Proton-conducting polymer membrane comprising polymers containing phosphonic acid groups and its use in fuel cells

Abstract

The present invention relates to a proton-conducting polymer membrane comprising polymers containing phosphonic acid groups which is obtainable by a process comprising the steps A) mixing of vinyl-containing phosphonic acid with one or more aromatic tetramino compounds with one or more aromatic carboxylic acids, esters thereof, acid halides thereof or anhydrides thereof which contain at least two acid groups per carboxylic acid monomer, and/or mixing of vinyl-containing phosphonic acid with one or more aromatic and/or heteroaromatic diamino carboxylic acids, esters thereof, acid halides thereof or anhydrides thereof, B) heating of the mixture obtainable according to step A) under inert gas at temperatures of up to 350° C. to form polyazole polymers, C) application of a layer using the mixture from step A) and/or B) to a support, D) polymerization of the vinyl-containing phosphonic acid present in the sheet-like structure obtainable according to step C).

1 .- 22 . (canceled) 
     
     
         23 . An electrode having a proton-conducting polymer coating comprising polymers containing phosphonic acid groups which is obtained by a process comprising the steps
 A) mixing at least 20% by weight of based on the total weight of the mixture of vinyl-containing phosphonic acid with one or more aromatic tetramino compounds with one or more aromatic carboxylic acids, esters thereof, acid halides thereof or anhydrides thereof which contain at least two acid groups per carboxylic acid monomer, and/or   
       mixing of vinyl-containing phosphonic acid with one or more aromatic and/or heteroaromatic diamino carboxylic acids, esters thereof, acid halides thereof or anhydrides thereof,
 B) heating of the mixture obtainable according to step A) under inert gas at temperatures of up to 350° C. to form a polyazole polymer, 
 C) application of a layer using the mixture from step A) and/or B) to a support, 
 D) polymerization of the vinyl-containing phosphonic acid present in the sheet-like structure obtainable according to step C). 
 
     
     
         24 . The electrode as claimed in  claim 23 , wherein the coating has a thickness in the range from 2 to 3,000 μm. 
     
     
         25 . The electrode as claimed in  claim 23 , wherein the coating has a thickness in the range from 3 to 2,000 μm. 
     
     
         26 . The electrode as claimed in  claim 23 , wherein the coating has a thickness in the range from 5 to 1,500 μm. 
     
     
         27 . A membrane-electrode unit comprising at least one electrode as claimed in  claim 23  and at least one membrane. 
     
     
         28 . A fuel cell comprising one or more membrane-electrode units as claimed in  claim 27 . 
     
     
         29 . A process for producing proton-conducting polymer membranes comprising polymers containing phosphonic acid groups, which comprises the steps
 A) mixing of one or more aromatic tetramino compounds with one or more aromatic carboxylic acids, esters thereof, acid halides thereof or anhydrides thereof which contain at least two acid groups per carboxylic acid monomer or   
       mixing of one or more aromatic and/or heteroaromatic diamino carboxylic acids, esters thereof, acid halides thereof or anhydrides thereof with vinyl-containing phosphonic acid,
 B) heating of the mixture obtainable according to step A) under inert gas at temperatures of up to 350° C. to form polyazole polymers, 
 C) application of a layer using the mixture from step A) and/or B) to a support, 
 D) polymerization of the vinyl-containing phosphonic acid. 
 
     
     
         30 . The electrode as claimed in  claim 23 , wherein the aromatic tetramino compounds are 3,3′,4,4′-tetraminobiphenyl, 2,3,5,6-tetraminopyridine, 1,2,4,5-tetraminobenzene, bis(3,4-diaminophenyl) sulfone, bis(3,4-diaminophenyl)ether, 3,3′,4,4′-tetraminobenzophenone, 3,3′,4,4′-tetraminodiphenylmethane or 3,3′,4,4′-tetraminodiphenyldimethylmethane. 
     
