Composite proton exchange membrane as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of proton exchange membranes, and particularly relates to a composite proton exchange membrane and a preparation method and application thereof. The composite proton exchange membrane is characterized by comprising the following raw materials: iHOF, sulfonated polyarylene ether nitrile and a solvent, and the mass ratio of the iHOF to the sulfonated polyarylene ether nitrile is (3-9): 100. The composite proton exchange membrane provided by the invention has good proton conductivity and chemical stability, and the preparation method is simple.

Description

Technical Field

[0001] The present invention belongs to the technical field of proton exchange membranes, and in particular relates to a composite proton exchange membrane and a preparation method and application thereof. Background Art

[0002] Proton exchange membranes (PEMs) have important applications in fuel cells, water electrolysis, and other fields, where their performance directly impacts the efficiency and stability of these devices. While common PEM materials, such as perfluorosulfonic acid (PFSA) membranes, offer good chemical stability and mechanical properties, they suffer from high costs and require improved proton conductivity. While non-fluorinated PEM materials offer certain cost advantages, their overall performance lags behind that of PFSA membranes. For example, proton conductivity decreases significantly under high-temperature, low-humidity conditions, and their chemical stability is insufficient, limiting their widespread application.

[0003] The compounding of polymers and inorganic fillers has always been a thorny issue, particularly regarding their compatibility. Due to challenges with interfacial compatibility, inorganic fillers are often difficult to evenly disperse within polymers. This is due to significant differences between polymers and inorganic fillers in several aspects. In terms of surface properties, polymers generally possess an organic and flexible molecular structure with low surface energy, resulting in hydrophobicity. Inorganic fillers, on the other hand, typically have higher surface energy, are more active, and are often hydrophilic. This significant difference in surface properties makes it difficult for the two to form a good physical bond and interaction. Molecularly, the polymer's molecular chains are highly flexible and deformable, while the inorganic filler's crystalline or amorphous structure is relatively rigid. This mismatch makes it difficult for the two to coordinate under load, leading to interfacial debonding. Regarding polarity, polymers are less polar, while inorganic fillers are more polar. Based on the principle of "like dissolves like," this polarity difference prevents them from interpenetrating and evenly dispersing when mixed. Inorganic fillers are prone to agglomeration, making uniform distribution at the nanometer or micrometer scale difficult within the polymer matrix.

[0004] These problems can lead to a number of adverse effects. In terms of performance, uneven dispersion of inorganic fillers can prevent the effective improvement of the mechanical properties of composite materials, such as strength and toughness, and may even result in localized weak areas.

[0005] As reported in the literature Xiang-Tian Bai, Li-Hui Cao, Xu-Yong Chen, Shu-Hui Li, Jia-Hao Zhang, Dimethylamine-tuned guanidinium arylphosphonate iHOFs and superprotonicconduction Nafion hybrid membranes for DMFCs, Chemical Engineering Journal, Volume 487, 2024, 150747, the preparation of a proton exchange membrane (PEMs) with excellent electrical conductivity and low methanol permeability is crucial for the further development of high-performance direct methanol fuel cells (DMFCs). In this study, two ionic hydrogen-bonded organic frameworks (iHOF-14 and iHOF-15) were obtained from 1,3,5-tris(4-phenylphosphate)benzene and guanidine hydrochloride under the control of dimethylamine cations. Due to the rich hydrogen bond network, iHOF-14 and iHOF-15 exhibited good proton conductivity, exceeding 10 -2 Scm -1 In addition, the study doped iHOF into the Nafion matrix to obtain PEMs with richer proton transfer pathways and good methanol barrier properties. However, its mechanical properties were poor.

[0006] For example, Chinese patent CN115044057A discloses a benzenesulfonic acid-based ionic hydrogen-bonded organic framework material with the chemical formula: {L·(DBPy)·3(H2O)} n , where n is a positive integer, L is 7-amino-1,3-naphthalene disulfonic acid anion, and the chemical formula is {C10 H7 NO6 S2} 2- ; DBPy is 1,1'-diamino-4,4'-bipyridinium cation, with the chemical formula {C10 H12 N4} 2+ The structural unit belongs to the orthorhombic system, the space group is Pna21, and the molecular formula is C 20 H 25 N5O9S2, each repeating unit consists of an L 2- , a DBPy 2+ and three water molecules; DBPy 2+ The amino group, L 2- The sulfonic acid groups on the sulfonic acid and free water molecules form a three-dimensional hydrogen bond network. The invention discloses a preparation method thereof, the raw materials are readily available, the preparation process is simple, and it has a good application prospect in proton conducting materials. This invention also has the above-mentioned problems.

