How fundamental material properties influence interfacial effects on polymer dynamics.*

It is an enduring problem to make direct connections between the characteristic material properties of a system and its behavior. We have illuminated one path that begins with a thermodynamic characterization and leads to new understanding of various material responses, including the dynamics of local segmental relaxation.  Our initial work focused on bulk samples which allowed for substantive model testing. More recently we have turned our attention to confined systems, where one or more interfaces are present in the form of a substrate (or cap), or a free surface.  This presentation will focus on recent collaborative work in which our theoretical model leads to predictions and explanations for dielectric relaxation measurements involving several polymer systems. Results to be discussed include those showing the effects of surface roughness, as well as a direct comparison of the influence from proximity to supported versus free surfaces.