Dynamics of Glassy Polymers Under Nanoscale Confinement

Myriads of studies have shown that glassy polymers under nanoscale confinement demonstrate changes in the dynamic properties with the size of confinement. For polymers confined in nanometer films, overwhelming evidence has shown that the thickness dependences found of the dynamic properties are caused by perturbations to the local dynamics of the polymer by the interfaces of the films. The dynamics ultimately displayed by a film is determined by the overarching effect of the two interfaces. In this talk, I will focus on how the effects of the two interfaces combine to produce changes to the whole-film dynamics as revealed by recent experiments conducted by our group on the glass transition temperature and effective viscosity of thin films of random copolymers [1,2] and polymers chemically mildly modified by ultra-violet ozone treatment [3-5]. Cases where the dynamics at one interface is modified by the opposite one will be emphasized to highlight the need to consider the interplay between the effects of the two interfaces to fully understand the dynamics of glassy polymers under nanoscale confinement.