TY  - JOUR
A1  - Pietsch, Ullrich
A1  - Bhattacharya, M. K.
A1  - Sanyal, M. K.
A1  - Geue, Thomas
T1  - Glass transition in Ultrathin Polymer Films : a Thermal Expansion Study
N2  - The glass transition process gets affected in ultrathin films having thickness comparable to the size of the molecules. We observe systematic broadening of the glass transition temperature (T-g) as the thickness of an ultrathin polymer film reduces below the radius of gyration but the change in the average T-g was found to be very small. The existence of reversible negative and positive thermal expansion below and above T-g increased the sensitivity of our thickness measurements performed using energy-dispersive x-ray reflectivity. A simple model of the T-g variation as a function of depth expected from sliding motion could explain the results
Y1  - 2005
ER  -