     
         31 . The electrode as claimed in  claim 23 , wherein the aromatic carboxylic acids are isophthalic acid, terephthalic acid, phthalic acid, 5-hydroxyisophthalic acid, 4-hydroxyisophthalic acid, 2-hydroxyterephthalic acid, 5-aminoisophthalic acid, 5-N,N-dimethylaminoisophthalic acid, 5-N,N-diethylaminoisophthalic acid, 2,5-dihydroxyterephthalic acid, 2,5-dihydroxyisophthalic acid, 2,3-dihydroxyisophthalic acid, 2,3-dihydroxyphthalic acid, 2,4-dihydroxyphthalic acid, 3,4-dihydroxyphthalic acid, 3-fluorophthalic acid, 5-fluoroisophthalic acid, 2-fluoroterephthalic acid, tetrafluorophthalic acid, tetrafluoroisophthalic acid, tetrafluoroterephthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, diphenic acid, 1,8-dihydroxynaphthalene-3,6-dicarboxylic acid, bis(4-carboxyphenyl)ether, benzophenone-4,4′-dicarboxylic acid, bis(4-carboxyphenyl) sulfone, biphenyl-4,4′-dicarboxylic acid, 4-trifluoromethylphthalic acid, 2,2-bis(4-carboxyphenyl)hexafluoropropane, 4,4′-stilbenedicarboxylic acid, 4-carboxycinnamic acid, or C1-C20-alkyl esters or C5-C12-aryl esters thereof, or anhydrides thereof or acid chlorides thereof. 
     
     
         32 . The electrode as claimed in  claim 23 , wherein the aromatic carboxylic acids are tricarboxylic acids, C1-C20-alkyl esters thereof, C5-C12-aryl esters thereof, anhydrides thereof or acid chlorides thereof or tetracarboxylic acids, C1-C20-alkyl esters thereof, C5-C12-aryl esters thereof, anhydrides thereof or acid chlorides thereof. 
     
     
         33 . The electrode as claimed in  claim 32 , wherein the aromatic carboxylic acids are 1,3,5-benzenetricarboxylic acid (trimesic acid); 2,4,5-benzenetricarboxylic acid (trimellitic acid); (2-carboxyphenyl)iminodiacetic acid, 3,5,3′-biphenyltricarboxylic acid; 3,5,4′-biphenyltricarboxylic acid, 2,4,6-pyridinetricarboxylic acid, benzene-1,2,4,5-tetracarboxylic acid; naphthalene-1,4,5,8-tetracarboxylic acid, 3,5,3′,5′-biphenyltetracarboxylic acid, benzophenonetetracarboxylic acid, 3,3′,4,4′-biphenyltetracarboxylic acid, 2,2′,3,3′-biphenyltetracarboxylic acid, 1,2,5,6-naphthalenetetracarboxylic acid or 1,4,5,8-naphthalenetetracarboxylic acid or mixtures thereof. 
     
     
         34 . The electrode as claimed in  claim 32 , wherein the content of tricarboxylic acids and/or tetracarboxylic acids is in the range from 0 to 30 mol % based on dicarboxylic acid used. 
     
     
         35 . The electrode as claimed in  claim 23 , wherein the heteroaromatic carboxylic acids are heteroaromatic dicarboxylic acids, heteroaromatic tricarboxylic acids and/or heteroaromatic tetracarboxylic acids containing at least one nitrogen, oxygen, sulfur or phosphorus atom in the aromatic. 
     
     
         36 . The electrode as claimed in  claim 35 , wherein the heteroaromatic carboxylic acids are pyridine-2,5-dicarboxylic acid, pyridine-3,5-dicarboxylic acid, pyridine-2,6-dicarboxylic acid, pyridine-2,4-dicarboxylic acid, 4-phenyl-2,5-pyridinedicarboxylic acid, 3,5-pyrazoledicarboxylic acid, 2,6-pyrimidinedicarboxylic acid, 2,5-pyrazinedicarboxylic acid, 2,4,6-pyridinetricarboxylic acid, benzimidazole-5,6-dicarboxylic acid, and also C1-C20-alkyl esters or C5-C12-aryl esters thereof, or anhydrides thereof or acid chlorides thereof or C1-C20-alkyl esters or C5-C12-aryl esters thereof or anhydrides thereof or acid chlorides thereof. 
     
     
         37 . The electrode as claimed in  claim 23 , wherein the aromatic diamino carboxylic acids are diaminobenzoic acid and/or monohydrochloride and dihydrochloride derivatives thereof. 
     
