Regensburg 2013 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 16: Interfaces and Thin Films II (joint session with DECHEMA and VDI)
CPP 16.11: Vortrag
Dienstag, 12. März 2013, 12:30–12:45, H40
Segmental and chain dynamics in thin layers of poly(cis-1,4-isoprene) — •Emmanuel Urandu Mapesa1, Martin Tress1, Manfred Reiche2, and Friedrich Kremer1 — 1University of Leipzig, Linnestraße 5, 04103 Leipzig, Germany. — 2Max Planck Institute of Microstructure Physics, Weinberg 2, 06120 Halle an der Saale, Germany.
Broadband Dielectric Spectroscopy (BDS) - in combination with a nanostructured electrode arrangement - is used to study thin layers of poly(cis-1,4-isoprene) (PIP). Being a Type A polymer, PIP enables the investigation of two distinct relaxation modes taking place at two different length scales: the segmental motion which involves structures of about one nanometer in size and the normal mode which represents the global dynamics of the chain. For molecular weights (Mw = 24.5, 44.5, 53 and 75 kg/mol) much greater than Mc (the critical molecular weight, Mc = 10e+04), down to thicknesses comparable to the respective radii of gyration, it is observed that: (i) the segmental mode as a local relaxation process is unaltered by the confinement in thin layers; (ii) the normal mode becomes faster with decreasing layer thickness, and (iii) this change in the normal mode is molecular-weight dependent. For Mw approximately equal to Mc, both the segmental and normal modes remain unaffected by changes in layer thickness.