title: Orientation selection in lamellar phases by oscillatory shears.
abstract: In order to address the selection mechanism that is responsible for the unique lamellar orientation observed in block copolymers under oscillatory shears, we use a constitutive law for the dissipative part of the stress tensor that respects the uniaxial symmetry of a lamellar phase. An interface separating two domains oriented parallel and perpendicular to the shear is shown to be hydrodynamically unstable, a situation analogous to the thin layer instability of stratified fluids under shears. The resulting secondary flows break the degeneracy between the parallel and perpendicular lamellar orientation, leading to a preferred perpendicular orientation in certain ranges of parameters of the polymer and of the shear.
authors.affiliation: McGill Institute for Advanced Materials and Department of Physics, McGill University, Montreal, QC H3A 2T8, Canada.
authors.forename: Zhi-Feng
authors.initials: ZF
authors.lastname: Huang
authors.forename: Jorge
authors.initials: J
authors.lastname: Viñals