Understanding the Thermodynamics of Hydrogen Bonding in Alcohol-Containing Mixtures: Self Association

The perturbed chain form of the polar statistical associating fluid theory (Polar PC-SAFT) was used to model lower 1-alcohol + n-alkane mixtures. The ability of the equation of state to predict accurate activity coefficients at infinite dilution was demonstrated as a function of temperature. Investigations show that the association term in SAFT plays an important role in capturing the right composition dependence of the activity coefficients in comparison with nonassociating models (UNIQUAC). Results also show that considering long-range polar interactions can significantly improve the fractions of free monomers predicted by PC-SAFT in comparison with spectroscopic data and molecular dynamic (MD) simulations carried out in this work. Furthermore, evidence of hydrogen-bonding cooperativity in 1-alcohol + n-alkane systems is discussed using spectroscopy, simulation, and theory. In general, results demonstrate the theory's predictive power, limitations of first-order perturbation theories, as well as the importance of considering long-range polar interactions for better hydrogen-bonding thermodynamics.