Viscosity B-Coefficients, Apparent Molar Volumes, and Activity Coefficients for α- and γ-Cyclodextrins in Aqueous Solutions

The viscosities and densities at 15, 25, and 35 °C, and activity coefficients at 25 °C for the aqueous solutions of α- and γ-cyclodextrins were measured, and the results were interpreted in terms of solute-solvent and solute-solute interactions. The concentration and temperature dependences of viscosities and apparent molar volumes are almost similar to those of linear saccharides, i.e. maltose and maltotriose, indicating that α- and γ-cyclodextrins are structure forming solutes. However, the concentration dependences of activity coefficients of cyclodextrins are significantly different from those of maltose and maltotriose. The results were tentatively assigned to the formation of dimer in aqueous solutions.