Structure features of self-assembly and diffusion in polydisperse emulsions

Abstract

Abstract: Polydispersity is among the most common properties of matter, important for food science, drug delivery and biotechnology. However, despite its significance, the influence of polydispersity on self-assembly remains poorly understood.
We used experiments with a monolayer polydisperse oil-in-water emulsion in a rotating electric field, to create a long-range dipole attraction.
Here we found that there are two distinct mechanisms providing self-assembly: the assembly of particles at condensation centres and the merging of clusters. The rate of particle assembly at the crystallisation centres was observed to increase quadratically with increasing electric field amplitude. Moreover, it was demonstrated that there exists an electric field amplitude value between the condensation point and the freezing point, which ensures the assembly of the largest clusters.
We established that up to the fourth layer of the cluster, the average particle diameter increases and from the fifth layer onwards, the it decreases. This observation can be explained by the structural transformation that occurs during cluster coalescence, which results in smaller particles being trapped within the cluster.
We found that the Stokes–Einstein relation is not fulfilled for polydisperse emulsions. The dependence of the diffusion coefficient on the electric field amplitude allowed to be determined as the dynamic freezing criterion is fulfilled for polydisperse systems with dipole-dipole attraction.
The results reveal a novel regularity and will aid development of new materials and 3-D bioprinting.

This work was supported by the Russian Science Foundation, Grant No. 22-72-10128

Speaker

Ivan A. Kushnir
Bauman Moscow State Technical University, Moscow, Russia
Russia

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