Structure of vesicles in homogeneous short-chain polyoxyethylene cholesterol ether systems

Mixtures of the homogeneous nonionic surfactant trioxyethylene cholesterol ether, ChEO(3) and water were examined by microscopy, small-angle X-ray sca ttering, differential scanning calorimetry, electron-spin resonance and flu orescence spectrometry. A lamellar liquid-crystalline phase with peculiar c haracteristics is found above 75% of surfactant concentration. This phase s eems to consist of a rather rigid and ordered bilayer when compared with ty pical L-alpha-phases although the degree of crystallinity is less than that of Lp-phases in nonionic systems with the same EO chain. The peculiarities of this phase are attributed to the rigid and bulky hydrophobic group of s urfactant. The dispersion of this lamellar phase in water leads to the form ation of very stable vesicles with a wide range of morphologies at rather l ow surfactant concentrations. (C) 2001 Elsevier Science B.V. All rights res erved.