In this study, a series of polyether-ester ionomers was prepared by neutralizing the carboxylic acid groups in 1 : 1 copolymers of benzenetracarboxylic dianhydride (BTDA) and poly(tetramethylene oxide) or poly(ethylene oxide) glycol. The base polymers were in a liquid state while the ionomers were in solid state and a separate ionic phase was formed. The local structure and the morphology of the ionomers were investigated by dynamic mechanical analysis, Fourier transform infrared spectroscopy, and small-angle x-ray scattering as well as extended x-ray absorption fine structure. Clearly, the geometric structure of the ionic sites varied with the nature of the metal ions and the morphology of the ionomers was determined by the microstructure of the ion aggregates.