CN110903449B - Isatin arene copolymer, preparation method and application - Google Patents

Abstract

The invention belongs to the field of high molecular materials and polymer ion exchange membranes thereof, and relates to an isatin arene copolymer, a preparation method and application thereof. The invention synthesizes isatin-arene copolymer with ammonium cation by using substituted isatin, methyl piperidone and arene through super acid catalyzed hydroxyalkylation polycondensation, and electrolyte solution and tough polymer anion exchange membrane are conveniently prepared. The intrinsic viscosity of the ammonium isatin aromatic hydrocarbon copolymer prepared according to the invention is 1.5-4.0 dL/g (DMAc,25 ℃), and the polymer can be crosslinked or functionalized by introducing an isatin structural unit, so that the chemical stability and the mechanical property are further improved. The copolymer electrolyte solution and the ion exchange membrane have high ion conductivity, excellent alkali resistance/oxidation resistance and mechanical properties, and wide application in fuel cells, energy storage cells, electrolysis and other electrochemical devices or membrane separation related fields.

Description

A kind of isatin aromatic copolymer, preparation method and application

technical field

The invention belongs to the field of polymer materials and polymer ion exchange membranes thereof, and relates to an isatin aromatic hydrocarbon copolymer, a preparation method and an application.

Background technique

As a clean hydrogen energy technology, polymer ion exchange membrane fuel cells have the advantages of room temperature start-up, high energy efficiency, zero pollution, etc., and are widely used in the fields of transportation, aerospace, ships and military science and technology. At present, the operation of proton exchange membrane fuel cell (PEMFC) requires a precious metal platinum catalyst, and uses an expensive perfluoropolymer ion membrane such as the Nafion ion membrane of DuPont in the United States. Therefore, the high cost of PEMFC restricts its popularization and application. Alkaline anion exchange membrane fuel cells (AEMFCs), operating under alkaline conditions, can use non-precious metal catalysts such as nickel, cobalt, silver, etc., avoiding the use of precious metal platinum catalysts with limited resources, and at the same time have efficient oxygen reduction kinetics, therefore, AEMFC technology has low cost and high battery performance, and has received great attention in recent years.

At present, one of the bottleneck problems in AEMFC is the poor mechanical properties and chemical stability of polymer ion membranes in alkaline environments, and the poor performance of electrolyte solutions in membrane electrodes, resulting in poor fuel cell performance. Develop alkaline ion membrane materials and polymer electrolyte solutions that can meet practical applications. The piperidine aromatic polymer synthesized by Olsson et al. was stable in 2M NaOH solution at 60°C for 15 days, and the hydroxide conductivity reached 89mS·cm ^-1 at 80°C [Olsson JS et al, Advanced Functional Materials, 2018, 28(2):1702758]. Peng et al. synthesized poly-N-methylpiperidine arene copolymers, with a peak power density of up to 1.5 W·cm ^-2 in a hydrogen-oxygen fuel cell, and a stable battery operation of 100 h [Peng H, et al. Journal of Power Sources, 2018 , 390:165-167].

SUMMARY OF THE INVENTION

Aiming at the key problems of poor mechanical properties and chemical stability of polymer ion membranes in current alkaline fuel cells, the present invention provides an isatin aromatic copolymer with good mechanical properties and high alkali resistance stability, and an electrolyte solution thereof. And ion exchange membrane, preparation method and application thereof. The present invention introduces isatin structural unit into the copolymer, which facilitates the cross-linking and functionalization of the polymer, and further improves the mechanical properties and chemical stability of the polymer ion membrane and the electrolyte solution (Ionomer). It is widely used in the fields of electrolysis of water to hydrogen, membrane separation and other electrochemical devices.

The present invention adopts the following technical solutions to realize:

An isatin aromatic copolymer, the structure is shown in general formula I:

Among them, 0<n<1;

R is H or C ₁ -C ₁₂ alkyl, dibromoalkane, alkene, benzyl styrene, epoxy, acrylate or -(CH ₂ ) _n' -G, wherein G is trimethylamine, N- Methylpiperidine, N-methylpyrrole or N-methylmorpholine alkylated ammonium ion; n'=1～10.

Ar is an aromatic hydrocarbon with the following structure:

Wherein, R ₁ is a methyl group or a C ₁ -C ₁₂ alkyl group.

A preparation method of isatin aromatic hydrocarbon copolymer, the concrete steps are as follows:

Step 1, Synthesis of Substituted Isatin

Dissolve isatin in solvent A to make a 1-20wt% solution, add excess anhydrous K ₂ CO ₃ and stir to dissolve, then add compound B, and control the molar ratio of isatin to compound B to be 1:1～1:3, React at 20-60°C for 10-50h; after the reaction, pour the reaction solution into ice water, extract with an extractant, spin steam, and recrystallize the crude product from ethanol to obtain substituted isatin.

The solvent A is one or a mixture of two or more of N,N-dimethylacetamide, N,N-dimethylformamide, chloroform, dimethyl sulfoxide, and N-methylpyrrolidone.

The compound B is bromoalkane, bromoalkene, vinylbenzyl chloride, glycidyl acrylate (GMA), bromoalkylammonium salt Br-( _CH2 ) _n' -G or 1,6-di Bromoalkanes.

The extraction agent is one or more of methanol, toluene, acetone, petroleum ether, ether and chloroform.

Step 2, Synthesis of Isatin Arene Copolymer

Adding the substituted isatin, N-methyl-4-piperidone and aromatic hydrocarbon obtained in step 1 into dichloromethane, stirring and dissolving under an ice bath so that the monomer concentration of the substituted isatin is 15-40wt% to obtain a mixed solution; Trifluoromethanesulfonic acid and trifluoroacetic acid were added to the mixture as catalysts, and the reaction was stirred at 0 to 5 °C for 14 to 48 h; when the reaction was over, the product was poured into ice water, filtered, and the excess acid was removed with NaHCO ₃ , and washed with water. , filtration, and vacuum drying to obtain a white fibrous isatin aromatic copolymer; the copolymer is dissolved in solvent A, then poured into a precipitant, filtered, and dried to obtain a refined fibrous isatin aromatic copolymer.

