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

Hird, Mike; Lewis, Robert

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

Hird, M., & Lewis, R. (2010). The influence of an alkenyl terminal group on the mesomorphic behavior 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: Jan 1, 2010
• 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: alkylalkenyloxyfluoroterphenyl liq crystal nematic dielec anisotropy threshold voltage switching
• Public URL: https://hull-repository.worktribe.com/output/418041