A high-stability alkaline polyelectrolyte and preparation method thereof

Abstract

The invention discloses a high-stability alkaline polyelectrolyte and a preparation method thereof. First, under the action of a first catalyst, a vinyl-containing norbornene monomer is subjected to addition polymerization to obtain a polynorbornene having a bridge ring structure as a main chain and a vinyl reaction site in a side chain; then, under the action of a second catalyst, the polynorbornene and a halogenated olefin are subjected to an olefin metathesis reaction to obtain a halogenated polynorbornene having a halogen reaction site in a side chain; then, under the action of a reducing agent, the remaining carbon-carbon double bonds in the halogenated polynorbornene are subjected to a hydrogenation reaction to obtain a hydrogenated halogenated polynorbornene; finally, the hydrogenated halogenated polynorbornene is reacted with a quaternary ammonium agent to obtain an alkaline polymer electrolyte having high stability. The invention has a simple process, mild reaction conditions, and a cross-linked membrane product having a low swelling rate and water content, high ionic conductivity, better gas barrier performance and high stability, and high application value.

Description

Technical Field

[0001] The invention belongs to the field of materials and relates to a method for preparing a polymer electrolyte, in particular to a high-stability alkaline polyelectrolyte and a method for preparing the same. Background Art

[0002] With the rapid development of human society, non-renewable energy is becoming increasingly depleted. Fuel cells, as an efficient energy storage and conversion device that can utilize renewable energy such as hydrogen energy, have received increasing attention. The earlier developed proton exchange membrane fuel cells have achieved a certain scale of commercialization, but the perfluorosulfonic acid proton exchange membrane and precious metal catalysts used in them make them expensive, limiting their large-scale application. The working environment of alkaline polyelectrolyte fuel cells is alkaline, and theoretically cheaper core materials can be used, which provides the possibility of reducing the cost of batteries. In order to promote alkaline polyelectrolyte fuel cells to practical applications, the problem of long-term stable operation of batteries needs to be solved at this stage. The stability of batteries is related to the stability of electrode materials, electrode structure and battery operating conditions. Electrode materials mainly include catalysts and polyelectrolytes. Therefore, finding a simple and easy-to-obtain high-stability polyelectrolyte and using it reasonably is expected to achieve a breakthrough in the long-term stability of batteries.

[0003] Quaternized polynorbornene has a saturated carbon-hydrogen main chain structure, so it has extremely high alkaline stability and oxidation stability, and is one of the excellent candidate materials for alkaline polyelectrolyte fuel cells. There are three methods for synthesizing polynorbornene: ring-opening metathesis polymerization, free radical / ion polymerization, and addition polymerization, among which the product obtained by addition polymerization is a saturated carbon-hydrogen structure with higher stability. The quaternization reaction of polynorbornene with substituents on the side chain can obtain an alkaline polyelectrolyte containing quaternary ammonium cations, which can be further used in fuel cells. However, the synthetic methods reported so far have the problems of narrow monomer selection range, expensive monomers, and harsh synthesis conditions, which makes it difficult to reflect the low-cost advantage of alkaline polyelectrolyte fuel cells, and therefore difficult to promote in practical applications. Summary of the invention

[0004] In view of the above problems, the present invention proposes a high-stability alkaline polyelectrolyte and a preparation method thereof, and obtains a structurally adjustable alkaline polyelectrolyte material (quaternized polynorbornene) by combining addition polymerization and olefin metathesis reaction. This type of material has excellent chemical stability and ion conductivity, and is expected to solve the problem of long-term stable operation of alkaline polyelectrolyte fuel cells, and is expected to be applied to alkaline water electrolysis, carbon dioxide electrolyzers, and gas or liquid separation in the future.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A method for preparing a high-stability alkaline polyelectrolyte comprises the following steps:

[0007] Step 1: Under the action of a first catalyst, a norbornene monomer containing a vinyl group is subjected to addition polymerization to obtain a polynorbornene having a bridged ring structure as a main chain and a vinyl reaction site on a side chain;

