Effect of the linking unit on the twist-bend nematic phase in liquid crystal dimers: a comparative study of two homologous series of methylene- and ether-linked dimers

TY - JOUR

T1 - Effect of the linking unit on the twist-bend nematic phase in liquid crystal dimers

T2 - a comparative study of two homologous series of methylene- and ether-linked dimers

AU - Archbold, Craig T.

AU - Andrews, Jessica L.

AU - Mandle, Richard J.

AU - Cowling, Stephen J.

AU - Goodby, John W.

N1 - © 2016 Informa UK Limited, trading as Taylor & Francis Group. This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy. Further copying may not be permitted; contact the publisher for details

PY - 2017/1/2

Y1 - 2017/1/2

N2 - 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.

AB - 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.

KW - bimesogens

KW - Liquid crystals

KW - twist-bend nematic

UR - http://www.scopus.com/inward/record.url?scp=84990223172&partnerID=8YFLogxK

U2 - 10.1080/02678292.2016.1240247

DO - 10.1080/02678292.2016.1240247

M3 - Article

AN - SCOPUS:84990223172

SN - 0267-8292

VL - 44

SP - 84

EP - 92

JO - LIQUID CRYSTALS

JF - LIQUID CRYSTALS

IS - 1

ER -