title: Boundary-driven colloidal crystallization in simple shear flow.
abstract: Using confocal microscopy, we directly observe that simple shear flow induces transient crystallization of colloids by wall-normal propagation of crystallization fronts from each shearing surface. The initial rate of the front propagation was 1.75±0.07 colloidal layers per unit of applied strain. The rate slowed to 0.29±0.04 colloidal layers per unit of applied strain as the two fronts approached each other at the midplane. The retardation of the front propagation is caused by self-concentration of shear strain in the growing bands of the lower-viscosity crystal, an effect that leads to a progressive reduction of the shear rate in the remaining amorphous material. These findings differ significantly from previous hypotheses for flow-induced colloidal crystallization by homogeneous mechanisms.
authors.affiliation: University of Michigan, Ann Arbor, Michigan 48109-2136, USA.
authors.forename: Laura T
authors.initials: LT
authors.lastname: Shereda
authors.forename: Ronald G
authors.initials: RG
authors.lastname: Larson
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Solomon