Novel zone formation due to interplay between sedimentation and phase ordering
Institute of Industrial Science, University of Tokyo - Meguro-ku, Tokyo 153-8505, Japan
2 School of Chemistry, University of Bristol - Bristol BS8 1TS, UK, EU
Corresponding author: firstname.lastname@example.org
Accepted: 14 January 2010
Usually, we expect large particles to sediment faster than small ones of the same material. Contrary to this intuition, we report a dynamical competition between sedimentation and phase ordering which leads to smaller particles settling faster than larger ones. We access this phenomenon using suspensions of polymers and two colloidal species which we image with confocal microscopy. Polymers mediate attractions between colloids, leading to phase separation and crystallisation. We find that the dynamical interplay between sedimentation, phase separation and crystal nucleation underlie this phenomenon. Furthermore, under certain conditions we find a kinetic pathway leading to an apparent coexistence between a one-component crystal and a binary fluid of equal buoyancy. These findings may be relevant to the basic understanding of sedimentation-induced zone formation in nature and industrial applications.
PACS: 82.70.Dd – Colloids / 47.57.ef – Sedimentation and migration / 64.60.Cn – Order-disorder transformations
© EPLA, 2010