Eur. Phys. J. E (2005) 18: 143-148
https://doi.org/10.1140/epje/i2004-10158-1

Original Article

Qualitative discrepancy between different measures of dynamics in thin polymer films^⋆

¹ Department of Physics and Guelph-Waterloo Physics Institute, University of Waterloo, 200 University Ave. W., N2L 3G1, Waterloo, Ontario, Canada
² Department of Mechanical Engineering, University of Waterloo, N2L 3G1, Waterloo, Ontario, Canada

^* e-mail: jforrest@uwaterloo.ca

Received: 4 October 2004
Accepted: 26 July 2005
Published online: 7 October 2005

Abstract

We have used ellipsometry to measure the initial stages of interface healing in bilayer polystyrene films. We also used ellipsometry to measure the glass transition temperature T_g of the same or identically prepared samples. The results indicate that as the film thickness is decreased, the time constant for the interface healing process increases, while at the same time the measured glass transition temperature in the same samples decreases as the film thickness is decreased. This qualitative difference in the behavior indicates that it is not always possible to make inferences about one probe of polymer dynamics from measurements of another. We propose a reason for this discrepancy based on a previously discussed origin for reduction in the T_g value of thin films.