TY - JOUR A1 - Madkour, Sherif A1 - Szymoniak, Paulina A1 - Hertwig, Andreas A1 - Heidari, M. A1 - von Klitzing, R. A1 - Napolitano, S. A1 - Sferrazza, M. A1 - Schönhals, Andreas T1 - Decoupling of dynamic and thermal glass transition in thin films of a PVME/PS blend T2 - ACS Macro Letters N2 - The discussions on the nanoconfinement effect on the glass transition and glassy dynamics phenomena have yielded many open questions. Here, the thickness dependence of the thermal glass transition temperature of thin films of a PVME/PS blend is investigated by ellipsometry. Its thickness dependence was compared to that of the dynamic glass transition (measured by specific heat spectroscopy), and the deduced Vogel temperature (T0). While and T0 showed a monotonous increase, with decreasing the film thickness, the dynamic glass transition temperature () measured at a finite frequency showed a non-monotonous dependence that peaks at 30 nm. This was discussed by assuming different cooperativity length scales at these temperatures, which have different sensitivities to composition and thickness. This non-monotonous thickness dependence of disappears for frequencies characteristic for T0. Further analysis of the fragility parameter, showed a change in the glassy dynamics from strong to fragile, with decreasing film thickness. PB - ACS Publications KW - Thin polymeric films KW - Ellipsometry KW - Specific heat spectroscopy PY - 2017 UR - https://opus4.kobv.de/opus4-bam/frontdoor/index/index/docId/42266 AN - OPUS4-42266 SN - 2161-1653 VL - 6 IS - 10 SP - 1156 EP - 1161 AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany