Comb-Like Poly(Ether-Sulfone) Membranes Derived from Planar 6,12-Diaryl-5,11-Dihydroindolo[3,2-b]Carbazole Monomer...

Highly conductive anion exchange membranes (AEMs), along with the ability to suppress swelling, are critical but challenging requirements for alkaline fuel cell applications. To achieve this criterion, a series of poly(ether sulfone)s (PESFs) with flexible alkyl imidazolium pendants attached directly on large planar 6,12-bis(4-hydroxyphenyl)-5,11-dihydroindolo[3,2-b]carbazole (DCP) units is reported. The planar DCP units stabilize the hydrophobic phase through strong π-π interactions and also facilitate the formation of ionic conducting channels through self assembly of hydrophilic pendants. The AEM prepared here, based on rational design, has a relatively low ion exchange capacity (IEC) of 1.86 × 10^-3 mol g^-1 and exhibits high hydroxide ion (OH^- ) conductivity of 101 × 10^-3 S cm^-1 , a low swelling ratio of 9.3% and a water uptake of 39.6%. Furthermore, the AEMs reported in this paper have excellent stability in 1 m NaOH solution at 80 °C over 500 h. Therefore, the synthesized polymers offer a new insight into the design of high performance materials for AEMs.