Berlin 2008 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 31: Thin Films

CPP 31.1: Talk

Thursday, February 28, 2008, 09:30–09:45, C 264

Cylindrical phase of diblock copolymers in thin films — •Rosa Marianne Breuer and Barbara Drossel — Institut für Festkörperphysik, Hochschulstr. 6, 64289 Darmstadt

Diblock copolymers are polymers in which two chains of different monomers are covalently bound to one another. Because of their different chemical nature the blocks have a tendency to phase separate, but a macroscopic phase separation is prohibited by the chemical bond connecting the different blocks. Therefore such molecules have a tendency to separate on a microscopic scale forming a variety of ordered structures, called microphases. We investigate the microphases of diblock copolymers confined in a thin film with walls attracting one of the monomer types. We focus on the possible structures of copolymers that form cylindrical phases in the bulk. We employ both self-consistent field theory and strong segregation theory to obtain the concentration profile minimizing the free energy of the system and to compare the free energy of possible morphologies. We present a phase diagram showing the possible microphases for a diblock copolymer with fixed volume fraction and fixed segregation parameter in dependence of the film thickness and the affinity of the walls. We study the effects of numerical inaccuracies on the appearance of different morphologies and their free energies.