Electric field driven hierarchical self-assembly of polydisperse colloidal emulsion.

Abstract

This study demonstrates the tunable self-assembly of polydisperse colloidal microdroplets (particles) governed by a high-frequency (30 kHz) rotating electric field, presenting a novel approach for designing advanced biomimetic materials. We experimentally investigated BSA-stabilized oil-in-water microdroplets deposited on a substrate under a 30 kHz in-plane rotating field, which induces tunable long-range attractive dipole-dipole interactions between particles. The assembly dynamics were characterized in real-time using high-resolution optical microscopy (40x magnification), with subsequent computational analysis enabling precise tracking of individual particles, cluster identification, and detailed segmentation of internal stratification.
We discovered two distinct stratification regimes. Small clusters exhibit core localization of larger particles. However, larger clusters demonstrate a non-intuitive structure where big particles are stably localized in an intermediate layer. Our theoretical model and simulations confirm that this stratification is not a kinetic artifact but a thermodynamically stable equilibrium state resulting from a competitive minimization of the system's interaction energy under specific conditions of size polydispersity and magnitude of the governing field.
This ability to precisely engineer hierarchical microstructure by tuning field parameters and population composition provides a powerful tool for bottom-up fabrication. The results pave the way for novel applications in bioprinting and tissue engineering, where the creation of complex, multi-scale patterns with specific compositional gradients is essential for mimicking sophisticated biological architectures.

Speaker

Ivan V. Simkin
Bauman Moscow State Technical University, 2nd Baumanskaya street 5, Moscow, 105005, Russia
Russia

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