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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 26: Poster: New Perspectives of Scattering at Soft Matter

CPP 26.1: Poster

Mittwoch, 28. März 2012, 11:00–13:00, Poster A

Structural evolution in diblock copolymer thin films with perpendicular lamellar structure during solvent vapor treatment — •Jianqi Zhang¹, Alessandro Sepe¹, Richard Steinacher¹, Jan Perlich², Dorthe Posselt³, and Christine Papadakis¹ — ¹TU München, Physikdepartment, Physik weicher Materie, Garching, Germany — ²HASYLAB at DESY, Hamburg, Germany — ³Roskilde University, IMFUFA, Denmark

Well-ordered structures formed by self-assembly of diblock copolymer have attracted increasing interest due to the potential applications. However, the usual preparation methods often result in defects which hamper the application. Vapor treatment with solvents is a commonly used technique to anneal defects in thin films. We have investigated the structural changes of lamellae-forming P(S-b-B) diblock copolymer thin films with perpendicular lamellar structure using in-situ, real-time grazing-incidence small-angle X-ray scattering with a time resolution of 30 s. Cyclohexane and ethyl acetate were used for vapor treatment, which are selective for PB and PS, respectively. We have found that new narrow Bragg rods appear before the diffuse Bragg rods bend in the vapor. These findings point to an initial formation of a thin near-surface layer having the perpendicular orientation and a later destabilization of the perpendicular orientation. The main reason is the change of chain conformations, i.e. a tendency to coiling of the initially stretched copolymers upon solvent uptake.