CBE Seminar: Dr. Safa Jamali

“Microstructure-Rheology Relationship in Complex Fluids: Towards Design of Soft Materials with Tunable Properties”

Complex fluids are a wide class of materials which exhibit unusual mechanical responses to an applied stress or strain. In virtually all complex fluids, this rich and unusual mechanical response originates from a microstructure that responds to different applied stresses or strains in specific and varied ways; Thus understanding the microstructure – macroscopic behavior relationship is a crucial step for systematically designing complex fluid materials for novel applications. Although we have seen a tremendous progress towards employing different techniques for tuning the properties of nano-particle systems, most of these techniques have failed to materialize, due to a large gap between our scientific understanding at the micro-scale and collective physics and dynamics of particles at larger scales. I will present a computational approach based on statistical mechanics and preserving proper hydrodynamics to study physics and dynamics of particulate systems in and far from equilibrium.

I will begin with the well-known non-Newtonian behavior observed in dense colloidal systems, Shear-Thickening. I will discuss the role of hydrodynamics, friction and particle geometry/deformability in dense and crowded environments. I will then discuss the role of microstructural evolutions and structural heterogeneities in defining the macroscopic properties of a self-assembled network of attractive particles: A distinct hallmark of attractive Brownian particles, even at small and intermediate concentrations, is their ability to self-assemble into percolated networks that span over the sample size. These structures show a rich time and rate dependent response to applied deformation/forces such as yielding, shear banding, microphase separation, etc. Finally, new methods for bottom-up design of materials using colloids as primary building blocks will be discussed.

Seminar Flyer_Safa Jamali