[0008] Step 2: Under the action of a second catalyst, the polynorbornene is subjected to an olefin metathesis reaction with a halogenated olefin to obtain a halogenated polynorbornene having a halogen reaction site in the side chain;

[0009] Step 3: Under the action of a reducing agent, hydrogenating the remaining carbon-carbon double bonds in the halogenated polynorbornene to obtain hydrogenated halogenated polynorbornene;

[0010] Step 4: reacting the hydrogenated halogenated polynorbornene with a quaternary ammonium agent to obtain an alkaline polymer electrolyte with high stability.

[0011] Further, in step 1, the specific reaction steps are as follows:

[0012] The first catalyst and the corresponding co-catalyst are dissolved in an organic solvent, and then a norbornene monomer containing a vinyl group is added, and the mixture is stirred for a period of time at room temperature under the protection of an inert gas. The reaction system is diluted to a relatively low concentration and then precipitated in an ethanol solution of hydrochloric acid. The filter residue after suction filtration is washed with a volatile organic solvent until the pH value is neutral to obtain a white flocculent. The white flocculent is vacuum dried to obtain a polynorbornene (PNB) having a vinyl side chain.

[0013] The organic solvent includes anhydrous dichloromethane, chloroform, dichloroethane, tetrahydrofuran, toluene, etc.; the inert gas includes rare gases such as nitrogen and argon; the volatile organic solvent includes methanol, ethanol, propanol, etc.

[0014] Further preferably, in step 1, the first catalyst comprises the following types:

[0015] (1) Metal Ti and cyclopentadienyl complexes, there are five types:

[0016]

[0017] (2) Metal Pd or Ni and allyl complexes, there are six types:

[0018]

[0019] (3) Metal Pd and cyclopentadienyl complexes, there are two types:

[0020]

[0021] (4) The bidentate complexes of metal Pd and acetylacetonimine include the following six types:

[0022]

[0023] (5) Metal Pd complexes include the following four types:

[0024]

[0025] Furthermore, in step 1, during the addition reaction, a co-catalyst is selected according to the first catalyst type, and the co-catalyst is selected from NaBARF (sodium tetrakis(3,5-di(trifluoromethyl)phenyl)borate), AgSbF2, Al2Et3Cl3, LiFABA (lithium tetrakis(pentafluorophenyl)borate), TrFABA (triphenylcarbon tetrakis(pentafluorophenyl)borate) and methylaluminoxane.

[0026] Furthermore, in step 1, the norbornene monomers containing vinyl groups include the following six categories:

[0027]

[0028] Wherein, n is 1 to 18, R1 is a hydrogen atom or an alkyl group, and R2 is also a hydrogen atom or an alkyl group.

[0029] Further, in step 2, the specific reaction steps are as follows:

[0030] The polynorbornene PNB and halogenated olefin prepared in step 1 are dissolved in an organic solvent to obtain a reaction solution, and then the second catalyst is dissolved in an organic solvent to obtain a catalyst solution, and then the catalyst solution is injected into the reaction solution containing PNB, and stirred and refluxed for 20 hours under inert gas protection conditions at around the boiling point of the organic solvent, and the reaction product is precipitated in an ethanol solution of hydrochloric acid. The filter residue after suction filtration is washed with ethanol to a neutral pH, and vacuum dried at 45° C. for 12 hours to obtain a polynorbornene with a halogenated olefin on the side chain.

[0031] The organic solvent includes anhydrous dichloromethane, chloroform, dichloroethane, tetrahydrofuran, toluene, etc.; the inert gas includes rare gases such as nitrogen and argon.

[0032] Further preferably, in step 2, the second catalyst is a ruthenium carbene complex.

[0033] Further preferably, in step 2, the halogenated olefin is an olefin substituted with chlorine, bromine, iodine or p-toluenesulfonyl, and the linear length does not exceed 18 carbon atoms.

