CN111393696B

CN111393696B - Guanidine-based functionalized anion exchange membrane with cross-linked network structure and preparation method thereof

Info

Publication number: CN111393696B
Application number: CN202010269832.9A
Authority: CN
Inventors: 方军; 俞生生; 魏东伟
Original assignee: Fuzhou University
Current assignee: Fuzhou University
Priority date: 2020-04-08
Filing date: 2020-04-08
Publication date: 2022-04-12
Anticipated expiration: 2040-04-08
Also published as: CN111393696A

Abstract

The invention discloses a guanidino functionalized anion exchange membrane with a cross-linked network structure and a preparation method thereof, belongs to the technical field of membranes, and particularly relates to an ion exchange membrane and a preparation method thereof. The invention takes a polymer with a benzene ring structure on a main chain as a raw material, introduces a guanidine functional group into a side chain of the polymer, and forms a cross-linked network structure. The anion membrane prepared by the invention has higher ionic conductivity, good chemical stability and thermal stability, excellent dimensional stability and mechanical property.

Description

Guanidine-based functionalized anion exchange membrane with cross-linked network structure and preparation method thereof

Technical Field

The invention belongs to the technical field of membranes, and particularly relates to a guanidino functionalized anion exchange membrane and a preparation method thereof.

Background

A polymer anion exchange membrane is an alkaline electrolyte that contains basic active groups and has a permselective effect on anions, also known as an ion permselective membrane. Anion exchange membranes are generally composed of three parts: the main chain of the high molecular polymer, a positively charged active group connected to the main chain, and an anion which can freely move and is paired with the active group. The anion exchange membrane has wide application, is a key part in a separation and purification device and an electrochemical assembly, and plays a significant role in the fields of chlor-alkali industry, water treatment, heavy metal recovery, hydrometallurgy, energy storage and conversion and the like. In recent years, with the development of new chemical power sources, anion exchange membranes have been attracting more attention and studied as battery separators in liquid flow energy storage batteries, anion exchange membrane fuel cells, new supercapacitors and the like.

In an electrochemical device such as a fuel cell, an anion exchange membrane as a key material not only plays a role of isolating an oxidizing agent and a reducing agent but also has an ion conduction role. Therefore, the anion exchange membrane needs to have high ion selective permeability and electrical conductivity, and simultaneously, the anion exchange membrane also has good mechanical strength, flexibility, dimensional stability, and high thermal stability and chemical stability.

Currently, the developed anion exchange membranes generally have the problems of low ionic conductivity, poor alkali resistance and heat resistance, and the like, and membranes with high conductivity generally have high water content and ion exchange capacity. However, too high a water content leads to excessive swelling of the film, poor dimensional stability, and reduced mechanical properties and alkali resistance.

In a conventional anion exchange membrane, the active groups are generally quaternary ammonium salt groups or quaternary phosphonium salt groups. It is known that quaternary ammonium salts are chemically unstable and easily degraded in an alkaline environment. The alkali resistance of the quaternary phosphonium salt group is better than that of the quaternary ammonium salt group, but the quaternary phosphonium salt has poor heat resistance, difficult film formation and higher price, so the development and the application of the quaternary phosphonium salt type anion exchange membrane are also greatly limited. The invention introduces guanidine salt group as active group on the main chain of high molecular polymer, in the molecular structure of guanidine salt, positive charge is distributed on central carbon and 3 nitrogen atoms in a conjugated way, and the high delocalization of the charge ensures that guanidine salt ion has excellent thermal stability and chemical stability. In addition, 6 substituents are distributed on 3 nitrogen atoms of the guanidine salt, the structure of the substituents can have diversity, and the substituents can be electron withdrawing groups or electron pushing groups, and even can be substituent groups with large steric hindrance, so that the guanidine salt type anion exchange membrane can be designed possibly. For example, azide groups can be introduced into the main chain of the polyether sulfone, and then guanidine salt structures are introduced into the side chain of the polymer skeleton by utilizing the reaction between guanidine alkyne-containing monomers with different structures and the polyether sulfone, so as to prepare the polyether sulfone anion exchange membrane of side-chain guanidine salt. U.S. Journal of Polymer Science (Journal of Polymer Science, Part A: Polymer Chemistry, 2017, 55: 1313-1320) reports a polyethersulfone-modified guanidinium-type anion-exchange membrane having high ionic conductivity and good thermal stability. Life under alkaline conditionThe membrane is an important performance index of an anion exchange membrane, but the membrane is rapidly degraded after being soaked in 1mol/L NaOH solution at 60 ℃ for 72 hours, mainly because guanidine salt ions substituted by hydrogen atoms are attacked by hydroxide ions. Chinese patent CN 106784949A discloses preparation of anion exchange membrane (CGH-MA) with interpenetrating network by using chitosan biguanide salt as intermediate of cross-linking agent and glutaraldehyde as cross-linking agent_x%) The alkali resistance of the membrane is improved to a certain extent, but the integral performance of the membrane does not meet the requirement of a commercial membrane, and the membrane CGH-MA with optimal performance_4%The conductivity at 70 ℃ was 44 mS/cm, but the dimensional change rate was 54%. China's reports of the Polymer science (2016, 4, 436-441) reports a series of self-crosslinking quaternized polyether sulfone anion-exchange membranes, and the solvent resistance of the membranes is remarkably enhanced through crosslinking treatment, but the alkali resistance and the thermal stability of the membranes are still to be improved. The weight loss of the membrane is 3.8 percent after the membrane is treated with water at 100 ℃ for 24 hours, and the ionic conductivity loss is 21 percent after the membrane is treated with 4 mol/L NaOH solution at room temperature for 168 hours.

