Sedimentation and multi-phase equilibria in mixtures of platelets and ideal polymer
Abstract
The role of gravity in the phase behaviour of mixtures of hard colloidal plates without and with non-adsorbing ideal polymer is explored theoretically. By analyzing the (macroscopic) osmotic equilibrium conditions, we show that sedimentation of the colloidal platelets is significant on a height range of even a centimeter. Gravity enables the system to explore a large density range within the height of a test tube which may give rise to the simultaneous presence of multiple phases. As to plate-polymer mixtures, it is shown that sedimentation may lead to a four-phase equilibrium involving an isotropic gas and liquid phase, nematic and columnar phase. The phenomenon has been observed experimentally in systems of colloidal gibbsite platelets mixed with PDMS polymer.
- Publication:
-
EPL (Europhysics Letters)
- Pub Date:
- April 2004
- DOI:
- 10.1209/epl/i2003-10140-1
- Bibcode:
- 2004EL.....66..125W