Main areas of research Environmental Chemistry Surface Chemistry Electrochemistry Chromatography Organized Molecular Assemblies Biological Nanostructures Chemical Education

Last Modified: 12:00 PM, Mon Mar 29, 1999

Interfacial Solvent Structure at Organic Surfaces
Characterization of Self-Assembled Monolayer (SAM) Structures

Self-assembled monolayers (SAMs) formed by the adsorption of n-alkanethiols onto Ag and Au surfaces have received intense interest in recent years in studies of fundamental interfacial behavior including adhesion, wetting, molecular recognition, and as the basis for novel microstructured organic materials and devices. The formation of monolayer films from organosulfur precursors allows for the construction of interfaces with defined structures and properties. These films form spontaneously upon immersion of the metal substrate into dilute solutions of a thiol-containing compound. The large interest in these particular adsorbate-substrate systems stems from the high degree of structural definition, composition, and thickness afforded by these adsorbates as organic interfaces. For example, a CH3 - terminated alkanethiol film represents a non-polar surface while a HO-terminated alkanethiol film represents a more polar surface. By varying the chemical nature of the terminal functional group, one can observe changes in the wettability, film order, and solvent interactions that can be correlated with the molecular structure of the interface.

Molecular Structure of Surfactants at the Air-Water Interface
Surface Enhanced Raman Spectroscopy (SERS)

Surfactants play a major role in nearly every aspect of our daily lives. From their obvious roles in soaps and detergents to their less obvious role in the enhancement of oil recovery and in metal ore processing, surfactants play key roles in each process. A recent Chemical and Engineering News (Feb 1, 1999 pp 35-48) contained a product report on surfactants. The report indicated that 5.14 billion pounds of surfactants were manufactured in the US alone in 1997. Of this amount, 60% was consumed as household or industrial cleaning products. One would think that with such widespread use, a firm understanding of the chemical/ molecular basis for surfactant function would be known, but this is not the case. In fact, a molecular picture of surfactant behavior at the air-water interface and correlations between the molecular structure and physical manifestations such as decreases in surface tension remain.