Unusual Volumetric and hydration behavior of the catanionic system undecenoate-dodecyltrimethylammonium bromide.

MARÍA BELÉN SIERRA; MARCELA MORINI; PABLO SCHULZ; MARÍA LUJÁN FERREIRA

COLLOID AND POLYMER SCIENCE

Año: 2005 vol. 283 p. 1016 - 1024

0303-402X

Following the studies on the effect of double bonds in the surfactant hydrophobic tail on the formation of mixed surfactant aggregates, we studied the viscosity and density of the system Sodium 10-Undecenoate (SUD)-Decyltrimethylammonium Bromide (DTAB)-water.We found that the partial molar volume and intrinsic viscosity of both, micellised and non-micellisedmixtures, are non-ideal, depending on the mixture composition and related to structural changes in micelles. These phenomena are caused by the presence of the double bond at the distal extreme of the SUD molecule, which has some affinity with water by formation of hydrogen bonds. In particular, as far as we know, this is the first report of non-ideal behavior of the partial molar volume in mixed micelles.