Complex Fluids With Extended, Rigid Components

Louisiana State University, Baton Rouge LA

Investigators

Abstract

The project will lead to improved understanding of entanglements and tenuous structures in complex fluids containing rigid components. It will include a study of the rotation and translation of rigid rods in entangling and non-entangling polymer solutions. The model system here is composed of tobacco mosaic virus and linear or globular dextran. Related experiments concern diffusive transport in liquid crystals, emphasizing synthetic polypeptides of variable length to determine the effects of flexibility. Characterization of poly(stearylglutamate in dodecane will illuminate the unique properties of this, perhaps the simplest of all reversible gels. Studies of self-assembling, two-directional arborols will emphasize basic properties such as stability. Equally important are the mechanisms by which the self-assembly can be controlled. Techniques include static and dynamic light scattering, fluorescence photobleaching recovery, pulsed field gradient NMR spectroscopy, and to-be-developed birefringence methods. Complex fluids with rigid, extended components are important precursors to high-strength fibers and films. They also pose very challenging fundamental questions, such as the nature of entanglements. The experiments will provide the observations to support theoretical developments elsewhere, creating together the underpinnings for rational design and processing of better materials. Good chances for serendipitous discovery exist, particularly in the self-assembling arborols, which show preliminary signs of unusual long-range structures. Potential applications include diffraction gratings and other optical devices, superior stationary phases for enhanced throughput in analytical separations, and more efficient systems for control of polymer/colloid stability, which is important in environmental remediation and nanofabrication. Students and others will work in an atmosphere that blends classroom and practical laboratory education with fundamental research and partnership with industrial and other off-campus scientists.