A large-area two-dimensional polymer nanosheet-based proton exchange membrane and a preparation method thereof

Abstract

The application discloses a large-area two-dimensional polymer (2DP) nanosheet matrix proton exchange membrane (PEM), which is prepared by using ionic 2DP nanosheets as a main membrane material, adding ionic polyelectrolyte as an intercalation agent, and then mixing and preparing the large-area PEM by a flow casting method. The 2DP nanosheet solution is synthesized by using a step-by-step single-phase polymerization method, and then the polyelectrolyte is dissolved in a suitable solvent, mixed with the 2DP nanosheet solution according to a certain proportion, and a 2DP-polyelectrolyte composite membrane is prepared by a flow casting method. The preparation method is simple, controllable and convenient to operate. The prepared large-area 2DP-polyelectrolyte composite PEM has large size (400cm 2 ), excellent stability and extremely high proton conduction capacity.

Description

Technical Field

[0001] This invention belongs to the field of membrane preparation technology, and specifically relates to a large-area two-dimensional polymer nanosheet matrix sub-exchange membrane and its preparation method. Background Technology

[0002] In recent years, ionic two-dimensional polymer (2DP) nanosheets with unique structural and functional properties have provided a novel material platform for the fabrication of high-performance membranes. For example, solution-processable ultrathin 2DP nanosheets provide a new building block for the fabrication of novel proton exchange membranes (PEMs), which play a crucial role in various energy conversion devices (such as fuel cells and PEM water electrolysis) and determine their overall performance. Despite significant progress, the fabrication of continuous large-area ionic PEMs based on 2DP nanosheets has not yet been achieved, hindering their practical application.

[0003] Generally, fabricating large-area ionic 2DP nanosheet films while maintaining their integrity is quite challenging. On one hand, the inherent properties of ionic 2DP nanosheets can impose limitations on the assembly process. It is well known that the rigid structure of 2DP nanosheets makes them prone to cracking as the film area increases. Furthermore, the numerous covalently bonded ionic groups on the 2DP nanosheets generate electrostatic repulsion, reducing the interaction between adjacent 2DP nanosheets and leading to difficulties in assembling large-area films and instability in aqueous environments. On the other hand, most reported 2DP nanosheet-based films are prepared using vacuum-assisted self-assembly methods, which significantly limit the film size. Fortunately, the rapid development of layered films based on multifunctional two-dimensional nanosheets (such as graphene oxide and MXene) provides important insights. Intercalation strategies have proven to be effective methods for enhancing the interaction between adjacent two-dimensional nanosheets, further adjusting the physicochemical structure of layered films, and achieving ideal comprehensive performance. Therefore, constructing intercalated films holds promise for largely solving the aforementioned problems in the preparation of large-area ionic 2DP nanosheet films. The key to this method lies in screening or synthesizing suitable intercalating agents, which can enhance the interfacial interaction between adjacent nanosheets and make the membrane flexible, ultimately preparing a large-area 2DP-polyelectrolyte composite PEM with both high stability and excellent proton conductivity. Summary of the Invention

[0004] To address the shortcomings of the aforementioned background technology, this invention provides a method for preparing a large-area two-dimensional polymer nanosheet matrix proton exchange membrane, and the prepared 2DP-polyelectrolyte composite membrane possesses excellent proton conduction performance.

[0005] To address the aforementioned technical problems, this invention proposes a method for preparing a large-area two-dimensional polymer nanosheet matrix sub-exchange membrane, which involves the following steps:

[0006] Step 1, Preparation of ionic 2DP nanosheet solution: Weigh a certain amount of aldehyde monomer and amine monomer, wherein the molar ratio of aldehyde monomer to amine monomer is 1:1.5, then add a certain amount of solvent, stir at 25℃ for 24h, then add a certain amount of deionized water, stir until the solution is clear and transparent, and the resulting solution is denoted as solution A.

[0007] Step 2, Preparation of polyelectrolyte solution: Weigh the polyelectrolyte according to the mass ratio of polyelectrolyte to ionic 2DP nanosheet solution of 0.1 to 0.4:1, add it to a suitable solvent, and sonicate until completely dissolved. This solution is denoted as solution B.

