Abstract
We report the first measurements of the glass transition temperature for thin freely standing polystyrene (PS) films. We have used Brillouin light scattering to measure for freely standing films of different thicknesses. We find that decreases linearly with film thickness for , with a reduction of 70 K for a film with . These measurements characterize unambiguously the effects of the free surface on of thin polymer films. Results are compared to similar results for supported PS films [Keddie et al., Europhys. Lett. 27, 59 (1994)], and we find that their measured values are influenced strongly by the substrate.
- Received 9 April 1996
DOI:https://doi.org/10.1103/PhysRevLett.77.2002
©1996 American Physical Society