Abstract
We have used Brillouin light scattering to make a detailed study of the behavior of the glass transition temperature in ultrathin, free-standing polystyrene films. The glass transitions were experimentally identified as near discontinuities in the thermal expansion. The effects of film thickness, molecular weight, and thermal history on the measured values have been investigated. While the size of the glass transition effects was comparable for all molecular weights, a complicated dependence suggested a separation of the results into two regimes, each dominated by a different length scale: a low regime controlled by a length scale intrinsic to the glass transition and a high region, where polymer chain confinement induced effects take over.
- Received 18 February 2000
DOI:https://doi.org/10.1103/PhysRevE.62.5187
©2000 American Physical Society