°C for 24 h to yield polyphenylene sulfide-piperidine polymer (PPSP). Step B. Preparation of 6-bromohexyl-1-methylpiperidinium bromide: 49.79 g of 1,6-dibromohexane (200 mmol) and 30 mL of ethyl acetate were added to a 100 mL three-necked flask equipped with a stirrer and N2 inlet and outlet, and stirred thoroughly at 60 ° C for 30 min. Then, 4.09 g (40 mmol) of 1-methylpiperidine and 70 mL of ethyl acetate were added dropwise to the mixture through a constant pressure funnel, and the mixture was further stirred for 12 hours. After the reaction was completed, the product was filtered and washed several times with ethyl acetate. It was then dried in vacuo at 60 ° C for 12 hours to obtain 6-bromohexyl-1-methylpiperidinium bromide (Br-6-Pip) as a white solid powder; Step C. Preparation of a cross-linked poly(piperidinium diphenyl sulfide) anion exchange membrane material: 0.60 g (2.1320 mmol) of PPSP and 15 mL of N-methylpyrrolidone were added to a 100 mL three-necked flask equipped with a nitrogen inlet and outlet. The mixture was stirred at 80°C for approximately 30 minutes. After the polymer was completely dissolved, 0.22 g of K2CO3 (1.5990 mmol) and then 0.2561 g of Br-6-Pip (0.7462 mmol) were added. Heating was stopped after 3 days. After cooling to room temperature, 0.10 g of 1,6-dibromohexane (0.4264 mmol) was added and stirring continued for 1 hour. The reaction solution was filtered using a G4 fritted funnel and poured into the prepared membrane mold. After drying, the cross-linked poly(piperidinium diphenyl sulfide) anion exchange membrane PPSP35-Co40 was obtained.

[0037] Example 3 Step A. Preparation of polyphenylene sulfide-piperidine polymer with a sulfide flexible spacer: 3.7254 g (20 mmol) of phenylene sulfide, 2.38 g (21 mmol) of 1-methyl-4-piperidone, and 10 mL of dichloromethane were added to a 100 mL three-necked flask. After stirring in an ice bath for 20 min, 6 mL (67 mmol) of trifluoromethanesulfonic acid was slowly added. The reaction was continued in an ice bath for 30 min, after which the ice bath was removed and the reaction continued at room temperature for 12 h. The solution became highly viscous and was diluted with dichloromethane. The solution then settled in an alkaline solution to yield a white, thin solid. This solid was isolated, washed several times with deionized water until neutral, and dried at 60°C for 24 h to yield polyphenylene sulfide-piperidine polymer (PPSP). Step B. Preparation of 6-bromohexyl-1-methylpiperidinium bromide: 49.79 g of 1,6-dibromohexane (200 mmol) and 30 mL of ethyl acetate were added to a 100 mL three-necked flask equipped with a stirrer and N2 inlet and outlet, and stirred thoroughly at 60 ° C for 30 min. Then, 4.09 g (40 mmol) of 1-methylpiperidine and 70 mL of ethyl acetate were added dropwise to the mixture through a constant pressure funnel, and the mixture was further stirred for 12 hours. After the reaction was completed, the product was filtered and washed several times with ethyl acetate. It was then dried in vacuo at 60 ° C for 12 hours to obtain 6-bromohexyl-1-methylpiperidinium bromide (Br-6-Pip) as a white solid powder; Step C. Preparation of a cross-linked poly(piperidinium diphenyl sulfide) anion exchange membrane material: 0.60 g (2.1320 mmol) of PPSP and 15 mL of N-methylpyrrolidone were added to a 100 mL three-necked flask equipped with a nitrogen inlet and outlet and stirred at 80°C for approximately 30 minutes. After the polymer was completely dissolved, 0.25 g of K2CO3 (1.8122 mmol) and then 0.2561 g of Br-6-Pip (0.7462 mmol) were added. Heating was discontinued after 3 days. After cooling to room temperature, 0.13 g of 1,6-dibromohexane (0.5330 mmol) was added and stirring continued for 1 hour. The reaction solution was filtered using a G4 fritted funnel and poured into the prepared membrane mold. After drying, the cross-linked poly(piperidinium diphenyl sulfide) anion exchange membrane PPSP35-Co50 was obtained.