Disclosure of Invention

In order to overcome the problems of lower ion conductivity, poor alkali resistance and heat resistance, poor dimensional stability and the like of the anion exchange membrane in the prior art, the invention aims to provide a guanidino functionalized anion exchange membrane with a cross-linked network structure and a preparation method thereof. The anion membrane prepared by the invention has higher ionic conductivity, good chemical stability and thermal stability, excellent dimensional stability and mechanical property.

The invention takes commercialized polymers with a benzene ring structure in the main chain, such as polysulfone, polyphenyl ether, polyether sulfone, phenolphthalein polyether sulfone, polyether ketone, polyimide and the like as raw materials, and prepares the anion exchange membrane with a cross-linked network structure through the steps of boration, guanidine functionalization, coupling reaction and the like. The guanidine functional group introduced into the side chain has good anion conductivity and chemical stability, the alkali resistance of the membrane is further improved after a cross-linked network structure is formed through a coupling reaction, the dimensional stability and the mechanical property of the membrane are also obviously improved, and the highest tensile strength can reach 38.27 MPa.

The technical scheme of the invention is as follows:

a guanidino-functionalized anion-exchange membrane with a cross-linked network structure, which is a polymer with a large number of guanidino functional groups on side chains and forms a cross-linked network structure. Wherein, any one of polysulfone, polyphenylether, polyethersulfone, phenolphthalein polyethersulfone, polyetherketone and polyimide is taken as a main chain, the side chain is a polymer of halogenated tetramethyl benzylguanidine and dihydric phenol organic monomers, and the part of the main chain with phenyl is para-position and bonded with the side chain halogenated tetramethyl benzylguanidine through coupling reaction; the halogenated methyl of side chain halogenated tetramethyl benzyl guanidine and-OH on the dihydric phenol organic monomer are bonded through etherification reaction; after the halogenated tetramethyl benzyl guanidine is bonded on a high molecular main chain after the coupling reaction, and is soaked by a target anion solution, the tetramethyl benzyl guanidine compound on the polymer main chain contains target anions.

Wherein the target anion is specifically Cl^- 、Br^-、I^-、CO₃ ^2-、SO₃H^-、OH^-Any one of the above.

Further, the dihydric phenol organic monomer is specifically bisphenol AF or 2' 2-hydroxybiphenyl.

