CN103560259A - POSS (Polyhedral Oligomeric Silsesquioxane) crosslinking type sulfonated polyimide proton exchange membrane as well as preparation method thereof - Google Patents

Abstract

The invention belongs to the technical field of functional high molecular materials and electrochemistry, and specifically relates to a POSS (Polyhedral Oligomeric Silsesquioxane) crosslinking type sulfonated polyimide proton exchange membrane as well as a preparation method thereof. The preparation method comprises the following steps: firstly, synthesizing a sulfonated polyimide polymer with a crosslinkable group imidazole group on a main chain, wherein the degree of sulfonation is controlled within 10-190%; and preparing a membrane forming liquid, adding a functional POSS crosslinking agent, carrying out reaction with the imidazole group, crosslinking the sulfonated polyimide polymer in a membrane forming process to form the crosslinking type sulfonated polyimide proton exchange membrane. The crosslinking membrane is endowed with good mechanical property and has higher hydrolytic stability and anti-oxidation stability. The method disclosed by the invention is good in controllability of the preparation process. Compared with conventional sulfonated polyimide membranes, the crosslinking type sulfonated polyimide proton exchange membrane is high in mechanical strength, strong in hydrolytic resistance and oxidation resistance, and good in dimensional stability, and has a broad application prospect in polymer electrolyte membrane fuel cells.

Description

A sort of POSS Cross-linked sulfonated polyimide proton exchange membrane and preparation method thereof

technical field

The invention belongs to the technical field of functional polymer materials and electrochemistry, and in particular relates to a POSS cross-linked sulfonated polyimide proton exchange membrane and a preparation method thereof.

Background technique

Proton exchange membrane fuel cells (PEMFCs) are currently the most mature technology in the world that can convert hydrogen and oxygen in the air into clean water and release electricity. It has the advantages of high energy efficiency, low emissions and environmental friendliness. The proton exchange membrane is the core component of PEMFC, which determines the performance and service life of the entire battery. At present, perfluorosulfonic acid membrane (such as Nafion ^® ) is mainly used in PEMFC, but its disadvantages such as high price, low mechanical strength, poor dimensional stability and high permeability limit its wide application.

The sulfonated polyimide proton membrane has several outstanding features: (1) It is not sensitive to external temperature changes (its glass transition temperature is high); (2) The number of water molecules per ion cluster does not depend on EW; (3 ) the proton conductivity is weakly correlated with the water content in the membrane; (4) the internal structure of the ionic phase contained in the monomer is not water droplets but the ionic part of the polymer chain; (5) the microstructure of the membrane may be lamellar rather than Ellipsoid like Nafion ^® . Therefore, sulfonated polyimide is considered to be a class of membrane materials with great promise for application. However, compared with Nafion ^® , the sulfonated hydrocarbon polymer membranes are less stable against free radical oxidation, which affects the service life of fuel cells.

Sulfonated polybenzimidazole has excellent resistance to free radical oxidation, but due to the strong interaction between the basic imidazole group and the acidic sulfonic acid group, the proton conduction is hindered, making the proton conduction of the sulfonated polybenzimidazole membrane The rate is very low. If a suitable method is adopted to introduce the benzimidazole structure into polyimide, the two can learn from each other. The present invention combines the characteristics and properties of polyimide and polybenzimidazole, introduces benzimidazole group into the main chain of sulfonated polyimide, and utilizes the active N-H structure on the imidazole group in the film forming process to add functional Polyhedral oligomeric silsesquioxane (POSS) cross-linking agent is used to form a cross-linked proton exchange membrane material, which is expected to greatly improve the anti-hydrolysis stability of the membrane while improving the anti-free radical oxidation performance of the membrane. performance and prolong the service life of the membrane.

Contents of the invention

The purpose of the present invention is to provide a POSS cross-linked sulfonated polyimide proton exchange membrane and a preparation method thereof.

