Scattering from colloidal cubic silica shells: Part II, static structure factors and osmotic equation of state

F Dekker; B W M Kuipers; Á González García; R Tuinier; A P Philipse

doi:10.1016/j.jcis.2020.02.058

Scattering from colloidal cubic silica shells: Part II, static structure factors and osmotic equation of state

J Colloid Interface Sci. 2020 Jul 1:571:267-274. doi: 10.1016/j.jcis.2020.02.058. Epub 2020 Feb 29.

Authors

F Dekker¹, B W M Kuipers¹, Á González García², R Tuinier², A P Philipse³

Affiliations

¹ Van't Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute for Nanomaterials Science, Padulaan 8, 3584 CH, Utrecht University, the Netherlands.
² Van't Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute for Nanomaterials Science, Padulaan 8, 3584 CH, Utrecht University, the Netherlands; Laboratory of Physical Chemistry, Department of Chemical Engineering and Chemistry & Institute for Complex Molecular Systems, Eindhoven University of Technology, P.O. Box 513, 5600 MB, Eindhoven, the Netherlands.
³ Van't Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute for Nanomaterials Science, Padulaan 8, 3584 CH, Utrecht University, the Netherlands. Electronic address: A.P.Philipse@uu.nl.

PMID: 32203763
DOI: 10.1016/j.jcis.2020.02.058

Abstract

Hypothesis: The shape of colloidal particles affects the structure of colloidal dispersions. The effect of the cube shape on the thermodynamics of colloidal cube dispersions has not yet been studied experimentally. Static light scattering measurements on colloidal cubic silica shells at finite concentrations allows us to measure the structure factor of colloidal cube fluids and to test theoretical predictions for the equation of state of hard convex superballs.

Experiments: Hollow silica nanocubes of varying concentrations in N,N,-dimethylformamide were studied with static light scattering. The structure factor was extracted from the scattering curves using experimental form factors. From this experimental structure factor, the specific density of the particles, and the osmotic compressibility were obtained. This osmotic compressibility was then compared to a theoretical equation of state of hard superballs.

Findings: The first experimental structure factors of a stable cube fluid are presented. The osmotic compressibility of the cube fluid can be described by the equation of state of a hard superball fluid, showing that silica cubes in N,N,-dimethylformamide with LiCl effectively interact as hard particles.

Keywords: Colloidal cubic shells; Osmotic equation of state; Static light scattering; Static structure factor; Superballs.