阅读说明：本技术 一种新型多哌嗪鎓官能化阴离子交换膜及其制备方法 (Novel polypiperazinium functionalized anion exchange membrane and preparation method thereof ) 是由 焉晓明 肖燕 贺高红 潘昱 姜晓滨 吴雪梅 于 2020-11-24 设计创作，主要内容包括：本发明属于阴离子交换膜技术领域,旨在提高阴离子交换膜的离子传递性能和尺寸稳定性,提供了一种新型多哌嗪鎓官能化阴离子交换膜及其制备方法,本发明的制备方法合成了具有良好尺寸稳定性和机械性能的含有多哌嗪鎓官能化聚合物,再对聚合物进行季胺化得到多哌嗪鎓官能化聚合物,并制膜。所制备的膜具有较好的尺寸稳定性和较好的离子传导率,可应用于中性、和全钒液流电池中。(The invention belongs to the technical field of anion exchange membranes, aims to improve the ion transfer performance and the dimensional stability of an anion exchange membrane, and provides a novel polypiperazinium functionalized anion exchange membrane and a preparation method thereof. The prepared membrane has good dimensional stability and good ionic conductivity, and can be applied to neutral and all-vanadium flow batteries.)

1. A novel polypiperazinium-functionalized anion exchange membrane characterized in that the novel polypiperazinium-functionalized anion exchange membrane has the following structure:

wherein: x is 0.01-0.99; n is a positive integer of 0-10; r is H or piperazinium.

2. A preparation method of a novel polypiperazinium functionalized anion exchange membrane is characterized by comprising the following steps:

(1) synthesis of polypiperazinium functionalized 4,4' -biphenols: dissolving 4,4' -biphenol in ethanol, and adding an aqueous solution of N-alkyl piperazine and formaldehyde after the temperature of a reaction solution is reduced to 0 ℃ under an ice bath condition; stirring the solution at 10-40 ℃ for 12-48 hours; the viscous solid was collected by rotary evaporation and washed several times with dichloromethane by rotary evaporation; recrystallizing with diethyl ether, filtering, and vacuum drying at 30 deg.C for 12 hr to obtain off-white powder;

the content of the 4,4' -biphenol: n-alkylpiperazine: the molar ratio of formaldehyde is 1: 1-4: 4-8;

the structure of the polypiperazinium functionalized 4,4' -biphenol is as follows:

wherein R is H or piperazinium;

(2) synthesis of polypiperazinium functionalized polymers: under the protection of inert gas, dissolving polypiperazinium functionalized 4,4 '-biphenol, decafluorobiphenyl and 4,4' -biphenol in a solvent A, adding potassium carbonate, refluxing at 60-90 ℃ to remove water, and then keeping the temperature of 80-90 ℃ for constant reaction for 24-48 h; pouring the reaction solution into a precipitator B, filtering, washing and drying to obtain a polypiperazinium functionalized polymer;

the polypiperazinium functionalized 4,4' -biphenol: decafluorobiphenyl: 4,4' -biphenol: the molar ratio of potassium carbonate is 0.01-0.99: 1: 0.99-0.01: 1-10;

the total mass w/v of the polypiperazinium functionalized 4,4 '-biphenol, decafluorobiphenyl and 4,4' -biphenol in the solvent A is 15-40%, kg/L;

the solvent A is N, N-dimethylacetamide, N-dimethylformamide or N-methylpyrrolidone;

the precipitant B is ice water, methanol or ethanol;

(3) quaternization of polypiperazinium-functionalized polymers: adding 1 equivalent of the polypiperazinium functionalized polymer obtained in the step (2) into DMAC (dimethylacetamide), stirring to form a white emulsion, adding 4-8 equivalents of methyl iodide, and reacting at 30-50 ℃ for 24-48 h; slowly pouring the mixed solution into the stirred solution of the solvent C to precipitate a target product, washing the target product for a plurality of times by using the solvent C, performing suction filtration, and drying the target product in a constant-temperature drying oven;

the solvent C is ethyl acetate, acetone or diethyl ether;

