Dipolar Self-Assembling in Mixtures of Propylene Carbonate and Dimethyl Sulfoxide as Revealed by the Orientational Entropy

Abstract

This article presents the results of static dielectric studies performed on mixtures of two strongly polar liquids important from a technological point of view: propylene carbonate (PC) and dimethyl sulfoxide (DMSO). The dielectric data were analyzed in terms of the molar orientational entropy increment induced by the probing electric field. It was found that the two polar liquids in the neat state reveal quite different molecular organization in terms of dipole-dipole self-assembling: PC exhibits a dipolar coupling of the head-to-tail type, whereas in DMSO one observes extreme restriction of dipolar association in any form. In PC + DMSO mixtures, the disintegration of the dipolar ensembles of PC molecules takes place and the progress of that process is strictly proportional to the concentration of DMSO. The static permittivity of mixtures of such differently self-organized liquids exhibits a positive deviation from the additive rule and the deviation develops symmetrically within the concentration scale.

Comprehensive review on Froehlich entropy estimation: a technique to investigate the state of order in condensed matter

“…FE evaluation is exploited to describe the arrangement of structural liquids, both organic and inorganic, in suitable solvents. Studies are carried out on polar inorganic pure formamide [86], propylene carbonate and dimethylsulfoxide (DMSO) with their mixtures [87], highly-polar amide compounds such as n-methylpropionamidine, its homologue n-methylacetamide, and nethylacetamide [68], organic lactones [88], inorganic lithium perclorate in polyethylene glycols solvent [89]. On a different research line, a theoretical study of D.V.…”

“…Such experimental approach was also used to specifically highlight the variation of orientational features as a function of solvent concentration: this was carried out, as hinted above, with mixtures of propylene carbonate and DMSO, a compound of significant application interest [87]. The plot of Fig.…”