A Maximization of the Proton Conductivity of Sulfonated Poly(Ether Ether Ketone) with Grafted Segments Containing Multiple, Flexible Propanesulfonic Acid Groups.

To enhance the proton conductivity of sulfonated poly(ether ether ketone) (SPEEK), proton-conducting groups are required to be covalently connected to SPEEK and form proton-conducting channels. Herein, SPEEK fully grafted with segments containing multiple, flexible propanesulfonic acid groups (MS-SPEEK-102) is successfully prepared. Compared with SPEEK, MS-SPEEK-102 exhibits a higher proton conductivity of 8.3 × 10-2  S cm-1 at 80 °C with 98% relative humidity, and consequently a greater power density of 0.530 W cm-2 at 60 °C. These can be ascribed to the increased number of sulfonic acid groups, and ample, uninterrupted proton-conducting channels constructed by the movement of the maximum content, flexible side-chain segments. This approach offers an idea for obtaining a proton exchange membrane with good proton conductivity based on SPEEK.