Poly(ether sulfone)s with pendent imidazolium for anion exchange membranes via click chemistry

Abstract

A new monomer, propargyl-1-methylimidazolium bromide, is synthesized. A series of poly(ether sulfone)s with pendent imidazolium (PES-Im-x) are synthesized from poly(ether sulfone)s with azide via nucleophilic polycondensation, bromination, and azidation, which are then reacted with propargyl-1-methylimidazolium bromide via click chemistry. The membranes are prepared sequentially via solution casting and ion exchange, which exhibit good alkaline stability under basic and elevated temperature conditions. The micro-phase separation of the membranes is observed on transmission electron microscopy. The conductivities of the membranes achieve in the range of 3.53 × 10−2 to 5.76 × 10−2 S cm−1 at 80 °C, which are related to the introduction of dense imidazolium groups on the side chains of the polymers. The designed structure facilitates the aggregation and transport of the ions in the membranes. The membrane electrode assembly based on PES-Im-38 with a power density of 18.0 mW cm−2 at 60 °C is obtained. In addition, all these membranes show good dimensional stability and thermal stability. It is demonstrated that click reaction may provide a viable strategy for the further preparation of high performance anion exchange membranes.