[en] We investigate the relation between the structure and the viscoelastic properties of a model polymer nanocomposite system based on a mixture of inorganic particles and poly(ethyleneoxide). Hydrophilic fumed silica nanoparticles were used as fillers and PEO-based nanocomposites were prepared by melt compounding and freeze-dryng. In both cases, dynamic oscillatory measurements in the melt state highlighted an increase of the frequency-dependent linear viscoelastic moduli with the filler content and a solid-like behaviour above a critical volume fraction. The freeze-dried samples exibhited a significant enhancement of the elasticity at lower filler contents as a result of the effect of particle dispersion on polymer chain dynamics.