(4) preparation of polypiperazinium functionalized anion exchange membranes: dissolving the quaternized polypiperazinium functionalized polymer synthesized in the step (3) in a casting film agent to form a casting film solution with the concentration of 20g/L-50 g/L; dripping the casting solution on a casting glass plate, and fully drying in an oven to prepare a polypiperazinium functionalized anion exchange membrane with the thickness of 30-70 m; and gently peeling the polypiperazinium-functionalized anion-exchange membrane from the cast glass plate; soaking the polypiperazinium functionalized anion exchange membrane in deionized water for 12h at room temperature to remove impurities; then, soaking the polypiperazinium functionalized anion-exchange membrane in alkali for 12 hours to perform sufficient ion exchange; and soaking the polypiperazinium functionalized anion-exchange membrane in deionized water to remove redundant alkali.

3. The process according to claim 2, wherein the N-alkylpiperazine is N-methylpiperazine, N-ethylpiperazine, N-propylpiperazine, N-butylpiperazine, N-pentylpiperazine, N-hexylpiperazine, N-heptylpiperazine, N-octylpiperazine, N-nonylpiperazine or N-decylpiperazine.

4. The method according to claim 2 or 3, wherein the drying temperature for the film formed by the casting method is 50 to 80 ℃ for 24 to 48 hours.

5. The method according to claim 4, wherein in the step (1), the reaction temperature is 30 ℃ and the reaction time is 24 hours.

6. The method according to claim 2, 3 or 5, wherein the reaction temperature in the step (2) is 85 ℃.

7. The method according to claim 6, wherein the reaction temperature in the step (3) is 45 ℃.

Technical Field

The invention belongs to the technical field of anion exchange membranes, and relates to a novel multi-piperazinium functionalized anion exchange membrane and a preparation method thereof.

Background

The scientific application demand of renewable energy sources is rapidly growing, and it is crucial to develop a large energy storage system with low cost and high efficiency to eliminate the intermittency of renewable energy sources. Redox Flow Batteries (RFBs) have attracted considerable attention in recent years as one of the most promising large energy storage systems. The membrane is one of the key components of the RFB, which not only affects the overall cycle performance, but also determines the economic viability of the system. The membrane separates the positive and negative half-cells and prevents cross-mixing of the bipolar active materials while providing the desired ionic conductivity. The ideal membrane should have good ion exchange capacity; high ionic conductivity, low water absorption, swelling ratio, zone resistance and permeability of active substances; good chemical stability and low cost. At present, polymers such as polysulfone, polybenzimidazole, polyphenyl ether and the like are commonly used as main chains of membrane materials, but partial polymers have the problems of low ionic conductivity, high water absorption swelling and poor dimensional stability. Therefore, finding a polymer with good dimensional stability and high conductivity is one of the hot spots of current interest.

Disclosure of Invention

The invention aims to improve the ion transfer performance and the dimensional stability of an anion exchange membrane, and provides a preparation method of a novel polypiperazinium functionalized anion exchange membrane, which comprises the following steps: the polypiperazinium functionalized polymer with good dimensional stability and mechanical properties is synthesized, and then the polymer is quaternized to obtain the polypiperazinium functionalized polymer, and a membrane is prepared. The prepared membrane has good dimensional stability and good ionic conductivity, and can be applied to neutral and all-vanadium flow batteries.

The technical scheme of the invention is as follows:

a novel polypiperazinium functionalized anion exchange membrane having the following structure:

wherein: x is 0.01-0.99; n is a positive integer of 0-10; r is H or piperazinium.

A preparation method of a novel polypiperazinium functionalized anion exchange membrane comprises the following steps:

(1) synthesis of polypiperazinium functionalized 4,4' -biphenols: dissolving 4,4' -biphenol in ethanol, and adding an aqueous solution of N-alkyl piperazine and formaldehyde after the temperature of a reaction solution is reduced to 0 ℃ under an ice bath condition; stirring the solution at 10-40 ℃ for 12-48 hours; the viscous solid was collected by rotary evaporation and washed several times with dichloromethane by rotary evaporation; recrystallizing with diethyl ether, filtering, and vacuum drying at 30 deg.C for 12 hr to obtain off-white powder;

the content of the 4,4' -biphenol: n-alkylpiperazine: the molar ratio of formaldehyde is 1: 1-4: 4-8;

the structure of the polypiperazinium functionalized 4,4' -biphenol is as follows:

wherein R is H or piperazinium.

