Abstract:Polyethers are promising compounds for the creation of electrochemical energy storage systems. The molecular dynamics method can facilitate the search of compounds that have the most potential. However, the application of this method requires verification of the force fields. We perform molecular dynamics calculations of the physical properties of the aqueous 1,4-dioxane solution (density, enthalpy of mixing, and viscosity) and compare them to the available experimental data. In addition, we confirm the idea t… Show more
“…The dependences E̅ P,2 = f ( x 2 ) (Figure b) show a sharp maximum at x 2 ≈ 0.04, the height of which decreases with increasing temperature. In addition, these dependences at all temperatures exhibit a small minimum at x 2 ≈ 0.3–0.4 and a small maximum at x 2 ≈ 0.7, which is more pronounced at a low temperature of 278.15 K. As can be seen from Figure , the positions of the extremes on the dependences E̅ P, i = f ( x 2 ) coincide with the description of the compositions at which there is a strong change in the structure of the water + 1,4-dioxane mixture. ,− ,, The dependencies demonstrated above show that the formation of water–dioxane clusters in the mixture − requires additional consideration of the manifestation of the hydrophobicity of 1,4-DO, the formation of more stable hydrogen bonds between water and 1,4-DO at a 1:2 ratio, and the presence of bulk water clusters in the mixture up to x 2 ≈ 0.7.…”
Section: Discussionsupporting
confidence: 56%
“…Previously, the properties of 1,4-DO solutions have been repeatedly studied by many experimental and theoretical methods, and thanks to these works, the structure and some properties related to the structure were determined. To study 1,4-DO aqueous mixtures, X-ray diffraction; 17−19 neutron diffraction; 17−19 NMR, 17,19,20 IR, 21 and Raman spectrosco-py; 22 MD simulations; 23 time-resolved fluorescence spectroscopy; 24 dielectric relaxation; 25 calorimetry; 26 viscometry; 27 and densimetry were used. 13,27−68 However, despite the availability of a large amount of literature data on the volumetric properties of the water + 1,4-DO mixture, there are still some contradictions.…”
The densities of the mixture {water (1) + 1,4-dioxane (2)} were measured using a vibration density meter at temperatures from 274.15 to 333.15 K and atmospheric pressure over the entire composition range. The excess molar volume of the mixture and the partial molar volumes of water and 1,4-dioxane were calculated. The temperature of the maximum density of 1,4-dioxane aqueous solutions was determined. It is shown that the formation of the mixture occurs with a decrease in volume. The dependences of partial molar volumes on the concentration of water and 1,4-dioxane have extremums. The values of molar volumes of water and 1,4-dioxane exceed the corresponding limit partial molar volumes. An increase in the temperature or concentration of 1,4-dioxane increases the magnitude of the molar expansion of the mixture over the entire range of compositions. Replacing the intrinsic environment of a molecule in a solvate shell with molecules of another component leads to a decrease in the partial molar volume at infinite dilution. The obtained results were compared with the literature data.
