Transformation between elastic dipoles, quadrupoles, octupoles and hexadecapoles driven by surfactant self-assembly in nematic emulsion

TL;DR

This paper demonstrates how surfactant absorption or desorption can induce continuous and reversible transformations of elastic multipoles around droplets in nematic emulsions, enabling reconfigurable molecular alignment structures.

Contribution

It reveals a novel mechanism for controlling elastic multipole transformations in nematic emulsions through surfactant self-assembly and desorption.

Findings

Surfactant dynamics induce elastic multipole transformations.

Reversible switching between dipoles, quadrupoles, octupoles, and hexadecapoles.

Potential for reconfigurable and responsive nematic materials.

Abstract

Emulsions comprising isotropic fluid drops within a nematic host are of interest for applications ranging from biodetection to smart windows, which rely on changes of molecular alignment structures around the drops in response to chemical, thermal, electric and other stimuli. We show that absorption or desorption of trace amounts of common surfactants can drive continuous transformations of elastic multipoles induced by the droplets within the uniformly aligned nematic host. Out-of-equilibrium dynamics of director structures emerge from a controlled self-assembly or desorption of different surfactants at the drop-nematic interfaces, with ensuing forward and reverse transformations between elastic dipoles, quadrupoles, octupoles and hexadecapoles. We characterize inter-transformations of droplet-induced surface and bulk defects, probe elastic pair interactions and discuss emergent prospects for fundamental science and applications of the reconfigurable nematic emulsions.