Materials Assembly – A complex route to merging nano- and micro- length scales

Tuesday, January 26, 2010 – 3:15pm
Reiss 502
Kimani Stancil, Assistant Professor
Howard University, Department of Physics

Nanocrystal syntheses typically require complex surfactant mixtures that at high temperatures play host to nucleating monomer clusters that subsequently grow and/or ripen. The resulting nanoparticles with ligand passivated surfaces defy aggregation in the presence of excess surfactant, polymers, or physical gel resulting from their pre-mixture components. For individual nanoparticle manipulation, excess material must be removed or does it? Before ‘cleaning’ semiconductor nanorods, compositions of gel by-product and nanoparticle provide an elastic environment for optically sensitive nanorods. By using SAXS, these nano-composites are shown to exhibit nematic liquid crystalline textures due to nanorod alignment within the gel. The early aims of the Stancil research group at Howard University are to combine the knowledge gained from lyotropic nanorod assembly, with the phase-behavior of heteropolymer gels as a quantitative route to establishing novel optically sensitive materials. Our early steps will utilize Dr. Stancil’s work with drying assembly of CdSe nanorods on large or um scales (confirmed by SAXS) for patterned and unpatterned substrates. In addition, we consider influences on a gel’s volume phase behavior that may provide insight into complex nanoparticle gel compositions.

Host: Edward Van Keuren
Discussion Leader: Edward Van Keuren