Micellar structure of gemini cationic surfactants: influence of the spacer length

The enthalpies of micellisation of gemini and conventional cationic surfactants have been determined using calorimetric measurements as a function of temperature. The differential molar enthalpies of micellisation depend on the structure of the surfactants as well as on the temperature. As expected, a drastic increase of the enthalpies of micellisation are observed with an increase of the temperature. Moreover, calorimetric investigation of self-association process shows that the enthalpies of micellisation are much more exothermic for the gemini surfactants than for the conventional cationic surfactant. The higher values of the micellisation enthalpies are due to a higher micellar density of gemini surfactant micelles.