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Complex Fluids and Nanomaterials Group

Types of Materials We Study

Applications of Interest to Us

Self-Assemblies of Amphiphiles

Our primary interest is in the self-assembly of surfactant and lipid molecules in water or organic solvents. Self-assembly refers to the spontaneous organization of the molecules into nanoscale structures such as spherical or wormlike micelles (long, flexible chains), vesicles and liposomes (container structures), helical tubules and gel networks. The ability to tune self-assembly using external stimuli such as light, pH or temperature is of particular interest.

Polymers & Biopolymers

Polymers and biopolymers are integral components of our research. We are studying the self-assembly of amphiphilic polymers in conjunction with biological cells. Polymer hydrogels (networks of chains swollen with solvent) and capsules are being synthesized at both micro and nano scales using bulk or microfluidic methods. Polymeric materials are frequently comibined with nanoparticles to form nanocomposites that can have unique properties.

Colloids & Nanoparticles

A range of micro- and nano-sized particles are used in our studies. Nanoplatelets or nanodiscs of clay, as well as carbon nanotubes and nanofibers are used to make polymer nanocomposites. Nanoparticles are being synthesized by templating or self-assembly methods and they are being tailored to include MRI contrast agents or biological surface ligands. Assembly of particles into larger-scale structures under the guidance of external stimuli such as light is also being studied.

Drug Delivery, Nanomedicine, Sensors

We are developing pH, light, or temperature-responsive "smart" gels, capsules, and self-assemblies for the controlled and triggered delivery of drugs, proteins, or cosmetics. Nanoparticles are being developed for use in MRI-imaging of cancer tumors. Thermogelling or photogelling "smart" fluids are under investigation for use in fire-fighting and in microfluidic sensors and valves. Superabsorbent hydrogels are being employed as temperature sensors. Vesicle-coated polymers are being studied as "smart" surfaces for biological assays.

Biomaterials, Biomimetic Systems

In conjunction with Remedium Technologies, we are developing a new class of hemostatic bandages and sprays, i.e., materials that can rapidly arrest bleeding from serious wounds. Vesicle-bearing polymer films are being studied as advanced dressings for treating chronic wounds. Composites of amphiphilic polymers and carbon particles are being evaluated as bio-lubricants. We are also constructing biomimetic soft microrobots that can either be actuated by external fields or can propel themselves in water upon exposure to a chemical fuel source.

Materials for Oil Recovery, Environmental Clean-Up, Energy Storage

Viscoelastic fluids based on wormlike micelles are being designed for use in hydraulic fracturing operations, a key step in tertiary oil recovery. New types of dispersants and phase-selective gelators are being developed for application in the clean-up of oil spills. We are also working on a variety of materials for energy applications, including new electrolytes and electrodes for use in rechargeable lithium-ion batteries or in flow batteries.

Experimental Techniques that We Use Frequently

Used for characterizing
the mechanics of soft,
viscoelastic materials
and complex fluids.

Light Scattering
Used to measure the
sizes and interactions of nanostructures, typically in dilute solution.

Neutron Scattering
Used to elucidate the interactions, sizes, and
shapes of nanostructures
(done at NIST NCNR).

Used to directly image structures at the micro-scale (by optical microscopy) or the nano-scale (by cryo-TEM).

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© 2007 Srinivasa Raghavan |
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