X-RAY STUDIES OF LIQUID CRYSTALS VI THE STRUCTURE OF THE SMECTIC A, C, Bn AND Bt PHASES OF TRANS-1,4-CYCLOHEXANE-DI-N-OCTYLOXYBENZOATE

Abstract

The smectic A phase of trans-1,4-cyclohexane-di-n-octyloxybenzoate (TCOB) appears to be a tilted smectic A phase. The uniaxial character of the phase is not caused by an absence of tilt, but rather by an absence of long-range order of the direction of tilt. The C-A phase transition is marked by the disappearance of this long-range order. The smectic B phases of TCOB are different from most other B phases because of an unusually large disorder in the alkyl end-chains of the molecule, the result of the large intermolecular distance caused by the cyclohexane ring in the center of the molecule. The disorder in the alkyl chains disrupts the coupling between adjacent layers. As a consequence, the tilted smectic B phase has no three-dimensional order