Berlin 2005 – wissenschaftliches Programm
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CPP: Chemische Physik und Polymerphysik
CPP 3: SYMPOSIUM: Dynamics of multi-component fluids III
CPP 3.3: Vortrag
Freitag, 4. März 2005, 14:45–15:00, TU C243
Thermal patterning of a critical polymer blend — •Werner Köhler, Wolfgang Enge, Albert Voit, Alexei Krekhov, and Lorenz Kramer — Physikalisches Institut, Universität Bayreuth
We have employed a moderately focused laser beam (30 µm, 20 mW) to write spatial composition patterns into layers of the critical polymer blend poly(dimethyl siloxane)/poly(ethyl-methyl siloxane) (PDMS/PEMS, Mw = 16.4/22.3 kg/mol) both in the one and in the two phase region a few degrees above and below the critical temperature Tc= 37.7 ∘C. Due to the critical divergence of the Soret coefficient, moderate temperature gradients are sufficient to induce composition modulations of large amplitude. In the two phase regime the spinodal demixing pattern can be locally manipulated in a controlled way. 2D-simulations based on a modified Cahn-Hilliard equation are able to reproduce the essential spatial and temporal features observed in the experiments.