Dynamic Heterogeneity in Fully Miscible Blends of Polystyrene with Oligostyrene

Binary blends of polystyrene with oligostyrene are perfectly miscible (chi = 0) yet dynamically heterogeneous. This is evidenced by independent probing of the dipole relaxation perpendicular to the backbone by dielectric spectroscopy and molecular dynamics. The self-concentration model with a single intramolecular length scale qualitatively describes the slower segmental dynamics. A quantitative comparison based on MD, however, requires a composition-dependent length scale. The pertinent dynamic length scale that best describes the slow segmental dynamics in miscible blends relates to both intra-and intermolecular contributions. DOI: 10.1103/PhysRevLett.110.165701