Formation of cubic-phase microemulsions in sucrose alkanoate systems

The self-organized structure is changed from hexagonal to lamellar liquid crystals by mixing sucrose lipophilic multi-dodecanoate (L-595) with hydrophilic sucrose monododecanoate (L-1695) in water. Although no cubic phases are found in water, a discontinuous cubic phase (I-1) with oil-swollen micelles or a cubic-phase microemulsion is produced upon addition of squalane, n-hexadecane, n-decane, n-octane and n-heptane at the weight ratio of L-1695/L-595 = 1/1. The small-angle X-ray scattering spectrum and the phase behavior show that the micelles are packed in a face-centered cubic array in the I-1 phase. The single cubic-phase region shifts to higher oil content with the decrease in the molecular size of oil and finally, no cubic phases are found with m-xylene and cyclohexane as oil. Furthermore, from the analysis of compositions of the I-1 phases, it is suggested that the shape of the micelles becomes non-spherical in the short-chain alkane systems. (C) 2001 Published by Elsevier Science B.V. All rights reserved.