Molecular weight dependence of reductions in the glass transition temperature of thin, freely standing polymer films

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) …