[0007] Therefore, there is an urgent need to develop a proton exchange membrane with good mechanical properties. Summary of the Invention

[0008] Based on the deficiencies of the prior art, the present invention provides a composite proton exchange membrane and its preparation method and application. The composite proton exchange membrane provided by the present invention has good proton conductivity and chemical stability, and the preparation method is simple.

[0009] To achieve the above object, the present invention adopts the following technical solutions:

[0010] In a first aspect, the present invention provides a composite proton exchange membrane comprising the following raw materials: iHOF and sulfonated poly (arylene ether nitrile) (SPEN).

[0011] Preferably, the mass ratio of the iHOF to the sulfonated poly(arylene ether nitrile) is 3-9:100.

[0012] More preferably, the mass ratio of the iHOF to the sulfonated poly(arylene ether nitrile) is 9:100.

[0013] Preferably, the solvent is selected from one of isopropyl alcohol, N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAC), and dimethyl sulfoxide (DMSO).

[0014] In a second aspect, the present invention further provides a method for preparing a composite proton exchange membrane, wherein the preparation method is a solution blending method.

[0015] Preferably, the solution blending method comprises the following steps:

[0016] The iHOF and sulfonated poly(arylene ether nitrile) in a prescribed amount are dissolved in a solvent, the two solutions are then mixed, and ultrasonically treated with stirring at 100-150°C for 12-14 hours to fully mix the sulfonated poly(arylene ether nitrile) and the iHOF. The mixed solution is then poured into a glass mold and dried to obtain a composite membrane. The composite membrane is then immersed in 3-5% by mass H2O2 at 80-100°C for 1 hour, then immersed in deionized water for half an hour, and then immersed in a 1-1.5M acid solution at 80-100°C for 1 hour, washed with deionized water, and dried to obtain the composite proton exchange membrane.

[0017] Preferably, the acid is selected from sulfuric acid, nitric acid or hydrochloric acid.

[0018] As a preferred embodiment, the solution blending method comprises the following steps:

[0019] Take the formulated amount of iHOF and sulfonated polyarylether nitrile and dissolve them in isopropanol respectively, then mix the two solutions, stir and ultrasonically treat at 100°C for 12 hours to fully mix the sulfonated polyarylether nitrile and iHOF; then pour the mixed solution into a glass mold and dry it to obtain a composite membrane; then soak the composite membrane in 3% H2O2 by mass at 80°C for 1 hour, then soak it in deionized water for half an hour, and then soak it in 1M H2SO4 solution at 80°C for 1 hour, wash it with deionized water, and dry it to obtain the composite proton exchange membrane.

[0020] The present invention also provides a method for preparing iHOF, comprising the following steps: completely dissolving 1,3,5-tris(4-phosphinophenyl)benzene (16.38 mg, 0.03 mmol) (CAS: 1045720-71-5, purchased from Bidex Pharmaceuticals Co., Ltd.) in 1.5 ml of H2O, and dissolving guanidine hydrochloride (38.48 mg, 0.45 mmol) (CAS: 50-01-1, purchased from Aladdin) in 1.5 ml of methanol. The two solutions are then uniformly mixed and allowed to stand at room temperature for 5 days to obtain colorless, transparent polyhedral crystals, iHOF.

