[Soft-matter] Soft Matter and Complex Systems Seminar on 24 March 2023

[Maciej Lisicki]

Dear Soft Matter Colleagues and Friends,

On Friday 24 March 2023 at 9:30 AM at the UW Faculty of Physics (Pasteura 5, Warsaw; room 1.40) we are hosting a seminar during which

Michał Bogdan (IChF PAN)

will give a talk

Crystallization and topology-induced dynamical heterogeneities in soft granular clusters	

Authors: Michał Bogdan, Mihir Durve, Leon Jurkiewicz, Sauro Succi, Jan Guzowski

Abstract
	Soft-granular media such as dense emulsions, foams or tissues tend to exhibit either fluid- or solid-like properties depending on the applied stresses. However, the internal dynamics of soft granular systems bound by closed interfaces is poorly understood, while it remains of significant interest in diverse fields ranging from material science (porous materials) and tissue engineering (granular bioinks) to developmental biology (embryos, organoids) and medicine (circulating tumor cell clusters). Here, we report the spontaneous occurrence of crystalline-like hexagonal structures within soft granular clusters which self-organize under external flow. We use a densely packed double emulsion as a model soft granular material to produce clusters of sizes of 20-40 grains (droplets). We find that, optimally, the crystallites emerge under weak flows, when the internal shear stresses slightly agitate the system allowing internal rearrangements. Excessive flows destroy the delicate crystalline structure and lead to constant internal recirculations, i.e., effective fluidization of the granular medium. Upon subjecting the clusters to cycles of constriction and relaxation/expansion, we also find differences between the behaviours of two groups of droplets: those within the inner part of the cluster and those at its rim, with the latter subjected to larger deformations and less frequent rearrangements, effectively acting as an elastic solid-like membrane around the inner fluid-like core. This structural-dynamical heterogeneity appears to be of purely topological origin and as such we expect it to remain universal in various types of soft granular clusters or jets including also cell aggregates, organoids or bioprinted tissues.

We warmly welcome everyone to attend the talk and the Soft Matter Coffee Break after the seminar, held in room 2.63 (2nd floor).

Maria Ekiel-Jeżewska
Maciej Lisicki
Piotr Szymczak
Panagiotis Theodorakis
Marek Trippenbach





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