The ratio of the total moles of the substituted isatin and N-methyl-4-piperidone to the moles of aromatic hydrocarbons is (1-1.1): 1; the substituted isatin and N-methyl-4-piperidone The molar ratio of the trifluoromethanesulfonic acid to the aromatic hydrocarbon is (6 to 14):1; the volume ratio of the trifluoromethanesulfonic acid to the trifluoroacetic acid is ( 8 to 14): 1.

The aromatic hydrocarbon is biphenyl, p-terphenyl, m-terphenyl, 9,9-dialkyl fluorene or bisphenol fluorene.

The precipitating agent is one or a mixture of two or more of methanol, ethanol, water, petroleum ether, ethyl acetate, acetone and ether.

A method of isatin aromatic copolymer for preparing anion exchange membrane, the steps are as follows:

Step (1), the synthesis of isatin aromatic copolymer with ammonium cation

Dissolving the isatin arene copolymer in solvent A to obtain a 5-20wt% solution, adding methyl iodide or bromoalkane R ₁ -Br, wherein the mol ratio of methyl iodide or R ₁ -Br and the isatin arene copolymer is ( 5～15): 1, react at 30～100 ℃ for 20～100h; after the reaction, pour the reaction solution into the precipitating agent, filter, and wash the product to obtain isatin aromatic copolymer with ammonium cation, and its structure is as follows: Formula II is shown as:

Wherein, 0<n<1; X ^- is a counter ion, which is Br ^- or OH ^- ion; R ₁ is a methyl group or a C ₁ -C ₁₂ alkyl group.

The solvent A is one or a mixture of two or more of N,N-dimethylacetamide, N,N-dimethylformamide, chloroform, dimethyl sulfoxide, and N-methylpyrrolidone.

The precipitating agent is one or a mixture of two or more of methanol, ethanol, water, petroleum ether, ethyl acetate, acetone and ether.

Step (2), preparation of electrolyte solution (Ionomer) of isatin aromatic copolymer with ammonium cation

The isatin aromatic hydrocarbon copolymer with ammonium cation prepared in step (1) is added to solvent A, stirred to dissolve, and defoamed to obtain a transparent and uniform electrolyte solution (Ionomer), and the solution concentration is determined according to actual needs.

Step (3), preparation of isatin aromatic copolymer anion exchange membrane

Lay a film of the electrolyte solution with a concentration of 3-15wt% obtained in step (2), immerse the film at room temperature to 80°C, carry out ion exchange with 1M NaOH or KOH solution for 2-24 hours, soak in deionized water at room temperature for 24-48 hours, and wash with water to medium isatin aromatic copolymer anion exchange membrane; wherein, when R in the general structural formula of isatin arene copolymer is olefin, styrene benzyl, epoxy group or acrylate, it is added during film making Thermal initiator or photoinitiator to obtain cross-linked isatin aromatic copolymer anionic film; when R is dibromoalkane, add diamine or ternary amine for chemical cross-linking to obtain cross-linked isatin Aromatic copolymer anionic membrane.

The bromoalkane R ₁ -Br, wherein R ₁ is a methyl group or a C ₁ -C ₁₂ alkyl group.

The above-mentioned isatin aromatic copolymer electrolyte solution (Ionomer) is used as a resin binder in the preparation of membrane electrodes in fuel cells.

The application of the above-mentioned isatin aromatic copolymer anion exchange membrane in the fields of fuel cells, flow cells, electrolysis, electrodialysis or separation membranes.

A synthetic route of isatin aromatic copolymer, electrolyte solution and ion exchange membrane thereof is as follows:

A method of isatin aromatic copolymer for preparing composite membrane, the concrete steps are as follows:

Step (1), the synthesis of isatin aromatic copolymer with ammonium cation

Dissolving the isatin arene copolymer in solvent A to obtain a 5-20wt% solution, adding methyl iodide or bromoalkane R ₁ -Br, wherein the mol ratio of methyl iodide or R ₁ -Br and the isatin arene copolymer is ( 5～15): 1, react at 30～100 ℃ for 20～100h; after the reaction, pour the reaction solution into the precipitating agent, filter, and wash the product to obtain isatin aromatic copolymer with ammonium cation, and its structure is as follows: The general formula (II) is shown as:

Wherein, 0<n<1; X ^- is a counter ion, which is Br ^- or OH ^- ion; R ₁ is a methyl group or a C ₁ -C ₁₂ alkyl group.

The solvent A is one or a mixture of two or more of N,N-dimethylacetamide, N,N-dimethylformamide, chloroform, dimethyl sulfoxide, and N-methylpyrrolidone.

The precipitating agent is one or a mixture of two or more of methanol, ethanol, water, petroleum ether, ethyl acetate, acetone and ether.

Step (2), the preparation of isatin aromatic copolymer solution with ammonium cation

Adding the isatin aromatic copolymer with ammonium cations prepared in step (1) into solvent A, stirring and dissolving to prepare a 1-10 wt% solution, and defoaming to obtain a transparent and uniform solution of isatin aromatic hydrocarbon copolymers with ammonium cations.

Step (3), the preparation of composite membrane

Immerse the base film in ethanol at room temperature for 3 to 24 hours, take out the base film and lay it flat, drop a small amount of solvent A evenly on the surface to infiltrate the base film, and then soak the isatin aromatic copolymer solution with ammonium cations prepared in step (2). Cast on the base film and self-leveling, put the base film in a drying box to dry to constant weight; then, immerse the obtained base film in room temperature ~ 80 ℃, 1M NaOH for 2 ~ 24h ion exchange, put in deionized water at room temperature for 24 ~ 48h, take out, and vacuum dry to constant weight to obtain a composite membrane of isatin aromatic copolymer.

