THE LEVICH INSTITUTE ANNOUNCES THE FOLLOWING SEMINAR

Tuesday, 10/31/2000 4:00 PM Steinman Hall, Room #1M-22 Professor Norman Wagner University of Delaware, Chemical Engineering Department,Center for Molecular and Engineering Thermodynamics "Polyampholyte & Polymer Stabilization of Colloids and the Rheological Consequences"

ABSTRACT

In his 1857 Bakerian lecture, Michael Faraday described a comprehensive experimental investigation into the optical properties of colloidal gold sols and films obtained from such sols. In the first part of this lecture, we exploit Faraday’s investigations and use plasmon surface resonance to quantitatively measuring the kinetics of biopolymer adsorption onto colloidal nanoparticles in solution.

In the second part of this lecture, we examine the rheological consequences of adsorption of polyampholytes and nonionic polymers onto colloidal dispersions. The adsorption thermodynamics and adsorbed layer structure is quantified and the influence of this adsorbed layer on both perikinetic and othokinetic aggregation as well as on dispersion rheology are studied. Small angle neutron scattering, dynamic light scattering, and intrinsic viscometry are used to determine the structure and extent of the adsorbed layer. SANS and rheology are also used to independently probe the interparticle potential resulting from the adsorbed gelatin layer. The rheological consequences of adsorbed polymer on the high shear rheology of dense suspensions is elucidated and understood within a balance of colloidal and hydrodynamic forces.

BRIEF ACADEMIC/EMPLOYMENT HISTORY:

• Professor, University of Delaware, 5-99 to present
• Center for Molecular and Engineering Thermodynamics, 5-95 to present
• Fulbright Senior Scholar, Guest Professor-Dept. of Physics, University of Konstanz, Konstanz, Germany (8/97-1/98)
• Guest Professor-Institute for Polymer Physics, Swiss Federal Institute of Technology (ETH), Zürich, Switzerland (1/97-6/97)
• Associate Professor, Department of Chemical Engineering University of Delaware, 5-95 to 5-99
• Assistant Professor, Department of Chemical Engineering University of Delaware, 1-91 to 5-95

RECENT RESEARCH INTERESTS:

Rheology of liquid crystal polymers and blends, Rheo-optics, Microstructure and properties of colloidal suspensions, Statistical mechanics and parallel simulation of complex fluids and polymer membranes, small angle neutron scattering


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