Further, halogenated tetramethyl benzyl guanidine, the structural formula is

。

Further, the halogenated tetramethyl benzyl guanidine is brominated tetramethyl benzyl guanidine, and has the following structure:

。

the preparation method of the guanidino functionalized anion exchange membrane with the cross-linked network structure comprises the following steps:

(1) boration of M and Q: dissolving M in a solvent, sequentially adding a boration reagent, a catalyst and 4,4' -di-tert-butyl bipyridyl, reacting at 60-100 ℃ for 10-48 h, pouring the reaction solution into a precipitator, filtering, washing and drying to respectively obtain borated M, and marking the borated M as B-x-M; carrying out the same boration treatment on the Q to obtain borated Q which is recorded as BQ; wherein M is any one high molecular polymer of polysulfone, polyphenyl ether, polyether sulfone, phenolphthalein polyether sulfone, polyether ketone and polyimide, and Q is dihydric phenol organic monomer, specifically bisphenol AF or 2' 2-hydroxy biphenyl;

(2) preparation of tetramethylbenzylguanidine bromide: putting tetramethylguanidine into a reactor, then dropwise adding benzyl chloride, stirring and reacting at room temperature for 18-48 h, and filtering the mixture with the molar ratio of the tetramethylguanidine to the benzyl chloride being 10: 1-10; dissolving the filtrate with 40-60 mL diethyl ether, sequentially washing with distilled water for 4-6 times, and adding anhydrous Na₂SO₄Drying; obtaining a brown oily product tetramethyl benzyl guanidine by evaporating the solvent; dissolving tetramethyl benzyl guanidine in solvent, adding brominating agent and initiator, boiling and refluxing at 60-85 deg.C under stirring for 6-12 h; precipitating in a precipitator, and drying to obtain tetramethyl benzyl guanidine bromide;

(3) polymer guanidino functionalization: mixing the B-x-M obtained in the step (1) with a catalyst and a solvent tetrahydrofuran, placing the mixture in a round-bottom flask, and injecting the K of the brominated tetramethyl benzylguanidine obtained in the step (2)₂CO₃Stirring the aqueous solution at the temperature of 60-85 ℃ for reaction for 8-24 h; after the reaction is finished, cooling, filtering, precipitating and drying are carried out, and a guanidino functional polymer is obtained and is marked as G_x-M；

(4) Preparation of guanidinated biphenol: taking the BQ obtained in the step (1), and referring to the step (3), preparing guanidinated diphenol, which is marked as GQ;

(5) preparation of guanidine functionalized polymers of crosslinked network structure: g obtained in the step (3)_xDissolving the-M and the GQ obtained in the step (4) in a proper amount of solvent, adding 1-2M sodium hydroxide or potassium carbonate, reacting for 4-8 h at the temperature of 100-160 ℃, and then heating to the temperature of 150-180 ℃ for further reaction for 18-36 h; after the reaction is finished, the guanidine functionalized polymer Q-G with the cross-linked net structure is obtained after precipitation, filtration and drying in water_x-M；

(6) Become intoMembrane and alkalization: dissolving the polymer obtained in the step (5) in a proper solvent, forming a film by adopting a phase inversion method, washing the film in deionized water, soaking the film in 1M NaOH aqueous solution at room temperature for 24-48h, and alkalifying the film to obtain Q-G_x-OH-M, washed with deionized water to neutral.

Further, the solvent in the step (1) is a reagent which can dissolve reactants and products, such as tetrahydrofuran, toluene, N-dimethylformamide, N-dimethylacetamide and the like; the boration reagent is pinacol diboron; the catalyst is (1, 5-cyclooctadiene) iridium chloride dimer [ IrCl (COD)]₂Or [1, 1-bis (diphenylphosphino) ferrocene]Palladium dichloride, dichloromethane complex or tetrakis (triphenylphosphine) palladium or palladium acetate or tris (dibenzylideneacetone) dipalladium; the precipitant is a solvent capable of precipitating the product, such as diethyl ether, ethanol or methanol.

Further, in the step (1), the molar ratio of the polymer M, the dihydric phenol organic monomer Q, the boration reagent, the catalyst and the 4,4' -di-tert-butyl bipyridyl is 250-400: 100-400:1:1, wherein x is the boration degree and is 40-80% of the molar ratio fraction;

further, in the step (2), the brominating agent is N-bromosuccinimide or hydrogen bromide or dimethyl sulfur bromide, and the initiator is azobisisobutyronitrile or benzoyl peroxide or dicumyl peroxide;

further, the molar ratio of the brominating agent to the initiator in the step (2) is 5-15: 1.

