title: Lamellar Diblock Copolymer Thin Films during Solvent Vapor Annealing Studied by GISAXS: Different Behavior of Parallel and Perpendicular Lamellae.
abstract: The reorientation of lamellae and the dependence of the lamellar spacing,Dlam, on polymer volume fraction, ϕP,Dlam∝ ϕP-β, in diblock copolymer thin films during solvent vapor annealing (SVA) are examined by combining white light interferometry (WLI) and grazing-incidence small-angle X-ray scattering (GISAXS). A thin film of lamellae-forming poly(styrene-b-butadiene) prepared by spin-coating features lamellae of different orientations with the lamellar spacing depending on orientation. During annealing with ethyl acetate (EAC) vapor, it is found that perpendicular lamellae behave differently from parallel ones, which is due to the fact that their initial lamellar thicknesses differ strongly. Quantitatively, the swelling process is composed of three regimes and the drying process of two regimes. The first two regimes of swelling are associated with a significant structural rearrangement of the lamellae; i.e., the lamellae first become thicker, and then perpendicular and randomly oriented lamellae vanish, which results in a purely parallel orientation at the end of the swelling process. The rearrangement is attributed to the increase of mobility of the polymer chains imparted by the solvent and to a decrease of total free energy of the thin film. In the third regime of swelling, the scaling exponent is found to be β = -0.32. During drying, the deswelling is nonaffine which may be a consequence of the increase of nonfavorable segmental interactions as the solvent is removed.
authors.affiliation: Physik-Department, Fachgebiet Physik weicher Materie, Technische Universität München , James-Franck-Str. 1, 85748 Garching, Germany.
authors.forename: Jianqi
authors.initials: J
authors.lastname: Zhang
authors.affiliation: IMFUFA, Department of Science, Systems and Models, Roskilde University , P.O. Box 260, 4000 Roskilde, Denmark.
authors.forename: Dorthe
authors.initials: D
authors.lastname: Posselt
authors.affiliation: Cornell High Energy Synchrotron Source (CHESS), Wilson Laboratory, Cornell University , Ithaca, New York 14853, United States.
authors.forename: Detlef-M
authors.initials: DM
authors.lastname: Smilgies
authors.affiliation: Deutsches Elektronen-Synchrotron (DESY), Notkestr. 85, 22607 Hamburg, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Perlich
authors.affiliation: Physik-Department, Fachgebiet Physik weicher Materie, Technische Universität München , James-Franck-Str. 1, 85748 Garching, Germany.
authors.forename: Konstantinos
authors.initials: K
authors.lastname: Kyriakos
authors.affiliation: Physik-Department, Fachgebiet Physik weicher Materie, Technische Universität München , James-Franck-Str. 1, 85748 Garching, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Jaksch
authors.affiliation: Physik-Department, Fachgebiet Physik weicher Materie, Technische Universität München , James-Franck-Str. 1, 85748 Garching, Germany.
authors.forename: Christine M
authors.initials: CM
authors.lastname: Papadakis