[0034] Further preferably, in step 2, the halogenated olefin is any one selected from 6-bromo-1-hexene, 5-bromo-1-pentene, 4-bromo-1-butene and 3-bromo-1-propylene.

[0035] Further, in step 3, the specific reaction steps are as follows:

[0036] The polynorbornene with a halogenated olefin on the side chain prepared in step 2 is weighed and dissolved in chlorobenzene or toluene, p-toluenesulfonyl hydrazide is added as a reducing agent, and the mixture is stirred and refluxed for a period of time under the protection of an inert gas. The reaction product is precipitated in ethanol or water, and a gray solid powder is obtained after centrifugation. The gray solid powder is washed with ethanol or water for multiple times, and the supernatant is removed by centrifugation and then vacuum dried to obtain a polynorbornene with a hydrogenated halogenated olefin on the side chain.

[0037] Furthermore, in step 3, the reducing agent is p-toluenesulfonyl hydrazide or hydrogen.

[0038] Furthermore, in step 4, the quaternizing agent is any one or more of tertiary amines such as trimethylamine, triisopropylamine, tri-tert-butylamine, triethylamine, pyridine, 4-methylpyridine, methylpiperidine, quinoline, and isoquinoline.

[0039] Further, in step 4, the alkaline polymer electrolyte includes alkaline polymer electrolyte powder and alkaline polymer electrolyte membrane, and the specific reaction steps of preparing quaternized hydrogenated polynorbornene powder (alkaline polymer electrolyte powder) by reacting the hydrogenated halogenated polynorbornene with a quaternizing agent are as follows:

[0040] The polynorbornene of hydrogenated halogenated olefin prepared in step 3 is dispersed in the aqueous solution of quaternizing agent, stirred and reacted for a period of time, the reaction product is poured into a mortar, ground while evaporating the liquid, and dried after grinding to obtain quaternized hydrogenated polynorbornene powder, that is, ionic polymer powder with high stability.

[0041] As a preferred embodiment, the stirring reaction temperature is about 40° C. and the time is about 24 hours.

[0042] Furthermore, in step 4, the specific reaction steps for preparing a polyelectrolyte membrane (alkaline polymer electrolyte membrane) by reacting the hydrogenated halogenated polynorbornene with a quaternary ammonium agent are as follows:

[0043] The hydrogenated brominated polynorbornene prepared in step 3 is dissolved in a film-forming solvent, stirred at room temperature to obtain a uniform transparent solution, and then a cross-linking agent is added and stirred again to be uniform. After filtering, the filtrate is poured onto a template with a groove, and the template is dried in an oven to volatilize the solvent to form a film; then the film is peeled off from the template, immersed in a quaternary ammonium reagent solution for a period of time, and the residual quaternary ammonium reagent on the surface of the membrane is washed off and then immersed in a strong alkaline solution for ion exchange, and the strong alkaline solution is replaced every time to obtain an anion of OH - type of polyelectrolyte membrane.

[0044] The film-forming solvent is a volatile organic solvent, such as chlorobenzene, etc.; the cross-linking agent is a ditertiary amine reagent such as N,N,N,N-tetramethyl-1,6-hexanediamine, tetramethylbutylene diamine, tetramethylpropylene diamine, tetraethylbutylene diamine, tetraethylhexanediamine, etc.

[0045] The strong alkaline solution is KOH solution, NaOH solution, etc.

[0046] The template is a glass plate with grooves.

[0047] The present invention also protects a high-stability alkaline polyelectrolyte prepared by any one of the above-mentioned preparation methods.

