Pyridinium-functionalized crosslinked anion exchange membrane based on multication side chain tethered elastomeric triblock poly(styrene-b-(ethylene-co-butylene)-b-styrene)

摘要

Hydroxide ion conductivity and long-term chemical stability play an important role in the development of anion exchange membranes (AEMs) for application of alkaline anion exchange membrane fuel cells (AAEMFCs). Herein, the high alkaline stable elastomeric triblock copolymer, poly(styrene-b-(ethylene-co-butylene)-b-styrene) (SEBS) with pendent multi-cation side chain and 4,4-bipyridine was develop for AEMs. The three cations in a side chain were tethered to the SEBS backbone and the length of the spacer between cations was six methylene (-CH2-) groups (TNQN). More importantly, the 4,4-bipridine was introduced to the membranes as the crosslinker and functional groups, which exhibited the significant improvement in hydroxide ion conductivity of the membranes. The hydroxide conductivity of the cross-linked quaternized SEBS (TNQN-SEBS-Bpy) membranes was 30.41-69.04 mS.cm(-1) from 30 degrees C to 80 degrees C, which could be ascribed to well micromorphology and more functional groups. Compared to the uncross-linked TNQN-SEBS, the TNQN-SEBS-Bpy membranes showed higher mechanical property and thermal stability. All the membranes exhibited good alkaline stability which the hydroxide conductivity maintained above 90% of the original ionic conductivity after 300 h of alkaline treatment (1 M aqueous NaOH) at 80 degrees C. Based on these outstanding properties, the cross-linked membranes show great potential application as alkaline anion exchange membranes.