Regensburg 2002 – wissenschaftliches Programm
SYPF 2.15: Poster
Donnerstag, 14. März 2002, 09:00–18:00, Poster B
Morphology of Thin Films of Cylinder Forming ABA Block Copolymers — •Armin Knoll, Andriana Horvat, Robert Magerle, and Georg Krausch — Physikalische Chemie II, Universität Bayreuth, 95440 Bayreuth, Germany
We study the microdomain structure of ultra thin films of different ABA block copolymers, which form cylindrical microdomains in the bulk. Spin cast films were treated with a controlled partial pressure of CHCl3 vapor 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 ModeTM AFM.
The films typically form islands and holes with thicknesses smaller and larger than the original thickness, corresponding to energetically favored thicknesses. At a certain solvent content a variety of morphologies are found as a function of the film thickness. A phase diagram of the stable morphologies for different film thicknesses and solvent contents was determined.
The findings show remarkable agreement with computer simulations done in our group (see poster of Horvat et. al). This agreement indicates that the interactions between the different microdomains and between the micodomains and the surfaces are the relevant parameters. The change of morphologies can be understood in terms of surface reconstruction and confinement effects.