Metastable states of glassy dynamics, possibly mimicking confinement-effects in thin polymer films

The impact of the preparation and thermal films history on the dynamic glass transition in thin films of poly(methyl methacrylate) and poly(vinyl acetate) is systematically investigated means of broadband dielectric spectroscopy. Metastable states of glassy dynamics are detected, exhibiting shifts in the mean-relaxation time from the bulk values. These shifts - possibly mimicking confinement- effects in thin polymer films - become weaker (or even disappear) after an extensive annealing.