On the Self-Assembly of Monoolein in Mixtures of Water and a Polar Aprotic Solvent

Abstract

Four different one-phase regions: two liquid phases (L and L3) and two liquid crystalline phases (Lα and V2) of the MO/NMP/water system, were studied by SAXS, PGSE-NMR, and rheology at 20 °C. The location of the dramatic increase in solubility of MO, in binary NMP/water mixtures, can be explained in terms of the presence or absence of free water, as a consequence of strong NMP(water)2 complex formation in the binary NMP/water system. A direct effect of this complexation is aggregate formation at a certain region within the L phase. The microstructure of the L3 phase can be modeled as bicontinuous according to the theory of interconnected rods when formation of NMP(water)2 complexes are taken into consideration. The swelling of the sponge phase correlates well to predicted swelling laws and characteristic lengths, as found in other sponge phases. The cubic phase region of the ternary system consists of at least two different cubic phases, with and symmetry of the space group, respectively. At higher NMP contents it seems as if the symmetry of the space group transforms into .