Regensburg 2016 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 61: Interfaces and Thin Films I (joint session CPP/DY, organized by CPP)

CPP 61.3: Vortrag

Donnerstag, 10. März 2016, 17:00–17:15, H51

Evidence of a three-Layered structure in ultra-thin PVME and PVME/PS blend Films by nano-sized relaxation spectroscopy — •Sherif Madkour¹, Paulina Szymoniak¹, Mojdeh Heidari², Regine von Klitzing², and Andreas Schönhals¹ — ¹BAM Bundesanstalt für Materialforschung und -prüfung, Unter den Eichen 87, 12205 Berlin (Germany) — ²Technische Universität Berlin, Straße des 17. Juni 124, 10623 Berlin (Germany)

Despite the many controversial discussions about the nanometric confinement effect on the properties of ultrathin films, many details remain not understood and/or experimentally unproven. Here, a combination of Broadband Dielectric Spectroscopy (BDS), Specific Heat Spectroscopy (SHS), and ellipsometry was utilized to investigate the glassy dynamics of ultra-thin films of Poly (vinyl methyl ether) (PVME) and PVME/Polystyrene (PS) 50:50 wt-% miscible blend (thicknesses: 8nm - 200nm). For BDS measurements, a recently developed nano-structured sample arrangement; where ultra-thin films are spin-coated on an ultra-flat highly conductive silicon wafer and sandwiched between a wafer with nanostructured SiO2 nano-spacers, was used. For PVME films, two processes were observed and interpreted to be the α-processes of a bulk-like layer and an absorbed layer to the substrate. BDS and SHS showed that glassy dynamics are bulk-like. However, for films lower than 15nm, BDS showed weakly slowed dynamics. For PVME/PS blend, by measuring the dynamic Tg in dependence on the film thickness, both BDS and SHS, showed that the Tg of the whole film was strongly influenced by a nanometer thick surface layer.