engleski

Lamellar-inverse hexagonal transition of 4-(1-butyloctyl)benzenesulphonate in electrolyte/water/octanol solvents: a fractal approach to the homogeneous nucleation of the liquid crystalline phase from the solution

The behavior of mesophases in the sodium 4-(1-butyloctyl)benzenesulphonate/Mg(NO3)2/water system was determined by using crossed polars, polarized light microscopy, and small-angle X-ray diffraction. In comparison with the binary system without Mg(NO3)2, these systems showed changes in the formation of phases. A considerable shift of the two-phase region (isotropic/lamellar) towards a lower concentration of surfactant has been found. In water/n-octanol mixtures the lamellar phase was formed bellow 10% of cosurfactant (n-octanol). Above 30% of a cosurfactant, the transition of lamellar-inverse hexagonal phase has been observed due to the corresponding convex/concave change of the bilayer curvature. The formation of the inverse hexagonal phase was caused by an increase in the cosurfactant concentration. By heating the sample above 55°C the solution became isotropic ; following cooling the homogeneous nucleation of an inverse hexagonal phase from the isotropic solution was observed. The fractal approach was applied to characterize the dendrite-like growth of the inverse hexagonal phase using the "box-counting" method. The fractal dimensions for the diffusion-limited aggregation resulting in the growth of the starlike, as well as the rod-like, dendrites were found to be Dstar~1.36-1.4 (time dependent) and Drod=1.25 (time independent), respectively.

Fractal; homogeneous nucleation; Lamellar-Hexagonal Transition

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