Entropic patchiness drives multi-phase coexistence in discotic colloid-depletant mixtures
arXiv:1711.04143 · doi:10.1038/s41598-017-16415-0
Abstract
Entropy-driven equilibrium phase behaviour of hard particle dispersions can be understood from excluded volume arguments only. While monodisperse hard spheres only exhibit a fluid-solid phase transition, anisotropic hard particles such as rods, discs, cuboids or boards exhibit various multi-phase equilibria. Ordering of such anisotropic particles increases the free volume entropy by reducing the excluded volume between them. The addition of depletants gives rise to an entropic patchiness represented by orientation-dependent attraction resulting in non-trivial phase behaviour. We show that free volume theory is a simple, generic and tractable framework that enables to incorporate these effects and rationalise various experimental findings. Plate-shaped particles constitute the main building blocks of clays, asphaltenes and chromonic liquid crystals that find widespread use in the food, cosmetics and oil industry. We demonstrate that mixtures of platelets and ideal depletants exhibit a strikingly rich phase behaviour containing several types of three-phase coexistence areas and even a quadruple region with four coexisting phases.
9 pages, 4 figures
References in corpus (8)
- Measurement of a solid-state triple point at the metal-insulator transition in VO2
- Universal Phase Diagram for High-Piezoelectric Perovskite Systems
- Understanding shape entropy through local dense packing
- Entropy-driven formation of prolate and oblate cholesteric phases by computer simulations
- Nematic phase transitions in mixtures of thin and thick colloidal rods
- Shape Driven Solid--Solid Transitions in Colloids
- Phase diagram of hard colloidal platelets: a theoretical account
- Tracking three-phase coexistences in binary mixtures of hard plates and spheres