Anion exchange membrane and methods of making and using the same
Anion exchange membrane and methods of making and using the same. In one embodiment, the anion exchange membrane may be made by a method that includes a two-step polymerization. In the first step, an α-olefin monomer containing a pendant halide, such as 8-bromo-1-octene, may be polymerized by Ziegler-Natta polymerization to form a first polymer portion, the first polymer portion being a homopolymer. In the second step, the polymerization is charged with a non-functionalized α-olefin monomer, such as ethylene, thereby forming a second polymer portion, the second polymer being a copolymer made up predominantly of the non-functionalized olefin monomer. If desired, a small amount of an α-olefin monomer containing a crosslinking functionality may be included in the first and/or second steps. Following the two-step polymerization, the polymer is fabricated into a thin film. Thereafter, the thin film may be functionalized by replacing the pendant halides with pendant cations.
1. An anion exchange membrane, the anion exchange membrane comprising a copolymer, the copolymer comprising first monomer units and second monomer units, wherein each of the first monomer units comprises an α-octene monomer unit containing a pendant ammonium group, and wherein each of the second monomer units comprises an ethylene monomer unit.
2. An anion exchange membrane, the anion exchange membrane comprising a copolymer, the copolymer comprising first monomer units and second monomer units, wherein each of the first monomer units comprises an α-octene monomer unit containing a pendant ammonium group, and wherein each of the second monomer units comprises a non-functionalized α-olefin monomer unit.
3. The anion exchange membrane as claimed in claim 2 , wherein the non-functionalized α-olefin monomer unit is selected from the group consisting of an ethylene monomer unit, a propylene monomer unit, a butylene monomer unit, and a 3-methyl-1-pentene monomer unit.
4. The anion exchange membrane as claimed in claim 3 , wherein the non-functionalized α-olefin monomer unit is a propylene monomer unit.
5. The anion exchange membrane as claimed in claim 2 , wherein the α-octene monomer unit containing a pendant ammonium group is an 8-halo-1-octene monomer unit containing a pendant ammonium group.
6. The anion exchange membrane as claimed in claim 5 , wherein the 8-halo-1-octene monomer unit containing a pendant ammonium group is selected from an 8-bromo-1-octene monomer unit containing a pendant ammonium group and an 8-chloro-1-octene monomer unit containing a pendant ammonium group.
7. The anion exchange membrane as claimed in claim 5 , wherein the 8-halo-1-octene monomer unit containing a pendant ammonium group is an 8-bromo-1-octene monomer unit containing a pendant ammonium group.
8. The anion exchange membrane as claimed in claim 2 , wherein the α-octene monomer unit containing a pendant ammonium group constitutes about 10% to about 50% of the copolymer.
9. The anion exchange membrane as claimed in claim 8 , wherein the α-octene monomer unit containing a pendant ammonium group constitutes about 10% to about 15% of the copolymer.
10. The anion exchange membrane as claimed in claim 2 , wherein the pendant ammonium group is selected from the group consisting of trimethylammonium, N-methyl-piperidinium, N-methyl-pyrrolidinium, 1-methylimidazolium, and 1,2-methylimidazolium.
11. The anion exchange membrane as claimed in claim 10 , wherein the pendant ammonium group is trimethylammonium.