Effects of Temperature on the Thermodynamic and Dynamical Properties of Glycerol-Water Mixtures: A Computer Simulation Study of Three Different Force Fields

FO Akinkunmi and DA Jahn and N Giovambattista, JOURNAL OF PHYSICAL CHEMISTRY B, 119, 6250-6261 (2015).

DOI: 10.1021/acs.jpcb.5b00439

Glycerol water solutions are relevant in technological and scientific applications, such as in the preservation of biomolecules and tissues at low temperatures. We perform molecular dynamics Simulations of glycerol- water mixtures with glycerol molar fractions of chi(g) = 0-100% at P = 0.1 MPa and T = 210-460 K. We focus On the effects of temperature and concentration on the thermodynamic (density rho, thermal expansion coefficient alpha(p), isobaric specific heat c(p), compressibility K-T) and dynamical (glycerol and water diffusion coefficients, D-g and D-w) properties of the mixtures. In particular, we test the sensitivity of computer simulation results to the glycerol force field and water model (TIP3P and TIP4P/2005) employed. All mixture models underestimate rho at high T and tend to overestimate rho at low T-j only the mixture model based on TIP4P/2005 water exhibits a density maximum at low chi(g), as expected. All models overestimate alpha(p), c(p), and K-T; they are able to reproduce qualitatively the T dependence of alpha(p) and K-T but fail in the case of c(p). In all cases, D-g and D-w follow the Vogel Tamman Fulcher equation and decouple at low T, with D-w/D-g increasing upon cooling. Overall, the mixture based on TIP4P/2005 water provides better thermodynamic and dynamical properties than the mixtures based on TIP3P water, even chi(g) = 20%.

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