Date of Award

Spring 1-1-2012

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Physics

First Advisor

Noel A. Clark

Second Advisor

Joseph E. Maclennan

Third Advisor

Matthew A. Glaser

Abstract

Bent-core liquid crystals have attracted intense interest in recent years, exhibiting a wide variety of novel structural phenomena involving the interplay of chirality, molecular bend and molecular tilt. Freeze-fracture transmission electron microscopy together with other experimental methods has been used to characterize the nanostructures of bent-core liquid crystal phases in which the molecules undergo complex self-assembly, forming, for example, helical nanofilaments (the B4 phase), disordered focal conics (the DC phase), and layer undulations (the B7 phase) in the bulk. These studies have helped us better understand the complex nature of these and other liquid crystal phases. For example, the investigation of the chirality-preserving growth of the helical nanofilaments in the B4 phase will allow better control of its growth for applications, the discovery of the quasi-ordered toric focal conics of the DC phase at the air/liquid crystal interface opens the way for the development of two-dimensional or even three-dimensional periodic dielectric media for photonic crystal applications, the study of layer undulation defects reveals the detailed molecular arrangement in the B7 phase, and the discovery and characterization of the randomized twist grain boundary phase broads the understanding of chiral liquid crystal phases.

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