The influence of an alkenyl terminal group on the mesomorphic behaviour and electro-optic properties of fluorinated terphenyl liquid crystals

Gasowska, Julita S.; Cowling, Stephen J.; Cockett, Martin C. R.; Hird, Michael; Lewis, Robert A.; Raynes, E. Peter; Goodby, John W.

Abstract

Novel liquid crystal terphenyls with two, three and four lateral fluoro substituents and an alkene unit at the end of a terminal chain are presented in terms of synthesis, mesomorphic behaviour and electro-optic properties. The difluoro analogues were found to exhibit the smectic C phase over a wide temperature range, with short temperature ranges of the smectic A and the nematic phase above. Very low melting points were recorded for the trifluoro analogues, and the shorter chain homologues of these materials exhibit the nematic phase over a wide temperatures with a monotropic smectic C phase and the higher homologues exhibit the smectic C phase over a wide temperature range with the nematic phase above. The tetrafluoroterphenyls exhibit the nematic phase over a wide temperature range with the complete absence of smectic phases. As appropriate, the materials were evaluated for dielectric anisotropy and threshold voltage in nematic phase, and mixed with a chiral dopant to evaluate the spontaneous polarisation, tilt angle and switching times in the chiral smectic C phase. The results show that these compounds are strong potential candidates for application in both vertically aligned nematic (VAN) and ferroelectric liquid crystal (FLC) devices.

Citation

Gasowska, J. S., Cowling, S. J., Cockett, M. C. R., Hird, M., Lewis, R. A., Raynes, E. P., & Goodby, J. W. (2010). The influence of an alkenyl terminal group on the mesomorphic behaviour and electro-optic properties of fluorinated terphenyl liquid crystals. Journal of Materials Chemistry, 20(2), 299-307. https://doi.org/10.1039/b914260f

• Journal Article Type: Article
• Acceptance Date: Sep 29, 2009
• Online Publication Date: Nov 11, 2009
• Publication Date: Jan 1, 2010
• Journal: JOURNAL OF MATERIALS CHEMISTRY
• Print ISSN: 0959-9428
• Publisher: Royal Society of Chemistry
• Peer Reviewed: Peer Reviewed
• Volume: 20
• Issue: 2
• Pages: 299-307
• DOI: https://doi.org/10.1039/b914260f
• Keywords: Materials Chemistry; General Chemistry
• Public URL: https://hull-repository.worktribe.com/output/387113