CUED Publications database

Structure-flexoelastic properties of bimesogenic liquid crystals

Morris, SM and Clarke, MJ and Blatch, AE and Coles, HJ (2007) Structure-flexoelastic properties of bimesogenic liquid crystals. Physical Review E - Statistical, Nonlinear, and Soft Matter Physics, 75. ISSN 1539-3755

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Abstract

In this paper, we report on the flexoelastic and viscoelastic ratios for a number of bimesogens compounds with the same generic structure. Values are obtained indirectly by measuring the flexoelectro-optic response in the chiral nematic phase. By varying the molecular structure we alter the bend angle, transverse dipole moment, and length of the molecule. First, to examine the influence of the bend angle we use a homologous series whereby the only alteration in the molecular structure is the number of methylene units in the aliphatic spacer, n. Results show that the flexoelastic ratio, e K, and the effective flexoelectric coefficient, e, both exhibit an odd-even effect with values for n=odd being greater than that for n=even. This is understood in terms of an increase in the bend angle of the molecule and an increase in the transverse dipole moment. Second, in order to investigate the impact of the dipole moment, we have altered the mesogenic units so as to vary the longitudinal dipole moment and used different linkages in the aliphatic spacer in an attempt to alter the transverse dipole moment. Qualitatively, the results demonstrate that the odd-spaced bimesogen with larger transverse dipole moments exhibit larger flexoelastic ratios. © 2007 The American Physical Society.

Item Type: Article
Subjects: UNSPECIFIED
Divisions: Div B > Photonics
Depositing User: Cron Job
Date Deposited: 07 Mar 2014 11:40
Last Modified: 08 Dec 2014 02:36
DOI: 10.1103/PhysRevE.75.041701