Attend CHME seminar today

Dr. Sara Hashmi
Dr. Sara Hashmi

The Department of Chemical and Bimolecular Engineering invites CSE students to attend a research talk by Dr. Sara Hashmi of Yale University on Wednesday, March 13.

Dr. Sara Hashmi
Associate Research Scientist, Director of the Facility for Light Scattering
Department of Chemical & Environmental Engineering Yale University

Wednesday, March 13, 2019
11:30 a.m.–12:30 p.m. | Othmer Hall Room 205 *Refreshments provided

Talk Title: "From Molecules to Meters: Linking Length Scales in Complex Fluids"

Abstract: Complex fluids are everywhere: suspensions, emulsions, dispersions,foams. A few examples in daily life include cosmetics, pharmaceuticals, cleaning supplies, some food products, and most biological materials. A common theme among these everyday materials: characteristics and dynamic properties on the macroscopic scale arise from microstructure and constituent properties on the nano- and microscale. Using asphaltenes as a case study, I will present an in-depth study of the influence of nanoscale properties on bulk suspension characteristics. Asphaltenes, naturally occurring molecules found in petroleum fluids, can cause clogging in even the largest pipelines. A combination of molecular and colloidal scale measurements reveals the impact of asphaltene molecular assembly andnanoparticle surface chemistry on aggregation dynamics. The aromaticchemistry of asphaltenes, combined with trace heteroatomic and metal content, imbues asphaltene nanoparticles with surface charge. Given the non-polar nature of alkanes and other petroleum constituents, charged moieties readily destabilize, aggregate, and phase separate out of solution. At the same time, electrostatic forces in oil are long-range, enabling repulsion between like-charged nanoparticles. Controlling nano- and micro-scale features of asphaltenes using surfactant additives enables control over asphaltene self-assembly and bulk suspension dynamics. In particular, we will see how colloidal surface charge, growth and aggregation influence macroscopic dynamics of asphaltene sedimentation and deposition in lab-scale pipelines. Future investigations in my lab will both tune particulate properties to control complex fluid dynamics on the macro-scale, and design fluidic sensors to detect and diagnose microscale phenomena for a variety of applications.

Biography: Sara M. Hashmi is an Associate Research Scientist in the Department of Chemical & Environmental Engineering at Yale University, and the Director of the Facility for Light Scattering, which provides instrumentation to investigate structure and dynamics in a variety of materials. Before establishing the Facility, Dr. Hashmi completed postdoctoral research on colloidal phenomena in petroleum fluids. Dr. Hashmi received her Ph.D. from the Yale Department of Chemical & Environmental Engineering, investigating the flow of soft particle suspensions in microchannels, and completed her Bachelors in Physics from Harvard University. Before graduate school, she spent a research year studying calcite crystal self-assembly at interfaces, during which time where she discovered her interest in soft materials and complex fluids found in and inspired by everyday phenomena.