[0048] The beneficial effects of the present invention are as follows:

[0049] The present invention creatively proposes a simple method for preparing quaternized polynorbornene, which does not contain polar groups such as ether, sulfur, carbonyl or unsaturated structures such as carbon-carbon double bonds in its structure, and thus has extremely high chemical stability under harsh conditions such as acidic or alkaline. By utilizing olefin metathesis reaction, a side chain with adjustable length can be grafted onto the polymer main chain, and a polymer electrolyte with a completely saturated carbon-hydrogen structure can be obtained through reduction hydrogenation and quaternization reaction. The reagents, solvents, catalysts, etc. required for the synthesis are simple and easy to obtain, and the reaction conditions are relatively mild, which provides the possibility for mass production of high-stability polyelectrolytes.

[0050] In addition, it is worth noting that the polymerization method of functionalized norbornene in the prior art is generally ring-opening polymerization. During the polymerization process, the monomer and the catalyst will form more complex four-membered ring heterometallic intermediates, which will lead to the formation of isomers in the polymerization process. The resulting polymer has a low molecular weight, resulting in poor mechanical strength after its preparation into a film, and the swelling rate and water content of the film are high, resulting in poor performance when used in devices such as fuel cells. And the main chain of the resulting polymer is a five-membered single ring structure, and the two five-membered rings are connected by -CH2-CH2-. Since the carbon-carbon single bond has a certain rotatability, this type of main chain structure has a strong flexibility feature, which easily leads to entanglement and confusion of the polymer chain, which is also one of the reasons for the poor gas barrier properties of the polyelectrolyte membrane. The polymerization method used in the present invention is addition polymerization, which is essentially different from ring-opening polymerization. The coordination addition polymerization process is relatively simple and can obtain a higher molecular weight (number average molecular weight>80kg / mol, weight average molecular weight>250kg / mol). The resulting polymer main chain is a bridge ring structure with stronger rigidity in which five-membered rings and six-membered rings coexist, which makes the polyelectrolyte membrane have a lower swelling rate and water content, and has a higher ionic conductivity and better gas barrier properties. Ultimately, a higher power density can be obtained in fuel cell applications, and it has a high practical application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 1 is the hydrogen nuclear magnetic resonance spectrum of the polynorbornene having alkenyl side chains in the embodiments of the present invention.

[0052] Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of the brominated polynorbornene in Example 1 of the present invention.

[0053] Figure 3 This is the hydrogen nuclear magnetic resonance spectrum of the brominated hydrogenated polynorbornene in Example 1 of the present invention.

[0054] Figure 4 This is the Raman spectrum of the quaternized hydrogenated polynorbornene in Example 1 of the present invention.

[0055] Figure 5 The OH group in Example 1 of the present invention has a side chain containing 6 carbon atoms. - Alkaline stability of polyelectrolyte membranes immersed in 1 M KOH at 80 °C for 80 days.

[0056] Figure 6 The OH group having 5 carbon atoms in the side chain in Example 2 of the present invention is - Alkaline stability of polyelectrolyte membranes immersed in 1 M KOH at 80 °C for 80 days.

[0057] Figure 7 The OH group having 5 carbon atoms in the side chain in Example 2 of the present invention is -Swelling rate and water content of polyelectrolyte membrane at 40, 60 and 80℃.

[0058] Figure 8 The OH group having 5 carbon atoms in the side chain in Example 2 of the present invention is - The ionic conductivity of the polyelectrolyte membrane at 30-88°C.

[0059] Fig. 9 The fuel cell performance is shown in Figure 1, which uses the QAHPNB-C6 in Example 1 of the present invention as the ionomer in the catalyst layer and the alkaline polyelectrolyte membrane in Example 2 of the present invention as the separator. DETAILED DESCRIPTION

[0060] The present invention is further described below by specific examples, the purpose of which is to help better understand the content of the present invention, but these specific embodiments do not limit the scope of protection of the present invention in any way. The raw materials used in this embodiment are all common known compounds and can be purchased on the market.