Further, in the step (3), the catalyst is [1, 1-bis (diphenylphosphino) ferrocene ] palladium dichloride or dichloromethane compound or tetrakis (triphenylphosphine) palladium or palladium acetate or tris (dibenzylideneacetone) dipalladium;

further, wherein the brominated tetramethyl benzyl guanidine, B-x-M, catalyst, K₂CO₃The molar ratio of (A) to (B) is 40-80:100:2-5: 300.

Further, the solvent in the step (5) is one or more of N, N-dimethylformamide, N-dimethylacetamide and toluene;

further, step (5) wherein G_xMoles of-M and GQThe ratio is 1:1-1: 15.

The invention has the following significant advantages over the prior art:

compared with the chloromethylation and oxalyl chloride methods of the traditional quaternary ammonium salt anion exchange membrane, the preparation method avoids using highly toxic and carcinogenic reagents, namely chloromethyl ether and the like, and is environment-friendly and mild in reaction conditions. The membrane prepared by the invention has the conductivity of 92 mS-cm at 80 DEG C^-1And the conductivity of the membrane soaked in 6 mol/L alkali liquor for 500 hours hardly changes.

Drawings

FIG. 1 scheme for the preparation of guanidino-functionalization of polymers in example 1.

FIG. 2 is a flow chart of the preparation of guanidinated biphenol according to example 1.

Detailed Description

The technical solution of the present invention is further illustrated by the following embodiments.

Example 1

Firstly, the preparation method of M and Q by boration comprises the following steps: a50 mL flask was charged with Tetrahydrofuran (THF) as a solvent, 2 g of polysulfone was dissolved in THF as a solvent, and bis (pinacolato) diboron (B) was added₂Pin₂) (76 mg), 1, 5-cyclooctadiene) IrCl dimer [ IrCl (COD)]₂(24 mg), 4,4' -di-tert-butylbipyridine (dtbpy) 27 mg, and finally a magnetic stirring bar was put into the flask, the flask was sealed, and the reaction was stirred for 18 hours under an oil bath at 60 ℃. After the reaction was completed, the reaction solution was diluted with THF (15 mL) as a solvent, then filtered through a short silica gel plug to remove the catalyst, the remaining filtrate was put into a rotary evaporator to evaporate the excess solvent and poured into methanol to precipitate the polymer, the process of dissolution and precipitation of the polymer was repeated again, and then the polymer was placed in a beaker and dried under vacuum at 60 ℃ for 10 hours. Borated polymer B-70-PSF (2.18 g) was finally obtained. The boration method of 4,4 '-biphenol comprises adding THF solvent into flask, dissolving 1.26 g of 4,4' -biphenol in the THF solvent, and adding B₂Pin₂（66 mg），[IrCl（COD]₂(18 mg), dtbpy (22 mg), most preferablyThen putting a magnetic stirring rod into the flask; the remaining operation steps were the same as for the boration of polysulfone to finally obtain 1.33 g of organic borated biphenol (B-D).

Second, preparation of tetramethylbenzylguanidine bromide: 3 mmol (0.617 g) of tetramethylbenzylguanidine was dissolved in 1, 2-dichloroethane, and the resulting solution was poured into a three-necked flask, and 0.533 g of brominating agent NBS and 0. 0.0493 g of initiator AIBN were further added. Boiling and refluxing the mixture for 12 hours under the conditions of heating to 80 ℃ and stirring, gradually changing the solution into red along with the reaction, and continuously reacting for 2 hours after the red color of the solution fades, thus stopping heating and stirring. Precipitated in anhydrous methanol or isopropanol, washed to remove impurities, and dried in an oven to obtain the final tetramethylbenzylguanidine bromide (1.06 g).

