Composite ion exchange membrane and method of making same
An anion exchange membrane is made by mixing 2 trifluoroMethyl Ketone [nominal] (1.12 g, 4.53 mmol), 1 BiPhenyl (0.70 g, 4.53 mmol), methylene chloride (3.0 mL), trifluoromethanesulfonic acid (TFSA) (3.0 mL) to produce a pre-polymer. The pre-polymer is then functionalized to produce an anion exchange polymer. The pre-polymer may be functionalized with trimethylamine in solution with water. The pre-polymer may be imbibed into a porous scaffold material, such as expanded polytetrafluoroethylene to produce a composite anion exchange membrane.
1. A method of making a composite ion exchange membrane comprising the steps of:
a) providing a porous scaffold material having pores and selected from the group of porous polyolefin and porous fluoropolymer;
b) preparing a pre-polymer by mixing:
i) 2 trifluoromethyl ketone;
ii) 1 biphenyl;
iii) methylene chloride; and
iv) trifluoromethanesulfonic acid,
for a mixing time and temperature to produce said pre-polymer;
c) providing a functional polymer selected from the group consisting of: hydroxide halide and oxyanions;
d) surface modifying the porous scaffold material to produce a hydrophilic porous scaffold;
e) imbibing the pre-polymer into the pores of said porous scaffold material and subsequently
functionalizing the pre-polymer by contacting the pre-polymer with a trimethylamine solution to produce said composite ion exchange membrane having quaternized ammonium hydroxide functional groups, wherein the prepolymer is functionalized into to produce an ion exchange polymer.
2. The method of making an anion exchange membrane of claim 1 , wherein the porous scaffold material consists of porous polyolefin.
3. The method of making a composite ion exchange membrane of claim 1 , wherein the porous polyolefin comprises polyethylene.
4. The method of making a composite ion exchange membrane of claim 1 , wherein the porous scaffold material is a porous polyethylene film.
5. The method of making an ion exchange membrane of claim 1 , wherein the porous scaffold material consists of expanded ultra-high molecular weight polyethylene.
6. The method of making a composite ion exchange membrane of claim 1 , wherein the scaffold material consists of expanded polytetrafluoroethylene.
7. The method of making an ion exchange membrane of claim 6 , further comprising surface modifying the expanded polytetrafluoroethylene membrane to produce a hydrophilic expanded polytetrafluoroethylene membrane.
8. The method of making an ion exchange membrane of claim 7 , wherein surface modifying comprises treatment of the expanded polytetrafluoroethylene membrane with UV light.
9. The method of making an ion exchange membrane of claim 7 , wherein surface modifying comprises treatment with a surfactant.
10. The method of making an ion exchange membrane of claim 7 , wherein surface modifying comprises treatment with an ion exchange medium.
11. The method of making an ion exchange membrane of claim 1 , wherein the ion exchange polymer is cationic.
12. The method of making an ion exchange membrane of claim 1 , wherein the ion exchange polymer is anionic.