Linda (Lee) Magid Professor Organic Chemistry Neutron scattering; micellar systems B.S., Rice University (1969) Ph.D., University of Tennessee (1973)
E-mail: lmagid@mail.chem.utk.edu Representative publications   ·   Biographical sketch

Research

We study the structure and dynamics of supramolecular assemblies (micelles, microemulsions) formed by amphiphilic molecules in water-rich and oil-rich media. Micellar and microemulsion aggregates may be spherical, disclike or long, flexible (wormlike) cylinders; control of the aggregate morphology is possible by varying the molecular structure of the monomeric amphiphiles, among other variables. Analogies between the behavior in aqueous solution of wormlike micelles and polyelectrolyte chains are also investigated. For example, micelles of cationic surfactants like alkyl trimethylammonium salts and the structurally related cationic polyelectrolyes called ionenes show changes in flexibility as their charge-neutralizing anions - called counterions - change from halides to aromatic anions like carboxylates or sulfonates. In surfactant microemulsions and in lamellar liquid crystals, more extended sheetlike (membrane-like) structues are also observed. For those systems we are interested in relating their two-dimensional bending moduli to the corresponding one-dimensional bending moduli of wormlike micelles.

Surfactant assemblies are used in detergents, in a variety of personal-care products, in timed-released drug delivery, as drag reducers and in the enhanced recovery of petroleum. The techniques used to elucidate microstructure include small-angle scattering (including static and dynamic light scattering, static and dynamic neutron scattering - also called neutron spin echo spectroscopy), neutron reflectometry, conductimetry, rheological measurements and multinuclear NMR. We also have a program to synthesize new surfactants, and to prepare selectively deuterated surfactant molecules, counterions and polyelectrolytes for use in our neutron scattering and NMR work.

SANS, reflectometry and neutron spin echo experiments are done at Oak Ridge National Laboratory's High Flux Isotope Reactor, at NIST's Center for Cold Neutron Research and at SINQ (Switzerland). Spectrometers at ISIS (UK), ILL (France), IPNS (Argonne) and HFBR (Brookhaven; no longer available) have also been used in the past. Our work is currently supported by the National Science Foundation.

Representative publications

Flexibility of elongated sodium dodecylsulfate micelles in aqueous sodium chloride: a small-angle neutron scattering study. L.J. Magid, Z. Li, and P.D. Butler, Langmuir 16, 10028 (2000).

Tuning the contour lengths and persistence lengths of cationic micelles: the role of electrostatics and specific ion binding. L.J. Magid, Z. Han, Z. Li, and P.D. Butler, J. Phys. Chem. B 104, 6717 (2000).

Tuning microstructure of cationic micelles on multiple length scales: the role of electrostatics and specific ion binding. L.J. Magid, Z. Han, Z. Li, and P.D. Butler, Langmuir 16, 149 (2000).

Biographical sketch

Professor Magid completed her B.S. degree in chemistry at Rice University in 1969 and received her Ph.D. in chemistry from the University of Tennessee in 1973. She joined the chemistry faculty at Tennessee in 1973 and attained the rank of full professor in 1987. She held an NSF Visiting Professorship for Women at the University of Minnesota in 1986-87, and she has held several short-term research appointments at other institutions, including Oak Ridge National Laboratory, ETH-Zurich, and the Max Planck Institut, Gottingen.

Dr. Magid served as Associate Dean for Research in the College of Arts and Sciences from 1987 to 1990, and as Executive Assistant to the Chancellor, 1990-91; she was Vice-President for Research and Graduate Studies at the University of Kentucky from 1991 to 1994. She is the University's ORNL/SNS Liaison for Science and Technology and the Acting Director of the UT/ORNL Joint Institute for Neutron Sciences.