The ferroelectric nematic phase: on the role of lateral alkyloxy chains.

Cruickshank, Ewan; Pearson, Abigail; Brown, Stevie; Storey, John M.D.; Imrie, Corrie T.; Walker, Rebecca

Abstract

The synthesis and characterisation of the 4-({[4’-nitro-(1,1'-biphenyl)−4-yl]oxy}carbonyl)phenyl 2-alkoxy-4-methoxybenzoates are reported: the 1O(m-On)PEPEBNO2 series. These materials include an additional phenyl ring compared to the extensively studied ferroelectric nematogen RM734, added to increase the liquid crystal transition temperatures. All members of the series exhibited both conventional nematic (N) phase and ferroelectric nematic (NF) phases; TNI and TNFN both decrease on increasing n, the length of the lateral alkoxy chain. The properties of this four-ring series are compared with analogous three-ring laterally substituted variants of RM734; the addition of the extra phenyl ring has a significantly more pronounced effect on the value of TNI than on TNFN. The increase in TNI may be attributed to the enhanced structural anisotropy and more favourable intermolecular interactions arising from the insertion of the phenyl ring, whereas the much weaker effect on TNFN may reflect a change in the shape of the molecule. We also report two materials with three-ring structures, the 4'-nitro-(1,1'-biphenyl)-4-yl 2-alkoxy-4-methoxybenzoates: 1O(m-On)PEBNO2 (n=1 and 2). The removal of the ester linkage between RM734 and 1O(m-O1)PEPNO2 extinguishes the NF phase and this appears to be consistent with a model in which the molecules are described in terms of a longitudinal surface charge density wave.

Citation

CRUICKSHANK, E., PEARSON, A., BROWN, S., STOREY, J.M.D., IMRIE, C.T. and WALKER, R. 2023. The ferroelectric nematic phase: on the role of lateral alkyloxy chains. Liquid crystals [online], 50(11-12), pages 1960-1967. Available from: https://doi.org/10.1080/02678292.2023.2221651

• Journal Article Type: Article
• Acceptance Date: May 2, 2023
• Online Publication Date: Jun 12, 2023
• Publication Date: Oct 31, 2023
• Deposit Date: Aug 10, 2023
• Publicly Available Date: Aug 10, 2023
• Journal: Liquid crystals
• Print ISSN: 0267-8292
• Electronic ISSN: 1366-5855
• Publisher: Taylor and Francis
• Peer Reviewed: Peer Reviewed
• Volume: 50
• Issue: 11-12
• Pages: 1960-1967
• DOI: https://doi.org/10.1080/02678292.2023.2221651
• Keywords: Ferroelectric nematic phase; Ferronematic; Lateral substituents; Calamitic
• Public URL: https://rgu-repository.worktribe.com/output/2010354