Densities, refractive indices and excess properties of binary mixtures of dimethylsulphoxide with some poly(ethylene glycol)s at different temperatures

Abstract

The densities, ρ and refractive indices, nD of binary mixtures of dimethylsulphoxide (DMSO) with poly(ethylene glycol) 200 (PEG200), poly(ethylene glycol) 300 (PEG300) and poly(ethylene glycol) 400 (PEG400) over the entire composition range were measured at temperatures (298.15, 303.15, 308.15, and 313.15K) and at atmospheric pressure. From the experimental data, the excess molar volumes, VmE and excess refractive indices, nDE were calculated. The partial molar volumes, V¯m,1°∞ and V¯m,2°∞ of the components at infinite dilution and excess partial molar volumes, V¯m,1°E,∞ and V¯m,2°E,∞ of the components at infinite dilution have been calculated. The VmE values were negative and nDE were positive for all the three systems at each investigated temperatures. The results indicate the presence of specific interactions between DMSO and PEG molecules. The negative deviations in VmE values follow the order: PEG200<PEG300<PEG400. It is observed that VmE and nDE values depend upon the chain length of PEG molecules. Further, the refractive indices of these binary mixtures were calculated theoretically from the refractive index data of pure components and densities of the mixtures by using various empirical and semi-empirical relations and the results were compared with the experimental findings.