[0038] Example 4 Step A. Preparation of polyphenylene sulfide-piperidine polymer with a sulfide flexible spacer: 3.7254 g (20 mmol) of phenylene sulfide, 2.38 g (21 mmol) of 1-methyl-4-piperidone, and 10 mL of dichloromethane were added to a 100 mL three-necked flask. After stirring in an ice bath for 20 min, 6 mL (67 mmol) of trifluoromethanesulfonic acid was slowly added. The reaction was continued in an ice bath for 30 min, after which the ice bath was removed and the reaction continued at room temperature for 12 h. The solution became highly viscous and was diluted with dichloromethane. The solution then settled in an alkaline solution to yield a white, thin solid. This solid was isolated, washed several times with deionized water until neutral, and dried at 60°C for 24 h to yield polyphenylene sulfide-piperidine polymer (PPSP). Step B. Preparation of 6-bromohexyl-1-methylpiperidinium bromide: 49.79 g of 1,6-dibromohexane (200 mmol) and 30 mL of ethyl acetate were added to a 100 mL three-necked flask equipped with a stirrer and N2 inlet and outlet, and stirred thoroughly at 60 ° C for 30 min. Then, 4.09 g (40 mmol) of 1-methylpiperidine and 70 mL of ethyl acetate were added dropwise to the mixture through a constant pressure funnel, and the mixture was further stirred for 12 hours. After the reaction was completed, the product was filtered and washed several times with ethyl acetate. It was then dried in vacuo at 60 ° C for 12 hours to obtain 6-bromohexyl-1-methylpiperidinium bromide (Br-6-Pip) as a white solid powder; Step C. Preparation of a cross-linked poly(piperidinium diphenyl sulfide) anion exchange membrane material: 0.60 g (2.1320 mmol) of PPSP and 15 mL of N-methylpyrrolidone were added to a 100 mL three-necked flask equipped with a nitrogen inlet and outlet. The mixture was stirred at 80°C for approximately 30 minutes. After the polymer was completely dissolved, 0.28 g of K2CO3 (2.0254 mmol) and 0.2561 g of Br-6-Pip (0.7462 mmol) were added. Heating was stopped after 3 days. After cooling to room temperature, 0.16 g of 1,6-dibromohexane (0.6396 mmol) was added and stirring continued for 1 hour. The reaction solution was filtered using a G4 fritted funnel and poured into the prepared membrane mold. After drying, the cross-linked poly(piperidinium diphenyl sulfide) anion exchange membrane PPSP35-Co50 was obtained.

[0039] The basic properties of the anion exchange membranes grafted with flexible side chain cationic groups containing thioether flexible spacers obtained in Examples 1-4 are shown in Table 1.

[0040] Table 1

[0041] In the table: the test temperatures of WU and SR are 20℃ and 80℃, AEMs refers to anion exchange membranes; IEC is the ion exchange capacity, which is measured by titration; Theo. a is the theoretical value of ion exchange capacity; Expt. b is the value measured on the ion exchange capacity; σ is the ionic conductivity, measured in pure water by an electrochemical workstation; WU is the mass change of the membrane before and after water absorption; SR is the change in membrane length before and after water absorption.

[0042] As shown in Table 1, the IEC values ​​of the PPSP35-Cox membrane prepared according to the present invention, measured by molar titration, range from 2.64 to 3.27 mmol / g, close to the theoretical values. A higher degree of crosslinking and a higher content of piperidinium cationic groups per unit mass result in a higher IEC value. Both the water absorption and swelling ratio of the membrane decrease with increasing crosslinking: at 80°C, the water absorption of the membrane decreases from 40.0% to 27.0%, and the swelling ratio decreases from 15.8% to 11.8%.

[0043] At the same time, the IEC value of PPSP35-Co60 in Table 1 has increased to 3.10 mmol g -1 At this point, the IEC value's regulatory effect on membrane performance tends to be saturated. At the same time, an excessively high degree of cross-linking excessively inhibits the membrane's water absorption capacity, greatly weakening the freedom of movement of hydrophilic piperidine ions, resulting in a slight decrease in the membrane's ionic conductivity.

[0044] The ionic conductivity of the membrane is one of the key factors in evaluating the performance of the membrane. The ionic conductivity of the PPSP35-Cox membrane was tested in the temperature range of 20 ℃ to 80 ℃ by the four-electrode method. Figure 5 As shown in the figure, the ionic conductivity of the membrane increases with the increase of temperature. For example, when the temperature increases from 30 ℃ to 80 ℃, the hydroxide ion conductivity of PPSP35-Co50 increases from 68.9 mS cm -1 Increased to 160.9 mS cm -1 This is because rising temperature, on the one hand, provides molecules with thermal energy, accelerating their movement, and on the other hand, expands the volume of the polymer membrane, increasing the space for molecular movement. At the same time, when the degree of polymer cross-linking increases, the ionic conductivity of the membrane also increases. This is because the introduction of the cross-linking structure increases the IEC value of the membrane while also suppressing its swelling.

