Morphological Transition Induced by Nanoparticles in Dynamically Asymmetric PS/PVME Blends

Abstract

AbstractThe influence of hydrophilic SiO2 nanoparticles on the morphology of polystyrene (PS)/poly(vinyl methyl ether) (PVME) (10/90) blends in an unstable region has been investigated using optical microscopy and dynamic rheology techniques. For PS/PVME (10/90) blends annealed at 120 °C, the formation of a transient network structure and subsequent phase inversion indicates that a typical viscoelastic phase separation has occurred. However, for PS/PVME (10/90) blends filled with 4 wt.‐% SiO2 nanoparticles, a droplet‐like structure was formed immediately without the appearance of a network‐like structure. The rheological relaxation time of the blends suggested that the morphology transition observed in the PS/PVME/SiO2 (10/90/4) blend was related to the change in the dynamic asymmetry between the PS‐rich phase and the PVME‐rich phase, which was induced by the selective affinity of the SiO2 nanoparticles for PVME. After the incorporation of SiO2 nanoparticles, the PVME‐rich majority phase, which is originally the dynamically fast phase, became the slow phase, and led to a dynamic inversion compared with those unfilled blends.magnified image