Wormlike micelles: Visualization and Rheology

We are interested in the study of structure, equilibrium behavior, and rheology of fluids with embedded long linear and flexible or nonflexible threadlike supramolecular structures. Trapping and manipulation of single particles and molecules studies have gained insight into the behavior of biomolecules, as well as isolated polymers in simple flows. Hydrodynamic trapping is a useful tool based on the hydrodynamic forces that capture particles or cells using the fluid flow at stagnation points generated in microfluidic devices. In this way, we intend to develop a microfluidic device for achieving an elongational flow to be imposed to the fluid embedded with tubular micelles. This would allow observation of marked tubular polymer micelles with a fluorescent dye using a confocal microscopy. The other systems of our interest are carbon nanotubes that also represent threadlike supermolecular structure. The aim of this work is to obtain stable dispersions of single carbon nanotubes using polyacrylic acid that has viscoelastic properties. The organization within these supramolecular structures will depend on a complex interplay of molecular geometry, amphiphilic character, and charge of all the involved molecules in the supramolecular structures. Many factors can modify this interplay as polyelectrolyte concentration, pH, temperature, and ionic strength of the media. We intend to investigate the effect of pH and ionic strength on the microstructure of the carbon nanotubes stabilized with polyacrylic acid.