It is now known that both the glass transition temperature (Tg) and the alpha relaxation dynamics can deviate substantially from the bulk with confinement of polymer films. Using a novel fluorescence multilayer method, it has been established that the deviations in Tg observed with decreasing film thickness for polystyrene and poly(methyl methacrylate) films supported on silica are a result of interfacial effects. Since the glass transition is related to the cooperative segmental (alpha) relaxation dynamics, it must be that these dynamics at the interfaces are different from the bulk. However, because of experimental limitations no direct measurement of the complete alpha relaxation time distribution at the interfaces has been conducted. Here we present results of a novel dielectric multilayer method that allows for such measurements. For the first time, a reduction in the peak temperature of the alpha process and a broadening of the alpha-relaxation process are observed at the polystyrene interface. Our results suggest that the impact of nanoconfinement on the alpha process originates from interfacial effects just as the impact of nanoconfinement on Tg originates from interfacial effects.

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