Influence of alkyl chain length on molecular interactions in binary mixtures of diethylene glycols of monoalkyl ethers and ethanol

The glycol ether derivatives like monoalkyl ethers of diethylene glycol have wide applications as industrial solvents, surfactants and detergents. Study of their interactions with other solvents like ethanol have good potential for improving their applicability. Hence an attempt has been made to evaluate the hydrogen bonding interactions among mono-methyl, mono-ethyl and mono-butyl ethers of diethylene glycols and ethanol with dielectric (both time domain and frequency domain), volumetric and FTIR spectroscopic approaches. The dielectric parameters like static dielectric permittivity (ε s ), dielectric relaxation time (τ), excess parameters like excess static dielectric permittivity (ε s E ), excess dielectric permittivity at high frequency (ε ∞ E ) and excess molar volume (V E ) revealed the existence of intermolecular interactions among the constituent molecules, and fascinatingly, they are influenced by the length of the alkyl chain. The Bruggeman factor (f B ) suggested the existence of heteromolecular interactions which increases with increase in hydrocarbon chain length of the molecules. The participation of various atoms/groups of a constituent molecule in hydrogen bonding has been confirmed with the help of FTIR spectroscopy. Moreover, it revealed non-classical hydrogen bonding. • The non-linear variations in the dielectric parameters suggests the existence of intermolecular hydrogen bonding. • The longer chain polar molecules prefer low frequency relaxation phenomenon with minimal energy loss. • Classical and non-classical hydrogen bonding exists between diethylene glycol mono-alkyl ethers and ethanol. • The Bruggeman interaction parameter depends on number of methylene groups in molecular chain. • The molecular chain length influences ion mobility within liquid binary mixtures.