Third, the polymer guanidino functionalization: taking B-70-PSF (1.77 g) and [1,1' -bis (diphenylphosphino) ferrocene]Palladium dichloride dichloromethane complex (Pd (dppf) Cl₂ -CH₂ Cl₂) (48 mg), THF (15 mL) and a magnetic stir bar were placed in a two-necked 50 mL round bottom flask. Dissolving dried tetramethyl benzyl guanidine bromide (6.00 mmol) in K₂CO₃The aqueous solution was then added to the reaction via syringe, the reaction stirred at 75 ℃ for 12h, cooled and diluted with THF (15 mL) and filtered through a short plug of silica gel to remove the catalyst. The filtrate was concentrated using a rotary evaporator and poured into methanol to precipitate a polymer, and the dissolution and precipitation processes were repeated again. After drying at 80 ℃ under vacuum for 12h, the guanidine-functionalized polymer, gray fiber G, was obtained₇₀-PSF（3.82 g）。

Fourthly, preparing the guanidinated diphenol: taking B-D (1.04 g), Pd (dppf) Cl₂-CH₂Cl₂(48 mg), THF (15 mL) and a magnetic stir bar were placed in a two-necked 50 mL round bottom flask. Dissolving dried tetramethyl benzyl guanidine bromide (6.00 mmol) in K₂CO₃To the reaction was added via syringe, the reaction stirred at 75 ℃ for 12h, cooled and diluted with THF (15 mL) and filtered through a short plug of silica gel to remove the catalyst. Then washing with dichloromethane and ultrapure water, and finallyExcess solvent was evaporated using a rotary evaporator. The remaining non-volatile liquid was dried under vacuum at 80 ℃ for 12h (3.08G) to give the guanidine-functionalized organic G-D.

Fifth, preparation of guanidine functionalized polymers in cross-linked network structure: taking the prepared G₇₀PSF (1.23G), G-D (1.08G) and K₂CO₃(0.83 g) were mixed together and dissolved in a mixed solution of 10mL of N, N-dimethylacetamide (DMAc) and 5mL of toluene. Heating the mixed solution to 100 ℃ and refluxing for 4 hours, then heating the reaction system to 150 ℃ and continuing to react for 18 hours, dropwise adding the reaction liquid into hot water after the reaction is finished, and then filtering and drying to obtain a product D-G₇₀PSF (2.28 g), the product solvent was then dissolved in dimethyl sulfoxide, and the casting solution was cast onto a glass plate to form a film. After the solvent is evaporated and the primary film is formed, the film is placed in a vacuum drying oven for heat preservation for 12 hours at 50 ℃. Then soaking the anion exchange membrane in the order of water, alkali and water to ensure that all anions of the anion exchange membrane are OH^-Finally, the membrane is washed to be neutral by ultrapure water, and the polysulfone negative ion exchange membrane D-G with the cross-linked net structure is obtained₇₀-OH-PSF。

When the degree of side chain crosslinking of the polysulfone anion-exchange membrane with the crosslinked network structure is 20 percent, the water absorption rate at room temperature reaches 14 percent, and the conductivity at 25 ℃ is 38.5 mS cm^-1And when the temperature is increased to 80 ℃, the conductivity is as high as 92 mS cm^-1When the film is soaked in 4M NaOH aqueous solution for 500 h, the conductivity is hardly changed. Therefore, the net structure and the introduction of a large amount of guanidine functional groups can be seen, and the comprehensive performance of the membrane is greatly improved.

Example 2

Firstly, the preparation method of M and Q by boration comprises the following steps: adding tetrahydrofuran solvent into a 50 mL flask, dissolving 2.0 g of polysulfone in THF solvent, and adding B₂Pin₂（38 mg），[IrCl（COD）]₂(12 mg), 13.5 mg of 4,4' -di-tert-butylbipyridine (dtbpy), and finally a magnetic stir bar was placed in the flask; the flask was taken out of the glove box, the flask was sealed, and then the reaction was stirred for 24 hours under the condition of an oil bath at 80 ℃. After the reaction is finished, the reaction solution is dissolvedThe reagent THF (15 mL) was diluted, then filtered through a short plug of silica gel to remove the catalyst, the remaining filtrate was put into a rotary evaporator to evaporate the excess solvent, the remaining solution was poured into methanol to precipitate the polymer, the dissolution and precipitation processes were repeated again, and then the polymer was placed in a beaker and dried under vacuum at 80 ℃ for 10 hours to finally obtain a borated polymer B-35-PSF (2.13 g). The boration method of 4,4 '-biphenol comprises adding solvent tetrahydrofuran into flask, dissolving 4,4' -biphenol 1.26 g in solvent, and adding B₂Pin₂（66 mg），[IrCl（COD）]₂(18 mg), dtbpy (4, 4' -di-tert-butylbipyridine) 11 mg, and finally a magnetic stir bar was placed in the flask; the remaining procedure was the same as for the boration of polysulfone to give 1.34 g of borated biphenol (B-D).

