title: Molecular weight dependence of reductions in the glass transition temperature of thin, freely standing polymer films.
abstract: We have used transmission ellipsometry to perform a comprehensive study of the glass transition temperature T(g) of freely standing polystyrene films. Six molecular weights M(w), ranging from 575 x 10(3) to 9100 x 10(3), were used in the study. For each M(w) value, large reductions in T(g) (as much as 80 degrees C below the bulk value) were observed as the film thickness h was decreased. We have studied in detail the dependence of the T(g) reductions on M(w) in a regime dominated by chain confinement effects. The empirical analysis presented is highly suggestive of the existence of a mechanism of mobility in thin freely standing films that is inhibited in the bulk and distinct from the usual cooperative motion associated with the glass transition.
authors: Department of Physics and the Guelph-Waterloo Physics Institute, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
authors: K
authors: K
authors: Dalnoki-Veress
authors: J A
authors: JA
authors: Forrest
authors: C
authors: C
authors: Murray
authors: C
authors: C
authors: Gigault
authors: J R
authors: JR
authors: Dutcher