Date of Award

Spring 2011

Document Type

Restricted Thesis

Terms of Use

© 2011 Elizabeth Mills. All rights reserved. Access to this work is restricted to users within the Swarthmore College network and may only be used for non-commercial, educational, and research purposes. Sharing with users outside of the Swarthmore College network is expressly prohibited. For all other uses, including reproduction and distribution, please contact the copyright holder.

Degree Name

Bachelor of Arts

Department

Physics & Astronomy Department

First Advisor

Peter J. Collings

Abstract

IR-806 is an infrared absorbing chromonic liquid crystal that forms a liquid crystal phase at around 0.45 wt% at room temperature. It has a unique coexistence region whereby there is not ever a distinct separation of phase between the isotropic liquid and liquid crystal regions, only a decrease in birefringence everywhere. Also, IR-806's most stable conformation (in gas form) was obtained, and it was found to be most stable in its AA conformation. Unfortunately, it was discovered that IR-806 is not stable in solution, quickly degrading in acidic environments, and not completely stable in any aqueous environment. The decay times of a 0.0005 wt% solution were 21 ± 1.6 hours at pH 2.S and lOS ± 1.6 hours at pH 7.3. It is least stable at low concentrations, but was also found to degrade in solution at liquid crystal phase concentrations.

IR-806 exhibits a very dynamic absorption spectra, with three distinct peaks that vary in amplitude depending on concentration. These peaks can be connected to the formation of different aggregate species in solution as concentration changes. Analysis of these peaks support the idea that there is a distinct structural change between the aggregates before the liquid crystal phase. Analysis of the low concentration peak amplitude (or monomer peak) allowed for a calculation of stacking free energy change. IR-806 was found to have a stacking free energy change of 9.01 ± 0.12 kBT.

Although it may not have long term applications due to its instability in solution, IR-806 might be able to shed light on how other chromonics aggregate at concentrations lower than their liquid crystal phase. This report discusses the investigation of such chromonic and liquid crystal properties not only with the purpose of learning more about IR-806, but also of applying this insight to other chromonic liquid crystals.

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