Berlin 2001 – wissenschaftliches Programm

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CPP: Chemische Physik und Polymerphysik

CPP 19: Poster: New Methods, Thin Polymer Films, Monolayers

CPP 19.12: Poster

Donnerstag, 5. April 2001, 12:30–15:00, AT1

Confinement Induced Reconstruction of Cylindrical ABA Block Copolymer Microdomains — •Armin Knoll, Robert Magerle, and Georg Krausch — Physical Chemistry II, University of Bayreuth, D-95440 Bayreuth

We studied the microdomain structure of ultra thin films of a SBS (polystyrene-b-polybutadien-b-polystyrene) blockcopolymer which forms cylindrical microdomains in bulk. Spin cast films were treated with a controlled partial pressure of solvent vapor (CHCl₃) in order to reach local minima in the free energy of the system. The resulting microdomain structures were frozen in by quickly drying the samples and were studied by Tapping Mode AFM.

The films typically form islands and holes with thicknesses smaller and larger than the original thickness, corresponding to energetically favored thicknesses. Layers with thickness larger than one cylinder-layer spacing show typical stripe-like patterns in the AFM images corresponding to polystyrene cylinders lying parallel to the surface. In thinner layers two additional morphologies were found, one corresponding to a perforated lamella and one without any topographical features corresponding to a lamella phase. These results are in good agreement with recent computer simulations (H. P. Huinink et al., J. Chem. Phys. 112, 2452 (2000); G.J.A. Sevink und H. P. Huinink, submitted to Macromolecules).