The POSS cross-linked sulfonated polyimide proton exchange membrane proposed by the present invention introduces benzimidazole groups into the main chain of sulfonated polyimide polymers, and utilizes the active properties of imidazole groups in the film-forming process. The N-H structure is obtained by reacting with polyhedral oligomeric silsesquioxane (POSS) cross-linking agent to make it cross-linked. Its raw material composition includes:

1 part of sulfonated polyimide (number of moles)

POSS crosslinking agent 0.025-0.5 parts (accounting for the mass ratio of sulfonated polyimide)

160-500 parts (moles) of organic solvent;

Wherein, the main chain of the sulfonated polyimide contains benzimidazole groups.

In the present invention, the degree of sulfonation of the sulfonated polyimide (the number of moles of sulfonated diamine monomer multiplied by two divided by the number of moles of dianhydride monomer) is controlled by the feed ratio in the synthesis process. The degree of sulfonation is any one of 10%-190%.

In the present invention, the POSS crosslinking agent is a compound containing a polyhedral oligomeric silsesquioxane (POSS) structure that can react with the benzimidazole group in the sulfonated polyimide, such as Hybrid Plastics' eight Epoxy-substituted polyhedral oligomeric silsesquioxane, triepoxy-substituted polyhedral oligomeric silsesquioxane, etc., but not limited thereto.

In the present invention, the organic solvent is any one of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide or N-methylpyrrolidone, m-cresol or A mixture of the two.

The preparation method of the POSS cross-linked sulfonated polyimide proton exchange membrane that the present invention proposes, concrete steps are as follows:

(1) Soak the sulfonated polyimide in a saturated NaCl solution, take it out and dry it after 24 hours. Dissolve in an organic solvent at 100°C to form a solution. Wherein the addition amount of sulfonated polyimide in every 50mL organic solvent is 0.5-2.5g;

(2) Dissolve polyhedral oligomeric silsesquioxane (POSS) in an organic solvent at room temperature. The amount of POSS per 1mL of organic solvent is 0.05-0.1g;

(3) Mix the solutions obtained in step (1) and step (2) at room temperature, and after stirring, filter to remove air bubbles. Among them: the mass ratio of sulfonated polyimide to POSS crosslinking agent is 2:1～40:1;

(4) The film solution was poured on a 10 cm×10 cm glass plate, and dried in a vacuum oven at 60-90°C for 4-6 h, and the solvent was completely evaporated. Raise the temperature to 150-180°C and continue heating for 6-10h. Obtain sodium salt type POSS cross-linked sulfonated polyimide proton exchange membrane;

5) Soak the proton exchange membrane obtained in step (4) in methanol at 50-60 °C for 6-12 h to remove the residual organic solvent in the proton exchange membrane. After washing with deionized water, soak the proton exchange membrane in 1.0 mol/L hydrochloric acid at room temperature for 48 h, take it out, wash it repeatedly with deionized water until neutral, and dry it in a vacuum oven at 150 °C for 24 h to obtain the desired product .

The feature of the present invention is to introduce imidazole groups on the main chain of sulfonated polyimide polymer, and then use POSS as a cross-linking agent to cross-link with polyimide, which can significantly increase the proton yield of sulfonated polyimide. The thermal stability, anti-oxidation stability, hydrolytic stability and mechanical properties of the exchange membrane still have high proton conductivity.

Description of drawings

Fig. 1 is the change of the mechanical properties of POSS cross-linked sulfonated polyimide proton exchange membrane with the degree of sulfonation of sulfonated polyimide, wherein the degree of sulfonation of sulfonated polyimide is 80%, 100%, 120%, the molar ratio of POSS to sulfonated polyimide is 0.14:1.

Detailed ways

The following examples are only to further illustrate the present invention in detail, and the present invention should not be limited to the specific and express contents of the following experimental examples without violating the gist of the present invention.

