A simple view of $T_g$ measurements in thin polymer films

ORAL

Abstract

In the past two decades, there have been numerous measurements of the glass transition temperature, $T_g$, in thin polymer films. These results have been the subject of significant controversy. While it does appear that the surface of glassy polymer films exhibits an anomalously high mobility, how this results in measured values of $T_g$ less than that of the bulk is not yet clear. Here we present a simple model that shows how an enhanced surface mobility that penetrates into the material with a characteristic length scale can lead to what appears as a reduced dilatometric $T_g$. We will show that despite the strong similarities to a $T_g$ measurement, the signature observed in experiments does not necessarily correspond to a glass transition in the thin polymer film.

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Authors

  • James A. Forrest

    University of Waterloo

  • Miriam Rafailovitch

    McMaster University, Department of Physics and Astronomy, McMaster University, Hamilton, ON, Canada, Department of Physics and Astronomy, McMaster University, Hamilton, Ontario, Canada, L8S 4M1, Department of Physics \& Astronomy, McMaster University, Hamilton, ON, Canada, L8S 4M1, Department of Physics \& Astronomy and the Brockhouse Institute for Materials Research, McMaster University, Hamilton, ON, Canada, Department of Physics and Astronomy, McMaster University, SUNY-Stony Brook