Glass transition and chain mobility in thin polymer films

We review recent work on the motion of polymer molecules confined to thin films. There has been considerable experimental evidence for large reductions in the glass transition temperature T, with decreasing film thickness, indicative of enhanced segmental motion, while the motion of entire molecules is essentially unchanged from that in bulk samples. General trends in the data are highlighted and outstanding issues are discussed. (c) 2004 Elsevier B.V. All rights reserved.