A variation on Luzzati's soap phases. Room temperature thermotropic liquid crystals

Abstract

Remarkable room-temperature liquid crystallinity is observed for a wide range of metal soaps. Incorporation of saturated, mid-chain mono-methyl branched C₁₇ fatty acid (mid-chain branched fatty acid) into metal soaps lowers the liquid crystalline transition to below room temperature. Soaps of Na, Mg, Al, Ca, Cu, Zn, Sr, Ag, Cd, La, Ce, Tb and Lu are synthesized and characterized via XRD, FTIR, DSC, optical microscopy, density determinations and other physical methods. The main room temperature mesophase identified in the soaps here is a liquid crystalline hexagonal columnar phase, first described by Luzzati et al. A comparative analysis of the branched soaps with their saturated, linear analogues is given. Implications for room temperature columnar soap structure is discussed in terms of the various physical parameters found for these soaps.