Effect of molecular structure on the phase behaviour of some liquid crystalline compounds and their binary mixtures VI[1]. The effect of molecular length

Abstract

The apparent solution dipole moments of compounds based on 4,4-di-substituted phenyl benzoate (ROC6H4COOC6H4X), I, where X is a cyano group and R a terminal linear alkyl chain ranging from C12 to C20, were determined in cyclohexane at 30 C. The compounds were also thermally characterized by polarized light microscopy and differential scanning calorimetry. Phase diagrams were constructed for various binary mixtures prepared from any two homologues of series I as well as for every one of them with the nitro analogue II, where X is a nitro group and R C16H33. The study was undertaken in order to investigate the effect of the alkyl chain length on the mesophase behaviour. In order to assess the influence of structural variation in the central mesogenic group on the mesophase stability of pure and mixed compounds, the investigation was extended to cover binary mixtures of any two of the three compounds: analogue II (X=OC16H33), and the symmetric dialkoxy substituted phenyl esters (C16H33OC6H4COO)2 A, where A is the 1,4-phenylene group (IV) or 4,4-biphenylene (V).