No abstract

Hybrid organic-inorganic two-phase nanocomposites of siloxane-poly(ethylene glycol) (SiO 3/2 -PEG) and siloxane-poly(propylene glycol) (SiO 3/2 -PPG) have been obtained by the sol-gel process. In these composites, nanometric siloxane heterogeneities are embedded in a polymeric matrix with covalent bonds in the interfaces. The structure of these materials was investigated in samples with different molecular weights of the polymer using the small-angle X-ray scattering (SAXS) technique. The SAXS spectra exhibit a well-defined peak that was attributed to the existence of a strong spatial correlation of siloxane clusters. LiClO 4 -doped siloxane-PEG and siloxane-PPG hybrids, which exhibit good ionic conduction properties, have also been studied as a function of the lithium concentration [O]/[Li], O being the oxygens of ether type. SAXS results allowed us to establish a structural model for these materials for different basic compositions and a varying [Li] content. The conclusion is consistent with that deduced from ionic conductivity measurements that exhibit a maximum for [O]/[Li] )15.

Hybrid organic-inorganic ionic conductors, also called ormolytes, were obtained by dissolution of LiClO 4 into silica/poly(ethylene glycol) matrices. Solid-state nuclear magnetic resonance (NMR) was used to probe the inorganic phase structure ( 29 Si) and the effects of the temperature and composition on the dynamic behavior of the ionic species ( 7 Li) and the polymer chains ( 1 H and 13 C). The NMR results between -100 and +90 °C show a strong correlation with ionic conductivity and differential scanning calorimetry experiments. The results also demonstrate that the cation mobility is assisted by segmental motion of the polymer, which is in agreement with the results previously reported for pure poly(ethylene oxide), PEO, electrolytes.