| Abstract: | Polyurea, which was synthesized from 4,4′‐diphenylmethane diisocyanate, Jeffamine‐ED2001 (weight‐average molecular weight: 2000), and 3,5‐diaminobanzoic acid (DABA) were doped with lithium perchlorate (LiClO4) as the polyelectrolyte. Differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, and 7Li magic‐angle spinning (MAS) solid‐state NMR were used to monitor changes in the morphology of polyurea electrolytes corresponding to the concentration of LiClO4 dopants. DSC showed the glass‐transition temperature of the hard and soft segments increases with salt concentration. FTIR indicated the carboxylic group of DABA coordinates with the Li+ ion, and the ordered hydrogen‐bonded urea carbonyl groups are destroyed when the salt concentration exceeds 0.5 mmole of LiClO4 (gPUrea)?1. The 7Li MAS solid‐state NMR investigation of the polyurea electrolytes revealed the presence of two Li+ environments at lower temperature. Impedance spectroscopy measurements showed that the conductivity behavior followed the Arrhenius equation, and the maximum conductivity occurred when the crystalline structure of polyurea was disrupted. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 4007–4016, 2003 |