“…The dependences E̅ P,2 = f ( x 2 ) (Figure b) show a sharp maximum at x 2 ≈ 0.04, the height of which decreases with increasing temperature. In addition, these dependences at all temperatures exhibit a small minimum at x 2 ≈ 0.3–0.4 and a small maximum at x 2 ≈ 0.7, which is more pronounced at a low temperature of 278.15 K. As can be seen from Figure , the positions of the extremes on the dependences E̅ P, i = f ( x 2 ) coincide with the description of the compositions at which there is a strong change in the structure of the water + 1,4-dioxane mixture. ,− ,, The dependencies demonstrated above show that the formation of water–dioxane clusters in the mixture − requires additional consideration of the manifestation of the hydrophobicity of 1,4-DO, the formation of more stable hydrogen bonds between water and 1,4-DO at a 1:2 ratio, and the presence of bulk water clusters in the mixture up to x 2 ≈ 0.7.…”
Section: Discussionsupporting
confidence: 56%
“…Previously, the properties of 1,4-DO solutions have been repeatedly studied by many experimental and theoretical methods, and thanks to these works, the structure and some properties related to the structure were determined. To study 1,4-DO aqueous mixtures, X-ray diffraction; 17−19 neutron diffraction; 17−19 NMR, 17,19,20 IR, 21 and Raman spectrosco-py; 22 MD simulations; 23 time-resolved fluorescence spectroscopy; 24 dielectric relaxation; 25 calorimetry; 26 viscometry; 27 and densimetry were used. 13,27−68 However, despite the availability of a large amount of literature data on the volumetric properties of the water + 1,4-DO mixture, there are still some contradictions.…”
The densities of the mixture {water (1) + 1,4-dioxane (2)} were measured using a vibration density meter at temperatures from 274.15 to 333.15 K and atmospheric pressure over the entire composition range. The excess molar volume of the mixture and the partial molar volumes of water and 1,4-dioxane were calculated. The temperature of the maximum density of 1,4-dioxane aqueous solutions was determined. It is shown that the formation of the mixture occurs with a decrease in volume. The dependences of partial molar volumes on the concentration of water and 1,4-dioxane have extremums. The values of molar volumes of water and 1,4-dioxane exceed the corresponding limit partial molar volumes. An increase in the temperature or concentration of 1,4-dioxane increases the magnitude of the molar expansion of the mixture over the entire range of compositions. Replacing the intrinsic environment of a molecule in a solvate shell with molecules of another component leads to a decrease in the partial molar volume at infinite dilution. The obtained results were compared with the literature data.
“…The TIP4P class of water models provides a well balanced instrument that allows predictive modelling of water-based systems at reasonable computational expenses and, therefore, at relatively large length and time scales (see e.g. 26 – 29 ). Figure 1 The T-P diagram of amorphous and liquid water.…”
Unlike conventional first-order phase transitions, the kinetics of amorphous-amorphous transitions has been much less studied. The ultrasonic experiments on the transformations between low-density and high-density amorphous ice induced by pressure or heating provided the pressure and temperature dependencies of elastic moduli. In this article, we make an attempt to build a microscopic picture of these experimentally studied transformations using the molecular dynamics method with the TIP4P/Ice water model. We study carefully the dependence of the results of elastic constants calculations on the deformation rates. The system size effects are considered as well. The comparison with the experimental data enriches our understanding of the transitions observed. Our modeling gives new information about the formation mechanisms of new phase clusters during the transition between low-density and high-density amorphous ices. We analyse the applicability of the term “nucleation” for these processes.
“…As can be seen from Figure a, the depth of the minimum dependence V̅ 1 = f ( x 2 ) is lower in 1,3-dioxolane, and its position, like that in oxolane, is shifted to the region of higher x 2 values, compared with the 1,4-dioxane extremum position. As shown earlier, the formation of such extrema in the water + 1,4-dioxane mixture is associated with changes in the conformational state of the nonelectrolyte molecule, − final destruction of the water clusters in the mixture, and release of H 2 O molecules from its cavities. − …”
The
densities of the binary mixture {water (1) + 1,3-dioxolane
(2)} were measured using a vibration density meter over the entire
range of compositions in the temperature range from (274.15 to 333.15)
K at atmospheric pressure. The excess molar volumes, molar isobaric
temperature expansions of the mixture, and apparent and partial molar
volumes of water and 1,3-dioxolane, including their limiting values,
were calculated. The obtained results were compared with the literature
data and with those having similar properties of aqueous mixtures
of other simple cyclic ethers: oxolane and 1,4-dioxane. The formation
of the water + 1,3-dioxolane mixture was shown to be accompanied by
a volume decrease at all temperatures. The addition of ether to water
led to a negative shift in the temperature corresponding to the maximum
mixture density. The concentration dependencies of the partial molar
volumes of 1,3-dioxolane were characterized by the absence of a minimum
at low concentrations of cyclic ether in the mixture. The limiting
partial molar volumes of water and 1,3-dioxolane were smaller than
the respective molar volumes and increased as the temperature increased.
The temperature coefficient of the limiting molar isobaric expansion
of water in 1,3-dioxolane was positive, which indicated that the temperature
increase made the solvate shell larger. The negative temperature coefficient
of the limiting molar isobaric expansion of 1,3-dioxolane indicates
the destruction of the water structure in the immediate environment
of the cyclic ether molecule.
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