The N-alkyl piperazine is N-methyl piperazine, N-ethyl piperazine, N-propyl piperazine, N-butyl piperazine, N-pentyl piperazine, N-hexyl piperazine, N-heptyl piperazine, N-octyl piperazine, N-nonyl piperazine or N-decyl piperazine;

(2) synthesis of polypiperazinium functionalized polymers: under the protection of inert gas, dissolving polypiperazinium functionalized 4,4 '-biphenol, decafluorobiphenyl and 4,4' -biphenol in a solvent A, adding potassium carbonate, refluxing at 60-90 ℃ to remove water, and then keeping the temperature of 80-90 ℃ for constant reaction for 24-48 h; pouring the reaction solution into a precipitator B, filtering, washing and drying to obtain a polypiperazinium functionalized polymer;

the polypiperazinium functionalized 4,4' -biphenol: decafluorobiphenyl: 4,4' -biphenol: the molar ratio of potassium carbonate is 0.01-0.99: 1: 0.99-0.01: 1-10;

the total mass w/v of the polypiperazinium functionalized 4,4 '-biphenol, decafluorobiphenyl and 4,4' -biphenol in the solvent A is 15-40%, kg/L;

the solvent A is N, N-dimethylacetamide, N-dimethylformamide or N-methylpyrrolidone;

the precipitant B is ice water, methanol or ethanol;

(3) quaternization of polypiperazinium-functionalized polymers: adding 1 equivalent of the polypiperazinium functionalized polymer obtained in the step (2) into DMAC (dimethylacetamide), stirring to form a white emulsion, adding 4-8 equivalents of methyl iodide, and reacting at 30-50 ℃ for 24-48 h; slowly pouring the mixed solution into the stirred solution of the solvent C to precipitate a target product, washing the target product for a plurality of times by using the solvent C, performing suction filtration, and drying the target product in a constant-temperature drying oven;

the solvent C is ethyl acetate, acetone or diethyl ether;

(4) preparation of polypiperazinium functionalized anion exchange membranes: dissolving the quaternized polypiperazinium functionalized polymer synthesized in the step (3) in a casting film agent to form a casting film solution with the concentration of 20g/L-50 g/L; dripping the casting solution on a casting glass plate, and fully drying in an oven to prepare a polypiperazinium functionalized anion exchange membrane with the thickness of 30-70 m; and gently peeling the polypiperazinium-functionalized anion-exchange membrane from the cast glass plate; soaking the polypiperazinium functionalized anion exchange membrane in deionized water for 12h at room temperature to remove impurities; then, soaking the polypiperazinium functionalized anion-exchange membrane in alkali for 12 hours to perform sufficient ion exchange; and soaking the polypiperazinium functionalized anion-exchange membrane in deionized water to remove redundant alkali.

The drying temperature of the film formed by the casting method is 50-80 ℃, and the time is 24-48 hours.

The invention has the advantages that a multi-piperazinium functionalized anion exchange membrane applied to neutral and all-vanadium flow batteries is designed and prepared through condensation and quaternization reactions. The introduction of piperazinium can effectively improve the ion conduction capability and vanadium resistance of the membrane, so that the membrane has higher ion conductivity and ion selectivity. The polypiperazinium functionalized anion-exchange membrane prepared by the method can show excellent battery performance, the energy efficiency of the polypiperazinium functionalized anion-exchange membrane is far superior to that of common sulfonic acid membranes such as Nafion212 and sulfonated polyether ether ketone, the polypiperazinium functionalized anion-exchange membrane has good stability, the efficiency of the battery is not obviously attenuated after the battery is circulated for 200 circles, and the mass loss after the battery is soaked in a high-valence vanadium ion solution for 14 days is far lower than that of the sulfonated polyether ether ketone membrane.

Detailed Description

The present invention will be described in further detail with reference to examples, but the embodiments of the present invention are not limited thereto.