The base film is a polytetrafluoroethylene or polyethylene microporous film, and the porosity is more than 90%.

The prepared isatin aromatic copolymer composite membrane is applied to fuel cells, flow cells, electrolysis, electrodialysis or separation membranes.

Compared with the prior art, the beneficial effects of the present invention:

The intrinsic viscosity of the isatin aromatic copolymer with ammonium cation prepared according to the present invention is 1.5-4.0 dL/g at 25° C. in N,N-dimethylacetamide. The electrolyte solution of isatin aromatic copolymer and its anion exchange membrane prepared according to the invention have high ionic conductivity, for example, the OH ^- ion conductivity can reach 100 mS/cm at 80°C, and both wet and dry films have strong toughness , excellent mechanical properties, soaked in 80 ℃, 1M NaOH solution for 30-40 days, the ionic conductivity decreases less, and the alkali resistance stability is excellent. It is widely used in the fields of fuel cells, flow batteries, electrolysis and electrodialysis plasma membranes application.

Description of drawings

FIG. 1 is a ¹ H-NMR spectrum of allylisatin in Example 1. FIG.

FIG. 2 is the ¹ H-NMR spectrum of the spirocyclic ammonium salt isatin-piperidone-biphenyl copolymer in Example 1. FIG.

3 is the ¹ H-NMR spectrum of the hexylmethyl-piperidine salt isatin-methylpiperidone-biphenyl copolymer in Example 8. FIG.

4 is a ¹ H-NMR spectrum of the allylisatin-methylpiperidone-terphenyl copolymer in Example 6. FIG.

Detailed ways

The following examples further illustrate the isatin aromatic copolymer, preparation method and application of the present invention in detail, but are not intended to limit the protection scope of the present invention.

Test methods involved in the examples:

IEC test method: Take about 0.2 g of three isatin aromatic copolymers and soak them in 100 mL of 1mol/L NaCl solution for 24 hours. Then soak in deionized water for 24h, dry in a vacuum oven, and record the weighing. Then soak in 25mL of 0.5M NaNO ₃ solution for 24h, add potassium chromate solution indicator, and titrate with 0.1M AgNO ₃ solution. When a brick red precipitate appears and does not change color within 30 seconds, it means the titration is completed, and record the consumption. _AgNO3 solution volume. The IEC is obtained by dividing the product of the concentration and volume _of the AgNO3 solution by the mass of the film after drying.

Alkali resistance stability: Soak the membrane in 80°C, 1M NaOH solution, take out the membrane at a certain interval, wash it with deionized water until it becomes neutral, and test the conductivity at room temperature.

Example 1

Dissolve 10mol isatin in dimethyl sulfoxide, add 15mol anhydrous K ₂ CO ₃ and stir to dissolve at room temperature. 12mol of bromopropene was added, and the reaction was carried out at 60°C for 24h. The reaction solution was poured into ice water, extracted with ether, and the ether was removed by rotary evaporation. The product was recrystallized from ethanol to obtain allylisatin.

Allylisatin and 4-piperidone hydrochloride were added to the reactor, biphenyl was added, and dichloromethane was added at 0° C. to stir and dissolve to make the monomer concentration 20wt%. Then, trifluoromethanesulfonic acid and trifluoroacetic acid were added, and the reaction was stirred at 0 °C for 20 h. When the system became viscous, the polymer product was poured into a large amount of ice water, and the excess acid was removed with 1M NaHCO ₃ . The product was washed with water, filtered, and dried in vacuo , to obtain allylisatin-piperidone-biphenyl copolymer. The molar ratio of allylisatin to piperidone monomer is 1:4, and the ratio of the total moles of allylisatin and 4-piperidone hydrochloride to the moles of biphenyl is 1:1 , the molar ratio of trifluoromethanesulfonic acid to biphenyl is 8:1, and the volume ratio of trifluoroacetic acid to trifluoromethanesulfonic acid is 1:8.

Among them, the piperidine structure N-H of the allylisatin-piperidone-biphenyl copolymer and a slight excess of 1,5-dibromopentane undergo a ring-forming reaction under the action of a catalyst, resulting in a spirocyclic ammonium copolymerization thing. The specific reaction is as follows:

Dissolve 1.3mol of the above copolymer in N,N-dimethylformamide to prepare a 5wt% solution, add 1.5mol of DMAc solution of 1,5-dibromopentane dropwise, add 1.5mol of N,N-diisopropyl Ethylamine was used as a catalyst, and the reaction was carried out at 60°C for 36h. After the reaction is completed, it is poured into acetone for precipitation, filtered, washed with acetone, washed with water, and dried in vacuum to obtain a spirocyclic aminated allylisatin-piperidone-biphenyl copolymer.

The above-mentioned spirocyclic aminated copolymer is dissolved in N-methylpyrrolidone to prepare a casting solution. Pour onto a clean glass plate and dry. The membrane was soaked at 80°C, ion-exchanged in 1M NaOH for 2 h, then soaked in deionized water for 24 h, and washed with water to obtain a copolymer anion-exchange membrane.

The above-mentioned spiro ammonium copolymer was dissolved in N-methylpyrrolidone to prepare a 10 wt% casting solution. A small amount of 2,2-(1,2-ethanediyldioxo)bisethanethiol was added as a cross-linking agent and a photoinitiator was added. The casting solution was poured onto a clean glass plate and cross-linked by irradiation with a 365 nm UV lamp. Oven drying to obtain a cross-linked spiro-ring ammonium copolymer anionic membrane.

