Anion exchange ionomer with a poyarylene backbone and anion exchange membrane incorporating same
An anion exchange ionomer is disclosed that contains a fluorinated, ether-free backbone, and a fluorinated ether based quaternary ammonium functional group. The novel polymer has improved chemical and mechanical stability as compared to the state-of-the-art materials for incorporation in anion exchange membrane. The disclosed anion exchange ionomer may be incorporated into an anion exchange membrane and used in electrochemical applications.
1. An anion exchange ionomer comprising:
a) a polyphenylene backbone bonded with a fluorinated alkyl halide;
b) a side chain comprising said fluorinated alkyl halide; and
c) a quaternary ammonium functional group bonded to the fluorinated alkyl halide of said side chain.
2. The anion exchange ionomer of claim 1 , wherein the backbone comprises a tetrafluoroethylene compound.
3. The anion exchange ionomer of claim 1 , wherein the backbone comprises a polyphenylene compound.
4. An anion exchange membrane comprising the polymer of claim 1 and a porous scaffold.
5. The anion exchange membrane of claim 4 , wherein the porous scaffold is comprises poly(tetrafluoroethylene).
6. The anion exchange membrane of claim 5 , wherein the porous polytetrafluoroethylene is expanded polytetrafluoroethylene.
7. The anion exchange membrane of claim 4 , wherein the porous scaffold is selected from the group consisting of: polyethylene, polypropylene, polyether-ether-ketone (PEEK), and poly(tetrafluoroethylene).
8. The ion exchange membrane of claim 7 , wherein a thickness of the exchange membrane is no more than 50 μm.
9. The ion exchange membrane of claim 7 , wherein a thickness of the exchange membrane is no more than 25 μm.
10. A method of making the anion exchange ionomer of claim 1 , comprising:
a) reacting polyphenylene with fluoroalkyl ketone in the presence of a strong acid having a pH of no more than 2.0;
b) converting a terminal group of said side chain to quaternary ammonium hydroxide group.
11. The method of making the anion exchange ionomer of claim 10 , wherein the strong acid has a pH of no more than 1.0.
12. The method of making the anion exchange ionomer of claim 10 , wherein the strong acid has a pH of no more than 0.5.
13. The method of making the anion exchange ionomer of claim 10 , wherein the strong acid triflic acid.
14. The anion exchange ionomer of claim 1 , comprising a pyridinium functional group.
15. The anion exchange ionomer of claim 1 , comprising a piperidinium functional group.
16. The anion exchange ionomer of claim 1 , comprising a tetramethylammonium functional group.