Topological charges drive morphogenesis in liquid droplets

by Eli Sloutskin

at Condensed Matter Seminar

Mon, 01 Jan 2018, 11:30
Physics building (#54) room 207

Abstract

Among all possible shapes of a volume V a sphere has the smallest surface area A Therefore liquid droplets are spherical minimizing their interfacial energy gamma A for a given interfacial tension gamma We demonstrate that liquid oil e g hexadecane droplets in water stabilized by a common surfactant e g octadecyltrimethylammonium bromide adopt icosahedral and other faceted shapes tunable by temperature while still remaining liquid 1 2 Although liquid droplets have been studied for centuries no faceted droplets have ever been detected We attribute the observed transition from a spherical to an icosahedral shape to the interplay between gamma and the elastic properties of the interfacial monomolecular layer which in these systems crystallizes above the bulk melting point The role of topological lattice defects in this quasi two dimensional crystalline surface monolayer will be discussed The shape of the droplets is determined by the topological charges of these defects i e the number of nearest neighbours missing at each defect location with the icosahedral droplets transforming on cooling into platelet like rectangular hexagonal hexagram like and other faceted shapes Remarkably the topological charges which form in this system are unusually high for the soft matter 3 In addition to faceting we observe a wide range of other unexpected phenomena such as a spontaneous splitting of liquid droplets The common physical mechanism responsible for all these effects will be demonstrated 1 3 These phenomena allow deeper insights into the fundamentals of molecular elasticity to be gained mimicking morphogenetic transitions in complex biological systems and opening new horizons for a wide range of technologies from self assembly of complex colloidal shapes to new delivery strategies in bio medicine 1 S Guttman Z Sapir M Schultz A V Butenko B M Ocko M Deutsch and E Sloutskin Proc Natl Acad Sci USA 113 493 2016 2 S Guttman B M Ocko M Deutsch and E Sloutskin Curr Opin Colloid Interface Sci 22 35 2016 3 S Guttman Z Sapir B M Ocko M Deutsch and E Sloutskin Langmuir 33 1305 2017

Created on 26-12-2017 by Bar Lev, Yevgeny (ybarlev)
Updaded on 26-12-2017 by Bar Lev, Yevgeny (ybarlev)