Levich Institute Seminar Announcement, 10/12/2004

Tuesday, 10/12/2004
2:00 PM
Steinman Hall, Room #312
(Chemical Engineering Conference Room)

Professor Srinivasa Raghavan
University of Maryland
Department of Chemical Engineering


"New Classes of Viscoelastic Fluids and Gels Formed via Molecular Self-Assembly"


[This is a CCNY/Columbia NSF-IGERT Soft Materials seminar]

ABSTRACT

This presentation will revolve around self assembled viscoelastic fluids being investigated in my group. I will focus on two interesting systems. In the first system, unilamellar vesicles (ca. 100 nm in diameter) are present in the fluid at room temperature. Upon heating, these vesicles transform into wormlike micelles (i.e., flexible, polymer-like chains, several microns in contour length). Consequently, there is a 1000-fold increase in the zero shear viscosity with increasing temperature. The second system is a mixture of vesicles and an associating polymer, i.e., a polymer with a hydrophilic backbone and hydrophobic side-chains. In this case, the addition of polymer transforms the sample from a Newtonian fluid to an elastic gel. We have used small-angle neutron scattering (SANS) and cryo-microscopy to elucidate the microstructure in the gel. The gel is likely to consist of a three-dimensional network of vesicles bridged by polymer chains, with the hydrophobes on the polymer bound to the vesicle bilayer.

BRIEF ACADEMIC/EMPLOYMENT HISTORY

  • 1988-1992 B. Tech, Chemical Engineering, IIT Madras, India
  • 1992-1998 Ph.D., Chemical Engineering, NC State Univ. (advisor: Saad Khan)
  • 1998-2001 Postdoc, University of Delaware (with Eric Kaler)
  • 2001-present Asst. Prof., Chemical Engineering, Univ. of Maryland, College Park

CURRENT RESEARCH

The science of "soft" matter (polymers, colloids, liquid crystals) Self-assembled systems (micelles, vesicles, bilayers) Light and neutron scattering, rheology