Isothermal titration calorimetry as a tool to determine the thermodynamics of demicellization processes

Rev Sci Instrum. 2012 Oct;83(10):105104. doi: 10.1063/1.4754718.

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.

MeSH terms

  • Calorimetry / instrumentation*
  • Calorimetry / methods*
  • Equipment Design
  • Equipment Failure Analysis
  • Micelles*
  • Phase Transition
  • Sodium Dodecyl Sulfate / chemistry*
  • Temperature
  • Thermodynamics
  • Titrimetry / instrumentation*

Substances

  • Micelles
  • Sodium Dodecyl Sulfate