Abstract: A series of nano SiO₂/PEO composites with different compositions were prepared and studied by solid-state high-resolution NMR spectroscopy. The ¹H spin-spin relaxation time( t₂) of PEO in the composites was measured Via ¹H→ 13^C cross polarization. It is found that with the increase of nano-SiO₂ content, the crystallinity of PEO decreases greatly while the mobility of PEO chains in the noncrystalline region of PEO decreases dramatically. A model was suggested to describe the interfacial structure of the nano SiO₂/PEO composites based on the single exponential relaxation characteristic of the ¹H t₂ decay curve. Via ¹H→ ²⁹Sicross-polarization the dynamics of the hydroxyls lying on the surface of nano SiO₂ particles was also studied. The obtained result strongly suggests that at room temperature there exists an equilibrium of forming and breaking of the hydrogen bonds between the surface hydroxyl group and the ether oxygen.

Key words: Poly(ethylene oxide), Nano-SiO₂, Solid-state high-resolution NMR, Interfacial interaction, Polymer solid electrolyte