[0021] The present invention also provides a method for preparing sulfonated poly(arylene ether nitrile), comprising the following steps: adding biphenol (BP), potassium 2,5-dihydroxybenzenesulfonate (SHQ), anhydrous potassium carbonate (K2CO3), and 2,6-difluorobenzonitrile (DFBN) to a reaction apparatus equipped with a condensation and water separation unit, and dissolving them in N-methylpyrrolidone and toluene. Stirring is initiated and the mixture is heated to 130-140°C. The reaction system begins to boil and generate bubbles, and reflux and dehydration gradually occur. After the dehydration reaction continues for a certain period of time, water is released from the water separator and the temperature is raised to 170-180°C. The reaction continues at this temperature for a certain period of time, while excess water is released, and the temperature is further raised to 190-200°C. The reaction is terminated when the viscosity of the solution in the reaction system no longer increases. The product is slowly poured into anhydrous ethanol with an appropriate amount of hydrochloric acid for precipitation. The product is then crushed into a powder using a grinder, washed with water multiple times, purified with a dilute hydrochloric acid solution 3-5 times, and dried to obtain the sulfonated poly(arylene ether nitrile).

[0022] Preferably, the molar ratio of 2,6-difluorobenzonitrile (DFBN), potassium 2,5-dihydroxybenzenesulfonate (SHQ), biphenol (BP) and anhydrous potassium carbonate (K2CO3) is 1:0.7:0.3:1-2.

[0023] The sulfonated polyarylether nitrile synthesis process is as follows:

[0024]

[0025] Wherein, HO-Ar-OH includes but is not limited to catechol, resorcinol, hydroquinone, and bisphenol A;

[0026] 2,6-Difluorobenzonitrile can also be replaced by 2,6-dichlorobenzene.

[0027] Preferably, the structure of the sulfonated poly (arylene ether nitrile) is:

[0028]

[0029] Wherein, n=0.3, 0.4, 0.5 or 0.6.

[0030] In a fourth aspect, the present invention also provides the use of the composite proton exchange membrane in water electrolysis.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] (1) The present invention has higher proton conductivity by compounding iHOF and sulfonated polyarylethernitrile, which can effectively improve the efficiency of water electrolysis.

[0033] (2) The composite proton exchange membrane prepared by the present invention has better chemical stability, can maintain stable performance in harsh chemical environments, and extend the service life of the proton exchange membrane.

[0034] (3) The composite proton exchange membrane prepared by the present invention has better mechanical properties, can withstand greater stress and strain, and improves the reliability and stability of the membrane.

[0035] (4) The composite proton exchange membrane prepared by the present invention has lower cost and better economy and market competitiveness. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is described clearly and completely below with specific embodiments. Obviously, the embodiments described are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention. The materials, reagents, etc. used, unless otherwise specified, are reagents and materials available from commercial sources.

[0037] In the following examples, the sulfonated poly(arylene ether nitrile) used was prepared by the following method: 14.90 g of biphenyl diphenol, 27.39 g of potassium 2,5-dihydroxybenzenesulfonate, 38.7 g of anhydrous potassium carbonate, and 27.8 g of 2,6-difluorobenzonitrile were added to a reaction apparatus equipped with a condensation and water separation component, and 90 mL of N-methylpyrrolidone and 30 mL of toluene were added for dissolution. Stirring was started and heated to 135°C. The reaction system began to boil and produce bubbles, the reaction began to reflux, and gradually dehydrated. After the reaction continued to dehydrate for 1 hour, water was released from the water separator and the temperature was raised to 180°C. The reaction continued at this temperature for 1 hour, and excess water was released, and the temperature continued to rise to 195°C. The reaction was stopped when the viscosity of the solution in the reaction system no longer increased. The product was slowly poured into anhydrous ethanol with 0.1 mol / L hydrochloric acid for precipitation. The product was crushed into powder using a grinder, washed with water several times, purified with hydrochloric acid solution four times, and dried to obtain a sulfonated poly (arylene ether nitrile) with the following structure:

[0038]

[0039] Wherein, n=0.4.

[0040] In the following examples, iHOF was prepared by the following method: 1,3,5-tris(4-phosphinophenyl)benzene (16.38 mg, 0.03 mmol) (CAS: 1045720-71-5, purchased from Bidex Pharmaceuticals Co., Ltd.) was completely dissolved in 1.5 ml of H₂O, and guanidine hydrochloride (38.48 mg, 0.45 mmol) (CAS: 50-01-1, purchased from Aladdin) was dissolved in 1.5 ml of methanol. The two solutions were then mixed and allowed to stand at room temperature for 5 days to obtain colorless, transparent polyhedral crystals, iHOF.

[0041] Example 1 A composite proton exchange membrane

[0042] It is composed of the following raw materials:

[0043] 100 parts of sulfonated poly (arylene ether nitrile), 3 parts of iHOF.