[0061] Example 1

[0062] Polyelectrolyte backbone synthesis

[0063] 1) Sodium tetrakis(3,5-bis(trifluoromethyl)phenyl)borate (0.08 mmol, 71.2 mg) as a co-catalyst and allylpalladium chloride-triphenylphosphine complex (0.08 mmol, 35.6 mg) as a first catalyst were weighed into a 100 mL three-necked flask, 2 mL of chlorobenzene as a solvent was added, and the mixture was stirred for 20 min. Then, 5-vinyl-2-norbornene (80 mmol, 11.5 mL) as a norbornene monomer was added, and the mixture was stirred for 2 h at room temperature under argon protection. The reaction system was diluted to a lower concentration and precipitated in a 4 mol / L hydrochloric acid ethanol solution. The filter residue after suction filtration was washed with ethanol until the pH was neutral to obtain a white flocculent, which was dried in a vacuum drying oven at 60° C. for 12 h to obtain polynorbornene (PNB) with a vinyl side chain. Figure 1 is the hydrogen nuclear magnetic resonance spectrum of the above polynorbornene.

[0064] 2) Side chain grafting

[0065] The polynorbornene PNB (33.0 mmol, 4.00 g) prepared in step 1) and 6-bromo-1-hexene (49.5 mmol, 6.60 mL) as a halogenated olefin were weighed and dissolved in 170 mL of anhydrous dichloromethane to obtain a reaction solution. Grubbs second-generation catalyst (0.66 mmol, 568 mg) was then dissolved in 30 mL of anhydrous dichloromethane. The solution of Grubbs second-generation catalyst was then injected into the reaction solution containing PNB, and the mixture was stirred and refluxed at 42° C. under argon protection for 20 h. The reaction product was precipitated in a 4 mol / L ethanol solution of hydrochloric acid. The filter residue after suction filtration was washed with ethanol until the pH was neutral, and dried in vacuo at 45° C. for 12 h to obtain a polynorbornene (PNB-C6-Br) having 6 carbon bromines on the side chain. Figure 2 is the hydrogen nuclear magnetic resonance spectrum of the above-mentioned brominated polynorbornene.

[0066] 3) Side chain reduction

[0067] The brominated polynorbornene PNB-Br (11.7 mmol, 2.50 g) prepared in step 2) was weighed and dissolved in 120 mL of chlorobenzene, p-toluenesulfonyl hydrazide (46.6 mmol, 7.84 g) was added, and the mixture was stirred and refluxed at 133° C. for 7 h under argon protection. The reaction product was precipitated in ethanol and centrifuged. The gray solid powder was washed three times with ethanol, and the supernatant was removed by centrifugation and vacuum dried at 50° C. for 12 h to obtain a hydrogenated brominated polynorbornene (HPNB-C6-Br) having 6 carbon atoms in the side chain. Figure 3 is the hydrogen nuclear magnetic resonance spectrum of the above-mentioned brominated hydrogenated polynorbornene.

[0068] 4) Preparation of ionic polymer powder

[0069] Weigh the hydrogenated brominated polynorbornene HPBN-C6-Br (400 mg) prepared in step 3) into a 50 mL round-bottom flask, add 30 wt % trimethylamine aqueous solution (20 mL), stir at 40 ° C for 24 h, pour the reaction product into a mortar, grind while evaporating the liquid, and dry at 60 ° C after grinding to obtain quaternary ammonium hydrogenated polynorbornene powder (QAHPNB-C6). Figure 4 : is the Raman spectrum of the quaternized hydrogenated polynorbornene powder.

[0070] 5) Polyelectrolyte membrane preparation

[0071] Weigh 0.5 g of the hydrogenated brominated polynorbornene prepared in step 3) into a 50 mL round-bottom flask, add 30 mL of chlorobenzene, stir at room temperature to obtain a uniform transparent solution, add N,N,N,N-tetramethyl-1,6-hexanediamine (32 μL) and stir again, filter through a 600 mesh filter cloth and pour into a 10*10 cm 2The film was formed by evaporating the solvent in a 55°C oven on a glass plate with a groove. The film was peeled off the glass plate, cut into a suitable size and placed in a beaker. 80 mL of trimethylamine aqueous solution was added and soaked at 40°C for 24 h. The residual trimethylamine on the surface of the film was washed off and then soaked in 1M KOH solution. Ion exchange was performed at 50°C for 3 h. The KOH solution was replaced every 1 h to obtain an anion of OH - type of polyelectrolyte membrane.

