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ABSTRACT
Two series of bimesogens with phenyl benzoate mesogenic units were prepared: one series having a heptamethylene spacer and the other a pentamethylene spacer with two ether-linking groups. These materials were prepared to provide experimental backing to the widely held hypothesis that methylene-linked bimesogens are more likely to exhibit the twist-bend nematic mesophase than their ether-linked counterparts. Several of the methylene-linked materials exhibited nematic and NTB mesophases, whereas the analogous ether-linked materials gave only nematic phases albeit with significantly higher clearing points. Virtual N–NTB transition temperatures for both methylene- and ether-linked bimesogens were extrapolated by constructing binary phase diagrams with the well-studied twist-bend material CB9CB. Contrary to our expectations these virtual transition temperatures were in most cases higher for the ether-linked bimesogens than in the analogous methylene compounds, this runs counter to reported theories and hypotheses that the incorporation of ether-linking groups should serve to destabilise the NTB phase.
Graphical Abstract
Acknowledgements
CTA thanks the University of York for funding this research through the award of a doctoral scholarship. The authors also recognise the support of the Engineering and Physical Sciences Research Council (EPSRC) via grant codes EP/J007714/1, EP/K039660/1 and EP/M020584/1. Raw data are available upon request from the University of York data catalogue.
Disclosure statement
No potential conflict of interest was reported by the authors.
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