Fig. 16.a. Ion conductivity isotherms of aqueous KOH (open symbols) and of mes-PBI equilibrated in the corresponding KOH solutions (solid symbols); b. Mn relative to initial Mn for mes-PBI and m-PBI18 at different durations of aging in 10 and 50wt% aqueous KOH at 88 oC. Reproduced with permission of Ref. [63]. Copyright 2017, Royal Society of Chemistry.