The raw materials used are as follows:

Sulfonated polyimide (containing benzimidazole group and sulfonic acid group, SPIBI-X), made in the laboratory according to the method described in the literature (Pan Haiyan et al., Chemical Journal of Chinese Universities. 2007, 28(1): 173) , where X is the degree of sulfonation;

Octaepoxy-substituted, triepoxy-substituted polyhedral oligomeric oligomeric silsesquioxane (POSS), 99.5%, Hybrid Plastics;

Dimethyl sulfoxide (DMSO), 99%, Sinopharm Chemical Reagent Co., Ltd.;

N,N-Dimethylacetamide (DMAc), chemically pure (>98%), Sinopharm Chemical Reagent Co., Ltd.;

N,N-Dimethylformamide (DMF), chemically pure (>98%), Sinopharm Chemical Reagent Co., Ltd.;

N-Methylpyrrolidone (NMP), chemically pure (>98%), Sinopharm Chemical Reagent Co., Ltd.;

m-cresol ( m -cresol), chemically pure (>98%), Sinopharm Chemical Reagent Co., Ltd.;

Example 1

The ratio of raw materials used is as follows:

1 part of SPIBI-100 (number of moles of repeating units)

Octaepoxy polyhedral oligomeric silsesquioxane (POSS) 0.025 parts (accounting for the mass number of SPIBI-100)

Dimethylsulfoxide 160 parts (moles)

(1) Add 0.6g Soak SPIBI-100 in saturated NaCl solution, take it out and dry it after 24 hours. Then dissolved in 13 mL of dimethyl sulfoxide (DMSO) at 100 °C to form a homogeneous solution.

(2) Dissolve 0.015g octaepoxy-substituted POSS in 1mL DMSO solution at room temperature, and stir until a homogeneous solution. Mix well with the solution formed in (1) at room temperature, and filter to remove air bubbles.

(3) The mixture obtained in step (2) was poured on a 10 cm×10 cm glass plate, and dried in a vacuum oven at 80 °C for 6 h, and the solvent was completely evaporated. Raise the temperature to 150 °C and continue heating for 10 h to complete the cross-linking reaction.

(4) Soak the film obtained in step (3) in methanol at 60 °C for 6 h to remove the residual DMSO solvent in the film. Then, the membrane was soaked in 1.0 mol/L hydrochloric acid at room temperature for 48 h of proton exchange. The membrane was taken out, washed repeatedly with deionized water until neutral, and dried in a vacuum oven at 150 °C for 24 h to obtain the desired POSS cross-linked proton exchange membrane.

Mechanical property test of crosslinked film:

The cross-linked proton exchange membrane was made into a dumbbell-shaped film sample according to the ASTM D882-02 standard, and the tensile strength of the cross-linked film was measured on a DXLL-5000 double-screw electronic tensile machine (Shanghai Dejie Instrument Equipment Co., Ltd.) , the stretching rate is 50mm/min. The mechanical properties of the crosslinked film are shown in Fig. 1.

Example 2

The ratio of raw materials used is as follows:

1 part of SPIBI-10 (number of moles of repeating units)

0.15 parts of octaepoxy polyhedral oligomeric silsesquioxane (POSS) (accounting for the mass number of SPIBI-10)

400 parts of dimethyl sulfoxide (number of moles)

(1) Add 0.6g Soak SPIBI-100 in saturated NaCl solution, take it out and dry it after 24 hours. Then dissolved in 30 mL dimethyl sulfoxide (DMSO) at 100 °C to form a homogeneous solution.

(2) Dissolve 0.015g octaepoxy-substituted POSS in 4mL DMSO solution at room temperature, and stir until a homogeneous solution is obtained. Mix well with the solution formed in (1) at room temperature, and filter to remove air bubbles.

(3) The mixture obtained in step (2) was poured on a 10 cm×10 cm glass plate, and dried in a vacuum oven at 80 °C for 6 h, and the solvent was completely evaporated. Raise the temperature to 150°C and continue heating for 12 hours to complete the crosslinking reaction.

(4) Soak the film obtained in step (3) in methanol at 60 °C for 8 h to remove the residual DMSO solvent in the film. Then, the membrane was soaked in 1.0 mol/L hydrochloric acid at room temperature for 48 h of proton exchange. The membrane was taken out, washed repeatedly with deionized water until neutral, and dried in a vacuum oven at 150 °C for 24 h to obtain the desired POSS crosslinked proton exchange membrane.

