(751a) Molecular Mobility in Ultrathin Polymer Films

Central to the advancement of many technologies is the miniaturization of functional devices to the nanometer length scale.  As polymers continue to play a prominent role in material solutions in meeting the challenges of reducing size, they are increasingly being utilized at length scales that are approaching the dimensions of the unperturbed macromolecule.  Furthermore, with decreasing the confining dimension to the nanoscale an increasingly larger fraction of molecules are in direct contact with solid surfaces.   As a consequence, in ultrathin polymer films, molecular mobility can differ significantly from the bulk.  Here we present a non-contact method to measure the viscoelastic properties of supported thin polymer films.  The approach is based on the blow-off method originally developed to measure viscosity in monolayer films of molecular liquids.  The method entails flowing gas under laminar flow conditions through a narrow channel in order to generate a well-define shear stress on a properly placed sample and subsequently measuring the deformation.  Our design is modernized in numerous ways, including, the ability to simultaneously control the gas and substrate temperature.  In combination with hole- and edge- dewetting experiments, the new blow-off features will allow for the measurement of time- and temperature-dependent viscoelastic properties of thin polymer films.