[0072] The above OH - The polyelectrolyte membrane was immersed in 1M KOH at 80°C for 80 days, and the membrane was taken out at regular intervals to perform ion exchange capacity tests using precipitation titration to characterize the chemical stability of the membrane. Figure 5 In the 80-day (about 2000 hours) alkaline stability test, the ion exchange capacity of the polyelectrolyte membrane did not change significantly, and the quaternary ammonium cation retention rate calculated by the ion exchange capacity was 90%, indicating that it is very stable and suitable for use in alkaline polyelectrolyte fuel cells and is expected to solve the problem of long-term stable operation of the battery.

[0073] Example 2

[0074] 1) Synthesis of polyelectrolyte main chain, same as in Example 1.

[0075] 2) Side chain grafting

[0076] The polynorbornene PNB (33.0 mmol, 4.00 g) prepared in step 1) and 5-bromo-1-pentene (40 mmol, 4.88 mL) as a halogenated olefin were weighed and dissolved in 130 mL of anhydrous dichloromethane, and then Grubbs second-generation catalyst (0.99 mmol, 852 mg) was dissolved in 30 mL of anhydrous dichloromethane. The solution of Grubbs second-generation catalyst was then injected into the reaction solution containing PNB, and stirred and refluxed at 42° C. under argon protection for 20 h. The reaction product was precipitated in a 4 mol / L ethanol solution of hydrochloric acid. The filter residue after suction filtration was washed with ethanol until the pH was neutral, and vacuum dried at 45° C. for 12 h to obtain a polynorbornene (PNB-C5-Br) having 5 carbon bromines on the side chain.

[0077] 3) Side chain reduction

[0078] The brominated polynorbornene PNB-Br (13.4 mmol, 2.50 g) prepared in step 2) was weighed and dissolved in 100 mL of chlorobenzene, p-toluenesulfonyl hydrazide (40 mmol, 6.76 g) was added, and the mixture was stirred and refluxed at 133° C. for 7 h under argon protection. The reaction product was precipitated in ethanol and centrifuged. The gray solid powder was washed three times with ethanol, and the supernatant was removed by centrifugation and vacuum dried at 50° C. for 12 h to obtain a hydrogenated brominated polynorbornene (HPNB-C5-Br) having 5 carbon atoms in the side chain.

[0079] 4) Preparation of ionic polymer powder is the same as in Example 1.

[0080] 5) Polyelectrolyte membrane preparation

[0081] Weigh 0.35 g of the hydrogenated brominated polynorbornene prepared in step 3) into a 50 mL round-bottom flask, add 30 mL of chlorobenzene, stir at room temperature to obtain a uniform transparent solution, add N,N,N,N-tetramethyl-1,6-hexanediamine (33 μL) and stir again, filter through a 600 mesh filter cloth and pour into a 10*10 cm 2 The film was formed by evaporating the solvent in a 55°C oven on a glass plate with a groove. The film was peeled off the glass plate, cut into a suitable size and placed in a beaker. 80 mL of trimethylamine aqueous solution was added and soaked at 40°C for 24 h. The residual trimethylamine on the surface of the film was washed off and then soaked in 1M KOH solution. Ion exchange was performed at 50°C for 3 h. The KOH solution was replaced every 1 h to obtain an anion of OH - type of polyelectrolyte membrane.

