The dynamics of polymer molecules in confined geometries have been studied extensively for more than a decade. During this time, much has been achieved toward an understanding of the effect of confinement on the motion of polymer molecules on different time scales, especially for the thin film geometry corresponding to one-dimensional confinement of the molecules. In recent years, beautiful experiments, sample geometries and computational techniques have been devised to address specific aspects of this problem such as the mobility associated with the free surface, the depth dependence of the glass transition temperature within a polymer film, and measurements of relaxation processes on different time scales within thin polymer films. Despite this progress, there remain many unanswered questions and outstanding issues related to the dynamics of confined polymers, such as the effect of interfaces, molecular weight, chemical nature of the molecules, and time scale of the measurement on the observed dynamical behavior of the polymer sample. The results obtained for the thin film geometry have begun to be applied to the more complicated but technologically important geometry of polymer nanocomposites.
The articles in this Special Issue have been contributed by leading groups who collectively address many of the interesting and unresolved issues mentioned above. The Special Issue is organized loosely into the following categories: glass transition in polymer nanocomposites, glass transition in thin polymer films, and the motion of confined polymer chains on larger length scales.
It is my hope that by reading this Special Issue that the reader is able to obtain a flavor of the exciting research that is being pursued in this very active field.