Second, preparation of tetramethylbenzylguanidine bromide: tetramethylbenzylguanidine was dissolved in 1, 2-dichloroethane, and the resulting solution was poured into a three-necked flask, and 0.267 g of a brominating agent NBS and 0.0247 g of an initiator AIBN were added as initiators for the brominating agent. Boiling and refluxing the mixture for 8 hours under the conditions of heating to 75 ℃ and stirring, gradually changing the solution into red along with the reaction, and continuously reacting for a period of time after the red color of the solution fades, thus stopping heating and stirring. Precipitating in absolute methanol or isopropanol, washing to remove impurities, and drying in an oven to obtain 0.54 g of final tetramethyl benzylguanidine bromide.

Third, the polymer guanidino functionalization: taking B-35-PSF (1.77 g), Pd (dppf) Cl₂-CH₂ Cl₂(24 mg,). B-35-PSF, THF (15 mL) and a magnetic stir bar were placed in a two-necked 50 mL round bottom flask. Dissolving dried tetramethyl benzyl guanidine bromide (3.00 mmol) in K₂CO₃To the reaction was added via syringe, the reaction stirred at 75 ℃ for 12h, cooled and diluted with THF (15 mL) and filtered through a short plug of silica gel to remove the catalyst. The excess solvent was evaporated using a rotary evaporator, the remaining solution was added to methanol to precipitate a polymer, and the dissolution and precipitation processes were repeated again. After drying at 80 ℃ for 12h under vacuum, an off-white colour is obtainedFibrous guanidine-functionalized Polymer G₃₅-PSF（2.79 g）。

Fourthly, preparing the guanidinated diphenol: taking B-D (1.04 g), Pd (dppf) Cl₂ -CH₂ Cl₂(48 mg). B-D, THF (15 mL) and a magnetic stir bar were placed in a two-necked 50 mL round-bottom flask, and dried tetramethylguanidine bromide (3.00 mmol) was dissolved in K₂CO₃Aqueous solution, then, added to the reaction via syringe, stirred at 75 ℃ for 12h, cooled as the reaction was diluted with THF (15 mL), then filtered through a short plug of silica gel to remove the catalyst. Then washed with dichloromethane and ultrapure water, and finally the excess solvent was evaporated with a rotary evaporator, and the remaining liquid was dried under vacuum at 80 ℃ for 12 hours to obtain a guanidine-functionalized organic substance G-D (1.48G).

Fifth, preparation of guanidine functionalized polymers in cross-linked network structure: taking the prepared G₃₅PSF (1.15G), G-D (1.08G) and K₂CO₃(0.83 g) were mixed together and dissolved in a mixed solution of 10mL of N, N-dimethylacetamide (DMAc) and 5mL of toluene. Heating the mixed solution to 100 ℃ and refluxing for 4 h, then heating the reaction system to 150 ℃ and continuing to react for 18 h, dropwise adding the reaction solution into water after the reaction is finished, and then filtering and drying to obtain a product D-G₃₅PSF (2.22 g), the product solvent was then dissolved in dimethyl sulfoxide, and the casting solution was cast onto a glass plate to form a film. After the solvent is evaporated and the primary film is formed, the film is placed in a vacuum drying oven for heat preservation for 12 hours at 50 ℃. Then soaking the membrane according to the sequence of water, alkali and water to ensure that all anions of the anion exchange membrane are OH^-Finally, the membrane is washed to be neutral by ultrapure water, and the polysulfone anion exchange membrane D-G with the cross-linked network structure is obtained₃₅-OH-PSF。

When the degree of crosslinking of the polysulfone anion-exchange membrane with the side chain net structure is 15 percent, the water absorption rate at room temperature reaches 12 percent, and the conductivity at 25 ℃ is 31.25 mS cm^-1And when the temperature is increased to 80 ℃, the conductivity is as high as 78.2 mS cm^-1The conductivity hardly changed when the film was immersed in 6M NaOH aqueous solution for 450 h. Visible network structure andthe introduction of a large amount of guanidine functional groups greatly improves the comprehensive performance of the membrane.

