Self-Assembly in SomeN-Lauroyl-l-glutamate/Water Systems

Abstract

Acylglutamate is a divalent anionic surfactant whose properties are affected by its degree of neutralization. In this study, we present phase maps for aqueous systems of the potassium (LGP) and triethanolamine salts (LGT) of N-lauroyl l-glutamic acid, at different degrees of neutralization. A cubic phase forming between the isotropic micellar and the hexagonal phase was detected in both LGP/water and LGT/water systems. The stability of this cubic phase was promoted by increasing the degree of neutralization. The lattice parameters of the phase were determined by small-angle X-ray scattering (SAXS). SAXS spectra from samples of this cubic phase could be indexed to the crystallographic space group Pm3n. 1H NMR self-diffusion measurements have also been performed in the isotropic micellar and cubic regions. The self-diffusion coefficient of the surfactant decreases with increasing its concentration. In the cubic phase, the self-diffusion is of the order of 10-13 m2 s-1, demonstrating that the cubic phase consists of discrete micelles.