PARABOLIC FOCAL CONICS AND POLYGONAL TEXTURES IN LIPID LIQUID-CRYSTALS

Polygonal defect arrays in lipid liquid crystals prepared from dipalmitoyl-, dimyristoyl-, and dilauryl-phosphatidylcholine with various concentrations of water have been observed and characterized using optical microscopy. These arrays appear similar to the polygonal arrays previously observed in thermotropic smectic and cholesteric liquid crystals. The parabolic focal conic model proposed by Rosenblatt, Pindak, Clark and Meyer for the polygonal arrays in thermotropic smectic liquid crystals also describes the observed properties in the smectic A phase of lipid liquid crystals. The polygonal arrays become progressively more birefringent as the strains inducing them are increased. The parabolic focal conic model does not completely describe the details of the more birefringent polygonal arrays. 35 refs.