Invited Talk: The Calorimetric Glass Transition Under Nanoconfinement

The behavior of materials confined at the nanoscale has been of considerable interest over the past two decades.  Recent work in our laboratory has focused on the influence of nanoconfinement on the glass transition and associated kinetics, on melting and crystallization, and on polymerization kinetics and resulting properties.  In this talk I will present recent results investigating the depression of the glass transition temperature for nanoconfined materials, including single polystyrene ultrathin films studied with ultrafast scanning chip calorimetry, glass-formers confined to nanopores, and glass-formers confined by crystalline domains.  The single thin films are of particular interest because they show a T_g depression which can be reversed by film dewetting and thickening during high-temperature annealing.  The results of materials confined in different geometries will be used to test the leading explanation for the T_g depression in nanoconfined glasses, i.e., that the enhanced mobility arises from free surface and interface affects.