Undergraduate Honors Theses

Thesis Defended

Spring 2019

Document Type

Thesis

Type of Thesis

Departmental Honors

Department

Physics

First Advisor

Joseph MacLennan

Abstract

Smectic A and C liquid crystals are capable of forming incredibly thin films, discretized by the number of molecular layers. This property makes liquid crystal films ideal for studying 2D hydrodynamics, a field of great interest both due to its fundamental importance to physics and because of its applications to biological systems. The phospholipid bilayer which makes up cell membranes is itself an ideal 2D fluid as it consists of only two layers of phospholipids, however cell membranes are incredibly small and difficult to work worth. Liquid crystal films can be several millimeters across and stable for long periods of time. As part of the OASIS NASA experiment, a large number of experiments on bubbles of liquid crystal film in zero gravity were carried out. This thesis will use video of those experiments to draw conclusions about the hydrodynamics of smectic liquid crystal films without the influence of gravity. Analysis was performed of thermomigration experiments, coarsening experiments, and on terrestrial smectic C island diffusion experiments. A simulation based on the current understanding of coarsening, diffusion, and Ostwald ripening was constructed and compared to the experimental data, confirming our theoretical expectations. For the thermomigration experiments, thermally induced motion was observed and measured. The data suggest that the Marangoni effect is primarily responsible for this motion. For the smectic C analysis, where smectic C islands tended to form chains, it was found that islands in the chains tended to diffuse more in a direction perpendicular to the chain than in a direction parallel to the chain.

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