A hollow nanostructure-enhanced ion exchange membrane and its preparation method

Abstract

This invention discloses a hollow nanostructure-enhanced ion exchange membrane and its preparation method. The ion exchange membrane is composed of a polymer resin and a hollow nanostructure. The hollow nanostructure is a precursor rich in terminal alkynes that polymerizes under a template. After polymerization, the template is removed to obtain the membrane. The hollow nanostructure is dispersed in a polymer resin solution, and the membrane-forming solution is cast into a membrane-forming mold. The solvent is removed by heat treatment to form the membrane material. The synthesis conditions of this invention are mild, the process is simple, and it can be prepared on a large scale. The hollow nanostructure can increase the water content of the membrane and reduce membrane swelling during application, thereby improving the ion conductivity. It possesses high ionic conductivity, high mechanical strength, low swelling performance, and low gas permeation, and can be applied to systems requiring rapid ion conduction, such as hydrogen-oxygen fuel cells, direct alcohol fuel cells, water electrolysis, flow batteries, chlor-alkali industry, and water treatment.

Description

Technical Field

[0001] This invention relates to the field of ion exchange membrane technology, and more specifically to a hollow nanostructure-enhanced ion exchange membrane and its preparation method. Background Technology

[0002] Ion exchange membranes, including anion exchange membranes and cation exchange membranes, are key materials in devices for producing green hydrogen through water electrolysis, green hydrogen applications in fuel cells, water treatment, flow batteries, chlor-alkali industries, and high-value carbon dioxide reduction. Ion exchange membranes with high stability, high ion conductivity, and low permeation of active substances can improve the power performance, energy efficiency, and lifespan of devices, while reducing equipment costs. Currently, ion exchange membranes still face problems such as poor membrane stability, severe swelling, significant permeation of active substances, and insufficient ion conductivity, requiring the development of new concepts to address these issues.

[0003] Developing thin films is the main method to improve the ionic conductivity of membranes, but thin films face problems such as high processing and preparation difficulty, poor mechanical stability, serious permeation of active materials, and insufficient service life. For example, in fuel cells and water electrolysis systems, ultrathin ion exchange membranes cannot solve the problem of hydrogen cross-permeation, which seriously affects the safety of device use; corresponding to flow battery systems, the cross-permeation of active ions affects the energy utilization efficiency and device life.

[0004] By enhancing ion exchange membranes with hollow structures, the water content of the membrane can be significantly increased without altering the ion exchange degree of the ion exchange resin. This reduces the cost of ion exchange resin usage, improves ionic conductivity, decreases membrane swelling rate, and enhances membrane stability. Simultaneously, the mechanical stability of the ion exchange membrane is improved through the mechanical stability of the hollow structure. The resulting hollow-structure-reinforced ion exchange membrane exhibits better mechanical properties and active material permeation inhibition, allowing for the development of ion exchange membrane materials with superior mechanical properties, lower swelling, stronger ion conductivity, lower active material permeation, and easier processing. Summary of the Invention

[0005] In view of this, the present invention provides a hollow nanostructure-enhanced ion exchange membrane and its preparation method, aiming to reduce the swelling rate of the membrane, increase the water content of the membrane, improve the mechanical stability of the membrane, suppress the cross-permeation problem of active substances in the membrane, and obtain a low-cost, high-power, high-efficiency, and highly stable ion exchange membrane material.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] First, this invention provides a method for preparing a hollow nanostructure-enhanced ion exchange membrane, comprising the following steps:

[0008] (1) The alkynyl coupling reaction was carried out with the terminal alkynyl precursor under the action of the sacrificial template agent, and the sacrificial template agent was removed to obtain hollow nanostructure powder.

[0009] (2) Dissolve the ion exchange resin and hollow nanostructure powder in a solvent in a certain proportion and stir evenly to obtain the casting solution;

[0010] (3) The casting liquid from step (2) is poured into a mold and heat-treated to remove the solvent to obtain a hollow nanostructure-enhanced ion exchange membrane material.

[0011] Preferably, the structure of the terminal-rich alkyne precursor in step (1) is as follows:

[0012] ;

[0013] Wherein, A is a terminal alkyne bond, n≥1, preferably greater than 2; B is an aromatic ring or amine; C is one or more of sulfonate, phosphate, and ammonium functional groups, m≥1.

[0014] Furthermore, the terminal-rich alkyne precursor is selected from one or more of the following structures:

[0015] , , , , , , , , , , .

[0016] Preferably, the sacrificial template agent is one or more of copper nanoparticles, copper sulfate nanoparticles, copper acetate nanoparticles, and copper hydroxide nanoparticles, and the particle size of the sacrificial template agent is 20 nm-1 µm, preferably 200-200 nm.

[0017] Preferably, the solvent for the acetylene coupling reaction in step (1) is a combination of at least one of the nitrogen-containing basic solvents selected from pyridine, triethylamine, diisopropylamine, and tetramethylethylenediamine, and at least one of the solvents selected from toluene, dichloromethane, chloroform, ethyl acetate, and N,N-dimethylformamide.

