Regensburg 2010 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 30: Posters II

DY 30.21: Poster

Thursday, March 25, 2010, 16:00–18:00, Poster C

Pattern Formation in Langmuir-Blodgett Transfer Systems — •Michael H. Köpf, Svetlana V. Gurevich, and Rudolf Friedrich — Institute for Theoretical Physics, University of Münster, Wilhelm-Klemm-Straße 9, D-48149 Münster

We present a theoretical investigation of self-organized pattern formation that has been observed during Langmuir-Blodgett transfer of phospholipids onto solid substrates. Two coupled differential equations describing the surfactant density and the height profile of the water subphase are derived within the long-wavelength approximation. If the transfer is carried out in the vicinity of the so-called main transition, the first-order phase transition between the liquid-expanded and the liquid-condensed phase, the interaction with the substrate plays a key role. We model this effect via a height dependent external field in the surfactant free-energy functional. Using transfer velocity and lateral pressure as control parameters a bifurcation from a homogeneous transfer to regular stripe patterns arranged parallel to the contact line is investigated in one and two dimensions. Moreover, in the two-dimensional case a secondary bifurcation to perpendicular stripes is observed in a certain control parameter range.