@article{PietschBhattacharyaSanyaletal.2005,
  author    = {Pietsch, Ullrich and Bhattacharya, M. K. and Sanyal, M. K. and Geue, Thomas},
  title     = {Glass transition in Ultrathin Polymer Films : a Thermal Expansion Study},
  year      = {2005},
  abstract  = {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},
  language  = {en}
}