Possible structures for the lamellar–isotropic (Lam‐I) and lamellar–nematic (Lam‐N) liquid crystalline phases

Abstract

The three refractive indices of a liquid crystal that exhibits lamellar analogues of the three‐dimensional isotropic, nematic, and smectic A phases are reported as functions of temperature for the Lam‐I and Lam‐N phases. The data suggest a number of striking behaviour types. The orientational distribution of the mesogenic moieties becomes more highly peaked in two dimensions on cooling from the Lam‐I to the Lam‐N phase; the two‐dimensional order associated with mesogenic director n in the Lam‐N phase is weak; and conformational changes in the side chain result in an increase in the refractive index perpendicular to the lamellae with decreasing temperature in the Lam‐N phase.

Acknowledgements

We thank Prof. Rolfe G. Petschek for useful discussions. This work was supported by the Deutsche Forschungsgemeinschaft under grants TS 39/11‐3 and GRK 894, by the National Science Foundation under grant DMR‐0345109, and by the Donors of the Petroleum Research Fund, administered by the American Chemical Society, under grant 37736‐AC7.