[0044] Example 2 A composite proton exchange membrane

[0045] It is composed of the following raw materials:

[0046] 100 parts of sulfonated poly (arylene ether nitrile), 6 parts of iHOF.

[0047] Example 3 A composite proton exchange membrane

[0048] It is composed of the following raw materials:

[0049] 100 parts of sulfonated poly (arylene ether nitrile), 9 parts of iHOF.

[0050] Comparative Example 1 A composite proton exchange membrane

[0051] The difference from Example 3 is that 9 parts of iHOF are replaced by 9 parts of sulfonated poly(arylene ether nitrile), that is, 109 parts of sulfonated poly(arylene ether nitrile).

[0052] Comparative Example 2 A composite proton exchange membrane

[0053] The difference from Example 3 is that 100 parts of sulfonated poly (arylene ether nitrile) are replaced by 100 parts of iHOF, that is, 109 parts of iHOF.

[0054] Comparative Example 3 A composite proton exchange membrane

[0055] It is composed of the following raw materials:

[0056] 50 parts of sulfonated poly (arylene ether nitrile), 50 parts of iHOF.

[0057] The above Examples 1-3 and Comparative Examples 1-3 were prepared as follows:

[0058] Take the formulated amount of iHOF and sulfonated polyarylether nitrile and dissolve them in isopropanol respectively, then mix the two solutions, stir and ultrasonically treat at 100°C for 12 hours to fully mix the sulfonated polyarylether nitrile and iHOF; then pour the mixed solution into a glass mold and dry it to obtain a composite membrane; then soak the composite membrane in 3% H2O2 by mass at 80°C for 1 hour, then soak it in deionized water for half an hour, and then soak it in 1M H2SO4 solution at 80°C for 1 hour, wash it with deionized water, and dry it to obtain the composite proton exchange membrane.

[0059] Effect experiment

[0060] 1. Thermogravimetric analysis experiment

[0061] Thermogravimetric analysis was performed using a synchronous thermal analyzer STA449F5 (Netzsch Instrument Manufacturing Co., Ltd., Germany). The proton exchange membrane sample was heated at 10 °C min -1 The temperature was raised from room temperature to 150 °C and maintained for 15 min, and then the temperature was raised at 20 °C min -1 The thermal decomposition temperature was tested by increasing the temperature from 80°C to 600°C, and the results are shown in Table 1.

[0062] Table 1

[0063]

[0064]

[0065] 2. Mechanical properties test

[0066] The mechanical properties of the proton exchange membrane were measured using a SANS microcomputer-controlled electronic universal testing machine at a speed of 5 mm min. -1 The results are shown in Table 2.

[0067] Table 2

[0068] Tensile strength (MPa) Tensile modulus (MPa) Example 1 32 2580 Example 2 54 3119 Example 3 88 2850 Comparative Example 1 22 1100 Comparative Example 3 20 763

[0069] 3. Water absorption and swelling rate test

[0070] The water absorption swelling rate of the proton exchange membrane is calculated by comparing the change in mass to length before and after immersion in water. The specific operation is as follows: First, sulfonated poly (arylene ether nitrile) membranes of different structures are placed in an 80°C oven for 24 hours, and the membrane length (Ldry) is weighed. Next, the membranes are immersed in deionized water at different temperatures for 24 hours. The deionized water attached to the membrane surface is quickly wiped clean with filter paper, and the length of the membrane after immersion is measured (Lwet). The experiment is repeated 3-5 times, and the membrane swelling rate at room temperature and 80°C is calculated according to the following formula (1). The results are shown in Table 3.

[0071]

[0072] Table 3

[0073]

[0074]

[0075] 4. Ion exchange capacity

[0076] The ion exchange capacity (IEC) of the proton exchange membrane is determined by acid-base titration. The membrane is placed in an oven at 80°C for 24 hours, dried, and weighed and labeled Wdry. The dried membrane is then immersed in 50 mL of 1 M NaCl at room temperature for 24 hours to ensure sufficient exchange of sodium ions and hydrogen ions. The solution is titrated with 0.01 M NaOH, and the volume of NaOH used is recorded. The experiment is repeated 3-5 times and the ion exchange capacity is calculated using formula (2). The results are shown in Table 4.