Example 3

The ratio of raw materials used is as follows:

1 part of SPIBI-190 (number of moles of repeating unit)

Octaepoxy polyhedral oligomeric silsesquioxane (POSS) 0.50 parts (mass ratio to SPIBI-190)

N-Methylpyrrolidone (NMP) 500 parts (moles)

(1) Add 0.6g Soak SPIBI-190 in saturated NaCl solution, take it out and dry it after 24 hours. Then dissolve in 30 mL of N-methylpyrrolidone (NMP) at 100 °C to form a homogeneous solution.

(2) Dissolve 0.3g of octaepoxy-substituted POSS in 10mL of NMP solution at room temperature, and stir until a homogeneous solution is obtained. Mix well with the solution formed in (1) at room temperature, and filter to remove air bubbles.

(3) The mixture obtained in step (2) was poured on a 10 cm×10 cm glass plate, and dried in a vacuum oven at 80 °C for 6 h, and the solvent was completely evaporated. Raise the temperature to 150°C and continue heating for 8 hours to complete the crosslinking reaction.

(4) Soak the film obtained in step (3) in methanol at 60 °C for 10 h to remove the residual NMP solvent in the film. Then, the membrane was soaked in 1.0 mol/L hydrochloric acid at room temperature for 48 h of proton exchange. The membrane was taken out, washed repeatedly with deionized water until neutral, and dried in a vacuum oven at 150 °C for 24 h to obtain the desired POSS crosslinked proton exchange membrane.

Example 4

The ratio of raw materials used is as follows:

1 part of SPIBI-20 (number of moles of repeating units)

Triepoxy polyhedral oligomeric silsesquioxane (POSS) 0.25 parts (mass ratio to SPIBI-20)

N,N-Dimethylformamide (DMF) 360 parts (moles)

(1) Soak 0.6g SPIBI-20 in saturated NaCl solution, take it out and dry it after 24 hours. Then dissolve in 25 mL N,N-dimethylformamide (DMF) at 100 °C to form a homogeneous solution.

(2) Dissolve 0.15g triepoxide-substituted POSS in 5mL DMF solution at room temperature, and stir until a uniform solution is formed. Mix well with the solution formed in (1) at room temperature, and filter to remove air bubbles.

(3) The mixture obtained in step (2) was poured on a 10 cm×10 cm glass plate, and dried in a vacuum oven at 80 °C for 6 h, and the solvent was completely evaporated. Raise the temperature to 150°C and continue heating for 8 hours to complete the crosslinking reaction.

(4) Soak the film obtained in step (3) in methanol at 60 °C for 6 h to remove the residual DMF solvent in the film. Then, the membrane was soaked in 1.0 mol/L hydrochloric acid at room temperature for 48 h of proton exchange. The membrane was taken out, washed repeatedly with deionized water until neutral, and dried in a vacuum oven at 150 °C for 24 h to obtain the desired POSS crosslinked proton exchange membrane.

Example 5

The ratio of raw materials used is as follows:

1 part of SPIBI-120 (number of moles of repeating units)

Triepoxide-substituted polyhedral oligomeric silsesquioxane (POSS) 0.5 parts (mass ratio to SPIBI-120)

500 parts of dimethyl sulfoxide (moles)

(1) Soak 0.6g SPIBI-120 in saturated NaCl solution, take it out and dry it after 24 hours. Then dissolved in 30 mL dimethyl sulfoxide (DMSO) at 100 °C to form a homogeneous solution.

(2) Dissolve 0.3g triepoxide-substituted POSS in 10mL DMSO solution at room temperature, and stir until a uniform solution is obtained. Mix well with the solution formed in (1) at room temperature, and filter to remove air bubbles.

(3) The mixture obtained in step (2) was poured on a 10 cm×10 cm glass plate, and dried in a vacuum oven at 80 °C for 6 h, and the solvent was completely evaporated. Raise the temperature to 150°C and continue heating for 8 hours to complete the crosslinking reaction.

