# Effect of sample height and particle elongation in the sedimentation of colloidal rods

T. Eckert, M. Schmidt, D. de las Heras

Soft Matter, **19**, 2214, (2023) DOI: 10.1039/D3SM00191A

Full text: journal (feel free to email me if you want a copy of this paper!)

**Abstract**:

We study theoretically the effect of a gravitational field on the equilibrium behaviour of a colloidal suspension of rods with different length-to-width aspect ratios. The bulk phases of the system are described with analytical equations of state. The gravitational field is then incorporated via sedimentation path theory, which assumes a local equilibrium condition at each altitude of the sample. The bulk phenomenology is significantly enriched by the presence of the gravitational field. In a suspension of elongated rods with five stable phases in bulk, the gravitational field stabilizes up to fifteen different stacking sequences. The sample height has a non-trivial effect on the stable stacking sequence. New layers of distinct bulk phases appear either at the top, at the bottom, or simultaneously at the top and the bottom when increasing the sample height at constant colloidal concentration. We also study sedimentation in a mass-polydisperse suspension in which all rods have the same shape but different buoyant masses.

**Additional material/comments**:

Download the full text for this article: journal (feel free to email me if you want a copy of this paper!)

**Related publications**:

**1** *Sedimentation path theory for mass-polydisperse colloidal systems* (+ info)

**2** *The role of sample height in the stacking diagram of colloidal mixtures under gravity* (+ info)

**3** *Sedimentation of colloidal plate-sphere mixtures and inference of particle characteristics from stacking sequences* (+ info)

**4** *Gravity-induced phase phenomena in plate-rod colloidal mixtures* (+ info)

**5** *Reentrant Network Formation in Patchy Colloidal Mixtures under Gravity* (+ info)

**6** *Sedimentation stacking diagram of binary colloidal mixtures and bulk phases in the plane of chemical potentials* (+ info)

**7** *The phase stacking diagram of colloidal mixtures under gravity* (+ info)

**8** *Floating nematic phase in colloidal platelet-sphere mixtures* (+ info)