Regensburg 2013 – wissenschaftliches Programm
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DS: Fachverband Dünne Schichten
DS 31: Organic thin films II
DS 31.8: Vortrag
Donnerstag, 14. März 2013, 16:30–16:45, H8
Triangular dewetting of a PCDTBT-PS blend — •Paul Freyberg1, Ioan Botiz1,2, and Günter Reiter1,2 — 1Institute of Physics, University of Freiburg, Freiburg, Germany — 2Freiburg Institute for Advanced Studies, Freiburg, Germany
Normally the dewetting of thin polymer films results in the growth of circular holes. The symmetry of this process is well understood by current theories. Interestingly, a breaking of this symmetry is found in a particular case: We observe highly anisotropic growth of holes leading to a triangular dewetting shape for the dewetting of thin polymer blend films consisting of rigid, conjugated PCDTBT* and polystyrene (PS).
By varying physical parameters like the volume fraction or by changing the substrate we can control the transition from circular to triangular dewetting. The presence of PCDTBT in thin polystyrene films leads to symmetry breaking for all dewetting temperatures in the experiments. We tentatively explain our experimental observations by an ordering of PCDTBT molecules at the contact line, leading to a breaking of the symmetry. The triangular shape is very stable, allowing triangular growth up to large scales.
*Poly[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1,3-benzo-thiadiazole-4,7-diyl-2,5-thiophenediyl]