Berlin 2012 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 13: Poster: Interfaces and Thin Films
CPP 13.30: Poster
Dienstag, 27. März 2012, 18:15–20:45, Poster A
Can we correlate residual stresses in ultrathin polymer films with a high surface mobility? — •Mithun Chowdhury1, Paul Freyberg1, and Günter Reiter1,2 — 1Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, 79104, Freiburg, Germany — 2Freiburg Institute for Advanced Studies (FRIAS), 79104, Freiburg, Germany.
The fabrication process of a thin polymer film, involving the transition from a solution to a glass, is believed to have an impact on film properties, often related to poorly entangled out-of-equilibrium chain conformations and corresponding residual stresses caused by rapid solvent loss. Physical ageing of polymer films, at temperatures below the glass transition was found to lead to a progressive decay in dewetted hole size (indicative of a decreasing residual stress), in a close to exponential fashion with ageing time, defining a characteristic relaxation time. Relaxation times are largely in agreement with some earlier reports based on surface sensitive techniques for thin polymer films. This is indeed surprising as dewetting cannot be considered as a surface sensitive probe. Moreover, temperature dependence of the relaxation time of residual stresses, above the glass transition of the polymer can be obtained from the evolution of the shape of the dewetting rim. Relaxation times in that region are much faster with a significant deviation from the bulk polymer. Our results certainly invoke the possibility to explain the faster relaxation dynamics in thin films and its deviation from the bulk, also in terms of residual stresses induced from the film preparation stage.