Levich Institute Seminar Announcement, 09/20/2005

Tuesday, 09/20/2005
2:00 PM
Steinman Hall, Room #312 (Chemical Engineering Conference Room)

Professor Lynn M. Walker
Carnegie Mellon University
Department of Chemical Engineering


"Formation of Rod-like Polyelectrolyte-Surfactant Aggregates: Synthesis, Structure and Rheology "

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

ABSTRACT

Surfactants spontaneously form structures, or micelles, in aqueous solution. Through appropriate choice of surfactant chemistry, the formation of cylindrical, or wormlike, micelles with radii of a few nanometers is possible. The rich dynamics of these wormlike micelles are analogous to semi-dilute polymer solutions but have additional relaxation mechanisms due to the aggregate nature of the micelles. Through polymerization of the anionic counterions in our system, we generate water-soluble, rodlike, amphiphilic, polyelectrolyte-surfactant aggregates. The diameter of the aggregates is defined by the tail-length of the surfactant while the length is controlled through the polymerization conditions, specifically the initiator concentration and decomposition time. The resulting nanoparticles have properties very different from the initial template. We have shown that these aggregates adsorb irreversibly at liquid-solid interfaces allowing for potential templating applications, form liquid crystalline phases at high concentration, and do maintain their amphiphilic nature even after polymerization.

BRIEF ACADEMIC/EMPLOYMENT HISTORY
  • PhD, Dept. of Chemical Eng., University of Delaware, Newark DE (March 1995)
  • BS, Dept. of Chemical Eng., University of New Hampshire, Durham NH (May 1990)
  • Associate Professor, Department of Chemical Eng., Carnegie Mellon University, Pittsburgh PA (2002- )
  • Assistant Professor, Dept. of Chemical Eng., Carnegie Mellon University, Pittsburgh PA (1997-2002)
  • Postdoctoral Fellow, Katholieke Universiteit Leuven, Leuven Belgium (1995 - 1996)

CURRENT RESEARCH INTERESTS:


Quantifying the coupling between flow behavior and flow-induced structure in complex fluids; Self-Assembled structures and Interface-dominated flows of viscoelastic solutions.