Comparative Dielectric Behavior of PEGs with Varying Molecular Weights (200–600) in DMSO via Time-Domain Reflectometry

This study investigates the dielectric behavior and complex permittivity of poly(ethylene glycol) (PEG) with molecular weights of 200, 300, 400, and 600 g mol-1 in binary mixtures with dimethyl sulfoxide (DMSO) using time-domain reflectometry (TDR) in the frequency range of 10 MHz to 30 GHz. The static dielectric constant (ε₀) and relaxation time (τ) were evaluated to understand the impact of PEG chain length on solvation dynamics. The Cole-Davidson model was employed to fit the measured dielectric spectra. The excess static dielectric constant (ε₀)E and inverse excess relaxation time (1/τ)E were analyzed to assess deviations from ideal mixing behavior and cooperative dipole interactions in the system. The results indicate that increasing PEG molecular weight leads to systematic variations in dielectric properties, attributed to differences in hydrogen bonding and segmental mobility. The findings provide insights into the solvation behavior of PEG in DMSO, with implications for solvent design in biophysical and industrial applications.