Influence of structural modifications near the polar head of sodium carboxylates on their aqueous solution behaviour

The preparation of sodium carboxylate salts containing one or two unsaturat ions next to the polar head is reported. The effect of unsaturations and of the Z and E isomerism on their aqueous solution properties were studied as a function of temperature, using cryometry at 0 degrees C, conductimetry a t 25 degrees C and vapour pressure osmometry at 40 degrees C. The critical micelle concentrations are determined and are compared with those of their homologous saturated compounds. The free energy of micellization per double bond is determined (-3.12 kJ mol(-1)) and is less negative than the free e nergy of micellization per single bond (-5.2 kJ mol(-1) ). (C) 1999 Elsevie r Science B.V. All rights reserved.