Small-Angle X-ray Scattering Study of Sol−Gel-Derived Siloxane−PEG and Siloxane−PPG Hybrid Materials

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.