Example 3

The procedure for the boration preparation of tetramethylbenzylguanidine bromide, M and Q, the preparation of the polymeric guanidino-functionalized guanidinium diphenol and the procedure for the preparation of the guanidinium-functionalized diphenol were as in example 1, except that the catalyst used in the coupling reaction in the guanidino-functionalization of the polymer was tris (dibenzylideneacetone) dipalladium in an amount of 53.8 mg.

Preparing a polysulfone anion-exchange membrane with a side chain net structure: the same procedure was used as in example 1.

Film forming: the same procedure as in example 1 was used.

It was determined that the polysulfone anion-exchange membrane having a side-chain network structure prepared in this example had a degree of crosslinking of 19%, a water absorption at room temperature of 14%, and an electrical conductivity of 35.65 mS · cm at 25 deg.C^-1And when the temperature is increased to 80 ℃, the conductivity is as high as 83.46 mS cm^-1The conductivity hardly changed when the film was immersed in 6M NaOH aqueous solution for 450 h. Therefore, the net structure and the introduction of a large amount of guanidine functional groups can be seen, and the comprehensive performance of the membrane is greatly improved.

Example 4

First, tetramethylbenzylguanidine bromide, guanidino-functionalized polymer, guanidinated biphenol were prepared in the same manner as in example 2, except that the catalyst used in the Q and M boration reaction was tris (dibenzylideneacetone) dipalladium. The amount added was 26.9 mg.

Preparing a polysulfone anion-exchange membrane with a side chain net structure: the same procedure was used as in the second example.

Film forming: the same procedure was used as in example 2.

It was determined that the polysulfone anion-exchange membrane having a side-chain network structure prepared in this example had a degree of crosslinking of 18%, a water absorption at room temperature of 9.2%, and an electrical conductivity of 36.83 mS. cm at 25 deg.C^-1And when the temperature is increased to 80 ℃, the conductivity is as high as 85.28 mS cm^-1The conductivity hardly changed when the film was immersed in 6M NaOH aqueous solution for 450 h. Visible net knotThe introduction of a large amount of structural guanidine functional groups greatly improves the comprehensive performance of the membrane.

Example 5

First, tetramethylbenzylguanidine bromide, guanidino functionalized polymer, guanidino diphenol were prepared in the same manner as in example 2, except that the catalyst used in the Q and M boration reaction was palladium acetate (Pd (OAc)₂). The amount added was 8.8 mg.

Preparing a polysulfone anion-exchange membrane with a side chain net structure: the same procedure was used as in example 2.

Film forming: the same procedure was used as in example 2.

It was determined that the polysulfone anion-exchange membrane having a side-chain network structure prepared in this example had a degree of crosslinking of 13%, a water absorption at room temperature of 16%, and an electric conductivity of 29.63 mS · cm at 25 deg.C^-1And when the temperature is increased to 80 ℃, the conductivity is as high as 75.67 mS cm^-1The conductivity hardly changed when the film was immersed in 6M NaOH aqueous solution for 450 h. Therefore, the net structure and the introduction of a large amount of guanidine functional groups can be seen, and the comprehensive performance of the membrane is greatly improved.

Claims

1. A preparation method of a guanidino functionalized anion exchange membrane with a cross-linked network structure is characterized by comprising the following steps: the method comprises the following specific steps:

firstly, the preparation method of M and Q by boration comprises the following steps: a50 mL flask was charged with tetrahydrofuran THF as a solvent, 2 g of polysulfone was dissolved in THF as a solvent, and bis (pinacolato) diboron B was further added₂Pin₂76 mg, 1, 5-Cyclooctadiene Iridium chloride dimer [ IrCl (COD)]₂24 mg, 4,4' -di-tert-butyl bipyridyl dtbpy27 mg, finally placing a magnetic stirring rod into the flask, sealing the flask, and then stirring and reacting for 18 h under the condition of oil bath at 60 ℃; after the reaction was completed, the reaction solution was diluted with the solvent THF15 mL, then filtered through a short silica gel plug to remove the catalyst, the remaining filtrate was put into a rotary evaporator to evaporate the excess solvent and poured into methanol to precipitate the polymer, the process of dissolution and precipitation of the polymer was repeated again, and then the polymer was placed in a beaker and placed in a beakerDrying at 60 deg.C under vacuum for 10 h; finally obtaining 2.18 g of borated polymer B-70-PSF; the boration method of 4,4 '-biphenol comprises adding THF solvent into flask, dissolving 1.26 g of 4,4' -biphenol in the THF solvent, and adding B₂Pin₂66 mg，[IrCl（COD）]₂18 mg, dtbpy 22 mg, and finally placing a magnetic stirring rod into the flask; the rest operation steps are the same as the boric acid treatment of the polysulfone, and 1.33 g of boric acid diphenyl diphenol B-D organic matter is finally obtained;