[0008] Step 3: Preparation of large-area 2DP-polyelectrolyte composite membrane: Add solution B obtained in step 2 to solution A obtained in step 1, sonicate until mixed evenly, and record the mixed solution as solution C. Take 120 mL of solution C and drop it onto the mold, heat it at 60°C until completely dry, and a large-area 2DP-polyelectrolyte composite membrane attached to the glass substrate is obtained.

[0009] Step 4: Post-treatment of the large-area 2DP-polyelectrolyte composite membrane: The large-area 2DP-polyelectrolyte composite membrane attached to the glass substrate prepared in step 3 is first soaked in deionized water and peeled off from the glass substrate. Then, the self-supporting membrane is soaked in 1M H2SO4 solution for acidification for 24 hours. Then, the composite membrane is soaked in deionized water, and the water is changed until neutral, to obtain the self-supporting large-area 2DP-polyelectrolyte composite membrane.

[0010] Furthermore, in the preparation method described in this invention:

[0011] In step 1, the aldehyde monomer is any one of the following ternary aldehyde monomers: 1,3,5-tris(p-formylphenyl)benzene, 1,3,5-tris(3'-aldehyde-4'-hydroxybenzene), 1,3,5-tris(4'-aldehyde[1,1'-biphenyl]-4-yl)benzene, pyromellitic aldehyde, 2-hydroxy-1,3,5-benzenetricarboxaldehyde, 1,3-dihydroxy-2,4,6-trialdehydebenzene, trialdehyde-resorcinol, 1,3,5-trimethoxy-2,4,6-triformylbenzene, and 2,4,6-trichloro-1,3,5-benzenetricarboxaldehyde.

[0012] In step 1, the amine monomer includes any one of the following diamine monomers: 2,5-diaminobenzenesulfonic acid, p-phenylenediamine-2,5-disulfonic acid, 2,5-diaminobenzoic acid, 2,5-diaminoterephthalic acid, 2,2'-benzidine disulfonic acid, 4,4'-diamino-3,3'-biphenyl disulfonic acid, and 4,4'-diaminostilbene-2,2'-disulfonic acid.

[0013] In steps 1 and 2, the solvent includes any one of dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and deionized water.

[0014] In step 2, the mass ratio of the polyelectrolyte to the ionic covalent organic polymer is preferably 0.1-0.4.

[0015] In step 3, the ultrasonic time for the mixed solution is 10-20 minutes; the mold used is a glass plate of 20×20cm or larger.

[0016] The large-area 2DP-polyelectrolyte composite membrane of the present invention exhibits a proton conductivity of 802 mS / cm under conditions of 70°C and 95% relative humidity. -1 .

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] This invention employs an intercalation method, using ionic 2DP nanosheets as the main film material and adding an ionic polyelectrolyte as an intercalation agent. After thorough mixing, a large-area PEM is prepared by casting. This preparation method is convenient, simple, controllable, and easy to operate. The prepared large-area 2DP-polyelectrolyte composite PEM has a large size (400 cm²). 2 It has excellent stability and extremely high proton conduction ability. Attached Figure Description

[0019] Figure 1 This is a scanning electron microscope (SEM) image of the large-area 2DP-polyelectrolyte composite membrane from Example 1.

[0020] Figure 2 This is a scanning electron microscope cross-sectional image of the large-area 2DP-polyelectrolyte composite membrane of Example 1.

[0021] Figure 3 The graph shows the proton conductivity of the large-area 2DP-polyelectrolyte composite membrane in Example 1 at different temperatures.

[0022] Figure 4 This is a schematic diagram of the process for preparing a large-area 2DP-polyelectrolyte composite membrane in Example 1. Detailed Implementation

[0023] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. However, the following examples are for illustrative purposes only and should not be considered as any limitation on the present invention.

[0024] The preparation method of the large-area two-dimensional polymer nanosheet matrix proton exchange membrane of the present invention is carried out as follows: using 2DP nanosheets as the main body, adding polyelectrolytes as intercalating agents, and preparing the membrane by casting after thorough mixing. The preparation process mainly includes: preparation of ionic 2DP nanosheet solution, preparation of polyelectrolyte solution, preparation of large-area 2DP-polyelectrolyte composite membrane, and post-treatment of the composite membrane. In this invention, the polyelectrolyte intercalation method is used to enhance the multiple interactions between the polyelectrolyte and the 2DP nanosheets and further increase the content of conductive groups within the membrane, thereby improving the mechanical properties and proton conductivity of the membrane. The preparation method of this invention is mild, controllable, simple, and easily scaled up. The prepared composite membrane has good stability and excellent proton conductivity, which is beneficial for its application in fuel cells. Example 1

