Article

# Sedimentation and multi-phase equilibria in mixtures of platelets and ideal polymer

EPL (Europhysics Letters) (Impact Factor: 2.26). 01/2007; 66(1):125. DOI: 10.1209/epl/i2003-10140-1

Source: OAI

- Citations (0)
- Cited In (5)

- [Show abstract] [Hide abstract]

**ABSTRACT:**We present a study of the interface between fluid–fluid phase separated colloid–polymer mixtures of identical composition but with varying suspension height. The significance of the sedimentation gradient present in the suspension is controlled by the ratio between the suspension height and the gravitational length of the colloids. We demonstrate that increasing the suspension height, and thus the importance of gravity leads to a systematic roughening of the gas–liquid interface as if one approaches the critical point. By carefully tuning the system height, the suspension can be brought arbitrarily close to criticality, irrespective of the overall composition of colloid and polymer. Our findings are based on measurements of the interfacial tension and capillary wave properties and supported by predictions from a simple density functional theory.Soft Matter 01/2010; 6(2). · 4.15 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**The observation of stacks of distinct layers in a colloidal or liquid mixture in sedimentation-diffusion equilibrium is a striking consequence of bulk phase separation. Drawing quantitative conclusions about the phase diagram is, however, very delicate. Here we introduce the Legendre transform of the chemical potential representation of the bulk phase diagram to obtain a unique stacking diagram of all possible stacks under gravity. Simple bulk phase diagrams generically lead to complex stacking diagrams. We apply the theory to a binary hard core platelet mixture with only two-phase bulk coexistence, and find that the stacking diagram contains six types of stacks with up to four distinct layers. These results can be tested experimentally in colloidal platelet mixtures. In general, an extended Gibbs phase rule determines the maximum number of sedimented layers to be $3+2(n_b-1)+n_i$, where $n_b$ is the number of binodals and $n_i$ is the number of their inflection points.Soft Matter 05/2013; 9:8636. · 4.15 Impact Factor - [Show abstract] [Hide abstract]

**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 µi, 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.Scientific Reports 11/2012; 2:789. · 5.08 Impact Factor

Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.