Abstract:

The association of a series of anionic surfactants (C n H 2 n +1 SO 3Na, n =5,8,10,12,14) with β-cyclodextrin was studied by means of the isothermal titration calorimeter(ITC) at 298.15 K. For these type of inclusion complexes, the results agreed well with a 1:1 association model. Apparent values for the association constants, and changes in the standard molar Gibbs energies, enthalpies, entropies ,were derived for the association process. The results indicated that the association of surfactants with β-cyclodextrin are favorable by both enthalpy and entropy changes. The results also indicated that -Δ GΘincrease steadily with an increasing of alkyl chain length of the surfactants. The results also demonstrated that the longer chain tail of surfactant, the greater the association constant with β-cyclodextrin .

Key words: β--cyclodextrin, Anionic surfactants, Inclusion complexes, Isothermal titration calorimeler, Thermodynamic parameters