[0045] When the cross-linked poly (piperidinium diphenyl sulfide) anion exchange membrane prepared in Example 3 is assembled in a water electrolyzer, since strong alkaline hydroxide ions are generated during the electrolysis process, alkali resistance stability is one of the key performance indicators of the anion exchange membrane. This test takes the PPSP35-Co50 membrane as an example and immerses it in 2 mol L -1 The membrane was immersed in a NaOH solution at 80℃ for 1200 h. The membrane's alkali resistance stability was evaluated by measuring the membrane's ionic conductivity. Figure 6 As shown in the figure, the ionic conductivity decreases with time, and its retention rate is 91.7% after 1200 h.

[0046] Figure 7 The voltage durability curve of a water electrolyzer equipped with a cross-linked poly(piperidinium diphenyl sulfide) anion exchange membrane is shown at 30 °C and 500 mA cm -2 A steady-state polarization curve was recorded for 1200 hours at a constant current density. Throughout the test, the voltage fluctuated between 1.68 V and 1.72 V, with a voltage retention rate of 97.62%. This overall test demonstrates the feasibility of this membrane in alkaline conditions.

[0047] The grafted flexible side chain cationic group anion exchange membrane material provided in the background technology contains a sulfide flexible spacer group. When the IEC value of the anion exchange membrane reaches 1.96 mmol g -1 When the WU% at 80℃ is 57.5%, SR is 20.6%, OH - The ionic conductivity reaches 117.1 mS cm -1 The conductivity retention rate of the membrane sample after 520 h of treatment in 2M NaOH solution was as high as 89.1%. In Example 3 of the present invention, when the IEC value of the anion exchange membrane reached 3.10 mmol g -1 When WU is 29.0% at 80℃, SR is 12.4%, and OH is - The ionic conductivity reaches 160.9 mS cm -1 After 1200 hours of treatment in 2M NaOH, the conductivity retention of the membrane sample reached 91.7%. This indicates that the cross-linked poly(piperidinium diphenyl sulfide) anion exchange membrane prepared in the present invention has a significantly lower swelling rate than the anion exchange membrane materials with grafted flexible side chain cationic groups and containing sulfide flexible spacers, as described in the prior art.

[0048] While various embodiments of the present invention have been described above, the foregoing description is intended to be illustrative and non-exhaustive, and is not intended to be limiting of the disclosed embodiments. Numerous modifications and variations will be apparent to those skilled in the art without departing from the scope and technical principles of the described embodiments, and such modifications and variations should be considered within the scope of the present invention.

Claims

1. A cross-linked poly (piperidinium diphenyl sulfide) anion exchange membrane material, characterized in that: The molecular structure of the anion exchange membrane material is shown in Formula 1: Formula 1 In formula 1, the content of the functionalized structural unit is 0.35, the content of the cross-linked structural unit is x=0.30~0.60, the content of the non-functionalized structural unit is 0.65-x=0.05~0.35; and the degree of polymerization n=300~1000.

2. A method for synthesizing the cross-linked poly (piperidinium diphenyl sulfide) anion exchange membrane material according to claim 1, characterized in that: Includes the following steps Step A. Preparation of polyphenylene sulfide-piperidine polymer with sulfide flexible spacer: using phenylene sulfide and 1-methyl-4-piperidone as raw materials, carrying out Friedel-Crafts polycondensation reaction in an organic solvent with trifluoromethanesulfonic acid as catalyst to obtain polyphenylene sulfide-piperidine polymer with sulfide flexible spacer; Step B. Preparation of 6-bromohexyl-1-methylpiperidinium bromide: Under N2 conditions, 1,6-dibromohexane is used as a raw material, and a mixture of 1-methylpiperidine and an organic solvent is added dropwise in an organic solvent environment. After post-treatment, 6-bromohexyl-1-methylpiperidinium bromide is obtained; Step C. Preparation of cross-linked poly (piperidine diphenyl sulfide) anion exchange membrane material: The sulfide flexible spacer poly (piperidine diphenyl sulfide) polymer prepared in step A and N-methylpyrrolidone are heated and stirred in an inert gas atmosphere, K2CO3 is added first, and then the 6-bromohexyl-1-methylpiperidinium bromide prepared in step B is added. After keeping the temperature for a period of time, 1,6-dibromohexane is added to carry out a Menshutkin reaction. After the reaction is completed, the reaction solution is filtered and poured into a membrane mold to obtain a cross-linked poly (piperidine diphenyl sulfide) anion exchange membrane.

