Scattering from colloidal cubic silica shells: Part I, particle form factors and optical contrast variation

F Dekker; B W M Kuipers; A V Petukhov; R Tuinier; A P Philipse

doi:10.1016/j.jcis.2019.11.002

Scattering from colloidal cubic silica shells: Part I, particle form factors and optical contrast variation

J Colloid Interface Sci. 2020 Jul 1:571:419-428. doi: 10.1016/j.jcis.2019.11.002. Epub 2019 Nov 20.

Authors

F Dekker¹, B W M Kuipers¹, A V Petukhov², 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: 31813577
DOI: 10.1016/j.jcis.2019.11.002

Abstract

Hypothesis: Colloidal cubic silica shells, prepared from cuprous oxide cubes, with a typical size of 100 nm are promising model particles for scattering studies on dilute, as well as concentrated fluids, of non-spherical colloids.

Experiments: Small angle X-ray scattering, and static light scattering are employed to determine form factors of cubic silica shells and silica covered cuprous oxide cubes. Contrast variation experiments are performed to assess the refractive index and optical homogeneity of the cubic silica shells, which is important for the extension of the scattering study to concentrated dispersions of cubic shells in Part II (Dekker, submitted for publication).

Results: The experimental form factors, which compare well to theoretical form factors, manifest cubic silica shells that are dispersed as single stable colloids with a shape intermediate between a sphere and a perfect cube. Contrast variation demonstrates that the silica shells are optically homogeneous, with a refractive index that is independent of the shell thickness. The results presented here open up the possibility to extract structure factors from light scattering measurements on concentrated cube dispersions in Part II.

Keywords: Colloidal core-shell particles; Colloidal cubic shells; Contrast variation; Guinier approximation; Particle form factor; Small angle X-ray scattering; Static light scattering.