Berlin 2015 – wissenschaftliches Programm

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DS: Fachverband Dünne Schichten

DS 18: Interfaces and Thin Films II (joint session with CPP)

DS 18.5: Vortrag

Dienstag, 17. März 2015, 15:15–15:30, C 243

Polymer-solid interphases and glass transition probed by positron annihilation lifetime spectroscopy — Christian Ohrt, Tönjes Koschine, •Klaus Rätzke, and Franz Faupel — University of Kiel, Chair for Multicomponent Materials, D-24143 Kiel, Germany

The properties of materials involving polymer-solid interfaces are not only determined by the constituents but also by the interfacial region of the polymer near the solid, the so-called interphase. This interphase is particularly important in polymer-based nanocomposites. Here we report on positron annihilation lifetime spectroscopy (PALS) measurements of the free volume near the interface with a moderated positron beam. First investigations from the polymer side indicated a reduced free volume in Teflon AF / Si samples [1] but no quantitative information. Analysis from substrate side with a focused beam through a hole showed a significant average density increase iin an interphase region with a width of about 10 nm. Additionally, the glass transition temperature as a probe for chain dynamics was determined as function of distance to the interface in a Teflon AF / SiN sample with depth resolved PALS. Within error margins, no change in the glass transition temperature could be detected in the interfacial region.

[1] S. Harms, K. Rätzke, V. Zaporojtchenko, F. Faupel W. Egger, L. Ravelli, Polymer, 52 (2011) 505