Dresden 2009 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 21: Polymer Physics II

CPP 21.8: Talk

Wednesday, March 25, 2009, 11:30–11:45, ZEU 114

The glass transition in blends of molecular glasses — •Roman Ueberschaer, Evgeny Tatarov, Thomas Fuhrmann-Lieker, and Josef Salbeck — Universität Kassel, Heinrich-Plett-Straße 40, D-34132 Kassel, Germany

Blends of molecular glasses and their properties are of great interest for applications in optoelectronics. In this contribution we present results of differential-calorimetric measurements on binary blends of spiro-compounds. Spiro-compounds are low-molecular organic glass formers with glass transition temperatures well above 100 °C. The investigation was focused on the composition dependence of the glass transition temperature for two prototype blend systems. One system consists of two components that are miscible over the whole composition range. Applying the Fox law that approximates the inverse glass temperature as the sum of the inverse glass temperatures of the two compatible components weighted by their mass fractions, we found that a modified version of the Fox law where the weighting is related to the mole fraction predicts the glass transition temperature of the blend more accurately. This result might be useful for approximating the phase compositions of partially miscible blends from the corresponding glass transition temperatures. We discuss this issue with respect to the second system that exhibits a broad miscibility gap despite the high entropy of mixing that is expected for low-molecular substances.