The structural formula of the spiro ammonium copolymer is as follows:

Fig. 1 is a ¹ H-NMR spectrum of allylisatin. The chemical shifts are the chemical shifts of the protons on the isatin benzene ring at 7.53 and 7.6, 7.09 and 7.01 ppm, and the chemical shifts of the protons on the double bond of the olefin isatin at 5.8, 5.32 and 5.15 ppm, and the chemical shifts are 4.27 ppm is the chemical shift of the proton on the methylene group attached to the N atom of isatin. The above analysis indicated that allylisatin was successfully synthesized.

Figure 2 is a ¹ H-NMR spectrum of an allylisatin-piperidone-biphenyl copolymer and a spirocyclic aminated polyallylisatin-piperidone-biphenyl anion membrane. As can be seen from Figure 2, the peaks with chemical shifts at 7.09-7.6 ppm are the proton peaks on the benzene ring, the peaks at 8.9 ppm are the characteristic peaks of NH on piperidine, and the peaks at 5.9, 5.16 and 1.9 ppm are the N atoms attached to isatin. Characteristic peaks of the upper double bond hydrogen, at 3.06, 2.69 and 2.18 ppm are the proton peaks of the methylene group on the piperidine ring. After the N atom of piperidone was formed into a ring, its NH peak disappeared, and chemical shift peaks at 1.76 and 1.56 ppm appeared, which were the characteristic peaks of the proton on the N spiro ring. This indicates that the above-mentioned copolymer and spiro-amminated copolymer anionic membrane have been successfully synthesized. The prepared anion membrane is transparent and light yellow, and has good flexibility.

The experimental test shows that the ion exchange capacity IEC is 1.03mmol/g, the hydroxide ion conductivity is 53mS/cm at 80°C, the water absorption rate is 45% at 80°C, and the swelling degree is 5.5%. After soaking in 1M NaOH solution at 80℃ for 570h, the ionic conductivity retention rate was 90%.

Example 2

Synthesis of allyl isatin: the method is the same as that in Example 1, 10mol isatin is dissolved in dimethyl sulfoxide, and 15mol anhydrous K ₂ CO ₃ is added to dissolve at room temperature with stirring. 10mol of bromopropene was added, and the reaction was carried out at 20°C for 50h. The reaction solution was poured into ice water, extracted with ether, and the ether was removed by rotary evaporation. The product was recrystallized from ethanol to obtain allylisatin.

Allylisatin, N-methyl-4-piperidone were added to the reactor, and biphenyl was added. Add dichloromethane and stir to dissolve at 0°C to make the monomer concentration 20wt%. Trifluoromethanesulfonic acid and trifluoroacetic acid were added, and the reaction was stirred at 0 °C for 14 h. When the system became viscous, the polymer product was poured into a large amount of ice water, and the excess acid was removed with 1M NaHCO ₃ . The product was washed with water, filtered, and dried in vacuo. Allylisatin-methylpiperidone-biphenyl copolymer was obtained. Among them, the molar ratio of allylisatin and N-methyl-4-piperidinone is 2:3, and the total moles of allylisatin and N-methyl-4-piperidinone is the same as that of biphenyl. The molar ratio is 1:1, the molar ratio of trifluoromethanesulfonic acid to biphenyl is 6:1, and the volume ratio of trifluoroacetic acid to trifluoromethanesulfonic acid is 1:14.

2mol of the above copolymer was dissolved in N,N-dimethylacetamide to prepare a 15wt% solution, and 30mol of methyl iodide was added to react at 40°C for 24h. The polymer solution was poured into acetone for precipitation, filtered, washed with water, and dried in an oven to obtain an ammoniumized copolymer. The above-mentioned aminated copolymer was added to dimethylacetamide, stirred and dissolved to obtain a clear electrolyte solution (Ionomer). It was poured on a clean glass plate and dried in an oven at 60° C. to obtain the anion exchange membrane of the ammoniumized copolymer. The film thickness is adjusted by the solution concentration, generally the concentration of the casting solution is 5-15wt%.

Alternatively, the above-mentioned aminated copolymer was dissolved in dimethylacetamide to prepare 8 wt% casting solution. Pour it on a clean glass plate, add a photoinitiator, and place it under a 365 nm ultraviolet lamp for 30 minutes to obtain an anion exchange membrane of a cross-linked ammonium copolymer.

The structural formula of the ammoniumized copolymer is as follows:

At 80°C, the hydroxide ion conductivity is 100mS/cm, and the alkali resistance is 1800h in 1M NaOH at 80°C, and the conductivity decreases by 15%.

Example 3

Synthesis of hexylisatin: use bromohexane instead of bromopropene, the method is the same as that in Example 1, wherein 10mol isatin is dissolved in dimethyl sulfoxide, and 20mol anhydrous K ₂ CO ₃ is added to dissolve at room temperature with stirring. Add 30mol of bromohexane and react at 50°C for 10h. The reaction solution was poured into ice water, extracted with ether, and the ether was removed by rotary evaporation. The product was recrystallized from ethanol to obtain hexylisatin.

Hexylisatin, N-methyl-4-piperidone were added to the reactor, and p-terphenyl was added. Dichloromethane was added at 0°C and stirred to dissolve so that the monomer concentration was 30 wt %. Trifluoromethanesulfonic acid and trifluoroacetic acid were added, and the reaction was stirred at 5 °C for 48 h. When the system became viscous, the polymer product was poured into a large amount of ice water, and the excess acid was removed with 1M NaHCO ₃ . The product was washed with water, filtered, and dried in vacuo. A hexylisatin-methylpiperidone-terphenyl copolymer was obtained. The molar ratio of hexylisatin to N-methyl-4-piperidinone is 1:4, and the ratio of the total moles of hexylisatin and N-methyl-4-piperidinone to the moles of p-terphenyl is 1:1, the molar ratio of trifluoromethanesulfonic acid to p-terphenyl is 12:1, and the volume ratio of trifluoroacetic acid to trifluoromethanesulfonic acid is 1:8.

