College Park, Maryland June 6 - 10 , 2004 |
W2-B2 (2:00 PM): Structural Characterization and Solution Behavior of Polymerized Rod-like Surfactant Micelles
Michael J. Gerber, Lynn M. Walker (Department of Chemical Engineering, Center for Complex Fluids Engineering, Carnegie Mellon University, Pittsburgh PA)
The polymerization of elongated micellar structures offers a novel approach to the production of high aspect ratio, water-soluble amphiphilic nanorods. A cationic surfactant is used as a template to polymerize a vinyl-containing counterion, cetyltrimethylammonium 4-vinylbenzoate (CTVB) based on procedures presented by Kline (Kline, S. R., Langmuir 15:2726 1999). The surfactant-polyacid aggregate that forms results in high aspect ratio nanoparticles. In this work, the influence of initiator concentration on particle length and structure is characterized. Small angle neutron scattering and light scattering are combined to characterize the dimensions and the solution behavior of the polymerized aggregates. Scattering provides evidence that the aggregates have a net negative charge, explaining their solubility and stability. NMR studies reinforce this observation and indicate that the surfactant is able to dissociate while the polymerized counterion is trapped in the aggregate. Finally, GPC of the polymer extracted from the aggregates indicates that approximately 2 chains are immobilized in each aggregate. Results demonstrate our ability to control aggregate dimensions and properties. This procedure offers an inexpensive and simple approach to generate nanorods with a diameter of 4nm and aspect ratios ranging from 20 to 60.
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