Polymer dispersant addition to fuel cell electrode inks for improved manufacturability

1. An ink composition for forming fuel cell electrodes, the ink composition comprising:

a catalyst composition;

a polymeric binder;

a polymer dispersant comprising a polymer segment including a perfluorocyclobutyl group; and

a solvent.

2. The ink composition of claim 1 wherein the catalyst composition comprises a precious metal.

3. The ink composition of claim 1 wherein the catalyst composition further comprises a catalyst support.

4. The ink composition of claim 3 wherein the weight ratio of polymer dispersant to catalyst support is from about 0.05 to 0.2.

5. The ink composition of claim 3 wherein the weight ratio of precious metal or precious metal oxide to support is from about 0.2 to 0.8.

6. The ink composition of claim 1 wherein the catalyst composition is present in an amount from about 1 to 6 weight percent of the total weight of the ink composition.

7. The ink composition of claim 1 wherein the polymeric binder is present in an amount from about 1 to about 5 weight percent of the total weight of the ink composition.

8. The ink composition of claim 1 wherein the polymer dispersant is present in an amount of 0.5 to 5 weight percent of the total weight of the ink composition.

9. The ink composition of claim 1 wherein the polymer segment including a perfluorcyclobutyl group has the following formula:

10. The ink composition of claim 7 wherein the polymer dispersant includes a hydrophobic region and a hydrophilic region.

11. The ink composition of claim 10 wherein the hydrophilic region has an ion exchange capacity from about 1 to about 4 meq per gram.

12. The ink composition of claim 1 wherein the polymer dispersant includes a hydrophilic polymer region comprising polymer segment 2 and a hydrophobic polymer region comprising polymer segment 3:

[E 1 (Z 1 ) d ]—P 1 -Q 1 -P 2   2

E 2 -P 3 -Q 2 -P 4   3

wherein:

Z 1 is —SO 2 X, —PO 3 H 2 , or —COX;

E 1 is an aromatic containing moiety;

E 2 is an unsulfonated aromatic-containing and/or aliphatic-containing moiety;

X is an —OH, a halogen, an ester, or

d is the number of Z 1 attached to E 1 ;

P 1 , P 2 , P 3 , P 4 are each independently absent, —O—, —S—, —SO—, —CO—, —SO 2 —, —NH—, NR 2 —, or —R 3 —;

R 2 is C 1-25 alkyl, C 1-25 aryl or C 1-25 arylene;

R 3 is C 1-25 alkylene, C 1-25 perfluoroalkylene, perfluoroalkyl ether, alkylether, or C 1-25 arylene;

R 4 is trifluoromethyl, C 1-25 alkyl, C 1-25 perfluoroalkylene, C 1-25 aryl, or another E 1 group; and

Q 1 , Q 2 are each independently a fluorinated cyclobutyl moiety.

13. The ink composition of claim 1 wherein the polymer dispersant includes a hydrophilic polymer region comprising polymer segment 4 and a hydrophobic polymer region comprising polymer segment 5:

wherein:

Z 1 is —SO 2 X, —PO 3 H 2 , or —COX;

E 1 , E 2 are each independently an aromatic-containing and/or aliphatic-containing moiety;

X is an —OH, a halogen, an ester, or

d is the number of Z 1 attached to R 8 ;

P 1 , P 2 , P 3 , P 4 are each independently absent, —O—, —S—, —SO—, —CO—, —SO 2 —, —NH—, NR 2 —, or —R 3 —;

R 2 is C 1-25 alkyl, C 1-25 aryl or C 1-25 arylene;

R 3 is C 1-25 alkylene, C 1-25 perfluoroalkylene, perfluoroalkyl ether, alkylether, or C 1-25 arylene;

R 4 is trifluoromethyl, C 1-25 alkyl, C 1-25 perfluoroalkylene, C 1-25 aryl, or another E 1 group;

R 8 (Z 1 ) d is a moiety having d number of protogenic groups; and

Q 1 , Q 2 are each independently a fluorinated cyclobutyl moiety.

14. The ink composition of claim 1 wherein the polymer dispersant includes a hydrophilic polymer region comprising polymer segment 6 and a hydrophobic polymer region comprising polymer segment 7:

E 1 (SO 2 X) d —P 1 -Q 1 -P 2   6

E 2 -P 3 -Q 2 -P 4   7

connected by a linking group L 1 to form polymer units 8 and 9:

wherein:

Z 1 is —SO 2 X, —PO 3 H 2 , or —COX;

E 1 is an aromatic-containing moiety;

E 2 is an unsulfonated aromatic-containing and/or aliphatic-containing moiety;

L 1 is a linking group;

X is an —OH, a halogen, an ester, or

d is a number of Z 1 functional groups attached to E 1 ;

P 1 , P 2 , P 3 , P 4 are each independently absent, —O—, —S—, —SO—, —SO 2 —, —CO—, —NH—, NR 2 —, —R 3 —, and

R 2 is C 1-25 alkyl, C 1-25 aryl or C 1-25 arylene;

R 3 is C 1-25 alkylene, C 1-25 perfluoroalkylene, or C 1-25 arylene;

R 4 is trifluoromethyl, C 1-25 alkyl, C 1-25 perfluoroalkylene, C 1-25 aryl, or another E 1 group;

Q 1 , Q 2 are each independently a fluorinated cyclobutyl moiety;

i is a number representing repetition of polymer segment 6; and

j is a number representing repetition of polymer segment 7.

15. The ink composition of claim 1 wherein the polymer dispersant includes a hydrophilic polymer region comprising polymer segment 10 and a hydrophobic polymer region comprising polymer segment 11:

E 1 (Z 1 ) d —P 1 -Q 1 -P 2   10

E 2 (Z 1 ) f —P 3   11

wherein:

Z 1 is a —SO 2 X, —PO 3 H 2 , or —COX;

E 1 , E 2 are each independently an aromatic or aliphatic-containing moiety wherein at least one of E 1 and E 2 include an aromatic substituted with Z 1 ;

X is an —OH, a halogen, an ester, or

d is the number of Z 1 functional groups attached to E 1 ;

f is the number of Z 1 functional groups attached to E 2 ;

P 1 , P 2 , P 3 are each independently absent, —O—, —S—, —SO—, —SO 2 —, —CO—, —NH—, NR 2 —, or —R 3 —;

R 2 is C 1-25 alkyl, C 1-25 aryl, or C 1-25 arylene;

R 3 is C 1-25 alkylene, C 1-25 perfluoroalkylene, perfluoroalkyl ether, alkyl ether, or C 1-25 arylene;

R 4 is trifluoromethyl, C 1-25 alkyl, C 1-25 perfluoroalkylene, C 1-25 aryl, or another E 1 group; and

Q 1 is a fluorinated cyclobutyl moiety,

with the proviso that when d is greater than zero, f is zero and when f is greater than zero d is zero.