10 mol of the above copolymer was dissolved in N,N-dimethylformamide to prepare a 10 wt% solution, and 50 mol of methyl iodide was added to react at 30° C. for 100 h. The polymer solution was poured into ethanol for precipitation, filtered, washed with water, and dried in an oven to obtain an ammoniumized copolymer.

The electrolyte solution and anion exchange membrane of the ammonium copolymer were prepared by the method of Example 2, wherein the membrane was soaked at room temperature, ion exchanged in 1M NaOH for 24 hours, then soaked in deionized water for 48 hours, and washed with water.

The structural formula of the ammoniumized copolymer is as follows:

The hydroxide ion conductivity is 85mS/cm at 80℃, and the alkali resistance is 1700h in 1M NaOH at 80℃, and the conductivity decreases by 15%.

Example 4

Isatin, N-methyl-4-piperidone were added to the reactor, and biphenyl was added. Dichloromethane was added at 0°C and stirred to dissolve to make the monomer concentration 35wt%. Trifluoromethanesulfonic acid and trifluoroacetic acid were added, and the reaction was stirred at 0 °C for 20 h. When the system became viscous, the polymer product was poured into a large amount of ice water, and the excess acid was removed with 1M NaHCO ₃ . The product was washed with water, filtered, and dried under vacuum. Isatin-methylpiperidone-biphenyl copolymer was obtained. Among them, the molar ratio of isatin and N-methyl-4-piperidinone is 15:85, and the ratio of the total moles of isatin and N-methyl-4-piperidinone to the moles of biphenyl is 1.1 : 1, the molar ratio of trifluoromethanesulfonic acid to biphenyl is 10:1, and the volume ratio of trifluoroacetic acid to trifluoromethanesulfonic acid is 1:12.

10 mol of the above copolymer was dissolved in dimethylacetamide to prepare a 10 wt% solution, and 60 mol of methyl iodide was added to react at 60° C. for 48 h. The polymer solution was poured into acetone for precipitation, filtered, washed with water, and dried in an oven to obtain an ammonized isatin-methylpiperidone-biphenyl copolymer.

The electrolyte solution and anion exchange membrane of the ammonium copolymer were prepared by the method of Example 2, wherein the membrane was soaked at 80° C., ion exchanged in 1M NaOH for 2 hours, then soaked in deionized water for 24 hours, and washed with water.

Figure 3 is a ¹ H-NMR spectrum of an aminated isatin-methylpiperidone-biphenyl copolymer. The chemical shift at 10.84ppm is the NH peak of the amide bond in isatin, the characteristic peak at 7.05-7.58ppm is the chemical shift of the proton on the benzene ring, and at 3.15ppm is the characteristic peak of the methyl proton on the N atom of piperidine, At 2.84 ppm, it is a characteristic peak of the proton of methylene on the piperidine ring. This indicates that the methylammonium-based isatin-methylpiperidone-biphenyl copolymer was successfully synthesized.

The structural formula of the ammonium copolymer is as follows:

The hydroxide ion conductivity is 85mS/cm at 80℃, and the alkali resistance is 1700h in 1M NaOH at 80℃, and the conductivity decreases by 15%.

Example 5

Synthesis of vinylbenzylisatin, same as Example 2.

Vinylbenzylisatin, N-methyl-4-piperidone were added to the reactor, and m-terphenyl was added. Dichloromethane was added at 0°C and stirred to dissolve so that the monomer concentration was 28 wt %. Add trifluoromethanesulfonic acid and trifluoroacetic acid, stir the reaction at 0 °C, when the system becomes viscous, pour the polymerized product into a large amount of ice water, remove the excess acid with 1M _NaHCO3 , wash the product with water, filter, and vacuum dry to obtain Vinylbenzylisatin-methylpiperidone-biphenyl copolymer. Wherein the molar ratio of vinylbenzylisatin to N-methyl-4-piperidinone is 3:7, and the total moles of vinylbenzylisatin and N-methyl-4-piperidinone are related to the meta-triple The molar ratio of benzene is 1.05:1, the molar ratio of trifluoromethanesulfonic acid to m-terphenyl is 6:1, and the volume ratio of trifluoroacetic acid to trifluoromethanesulfonic acid is 1:10.

10 mol of the above copolymer was dissolved in N,N-dimethylacetamide to prepare a 3 wt% solution, and 60 mol of bromohexane was added to react at 50° C. for 36 h. The polymer solution was poured into methanol for precipitation, filtered, washed with water, and dried in an oven to obtain an ammoniumized copolymer.

Using the method of Example 2, the electrolyte solution and the anion exchange membrane of the ammoniumized copolymer were prepared.

The preparation of the cross-linked ammonium ion membrane is the same as in Example 2.

The structural formula of the ammonium copolymer is as follows:

At 80°C, the hydroxide ion conductivity is 80mS/cm, and the alkali resistance is reduced by 15% in 1M NaOH for 2000h at 80°C.

Example 6

Synthesis of allylisatin is the same as in Example 1.

Allylisatin, N-methyl-4-piperidone were added to the reactor, and p-terphenyl was added. Dichloromethane was added at 0°C and stirred to dissolve so that the monomer concentration was 30 wt %. Trifluoromethanesulfonic acid and trifluoroacetic acid were added, and the reaction was stirred at 0 °C for 22 h. When the system became viscous, the polymer product was poured into a large amount of ice water, and the excess acid was removed with 1M NaHCO ₃ . The product was washed with water, filtered, and dried in vacuo. Allylisatin-methylpiperidone-terphenyl copolymer was obtained. Wherein the molar ratio of allylisatin to N-methyl-4-piperidinone is 1:9, and the total moles of allylisatin and N-methyl-4-piperidinone is the same as that of p-terphenyl. The molar ratio is 1.1:1, the molar ratio of trifluoromethanesulfonic acid to p-terphenyl is 9:1, and the volume ratio of trifluoroacetic acid to trifluoromethanesulfonic acid is 1:10.

