Berlin 2008 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 31: Thin Films

CPP 31.2: Vortrag

Donnerstag, 28. Februar 2008, 09:45–10:00, C 264

3-Dimensional Control over lamella orientation in thick block copolymer films — •Violetta Olszowka, Larisa Tsarkova, and Alexander Böker — Physikalische Chemie II, Universität Bayreuth, Germany

We present a novel route to produce thick films with long-ranged 3D ordered upstanding lamellae and a perfectly ordered nano-striped surface pattern. Thick lamella polystyrene-b-poly(2-vinyl pyridine) diblock copolymer films are exposed simultaneously to a selective solvent vapor and to an in-plane electric field. The orientation of the lamellae was studied by combined scanning force microscopy, grazing incidence small angle x-ray scattering and transmission electron microscopy measurements. The lamellae orientation perpendicular to the film plane upon long-term selective solvent annealing was detected in a narrow window of the film thickness (about 17-22 lamella distances). In thicker and thinner films, lamellae were perfectly aligned parallel to the film plane due to the surface fields effects. Theoretical model is proposed to account for the thickness- and annealing time dependent reorientation of lamella domains. The observed phenomena presumably initiates in the interior of the film when the concentration fluctuations due to selective swelling overcome the suppression by the surface fields.