title: Flexoelectric and elastic coefficients of odd and even homologous bimesogens.
abstract: It is known that bimesogenic liquid crystals exhibit a marked "odd-even" effect in the flexoelastic ratio (the effective flexoelectric coefficient to the average elastic coefficient), with the ratio being higher for the "odd-spaced" bimesogens (those with an odd number of alkyl groups in the spacer chain) than their neighboring even-spaced counterparts. To determine the contribution of each property to the flexoelastic ratio, we present experimental results on the flexoelectric and elastic coefficients of two homologous nonsymmetric bimesogens which possess odd and even alkyl spacers. Our results show that, although there are differences in the flexoelectric coefficients, there are substantially larger differences in the effective elastic coefficient. Specifically, the odd bimesogen is found to have both a low splay elastic coefficient and a very low bend elastic coefficient which, when combined, results in a significantly lower effective elastic coefficient and consequently a higher flexoelastic ratio.
authors.affiliation: Centre of Molecular Materials for Photonics and Electronics, Electrical Engineering Division, Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA, United Kingdom.
authors.forename: Katie L
authors.initials: KL
authors.lastname: Atkinson
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Morris
authors.forename: Flynn
authors.initials: F
authors.lastname: Castles
authors.forename: Malik M
authors.initials: MM
authors.lastname: Qasim
authors.forename: Damian J
authors.initials: DJ
authors.lastname: Gardiner
authors.forename: Harry J
authors.initials: HJ
authors.lastname: Coles
mesh_terms: D003198:Computer Simulation; D055119:Elastic Modulus; D004574:Electromagnetic Fields; D050866:Liquid Crystals / Q000737:chemistry* / Q000528:radiation effects*; D008956:Models, Chemical; D008958:Models, Molecular