Pretransitional effects in the isotropic phases of some alkyl cyanobiphenyls (n=8, 9, 11 and 12)

Abstract

The pretransitional effects occurring in the isotropic phase of the higher homologues in the alkyl-cyanobiphenyl series (CNϕϕC _n H_2n+1) have been studied by the optical Kerr effect for n = 8, 9, 11, 12 and by flexoelectricity for n = 8 and 9. Both the amplitude and the dynamics of the induced order are shown to deviate from the predictions of the Landau-de Gennes theory. The results are discussed in terms of a recent theory of the isotropic-nematic phase transition adapted for the case of smectogenic compounds.