10mol of the above copolymer was dissolved in N,N-dimethylacetamide to prepare an 8wt% solution, and 100mol of methyl iodide was added to react at 70°C for 48h. The polymer solution was poured into diethyl ether to separate out, filtered, washed with water, and dried in an oven to obtain an ammonium copolymer.

Using the method of Example 2, the electrolyte solution and the anion exchange membrane of the ammoniumized copolymer were prepared.

The preparation of the cross-linked ammonium ion membrane is the same as in Example 2.

The structural formula of the ammonium copolymer is as follows:

At 80°C, the hydroxide ion conductivity is 80mS/cm, and the alkali resistance is reduced by 15% in 1M NaOH for 2000h at 80°C.

4 is a ¹ H-NMR chart of Example 6 allylisatin-methylpiperidone-terphenyl copolymer.

Example 7

Synthesis of hexylisatin: use bromohexane instead of bromopropene, and other reactions are the same as in Example 1.

Hexylisatin, N-methyl-4-piperidone were added to the reactor, and biphenyl was added. Dichloromethane was added at 0°C and stirred to dissolve to make the monomer concentration 15wt%. Trifluoromethanesulfonic acid and trifluoroacetic acid were added, and the reaction was stirred at 0 °C for 30 h. When the system became viscous, the polymer product was poured into a large amount of ice water, and the excess acid was removed with 1M NaHCO ₃ . The product was washed with water, filtered, and dried under vacuum. A hexylisatin-methylpiperidone-biphenyl copolymer was obtained. The molar ratio of hexylisatin to N-methyl-4-piperidone is 1:4, and the ratio of the total moles of hexylisatin and N-methyl-4-piperidone to the moles of biphenyl is 1:1, the molar ratio of trifluoromethanesulfonic acid to biphenyl is 14:1, and the volume ratio of trifluoroacetic acid to trifluoromethanesulfonic acid is 1:10.

1 mol of the above copolymer was dissolved in N,N-dimethylacetamide to prepare an 8% solution, and 10 mol of methyl iodide was added to react at 30° C. for 24 h. The polymer solution was poured into methanol for precipitation, filtered, washed with water, and dried in an oven to obtain an ammoniumized copolymer.

Using the method of Example 2, the electrolyte solution and the anion exchange membrane of the ammoniumized copolymer were prepared.

The structural formula of the ammonium copolymer is as follows:

The hydroxide ion conductivity is 85mS/cm at 80℃, and the alkali resistance is 1600h in 1M NaOH at 80℃, and the conductivity decreases by 15%.

Example 8

Bromohexyl N-methylpiperidine salt was synthesized from N-methylpiperidine and excess dibromohexane through Menxiukin reaction.

Synthesis of N-methylhexylpiperidine salt isatin: bromohexyl N-methylpiperidine salt is used instead of bromopropene, and other reactions are the same as in Example 1.

N-methylhexylpiperidine salt isatin, N-methyl-4-piperidone were added to the reactor, and biphenyl was added. Dichloromethane was added at 0°C and stirred to dissolve to make the monomer concentration 20wt%. Trifluoromethanesulfonic acid and trifluoroacetic acid were added, and the reaction was stirred at 0 °C for 38 h. When the system became viscous, the polymer product was poured into a large amount of ice water, and the excess acid was removed with 1M NaHCO ₃ . The product was washed with water, filtered, and dried under vacuum. The hexylmethylpiperidine salt isatin-methylpiperidone-biphenyl copolymer was obtained. Wherein the molar ratio of N-methylhexylpiperidine salt isatin and N-methyl-4-piperidone is 2:3, N-methylhexylpiperidine salt isatin and N-methyl-4-piperidine The ratio of the total moles of ketone to the moles of biphenyl is 1:1, the molar ratio of trifluoromethanesulfonic acid to biphenyl is 7:1, and the volume ratio of trifluoroacetic acid to trifluoromethanesulfonic acid is 1:8.

3mol of the above copolymer was dissolved in N,N-dimethylacetamide to prepare an 8% solution, and 20mol of iodohexane was added to react at 60°C for 24h. The polymer solution was poured into methanol for precipitation, filtered, washed with water, and dried in an oven to obtain an ammoniumized copolymer.

Using the method of Example 2, the electrolyte solution and the anion exchange membrane of the ammoniumized copolymer were prepared.

The structural formula of the ammonium copolymer is as follows:

At 80 °C, the hydroxide ion conductivity is 110mS/cm, and the alkali resistance is 1800h in 1M NaOH at 80 °C, and the conductivity decreases by 15%.

Example 9

The synthesis of vinylbenzylisatin is the same as in Example 2.

Vinylbenzylisatin, N-methyl-4-piperidone were added to the reactor, and bisphenol fluorene was added. Dichloromethane was added at 0°C and stirred to dissolve to make the monomer concentration 35wt%. Trifluoromethanesulfonic acid and trifluoroacetic acid were added, and the reaction was stirred at 0 °C for 20 h. When the system became viscous, the polymer product was poured into a large amount of ice water, and the excess acid was removed with 1M NaHCO ₃ . The product was washed with water, filtered, and dried under vacuum. The vinylbenzylisatin-methylpiperidone-bisphenol fluorene copolymer was obtained. Wherein the molar ratio of vinylbenzylisatin and N-methyl-4-piperidone is 1:4, and the total moles of vinylbenzylisatin and N-methyl-4-piperidone are the same as those of bisphenol The molar ratio of fluorene is 1:1, the molar ratio of trifluoromethanesulfonic acid to p-bisphenol fluorene is 8:1, and the volume ratio of trifluoroacetic acid to trifluoromethanesulfonic acid is 1:10.

