(490h) Dynamics of Chains and Disks Formation in Superparamagnetic Colloids Submitted to Magnetic Fields in Different Configurations

When exposed to an external magnetic field, superparamagnetic colloids form specific structures which depend on the features of the external field. If the magnetic field is constant along time, superparamagnetic colloids self-organize into chains oriented in the direction of the field. If the magnetic field is rotating in the plane of the suspension, below a critical frequency, the superparamagnetic beads still aggregate into chains, but these chains rotate with the magnetic field. When the rotation reaches a certain speed, the colloids aggregate in rotating disklike clusters. In this presentation, we will review a set of experimental results obtained recently. We will start with the study of chains and disks formation dynamics. Afterward the influence of magnetic interactions on the coffee-ring effect will be investigated.

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Effect of volume fraction on chains of superparamagnetic colloids at equilibrium, A. Darras, E. Opsomer, N. Vandewalle and G. Lumay, European Physical Journal E 42, 13 (2019)

Combined effects of Marangoni, sedimentation and coffee-ring flows on evaporative deposits of superparamagnetic colloids, A. Darras, N. Vandewalle and G. Lumay, Colloids and Interface Science Communications 32, 100198 (2019)

Superparamagnetic colloids in rotating field : transition state from chains to disks, F. Mignolet, A. Darras, and G. Lumay, submitted to Physical Review E