     
         38 . The electrode as claimed in  claim 23 , wherein the mixture prepared in step A) and/or step B) comprises compounds of the formula 
       
         
           
           
               
               
           
         
         where 
       
       R is a bond, a C1-C15-alkyl group, C1-C15-alkoxy group, ethylenoxy group or C5-C20-aryl or heteroaryl group, with the above radicals themselves being able to be substituted by halogen, —OH, COOZ, —CN, or NZ 2 ,
 the radicals Z are each, independently of one another, hydrogen, a C1-C15-alkyl group, C1-C15-alkoxy group, ethylenoxy group or C5-C20-aryl or heteroaryl group, with the above radicals themselves being able to be substituted by halogen, —OH, or —CN, and 
 x is 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, 
 y is 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, 
 and/or of the formula 
 
       
         
           
           
               
               
           
         
         where 
       
       R is a bond, a C1-C15-alkyl group, C1-C15-alkoxy group, ethylenoxy group or C5-C20-aryl or heteroaryl group, with the above radicals themselves being able to be substituted by halogen, —OH, COOZ—CN, or NZ 2 ,
 the radicals Z are each, independently of one another, hydrogen, a C1-C15-alkyl group, C1-C15-alkoxy group, ethylenoxy group or C5-C20-aryl or heteroaryl group, with the above radicals themselves being able to be substituted by halogen, —OH, or —CN, and 
 x is 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, 
 and/or of the formula 
 
       
         
           
           
               
               
           
         
         where 
       
       A is a group of the formulae COOR 2 , CN, CONR 2   2 , OR 2  and/or R 2 , where R 2  is hydrogen, a C1-C15-alkyl group, C1-C15-alkoxy group, ethylenoxy group or C5-C20-aryl or heteroaryl group, with the above radicals themselves being able to be substituted by halogen, —OH, COOZ, —CN, or NZ 2 , 
       R is a bond, a divalent C1-C15-alkylene group, divalent C1-C15-alkylenoxy group, for example ethylenoxy group, or divalent C5-C20-aryl or heteroaryl group, with the above radicals themselves being able to be substituted by halogen, —OH, COOZ, —CN, or NZ 2 ,
 the radicals Z are each, independently of one another, hydrogen, a C1-C15-alkyl group, C1-C 15-alkoxy group, ethylenoxy group or C5-C20-aryl or heteroaryl group, with the above radicals themselves being able to be substituted by halogen, —OH, or —CN, and 
 x is 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10. 
 
     
     
         39 . The electrode as claimed in  claim 23 , wherein the monomers which are capable of effecting crosslinking and have at least 2 carbon-carbon double bonds are polymerized in step D). 
     
     
         40 . The electrode as claimed in  claim 23 , wherein the polymerization in step D) is brought about by substance capable of forming free radicals. 
     
     
         41 . The electrode as claimed in  claim 23 , wherein the polymerization in step D) is effected by irradiation with IR or NIR light, UV light, β-rays, γ-rays and/or electron beams. 
     
     
         42 . The electrode as claimed in  claim 23 , wherein the mixture produced in step A) and/or step B) comprises dissolved, dispersed and/or suspended polymer. 
     
     
         43 . The electrode as claimed in  claim 23 , wherein a layer having a thickness of from 20 to 4000 μm is produced in step C). 
     
     
         44 . The electrode as claimed in  claim 23 , wherein the membrane formed in step D) has a thickness in the range from 15 to 3000 μm. 
     
     
         45 . The electrode as claimed in  claim 32 , wherein the content of tricarboxylic acids and/or tetracarboxylic acids is in the range 0.5 to 10 mol %, based on dicarboxylic acid used. 
     
     
         46 . The electrode as claimed in  claim 23 , wherein the electrode has a proton conductivity of at least 0.001 S/cm @ 120° C. 
     
     
         47 . The electrode as claimed in  claim 23 , wherein the electrode has a proton conductivity of at least 10 mS/cm @ 120° C. 
     
     
         48 . The electrode as claimed in  claim 23 , wherein the electrode has a proton conductivity of at least 20 mS/cm @ 120° C. 
     
     
         49 . The electrode as claimed in  claim 23 , wherein the vinyl-containing phosphonic acid is present in step A) in an amount of at least 30% by weight of based on the total weight of the mixture. 
     
     
         50 . The electrode as claimed in  claim 23 , wherein the vinyl-containing phosphonic acid is present in step A) in an amount of at least 50% by weight of based on the total weight of the mixture. 
     
     
         51 . The electrode as claimed in  claim 23 , wherein the polyzole polymer formed in step B) has recurring azole units in the polymer greater than or equal to 10. 
     
     
         52 . The electrode as claimed in  claim 23 , wherein the polyzole polymer formed in step B) has recurring azole units in the polymer greater than or equal to 100. 
     
     
         53 . The electrode as claimed in  claim 48 , wherein the polyzole polymer formed in step B) has recurring azole units in the polymer greater than or equal to 100 and wherein the vinyl-containing phosphonic acid is present in step A) in an amount of at least 50% by weight of based on the total weight of the mixture.