Synthesis of Aromatic Anion Exchange Membranes by Friedel–Crafts Bromoalkylation and Cross-Linking of Polystyrene Block Copolymers
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- Rensselaer Polytechnic Inst., Troy, NY (United States). Dept. of Chemistry and Chemical Biology
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Pennsylvania State Univ., University Park, PA (United States). Dept. of Materials Science and Engineering
- New York Univ. (NYU), NY (United States). Dept. of Chemistry. Courant Inst. of Mathematical Sciences; NYU Shanghai (China). NYU-ECNU Center for Computational Chemistry
- Univ. of Tennessee, Knoxville, TN (United States). Dept. of Chemical & Biomolecular Engineering
- Rensselaer Polytechnic Inst., Troy, NY (United States). Dept. of Chemistry and Chemical Biology. Dept. of Chemical and Biological Engineering
Elastomeric anion exchange membranes (AEMs) were prepared here by acid-catalyzed Friedel–Crafts alkylation of the polystyrene block of polystyrene-b-poly(ethylene-co-butylene)-b-polystyrene (SEBS) using bromoalkylated tertiary alcohols and triflic acid as a catalyst, followed by amination with trimethylamine. This simple one-step bromoalkylation allowed convenient control of both the degree of functionalization and cation tether length by changing the molar ratio and the structure of the bromoalkylated tertiary alcohol. The resulting quaternary ammonium-functionalized ionic triblock SEBS copolymers showed a microphase-separated morphology on the 35 nm length scale. A series of AEMs with different ion exchange capacities and ion tether lengths were systematically investigated by comparing swelling and anion conductivity. Because the SEBS AEMs showed high swelling and low dimensional stability in water due to the rubbery nature of SEBS, the hard segment PS units were cross-linked by 1,6-hexanediamine for practical use. The cross-linking of SEBS AEMs reduced water uptake significantly (e.g., 155% vs 28%) and enhanced their mechanical properties. Because the backbone of the SEBS AEMs are composed of all carbon–carbon bonds, they showed good alkaline stability, preserving their IEC and OH– conductivity after testing in a 1 M NaOH solution at 80 °C for 500 h. Alkaline membrane fuel cell performance was evaluated with the cross-linked SEBS AEM, and a peak power density of 520 mW/cm2 was achieved at 60 °C under H2/O2 conditions.
- Research Organization:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Rensselaer Polytechnic Inst., Troy, NY (United States)
- Sponsoring Organization:
- USDOE Office of Energy Efficiency and Renewable Energy (EERE), Sustainable Transportation Office. Hydrogen Fuel Cell Technologies Office; USDOE Advanced Research Projects Agency - Energy (ARPA-E); USDOE Office of Science (SC); National Science Foundation (NSF)
- Grant/Contract Number:
- 89233218CNA000001; AR0000769; AC02-06CH11357; CHE 1534289
- OSTI ID:
- 1503188
- Report Number(s):
- LA-UR-18-28671
- Journal Information:
- Macromolecules, Vol. 52, Issue 5; ISSN 0024-9297
- Publisher:
- American Chemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
Web of Science
Cross‐Linked Spirocyclic Quaternary Ammonium‐Based Anion Exchange Membrane with Tunable Properties for Fuel Cell Applications
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journal | May 2019 |
Novel anion exchange membrane with low ionic resistance based on chloromethylated/quaternized‐grafted polystyrene for energy efficient electromembrane processes
|
journal | November 2019 |
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