[0082] The above OH - The polyelectrolyte membrane was immersed in 1M KOH at 80°C for 80 days. The membrane was taken out at regular intervals and the ion exchange capacity was tested using the precipitation titration method. Figure 6 It can be seen that the anion exchange membrane in this embodiment also has very good alkali stability, and the quaternary ammonium cation retention rate is still 94% after 80 days of stability test.

[0083] For the above OH - The swelling rate and water content of polyelectrolyte membranes were tested. The specific test method is: soak a membrane of a certain size in water at a certain temperature, take it out after stabilizing for 2 hours, measure its wet size and mass, and measure the size and mass of the dry membrane after the membrane is completely dried. The swelling rate and water content at a specific temperature are obtained by calculation. The specific results are shown in Figure 7 The cross-linked polynorbornene film with a cross-linking degree of 15% prepared by the method has a swelling rate of less than 30% in the range of 40 to 80° C. and a water content of about 100%, which meets the use requirements of fuel cells.

[0084] The four-electrode electrochemical impedance spectroscopy was used to measure the OH - The ionic conductivity of the polyelectrolyte membrane was tested in an environment of 100% relative humidity of N2. The specific results are shown in Figure 8 The ion exchange capacity of the polynorbornene membrane prepared in this embodiment is about 2.7 mmol / g, the ion conductivity at 30° C. is 91 mS / cm, and the ion conductivity at 88° C. reaches 195 mS / cm, and the ion conductivity is excellent.

[0085] The ionic polymer prepared in step 4) of Example 1 was mixed with a Pt / C catalyst, and an ink of a certain concentration was prepared using isopropanol and then sprayed on carbon paper with a leveling layer, and assembled with the anion exchange membrane prepared in step 5) of this Example to obtain a membrane electrode assembly. The membrane electrode assembly was used to test the performance of a fuel cell. The test instrument used was 850eFuel Cell, and the test conditions were hydrogen and oxygen injection, 80°C, and 0.2 MPa back pressure. Fig. 9 The polarization curve and power density curve of the battery. The open circuit voltage is 1.03V, indicating that the gas barrier property of the polyelectrolyte membrane is good at 3.2A / cm 2 The current density was 1.36 W / cm 2 Higher peak power density.

[0086] Example 3

[0087] 1) Synthesis of polyelectrolyte main chain, same as in Example 1.

[0088] 2) Side chain grafting

[0089] The polynorbornene PNB (16.7 mmol, 2.00 g) prepared in step 1) and 3-bromo-1-propylene (25 mmol, 2.16 mL) as a halogenated olefin were weighed and dissolved in 60 mL of anhydrous dichloromethane to obtain a reaction solution. Grubbs second-generation catalyst (0.334 mmol, 284 mg) was then dissolved in 20 mL of anhydrous dichloromethane. The solution of Grubbs second-generation catalyst was then injected into the reaction solution containing PNB, and the mixture was stirred and refluxed at 42° C. under argon protection for 20 h. The reaction product was precipitated in a 4 mol / L ethanol solution of hydrochloric acid. The filter residue after suction filtration was washed with ethanol until the pH was neutral, and dried in vacuo at 45° C. for 12 h to obtain a polynorbornene (PNB-C3-Br) having three carbon bromines on the side chain.

[0090] 3) Side chain reduction

[0091] The brominated polynorbornene PNB-Br (13.3 mmol, 2.00 g) prepared in step 2) was weighed and dissolved in 90 mL of chlorobenzene, p-toluenesulfonyl hydrazide (40 mmol, 6.72 g) was added, and the mixture was stirred and refluxed at 133° C. for 7 h under argon protection. The reaction product was precipitated in ethanol and centrifuged. The gray solid powder was washed three times with ethanol, and the supernatant was removed by centrifugation and vacuum dried at 50° C. for 12 h to obtain a hydrogenated brominated polynorbornene (HPNB-C3-Br) having 3 carbons in the side chain.

[0092] 4) Preparation of ionic polymer powder is the same as in Example 1.