[0077]

[0078] Where: V NaOH is the volume of sodium hydroxide used in the titration (mL), C NaOH is the concentration of sodium hydroxide (mol / L).

[0079] Table 4

[0080]

[0081] 5. Proton conductivity

[0082] The proton conductivity of the proton exchange membrane was measured using a Shanghai Chenhua CH760F electrochemical workstation at a voltage of 50 mV, a frequency range of 0.1 Hz to 100 kHz, and a temperature of 80°C. The membrane resistance was measured using the AC impedance method, and the proton conductivity was calculated using the following equation (3). The resulting solution is shown in Table 5.

[0083]

[0084] Where: σ, L, R and A represent conductivity (S / cm), membrane thickness (cm), impedance (Ω) and membrane cross-sectional area (cm) respectively. 2 ).

[0085] Table 5

[0086] Proton conductivity (S / cm) Example 1 0.121 Example 2 0.163 Example 3 0.223 Comparative Example 1 0.085 Comparative Example 3 0.067

[0087] It can be seen from the data in Tables 1-5 that the composite proton exchange membrane prepared in the present invention has good mechanical properties and low preparation cost, and has broad application prospects.

[0088] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, rather than to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by ordinary technicians in this field do not deviate from the essence and scope of the technical solution of the present invention.

Claims

1. A composite proton exchange membrane, characterized in that: The method comprises the following raw materials: iHOF and sulfonated polyarylethernitrile, wherein the mass ratio of the iHOF to the sulfonated polyarylethernitrile is 3-9:

100.

2. The composite proton exchange membrane according to claim 1, characterized in that The mass ratio of the iHOF to the sulfonated poly(arylene ether nitrile) is 6-9:

100.

3. The composite proton exchange membrane according to claim 1, characterized in that The mass ratio of the iHOF to the sulfonated poly(arylene ether nitrile) is 9:

100.

4. The composite proton exchange membrane according to claim 1, characterized in that The structure of the sulfonated polyarylethernitrile is: Wherein, n=0.3, 0.4, 0.5 or 0.

6.

5. The composite proton exchange membrane according to claim 4, characterized in that In the structure of the sulfonated polyarylethernitrile, n=0.

4.

6. The method for preparing a composite proton exchange membrane according to any one of claims 1 to 5, characterized in that: The preparation method is a solution blending method, which includes the following steps: The iHOF and sulfonated poly(arylene ether nitrile) in a formulated amount are dissolved in a solvent respectively, and then the two solutions are mixed, stirred and ultrasonically treated at 100-150°C for 12-14 hours, and dried to obtain a composite membrane; the composite membrane is then immersed in 3-5% H2O2 with a mass fraction at 80-100°C for 1 hour, then immersed in deionized water for half an hour, and then immersed in a 1-1.5M acid solution at 80-100°C for 1 hour, washed with deionized water, and dried to obtain the composite proton exchange membrane.

7. The preparation method according to claim 6, characterized in that The solvent is selected from one of isopropyl alcohol, propylene glycol, N,N-dimethylformamide, N,N-dimethylacetamide or dimethyl sulfoxide.

8. The preparation method according to claim 7, characterized in that The acid is selected from one of sulfuric acid, nitric acid or hydrochloric acid.

9. The preparation method according to claim 8, characterized in that The preparation method of the composite proton exchange membrane includes the following steps: taking a formulated amount of iHOF and sulfonated polyarylethernitrile and dissolving them in isopropanol respectively, then mixing the two solutions, stirring and ultrasonically treating them at 100°C for 12 hours to fully and evenly mix the sulfonated polyarylethernitrile and iHOF; then pouring the mixed solution into a glass mold and drying it to obtain a composite membrane; then soaking the composite membrane in 3% H2O2 with a mass fraction at 80°C for 1 hour, then soaking it in deionized water for half an hour, and then soaking it in 1M H2SO4 solution at 80°C for 1 hour, washing it with deionized water, and drying it to obtain the composite proton exchange membrane.

10. Use of the composite proton exchange membrane according to any one of claims 1 to 5 or the composite proton exchange membrane prepared by the preparation method according to any one of claims 6 to 9 in water electrolysis.

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