Dresden 2011 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 13: Focused Session: Confinement of Polymers in Nanoscopic Layers - How Much do Properties Change? I

CPP 13.1: Hauptvortrag

Dienstag, 15. März 2011, 10:30–11:00, ZEU 160

Rheological Response of Ultrathin Polymer Films — •Gregory McKenna, Paul O'Connell, and Jinhua Wang — Texas Tech University, Lubbock, TX, USA

We have developed a novel bubble inflation method to determine the rheological response of ultrathin polymer films. The method shows,consistent with other methods, dramatic reductions of the glass transition (Tg) of polystyrene of high molecular weight. We have also discovered a major stiffening of the material in the rubbery plateau regime. New information for polycarbonate shows that, like polystyrene it can exhibit strong reductions in the Tg and rubbery stiffening. We also report the first evidence of terminal flow in the bubble inflation experiment using polycarbonate having thicknesses from 3 nm to 9 nm. We have also performed liquid film dewetting experiments for both polystyrene and polycarbonate systems. The results for the polystyrene are consistent with literature reports of little change in the glass transition and no change from macroscopic behavior for the rubbery plateau regime. On the other hand, for polycarbonate we observe both a reduction in the Tg and moderate stiffening in the rubbery regime. These results will be discussed in detail.