scholarly journals Activity modelling of the solid–liquid equilibrium of deep eutectic solvents

2019 ◽  
Vol 91 (8) ◽  
pp. 1341-1349 ◽  
Author(s):  
Laura J.B.M. Kollau ◽  
Mark Vis ◽  
Adriaan van den Bruinhorst ◽  
Gijsbertus de With ◽  
Remco Tuinier
Keyword(s):  
Melting Point ◽  
Binary Mixtures ◽  
Order Term ◽  
Deep Eutectic Solvents ◽  
Melting Point Depression ◽  
Ideal Behavior ◽  
Liquid Phase Boundary ◽  
Melting Temperatures ◽  
Sustainable Solvents ◽  
Solid Liquid

Abstract Compared to conventional solvents used in the chemical industry, deep eutectic solvents (DESs) are considered as promising potentially sustainable solvents. DESs are binary mixtures and the resulting liquid mixture is characterized by a large melting point depression with respect to the melting temperatures of its constituents. The relative melting point depression becomes larger as the two components have stronger attractive interactions, resulting in non-ideal behavior. The compositional range over which such binary mixtures are liquids is set by the location of the solid–liquid phase boundary. Here we present experimental phase diagrams of various recent and new DESs that vary in the degree of non-ideality. We investigate whether thermodynamic models are able to describe the solid–liquid equilibria and focus on relating the parameters of these models to the non-ideal behavior, including asymmetric behavior of the activity coefficients. It is shown that the orthogonal Redlich–Kister-like polynomial (OP) expansion, including an additional first order term, provides an accurate description. This theory can be considered as an extension of regular solution theory and enables physical interpretation of the fit parameters.

Phase Diagrams of Binary Mixtures of Phenylenediamines and Dihydroxybenzenes

1977 ◽  
Vol 32 (1) ◽  
pp. 98-100
Author(s):  
M. S. Dhillon
Keyword(s):  
Phase Diagrams ◽  
Binary Mixtures ◽  
Melting Temperatures ◽  
Solid Liquid

Abstract Solid - liquid equilibria for o-phenylenediamine + resorcinol, m-phenylenediamine + pyrocatechol, + resorcinol and p-phenylenediamine + pyrocatechol, + resorcinol have been studied by the thaw-melt method. The types and melting temperatures of the complexes formed in theses mixtures were ascertained from the phase diagrams.

Determining solid/liquid interfacial energies in Al-Cu by curvature controlled melting point depression

2018 ◽  
Vol 147 ◽  
pp. 113-121 ◽  
Author(s):  
S. Lippmann ◽  
C. Simon ◽  
S. Zechel ◽  
M. Seyring ◽  
U.S. Schubert ◽  
...  
Keyword(s):  
Melting Point ◽  
Melting Point Depression ◽  
Interfacial Energies ◽  
Solid Liquid

scholarly journals The Role of Charge Transfer in the Formation of Type I Deep Eutectic Solvent-Analogous Ionic Liquid Mixtures

Molecules ◽  
2019 ◽  
Vol 24 (20) ◽  
pp. 3687 ◽  
Author(s):  
Dinis O. Abranches ◽  
Nicolas Schaeffer ◽  
Liliana P. Silva ◽  
Mónia A. R. Martins ◽  
Simão P. Pinho ◽  
...  
Keyword(s):  
Ionic Liquid ◽  
Deep Eutectic Solvent ◽  
Deep Eutectic Solvents ◽  
Liquid Mixtures ◽  
Chloride Ions ◽  
Melting Point Depression ◽  
Type I ◽  
Chloride Complexes ◽  
Charge Delocalization ◽  
Solid Liquid

