Comb polymers for supramolecular nanoconfinement
Polymers including pendent hydrophobic groups and pendent proton transfer groups are shown to form nanostructured films exhibiting greatly increased proton conductivity compared with films prepared from corresponding polymers lacking hydrophobic groups. The polymers can include repeating units each of which has both a hydrophobic group and a proton transfer group. Alternatively, the polymers can be the product of copolymerizing a first monomer with at least one hydrophobic group and a second monomer with at least one proton transfer group. The polymers are useful for the preparation of fuel cell proton exchange membranes.
1. A polymer, comprising:
a plurality of repeating units;
wherein each repeating unit comprises
a monovalent pendent hydrophobic group comprising about 5 to about 20 carbon atoms, and
a pendent proton transfer group bound to the repeating unit via a linking group; wherein the pendent proton transfer group is selected from the group consisting of
2. The polymer of claim 1 , wherein the pendent hydrophobic group is selected from the group consisting of C 5 -C 20 hydrocarbyl, C 5 -C 20 hydrocarbyloxyl, C 5 -C 20 partially fluorinated hydrocarbyl, C 5 -C 20 partially fluorinated hydrocarbyloxyl, C 5 -C 20 perfluorinated hydrocarbyl, and C 5 -C 20 perfluorinated hydrocarbyloxyl.
3. The polymer of claim 1 , wherein the pendent hydrophobic group is C 5 -C 20 perfluorinated hydrocarbyl.
4. The polymer of claim 1 , wherein the pendent proton transfer group is
5. The polymer of claim 1 , wherein the linking group is a divalent group comprising about 3 to about 10 aliphatic carbon atoms.
6. The polymer of claim 1 , wherein the repeating units have the structure
wherein X is the pendent proton transfer group, L is the linking group, and Y is the pendent hydrophobic group.
7. The polymer of claim 1 , wherein the repeating units have a structure selected from the group consisting of
wherein X is the pendent proton transfer group, L is the linking group, and Y is the pendent hydrophobic group.
8. The polymer of claim 1 , wherein the repeating units have a structure selected from the group consisting of
wherein X is the pendent proton transfer group, L is the linking group, Y is the pendent hydrophobic group, Z is —C(═O)— or —S(═O) 2 —, and R 1 is selected from the group consisting of hydrogen and C 1 -C 6 alkyl.
9. The polymer of claim 1 , wherein the repeating units have the structure
wherein X is the pendent proton transfer group, L is the linking group, and Y is the pendent hydrophobic group.
10. The polymer of claim 1 , wherein the repeating units have a structure selected from the group consisting of
wherein X is the pendent proton transfer group, L is the linking group, and Y is the pendent hydrophobic group.
11. The polymer of claim 1 , wherein the repeating units have a structure selected from the group consisting of
wherein X is the pendent proton transfer group, L is the linking group, and Y is the pendent hydrophobic group.
12. The polymer of claim 1 , wherein the repeating units have a structure selected from the group consisting of
wherein X is the pendent proton transfer group, L is the linking group, and Y is the pendent hydrophobic group.
13. A polymer, comprising:
a plurality of repeating units;
wherein each repeating unit comprises
a pendent hydrophobic group, and
a pendent proton transfer group bound to the repeating unit via a linking group;
wherein the repeating units are selected from the group consisting of
and combinations thereof.
14. A proton exchange membrane comprising the polymer of claim 1 .
15. A fuel cell comprising the proton exchange membrane of claim 14 .