Study of a Phase Transition in a Lyotropic Liquid Crystal of Potassium Laurate/KCI/ Water by X-ray Diffraction and Optical Microscopy

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Abstract
Type I lyomesophase of potassium laurate was studied by X-ray diffraction and optical microscopy techniques with temperature variation. For increasing temperatures from 22°C to about 54°C only a nematic phase (N) was observed. For temperatures between 60°C and 74°C it was observed coexistence of an isotropic (I) and hexagonal (H α) phase with lattice parameter (47 ± 1) Å. For temperatures between 54°C and 60°C, in some experiments, it was observed the coexistence of phases N and H α. A binary system of potassium laurate/water (H α phase) was also studied by both techniques at room temperature; the lattice parameter is (44.9 ± 0.5) Å. Possible models for the N phase are discussed and compared with the obtained lattice parameters and associated micellar radius.