Ovchinnikova K, Pollack GH. Cylindrical phase separation in colloidal suspensions.
PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2009;
79:036117. [PMID:
19392028 DOI:
10.1103/physreve.79.036117]
[Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2008] [Revised: 12/03/2008] [Indexed: 05/27/2023]
Abstract
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.
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