ABSTRACT: We report relaxation times (τ) for surface capillary waves on 27-127 nm polystyrene (PS) top layers in bilayer films using x-ray photon correlation spectroscopy. At ∼10 °C above the PS glass transition temperature (T(g)), τ tracks with underlayer modulus, being significantly smaller on softer substrates at low in-plane scattering wave vector. Relative to capillary wave theory, we also report stiffening behavior upon nanoconfinement of the PS layers. At PS T(g)+40 °C, both effects become negligible. We demonstrate how neighboring polymer domains impact dynamics over substantial length scales.
Physical Review Letters 07/2012; 109(3):038302. · 7.37 Impact Factor