Search

X-ray Photon Correlation Spectroscopy (XPCS) was employed in a surface standing wave geometry in order to resolve the thermally diffusive in-plane dynamics at both the surface/vacuum (top) and polymer/polymer (bottom) interfaces of a thin Polystyrene (PS) film on top of Poly (4-bromo styrene) (PBrS) and supported on a Si substrate. The top vacuum interface shows two relaxation modes: one fast and one slow, while the buried polymerpolymer interface shows a single slow mode. The slow mode of the top interface is similar in magnitude and wavevector dependence to the single mode of the buried interface. The dynamics are consistent with a low-viscosity mixed layer between the PS and PBrS and coupling of the capillary wave fluctuations between this layer and the PS.