Chemists have discovered details about how the tadpole-shapedmolecules found in many soaps and detergents bury their heads into thetop-most surface of water, an insight expected to yield benefits suchas better methods for cleaning up environmental hazards. The findingsof a team led by University of Oregon chemist Geri Richmond arefeatured on the cover of the Sept. 8 issue of the Journal of PhysicalChemistry B.
"We have developed a method to determine the tiltand twist angles of these molecules at the surface, a characterizationthat is important for understanding how they might function in variouspractical applications," Richmond said. "This is a general approachthat has broad implications for a variety of chemically andbiologically important applications."
"With the head groups ofthese molecules happy to be surrounded by water molecules at the watersurface and their tails preferring to stick up out of the water,extending into the air or an adjacent oily layer in the case of an oilslick," Richmond explained, "such molecules known as surfactants aresome of the most pervasive and useful chemicals in the world, found inproducts ranging from motor oil to cosmetics. They are also keyingredients for environmental clean-up and oil recovery."
Thework by Richmond, Dennis Hore, Daniel Beaman and Daniel Parks providesa picture of how these surfactant molecules orient at an aqueoussurface. Theirs are the first studies to determine the detailedorientation of simple soap head groups at the water surface, using aunique combination of laser-based experiments and computer modeling.These studies add important new insights into ongoing studies in theRichmond laboratory that seek to understand how these surfactant headgroups change the properties of water at aqueous surfaces.
Richmond'sresearch on surfaces and interfaces, funded by the Department ofEnergy, the National Science Foundation (NSF) and the Office of NavalResearch, involves laser-based techniques and is related to biologicalprocesses, semiconductor processing and environmental clean-up efforts.At Oregon since 1985, she is the Richard M. and Patricia H. NoyesDistinguished Professor of Chemistry and a member of the university'sMaterials Science Institute. She founded the Committee on theAdvancement of Women Chemists (COACh), sponsored by the NationalScience Foundation, National Institutes of Health and the Department ofEnergy.
Hore is a postdoctoral associate and Beaman is a graduatestudent in the Richmond laboratory. Parks contributed as a visitingNSF-sponsored Research Experience for Undergraduates student fromWhitman College.
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