Novel liquid crystals with bulky terminal groups for ferroelectric displays in nanotechnology

Pashameah, Rami Adel

Abstract

The field of liquid crystals has become the focus of extensive research over the last century in terms of the design, synthesis and evaluation of novel materials, and the development of high technology applications, particularly displays. Virtually all current liquid crystal displays are based on the nematic phase, however, ferroelectric liquid crystal displays based on the chiral smectic C phase offers many advantages such as faster switching, higher resolution and contrast, bistability and wider angles of view. Although ferroelectric microdisplays are a commercial success, the technology is currently severely limited in their applicability because of problems in aligning the molecules in the ideal so-called bookshelf configuration. A wide range of novel materials has been designed, synthesized and evaluated. The main feature of the molecular design is the inclusion of a bulky group as part of a terminal chain, designed to cause a phase separation and preclude layer shrinkage on formation of the smectic C phase, and hence generate the desired bookshelf alignment. The synthesis was affected most efficiently using a range of synthetic methods, in particular low temperature lithiations and Suzuki coupling reactions. The materials were evaluated for structure and purity, and for mesomorphic and physical properties. The majority of the novel materials exhibit the smectic C phase over a wide temperature range, some compounds generate solely the smectic C phase whereas other additionally show the smectic A and nematic phases, and these results helps to establish patterns of how the mesomorphism relates to the structure of the bulky terminal group. Selected novel compounds were mixed with an established ferroelectric host mixture (KCHM211) to generate a range of novel ferroelectric host mixtures, which were doped with an established chiral dopant (BE8OF2N) to generate a range of novel ferroelectric mixtures, which were evaluated for their ferroelectric properties, namely tilt angle and spontaneous polarization. The results in terms of synthesis, mesomorphism and ferroelectric properties are discussed comparatively between novel compounds and known compounds.

Citation

Pashameah, R. A. Novel liquid crystals with bulky terminal groups for ferroelectric displays in nanotechnology. (Thesis). University of Hull. https://hull-repository.worktribe.com/output/4222304

• Thesis Type: Thesis
• Deposit Date: Mar 11, 2020
• Publicly Available Date: Feb 23, 2023
• Keywords: Chemistry
• Public URL: https://hull-repository.worktribe.com/output/4222304
• Additional Information: Department of Chemistry, The University of Hull
• Award Date: Jul 1, 2015