[0093] 5) Polyelectrolyte membrane preparation

[0094] Weigh 0.3 g of the hydrogenated brominated polynorbornene prepared in step 3) into a 50 mL round-bottom flask, add 30 mL of chlorobenzene, stir at room temperature to obtain a uniform transparent solution, filter through a 600 mesh filter cloth, and pour into a 10*10 cm 2 The film was formed by evaporating the solvent in a 55°C oven on a glass plate with a groove. The film was peeled off the glass plate, cut into a suitable size and placed in a beaker. 50 mL of trimethylamine aqueous solution was added and soaked at 40°C for 24 h. The residual trimethylamine on the surface of the film was washed off and then soaked in 1M KOH solution. Ion exchange was performed at 50°C for 3 h. The KOH solution was replaced every 1 h to obtain an anion of OH - type of polyelectrolyte membrane.

[0095] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing a high-stability alkaline polyelectrolyte, characterized in that: The following steps are involved: Step 1: Under the action of a first catalyst, a norbornene monomer containing a vinyl group is subjected to addition polymerization to obtain a polynorbornene having a bridged ring structure as a main chain and a vinyl reaction site on a side chain; Step 2: Under the action of a second catalyst, the polynorbornene is subjected to an olefin metathesis reaction with a halogenated olefin to obtain a halogenated polynorbornene having a halogen reaction site in the side chain; Step 3: Under the action of a reducing agent, hydrogenating the remaining carbon-carbon double bonds in the halogenated polynorbornene to obtain hydrogenated halogenated polynorbornene; Step 4: reacting the hydrogenated halogenated polynorbornene with a quaternary ammonium agent to obtain an alkaline polymer electrolyte with high stability; In step 1, the first catalyst includes the following types: (1) Metal Ti and cyclopentadienyl complex (2) Metal Pd or Ni and allyl complex (3) Metal Pd and cyclopentadienyl complexes (4) Bidentate complex of metal Pd and acetylacetonimide (5) Metal Pd complexes Norbornene monomers containing vinyl groups include the following six categories: Wherein, n is 1 to 18, R1 is a hydrogen atom or an alkyl group, and R2 is also a hydrogen atom or an alkyl group.

2. The method for preparing the highly stable alkaline polyelectrolyte according to claim 1, characterized in that: In step 1, during the addition reaction, a co-catalyst is selected according to the first catalyst type, and the co-catalyst is selected from sodium tetrakis(3,5-di(trifluoromethyl)phenyl)borate, AgSbF2, Al2Et3Cl3, lithium tetrakis(pentafluorophenyl)borate, triphenylcarbon tetrakis(pentafluorophenyl)borate and methylaluminoxane.

3. The method for preparing the highly stable alkaline polyelectrolyte according to claim 1, characterized in that: In step 2, the second catalyst is a ruthenium carbene complex.

4. The method for preparing the highly stable alkaline polyelectrolyte according to claim 1, characterized in that: In step 2, the halogenated olefin is an olefin substituted with chlorine, bromine or iodine, and the linear length does not exceed 18 carbon atoms.

5. The method for preparing the highly stable alkaline polyelectrolyte according to claim 3, characterized in that: In step 2, the halogenated olefin is any one selected from 6-bromo-1-hexene, 5-bromo-1-pentene, 4-bromo-1-butene and 3-bromo-1-propylene.

6. The method for preparing the highly stable alkaline polyelectrolyte according to claim 1, characterized in that: In step 3, the reducing agent is p-toluenesulfonyl hydrazide or hydrogen.

7. The method for preparing the high stability alkaline polyelectrolyte according to claim 1, characterized in that: In step 4, the quaternizing agent is any one or more of trimethylamine, triisopropylamine, tri-tert-butylamine, triethylamine, methylimidazole, pyridine, methylpiperidine, quinoline, and isoquinoline.

8. A high stability alkaline polyelectrolyte, characterized in that: Prepared by the preparation method according to any one of claims 1 to 7.

Images