FORMATION OF COLUMNAR AND LAMELLAR LYOTROPIC MESOPHASES BY FACIAL AMPHIPHILES WITH PROTIC AND LIPOPHILIC SOLVENTS

The influence of water, formamide, and n-dodecane on the liquid crystalline properties of several rodlike 4,4‘‘-bis(decyloxy)-p-terphenyl derivatives incorporating nonionic hydrophilic groups in a central position was investigated by polarizing microscopy and X-ray scattering. Up to three different rectangular columnar mesophases have been found for molecules with large hydrophilic groups with increasing concentrations of protic solvents. Remarkably only one lattice parameter changes in dependence on the mesophase type and the number of solvent molecules coordinated to the polar groups. We propose that the columns represent ribbons consisting of the rigid terphenyl units, separated laterally by the segregated regions of the hydrophilic groups, whereby the three different columnar mesophases should result from an anisotropic swelling of the polar regions on addition of solvents. Lipophilic solvents (dodecane) destabilize the columnar phases and replace them by smectic layer structures (SA phases).