(4) Soak the film obtained in step (3) in methanol at 60 °C for 8 h to remove the residual DMSO solvent in the film. Then, the membrane was soaked in 1.0 mol/L hydrochloric acid at room temperature for 48 h of proton exchange. The membrane was taken out, washed repeatedly with deionized water until neutral, and dried in a vacuum oven at 150 °C for 24 h to obtain the desired POSS crosslinked proton exchange membrane.

Example 6

The ratio of raw materials used is as follows:

1 part of SPIBI-180 (number of moles of repeating units)

Triepoxide-substituted polyhedral oligomeric silsesquioxane (POSS) 0.025 parts (mass ratio to SPIBI-180)

400 parts of dimethyl sulfoxide (number of moles)

(1) Soak 0.6g SPIBI-180 in saturated NaCl solution, take it out and dry it after 24 hours. Then dissolved in 13 mL of dimethyl sulfoxide (DMSO) at 100 °C to form a homogeneous solution.

(2) Dissolve 0.015g triepoxide-substituted POSS in 1mL DMSO solution at room temperature, and stir until a uniform solution is formed. Mix well with the solution formed in (1) at room temperature, and filter to remove air bubbles.

(3) The mixture obtained in step (2) was poured on a 10 cm×10 cm glass plate, and dried in a vacuum oven at 80 °C for 6 h, and the solvent was completely evaporated. Raise the temperature to 150°C and continue heating for 8 hours to complete the crosslinking reaction.

(4) Soak the film obtained in step (3) in methanol at 60 °C for 8 h to remove the residual DMSO solvent in the film. Then, the membrane was soaked in 1.0 mol/L hydrochloric acid at room temperature for 48 h of proton exchange. The membrane was taken out, washed repeatedly with deionized water until neutral, and dried in a vacuum oven at 150 °C for 24 h to obtain the desired POSS crosslinked proton exchange membrane.

Example 7

The ratio of raw materials used is as follows:

1 part of SPIBI-80 (number of moles of repeating units)

Octaepoxy polyhedral oligomeric silsesquioxane (POSS) 0.30 parts (mass ratio to SPIBI-80)

N,N-Dimethylacetamide (DMAc) 500 parts (moles)

(1) Add 0.6g Soak SPIBI-80 in saturated NaCl solution, take it out and dry it after 24 hours. Then dissolved in 30 mL N,N-dimethylacetamide (DMAc) at 100 °C to form a homogeneous solution.

(2) Dissolve 0.18g octaepoxy-substituted POSS in 10mL DMAc solution at room temperature, and stir until a homogeneous solution. Mix well with the solution formed in (1) at room temperature, and filter to remove air bubbles.

(3) The mixture obtained in step (2) was poured on a 10 cm×10 cm glass plate, and dried in a vacuum oven at 80 °C for 6 h, and the solvent was completely evaporated. Raise the temperature to 150°C and continue heating for 8 hours to complete the crosslinking reaction.

(4) Soak the film obtained in step (3) in methanol at 60 °C for 6 h to remove the residual DMAc solvent in the film. Then, the membrane was soaked in 1.0 mol/L hydrochloric acid at room temperature for 48 h of proton exchange. The membrane was taken out, washed repeatedly with deionized water until neutral, and dried in a vacuum oven at 150 °C for 24 h to obtain the desired POSS crosslinked proton exchange membrane.

Example 8

The ratio of raw materials used is as follows:

1 part of SPIBI-60 (number of moles of repeating units)

Triepoxy polyhedral oligomeric silsesquioxane (POSS) 0.40 parts (mass ratio to SPIBI-60)

m-cresol ( m -cresol) 360 parts (moles)

(1) Soak 0.6g SPIBI-60 in saturated NaCl solution, take it out and dry it after 24 hours. Then dissolved in 25 mL m-cresol ( m -cresol) at 100 °C to form a homogeneous solution.

(2) Dissolve 0.24g triepoxide-substituted POSS in 5mL m -cresol solution at room temperature, and stir until a homogeneous solution. Mix well with the solution formed in (1) at room temperature, and filter to remove air bubbles.

