Surface wrinkling of freely-floating smectic bubbles

TL;DR

This study investigates the formation and characteristics of surface wrinkles and protrusions on freely-floating smectic liquid crystal bubbles, revealing mechanisms of deformation and the influence of external forces.

Contribution

It introduces new insights into how external forces and bubble dynamics induce surface wrinkling and protrusions in smectic liquid crystal bubbles.

Findings

Wrinkles depend on force direction.

Wavelength of wrinkles varies over time.

Small protrusions (tubuli) form outside the film.

Abstract

Bubbles made of smectic liquid crystals (LC) can display buckling and wrinkling. These deformations are induced in the course of the relaxation of an elongated bubble towards a sphere. The bubbles are created through the collapse of a catenoid LC film. Two mechanisms leading to wrinkles are reported: (a) Compression of the smectic film by outer forces, and (b) Invagination of the bubble shortly after formation. The flow on the bubble surface is analyzed, providing insight into how the outer forces act on the bubble and induce local surface deformation. It is found that the orientation of the wrinkles depends on the direction of the acting force. The wavelength of the wrinkles is analyzed over time. Additionally, the formation of small protrusions outside the film area (i.e., tubuli) is described.