The physics of soft materials is distinct from hard matter as the weaker intermolecular bonds can result in a large response to external stresses. A surprising aspect of these materials is that at interfaces and on small length scales, like thin films or coatings, these materials can have properties that differ vastly from those of bulk systems. The difference can be the result of molecules being confined or because the interface plays a greater role the smaller the size of the system studied. In this talk I will summarize our recent work on using “stepped films” to uncover some of the physics relevant to polymer rheology on length scales comparable to the size of polymer molecules. The work presented will focus on the efforts of a larger collaboration (Élie Raphaël's theory group , James Forrest’s experimental group , and the experimental group at McMaster ). The simple geometry of a polymer film on a substrate with a step at the free surface is unfavourable due to the excess interface induced by the step, which drives flow within the film. These studies provide an opportunity to study how systems transition from the bulk to confined.
 T. Salez, M. Benzaquen, E. Raphaël, Gulliver Laboratory, CNRS-ESPCI, Paris, France
 Y. Chai & J. A. Forrest, University of Waterloo, Waterloo, Canada.
 J. D. McGraw, O. Bäumchen, S. L. Cormier, P. D. Fowler, M. Backholm, M. Ilton
Coffee and Refreshments will be available in MacN 101.