(3) The mixture obtained in step (2) was poured on a 10 cm×10 cm glass plate, and dried in a vacuum oven at 80 °C for 6 h, and the solvent was completely evaporated. Raise the temperature to 150°C and continue heating for 8 hours to complete the crosslinking reaction.

(4) Soak the film obtained in step (3) in methanol at 60 °C for 12 h to remove the residual m -cresol solvent in the film. Then, the membrane was soaked in 1.0 mol/L hydrochloric acid at room temperature for 48 h of proton exchange. The membrane was taken out, washed repeatedly with deionized water until neutral, and dried in a vacuum oven at 150 °C for 24 h to obtain the desired POSS crosslinked proton exchange membrane.

In the foregoing embodiments, the raw materials and amounts of each component and the parameters of the preparation process are only selected representatives for describing the invention. In fact, a large number of experiments have shown that within the scope defined in the summary of the invention, POSS cross-linked sulfonated polyimide proton exchange membranes similar to those of the above examples can be obtained.

Claims (5)

1. a POSS crosslinked sulfonated polyimide proton exchange membrane, it is characterized in that this cross linking membrane is to introduce benzimidazolyl on polyimide main polymer chain, and in film forming procedure, utilize active N-H structure and polyhedral oligomeric silsesquioxane POSS crosslinking agent on imidazole radicals to react and crosslinked obtaining, its raw material forms and comprises:

1 part of sulfonated polyimide (molal quantity)

Polyhedral oligomeric silsesquioxane crosslinking agent 0.025-0.5 part (accounting for the mass ratio of sulfonated polyimide)

Organic solvent 160-500 part (molal quantity);

Wherein, described sulfonated polyimide is that main chain contains benzimidazole based structures.

2. POSS crosslinked sulfonated polyimide proton exchange membrane according to claim 1, the sulfonation degree that it is characterized in that described sulfonated polyimide any one value from 10%-190%.

3. POSS crosslinked sulfonated polyimide proton exchange membrane according to claim 1, it is characterized in that POSS crosslinking agent be the polyhedral oligomeric silsesquioxane that replaces of octa-epoxy, in the polyhedral oligomeric silsesquioxane that three epoxy radicals replace any, but be not limited only to this.

4. POSS crosslinked sulfonated polyimide proton exchange membrane according to claim 1, it is characterized in that described organic solvent is N, the mixed liquor of any one or two kinds in dinethylformamide, DMA, dimethyl sulfoxide (DMSO) or 1-METHYLPYRROLIDONE.

5. a preparation method for POSS crosslinked sulfonated polyimide proton exchange membrane as claimed in claim 1, is characterized in that concrete steps are as follows:

(1) sulfonated polyimide is immersed in saturated NaCl solution, after 24h, takes out and dry; At 100 ℃, be dissolved in organic solvent wiring solution-forming; Wherein in every 50mL organic solvent, the addition of sulfonated polyimide is 0.5-2.5g;

(2) by polyhedral oligomeric silsesquioxane crosslinking agent, normal-temperature dissolution is in organic solvent; Wherein in every 1mL organic solvent, the addition of polyhedral oligomeric silsesquioxane is 0.05-0.1g;

(3) under room temperature, the solution of step (1) and step (2) gained is mixed, after stirring, filter bubble removing; Wherein: the mass ratio of sulfonated polyimide and polyhedral oligomeric silsesquioxane crosslinking agent is 2:1～40:1;

(4) film liquid step (3) being obtained is cast on the glass plate of 10 cm * 10 cm, dry 4-6 h in 60-90 ℃ of vacuum drying oven, and solvent volatilizees completely; Be warming up to 150-180 ℃ and continue heating 6-10h; Obtain sodium-salt type POSS crosslinked sulfonated polyimide proton exchange membrane;

(5) the quality proton exchange of step (4) gained is soaked to 6-12 h in the methyl alcohol of 50-60 ℃, remove organic solvent residual in proton exchange membrane; Deionized water is immersed in film in 1.0 mol/L hydrochloric acid and takes out after 48 h under normal temperature after cleaning, and with deionized water cyclic washing, to neutral, in 150 ℃ of vacuum drying ovens, dry 24 h, obtain required product.

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