The association of Triton X surfactants with beta-cyclodextrin. An isothermal titration calorimetry study

The association with beta-cyclodextrin of a series of Triton X surfactants with different ethylene oxide (EO) chain lengths was studied by isothermal titration calorimetry at 298.15 K. The results agree with a 1:1 association model. Association constants and changes in Gibbs free energies, enthalpie s and entropies were derived for the association process. Association of th ese surfactants with beta-cyclodextrin have favorable enthalpy changes and unfavorable entropy changes. The shorter the EO chain of the surfactant, th e greater the association constant with beta-cyclodextrin.