10 mol of the above copolymer was dissolved in dimethyl sulfoxide to prepare a 10 wt% solution, and 60 mol of methyl iodide was added to react at 50° C. for 48 h. The polymer solution was poured into diethyl ether to separate out, filtered, washed with water, and dried in an oven to obtain an ammonium copolymer.

Using the method of Example 2, the electrolyte solution and the anion exchange membrane of the ammoniumized copolymer were prepared.

The preparation of the cross-linked ammonium ion membrane is the same as in Example 2.

The structural formula of the ammonium copolymer is as follows:

The hydroxide ion conductivity is 75mS/cm at 80°C, and the alkali resistance decreases by 15% in 1M NaOH at 80°C for 2000h.

Example 10

The ammoniumized allylisatin-methylpiperidone-biphenyl copolymer prepared in Example 2 was added to dimethyl sulfoxide, stirred and dissolved to prepare a 3wt% solution, and defoamed to obtain a transparent and uniform copolymer solution .

At room temperature, 2.0 × 3.0 cm ² of polytetrafluoroethylene PTFE microporous membrane was soaked in ethanol for 10 h. The PTFE membrane was taken out and flat, and dimethyl sulfoxide was evenly added dropwise with a dropper, and the liquid on the surface of the membrane was blotted dry with filter paper. The above copolymer solution was added dropwise to the surface of the PTFE membrane for self-leveling, and then the membrane was placed in an oven at 60°C to dry to constant weight. The obtained membrane was immersed in 80°C, 1M NaOH for 2h ion exchange, then placed in deionized water at room temperature for 24h, and dried to constant weight to obtain a composite membrane.

At 80°C, the hydroxide ion conductivity is 60mS/cm, and the alkali resistance is 2300h in 1M NaOH at 80°C, and the conductivity decreases by 12%.

Example 11

The ammoniumized allylisatin-methylpiperidone-terphenyl prepared in Example 6 was added to dimethylacetamide DMAc, stirred and dissolved to prepare a 1 wt% solution, and defoamed to obtain a transparent and uniform copolymer solution.

At room temperature, 2.0 × 3.0 cm ² polyethylene microporous membrane was soaked in ethanol for 3 h. The polyethylene microporous membrane was taken out and laid flat, a few drops of DMAc were evenly added dropwise with a dropper, and the liquid on the membrane surface was blotted dry with filter paper. The above-mentioned ammoniumized copolymer solution was added dropwise to the surface of the PTFE membrane for self-leveling, and then the membrane was placed in an oven at 60° C. to dry to constant weight. The obtained membrane was immersed in 1M NaOH at room temperature for 24h ion exchange, then placed in deionized water at room temperature for 48h, taken out, and dried to constant weight to obtain a composite membrane.

Example 12

The aminated hexylmethylpiperidine salt isatin-methylpiperidone-biphenyl copolymer prepared in Example 8 was added to DMAc, stirred and dissolved to prepare a 10wt% solution, and defoamed to obtain a transparent and uniform copolymer solution.

At room temperature, 2.0 × 3.0 cm ² of polytetrafluoroethylene PTFE microporous membrane was soaked in ethanol for 24 h. The PTFE membrane was taken out and flat, and the DMAc solvent was evenly added dropwise with a dropper, and the liquid on the surface of the membrane was blotted dry with filter paper. The above copolymer solution was added dropwise to the surface of the PTFE membrane for self-leveling, and then the membrane was placed in an oven at 60°C to dry to constant weight. The obtained membrane was immersed in 80°C, 1M NaOH for 6h ion exchange, then placed in deionized water at room temperature for 30h, and dried to constant weight to obtain a composite membrane.

Claims (8)

1. An isatin aromatic hydrocarbon copolymer, which is characterized by having a structure shown as a general formula I:

wherein n is more than 0 and less than 1;

r is H or C ₁ ～C ₁₂ Alkyl groups of (a);

ar is aromatic hydrocarbon and has the following structure:

wherein R is ₁ Is C ₁ ～C ₁₂ Alkyl group of (1).

2. The preparation method of the isatin arene copolymer is characterized by comprising the following specific steps:

step one, synthesis of substituted isatin

Dissolving isatin in solvent A to obtain 1-20 wt% solution, adding excessive anhydrous K ₂ CO ₃ Stirring to dissolve, adding the compound B, and controlling the molar ratio of the isatin to the compound B to be 1: 1-1: 3, reacting for 10-50h at 20-60 ℃; after the reaction is finished, pouring the reaction solution into ice water, extracting by using an extracting agent, carrying out rotary evaporation, and recrystallizing the crude product by using ethanol to obtain substituted isatin;

the solvent A is one or a mixture of more than two of N, N-dimethylacetamide, N-dimethylformamide, chloroform, dimethyl sulfoxide and N-methylpyrrolidone;

the compound B is brominated alkane, brominated olefin, vinyl benzyl chloride or glycidyl acrylate GMA;

the extractant is one or more than two of methanol, toluene, acetone, petroleum ether, diethyl ether and chloroform;

step two, synthesis of isatin arene copolymer

Adding the substituted isatin, the N-methyl-4-piperidone and the aromatic hydrocarbon obtained in the step one into dichloromethane, and stirring and dissolving in ice bath to enable the monomer concentration of the substituted isatin to be 15-40 wt% to obtain a mixed solution; adding trifluoromethanesulfonic acid and trifluoroacetic acid into the mixed solution as catalysts, and stirring at 0-5 ℃ to react for 14-48h; after the reaction is finished, the product is poured into ice water and filtered, and NaHCO is used as the product ₃ Removing excessive acid, washing with water, filtering, and vacuum drying to obtain white fibrous isatin arene copolymer; dissolving the copolymer in a solvent A, then pouring the solution into a precipitator, filtering and drying the solution to obtain a refined fibrous isatin arene copolymer;

the ratio of the total mole number of the substituted isatin and the N-methyl-4-piperidone to the mole number of the aromatic hydrocarbon is (1-1.1): 1; the molar ratio of the substituted isatin to the N-methyl-4-piperidone is 1: 9-4: 6; the molar ratio of the trifluoromethanesulfonic acid to the aromatic hydrocarbon is (6-14): 1; the volume ratio of the trifluoromethanesulfonic acid to the trifluoroacetic acid is (8-14): 1;

the aromatic hydrocarbon is biphenyl, p-terphenyl, m-terphenyl, 9-dialkyl fluorene or bisphenol fluorene;

the precipitant is one or more of methanol, ethanol, water, petroleum ether, ethyl acetate, acetone, and diethyl ether.

