title: Symmetry breaking of in-plane order in confined copolymer mesophases.
abstract: Packing of spherical-domain block copolymer mesophases confined to a thin film is investigated as a function of the number of layers n. We find an abrupt transition from hexagonal to orthorhombic in-plane ordering of domains when n is increased from 4 to 5. As n increases further (up to 23 in this study), the symmetry of the orthorhombic phase asymptotically approaches that of the body-centered cubic (110) plane. These results are interpreted in terms of the energetics of competing packings in the bulk and at the film interfaces. Detailed structural and thermodynamic properties are obtained with self-consistent field theory.
authors.affiliation: Department of Chemical Engineering, University of California, Santa Barbara, California 93106, USA.
authors.forename: G E
authors.initials: GE
authors.lastname: Stein
authors.forename: E W
authors.initials: EW
authors.lastname: Cochran
authors.forename: K
authors.initials: K
authors.lastname: Katsov
authors.forename: G H
authors.initials: GH
authors.lastname: Fredrickson
authors.forename: E J
authors.initials: EJ
authors.lastname: Kramer
authors.forename: X
authors.initials: X
authors.lastname: Li
authors.forename: J
authors.initials: J
authors.lastname: Wang