Dynamics of polymer bilayer films

We report grazing incidence coherent X-ray measurements from polymer bilayers consisting of spun-cast layers of Polystyrene (PS) and Poly(4-bromo styrene) (PBrS) supported on silicon wafers. For PS/PBrS/Si bilayers, the films are stable and we are able to probe equilibrium thermal surface height fluctuations using X-ray Photon Correlation Spectroscopy (XPCS). When the layers are inverted to PBrS/PS/Si, the films de-wet. In this geometry we can measure both the non-equilibrium evolution of the film structure using time-resolved surface diffuse X-ray scattering and quasi-equilibrium fluctuations of the de-wetting film using XPCS.