Abstract
We report two distinct types of two-dimensionally periodic phases in different concentration regions of a binary system composed of the bent-core (BC) compound (BC12) and the rodlike (R) compound (8OCB). BC12 exhibits only the lamellar phase. 8OCB which has a highly polar cyano end group exhibits the phase with a lamellar structure of partial bilayers made of antiparallel pairs of the polar molecules. The molecular arrangements in the two-dimensionally periodic phases have been deduced based on optical microscopy, polarized infrared and x-ray diffraction studies. The arrangement in the two-dimensionally periodic phase in lower concentration ranges of BC12 (24 to ) is dictated by the partial bilayer structure formed by the rods. The BC molecules arrange themselves with their arrow axes parallel to the long axes of the R molecules and the structure conforms to the space group symmetry. In higher concentration ranges of BC12 (35 to ) the structure is dominated by the BC molecules, to form the familiar phase with the space group symmetry. The R molecules lie at the interfaces of these domains stabilizing the structure.
12 More- Received 17 April 2004
DOI:https://doi.org/10.1103/PhysRevE.71.011701
©2005 American Physical Society