second, preparation of tetramethylbenzylguanidine bromide: dissolving 0.617 g of tetramethyl benzylguanidine in 1, 2-dichloroethane, pouring into a three-neck flask, and adding 0.533 g of brominating agent NBS and 0.0493 g of initiator AIBN respectively; boiling and refluxing the mixture for 12 hours under the conditions of heating to 80 ℃ and stirring, gradually changing the solution into red along with the reaction, and continuously reacting for 2 hours after the red color of the solution fades, and stopping heating and stirring; precipitating in absolute methanol or isopropanol, washing to remove impurities, and drying in an oven to obtain 1.06 g of final tetramethyl benzyl guanidine bromide;

third, the polymer guanidino functionalization: taking 1.77 g of B-70-PSF, [1,1' -bis (diphenylphosphino) ferrocene]Palladium dichloride dichloromethane complex Pd (dppf) Cl₂ -CH₂ Cl₂48 mg, THF15 mL and a magnetic stir bar were placed in a two-necked 50 mL round bottom flask; dissolving dried tetramethyl benzyl guanidine bromide 6.00 mmol in K₂CO₃Aqueous solution, then added to the reaction via syringe, stirred at 75 ℃ for 12h, cooled with reaction, diluted with THF15 mL, then filtered through a short plug of silica gel to remove catalyst; concentrating the filtrate using a rotary evaporator and pouring into methanol to precipitate a polymer, repeating the dissolving and precipitating processes again; after drying at 80 ℃ under vacuum for 12h, the guanidine-functionalized polymer, gray fiber G, was obtained₇₀-PSF3.82 g；

Fourthly, preparing the guanidinated diphenol: taking 1.04 g of B-D, Pd (dppf) Cl₂-CH₂Cl₂48 mg, THF15 mL and a magnetic stir bar were placed in a two-necked 50 mL round bottom flask; dissolving dried tetramethyl benzyl guanidine bromide 6.00 mmol in K₂CO₃In aqueous solution, byThe reaction was stirred at 75 ℃ for 12h with syringe addition, diluted with 15mL of THF after cooling, and filtered through a short plug of silica gel to remove the catalyst; then washing with dichloromethane and ultrapure water, and finally evaporating the redundant solvent by using a rotary evaporator; vacuum drying the residual nonvolatile liquid at 80 ℃ for 12h and 3.08G to obtain a guanidine functionalized organic matter G-D;

fifth, preparation of guanidine functionalized polymers in cross-linked network structure: taking the prepared G₇₀PSF 1.23G, G-D1.08G and K₂CO₃0.83 g of the resulting mixture was mixed together and dissolved in a mixed solution of 10mL of N, N-dimethylacetamide DMAc and 5mL of toluene; heating the mixed solution to 100 ℃ and refluxing for 4 hours, then heating the reaction system to 150 ℃ and continuing to react for 18 hours, dropwise adding the reaction liquid into hot water after the reaction is finished, and then filtering and drying to obtain a product D-G₇₀2.28 g of PSF, then dissolving the product solvent in dimethyl sulfoxide, and pouring the casting solution on a glass plate to form a film; after the solvent is evaporated and the primary film is formed, the film is placed in a vacuum drying oven for heat preservation for 12 hours at 50 ℃; then soaking the anion exchange membrane in the order of water, alkali and water to ensure that all anions of the anion exchange membrane are OH^-Finally, the membrane is washed to be neutral by ultrapure water, and the polysulfone negative ion exchange membrane D-G with the cross-linked net structure is obtained₇₀-OH-PSF。