Aggregate structures of asymmetric di-alkylphosphate anions in concentrated aqueous solutions and the role of the short chain: X-ray diffraction and Raman scattering studies

Abstract

The microstructures of concentrated aqueous solutions of n-butyl(n-dodecyl)phosphate (BDoP) and n-hexyl(n-dodecyl)phosphate (HDoP) anions, as asymmetric double-chain surfactants, were studied using X-ray diffraction and Raman scattering techniques. The results indicated a marked difference in the aggregate behavior between BDoP and HDoP, attributed to the difference in the extent of the steric effect of the two short chains. The Raman scattering spectra provided direct evidence of the steric effect. This marked difference in the steric effect is clearly reflected in the phase structures of the BDoP and HDoP water binary systems. © 2013 Springer-Verlag Berlin Heidelberg.