Dielectric properties and the structure of solutions of 2,2-dimethyl-1,3-propanediol in dioxane

The static permittivity epsilon (s) of solutions of 2,2-dimethyl-1,3-propan ediol (DMPD) in dioxane over the temperature range 293-363 K at concentrati ons x from 0.0203 to 0.2917 mol fractions and a Frequency of 1 MHz is shown . It was demonstrated that, at x = 0.0203-0.0966, the permittivity epsilon (s) is adequately described by models of solutions composed of dioxane and DMPD monomers or dioxane monomers and I : 2 DMPD-dioxane complexes. At x = 0.1877 and 0.2917, DMPD clusters are formed. At x = 0.333 and 303 K, the Di ssado-Hill model predicted that the average dipole moment of the DMPD clust ers in DMPD-containing solution (<(<mu>)over bar>(c) = 8.07 D) is smaller t han in the plastic phase of DMPD (<(<mu>)over bar>(c) = 21.72 D). In liquid DMPD, the decomposition of DMPD clusters caused by the temperature increas e from 408 to 423 K is accompanied by a decrease in <(<mu>)over bar>(c) fro m 10.3 to 9.03 D. The activation energy U-DHth(#) for the rearrangement of the structure of clusters in liquid DMPD (40.4 kJ/mol) and in the supercool ed plastic phase (43.0 kJ/mol) is determined by the formation and dissociat ion of two intermolecular H-bonds.