Professor Kenneth Schweizer Seminar, Tuesday, 11/18/2025

Tuesday, 11/18/2025
2:00 PM
Steinman Hall, #312

Professor Kenneth Schweizer

University of Illinois, Materials Science and Engineering

“Using Microscopic Statistical Mechanical Theory to Understand the Slow Dynamics and Nonlinear Rheology of Dense Glass and Gel Forming Colloidal Suspensions”

ABSTRACT

The richness of mechanically-driven nonequilibrium phenomena in soft matter is remarkable and highly relevant to materials applications. I will describe our bottom up efforts to build predictive microscopic theories at the level of interactions and particles within a microrheological framework with memory. The enabling foundation is a fundamental description of quiescent activated structural relaxation, elasticity, and kinetic arrest of dense fluids into amorphous solids (glasses, gels). The unifying concept is a dynamic free energy that determines effective forces and stresses, transient particle localization, and activation barriers which are casually related to structure and evolve strongly with external stress, strain, and shear rate. Predictions for the transient and steady state rheology of repulsive and attractive dense colloidal suspensions under continuous step rate deformation will be described with an emphasis on single, double, and plastic-like yielding, and the coupled stress and structural nonequilibrium recovery dynamics after cessation of deformation. New directions aimed at building microscopic physics based theories for recovery rheology, including large amplitude oscillatory and creep protocols, will be sketched.

BRIEF ACADEMIC/EMPLOYMENT HISTORY:

Ken received a PhD in physics from Illinois in 1981. After a postdoc at Bell Labs, he joined the Materials Directorate at Sandia National Laboratories as a staff member. In 1991 he moved to back to Illinois where he is the Morris Professor of Materials Science, Professor of Chemistry and of Chemical Engineering, and a member of the Materials Research Laboratory.

MOST RECENT RESEARCH INTERESTS:

Development and application to understand experiment of predictive and integrated statistical mechanical theories of the structure, slow dynamics, transport processes, and rheology of functional soft materials. This includes dense colloidal and nanoparticle suspensions, topologically-compacted ring polymer melts, transient and permanent polymer networks, molecular diffusion and ionic conduction in polymeric media, and diverse fundamental phenomena controlled by activated relaxation in deeply supercooled liquids.