Dresden 2009 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 28: POSTERS Interfaces and Thin Films

CPP 28.6: Poster

Mittwoch, 25. März 2009, 17:00–19:00, P3

Glass transition in ultra thin polymeric films measured by differential AC chip calorimetry — •Heiko Huth¹, Dongshan Zhou², and Christoph Schick¹ — ¹University of Rostock, Institute of Physics Universitätsplatz 3, 18051 Rostock, Germany — ²Dept. of Polymer Science and Eng., Nanjing University, Nan- jing, 210093, China

The film thickness dependency of glass transition in polymer films is still controversially discussed. For different experimental probes different dependencies are observed and a generally accepted link to molecular mobility is not yet established. Calorimetry has proven to provide useful information about glass transition, because it establishes a direct link to energetic characterization. In several cases a direct comparison with results from other dynamic methods like dielectric spectroscopy is possible giving further insights. For thin films in the micro...nm range standard calorimetric methods are mostly not applicable. In the recent years there are new developments in the field of calorimetry which overcome these limitations. We set up a differential AC-chip calorimeter capable to measure the glass transition in nanometer thin films with pJ/K sensitivity. Changes in heat capacity can be measured for sample masses below one nanogram as needed for the study of the glass transition in nanometer thin polymeric films. No thickness dependency of the glass transition temperature was observed within the error limits - neither at constant frequency nor for the traces in the activation diagrams.