Benzimidazole-containing sulfonated polyethersulfones
View Patent ↗Sulfonated polyethersulfones and polymer compositions comprising sulfonated polyethersulfones and at least one inorganic heteropolyacid are useful as proton exchange membranes for fuel cells. The polyethersulfones include structural units derived from at least one biphenol monomer and a monomer of formula I wherein X is O, S or NR 1 ; Y is N or CR 5 ; R 1 , R 2 , R 3 and R 4 are independently hydrogen, alkyl, substituted alkyl, aryl, substituted aryl, alkylaryl, substituted alkylaryl, arylalkyl or substituted arylalkyl, or R 3 and R 4 , taken together, form a 5- or 6-membered substituted or unsubstituted aliphatic or aromatic ring; R 5 is hydrogen, alkyl, substituted alkyl, aryl, substituted aryl, alkylaryl, substituted alkylaryl, arylalkyl or substituted arylalkyl; and L is a direct bond or a divalent aromatic linker containing 6-12 carbons.
1. A polymer composition comprising a sulfonated polyethersulfone and at least one inorganic heteropolyacid, said polyethersulfone comprising structural units derived from at least one biphenol monomer and a monomer of formula I
wherein X is O, S or NR 1 ;
Y is N or CR 5 ,
R 1 , R 2 , R 3 and R 4 are independently hydrogen, alkyl, substituted alkyl, aryl, substituted aryl, alkylaryl, substituted alkylaryl, arylalkyl or substituted arylalkyl, or
R 3 and R 4 , taken together, form a 5- or 6-membered substituted or unsubstituted aliphatic or aromatic ring;
R 5 is hydrogen, alkyl, substituted alkyl, aryl, substituted aryl, alkylaryl, substituted alkylaryl, arylalkyl or substituted arylalkyl; and
L is a direct bond or a divalent aromatic linker containing 6-12 carbons.
2. A polymer composition according to claim 1 , wherein the polyethersulfone comprises structural units derived from a dihalodiarylsulfone.
3. A polymer composition according to claim 2 , wherein the polyethersulfone comprises structural units derived from at least one sulfonated dihalodiarylsulfone.
4. A polymer composition according to claim 1 , wherein X is NR 1 .
5. A polymer composition according to claim 1 , wherein Y is N and R 1 is H.
6. A polymer composition according to claim 1 , wherein R 2 is hydrogen.
7. A polymer composition according to claim 1 , wherein R 3 and R 4 are taken together and form a 6-membered aromatic ring.
8. A polymer composition according to claim 1 , wherein L is a direct bond.
9. A polymer composition according to claim 1 , wherein R 2 , R 3 and R 4 are hydrogen.
10. A polymer composition according to claim 1 , comprising about 1-25 mol % of the structural units derived from the monomer of formula I.
11. A polymer composition according to claim 1 , comprising about 2-15 mol % of the structural units derived from of the monomer of formula I.
12. A polymer composition according to claim 1 , comprising about 2-7 mol % of the structural units derived from of the monomer of formula I.
13. A polymer composition according to claim 1 , comprising about 5 mol % of the structural units derived from of the monomer of formula I.
14. A polymer composition according to claim 2 , wherein about 30-70 mol % of the structural units derived from the dihalodiarylsulfone are sulfonated.
15. A polymer composition according to claim 2 , wherein about 40-60 mol % of the structural units derived from the dihalodiarylsulfone are sulfonated.
16. A polymer composition according to claim 2 , wherein about 40 mol % of the structural units derived from the dihalodiarylsulfone are sulfonated.
17. A polymer composition according to claim 1 , wherein the inorganic heteropolyacid is phosphotungstic acid.
18. A polymer composition according to claim 1 , comprising about 20-70 parts heteropolyacid and 30-80 parts sulfonated polyethersulfone.
19. A polymer composition according to claim 1 , comprising about 40-60 parts heteropolyacid and 40-60 parts sulfonated polyethersulfone.
20. A polymer composition according to claim 1 , comprising about 50 parts heteropolyacid and 50 parts sulfonated polyethersulfone.
21. A membrane comprising a polymer composition according to claim 1 .
22. A polymer composition comprising a sulfonated polyethersulfone and phosphotungstic acid, said polyethersulfone comprising structural units derived from a 4,4′-dihalodiphenylsulfone, a sulfonated 4,4′-dihalodiphenylsulfone, biphenol and 2-(3′,5′-dihydroxyphenyl)benzimidazole.
23. A polymer composition according to claim 22 , wherein the polyethersulfone comprises about 40 mol % of the sulfonated 4,4′-dihalodiphenylsulfone.
24. A polymer composition according to claim 22 , wherein the sulfonated polyethersulfone comprises about 5-10 mol % 2-(3′,5′-dihydroxyphenyl)benzimidazole.
25. A polymer composition according to claim 22 , wherein the sulfonated polyethersulfone comprises about 30-50 weight % phosphotungstic acid.
26. A fuel cell comprising a membrane according to claim 21 .