COMPLEX IMPEDANCE AND MULTIFREQUENCY NA-23 NMR-STUDY OF POLY(PROPYLENE OXIDE) COMPLEXED WITH NAB(C6H5)4

Complex impedance and multifrequency Na23 nuclear magnetic resonance (NMR) measurements on a poly (propylene oxide) :sodium tetraphenylborate, PPO8NaB(C6H5)4, solid polymer electrolyte, with a composition of eight ether oxygens per sodium, are reported. The NMR linewidths are found to be second-order quadrupole broadened, thus indicating low site-symmetry for the Na+ ions. The title compound exhibits some interesting differences in properties compared to other PPO-Na salt complexes, including an anomalously low value of the stretched exponential parameter beta-se (obtained in fits to electric modulus data), an unusually high glass transition temperature (T(g) = 306 K), and sub-T(g) line narrowing of lower frequency Na-23 resonances. This last phenomenon is attributed to strong interaction between the Na+ ions and their large [B(C6H5)4] - counterions caused by the localization of the [B(C6H5)4]- anions in weak interactions with the polymer chains which, in turn, leads to the elevated glass transition temperatures.