3. The method for synthesizing the cross-linked poly (piperidinium diphenyl sulfide) anion exchange membrane material according to claim 2, wherein: The specific steps are as follows: Step A. Preparation of a sulfide flexible spacer polyphenylene sulfide-piperidine polymer: Phenylene sulfide, 1-methyl-4-piperidone, and dichloromethane are added to a three-necked flask and stirred in an ice bath. Trifluoromethanesulfonic acid is added thereto, and the reaction is continued in an ice bath. The ice bath is then removed and the reaction is continued at room temperature. The mixture is diluted with dichloromethane and precipitated in an alkaline solution to obtain a white, thin solid. The solid is separated and washed several times with deionized water until neutral, and dried to obtain a sulfide flexible spacer polyphenylene sulfide-piperidine polymer. Step B. Preparation of 6-bromohexyl-1-methylpiperidinium bromide: 1,6-dibromohexane and ethyl acetate were added to a three-necked flask equipped with a stirrer and a N2 inlet and outlet. After heating and stirring thoroughly, a mixture of 1-methylpiperidine and ethyl acetate was added dropwise to the three-necked flask through a constant pressure funnel, and the mixture was further stirred. After the reaction was completed, the product was filtered and washed several times with ethyl acetate, and then dried to obtain a white solid powder containing 6-bromohexyl-1-methylpiperidinium bromide; Step C. Preparation of cross-linked poly (piperidine diphenyl sulfide) anion exchange membrane material: add the sulfide flexible spacer poly (piperidine diphenyl sulfide) polymer prepared in step A and N-methylpyrrolidone to a flask with a nitrogen inlet and outlet, heat and stir, add K2CO3 after the polymer is dissolved, and then add the 6-bromohexyl-1-methylpiperidinium bromide prepared in step B. After keeping warm for a period of time, cool to room temperature, add 1,6-dibromohexane, continue stirring, filter the reaction solution, pour it into a membrane mold, and dry it to obtain a cross-linked poly (piperidine diphenyl sulfide) anion exchange membrane.

4. The method for synthesizing the cross-linked poly (piperidinium diphenyl sulfide) anion exchange membrane material according to claim 3, wherein: In the step A, the molar ratio of phenylene sulfide to 1-methyl-4-piperidone is 1:1 to 1:1.

3.

5. The method for synthesizing a cross-linked poly (piperidinium diphenyl sulfide) anion exchange membrane material according to claim 3, characterized in that: In the step A, the molar ratio of trifluoromethanesulfonic acid to 1-methyl-4-piperidone is 3:1 to 4:

1.

6. The method for synthesizing a cross-linked poly (piperidinium diphenyl sulfide) anion exchange membrane material according to claim 3, characterized in that: In the step B, the amount of 1,6-dibromohexane used is 3 to 5 times that of 1-methylpiperidine, the reaction temperature is 40 to 60° C., and the reaction time is 6 to 12 hours.

7. The method for synthesizing a cross-linked poly (piperidinium diphenyl sulfide) anion exchange membrane material according to claim 3, characterized in that: In the step C, the amount of N-methylpyrrolidone used is 40 to 80 times the mass of the sulfide flexible spacer polyphenylene sulfide piperidine polymer.

8. The method for synthesizing a cross-linked poly (piperidinium diphenyl sulfide) anion exchange membrane material according to claim 3, characterized in that: In the step C, the molar ratio of K2CO3 to the sum of 6-bromohexyl-1-methylpiperidinium bromide and 2 times the amount of 1,6-dibromohexane is 1:

1.

9. The method for synthesizing a cross-linked poly (piperidinium diphenyl sulfide) anion exchange membrane material according to claim 3, characterized in that: In step C, the molar ratio of 1,6-dibromohexane to the sulfide flexible spacer polyphenylene sulfide piperidine polymer is 0.15 to 0.30:1; the reaction conditions for adding 1,6-dibromohexane are: reaction temperature of 20 to 30° C., and reaction time of 0.5 to 2 h.

10. A use of the cross-linked poly (piperidinium diphenyl sulfide) anion exchange membrane material according to claim 1, characterized in that: The cross-linked poly (piperidinium diphenyl sulfide) anion exchange membrane material can be used as a key component in an alkaline water electrolysis cell.

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