Measurement of the interaction enthalpy for mixed micelles of dodecyltrimethylammonium bromide and 1-dodecyl-3-methylimidazolium bromide

In order to clarify the nature of the inter-micellar interactions, we developed an approach to obtain the intermicellar interaction enthalpy through measuring the mixing heats of dodecyltrimethylammonium bromide (DTAB)/1-dodecyl-3-methylimidazolium bromide (C 12 mimBr) mixed micelles by using flow-mixing calorimetry . It was found that the inter-micellar interaction enthalpies for this system were negative, representing the attractive enthalpy interactions between the mixed micelle droplets. These results are contradictory to those reported in the literature and interpreted by the predominant attractive dehydration effect of counterion. Static light scattering experiment revealed that the repulsive nature of the interaction characterized by the Gibss free energy should be dominated by the entropy interaction.