Sonderforschungsbereich 481

    Komplexe Makromolekül- und Hybridsysteme in inneren und äußeren Feldern

Subproject a8:

Thermodiffusion in polymer blends: structure formation and length scale selection

Prof. Werner Köhler (Experimental Physics IV)
Prof. Walter Zimmermann (Theoretical Physics I)

Due to the Soret effect, inhomogeneous temperature fields give rise to composition gradients in polymer blends which can grow very large in the vicinity of a phase transition. We are studying this mechanism both experimentally and theoretically. In particular, we want to understand how thermally driven surface-induced demixing can be utilized for the formation of controllable and switchable morphologies. Other potential applications are rewritable and erasable wave-guide structures of arbitrary shape. Light absorbing metal colloids are suitable as localized intrinsic heat sources. Further theoretical studies are concerned with the influence of electric fields on the order-disorder-transition.
Arbitrary pattern ("Bayreuth") reversibly written into a thin layer of a PDMS/PEMS blend. Simulation of cross section through a written line. PDMS rich (red) channel with PEMS rich (blue) shield against the sapphire windows (top, bottom). The flow field is due to solutal convection.

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