Example 1

Synthesis of polypiperazinium functionalized 4,4' -biphenols: in a 250mL round bottom flask, 3.7242g (20mmol) of 4,4' -biphenol was dissolved in 40mL ethanol, after 1 hour, the reaction vessel was placed in an ice bath, the reaction solution was cooled to 0 ℃ and 4.0471g (40mmol) of N-methylpiperazine and 5.9mL of an aqueous solution of formaldehyde were added. The solution was stirred at 25 ℃ for 24 hours. The viscous solid was collected by rotary evaporation and washed several times with dichloromethane by rotary evaporation. Recrystallization from ether, filtration and drying under vacuum at 30 ℃ for 12 hours gave an off-white powder.

The structure of the resulting polypiperazinium-functionalized 4,4' -biphenol is as follows (R is H; n ═ 0):

synthesis of polypiperazinium functionalized polymers: 1.6424g (4mmol) of polypiperazinium-functionalized 4,4 '-biphenol, 3.3411g (10mmol) of decafluorobiphenyl and 1.1173g (6mmol) of 4,4' -biphenol are dissolved in DMAC under inert gas protection, 2.0732g (15mmol) of potassium carbonate are added, reflux is carried out at 80 ℃ for 6h to remove water, and then the temperature is kept constant at 85 ℃ for reaction for 48 h; pouring the reaction solution into deionized water for precipitation, filtering, alternately washing for several times by using the deionized water and ethanol, and drying to obtain a polypiperazinium functionalized polymer;

quaternization of polypiperazinium-functionalized polymers: 2.8384g (5mmol) of the reaction product polymer obtained in the last step is taken and added into DMAC, white emulsion is formed by stirring, 1.1355g (8mmol) of methyl iodide is respectively added, and the reaction time is 48h at 45 ℃; slowly pouring the mixed solution into a stirred ether solution to separate out a target product, washing the target product for a plurality of times by using ether, carrying out suction filtration, and drying the target product in a constant-temperature drying oven at the temperature of 30 ℃;

preparation of polypiperazinium functionalized anion exchange membranes: dissolving the polypiperazinium functionalized polymer synthesized in the last step into a film casting agent DMAC to form a film casting solution with the concentration of 28 g/L; dropwise adding the casting solution onto a casting glass plate, and fully drying in an oven to prepare the polypiperazinium functionalized anion exchange membrane; and gently peeling the polypiperazinium-functionalized anion-exchange membrane from the cast glass plate; soaking the polypiperazinium functionalized anion exchange membrane in deionized water for 12h at room temperature to remove impurities; then, soaking the polypiperazinium functionalized anion-exchange membrane in alkali for 12 hours to perform sufficient ion exchange; and soaking the polypiperazinium functionalized anion-exchange membrane in deionized water to remove redundant alkali.

The anion-exchange membrane obtained in this example had the following structure (R is H; n is 0):

tests show that the ion conductivity of the multi-branched polyaryletherketone anion-exchange membrane prepared in the embodiment at 25 ℃ is 16mS cm^-1The water absorption rate was 9% and the swelling degree was 5.6%. In a neutral flow battery, 40mA cm^-2When the electric density is high, the CE is 98 percent and the EE is 73 percent; in all vanadium flow batteries, 80mA cm^-2When the electric density is high, the CE is 96 percent and the EE is 82 percent;

example 2

Synthesis of polypiperazinium functionalized 4,4' -biphenols: same as example 1

Synthesis of polypiperazinium functionalized polymers: 2.8742g (7mmol) of polypiperazinium-functionalized 4,4 '-biphenol, 3.3411g (10mmol) of decafluorobiphenyl and 0.5586g (3mmol) of 4,4' -biphenol are dissolved in DMAC under inert gas protection, 2.0732g (15mmol) of potassium carbonate are added, reflux is carried out at 80 ℃ for 6h to remove water, and then the temperature is kept constant at 85 ℃ for reaction for 48 h; pouring the reaction solution into deionized water for precipitation, filtering, alternately washing for several times by using the deionized water and ethanol, and drying to obtain a polypiperazinium functionalized polymer;

quaternization of polypiperazinium-functionalized polymers: 3.1809g (5mmol) of the reaction product polymer obtained in the last step is taken and added into DMAC, white emulsion is formed by stirring, 1.9872g (14mmol) of methyl iodide is respectively added, and the reaction time is 48h at 45 ℃; slowly pouring the mixed solution into a stirred ether solution to separate out a target product, washing the target product for a plurality of times by using ether, carrying out suction filtration, and drying the target product in a constant-temperature drying oven at the temperature of 30 ℃;

