title: Isothermal titration calorimetry as a tool to determine the thermodynamics of demicellization processes.
abstract: Demicellization  of a 90 mM sodium dodecyl sulfate (SDS) solution in water at 10, 22, and 30 °C was studied by isothermal titration calorimetry (ITC). ΔH of the demicellization process was strongly temperature dependent, having an exothermic progression (-20.4 ± 0.9 kJ∕mol, max) at 10 °C and an endothermic one (3.7 ± 1.2 kJ∕mol, max) at 30 °C. ΔH for micelle dilution followed a slightly endothermic progression (0.9 ± 0.5 kJ∕mol at 30 °C, 0.7 ± 1.3 kJ∕mol at 22 °C, and 0.0 ± 0.5 kJ∕mol at 10 °C) at all studied temperatures. No differences in ΔH for micelle dilution and demicellization was observed at 22 °C. The temperature dependence of ΔH measured by ITC could be related to hydrophobic interactions. Therefore, ITC was shown to be a useful tool to describe the thermodynamics of demicellization processes and in addition to determine alterations in ΔH caused by changes in hydrophobic and steric∕electrostatic interactions.
authors.affiliation: Department of Food Physics and Meat Science, Institute of Food Science and Biotechnology, University of Hohenheim, Garbenstr. 25, 70599 Stuttgart, Germany.
authors.forename: Anne
authors.initials: A
authors.lastname: Kessler
authors.forename: Benjamin
authors.initials: B
authors.lastname: Zeeb
authors.forename: Bertolt
authors.initials: B
authors.lastname: Kranz
authors.forename: Orquídea
authors.initials: O
authors.lastname: Menéndez-Aguirre
authors.forename: Lutz
authors.initials: L
authors.lastname: Fischer
authors.forename: Jörg
authors.initials: J
authors.lastname: Hinrichs
authors.forename: Jochen
authors.initials: J
authors.lastname: Weiss
mesh_terms: D002151:Calorimetry / Q000295:instrumentation* / Q000379:methods*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008823:Micelles; D044367:Phase Transition; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry*; D013696:Temperature; D013816:Thermodynamics; D017186:Titrimetry / Q000295:instrumentation*
chemical_list: D008823:Micelles; D012967:Sodium Dodecyl Sulfate