The effect of a lateral alkyloxy chain on the ferroelectric nematic phase.

Cruickshank, Ewan; Walker, Rebecca; Storey, John M. D.; Imrie, Corrie T.

Abstract

The synthesis and characterisation of two series of low molar mass liquid crystals, the 4-[(4-nitrophenoxy)carbonyl]phenyl 2-alkoxy-4-methoxybenzoates (series 5-m) and the 4-[(3-fluoro-4-nitrophenoxy)carbonyl]phenyl 2-alkoxy-4-methoxybenzoates (series 6-m) are reported in order to explore the effects of a lateral alkyloxy chain on the formation and stability of the recently discovered ferroelectric nematic phase. In both series m, the number of carbon atoms in the lateral chain, is varied from one to nine. The two series differ by the addition of a fluorine substituent in the 6-m series. 5-1 is the extensively studied ferroelectric nematogen RM734. All the members of the 5-m series exhibited both a conventional nematic, N, and ferroelectric nematic, NF, phase, whereas all the members of the 6-m series exhibit a direct NF–I transition with the exception of 6-1 that also exhibits a N phase. The replacement of a hydrogen atom by a fluorine atom reduces the nematic–isotropic transition temperature, TNI, whereas the ferroelectric nematic–nematic, or isotropic, transition temperature, TNFN/I, increases. This is interpreted in terms of the reduced structural anisotropy associated with the larger fluorine atom whereas the increase in the stability of the NF phase reflects changes in polarity and polarizability. The dependence of TNI and TNFN/I on m in both series is similar, and these initially decrease on increasing m but converge to limiting values on further increasing m. This suggests that the lateral alkyloxy chain may adopt conformations in which it lies along the major axis of the mesogenic unit.

Citation

CRUICKSHANK, E., WALKER, R., STOREY, J.M.D. and IMRIE, C.T. 2022. The effect of a lateral alkyloxy chain on the ferroelectric nematic phase. RSC advances [online], 12(45), pages 29482-29490. Available from: https://doi.org/10.1039/D2RA05628C

• Journal Article Type: Article
• Acceptance Date: Oct 6, 2022
• Online Publication Date: Oct 14, 2022
• Publication Date: Oct 25, 2022
• Deposit Date: Aug 10, 2023
• Publicly Available Date: Aug 10, 2023
• Journal: RSC advances
• Electronic ISSN: 2046-2069
• Publisher: Royal Society of Chemistry
• Peer Reviewed: Peer Reviewed
• Volume: 12
• Issue: 45
• Pages: 29482-29490
• DOI: https://doi.org/10.1039/d2ra05628c
• Keywords: Liquid crystals; Ferroelectric nematics; Optical studies; Differential scanning calorimetry; Molecular modelling
• Public URL: https://rgu-repository.worktribe.com/output/2010288
• Additional Information: This article has been published with separate supporting information. This supporting information has been incorporated into a single file on this repository and can be found at the end of the file associated with this output.