Related Experiment Video
Updated: May 19, 2026

Cooling Rate Dependent Ellipsometry Measurements to Determine the Dynamics of Thin Glassy Films
Published on: January 26, 2016
Modulus, confinement, and temperature effects on surface capillary wave dynamics in bilayer polymer films near the
Christopher M Evans1, Suresh Narayanan, Zhang Jiang
1Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, USA.
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.
Related Concept Videos
Surface Tension of Fluid
Surface tension varies with...
Surface Tension, Capillary Action, and Viscosity
The various IMFs between identical molecules of a substance are examples of cohesive forces. The molecules within a liquid are surrounded by other molecules and are attracted equally in all directions by the cohesive forces within the liquid. However, the molecules on the surface of a liquid are attracted only by about one-half as many molecules. Because of the unbalanced molecular attractions on the surface molecules, liquids contract to form a shape that minimizes the number...
Surface Tension

