Glass Transition in Polymer Thin Films

We investigated glass transition temperature Tg and thermal expansivity in polymer thin films using neutron and X-ray reflectivity measurements. In addition we studied dynamics of polymer thin films using inelastic and quasielastic neutron scattering.

Glass Transition temperature Tg

Thermal Expansivity

We found that glass transition temperature and thermal expansivity decrease with film thickness using XR and NR.

Polymer, 38, 3769 (2003)

Phys. Rev. E69, 022801 (2004)

Phys. Rev. E69, 06183 (2004)

Mean square displacement <u2>

Density of phonon states G(w)

We found decreases in mean square displacement <u2>as well as density of phonon states with film thickness by QENS. These results have been assigned to interface hard layer.

Interface hard layer

Phys. Rev. Lett., 95. 56102 (2005)

Phys. Rev. E74, 021801 (2006)