Suppression of the t _g-nanoconfinement effect in thin poly(vinyl acetate) films by sorbed water

Suppression of the T_g-nanoconfinement effect in thin poly(vinyl acetate) films by sorbed water was studied by several researchers. Keddie and co-researchers reported that nanoconfinement reduces the glass transition temperatures (T_gs) of polystyrene (PS) films supported on silica and poly(methyl methacrylate) (PMMA) films supported on gold. They demonstrated that the T_g increase in an ultrathin layer at the PMMA-silica interface is greater than the T_g decrease in a similar layer at the PMMA-air interface. Fukao and co-researchers characterized Tα, the peak temperature in the T dependence of the imaginary part of the complex dielectric constant, at 100 Hz. Characterizing creep compliance in microbubble experiments, O'Connell and McKenna concluded that there was little or no T_g-confinement effect in free-standing films as thin as 27 nm. Because they floated films on water prior to experiment, their films should be considered wet.