Dielectric properties and molecular interactions of 2-isopropoxyethanol and dimethyl sulfoxide (DMSO) binary mixtures using TDR

Dielectric measurements were performed on binary mixtures of 2- isopropoxyethanol (IPE) and Dimethyl Sulfoxide (DMSO) at various concentrations, and temperatures. The measurements were performed over a frequency range of 10 MHz to 30 GHz using Time Domain Reflectometry (TDR). The complex permittivity spectra were fitted using the Havriliak – Negami equation. The results show that the dielectric constant decreases with an increase in 2-isopropoxyethanol (IPE) concentration, reflecting a reduced ability of the system to store electrical energy. Conversely, relaxation time increases, indicating slower molecular dynamics. Positive (ε0E) values suggest enhanced dipolar interactions across all concentrations, with the highest contribution observed in the composition range of VDMSO = 0.4–0.6. The negative (1/τ)E values indicate slowed dipolar relaxation, further confirming strong solute-solvent interactions. The activation enthalpy (∆H) is highest for pure DMSO and decreases at VIPE = 0.4, indicating composition-dependent structural changes.