Berlin 2018 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 20: Poster Session I

CPP 20.58: Poster

Montag, 12. März 2018, 17:30–19:30, Poster A

Dynamics of nanoscopically confined PVME in thin films of an asymmetric PVME/PS blend — •Paulina Szymoniak, Sherif Madkour, and Andreas Schönhals — BAM Bundesanstalt für Materialforschung und -prüfung, Unter den Eichen 87, 12205 Berlin (Germany)

In recent years, substantial efforts have been devoted to investigating nanoscopic confinement of polymers, and its effect on glassy dynamics. Broadband Dielectric Spectroscopy (BDS) was used to study the dynamics of ultra-thin films of PVME/PS 50/50 wt% blend, employing a novel nano-structured capacitor sample arrangement. The investigated system shows a complex dynamic behavior. First, an α-relaxation, related to a bulk-like layer was found. Second, an α'-relaxation was observed, characteristic for dynamically asymmetric blends, where the out of equilibrium dynamics is attributed to weakly-cooperative PVME segments relaxing within a frozen environment of PS segments. Thirdly, for thinnest films, an Arrhenius-like process was dominant in the dielectric spectra, indicating localized fluctuations of the segments. Relaxation rates of this process resembled that of the degenerated α-relaxation of the adsorbed layer, found for pure PVME [1], thus it was assigned accordingly. For thinnest films, this process undergoes a further confinement, due to the topological constraints, introduced by PS. Such multiple confinement effect has not been reported for ultra-thin films of polymer blends, before this study [2]. [1] Madkour, S. et al. ACS Appl. Mater. Interfaces 2017, 9, 7535. [2] Madkour, S. et al. ACS Appl. Mater. Interfaces 2017, 9, 37289