Floating nematic phase in colloidal platelet-sphere mixtures

Abstract

The phase behaviour of colloidal dispersions is interesting for fundamental reasons and for technological applications such as photonic crystals and electronic paper. Sedimentation, which in everyday life is relevant from blood analysis to the shelf life of paint, is a means to determine phase boundaries by observing distinct layers in samples that are in sedimentation-diffusion equilibrium. However, disentangling the effects due to interparticle interactions, which generate the bulk phase diagram, from those due to gravity is a complex task. Here we show that a line in the space of chemical potentials ${\mu }_i$, where $i$ labels the species, represents a sedimented sample and that each crossing of this sedimentation path with a binodal generates an interface under gravity. Complex phase stacks can result, such as the sandwich of a floating nematic layer between top and bottom isotropic phases that we observed in a mixture of silica spheres and gibbsite platelets.

5 pages, 3 figures, http://www.nature.com/srep/2012/121109/srep00789/full/srep00789.html

References in corpus (4)

• Density functional theory for colloidal mixtures of hard platelets, rods, and spheres
• Highly nonlinear dynamics in a slowly sedimenting colloidal gel
• Structure and thermodynamics of platelet dispersions
• What buoyancy really is. A Generalized Archimedes Principle for sedimentation and ultracentrifugation

Cited by in corpus (18)

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• Structural nonequilibrium forces in driven colloidal systems
• Active ideal sedimentation: Exact two-dimensional steady states
• Gravity-induced phase phenomena in plate-rod colloidal mixtures
• Tracking three-phase coexistences in binary mixtures of hard plates and spheres
• Bulk fluid phase behaviour of colloidal platelet-sphere and platelet-polymer mixtures
• The role of sample height in the stacking diagram of colloidal mixtures under gravity
• Depletion-driven four-phase coexistences in discotic systems
• Reentrant Network Formation in Patchy Colloidal Mixtures under Gravity
• Sedimentation stacking diagram of binary colloidal mixtures and bulk phases in the plane of chemical potentials
• Sedimentation stacking diagrams of binary mixtures of thick and thin hard rods
• Composition inversion in mixtures of binary colloids and polymer
• Sedimentation of colloidal plate-sphere mixtures and inference of particle characteristics from stacking sequences
• Sedimentation path theory for mass-polydisperse colloidal systems
• Effect of sample height and particle elongation in the sedimentation of colloidal rods