Authors Serghei, A. ; Mikhailova, Y. ; Eichhorn, K.-J. ; Voit, B. ; Kremer, F.
Title Discrepancies in the Characterization of the Glass Transition in Thin Films of hyperbranched polyesters
Date 04.10.2006
Number 13841
Abstract The dynamic glass transition and the dilatometric glass transition temperature are simultaneously characterized in thin films of hyperbranched aromatic polyesters by broadband dielectric spectroscopy and capacitive scanning dilatometry. A diverging thickness dependence is detected: while the temperature position of the alpha relaxation peak T decreases by 30 K, the dilatometric Tg increases by 10 K with decreasing film thickness. This emphasizes the subtle character of the glass transition phenomenon - as manifested in the molecular dynamics and in the (structural) thermal expansion - and proves that, in contrast to the bulk, different experimental techniques do not necessarily deliver similar results in confinement.
Publisher Journal of Polymer Science: Part B: Polymer Physics
Citation Journal of Polymer Science: Part B: Polymer Physics 44 (2006) 3006-3010
Tags glass transition molecular dynamics thin films ultrathin polymer-films molecular-dynamics poly(methyl methacrylate) dielectric relaxations temperature polystyrene scale

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