[0025] A method for preparing a large-area two-dimensional polymer nanosheet matrix sub-exchange membrane, comprising the following steps:

[0026] Step 1: Preparation of ionic 2DP nanosheet solution: Weigh 563.4 mg of trialdehyde phloroglucinol and 1821.6 mg of 2,2'-benzidine disulfonic acid, wherein the molar ratio of trialdehyde phloroglucinol to 2,2'-benzidine disulfonic acid is 1:1.5. Then add 180 mL of dimethyl sulfoxide, stir at 25 °C for 24 hours, then add 36 mL of deionized water, and stir for 24 hours until the solution is clear and transparent to obtain ionic 2DP nanosheet solution.

[0027] Step 2, Preparation of polyelectrolyte solution: Weigh 87.6 mg of sodium poly(p-styrene sulfonate) according to the optimal mass ratio of sodium poly(p-styrene sulfonate) to ionic covalent organic polymer of 0.3:1, add it to 96 mL of deionized water, and sonicate until completely dissolved to obtain polyelectrolyte solution.

[0028] Step 3: Add the polyelectrolyte solution obtained in Step 2 to the ionic 2DP nanosheet solution obtained in Step 1, mix them at a volume ratio of 4:1, and sonicate for 12 minutes until fully mixed. The resulting solution is denoted as solution C. Take 120 mL of solution C and drop it onto a 20×20 cm square glass plate. Heat in a 60℃ oven for 36 hours until completely dry to obtain a large-area 2DP-polyelectrolyte composite film attached to a glass substrate. Its cross-section is shown in Figure 1. Figure 2 As shown, the surface is as Figure 1 As shown.

[0029] Step 4: The large-area 2DP-polyelectrolyte composite membrane attached to the glass substrate prepared in step 3 is first soaked in deionized water and peeled off from the glass substrate. Then, the self-supporting membrane is soaked in 1M H2SO4 solution for acidification for 24 hours. Then, the composite membrane is soaked in deionized water for 48 hours, changing the water until it is neutral, to obtain the self-supporting large-area 2DP-polyelectrolyte composite membrane.

[0030] The proton conductivity of a large-area 2DP-polyelectrolyte composite membrane was tested using an electrochemical workstation. At 70℃ and 95% relative humidity, the proton conductivity was 802 mS / cm. -1 ,like Figure 3 As shown. Example 2

[0031] The preparation process of a large-area two-dimensional polymer nanosheet matrix sub-exchange membrane is basically the same as that in Example 1, with the only difference being:

[0032] In step 3, 3g of sulfonated polyethersulfone was weighed and added to 45mL of dimethyl sulfoxide. After ultrasonic dissolution, solution D was obtained. Then, solution D was added to solution C obtained in step 3 at a 1:1 volume ratio, and the mixture was ultrasonically mixed for 10min. Subsequently, the mixed solution was dropped onto a 20×20cm square glass plate and dried in a 60℃ oven to obtain a large-area 2DP-polyelectrolyte composite membrane attached to a glass substrate.

[0033] In summary, this invention provides a large-area 2DP nanosheet matrix proton exchange membrane (PEM) using ionic 2DP nanosheets as the main membrane material and adding ionic polyelectrolytes as intercalating agents. After thorough mixing, a large-area PEM is prepared by a casting method. The preparation method of this invention is mild, controllable, simple, and easily scaled up. The prepared large-area 2DP nanosheet matrix PEM exhibits excellent stability and proton conductivity, with a proton conductivity of 802 mS / cm at 70°C and 95% relative humidity. -1 .

[0034] Although the present invention has been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many modifications under the guidance of the present invention without departing from the spirit of the present invention, and these modifications are all within the protection scope of the present invention.

Claims

1. A method for preparing a large-area two-dimensional polymer nanosheet matrix sub-exchange membrane, characterized in that, The nanosheets were used as the main body, and a polyelectrolyte was added as an intercalating agent. After thorough mixing, the nanosheets were prepared by casting. Details are as follows: First, ionic 2DP nanosheet solutions were synthesized using aldehyde monomers and amine monomers as raw materials via a stepwise single-phase polymerization method. Then, polyelectrolytes were dissolved in an appropriate amount of solvent and thoroughly mixed with the above ionic 2DP nanosheet solutions in a certain volume ratio. Finally, 2DP-polyelectrolyte composite membranes were prepared by casting.

2. The method for preparing a large-area two-dimensional polymer nanosheet matrix sub-exchange membrane according to claim 1, characterized in that, The aldehyde monomer includes one of 1,3,5-tris(p-formylphenyl)benzene, 1,3,5-tris(3'-aldehyde-4'-hydroxybenzene)benzene, 1,3,5-tris(4'-aldehyde[1,1'-biphenyl]-4-yl)benzene, pyromellitic methylformaldehyde, 2-hydroxy-1,3,5-benzenetriformaldehyde, 1,3-dihydroxy-2,4,6-trialdehydebenzene, trialdehyde-phloroglucinol, 1,3,5-trimethoxy-2,4,6-triformylbenzene, and 2,4,6-trichloro-1,3,5-benzenetriformaldehyde.

3. The method for preparing a large-area two-dimensional polymer nanosheet matrix sub-exchange membrane according to claim 1, characterized in that, The amine monomer includes one of 2,5-diaminobenzenesulfonic acid, p-phenylenediamine-2,5-disulfonic acid, 2,5-diaminobenzoic acid, 2,5-diaminoterephthalic acid, 2,2'-benzidine disulfonic acid, 4,4'-diamino-3,3'-biphenyl disulfonic acid, and 4,4'-diaminostilbene-2,2'-disulfonic acid.

4. The method for preparing a large-area two-dimensional polymer nanosheet matrix sub-exchange membrane according to claim 1, characterized in that, The polyelectrolyte is one or more of the following: sodium poly(p-styrene sulfonate), sulfonated polyethersulfone, sulfonated polyether ether ketone, sulfonated polybenzimidazole, sulfonated polyimide, sulfonated polyvinyl alcohol, and perfluorosulfonic acid.

5. The method for preparing a large-area two-dimensional polymer nanosheet matrix sub-exchange membrane according to claim 1, characterized in that, Specifically, the steps include the following: Step 1, Preparation of ionic 2DP nanosheet solution: Weigh a certain amount of aldehyde monomer and amine monomer, wherein the molar ratio of aldehyde monomer to amine monomer is 1:1.5, then add a certain amount of solvent, stir at 25℃ for 24h, then add a certain amount of deionized water, stir until the solution is clear and transparent, and the resulting solution is denoted as solution A. Step 2, Preparation of polyelectrolyte solution: Weigh the polyelectrolyte according to the mass ratio of polyelectrolyte to ionic 2DP nanosheet solution of 0.1 to 0.4:1, add it to a suitable solvent, and sonicate until completely dissolved. This solution is denoted as solution B. Step 3: Preparation of large-area 2DP-polyelectrolyte composite membrane: Add solution B obtained in step 2 to solution A obtained in step 1, sonicate until mixed evenly, and record the mixed solution as solution C. Take 120 mL of solution C and drop it onto a glass mold, heat it at 60°C until completely dry, and a large-area 2DP-polyelectrolyte composite membrane attached to the glass substrate is obtained. Step 4: Post-treatment of the large-area 2DP-polyelectrolyte composite membrane: The large-area 2DP-polyelectrolyte composite membrane attached to the glass substrate prepared in step 3 is first soaked in deionized water and peeled off from the glass substrate. Then, the self-supporting membrane is soaked in 1M H2SO4 solution for acidification for 24 hours. Then, the composite membrane is soaked in deionized water, and the water is changed until neutral, to obtain the self-supporting large-area 2DP-polyelectrolyte composite membrane.

6. The method for preparing a large-area two-dimensional polymer nanosheet matrix sub-exchange membrane according to claim 5, characterized in that, In steps 1 and 2, the solvent includes one or more of dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, and deionized water.

7. The method for preparing a large-area two-dimensional polymer nanosheet matrix sub-exchange membrane according to claim 5, characterized in that, In step 2, the ultrasonic time for the mixed solution is 10-20 min.

8. The method for preparing a large-area two-dimensional polymer nanosheet matrix sub-exchange membrane according to claim 5, characterized in that, The glass mold mentioned in step 3 is a glass plate with a size of 20×20cm or larger.

9. A large-area two-dimensional polymer nanosheet matrix exchange membrane, characterized in that... Prepared using any one of the preparation methods described in claims 1-8.

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