Controllable Cross-Linking Anion Exchange Membranes with Excellent Mechanical and Thermal Properties

A new monomer called 2,2-(4,4-oxydiphenol-4,4-diyl)bis(2-methyl-2,3,3a,4,7,7a-hexahydro-1H-4,7-methanoisoindol-2-ium) iodide (d(3)) is synthesized possessing both cross-linker and functional groups. The membranes are formed by copolymerizing d(3) with norbornene and (3aR,4S,7R,7aS)-2-methyl-2-(3-(trimethylammonio)propyl)-2,3,3a,4,7,7a-hexahydro-1H-4,7-methanoisoindol-2-ium iodide (a(3)) at varying ratios. The water uptake is 41.35% at 60 degrees C, and ion exchange capacity is 2.35 mequiv g(-1) for a mole ratio of a(3), norbornene, and d(3) (1:6:3). The conductivity is 12, 37, and 40 mS cm(-1) when d(3) is decreased. Meanwhile, the conductivity increases quickly with increasing the temperature. Furthermore, the mechanical properties and thermal properties are improved, attributed to the increased cross-linker. The membrane has a tensile strength of 41.3 MPa and the elongation at break of 38.0 %, and the 5 wt% loss temperature for membrane is approximate to 159 degrees C. The H-2/O-2 single fuel cells with this membrane show a maximum power density of 124 mW cm(-2) at 50 degrees C. The cross-linked membranes demonstrate high-dimensional stability in alkaline solution.