Self-decoration and magic number structures in liquid polyhedra

by Prof. Eli Sloutskin

Physics Department and Institute of Nanotechnology & Advanced Materials, Bar-Ilan University
at Biological and soft-matter physics

Thu, 22 Dec 2022, 12:10
Sacta-Rashi Building for Physics (54), room 207


Contrary to everyday experience, where all liquid droplets assume rounded, near-
spherical shapes, we have demonstrated that liquid oil-in-water and water-in-oil droplets
undergo temperature-controllable self-faceting shape transitions, with their bulk remaining
liquid. These transitions occur for a wide range of different chemical compositions, for
broad temperature ranges, and in droplets of sizes spanning an incredible 13 decades in
volume, from nano- to yocto- liters. We have demonstrated that the effect is driven by a
few-nm thick interfacial crystal, self-assembled at the surface of these liquid droplets. The
closed-surface topology of this geometrically frustrated, quasi-two-dimensional hexagonal
crystal dictates the formation of lattice defects, controlling the precise shapes adopted by
the droplets. Similar physical mechanisms may play a fundamental role in shape formation
in a wide range of biological systems: from viruses to living organisms [1].

Recently, we developed a strategy, allowing these droplets to be decorated by precisely
self-positioned molecules or nanoparticles. The achieved topology-controlled self-
decoration opens new routes towards the self-assembly of complex higher-hierarchy liquid
and solid structures [2].

In the last part of my talk, I will demonstrate that doping the system by a sub-percent
concentration of long-chain alcohol molecules dramatically increases the self-faceting
temperature, by >20 C. Furthermore, we observe that the faceting temperature exhibits
strong peaks for several magic alcohol chain lengths, indicating a non-trivial variation of
the interfacial structure, which is not yet fully understood.

[1] Marin et al., Curr. Opin. Colloid Interface Sci. 49, 107 (2020)
[2] Das et al., Nat. Phys. 18, 1177 (2022)

Created on 18-12-2022 by Feingold, Mario (mario)
Updaded on 18-12-2022 by Feingold, Mario (mario)