[0018] By volume, the volume of nitrogen-containing alkaline solvent should not be less than 5%, with an optimal value of 10%-20%;

[0019] The mass ratio of the sacrificial template agent to the terminal alkyne precursor is (10-30):(0.3-4); the reaction temperature is 25-120℃, preferably 30-60℃, and the reaction time is <48h.

[0020] Preferably, in step (1), an aqueous solution of hydrochloric acid or sulfuric acid is used to remove the sacrificial template agent.

[0021] Preferably, the ion exchange resin in step (2) is one or a combination of the following structures.

[0022] , , , , , , , .

[0023] Preferably, the hollow nanostructure powder in step (2) is 1%-60% of the mass of the ion exchange resin, preferably 5%-20%, and the solvent is one or more of N,N-dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone and water, with no volume limit.

[0024] Preferably, the heat treatment temperature in step (3) is 50℃-120℃, more preferably 60℃-80℃, and the treatment time is <12h, more preferably 30min-2h.

[0025] In addition, the present invention provides a hollow nanostructure-enhanced ion exchange membrane prepared by the method described above.

[0026] As can be seen from the above technical solution, compared with the prior art, the present invention discloses a hollow nanostructure-enhanced ion exchange membrane and its preparation method, which has the following beneficial effects:

[0027] This invention utilizes the water storage function of hollow nanostructures to increase the water content of ion exchange membranes, reduce the membrane swelling rate, shorten the ion transport distance in the resin phase, and increase the ion transport rate. The mechanical properties of the membranes are also improved by utilizing the mechanical properties of hollow nanostructures.

[0028] The hollow nanostructure-enhanced ion exchange membrane obtained by this invention can be prepared on a large scale under mild conditions and with a simple process, and can be applied to a variety of scenarios. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0030] Figure 1This is a cross-sectional morphology diagram of the hollow nanostructure-enhanced ion exchange membrane prepared in Example 2 of the present invention;

[0031] Figure 2 This is a cross-sectional morphology diagram of the hollow nanostructure-enhanced ion exchange membrane prepared in Example 3 of the present invention. Detailed Implementation

[0032] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0033] Example 1

[0034] (1) Add 10 g of 50 nm copper nanoparticles to the terminal-rich yne precursor. (0.5g) and (2g) was added to 400mL of tetramethylethylenediamine / N,N-dimethylformamide (volume ratio 1:10) solution and reacted at 90℃ for 7h. After the reaction was stopped, the insoluble matter was obtained by filtration. After drying, the insoluble matter was added to a 3% hydrochloric acid aqueous solution to remove copper nanoparticles. After centrifugation, washing and drying, hollow nanostructure powder was obtained.

[0035] (2) Mix 100 mg of the obtained hollow nanostructure powder with 500 mg Disperse the solution in 10 mL of dimethyl sulfoxide solvent and stir until homogeneous to obtain the casting solution;

[0036] (3) The casting liquid obtained in step (2) is cast into the film forming mold and dried at 80°C to remove the solvent for 1 hour to obtain the film material.

[0037] Comparative Example 1

[0038] Preparation of membrane materials without adding hollow nanostructure powder:

[0039] 500mg The casting solution dispersed in 10 mL of dimethyl sulfoxide solvent was cast into a film-forming mold, dried at 80°C to remove the solvent, and dried for 1 hour to obtain the membrane material.

[0040] Compared with Comparative Example 1, Example 1 showed that the swelling of the membrane was reduced by 5%, the water absorption rate of the membrane was the same, the mechanical strength of the membrane increased by 20% to 40 MPa, and the proton conductivity increased by 15%.

[0041] Example 2

[0042] (1) Add 5g of copper hydroxide nanoparticles with a particle size of 20nm to the terminal-rich yne precursor. (100mg) and 100 mg of copper hydroxide nanoparticles were added to 300 mL of pyridine / dichloromethane solution (volume ratio 1:5) and reacted at 40 °C for 10 h. After the reaction was stopped, the insoluble matter was obtained by filtration. After drying, the insoluble matter was added to a 2% sulfuric acid aqueous solution to remove copper hydroxide nanoparticles. After centrifugation, washing and drying, hollow nanostructured powder was obtained.

[0043] (2) Mix 100 mg of the obtained hollow nanostructured powder with 600 mg of Disperse the solution in 15 mL of N,N-dimethylformamide and stir until homogeneous to obtain the casting solution;

[0044] (3) The casting liquid obtained in step (2) is cast into the film forming mold and dried at 60°C to remove the solvent for 3 hours to obtain the film material.

[0045] Figure 1 The image shows a cross-sectional area scanning electron microscope image of the hollow structure-enhanced ion exchange membrane prepared in this embodiment. The membrane contains a large number of hollow structures, which can increase the water retention capacity of the membrane, improve the mechanical strength of the membrane, and reduce the swelling of the membrane.

