Solubilization of Dye in Lamellar Liquid Crystal of System Igepal CO-610 and H₂O

ABSTRACT

The solubilization and spectrum characteristics of a dye mixture, Morefast Red 101, in the lamellar liquid crystal (LLC( of the system Igepal CO-610 and H₂O were studied by measurements of phase behavior, low angle X-ray diffraction, UV and visible spectrum. Pure dye molecules, NAHPA, were located in the hydrocarbon chain part of the LLC bilayer of the solvents for the formulated dye. Of the solvents, n-propanol was evenly distributed between all parts of the liquid crystal while the bis(2-ethylhexyl)amine was localized to the space between the mirroring terminal methyl groups of the layered structure. In this manner the influence of the different components was compensated and the net result of the added dye was no effect on the interlayer spacing of the lamellar liquid crystal. The UV spectrum of the dye showed an interesting feature. After addition of water to the solution of dye in the relatively nonpolar surfactant the change in the dye spectrum showed a less polar environment of the dye in spite of the increased polarity. The explanation is found in the ordered structure of the lamellar liquid crystal; addition of water caused a transfer of the dye from the polar part of the surfactant tot he non-polar hydrocarbon chains.

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Guo Rong*

permanent address: ChemistryDepartment, Teacher's College, Yangzhou University, Yangzhou, 225002, China