“…However, leaching of the mobile (e.g., liquid) molecules by water remains a severe problem when used in fuel cells. [5] More recently, proton conducting polymers with tethered phosphonic acid, [22] imidazole, [23] and benzimidazole [24] moieties have been prepared. Both, proton conductivities and the proton diffusion coefficients of phosphonic acid, imidazole, and their derivatives tethered to small molecules and various oligomers have been studied by Kreuer and coworkers.…”