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  • 1 Université des Sciences et Techniques du Languedoc Lammi, U.R.A. 79 pl. E. Bataillon 34095 Montpellier Cedex 05 France
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The importance of calorimetric methods in studies of colloidal phenomena is illustrated by the analysis of the experimental enthalpies of dilution and adsorption for aqueous solutions of three zwitterionic surfactants: 1–12 betaine, 3–12 betaine, and 3–12 sulfobetaine. The batch microcalorimeter ‘Montcal 3’, used to obtain these data, is described. The molar enthalpies of micellization and the differential molar enthalpies of adsorption onto silica gel are shown to be functions of the headgroup hydrophilicity, fixed by the type of negatively charged center and the number of methylene groups separating the charged sites.