preparation of polypiperazinium functionalized anion exchange membranes: dissolving the polypiperazinium functionalized polymer synthesized in the last step into a film casting agent DMAC to form a film casting solution with the concentration of 28 g/L; dropwise adding the casting solution onto a casting glass plate, and fully drying in an oven to prepare the polypiperazinium functionalized anion exchange membrane; and gently peeling the polypiperazinium-functionalized anion-exchange membrane from the cast glass plate; soaking the polypiperazinium functionalized anion exchange membrane in deionized water for 12h at room temperature to remove impurities; then, soaking the polypiperazinium functionalized anion-exchange membrane in alkali for 12 hours to perform sufficient ion exchange; and soaking the polypiperazinium functionalized anion-exchange membrane in deionized water to remove redundant alkali.

The anion-exchange membrane obtained in this example had the following structure (R is H; n is 0):

tests show that the ion conductivity of the multi-branched polyaryletherketone anion-exchange membrane prepared in the embodiment at 25 ℃ is 27mS cm^-1The water absorption was 15.2% and the swelling degree was 9.8%. In a neutral flow battery, 40mA cm^-2When the electric density is high, the CE is 98 percent and the EE is 75 percent; in all vanadium flow batteries, 80mA cm^-2When the electric density is high, the CE is 96 percent and the EE is 85 percent;

example 3

Synthesis of polypiperazinium functionalized 4,4' -biphenols: same as example 1

Synthesis of polypiperazinium functionalized polymers: 3.6954g (9mmol) of polypiperazinium-functionalized 4,4 '-biphenol, 3.3411g (10mmol) of decafluorobiphenyl and 0.1862g (1mmol) of 4,4' -biphenol are dissolved in DMAC under inert gas protection, 2.0732g (15mmol) of potassium carbonate are added, reflux is carried out at 80 ℃ for 6h to remove water, and then the temperature is kept constant at 85 ℃ for reaction for 48 h; pouring the reaction solution into deionized water for precipitation, filtering, alternately washing for several times by using the deionized water and ethanol, and drying to obtain a polypiperazinium functionalized polymer;

quaternization of polypiperazinium-functionalized polymers: 3.4093g (5mmol) of the reaction product polymer obtained in the last step is taken and added into DMAC, white emulsion is formed by stirring, 2.5549g (18mmol) of methyl iodide is respectively added, and the reaction time is 48h at 45 ℃; slowly pouring the mixed solution into a stirred ether solution to separate out a target product, washing the target product for a plurality of times by using ether, carrying out suction filtration, and drying the target product in a constant-temperature drying oven at the temperature of 30 ℃;

preparation of polypiperazinium functionalized anion exchange membranes: dissolving the polypiperazinium functionalized polymer synthesized in the last step into a film casting agent DMAC to form a film casting solution with the concentration of 28 g/L; dropwise adding the casting solution onto a casting glass plate, and fully drying in an oven to prepare the polypiperazinium functionalized anion exchange membrane; and gently peeling the polypiperazinium-functionalized anion-exchange membrane from the cast glass plate; soaking the polypiperazinium functionalized anion exchange membrane in deionized water for 12h at room temperature to remove impurities; then, soaking the polypiperazinium functionalized anion-exchange membrane in alkali for 12 hours to perform sufficient ion exchange; and soaking the polypiperazinium functionalized anion-exchange membrane in deionized water to remove redundant alkali.

The anion-exchange membrane obtained in this example had the following structure (R is H; n is 0):

tests show that the ion conductivity of the multi-branched polyaryletherketone anion-exchange membrane prepared in the embodiment at 25 ℃ is 40mS cm^-1The water absorption was 22% and the swelling degree was 14%. In a neutral flow battery, 40mA cm^-2When the electricity is dense, the CE is 99 percent and the EE is 78 percent; in all vanadium flow batteries, 80mA cm^-2When the electric density is high, the CE is 98%,EE accounts for 89 percent; the film showed relatively good performance.