History Dependent Temporal Changes of Properties of Thin Polymer Films

Despite an extensive number of investigations, it is becoming increasingly obvious that a clear understanding of thin polymer film properties has not yet been reached. The origin of (some of) the puzzling behavior of thin polymer films is still not satisfactorily unveiled. At present, we are still missing a consistent understanding of how film preparation and confinement affect film properties, in particular on approaching the glass transition temperature. While it may be disputable if the change from the initial solution to a dry glassy film introduces a conformational state” with its “own” properties, we will present various findings, mainly observed in dewetting experiments, which demonstrate the influence of sample preparation and of the thermal history these films have undergone. We conclude that that thickness is not the only parameter defining the properties of thin polymer films, i.e., they depend in addition on what happened to a film before a particular measurement was performed.