475750 Microstructure-Rheology Relationship in Complex Fluids:Towards Design of Soft Materials with Tunable Properties

Sunday, November 13, 2016
Continental 4 & 5 (Hilton San Francisco Union Square)
Safa Jamali, Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA

Research Interests:

The field of complex fluids encompasses 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 stress or strain 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. The complex fluid landscape can be subdivided based on the particle-level interactions that govern their underlying microstructure and the resulting macro rheology:

In my graduate research work under supervision of Prof. Joao Maia (Case Western Reserve University) and in collaboration with Prof. Norman Wagner (University of Delaware), I studied the interplay between the microstructure and mechanical response of repulsive and neutral (so-called hard spheres) concentrated suspensions, with emphasis on Shear-Thickening behavior, where viscosity of a dense suspension progressively increases with increasing the applied rate of deformation. To do so, I developed a mesoscale simulation scheme, based on Dissipative Particle Dynamics method, providing a platform that enables us to study the crucial role of multi-body long and short range hydrodynamic effects, frictional interactions between the constituents, particle deformability, and particle anisotropy.

During my postdoctoral research work with Prof. Robert Armstrong and Prof. Gareth McKinley (MIT), I studied the role of microstructural evolutions of attractive systems in defining their macroscopic rheological response. I established a quantitative correlation between the microstructural measures of a system, to flow properties and heterogeneities observed in complex fluids. We showed that steady state properties, as well as transient phenomena at various time scales can be explained through detailed study of the microstructure. Furthermore, we proposed a Time-Peclet-Transformation (TPT) procedure with regards to their fundamental interactions and flow properties/history. This provides a phase map for the attractive systems such as nano emulsions and colloidal gels, prescribing novel design tools for complex fluids with modified and tunable properties.

By exploring the microstructure-rheology relationship for a wide range of complex fluids, and connecting this knowledge to electrochemical processes, my future research will focus on finding new routes for designing soft materials with tunable properties, with emphasis on applications in flow batteries and water desalination technologies.

Teaching Interests:

Will be presented upon request.

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