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

Ewan Cruickshank* (Corresponding Author), Rebecca Walker, John M.D. Storey, Corrie T. Imrie

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

23 Citations (Scopus)
3 Downloads (Pure)

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.

Original languageEnglish
Pages (from-to)29482-29490
Number of pages9
JournalRSC Advances
Volume12
Issue number45
Early online date14 Oct 2022
DOIs
Publication statusPublished - 14 Oct 2022

Bibliographical note

Funding Information:
C.T.I. and J.M.D.S. acknowledge the financial support of the Engineering and Physical Sciences Research Council [EP/V048775/1].

Data Availability Statement

Electronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d2ra05628c

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