3. A method for preparing an anion exchange membrane from the isatin arene copolymer, which is prepared by the method of claim 2, and is characterized by comprising the following steps:

step (1), synthesis of isatin arene copolymer with ammonium cation

Dissolving isatin arene copolymer in solvent A to obtain 5-20 wt% solution, and adding methyl iodide or bromoalkane R ₁ -Br, wherein methyl iodide or R ₁ The molar ratio of-Br to the isatin arene copolymer is (5-15): 1, reacting for 20-100 h at 30-100 ℃; after the reaction is finished, pouring the reaction liquid into a precipitator, filtering, and washing the product with water to obtain the isatin arene copolymer with ammonium cations, wherein the structure of the isatin arene copolymer is shown as a general formula II:

wherein n is more than 0 and less than 1; x ^- Is a counter ion of Br ^- Or OH ^- Ions; r is ₁ Is C ₁ ～C ₁₂ Alkyl groups of (a);

the solvent A is one or a mixture of more than two of N, N-dimethylacetamide, N-dimethylformamide, chloroform, dimethyl sulfoxide and N-methylpyrrolidone;

the precipitant is one or more of methanol, ethanol, water, petroleum ether, ethyl acetate, acetone, and diethyl ether;

step (2) preparation of electrolyte solution of isatin arene copolymer with ammonium cation

Adding the isatin arene copolymer with ammonium cations prepared in the step (1) into a solvent A, stirring for dissolving, and defoaming to obtain a transparent and uniform electrolyte solution, wherein the concentration of the solution is determined according to actual needs;

step (3), preparation of isatin arene copolymer anion exchange membrane

Spreading a membrane on the electrolyte solution with the concentration of 3-15 wt% obtained in the step (2), immersing the membrane into a 1M NaOH or KOH solution at the temperature of room temperature to 80 ℃ for ion exchange for 2-24 h, soaking the membrane in room temperature deionized water for 24-48 h, washing the membrane to be neutral, and drying the membrane to obtain an isatin arene copolymer anion exchange membrane; when the compound B for preparing the isatin arene copolymer is brominated alkane, brominated olefin, vinyl benzyl chloride or glycidyl acrylate GMA, adding a thermal initiator or a photoinitiator during film preparation to obtain the cross-linked isatin arene copolymer anionic film.

4. The method for preparing an anion exchange membrane from the isatin arene copolymer according to claim 3, wherein the electrolyte solution of the isatin arene copolymer with ammonium cations prepared in the step (2) is used as a resin binder in a fuel cell for preparing a membrane electrode.

5. The anion-exchange membrane prepared by the method of claim 3 is applied to fuel cells, flow batteries, electrolysis, electrodialysis or separation membranes.

6. A method for preparing a composite membrane by using the isatin arene copolymer prepared by the method of claim 2, which is characterized by comprising the following specific steps:

step (1), synthesis of isatin arene copolymer with ammonium cation

Dissolving isatin arene copolymer in solvent A to obtain 5-20 wt% solution, adding methyl iodide or bromoalkane R ₁ -Br, wherein, methyl iodide or R ₁ The molar ratio of-Br to isatin arene copolymer is (5-15): 1, reacting for 20-100 h at 30-100 ℃; after the reaction is finished, pouring the reaction liquid into a precipitator, filtering, washing the product with water to obtain the isatin arene copolymer with ammonium cations, wherein the structure of the isatin arene copolymer is shown as a general formula (II):

wherein n is more than 0 and less than 1; x ^- Is a counterion of Br ^- Or OH ^- Ions; r ₁ Is C ₁ ～C ₁₂ Alkyl groups of (a);

the solvent A is one or a mixture of more than two of N, N-dimethylacetamide, N-dimethylformamide, chloroform, dimethyl sulfoxide and N-methylpyrrolidone;

the precipitant is one or more of methanol, ethanol, water, petroleum ether, ethyl acetate, acetone, and diethyl ether;

step (2), preparation of isatin arene copolymer solution with ammonium cation

Adding the isatin arene copolymer with ammonium cations prepared in the step (1) into a solvent A, stirring and dissolving to prepare a 1-10 wt% solution, and defoaming to obtain a transparent and uniform isatin arene copolymer solution with ammonium cations;

step (3), preparation of composite film

Soaking the base membrane in ethanol at room temperature for 3-24 h, taking out and spreading the base membrane, uniformly dropwise adding a solvent A on the surface to soak the base membrane, casting the isatin aromatic hydrocarbon copolymer solution with ammonium cations prepared in the step (2) on the base membrane for self-leveling, and putting the base membrane into a drying oven to be dried to constant weight; and then, immersing the obtained base membrane into 1M NaOH at the room temperature of 80 ℃ for ion exchange for 2-24 h, placing the base membrane into deionized water at the room temperature for 24-48 h, taking out the base membrane, and drying the base membrane in vacuum to constant weight to obtain the isatin arene copolymer composite membrane.

7. The method for preparing the composite membrane by using the isatin arene copolymer according to claim 6, wherein the base membrane is a polytetrafluoroethylene or polyethylene microporous membrane, and the porosity is greater than 90%.

8. The composite membrane prepared by the method of claim 6 is applied to a fuel cell, a flow battery, electrolysis, electrodialysis or a separation membrane.

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