title: Splay and bend elastic constants in the nematic phase of some disulfide bridged dimeric compounds.
abstract: We report measurements of the temperature dependences of the splay (K11) and bend (K33) elastic constants of several homologues and a binary mixture of disulfide bridged symmetric dimers made of alkoxy cyanobiphenyl monomeric units. All of them have an even number m of carbon and sulfur atoms in the linking chain and expected to have linear conformations. Both K(11) and K(33) alternate depending on the parity of x which is the number of carbon atoms in the alkyl chain of a monomer. We will refer to this as 'odd-even' effect. This effect, occurs near the nematic-isotropic transition temperature. T(NI), but monotonically decrease with m at lower temperatures. We argue that these results imply large rotational fluctuations of the two halves of the dimers about the S-S bond giving rise to average bent conformations near T(NI). At lower temperatures those conformations which can adapt better to the given curvature deformation in the medium are favored.
authors.affiliation: Liquid Crystal Institute, Tokyo University of Science, Yamaguchi, 1-1-1 Daigaku-Dori, San-yo-Onoda, Yamaguchi Prefecture 756-0884, Japan.
authors.forename: Brindaban
authors.initials: B
authors.lastname: Kundu
authors.forename: Santanu Kumar
authors.initials: SK
authors.lastname: Pal
authors.forename: Sandeep
authors.initials: S
authors.lastname: Kumar
authors.forename: R
authors.initials: R
authors.lastname: Pratibha
authors.forename: N V
authors.initials: NV
authors.lastname: Madhusudana