Molecular dynamics in thin films of isotactic poly(methylmethacrylate) - revisited

The molecular dynamics in thin films of isotactic poly(methylmethacrylate) is investigated by broadband dielectric spectroscopy. No shifts in the mean relaxation time of the dynamic glass transition are detected down to a film thickness of 6.6 nm. These results are compared to previous measurements on thin films of isotactic poly(methylmethacrylate) [L. Hartmann et al., Eur. Phys. J. E 8 (2002) 145]. We show that in the latter case, the shifts in the dynamic glass transition are caused by an erroneous analysis of the experimental results. (c) 2007 Published by Elsevier B.V.