Cylindrical phase separation in colloidal suspensions.
When left overnight undisturbed in a covered beaker, suspensions of polystyrene microspheres were found to undergo a distinctive kind of macroscopically visible phase separation. Microspheres migrated radially, leaving a vertically oriented cylinder near the center of the beaker that was devoid of microspheres. Cylinder formation was preceded by formation of a microsphere-free plate at the suspension surface, which may be the precursor of the cylinder. The cylindrical phase separation was found to depend on illumination, which suggests that low-level photon energy from the laboratory environment is sufficient to drive this surprising pattern formation. So long as suspension parameters were set within certain ranges, the cylindrical pattern occurred regularly.
Ovchinnikova
Kate
K
Department of Bioengineering, University of Washington, Box 355061, Seattle, Washington 98195, USA.
Pollack
Gerald H
GH
D001703:Biophysics / Q000379:methods; D003102:Colloids / Q000737:chemistry*; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D008863:Microspheres; D015233:Models, Statistical; D010316:Particle Size; D017785:Photons; D011137:Polystyrenes / Q000737:chemistry*; D013499:Surface Properties; D013535:Suspensions; D013696:Temperature
D003102:Colloids; D011137:Polystyrenes; D013535:Suspensions