It was recently shown that tetramethylammonium chloride presented negative deviations to ideality when mixed with tetraethylammonium chloride or tetrapropylammonium chloride, leading to a strong decrease of the melting points of these salt mixtures, in a behavior akin to that observed in the formation of deep eutectic solvents. To better rationalize this unexpected melting point depression between two structurally similar compounds devoid of dominant hydrogen bonding capability, new solid–liquid equilibria data for tetramethylammonium-based systems were measured and analyzed in this work. Molecular dynamics was used to show that the strong negative deviations from ideality presented by these systems arise from a synergetic share of the chloride ions. A transfer of chloride ions seems to occur from the bigger cation in the mixture (which possesses a more disperse charge) to the smaller cation (tetramethylammonium), resembling the formation of metal–chloride complexes in type I deep eutectic solvents. This rearrangement of the charged species leads to an energetic stabilization of both components in the mixture, inducing the negative deviations to the ideality observed. The conclusions presented herein emphasize the often-neglected contribution of charge delocalization in deep eutectic solvents formation and its applicability toward the design of new ionic liquid mixtures.

Thermal Crystallization of Polytetrahydrofuran Networks

1991 ◽  
Vol 64 (1) ◽  
pp. 74-82 ◽  
Author(s):  
C. Michael Roland ◽  
Gary S. Buckley
Keyword(s):  
Melting Point ◽  
Crystallization Behavior ◽  
Degree Of Crystallinity ◽  
Melting Point Depression ◽  
Network Architectures ◽  
Experimental Conditions ◽  
Thermal Crystallization ◽  
Melting Temperatures ◽  
Equilibrium Melting Point ◽  
The Degree Of Crystallinity

Abstract The formation of a network in PTHF inhibits the crystallization of chain units in proximity to the crosslinks. From melting-point-depression measurements, it is estimated that the suppression in crystallizability extends to as much as 8 chain units away from a network junction. This estimate is consistent with the degree of crystallinity measured in various crosslinked PTHF rubbers. The equilibrium melting point for linear PTHF was determined to be 361°K. Although this is significantly higher than previously reported values, the present result is congruent with the melting temperatures measured for crosslinked PTHF, and its use leads to satisfactory predictions of their melting-point depression. The distribution in the lengths of network chains exerted a trivial influence on thermal crystallization behavior. Although this distribution must in principle influence crystallization behavior in so far as it governs crystallizable sequence lengths, differences between uni- and bi-modal network architectures were moderate under the present experimental conditions.

Melting and Crystallization of Poly(oxyethylene) Mixtures

1995 ◽  
Vol 60 (11) ◽  
pp. 1855-1868 ◽  
Author(s):  
Ivo Lapeš ◽  
Josef Baldrian ◽  
Ján Biroš ◽  
Julius Pouchlý ◽  
Hanes Mio
Keyword(s):  
Melting Point ◽  
Lamellar Structure ◽  
Composition Dependence ◽  
Eutectic Phase ◽  
Eutectic Melting ◽  
Pure Polymer ◽  
X Ray ◽  
Long Period ◽  
Solid Liquid ◽  
Melting And Crystallization

Solid-liquid eutectic phase diagrams of mixtures of poly(oxyethylene) (M.w. 2 000) with hydroxy and methoxy endgroups, crystallizing in extended-chain macroconformation only, with glutaric acid, benzoic acid or 1,2-diphenylethane are given. The composition dependence of the melting temperature can be fitted by the Flory-Huggins equation. Interaction parameters X and interaction energy densities B evaluated from the diluent branch of the phase diagram are consistent with those obtained from the polymer branch provided the calorimetric value of enthalpy of polymer fusion is used in the latter computation. Measurements of small- and wide-angle X-ray scatterings showed a stacked lamellar structure of POE. Below the eutectic melting point, the long period of the polymer is almost independent of the diluent concentration. On raising temperature gradually from this melting point to the melting point of pure polymer, the increasing long period indicates the penetration of the diluent between the lamellae. As follows from SAXS measurements, the crystallinity of poly(oxyethylene) in the mixtures remains unchanged compared to that of the pure polymer.

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