Addition of nanoparticles to a polymer matrix is known to alter, and often enhance, the mechanical, thermal and barrier properties of the materials. When nanoparticles (NPs) are added to a polymer-polymer additional factors need to be considered which may affect the thermodynamic behaviour and morphology of the blend. Recently the phase behaviour of blends incorporating TNPs has been studied but no experiments have been made on blends in which one of the components is grafted onto the NP. The proposed SANS investigation makes use of chain-grafted samples recently prepared in our laboratory and aims to investigate how grafting polystyrene chains onto the surface of two different silica NPs affects the phase behaviour of PS/poly(vinyl methyl ether) blends.