We present the diffusiophoresis of ellipsoidal particles induced by ionic solute gradients. Contrary to the common expectation that diffusiophoresis is shape independent, here we show experimentally that this assumption breaks down when the thin Debye layer approximation is relaxed. By tracking the translation and rotation of various ellipsoids, we find that the phoretic mobility of ellipsoids is sensitive to the eccentricity and the orientation of the ellipsoid relative to the imposed solute gradient, and can further lead to nonmonotonic behavior under strong confinement. We show that such a shape- and orientation-dependent diffusiophoresis of colloidal ellipsoids can be easily captured by modifying theories for spheres.
@article{arxiv.2302.11749,
title = {Shape- and orientation-dependent diffusiophoresis of colloidal ellipsoids},
author = {Viet Sang Doan and Dong-Ook Kim and Craig Snoeyink and Ying Sun and Sangwoo Shin},
journal= {arXiv preprint arXiv:2302.11749},
year = {2023}
}