The adage “oil and water don’t mix” underlies many phenomena of the aqueous environment, including surfactant assembly, folding of globular proteins, biological membrane formation, and the fate of pollutants in nature. If one examines the interaction of hydrophobic/non-polar substances with water more closely, however, one sees that the actual situation is more subtle. For example, many soluble proteins are globular at one temperature but unfold upon both heating and cooling. Simpler examples are the solubilities of inert gases and non-polar oils in water that exhibit solubility minima with increasing temperature, attributable to thermodynamic signatures characteristic of hydrophobic hydration. The application of pressure, on the other hand, can mollify the hydrophobic driving forces for assembly and denature proteins, while surfactant micelles exhibit maxima in their critical micelle concentrations with pressure, indicative of significant volumetric differences with protein folding. The distinctions between water and organic solvents are generic and are a central puzzle of hydrophobic hydration.
Dr. Hank Ashbaugh obtained his Bachelor’s of Chemical Engineering at North Carolina State University in 1992. He subsequently obtained his PhD in Chemical Engineering in Chemical Engineering from the University of Delaware in 1998 on the thermodynamics of surfactant hydration under the direction of Profs. Mike Paulaitis and Eric Kaler. After postdoctoral appointments at Lund University in Sweden, Princeton University, and Los Alamos National Laboratory, Hank joined the Chemical and Biomolecular Engineering at Tulane University in 2004 as an Assistant Professor, as was appointed to the rank of Associate Professor in 2010. Hank’s research interests include the multiscale simulation and theory of self-assembly and hierarchical organization in complex fluids including surfactant solutions, polymer melts and solutions, and biopolymer gels and networks to advance self-assembly as a labile tool for building tailored nanostructured materials.
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