Volumetric behavior of a bolaamphiphile in different amides-water and ethylene glycol-water mixtures

The effect of binary aqueous mixtures of ethylene glycol (EG), formamide (FA), N-methylformamide (NMF), dimethylformamide (DMF), and their pure phase on the apparent molar volume ϕV of the bolaamphiphile decamethonium bromide (C10Me6) has been investigated at 298.15 K. The behavior of standard molar volumes V20 and transfer volumes ΔtϕV of C10Me6 from water to solvent/water (S/W) binary mixtures, shows different minima and maxima depending on the composition of the solvent. This behavior is influenced by the nature of the cosolvent and on the type of the solute and more or less corresponds to volumetric changes in the S/W mixture. The investigation of the transfer volumes in different fixed concentrations reveals an inversion of ΔtϕV values between the compositions, which suggests a differentiation of the effects of different volume contributions on the partial molar volume of ions. The correlation of ΔtϕV with the dielectric constant of the aqueous amide mixtures shows that the behavior of ΔtϕV vs xamide reflects the changes of ɛE vs xamide.