Polyurethaneureas (PUU), which were synthesized from 4,4'-diphenylmethane diisocyanate (MDI), polyethylene glycol) (PEG, MW = 2000), and 3,5-diaminobenzoic acid, were used as the matrix of the polyelectrolytes, in this study. Differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FT-IR), and Li-7 magic angle spinning (MAS) solid-state NMR were used to monitor changes in the morphology of PUU electrolytes corresponding to the concentration of lithium perchlorate (LiClO4) dopants. The results of DSC and FT-IR indicate the different polymer complexes formed by the interaction of the Li+ ions with the different coordination sites of PUU. The Li-7 MAS solid-state NMR investigation of the PUU electrolytes points out that two different Li+ environments exist at lower temperature. The results of DSC and the Li-7 MAS solid-state NMR show that Li+ ions are preferentially coordinated to the ether oxygen of the PEG soft-segment when the salt concentration is below 0.1 mmol LiClO4(gPUU)(-1). Impedance spectroscopy measurements show that the conductivity behavior followed the Arrhenius equation and was influenced by the hard-segment T-g. One of the PUU electrolytes under the investigation has an ionic conductivity as high as 3.0 x 10(-5) S cm(-1) at 30degreesC. (C) 2003 Elsevier Ltd. All rights reserved.