[0046] Comparative Example 2

[0047] 100 mg of the obtained hollow nanostructure powder was mixed with 600 mg The solution was dispersed in 15 mL of N,N-dimethylformamide and stirred until homogeneous to obtain a casting solution. The solution was then cast into a film-forming mold and dried at 60 °C for 3 hours to remove the solvent, thus obtaining the membrane material.

[0048] Compared with the membrane material prepared in Comparative Example 2, the water absorption rate of the membrane in Example 2 increased by 20%, but the swelling of the membrane remained unchanged. The mechanical strength of the membrane increased by 30%, reaching 35 MPa, and the proton conductivity increased by 20%.

[0049] Example 3

[0050] (1) Add 10 g of copper acetate nanoparticles with a particle size of 500 nm to the terminal-rich alkyne precursor. (100mg) and (200 mg) was added to 500 mL of diisopropylamine / toluene (volume ratio 1:1) solution and reacted at 70 °C for 5 h. After the reaction was stopped, the insoluble matter was obtained by filtration. After drying, the insoluble matter was added to an aqueous solution of 1% hydrochloric acid to remove copper acetate nanoparticles. After centrifugation, washing and drying, hollow nanostructured powder was obtained.

[0051] (2) Mix 200 mg of the obtained hollow nanostructured powder with 1500 mg of Disperse the solution in 20 mL of N-methylpyrrolidone and stir until homogeneous to obtain the casting solution;

[0052] (3) The casting liquid obtained in step (2) is cast into the film forming mold and dried at 70°C to remove the solvent for 2 hours to obtain the film material.

[0053] Figure 2 The cross-sectional area scanning electron microscope image of the hollow structure-enhanced ion exchange membrane prepared for this embodiment clearly shows that the membrane contains a large number of hollow structures, indicating that the designed structure was successfully obtained. The hollow structure can increase the water retention capacity of the membrane and improve the ion transport rate of the membrane.

[0054] Comparative Example 3

[0055] 200 mg of the obtained hollow nanostructure powder was mixed with 1500 mg The solution was dispersed in 20 mL of N-methylpyrrolidone and stirred until homogeneous to obtain a casting solution. The solution was then poured into a film-forming mold and dried at 70 °C for 2 hours to remove the solvent, thus obtaining the membrane material.

[0056] Compared with the membrane material prepared in Comparative Example 3, the water absorption rate of the membrane in Example 3 increased by 30%, the swelling decreased by 5%, the mechanical strength of the membrane increased by 30% to 50 MPa, and the proton conductivity increased by 15%.

[0057] The various embodiments described in this specification are presented in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing a hollow nanostructure-reinforced ion exchange membrane, characterized by, The method comprises the following steps: (1) performing acetylene-acetylene coupling reaction under the action of a sacrificial template, removing the sacrificial template, and obtaining hollow nano-structure powder; (2) stirring the ion exchange resin and the hollow nano-structure powder in a solvent in a certain proportion to obtain a casting solution; (3) casting the casting solution of step (2) into a mold, and removing the solvent by heat treatment to obtain a hollow nano-structure reinforced ion exchange membrane material; The end-rich acetylene precursor is selected from one or more of the following structures: 、 、 、 、 、 、 、 、 、 、 。 2. The method of claim 1, wherein the hollow nanostructure reinforced ion exchange membrane is prepared by the steps of: The sacrificial template is one or more of copper nanoparticles, copper sulfate nanoparticles, copper acetate nanoparticles, and copper hydroxide nanoparticles, and the particle size of the sacrificial template is 20 nm-1 µm.

3. The method for preparing a hollow nanostructure-reinforced ion exchange membrane according to claim 1, characterized in that, The acetylene-acetylene coupling reaction solvent in step (1) is a combination of at least one of pyridine, triethylamine, diisopropylamine, and tetramethyl ethylenediamine nitrogen-containing alkaline solvent and at least one of toluene, dichloromethane, trichloromethane, ethyl acetate, and N,N-dimethylformamide solvent. The mass ratio of the sacrificial template to the end-rich acetylene precursor is (10-30):(0.3-4), the reaction temperature is 25-120°C, and the reaction time is <48 h.

4. The method for preparing a hollow nanostructure-reinforced ion exchange membrane according to claim 1, characterized in that, In step (1), hydrochloric acid or sulfuric acid aqueous solution is used to remove the sacrificial template.

5. The method for preparing a hollow nanostructure-reinforced ion exchange membrane according to claim 1, characterized in that, The ion exchange resin in step (2) is a combination of one or more of the following structures 、 、 、 、 、 、 、 。 6. The method for preparing a hollow nanostructure-reinforced ion exchange membrane according to claim 1, characterized in that, In step (2), the hollow nano-structure powder is 1%-60% of the mass of the ion exchange resin, and the solvent is a mixture of one or more of N,N-dimethylformamide, dimethyl sulfoxide, and N-methyl pyrrolidone.

7. The method for preparing a hollow nanostructure-reinforced ion exchange membrane according to claim 1, characterized in that, In step (3), the heat treatment temperature is 50°C-120°C, and the treatment time is <12 h.

8. A hollow nano-structure reinforced ion exchange membrane prepared by the method of any one of claims 1-7.

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