Theory of Fluids, Phase Transitions, and Interfaces

Cornell University, Ithaca NY

Investigators

Abstract

Ben Widom of Cornell University is supported by the Theoretical and Computational Chemistry Program to continue his research on fluids, phase transitions, and interfaces. He will employ statistical mechanical methods to study the properties of liquids and liquid mixtures, the phase transitions that such fluids undergo, and the thermodynamics and structural transformations of the interfaces between fluid phases. Five research topics will be explored: 1) modeling of interfacial tensions of binary phase-separated liquid mixtures; 2) an extension of a one-dimensional model for hydrophobic interaction to higher dimensions and more water-like solvent; 3) a theoretical treatment of a recent unexpected experimental observation regarding the two-stage wetting transition for the temperature dependence of hydrocarbon spreading on water; 4) a study to determine the effect of the presence of surfactants on the fluctuations in the structure of interfaces; 5) a collaborative study with researchers from the Netherlands to analyze experimental results on mixed colloids and polymers. Both in the laboratory and in industrial practice it is often necessary to predict the interfacial tensions of phase-separated liquid mixtures. This research project address the interfacial tensions in two-component mixtures. The effective attraction between two nonpolar, hydrophobic molecules in a water solution is a fundamental and much studied phenomenon in physical chemistry and biology. A recently proposed model suggests an inverse relation between the range and strength of the hydrophobic attraction, and this work will extend that model to higher dimensions and include more "water-like" solvent behavior. Collaborative work with experimentalists will analyze results on mixed colloids and polymers.