LIQUID-CRYSTALS OF LONG-CHAIN DIALKYL PHOSPHATE SALTS IN NONPOLAR-SOLVENTS

The structure of a binary system of aluminum salts of dihexadecyl phosphate (C16DP{single bond}Al) andn-hexadecane were studied in the high C16DP{single bond}Al content region. Above the melting point of the hydrocarbon chain of C16DP{single bond}Al (Tc), the experimental results of X-ray diffraction studies for the C16DP{single bond}Al solution show that cylinder structures-composed of an aggregation with a center of aluminum atoms of C16DP{single bond}Al molecules whose architecture consists of a trisubstituted central aluminum atom and three regional C16DP molecules-are stacked periodically to form a hexagonal liquid crystal. The Bragg spacingd between the (1010) planes in the hexagonal network increased with increasing concentration ofn-hexadecane, which should fill the C16DP{single bond}Al acyl chain region and the space between the tails of C16DP{single bond}Al cylinders. Below Tc this system exists as a single hard wax-like phase. The packing structure of C16DP{single bond}Al in this phase is similar to the hexagonal structure of the liquid crystal phase and in the region up to 23 wt%n-hexadecane content this packing order changes with the addition ofn-hexadecane. The effects or varying amounts ofn-hexadecane on the packing states of C16DP{single bond}Al are discussed. © 1991 Academic Press, Inc. All rights reserved.